High quality compressed air has become an essential tool to the modern manufacturer or process plant. The vast array of air-powered torque-drivers, pneumatic grippers, air presses, and impact wrenches demand low humidity air for optimum reliability and service life. A broad range of air drying solutions are available to deliver dew point control and prevent condensation from degrading the performance of air devices located downstream.
Of common air dryers for sale today, desiccant air dryers provide the lowest dew points, down to -40°C. Desiccant dryers function by flowing air through a highly porous and hygroscopic material, such as alumina, which draws and traps vapor from the gas stream using adsorption. Typically two air dryers are used in combination, allowing one dryer to regenerate via hot exhaust gas, while the other actively removes moisture. Electronic controllers switch between the two dryers on a fixed cycle, dependent upon the desired dew point, pressure, and flow of the compressed gas.
Refrigeration dryers provide control over humidity through the use of one or more refrigeration cycles. Vapors condense on the cooled lines of the heat exchanger, and drain into a collection vessel that can be emptied manually or automatically. While implementing a refrigerated dryer carries a greater up-front cost, a well-designed system will dry air more efficiently leading to lower utility costs in larger scale operations. This type of air conditioned dryer cannot obtain as low a dew point as a desiccant dryer, but performs sufficiently for most manufacturing facilities.
More specialized dryers exist for certain unique applications. One example is the deliquescent dryer, which is actually a type of desiccant dryer, although not typically termed as such. The deliquescent dryer uses an absorbent desiccant, which must be replaced once saturated. The primary benefit of this type of dryer is its simplicity as a passive system, and thus no electrical power is required to run it.
When selecting an air drying solution it is important to design specifically for the compressed air application as well as any foreseeable future expansions of the system. Understanding of the dew point, pressure, and flow demands, will aid in the selection of the most financially effective long term solution for today’s high performing manufacturer.