Hi, Everybody

…where has this site been hiding? I discovered it by Googling for Charcoal Gasifier, which normally takes me to the Kalle gasifier page, but this time took me to Gary Gilmore’s log splitter gasifier, which definitely looks like the way to go as a first gasifier. My background- my vice is driving and exploring in an ex-army Series 3 Land Rover. It’s an expensive vice at about GBP 0.30 per mile on Propane, but nothing puts a big smile on my face like driving something that I’ve nursed through the MOT (UK vehicle safety test). I need to get the financial and environmental cost down, though, and a gasifier seems like the way to go, primarily for road use, but I’m interested in developing a spinoff mobile CHP system to supply power and hot showers at music festivals. I’ve got plenty of questions, but I’ve got a lot of scrap fire extinguishers, a MIG welder, and I’m off to the garden centre for a bag of charcoal tomorrow.

Hi Brian! Welcome to the site.

The Simple-Fire is a great place to start! You can have a small engine up and running in no time.

Keep us posted on your progress.

Welcome to the Wood Gas Funny Farm :slight_smile: from a fellow newbie.

Can’t wait to get started- I’ve got the charcoal, I’ve got a combi boiler fan and various bits of pipe. A little refinement- I’ve got a batch of scrap wide mouthed fire extinguishers, and I want to put the feed air pipe in vertically from the top. Stay tuned.

Brian, Wmshooke posted four photos (Nov. 2, 2012) of his fire extinguisher simple-fire running a Briggs and Stratton small engine in the charcoalgasifier yahoo group. The air inlet is at the bottom, and the output gas comes out of the shoulder of the fire extinguisher where he mentioned that he “forced” a fitting into what was the fire extinguisher output. Hopefully you have natural charcoal (not briquettes) and it will need to be sized rather small…less than 3/4" and larger than 1/8". At the air inlet, be sure to have a setup that allows you to easily remove and inspect that nozzle. I suggest wrapping the inlet nozzle with some thin stainless steel sheet held on with a stainless hose clamp.
I’m not sure I understand why you want to feed the air pipe in vertically from the top?? Be sure to keep us posted.

What I’m thinking is… if I leave the extinguisher body as a sealed, inviolate vessel, I can put a safety cap on it while a part used fill cools down, and in addition, it’ll simplify adding a water jacket- remember, I’m interested in a hot water spin-off. Do I understand that mild steel inlet tip = burnt and molten tip, and stainless tip = hassle free operation? It sounds worthwhile splashing out on a length of stainless… but enough of the armchair engineering- lets get fabricating.

Update… I got something cobbled together today- I was lucky enough to get a length of stainless tube from the scrapyard, and welded together a coupling for the fire extinguisher top so that the stainless tuyere could be driven into the charge like a spear- a spuyere, if you will. I mounted the induced air fan- I’m starting with a flare and graduating to an engine- to suck gas from the top, filled her up, powered her up and lit her up. It lit up easily, and produced fairly spectacular quantities of grey smoke… which resisted every attempt to ignite it. So no flaring… until I switched off the fan, and a rather pretty little flame appeared… at the air intake. On opening up, it was quite obvious that the charcoal pieces were much too large, so Take 2 next weekend with much smaller pieces. To be continued…

Re. Recirculating of exhaust gas- I’m just trying to get it clear in my mind why it makes sense to recirculate CO2, rather than just restrict the feed air. Do I understand that it’s to control the tip temperature without reducing the mass flow through the gasifier? If it is, I’d be more inclined to experiment with giving it something to crack- tarry gas from an updraft gasifier, anything as long as it’s just carbon, hydrogen and oxygen.

Hi Brian, I like the attitude of “…but enough of the armchair engineering- lets get fabricating”. Talked to a lot of people who talk, but do not jump in and that is when you really learn to swim.
First off a message to the moderator. Chris, can you move this to the Charcoal section of the forum since it is dealing with charcoal gasification?
OK Brian, back to you. Recirculation of exhaust gas has only one purpose but two benefits. Purpose = temperature reduction of the oxidation zone. This will slow down the oxidation of your nozzle (benefit #1) and add “fuel” to the charcoal gas generator in the form of CO2 (benefit #2). You cannot control nozzle temp by reducing the air comming into the generator. (unless your air inflow is very low, and that means your gas production is close to nothing and that means you will get very little charcoal gas) Air contacting charcoal at a velocity needed to produce good charcoal gas will created temperatures close to 3,000F. Steel will burn up very quickly at that temp and so will stainless steel. You have to do something to cool down that hot oxidation zone and engine exhaust is a very simple, effective remedy BUT there are other ways of doing it.
If you want to introduce tarry gas from an updraft gasifier, that will work well too. I’ve done it. Now you need your charcoal gasifier running and then pipe in some “smoke” from another updraft gasifier that is fired at the same time. You can also rig up a drip and allow motor oil to run down the air inlet and vaporize in the nozzle or use water. Done them all but the simplest method is the engine exhaust. But, experiment. It is fun.
Just curious, How did you know the reason you did not get a flare was due to charcoal size? With a small generator, it is extremely important to have small (1/8 -3/4") pieces of charcoal. If much bigger than this, the CO2 from the oxidation zone will not encounter any charcoal in the reduction zone and thus remain CO2.
One last thing before signing off, you mentioned capturing the heat from the exterior of the charcoal generator. You may be disappointed. Charcoal is a very good insulator and therefore the heat does not radiate well from the oxidation zone. It will move out slowly, but by the time the outside of the generator gets hot, it may be time to shut it down to add more charcoal. Let us know what you find out here.
Until later,
Gary in PA

Topic moved.

Hi Brian, I like the attitude of “…but enough of the armchair engineering- lets get fabricating”. Talked to a lot of people who talk, but do not jump in and that is when you really learn to swim.

Awwww, you say the nicest things. Remember, I wouldn’t have even tried without your video showing that a small gasifier really was that simple.

Re. Chunk size… I sort of guessed when I opened up and looked in and saw big red hot charcoal chunks on the surface, that something wasn’t right- I assume that if the gas is too hot when it escapes the surface of the charcoal, it won’t stay good charcoal gas very long. I’m guessing that too fine= poor gas flow without forced air down the tuyere.

To be continued…

, Actually too fine is not a problem unless it is dust. Charcoal is rather light weight stuff and the turbulent of the air moving through it will cause the charcoal to “float”. Of course every thing is relative, but in you smaller unit, try a mixture of 1/4" to 3/4" sized pieces. Another thing about charcoal is it does not pack down into a tight mass. (unless it is wet) Rather amazing fuel. Give your charcoal generator a try with the smaller charcoal sizes. It will work!
Gary in PA

Almost, but not quite. I ground up a load of commercial lumpwood charcoal in the garden shredder ( the quiet, low speed type) , and screened out anything below about 5mm, lit up, watched lots of grey smoke appear, and dramatically disappear when I managed to ignite it, and it lit back into the fan body. There’s too much air leaking into the fan, so I’ve got a tube of high temp silicone to seal everything up, and I’ll have another shot tomorrow. It will flare backwards, with gas straight out of the hot combustion zone rising up the vertical tuyere. My assumption at the moment is that whereas tarry gas needs to be coaxed to burn, charcoal gas - Deadly Poisonous Carbon Monoxide- is pretty undemanding, and should flare from any old nozzle. Does anyone know otherwise?

The question that I need to be ready to answer is: What are the health hazards in charcoal dust? As I understand it, once a carbon particle gets into your lungs, it stays there, and eventually causes problems in extreme cases like coal miners. A bit of perspective- I was a despatch rider in central London for six years without noticeable ill effects.

Yeeeee Harrrrrr, as American people say, apparently, I’m gasifying. No photos as yet, due to a flat phone battery, but I sealed up nearly all the air ingress points with weld, RTV goo, and exhaust paste, lit up- without exception, always the easiest bit- , watched an awful lot of grey vapour (what?) appear, which eventually ignited, and spent a rather pleasant twilight watching and tweaking the flame.

The interesting bits- what was the grey vapour? Given that it didn’t have the yellowish tinge of wood smoke, and I twice had to pour a lot of dirty condensed water out of the fan casing, my guess is that it was water vapour. I’m not using fresh charcoal, I’m grinding up commercial charcoal and storing it in damp conditions, so hopefully, as my own charcoal production ramps up, it shouldn’t be a problem.

The biggest “that’s strange” moments were when I started putting stuff down the tuyere into the hot zone. Both water and wood pellets turned the flame yellow. The worst answer would be that wood tars were getting through without being cracked, the best would be that the yellow was from sodium in the wood and water, and I’ve got the beginnings of an assay to identify wood treated with copper or arsenic.


More interesting bits- since the metalwork was cobbled together very quickly and dirtily, the vertical tuyere is wildly off the central vertical axis of the fire extinguisher casing, so there’s a distinct spot glowing red hot on the outside. Do I eliminate this by centring up the tuyere and moderating the hot zone with water or exhaust gas, or do I harness it with a water jacket for my CHP scheme?

The endgame- the pipe between the gasifier and the fan became too hot to touch, and the flare started lighting back into the fan casing- I know where the air leak is. It was too dark for any further investigation, so so ended a rewarding days gasifying. In retrospect, flaring the gas is a good start because I can learn so much about the gas quality from the flare before I try to start an engine with it.

To be continued…

Hi Brian,
From my experience do both. centre the tuyere first then moderate that reaction with exhaust. On a unit that size I would avoid the water or the heat jacket. The exhaust will give you longer run time and cool the reaction down. the water goes very quickly from helping you to being too much and water vapour will accumulate in the filters down the line. A heat jacket on such a small vessel risks causing too much stress on the thin metal; the red hot on one side cool on the other will lead to early failure. Of course experimenting is half the fun so go for it just some thoughts…
Best regards, David Baillie

Hi Brian, You have to be careful using commercial lump charcoal. That stuff is sold by the pound so the more tars it holds, the more it weighs. This is done by burning off most of the volitals but shutting down the retort early so some of the remaining tar is adsorbed by the charcoal. This is not good engine grade charcoal, but can make a flare. The white vapor is water. I get it all the time too. Really depends on how moist your charcoal is and the dew point for the day.
Not sure about the flame color change. We have had this discussion before and I believe it is trace elements, like sodium that are present in your wood or water. Some folks from Texas have had issues with yellow flame too. The charcoal is made from mesquite which grows on alkiline (sodium rich) soils. There is also the possibility of a road killed armadillo beinging inadvertantly charred in this particular batch too.
You are using a small reactor (fire extingisher). Why not place the bottom half of it in a bucket of water to cool down that red hot spot? Ideally you want the nozzle centered in the generator… FIX those AIR Leaks! They can really mess with your charcoal gas power and at worst will back feed into your filter. Keep on charcoal gassing. It is fun and fairly cheap. Compare this hobby to playing golf!
Gary in PA

Over the last couple of weekends… I got the fan sealed and properly cased up, and managed to get a four hour run at a low flow rate- photo attached. One intriguing effect was by dropping bits of copper wire down the tuyere, I once or twice managed to get a delightful green flare- I couldn’t make it happen consistently, but it was inspiring enough to search for, and find this site:


Strontium for red, calcium for orange, sodium for yellow- thanks to Gary, by the way, for supplying a potential band name- Ladies and gentlemen, put your hands together for… The Squashed Armadillo Hypothesis.

The focus at the moment is charcoal production- my own challenges are that I live in the suburbs- space is very much at a premium, and the neighbours live yards, rather than miles away, and noise, dust, and smoke abatement are imperative. The avenue I’m following at the moment is to process wood pellets in a TLUD stove, and get them sealed into one of my extinguishers with the minimum of handling. The cheapest way to source the wood pellets- for now- is actually to buy 5 litre bags of cat litter at Poundworld. I bought 50 litres today for UK£10, and everyone was very nice, and wished my cat a speedy recovery.

To be continued…

OK, Not sure what possesed you to put copper wire into the nozzle, but as you note, it will produce a green flare caused by copper ions. Good thing there are no armadillos in the UK or you will try popping one of them in. :slight_smile: Wait, what about a flattened hedge hog?
Seriously, when I burn well charred charcoal, all I get is a blue flame. This is carbon monoxide burning. Should I poke a stick into the hot charcoal around the nozzle, my flame color will show tinges of orange/red. This has to be the hydrogen released from the wood. I was demonstrating my Simple-Fire generator on Saturday when the humidity was 90% and air temp in the 30s (F). I was amazed at how much water vapor condensed on my filter and was comming out the exhaust pipe. In other words, there was so much water in the air that adding any more water to the oxidation zone would have been pointless. Also found this water dampened my usually dry filter so that I could not just shake off the dust. Now I had to dry the felt first!
Always something new to learn.
Gary in Pa

Now you understand my frusteration PAGary tring to charcoal operate in a climate that is +90% condensing air at 30-40F for six months of the year; +70% consensing air at 50-60F for another four months!
Charcoal was always air sucked in wet with the wet air.
I think it is great for Northern frozen moisture fixing people, those with lots of fuel woods solar inputs in low relitive humidiy areas.
“Don’t mean to Rain on the charcoal parade” At thier hearts every raw woodfuel reactor IS a charcoal machine. Lot here for us all to learn from. Thanks.

Steve Unruh

Hi Gary, when you had the high humidity were you still using the exhaust to moderate the reaction? I’ve been wondering about cutting it out as a way of running in the wet season…
Best regards, David Baillie

A rewarding couple of days- I’ve got hold of a couple of clippy top plastic barrels, hopefully to make dry storage easier. I was hoping to approach the local wood pellet depot to get a good price on a barrel of pellets, only to find that it was all about silos and blown transfer. I did manage to get 180 litres of woodchips from a friendly farmer for UK£10, but kilo for kilo, litre for litre, 5 litre bags of cat litter are still an attractive option for wood supplies. Remember, I’m working in a postage stamp sized back garden, so storing logs for a year to dry them isn’t really an option.

Charcoal making… the most successful method, that I keep returning to, is a stove with drop-in/lift out mini retorts


basically a container with a pipe to draw the tar gases from the top and feed them to the bottom of the combustion process. There’s a net avalanche effect as more tar gas is produced, which adds more fuel, which makes everything hotter and produces more tar gas, and I had three retorts running rather alarmingly today. It’s still too labour intensive for my liking, and I’ve been trying to scale it up into a “Load It, Light It, Leave It” process, with limited success. First attempt, load up a fire extinguisher with slabs of old pallet, put a gas tight cap on it, and pipe the tar gas into the primary air intake- what could be simpler? Getting a gas tight seal on a rim about 150mm in diameter wasn’t actually that simple, but I did manage to produce something resembling charcoal… and learned the following day that charcoal can play dead.

Latest attempt… get a better seal on the 65mm thread on top of an unmutilated fire extinguisher, load it with pellets, screw it down, and fire the stove up. It smoked like hell, I suspect because the extinguisher took up too much space within the stove, produced a lot of condensed tar- not really an issue- but when everything had cooled, I peered in, only to see a lot of shiny black gunge. Condensed tar, or melted plastic lining- to be investigated, but if I can make this work, I can char and gasify in the same vessel, reducing the amount of handling dust. What I am impressed with, is that wood pellets char into robust and uniform charcoal pellets.

To be continued…