Study On3-D Flow Field And Fatigue Characteristics Of Steam Condenser

Steam cooler is the key equipment which is used to condense the excess superheatedsteam from once-through steam generator. It is mostly used to ensure steam power plantrunning steadily from startup to trip, and under low load condition. The operation status of thesteam cooler is related to the safety of whole steam power plant directly.The steam cooler considered in this work is of the shell-and-tube type, in which thesteam flows through the shell and the secondary fluid inside the tubes. The flow and heattransfer characteristics are changed from single phase flow to vapor-liquid two-phase flow. Tounderstand the flow and heat transfer process of the superheated steam in the cooler,especially in order to know the onset location of steam condensation is very import for theanalysis of the stress characteristics of tubes. It is necessary to simulate and predict the flowfield and the temperature field of the steam cooler used CFD tools.With the numerical methods and models such as multiphase flow model, evaporation andcondensation model etc. provided by ANSYS FLUENT, a3D numerical study of thevapor-liquid two-phase flow in the steam cooler is performed. The fatigue analysis isprocessed by ANSYS APDL with the information of temperature field of steam cooler.The results show that the steam and liquid is gathered in the middle tubes due to thepresence of impingement baffle and cross baffle. As the blocking effect of impingement baffle,the steam does not directly rush on the top tube of the steam cooler, so the thermal stress ofthe tube will be reduced. In addition, the flow field and temperature field of shell side showssignificant asymmetry. The fatigue analysis results show that the performance of tubessatisfies the requirements for operation of steam cooler during the life time.