[Stoves] Influence of fuel-bed temperatures on CO and condensed matter emissions from packed-bed residential coal combustion

Crispin Pemberton-Pigott crispinpigott at outlook.com
Sun Sep 20 09:34:43 CDT 2015


Dear Paul

 

>Please confirm:   Something like a bucket with holes in the bottom.   

 

Yes.

 

No upper extension.   

 

Added during ignition. Removed once coked. Behaviour varies.

 

No attempt to have a TLUD-type concentrator or directed horizontal entrance of the secondary air.   

 

That is not special to TLUD’s. Upper holes serve as horizontal air entrances.

 

Just light one at the bottom (bottom burning only - BB) and the other at the top (meaning that the pyrolytic front will be moving downward through the stack of fuel, as migratory pyrolytic front MPF until it reaches the bottom.)   



The two approaches are used. Top lit is advertised as ‘improved’ but it goes back a long way. The top lit version does not mean an MPF. You can only really get an MPF if it is a packed bed gasifier and virtually no one is doing that.


2.  So the fuel-bed temperatures were always measured in the bottom of the BB unit, but were measured at the position of the MPF as the MPF progressed downward.   Right?   If not, please describe.



Don’t know.


3.  How did the experimenters control (make hotter or less hot) the fuel bed temperatures?   

 

Don’t know. I don’t think they did.

 

4.  How deep is the pile of coal fuel?

 

Typical is < 150mm.

5.  Please describe the "secondary" burning.   Flames flickering on the top?   tall, short, etc.



Tall in the beginning and short after pyrolysis.


6.  And which way (BB or MPF)  is the common practice in South Africa?



Bottom lit updraft (BLUD) is common, and TLUD is also common. MPF is not going to be seen, not a real one. That would require complete air control and there is no attempt to do that in an mbaula.

 

Regards

Crispin

 

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