Best Practice for Steam Turbine Mechanical Worldclass engineering

Best Practice for Steam Turbine Mechanical World-class engineering Overspeed Trip Assembly and support Dan Whitton - Aftermarket Sales Manager Matt Down, Field Service Manager 8 th November 2015 1

Agenda 1. Protection Systems Overview 2. Purpose of Mechanical Overspeed Trip 3. Best practise for maintenance of Mechanical Overspeed Trip 4. Oil Cleanliness 5. OEM Responsibilities 6. Conclusion Technical Support Parts Supply & Management Engineered Solutions Customer Repair Services Customer Training 2

Protection Systems Overview To protect the Steam Turbine during abnormal operation events, a number of protection systems are used, these systems can be collectively named as the Emergency Trip Gear. Typical Examples: • • Mechanical overspeed trip Electrical overspeed trip Manual trip valve Control Stop & Emergency Valve Master trip valve Solenoid trip valve LP inlet valve 3

Protection Systems Mechanical Overspeed Trip ü Typically mounted on the steam end of the turbine rotor ü The mechanical trip set point is pre-set by the factory 4

Protection Systems Mechanical Overspeed Trip ü To ensure that the turbine is protected from an overspeed event, a mechanical overspeed device is utilised. ü The mechanical overspeed device utilises the centrifugal forces created during turbine rotation to ascertain the rotational speed. ü During overspeed, the centrifugal force is so great, the spring force is overcome and the valve dumps the relay oil to drain 1 2 1. 2. 3. 4. Cap Spring Valve Trip Shaft 3 4 5

Turbine Operation Overspeed Testing ü A full functional test of the mechanical overspeed system is recommended to be carried out before every running period and the tripping speed recorded, reviewed & approved ü As a minimum, we would recommend it is tested every 6 months (minimum) Or ü Tested after prolonged shut downs (Test at the beginning of the sugar season) 6

Turbine Operation Overspeed Testing NEVER exceed the overspeed trip tolerances Typically 10 -15% Mechanical 10% Electrical 7

Turbine Operation Overspeed Testing If the turbine does not trip when it is supposed to then immediately shutdown and isolate the turbine Thoroughly investigate the issue before going any further Overspeed failures can be deadly & catastrophic 8

Turbine Operation Examples of Overspeed Failures 9

Turbine Operation Examples of Overspeed Failures 10

Protection Systems Examples of poor maintained overspeed trips 11

Protection Systems Examples of correct maintained overspeed trips 12

Oil Cleanliness ü Common cause for the overspeed trip to not operate ü Additionally dirty oil can also lead to: ü ü Severe damage to journal bearings High vibration Efficiency losses Shutdown and potentially catastrophic damage to equipment 13

Original Equipment Manufacturer (OEM) Responsibilities ü Supplying a manual for the machine ü Including installation instructions ü Operating ü Maintenance ü Notifying you of any upgrades or safety concerns around the equipment ü Via Technical Support Bulletins ü Providing Training ü Technical Support 14

Conclusion Do’s ü A full functional test of the mechanical overspeed before every running period ü Test the overspeed trip every 6 months as a minimum ü Document regular recording and monitoring of the trip speed Don’t ü Exceed the overspeed trip tolerances ü Continue to run the turbine if it is supposed to trip ü Allow the oil cleanliness level to drop ü Allow the overspeed trip to become seized 15

Technical Support Thank you. Any questions? Dan Whitton Parts Supply & Management Engineered Solutions Customer Repair Services Customer Training 16