Nano D1 Series
Modular Desiccant Air Dryers

Principles of operation

Heatless desiccant dryers are the most common due to their simplicity and hence low cost. A heatless twin tower dryer (see figure opposite) operates by removing moisture through adsorption onto a granular desiccant bed from the feed air (typically at 100 psig) as it flows up through a packed bed of desiccant, column A. Column B (having been previously used in drying the inlet air) is at atmospheric pressure and dry purge air from the outlet of column A is fed through a purge valve, expanded to near atmospheric pressure, and flowed in contra flow direction down through column B to effect the regeneration of its granular desiccant bed. When the desiccant in column A becomes saturated with water vapor (usually determined by a simple timer controller) the feed air is switched back to column B, after it has been pressurised, and the cycle continues.

System Performance

These advanced dryers use the pressure swing adsorption principle to efficiently dry compressed air. They use a heatless twin tower configuration housed in a modular design. Each column contains a unique (and patented) desiccant cartridge which incorporates an inlet water separator (D1 only) and outlet filtration. Wet air from the compressor aftercooler enters the dryer and is directed into column A. nano can provide F1 water separators and coalescing prefilters to ensure trouble-free operation for nano D-Series dryers. Bulk liquids (water) and particles are removed by the separator on the inlet of the cartridge. Water is retained within the dryer until the column is regenerated, when it will be vented to atmosphere as it is depressurized. Air passes through the desiccant bed where moisture vapor is adsorbed. Then the dry air passes through a particle filter which retains any desiccant particles (< 1 micron / ISO8573.1 class 2 for dust). Simultaneously, a small amount of dry air is counter-flowed down through cartridge B and exhausted to atmosphere, removing the moisture and regenerating the desiccant. The dryer is controlled by a PLC which periodically switches the solenoid valves, reversing the function of each column and therefore ensuring the continuous supply of dry air.