Our customer, a European refiner and wholesaler of petroleum products, approached us in April 2009 to design and build a new steam turbine control to replace an old mechanical governor which had failed in service. The customer also had new control requirements for the equipment to meet their future plans for the business, in addition to seeking to improve safety and engineer usability.
The existing mechanical governor had to be modified in such a way that it no longer acted as a control but had a key purpose in driving the main oil lubrication pump that had to be retained.
The new electronic governor system was the Woodward 505 control and Woodward CPC-II current to pressure converter.
A new driveshaft for the oil pump drive was manufactured that incorporated a phonic wheel with three dual core speed pickups. Various blanking plates were made where mechanical control gear was mounted, utilising one of these for cable entry.
The CPC converter was mounted on the turbine and piped to the relay oil for supply and sensitive oil output for the steam valve control.
The Woodward 505 control was remote mounted next to the turbine start panel and incorporated various process meters and operational controls such as emergency shutdown, rpm indication & kW output indication.
Also used was an electronic two out of three voting overspeed trip system the Woodward ProTech G11 which is the latest self-testing, acceleration monitoring, overspeed trip device.
The replacement system was designed to include redundant back up power supplies for the control & overspeed unit and CPC converter which has replaced the old mechanical governor.
Performance testing & test tripping of the turbine proved very good along with far better performance that can now be monitored via Modbus to the turbine control room.