I discovered the midge stove on this site a few months ago and immediately thought this would work great for a barbecue grill. For those of you not familiar with the term a midge is a small wood gasification stove. It is designed to burn wood far more cleanly and efficiently than an open fire. I live in a forested area and always have wood scraps and brush. What I never seem to have when I need it is charcoal. Also charcoal is expensive and wasteful to produce.
Step 1: Set Up
The first step was to construct my own gas wood stove. With the help and inspiration of some great instructables here, I was able to build something that works fairly well. A midge burner is fairly simple in design, it consists of 2 cylinders 1 inside the other. The Inner cylinder is used for combustion. The outer cylinder collects, and circulates the wood gas. A very good instuctable on Midge construction can be found here: https://www.instructables.com/id/Woodgas-Can-Stove/
Through a system of measuring and test fitting; I selected two metal storage canisters from walmart in the dollar store. For my purposes a handle is a necessity. I found one free on a grill at the local recycler. Total cost was about 15 dollars.
The grill I had and is essentially unmodified. This is a cheap charcoal grill, a canister attaches to the bottom to catch and remove ashes. With this canister removed there is an 8 inch hole in the bottom of the grill. I placed a large porcelain pot on the bottom shelf of the grill leaving just enough space for the midget burner beneath this hole. Please keep in mind this is an alph release, version 1. nothing, prototype.(Its redneck rigged ;)
Step 2: Operation:
Fueling and lighting:
The midge burner is fueled and lit outside of the grill. I have been experimenting with different fuel stock combinations. What seems to work best is large wood >> smallwood >> 2 ounces lighter fluid >> then paper. With this combination the burner ignites easily and reliable. There are basically three stages to the burn process.
Igintion: The midge will burn smokey, and uneven for the first 3-5 min.
Gassification: When gasification begins you will notice small flames emitting from the holes in the top of the combustion chamber. The stove will be smokeless, and clean burning. At this point I position the Midge burner, beneath the opening in the bottom of grill. As the gassification increases the flames intensify reaching about 8 inches above the top of the burner. The midge that I built will burn for about 20 - 25 minuites, while producing tremendous heat. During this stage of operation the stove can easily be refuel, the trick is to only add small amounts of fuel at at time.
Cacoal: The gasification process pryrolizes the wood beneath essentially converting it to charcoal. Once all of the wood gas has been consumed this carcoal will continue to burn as red hot embers. The stove will still produce good heat for another 10 – 15 mins.
Step 3: Conclusions/Improvements:
All in all I would say that my experiment is successful. A midge burner is an affective heat source for a barbecue Grill, and a viable alternative to charcoal. I have used this setup four or five times now, with good results. The burner makes plenty of heat, there is no char or carbon in the grill. Most importantly the food tastes great!
I have had a couple problems. First if the midge does not ignite properly or goes out, it will smoke like crazy! Indians may come to your rescue. ;) You can avoid this by using dry wood, and not over filling the burner. When refueling add wood in small amounts. Second too much small wood + too much lighter fluid = FIRE BALL. On one test I had flames nearly a foot tall, and the stove burned out in 15 min.
I got lucky with the flower vase, it was just the right height for my burner. I need to add a stable shelf. The height of flames, and heat produced varies. Ideally the height of this shelf would be adjustable.
I agree with other authors that a well designed midge creates plenty of draft. No fan, or blower is needed. It may be advantageous to be able to control the inlet air at the bottow of the burner. I am considering a metal ring that could partially close off the inlet holes.
Hope this information helps someone out there!