Protracted problems with pneumatic control valves have been successfully eliminated by the introduction of electro-hydraulic alternatives at the Scottish Power Longannett power station in Clackmannanshire. The new equipment – comprising Rotork Skilmatic actuators and Evola ball valves – have been installed to control water levels in direct contact heater and condenser plant areas. The Rotork Skilmatic electro-hydraulic actuator and Evola ball valve combination were recommended by specialist actuation service provider Exeeco. The Skilmatic actuator provides the simplicity of electrical operation, combined with hydraulic operation for modulating or failsafe applications. The actuators operate directly from an electrical supply and control signal, without relying on a pneumatic supply. The new actuated valves were installed during a major outage on Longannett Unit 2 in the summer of 2004.
