Outdoor Wood Furnace Info
Outdoor Furnaces - Manufacturers with NON EPA-Certified Models Only => Home Made => Topic started by: zimmer988 on January 10, 2013, 03:41:28 PM
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A friend of mine and I are starting construction of a gasification boiler. We plan on building it similar to the Portage and Main 250. We are building it in SolidWorks first to test everything and make our .dxf files for the plasma table. I will post some screen shots of what we have so far. One of the things that I am confused about is building the nozzle in the floor. I would like to make it replaceable. Does anyone have pictures or ideas for me? It seems very difficult to find information on the size and shape of the nozzle.
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:pic:
Here's some screenshots of what we have so far. Still a lot more work to do yet. Just wanted to give you guys an idea of what we have in mind. I will keep posting as the project progresses.
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That looks like a great start!! The only suggestion I want to make is to move your primary air channel down closer to the floor, I'd say around 6" to 7" up. For all the faults in the CB E-2300 that I have, I've recently come to a realization after 5 years. Their original design had it down around 6" off the floor. Problem was they did not make it cleanable. I CAN'T STRESS CLEANABILITY ENOUGH!!! My air channel deteriorated after only two to three years. Last year (season 4) I had a welder help me with a new channel using pipe. Air flow was no longer a problem, but my fire was too centralized around the nozzle and didn't burn well enough on the sides, thus bridging was a problem. Also I got a lot of puffing (kind of like a backfire). I actually had charcoal blast it's way out the chimney a few times as a result if you can believe that. Boiler is located in a building with metal roof and I heard the coals land on the roof. Freaky for sure. I'll attach the picture of that design. The second picture gives a little peak at the old channel. If you look close you can see all the build-up of ash and creosote inside the old channel. Sadly, like I explained earlier the new channel did not produce a stable fire.
So I decided to try another change, but I have not taken a picture of it. I came in through the back wall like before with a 2" nipple to a verticle"T" with a bushing at the bottom so there is still a drain for creosote (very important to consider) and some air can blow from there also. Short nipple up to another horizontal "T", sized down to 1 1/4", then pipe to each side and elbows forward along each side. I ran the channels up on top of the old channel for support. First I tried it with my outlet holes aiming mostly downward instead of straight outward like they had it, thinking this would also allow for creosote drainage. Problem with this was it burned the coals right out from under the wood. So I aimed the holes up some, not all the way. Basically at or just above the nozzle area. This thing is burning better than ever!! Good consistent fire, clean with very little smoke and minimal bridging issues.
The guys I've seen on here with the P&M 250 seem very happy with performace of those units. I've never seen one so I don't know how much it differs from the CB E-2300 design. The way I see it with my unit having the lower air channel is that it puts a nice even flow of air over the whole coal bed.
Good luck with your planning and building. Looks great so far. Keep us all posted!!
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Thanks for the tip. I will move the air tube down to just above the angle in the firebox. I made the air tubes flanged so that they would be cleanable, replaceable, and easily modified. I do not plan on welding them up against the firebox wall but maybe just have them sit on top of some tabs welded to the firebox. I also have them running through a larger tube so that the tube that would be in contact with the boiler water would not also be in contact with the smoke and creosote to help prevent rusting through to the water jacket. How often will the air tubes need to be cleaned? More than once a season? I have 2" square tubes in the drawing but maybe round would be better. Are the under fire air tubes prone to creosote buildup too? I plan on burying them in refractory cement.
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I've never heard of anyone having trouble with buildup in secondary air tubes. Just a little dust here and there. Never been a problem for me. To help with primary tube build-up, I'd put a couple of holes in the bottom of the tubes. A good place for a drain is near the back just inside the firebox. I'm wondering if it's partially caused by condensation on the air tube since relatively cool air is flowing through there, but I get a lot of creasote/tar buildup around my back wall. Although, that is also the farthest wall from the fire as my burn favors the front of the stove so I stack the wood as close to the door as possible.
It's hard to say for sure how fast it could plug up. With the new air channel I built from pipe, I used 2 bushings to drop from 2" down to 5/8" I think. After a week or maybe a week and a half, I pulled the channel out to inspect it and found the drain was plugged and was built up to the air inlet hole. So I removed one bushing leaving about a 1" drain and it is working great so far. I have not had it back out to inspect again since, however.
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I have 2" square tubes in the drawing but maybe round would be better.
I am not sure how dirty the tubes would get with your design but there is bound to be some loose deposits.
I would think round tubes would be better because it would be easier to source a round brush to clean them.
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Def use round tubes
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Thanks for all the great tips! We have designed quite a bit more on the boiler, but we only get work on it for a few hours once a week after work. We changed the top of the firebox to have 45 degree corners and the bottom has 60 degree. I am going to change the 2" square tubing to 2" pipe and add another one so that there will be one at the top corner and moving the existing one down to the bottom corner. I will leave the floor air the same. This will give me some flexibility on how I can bring air into the firebox. With my flanges, I will be able to seal one off if not needed. Better to have it and not need it than to need it and not have it as I always say. After we get a bit further, I will post more pictures.
Thanks again everyone!!
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Looks like a great project. I'm in the process of building pretty much the same thing. I had my fire box rolled and i put a flat bottom in it. I'm going to be using threaded pipe for the air so it can be removed for cleaning or replacement if needed. What size tubing you using for the exchanger? I was thinking 2 x .120 for the verts and 1.5 x .120 for the horizontals. I was originally going to use pipe but all I could find was sch 40 which is a little heavy for efficient heat transfer. Good idea you have there with the air tube inside a larger one through the water jacket. . I also am a little confused on the nozzle. I like the firebrick idea some on here suggested. Simple and cheap. Keep us posted.
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I managed to get a few pics of my new primary air channel in my CB E-2300. As long as I keep the drain hole clear so creosote can drain out it is burning great!!!
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Here's some more pics of the boiler. We are almost finished. Just making up the .dxf files for the plasma table and generating parts drawings. The water jacket is 4 ft x 4 ft x 8 ft tall. Not sure on the total water volume yet. I will have to calculate all of the internals.
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Looking good! Will you share the SolidWorks files when your done?
John
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i would also be interested in the file when complete if possible
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I will probably post it for you guys to use but I will not be responsible for any errors.
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That is fine with me and thanks for sharing. Mainly I'm interested in looking at your design from different view and such and being able to open the 3D model up in SW makes that easy.
John
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Looking forward to your build Z.
Bookmarking this thread. :thumbup:
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Well I finally got started on the fabrication of my boiler!
You can check out some of the pictures here: https://www.dropbox.com/sh/h4lbsxbz8g5ckco/snOXOEeL1E (https://www.dropbox.com/sh/h4lbsxbz8g5ckco/snOXOEeL1E)
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That thing is a BEAST. Can't wait to see and hear about yours too.
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Alright, glad to see a current build thread!
Looking good, nice pics. I would be interested in a better angle of how you laid the firebrick in the secondary. It looks like your nozzle is in the middle of the burn chamber? Does the firebrick route the gases forward first- or is it just open to go back towards the heat exchangers? I'd also like to know what firebrick you used, I'm trying to lay my secondary out in CAD with the brick, to minimize cutting.
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Nice build!! Looks awesome and looks like you have the equipment to do it too!
Brings back memories of my build but mine didn't turn out that nice.
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Actually, I will be using refractory cement instead of firebricks. I have not put the cement in the boiler yet though. That will be done once I get the water jacket on and tested for leaks. I may lay some firebricks under the nozzle so that they can be easily replaced.
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I have heard that the refractory cement is really hard to work with and expensive. Do you have any experience with it or just going to give it a go? Personally I always like to give anything a go and see what I can make happen.
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I have never personally used it but I have some connections to help us out.
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I added a few more pictures to the Dropbox of our build. We decided at the last minute before we put the top on to add a pipe for possible future burning of wood chips. We installed a flapper on the bottom of the pipe that will be counterbalanced closed and will also build and install a rotary valve on the top side of the pipe to meter in chips fed from an auger. That part will take some more designing at a later date. We thought we should do it now to make it easier down the road.
You can check out the pictures here: https://www.dropbox.com/sh/h4lbsxbz8g5ckco/snOXOEeL1E (https://www.dropbox.com/sh/h4lbsxbz8g5ckco/snOXOEeL1E)
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That is some IMPRESSIVE S***. Good job!
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I see you have 3 air channels into firebox, whats the purpose of the top inlet? Most I've seen use air midway or even lower, and air at the nozzle. I guess its better to have it and not need it than need it and not have it?
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You guys that can design, weld, fabricate so well are awesome! Super nice job. :)
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I finally got this boiler installed and have it heating my house and a 45x60 shop with floor heat. It works great!
https://photos.app.goo.gl/YY3SUF3RA7HLLSeeA (https://photos.app.goo.gl/YY3SUF3RA7HLLSeeA)
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I am also measuring the temperatures with a Click PLC and some ESP8266 flashed with Tasmota. I have the readings going to my Home Assistant instance and logging the data with InfluxDB and Grafana.