Homemade Gasifier

bigredowner · Feb 22, 2015

Hi everyone, my names Aaron I'm new to the forum. I am a proud owner of what I call BIG RED, my homemade gasser. I am in the excavation business, but also own a welding shop, so I decided to build a gasifier myself to replace my central boiler. which is a story of it's own, rotting from the outside - inward under the spray foam. This after only 15 years! Anyway I will attach some picts and answer any questions should anyone be inspired to take on a project like this. A few stats. the boiler is 3/8" thick fire box, 1/4" water jacket and boiler tube design. the fire box is around 45 cubic ft and the boiler holds approx. 550 gals of water. Yes I have a huge heat load!

bigredowner · Feb 22, 2015

lets build a firebox.

bigredowner · Feb 22, 2015

bigredowner · Feb 22, 2015

exchanger

bigredowner · Feb 22, 2015

Exchanger attached to firebox

bigredowner · Feb 22, 2015

1/4"

water jacket!

bigredowner · Feb 22, 2015

Air tubes and blower housing. Blowers are mounted external in a louvered box. All these manufactures mount the blowers inside the back of the stove. Often they louver the back access door to get combustion air in there. To me this is stupid! A major heat loss!

You can see the louvered door/box housing the blowers on the right.

bigredowner · Feb 22, 2015

blower box.

bigredowner · Feb 22, 2015

bigredowner · Feb 22, 2015

bigredowner · Feb 22, 2015

I load the big rounds with a skidsteer. And BTW for those that say unseasoned rounds wont gasify they are mistaken!

kuribo · Feb 22, 2015

Amazing work!

What's your flue gas path through the boiler? Where is the gasification happening?

bigredowner · Feb 23, 2015

kuribo said:
Amazing work!

What's your flue gas path through the boiler? Where is the gasification happening?

Thanks kuribo.

Here is a rough diagram. This pic. was taken before the floor was fabricated. Where you see that black line there are 4 pieces of 2"x4" rectangle tubing, it isn't cut and welded in place in this pic. I have tabs welded to the tubing on the bottom (sort of forms an upside down tee) 3/8" plate sits on the tabs in between the pieces of tubing. Firebrick is placed on top of the plate to make the floor. I did it this way so the whole floor could be taken apart. The floor has a 2" wide x 9" long opening for the smoke to travel through with a grate over that in the fire box

. I inject air at this opening through a 3/8" hole in the side of the fire brick. the air is from a 78 cfm blower.

ewdudley · Feb 23, 2015

So floor is water-cooled?

brant2000 · Feb 23, 2015

Awesome, that thing is beastly. From the looks of the construction, it will certainly outlast you (not a joke on your age).

I have been looking at a number of these home builds and thinking about doing something similar, but I have a few questions:

It doesn't appear that there's any means for bypass, during startup. Is that correct?
Do you have any means to control the primary/secondary air blowers? If so, is that just a manual adjustment?
Do you find that the entire firebox becomes engulfed in flames/combustion? I was thinking it would be great to have a very tall firebox, that would provide more controlled, longer burn times by allowing only the wood to burn near the bottom? Would that be possible, or would the entire box burn uncontrollably?

peakbagger · Feb 23, 2015

Do you have a large thermal storage tank somewhere? I am curious if you don't, how do you get turn down to match the output to the demand.?

woodsmaster · Feb 23, 2015

Do you have a refractory lined nozzle and lower chamber ? if not Id be worried about ruining the steel.

Mike Fromme · Feb 23, 2015

brant2000 said:
Awesome, that thing is beastly. From the looks of the construction, it will certainly outlast you (not a joke on your age).

I have been looking at a number of these home builds and thinking about doing something similar, but I have a few questions:

It doesn't appear that there's any means for bypass, during startup. Is that correct?

Do you have any means to control the primary/secondary air blowers? If so, is that just a manual adjustment?

Do you find that the entire firebox becomes engulfed in flames/combustion? I was thinking it would be great to have a very tall firebox, that would provide more controlled, longer burn times by allowing only the wood to burn near the bottom? Would that be possible, or would the entire box burn uncontrollably?

I have indoor gasser with the bypass and almost never use it. If I was building an outdoor gasser I would not got through the trouble of incorporating one.

bigredowner · Feb 23, 2015

ewdudley said:
So floor is water-cooled?

not really....there are 4 pieces of 2"x4" tubing one at the back, one at the front and two evenly spaced apart in the center. They do have water in them. there is fire brick between them sitting on 3/8" plate. The plate isn't welded to the tubes. As I said above there are "tabs" or pieces welded to the bottom of the tubes, the plate that holds the brick rests on. I did it this way, so the floor could be pulled up if needed. So in short the tubes get heat transfer from the exposed 2 inches on the bottom in the secondary combustion chamber and the exposed 2" in the primary under the coals, but the majority of the floor is fire brick.

bigredowner · Feb 23, 2015

brant2000 said:
Awesome, that thing is beastly. From the looks of the construction, it will certainly outlast you (not a joke on your age).

I have been looking at a number of these home builds and thinking about doing something similar, but I have a few questions:

It doesn't appear that there's any means for bypass, during startup. Is that correct?

Do you have any means to control the primary/secondary air blowers? If so, is that just a manual adjustment?

Do you find that the entire firebox becomes engulfed in flames/combustion? I was thinking it would be great to have a very tall firebox, that would provide more controlled, longer burn times by allowing only the wood to burn near the bottom? Would that be possible, or would the entire box burn uncontrollably?

Brant - I did put a bypass in there. It wasn't in the pics, but if you look at the picture facing the front with the heat exchanger attached, I put a 8" pipe from that heat exch. box down into the fire box. I ended up cementing it with furnace cement. The cover and pipe weren't milled and I didn't incorporate a gasket in the build. though the fit was tight, it was letting a surprisingly amount of smoke through and into the tubes from the firebox. If you look at the tenth picture of the back of the unit those pipes are the air intake, and can be adjusted by the ball valves. By luck, I just run all 3 pipes wide open, haven't had to restrict them. With this unit, as well as most I believe, you will find its not a rip roaring fire when your door is shut. Remember with a gasifier, by design you are somewhat chocking the fire by making the smoke pass through an opening smaller than a conventional wood burners flue. At least with this unit, when you open that door while the blowers are on, you have some major flames dancing out!

bigredowner · Feb 23, 2015

woodsmaster said:
Do you have a refractory lined nozzle and lower chamber ? if not Id be worried about ruining the steel.

Yes, nozzle is firebrick. floor and ceiling of lower chamber is fire brick, side wall of lower chamber is heat transfer area = steel water jacket and it's 3/8". I have to add, this fire brick is the real deal. It is old school came out of a local tannery that was being demolished. The brick is impregnated with steel mesh, went through several diamond blades cutting the stuff!

bigredowner · Feb 23, 2015

Mike Fromme said:
I have indoor gasser with the bypass and almost never use it. If I was building an outdoor gasser I would not got through the trouble of incorporating one.

I agree 100% I did put one on this and ended up cementing it shut.

bigredowner · Feb 23, 2015

peakbagger said:
Do you have a large thermal storage tank somewhere? I am curious if you don't, how do you get turn down to match the output to the demand.?

I don't need a storage tank. The unit holds approx. 550 gal of water, however it cycles on and off several times an hour. I fill the 45 cubic ft firebox twice a day.

maple1 · Feb 23, 2015

Fill it full?

That's a full cord of wood every 3 days if so - yikes.

stee6043 · Feb 23, 2015

maple1 said:
Fill it full?

That's a full cord of wood every 3 days if so - yikes.

He loads with a skid steer, unsplit, unseasoned, hold the mayo. It's a badass project but he's surely not trying to win awards for efficiency.

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