Post
by BigBarney » Mon. Feb. 07, 2022 4:45 pm
Most of the people burn wood in these gasifiers not coal, you have much more flexibility
with coal because of the low water content , so much less of the energy is used just to ev-
porate the water in the wood , sometimes up to 50% water content in wood even dried
25% is common. The second point is that they have to have heated chamber to be able to
make the gasification start , whereas in a coal unit the glowing coal itself provides the heat
for the reaction to occur.
One problem with coal is that it has much more ash so the straight down path is not
possible so a exit chamber near the grate is used. That way the ash can accumulate there
and can be removed by using a riddling bar or rod. My unit doesn't run out of coal it runs
out of air and needs to be serviced by riddling the ashes out of the top of the grate to continue
its burn , 12 to 24 hours apart except in sub-zero weather.
Most of the videos on youtube do not have a good enough control of the air in the top
to be able to create the gases needed for combustion.If you open the fill door care must be
taken because you have a volume of highly flammable gas that can cause an explosion and
personal injury and damage, once you do it thousands of times you get used to use caution.
None of these home built units can be true gasifiers because they usually have no way to
add a continuous supply of fuel and air at exact ratios to be able to run steady for days on
end. My boiler adds the air below the grate an keeps a hot fire above the grate and causes
the gases and smoke to constantly heat the coal supply in the magazine and cause the coal
to sweat out gases which are highly combustible ,because solid coal cannot burn only the
gases. When drawn out through the chimney they draw in secondary air to complete the
process to the heat exchanger and the water heating. This is where the videos were taken
looking right into the burning mass.
Any type of fuel can be used wood , coal , tires , hay, anything that's combustible.
BigBarney