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re: best way to burn trash
26 dec 1997
kirk kerekes wrote:
>if your "barrel" is an unmodified 55gallon drum, you need to make some
>modifications. the barrel needs holes in it to admit combustion air. we
>use a standard barrel, with the addition of a grate on the bottom (to keep
>the trash off of the bottom of the barrel) and a surplus squirrel-cage
>blower to force air into the bottom of the barrel. this provides a very
>hot, very fast, very clean burn. glass and aluminum items melt to slag
>that ends up at the bottom of the barrel, and iron cans get the tin
>coating burned off, so they will rust away rapidly if buried.
>the high temps tend to destroy the drum rather rapidly. the barrel will
>glow visibly when in use with a blower.
>we use a trash compactor, and burn trash for our family of 4 about once a
>month. it takes about two hours to burn a month's worth of trash...
wow :-) this sounds very nice. i pay about $23/month for trash removal,
which consists of removing the mostly burnable trash from a squarish
plastic container that holds about 50 gallons, less than once a month.
the trash people also pick up recyclables weekly, and that only costs
about $3/month, so it would pay me to burn trash. my neighbor burns trash
and sheepskins in an outdoor chicken wire enclosure. (he usually does this
on calm cloudy days, which really stinks up the neighborhood.) it would be
nice to get some useful heat out of the trash too, if possible. telephone
books and newspaper and junk mail and slick catalogs don't burn very well
in my woodstove, but this forced draft with a grate sounds better.
some friends of mine burn trash in what they call a "crematorium" built
into a hill in back of their house. it's made with stacked up cement
block, with a grill at the bottom made from rebar. the rebar has to be
replaced from time to time. (they were standing at the counter of a
building supply store a while ago, and judy mentioned to ron that they
needed some more rebar for the crematorium, which brought some odd looks
from the others at the counter.)
i'm imagining that this thing would work better if it were taller, so
the "chimney" had more draft. i wonder how it would work with several
55 gallon drums stacked up or welded or bolted together vertically to
make something 12 or 15' tall. maybe the natural draft in that case would
work as well as the blower. the rebar might be slid through holes near
the bottom of the lower drum, with handles to wiggle it, and the drum
might have some holes below that big enough to clean out the ashes, and
the drum above that might have a door cut out of it, swinging inwards,
hinged at the top, to throw in the trash...
but it still sounds like the lower drum would burn out once a year...
lining it with concrete would help... with some copper pipes buried in
the concrete to make hot water, with a thermosyphoning loop to an insulated
tank above it, a gravity feed hot water system, kept filled by a float valve,
inside the house, say above the kitchen? it wouldn't be very efficient, and
there wouldn't be that much trash, maybe 5 pounds a day, at most. occasional
space heating might be a simpler and better use for the heat...
this might work better with an arrangement of concrete blocks at the base,
then some drums above that, welded or bolted into a chimney, or corbeled
blocks to make a tall narrow conical tower with lots of thermal mass and
surface area, with a serpentine smoke path, surrounded by insulation, eg
bags of leaves, like an outdoor russian fireplace near a house wall. the
summer kitchen in my 1820 stone house used to have an outdoor bread oven
built into the north wall. the lower blocks might stay warm by conduction,
and house air might circulate through the vertically lined-up holes in
the blocks.
nick
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