Influence of a Circular Filter on Super-Critical Steam Flow Through Main Stop and Control Valves in a 1000MWSuper-Critical Power Plant

摘要

Influence of a circular filter on the aerodynamic characteristics of steam flow through the closely spaced main stop and control valves, which were used in a 1000 MW super-critical steam power plant (262 bar, 600 degrees C) in south China, was numerically studied. A porous media model concerning the directivity of the pressure drop was applied to the circular filter; database of the dependence of the pressure drop on the superficial velocity was established by using computational fluid dynamics. The complex three-dimensional steam flow in the main stop and control valves was demonstrated to be well managed by the circular filter, through which the steam flow was straightened in the radial direction. As a result, the aerodynamic force exerted on the spindle of the main stop valve was greatly attenuated. However, the blockage of the filter to the steam flow was certain to increase the pressure loss in the main stop valve, whereas pressure loss in the control valve decreased due to the smoothened incoming flow. The dynamic behavior of the steam flow and the influence of the filter at different control valve openings have been studied as well. As the opening decreases, the flow velocity at the throat of the main control valve increases, and therefore, the pressure loss at the throat of the main control valve increases rapidly. The influence of the filter abates as the opening of the control valve drops.