Upgrade of turbine intake damper controllers on SS Cape Isabel - Case Study

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Courtesy of Rotork

Overview
SS Cape Isabel is a 655ft, 15,000 ton roll on/roll off cargo ship based at Long Beach and operated by the US Military Sealift Command. Launched in 1976, the ship is powered by two steam turbines.

The Reason
The ship’s two turbine intake radial vane dampers were equipped with pneumatic controllers (actuators) which were now obsolete. The old actuators did not respond quickly and accurately to signals from the control system, resulting in potentially inefficient combustion and undesirable emissions. Replacing the actuators was necessary to increase efficiency, reduce maintenance and associated costs that could result from unplanned shutdowns.

The Solution
The equipment selected to upgrade the old actuators was Rotork Type K damper drives, which provide a direct ‘drop-in-place’ replacement that exactly matches the existing damper drive footprint and output shaft location. Duplication of the existing drive’s dimensions simplifies the installation, enabling the upgrade to be swiftly completed in a matter of hours.

Type K damper drives incorporate vane type actuators that offer high speed full stroke capabilities of less than 5 seconds, combined with accurate and responsive positioning. The rugged construction is designed to withstand the harsh environments associated with power stations and combustion plants.

The Results
Once the two Type K pedestal mounted damper drive units had been delivered to the ship, installation of both units was performed by engineers from Rotork Site Services within three days. All the work was co-ordinated prior to commencement by the ship’s Chief and First Engineers.

The Timetable of Installation
Day 1

  • Transport shipping crate containing new Type K units to weld shop so they could be lowered via chain hoist into position 1 deck below in the engine room
  • Isolate pneumatic supply and analogue control signal
  • Confirm authorisation to remove existing damper linkage, pneumatic supply line, analogue control cable and old units
  • Perform above tasks for Port Damper control
  • Install new Type K unit, attach damper linkage, test hand wheel operation and adjust linkage arm

Day 2

  • Confirm authorisation to remove existing damper linkage, pneumatic supply line, analogue control cable and old units
  • Perform above tasks for Starboard Damper control
  • Install new Type K unit, attach damper linkage, test hand wheel operation and adjust linkage arm

Day 3

  • Install new stainless steel flexible hose connection from Type K units to original copper pneumatic supply lines
  • Test operation of Port and Starboard units with mA generator to confirm correct I/P calibration and pneumatic operation of dampers
  • Install new Beldin shielded cable and junction box from Type K units to original analogue control shielded cable
  • Test operation of Port and Starboard units from Engine Room control panel to confirm correct operation
  • Demonstrate operation via control panel to the First Engineer
  • Demonstrate transition from “Auto” operation to “Manual” and vice versa to the First Engineer

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