SECTION 6 DHL HEATLESS REGENERATIVE DRYER
25
6.5 CYCLE DESCRIPTION
The desiccant material, if contaminated from
lubricant oil, loses its adsorption propriety. Moreover
during operation, the desiccant can release solid
particles (powders) particularly abrasive and
extremely damaging for the final users.
For this reason the dryer is equipped with two high-
efficiency filters:
• Inlet filter, 0.01 micron filtration grade, with
differential gauge and electronic timed
drain or zero loss drain optional.
• Outlet filter, 1 micron filtration grade, with
differential gauge and manual drain.
During the start-up both regeneration drain solenoid valves PVA and PVB are closed (for about 120 seconds) to
guarantee the complete pressurization of the dryer.
Stage A The solenoid valve PVB is supplied so the tower B is depressurized. Both inlet and outlet
spools of shuttle valves move towards tower B (side without pressure).
The compressed air flow is directed to tower A, where the desiccant material adsorbs the
humidity up to the target Dew Point.
Through the regeneration nozzle a calibrated part of dry air coming out from tower A is
expanded towards tower B. This air (particularly dry for this expansion operation) while cross-
ing tower B, dries the adsorbent material dragging away the humidity through the PVB solenoid
valve and the silencers. At the end of this stage the adsorption material of tower B is com-
pletely regenerated.
Stage B The solenoid valve PVB is closed and then through the regeneration nozzle tower B is pressur-
ized again up to the working pressure. The sum of stages A + B equals a half cycle time.
Stage C The solenoid valve PVA is supplied so tower A is depressurized. Both inlet and outlet spools of
shuttle valves move towards tower A (side without pressure).
The compressed air flow is directed to tower B, where the desiccant material adsorbs the
humidity up to the target DewPoint.
Through the regeneration nozzle a calibrated part of dry air coming out from tower B is
expanded towards tower A. This air (particularly dry for this expansion operation) while cross-
ing tower A, dries the adsorbent material dragging away the humidity through the PVB solenoid
valve and the silencers. At the end of this stage the adsorption material of tower A is completely
regenerated.
Stage D The solenoid valve a PVA is closed and then through the regeneration nozzle tower A is pres-
surized again up to the working pressure. The sum of stages C + D equals a half cycle time. At
the end the cycle starts up’ again from phase A.
NOTE
The cycles are symmetrical therefore A=C
and B=D
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