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

[psanders at ilstu.edu]

Kevin and all,

Alexis, would you please send us an address for seeing your 2 fuel-chamber
units.  Or send Kevin pictures directly.  You cannot post pictures to the
Stoves listserve (only if you are a subscriber and the photo file size is very
small.  But you can send photos and reportss to Tom Miles at   
tmiles at trmiles.com    and he can post them to the website.)

Yes, all T-LUDs that I know of are batch feed, but they can provide continual
heat when allowance is made for easy change over between two fuel 
chambers. One chamber is not sufficient because the container needs to 
be cleaned out and
cooled off to avoid combustion at the lower levels.

What Kevin discusses about an up-draft gasifier that is lit at the bottom does
refer to the normal operation of a "standard" or "traditional" updraft
gasifier.  Those are all ignited at the bottom.  And let's call them standard
updraft gasifiers.  [After all, we do NOT call a standard downdraft gasifier a
"BLDD", nor call it an ITLUD = Inverted Top-Lit UpDraft, or IIDD = Inverted
Inverted Downdraft.]

My comment about a specifically-pyrolytic B-LUD unit refers to a special case
that is not intended to be initially nor eventually operated as a standard
up-draft gasifier.

The name T-LUD refers to a specifically-pyrolytic gasifier of distinct
characteristics, and in that context, a B-LUD (bottom-lit updraft)
specifically-pyrolytic gasifier is not able to function in a uniform 
manner for
the reasons I wrote in my previous message, namely inconsistant production of
combustible gases.

Paul

Quoting Kevin Chisholm <kchisholm at ca.inter.net>:

> 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
>>
>
>



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