A few years back our distributor, PBE INC. of Richmond, Virginia asked me to accompany them to survey a landfill site in northern Virginia that was having issues with freezing gas lines.

The gas produced by this landfill is used to fire gas heaters that supply heat for the large county maintenance garages.  The problem they experienced was moisture freezing in the gas supply lines in the colder winter months and blocking gas flow to the heaters.

What was the Application?

200 SCFM Landfill Gas at 5 PSIG with 165°F inlet conditions

This site was using an air-cooled aftercooler followed by a refrigerated dryer.  The problem arose in the cold winter months because the refrigerated dryer only produces a 35°F dew point.  The ambient temperatures in winter can get down to the 20’s or lower in northern Virginia, and the piping that transports the gas between buildings is outdoors.  When frigid winter temperatures arrive, the refrigerated dryer could not get the dew point of the gas low enough to prevent freezing.  You need to dry the gas at least 10°F below the lowest ambient temperature to guard against freezing.

Van Air Systems Solution:

Install a Van Air D-36 Deliquescent Desiccant Compressed Air Dryer with 10BF desiccant for the cold winter months. This dryer is installed directly after the refrigerated dryer.  The D-36 produces a -5°F dew point with our 10BF desiccant. The customer took our recommendations and it solved the problem, no more freezing gas lines.  They still had issues with the refrigerated dryer though because when it broke down, typically in the hot summer months, they had to rely solely on the D-36 dryer, and it consumed more desiccant when the refrigerated dryer was not working.

They said the Deliquescent Dryer handled the refrigerated dryer breakdown situation but the customer wanted a reliable year-round solution that was simple and cost effective.  We recommended eliminating or by-passing the refrigerated dryer and then install an additional D-36 Deliquescent Desiccant dryer with Dry-O-Lite desiccant upstream of the D-36 with 10BF desiccant.  This second dryer would cut the consumption of the 10BF desiccant by 50% and eliminate the electric utility cost associated with refrigerated dryer.  The customer agreed with our solution.  They used the refrigerated dryer as a backup, but it never had to come online. Van Air Systems Single Tower Deliquescent Dryers have no moving parts, require no electricity, therefore, they never broke down.

These dryers have been in successful operation for several years.  We were awarded another project with this customer for a larger landfill gas application that required (2) D-54 Deliquescent Desiccant dryers in series.

If you or your customer has a similar issue with freeze-ups in the cold winter months, a Single Tower Deliquescent Dryer just may be the solution. Contact us at 1-800-840-9906 and we can do a full air system evaluation of your application.

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