Development and Investigation of a New Rotary Valve for Power Steam Turbines

Abstract

Control valves are actuating elements of a steam turbine control system; the quality of their performance directly affects the reliability of the overall steam turbine unit. Accordingly, these valves must meet very stringent requirements. Among the factors and characteristics responsible for the quality of control valves, an important place is occupied by the design simplicity, manufacturability, serviceability, ease of installation, high operating reliability, low hydraulic resistance, low dynamic loads acting on the valve stem, and moderate noise level. At the same time, it should be noted that there is quite a large fleet of old, obsolete steam turbine power units at present in Russia with valves featuring both high hydraulic resistance and poor reliability. In new, linear control valves developed in the last decade, almost all design possibilities for their improvement have been exhausted. Hence, rotary control valves may be of great interest for practice. It is this type of valve that is considered below. This information includes a description of valve design, results from the investigation of flow parameters in the valve flow path, and the flow characteristic obtained by a mathematical simulation technique. This valve meets the above-mentioned requirements to the maximum extent, is fully balanced of axial thrust, has almost zero steam leakage along the drive stem, and is operated with low-power actuators with any bores and any initial steam pressures.