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  • Peg Minichiello

Understanding HOC Dryers

Since its inception in the 1960s, Heat of Compression (HOC) desiccant dryers have proven to contain massively successful technology for compressed air drying.

But there are various misconceptions about HOC dryer technology. A lack of basic understanding of how they work and what their uses & capabilities are cements the confusion that surrounds this technology.

Today we’re going to look at what a HOC Dryer is, the different types, how it works and the pros & cons of using them.

What is a HOC Dryer?

HOC dryers are regenerative desiccant dryers that accomplish desiccant regeneration (expelling moisture from desiccant and drying it) by using the heat that’s generated during compression in an oil-free compressor.

Different Types of HOC Dryers

There are two different types of HOC dryers available:

  • Rotating drum

  • Twin tower

How Do HOC Dryers Work?

How HOC dryers work can seem complicated and even confusing at times. This simple 6 step explanation should make it easier to understand:

  • Hot air from compressor(s) enters dryer.

  • Heat energy from the hot air removes moisture from the desiccant being regenerated.

  • Hot air enters heat exchanger and is cooled (causing moisture to condense).

  • Condensate is removed from the air through a moisture separator.

  • Air flows through drying vessel and remaining moisture is adsorbed by the desiccant.

  • Air exits through filter providing high quality compressed air.

Pros & Cons of Using HOC Dryers

As with all products and offerings, there are pros and cons associated with HOC dryers.

Pros of using HOC Dryers

  • Low electrical installation cost.

  • Low power costs.

  • Low energy consumption.

  • Minimum amount of floor space used.

  • No loss of purge air.

Cons of using HOC Dryers

  • Can only be used with oil-free compressors.

  • Applicable only to compressors that have continuously high discharge temperatures.

  • Inconsistent dew points.

  • Booster heater required for low load (heat) conditions.

We Are Here To Help

Do you think a HOC dryer sounds like the ideal solution for you? Or do you still want to explore other options? CDS Systems’ expertise in Clean Dry Air will assure the proper solution for your process. Call us today for more information on all aspects regarding HOC dryers. 925.667.3400/

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