Topics

Preventing escaping gases #technology #tlud


Susan
 

Scenario...   burn brush in a 20 to 30ft long half tank, cut lengthwise, then roll the tank over and put dirt along it to prevent escaping smoke and gases.  The charring process would continue for several days.  

How successful do you think our efforts to prevent polluting gases and smoke escaping would be?

Susan


Nando Breiter
 

Susan,

The issue is that pyrolysis gases will take up vastly more space than the same atoms and molecules as solids, so pressure will quickly build up within the tank and the gases will have to go somewhere. 

Condensable gases may be trapped in the soil barrier if there is enough to cool them sufficiently to become liquids or solids before they escape. Non-condensables such as carbon monoxide, carbon dioxide and methane will escape into the atmosphere. If you see smoke leaking out, then that would be an indication that your soil barrier is not sufficient to condense them.

What you might consider is to create a small outlet for the gases at the end of the tank, and flare them off in an appropriately designed / jury-rigged burner.

If you are venting the gases and flaring them, and the brush consists of thin branches rather than thick tree trunks, I would assume that a batch would complete itself in hours rather than days. All that needs to happen is the heat generated needs to penetrate to the depth of each particle of biomass at temperatures over 300° C for the reaction to become exothermic. If the brush is really thin, then once you flip it over, pyrolysis will largely have already occurred and the char will simply need to cool in an oxygen starved environment under the half tank.

How thick are the branches of the "brush" you have available?




On Tue, Sep 8, 2020 at 6:16 PM Susan <suemegg@...> wrote:
Scenario...   burn brush in a 20 to 30ft long half tank, cut lengthwise, then roll the tank over and put dirt along it to prevent escaping smoke and gases.  The charring process would continue for several days.  

How successful do you think our efforts to prevent polluting gases and smoke escaping would be?

Susan


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


Susan
 

Nando,

Thank you fir your reply.

Unfortunately, due to the nature of our feedstock size is very variable.  We operate a compost site, and loads come in via car trunk loads, pickup trucks and full size dump trucks.  So we have from small bundles of twigs up to tree trunks.

The varying size makes for a longer time frame for charring the wood waste.

We had considered attempting to flare off the gas and burn it, hoping that would problematic escape of gases and smoke into the atmosphere.

Susan




On Tue, Sep 8, 2020, 4:04 PM Nando Breiter <nando@...> wrote:
Susan,

The issue is that pyrolysis gases will take up vastly more space than the same atoms and molecules as solids, so pressure will quickly build up within the tank and the gases will have to go somewhere. 

Condensable gases may be trapped in the soil barrier if there is enough to cool them sufficiently to become liquids or solids before they escape. Non-condensables such as carbon monoxide, carbon dioxide and methane will escape into the atmosphere. If you see smoke leaking out, then that would be an indication that your soil barrier is not sufficient to condense them.

What you might consider is to create a small outlet for the gases at the end of the tank, and flare them off in an appropriately designed / jury-rigged burner.

If you are venting the gases and flaring them, and the brush consists of thin branches rather than thick tree trunks, I would assume that a batch would complete itself in hours rather than days. All that needs to happen is the heat generated needs to penetrate to the depth of each particle of biomass at temperatures over 300° C for the reaction to become exothermic. If the brush is really thin, then once you flip it over, pyrolysis will largely have already occurred and the char will simply need to cool in an oxygen starved environment under the half tank.

How thick are the branches of the "brush" you have available?




On Tue, Sep 8, 2020 at 6:16 PM Susan <suemegg@...> wrote:
Scenario...   burn brush in a 20 to 30ft long half tank, cut lengthwise, then roll the tank over and put dirt along it to prevent escaping smoke and gases.  The charring process would continue for several days.  

How successful do you think our efforts to prevent polluting gases and smoke escaping would be?

Susan


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


Dick Gallien
 

Thanks Nando,
Sue is my wild Aussie wife, who claims I ramble.  Our goal is to save The Winona Farm by turning most of Winona's "waste wood" into biochar.  The City has burned about 2,000 mostly ash trees in the last 4 yrs.. They weren't going to burn anymore, but their compost site can't handle them, so they have about 400 trees stacked.
1. My plan, which Sue doesn't see how we can control the fumes, is to acquire a 10' dia. X 30' x 7/8" railroad tank with 1 factory end and another factory end welded on, since most are 60'.  Instead of cutting the tank in half lengthwise, I want to have a 6' wide piece taken off length wise, so the tank will roll more easily, the flame cap will be protected from wind and I can doze clay against the tank base, while hopefully with your suggestions, the acrid fumes of pyrolysis are eliminated.  Besides a huge pile of green wood chips and brush at The Farm, Winona will gladly dump hundreds of trees here.    

2.  In a few wks. we'll start loading the 10' dia X 30' X 7/8" rr vertical tank in a building, with brush and logs, which could pyrolosize for a couple months.  A 11' dia fuel tank top keeps the rain out, but unlike the horizontal tank, how can fumes be retorted or burned off, since the lid is far from air tight?
Thanks, Dick

Dick Gallien 
22501 East Burns Valley Road
Winona  MN  55987
dickgallien@...  [507] 312 0194
www.thefarm.winona-mn.us

Prison bars do the confining, allowing the prisoner a mental freedom not possible in schools, where an endless barrage of assignments, lectures, questions and tests, serve the same purpose, under the guise of education, while distracting as efficiently as the cracking of whips, keeping the imprisoned from discovering and pursuing their passions, or noticing that there are no real bars------and by the time they might realize the purpose of their confinement, it is too late.


On Tue, Sep 8, 2020 at 5:49 PM Susan <suemegg@...> wrote:
Nando,

Thank you fir your reply.

Unfortunately, due to the nature of our feedstock size is very variable.  We operate a compost site, and loads come in via car trunk loads, pickup trucks and full size dump trucks.  So we have from small bundles of twigs up to tree trunks.

The varying size makes for a longer time frame for charring the wood waste.

We had considered attempting to flare off the gas and burn it, hoping that would problematic escape of gases and smoke into the atmosphere.

Susan




On Tue, Sep 8, 2020, 4:04 PM Nando Breiter <nando@...> wrote:
Susan,

The issue is that pyrolysis gases will take up vastly more space than the same atoms and molecules as solids, so pressure will quickly build up within the tank and the gases will have to go somewhere. 

Condensable gases may be trapped in the soil barrier if there is enough to cool them sufficiently to become liquids or solids before they escape. Non-condensables such as carbon monoxide, carbon dioxide and methane will escape into the atmosphere. If you see smoke leaking out, then that would be an indication that your soil barrier is not sufficient to condense them.

What you might consider is to create a small outlet for the gases at the end of the tank, and flare them off in an appropriately designed / jury-rigged burner.

If you are venting the gases and flaring them, and the brush consists of thin branches rather than thick tree trunks, I would assume that a batch would complete itself in hours rather than days. All that needs to happen is the heat generated needs to penetrate to the depth of each particle of biomass at temperatures over 300° C for the reaction to become exothermic. If the brush is really thin, then once you flip it over, pyrolysis will largely have already occurred and the char will simply need to cool in an oxygen starved environment under the half tank.

How thick are the branches of the "brush" you have available?




On Tue, Sep 8, 2020 at 6:16 PM Susan <suemegg@...> wrote:
Scenario...   burn brush in a 20 to 30ft long half tank, cut lengthwise, then roll the tank over and put dirt along it to prevent escaping smoke and gases.  The charring process would continue for several days.  

How successful do you think our efforts to prevent polluting gases and smoke escaping would be?

Susan


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


Nando Breiter
 

If the lid is not relatively air tight, the pyrolysis gases will leak out everywhere. Keep in mind that as pyrolysis begins, the gases produced are going to expand exponentially compared to their solid form at biomass. So not only do you have the tendency for hot gases to rise working against you, you also have significant potential pressure differential between the inside and outside of the tank. 

Going back to Susan's idea to cut the tank lengthwise, even if you pack the base with a lot of clay, the non condensable gases are going to find their way out, by pushing the tank half up off the ground if need be. You could set it in a foundation of concrete and the gases would still escape. 

Even a small 55 gallon barrel kiln will develop a significant pressure differential, enough so that the burning gases escaping from a 3/8" hole in a tightly sealed lid will roar as they are burned, producing a large flare 6 feet high. 

So, I think Sue is right. I responded to her idea to roll a half tank over because it seemed interesting and viable. It might also work to position the half tank next to a long burn pile, and flip it over on the burn pile once the fire is sufficiently hot. That way the tank is much less heavy, and you might be able to position and wedge it nearly halfway rolled over so all it needs is a bit of a push. That said, I have no experience working with heavy equipment and tanks. Safety first.

Bottom line, to prevent gases, particularly methane, that have a higher greenhouse gas effect than CO2 from escaping to the atmosphere, they will need to be flared. Note also that CO is heavier than air, so it will tend to settle to the floor in an enclosed space. One breath of CO laden air is enough to render an animal or human unconscious and unless someone with an oxygen mask rushes in immediately to pull them out, death is certain. You wrote "In a few wks. we'll start loading the 10' dia X 30' X 7/8" rr vertical tank in a building"

Put it out in the open, no walls whatsoever, to allow the CO to drift away rather than accumulate. Carbon monoxide poisoning is a high risk for any enclosed pyrolysis device. It doesn't take much.

The flare produced from a half railroad car pyrolysis kiln would produce an impressive amount of heat. I'm reluctant to give armchair advice on how to jury rig such a burner. The right way to do it would be to find something lined with ceramic. If it were me in your shoes, I'd grab 2 55 gallon barrels and fashion a quick swirl burner from them so I could see how well the tank kiln worked. But I'd also be prepared that it would burn through, leaving a naked fireball at the end of the half tank. Given the potential pressure, I'd aim this end of the tank away from anything flammable, and stay well away if my provisional burner was glowing orange red. If I did not have a space without anything flammable nearby, I wouldn't try this without a properly engineered burner, particularly if I lived in an area at risk of wildfires. 

In Brazil, I've seen images of charcoal factories made of second hand shipping containers, a series of tubes, and a central second hand gas burner, which is of course lined with ceramic. The exhaust heat is piped out to the shipping containers, and the raw syngas produced is piped into the gas burner. It's a circular, round robin system. The shipping containers have doors on the end, making them convenient to load, unload, and close. While the seal may not be ideal, the large diameter exit tube near the top provides an ample escape route for most of the gases. 

Hope that helps.

Reminder #1: Don't put any experimental kiln in an enclosed space, even one without a proper roof. 

Bonus tip: Your first impulse may be to run towards your experimental kiln if you see something going wrong. You want to fix it! Don't do that. Take some steps back and carefully observe what is happening. Think things through. Develop a plan at a distance. Figure out if you can implement it safely. Be ready from the very beginning to let everything go wrong at a distance.

Dick, I know you may know these things already because of your experience, but am writing them for others, just in case.

Kind regards,

Nando


CarbonZero Sagl
CP 15
6999 Astano
Switzerland

+41 76 303 4477 cell / WhatsApp
skype: ariamedia




On Wed, Sep 9, 2020 at 3:11 AM Dick Gallien <dickgallien@...> wrote:
Thanks Nando,
Sue is my wild Aussie wife, who claims I ramble.  Our goal is to save The Winona Farm by turning most of Winona's "waste wood" into biochar.  The City has burned about 2,000 mostly ash trees in the last 4 yrs.. They weren't going to burn anymore, but their compost site can't handle them, so they have about 400 trees stacked.
1. My plan, which Sue doesn't see how we can control the fumes, is to acquire a 10' dia. X 30' x 7/8" railroad tank with 1 factory end and another factory end welded on, since most are 60'.  Instead of cutting the tank in half lengthwise, I want to have a 6' wide piece taken off length wise, so the tank will roll more easily, the flame cap will be protected from wind and I can doze clay against the tank base, while hopefully with your suggestions, the acrid fumes of pyrolysis are eliminated.  Besides a huge pile of green wood chips and brush at The Farm, Winona will gladly dump hundreds of trees here.    

2.  In a few wks. we'll start loading the 10' dia X 30' X 7/8" rr vertical tank in a building, with brush and logs, which could pyrolosize for a couple months.  A 11' dia fuel tank top keeps the rain out, but unlike the horizontal tank, how can fumes be retorted or burned off, since the lid is far from air tight?
Thanks, Dick

Dick Gallien 
22501 East Burns Valley Road
Winona  MN  55987
dickgallien@...  [507] 312 0194
www.thefarm.winona-mn.us

Prison bars do the confining, allowing the prisoner a mental freedom not possible in schools, where an endless barrage of assignments, lectures, questions and tests, serve the same purpose, under the guise of education, while distracting as efficiently as the cracking of whips, keeping the imprisoned from discovering and pursuing their passions, or noticing that there are no real bars------and by the time they might realize the purpose of their confinement, it is too late.


On Tue, Sep 8, 2020 at 5:49 PM Susan <suemegg@...> wrote:
Nando,

Thank you fir your reply.

Unfortunately, due to the nature of our feedstock size is very variable.  We operate a compost site, and loads come in via car trunk loads, pickup trucks and full size dump trucks.  So we have from small bundles of twigs up to tree trunks.

The varying size makes for a longer time frame for charring the wood waste.

We had considered attempting to flare off the gas and burn it, hoping that would problematic escape of gases and smoke into the atmosphere.

Susan




On Tue, Sep 8, 2020, 4:04 PM Nando Breiter <nando@...> wrote:
Susan,

The issue is that pyrolysis gases will take up vastly more space than the same atoms and molecules as solids, so pressure will quickly build up within the tank and the gases will have to go somewhere. 

Condensable gases may be trapped in the soil barrier if there is enough to cool them sufficiently to become liquids or solids before they escape. Non-condensables such as carbon monoxide, carbon dioxide and methane will escape into the atmosphere. If you see smoke leaking out, then that would be an indication that your soil barrier is not sufficient to condense them.

What you might consider is to create a small outlet for the gases at the end of the tank, and flare them off in an appropriately designed / jury-rigged burner.

If you are venting the gases and flaring them, and the brush consists of thin branches rather than thick tree trunks, I would assume that a batch would complete itself in hours rather than days. All that needs to happen is the heat generated needs to penetrate to the depth of each particle of biomass at temperatures over 300° C for the reaction to become exothermic. If the brush is really thin, then once you flip it over, pyrolysis will largely have already occurred and the char will simply need to cool in an oxygen starved environment under the half tank.

How thick are the branches of the "brush" you have available?




On Tue, Sep 8, 2020 at 6:16 PM Susan <suemegg@...> wrote:
Scenario...   burn brush in a 20 to 30ft long half tank, cut lengthwise, then roll the tank over and put dirt along it to prevent escaping smoke and gases.  The charring process would continue for several days.  

How successful do you think our efforts to prevent polluting gases and smoke escaping would be?

Susan


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


Nando Breiter
 

Susan, 

You might consider sorting the feedstock by size (cross-sectional thickness). Batch similar sizes together. It's like baking cookies. Bake all the same size together to ensure they are all baked to the same degree during a fixed amount of time they share together in the oven. If you bake bread and cookies together for the same amount of time, either the cookies will be burned or the bread underbaked. 

When you sort feedstock like this for a batch kiln, it ensures that the processing time is sufficient to transform it to char, while not excessively "baking" the smaller bits into gases. The large rounds might take a few days, the smaller branches a few hours. If the small branches are combined with the large rounds, they will be converted mostly to gases and ash. 

Kind regards,

Nando



On Wed, Sep 9, 2020 at 12:49 AM Susan <suemegg@...> wrote:
Nando,

Thank you fir your reply.

Unfortunately, due to the nature of our feedstock size is very variable.  We operate a compost site, and loads come in via car trunk loads, pickup trucks and full size dump trucks.  So we have from small bundles of twigs up to tree trunks.

The varying size makes for a longer time frame for charring the wood waste.

We had considered attempting to flare off the gas and burn it, hoping that would problematic escape of gases and smoke into the atmosphere.

Susan




On Tue, Sep 8, 2020, 4:04 PM Nando Breiter <nando@...> wrote:
Susan,

The issue is that pyrolysis gases will take up vastly more space than the same atoms and molecules as solids, so pressure will quickly build up within the tank and the gases will have to go somewhere. 

Condensable gases may be trapped in the soil barrier if there is enough to cool them sufficiently to become liquids or solids before they escape. Non-condensables such as carbon monoxide, carbon dioxide and methane will escape into the atmosphere. If you see smoke leaking out, then that would be an indication that your soil barrier is not sufficient to condense them.

What you might consider is to create a small outlet for the gases at the end of the tank, and flare them off in an appropriately designed / jury-rigged burner.

If you are venting the gases and flaring them, and the brush consists of thin branches rather than thick tree trunks, I would assume that a batch would complete itself in hours rather than days. All that needs to happen is the heat generated needs to penetrate to the depth of each particle of biomass at temperatures over 300° C for the reaction to become exothermic. If the brush is really thin, then once you flip it over, pyrolysis will largely have already occurred and the char will simply need to cool in an oxygen starved environment under the half tank.

How thick are the branches of the "brush" you have available?




On Tue, Sep 8, 2020 at 6:16 PM Susan <suemegg@...> wrote:
Scenario...   burn brush in a 20 to 30ft long half tank, cut lengthwise, then roll the tank over and put dirt along it to prevent escaping smoke and gases.  The charring process would continue for several days.  

How successful do you think our efforts to prevent polluting gases and smoke escaping would be?

Susan


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


Frank Strie
 

Well explained Nando,
There is also the possibility to additional, deliberate air injection onto the right spot of the process, above the glow zone.
Provided there is also some agitation for separation of brittle carbon from flexible carbon the pyrolysis / gasification process can be further optimised.
Observation and practical work go together to further develop the technology and procedure.
Thermal insulation conditions of the kiln vessel and preheating of the inflowing air also play a role.
All practical, productive fun.
Cheers from under Down Under, Spring is here.

 

From: main@Biochar.groups.io <main@Biochar.groups.io> On Behalf Of Nando Breiter
Sent: Wednesday, September 9, 2020 11:29 PM
To: main@biochar.groups.io
Subject: Re: [Biochar] Preventing escaping gases

 

Susan, 

 

You might consider sorting the feedstock by size (cross-sectional thickness). Batch similar sizes together. It's like baking cookies. Bake all the same size together to ensure they are all baked to the same degree during a fixed amount of time they share together in the oven. If you bake bread and cookies together for the same amount of time, either the cookies will be burned or the bread underbaked. 

 

When you sort feedstock like this for a batch kiln, it ensures that the processing time is sufficient to transform it to char, while not excessively "baking" the smaller bits into gases. The large rounds might take a few days, the smaller branches a few hours. If the small branches are combined with the large rounds, they will be converted mostly to gases and ash. 


Kind regards,

 

Nando

 

 

On Wed, Sep 9, 2020 at 12:49 AM Susan <suemegg@...> wrote:

Nando,

 

Thank you fir your reply.

 

Unfortunately, due to the nature of our feedstock size is very variable.  We operate a compost site, and loads come in via car trunk loads, pickup trucks and full size dump trucks.  So we have from small bundles of twigs up to tree trunks.

 

The varying size makes for a longer time frame for charring the wood waste.

 

We had considered attempting to flare off the gas and burn it, hoping that would problematic escape of gases and smoke into the atmosphere.

 

Susan

 

 

 

On Tue, Sep 8, 2020, 4:04 PM Nando Breiter <nando@...> wrote:

Susan,

 

The issue is that pyrolysis gases will take up vastly more space than the same atoms and molecules as solids, so pressure will quickly build up within the tank and the gases will have to go somewhere. 

Condensable gases may be trapped in the soil barrier if there is enough to cool them sufficiently to become liquids or solids before they escape. Non-condensables such as carbon monoxide, carbon dioxide and methane will escape into the atmosphere. If you see smoke leaking out, then that would be an indication that your soil barrier is not sufficient to condense them.

 

What you might consider is to create a small outlet for the gases at the end of the tank, and flare them off in an appropriately designed / jury-rigged burner.

 

If you are venting the gases and flaring them, and the brush consists of thin branches rather than thick tree trunks, I would assume that a batch would complete itself in hours rather than days. All that needs to happen is the heat generated needs to penetrate to the depth of each particle of biomass at temperatures over 300° C for the reaction to become exothermic. If the brush is really thin, then once you flip it over, pyrolysis will largely have already occurred and the char will simply need to cool in an oxygen starved environment under the half tank.

 

How thick are the branches of the "brush" you have available?

 

 

 

 

On Tue, Sep 8, 2020 at 6:16 PM Susan <suemegg@...> wrote:

Scenario...   burn brush in a 20 to 30ft long half tank, cut lengthwise, then roll the tank over and put dirt along it to prevent escaping smoke and gases.  The charring process would continue for several days.  

 

How successful do you think our efforts to prevent polluting gases and smoke escaping would be?

 

Susan


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


Hugh McLaughlin
 

Dear biochar.groups list,

I would like to present an alternative perspective:

I think this is a terrible idea, fraught with inherent dangers and and unanticipated responses by the equipment due to the scale. In addition, the biochar quality will be all over the place and virtually uncontrolled except for the few operators that can see through steel walls.

Because of the scale, it is implied that there will be "yellow iron" moving things around. I think it is much better suited to devote the same resources to digging a pit and work on a better method to seal the batch after it has burned to mostly char - basically a giant Kon-tiki. If necessary, flood it.

Alternately, modifying a Missouri Kiln to have exiting vapor capture and oxidation would probably give you a safe alternative. Moving large hot objects with combusting contents that can shift is just a bad idea which deserves a redesign.

- Hugh McLaughlin, PhD, PE
(I am a Chemical Engineer and we do lots of hazard reviews and reduction. It has taken the industry decades to realize that a stitch in time saves nine and foresight can identify the same scenarios as hindsight if the right questions are asked in advance.)

On Wednesday, September 9, 2020, 6:25:06 PM EDT, Frank Strie <frank.strie@...> wrote:


Well explained Nando,
There is also the possibility to additional, deliberate air injection onto the right spot of the process, above the glow zone.
Provided there is also some agitation for separation of brittle carbon from flexible carbon the pyrolysis / gasification process can be further optimised.
Observation and practical work go together to further develop the technology and procedure.
Thermal insulation conditions of the kiln vessel and preheating of the inflowing air also play a role.
All practical, productive fun.
Cheers from under Down Under, Spring is here.

 

From: main@Biochar.groups.io <main@Biochar.groups.io> On Behalf Of Nando Breiter
Sent: Wednesday, September 9, 2020 11:29 PM
To: main@biochar.groups.io
Subject: Re: [Biochar] Preventing escaping gases

 

Susan, 

 

You might consider sorting the feedstock by size (cross-sectional thickness). Batch similar sizes together. It's like baking cookies. Bake all the same size together to ensure they are all baked to the same degree during a fixed amount of time they share together in the oven. If you bake bread and cookies together for the same amount of time, either the cookies will be burned or the bread underbaked. 

 

When you sort feedstock like this for a batch kiln, it ensures that the processing time is sufficient to transform it to char, while not excessively "baking" the smaller bits into gases. The large rounds might take a few days, the smaller branches a few hours. If the small branches are combined with the large rounds, they will be converted mostly to gases and ash. 


Kind regards,

 

Nando

 

 

On Wed, Sep 9, 2020 at 12:49 AM Susan <suemegg@...> wrote:

Nando,

 

Thank you fir your reply.

 

Unfortunately, due to the nature of our feedstock size is very variable.  We operate a compost site, and loads come in via car trunk loads, pickup trucks and full size dump trucks.  So we have from small bundles of twigs up to tree trunks.

 

The varying size makes for a longer time frame for charring the wood waste.

 

We had considered attempting to flare off the gas and burn it, hoping that would problematic escape of gases and smoke into the atmosphere.

 

Susan

 

 

 

On Tue, Sep 8, 2020, 4:04 PM Nando Breiter <nando@...> wrote:

Susan,

 

The issue is that pyrolysis gases will take up vastly more space than the same atoms and molecules as solids, so pressure will quickly build up within the tank and the gases will have to go somewhere. 

Condensable gases may be trapped in the soil barrier if there is enough to cool them sufficiently to become liquids or solids before they escape. Non-condensables such as carbon monoxide, carbon dioxide and methane will escape into the atmosphere. If you see smoke leaking out, then that would be an indication that your soil barrier is not sufficient to condense them.

 

What you might consider is to create a small outlet for the gases at the end of the tank, and flare them off in an appropriately designed / jury-rigged burner.

 

If you are venting the gases and flaring them, and the brush consists of thin branches rather than thick tree trunks, I would assume that a batch would complete itself in hours rather than days. All that needs to happen is the heat generated needs to penetrate to the depth of each particle of biomass at temperatures over 300° C for the reaction to become exothermic. If the brush is really thin, then once you flip it over, pyrolysis will largely have already occurred and the char will simply need to cool in an oxygen starved environment under the half tank.

 

How thick are the branches of the "brush" you have available?

 

 

 

 

On Tue, Sep 8, 2020 at 6:16 PM Susan <suemegg@...> wrote:

Scenario...   burn brush in a 20 to 30ft long half tank, cut lengthwise, then roll the tank over and put dirt along it to prevent escaping smoke and gases.  The charring process would continue for several days.  

 

How successful do you think our efforts to prevent polluting gases and smoke escaping would be?

 

Susan


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


Gordon West
 

I’ve been following this discussion out of general interest, but it is a very different track than ours. Hugh’s comments turned on a light in my head (particularly the mention of big yellow machines) regarding the objectives of the mission. One thing I find frustrating about dealing with most forestry managers is that their primary interest is biomass disposal, with utilization as a difficult byproduct. The Carbonizer is a perfect example. But if you are going to spend half a million $$ on disposal equipment, why wouldn’t you spend the same amount on equipment and a process that creates 20 additional benefits, avoids 10 destructive activities, and makes money in the process?

Excess biomass should not be trapped in the conceptual box of a disposal issue, it needs to be recognized as an incredible opportunity for triple-bottom-line development.

Gordon West
The Trollworks
503 North E Street
Silver City, NM 88061
575-537-3689

“You never change things by fighting the existing reality. 
To change something, build a new model that makes the old model obsolete.”  
– R. Buckminster Fuller










On Sep 9, 2020, at 5:32 PM, Hugh McLaughlin via groups.io <wastemin1@...> wrote:

Dear biochar.groups list,

I would like to present an alternative perspective:

I think this is a terrible idea, fraught with inherent dangers and and unanticipated responses by the equipment due to the scale. In addition, the biochar quality will be all over the place and virtually uncontrolled except for the few operators that can see through steel walls.

Because of the scale, it is implied that there will be "yellow iron" moving things around. I think it is much better suited to devote the same resources to digging a pit and work on a better method to seal the batch after it has burned to mostly char - basically a giant Kon-tiki. If necessary, flood it.

Alternately, modifying a Missouri Kiln to have exiting vapor capture and oxidation would probably give you a safe alternative. Moving large hot objects with combusting contents that can shift is just a bad idea which deserves a redesign.

- Hugh McLaughlin, PhD, PE
(I am a Chemical Engineer and we do lots of hazard reviews and reduction. It has taken the industry decades to realize that a stitch in time saves nine and foresight can identify the same scenarios as hindsight if the right questions are asked in advance.)

On Wednesday, September 9, 2020, 6:25:06 PM EDT, Frank Strie <frank.strie@...> wrote:


Well explained Nando,
There is also the possibility to additional, deliberate air injection onto the right spot of the process, above the glow zone.
Provided there is also some agitation for separation of brittle carbon from flexible carbon the pyrolysis / gasification process can be further optimised.
Observation and practical work go together to further develop the technology and procedure. 
Thermal insulation conditions of the kiln vessel and preheating of the inflowing air also play a role.
All practical, productive fun.
Cheers from under Down Under, Spring is here. 

 

From: main@Biochar.groups.io <main@Biochar.groups.io> On Behalf Of Nando Breiter
Sent: Wednesday, September 9, 2020 11:29 PM
To: main@biochar.groups.io
Subject: Re: [Biochar] Preventing escaping gases

 

Susan, 

 

You might consider sorting the feedstock by size (cross-sectional thickness). Batch similar sizes together. It's like baking cookies. Bake all the same size together to ensure they are all baked to the same degree during a fixed amount of time they share together in the oven. If you bake bread and cookies together for the same amount of time, either the cookies will be burned or the bread underbaked. 

 

When you sort feedstock like this for a batch kiln, it ensures that the processing time is sufficient to transform it to char, while not excessively "baking" the smaller bits into gases. The large rounds might take a few days, the smaller branches a few hours. If the small branches are combined with the large rounds, they will be converted mostly to gases and ash. 


Kind regards,

 

Nando

 

 

On Wed, Sep 9, 2020 at 12:49 AM Susan <suemegg@...> wrote:

Nando,

 

Thank you fir your reply.

 

Unfortunately, due to the nature of our feedstock size is very variable.  We operate a compost site, and loads come in via car trunk loads, pickup trucks and full size dump trucks.  So we have from small bundles of twigs up to tree trunks.

 

The varying size makes for a longer time frame for charring the wood waste.

 

We had considered attempting to flare off the gas and burn it, hoping that would problematic escape of gases and smoke into the atmosphere.

 

Susan

 
 
 

On Tue, Sep 8, 2020, 4:04 PM Nando Breiter <nando@...> wrote:

Susan,

 

The issue is that pyrolysis gases will take up vastly more space than the same atoms and molecules as solids, so pressure will quickly build up within the tank and the gases will have to go somewhere. 

Condensable gases may be trapped in the soil barrier if there is enough to cool them sufficiently to become liquids or solids before they escape. Non-condensables such as carbon monoxide, carbon dioxide and methane will escape into the atmosphere. If you see smoke leaking out, then that would be an indication that your soil barrier is not sufficient to condense them.

 

What you might consider is to create a small outlet for the gases at the end of the tank, and flare them off in an appropriately designed / jury-rigged burner.

 

If you are venting the gases and flaring them, and the brush consists of thin branches rather than thick tree trunks, I would assume that a batch would complete itself in hours rather than days. All that needs to happen is the heat generated needs to penetrate to the depth of each particle of biomass at temperatures over 300° C for the reaction to become exothermic. If the brush is really thin, then once you flip it over, pyrolysis will largely have already occurred and the char will simply need to cool in an oxygen starved environment under the half tank.

 

How thick are the branches of the "brush" you have available?

 
 
 

 

On Tue, Sep 8, 2020 at 6:16 PM Susan <suemegg@...> wrote:

Scenario...   burn brush in a 20 to 30ft long half tank, cut lengthwise, then roll the tank over and put dirt along it to prevent escaping smoke and gases.  The charring process would continue for several days.  

 

How successful do you think our efforts to prevent polluting gases and smoke escaping would be?

 

Susan


-- 
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland 


-- 
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland 




Susan
 

Thank you for your response, the problem with sizing is how some of the material arrives here.  

Most that comes in non-commercial loads would be easy to deal with.  We have a different dumping area for people to put larger branches.  This is turned into firewood to heat our home. 

However it is not feasible to sort commercial loads that come in dump trucks.  

It has been my belief that in having sizes varying so much that we are wasting the finer twigs and branches that char quickly in an attempt to char logs... but with the commercial loads I see no other option.

Susan



On Wed, Sep 9, 2020, 8:29 AM Nando Breiter <nando@...> wrote:
Susan, 

You might consider sorting the feedstock by size (cross-sectional thickness). Batch similar sizes together. It's like baking cookies. Bake all the same size together to ensure they are all baked to the same degree during a fixed amount of time they share together in the oven. If you bake bread and cookies together for the same amount of time, either the cookies will be burned or the bread underbaked. 

When you sort feedstock like this for a batch kiln, it ensures that the processing time is sufficient to transform it to char, while not excessively "baking" the smaller bits into gases. The large rounds might take a few days, the smaller branches a few hours. If the small branches are combined with the large rounds, they will be converted mostly to gases and ash. 

Kind regards,

Nando



On Wed, Sep 9, 2020 at 12:49 AM Susan <suemegg@...> wrote:
Nando,

Thank you fir your reply.

Unfortunately, due to the nature of our feedstock size is very variable.  We operate a compost site, and loads come in via car trunk loads, pickup trucks and full size dump trucks.  So we have from small bundles of twigs up to tree trunks.

The varying size makes for a longer time frame for charring the wood waste.

We had considered attempting to flare off the gas and burn it, hoping that would problematic escape of gases and smoke into the atmosphere.

Susan




On Tue, Sep 8, 2020, 4:04 PM Nando Breiter <nando@...> wrote:
Susan,

The issue is that pyrolysis gases will take up vastly more space than the same atoms and molecules as solids, so pressure will quickly build up within the tank and the gases will have to go somewhere. 

Condensable gases may be trapped in the soil barrier if there is enough to cool them sufficiently to become liquids or solids before they escape. Non-condensables such as carbon monoxide, carbon dioxide and methane will escape into the atmosphere. If you see smoke leaking out, then that would be an indication that your soil barrier is not sufficient to condense them.

What you might consider is to create a small outlet for the gases at the end of the tank, and flare them off in an appropriately designed / jury-rigged burner.

If you are venting the gases and flaring them, and the brush consists of thin branches rather than thick tree trunks, I would assume that a batch would complete itself in hours rather than days. All that needs to happen is the heat generated needs to penetrate to the depth of each particle of biomass at temperatures over 300° C for the reaction to become exothermic. If the brush is really thin, then once you flip it over, pyrolysis will largely have already occurred and the char will simply need to cool in an oxygen starved environment under the half tank.

How thick are the branches of the "brush" you have available?




On Tue, Sep 8, 2020 at 6:16 PM Susan <suemegg@...> wrote:
Scenario...   burn brush in a 20 to 30ft long half tank, cut lengthwise, then roll the tank over and put dirt along it to prevent escaping smoke and gases.  The charring process would continue for several days.  

How successful do you think our efforts to prevent polluting gases and smoke escaping would be?

Susan


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


Nando Breiter
 

Hugh, I don't think it is such a terrible idea, particularly as a starting point. I agree with you that rolling over a half tank that contains burning wood would be dangerous, but tipping a tank over a burning pile would be much less so, as I suggested. Attach a few chains to it and pull it over from a distance. Anchor it in place at the hinge point with a few chains and rebar driven into the ground.

I've seen images of Dick pushing piles of timber into a huge burning pit with his backhoe. If I had to choose, I'd rather not go anywhere near a large pit full of burning wood, particularly in a backhoe with the front tires testing the edge of the pit to get the wood more towards the middle. You've suggested flooding such a pit with water. That's not going to work unless you've got a river to draw it from, sufficient firehose and some very large pumps. Then how to unload it?

But ok. Pyrolysis isn't safe, particularly at large scale. You are correct. I am also concerned which is why I engaged in the discussion. We can discuss ideas without danger.

So here's a variation. Dig a trench a little smaller than the other half of the tank. Fill it with wood. Pre-position the half tank so it can be closed like a lid over the trench on a "hinge", best pulled over with a pre-positioned chain. Start off like a giant kontiki burn, but then close the lid sooner. Deal with the gases by flaring them off in a firebrick chamber with a stainless steel chimney positioned next to one end of the trench. 

Would you be comfortable with trying that? 

Kind regards,

Nando




On Thu, Sep 10, 2020 at 1:32 AM Hugh McLaughlin via groups.io <wastemin1=verizon.net@groups.io> wrote:
Dear biochar.groups list,

I would like to present an alternative perspective:

I think this is a terrible idea, fraught with inherent dangers and and unanticipated responses by the equipment due to the scale. In addition, the biochar quality will be all over the place and virtually uncontrolled except for the few operators that can see through steel walls.

Because of the scale, it is implied that there will be "yellow iron" moving things around. I think it is much better suited to devote the same resources to digging a pit and work on a better method to seal the batch after it has burned to mostly char - basically a giant Kon-tiki. If necessary, flood it.

Alternately, modifying a Missouri Kiln to have exiting vapor capture and oxidation would probably give you a safe alternative. Moving large hot objects with combusting contents that can shift is just a bad idea which deserves a redesign.

- Hugh McLaughlin, PhD, PE
(I am a Chemical Engineer and we do lots of hazard reviews and reduction. It has taken the industry decades to realize that a stitch in time saves nine and foresight can identify the same scenarios as hindsight if the right questions are asked in advance.)

On Wednesday, September 9, 2020, 6:25:06 PM EDT, Frank Strie <frank.strie@...> wrote:


Well explained Nando,
There is also the possibility to additional, deliberate air injection onto the right spot of the process, above the glow zone.
Provided there is also some agitation for separation of brittle carbon from flexible carbon the pyrolysis / gasification process can be further optimised.
Observation and practical work go together to further develop the technology and procedure.
Thermal insulation conditions of the kiln vessel and preheating of the inflowing air also play a role.
All practical, productive fun.
Cheers from under Down Under, Spring is here.

 

From: main@Biochar.groups.io <main@Biochar.groups.io> On Behalf Of Nando Breiter
Sent: Wednesday, September 9, 2020 11:29 PM
To: main@biochar.groups.io
Subject: Re: [Biochar] Preventing escaping gases

 

Susan, 

 

You might consider sorting the feedstock by size (cross-sectional thickness). Batch similar sizes together. It's like baking cookies. Bake all the same size together to ensure they are all baked to the same degree during a fixed amount of time they share together in the oven. If you bake bread and cookies together for the same amount of time, either the cookies will be burned or the bread underbaked. 

 

When you sort feedstock like this for a batch kiln, it ensures that the processing time is sufficient to transform it to char, while not excessively "baking" the smaller bits into gases. The large rounds might take a few days, the smaller branches a few hours. If the small branches are combined with the large rounds, they will be converted mostly to gases and ash. 


Kind regards,

 

Nando

 

 

On Wed, Sep 9, 2020 at 12:49 AM Susan <suemegg@...> wrote:

Nando,

 

Thank you fir your reply.

 

Unfortunately, due to the nature of our feedstock size is very variable.  We operate a compost site, and loads come in via car trunk loads, pickup trucks and full size dump trucks.  So we have from small bundles of twigs up to tree trunks.

 

The varying size makes for a longer time frame for charring the wood waste.

 

We had considered attempting to flare off the gas and burn it, hoping that would problematic escape of gases and smoke into the atmosphere.

 

Susan

 

 

 

On Tue, Sep 8, 2020, 4:04 PM Nando Breiter <nando@...> wrote:

Susan,

 

The issue is that pyrolysis gases will take up vastly more space than the same atoms and molecules as solids, so pressure will quickly build up within the tank and the gases will have to go somewhere. 

Condensable gases may be trapped in the soil barrier if there is enough to cool them sufficiently to become liquids or solids before they escape. Non-condensables such as carbon monoxide, carbon dioxide and methane will escape into the atmosphere. If you see smoke leaking out, then that would be an indication that your soil barrier is not sufficient to condense them.

 

What you might consider is to create a small outlet for the gases at the end of the tank, and flare them off in an appropriately designed / jury-rigged burner.

 

If you are venting the gases and flaring them, and the brush consists of thin branches rather than thick tree trunks, I would assume that a batch would complete itself in hours rather than days. All that needs to happen is the heat generated needs to penetrate to the depth of each particle of biomass at temperatures over 300° C for the reaction to become exothermic. If the brush is really thin, then once you flip it over, pyrolysis will largely have already occurred and the char will simply need to cool in an oxygen starved environment under the half tank.

 

How thick are the branches of the "brush" you have available?

 

 

 

 

On Tue, Sep 8, 2020 at 6:16 PM Susan <suemegg@...> wrote:

Scenario...   burn brush in a 20 to 30ft long half tank, cut lengthwise, then roll the tank over and put dirt along it to prevent escaping smoke and gases.  The charring process would continue for several days.  

 

How successful do you think our efforts to prevent polluting gases and smoke escaping would be?

 

Susan


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


Susan
 

Hugh,

Unfortunately, I am with you...

But I must ad that we used to have a trench,  about 50ft long and 20ft wide.  It was lined with steel, and was very easy to feed and monitor the process.

It was just above a steep slope and the char could be retrieved from below.

We did one batch where I set up eight impulse sprinklers to completely mist the whole area.  The mist prevented smoke and seemed to inhibit pyrolysis gasses escaping as I could not smell it as I had with our tank in the ground.

The tank in the ground worked well, we capped it with a larger diameter tank top, piled clay all around, but gasses did escape.  The other problem with the tank in the ground was retrieving the char.

Susan 



On Wed, Sep 9, 2020, 6:32 PM Hugh McLaughlin via groups.io <wastemin1=verizon.net@groups.io> wrote:
Dear biochar.groups list,

I would like to present an alternative perspective:

I think this is a terrible idea, fraught with inherent dangers and and unanticipated responses by the equipment due to the scale. In addition, the biochar quality will be all over the place and virtually uncontrolled except for the few operators that can see through steel walls.

Because of the scale, it is implied that there will be "yellow iron" moving things around. I think it is much better suited to devote the same resources to digging a pit and work on a better method to seal the batch after it has burned to mostly char - basically a giant Kon-tiki. If necessary, flood it.

Alternately, modifying a Missouri Kiln to have exiting vapor capture and oxidation would probably give you a safe alternative. Moving large hot objects with combusting contents that can shift is just a bad idea which deserves a redesign.

- Hugh McLaughlin, PhD, PE
(I am a Chemical Engineer and we do lots of hazard reviews and reduction. It has taken the industry decades to realize that a stitch in time saves nine and foresight can identify the same scenarios as hindsight if the right questions are asked in advance.)

On Wednesday, September 9, 2020, 6:25:06 PM EDT, Frank Strie <frank.strie@...> wrote:


Well explained Nando,
There is also the possibility to additional, deliberate air injection onto the right spot of the process, above the glow zone.
Provided there is also some agitation for separation of brittle carbon from flexible carbon the pyrolysis / gasification process can be further optimised.
Observation and practical work go together to further develop the technology and procedure.
Thermal insulation conditions of the kiln vessel and preheating of the inflowing air also play a role.
All practical, productive fun.
Cheers from under Down Under, Spring is here.

 

From: main@Biochar.groups.io <main@Biochar.groups.io> On Behalf Of Nando Breiter
Sent: Wednesday, September 9, 2020 11:29 PM
To: main@biochar.groups.io
Subject: Re: [Biochar] Preventing escaping gases

 

Susan, 

 

You might consider sorting the feedstock by size (cross-sectional thickness). Batch similar sizes together. It's like baking cookies. Bake all the same size together to ensure they are all baked to the same degree during a fixed amount of time they share together in the oven. If you bake bread and cookies together for the same amount of time, either the cookies will be burned or the bread underbaked. 

 

When you sort feedstock like this for a batch kiln, it ensures that the processing time is sufficient to transform it to char, while not excessively "baking" the smaller bits into gases. The large rounds might take a few days, the smaller branches a few hours. If the small branches are combined with the large rounds, they will be converted mostly to gases and ash. 


Kind regards,

 

Nando

 

 

On Wed, Sep 9, 2020 at 12:49 AM Susan <suemegg@...> wrote:

Nando,

 

Thank you fir your reply.

 

Unfortunately, due to the nature of our feedstock size is very variable.  We operate a compost site, and loads come in via car trunk loads, pickup trucks and full size dump trucks.  So we have from small bundles of twigs up to tree trunks.

 

The varying size makes for a longer time frame for charring the wood waste.

 

We had considered attempting to flare off the gas and burn it, hoping that would problematic escape of gases and smoke into the atmosphere.

 

Susan

 

 

 

On Tue, Sep 8, 2020, 4:04 PM Nando Breiter <nando@...> wrote:

Susan,

 

The issue is that pyrolysis gases will take up vastly more space than the same atoms and molecules as solids, so pressure will quickly build up within the tank and the gases will have to go somewhere. 

Condensable gases may be trapped in the soil barrier if there is enough to cool them sufficiently to become liquids or solids before they escape. Non-condensables such as carbon monoxide, carbon dioxide and methane will escape into the atmosphere. If you see smoke leaking out, then that would be an indication that your soil barrier is not sufficient to condense them.

 

What you might consider is to create a small outlet for the gases at the end of the tank, and flare them off in an appropriately designed / jury-rigged burner.

 

If you are venting the gases and flaring them, and the brush consists of thin branches rather than thick tree trunks, I would assume that a batch would complete itself in hours rather than days. All that needs to happen is the heat generated needs to penetrate to the depth of each particle of biomass at temperatures over 300° C for the reaction to become exothermic. If the brush is really thin, then once you flip it over, pyrolysis will largely have already occurred and the char will simply need to cool in an oxygen starved environment under the half tank.

 

How thick are the branches of the "brush" you have available?

 

 

 

 

On Tue, Sep 8, 2020 at 6:16 PM Susan <suemegg@...> wrote:

Scenario...   burn brush in a 20 to 30ft long half tank, cut lengthwise, then roll the tank over and put dirt along it to prevent escaping smoke and gases.  The charring process would continue for several days.  

 

How successful do you think our efforts to prevent polluting gases and smoke escaping would be?

 

Susan


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


Hugh McLaughlin
 

Hello Susan,

Let's drill down a bit on the challenge of removing material at the end of the batch. This is a mechanical challenge, but does not carry any of the hazard issues I flagged. I have seen a system for emptying Adam Retorts where the char is vacuumed via a cutter head that pulverizes the char and wets it at the same time.

These issues are not trivial, but material handling is much more straightforward and user-friendly than combustible vapors.

If the process is scaled down, do any of the challenges become more manageable? Boiling two smaller pots of pasta is not much more work than one large pot.....

This sounds solvable with a few trials and a bit of a learning curve.

- Hugh

On Wednesday, September 9, 2020, 9:23:20 PM EDT, Susan <suemegg@...> wrote:


Hugh,

Unfortunately, I am with you...

But I must ad that we used to have a trench,  about 50ft long and 20ft wide.  It was lined with steel, and was very easy to feed and monitor the process.

It was just above a steep slope and the char could be retrieved from below.

We did one batch where I set up eight impulse sprinklers to completely mist the whole area.  The mist prevented smoke and seemed to inhibit pyrolysis gasses escaping as I could not smell it as I had with our tank in the ground.

The tank in the ground worked well, we capped it with a larger diameter tank top, piled clay all around, but gasses did escape.  The other problem with the tank in the ground was retrieving the char.

Susan 



On Wed, Sep 9, 2020, 6:32 PM Hugh McLaughlin via groups.io <wastemin1=verizon.net@groups.io> wrote:
Dear biochar.groups list,

I would like to present an alternative perspective:

I think this is a terrible idea, fraught with inherent dangers and and unanticipated responses by the equipment due to the scale. In addition, the biochar quality will be all over the place and virtually uncontrolled except for the few operators that can see through steel walls.

Because of the scale, it is implied that there will be "yellow iron" moving things around. I think it is much better suited to devote the same resources to digging a pit and work on a better method to seal the batch after it has burned to mostly char - basically a giant Kon-tiki. If necessary, flood it.

Alternately, modifying a Missouri Kiln to have exiting vapor capture and oxidation would probably give you a safe alternative. Moving large hot objects with combusting contents that can shift is just a bad idea which deserves a redesign.

- Hugh McLaughlin, PhD, PE
(I am a Chemical Engineer and we do lots of hazard reviews and reduction. It has taken the industry decades to realize that a stitch in time saves nine and foresight can identify the same scenarios as hindsight if the right questions are asked in advance.)

On Wednesday, September 9, 2020, 6:25:06 PM EDT, Frank Strie <frank.strie@...> wrote:


Well explained Nando,
There is also the possibility to additional, deliberate air injection onto the right spot of the process, above the glow zone.
Provided there is also some agitation for separation of brittle carbon from flexible carbon the pyrolysis / gasification process can be further optimised.
Observation and practical work go together to further develop the technology and procedure.
Thermal insulation conditions of the kiln vessel and preheating of the inflowing air also play a role.
All practical, productive fun.
Cheers from under Down Under, Spring is here.

 

From: main@Biochar.groups.io <main@Biochar.groups.io> On Behalf Of Nando Breiter
Sent: Wednesday, September 9, 2020 11:29 PM
To: main@biochar.groups.io
Subject: Re: [Biochar] Preventing escaping gases

 

Susan, 

 

You might consider sorting the feedstock by size (cross-sectional thickness). Batch similar sizes together. It's like baking cookies. Bake all the same size together to ensure they are all baked to the same degree during a fixed amount of time they share together in the oven. If you bake bread and cookies together for the same amount of time, either the cookies will be burned or the bread underbaked. 

 

When you sort feedstock like this for a batch kiln, it ensures that the processing time is sufficient to transform it to char, while not excessively "baking" the smaller bits into gases. The large rounds might take a few days, the smaller branches a few hours. If the small branches are combined with the large rounds, they will be converted mostly to gases and ash. 


Kind regards,

 

Nando

 

 

On Wed, Sep 9, 2020 at 12:49 AM Susan <suemegg@...> wrote:

Nando,

 

Thank you fir your reply.

 

Unfortunately, due to the nature of our feedstock size is very variable.  We operate a compost site, and loads come in via car trunk loads, pickup trucks and full size dump trucks.  So we have from small bundles of twigs up to tree trunks.

 

The varying size makes for a longer time frame for charring the wood waste.

 

We had considered attempting to flare off the gas and burn it, hoping that would problematic escape of gases and smoke into the atmosphere.

 

Susan

 

 

 

On Tue, Sep 8, 2020, 4:04 PM Nando Breiter <nando@...> wrote:

Susan,

 

The issue is that pyrolysis gases will take up vastly more space than the same atoms and molecules as solids, so pressure will quickly build up within the tank and the gases will have to go somewhere. 

Condensable gases may be trapped in the soil barrier if there is enough to cool them sufficiently to become liquids or solids before they escape. Non-condensables such as carbon monoxide, carbon dioxide and methane will escape into the atmosphere. If you see smoke leaking out, then that would be an indication that your soil barrier is not sufficient to condense them.

 

What you might consider is to create a small outlet for the gases at the end of the tank, and flare them off in an appropriately designed / jury-rigged burner.

 

If you are venting the gases and flaring them, and the brush consists of thin branches rather than thick tree trunks, I would assume that a batch would complete itself in hours rather than days. All that needs to happen is the heat generated needs to penetrate to the depth of each particle of biomass at temperatures over 300° C for the reaction to become exothermic. If the brush is really thin, then once you flip it over, pyrolysis will largely have already occurred and the char will simply need to cool in an oxygen starved environment under the half tank.

 

How thick are the branches of the "brush" you have available?

 

 

 

 

On Tue, Sep 8, 2020 at 6:16 PM Susan <suemegg@...> wrote:

Scenario...   burn brush in a 20 to 30ft long half tank, cut lengthwise, then roll the tank over and put dirt along it to prevent escaping smoke and gases.  The charring process would continue for several days.  

 

How successful do you think our efforts to prevent polluting gases and smoke escaping would be?

 

Susan


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


Dick Gallien
 

Beautiful Nando,
 When the tank/turtle is rolled onto it's 6'X 30' belly and it's hot gases rise to it's 8' top and then are forced down along each side, into the charring mass, how much of the pressure build up, would you expect to be reduced by burning those gases?  Rather than interrupt the pyrolysis cycle by removing gases from the top, where would you suggest a pipe be placed, to balance the pressure?

The sealed 55 ga barrel of "waste wood", set over a wood fire, with the 3/8" hole flaming skyward vs retorting, should produce a little wonder.among visitors.

In this country, where most urban organic materials are officially labeled: "wood waste", "food waste", "yard waste" and "human waste", to be burned, buried, flushed or landfilled, is blindly accepted by most.  Only fools would be so determined, while finding fun/excitement in trying to turn "wood waste", which is being very efficiently disposed of across this country with matches and lighters into biochar, which can benefit healthy soil and the life that depends on it for hundreds to thousands of years.

The price/maintenance of whole tree chippers is out of sight for most..  Logs not good for lumber or firewood (I've heated only with wood for 54 yrs)  can be split,  but until processes are ironed out, the intense heat and patience, with no down dizing, will result in some biochar. 

I mentioned to Hugh a few yrs. ago about the trench into a clay bank, 24' W 12'D X60', with brush stacked 10' above the upper ground level, lit on top and when burned down, I spread two 1500 ga. tanks of creek water on it and Sue ran 4 hose sprinklers continuously for 11 days, with a steady stream of clear water running out the lower end.  Hugh said that water would've had a slight lemon taste.  Sue, who has always said "It worked !!", after I dozed it shut, just said the only time there was the acrid smell was when I turned the hose off (which is an interesting thought) in that when the DNR game warden visited in June about a pyrolysis complaint and we can have no smoke or fumes other than between 8 and 4. Might 2 or 3 fine spraying nozzles over the 10' dia X 30' tank top hold the authorities off, while we consult with all of you?  

My goal is to mix the biochar in compost and spread it on the farm fields.  If any microbes complain about their residence I'll suggest they visit the majority of Mid West farm fields, that are dead/over dosed on chem's and headed for the Gulf.  The 11' wide dozer blade would  easily make a trench of that width.  When the brush was burned down and I've done that with wet compost, dozed dirt or compost over the burn without the tracks touching the pyrolysizing covered pile.  The pyrolysis fumes will continue, so we could test light hosing; however, wouldn't the toxicity of the pyrolysis gases be trapped in the covering of dirt or compost ?.

Eliminating smoke and fumes after 4pm is essential--because I've poked the DNR Forestry Dept..  We have a 1500 gallon liquid manure tank and a nearby trout stream, but a flooded trench would be an impossible mud hole.  The bricks this house was built from came from an adjoining brickyard.  

I don't remember in photos of large kilns built into slopes in S.A., with condensate being collected from chimney pipes on the above slope, whether they bothered to burn off the fumes.   
Thanks for your thoughts and suggestions.  Dick
   

On Wed, Sep 9, 2020 at 8:29 AM Nando Breiter <nando@...> wrote:
Susan, 

You might consider sorting the feedstock by size (cross-sectional thickness). Batch similar sizes together. It's like baking cookies. Bake all the same size together to ensure they are all baked to the same degree during a fixed amount of time they share together in the oven. If you bake bread and cookies together for the same amount of time, either the cookies will be burned or the bread underbaked. 

When you sort feedstock like this for a batch kiln, it ensures that the processing time is sufficient to transform it to char, while not excessively "baking" the smaller bits into gases. The large rounds might take a few days, the smaller branches a few hours. If the small branches are combined with the large rounds, they will be converted mostly to gases and ash. 

Kind regards,

Nando



On Wed, Sep 9, 2020 at 12:49 AM Susan <suemegg@...> wrote:
Nando,

Thank you fir your reply.

Unfortunately, due to the nature of our feedstock size is very variable.  We operate a compost site, and loads come in via car trunk loads, pickup trucks and full size dump trucks.  So we have from small bundles of twigs up to tree trunks.

The varying size makes for a longer time frame for charring the wood waste.

We had considered attempting to flare off the gas and burn it, hoping that would problematic escape of gases and smoke into the atmosphere.

Susan




On Tue, Sep 8, 2020, 4:04 PM Nando Breiter <nando@...> wrote:
Susan,

The issue is that pyrolysis gases will take up vastly more space than the same atoms and molecules as solids, so pressure will quickly build up within the tank and the gases will have to go somewhere. 

Condensable gases may be trapped in the soil barrier if there is enough to cool them sufficiently to become liquids or solids before they escape. Non-condensables such as carbon monoxide, carbon dioxide and methane will escape into the atmosphere. If you see smoke leaking out, then that would be an indication that your soil barrier is not sufficient to condense them.

What you might consider is to create a small outlet for the gases at the end of the tank, and flare them off in an appropriately designed / jury-rigged burner.

If you are venting the gases and flaring them, and the brush consists of thin branches rather than thick tree trunks, I would assume that a batch would complete itself in hours rather than days. All that needs to happen is the heat generated needs to penetrate to the depth of each particle of biomass at temperatures over 300° C for the reaction to become exothermic. If the brush is really thin, then once you flip it over, pyrolysis will largely have already occurred and the char will simply need to cool in an oxygen starved environment under the half tank.

How thick are the branches of the "brush" you have available?




On Tue, Sep 8, 2020 at 6:16 PM Susan <suemegg@...> wrote:
Scenario...   burn brush in a 20 to 30ft long half tank, cut lengthwise, then roll the tank over and put dirt along it to prevent escaping smoke and gases.  The charring process would continue for several days.  

How successful do you think our efforts to prevent polluting gases and smoke escaping would be?

Susan


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


Dick Gallien
 

Frank's kiln insulation suggestion.   The huge pile of green, damp wood chips, would surely be more than dried, if not catching fire, by being stacked over the horizontal , 30' long charring turtle/tank for a few wks. and then replaced with more.  Lighting a few ft. of dried chips on the floor of the turtle/tank wouldn't seem to provide a flame cap, as with brush.  Would filling the turtle/tank with dry chips and lighting the top equal any biochar, or just smoke and ash ?? 
Hugh's Lemonade.  The Farm is between the vulture eyed DNR Game Warden, who lives just up the valley and town.  He would've immediately spotted the flame cap in the big trench, but if we'd have known Hugh's recipe, we'd have innocently   been making lemonade after 4 pm .  There's seldom any smoke, after the flame cap settles down, only the sightless, acrid smell of pyrolysis.

Hugh/Paul/Anyone, I've read that the chips in a large Jolly Rogers, don't burn  evenly, so collapse.  When I burned some brush in the 10' dia X 30' vertical tank, there was a 1/2 crack at the bottom of the 7'X7'X 7/8" steel door, that quickly became red hot on the lower 2' until clay was packed against the crack.  What experimental combinations would you suggest, with piles of wood chips and brush ?   .  .https://www.youtube.com/watch?v=Kg95KYrH8PI     Thanks, Dick





On Wed, Sep 9, 2020 at 10:15 PM Dick Gallien via groups.io <dickgallien=gmail.com@groups.io> wrote:
Beautiful Nando,
 When the tank/turtle is rolled onto it's 6'X 30' belly and it's hot gases rise to it's 8' top and then are forced down along each side, into the charring mass, how much of the pressure build up, would you expect to be reduced by burning those gases?  Rather than interrupt the pyrolysis cycle by removing gases from the top, where would you suggest a pipe be placed, to balance the pressure?

The sealed 55 ga barrel of "waste wood", set over a wood fire, with the 3/8" hole flaming skyward vs retorting, should produce a little wonder.among visitors.

In this country, where most urban organic materials are officially labeled: "wood waste", "food waste", "yard waste" and "human waste", to be burned, buried, flushed or landfilled, is blindly accepted by most.  Only fools would be so determined, while finding fun/excitement in trying to turn "wood waste", which is being very efficiently disposed of across this country with matches and lighters into biochar, which can benefit healthy soil and the life that depends on it for hundreds to thousands of years.

The price/maintenance of whole tree chippers is out of sight for most..  Logs not good for lumber or firewood (I've heated only with wood for 54 yrs)  can be split,  but until processes are ironed out, the intense heat and patience, with no down dizing, will result in some biochar. 

I mentioned to Hugh a few yrs. ago about the trench into a clay bank, 24' W 12'D X60', with brush stacked 10' above the upper ground level, lit on top and when burned down, I spread two 1500 ga. tanks of creek water on it and Sue ran 4 hose sprinklers continuously for 11 days, with a steady stream of clear water running out the lower end.  Hugh said that water would've had a slight lemon taste.  Sue, who has always said "It worked !!", after I dozed it shut, just said the only time there was the acrid smell was when I turned the hose off (which is an interesting thought) in that when the DNR game warden visited in June about a pyrolysis complaint and we can have no smoke or fumes other than between 8 and 4. Might 2 or 3 fine spraying nozzles over the 10' dia X 30' tank top hold the authorities off, while we consult with all of you?  

My goal is to mix the biochar in compost and spread it on the farm fields.  If any microbes complain about their residence I'll suggest they visit the majority of Mid West farm fields, that are dead/over dosed on chem's and headed for the Gulf.  The 11' wide dozer blade would  easily make a trench of that width.  When the brush was burned down and I've done that with wet compost, dozed dirt or compost over the burn without the tracks touching the pyrolysizing covered pile.  The pyrolysis fumes will continue, so we could test light hosing; however, wouldn't the toxicity of the pyrolysis gases be trapped in the covering of dirt or compost ?.

Eliminating smoke and fumes after 4pm is essential--because I've poked the DNR Forestry Dept..  We have a 1500 gallon liquid manure tank and a nearby trout stream, but a flooded trench would be an impossible mud hole.  The bricks this house was built from came from an adjoining brickyard.  

I don't remember in photos of large kilns built into slopes in S.A., with condensate being collected from chimney pipes on the above slope, whether they bothered to burn off the fumes.   
Thanks for your thoughts and suggestions.  Dick
   

On Wed, Sep 9, 2020 at 8:29 AM Nando Breiter <nando@...> wrote:
Susan, 

You might consider sorting the feedstock by size (cross-sectional thickness). Batch similar sizes together. It's like baking cookies. Bake all the same size together to ensure they are all baked to the same degree during a fixed amount of time they share together in the oven. If you bake bread and cookies together for the same amount of time, either the cookies will be burned or the bread underbaked. 

When you sort feedstock like this for a batch kiln, it ensures that the processing time is sufficient to transform it to char, while not excessively "baking" the smaller bits into gases. The large rounds might take a few days, the smaller branches a few hours. If the small branches are combined with the large rounds, they will be converted mostly to gases and ash. 

Kind regards,

Nando



On Wed, Sep 9, 2020 at 12:49 AM Susan <suemegg@...> wrote:
Nando,

Thank you fir your reply.

Unfortunately, due to the nature of our feedstock size is very variable.  We operate a compost site, and loads come in via car trunk loads, pickup trucks and full size dump trucks.  So we have from small bundles of twigs up to tree trunks.

The varying size makes for a longer time frame for charring the wood waste.

We had considered attempting to flare off the gas and burn it, hoping that would problematic escape of gases and smoke into the atmosphere.

Susan




On Tue, Sep 8, 2020, 4:04 PM Nando Breiter <nando@...> wrote:
Susan,

The issue is that pyrolysis gases will take up vastly more space than the same atoms and molecules as solids, so pressure will quickly build up within the tank and the gases will have to go somewhere. 

Condensable gases may be trapped in the soil barrier if there is enough to cool them sufficiently to become liquids or solids before they escape. Non-condensables such as carbon monoxide, carbon dioxide and methane will escape into the atmosphere. If you see smoke leaking out, then that would be an indication that your soil barrier is not sufficient to condense them.

What you might consider is to create a small outlet for the gases at the end of the tank, and flare them off in an appropriately designed / jury-rigged burner.

If you are venting the gases and flaring them, and the brush consists of thin branches rather than thick tree trunks, I would assume that a batch would complete itself in hours rather than days. All that needs to happen is the heat generated needs to penetrate to the depth of each particle of biomass at temperatures over 300° C for the reaction to become exothermic. If the brush is really thin, then once you flip it over, pyrolysis will largely have already occurred and the char will simply need to cool in an oxygen starved environment under the half tank.

How thick are the branches of the "brush" you have available?




On Tue, Sep 8, 2020 at 6:16 PM Susan <suemegg@...> wrote:
Scenario...   burn brush in a 20 to 30ft long half tank, cut lengthwise, then roll the tank over and put dirt along it to prevent escaping smoke and gases.  The charring process would continue for several days.  

How successful do you think our efforts to prevent polluting gases and smoke escaping would be?

Susan


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


Nando Breiter
 

Dick,

I'll try to answer your questions inline below.


 When the tank/turtle is rolled onto it's 6'X 30' belly and it's hot gases rise to it's 8' top and then are forced down along each side, into the charring mass, how much of the pressure build up, would you expect to be reduced by burning those gases? 
All of the gases would be flared, and there would only be a very minimal pressure difference. Our 10 m3 batch kiln uses 8" heat and corrosion resistant stainless steel tubing to transport the gases to the flare, which is up on a stand to keep the flame out of harm's way.
 
Rather than interrupt the pyrolysis cycle by removing gases from the top, where would you suggest a pipe be placed, to balance the pressure?

Pyrolysis won't be interrupted. Keep in mind that the gases will escape in any case. 

To keep the pyrolysis gases within a pyrolysis retort, you would need a very expensive kiln that could withstand extremely high pressures, easily costing 10's of millions of dollars for the capacity we are discussing. Nikolaus Foidl tried to build a small high pressure retort, and he ran into a world of trouble getting the access door for the biomass to seal. I don't know what the upper range is of a perfectly sealed retort, but Nikolaus was trying to hit 50 bar, if I remember correctly, and his initial tests at about 500° C saw the seal fail at some abysmally low value of perhaps 1.5 - 2 bar. I think the problem here is he wanted a large diameter access hatch that would allow for the easy loading and unloading of biomass, rather than a manhole sized access hatch where it would be "easier" to maintain the needed seal to reach 50 bar. His design had redundant relief values, and he intended to fully bury it in a containment pit in case of structural failure, which would lead to a massive explosion.

With the approach you've proposed, you aren't anywhere near being able to contain pyrolysis gases. So there will be virtually no pressure buildup under the tank. If there is for a moment, the gases will create one or more channels out of the kiln through the soil.

I'm proposing to create an easy escape route so we can flare them, instead of allowing them to escape through the soil. Once they are flared, you'll have an absolutely transparent emission of CO2 and H2O from the stack, like the emissions from a natural gas flame, rather than a mix of CO2, CO, CH4 (methane) perhaps some H2 (hydrogen) and a wide variety of complex hydrocarbons as gases or tar microdroplets. 

As you have heard, pyrolysis is exothermic. What that fancy word means is that as the biomass thermally decomposes at temperatures above 300° C, oxygen and carbon atoms, or carbon based molecules, and eventually hydrogen, are released, and as these recombine, either within the biomass particle on their way out, or just outside of the biomass particle, that reaction gives off heat. It is that exothermic heat that maintains a pyrolysis reaction in a batch process such as you are proposing once access to air is limited. 

The exothermic reaction in pyrolysis is the same reaction we call a fire, oxygen combining with carbon and or hydrogen, except that the amount of available oxygen is limited to that which is being decomposed from the biomass. It is that limit of oxygen that prevents the entire batch from being oxidized. That limit also self-regulates the temperature of a pyrolysis batch in a well designed kiln that conserves heat to between 450° - 550°C. Why? Because there is not enough oxygen in the biomass to elevate the temperature higher than that. 

This is also why a pyrolysis reaction in a closed batch stops; it runs out of oxygen.

Whether or not the pyrolysis reaction is self-sustaining depends on if there is sufficient exothermic heat available to continue to heat the remaining un-pyrolyzed biomass above 300° C. The critical factor here is how dry the biomass is. Evaporating water out of biomass cools the biomass down, so the entirety of a biomass particle will not heat above 99° C until all the water is evaporated out of it (in a simple kiln operating at atmospheric pressure). So if you start a batch, close the lid, and the temperature drops off, the biomass is still too wet for the reaction to be self-sustaining. 

In this case, which I certainly think will happen in your situation, what you could try is that rather than open the lid again, just let some air into it, from the end opposite the gas flare burner. You should hopefully have sufficient draft on the chimney to pull air into the kiln. Let a bit of air into the kiln to bring the temperature up to dry the wood. You don't want a roaring fire. A charred surface forms somewhat of a seal that makes it harder for evaporating water to escape.

So now we are getting very close to the Adam retort design. Here's an outline of a further evolution of Susan's idea that will be much safer and efficient to operate, while producing a reasonably uniform biochar with the minimum amount of biomass consumed to produce the heat necessary, and very little to no emissions besides CO2 and water vapor.

Sue's Evolved Biochar Kiln Concept - Details to be refined
  • Cut the tank in half lengthwise. 
  • (Optionally) dig a ramped trench that is slightly shorter and narrower than the tank, so that the tank will fit over the trench as a cover. After the batch is finished, a tractor or front end loader should be able to drive into the trench to remove the finished char
  • Fix the tank-half to the side of the trench so that it hinges closed over the trench to act as a cover. The hinge mechanism could use heavy chain welded to the tank and rebar driven into the ground. We only need to ensure the tank-half stays in the proper position as it is being pulled over.
  • Fix a longer heavy chain or better a cable to the other outer lip of the retort lid (tank-half) to be used to pull the lid over the trench with a tractor. If the cable is light enough to be tossed over the tank-half, then the same cable could be used for opening and closing the lid. Otherwise, 2 cables can be used, one to close and one to open.
  • Steel or wooden braces could be used to prevent the retort lid from tipping all the way over when it is opened. It should open past 90° so it stays put. If it is braced open, like the lid on a treasure chest, the cable should be anchored to prevent it from blowing closed in a strong wind.
  • The kiln is loaded with wood, generally oriented along the length of the trench and heaped to fill the space that will be enclosed by the lid, and the lid is then closed. No open fire is used.
  • The kiln is designed to encourage a pyrolysis front to move from one end to the other along the length of the half-tank / trench assembly. 
  • On the starting end, there is an opening in the tank near the bottom connected to a tube. This tube can be closed off, allow air into it, or allow hot flue gas from a wood fire into it. (If a large "stove" with a wood fire in it is used to initially heat the kiln, then that much less wood in the batch will be consumed to provide the heat necessary. So this is a trade off between maximizing the batch output or making operation more simple.)
  • At the other end, a tube is fixed to the tank-half. Midway up should be fine. This tube angles downward into a combustion chamber which will be used to flare the gases. The angle is meant to allow condensate that may form to run down into the combustion chamber. It has a tall chimney on it to encourage a draft to gently pull hot gases through the kiln. We can call this the gas burner.
  • Ideally, the gas burner should be moveable so that when the retort is closed and the tubing is fixed to the half-tank lid, the gas burner position can be adjusted as necessary to attach the other end of the tube to it. If the trench is ramped to allow machinery access for unloading, then the gas burner needs to be either mobile enough to easily move it out of place or positioned off center so it is out of the way of the ramp.
  • In the initial stages of a batch, the gas burner flame will need to be supported to remain lit because of the moisture content of the gas. What this means is that the humidity in the gas will extinguish the flame, largely because it is too dilute to sustain itself. There are options here, the easiest of which may be to burn a little wood in this chamber. The plus is this would be a simple solution, the minus is that someone may need to add wood every hour or so.
  • At the other end of the kiln, there is optionally what I will call the wood stove, to keep it simple. Wood is loaded into it, and the flue gases are directed into the kiln and drawn through either by a small squirrel cage blower if the intent is to simply dry the batch, or a small wood fire is lit in the "gas burner" to create a draft that will draw the moisture out of the kiln if the intent is to initiate pyrolysis more quickly
  • Easy startup of pyrolysis will depend on having thoroughly dry wood at the starting end. Ideally, smaller, pre-dried branches are loaded at the starting end. The core idea here is that once pyrolysis begins at the starting end, the heat generated will continue to dry and heat the feedstock ahead of the pyrolysis front, which will slowly advance from the starting end of the kiln to the finish point nearest the gas burner. So, operation is in several stages:
  1. Pre-drying the wood, particularly at the starting end. Smaller starting end wood can be dried outside of the kiln before loading it if more convenient. Or a large wood stove can be used to inject heat into the kiln to dry in particular the first 3-5 feet of wood. You can think of this as pyrolysis kindling. The drier our pyrolysis kindling, and the more we have of it at the leading end, the easier it will be to initiate pyrolysis. 
  2. Light the starting wood on fire at the starting end, allowing air into the kiln and controlling the amount of air to keep the flame gentle. At this stage, a wood (or propane or wood pellet ...) fire is started in the gas burner to provide some draft to pull the gases through and burn off any flammable gases coming out of Sue's kiln. The objective is to raise temperatures at the starting end sufficiently for pyrolysis to be maintained exothermically.
  3. Once pyrolysis can be maintained without air being added at the starting end, the air inlet is closed. Wood is occasionally added to the gas burner to help maintain the flare.
  4. If temperatures begin to fall in the kiln, the air inlet is slightly opened again to bring them up. Whether or not the exothermically available heat is sufficient to dry the wood ahead of the pyrolysis front is dependent on the moisture content and thickness of the wood.
  5. Once most of the moisture is driven out of the wood, the flare will continue to burn even without support. So it can operate overnight without being attended to if wood has been used to support the flame.
This approach is based on the principals at play in one of our proven vertical batch kiln designs that has been built and operated a number of times in South America. Because it is designed to allow a pyrolysis front to move through the batch, the amount of burnable gas it will produce remains at consistent, manageable levels. A probe penetrating the kiln lid would measure the internal temperature, and the aim would be to keep it below 450°-550 C or so. More than that and too much air is entering the kiln. 

The biomass that still needs to dry will not dry that much more quickly if higher temperatures are used. Higher temps will also corrode the tank more quickly. The velocity of drying will depend more on the rate at which water vapor laden gas is removed than the heat used. We will be depending primarily on the gases being produced within the kiln to develop the pressure needed to push them out through the burner.

Now, it may seem to be much more effective to leave the lid open light the whole pile on fire, but in this case, most of the heat being produced is immediately lost to the atmosphere, so we are transforming a significant portion of our biomass to CO2 for no useful purpose. And no matter how much heat is applied at the surface of a large log, drying simply takes time. Those 2 facts together mean that much more of the biomass will be burned to dry the biomass in an open flame approach than is actually necessary. Yes, you could produce a relatively small pile of glowing embers at the bottom of the trench after a long open fire, and then close the lid completely and just let the heat dissipate. Then no burner would be needed. But, to produce the same amount of char as you will get from a closed lid pyrolysis front approach, you'll need several batches and need much more wood.

When we close the half-tank lid to this trench kiln from the beginning of the batch, and only add air very judiciously, the heat we are producing from the addition of air is used very efficiently. 

So that's Sue's evolved biochar kiln in a nutshell. Much safer, much more efficient in its use of heat and wood, minimized CO2 emissions compared to char produced, and with the addition of the ramped trench, hopefully much easier to unload than a large pit while still maximizing the batch capacity under a half tank.

I'll leave it here for now.








The sealed 55 ga barrel of "waste wood", set over a wood fire, with the 3/8" hole flaming skyward vs retorting, should produce a little wonder.among visitors.

In this country, where most urban organic materials are officially labeled: "wood waste", "food waste", "yard waste" and "human waste", to be burned, buried, flushed or landfilled, is blindly accepted by most.  Only fools would be so determined, while finding fun/excitement in trying to turn "wood waste", which is being very efficiently disposed of across this country with matches and lighters into biochar, which can benefit healthy soil and the life that depends on it for hundreds to thousands of years.

The price/maintenance of whole tree chippers is out of sight for most..  Logs not good for lumber or firewood (I've heated only with wood for 54 yrs)  can be split,  but until processes are ironed out, the intense heat and patience, with no down dizing, will result in some biochar. 

I mentioned to Hugh a few yrs. ago about the trench into a clay bank, 24' W 12'D X60', with brush stacked 10' above the upper ground level, lit on top and when burned down, I spread two 1500 ga. tanks of creek water on it and Sue ran 4 hose sprinklers continuously for 11 days, with a steady stream of clear water running out the lower end.  Hugh said that water would've had a slight lemon taste.  Sue, who has always said "It worked !!", after I dozed it shut, just said the only time there was the acrid smell was when I turned the hose off (which is an interesting thought) in that when the DNR game warden visited in June about a pyrolysis complaint and we can have no smoke or fumes other than between 8 and 4. Might 2 or 3 fine spraying nozzles over the 10' dia X 30' tank top hold the authorities off, while we consult with all of you?  

My goal is to mix the biochar in compost and spread it on the farm fields.  If any microbes complain about their residence I'll suggest they visit the majority of Mid West farm fields, that are dead/over dosed on chem's and headed for the Gulf.  The 11' wide dozer blade would  easily make a trench of that width.  When the brush was burned down and I've done that with wet compost, dozed dirt or compost over the burn without the tracks touching the pyrolysizing covered pile.  The pyrolysis fumes will continue, so we could test light hosing; however, wouldn't the toxicity of the pyrolysis gases be trapped in the covering of dirt or compost ?.

Eliminating smoke and fumes after 4pm is essential--because I've poked the DNR Forestry Dept..  We have a 1500 gallon liquid manure tank and a nearby trout stream, but a flooded trench would be an impossible mud hole.  The bricks this house was built from came from an adjoining brickyard.  

I don't remember in photos of large kilns built into slopes in S.A., with condensate being collected from chimney pipes on the above slope, whether they bothered to burn off the fumes.   
Thanks for your thoughts and suggestions.  Dick
   

On Wed, Sep 9, 2020 at 8:29 AM Nando Breiter <nando@...> wrote:
Susan, 

You might consider sorting the feedstock by size (cross-sectional thickness). Batch similar sizes together. It's like baking cookies. Bake all the same size together to ensure they are all baked to the same degree during a fixed amount of time they share together in the oven. If you bake bread and cookies together for the same amount of time, either the cookies will be burned or the bread underbaked. 

When you sort feedstock like this for a batch kiln, it ensures that the processing time is sufficient to transform it to char, while not excessively "baking" the smaller bits into gases. The large rounds might take a few days, the smaller branches a few hours. If the small branches are combined with the large rounds, they will be converted mostly to gases and ash. 

Kind regards,

Nando



On Wed, Sep 9, 2020 at 12:49 AM Susan <suemegg@...> wrote:
Nando,

Thank you fir your reply.

Unfortunately, due to the nature of our feedstock size is very variable.  We operate a compost site, and loads come in via car trunk loads, pickup trucks and full size dump trucks.  So we have from small bundles of twigs up to tree trunks.

The varying size makes for a longer time frame for charring the wood waste.

We had considered attempting to flare off the gas and burn it, hoping that would problematic escape of gases and smoke into the atmosphere.

Susan




On Tue, Sep 8, 2020, 4:04 PM Nando Breiter <nando@...> wrote:
Susan,

The issue is that pyrolysis gases will take up vastly more space than the same atoms and molecules as solids, so pressure will quickly build up within the tank and the gases will have to go somewhere. 

Condensable gases may be trapped in the soil barrier if there is enough to cool them sufficiently to become liquids or solids before they escape. Non-condensables such as carbon monoxide, carbon dioxide and methane will escape into the atmosphere. If you see smoke leaking out, then that would be an indication that your soil barrier is not sufficient to condense them.

What you might consider is to create a small outlet for the gases at the end of the tank, and flare them off in an appropriately designed / jury-rigged burner.

If you are venting the gases and flaring them, and the brush consists of thin branches rather than thick tree trunks, I would assume that a batch would complete itself in hours rather than days. All that needs to happen is the heat generated needs to penetrate to the depth of each particle of biomass at temperatures over 300° C for the reaction to become exothermic. If the brush is really thin, then once you flip it over, pyrolysis will largely have already occurred and the char will simply need to cool in an oxygen starved environment under the half tank.

How thick are the branches of the "brush" you have available?




On Tue, Sep 8, 2020 at 6:16 PM Susan <suemegg@...> wrote:
Scenario...   burn brush in a 20 to 30ft long half tank, cut lengthwise, then roll the tank over and put dirt along it to prevent escaping smoke and gases.  The charring process would continue for several days.  

How successful do you think our efforts to prevent polluting gases and smoke escaping would be?

Susan


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


Paul S Anderson
 

Dick,

 

1.  What is the “the sightless, acrid smell of pyrolysis”

when the flame cap is gone?    Is it “char gasification”?  It is not pyrolysis.    

 

Sightless is the burning of char which is making CO that is then burned “sightless” (unless in the dark when a light blue flame is visible.      The smell???   Still some small amount of volitiles coming off,     So, if pyrloysis is finish

 

2.  The large crack near the bottom is letting in  air.  If there is any fire there, (such as if sparks or embers dropped down from a top-lit fire) it will make char right there and the char will burn at forge temperature and give the red metal.    Not desirable. 

 

Paul

 

Doc / Dr TLUD / Paul S. Anderson, PhD --- Website:   www.drtlud.com

         Email:  psanders@...       Skype:   paultlud

         Phone:  Office: 309-452-7072    Mobile & WhatsApp: 309-531-4434

Exec. Dir. of Juntos Energy Solutions NFP    Go to: www.JuntosNFP.org 

Inventor of RoCC kilns for biochar and energy:  See  www.woodgas.com

Author of “A Capitalist Carol” (free digital copies at www.capitalism21.org)

         with pages 88 – 94 about solving the world crisis for clean cookstoves.

 

From: main@Biochar.groups.io <main@Biochar.groups.io> On Behalf Of Dick Gallien via groups.io
Sent: Thursday, September 10, 2020 12:17 PM
To: main@biochar.groups.io
Subject: Re: [Biochar] Preventing escaping gases

 

[This message came from an external source. If suspicious, report to abuse@...]

Frank's kiln insulation suggestion.   The huge pile of green, damp wood chips, would surely be more than dried, if not catching fire, by being stacked over the horizontal , 30' long charring turtle/tank for a few wks. and then replaced with more.  Lighting a few ft. of dried chips on the floor of the turtle/tank wouldn't seem to provide a flame cap, as with brush.  Would filling the turtle/tank with dry chips and lighting the top equal any biochar, or just smoke and ash ?? 

Hugh's Lemonade.  The Farm is between the vulture eyed DNR Game Warden, who lives just up the valley and town.  He would've immediately spotted the flame cap in the big trench, but if we'd have known Hugh's recipe, we'd have innocently   been making lemonade after 4 pm .  There's seldom any smoke, after the flame cap settles down, only the sightless, acrid smell of pyrolysis.

 

Hugh/Paul/Anyone, I've read that the chips in a large Jolly Rogers, don't burn  evenly, so collapse.  When I burned some brush in the 10' dia X 30' vertical tank, there was a 1/2 crack at the bottom of the 7'X7'X 7/8" steel door, that quickly became red hot on the lower 2' until clay was packed against the crack.  What experimental combinations would you suggest, with piles of wood chips and brush ?   .  .https://www.youtube.com/watch?v=Kg95KYrH8PI     Thanks, Dick

 

 

 

 

 

On Wed, Sep 9, 2020 at 10:15 PM Dick Gallien via groups.io <dickgallien=gmail.com@groups.io> wrote:

Beautiful Nando,

 When the tank/turtle is rolled onto it's 6'X 30' belly and it's hot gases rise to it's 8' top and then are forced down along each side, into the charring mass, how much of the pressure build up, would you expect to be reduced by burning those gases?  Rather than interrupt the pyrolysis cycle by removing gases from the top, where would you suggest a pipe be placed, to balance the pressure?

 

The sealed 55 ga barrel of "waste wood", set over a wood fire, with the 3/8" hole flaming skyward vs retorting, should produce a little wonder.among visitors.

 

In this country, where most urban organic materials are officially labeled: "wood waste", "food waste", "yard waste" and "human waste", to be burned, buried, flushed or landfilled, is blindly accepted by most.  Only fools would be so determined, while finding fun/excitement in trying to turn "wood waste", which is being very efficiently disposed of across this country with matches and lighters into biochar, which can benefit healthy soil and the life that depends on it for hundreds to thousands of years.

 

The price/maintenance of whole tree chippers is out of sight for most..  Logs not good for lumber or firewood (I've heated only with wood for 54 yrs)  can be split,  but until processes are ironed out, the intense heat and patience, with no down dizing, will result in some biochar. 

 

I mentioned to Hugh a few yrs. ago about the trench into a clay bank, 24' W 12'D X60', with brush stacked 10' above the upper ground level, lit on top and when burned down, I spread two 1500 ga. tanks of creek water on it and Sue ran 4 hose sprinklers continuously for 11 days, with a steady stream of clear water running out the lower end.  Hugh said that water would've had a slight lemon taste.  Sue, who has always said "It worked !!", after I dozed it shut, just said the only time there was the acrid smell was when I turned the hose off (which is an interesting thought) in that when the DNR game warden visited in June about a pyrolysis complaint and we can have no smoke or fumes other than between 8 and 4. Might 2 or 3 fine spraying nozzles over the 10' dia X 30' tank top hold the authorities off, while we consult with all of you?  

 

My goal is to mix the biochar in compost and spread it on the farm fields.  If any microbes complain about their residence I'll suggest they visit the majority of Mid West farm fields, that are dead/over dosed on chem's and headed for the Gulf.  The 11' wide dozer blade would  easily make a trench of that width.  When the brush was burned down and I've done that with wet compost, dozed dirt or compost over the burn without the tracks touching the pyrolysizing covered pile.  The pyrolysis fumes will continue, so we could test light hosing; however, wouldn't the toxicity of the pyrolysis gases be trapped in the covering of dirt or compost ?.

 

Eliminating smoke and fumes after 4pm is essential--because I've poked the DNR Forestry Dept..  We have a 1500 gallon liquid manure tank and a nearby trout stream, but a flooded trench would be an impossible mud hole.  The bricks this house was built from came from an adjoining brickyard.  

 

I don't remember in photos of large kilns built into slopes in S.A., with condensate being collected from chimney pipes on the above slope, whether they bothered to burn off the fumes.   

Thanks for your thoughts and suggestions.  Dick

   

 

On Wed, Sep 9, 2020 at 8:29 AM Nando Breiter <nando@...> wrote:

Susan, 

 

You might consider sorting the feedstock by size (cross-sectional thickness). Batch similar sizes together. It's like baking cookies. Bake all the same size together to ensure they are all baked to the same degree during a fixed amount of time they share together in the oven. If you bake bread and cookies together for the same amount of time, either the cookies will be burned or the bread underbaked. 

 

When you sort feedstock like this for a batch kiln, it ensures that the processing time is sufficient to transform it to char, while not excessively "baking" the smaller bits into gases. The large rounds might take a few days, the smaller branches a few hours. If the small branches are combined with the large rounds, they will be converted mostly to gases and ash. 


Kind regards,

 

Nando

 

Image removed by sender.

 

On Wed, Sep 9, 2020 at 12:49 AM Susan <suemegg@...> wrote:

Nando,

 

Thank you fir your reply.

 

Unfortunately, due to the nature of our feedstock size is very variable.  We operate a compost site, and loads come in via car trunk loads, pickup trucks and full size dump trucks.  So we have from small bundles of twigs up to tree trunks.

 

The varying size makes for a longer time frame for charring the wood waste.

 

We had considered attempting to flare off the gas and burn it, hoping that would problematic escape of gases and smoke into the atmosphere.

 

Susan

 

 

 

On Tue, Sep 8, 2020, 4:04 PM Nando Breiter <nando@...> wrote:

Susan,

 

The issue is that pyrolysis gases will take up vastly more space than the same atoms and molecules as solids, so pressure will quickly build up within the tank and the gases will have to go somewhere. 

Condensable gases may be trapped in the soil barrier if there is enough to cool them sufficiently to become liquids or solids before they escape. Non-condensables such as carbon monoxide, carbon dioxide and methane will escape into the atmosphere. If you see smoke leaking out, then that would be an indication that your soil barrier is not sufficient to condense them.

 

What you might consider is to create a small outlet for the gases at the end of the tank, and flare them off in an appropriately designed / jury-rigged burner.

 

If you are venting the gases and flaring them, and the brush consists of thin branches rather than thick tree trunks, I would assume that a batch would complete itself in hours rather than days. All that needs to happen is the heat generated needs to penetrate to the depth of each particle of biomass at temperatures over 300° C for the reaction to become exothermic. If the brush is really thin, then once you flip it over, pyrolysis will largely have already occurred and the char will simply need to cool in an oxygen starved environment under the half tank.

 

How thick are the branches of the "brush" you have available?

 

 

 

Image removed by sender.

 

On Tue, Sep 8, 2020 at 6:16 PM Susan <suemegg@...> wrote:

Scenario...   burn brush in a 20 to 30ft long half tank, cut lengthwise, then roll the tank over and put dirt along it to prevent escaping smoke and gases.  The charring process would continue for several days.  

 

How successful do you think our efforts to prevent polluting gases and smoke escaping would be?

 

Susan


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


Hugh McLaughlin
 

List:

Acetic acid is a major component of any wood vapor (wood vinegar?) stream. Usually it is the predominate odor in the freshly generated vapor. Once it condenses and cools, the vapor pressure of the acetic acid in water is low enough that other odors come through because they have a much lower odor threshold, overcoming the lower concentration in the wood vinegar.

Acetic acid vapors are very acrid, since they condense into the water-rich liquids in our mouths and eyes, lower the pH and trigger a painful threat response.. Been there, done that, don't want to go back. Breathing through a damp rag helps remove the acetic acid and reduces the risk and discomfort.

- Hugh

On Thursday, September 10, 2020, 3:02:51 PM EDT, Paul S Anderson <psanders@...> wrote:


Dick,

 

1.  What is the “the sightless, acrid smell of pyrolysis”

when the flame cap is gone?    Is it “char gasification”?  It is not pyrolysis.    

 

Sightless is the burning of char which is making CO that is then burned “sightless” (unless in the dark when a light blue flame is visible.      The smell???   Still some small amount of volitiles coming off,     So, if pyrloysis is finish

 

2.  The large crack near the bottom is letting in  air.  If there is any fire there, (such as if sparks or embers dropped down from a top-lit fire) it will make char right there and the char will burn at forge temperature and give the red metal.    Not desirable. 

 

Paul

 

Doc / Dr TLUD / Paul S. Anderson, PhD --- Website:   www.drtlud.com

         Email:  psanders@...       Skype:   paultlud

         Phone:  Office: 309-452-7072    Mobile & WhatsApp: 309-531-4434

Exec. Dir. of Juntos Energy Solutions NFP    Go to: www.JuntosNFP.org 

Inventor of RoCC kilns for biochar and energy:  See  www.woodgas.com

Author of “A Capitalist Carol” (free digital copies at www.capitalism21.org)

         with pages 88 – 94 about solving the world crisis for clean cookstoves.

 

From: main@Biochar.groups.io <main@Biochar.groups.io> On Behalf Of Dick Gallien via groups.io
Sent: Thursday, September 10, 2020 12:17 PM
To: main@biochar.groups.io
Subject: Re: [Biochar] Preventing escaping gases

 

[This message came from an external source. If suspicious, report to abuse@...]

Frank's kiln insulation suggestion.   The huge pile of green, damp wood chips, would surely be more than dried, if not catching fire, by being stacked over the horizontal , 30' long charring turtle/tank for a few wks. and then replaced with more.  Lighting a few ft. of dried chips on the floor of the turtle/tank wouldn't seem to provide a flame cap, as with brush.  Would filling the turtle/tank with dry chips and lighting the top equal any biochar, or just smoke and ash ?? 

Hugh's Lemonade.  The Farm is between the vulture eyed DNR Game Warden, who lives just up the valley and town.  He would've immediately spotted the flame cap in the big trench, but if we'd have known Hugh's recipe, we'd have innocently   been making lemonade after 4 pm .  There's seldom any smoke, after the flame cap settles down, only the sightless, acrid smell of pyrolysis.

 

Hugh/Paul/Anyone, I've read that the chips in a large Jolly Rogers, don't burn  evenly, so collapse.  When I burned some brush in the 10' dia X 30' vertical tank, there was a 1/2 crack at the bottom of the 7'X7'X 7/8" steel door, that quickly became red hot on the lower 2' until clay was packed against the crack.  What experimental combinations would you suggest, with piles of wood chips and brush ?   .  .https://www.youtube.com/watch?v=Kg95KYrH8PI     Thanks, Dick

 

 

 

 

 

On Wed, Sep 9, 2020 at 10:15 PM Dick Gallien via groups.io <dickgallien=gmail.com@groups.io> wrote:

Beautiful Nando,

 When the tank/turtle is rolled onto it's 6'X 30' belly and it's hot gases rise to it's 8' top and then are forced down along each side, into the charring mass, how much of the pressure build up, would you expect to be reduced by burning those gases?  Rather than interrupt the pyrolysis cycle by removing gases from the top, where would you suggest a pipe be placed, to balance the pressure?

 

The sealed 55 ga barrel of "waste wood", set over a wood fire, with the 3/8" hole flaming skyward vs retorting, should produce a little wonder.among visitors.

 

In this country, where most urban organic materials are officially labeled: "wood waste", "food waste", "yard waste" and "human waste", to be burned, buried, flushed or landfilled, is blindly accepted by most.  Only fools would be so determined, while finding fun/excitement in trying to turn "wood waste", which is being very efficiently disposed of across this country with matches and lighters into biochar, which can benefit healthy soil and the life that depends on it for hundreds to thousands of years.

 

The price/maintenance of whole tree chippers is out of sight for most..  Logs not good for lumber or firewood (I've heated only with wood for 54 yrs)  can be split,  but until processes are ironed out, the intense heat and patience, with no down dizing, will result in some biochar. 

 

I mentioned to Hugh a few yrs. ago about the trench into a clay bank, 24' W 12'D X60', with brush stacked 10' above the upper ground level, lit on top and when burned down, I spread two 1500 ga. tanks of creek water on it and Sue ran 4 hose sprinklers continuously for 11 days, with a steady stream of clear water running out the lower end.  Hugh said that water would've had a slight lemon taste.  Sue, who has always said "It worked !!", after I dozed it shut, just said the only time there was the acrid smell was when I turned the hose off (which is an interesting thought) in that when the DNR game warden visited in June about a pyrolysis complaint and we can have no smoke or fumes other than between 8 and 4. Might 2 or 3 fine spraying nozzles over the 10' dia X 30' tank top hold the authorities off, while we consult with all of you?  

 

My goal is to mix the biochar in compost and spread it on the farm fields.  If any microbes complain about their residence I'll suggest they visit the majority of Mid West farm fields, that are dead/over dosed on chem's and headed for the Gulf.  The 11' wide dozer blade would  easily make a trench of that width.  When the brush was burned down and I've done that with wet compost, dozed dirt or compost over the burn without the tracks touching the pyrolysizing covered pile.  The pyrolysis fumes will continue, so we could test light hosing; however, wouldn't the toxicity of the pyrolysis gases be trapped in the covering of dirt or compost ?.

 

Eliminating smoke and fumes after 4pm is essential--because I've poked the DNR Forestry Dept..  We have a 1500 gallon liquid manure tank and a nearby trout stream, but a flooded trench would be an impossible mud hole.  The bricks this house was built from came from an adjoining brickyard.  

 

I don't remember in photos of large kilns built into slopes in S.A., with condensate being collected from chimney pipes on the above slope, whether they bothered to burn off the fumes.   

Thanks for your thoughts and suggestions.  Dick

   

 

On Wed, Sep 9, 2020 at 8:29 AM Nando Breiter <nando@...> wrote:

Susan, 

 

You might consider sorting the feedstock by size (cross-sectional thickness). Batch similar sizes together. It's like baking cookies. Bake all the same size together to ensure they are all baked to the same degree during a fixed amount of time they share together in the oven. If you bake bread and cookies together for the same amount of time, either the cookies will be burned or the bread underbaked. 

 

When you sort feedstock like this for a batch kiln, it ensures that the processing time is sufficient to transform it to char, while not excessively "baking" the smaller bits into gases. The large rounds might take a few days, the smaller branches a few hours. If the small branches are combined with the large rounds, they will be converted mostly to gases and ash. 


Kind regards,

 

Nando

 

Image removed by sender.

 

On Wed, Sep 9, 2020 at 12:49 AM Susan <suemegg@...> wrote:

Nando,

 

Thank you fir your reply.

 

Unfortunately, due to the nature of our feedstock size is very variable.  We operate a compost site, and loads come in via car trunk loads, pickup trucks and full size dump trucks.  So we have from small bundles of twigs up to tree trunks.

 

The varying size makes for a longer time frame for charring the wood waste.

 

We had considered attempting to flare off the gas and burn it, hoping that would problematic escape of gases and smoke into the atmosphere.

 

Susan

 

 

 

On Tue, Sep 8, 2020, 4:04 PM Nando Breiter <nando@...> wrote:

Susan,

 

The issue is that pyrolysis gases will take up vastly more space than the same atoms and molecules as solids, so pressure will quickly build up within the tank and the gases will have to go somewhere. 

Condensable gases may be trapped in the soil barrier if there is enough to cool them sufficiently to become liquids or solids before they escape. Non-condensables such as carbon monoxide, carbon dioxide and methane will escape into the atmosphere. If you see smoke leaking out, then that would be an indication that your soil barrier is not sufficient to condense them.

 

What you might consider is to create a small outlet for the gases at the end of the tank, and flare them off in an appropriately designed / jury-rigged burner.

 

If you are venting the gases and flaring them, and the brush consists of thin branches rather than thick tree trunks, I would assume that a batch would complete itself in hours rather than days. All that needs to happen is the heat generated needs to penetrate to the depth of each particle of biomass at temperatures over 300° C for the reaction to become exothermic. If the brush is really thin, then once you flip it over, pyrolysis will largely have already occurred and the char will simply need to cool in an oxygen starved environment under the half tank.

 

How thick are the branches of the "brush" you have available?

 

 

 

Image removed by sender.

 

On Tue, Sep 8, 2020 at 6:16 PM Susan <suemegg@...> wrote:

Scenario...   burn brush in a 20 to 30ft long half tank, cut lengthwise, then roll the tank over and put dirt along it to prevent escaping smoke and gases.  The charring process would continue for several days.  

 

How successful do you think our efforts to prevent polluting gases and smoke escaping would be?

 

Susan


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


Paul S Anderson
 

Dear Nando and Sue,

 

I respond about Nando’s suggestion that is based on Sue’s thoughts.   

 

Spoiler alert:  The response written here became long, and I conclude that the method will not work in a reliable manner.  Skip to the “Conclusion” if you want the verdict.   Or read here if you want the reasoning.

 

If I understand it correctly, there is a trench mounded up with biomass in it, with a half-cylinder (cut lengthwise) over that trench.  Air entrance and ignition are at one end and exit of emissions is at the other end.   Use of blowers is allowed or chimney to accomplish draft.   But it is a LOW flow of air (oxygen), not a raging fire fed by blasted air.    For this discussion, we will ignore any possible leaks into or out of the configuration.  

 

Did I state the situation correctly.   If not please correct any misstatements above.

 

This is essentially a horizontal  updraft unit (I hesitate to call  it a gasifier, but sort of a pyrolyzer) with fire at the bottom.    If it were in a vertical position, there would be  one major difference.   In a vertical container, the biomass falls by gravity to fill in the gaps at the edges.   But in the horizontal one, gravity pulls the biomass downward from the inside of the top of the cylinder, creating a gap which will be the path of least resistance for any gases to flow from the inlet (ignition) end to the outlet end.  But I will grant that everywhere inside the cylinder there will  be the emission gases, not pockets of fresh air.

 

Ignite it and let it draw for a few minutes so that it is certainly ignited.

 

Then, some new air enters.   An appropriate small amount with a continual flow.   It is drawn toward the exit end.   It will encounter the zone where the initial  fire has been burning and has been giving off emission gases that are pulled/pushed to the exit.   The  fresh air will come into contact with any combustible gases, helping them to be burned, giving more heat and some CO2 and some H2O (and other stuff, probably smoky).   Some of the incoming air will reach the solid biomass fuel, which is by now partially pyrolyzed and giving off some combustible gases through the created layer of charcoal around the pieces of biomass.  

 

Some of the air can reach the hot char (where pyrolysis is completed) and will make that char glow red, burning the char (called char gasification), creating CO  (combustible carbon monoxide) which may or may not be combusted with the incoming air (requires spark and sufficient temperature).   This will continue on and on and on.    The incoming air meets the zone of ignition.   The air (oxygen) cannot get through that zone.  Beyond the zone, there is a flow of hot gases, some of which are “smokey”, plus water vapor from combustion and mostly from any final drying of the biomass in or near that fire zone.

 

Beyond the fire zone, the hot emission gases move through the biomass (or worse, if the gases bypass the biomass by taking the passageway at the top edge of the tank, but ignore that for the moment).   The hot gases will do the necessary drying of the biomass.   Even if the biomass is quite dry at 10 to 20 percent moisture content (MC), there is still moisture coming off of the biomass.   That moisture moves along with the other gases toward the exit end.  

 

2 things can occur with that moisture.  A.  it stays as a vapor and exits this cylinder.   Or B, if the cylinder is long enough and the outside temperature is cold around the tank, the moisture can condense, causing increased wetness at the far end of the pile of biomass.   Not to worry, when the fire eventually gets to that area with the condensed moisture, it just needs to have enough extra heat to re-vaporize the moisture to above 100 deg C.  

 

Expect that all of the gases exiting the cylinder are NON-combustible until all of the biomass has reached minimum temperature for pyrolysis, above 300 degree C.  (and still would be 250 deg C lower than the desired 550 C for the char making, but ignore that for the time being.).  

 

During all of this, there is the consumption of the biomass at the combustion end with the air inlet.   Not just pyrolysis offgases but burning of the charcoal that is being created.   The air reaches the hot charcoal first.   The char must be consumed, and that gives the heat  that goes to the far  end of the cylinder (whether horizontal or vertical).  

 

Eventually, there can be combustible gases exiting the  far end of the  chamber.   Direct them wherever you desire to have them combusted to give heat to drive the pyrolysis.   To combust them requires additional oxygen (air), so they cannot be just simply redirected back into the cylinder.   But the burning gases would  not be a fire on the outside of the container (as if this were a retort) because the bottom half is earth or  dirt or concreate lined surface that is the formation of the trench.  

 

Maybe a feedback of those gases to the ignition end.   Feed in the gases and some air and burn  the gases there.   Good.   More heat, and not burning the biomass or charcoal any longer.   This heat has to reach all  of the biomass and bring the biomass to the desired temperature (say 450 to 550 C?).   Otherwise, there will be different qualities of biochar created in that batch, including possibly even some merely torrefied wood.  

 

So now, remember this:   there  is a passageway for hot gases up near the inside of the top of the inverted half cylinder, and there is a lot of biomass that is actually touching or within inches of the earth that forms the bottom of the chamber and keeps that biomass sufficiently cool to prevent pyrolysis or maybe even torrefaction or even full  drying.

 

*****

Conclusion:   Such a configuration may have produced some charcoal in  different efforts by different people.   But there is no evidence that the efforts were sufficiently successful to merit telling others about it, nor for launching a charcoal business.  Too many things are “sub-optimal” (a polite way to say “wrong”).   (If I am incorrect, the person(s) who solve such an issue of making quality biochar with such a simple method deserve all the praises and financial rewards that should flow to them.)

 

Recommendation:   If anyone produces such a configuration and puts it to use (at whatever size), please report back you experience, either favorable of unfavorable.    

 

And I do suggest that the trials should be done SMALL, such as with a 55 gallon half drum.   At least then you will not have a 30 foot long pile of biomass that is 8 to 10 ft high under a few tons of railway tank car steel, not to mention the costs and efforts to have made such a giant experiment. 

 

Paul

 

Doc / Dr TLUD / Paul S. Anderson, PhD --- Website:   www.drtlud.com

         Email:  psanders@...       Skype:   paultlud

         Phone:  Office: 309-452-7072    Mobile & WhatsApp: 309-531-4434

Exec. Dir. of Juntos Energy Solutions NFP    Go to: www.JuntosNFP.org 

Inventor of RoCC kilns for biochar and energy:  See  www.woodgas.com

Author of “A Capitalist Carol” (free digital copies at www.capitalism21.org)

         with pages 88 – 94 about solving the world crisis for clean cookstoves.

 

From: main@Biochar.groups.io <main@Biochar.groups.io> On Behalf Of Nando Breiter via groups.io
Sent: Thursday, September 10, 2020 12:20 PM
To: main@biochar.groups.io
Subject: Re: [Biochar] Preventing escaping gases

 

[This message came from an external source. If suspicious, report to abuse@...]

Dick,

 

I'll try to answer your questions inline below.

 

 When the tank/turtle is rolled onto it's 6'X 30' belly and it's hot gases rise to it's 8' top and then are forced down along each side, into the charring mass, how much of the pressure build up, would you expect to be reduced by burning those gases? 

All of the gases would be flared, and there would only be a very minimal pressure difference. Our 10 m3 batch kiln uses 8" heat and corrosion resistant stainless steel tubing to transport the gases to the flare, which is up on a stand to keep the flame out of harm's way.

 

Rather than interrupt the pyrolysis cycle by removing gases from the top, where would you suggest a pipe be placed, to balance the pressure?


Pyrolysis won't be interrupted. Keep in mind that the gases will escape in any case. 

To keep the pyrolysis gases within a pyrolysis retort, you would need a very expensive kiln that could withstand extremely high pressures, easily costing 10's of millions of dollars for the capacity we are discussing. Nikolaus Foidl tried to build a small high pressure retort, and he ran into a world of trouble getting the access door for the biomass to seal. I don't know what the upper range is of a perfectly sealed retort, but Nikolaus was trying to hit 50 bar, if I remember correctly, and his initial tests at about 500° C saw the seal fail at some abysmally low value of perhaps 1.5 - 2 bar. I think the problem here is he wanted a large diameter access hatch that would allow for the easy loading and unloading of biomass, rather than a manhole sized access hatch where it would be "easier" to maintain the needed seal to reach 50 bar. His design had redundant relief values, and he intended to fully bury it in a containment pit in case of structural failure, which would lead to a massive explosion.

 

With the approach you've proposed, you aren't anywhere near being able to contain pyrolysis gases. So there will be virtually no pressure buildup under the tank. If there is for a moment, the gases will create one or more channels out of the kiln through the soil.

 

I'm proposing to create an easy escape route so we can flare them, instead of allowing them to escape through the soil. Once they are flared, you'll have an absolutely transparent emission of CO2 and H2O from the stack, like the emissions from a natural gas flame, rather than a mix of CO2, CO, CH4 (methane) perhaps some H2 (hydrogen) and a wide variety of complex hydrocarbons as gases or tar microdroplets. 

As you have heard, pyrolysis is exothermic. What that fancy word means is that as the biomass thermally decomposes at temperatures above 300° C, oxygen and carbon atoms, or carbon based molecules, and eventually hydrogen, are released, and as these recombine, either within the biomass particle on their way out, or just outside of the biomass particle, that reaction gives off heat. It is that exothermic heat that maintains a pyrolysis reaction in a batch process such as you are proposing once access to air is limited. 

The exothermic reaction in pyrolysis is the same reaction we call a fire, oxygen combining with carbon and or hydrogen, except that the amount of available oxygen is limited to that which is being decomposed from the biomass. It is that limit of oxygen that prevents the entire batch from being oxidized. That limit also self-regulates the temperature of a pyrolysis batch in a well designed kiln that conserves heat to between 450° - 550°C. Why? Because there is not enough oxygen in the biomass to elevate the temperature higher than that. 


This is also why a pyrolysis reaction in a closed batch stops; it runs out of oxygen.

Whether or not the pyrolysis reaction is self-sustaining depends on if there is sufficient exothermic heat available to continue to heat the remaining un-pyrolyzed biomass above 300° C. The critical factor here is how dry the biomass is. Evaporating water out of biomass cools the biomass down, so the entirety of a biomass particle will not heat above 99° C until all the water is evaporated out of it (in a simple kiln operating at atmospheric pressure). So if you start a batch, close the lid, and the temperature drops off, the biomass is still too wet for the reaction to be self-sustaining. 

 

In this case, which I certainly think will happen in your situation, what you could try is that rather than open the lid again, just let some air into it, from the end opposite the gas flare burner. You should hopefully have sufficient draft on the chimney to pull air into the kiln. Let a bit of air into the kiln to bring the temperature up to dry the wood. You don't want a roaring fire. A charred surface forms somewhat of a seal that makes it harder for evaporating water to escape.

So now we are getting very close to the Adam retort design. Here's an outline of a further evolution of Susan's idea that will be much safer and efficient to operate, while producing a reasonably uniform biochar with the minimum amount of biomass consumed to produce the heat necessary, and very little to no emissions besides CO2 and water vapor.

Sue's Evolved Biochar Kiln Concept - Details to be refined

  • Cut the tank in half lengthwise. 
  • (Optionally) dig a ramped trench that is slightly shorter and narrower than the tank, so that the tank will fit over the trench as a cover. After the batch is finished, a tractor or front end loader should be able to drive into the trench to remove the finished char
  • Fix the tank-half to the side of the trench so that it hinges closed over the trench to act as a cover. The hinge mechanism could use heavy chain welded to the tank and rebar driven into the ground. We only need to ensure the tank-half stays in the proper position as it is being pulled over.
  • Fix a longer heavy chain or better a cable to the other outer lip of the retort lid (tank-half) to be used to pull the lid over the trench with a tractor. If the cable is light enough to be tossed over the tank-half, then the same cable could be used for opening and closing the lid. Otherwise, 2 cables can be used, one to close and one to open.
  • Steel or wooden braces could be used to prevent the retort lid from tipping all the way over when it is opened. It should open past 90° so it stays put. If it is braced open, like the lid on a treasure chest, the cable should be anchored to prevent it from blowing closed in a strong wind.
  • The kiln is loaded with wood, generally oriented along the length of the trench and heaped to fill the space that will be enclosed by the lid, and the lid is then closed. No open fire is used.
  • The kiln is designed to encourage a pyrolysis front to move from one end to the other along the length of the half-tank / trench assembly. 
  • On the starting end, there is an opening in the tank near the bottom connected to a tube. This tube can be closed off, allow air into it, or allow hot flue gas from a wood fire into it. (If a large "stove" with a wood fire in it is used to initially heat the kiln, then that much less wood in the batch will be consumed to provide the heat necessary. So this is a trade off between maximizing the batch output or making operation more simple.)
  • At the other end, a tube is fixed to the tank-half. Midway up should be fine. This tube angles downward into a combustion chamber which will be used to flare the gases. The angle is meant to allow condensate that may form to run down into the combustion chamber. It has a tall chimney on it to encourage a draft to gently pull hot gases through the kiln. We can call this the gas burner.
  • Ideally, the gas burner should be moveable so that when the retort is closed and the tubing is fixed to the half-tank lid, the gas burner position can be adjusted as necessary to attach the other end of the tube to it. If the trench is ramped to allow machinery access for unloading, then the gas burner needs to be either mobile enough to easily move it out of place or positioned off center so it is out of the way of the ramp.
  • In the initial stages of a batch, the gas burner flame will need to be supported to remain lit because of the moisture content of the gas. What this means is that the humidity in the gas will extinguish the flame, largely because it is too dilute to sustain itself. There are options here, the easiest of which may be to burn a little wood in this chamber. The plus is this would be a simple solution, the minus is that someone may need to add wood every hour or so.
  • At the other end of the kiln, there is optionally what I will call the wood stove, to keep it simple. Wood is loaded into it, and the flue gases are directed into the kiln and drawn through either by a small squirrel cage blower if the intent is to simply dry the batch, or a small wood fire is lit in the "gas burner" to create a draft that will draw the moisture out of the kiln if the intent is to initiate pyrolysis more quickly
  • Easy startup of pyrolysis will depend on having thoroughly dry wood at the starting end. Ideally, smaller, pre-dried branches are loaded at the starting end. The core idea here is that once pyrolysis begins at the starting end, the heat generated will continue to dry and heat the feedstock ahead of the pyrolysis front, which will slowly advance from the starting end of the kiln to the finish point nearest the gas burner. So, operation is in several stages:
  1. Pre-drying the wood, particularly at the starting end. Smaller starting end wood can be dried outside of the kiln before loading it if more convenient. Or a large wood stove can be used to inject heat into the kiln to dry in particular the first 3-5 feet of wood. You can think of this as pyrolysis kindling. The drier our pyrolysis kindling, and the more we have of it at the leading end, the easier it will be to initiate pyrolysis. 
  2. Light the starting wood on fire at the starting end, allowing air into the kiln and controlling the amount of air to keep the flame gentle. At this stage, a wood (or propane or wood pellet ...) fire is started in the gas burner to provide some draft to pull the gases through and burn off any flammable gases coming out of Sue's kiln. The objective is to raise temperatures at the starting end sufficiently for pyrolysis to be maintained exothermically.
  3. Once pyrolysis can be maintained without air being added at the starting end, the air inlet is closed. Wood is occasionally added to the gas burner to help maintain the flare.
  4. If temperatures begin to fall in the kiln, the air inlet is slightly opened again to bring them up. Whether or not the exothermically available heat is sufficient to dry the wood ahead of the pyrolysis front is dependent on the moisture content and thickness of the wood.
  5. Once most of the moisture is driven out of the wood, the flare will continue to burn even without support. So it can operate overnight without being attended to if wood has been used to support the flame.

This approach is based on the principals at play in one of our proven vertical batch kiln designs that has been built and operated a number of times in South America. Because it is designed to allow a pyrolysis front to move through the batch, the amount of burnable gas it will produce remains at consistent, manageable levels. A probe penetrating the kiln lid would measure the internal temperature, and the aim would be to keep it below 450°-550 C or so. More than that and too much air is entering the kiln. 

 

The biomass that still needs to dry will not dry that much more quickly if higher temperatures are used. Higher temps will also corrode the tank more quickly. The velocity of drying will depend more on the rate at which water vapor laden gas is removed than the heat used. We will be depending primarily on the gases being produced within the kiln to develop the pressure needed to push them out through the burner.

 

Now, it may seem to be much more effective to leave the lid open light the whole pile on fire, but in this case, most of the heat being produced is immediately lost to the atmosphere, so we are transforming a significant portion of our biomass to CO2 for no useful purpose. And no matter how much heat is applied at the surface of a large log, drying simply takes time. Those 2 facts together mean that much more of the biomass will be burned to dry the biomass in an open flame approach than is actually necessary. Yes, you could produce a relatively small pile of glowing embers at the bottom of the trench after a long open fire, and then close the lid completely and just let the heat dissipate. Then no burner would be needed. But, to produce the same amount of char as you will get from a closed lid pyrolysis front approach, you'll need several batches and need much more wood.

 

When we close the half-tank lid to this trench kiln from the beginning of the batch, and only add air very judiciously, the heat we are producing from the addition of air is used very efficiently. 

So that's Sue's evolved biochar kiln in a nutshell. Much safer, much more efficient in its use of heat and wood, minimized CO2 emissions compared to char produced, and with the addition of the ramped trench, hopefully much easier to unload than a large pit while still maximizing the batch capacity under a half tank.

I'll leave it here for now.






 

The sealed 55 ga barrel of "waste wood", set over a wood fire, with the 3/8" hole flaming skyward vs retorting, should produce a little wonder.among visitors.

 

In this country, where most urban organic materials are officially labeled: "wood waste", "food waste", "yard waste" and "human waste", to be burned, buried, flushed or landfilled, is blindly accepted by most.  Only fools would be so determined, while finding fun/excitement in trying to turn "wood waste", which is being very efficiently disposed of across this country with matches and lighters into biochar, which can benefit healthy soil and the life that depends on it for hundreds to thousands of years.

 

The price/maintenance of whole tree chippers is out of sight for most..  Logs not good for lumber or firewood (I've heated only with wood for 54 yrs)  can be split,  but until processes are ironed out, the intense heat and patience, with no down dizing, will result in some biochar. 

 

I mentioned to Hugh a few yrs. ago about the trench into a clay bank, 24' W 12'D X60', with brush stacked 10' above the upper ground level, lit on top and when burned down, I spread two 1500 ga. tanks of creek water on it and Sue ran 4 hose sprinklers continuously for 11 days, with a steady stream of clear water running out the lower end.  Hugh said that water would've had a slight lemon taste.  Sue, who has always said "It worked !!", after I dozed it shut, just said the only time there was the acrid smell was when I turned the hose off (which is an interesting thought) in that when the DNR game warden visited in June about a pyrolysis complaint and we can have no smoke or fumes other than between 8 and 4. Might 2 or 3 fine spraying nozzles over the 10' dia X 30' tank top hold the authorities off, while we consult with all of you?  

 

My goal is to mix the biochar in compost and spread it on the farm fields.  If any microbes complain about their residence I'll suggest they visit the majority of Mid West farm fields, that are dead/over dosed on chem's and headed for the Gulf.  The 11' wide dozer blade would  easily make a trench of that width.  When the brush was burned down and I've done that with wet compost, dozed dirt or compost over the burn without the tracks touching the pyrolysizing covered pile.  The pyrolysis fumes will continue, so we could test light hosing; however, wouldn't the toxicity of the pyrolysis gases be trapped in the covering of dirt or compost ?.

 

Eliminating smoke and fumes after 4pm is essential--because I've poked the DNR Forestry Dept..  We have a 1500 gallon liquid manure tank and a nearby trout stream, but a flooded trench would be an impossible mud hole.  The bricks this house was built from came from an adjoining brickyard.  

 

I don't remember in photos of large kilns built into slopes in S.A., with condensate being collected from chimney pipes on the above slope, whether they bothered to burn off the fumes.   

Thanks for your thoughts and suggestions.  Dick

   

 

On Wed, Sep 9, 2020 at 8:29 AM Nando Breiter <nando@...> wrote:

Susan, 

 

You might consider sorting the feedstock by size (cross-sectional thickness). Batch similar sizes together. It's like baking cookies. Bake all the same size together to ensure they are all baked to the same degree during a fixed amount of time they share together in the oven. If you bake bread and cookies together for the same amount of time, either the cookies will be burned or the bread underbaked. 

 

When you sort feedstock like this for a batch kiln, it ensures that the processing time is sufficient to transform it to char, while not excessively "baking" the smaller bits into gases. The large rounds might take a few days, the smaller branches a few hours. If the small branches are combined with the large rounds, they will be converted mostly to gases and ash. 


Kind regards,

 

Nando

 

 

On Wed, Sep 9, 2020 at 12:49 AM Susan <suemegg@...> wrote:

Nando,

 

Thank you fir your reply.

 

Unfortunately, due to the nature of our feedstock size is very variable.  We operate a compost site, and loads come in via car trunk loads, pickup trucks and full size dump trucks.  So we have from small bundles of twigs up to tree trunks.

 

The varying size makes for a longer time frame for charring the wood waste.

 

We had considered attempting to flare off the gas and burn it, hoping that would problematic escape of gases and smoke into the atmosphere.

 

Susan

 

 

 

On Tue, Sep 8, 2020, 4:04 PM Nando Breiter <nando@...> wrote:

Susan,

 

The issue is that pyrolysis gases will take up vastly more space than the same atoms and molecules as solids, so pressure will quickly build up within the tank and the gases will have to go somewhere. 

Condensable gases may be trapped in the soil barrier if there is enough to cool them sufficiently to become liquids or solids before they escape. Non-condensables such as carbon monoxide, carbon dioxide and methane will escape into the atmosphere. If you see smoke leaking out, then that would be an indication that your soil barrier is not sufficient to condense them.

 

What you might consider is to create a small outlet for the gases at the end of the tank, and flare them off in an appropriately designed / jury-rigged burner.

 

If you are venting the gases and flaring them, and the brush consists of thin branches rather than thick tree trunks, I would assume that a batch would complete itself in hours rather than days. All that needs to happen is the heat generated needs to penetrate to the depth of each particle of biomass at temperatures over 300° C for the reaction to become exothermic. If the brush is really thin, then once you flip it over, pyrolysis will largely have already occurred and the char will simply need to cool in an oxygen starved environment under the half tank.

 

How thick are the branches of the "brush" you have available?

 

 

 

 

On Tue, Sep 8, 2020 at 6:16 PM Susan <suemegg@...> wrote:

Scenario...   burn brush in a 20 to 30ft long half tank, cut lengthwise, then roll the tank over and put dirt along it to prevent escaping smoke and gases.  The charring process would continue for several days.  

 

How successful do you think our efforts to prevent polluting gases and smoke escaping would be?

 

Susan


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


Nando Breiter
 

Hello Paul,

Thanks for your review of the idea. I would fully agree that varying char qualities would be produced, but since Dick's use is as a soil amendment, that would be perfectly acceptable, particularly in light of the low capital investment involved. I would also agree that it would probably sense to try the idea out with a smaller tank. That said, the idea is similar to the Adam retort, and that's been demonstrated to work. The Adam retort will have better insulating qualities, but ... much of the charcoal made in the world is under earthen heaps. 

Recondensation could become an issue, if the gas in the tank was allowed to cool sufficiently. What I anticipate is that the gas flow rate through the kiln will be low enough that it will tend to function more as an oven. So I'm less concerned about heat not penetrating toward the base of the heap. 

What could be done is automate the air intake so that it opens when the internal temperature measure in the tank falls below, say 300° and the moisture content of the gas remains high enough to signal that water is still being evaporated from the feedstock. Air intake would close again when gas temps reach, say, 550 or 600° C. Once gas moisture content remains "low", the air intake remains closed, allowing exothermically driven pyrolysis to complete the process.

I also think the idea to try it at smaller scale is good, but a 55 gallon drum would be too small in my opinion to get a sense of how it works. 

If the gas outlet becomes clogged with condensed tar, smoke will start rising out of the soil surrounding the kiln - so no catastrophic failure in that case. The tank could be lifted if the downstream gas handling process fails in some other way to allow the batch to revert to a bonfire, and then closed again when the flames had begun to die down to embers.

The fallback if the experiment completely fails would be to make a bonfire and close the half-tank over it to extinguish the flames.





On Sat, Sep 12, 2020 at 4:31 AM Paul S Anderson <psanders@...> wrote:

Dear Nando and Sue,

 

I respond about Nando’s suggestion that is based on Sue’s thoughts.   

 

Spoiler alert:  The response written here became long, and I conclude that the method will not work in a reliable manner.  Skip to the “Conclusion” if you want the verdict.   Or read here if you want the reasoning.

 

If I understand it correctly, there is a trench mounded up with biomass in it, with a half-cylinder (cut lengthwise) over that trench.  Air entrance and ignition are at one end and exit of emissions is at the other end.   Use of blowers is allowed or chimney to accomplish draft.   But it is a LOW flow of air (oxygen), not a raging fire fed by blasted air.    For this discussion, we will ignore any possible leaks into or out of the configuration.  

 

Did I state the situation correctly.   If not please correct any misstatements above.

 

This is essentially a horizontal  updraft unit (I hesitate to call  it a gasifier, but sort of a pyrolyzer) with fire at the bottom.    If it were in a vertical position, there would be  one major difference.   In a vertical container, the biomass falls by gravity to fill in the gaps at the edges.   But in the horizontal one, gravity pulls the biomass downward from the inside of the top of the cylinder, creating a gap which will be the path of least resistance for any gases to flow from the inlet (ignition) end to the outlet end.  But I will grant that everywhere inside the cylinder there will  be the emission gases, not pockets of fresh air.

 

Ignite it and let it draw for a few minutes so that it is certainly ignited.

 

Then, some new air enters.   An appropriate small amount with a continual flow.   It is drawn toward the exit end.   It will encounter the zone where the initial  fire has been burning and has been giving off emission gases that are pulled/pushed to the exit.   The  fresh air will come into contact with any combustible gases, helping them to be burned, giving more heat and some CO2 and some H2O (and other stuff, probably smoky).   Some of the incoming air will reach the solid biomass fuel, which is by now partially pyrolyzed and giving off some combustible gases through the created layer of charcoal around the pieces of biomass.  

 

Some of the air can reach the hot char (where pyrolysis is completed) and will make that char glow red, burning the char (called char gasification), creating CO  (combustible carbon monoxide) which may or may not be combusted with the incoming air (requires spark and sufficient temperature).   This will continue on and on and on.    The incoming air meets the zone of ignition.   The air (oxygen) cannot get through that zone.  Beyond the zone, there is a flow of hot gases, some of which are “smokey”, plus water vapor from combustion and mostly from any final drying of the biomass in or near that fire zone.

 

Beyond the fire zone, the hot emission gases move through the biomass (or worse, if the gases bypass the biomass by taking the passageway at the top edge of the tank, but ignore that for the moment).   The hot gases will do the necessary drying of the biomass.   Even if the biomass is quite dry at 10 to 20 percent moisture content (MC), there is still moisture coming off of the biomass.   That moisture moves along with the other gases toward the exit end.  

 

2 things can occur with that moisture.  A.  it stays as a vapor and exits this cylinder.   Or B, if the cylinder is long enough and the outside temperature is cold around the tank, the moisture can condense, causing increased wetness at the far end of the pile of biomass.   Not to worry, when the fire eventually gets to that area with the condensed moisture, it just needs to have enough extra heat to re-vaporize the moisture to above 100 deg C.  

 

Expect that all of the gases exiting the cylinder are NON-combustible until all of the biomass has reached minimum temperature for pyrolysis, above 300 degree C.  (and still would be 250 deg C lower than the desired 550 C for the char making, but ignore that for the time being.).  

 

During all of this, there is the consumption of the biomass at the combustion end with the air inlet.   Not just pyrolysis offgases but burning of the charcoal that is being created.   The air reaches the hot charcoal first.   The char must be consumed, and that gives the heat  that goes to the far  end of the cylinder (whether horizontal or vertical).  

 

Eventually, there can be combustible gases exiting the  far end of the  chamber.   Direct them wherever you desire to have them combusted to give heat to drive the pyrolysis.   To combust them requires additional oxygen (air), so they cannot be just simply redirected back into the cylinder.   But the burning gases would  not be a fire on the outside of the container (as if this were a retort) because the bottom half is earth or  dirt or concreate lined surface that is the formation of the trench.  

 

Maybe a feedback of those gases to the ignition end.   Feed in the gases and some air and burn  the gases there.   Good.   More heat, and not burning the biomass or charcoal any longer.   This heat has to reach all  of the biomass and bring the biomass to the desired temperature (say 450 to 550 C?).   Otherwise, there will be different qualities of biochar created in that batch, including possibly even some merely torrefied wood.  

 

So now, remember this:   there  is a passageway for hot gases up near the inside of the top of the inverted half cylinder, and there is a lot of biomass that is actually touching or within inches of the earth that forms the bottom of the chamber and keeps that biomass sufficiently cool to prevent pyrolysis or maybe even torrefaction or even full  drying.

 

*****

Conclusion:   Such a configuration may have produced some charcoal in  different efforts by different people.   But there is no evidence that the efforts were sufficiently successful to merit telling others about it, nor for launching a charcoal business.  Too many things are “sub-optimal” (a polite way to say “wrong”).   (If I am incorrect, the person(s) who solve such an issue of making quality biochar with such a simple method deserve all the praises and financial rewards that should flow to them.)

 

Recommendation:   If anyone produces such a configuration and puts it to use (at whatever size), please report back you experience, either favorable of unfavorable.    

 

And I do suggest that the trials should be done SMALL, such as with a 55 gallon half drum.   At least then you will not have a 30 foot long pile of biomass that is 8 to 10 ft high under a few tons of railway tank car steel, not to mention the costs and efforts to have made such a giant experiment. 

 

Paul

 

Doc / Dr TLUD / Paul S. Anderson, PhD --- Website:   www.drtlud.com

         Email:  psanders@...       Skype:   paultlud

         Phone:  Office: 309-452-7072    Mobile & WhatsApp: 309-531-4434

Exec. Dir. of Juntos Energy Solutions NFP    Go to: www.JuntosNFP.org 

Inventor of RoCC kilns for biochar and energy:  See  www.woodgas.com

Author of “A Capitalist Carol” (free digital copies at www.capitalism21.org)

         with pages 88 – 94 about solving the world crisis for clean cookstoves.

 

From: main@Biochar.groups.io <main@Biochar.groups.io> On Behalf Of Nando Breiter via groups.io
Sent: Thursday, September 10, 2020 12:20 PM
To: main@biochar.groups.io
Subject: Re: [Biochar] Preventing escaping gases

 

[This message came from an external source. If suspicious, report to abuse@...]

Dick,

 

I'll try to answer your questions inline below.

 

 When the tank/turtle is rolled onto it's 6'X 30' belly and it's hot gases rise to it's 8' top and then are forced down along each side, into the charring mass, how much of the pressure build up, would you expect to be reduced by burning those gases? 

All of the gases would be flared, and there would only be a very minimal pressure difference. Our 10 m3 batch kiln uses 8" heat and corrosion resistant stainless steel tubing to transport the gases to the flare, which is up on a stand to keep the flame out of harm's way.

 

Rather than interrupt the pyrolysis cycle by removing gases from the top, where would you suggest a pipe be placed, to balance the pressure?


Pyrolysis won't be interrupted. Keep in mind that the gases will escape in any case. 

To keep the pyrolysis gases within a pyrolysis retort, you would need a very expensive kiln that could withstand extremely high pressures, easily costing 10's of millions of dollars for the capacity we are discussing. Nikolaus Foidl tried to build a small high pressure retort, and he ran into a world of trouble getting the access door for the biomass to seal. I don't know what the upper range is of a perfectly sealed retort, but Nikolaus was trying to hit 50 bar, if I remember correctly, and his initial tests at about 500° C saw the seal fail at some abysmally low value of perhaps 1.5 - 2 bar. I think the problem here is he wanted a large diameter access hatch that would allow for the easy loading and unloading of biomass, rather than a manhole sized access hatch where it would be "easier" to maintain the needed seal to reach 50 bar. His design had redundant relief values, and he intended to fully bury it in a containment pit in case of structural failure, which would lead to a massive explosion.

 

With the approach you've proposed, you aren't anywhere near being able to contain pyrolysis gases. So there will be virtually no pressure buildup under the tank. If there is for a moment, the gases will create one or more channels out of the kiln through the soil.

 

I'm proposing to create an easy escape route so we can flare them, instead of allowing them to escape through the soil. Once they are flared, you'll have an absolutely transparent emission of CO2 and H2O from the stack, like the emissions from a natural gas flame, rather than a mix of CO2, CO, CH4 (methane) perhaps some H2 (hydrogen) and a wide variety of complex hydrocarbons as gases or tar microdroplets. 

As you have heard, pyrolysis is exothermic. What that fancy word means is that as the biomass thermally decomposes at temperatures above 300° C, oxygen and carbon atoms, or carbon based molecules, and eventually hydrogen, are released, and as these recombine, either within the biomass particle on their way out, or just outside of the biomass particle, that reaction gives off heat. It is that exothermic heat that maintains a pyrolysis reaction in a batch process such as you are proposing once access to air is limited. 

The exothermic reaction in pyrolysis is the same reaction we call a fire, oxygen combining with carbon and or hydrogen, except that the amount of available oxygen is limited to that which is being decomposed from the biomass. It is that limit of oxygen that prevents the entire batch from being oxidized. That limit also self-regulates the temperature of a pyrolysis batch in a well designed kiln that conserves heat to between 450° - 550°C. Why? Because there is not enough oxygen in the biomass to elevate the temperature higher than that. 


This is also why a pyrolysis reaction in a closed batch stops; it runs out of oxygen.

Whether or not the pyrolysis reaction is self-sustaining depends on if there is sufficient exothermic heat available to continue to heat the remaining un-pyrolyzed biomass above 300° C. The critical factor here is how dry the biomass is. Evaporating water out of biomass cools the biomass down, so the entirety of a biomass particle will not heat above 99° C until all the water is evaporated out of it (in a simple kiln operating at atmospheric pressure). So if you start a batch, close the lid, and the temperature drops off, the biomass is still too wet for the reaction to be self-sustaining. 

 

In this case, which I certainly think will happen in your situation, what you could try is that rather than open the lid again, just let some air into it, from the end opposite the gas flare burner. You should hopefully have sufficient draft on the chimney to pull air into the kiln. Let a bit of air into the kiln to bring the temperature up to dry the wood. You don't want a roaring fire. A charred surface forms somewhat of a seal that makes it harder for evaporating water to escape.

So now we are getting very close to the Adam retort design. Here's an outline of a further evolution of Susan's idea that will be much safer and efficient to operate, while producing a reasonably uniform biochar with the minimum amount of biomass consumed to produce the heat necessary, and very little to no emissions besides CO2 and water vapor.

Sue's Evolved Biochar Kiln Concept - Details to be refined

  • Cut the tank in half lengthwise. 
  • (Optionally) dig a ramped trench that is slightly shorter and narrower than the tank, so that the tank will fit over the trench as a cover. After the batch is finished, a tractor or front end loader should be able to drive into the trench to remove the finished char
  • Fix the tank-half to the side of the trench so that it hinges closed over the trench to act as a cover. The hinge mechanism could use heavy chain welded to the tank and rebar driven into the ground. We only need to ensure the tank-half stays in the proper position as it is being pulled over.
  • Fix a longer heavy chain or better a cable to the other outer lip of the retort lid (tank-half) to be used to pull the lid over the trench with a tractor. If the cable is light enough to be tossed over the tank-half, then the same cable could be used for opening and closing the lid. Otherwise, 2 cables can be used, one to close and one to open.
  • Steel or wooden braces could be used to prevent the retort lid from tipping all the way over when it is opened. It should open past 90° so it stays put. If it is braced open, like the lid on a treasure chest, the cable should be anchored to prevent it from blowing closed in a strong wind.
  • The kiln is loaded with wood, generally oriented along the length of the trench and heaped to fill the space that will be enclosed by the lid, and the lid is then closed. No open fire is used.
  • The kiln is designed to encourage a pyrolysis front to move from one end to the other along the length of the half-tank / trench assembly. 
  • On the starting end, there is an opening in the tank near the bottom connected to a tube. This tube can be closed off, allow air into it, or allow hot flue gas from a wood fire into it. (If a large "stove" with a wood fire in it is used to initially heat the kiln, then that much less wood in the batch will be consumed to provide the heat necessary. So this is a trade off between maximizing the batch output or making operation more simple.)
  • At the other end, a tube is fixed to the tank-half. Midway up should be fine. This tube angles downward into a combustion chamber which will be used to flare the gases. The angle is meant to allow condensate that may form to run down into the combustion chamber. It has a tall chimney on it to encourage a draft to gently pull hot gases through the kiln. We can call this the gas burner.
  • Ideally, the gas burner should be moveable so that when the retort is closed and the tubing is fixed to the half-tank lid, the gas burner position can be adjusted as necessary to attach the other end of the tube to it. If the trench is ramped to allow machinery access for unloading, then the gas burner needs to be either mobile enough to easily move it out of place or positioned off center so it is out of the way of the ramp.
  • In the initial stages of a batch, the gas burner flame will need to be supported to remain lit because of the moisture content of the gas. What this means is that the humidity in the gas will extinguish the flame, largely because it is too dilute to sustain itself. There are options here, the easiest of which may be to burn a little wood in this chamber. The plus is this would be a simple solution, the minus is that someone may need to add wood every hour or so.
  • At the other end of the kiln, there is optionally what I will call the wood stove, to keep it simple. Wood is loaded into it, and the flue gases are directed into the kiln and drawn through either by a small squirrel cage blower if the intent is to simply dry the batch, or a small wood fire is lit in the "gas burner" to create a draft that will draw the moisture out of the kiln if the intent is to initiate pyrolysis more quickly
  • Easy startup of pyrolysis will depend on having thoroughly dry wood at the starting end. Ideally, smaller, pre-dried branches are loaded at the starting end. The core idea here is that once pyrolysis begins at the starting end, the heat generated will continue to dry and heat the feedstock ahead of the pyrolysis front, which will slowly advance from the starting end of the kiln to the finish point nearest the gas burner. So, operation is in several stages:
  1. Pre-drying the wood, particularly at the starting end. Smaller starting end wood can be dried outside of the kiln before loading it if more convenient. Or a large wood stove can be used to inject heat into the kiln to dry in particular the first 3-5 feet of wood. You can think of this as pyrolysis kindling. The drier our pyrolysis kindling, and the more we have of it at the leading end, the easier it will be to initiate pyrolysis. 
  2. Light the starting wood on fire at the starting end, allowing air into the kiln and controlling the amount of air to keep the flame gentle. At this stage, a wood (or propane or wood pellet ...) fire is started in the gas burner to provide some draft to pull the gases through and burn off any flammable gases coming out of Sue's kiln. The objective is to raise temperatures at the starting end sufficiently for pyrolysis to be maintained exothermically.
  3. Once pyrolysis can be maintained without air being added at the starting end, the air inlet is closed. Wood is occasionally added to the gas burner to help maintain the flare.
  4. If temperatures begin to fall in the kiln, the air inlet is slightly opened again to bring them up. Whether or not the exothermically available heat is sufficient to dry the wood ahead of the pyrolysis front is dependent on the moisture content and thickness of the wood.
  5. Once most of the moisture is driven out of the wood, the flare will continue to burn even without support. So it can operate overnight without being attended to if wood has been used to support the flame.

This approach is based on the principals at play in one of our proven vertical batch kiln designs that has been built and operated a number of times in South America. Because it is designed to allow a pyrolysis front to move through the batch, the amount of burnable gas it will produce remains at consistent, manageable levels. A probe penetrating the kiln lid would measure the internal temperature, and the aim would be to keep it below 450°-550 C or so. More than that and too much air is entering the kiln. 

 

The biomass that still needs to dry will not dry that much more quickly if higher temperatures are used. Higher temps will also corrode the tank more quickly. The velocity of drying will depend more on the rate at which water vapor laden gas is removed than the heat used. We will be depending primarily on the gases being produced within the kiln to develop the pressure needed to push them out through the burner.

 

Now, it may seem to be much more effective to leave the lid open light the whole pile on fire, but in this case, most of the heat being produced is immediately lost to the atmosphere, so we are transforming a significant portion of our biomass to CO2 for no useful purpose. And no matter how much heat is applied at the surface of a large log, drying simply takes time. Those 2 facts together mean that much more of the biomass will be burned to dry the biomass in an open flame approach than is actually necessary. Yes, you could produce a relatively small pile of glowing embers at the bottom of the trench after a long open fire, and then close the lid completely and just let the heat dissipate. Then no burner would be needed. But, to produce the same amount of char as you will get from a closed lid pyrolysis front approach, you'll need several batches and need much more wood.

 

When we close the half-tank lid to this trench kiln from the beginning of the batch, and only add air very judiciously, the heat we are producing from the addition of air is used very efficiently. 

So that's Sue's evolved biochar kiln in a nutshell. Much safer, much more efficient in its use of heat and wood, minimized CO2 emissions compared to char produced, and with the addition of the ramped trench, hopefully much easier to unload than a large pit while still maximizing the batch capacity under a half tank.

I'll leave it here for now.






 

The sealed 55 ga barrel of "waste wood", set over a wood fire, with the 3/8" hole flaming skyward vs retorting, should produce a little wonder.among visitors.

 

In this country, where most urban organic materials are officially labeled: "wood waste", "food waste", "yard waste" and "human waste", to be burned, buried, flushed or landfilled, is blindly accepted by most.  Only fools would be so determined, while finding fun/excitement in trying to turn "wood waste", which is being very efficiently disposed of across this country with matches and lighters into biochar, which can benefit healthy soil and the life that depends on it for hundreds to thousands of years.

 

The price/maintenance of whole tree chippers is out of sight for most..  Logs not good for lumber or firewood (I've heated only with wood for 54 yrs)  can be split,  but until processes are ironed out, the intense heat and patience, with no down dizing, will result in some biochar. 

 

I mentioned to Hugh a few yrs. ago about the trench into a clay bank, 24' W 12'D X60', with brush stacked 10' above the upper ground level, lit on top and when burned down, I spread two 1500 ga. tanks of creek water on it and Sue ran 4 hose sprinklers continuously for 11 days, with a steady stream of clear water running out the lower end.  Hugh said that water would've had a slight lemon taste.  Sue, who has always said "It worked !!", after I dozed it shut, just said the only time there was the acrid smell was when I turned the hose off (which is an interesting thought) in that when the DNR game warden visited in June about a pyrolysis complaint and we can have no smoke or fumes other than between 8 and 4. Might 2 or 3 fine spraying nozzles over the 10' dia X 30' tank top hold the authorities off, while we consult with all of you?  

 

My goal is to mix the biochar in compost and spread it on the farm fields.  If any microbes complain about their residence I'll suggest they visit the majority of Mid West farm fields, that are dead/over dosed on chem's and headed for the Gulf.  The 11' wide dozer blade would  easily make a trench of that width.  When the brush was burned down and I've done that with wet compost, dozed dirt or compost over the burn without the tracks touching the pyrolysizing covered pile.  The pyrolysis fumes will continue, so we could test light hosing; however, wouldn't the toxicity of the pyrolysis gases be trapped in the covering of dirt or compost ?.

 

Eliminating smoke and fumes after 4pm is essential--because I've poked the DNR Forestry Dept..  We have a 1500 gallon liquid manure tank and a nearby trout stream, but a flooded trench would be an impossible mud hole.  The bricks this house was built from came from an adjoining brickyard.  

 

I don't remember in photos of large kilns built into slopes in S.A., with condensate being collected from chimney pipes on the above slope, whether they bothered to burn off the fumes.   

Thanks for your thoughts and suggestions.  Dick

   

 

On Wed, Sep 9, 2020 at 8:29 AM Nando Breiter <nando@...> wrote:

Susan, 

 

You might consider sorting the feedstock by size (cross-sectional thickness). Batch similar sizes together. It's like baking cookies. Bake all the same size together to ensure they are all baked to the same degree during a fixed amount of time they share together in the oven. If you bake bread and cookies together for the same amount of time, either the cookies will be burned or the bread underbaked. 

 

When you sort feedstock like this for a batch kiln, it ensures that the processing time is sufficient to transform it to char, while not excessively "baking" the smaller bits into gases. The large rounds might take a few days, the smaller branches a few hours. If the small branches are combined with the large rounds, they will be converted mostly to gases and ash. 


Kind regards,

 

Nando

 

 

On Wed, Sep 9, 2020 at 12:49 AM Susan <suemegg@...> wrote:

Nando,

 

Thank you fir your reply.

 

Unfortunately, due to the nature of our feedstock size is very variable.  We operate a compost site, and loads come in via car trunk loads, pickup trucks and full size dump trucks.  So we have from small bundles of twigs up to tree trunks.

 

The varying size makes for a longer time frame for charring the wood waste.

 

We had considered attempting to flare off the gas and burn it, hoping that would problematic escape of gases and smoke into the atmosphere.

 

Susan

 

 

 

On Tue, Sep 8, 2020, 4:04 PM Nando Breiter <nando@...> wrote:

Susan,

 

The issue is that pyrolysis gases will take up vastly more space than the same atoms and molecules as solids, so pressure will quickly build up within the tank and the gases will have to go somewhere. 

Condensable gases may be trapped in the soil barrier if there is enough to cool them sufficiently to become liquids or solids before they escape. Non-condensables such as carbon monoxide, carbon dioxide and methane will escape into the atmosphere. If you see smoke leaking out, then that would be an indication that your soil barrier is not sufficient to condense them.

 

What you might consider is to create a small outlet for the gases at the end of the tank, and flare them off in an appropriately designed / jury-rigged burner.

 

If you are venting the gases and flaring them, and the brush consists of thin branches rather than thick tree trunks, I would assume that a batch would complete itself in hours rather than days. All that needs to happen is the heat generated needs to penetrate to the depth of each particle of biomass at temperatures over 300° C for the reaction to become exothermic. If the brush is really thin, then once you flip it over, pyrolysis will largely have already occurred and the char will simply need to cool in an oxygen starved environment under the half tank.

 

How thick are the branches of the "brush" you have available?

 

 

 

 

On Tue, Sep 8, 2020 at 6:16 PM Susan <suemegg@...> wrote:

Scenario...   burn brush in a 20 to 30ft long half tank, cut lengthwise, then roll the tank over and put dirt along it to prevent escaping smoke and gases.  The charring process would continue for several days.  

 

How successful do you think our efforts to prevent polluting gases and smoke escaping would be?

 

Susan


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland


--
Nando Breiter
http://biochar.info
CarbonZero Sagl
Astano, Switzerland