Biogas scrubber design - Removal of CO2 and H2S and their treatment

[bakedben]

Hi a am currently supposed to be designing a Gas Scrubber.
The idea is to reclaim Gas from waste water produced by a paper recycling plant (for use in the on site gas turbine CHP) whilst at the same time cleaning the water on site to avoid expensive mogden charges etc.
The Biogas is produced from an anerobic digester and a UASB. The biogas produced has been deemed too high in CO2 (~40% CO2) and so must be scrubbed.
In addition there will be H2S and im pretty sure ammonia present. The initial design consisted of a water scrubber for CO2 removal and an air stripper to clean the H2O. I must then deal with the contaminants present in the air which I believe to be H2S, CO2 and Ammonia.

The biogas stream to be scrubbed flows at a rate of ~50kg/hr according to information given to me.

I dont really know where to start and any information would be greatly appreciated. In additon I am certain the air used to strip the CO2 and H2S from the water cannot be simply allowed into the atmosphere untreated and so any information on methods of treatment (if neccessary) would also be appreciated.

 

[cckanand]

so how it would be if you goes for small amine treatment unit for stripping those acid gas

 

[dcasto]

by the time you circulate enough water to lower the CO2, most of your methane will end up in the water as will the H2S.

You can use caustic solution to remove the H2S and CO2 or use iron spong or one of its clones like sulfa treat to remove the H2S as a disposible soild. Then use an amine solution to remove the CO2.