Moneypoint Generating Station Replacing Troublesome Drain

For years, the Moneypoint Station had been plagued with reoccurring problems associated with its emergency heater-drain and main-steam drain systems. Excessive pipe velocity and the presence of magnetite/iron oxide exfoliation particles were resulting in heavy erosion and reduced pipe line and valve trim life.

A complete system study, performed by CCI, determined that the root cause for the excessive velocities lay in the fact that the system control valve capacities far exceeded the system line capacity. Consequently, head loss was the controlling mechanism for the flow. Given this information, CCI recommended replacing the existing system control valves with lower capacity DRAG® valves. (As the existing valves were fitted with integral seats, retrofit was not an option.)

Based on a thorough understanding of the system requirements, CCI designed the trim for the replacement DRAG® valves to accommodate a reduced flow rate, which in turn, reduced the line velocity and system erosion. In addition, the trim for there placement DRAG® valves was designed to provide reduced system noise, while still being capable of passing the expected exfoliation particles within the fluid stream.

The replacement DRAG® valves were fitted with balanced plugs for reduced actuator loading and disk-stack trim with pressure equalizing rings (PER) to prevent unbalanced radial plug force loading.

Published in SOLUTIONS Fall 2000