Hi David, Don’t worry about the blow back. At worst, it will blow out the nozzle and shoot some coals across the room. Put your clean out on the side opposite the nozzle or on the bottom. BUT make sure it is air tight or your charcoal will find the air leak and start burning there as well as at the nozzle. Here are some pictures of a charcoal gasifier I made with a water tank that has a removable nozzle.
Gary in PA
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Well i cant wait to see how you get on , and i’m sure you will have a smile so wide you will be able to fit lemons in sideways .
Please dont worry about using that 5 inch port for stiring up the charcoal as you WILL make more ash/dust/fines by poking anything up there ,just leave alone and you will be fine .
Use that 5 inch pipe cap as i mentioned as a clean out port you only need to get hand and wrist in at the most ( not your arm ) or even some sort of tongues to remove large build ups of slag and this time next week you will be wondering what all the fuss is about as you stand back watching your flare or running your engine , it really is that simple !
Dave
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I’m with Kristijan, I wanted affordable hatch covers so I made something myself. The basic idea is to make a thin metal disk with force applied at it’s center on a flat rim.
I made the upper and lower openings of this pipe very flat. I just used my angle grinder to get the surfaces close. Then i darkened the surfaces with a sharpie marker. I glued 80 grit sandpaper to a sheet of glass and used it to make the final surface. I beveled the sharp edges with file, just so I will never cut myself on them.
I made the covers with all their associated hinges & etc assembled. I then placed the sub-assemblies on the ends of the pipe and welded them in place.
Last, I opened the hatches and covered the flat surfaces of the ends of the pipe with plastic kitchen wrap. I then put high temp silicone on the covers where they would contact the ends of the pipe. I then closed the hatches and let the silicone cure.
It is very convenient to have a hatch at the bottom of the gasifier because I can very easily dump the char. Just because it is so convenient I always dump and reload before use.
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Hi Rindert , you said you always dump out your old coals and refill with new every time i think Koen also does that and i guess with a small sized tubed gasifier its not too messy .
what do you do with the old coals ? how much in volume or weight does your unit hold then ? what sort of run time do you get on your generator under load .
I know there’s lots of questions there , its just i did have a small 8 inch dia gasifier a few years back looked a bit like yours , but that had a vertical nozzle in the bottom and it would only run my 8kw generator for only about an hour before it was too hot , i couldn’t empty out the coals from that due to my nozzle being screwed into a solid bottom so if i ever needed to do anything i would lay it on its side and tip it out .
My Propane tank & 200 litre drum gasifier i would never empty out the coals as there would be far too much mess with the amount left in there , only time i would bother is when changing over to test a new nozzle out or if there was a large slag / clinker around my nozzle .
Dave
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Hi Dave,
I didn’t go into that. Was trying NOT to write a tome.
I screen out the fines, which go on the lawn, and put the larger char back in the gasifier.
Rindert
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Henry, looks like those socks are doing the job. You can fill your wardrobe with new socks, and put the old ones in filter duty. You can certainly try making some cyclones. Seems small engines prefer small-diameter cyclones. Here is an interesting test by Northern Self-Reliance. 
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Henry,
I think a cyclone is going to fill up with that coarse char really fast and clog. I think the gas might be moving too fast and dragging char along with it. Can you tell me more about your setup?
Rindert
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dont miss the point of a bag filter. They are supposed to develop a “cake” This is actually what becomes your filter not the actual bag or your sock in this case. The dirtier it gets the better it filters.
Screen your fuel better that alone will get rid of all that dust. No need for a cyclone just a vessel large enough to settle out the heavy stuff is all that should be needed. Low velocity, larger vessel = no cyclone needed to drop debris
I have not built a cyclone in years and don’t ever plan too again. If you make bags out of silica cloth you can clean them out toilet brush and never need to remove them. Just sweep them like a chimney brush and dump out. Plus this is very fine woven material so it will filter better than those socks.
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Hi David. I had to scroll up a ways to remember whose thread this was. Anyway it was suggested that you put a access port into your tank. I just got done building a charcoal unit and didn’t take the time to put one in mine. One run and I cut one in. Kind of an essential as far as my limited experience goes. Mine is a four inch ID pipe and I have big hands. I can reach through it and move my hand around inside the tank with no problem.
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I do not have load on engine , Have chipped green wood , screened and had tremendous waste and decided to re screen at 1/2 inch and building new gasifier . 3 something inch Iron pipe 6 feet tall bottom sealed in mortar 3/8 hole used as nozzle , toilet flange as top 1 1/4 sump pump hose connected to top to sock filter , sock filter connected to valve tree , connected to engine , ran two gasifiers at once .
Ran two engines in separate runs both ran for hours and then would not restart because intake valve was seized by tar .
Had burn pile of wood from trees shading solar panels . but stopped burning in this spot instead used wood to fire retort that is safer then huge open fire . Stopping now for winter . will start next year with left over chips and trees I cut down that are now hidden in weeds .
I was making charcoal while running engine . It would be nice to bake bread while making charcoal . Think someone does that .
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“Green chipped wood”, says it all for your valves tared problems, man.
There is nothing you can do on a small sytem that can compensate for this severe moisture system thermal-quenching overloading.
S.U.
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I have to agree with @SteveUnruh. You must get all the tar out of your fuel first.
Here in Colorado it is so dry that finding dry wood is not difficult at all. But I know this is a big problem for a lot of people. I started a thread about it but not many entrys yet. Maybe when you have worked through this you can contribute. Wood Drying Methods
Rindert
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I am making charcoal from the chipped green wood and reducing the weight of the green chipped wood from four pounds green to one pound charcoal . but how many days do you spend to make one pound of charcoal ? I do have to fire oven more then once . I can get two cans of charcoal made in one day but usually it takes a week . And not all the wood is made to charcoal and maybe there are small flakes of tar in the charcoal . and I used pipes that had tar in them from making charcoal to make valve tree when I ran out of parts and one inch pipe would not work .
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Henry,
This is the cold hard truth. This is the way I have made chunks for charcoal. If I push myself I can reasonably make 20 gallons per day.
I don’t mind the exercise. This is way better than running marathons, and I have done that three times. And I might even do it again. However, it is not a time efficient way to make chunks.
I am working on a chunker. I have come to see that a chunker is central to any woodgas or chargas system.
Rindert
PS I have a 1970s Echo chipper, shredder, vacuum. It makes really good mulch, but I wouldn’t use it to make gasifier fuel.
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I use a chop saw its way faster than that. Im way to lazy to do that!! Yaeh Marathon?? Im out of breath just saying that word!
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That is the way I make fuel to turn the green wood chips into charcoal . maybe I burn over 10 gallons of small wood chunks to make one pound of charcoal , otherwise I would burn this small wood in a pile .
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You cut all your wood up before cooking it into charcoal? Once cooked, those little limbs (like on the ground there) would just crumble apart. I am all for getting ones exercise (even if it doesnt make much sense - like riding a bike that doesnt go anywhere) but that setup looks like a repetitive stress injury waiting to happen! 
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Yep got that exactly one year ago, giging trugh rocks with a pick when l was diging out my well. Repetitive motion and shock wawes trugh the arm worn down my wrist tendon. Felt like there was sand in the muscle for 2 weeks. Swolen and painfull…
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Henry your problem is a simple one to over come . Do not use wood chips unless of course you have a fully insulated retort to bake them in , chips are very hard to fully cook all the way through when you have a container filled with them , but if you fill your retort up with branches ,twigs even small chunks of wood be it fresh green wood or fully seasoned dry wood you will get much better and fully charred wood .
Dave
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