C02 Removal from Bio gas stream

[gas1]

hi fellow process designers

i am interested to remove bulk CO2 from a biogas stream, to upgrade the gas to fuel quality.the flow rate desired for the 2 biogas upgraders is 50 and 150 scfm, there is a multistage high pressure compressor available that can deliver pressure to the process gas separation-treatment method, at any pressure from 1 atmosphere to 3500 psig,
the gas has this composition, all based on volume.
CO2 is 35%
Nitrogen is 2%,
Oxygen is 1.5 %
Water content, saterated at atmospheric pressure/and 100'F
H2S up to 1000 ppm, (can be removed before C02 removal (iron sponge?))
Methane - remaining volume.

i am aware that molecular gate (Guild) offers a solution though their system is upscale in terms of economics, vs the flow rate of gas to be treated
the desired CO2 content of less than 2 percent is preferred,

what alternative technologies are available, cost effective, other than engineered mole sieves and-or membrane technologies,
can anyone can put a dollar value per 50 scfm or issue an estimate what such a system would cost, ?

thank you

Gordon Brand

http://www.OffenbarEnergy.com

NGV Solutions, sweet gas drying

 

[MortenA]

You could try to talk to tehse guys:

http://terracastus.com/Terracastus_Technologies.html

I have reviewed a basic design for this company and think it will fly.

Best regards

Morten

 

[dcasto]

methanol or propylene carbonate

You could use off the shelf amine like mea too.

you must define fuel quality. burners can be adjusted or designed to handle the 40% inerts. Gas turbines can burn the gas as is as long as the H2S is removed. A reciprocating engine can be set up for as low as 600 BTU/CF.

 

[MortenA]

usually amines are cost prohibitive in landfill gas applications. Also tehre are usually other contaminants - the Terracastus application works as a "co2 washer" where the various pollutants are removed along with the co2

Best regards

Morten

 

[mjpdas]

There is a company in NZ, Flotech.com experienced in biogas purification and compression. They offer both standard products and engineered solutions.

Regards M Pearce

 

[cheute79]

This is a bit of a different approach, but your CO2 concentration is in the same ballpark as off-gas from a brewery or ethanol plant. They use a scrubber to remove and collect (and sell, if there is enough local demand by the soda pop industry) the CO2. The concentration is then low enough that use of MEA might be economical.

The H2S and any SOx will be more of an issue to get to "pipeline quality" than CO2. An iron sponge will get you a good deal there, but usually pipeline requirements are 2-6 ppm, maximum.