TXU Valley Makes the High-Performance Choice

When TXU Valley Steam Electric Station (SES) was experiencing problems with its superheater bypass valve, the three-unit gas/oil-fired supercritical power plant looked for a proven solution. With its sister plant, TXU Tradinghouse Creek SES, enjoying the success of CCI’s DRAG® technology, TXU Valley SES was confident that it too could benefit from the advantages of CCI’s superior control valve solutions.

The TXU Valley station, a Babcock and Wilcox supercritical power plant located in Savoy , Texas , was using a Fisher superheater bypass valve in unit 2. This valve is used during variable throttle pressure (VTP) mode to control turbine load based on megawatt demand. The valve must open against high inlet pressure at a steady, predetermined rate to allow the turbine load to increase or decrease gradually.

The existing conventional full-ported valve, however, suffered from extreme vibration at low flows and poor control throughout its short stroke. This resulted in high-risk system instability when transferring from variable to full throttle mode.

CCI’s customized solution for the TXU Valley station features DRAG® technology, including 16 pressure-reducing stages to eliminate the severe vibration that can reduce valve availability and increase the likelihood of breakdown and repair. The CCI valve’s characterized disk stack allows for low resistance at maximum flow and excellent trim exit velocity control at low flow.

This specialized design provides the high rangeability required to support throttling at various pressures, ranging from 10% to 70% of the max-continuous rating (MCR) of the boiler; it offers precise modulation to every signal for turbine load. CCI’s solution also features a longer, 10-inch stroke that will vastly improve turbine control during VTP.

With DRAG® technology successfully installed at the two sister plants, top performance and exceptional control is definitely running in the TXU family.

Published in SOLUTIONS Fall 20004