[Stoves] Making testing equipment for CO and O2

[frank]

Paul and other testers,

Paul S. Anderson wrote:

>Thanks to all who provided info.
>
>Now, what is the next step to get the needed measurement methods into 
>the hands
>of stove developers?  (Retorical question that I now struggle to answer.)
>
>1.  I am willing to leave out for the time being the measurement of PM.  Least
>expensive was $2000 mentioned by Dean.
>  
>
1) Using a suction from a vacuum pump with a filter in line may be a 
better way to determine weight carbon per volume emissions released from 
a run(?). A photo of the dirty filter could be taken and the glass fiber 
paper analyzed for carbon to make a 'color' chart as a comparison.
2) We have made nepholometers for water. I am thinking a suction of 
emissions through a clear glass tube ~1" dia.  A narrow light  beam 
shines into the tube and a photocell measuring reflected light at 90 
degrees of the light beam. The glass tube and light beam and photocell 
in a black box. light beam and photocell isolated via black tube pointed 
into the glass tube to prevent outside reflected light from interfering. 
This would be 'on time' measurements of soot and the filter paper will 
be weight of carbon lost as particles.


>2.  Penn Taylor led us to TPI where several units are available:
>At $800 USD is the TPI 712, which will get you the same info [as in the 
>US$1600
>unit the Bacharach PCA (Portable Combustion Analyzer) that he also mentioned]
>(as well as temperature and differential pressure). See
>http://www.tequipment.net/TPI712.asp     looks good, but $800 still 
>seems high,
>but maybe within reach of some.
>  
>
Problem is they do not mention what the detector is.

>3.  All seem to agree that measuring CO is easy enough and really 
>essential, but
>the question is still how to do it the least expensive way, such as a unit to
>only measure CO.  More thoughts on this please.
>  
>
As I mentioned before, I purchased a methane and CO detector and when I 
placed them in line with a pump circulating gas through both in a loop I 
found both had readings for methane and both had readings for CO. 
Looking into it more I found H2 will also give readings for both the 
other gases. I think they will work fine if we agree there will be no 
methane and H2  in the emissions and we can call all the reading CO.  
Can we do that? Crispin, you mentioned  you knew of a  stack that had a 
lot of H2 release and I am now wondering what was the detector used?  If 
the CO is measured using IR detection that might be more specific.

>4.  Crispin enlightened about measuring 02 directly and then calculating CO2
>indirectly, but Tami countered about measuring CO2 directly and calculating O2
>indirectly.  Both have good points.  Tami wrote:
>********
>I'm much more in favor of measuring CO2 because (1) it can be directly
>traced to the fuel and (2) if you have a lot of excess air/dilution, as you
>do above a non-chimney stove, the O2 quickly approaches atmospheric content
>and the calculation of excess air becomes very sensitive to small
>differences. The calculation of excess air is fairly robust if you are
>measuring 5% or 10% O2, but not very robust at all if you measure 19% O2.
>That's why we like to measure CO2 directly, and then the CO/CO2 ratio is
>better known. We get our CO2 sensors
>(infrared) from Telaire and they do take some wiring and calibration.
>These inexpensive CO2 sensors have been available only in the last ~5 years,
>and they are slowly making their way into combustion analyzers.
>O2 is still far more prevalent, but again, I think it is much less
>appropriate to stove applications.
>**********
>So, Tami and all, how do we handle those Telaire CO2 sensors including the
>wiring and calibration?  Sounds like a nice project with possible small profit
>(or heaps of praise from all of us) for someone in the professions or
>universities.  (Hint, Hint!!  do I need to name you??  I have at least five
>people/institutions in mind.  Please respond.)  Or just keep helping us build
>toward a solution.
>
>  
>
With experience measuring respiration rates of plants and organic 
materials using both O2 and CO2 I agree with Tami on this one. There is 
a lot of O2 and trying to determine a reduction is much less accurate 
than measuring the increase in CO2 produced. Also O2 senors are short 
lived compared to CO2 detectors. It would seem that while having air 
with 20% O2 blowing into a pipe via fan it would be easy to calibrate a 
CO2 detector using a CO2 tank and having a known flow of CO2 go in line 
of a known flow of air. But having a flow of air (20% O2) how would one 
reduce the O2 in the air to calibrate an O2 meter? I am talking about 
more than a one point calibration. curve. Using CO2 We could also do 
some standard addition calibration while the stove is running by adding 
a known amount of CO2 with the dilution gas.



>5.  Along with CO measurements, there is even reason to have BOTH CO2 and O2
>direct measurements (with interesting comparison of how well the indirect
>calculations of CO2 and O2 match with the direct measurements).
>
>6.  I (and probably others) need very specific help with this.  What do 
>I insert
>into the stream of flue gases in order to get some number that converts to CO
>numbers, and similar action to get O2, and similar action to get CO2?  Price
>tag for each separately?  Or some shared pieces of equipment like the 
>probe? Or even eventually get 2 or 3 measurements together.  NOT 
>required to give
>continual readings.  Just get meaningful readings when conducted with proper
>techniques.
>
>7.  Still no progress on having some institution (or person) acquire 
>measurement
>equipment and then RENT it or SPONSOR it (like giving a grant) to let 
>the stove
>developers have use at their local place of work for a couple of weeks.
>
>  
>
Before the purchase of any equipment it is -very- important to know 
exactly what the detector is. I would not use any equipment that used a 
'black box' without a full description of what is inside of it. .
I have already made that mistake with the purchase of the methane and CO 
detectors.

>I have not yet decided how much I will pay, but I am getting ready if enough
>guidance comes forth.
>
>Paul
>  
>

-- 
Frank Shields
Soil Control Lab
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Watsonville, CA  95076
(831) 724-5422 tel
(831) 724-3188 fax
frank at compostlab.com
www.compostlab.com