Drying Compressed Air in a Tough Environment. A Rail yard Desiccant Dryer Installation.

A few years back, I traveled to Lynchburg, VA, with our Virginia distributor PBE.  We went to Buncher Rail Car (BRC), now known as Appalachian Rail Car, to inspect a couple of recent installations of Van Air single tower deliquescent dryers.

Appalachian Rail Car is a rail car repair facility.  They are akin to an automotive body shop repair facility for train/rail cars.  Appalachian uses steel shot abrasives to blast the rail cars prior to painting.  One of the key contaminants in compressed air is water, and when you mix water with steel shot abrasives, you get “rust.”  Water in compressed air will also have an adverse effect on the quality of the paint finish on the rail cars.

The rail yard environment is dirty; hot in the summer; cold in the winter.  They needed dryers rugged enough to handle the environment and still deliver dry clean compressed air.

Refrigerated dryers are not big fans of hot and dirty environments, and they only produce a 35F dew point.  This would present issues in the winter when ambient temperatures in Virginia dip well below 35F.  A regenerative dryer would be overkill for this application because the customer does not require a -40F dew point during the spring, summer, & fall seasons.

So, what was the best solution?  Van Air Systems and PBE met with Appalachian to discuss our single tower deliquescent dryers as an option.  The single tower dryer, or “deli” as we like to call it, is immune to dust, dirt, heat, & cold.  We suggested they install the aftercoolers, filters, & dryers outdoors to take advantage of the cooler temperatures vs. installing them in a hot compressor room.  The deli will reduce the dew point 20F below the entering compressed air temperature.  The outlet dew point from the deli dryer is self-compensating.  For instance, in the winter, when the ambient temperature is say, 35F, the discharge compressed air temperature from the aftercooler is 45F.   This 45F air then enters the deli dryer, where the dew point is reduced by 20 degrees.   The net effect is the outlet dew point from the dryer at this set of conditions is 25F.  The dryer outlet dew point is 10F below the ambient temperature, which eliminates the potential for any more water condensing in the piping or, in this case, “freezing.”  In the warmer months, the same performance scenario holds true.

Appalachian personnel liked the idea of the deli dryer because there are no moving parts on the dryer.  No electricity is required for the installation and operation of the dryer. The only maintenance required is periodically adding Dry-O-Lite desiccant and draining the condensate from the dryer.  They also liked the added energy savings of a 1 psi or less pressure drop thru the dryer.  When you are sandblasting, every psi that can be saved is literally money in the bank.

After completing a survey of Appalachian’s (2) compressor stations and piping layouts, we proposed D-54 and D-42 dryers to handle all their compressed air-drying requirements for the facility.  The dryers have been installed for a few years now and are solid performers.

When you talk with your customers about their compressed air drying needs, it always pays to take a hard look at the “deli” dryer.  The deli works extremely well in applications such as sawmills, ready mix & bulk cement plants, asphalt plants, portable and stationary sandblasting operations, and of course, rail car facilities.  No environment is too tough for the Deli!!