[Stoves] Hi TLUDers -- and EPA testing questions

[Alex English]

Ron, Crispin,
Many moons ago, when I had access to an IR CO,CO2 monitor, I filtered 
the gasses before the flame on a TLUD. If memory serves me I got 9% CO 
and 15% CO2. But memory sometimes seems to be serving others. If only we 
had access to the old archives, I reported it to this list at the time, 
but alas the 'server' changed. It amazes me that nobody has done this since.
Alex


On 24/10/2011 10:41 PM, Crispin Pemberton-Pigott wrote:
>
> Dear Ron
>
> >>"For those not having experience with TLUDs,  Dean's reference to "no 
> primary air can make it up", means that the oxygen is "entirely" used 
> to produce carbon monoxide."
>
> ...
>
> >>It is really rare to find a normalised CO emissions factor (not 
> concentration in the emerging gases) above 100,000 ppm. I have only 
> see it once and I work with some of the wildest devices the 
> imagination has produced.
>
> >*[RWL:   This part I don't understand.  Neither Dean or I were talking 
> about anything other than primary air. ***
>
> **
>
> *I see that you did not follow. I am sure is it my method of 
> describing it. Here is a short version: You can't get pure CO from 
> biomass pyrolysis for inherent chemical reasons. *
>
> **
>
> *Proof that I offer:  I have measured CO production across a wide 
> range of conditions and it is almost impossible to get more than 10% 
> CO even when it is theoretically possible (from the elemental 
> composition) to get 40%.*
>
> **
>
> >>CO(ppm) * (EA+100%) = CO(EF) at O2=0% (the O2 is factored out).
>
> >*[RWL3:  The subject of excess air for testing the completeness of 
> combustion (after adding secondary air and releasing the majority of 
> the energy) is extraneous to the sentence under discussion.]*
>
> That is how to work out what the CO level is, in ppm. 100,000 ppm is 10%.
>
> >>I mention this to support my conclusion that the O2 tends to create 
> 'fuel moisture' very easily.
>
> **
>
> *>**I have personally measured the gases coming up through the fuel 
> bed in a TLUD (a borrowed high quality tool) and the dominant gas was 
> CO  (many millions of ppm). ***
>
> **
>
> That is impossible. 1 million parts per million is 100% CO.
>
> **
>
> *>>**   RWL4:   My main concern is with Crispin's above next-to-last 
> sentence:  "*/I am expressing doubts that level could be created in a 
> TLUD that was not first run as a regular fire./
>
> *   The word "TLUD" should say to all that the test operation was NOT 
> run as a regular fire.   They are as near to polar opposites as the 
> stove world can get.   So this is to ask Crispin what he is saying 
> here and what part of my response he is objecting to?*
>
> I am offering a method of how to get a CO content as high as 10%. 
> Start a regular fire, get it going well, then enclose it in a vessel 
> while hot and running. This can produce 10% CO, but a TLUD cannot. 
> That is my contention.
>
> Biomass needs just a little more air (Oxygen) to completely use up the 
> H2 and then breathe in whatever additional air would burn all the 
> Carbon. In any real file, some of the C becomes CO and CO2 (surface 
> reactions mentioned by Dr Tom Reed in a previous discussion).
>
> >>*[RWL:  I hope we can get a specific citation for/from Tom here. ***
>
> **
>
> *He addressed it directly previously on two occasions. *
>
> **
>
> *>At the hot surface from which (very complicated and numerous [1000's 
> of species??]) pyrolysis gases are emerging, my understanding of the 
> pyrolysis surface effect literature is that "all" (given control of 
> the incoming oxygen flow) are turned into CO and water. *
>
> **
>
> *My point is that if there is NO air entering, virtually all the O2 in 
> the fuel is turned into water. The great proportion. Some of the H2 is 
> left in the gas but is it hard to find an H2(EF) of 15,000 (1.5%). I 
> have no problem with others contradicting this with real measurements.*
>
> **
>
> *>>The relatively small amount of CO2 that is produced near the 
> surface (not ON) is converted back to CO as it interacts with the hot 
> char above it*
>
> **
>
> *This only happens under certain conditions and not when it is cool. 
> Dr Tom was mentioning C=> CO2 reactions taking place above 400 C on 
> the surface. CO can also be formed, and volatiles (which contain 
> carbon) can break down into CO as well. The CO in the gas is not 
> necessarily produced from CO2 and is unlikely if the temperature is 
> low because it has to absorb a lot of heat to do so (24 MJ/kg).*
>
> **
>
> *>So I repeat - I am mystified by this message and about what is at 
> dispute. *
>
> I am not sure there is a dispute. Perhaps the clarification will suffice.
>
> Regards
>
> Crispin
>
>
>
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