My Boiler Design -PICK IT APART!

sixmenn said:

Hi all.

Attached are some diagrams of a boiler design I've been thinking of. I'm posting it to get as much criticism (the good and the bad) as possible before I build it. Please feel free to put in your $0.02 as often as you want. Thanks!

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It looks like a non pressure boiler so this is good, Mich. would not allow a press. version & I wouldn't bet it would be safe anyways. I don't see good heat transfer in this after the tanks get creosoted up. You can only clean a limited amount of surface from the door. It looks to be just a "smoke dragon", do you have close neighbors? You would probably be much better off buying a used OWB for $2,000 than building this, Randy

Secondary burning requires the introduction of oxygen into a veyr hot chamber to burn up all the otherwise "up the chimney" gases. Proper ratios (wood gas to oxygen), proper mixing (turbulence), and proper insulation (refractory) is all required to make this work. All the "gasifying" boilers we focus on around here do exactly this.....they "burn" the wood in a primary chamber, really just to create wood gas, search on pyrolysis, and then this wood gas is introduced into a secondary chamber, along with preheated air, and it burns in this chamber at temps > 1600F. SO the efficiency is greatly boosted (in the 80's), emissions is greatly reduced, and there is little creosote (as long as the burn is fast and hot....not on/off with heat demand).

It doesn't look like your idea would create the "secondary" burn....and any type of fire "on/off" would cause the fire to smolder...and everything then would be pretty covered in black goo.

Woodstoves these days introduce secondary air near the top of the stove typically, which is lined with refractory to make it very hot (a top chamber as well), and this gets some good buring of the wood gases, increasing eff. and reducing emissions. But if the fire is allowed to smolder, as in anything really, this is a problem.

You need a secondary burn chamber for complete combustion....I was going to make something like this using propane tanks-:

sixmenn said:

Thanks for the reply. I appreciate your input.

I was thinking that the smoke and unburned gases would rise in the refractory-lined burn room and get burned up there in the area of the tanks (and burning off any creosote in the process). I placed the vent from the burn room to the chimney at the bottom so only the cooler gases would escape out the chimney. The criss-crossed water pipes in the pre-chimney area at the rear would help remove any extra heat before exiting out the chimney. I thought these aspects of the design might help eliminate excess smoke....

Hmmm...... Any suggestions for improvements?

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I would put a blower in the front, the type that Royall uses. This is available from Grainger & looks like a very small squirrel cage hair dryer. Make a flap that you can adjust over the blower intake. You will need some air right down at grate/floor level or idealy under grate air. You will need some overfire air to clean up the burn. Make everything adjustable. You don't want too much blower air or it will drive the heat right out. I think you can clean this up quite a bit that way, Randy

For the overfire air I would suggest 4 horizontal jets, 2 on each side blowing directly at the other 2. You could run 1 1/4" shed. 40 pipe for the manifold & put pipe caps on the end with drilled holes for the jets. They could be easily tuned that way. I would put the overfire jets about 3/4 of the way up from the floor, Randy

I'm going to have a used Adobe with a perfectly good heat exchanger that would be a better place to start a build. I am not going to put any more into this boiler. So make me an offer. Looking at your design, I am in agreement that it will fill up with creosote and fine ash.. Jim

sixmenn said:

Singed Eyebrows said:

For the overfire air I would suggest 4 horizontal jets, 2 on each side blowing directly at the other 2. You could run 1 1/4" shed. 40 pipe for the manifold & put pipe caps on the end with drilled holes for the jets. They could be easily tuned that way. I would put the overfire jets about 3/4 of the way up from the floor, Randy

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Thanks for the description; it was easy to understand and looks easy to build. In your opinion does my design have enough merit to warrant efforts to perfect it, or would I be better off going another way?

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Your design will never be a gasification boiler, either Garn like or downdrafter. What gives me pause is those cold tanks hanging in the firebox, I would not build a boiler that way. You might want to search for another design, Randy

Sixmenn,
Do you value your time? Do you mind throwing it all away if this design doesn't work?

Why not just copy a proven design...or are you trying to reinvent fire?

Search the internet, there used to be a concrete block building with sand and pipes that was a DIY outside water heater with no welding. I can't for the life of me remember what it was called though. There was another one called DEBS but I think that one needs welding.
Good luck!
dave

I just stumbled across this and thought you might find it interesting.
http://science.howstuffworks.com/environmental/green-tech/energy-production/gasification3.htm