Fisher EWT valves with Cavitrol trim improves cogeneration plant reliability, productivity and profitability.

A large cogeneration plant in the US providing electricity to a large city were having frequent problems with some of their critical va...

A large cogeneration plant in the US providing electricity to a large city were having frequent problems with some of their critical valves. The Dearator level control, for example, is a demanding application that requires valves to handle high flows, high pressure drops (165 psid), and potentially damaging cavitation. The existing rotary valves had experienced control problems and needed trim replacements at least once a year. The annual maintenance bill for one of these valves and cost to company was estimated at $100,000. During an asset management upgrade at the cogeneration plant site, engineers from Novaspect analyzed the application. Selecting a control valve required an analysis of the change in pressure drop across the valve as a function of the unit load. They recommended a replacement, Fisher valve with built-in protection against cavitation. Plant managers agreed to instal a new Fisher EWT sliding stem valve with a 585C actuator, two-stage Cavitrol III trim. The results of this exercise at the cogeneration plant improved valve monitoring and plant reliability. Eliminated cavitation and the need for frequent trim replacement.Finally they managed savings close to USD200,000 in unplanned breakdown, repairs and frequent inspections.