Experimental Hydraulic Analysis of Intake Structure for Cooling Towers Pumps

摘要

Experimental hydraulic analysis of troubleshooting intake structures for cooling towers (CT) pumps in nuclear power plant are presented in this paper. The formation of the free surface vortex in the pump sump with unfavorable intensity was not acceptable for the safe operation of the cooling towers pump and the cooling system in general. The objective of the present study is to investigate and improve hydraulic flow conditions in intake structure of CT pumping stations within acceptable criteria of the ANSI/HI standard experimentally. For this purpose, the physical hydraulic model with the scale factor 16 was made. Boundary conditions were calculated by dimensional analysis with the Froude number. The vorticity of flow in the suction pipe of the model pumps was measured and free surfaces and submerged vortices were observed. The model tests were made for all operating conditions of pumps Comparison between the model and prototype showed a good agreement by the formation of an identical free surface vortex in the same area of the sump. In order to prevent the formations of the unfavorable free surface vortex, the geometry of intake structures with the additional elements and obstacles were modified. Measured and observed results for additional tests have been obtained. The optimized geometry of intake structures provided favorable flow conditions by safety factor 1.5 within acceptable criteria of the ANSI/HI standard.