Reclamation of FRF at Coastal Energen Pvt. Ltd. (Tuticorin)
Customer: Coastal Energen Pvt. Ltd. (ENERGEN), the power generating flagship company of the coal and oil group, is a 1200 MW coal fired thermal power plant in the district of Tuticorin in the State of Tamil Nadu, India.
Symptom Observation: • The power plant was observing a loss in the production of electricity generation • The operation & maintenance team has identified that the turbine governing command is not functioning properly and is tripping frequently on regular interval • On further investigation it was found that the servo valve (Moog valve) has failed and showing hunting or sluggish behaviour
Problem Identification: Failure of Moog valve was the main reason for the trip of the turbine and ultimately reason for breakdown in the power plant.
Poor Oil Analysis Program: an oil analysis is supposed to be done monthly for Particle count & TAN (weekly if trend is negative) and weekly test for water content but the customer has undefined scheduled for it.
Inadequate Operation Practices: The solenoid valve of LVDH (oil purification machine) vacuum line was only 20% close, due to which vacuum was not able to generate.
Root Cause Analysis: High ingression of contamination in FRF flowing through the line which choked the filter before servo valve spool. Presence of varnish & silt in the clearance of the spool has created an obstruction for its to-fro movement inside the servo valve. Also, the high TAN value led to electro kinetic erosion of line and accessories of EHC system & subsequently formation of fine metal particle (solid contamination). It was concluded that all these factors related to lubricant degradation have contributed to the valve failure.
Solutions Implemented: Minimac uses the proven technology for reconditioning EH oil i.e. TAN reduction by ion exchange method (TRIX) MLC LVDH TRIX 20 which is a combo package designed for simultaneous reduction of TAN, moisture and NAS value of the EHC fluid. It plays a major role in achieving the properties range within the recommended limits. An onsite training on the function of EH oil re-conditioner, FRF maintenance and contamination control, importance of oil analysis program was provided to their team by Minimac’s service engineer.
Filter consumption: 01 qty of 10-micron filter element and 01 qty of 3 microns consumed to achieve NAS 5 cleanliness
Total consumption of resin: 36 Ltr
Total running hours of equipment: 698 hrs
Below chart is showing the trend of decrease in the values with continuous cycling of EH Oil.
Benefits: • Extending oil life • Reduced TAN value • Eliminate oil replacement cost • Increased turbine availability & reliability
Way Forwards: In order to have complete purification of FRF, an ex- ternal FRF Reconditioning system is recommended. The Minimac’s FRF Reconditioning system comprises 4 major Technologies, all packaged comprehensively in 1 single system. • Solid contamination super-fine filtration • Moisture in oil separation by vacuum dehydration technology • TAN reduction by ion exchange technique • EHC system tank Moisture removal and ingress prevention by Inert Gas Blanketing technique.