Run Wetter Fuels in Your Gasifier
Part of the drawback of gasification is the need to use drier fuels. A moisture content of less than 20% is generally required. During WWII, when gasifiers were heavily deployed for driving, a new type of fuel hopper was created by accident. The Monorator (right schematic pictured on the left) was designed as a low profile hopper to allow better driver visability. The beneficial byproduct was that water was able to circulate and condense at the outer edges, leaving the fuel drier for proper combustion at the center. This allowed fuels with up to 45% moisture content to be used. This design was especially popular in Northern Europe where the climate is wetter.
In a standard design the moisture condenses along the top and some does make it into a condensate drain, but the turbulence in the vertical shaft causes it to mix with the tarry vapors and ultimately get pulled through the reduction zone. This is where the moisture content is so vital. If there is too much moisture, the heat required to vaporize the water will quench the combustion zone and keep the temperatures from rising high enough to crack the tars. Tars and water vapor end up mixing into a wet black mess in your filter system.
The monorator is not commonly used outside of Northern Europe because it isn’t well understood. If you decide to try this design, then let us know your thoughts on it’s success. You can also use waste heat from your gasifier to pre-dry your fuel in a separate container if you decide to build a more common design.
Tags: fuel drying, gasifier design, monorator
