I get asked this question several times a month from customers who are searching for a cost effective solution for eliminating moisture from their compressed air system.
Here is a recent example where I was able to answer: “Yes a Deliquescent Dryer is perfect for the application”.
A long time Van Air distributor called me regarding a problem one of their customers is having at an Asphalt Plant. The customer is using a 400 SCFM/100 HP oil flooded screw compressor to supply compressed air for all the pneumatic cylinders, gates, solenoids, etc. These pneumatic components are not a big fan of wet compressed air. They initially looked at supplying a refrigerated dryer for the application, but the problem here is a majority of the pneumatic lines and components are outdoors. Since this plant is in the Midwest there is a huge issue with freeze ups in the colder months. A refrigerated dryer will only produce a 35°F pressure dew point at best. Once the ambient temperature falls below 35°F the headaches begin…..water condenses…..freeze ups. A refrigerated dryer is not a good fit here.
Next they took a look at a heatless regenerative dryer. The regenerative dryer will protect the plant from freeze up in the colder months because it produces a -40°F pressure dew point. The initial purchase price gave the customer sticker shock, plus there are some other disadvantages to using a regenerative dryer. The heatless regenerative dryer is going to require 72 SCFM for purge air to regenerate the desiccant. The purge air loss left them with 328 SCFM to run the plant. During peak loads they would have to bring another compressor on line to keep up with demand. In addition to the purge loss the regenerative dryer has a pressure drop of 5 psig. Add up the purge loss and the pressure drop it equates to 22HP/16Kw in additional utility costs to operate a heatless regenerative dryer. Plus they would have the added cost of running another compressor. A regenerative dryer is not a good solution here either.
The distributor salesperson asked me if they could use a deliquescent dryer. After some discussion regarding the application, my answer was “YES”!! I quoted them on a D-24 Single Tower Deliquescent Dryer which will be installed outdoors to take advantage of the cooler ambient temperatures. The outlet dew point from a single tower deliquescent dryer is always 20°F below the entering compressed air temperature when using Dry-O-Lite desiccant. For example, if the inlet air temperature to dryer is 80°F the outlet dew point will be 60°F. You can see the huge advantage here in the colder months. If the inlet temperature to the dryer is 30°F the outlet dew point will be 10°F, which assures protection from freeze ups. If the customer requires even better performance they can use our 10BF desiccant in the coldest months. 10BF Desiccant reduces the dew point 65°F below the entering compressed air temperature.
I recommended they install a Van Air Systems F200 Series filter - F200-400-A coarse coalescing pre-filter with auto-drain to remove any condensed water prior to the dryer inlet and a F200-400-B coalescing after-filter to remove any oil. I also quoted them on a MDV-400-I drain valve for automatic draining of the condensate from the D-24 dryer.
Finally, since all of this equipment is going to be installed outdoors in the Midwest, the F200-400 pre-filter bowl and the drain line on the D-24 need to be heat traced.
This customer is now going to have a cost effective solution for eliminating moisture and protecting them from freeze ups. Plus they get the added advantages of no moving parts on the Deliquescent Dryer, very low pressure drop (1 psi or less), zero utility cost, and a 10 year warranty on the dryer.
Have questions about trying to use a Deliquescent dryer for your particular application. Contact Van Air Systems at 1-800-840-9906.
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