Varnish reduction in Siemens SST-400 steam turbine
High MPC values above 30 indicated varnish contamination and increased failure risk in a 65 MW Siemens SST-400 steam turbine. After installing a CJC® Varnish Removal Unit (VRU 27/108), MPC was reduced from 41.6 to 16.3 within 47 days and stabilised below 15, avoiding a €28,000 oil change.
Application Snapshot
Industry:
Power
Country:
Spain
Oil type:
Cepsa HD Turbines 46
Executive summary
During periodic overhaul checks, a high level of varnish was detected in the steam turbine lubrication system. Recorded average MPC values above 30 indicated high failure risk of heat exchangers, valves, and bearings due to contamination from varnish and oil degradation products.
To address this issue, a CJC® Varnish Removal Unit (VRU 27/108) with VRi inserts was installed.
The MPC value decreased from 41.6 to 16.3 within 47 days. Due to thick varnish deposits in cold surface areas, continued filtration for two years was required to stabilise MPC below 15. The installation avoided a full oil change of 15,000 litres, saving approximately €28,000, with an additional €3,000 that would have been incurred for oil supply, bleeding, and disposal.
MPC reduced from 41.6 to below 15
MPC decreased to 16.3 in 47 days and stabilised at 13.6 after two years.
Avoided €28,000 oil change
The installation prevented replacement of 15,000 litres of oil, avoiding significant cost.
Reduced failure risk of critical components
Lower MPC reduced the risk of failure in heat exchangers, valves, and bearings.
Prevented waste oil generation
Avoided oil change supported environmental policy and reduced waste oil.
Measured oil condition development
Before installation of the CJC® Varnish Removal Unit, the MPC value measured 41.6, indicating a high level of varnish contamination in the turbine lubrication oil. After 47 days of continuous filtration with the CJC® VRU 27/108, the MPC value was reduced to 16.3.
Due to the presence of thick varnish layers deposited on colder surface areas within the system, extended filtration was required. After two years of operation with the VRU installed, the MPC value stabilised below 15, reaching 13.6.
Results and operational impact
The installation of the CJC® VRU significantly reduced MPC values and lowered the risk of failure in heat exchangers, valves, and bearings. The system avoided a complete oil replacement of 15,000 litres, saving approximately €28,000, with at least €3,000 additional cost that would have been incurred for oil supply and disposal.
The CJC® VRU has maintained low pollution levels for more than three years without altering the oil’s properties.
Customer savings & benefits
- Reduced MPC values
- No varnish-related failure risk
- No need for oil change
- Reduced environmental impact
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