[Gasification] thermoacoutics, rijke tubes, sondhauss tubes, pulse jets-- how do we make them not work?

sabbadess at aol.com sabbadess at aol.com
Mon May 16 04:32:19 CDT 2011


Jim,

Why did you stick with 5" tube"?  I would try using a 6" or 8" chimney and just set the swirl burner under or slightly in it.  The swirl burner will act as a heat source to provide natural convection like a wood stove if you just want to get the smoke away from the operator.  

Once you try to fire a boiler/heat exchanger with the flare you are looking at a different animal.  I bet the multiple narrow firetubes will move any resonance out of of your operating range.

Stephen
-----Original Message-----
From: jim mason <jim at allpowerlabs.org>
To: Discussion of biomass pyrolysis and gasification <gasification at lists.bioenergylists.org>
Sent: Mon, May 16, 2011 1:51 am
Subject: Re: [Gasification] thermoacoutics, rijke tubes, sondhauss tubes, pulse jets-- how do we make them not work?



> we're having lots of problems with thermoacoustics now that we've put
 a tall stack on our gasifier swirl burner.  we're using a tall stack
 now to keep startup gasses away from the operator.  the swirl burner
 is 5" in diameter, 10" tall. we've added a 4 foot or so stack of the
 same 5" diameter. it looks like this
 http://www.gekgasifier.com/forums/showthread.php?t=501 (though this
 one without the joint at 10")

ompleting the circle on this question from a few months ago, here's
hat we finally found solved the problem- insulation.  we found that
f we simply insulated the stack from bottom to top, eliminating the
ot/cold delta, the thermoacoustic effect went away.   more reading in
he rilke / sondhaus tube effect clarified that it needs this temp
ifferential, and if you eliminate the temp differential, the effect
tops (which it did).
this was one of the many good suggestions offered here.  we didn't try
ll of them.  but some of note.
1.  cut a V in the top of the stack like done to quiet some pulse jets
.  drill holes towards the top, or other shapes to soften the
ransition at the end to reduce the pulse wave
.  put a floating "deresonator" plate in the tube
.  angle the tube, or otherwise put angle plates in it to break up
he standing wave.
.  drill a hole in the side down low and put a rod across the flame path.
.  experiment with expansion chambers like a two stroke exhaust,
xcept with the intent of "detuning".

i don't know which of the suggested will work.  we ultimately decided
he easiest one was the insulation and tried that.  it worked, so we
topped there for now.
as usual, thank you for the input.
and btw, what problem of physics do gasifiers not touch?
j
_______________________________________________
asification mailing list
to Send a Message to the list, use the email address
asification at bioenergylists.org
to UNSUBSCRIBE or Change your List Settings use the web page
ttp://lists.bioenergylists.org/mailman/listinfo/gasification_lists.bioenergylists.org
for more Gasifiers,  News and Information see our web site:
ttp://gasifiers.bioenergylists.org/

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.bioenergylists.org/pipermail/gasification_lists.bioenergylists.org/attachments/20110516/90f3f1ad/attachment.html>


More information about the Gasification mailing list