Analysis and Research on the Aerodynamic Performance of HP Cylinder under the Mode of Regulating Steam Supply with Intermediate Control Valve
For the high-pressure cylinder of a 300MW unit,three-dimensional calculations were conducted on the modeling of the last five stages under three different back pressures of 3.4MPa,2.7MPa,and 1.9MPa.The aerodynamic flow characteristics of the last three stages were analyzed,and the ultimate streamline situation,changes in isentropic efficiency along blade height,and changes in relative work were studied.When the back pressure is controlled at 3.4MPa,when the inlet steam flow rate decreases to a certain extent,the flow state of the last three stages begins to deteriorate.When the back pressure decreases,the state at low flow rates improves.When the back pressure continues to decrease,there is flow instability at the root and top positions of the suction surface of the moving blade,while the flow is stable on the pressure surface of the moving blade and the surface of the stationary blade.When the flow rate decreases,the flow separation area on the suction surface of the moving blade decreases,and the flow condition improves.As the load decreases,the total isentropic efficiency of the last three stages gradually decreases,and the root and top efficiencies are lower than those of the blade,which is closely related to the separation phenomenon of the last three stage moving blades at the top of the blade root.Under the regulation condition of middle note valve,the blade frequency and strength can ensure safety due to the small temperature variation range.The upper and lower limits and corresponding constraints of exhaust pressure control of HP cylinder under the middle note valve participation mode under various working conditions are given,which can provide relevant guidance for the design and safe operation of middle note valve steam supply.And a lie test was conducted on the calculation object of 300MW to verify the reliability of the numerical calculation results.The control strategy of the medium pressure regulating valve can be obtained by providing the upper and lower limits of the exhaust pressure of the high-pressure cylinder under the parameter adjustment method of the medium pressure regulating valve under various working conditions.Provide a basis for heating design and guidance on operational adjustments.
deep peak shavingtotal entropy efficiencyflow fractioncontrol strategy
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