[Stoves] Gas analysis. was Re: More on flaming pyrolysis

[frank]

Bruno,
Thanks again.
I have a GC available and now I find out it is fitted with an FID 
detector. All the people that knew about the ~15 GC and GC-MS were laid 
off when that div was closed about a year ago. We kept one. For me to 
use it I would need to purchase another TCD detector, columns, tanks etc 
from my own pocket. Then learn how to use it. All in my spare time - if 
you get the picture. Not likely to happen very soon! I will keep your 
info on file should I win the lottery.

Thanks
Frank

Bruno M. wrote:

>At 20:34 3/06/2007, Frank wrote:
>
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>>>>   Tom Reed wished for a gas 
>>>>        
>>>>
>>analyzer.  Maybe 8-10 years ago I reported on this
>>    
>>
>>>>list (I think) on tests I had made with some borrowed (from the University
>>>>of Denver) expensive hydrocarbon gas monitoring apparatus.  The (well
>>>>described by others) 1) very low carbon dioxide, 2) lots of CO and 3) zero
>>>>oxygen above the pyrolysis front (but still in the charcoal and below the
>>>>secondary air port) were easy to see.
>>>>        
>>>>
>>I am wondering how hydrogen is measured? I noticed the GC-TCD  only goes down
>>to about 4% (on a good day) and wonder if that is low enough for our purposes?
>>And are there other ways more in the 'wet chemistry' style that can be used?
>>For example water coming from the stack collected in moisture traps and
>>subtracted from the fuel moisture?
>>
>>And does anyone know what column type and temperature setting are best for
>>this purpose? I can find out but thought if someone is using one their
>>experience would be helpful. I have available an old HP-GC I might be able to
>>set up for testing purposes. Its been about 30 years since the last time I
>>packed columns and used one -and things have changed.
>>
>>Thanks
>>Frank
>>www.compostlab.com              www.greenrooflab.com
>>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>    
>>
>
>Hi Frank,
>
>I'm no stoves specialist,
>besides being a mastercomposter in my spare time, I do quality control
>in different labs at a big Chem company for a living.
>So i use GC's alot, and I believe next numbers could be useful to you:
>
>For analyses in the ppm range there are other 
>methods, this will do for 0.1% to 100% v/v range.
>A standard FID detector can't do it, and standard 
>H2 gas as a carrier is also useless.
>
>For detection of  H2, O2, N2 and CO, CH4 use external standards ( mixture?),
>argon as carrier gas, 2 detectors in series, 
>first a thermal conductivity detector (TCD) at 170°C
>for the H2, O2, N2 detection; then lead the gas 
>stream trough a Methanizer ( at 370°C)
>and then in to a FID ( at 250°C)  to detect the 
>CO and CH4 ( the methanizer converts CO to CH4 ).
>
>You need the methanizer and the second detector only if you need CH4 and CO
>to measure in smaller concentrations like < 1000 ppm.
>
>Packed column, ss 1/8" 2à3 meter, filled with molecular sieve 5Å, 80 mesh
>
>Samples could be carried from the stoves setup to 
>the GC by means of steel or glass cylinders,
>rubber bladders, or nowadays in mylar foil bags.
>
>Sample holders must have some pressure, if to low,
>blow in some Argon, or heat them in a hot air oven at 60°C.
>inject 1 or 2 ml of the gas sample , starting 
>temp  60°C than up to 150°C if you can program 
>this, and after a couple of minutes again up to 290 °C.
>After analysis you can turn off the TCD, but you 
>may like to keep the oven very hot for a few hours if
>there were higher boiling components in your sample.
>Mind you that CO2 is not measured here but can 
>stick on your column, also to be removed by prolonged heating.
>
>This is not a specific stoves GC analysis but maybe useful.
>
>;-)
>Grts
>Bruno M.
>=====================================================================
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-- 
Frank Shields
Soil Control Lab
42 Hangar way
Watsonville, CA  95076
(831) 724-5422 tel
(831) 724-3188 fax
frank at compostlab.com
www.compostlab.com