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

[Crispin Pemberton-Pigott]

Dear Alex

>I enjoy the technical discussion and thought experiments but do we really still lack the data (Numbers) to support your positions?

I have tried to provide the two typical product ranges without trying to describe a particular implementation. I will respond to Paul’s comments on that basis. I feel for this list, it is important to set out the general principles and following agreement (if we can agree) then look at particular implementations.

>A Paul brand TLUD, (as opposed to Crispin 's generic tluds) can have easily controlled particle size and moisture, superficial velocity and stack excess air.

I think that is true, but care should be taken when describing that happens in a “Paul TLUD” as generic for all gasifiers. Obviously there are many ways to process the fuel. I think the flaked fuel mentioned by Tom is a good ‘generic’ point to start. It is as if the fuel was powder, and reacts ideally. When there are particles 1 inch in diameter, the behaviour is obviously going to change because the pyrolysis of the whole particle takes time. By the time it is done the outside is probably oxidising. We had to face challenges in the Central Java testing concerning remaining char. What to count and not count? Some stove producers claimed their stoves could use the char produced in the next fire, which according to the ‘rules’ meant it was not wasted. Testing the next burn showed indeed they can, gasifying the char, or at least some of it, while making new char. To be fair to all participants, there have to be rules for the performance evaluation.

>When it is connected to a pipe (as a gasifier) it can support a premixed flame with various measurable flame speeds. Surely there is a someone in 2018 who could insert a gas analyser (CO2, O2, CO, H2, CH4) into stream and correlate correlate correlate.

That is what Riaz Achmad is doing. He is trying to get a clear picture – as clear as possible – of what the products are when the fuel is being burned, and looking at when what portion of the fuel has just been ‘processed’. It is not too difficult to get a snapshot of the gases using a gas bad and putting the sample into a gas chromatograph. It is much more challenging to get real time measurements because of the condensation of volatiles and water. It is actually easier to measure things after the gas has been burned but not nearly as informative.

>Then it can compared to other systems and fitted to the process narratives that are so skillfully articulated.

If you consider stumbling around ‘skilful’. At least if we are stumbling, we are on the move. You can’t turn a ship around if it isn’t moving.

Regards
Crispin in really blizzardy conditions
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