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

Crispin Pemberton-Pigott crispinpigott at outlook.com
Thu Dec 14 13:18:22 CST 2017


Dear Andrew

I read your message carefully. I believe this is the most important point:

>> Your mention of the superficial velocity brings to mind the note from Tom Reed that the batch loaded TLUD gasifier was a particular implementation of a gasifier, in which, with no other change at all, the device could be made to gasify all the fuel from the top down (superficial velocity higher than 1.0) or to make char (superficial velocity lower than 1.0). This is a significant point.

>Yes it is, but not relevant to this discussion, He also suggested the char layer would need to be 20 particle diameters deep in order for the char to be oxidised to CO, and that the reaction took place from 1100C down to about 800C, the zone we are discussing is narrower and a lower temperature.  

I believe this is the most relevant point. If I construct a fan-assisted stove that can either create char if there is a market for it, or by turning up the fan consume the fuel as it is gasified - something many people on this list could do in a few minutes - then this device does not have two different names depending on the fan speed.

Paul proposes that a T-LUD (pronounced that way) is only applicable to the stove when the fan speed is below a certain threshold. You have proposed that on this discussion list such a limitation on the term has been accepted and that this convention requires that when the fan speed is increased above that threshold, the stove should not bear that name, even though it is operating in exactly the same top-lit updraft manner. 

My position is that TLUD is an ignition point and air supply direction. There are other well known ignition and air flow directions with corresponding abbreviations. As a TLUD Pyrolytic Gasifier is a class of TLUD it needs an additional descriptor if one want to attach an attribute beyond the ignition point and air flow direction. Because ignition points and air flow directions cannot have the attribute 'pyrolysis', using TLUD to include a type of combustion is a synecdoche - ascribing to it an attribute it cannot have. 

I believe Prof Lloyd may be able to assist with this. He led the group creating the list of definitions in WG1.

Regards
Crispin





More information about the Stoves mailing list