Dear Crispin and all,
I never liked trusting a reading on an instrument that is not calibrated before each use and for the situation applied (when possible). You have the readings, air flow reading and dilution to get the rate Hydrogen is coming off in instrument range. If you set the probe in a constant location, set the dilution then add hydrogen into the air stream from a gas tank at a known rate typical of what is seen. You can calibrate the instrument for the situation. Make adjustments to the airflow (using those reading true or not) to plot how linear the curve is. Forget the numbers given on the airflow and H meter. Just use units of measure knowing what the true Hydrogen reading should be because you know the amount released from the tank into the system. This system for all the readings. I realize when biomass gasses are given off there may be interferences and we can't exactly use standard additions (H will explode!) to see how well they work. I think Dean does something like this when setting up his system(?). Frank Frank Shields Control Laboratories; Inc. 42 Hangar Way Watsonville, CA 95076 (831) 724-5422 tel (831) 724-3188 fax [email protected] www.controllabs.com From: Stoves [mailto:[email protected]] On Behalf Of Crispin Pemberton-Pigott Sent: Wednesday, September 11, 2013 5:17 AM To: 'Discussion of biomass cooking stoves' Subject: Re: [Stoves] Hydrogen from charcoal Dear Andrew Hydrogen is highly reactive in gaseous form and influences many electrochemical cells. It is detected electrically, usually in the CO cell. I agree with Harold that we should rule out some sort of instrument error, but then the CO level is compensated for the H2 meaning they both should be working if the H2 is. It remains an interesting problem. Re the town gas, a major step in the production was to spray the hot coal with water to fracture it creating CO and H2 in the process (water gas) and when I first heard that I was amazed. What crazy guy thought of that?? J Crispin >Charcoal stove, was operating, but "everything was cooled"??? Meaning >that there was no "serious" (as in glowing red) char in the stove, but >emissions were still coming off, correct? If this was the case then I would expect the char would still be undergoing pyrolysis and the higher tar molecules splitting. As you all know town gas was originally made by heating coal to drive off CO and H2. That these molecules would survive the combustion is interesting but could simply be the dilution by other combustion products putting the air:fuel ratio out of range. How does a hydrogen cell sense the presence of hydrogen i.e. what mechanism is involved in the measuring instrument? AJH
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