[Gasification] Reverse purge cycle for a packed reduction bell

[jim mason]

http://www.gekgasifier.com/forums/showthread.php?t=496

here's bear's report on some experiments with a reverse flow purge
cycle to recover from a packed bell condition.  this means running the
downdraft gasifier temporarily as an updraft.  many here have done
this.  many have also done it historically.  nothing terribly new here
other than noting that most of us suffer packed bells at times, and
burning the problem out rather than digging it out is much easier and
much less messy.

we're working on this because our goal is to create an automated
system to do this. somewhat like an auto clean cycle in your oven
after you cook too much pork in it. press and button and the machine
erases your sins and makes ready for a new round.  it can also be used
to make your first charge of charcoal from raw biomass, without having
to prefill with charcoal.

also in this report you will see a hot element lighter. we've been
using some very interesting silicone nitride elements of late. these
are a newer generation of hot elements since the common silicone
carbide ones. the new ones self-regulate without electronics, and will
survive full combustion temps. you just turn them on and leave em. you
can't do this with the other typical options.

we like them very much. they cost about 30-40 each. ouch. but they
eliminate the need for a torch on your flare. flare always lights and
relights by itself, whenever there is combustible gas.

and . . . you can get them in 12vdc. so they work in vehicle and
genset applications.

now of course this might prevent the usual giant cloud of pyrolysis
gas and carbon monoxide collecting around your start up area, along
with the usual nausea that comes with it.  this may be a feature or a
bug, depending on your perspective.

j


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