nano Dryer Technology
Desiccant air dryers are used for high purity
applications where pressure dewpoints of -70,-40 and -20°C are
required according to ISO8573.1 humidity classes 1, 2 and 3 respectively.
Adsorption is a process whereby specific molecules
(the adsorbate) adhere to the surface of a highly solid (the
adsorbent) by electrostatic and molecular forces. The adsorbent
has a specific pore structure which will be a combination of larger
or macro pores, slightly smaller or mesopores, or very small pores
known as micro pores.
The adsorbent is normally made into granules
or beads which are used to form packed beds through which the adsorbate
is passed and the process of adsorption can take place. The rate
of adsorption is affected by several factors which ultimately determine
the adsorption isotherm profile and thus the size of the packed
Principles of Operation
Nano D-Series Ultra High Purity Compressed Air Desiccant Dryers
use the pressure swing adsorption principle to efficiently
dry compressed air. They use a heatless twin tower configuration
(see diagram opposite) housed in a modular design. Each column
contains a unique (and patented) desiccant cartridge which
incorporates inlet and outlet filtration.
Wet air from the compressor after-cooler
enters the dryer and is directed into column A. Bulk liquids
(water) and particles are removed by the filtration/separation
stage, which is located on the inlet to the cartridge. Water
is retained within the dryer until the column is regenerated,
when it will be vented to atmosphere as it is depressurised.
Following the filtration stage, air passes through the desiccant
bed where any remaining moisture is adsorbed. Finally, the
dry air passes through a particle filter, which retains any
remaining desiccant particles that may have been carried through
the system (<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 when the compressor
is running, reversing the function of each column and therefore
ensuring the continuous supply of dry air.