Actuation Upgrade Improves Power Station Combustion Efficiency

Rotork electric modulating actuators have been installed in an upgrade at the RWE npower Fawley Power Station in southern England. Built in the late 1960s, the oil-fired station is capable of supplying the National Grid with 1,000MW of power to balance supply and demand at times of peak usage. It is therefore essential that the station can respond to the National Grid demands with speed and flexibility.

The Rotork actuators have replaced obsolete hydraulic actuators and power packs that were requiring increased levels of costly and time-consuming maintenance and presenting ongoing issues involving the use of hydraulic oils. These included high operating pressures and the potential for safety and environmental issues associated with leaks. The power packs also required continuous electrical power to maintain hydraulic pressure. By comparison, the Rotork actuators only use electricity when they are operating and do not require routine maintenance.

The upgrade project was awarded to Exeeco Actuation Projects and Service (APS), a company that specialises in power station maintenance and upgrade services. APS responsibilities encompassed the removal of old equipment, installation of new actuators, wiring into new local junction boxes, commissioning and product training for staff at the station.

The retrofitting began on the station's Unit 1 during the 2009 outage period with the installation of Rotork Type LA linear stroke actuators on reheat and super heater dampers and electric feed pump speed regulators. This was followed by the installation of Rotork Type SM6000 lever arm actuators on ID (induced draft) and FD (forced draft) fan discharge dampers. Upon completion of the project, a total of 16 Type LA and four Type SM6000 actuators have now been installed on Units 1 and 3.

The Rotork Type LA actuators deliver a self-locking linear stroke output of up to 610mm (24in) at the rate of up to 2,000 starts per hour. Rotork Type SM6000 actuators deliver a self-locking rotational output ranging from 90° to 313° for continuous, unrestricted modulating duties. Both types are specifically designed for the high temperatures, challenging environments and arduous duty cycles associated with power station operations. At Fawley the actuators are operated by the station's existing Emerson Ovation DCS system utilising 4-20mA signals for position demand and feedback.

Referring to the contract at Fawley Power Station, APS technical sales engineer Simon Finley commented: "This is an excellent demonstration of our ability to deliver complete actuation solutions, including the supply, design interface, installation and commissioning of our products."