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 Section 4. ROTARY LIQUID PISTON COMPRESSORS
1 DESCRIPTION. Rotary liquid piston compressors (figures 2-10 and 2-11)
utilize a liquid (water or other low viscosity liquid) as the compressant.
The unit consists of a round multiblade rotor that rotates in an elliptical
casing partially filled with liquid. The liquid is carried around by the
rotor and follows the contour of the casing. The rotor buckets are filled
with air, through the intake port, by the suction created when the liquid is
forced to recede from the rotor buckets at the wide point of the elliptical
casing. As the liquid reaches the narrow point of the ellipse, it reenters
the buckets, compresses the air, and passes it out through the discharge
ports. The cycle is repeated twice for each revolution of the rotor. Liquid
is supplied continuously to the compressor to take up the heat of
compression. Excess water is discharged from the compressor with the air and
is removed by a separator connected to the compressor discharge. Operating
and maintenance instructions for electric motor drives are contained in NAVFAC
MO-205, Central Heating and Steam Electric Generating Plants.
2 STARTUP.
2.1 Prestart Inspection. Carefully inspect the installation to ensure the
following prestart requirements are fulfilled.
(a) All installation and repair work has been completed.
(b) Installation has been cleaned and tested for leaks.
(c) Alignment has been checked.
(d) Safety valve has been tested for proper operation.
(e) Compressor is properly lubricated.
2.2 Startup. Proceed as follows:
(a) Open compressor discharge valves.
(b) Turn on compressor sealing-water.
(c) Start the compressor.
3 NORMAL OPERATION. While the system is operating, perform the following
tasks.
(a) Maintain correct sealing-water flow rate.
(b) Check air discharge pressures.
(c) Watch for irregular performance of the compressor.
4 SHUTDOWN. When removing the compressor from service for an extended
period, thoroughly drain the casing of all sealing-water. Run a flushing oil
through the compressor to prevent rusting and corrosion. Repack grease
lubricated bearings with new grease and fill oil lubricated bearings with
2-23
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