21
APP-001f
SEPT 2016
About half the energy to concentrate the water comes from
the two electric heaters, and the other half comes from
the foul gas that continues to flow through the purger. For
positive suction pressures, the ammonia/water solution is
heated to 185°F (85°C). This corresponds to a concentration
of about 10% to 20% ammonia and about 80% to 90%
water. In a vacuum, water boils at lower temperatures,
so the set point to which the ammonia/water solution is
heated is reduced to an appropriately lower temperature
depending on the suction pressure as detected by the low
side pressure transducer.
The AUTO-PURGER Plus will prepare the concentrated
water for draining, but the computer software will not
allow draining until an operator presses a button to
permit draining. When the purger finishes heating the
water and the water has been concentrated, the suction
line solenoid valve (E) shuts. The Touchscreen indicates
READY TO DRAIN. OPEN WATER PURGE SHUT-OFF
VALVE THEN PRESS “OK” BUTTON. The system remains
in this condition until an operator opens the water purge
line shut-off valve and presses the OK button on the
Touchscreen, see Page 16.
After the operator opens the water purge line shut-off valve
and presses the OK button, the water purge line solenoid
valve (G) energizes to drain the concentrated water. The
Touchscreen Display indicates DRAINING WATER. If the
pressure in the evaporator chamber is less than 10 psig
(0.7 bar) as detected by the low side pressure transducer,
the low-side pressure assist solenoid valve (F) modulates
to maintain 10 psig (0.7 bar) in the evaporator chamber.
The concentrated water continues to drain until the level
reaches the low-liquid level sensor. After the liquid level
passes this sensor, the water purge line solenoid valve
(G) remains energized for an additional 10 seconds, and
then shuts.
After the water is drained, the low-side pressure-assist
solenoid valve F closes, the suction line solenoid valve
E opens, and the Touchscreen indicates, DRAINING IS
COMPLETE. CLOSE WATER PURGE SHUT-OFF VALVE
THEN PRESS “OK” BUTTON.
After the operator closes the water purge line shut-off
valve and presses the OK button, the AUTO-PURGER
Plus goes back to 3333 EVAP TEMP>40F (4C) cooling
down mode, then the 10 minute STARTUP DELAY mode,
and then COLLECTING AIR AND WATER mode. If no air
or water is present, there are no releases to atmosphere.
SECTION 4 AUTO-PURGER PLUS OPERATION
REMOTE RELAY
The remote relay should be connected to a signaling device
or to the plant monitoring and alarm system to notify plant
personnel when the purger requires service or the purger
is ready to drain water.
The remote relay is a dry contact that is normally open during
non-signaling conditions. The remote relay can switch up
to 1A @ 240VAC.
Conditions that trigger the remote relay:
1. ERROR 2222
2. ERROR 3333
3. ERROR 4444
4. ERROR 7777
5. HEATER FAULT or SERVICE REQUIRED
6. READY TO DRAIN
7. DRAINING COMPLETE
Refer to Figure 7 for wiring details
TYPICAL REMOTE RELAY WIRING
Figure 7
CUSTOMER SUPPLIED
AUTO-PURGER CONTROL CABINET
