[Stoves] [Gasification] Heating/thermal usage - Chinaworkshopnotes

[Kevin Chisholm]

Dear Paul
----- Original Message ----- 
From: "Paul S. Anderson" <psanders at ilstu.edu>
To: <english at kingston.net>
Cc: "Kevin Chisholm" <kchisholm at ca.inter.net>; <stoves at listserv.repp.org>
Sent: Monday, August 07, 2006 11:28 AM
Subject: Re: [Stoves] [Gasification] Heating/thermal usage - 
Chinaworkshopnotes


> Kevin and all,
>
> Alexis Belonio uses the 2 fuel-chamber approach very well.

I went to: 
http://www.repp.org/discussiongroups/resources/stoves/approtech/Two_Burner_Rice_Husk_Gas_Stove1.pdf
and he has what appears to be a single chamber updraft gasifier fueled with 
rice husks, and feeding two burners. This must be a simple updraft gasifier, 
and not a T-LUD, in that he is producing a fuel gas for use in a remote 
burner.

I went to: 
http://www.repp.org/discussiongroups/resources/stoves/approtech/Single%20BurnerRiceHuskStove.pdf
Here, he has what appears to be a single burner T-LUD cooker, capabable of 
40 to 50 minutes of cooking on one charge of rice husk fuel.

I could not find a URL leading to a description of his replaceable fuel 
canister system; would you have an appropriate URL?
>
> Personally, I like to have two fuel canisters that can be switched in and 
> out
> for sequentially continuing heat without continuous feed of fuel.  But 
> this
> applies only to the small small units where the canisters are small enough 
> to
> be manually exchanged.
>
Would not this inherently mean "batch operation"?

> Finally, the best reply about continuous-feed of a T-LUD could be to have 
> some
> other type of gasifier that is continuously operated.

That was my impression also.

  I showed such a
> prototype at the ETHOS 2006 meeting, and I will be bringing an improved 
> unit to
> Stove Camp.

Do you have a URL that would show a sketch of these systems, and a 
description of operation, for the benefit of those of us unfortulate to be 
unable to attend stove camps?

  It is a "traditional" updraft gasifier (with both pyrolyic
> gasificaton and carbon gasification) with the fire at the bottom and fuel
> coming in at the top.  It is NOT a pyrolytic gasifier, so I refrain from
> calling it a B-LUD, or even worse, a BLUD gasifier.
>
Once a bottom lit updraft gasifier is operating, it would appear to me that 
there is pyrolysis at play. Certainly, with a deep fuel bed, there would be 
distillation as a result of residual heat from the combustion at lower 
levels, but I don't think that distillation would take off all the 
volatiles. In a charcoal retort, with only external heating, there is 
distillation at the start of the process, but continued heating results in 
pyrolysis.

>By the way, a "B-LUD" pyrolytic gasifier does not work.  When the fire is 
>lit at the bottom of a full pile of fuel, the heat generated does not drive 
>off the
>combustible gases (via flaming pyrolysis or retort action) UNTIL AFTER the
>moisture of the fuel pile has been evaporated.  That means that the quality 
>of
>the gases would be mainly water vapor at the beginning and then make a 
>shift to the combustible gases, resulting in an inconsistant supply of 
>usable gases for
>the fire.  I learned this from Alexis Belonio during the China workshop. 
>Once stated, it >seems to be self-evident (unless one forgets about the 
>moisture in fuels).
>
I can see that you would get that problem if the fuel bed depth was too 
great, or if the moisture content of the fuel was too great for the design 
of the system. At any rate, if the system was operated within the range for 
which it was designed, there could be low quality fuel gas at start-up, but 
once the system was stabilized, then with continuous feed, there should be a 
gas output of continuous quality. Certainly, cooling of fuel gas from a 
bottom lit updraft gasifier would be beneficial, to knock out much of the 
water, and some of the tars.

> I will still be making a third report from the China workshop about 
> gasification
> technologies seen and not seen.

We look forward with great interest to your report. Thanks very much for 
your time and effort.

Best wishes,

Kevin
>