If you go to a larger blower, put a rheostat on it so that you can start at a low pressure and then build up as the fire takes in the hopper/reduction area. Too much air at the start tends to almost blow the char bed out. TomC
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No, Dave is spot on, I had completely forgotten we were not talking about an updraft model! If you read Kristijans thread on his Mercedes E230 (volume 2) build, he starts out with an updraft design, and then switches over to downdraft - I think if you start reading at about post 370 is where he starts the chage-over. Worth a read, if you havnt already.
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I have only used up draft charcoal gasifiers here at home and all my charcoal is stored out side in 25 and 200 liter drums before i refill my 200 liter gasifier , they are not 100% air tight drums that i use but even after all the years i have been making charcoal out side open to the elements i have not suffered from damp charcoal due to weather conditions and trust me it gets pretty wet where i am as i am up a mountain surrounded by gum tree’s and clouds .
Here is a typical damp winters morning , you should just be able to make out my charcoal crusher and drums ,
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So close, yet so far. I fixed several leaks and it did improve but still couldn’t get it to run normally. Harder than expected to get this little generator to run from this big gasifier. I’ll be trying a few other things and keep you posted.
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Hi Greg , what a shame like you say so very close , if i can just throw a few things out there and ramble on , in the video while it was trying to run up to speed i didnt see you trying to change the mixture valve is that correct or is it my bad eye sight ? as a lot of the time there is one position for easy starting ( sweet spot ) and another for ramping up to speed and making power .
If when on petrol the generator runs normal we can rule out mechanical problems with the engine and so my gut feeling still tells me its weak gas , when you blew back through your system did you also spray soapy water around on the carb and the fitting ?
Another way of testing that would be to run the engine up again on charcoal gas and while its trying to start spray some starter fluid onto the carb and see if the engine stops .
What filter material are you using for charcoal ? maybe don’t over pack your filters to allow free flowing of the gas or use open cell foam if you are using hay or other types of media .
And cap it off ,when i get an engine that will not start correctly on charcoal gas i start it on a carb full of petrol and with the air mixer valve wide open connect the charcoal gas pipe and you will hear the engine run overly rich , now keep your hand on the lever for the air mix and ever so slightly start to close off the air valve and as you feel the petrol running out you will find that running sweet spot that will keep the engine at speed once all the fuel has gone .
Good luck cant wait to see the next video of the engine running .
Dave
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You have about picked my mind of everything I have to offer. I’m not from the dark side so I don’t know how this pertains, but one thing I do is check my ash bin for any “white” ash which can mean a internal gas/air leak burning up my gas and weakening it. I did read that wet charcoal will give you weak gas. Don’t know how you make your charcoal or how you store it, but you might try putting some ( enough to fire your gas engine for a short time ) into a metal container with a hole punched in it. Place the container in a fire to try driving off any moisture that may have gotten into it while stored. TomC
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Hi Greg.
I am gonna propose something that might seem strange, but try weting your char. Add about 15% by weight to your char, mix and try runing that in your gasifier. It is possible your engine does not like the slow burning CO but a litle hydrogen goes a long ling way in woodgas.
Or, mix some wood chunks in.
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Hi Dave, I didn’t change the mixture valve while it was trying to get up to speed because I had done that several times before, and it got worse whether I went up or down. But in some cases, I did notice it improve from the starting position. The valve is way too big, so I’ll be installing a smaller valve before I try it next.
It does seem to run OK on propane, but it doesn’t seem to handle quite as many watts (2800 running watts) as it is supposed to. I should do a more precise load check on propane, to confirm engine is good.
Today, I made a flange so my spare blower can screw on and blow directly into the air intake. This will make it much easier to check for leaks in most of the gasifier. Unfortunately, much of the reactor and heat exchanger is covered with a layer of insulation and steel, so the inner steel skin of those parts cannot be accessed for leak testing.
Starter fluid is on the list of options to try.
The filters consist of a whole lot of hay plus 4 layers of open cell foam. After reading your post, I wondered if that might be too much filtration for this small application. I did install ports for pressure testing in the hopper and after the filter and I found significant difference of about 3.5 inches of water column between the two places. I assumed this was because of the obstruction of the filter and to a lesser extent, some of the charcoal around the nozzles. I could try decreasing the filter material.
I understand that starting it on propane and gradually shifting to woodgas is another thing to try.
There is so much good information here, it is going to take me some time to try it all. I know it will happen eventually, but I am kind of slow and sometimes I tend to make things more complicated than they need to be.
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Kristijan - Wow! Six likes already! I guess I better wet my charcoal. Looking foward to that hydrogen.
At one point duing the last few unsuccessful trials, I carelessly opened the lid of the reactor while it was burning, and experienced a small explosion. It came as a burst of hot air, but my face was not in the way, fortunately. I remembered then that I had read not to do that. Now I won’t forget.
Anyway, while the lid was open, I did notice a lot of condensation in the upper part of the hopper. There has also been noticeable condensation on the inside face of the sight glass. So even with apparently a lot of water around, I will be adding more water? We do live in a moist climate, but the charcoal looked pretty dry when I put it in.
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Tom, OK, I’ll check for white ash. And I need to figure out whether my charcoal is too wet or too dry. Judging by the condensation in the hopper, the charcoal seems to have significant moisture in it, but Kristijan suggests the moisture may be a good thing. Challenging.
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Hi Greg if your air valve is 1 inch then leave it , it will be perfect for most engines from 150 cc upwards to 500cc , just slight movements at a time is all thats needed ,i have a very small 49cc generator that i needed to use a smaller valve because my big clumsy hands couldnt tune it fine enough with the 1 inch valve so yours should be fine .
Condensation from the old charcoal that has been heated and cooled a few times is normal i think especially if you have forgotten to close of the air intake to the gasifier .
If you find no more air leaks then try starting it again and ever so slowly once again open or close off the air valve leavinga few seconds between each action to allow the new mixture up into the engine and with luck you should hear it pick up .
Can you run your engine of petrol rather than propane ? i was thinking of a float bowl full of petrol allows enough time for the engine to settle while feeding in the charcoal gas .
Dave
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Hi Greg , just wondering how your getting on with running your engine ? or has real life everyday chores got in the way 
Dave
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Hi Dave, Picking and freezing strawberries and other responsibilities. . . I’m trying to determine the best way to seal the small, slightly irregular crack between the two metal faces where the grate assembly bolts onto the bottom of the reactor. Had to fix a stripped thread in the reactor and got harder bolts to stop them from stripping. I’ve considered a fiberglass stove gasket or hi temperature exhaust manifold gasket. Not sure what material to paste on with the gasket. Hoping for something to withstand 600°C. I’ve tried furnace cement and it seems to work, but it’s not made to be removed. Any ideas?
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Hi Greg , i could be way off , but i would have thought being right at the bottom it would not get overly hot down there , and you could even sprinkle in a layer of ash to help protect it from slipped charcoal landing on it , i would just use red RTV and or maybe some flat fiberglass seal , i think Matt Ryder or someone else uses that kind of stuff on there builds for gaskets .
Dave
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This copper rtv is good up to 371 C or 700 F.
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There was a guy who went by the name “doc”, i think, several years ago who built a really nice looking stationary gasifier, all out of SS and powered a 20Kw Onan Generator set with it.
I think he’s the guy who made gaskets by saturating fiberglass matt with red RTV. IIRC, He sandwiched the saturated matt between two sheets of waxed paper to get them to lay flat.
I vaguely remember thinking that the RTV needs oxygen to cure, but he didn’t seem to have a trouble.
Once the material had cured, he simply cut out the gasket shape as needed.
I think this guy was from Florida.
I just saw on one site where that red RTV is only good up to 343°C.
OT, but the last I heard/saw was him having trouble with his hay filter molding from the high humidity down there.
Pete Stanaitis
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I think that was Dan Cox. YouTube name docdcox
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Yes, I am pretty sure that’s the guy.
I couldn’t find any of HIS OWN videos on youtube, though.
Just a note:
There are different consistencies of the high temp red RTV, and I think you’d want the “runniest” kind for that gasket making technique.
Pete Stanaitis
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RTV cures by exposure to air humidity. So cures from the exposure edge/surface inward. The more exposure area; the higher the air humidity; the more “normal” range the air temperature, the faster the cure.
GregC,
Try the flat glue-on, or oneside self-adhesive woven fiber glass tape Dave suggested.
On this curved surfaces, do not try and follow the curve and circle. It will bunch and pucker. Scissor cut straight short lengths going under and past/above the bolt holes. Angle your cut ends as to butt/edge as needed. You can fingers impregnate these once in place with red high temp RTV as you wish.
As Dave said the lower ash buildup will heat insulate this overlapping seam.
Ha! One of the woodstove/gasifier users experience trick is to never, ever OCD completely clean out all of the lower hearth ash. YOU need some, to insulate and seal, always.
Regards
Steve Unruh
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Because it’s a down draft, it gets hot. I measured about 450°C at the air just coming out of the reduction tube. I’ll sprinkle ash and use the flat fiberglass and hi temp RTV and report back.
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