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ProTech TPS Trip System: Valtek / Pneumatic Solenoid Upgrade


PROJECT OVERVIEW:

Governor Control Systems, Inc. was contracted to provide a new overspeed trip system to replace the old and problematic mechanical overspeed bolt on an Elliot 2 DYR steam turbine. The turbine was experiencing downtime which required operations to valve out steam so a manual reset of the trip valve could be performed. The control solution was a Woodward ProTech TPS 2-oo-3 voted Overspeed Protection Device. The ProTech TPS along with a new pneumatic actuator coupled directly to the existing steam valve would be used for steam shut off to the turbine.

TYPE OF PLANT
  • Sulphur Burning Plant Operating 24/7
PRIME MOVERS
  • Elliott 2 DYR Steam Turbine driving a compressor
CONTROL TECHNOLOGIES
  • Woodward ProTech TPS with custom GCS software for online partial stroking and trip time cycle counter

  • GCS Custom Valtek mounting kit to customer existing trip valve

  • Redundant Pneumatic Solenoids for tripping of Valtek
  • Pnuematic Solenoid Valve for partial stroking
  • Limit switches for valve position monitoring

An online partial stroke testing feature was also incorporated into the function of the system to ensure the trip valve would perform as needed when a trip event occurs. This test allows the user to see if problems are present before a trip event occurs.

An additional feature added was Total Trip Cycle Timing. This feature allows the user to monitor all trip cycle times to verify if issues are present which slow trip cycle times down. This is a very good indicator of potential valve sticking issues.

Upgraded Trip System

The new trip system allowed for the removal of the mechanical overspeed bolt due to its 2-oo-3 voting logic. The new speed sensing arrangement was placed on the turbine in accordance to API 612 guidelines. Other components of the system included custom bracketry, limit switches, pneumatic solenoids, and new speed sensing arrangement to monitor overspeed events. The pneumatic trip valve actuator receives its trip signal from redundant solenoid trip valves which are controlled via the ProTech TPS.




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