Numerical Simulation And Optimization Of Flow Field In Flue Gas Circulating Fluidized Bed Absorption Tower

In recent years,great progress has been made in the prevention and control of air pollution in China,but the current form of pollution is still serious,the annual emissions of sulfur dioxide far exceed the capacity of the ecological environment.Therefore,the development of desulfurization technology is of great significance to improve the quality of atmospheric environment.The research object is the absorption tower in CFB-FGD system of a domestic roasting plant.Based on FLUENT 15.0,the gas-solid flow in the absorption tower of CFB-FGD system was studied by numerical simulation.The gas-solid coupling flow in the absorption tower was studied by using Euler-Lagrange method.The k-ε two-equation model was used to deal with turbulence,and the DPM model was used to deal with the particle phase motion,heat and mass transfer in the absorption tower.The paper discuss the influence of changing the parameters of venturi on the flow field in the absorption tower first.Then the variation of flow field and temperature field in the absorption tower with different nozzle heights was studied.Finally,aiming at the shortage of back mixing and premature escape of absorbent particles in the upper part of absorption tower,the solution of installing flow obstructor was put forward.The influence of the height of flow obstructor and the outlet wind speed on the flow field,temperature field and particle residence time was simulated and analyzed.Research shows that the entrance of elbow leads to the deviation of flue gas in the absorption tower.Adjusting the parameters of venturi tube can effectively improve the asymmetry of flow field distribution in absorption tower.Adjusting the height of atomized water nozzle has little effect on the flow field of flue gas in the absorption tower,but has obvious effect on the temperature field.With the decreasing of atomized water nozzle height,the temperature distribution uniformity in the middle region of the absorption tower increases gradually.The gas-solid two-phase disturbance in the absorption tower can be enhanced by installing a flow obstructor in the tower,and the residence time of the absorbent in the tower can be prolonged,the flue gas temperature at the outlet of the absorption tower can be effectively reduced.The residence time of absorbent particles in the tower is prolonged with the increase of the installation height of the flow obstructor,and the outlet flue gas temperature is decreased at the same time.The average turbulent kinetic energy of the flue gas in the absorption tower increases with the increase of the flow obstructor’s outlet wind speed,the residence time of the absorbent particles in the absorption tower is also prolonged.and the outlet flue gas temperature decreases gradually with the increase of the outlet cold air flow rate of the flow obstructor.