Feedwater Control is Okey-Dokey in Muskogee

It isn’t wise to take chances when dealing with a boiler feedpump, one of the most critical pieces of equipment in a power plant. On the bank of the Arkansas River in Fort Gibson, Oklahoma lies Oklahoma Gas & Electric’s Muskogee Generating Station, where plant operators were determined to find the best feedwater recirculation solution for top-notch plant performance and reliability.

Extreme fluid conditions and critical performance requirements make feedwater recirculation the most severe valve application in any power plant. The feedpump typically delivers feedwater from the deaerator to the economizer at very severe fluid conditions (up to 5000 psi / 500ºF or 300 bar / 260ºC). A minimum flow at the pump suction is required to prevent the feedpump from overheating and cavitating; this is made possible with a recirculation control valve.

At the Muskogee facility, a 535-megawatt, Combustion Engineering design, coal-fired drum boiler plant, the existing feedwater recirculation valves – CDC ball valves – failed every three months, and their valve bodies had eroded within two years of installation. The excessive leakage resulting from these poorly performing valves seriously undermined plant efficiency.

Thus in 2002, Oklahoma Gas & Electric called on CCI for a dependable, high-performance feedwater recirculation valve. Even though the plant had several feedwater recirculation valves to replace, the customer ordered just one CCI valve to test its performance.

This valve was a custom-designed 100DR valve featuring DRAG® technology with 18 stages of pressure reduction. By incorporating multiple tortuous flow paths to limit the trim exit velocities, CCI’s DRAG® valve eliminates the erosion that results in trim and body damage. The valve also features a pressurized seat plug design to achieve MSS-SP-61 leak-tight shutoff for zero leakage, protecting the seat ring and plug surfaces from cutting or pitting due to erosion or cavitation.

Since installation of this CCI feedwater recirculation valve, the Muskogee power plant has enjoyed the many benefits of leak-free valve performance, such as higher plant efficiency and lower operating costs. The solution proved so effective that, a year later, the customer decided to replace the remaining five CDC valves with DRAG®.

As Oklahoma Gas & Electric installs its new valves throughout the year, it can depend on the trouble-free operation it has come to expect from CCI’s DRAG® solutions. To date, all of the installed CCI valves are performing perfectly, eliminating cavitation and erosion damage, protecting the plant’s expensive boiler feedpumps, and handling the severe service conditions of recirculation applications to avoid unplanned shutdowns.

Published in SOLUTIONS Fall 20004