Removing Moisture from Biogas Pipelines

Using moisture trap or moisture absorbing materials you can reduce the moisture from gas. Look at things that will not absorb your gas but will absorb only moisture. you can also use gas dryers.

Is the pipeline "empty" (does not contain biogas) when you need to remove moisture? If so, use dry air (less than minus 40 degrees dew point), which you can recycle thru any of a number of moisture removing/dehydrating agents, Dryrite, etc. You may also be able to place a quantity of moisture absorbing agents in the pipeline while it's carrying the biogas, for continuous moisture removal. Go to Google or the Handbook of Chemistry and Physics for a table of drying agents and their efficiency. Dryrite used to publish a booklet listing various drying agents and their efficiency. If necessary, use dry nitrogen to eliminate contamination. Probably not an option, but a third process would be to draw a good vacuum on the pipeline.

On a biogas pipeline this unique filter will work wonders with a spin-on filter head. Here is the first part of the MSDS.

MATERIAL SAFETY DATA SHEET

SECTION I - CHEMICAL PRODUCT AND COMPANY INFORMATION

H2O Control Products Inc.

2204 Algonquin Road, Sudbury, ON P3E 4Z6

PRODUCT TRADE NAME:

H2O CONTROL – Fuel, Hydraulic and Air Filters

CAS NO: Not applicable

SYNONYMS: None.

GENERIC/CHEMICAL NAME: Water & particulate removing filter

PRODUCT TYPE: Spin-on or cartridge type filter

PREPARATION/REVISION DATE: January 8, 2007

________________________________________________________________________

SECTION II - COMPOSITION/INFORMATION ON INGREDIENTS

H2O Control Filters are spin-on and cartridge style. The water absorbing media contained within the filter is one of a number of super absorbent polymers, all of which are listed as non-hazardous and non-toxic.

________________________________________________________________________________________________

SECTION III - PHYSICAL AND CHEMICAL PROPERTIES

STANDARD PSI RATING: UL approved for 150psi when filtering hydraulic/industrial fluid and air.

FUEL PSI RATING: UL approved for maximum of 50psi when filtering petroleum products such as diesel, gasoline, ethanol blends, methanol, etc.

Sounds that you have suggested almost the right solution. What else is needed? Good.

70% relative humidity? It seems like a lot of drying agent consideringthe volume rate you would need to treat. What temperature is the biogas evolving at? Maybe cool the vapor and separate "trap" the liquid moisture off first to remove a portion of the higher humidity content, then use a drying agent to remove a majority of the remain moisture.

Yes, This sounds much better idea. There is high humidity in biogas reactor as it is hot on continuing reaction and tank is full of water and no way for moisture to escape. A cooling trap will sure condense water and most part of the biogas may still remain as gas with some air. Normally biogas burns even with so much water in it but will work better if water is reduced. Let me see the optimum temperature reduction for the biogas reactor gases to get rid of moisture.

It looks to me that biogas reactor works much better in hot condition and optimum pH is 6.8 to 8 or slightly acidic to slightly basic where pH 7 is neutral for water.

Read more here

http://www.mothercow.org/oxen/gobar-gas-methane.html

For reducing the moisture, pipe trap seems to be cost effective solution. Any idea about the shape and size of trap? Even the location of trap seems to be important.