[Gasification] GEK air preheating test produces tar free gas

[Ken Boak]

Jim,

How did the weekend in San Mateo go?

Have you any more pictures of the Listeroid 6/1 running dual fuelled on wood 
gas, plus any fuel consumption figures.

Good luck with this line of research,  - as soon as I get back from China, I 
will be "snapping at your heels"

Have you thought of using the hot Lister exhaust to provide some 
air-preheating?

Ken


London.


----- Original Message ----- 
From: "jim mason" <jimmason at whatiamupto.com>
To: "Discussion of biomass pyrolysis and gasification" 
<gasification at listserv.repp.org>; "STOVES at LISTSERV.REPP.ORG" 
<STOVES at listserv.repp.org>
Sent: Tuesday, May 13, 2008 1:00 AM
Subject: [Gasification] GEK air preheating test produces tar free gas


> http://allpowerlabs.org/gasification/gek/reports/reportairpreheating1.html
>
> The pictures at the link above show a new air preheating scenario for
> the GEK nozzle and constriction (Imbert) type downdraft reactor. We
> ran this configuration at the Maker's Faire in San Mateo, CA last
> weekend to drive a Lister 6/1 diesel genset in dual fuel mode. The
> result was a tar free gas over about 10 hours of operation.
>
> This new air preheating system uses heat exchange tubes in the form of
> corregated stainless steel natural gas lines, spiral wrapped around
> the reactor. When the reactor is bolted down into the gas cowling,
> these heat exchange tubes fill the circular volume where the product
> gas rises upwads towards the outlet.
>
> Somewhat to our surprise, this aggressive air preheating system
> resulted in a gas that appeared completely tar free. This is likely
> the result of higher combustion and reduction zone temps and thus
> improved tar consumption and conversion. Condensate too was
> significantly decreased, owing to increased H2O conversion in the
> reduction zone from the higher temps.
>
> In addition to preheating the air, the heat exchange tubes also
> significantly cool the product gas. I was surprised to see gas exiting
> the top of the gas cowling at 150-210F. Yes that is correct, 100C or
> less. Compare with typical no air preheating or gas cooling
> configurations which have gas exit temps in the 200-400C range. Hot
> gas is much more difficult to process downstream than cool gas.
> Cyclones, filters, plumbing and pumps are all complicated by high temp
> gas.
>
> This success of this "gas cooling via air preheating" suggests the
> potential of eliminating the radiator all together. In the next run
> I'm going to double the length of the air preheating lines, put fins
> on the cyclone, increase the size of the granular filter, and see if
> we can do without the radiator (or in other words, incorporate the
> radiator into the gasifier). Efficiency will also continue to increase
> the more we recycle this "waste" heat back into the gasifier.
>
> The internal geometry for this run was the "textbook" dimensions for
> Sweedish inverted V hearth designs for a 2.5" reduction constriction.
> This is a very small constriction, intended for engines around 5-10hp.
> I did not do any special nozzle burn path tests or other diagnostic
> configurations, so i'm sure what I had could be improved upon.
>
> The fuel was walnut shells in 1/4 - 1/2 shell form. Moisture was
> measured at 15%.
>
> More soon.
>
> j
>
>
>
> --------------------------------------------------------------------------------
> jim mason
> website: www.whatiamupto.com
> current project: gasifier experimenters kit (the GEK):
> www.allpowerlabs.org/gasification/gek
> announce list: http://lists.spaceship.com/listinfo.cgi/icp-spaceship.com
>
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