Flow characteristics analysis of ultra supercritical overload turbine control valve for power plant

Abstract

Experiments were carried out to analyze the flow characteristics of ultra supercritical (USC) turbine control and stop valve for a power conversion system. The USC turbine system provides highest internal efficiencies with lowest fuel cost. The overload admission feature has proven to be very effective for flexible turbine operation with rapid load (electric) change and improved startup performance. The turbine valve plays a pivotal role to regulate the output power as per load demand by controlling the mass flow to the turbine. As the electric power output in a turbine system is proportional to the mass flow to turbine through valve, it should operate linearly. But though the ideal valve linearly controls the mass flow rate with its stem lift, the real valve has various flow characteristic pursuant to the plug and or stem lift type. Hence, it is necessary to check the flow characteristic and control performance precisely before installation of the valve. In this experiment, compressed air was used as the working fluid and LabVIEW was employed for real time data acquisition. CATIA V.5 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">®</sup> was used for three-dimensional computer-aided design. A test loop named VELO (Valve Engineered Layout Operation) was built to experimentally investigate the flow characteristics of the control valve. The flow characteristic curves were plotted by calculating the ratio of the measured mass flow rate versus the theoretical mass flow rate. The flow characteristic curves were utilized to check the performance of the turbine system control valve to ensure the highest controllability, reliability and safety of the power conversion system of nuclear power plants as well as fossil fuel plants.