Page 165 - Subyek Teknik Mesin - Forsthoffers Best Practice Handbook for Rotating Machinery by William E Forsthoffer

Compressor Best Practices Be st Practice 3.7

Fig 3.7.23 Slide valve operation
(Courtesy of Kobelco e Kobe Steel Ltd)

evaluated against properly designed oil flooded compressors.
Vendor experience lists should be required and checked.
P 1 ,P 2
T 1
Gas analysis (for each case) Condition monitoring
Gas contaminents
Flow rate Condition monitoring requirements for screw compressors
Off design flow requirements should follow the principle of component condition monitoring.
The following major components should be monitored:
Fig 3.7.24 Required process data - Rotor
- Journal bearing
- Thrust bearing
sour gas (H 2 S) must be accurately defined, since they will de-
termine material types and whether a flooded screw can be - Seals
used. The suggested minimal condition monitoring requirements
are presented in Figure 3.7.25.
Dry or wet screw?
As discussed in this chapter, the technical and cost advantages of
flooded screw compressors have made them the compressor of
choice. However, special modifications may be required for Screw compressor minimum condition monitoring requirements:
them to be used in sour gas service. The low retention time of oil Performance (rotor)
in the separation vessel (60e90 seconds) does not allow sour gas Flow trend
components to be vented from the reservoir oil. This can lead to Efficiency check
oil contamination, screw component damage and the need for Manual vibration readings (accelerometers/velocity)
Thrust bearing temperature measurement (RTDs)
frequent oil changes. Reservoir capacity can be increased, but
at an extra cost. The use of dry screw compressors should
be considered in sour gas service, and this option should be Fig 3.7.25 Minimum condition monitoring required

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