ADSORBENT DESICCANTS: Know what you are purchasing!

Photo of the 15,000 scfm Heat of Compression Dryer.

Recently a Van Air Systems distributor called me about a competitor’s Heated Regenerative Dryer.  This particular dryer was a 15,000 SCFM Heat of Compression dryer.  The customer was having dew point performance issues.  Heated type dryers need to have their desiccant changed out more frequently because of the effects of hydrothermal aging.  Hydrothermal aging is caused by the numerous heating and cooling cycles the desiccant inside the dryer is exposed to.  This reduces the capacity of the desiccant to adsorb moisture and causes poor dew point performance.

Our distributor asked me if Van Air Systems could supply activated alumina for this type of dryer.  I said yes, of course we can.  I also informed him that there are “cheap” grades of inexpensive alumina being sold online.  The problem with a lot of this desiccant sold online is that it inherently has a lot of dust fines.  These dust fines accomplish nothing except plugging up particulate filters and purge exhaust mufflers.  You purchase desiccant by the pound so you really want the smallest percentage (0.5%) of fines and the largest amount of spherical balls possible. The Van Air Systems spec is for 0.5% fines content maximum. The spherical balls are what adsorbs the moisture out of the compressed air stream, the fines, aka desiccant dust, cannot adsorb any moisture.    

 The dryer I talked with them about will require 8500 lbs. of 3/16” (4-8 mm) activated alumina per vessel or a total of 17,000 lbs.  You can see here that if they were to use a cheap brand of desiccant that had let’s say 3% desiccant fines, they would have 255 lbs. of desiccant fines per vessel to contend with.  If they purchase the desiccant from Van Air Systems, then they will only have 42.5 lbs. of desiccant fines to trap in their particulate filter downstream of the dryer.  What a customer saves on the initial purchase price of the cheaper brand of desiccant will be eaten up from frequently replacing particulate filter elements and purge exhaust muffler cores.  Also, they are actually getting short changed 425 lbs. of the spherical balls because of the excessive amount of desiccant fines in the cheaper brand.

 After explaining all of this to the customer, they decided to purchase Van Air Systems high grade Activated Alumina vs a bargain brand. A friendly reminder to always do the extra research and know what you are purchasing! For more information or questions about desiccant for you dryer contact us at 1-800-840-9906.