Page 392 - Subyek Teknik Mesin - Forsthoffers Best Practice Handbook for Rotating Machinery by William E Forsthoffer

Lube, Seal and Control Oil System Best Practices Be st Practice 7.6

7. Clear filter DP max-kPa (PSI) ______________ 5. System pressure below which accumulator begins to drain kPA
8. Cartridge material ______________ (PSIA) ¼ ________
9. Type end seals ______________ 6. Precharge pressure kPa (PSIA) ¼ ________
10. Cartridge e single or multiple ______________ 7. Proposed accumulator internal volume (approximately 90% of
11. Cartridge center tube material ______________ normal size) ¼ ________
12. DP at max viscosity-kPA (PSI) ______________ 8. Actual fluid capacity per accumulator ¼ ________

13. Collapse pressure-kPA (PSI) ______________ ð6Þ
ð7Þ 1 ¼ ________
14. Number of cartridges ______________ ð5Þ
15. LPM (GPM) per cartridge ______________ 9. Precharge type: manual, self contained, automatic

K. Switches or transmitters
Confirm proper range, type, materials and maximum dead- N. Additional tank sizing and construction confirmation
band (change in actuation point) of each switch. Confirm proper Overhead rundown (lube)
selection of transmitters.
Overhead (seal)
Degassing tank(s)
L. Gauges
These tanks should be checked against specifications data
Confirm proper range, type, material of each pressure, sheets for proper capacity, construction and ancillaries.
differential pressure, temperature and level gauges.

O. Piping, vessel, flange and component material
Confirm that all specified materials are supplied.
M. Accumulator sizing
1. Type: bladder ________ or direct acting ________
2. System flow KPM (GPM) ¼ ________ P. Console and unit connection orientation
3. System transient time (sec.) ¼ ________ Refer to Figure 7.5.10 and finalize all connection locations.
ð2Þ ð3Þ
4. Capacity of fluid required ¼ 60 ¼ ________ liters (gallons)

Best Practice 7.6

Monitor lube/seal oil reservoir level on all refrigeration This is a common problem with plants that have centrifugal com-
applications to ensure that seal oil does not enter the pressors using seal oil systems.
process loop and foul the chillers. It is sometimes possible to correct this problem by modification to
The entrance of oil through the oil seals into refrigeration systems the seal oil system design (see B.P. 7.42).
will reduce the capacity of the system and impact on process unit Contamination of refrigeration systems by centrifugal compressor
revenue. seal oil has been one of the major reasons for the use of dry gas seals
Careful monitoring of oil reservoir level will signal oil seal system and/or field modifications to dry gas seal systems.
problems and lead to their resolution before the refrigeration system,
plant capacity and revenue are affected. Benchmarks
This best practice has been used since the mid-1980s, when multiple
Lessons Learned issues had reduced the capacity of refrigeration processes and af-
Failure to monitor and correct infiltration of oil into re- fected plant revenue. Since that time this best practice has been used
to optimize oil seal system reliability and refrigeration process plant
frigeration systems has resulted in large decreases in plant
revenue.
capacity totaling millions of USD in revenue.

B.P. 7.6. Supporting Material sized for adequate residence time and the seal oil leakage is
reasonable (less than one gallon per hour per seal). A sweet
hydrocarbon gas is defined as a gas that does not contain
Sweet hydrocarbon or inert gas service hydrogen sulfide (H 2 S). The vent line on top of the drainer
canberoutedtoalowerpressuresource, to theatmosphere
For sweet or inert gas service, the seal oil drain can be or back to the compressor suction. If routed back to the
returned directly to the reservoir, provided the drainers are compressor suction, a demister should be installed to

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