18th – 29th June 2012
The final elements to the British Sugar upgrade have been completed. This ultimate stage consisted of comprehensive functional testing of all elements to the set, emergency stop tests, overspeed trip testing and a final testing of the turbine onload.
The ProTech TPS was tested to ensure it functioned correctly. The TPS is a 2 out of 3 system in which there are three independent modules; if any two give the same value it results in a functional output. If one module fails therefore, the system can still function and an alert of the failed module will be issued. The correct functioning of the three dual MPUs was also tested to ensure all three read correctly with the turbine turning over an electric motor at 263 RPM.
We also tested the 505 overspeed trip and the mechanical overspeed trip. The CPC-II (Current to Pressure Converter) was the final module to be tested. It is wired to the 505 control that positions the steam inlet valve to desired position depending on speed and load. All data feeds back to the HMI enabling the status of equipment to be monitored.
Lastly we ensured a final testing of the turbine onload took place, which generated 8MW and exported 4MW to the National Grid. The final test was very successful and proved very stable.
Overhaul and service
Ansaldo Valve Actuators
Our customer, a specialist installer of steam turbine generator sets, approached us to have a selection of valve actuators overhauled and performance tested in order to improve the performance of the valves. Significant wear could be noted in addition to oil leakages which were limiting oil pressure by two bar.
We were sent three valves:
- One HP Control Valve Actuator, for inspection of the glyde ring and cylinder bore.
- A Main Steam Stop Valve Power Cylinder, which was showing signals of excessive wear in particular to the cylinder bore and piston.
- An Oil/Air Relay Device – the customer was experiencing problems of air relay changeover and air escaping.
To overcome these challenges we replaced all seals which were designed and remanufactured due to being obsolete. All bores were also honed and we machined new bushings and piston rods where necessary.
The valves were tested hydraulically to the customer desired set points in addition to oil pressure.
Check out the photos of these valves pre and post overhaul to the right.
Governor Technician Steve recently overhauled a TG17E, an electric turbine governor. Unlike the TG, it doesn’t have a ballhead assembly, but rather a milliamp control. This was a routine overhaul in which all parts were cleaned, inspected for wear and replaced as necessary. All consumable parts were also replaced and the TGE tested to specification using a calibrated milliamp supply versus degrees output.
You can see a picture of the TGE to the right on test by Test Supervisor Ivor.
Governor Technician Chris overhauled one RE 1102V-4G-25L, high pressure governor of around 250 psi. The state of the governor was particularly dirty indicative of heavy engine oil contamination from the drive shaft oil seal.
Several key components had suffered notable wear. The rotor assembly was a 3G rotor, replaced with the metrics version 4G. The drive shaft was also replaced in addition to all consumable parts, gaskets and seals. The motor was also excessively worn and replaced.
The RE can be seen on test to the right.