[Stoves] Understanding TLUDs, MPF and more. (was Re: Bangladesh TLUD )

[Frank Shields]

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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