[Gasification] Oxygen sensors

Wed May 7 01:50:08 CDT 2008

On Tue, May 6, 2008 at 11:18 PM, Paul S. Anderson <psanders at ilstu.edu>
wrote:
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
--------------------------------------------------------------------------

oxygen sensors are available via the automotive route or the component
sensor manufacturer route.  the automotive ones and the interfaces to them
are well documented via the water injection folks who want to lean out
mixture for fuel economy.  they are in the 30-60 dollar range i believe. i
think there are two types: a 4 wire with integral heater and a 3 wire with
no heater.  they need to be hot to read correctly.

you can also get them from component manufacturers like figaro, city, e2v,
and others.  the interface to a logic chip of some type is various and
documented.  most are around 50 dollars if i remember correctly.

as we discussed before, bear kaufmann at our facility is developing a 6 gas
sensor from commodity components and an arduino interface board.  this will
read h2, co, co2, ch4, o2 and nox.  also included is 4 thermocouple read
circuits and 2 pressure differential input bungs.

below is bear's note from the stoves list summarizing his work to date
(three months ago) and sensor survey.  included is a link to a shared google
spreadsheet where he lists all he had found as of them.  a few more have
surfaced since this was last updated.  bear is still testing and comparing
the various sensors.  there are many issues of cross sensitivity, working
range and dilution needed, moisture sensitvity, etc that need to be
coordinated for a meaningful sensor set.  this project is not yet done, but
likely will be at some point this summer or fall.

automating various gasfiier run parameters via temp and gas sensing can and
should be accessible to the individual scale designer and builder.
automated control long ago left being just an industrial scale concern.  the
parts are there on the shelf to help us get sensing and responsive control
into even small and inexpensive gasifiers.

j

------------------------------

Message: 2
Date: Wed, 06 Feb 2008 18:08:47 -0800
From: Bear Kaufmann <bear at ursine-design.com>
Subject: [Stoves] Gas Sensing
To: stoves at listserv.repp.org
Message-ID: <47AA682F.9080908 at ursine-design.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Hi all,

Jim Mason recently directed me to the discussion of gas sensing
equipment on this list.
I've been working on developing a gas sensing system for our work with
gasifiers.
The goal of the system is to provide real time data about the operation
of the gasifier and to log the data to a computer (from gas sensor
components, differential pressure gauge(s), and thermocouples).
The system consists of an Arduino USB microcontroller board
(http://www.arduino.cc) along with electronics currently on a breadboard
including 16 12-bit analog->digital channels, op-amp circuits, TC chip, etc.
The gas sensing components currently have all come from Figaro and are
of two principal types: the electrolytic cells (Nernst) and
semiconductor/metal oxide resistive types. I've currently interfaced an
O2 and CO2 electrolytic cell (which requires some circuitry as mentioned
before to amplify the very small voltage the cells produce). The
resistive cells measure different gases that can be oxidized, including
CH4, CO, mixed HCs, etc. The CO cell is $14.50, and does have some
cross-sensitivity to methane. I haven't yet worked on calibrating these
to known gas concentrations, which is of course an important next step.
I'm also looking to source IR based sensors and interface them. The
system requires dilution with air since the gas stream concentrations
we'll be sampling are far above the 10,000 ppm limits of most of the
resistive sensors, which is accomplished with a pump and two rotameters.

When searching for sensors to use in the system I developed a
spreadsheet of sources that I could find online.
I've posted the spreadsheet on Google Docs, and it should be accessible
with this link:
http://spreadsheets.google.com/ccc?key=pij8V7pu-JgwtzEMuyk78bg&inv=bear@ursine-design.com&t=4575016692417395121&guest
<
http://spreadsheets.google.com/ccc?key=pij8V7pu-JgwtzEMuyk78bg&inv=bear@ursine-design.com&t=4575016692417395121&guest
>
Feel free to append this with other sources you may know of.
My main focus was on individual components, not on complete
handheld/industrial systems (though the ITX system at the bottom may be
of interest).

Hopefully the above information will be useful to others.
I can post further details of the system at a later date if others are
interested.

Cheers,
Bear Kaufmann

On Tue, May 6, 2008 at 11:18 PM, Paul S. Anderson <psanders at ilstu.edu>
wrote:

> 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
> --
> Paul S. Anderson, Ph.D., Geography professor - Emeritus
> Telephone:  USA-309-452-7072 (residence and office)
> Internet site:  www.ilstu.edu/~psanders <http://www.ilstu.edu/%7Epsanders>
> For my gasifier stoves info, go to:
> http://bioenergylists.org/contributors#Paul_Anderson
>
>
>
>
>
> ----------------------------------------------------------------
> This message was sent using Illinois State University Webmail.
>
>
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>

-- 
--------------------------------------------------------------------------------
jim mason
website: www.whatiamupto.com
current project: gasifier experimenters kit (the GEK):
www.allpowerlabs.org/gasification/gek
announce list: http://lists.spaceship.com/listinfo.cgi/icp-spaceship.com