Thank you guys for a lot information.
If I have done my system will update soon.
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Thanks for posting your charco maker design, that seems too make decent voluem/ i could build one like that- would be good too have for running smaller engine pull motor generators- or other power needs. Roughly how long it take too make a barrel of charco with this method.THANKS
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I’m very interested in this topic and wondering if there is any update on it. A bit disappointed that CK asked about dual fired gasifiers and came prepared with a scientific reference, but the topic became about steering him away from them - which is not helpful. We’re here because we all love gasification and because we help each other. We actually know a lot about the traditional designs, so this is an opportunity to dwelve into something new.
Several published studies showed scalability promise and a 97% tar improvement over traditional designs (yes that’s for wood as fuel), but you can’t just look away from these numbers, especially if one decides to look into dual fired CHARCOAL gasifiers, no?
CK, have you been working on a dual setup? How is it coming along?
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I reread the whole thread Tarek. No one tried to steer CK away from his experiment but only offered hands on experience with similar trials that were problematic. If CK has since been able to get a working model or want to report any new findings I would love to hear them. Published studies are fine. In theory things should work. When I see an engine running I then know they do.
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Matt, I’ve been thinking through a gasifier setup with a wood gasifying section connected to a charcoal gasifying one as well. I have an idea you might make use of? for the valves and woodgas mixing:
My thought is to use the temperature of the charcoal gasifier to adjust the valve between the wood and charcoal sections. Cold charcoal gasifier? valve closed so it’s all air, no wood gas. Hot charcoal section? Open the woodgas valve and take in a mix of Woodgas and air. The system would need calibration but should be robust once set.
Temperature actuated valves are a commercial product, but if going the DIY route… Stainless steel wire could hold the woodgas valve closed when cool and allow a spring to pull the valve open as the wire expands with heat. The wire can be made quite long and looped around supports many times so that there is a large change in length from cool to hot, say a half inch or so. This will give both high force and high travel for the valve. Alternatively, bi-metal strips can generate a good amount of force and travel.
Stainless steel starts to creep (stretch permanently) above 500c/900F and is really unhappy at full gasification temps so it can’t be located in the combustion zone proper. I looked at some more exotic metals to see if anything would be happy living in the lobe. Even exotic alloys begin to creep at gasifier temperatures so cheap stainless wire is about as good as anything. Keep it near the combustion zone, not it.
A fancier version would use a photo sensor looking down the nozzle to estimate lobe temps and actuate the valves accordingly, but I prefer pure mechanical options where possible.
*done->down edit
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My focus in on the VersiFire. Advancing the gasfier technology irrelivant because the VersiFire dont care how clean the gas is. So any gasifier will do as long as it makes volitile gas.
The versifire blower is the key and it will need to be tuned to the gasifeir so that it is always driving the unit to its optimum flow.
Get rid of brdging you get rid of tar. it is the #1 issue with tar production if you are doing everything else right.
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Once the Versifier control is full developed I will be phasing out metal fabrication. The CFX will be produced by other companies and my shop will be cleaned, painted all new lighting and all the fab stuff will be down sized to a small RnD lab. We wil becomes an assembly shop along with 3D printing, 3D printed alumum cast technologies, custom carbon fiber components and specialized electronics controls.
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I think one must keep in mind and remain focused on the purpose.
In the way you describe it: Pro: Instant performance boost at high loads (runing an engine) Con: A lot of wasted gasification in the wood gasifier, because it needs to be maintained anyway (for when it’s needed to boost the charcoal gasifier). May be this can be resolved with adequate sizing? Perhaps a much smaller wood gasifier can be operated continuously in support of the charcoal gasifier (kind of like an enrichment function without overloading it)
I was thinking about something similar, but different mechanically
I think a better application would be if we’re aiming for engine quality gas for creating heat, such as industrial heat, or even fueling appliances, especially indoors. Scenario can be during the production of charcoal, using a standalone charcoal gasifier instead of waste wood to heat up the retort. (I know that many are of the opinion that it’s ok to have a bit of a dirty fuel for that, but I strongly disagree. I wouldn’t want any signs of soot or black color build up on my cooking pans or kitchen ceiling or in my clothes dryer. The appliances deserve the engine grade gas).
So I think in the scenario of a standalone charcoal gasifier delivering the heat to a continuous charcoal retort, the post retort condensation load can be reduced by feeding a “small” portion of the charcoal retort gases into the standalone charcoal gasifier that is actually fueling the charcoal retort, hence cracking those extra gases and boosting its energy output…This would basically turn the charcoal gasifier into a more tunable wood gasifier because the wood gas content is controllable. Of course, testing would be needed to determine how much is the right amount of “small” in order to avoid overloading the charcoal gasifier…possibly with a Y-diverter…and can be automated in response to signals on the parameters (temps) in the charcoal gasifier. The un-diverted gases would be on their way the traditional condensation and gas cleaning processes downstream.
How far am I from the science? and from reality? I realize it adds cost, but this would be for a continuous process. What am I missing?
Please feel free to correct me
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I truly respect everything you do and say on the topic and would never question your experience. I just respectfully disagree that the gas doesn’t need to be clean when used for heat. If we want people to consider replacing propane with this gas, it’d better have a crisp blue flame, and not leave black marks on pots and pans and kitchen ceilings, and not cause issues in propane or natural gas furnaces and water heaters. And the fact that it’s also fuel grade, it makes it more attractive to adopt. I realize this is not for everyone, and as you adequately mentioned many many times before, you never really get away from this equipment for long. Therefore it’s only for the very committed DIY’er…but don’t forget the spouse of that DIY’er needs convincing too. Fuel grade gas makes it easier to adopt/accept, and let’s face it, it also gives us enthusiasts the confidence to fuel expensive appliances with. Just my thoughts. I could be wrong
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Thank you for reading the whole thread, Tom. I don’t disagree with you, on pretty much all the points. I’m starting to learn that in this forum, threads jump around and intersect. In Kristian’s thread on the Kursk cistern kiln, there was a lot on distillation, candle making, antique lamps, etc…Fun, but off-topic. I’m not saying this particular thread went off-topic, but it quickly went to a focus on a different topic. I’m now better at understanding the fluidity of communication within the threads. I’m used to automotive forums where if the topic is failures of rear differentials, a comment on a slightly different symptom from the original post is moved to a different thread by the administrator. I’m just getting my feet wet here, and have misinterpreted the responses. My bad. And thanks again for your response.
And yes of course I agree that studies don’t mean a lot, especially when only performed in a lab. We are here experimenting with low-tech engineering (with constraints - MAJOR constraints). But I’ll remind you that’s exactly how the interest in wood and char gasification (re)started by grass roots efforts like this one. Actually, the fact that the wood/char gasification had a life in the past and then died out of the mainstream, makes it an even bigger effort to overcome the naysayers who shake their heads at our charred hands and ashy workshops.
The dual fired gasifier has yet to be explored by the creative folks on this forum (from what I can find so far). I got excited to see someone wanting to go there. As for studies, here’s one that is done on actual equipment. I was glad to see it wasn’t just a lab on a microscopic level. It may or may not be worth pursuing by us here, but we shall see. 97% reduction in tar (from wood) is almost too good to be true.
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In the typical winter here I burn between a thousand and twelve hundred cubic feet of firewood to heat my house. Of course I have tried to think of ways to make useful producer gas from all that combustion but haven’t really made a crack in that nut. The main problem with producer gas other than to run IC engines is that it is very hard to store quantities of the stuff for things like cooking or perhaps clothes drying. I would definitely like to see someone develop a viable system but so far storing heat in either water or some other medium is the best I’ve done.
I think much of Vitally’s work is related to this idea and I would go back through the threads and look at things Joni has developed.
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Tarek - My use case is long runs of wood/char gas to run a generator. If I can clean up tarry wood gas by passing it through ultra hot incandescing charcoal that is also making fuel then I get more kilowatts of fuel per bucket of manually prepared char.
The chemistry is pretty straightforward. Wood gasification has a lot of endothermic (heat stealing) reactions going on so it needs to run heavy on air/oxygen combustion to keep temps up and self crack tars. If you don’t run a wood gasifier hot, you get tarry gas that kills engines. Charcoal gasification doesn’t have the same heat stealers so it naturally runs CRAZY hot, at least in the combustion zone, and it doesn’t generate much tar even at lower temps. The tar has already been burned off in the charcoal making (mostly).
A dual fuel system could generate large volumes of tarry cool wood gas and clean it up in a chargas combustion lobe. The clean up will steal heat but that’s something chargas has in spades. You would just need to ensure the chargas stayed hot, hence the interest in an automatic system to govern the amount of woodgas delivered.
A well designed Imbert wood gasifier ideally does the same thing but the physical design of the Imbert gasifier can’t adjust. It has to be tuned to one operating point and that means consistent fuel, constant load, that load matching the gasifier design point, a skilled operator and for nothing to go wrong.
This dual fuel idea creates a lot more room error: It separates the char zone of an Imbert from the wood combustion zone, manages the fraction of tarry gas inflow to be sure it can be “cleaned”, makes char available as needed rather than as converted, adds secondary air and a secondary combustion zone that stays hot-hot-hot. This all assures thorough conversion/cracking of char. It adds complexity but there is value if you can get more miles and watt-hours from the same amount of charcoal.
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Certainly makes sense. But you may have a couple of problems. Appliances run on Liquified Petroleum Gas (LPG), or Natural Gas (methane mostly). Both are more energy dense than wood or charcoal gas. You would need to re-jet the burners, and may have a hard time getting the same heat output. LPG and Natural Gas are non-toxic. They are a health hazard only because in high concentrations they displace oxygen (simple asphyxiants). Wood and charcoal gas both have Carbon Monoxide (CO) as a major component. It is toxic, and is cumulative, so dangerous even in small amounts over time. It’s not used indoors very often for that reason. Not saying you can’t do it, but it requires a lot of care.
Engine grade is good for engines, and for heat, but unless it’s really clean, your dryer may still give your clothes a campfire aroma. Anyone care to comment on exhaust smell from converted vehicles?
edit: There are some documents that suggest LPG may be toxic, since it has been found in the blood of presumed asphyxation victims. I don’t know, but since you can blow yourself up with any of these gases, be very careful.
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The closest I can come up with is a fire, completly burned down to red hot charcoal. Only a sweeter touch to it.
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Thanks Kent. That basically strengthens the case for absolutely best engine quality gas possible in any appliance. I never implied that char gas or wood gas are ready replacements for LPN or LNG. Calorific density being just one of the factors, in addition to toxicity. I was addressing the many comments by highly regarded folks on this forum who advocate for lower quality gas for heat applications, specifically on the low need for thorough condensation (removal or cracking of tars). Your arguments further expand on the practicality of switching to wood/char gas, and support the case for engine quality gas for appliances
Thanks Anthony. I think we’re saying the same thing on the science level. And as you explained, the tuning or a dual chamber or dual fired gasifier can be extremely costly or difficult, and just not doable without exotic material and instrumentation.
This is why I’m proposing (and might actually test) a setup where the wood gas is generated in a separate physical location from the char gasifier. Wood gas would only be introduced as necessary to maintain the charcoal gasifier operation to optimum (or max, using an automatic system as you mention). Since not all available wood gas would be used as an auxiliary input, the rest can just be condensed and flared the traditional way.
As for consistent load, I wonder if our response to load fluctuations as operators should be to divert excess output rather than input, in order not to disturb the established nominal input and system balance. In my case it would be flaring to the atmosphere rather than add heat to the retort. In your case, it may be the same, essentially running a flare as well as the generator simultaneously during those moments of system overshoot
Thanks Tom. I went through that thread but I’m not clear where there is mention of storing producer gas or a dual fired system. All I could find was a build to run a car. Did I miss anything?
I’m thinking the best case for a “dual” system is 2 separate gasifiers. In your case, producer gas (from all that combustion to a closed retort that produces the gas), that feeds into a charcoal gasifier that is essentially “boosted” (within limits). The output of the charcoal gasifier is flared to provide the heat to the retort as well as your house simultaneously. I hope that made sense
Tarek- I think we are on the same page so I’ll stand down from walls of text while we seem to be saying the same thing.
Regarding the woodgas source… I would not flare excess woodgas. On a long run, my use case, the balance of wood and chargas would stabilize and I would adjust the wood gasifier to target that balance point, perhaps with a little excess to leave room for variation. If I needed heat, I would harvest the exhaust heat of the gas engine. Ideally the gasifier is well insulated and isn’t a major source.
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Good description JO, actually i enjoy the woodgas-exhaust smell (it’s no good habit though, pretty poisonous) 
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I wasn’t talking specifically about the dual fired gasifier. If a WK is sized to fuel a V-10 then if it’s only feeding a 6 cylinder it is producing more gas than it’s using. Same with any other gasifier that is not sized to a specific engine. 'Doesn’t hurt anything but it’s still a benefit to divert that excess into useful work. Making producer gas specifically to fuel a water heater or other appliance would require a continuous production of gas. Maybe a drizzler if anyone could keep one running without fairly constant monitoring. Matt R has been working on gas storage using a gasometer which could then be stored for other uses but you are still dealing with wood gas and it takes a lot more volume of gas to equal the energy of propane or methane, so a fairly large apparatus. So now I see I’m beyond the original intent of the thread so I’ll shut up.
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