WHY USE A KLEENTEK ELC on Turbines

WHY USE KLEENTEK ELCs ON TURBINE PLANT?
INTRODUCTION
Gas and Steam Turbines are becoming more aggressive to
their oil systems and the systems themselves are being
engineered to tighter tolerances. In-line with this trend
Turbine operators are now among the most popular group of
users for Kleentek ELCs in the UK.
UK experiences suggest there is a consistent list of oil related
problems that cause downtime and unnecessary maintenance
costs.
Below are some of the problems that have led to Turbine
operators installing Kleentek ELCs. Each scenario is based on
experiences in recent years that have resulted in lost
generation or the need for premature oil changes. All have
been greatly improved by a Kleentek ELC application.
STICKING VALVES
Sticking valves are experienced by many operators of modern Turbines. This is a
common problem and is caused by oil oxidation products adhering to the valve,
resulting in ‘stick/slip’ or total seizure.
The most common cause of sticking valves is
the build up of oil oxidation products. These
build up on the valve over time, gradually
creating layers like ‘varnish’ on the valve.
Clearances are reduced until leading to
malfunction.
‘Varnish’
Kleentek reduces the likelihood of valve
failure because it removes oil oxidation
products from the oil. Also because the oil
becomes very clean then the oil itself will gradually remove existing layers from
valves through a process of equilibrium, allowing them to operate more freely without
the need to change the valve.
One valve failure will lead to an unplanned stoppage. From previous experience one
unplanned stoppage due to a sticking valve will easily pay for several Kleentek units.
OilCare Ltd
72 Oak Tree Lane, Mansfield, Nottinghamshire. NG18 3HL (UK)
Tel +44 (0)7795 545676 Fax +44 (0)1623 651832 [email protected]
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IN-LINE FILTER BLOCKAGE
Problems have been experienced whereby a build up of sludge entered the Turbine
lube oil in-line filter system. This resulted in one Turbine being taken off line while
the filters were changed. Filters were repeatedly becoming blocked and the only way
to cope was to repeatedly change the filters, incurring the costs of replacement filters
along with downtime costs of several hours.
It is important to understand that the build up of sludge is caused by presence of oil
oxidation products. These had developed in the system over time, forming layers on
the bottom of the tank. Something happened in the oil reservoir to disturb the sludge,
leading to sudden filter blockage and catastrophic breakdown, even though an oil
change had taken place between the sludge build up and system failure.
A Kleentek unit was fitted and no more filter changes were required and the oil
cleanliness returned to a very good level. Had an ELC been fitted from an early stage
the sludge would not have built up in the first place.
The cost of downtime paid for the Kleentek unit several times over.
Also the Gas Turbines have In-Line and Last Chance Filters for their control valves.
These valves control gas flow and inlet guide vanes etc. When the filters become
blocked then the valves will not operate, leading to the turbine being shut down.
Below are examples where oil oxidation products have caused these filters to become
blocked.
Servo Valve In-Line Filter
Servo valve Last Chance Filter
OilCare Ltd
72 Oak Tree Lane, Mansfield, Nottinghamshire. NG18 3HL (UK)
Tel +44 (0)7795 545676 Fax +44 (0)1623 651832 [email protected]
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BEARING WEAR
Effective lubrication is achieved by keeping moving surfaces apart, through a thin
lubrication film. Often the clearances involved, or the thickness of the oil film is only
a few microns. Present thinking is concerned with keeping the oil clean. However,
the lubricated surfaces must also be kept clean.
As oil becomes saturated by oil oxidation
products, they are naturally attracted to
the inner surfaces of the machine. This is
because oil contaminants are polar and
the metal surfaces have a high permanent
di-pole moment. Therefore, layers of
contaminants build up like ‘varnish’ over
time on moving parts such as bearings,
which leads to high friction and wear.
Whilst on a turbine this may not lead to a sudden failure, it will increase contaminants
in the oil and will require the bearing changing at the next major outage.
The increased length of outage and the cost of the new bearing would buy several
Kleentek units
The pictures below show how Kleentek has kept the internal surfaces of a pipe clean.
The picture on the left is before fitting Kleentek, the picture on the right is even 5
years after Kleentek was fitted. This proves that Kleentek keeps the internal surfaces
clean, not just the oil.
Before applying ELC
After applying ELC
OilCare Ltd
72 Oak Tree Lane, Mansfield, Nottinghamshire. NG18 3HL (UK)
Tel +44 (0)7795 545676 Fax +44 (0)1623 651832 [email protected]
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OIL LIFE
Oil degrades at varying rates, depending on type of oil, system design, system
temperature etc. However, a further significant accelerant of ageing is contaminants
in oil. Therefore, the cleaner the oil is, the slower the ageing process.
Present methods of cleaning oil involve fine filtration. However, a recent discovery is
that fine filters cause sparks in the oil. These sparks crack the oil molecules which
stimulates the oil ageing process. Therefore, fine filters reduce the life of oil.
The Kleentek ELC method removes many more contaminants than fine filters and at
the same time it does not cause sparks. Therefore, by using Kleentek to clean the oil,
rather than fine filters, the oil will last longer.
Furthermore, many oil changes are carried out purely due to contamination levels
which cannot be addressed by conventional filters. Kleentek will remove many more
contaminants than conventional filters, so the oil should not need to be changed due to
high contaminant levels alone.
Generally on Turbine applications, if one oil change is saved, then this will pay for the
Kleentek unit.
EFFECT OF OIL TEMPERATURE
Oil oxidation products are only harmful when they become insoluble. Their solubility
is dependent on oil temperature (the colder the oil the more products become
insoluble). Therefore, if the plant is periodically shut down then it could be that
oxidation products ‘grow’ in the system and then form deposits on bearings, valves
etc. In such situations it is important to remove these products with Kleentek in order
that future reliability problems are avoided.
CONCLUSION
Oil contamination, particularly oil oxidation products, can lead to many problems in
turbine plant. They reduce both the reliability of the Turbines and the useful life of
the lubricant.
Oil oxidation products build up layers on all internal surfaces including valves,
actuators, bearings, pumps, tank walls and floor, pipework etc. They can cause a
build up of sludge in the system along with ‘varnishing’ on valves and other moving
parts such as bearings.
OilCare Ltd
72 Oak Tree Lane, Mansfield, Nottinghamshire. NG18 3HL (UK)
Tel +44 (0)7795 545676 Fax +44 (0)1623 651832 [email protected]
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Fine filters accelerate the development of oil oxidation products because they create
sparks in the oil, which cracks the oil molecules.
The utilisation of Kleentek ELCs removes far more contaminants than conventional
filtration, without causing sparks. The oil becomes so clean that the oil even removes
contaminants from internal surfaces. This reduces the risk of system failures and as
well as increasing oil life. This can be more relevant too if the plant periodically shuts
down due to the solubility changes of oil oxidation products.
Exact paybacks are impossible to predict, however, evidence suggests that if
downtime is included in the payback, the prevention of one failure, one main
component change or one oil change can each easily justify the investment in
Kleentek.
OilCare Ltd
72 Oak Tree Lane, Mansfield, Nottinghamshire. NG18 3HL (UK)
Tel +44 (0)7795 545676 Fax +44 (0)1623 651832 [email protected]
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