PAGE 6
PRINTED IN THE U.S.A.
START UP
SECTION 5
5.2 PURGE FLOW ORIFICE
5.3 CONDITIONING THE DESICCANT BED
To condition the desiccant bed, the dryer is operated without any
outlet flow, while the towers regenerate with purge air.
Close the outlet isolation valve and pressurize the system. Energize the
power supply and start the dryer. Observe the dryer for several cycles.
Make sure that it is operating properly.
At initial start up or after extended shutdowns (over one month), the dryer
may take 24 to 48 hours of continuous operation for the bed to be
conditioned. Moisture that has accumulated on the desiccant bed should
be removed before the dryer is placed on stream.
PRINCIPLE OF OPERATION
SECTION 6
DRYER
MODEL
HLS-55
HLS-80
HLS-120
HLS-150
ORIFICE
SIZE
3/32" DIA
7/64" DIA
9/64" DIA
5/32" DIA
6.1 PRINCIPLE OF OPERATION
HLS Series Heatless Regenerative Air Dryers utilize the pressure swing
principle of operation. The desiccant bed in one tower dries the air stream
while the desiccant bed in the other tower is regenerated.
A purge of dry air is used for tower regeneration. It is taken from the outlet
of the dryer. To allow the correct amount of dry air to flow into the
regenerating tower, dryers are equipped with a purge metering orifice.
The heat created during adsorption of moisture in the drying tower is
retained in the desiccant bed and increases the moisture removal
capacity of the purge air.
When the dryer is pressurized and the power supply to the dryer is
energized, the dryer will begin operation. To achieve maximum
performance from this dryer, it should be operated continuously.
Operating this dryer for single shift periods may result in varied outlet
dew point performance.
The dryer operation consists of four stages; REPRESSURIZATION,
CHANGEOVER/DEPRESSURIZATION, DRYING and
REGENERATION.
6.1-1 REPRESSURIZATION STAGE
Repessurization occurs in the regenerating tower. Repessurization
must occur before tower changover. This reduces shock to the
desiccant and the possibility of downstream pressure spikes.
The purge valve is closed and the purge air, which was vented to
atomosphere earlier in the cycle, is now used to repressurize the
regenerated tower.
FIGURE 6A PNEUMATIC SCHEMATIC
6.1-2 CHANGEOVER/DEPRESSURIZATION STAGE
Tower changeover occurs after the previous regenerating tower is
pressurized. The controller signals the inlet transfer valve to switch.
The tower that was on line and drying the process air will begin to
depressurize.
FLOW AT
100 PSIG
9.5 SCFM
12.9 SCFM
21.4 SCFM
26.4 SCFM
BLANK
ORIFICE P/N
26-1933
26-1933
26-1933
26-1933
The Purge Orifice is located at the top of the outlet valve. Purge
can be adjusted by taking a blank orifice and drilling a new size
hole.
6.1-3 DRYING AND REGENERATION STAGE
During the drying stage, one tower is pressurized with process air. This
tower is in the drying stage. The process air passes through the
desiccant bed, which adsorbs moisture from the air.
5.1 START UP
WARNING
BEFORE STARTING THIS DRYER, FOLLOW THE INSTALLATION
INSTRUCTIONS AND PROCEDURES COMPLETELY. SERIOUS
PERSONAL INJURY CAN RESULT IF INSTRUCTIONS ARE NOT
CAREFULLY AND COMPLETELY FOLLOWED.
DO NOT REMOVE, REPAIR, OR REPLACE ANY ITEM ON THIS
DRYER WHILE IT IS UNDER PRESSURE.
If the dryer is being started up for the first time or after the
desiccant has been changed, the purge muffler must be removed.
Operate the dryer until no desiccant dust is visible at the purge
valve. Then the muffler can be reinstalled.
If bypass piping was installed on this dryer as outlined in SECTION
4.2, close the inlet and outlet isolation valves. Open the bypass valve.
Pressurize the air system. Once the air system is pressurized, slowly
open the inlet isolation valve. Check timing settings in control box.
The dryer should be factory set as shown in Figure 4B.
Energize the power supply to the dryer. Both towers will pressurize.
Several seconds later one tower will depressurize. Open the outlet
isolation valve.
The regeneration stage of one tower occurs at the same time as the
drying stage in the opposite tower. During the regeneration stage, a
percentage of dry air is directed through the desiccant bed of the
offstream tower. The purge air is vented through the purge valve to the
atmosphere.
IMPORTANT
TO START THE DRYER YOU MUST PRESS THE RUN SWITCH
WHICH WILL LIGHT THE RUN LED.
