Application of quadratic regression orthogonal design to optimization surface heating for control wet steam condensation flow in nozzle

Abstract

The condensed flow of wet steam in the low-pressure cylinder of a steam turbine will affect the safety and economy of the unit's operation. Therefore, it is necessary to reduce the influence of the wet steam on the turbine blades after condensation. Based on the research status at home and abroad, in view of the similarity of the steam turbine stationary blade cascade channel structure to the Laval nozzle, taking the Moses and Stein nozzle as the research object. The distribution law of the wetness and other parameters are obtained by numerical simulation under different heating intervals and heating rates. The results show that in the same heating interval, as the heating rate increases, the Wilson point continues to move backwards, while this requires a lot of heating. At the same heating rate, as the heating interval increases, the wetness of the same point also decreases. The maximum heating interval is 50% of the axial length. Finally, through the quadratic regression orthogonal design, the heating parameters to prevent the deposition of droplets on the surface were given, the optimal heating starting point is 1.33 cm, the heating interval length is 5.17 cm, and the heating rate is 0.221669J/(mm2·s). The research results can provide reference for the design of steam turbine stator blade heating and dehumidification.