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3.5 Operation flows
3.5.1 Air flow system
Description
Air drawn through the air intake filters (AF
C
), and
unloader (UA) into LP compressor element (CE
LP
) is
compressed and discharged to the LP intercooler
(IC
LP
) where the heat of first-stage compression is
removed by the cooling air flow.
The cooled air then enters MP compressor element
(CE
MP
) where it is further compressed and
discharged through MP intercooler (IC
MP
) to HP
compressor element (CE
HP
). The compressed air is
then led via check valve (CV), aftercooler 1 (AC
1
),
aftercooler 2 (AC
2
) and water separator (WS) to air
outlet valves (AOV).
During loaded operation air inlet throttle valve (TV)
is open and unloading valve (UV) closed. These
valves are simultaneously closed and opened
respectively by loading solenoid valve (LSV) through
unloader piston (UP) when the working pressure
reaches its preset maximum. The pressure of the HP
compressor element is then released to the
atmosphere through the unloading valve and the
blow-off silencers (BOS), resulting in closing of the
check valve. The throttle valve leaves an air passage
in the closed position. Thus air remains drawn into the
compressor to maintain a reasonable pressure ratio
over the elements.
An air-operated balancing piston is fitted behind the
male rotor rear thrust bearing of MP and HP
compressor element. The piston decreases the load on
the male rotor front thrust bearing during loaded
operation. During loading the MP and HP compressor
element balancing piston is actuated by working
pressure, while during unloading the pressure on the
piston equals the atmospheric pressure.
The bypass valve (BV), which is connected between
the inlet and outlet pipes of the HP compressor
element, serves to safeguard the element in case the
HP outlet pressure falls below the HP intercooler
pressure. This happens when the air consumption
exceeds the capacity of the compressor, or when the
compressor is started with the air outlet valve(s) fully
or partial open.
Intercooler pressure sensors, a discharge pressure
sensor, temperature sensors, two intercooler relief
valves (RV), an electric blow-off valve (BOV), a MP
safety valve (SV
MP
) and a HP safety valve (SV
HP
) are
comprised in the system.
Temperature shutdowns (outlet compressor elements)
will occur if max. air temperature limit is reached.
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