Elimination of Flow-induced Instability from Steam Turbine Control Valves

This paper describes two steam turbine governor valve failures in the same installation, the troubleshooting that determined the root cause, and the new valve designed to prevent similar failures. The original governor valve design had been used successfully for many years in large multistage, multivalve steam turbines, but apparently was not reliable at the high steam pressures employed today. Mechanical analyses, flow analyses, and testing showed that the failures were caused by flow-induced instability in the valve. Candidate valves with more stable flow fields were designed and tested. The final design combined features of two other, more typical designs, and showed good flow stability throughout the lift range. This new “hybrid” valve has since been applied successfully