Thanks again. This has saved me a lot of trial and error.
It sounds like I should try using plenty of air to minimize CO content,
preheated for secondary combustion, and a cyclonic separator for the
ash, probably with another filter as well, perhaps electrostatic? Air
lubricated bearings seem wise as well. The impeller case should open
with the feed door, swinging a rotary wire brush into contact with the
turbo, angled to both clean and turn it slowly. The magnet needs a
strong enclosure to handle the centrifugal force, and careful balancing.
As usual with gasifiers, price does not go down well for a
small-capacity rig, so solar may have this beat for home use now. Maybe
I've just dreamed up a good way to get forced draft on a condensing
stove using low-tech impellers. I hope someone will find this inspiring
for a larger scale unit.
Bob
On 17-01-03 12:06 PM, Doug wrote:
Hi Bob,
Coking is caused by the reversion of CO gas back to CO2 and carbon
soot, where-by the hot gas entering the turbo is over a temperature of
say 500C. If you were to first combust this gas with air so that only
CO2 hot gas drove the turbo, the problem then becomes one of ash
particle impaction onto the impeller blades. Naturally you get heaps
of waste heat, but the practicalities of cleaning the impeller daily
or after each refueling is a real party pooper! The only safe way is
to use ceramic filter candles, expensive and needing compressed air to
pulse clean.
Not sure maths is all that's required to make your idea work in the
way you perceive without adding energy. Steam and coke need the high
temperatures and pressures associated with turbo operation, but in
differing design application. I'm sure others will offer you comment
to develop this interesting concept.
Doug Williams.
On 03/01/17 12:56, Bob Stuart wrote:
Thanks, Doug.
I'd been worried about coking, so you have saved me a test setback.
Will a cyclonic separator upstream help? I've never dealt with
coking, so I don't even understand its vulnerabilities. Would a good
wire brushing with each new load of fuel do the trick? That could be
automated pretty easily.
All the ICEs have to deal with the power for a compression stroke.
I'll do the math on intake vs exhaust volume before building, of
course, to make sure the turbo efficiency is a minor fraction of the
equations. With a built-in air pump, a condensing flue is easy to
arrange, and it recaptures any heat used to burn wet wood. Would the
steam help clean coke? It eats carbon in an ICE.
From what I know about generators, a rapidly spinning magnet is quite
effective. Those little DC-DC voltage converters are surprisingly
small and efficient, running at very high frequencies.
Bob
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