[Stoves] Wood fired, two-stage gasification employed

ajheggie at gmail.com ajheggie at gmail.com
Sat Aug 6 12:09:30 CDT 2011


On Friday 05 August 2011 20:40:56 Crispin Pemberton-Pigott wrote:
> g/kg burned is common with vehicles power stations because the fuel is
> relatively constant. g/kg is not god for stoves because the emissions
> apply only to that fuel (wood?) at that moisture content. Change
> either, and the emission rate per kg is not relevant. For example how
> to you compare the Mayon Turbo stove and a Jiko, the former burning
> rice hulls and the latter pine charcoal briquettes? The obvious thing
> with a cooking stove is that people are going to continue burning until
> the food is cooked. This is an important guide. The absorbed heat (in
> the pot) is the important constant. The emissions per absorbed MJ are
> meaningful across all fuels, moisture contents, stoves and cooks. Once
> the water boils, there is something to compare.

One thing that struck me about this report was the chemical make up pf the 
particulate emissions. Yes the emissions per cooking task is the 
important figure just as emissions per distance travelled is important to 
a vehicle. The report you cited was on measurements for a 150kW 
wood/pellet boiler and the organic carbon content of the particulates was 
8% by mass. The remainder was fly ash and I would guess that the make up 
of natural draught batch ( or serial batch) fed cooksstoves would be 
significantly different. I had this discussion discussion with Tami about  
the possibility fanned stoves would increase the inorganic flyash in the 
particulate make up and these results do seem to point to the agitation 
and turbulence in these forced air, mechanically stoked putting small 
particulates into the flue gases.

My conclusion is that these industrial type woodburners have an even 
better performance in terms of air quality than the bald figures suggest 
because our cookstoves typically have PMs of PICs formed in the secondary 
combustion, with much higher organic carbon, and it is these that are 
implicated in the health problems from indoor air quality.

AJH






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