SECTION 6 DHL HEATLESS REGENERATIVE DRYER
35
6.10.2 DPD
The DPD cycle (DewPoint Demand) is used to adapt
the cycle times, that is the quantity of air needed for
the regeneration, to the real load applied to the dryer.
It is necessary to install a DewPoint meter (PDP
Meter - optional) to achieve this. Set the DIP D3 on
ON and the DIP D7 on ON. The DPD mode can be
selected only for DewPoints of -20°C and -40°C (set
the requested condition on DIP D1 and DIP D2).
After the first four operating cycles following machine
start-up, run in FIX mode, the SHDC-2100 device
starts operating in DPD mode according to the
following diagram:
While tower A is operating, tower B is regenerated
for the set time C (fixed), determined by the selected
operating cycle (see Table 6-2). At the end of the
regeneration phase, tower B is re-pressurized and
kept in stand-by until the DewPoint meter (PDP
Meter) indicates that the nominal value has been
reached in the tower (SPC) and activates the SHDC-
2100 device for the switching of the towers. The
process is repeated in the same way when tower B is
operating.
A = Regeneration time of tower A (fixed)
B = Re-pressurization time/stand-by tower A (variable)
C = Regeneration time of tower B (fixed)
D = Re-pressurization time/stand-by tower B (variable)
SPC = Switching Set-Point (-20°C or -40°C)
A = C
B1canbedifferentfrom D1
A+B1+C+D1=Completecycle
Figure 6-7: DewPoint Demand Cycle Timing Sequence Diagram
Table 6-2: Programmed Values
Low Pressure High Pressure
-20°C/-
4°F
-40°C/-
40°F
-20°C/-
4°F
-40°C/-
40°F
Time A = C [s]
355 240 270 180
Minimum value
Time B1 and D1 [s]
95 60 180 120
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