BFP is a DRAG® at Meredosia

The boiler feedpump recirculation valve is considered to be the most severe service application in power plant services. That’s why when the boiler feedpump recirculation valves at the Meredosia power station began to show signs of trim erosion, CCI recommended replacing the failing valves with two 2.5-in. x 2.5-in. (63.5-mm x 63.5-mm) boiler feedpump recirculation valves designed for the application’s demands.

The severe pressure drop demands seen by the BFP recirc valve is what causes it to be labeled as strenuous duty. The valve must reduce the high feedpump pressure to the low downstream pressure without generating excessive velocities that would create destructive cavitation or highly erosive flashing. The valve must also have a tight shutoff, and maintain this shutoff over a long period of time to prevent rapid seat and plug erosion failure through leakage. Failure to achieve either of these functions tends to result in a valuable loss of energy over an extended period, and in the worst case, a plant shutdown.

With velocity control DRAG® valves, CCI is providing long term reliability. Further, with the supply of a pressurized seat trim, which combines precise engineering and quality manufacturing to provide superior, block valve type shutoff (better than Class V), the DRAG® valve will not allow leakage. CCI’s pressurized seat trim effectively uses upstream pressure applied to the top of the plug to increase the seating load of the valve. The inlet pressure is allowed to pressurize the bonnet cavity through a controlled bypass path while the valve is in the closed position. When the valve must be opened, a pilot plug is opened by the actuator and the bonnet cavity pressure drops to the downstream pressure so that main plug can be moved.

Published in SOLUTIONS Spring 2002