[Digestion] Biogas concentration sensors - technical question

Tue May 29 03:26:45 CDT 2007

I have been using a Crowcon triple plus + IR gas sensor that will measure up to 4 gases. I don't think they do CO2, at least not at the concentration expected in AD but they can measure H2S up to about 200ppm I think. I was only interested in the methane part, and as standard it comes with a 0-100% LEL IR sensor, but can be bought with a dual range IR that will also measure 0-100% volume. It is of course designed for safety around landfill sites, so I advise the purchase of  the hand operated bulb which will allow you to channel gas from a digester across the sensors rather than constructing a channel from plastic as I did. The H2S sensor would be catalytic but I have no real pressure in my biogas: a couple of PSI is a lot when you ask to have a large tank manufactured. I just vent off the gas through the sensor for a minute or two, then flush it out with air. I think the dual range unit alone (with charger) would be less than 2000 euros.

Alastair Ward

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From: digestion-bounces at listserv.repp.org on behalf of Terrence Sauvé
Sent: Mon 28/05/2007 19:59
To: digestion at listserv.repp.org
Subject: [Digestion] Biogas concentration sensors - technical question

Hi all AD enthousiasts,
I am currently preparing for my thesis on AD and co-digestion for medium size dairy farms in Ontario, Canada.
I am having difficulty finding a "decently" priced biogas sensor to measure in-line concentrations of methane, carbon dioxyde and hydrogen sulfide for both lab-scale and full scale applications.
There is a few companies in Germany that offer that service but for around 7'500 to 10'000 euros price range.
Considering that we also have to run VFA's, based on those prices, we might as well buy ourselves a GC and a bunch of columns with it.
We were also falsly recommended by a company to purchase a hand-held portable gas detector, commonly used in the natural gas security industry. However, these sensors are catalytic and only works at normal atmospheric pressure...

I would like to receive your feedback on this issue and if you have any technical experience with brand-name IR adsorption of "in-line" gas meters.
Thanks all.

Terrence

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