The Mulchifier: A gasifier concept for the use of low quality chips
What to do with those small lousy wood chips that tend to plug up gasifiers?
This is a gasifier design that I have been kicking around in my head out in the shop. It makes use of low quality chips.
How it works-
The upper area is a standard downdraft gasifier. The char fines that are developed and plug the reduction bell, causing lower velocity, are consumed in the lower zone with a crossdraft architecture.
This does several things:
- Char fines get converted to fuel gas for greater efficiency and flow
- More heat is released up to the reduction area of the downdraft to aid in the water gas shift reactions, allowing the use of wetter fuels and needed additional tar cracking.
It is very important that the crossdraft air is introduced well below the gas path for the upper section to avoid combusting the gas and releasing heat with no downstream fuel value.
Using this design I believe mulchy type chips with a moisture content up to 25% could be utilized to make a clean gas. Initial research should be conducted with a 4 cylinder engine providing the suction, then moving progressively smaller to establish a boundary.
You guys that are about to start a build, may want to consider trying this.
Tags: mulchifier
Comment
-
Comment by DAVID ORRELL on March 7, 2010 at 3:28pm - HI, WHAT IF YOU HAD A GASIFIER DESIGN THAT HAD A VERTICAL SHAFT WITH STIRRING FINS THAT ROTATED ON A TIMER TO KEEP THE FINES MIXED UP AND AIR CIRCULATING ?
-
Comment by paul czarnecki on March 4, 2010 at 9:55pm - lmao now under designs you have to add the (cross down draft),,,,,,but seriously i think im going to build one ....cant see any reasons why it shouldnt work--this might be a good one for the garden tractor hmmmmmmm
-
Comment by ben on March 4, 2010 at 9:37pm - I haven't tried it so I couldn't say. We will just have to see what happens. With finer fuels like mulchy chips you can usually make the nozzle ring a little smaller to get proper penetration.
-
Comment by paul czarnecki on March 4, 2010 at 9:20pm
- what are your thoughts on mixng alittle of the finished gas in the tuyeres (like jets on a gas furnace burner) to up the heat?
-
Comment by ben on March 4, 2010 at 8:45pm
- Yeah, I have the parts to try one of these, just looking for the time. It will take a little playing around with to get the sizing right, but I think it will work too.
-
Comment by paul czarnecki on March 4, 2010 at 6:49pm
- this may be what im looking for! after the weather breaks im gonna give it a try---maybe the 1st actual design that works on chips ,makes good sense to try to do a second burn with the char--looks like a winner
-
Comment by ben on March 4, 2010 at 6:38pm
-
David,
If you don't want to do any cone shapes you can do a choke plate. Then a natural ash inverse cone forms on top and on the bottom the gas and char are still allowed to expand. The reason for the cone is to give room for the gas flow as the char breaks down into finer and finer particles. As the char gets finer the spaces between get small and there isn't anywhere for the gas to flow at the speed it needs. As the bell or in your case the chamber expands in size it allows enough room for the gas to flow through.
What you are going to do is have a 10" wide hearth cylinder for example and 3 or 4 inches below your tuyeres you are going to put a circular plate in there with the proper size reduction hole. Simple and functional.
-
Comment by David Siedschlag on March 4, 2010 at 6:05pm -
Ben,
So by the looks of your concept picture your proposing a straight reduction tube? I havn't started building yet, and I am looking to make a very simple design, without all the cones, or cast hearth, etc, and this looks like it might be it. Can you give me anymore details on how it could/should be layed out?
Thanks
David
PS. Please see my new discussion in the fab shop, and give me your input if you have time. I know your very busy with r&d, and making a living. I know how that goes with the pelleting thing were doing.
Welcome to
Victory Gasworks- Gasifiers and Wood Gasification
© 2010 Created by ben.
You need to be a member of Victory Gasworks- Gasifiers and Wood Gasification to add comments!
Join Victory Gasworks- Gasifiers and Wood Gasification