Experimental And Numerical Study On Swirl-vane Steam Separator Using Air And Water Model Fluids

In nuclear power plants the steam generators generates saturatedsteam/water mixture, however, high-quality dry steam is only allowed tosupply to the steam turbine. Swirl-vane steam separator removes more than75%moisture from steam and hence has a huge influence on operatingperformance of the steam turbine and, consequently, the safety and economyof nuclear power plant. Small-scale swirl-vane steam separators, which aredesigned referencing that in the PC300(Qinshan I) and AP1000, are built andstudied by experiments and numerical calculation.Tests with water/air mixture as model fluid were carried out toinvestigate the separation efficiency of swirl-vane separators with differentvane structure and height of outlet section. Separation process is investigatedthrough flow visualization. Parameters indicating separator performance, i.e.separation efficiency and pressure drop, are measured. And effects ofseparator structure, water and air flow rates, inlet droplet size on separator performance are investigated. The experimental results show that theseparation efficiency is significantly influenced by water flow rate. Itaugments gradually with increasing water flow rate and reaches its saturatedvalue at water flow rate of0.3m~3/h. When water flow rate is larger than0.3m~3/h, the separation efficiency drops. Pressure drop is sensitive to the airflow rate and increases remarkably with increasing air flow rate.CFD analysis is utilized to predict the complex flow structure in theswirl-vane steam separator. For two-phase flow calculation Euler two-fluidmodel is used where gas is defined as continuous fluid while water is definedas dispersed fluid. The SSG Reynolds stress model is used to model theturbulence. The flow structures in the three steam separators are obtained. Allof them agree with the visualization. The simulation results show that thedroplet size distribution has an obvious influence on the separation efficiency.The simulation results considering the droplets as particle mixture of twosizes agree better with the experimental results well in separation efficiency.The thesis is dedicated to study separation characteristics and parametersensitivity of swirl-vane steam separator by experiment and numericalanalysis, and to investigate the flow characteristics of steam-droplet mixturewith CFD analysis.