[Stoves] Understanding TLUDs, MPF and more. (was Re: Bangladesh TLUD )
Frank Shields
franke at cruzio.com
Thu Dec 14 13:52:37 CST 2017
Dear Crispin,
The TGA contains small buckets of biomass, purged with nitrogen and
heated to a temperature at a specified temperature and rate of increase.
The weight loss is plotted. How does it report "is a large spike in heat
released at 360 C." ? When I get a run-a-way temperature i still get a
very good char in the pipe, just not at the temperature I want.
I care not to re-visit spontaneous combustion but perhaps that the
reaction you refer to. That would include outside oxygen.
Regards
Frank
On 12/14/17 11:18 AM, Crispin Pemberton-Pigott wrote:
>
> Dear Frank
>
> The charts provided to the thermogrametric analyser results show that
> the partial decomposition of the biomass is exothermic, and that there
> is a large spike in heat released at 360 C. Some of the gas production
> (distillation) you are witnessing is driven by that heat. If it cools
> rapidly, that heat is lost and there is no more fuel to convert. Above
> that temperature the gas production is driven by external heat.
>
> So the answer is part and part, if the biomass is not well insulated.
> Given enough insulation, the biomass not only self-pyrolyses, it can
> experience thermal runaway as the heat released is more than the heat
> needed to pyrolyse the next fuel particle.
>
> Regards
> Crispin
>
> *From:*Stoves [mailto:stoves-bounces at lists.bioenergylists.org] *On
> Behalf Of *Andrew Heggie
> *Sent:* 14-Dec-17 22:29
> *To:* Discussion of biomass cooking stoves
> <stoves at lists.bioenergylists.org>
> *Subject:* Re: [Stoves] Understanding TLUDs, MPF and more. (was Re:
> Bangladesh TLUD )
>
> On 13 December 2017 at 05:43, Frank Shields <franke at cruzio.com
> <mailto:franke at cruzio.com>> wrote:
>
> This is an interesting topic and one i have wondered about. When
> packing hard a pipe with biomass then flushing with N2 then
> placing in an oven to heat from the outside to a temperature to
> 550c a lot of gases come out the small hole at the end. That will
> ignite if the door is opened and O2 contact. I have wondered if
> any heat is being produced in the pipe itself? or all from
> external heat? If there is it can't be much because the
> temperature advances at a continuous rate. Should you see the
> temperature jump well above 550c its because air leaked in to the
> furnace and there is a flame.
>
> Frank it is interesting what you seem to be showing when opening the
> door is that the pyrolysis offgas coming out of the hole is above its
> auotignition point. What would be relevant to the current discussion is :
>
> 1 the temperature variation inside the tube
>
> 2 the varying analysis of the composition of offgas as the tube heats up.
>
> Andrew
>
>
>
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--
Frank Shields
444 Main Street Apt. 4205
Watsonville, CA 95076
(831) 246-0417 cell
franke at cruzio.com
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