[Gasification] coal gasifier flamethrower pix v1.0

[jim mason]

last weekend i finally relented with my prolonged off-gassing about it
and actually built a working gasifier rig.   pictures of a bit of the
process and final flame can be found here:
http://www.jesshobbs.com/gasifier1.0/

the pix show a short chemistry lesson on what is happening, to educate
the locals.  welding and plumbing.  then coffee drying on the wood
stove, then filing the coffee grounds into the unit.  set up of unit
in yard.  various lighting attempts, with success after awhile.  then
some poofs on a combined fuel of coffee and wood.  then the hot tub
and champagne reward afterwards.  (we were trying for midnight new
years eve, but didn't actually get it fired until 1am.)

at this point i have so many esoteric gasifier designs in my head,
with more seeming to arrive daily, that i decided the only way i'm
ever going to actually build one is to just build the most simple and
quick one and be done with at least one.  then elaborate from there,
with iterative complexity.  far more will be learned by building
multiple ones, with progressive complexity, then trying to straight
out build the imagined "perfect" end one.

so in two days we built an updraft rig from an old air compressor
tank.  i was a bit stunned how easy it is to build and get basic gas,
as well as how flexible it was on fuels.  of course this was tarry and
wet gas, but it burned clean as nat gas on your stove.  even running
coal.  clean coal is not a myth . . . ;-)

the compressor tank we used is 6" in diameter and about two feet long.
i put a angle fill pipe about 2/3 of the way up.  the gas outlet is an
existing 1/2" pipe fitting in the tank.  the distance difference
between fill point and gas outlet was to encourage dust settling, and
used a gravity loop for the air in at the bottom.

as i have been long confused about the grates, and didn't have
anything to use that was fine enough or heat resistant enough, i
decided that a pipe that protruded to the center of the tank in the
base, and then curves upward outside the tank, will allow air in and
not allow fuel out.  it would likely be a bit better to curve the pipe
upward inside before the ends, but i just have it ending straight
sideways in the bottom.   my other main reason for this was that i
wanted to be able to run dusts, like coal dust and coffee grounds,
which seemed like a difficult proposition for grates.  so gravity was
engaged.

the resulting sideways air hole at the bottom of the tank also created
a nice lighting hole.  i'd fill it with gasoline and light it and the
whole thing would take right off.  about 30 seconds until the flare
would light.  real easy.

 i coupled the gas output with an air compressor pump to pressurize a
second tank, so i could have a little burst flamethrower.  we do lots
of pyro things around san francisco, so i decided to make my first
gasifier a flamethrower.  previous flamethower efforts for burning man
in the nevada desert are here: http://whatiamupto.com/ICP/index.html.
but these are kerosene and gasoline, pressurized with nitrogen.

with the gasifier, the gas energy density was too low to work well as
a burst flamethrower as the gas burst would blow out the pilot.  but
it ran very nicely as a torch/flare nonetheless.

we ran it on sawdust, cubed wood, coffee grounds and coal dust.  all
worked fine, but the coffee grounds were very difficult to get to
light.  though once lit, they burned fine.  it should really run on
any biomass that is reasonably dry and dense.

i was surprised to see htat yes, gasified coal burns with a clean blue
flame like the flame on your stove.  actually, all the fuels produced
an absolutely sootless fire of pure blue flame.  the case for
gasifying before combusting for solid fuels was pretty clear watching
the flame.

this weekend i'm building a very simple stratified downdraft, and
likely coupling it to the current wood fired boiler for our hot tub.

j