Technical Bulletin
Turbine Oil Condition Monitoring - Part 01
By Wanda – Technical Support PT Petrolube Cakra Persada
Introduction
Modern steam and gas turbines subject the turbine
lubricant to ever greater demands. Higher
temperatures are encountered in bearings,
smaller reservoirs reduce residence times, and issues with varnish deposits
have become critical concerns. Since the oil is the lifeblood of reliable turbine operation, a sound oil condition monitoring is needed to ensure long trouble free
operations.
Turbine Oil
Degradation
There are four primary reasons that
turbine oils degrade in service. First is oxidation. All oils oxidize in
service when exposed to oxygen in the atmosphere. And oxidation is not limited
to the reservoir as air is dissolved in the oil. With the increasing
temperatures found in turbines, increasing flow rates and shorter reservoir residence times, the oxygen and oil have more
opportunities to interact.
Second is thermal degradation. The oil can be exposed to temperatures in a turbine that cause base oil and
additive molecules to chemically
change. The result of this reaction is the formation of materials that are not readily soluble in the
oil. The materials then deposit
within the oil system causing deposits, and in some cases, equipment failures.
Third is contamination. Turbine oils
are subject to a variety of contaminants
such as water (especially in steam turbines), dust and other ingress materials, wash down chemicals, and internally derived contamination, such as wear metals. While
none of these are a direct result of
oil degradation, they often contribute to other degradation issues. Wear metals, such as copper iron and lead, catalyze the oxidation reaction. Water (especially
chemically treated water) can have very adverse effects on the ability
to dissipate foam and separate from water.
Excess foaming can lead to sluggish
response from hydraulic control systems, cavitation in pumps and bearings, and safety issues if the foam
over fills the reservoir and spills on the floor.
The fourth is additive depletion. Some additive depletion
is normal and
expected. Anti-oxidant additives are consumed as they perform their function. Demulsifiers
help the oil shed water, but if exposed to large amounts of water contamination, the
demulsifiers can
be removed. Antifoam additives can be removed from ultrafine filtration or can agglomerate
when the oil is not circulated for extended periods of time.
All of these factors should be consistently
monitored throughout the life of
the turbine oil. The following describes the tests most commonly
used for used turbine oil monitoring. They can be broken into three categories: Physical and Chemical Properties, Contamination Measurements and Performance
Properties.
Continous.........
For additional information, please contact:
PT. PETROLUBE CAKRA
PERSADA
The Promenade Building 2nd
Floor, H2
Jl. Warung Buncit Raya No.
98 Jakarta 12510
Tel.: (62)-21-7048 1177/88
Fax.:(62)-21-7919 1336
Email: info@petrolube.co.id
Email: technical@petrolube.co.id