HDK-MT350_EN_06
15
Function
The dryer dries the compressed air supplied by the compressor and makes it
available for industrial use.
The installed prefilter and after-filter clean the compressed air supplied to the
dryer and the compressed air from the dryer to the consumers.
The two vessels contain extremely porous desiccants by means of which
humidity is removed from the compressed air and stored just as in a sponge. The
stored moisture is further removed from the desiccants and then fed into the
environment.
To this end, the two vessels alternate between different operating modes. Whilst
in one vessel, compressed air is de-humidified (adsorption), in the other vessel
the humid desiccant is prepared for another charge (regeneration). These two
states, which run in parallel during compressed air preparation, are described
below.
Adsorption
The moist and unfiltered compressed air delivered by a compressor is initially fed
to the prefilter (coalescence filter) where solid and liquid particles are filtered out.
The filtered components are expelled from the system via a condensation drain
valve. The compressed air then flows through the pressurised absorption tower
from the bottom to the top. In so doing, the desiccants dehumidify the air. The
after-filter at the dryer outlet filters any remaining solids from the flow of
compressed air to protect the downstream components. The dry compressed air
is then routed via the piping system to the consumers.
Regeneration (running in parallel to the adsorption)
At the same time the other vessel is prepared for a renewed take-up of humidity.
This process is called regeneration.
The regeneration is subdivided into three phases: expansion, dehumidification,
and pressure build-up. If the dryer is operated in
dewpoint control
mode a further
phase, i.e. standby phase follows regeneration.
Expansion phase
During the expansion phase the pressure in the vessel is released via the muffler
down to ambient pressure within just a few seconds. The outflow of the
compressed air becomes noticeable due to a sudden powerful flow noise at the
muffler.
Dehumidification phase
Prior to being released into the pipe network, dried compressed air is bled by
means of an orifice plate. This separate regeneration air flow is fed through the
depressurised vessel.
The humidity stored in the desiccant is taken up by the air flow and expelled into
atmosphere via the muffler.
