Emerson VSG Manuel D’Utilisation

2 – 1

VSG/VSSG • Installation, Operation and Maintenance Manual •Vilter/Emerson • 35391SSG

Section 2 • Theory of Operation

The gas and oil systems work in unison, but each one
will be explained separately. Reference Figure 3 - Gas
Compressor Unit P&ID for gas and oil fl ow descriptions.

Gas Flow

The gas compression process begins as processed gas
enters the suction inlet (1). The processed gas fl ows
through a stop valve (2), check valve (3) then through
a suction line strainer (4) to the compressor (14). The
processed gas is then pressurized through the compres-
sor and discharged as high pressure gas vapor into the
oil separator (13). In the oil separator, the oil is then
separated from the discharged gas vapor by impinge-
ment separation. The high pressure gas fl ows out to

the aftercooler and scrubber for cooling while the oil is
pumped or syphoned back to the compressor.
Moreover, check valves (3) and (6) are provided between
the oil separator to prevent gas vapor or liquid from fl ow-
ing back to the compressor during shutdown periods.
An equalizing line is also installed between the high
pressure side (oil separator) and low pressure side (suc-
tion) to allow .

Oil Life and Oil Flow

The life of the oil is directly affected by the quality of the
gas. Proper separation of any liquids must be accom-
plished to prevent droplets of liquid at the compressor

OIL SEPARATOR

OPTIONAL DUAL OIL FILTERS

STANDARD SINGLE

OIL FILTER

COMPRESSOR

FILTER

DRAIN

BLEED

FILTER

BLEED

DRAIN

BLEED

SUCTION GAS

1/4” OIL CHARGING

1/4”

100#

DISCHARGE
STOP VALVE

MOTOR

BLEED

MOTOR

PUMP

CHECK
VALVE

OPTIONAL REMOTE AIR COOLED OIL COOLER

STANDARD WATER COOLED OIL COOLER

OIL COOLER

DRAIN

VENT

OIL
DRAIN

Figure 2-1. Gas Compressor Unit P&ID