[Stoves] Oxygen Sensors for all combustion...

[frank]

Dear Tom and stovers,

This info is very interesting and the more tools we have that cost less 
and that everyone can use is what we need.

It is good to know that it has its own heat source as I thought they 
relied on the heat from the motor. What I am now wondering is how 
selective for O2 is the meter? If I purged N pass the sensor and 
injected varying amounts of O2 what is the sensitivity? And then if i 
run methane pass the sensor will the injected O2 values be the same? And 
will tarry and miscellaneous organic compounds effect the reading?
Perhaps it -needs- an organic compound as something to burn to give a 
reading?

Perhaps it just me but I have a lot of trouble taking number from a 
sensor without knowing just what it is reading and that it is calibrated 
with every run. It may not be as important if the results are used to 
make adjustments to a stove but, I think, very important when used to 
compare one stove over another or in publish data on a group of stoves. 
It must be a fair playing field  if the data is being used to select one 
stove over another and the data obtained must be the same from lab to 
lab and country to country and be data we can trust. 

I still like the idea of a low flow of gases pass the sensors recording 
the values as they pass and collecting all the gases in a tedlar bag. 
Then determine exactly how much O2, CO2 and CO that is collected in the 
bag based on volume collected and injecting sample and standards in a 
flow pass the sensors. I think Dean was also thinking along these lines 
with his 'trash bag' idea (?).  Also; I still like the idea of an 
after-burner to combust all the unburned compounds and then measuring 
the CO2. Frans (of the famous Frans and Martin team) has given me some 
ideas on building one and I am expecting to get one from  
http://www.farnam-custom.com for me to try when I get some time.

It can take a lot of time and personal expense for these type of 
projects and any assistance like sharing the info on the O2 meter is 
much appreciated.

Thanks
Frank









Thomas Reed wrote:

>Dear Paul and Aul:
>
>We buy "4 wire" oxygen sensors at any automotive store for about $50 
>(typically Bosch).  (They may be only three wires with the ground as the 
>fourth.) 
>
>Two of the wires are the sensor to be hooked to a sensitive millivolt 
>meter.  The other two go directly to the battery and heat the sensor to 
>operating temperature. 
>
>The oxygen sensor easily senses rich (>250 mv) vs lean (250 mv) and it's 
>a very steep "S" curve at the stoichiometric combustion point.  It is 
>usually used as an "on/off" device - too rich and you increase air - too 
>lean and you decrease it.    However, if the temperature is well 
>controlled the voltage between 500 and 1500 tells you "how rich" - 
>slightly (500) to full of tarry compounds (>1000).
>
>Onward, 
>
>TOM REED             BEF
>
>-------- Original Message --------
>Subject: 	Re: [Gasification] Oxygen sensors
>Date: 	Wed, 7 May 2008 12:02:30 +0200
>From: 	Liran Dor <Liran at eer-israel.co.il>
>Reply-To: 	Discussion of biomass pyrolysis and gasification 
><gasification at listserv.repp.org>
>To: 	Discussion of biomass pyrolysis and gasification 
><gasification at listserv.repp.org>
>
>
>
>Paul,
>You should look at a  company called "Modcon"  although Israeli based they have rep. In
>The states.
>If you wish I can provide a contact
>We work with and are pleased
>
>Liran Dor
>EER 
>
>
>
>
>-----×?×?×?×¢×? ×?ק×?×?×?ת-----
>×?×?ת: "Paul S. Anderson" <psanders at ilstu.edu>
>×?×?: "GASIFICATION - Listserve" <GASIFICATION at listserv.repp.org>
>× ×©×?×?: 07/05/2008 09:35
>× ×?ש×?: [Gasification] Oxygen sensors
>
>Hello,
>
>We at Chip Energy are looking for modestly priced oxygen sensors that can give
>feedback to a PLC for operation of a gasifier.  The sensor would be in the
>chimney.  One recommendation was "big time" at about $3000.  What have the
>Gas-L readers found to be appropriate devices and at what price ranges?
>
>Thanks,
>
>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