Gasifying workshop boiler

[paulmowers]

Hi All

Anyone remember my prototype gasifying boiler from last year? Well it kind of got to the point of being installed, one test firing which was a bit disapointing as it failed to burn downwards, just smouldered and then went out.

Had a major refit in the house at the time with fitting a rojek wood boiler and accumulator tank, so with the choices of a warm house or warm workshop, went for the warm house option and the workshop under lpg heater for another year.

Till today when I decided the reason it failed to gasify was due to there not being a large enough gap in the base of the firebox for it to draw the flame down and then mix with the secondary air.
So today out with the plasma cutter and I doubled the width of the slot to just over 1/2" wide, it was the width of a cutting disc 6mm ish.

Second test burn, and it roars like a little jet engine, burning scrap ends of powdery wood and sawdust. And the heat exchanger is getting very hot which should be good when I get the plumbing sorted and some water in it.

First pic is of the fire from the fire door, only problem with trying to take pics is once a door is open the air flow is disrupted and the gasifying (downward burn) process stops.
Which is why the second pic, of the secondary combustion chamber shows a rather pathetic little flame as opening the door stopped the burn.
Pic three is the beast from the front.

Paul..

 

[danelectro]

don't suppose you've got any plans for that baby?? I got me a gas bottle that's crying out to be converted, but not sure of the principles behind a gasifying boiler!!

 

[paulmowers]

give me a few days and ill draw up a couple of sketches and post them on here, i'll dig up some of the build pics too which are on the office pc.
The basics behind the principle is you have a slow burning fire with restricted air, normally the resulting smoke / gas is drawn down through the hot coals by the draw of the chimney, at this point it is mixed with an inlet of secondary air (preferably warm) which causes the gas to ignite and that is your secondary burn, which results in a very clean flue gas, hopefully just co2 and water.
it is easier to understand with pictures.

paul

 

[danelectro]

Hi Paul,

That'd be great if you could, I'm very keen on building one!!!

Cheers

Neill

 

[prepman]

I'd be greatly interested also. If you would
include me in any circulation, much appreciated.

Thanks Phil.

 

[jugs]

I'd be greatly interested also. If you would
include me in any circulation, much appreciated.

Thanks Phil.

And me

 

[paulmowers]

Hi Guys

Well I managed to find time to do a bit of a sketch of it which should appear below.
As you can see hopefully it is made of 2 cylinders which make up the fire box and the heat exchanger, for the secondary burn chamber I used a bit of digger arm which had extending webs down each side, so welded a lump of 1/4" flat over these to make a water jacket under the chamber, and a couple of lumps of 3 x 3 box along each side, both join into the main water jacket around the heat exchanger at the back.
As you can see from the sketch there is a baffle at the top of the firebox, this is to allow easy lighting, whereby the secondary burn chamber door is opened and the air flows through the gasifying slot at the base of the firebox through the fire and smoke exits past the baffle at the top and into the top of the heat exchanger, primarily to heat the secondary air tubes abd then out through the flue.
Once its burned for a while the lower door is shut and the secondary air baffle is opened a bit and the baffle at the top of firebox is shut, at this point the chimney draft sucks the fire gases (smoke) back through the fire and out through the gasifying slot, at which point they are mixed with hot secondary air which causes them to burn, the resulting flame and heat travel through the burn chamber (digger arm) and up the heat exchanger, heating both the water jacket and the secondary air pipes which keep the process going, as the secondary air has got to be hot.
Wether you intend copying my design or doing your own, one thing you must build into any burner / boiler of this type is ample adjustment of all variables, this is essential to getting one to work properly.
1. Adjustable primary air intake (air to the fire)
2. Adjustable secondary air (to the secondary burn chamber)
3. Some kind of flue damper (to slow the burn if needed)
If I could build mine again I think I would have used 2" pipe for the primary air rather than the 1 1/4" I did use.
Also there is probably a better easier way to build one of these but the main thing that made mine look the way it does was simply the materials I had to build it from.

am going to put another batch of pics up as ive run out of space on this post

paul

 

[paulmowers]

ok next batch of pics

 

[paulmowers]

Yes i know theres a bit of a gap between semi built and finished, but during the build i got to apoint where I could see how everything was coming together and just sort of carried on forgetting to take pictures.

Hope it all makes sense.

Paul...

 

[danelectro]

Paul, you're a diamond!!

I think i've got the principle now!!

Thanks very much for posting that.

Cheers

Neill