KIMA00H1 (0204)
7
1.5
Capacity
Control
System
The capacity control system consists of an inlet capacity control valve
with an integral bleed-off valve, a 3-way solenoid valve, and a shuttle
valve. Opening (loaded) and closing (unloaded) of the inlet valve is
controlled by the solenoid valve which is controlled by the PLC (ref.
Section 5.2). The PLC monitors compressor operating conditions and
system air pressure to determine when loaded or unloaded operation
is required.
1.5.1
Unloaded,
Off
(Figure 6)
When the compressor is off, the spring in the capacity control valve
holds the inlet valve (1) closed and the bleed-off valve (2) open. The
solenoid valve (4) is deenergized. When the compressor is started
pressures at the 1st stage inlet (B) and interstage (F) are both
negative, keeping the capacity control valve in the unloaded position.
1.5.2
Loaded,
Running
(Figure 7)
The compressor remains unloaded until the main drive motor reaches
full speed, and lube oil pressure reaches 10 psig. After the
compressor reaches full speed and oil pressure is established, the
solenoid valve (4) is energized, the capacity control valve operating
chamber (C) is disconnected from 1st stage inlet vacuum and is
vented to atmosphere (A) through the shuttle valve (3). Vacuum on
the spring side of the operating chamber piston helps pull the inlet
valve (1) open and closes the bleed-off valve (2). The inlet valve (1) is
a butterfly valve which rotates and is operated by a slider on the
capacity control valve shaft.
Air is now drawn into the compressor stages through the inlet air filter,
compressed, and discharged through the check valve to the air piping
system. As air is compressed interstage pressure (F) increases,
transferring the shuttle valve (3) and pressurizing the operating
chamber (C), keeping the capacity control valve open.
1.5.3
Unloaded,
Running
(Figure 8)
System pressure is monitored by a pressure sensor on the discharge
air piping. When the discharge pressure reaches the upper limit of the
desired operating range, the solenoid valve is de-energized, de-
pressurizing the operating chamber (C). The spring closes the inlet
valve (1) and opens the bleed-off valve (2).
When unloaded a very slight amount of air is drawn through the inlet
valve (1) to cool the compressor during unloaded operation. 2nd stage
discharge air (G) is vented (D) to atmosphere (E) out of the bleed-off
silencer. The check valve prevents system air pressure from
pressurizing the compressor.
1.6
Monitoring
The compressor assembly is equipped with the following monitoring
devices:
and Limiting
Devices
(Figures 9-11)
a. Interstage air pressure transmitter. Monitors air pressure at the
intercooler outlet. The pressure is shown on the GT Terminal
(figure 10). Indicates condition of the intercooler and the
compressor stages.
b. Outlet air pressure transmitter. Monitors air pressure at the
aftercooler outlet connection to plant air system. Pressure is
shown on the GT Terminal (figure 10). Indicates condition of the
aftercooler and the compressor stages.
Содержание KNW Series
Страница 4: ...KIMA00H1 0204 FIGURE 1 KOBELCO KNW SERIES MODEL A00 AIR COMPRESSOR ...
Страница 47: ...KIMA00H1 0204 43 Appendix A Daily Operating Record ...
Страница 49: ...KIMA00H1 0204 45 Appendix B Unit Dimensions Minimum Working Clearances TOP VIEW FRONT VIEW ...
Страница 50: ...KIMA00H1 0204 46 Appendix B cont Unit Dimensions and Field Connections SIDE VIEW REAR VIEW ...
Страница 51: ...KIMA00H1 0204 47 Appendix B cont Unit Dimensions Field Connections and Mounting ...
Страница 52: ...KIMA00H1 0204 48 ...
