How to avoid, fix problems with boiler feedwater valves
Combined-cycle powerplants offer a great
deal of operating flexibility, typically having the ability to respond to changing load demands much faster than large fossil-fired steam stations. So it is not surprising that in competitive power markets combinedcycle facilities are experiencing more operating cycles than owners planned for at the design stage.
deal of operating flexibility, typically having the ability to respond to changing load demands much faster than large fossil-fired steam stations. So it is not surprising that in competitive power markets combinedcycle facilities are experiencing more operating cycles than owners planned for at the design stage.
While the ability to cycle a large combined-cycle plant is ideal for fleet flexibility, frequent startups and shutdowns strain many critical components and limit their effective lifetimes. Witness the relatively common boiler tube failures caused by flow-accelerated corrosion (FAC) and the premature failure of steam-turbine bypass valves. Such problems can bring a plant down for extended periods, often without warning.
Another maintenance issue, one that has not received much publicity to date, has to do with valves in the boiler feedwater system.
The design of boiler feedwater systems varies somewhat from plant to plant, but the valves used are fairly repeatable.