This project goes over the build of an efficient outdoor wood burning stove heater out of an old propane bottle and some scrap metal from the scrapyard. This stove has secondary burn system that helps in combustion of any unburned smoke or fume inside .Almost little to no smoke coming from the flue pipe.
The first step is to make sure that the old propane tank is empty. We take the valve at the top by removing the valve protector cage. Fill the tank with water and let it sit for a few hours before we drain the tank and start cutting top and bottom.
With the help of a hole saw cutter ,we cut 100mm four inch holes at the top and bottom of the tank . The top hole is for the flue pipe to sit in and the bottom hole is for cleaning the ashes out. We also remove the bottom stand too.
Next, we cut a hole for the door for the stove. This is cut as high up to the top of the bottle . The door is made of chequered plate piece . We fit a rectangular pyrex dish glass piece in the middle of the chequered plate that can withstand high temperature with couple of steel bracket pieces.
The glass on the door helps us to see how the secondary burn system is working inside the chamber. The door is attached to a frame through hinges.
The flue outlet on the top the tank is attached through a flange piece with holes. The door handle is made of a socket wrench. The wrench is bolted to the plate and a small metal piece is welded onto to the frame to which the wrench is pulled to close the door
A deflector plate made of small holes is installed inside the stove on the top . We drill 8mm holes around the top of tank and put dome bolts across them. The deflector pipe sits on these bolts. The deflector plate stop the unburned gases exiting out the flue outlet pipe. This encourages the flame that rises, pass through the deflector plate holes into the secondary burn chamber that helps in better combustion.
The secondary burn system is made of stainless steel pipes .The air intake section is long enough to get the air coming in to get super heated and move into two sections filled with holes.
Since not all gases from the wood combust from the primary air intake, the secondary burn pipe ensures that the air gets super heated before exiting the pre-drilled holes and helps burn the unburned gases rising from the fire before exiting the flue pipe.
The secondary air intake pipe coming out of the firebox is welded on the top of the tank with a flange piece. The primary air intake pipe that goes under the door frame is made of a two inch coupler and threaded damper disc. A small metal piece is welded to the coupler with a hole in the middle. The damper disc screws in through the hole that allows us to close and open the intake .
- How to build a Multi Use Simple Homemade Wood Gas System from Scrap Materials that can be used as a Generator,Cooking Stove and LanternThis project goes over the build of a simple gasification system that functions to produce wood gas for running a generator, a cooking stove and for lanterns. We feed the wood chips and other materials through the opening at the top of the gasifier ,the air also gets drawn in from the top .The air would drop through the wood mass, down to the reduction zone and gets collected down at the bottom of the tank through the output pipe . The materials needed to build this down draft style gasifier are a 3 old propane tanks, old steel sheets, wood pellets. The first step is to make sure that propane tanks are empty .Remove the handles from the top of the 3 propane tanks and unthread the valves. Cut the top portion from 2 tanks and stack the body of the tanks on top of each other and weld it. One of the cut out top pieces can be used a lid . The bottom portion of the lower tank is cut open to create the reduction zone of the gasifier. To make the reduction point, we take the scrap steel sheet and make a five inch wide small tube of the them and weld them to the bottom third propane tank . The bottom five gallon propane tank is used as a ash bin where all the ash is going to get caught and as an outlet for all the gases coming out of the system. The top portion of this tank is cut in such a way that it fits the reduction zone collar of the secondary tank. Make sure that both the tanks fits nicely together so that you can pull the inner chamber out of the bottom ash tank to remove it, dump the ash catch out and use it again and again. The top of the upper tank is cut open .This acts as the feed area where all the wood pieces are dropped in. We make a screen with holes using a 20mm hole saw cutter from the leftover cutouts of the propane tank. We are gonna mount this screen inside the gasifier lower reduction zone. A hinge and a wire is attached to the screen so it can open and close. This gives us the ability so we can shake the screen if it plugs up with ash or other materials. The wire goes through the reactor up to the top . We have a pressure relief system installed on the lid of the gasifier. If anything were to happen inside of the gasifier , the build up pressure can be made to escape through the top lid .This is done by hooking up two springs on both sides of the lid through small loops .The springs on both sides is attached to hand levers. We drill 8 half inch diameter holes just above reduction zone area and put thick steel tubing through them to the center of the chamber. The airflow will go in and be drawn down through the center of the reduction zone that helps in efficient burn. The pipes are curved in to the chamber so that it does not interfere with any wood mass as it goes into the reduction zone. We add plugs along these 8 tubes to regulate the air flow into the system. Next step is to add the draw fan to the gasifier. Here we use a pellet stove fan .We add a 2 inch plate over the face of the fan and a threaded pipe to seal any air going into the gasifier. We start up the gasifier by putting some chopped wood through the top and use the fan to get the wood gas producing out of the bottom outlet pipe. https://www.youtube.com/watch?v=h9vuphZe8iU
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