RE: DIG-L: Biogas from Wastewater Treatment Plant

["Holland, Jeremy" <JLHolland@brwncald.com>]

Kevin, Jeff, & List,

Siloxanes are also a significant problem for wastewater treatment plants.
Depending on the concentration in the gas you could ruin a turbine in a
matter of days (turbine blades are sensitive to deposits).  Microturbines
are actually worse due to the fact that they operate at much higher rpms
than bigger turbines.  The solution in all cases is to scrub the gas prior
to combustion.  Cooling the gas to 40 F removes about half of siloxanes
present (which you would want to do anyway to remove moisture from the gas).
Running the gas through a carbon tower will bring the siloxane levels down
to below detection limits.  If you need more info just let me know.

Jeremy
-------------------------------------------------
Jeremy Holland, P.E. 
Brown and Caldwell 
9620 SW Barbur Blvd. Suite 200 
Portland, OR  97219 
Ph: 503-977-6616 
Fx: 503-244-9095 

 

-----Original Message-----
From: Kevin Chisholm [mailto:kchisholm@ca.inter.net]
Sent: Thursday, October 17, 2002 6:21 AM
To: Jeff Forward
Cc: digestion@crest.org
Subject: Re: DIG-L: Biogas from Wastewater Treatment Plant


Dear Jeff

Silohexanes can be a problem with "landfill biogas",
but I do not know if they are a problem with municipal
waste water treatment sludge. At any rate, even if
silohexanes are a constituent from the MWWT gases, it
would be generally better for the environment if they
were put through a turbine..... when they are burned in
this manner, the silohexanes are destrowed and a silica
deposit occurs on the turbine blades.

Kindest regards,

Kevin Chisholm

> Jeff Forward wrote:
> 
> 
> Can anyone tell me what the salient differences are
> between biogas that is produced from a farm based
> digester and gas that is produced from an anaerobic
> digester located at a wastewater treatment plant?
> The plant is located in a town of about 8,000.  It
> already has an anaerobic digester and is considering
> installing a microturbine to run on biogas.  I am
> more familiar with farm based digesters, but I assume
> that a municipal wastewater treatment plant would
> produce a gas with different contaminants.  For
> example, would siloxanes be a problem at a wastewater
> plant where they are not particularly of concern for
> a farm based system?
> 
> Thanks for the help.
> 
> Jeff
> 
> Jeffrey W. Forward
> Richmond Energy Associates
> PO Box 615
> Richmond, VT  05477
> (802) 434-3770
> (802) 434-2344 FAX
> e-mail: forward@gmavt.net

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