[Gasification] stratified downdraft pressure

[Greg Manning]

Greetings John, and list members.

I'm somewhat confused, the suction fan is ONLY used for startup of a 
gasifier, and can be even at the "low point" of gas production volume (an 
old automotive heating blower or such) the fan is not used during the 
operation of the engine, and is by-passed via valves.

Yes the amount of tar is indicative of gasifier internal temperature 
AND/OR... water content of feedstock AND/OR  hearth to pryolosis zone 
placement ratio.

My suggestions..

Remove everything "Ancillary" to the gasifier itself except the fan and a 
"test flare", install the fan at a distance from the gasifier (10-15 ft) 
(3-5m) as to allow the steel tube to act as a cooler for the hot gas as to 
not melt the fan.  install a "T trap" just ahead of the fan to collect 
condensate and drain it to an appropriate container. NOW, get the gasifier 
working correctly... Then with trial and error, you can one at a time add 
the other stuff back into the system.

See my page on downdraft gasification:
http://www.inetlink.ca/a31ford/cgcmb/

Greg Manning,
Brandon, Manitoba, Canada



----- Original Message ----- 
From: "JOHN GOODWIN" <john.goodwin1 at btconnect.com>
To: <gasification at listserv.repp.org>
Sent: Tuesday, February 06, 2007 6:12 AM
Subject: [Gasification] stratified downdraft pressure


> Dear list,
>
> I have made a stratified downdraft gasifier as described by Dr Reed at 
> http://www.gengas.nu/byggbes/intro.shtml. Using a small blower, it works, 
> and I have large quantities of flammable gas. I unfortunatley also have 
> quantities of tar and steam coming through the filter, using wood chip of 
> about 10% moisture.
>
> Being new to this, please feel free to correct me at any point. Please 
> also excuse my mixing units.
>
> I assume that the tar and steam are present because the temperatures in 
> the reduction tube are too low for the water gas reaction to fully 
> complete, and too low for the tar to crack. From this I assume I need more 
> suction from my fan.
>
> I have used a 10" reduction tube. From table 2.2, 
> http://www.gengas.nu/byggbes/52.shtml this is suited to a 160 cubic inch 
> engine (2.6 litre). At 2000 RPM, a 2.6l engine is drawing 5200 litres per 
> minute. I understand that producer gas and air need mixing at 
> approximatley 50:50, so would be drawing 2600 litres (91 cubic feet) per 
> minute from the gasifier.
>
> So therefore, I am looking for a 100 cubic feet/min suction fan. How many 
> inches water suction does this fan need to generate in order to achieve 
> the neccessary temperatures in the reduction tube? Does anyone have any 
> good sources of cheap fans (UK 240v, 50Hz).
>
> One more beginners question, when using a simple U bend to measure water 
> guage, is the suction the difference between the gasifier side and 
> atmospheric side levels of water, or the difference between the gasifier 
> side and the starting level of water?
>
> Many thanks,
>
> John
>
>
>
>
>
>
>
> _______________________________________________
> Gasification mailing list
> Gasification at listserv.repp.org
> http://listserv.repp.org/mailman/listinfo/gasification_listserv.repp.org
> http://gasifiers.bioenergylists.org
>