Numerical Simulation Of Steam-liquid Perfored Seperator In 100t/h Boiler

The steam-liquid plate separator in boiler drum with the steam capacity of 100t/h and steam pressure 6.47 MPa is used as the research object for the hydrodynamics and separation of droplets in this paper,the characteristics of underwater orifice plate,medium orifice plate and top steam orifice plate are numerically simulated and analyzed with the FLUENT.Through the force analysis,the force of the droplet in drum is determined,and the steam-droplet two-phase flow model is established based on the mass and momentum conservation laws.The convergence and grid sensitivity of numerical solution are analyzed using different grids numbers.Meanwhile,the distributions of steam concentration,steam velocity and streamline of steam and water have been studied under the different drum water levels.Numerical simulations show that the stable zone formed between the underwater orifice plate,and the inlet of the water cooled wall tubes can effectively improve the distribution of the flow field in the drum.The middle orifice can block the droplet from the water level directly into the steam space and avoid the droplets carried directly by steam.The top steam orifice improves droplets separation efficiency.The flow fields of steam and droplets in the underwater orifice plate,middle and top orifice plate separators are numerically simulated under the low,medium and high water levels.The flow distributions of steam and droplets velocities,streamline,droplet concentration and overall separation efficiency are obtained.According to the simulating results,it is found that under different working conditions,the separation efficiency of steam-droplets is increased with the increase of diameter of droplets.When the water level is below the medium orifice plate,the vortex on the left side of the underwater orifice helps to separate the vapor from the saturated water.When the water level is below the centerline of the drum,the middle orifice can uniform the distribution of steam,and has the function as the same as the top orifice plate.As the water level is higher than the normal water level,the middle orifice plate has a function similar to the underwater orifice plate,and uniforms the distribution of steam.The cooperation of three plates will increase separation efficiency of droplets in the steam drum.