Numerical Simulation Of Semi-dry Flue Gas Desulfurization Reaction And The PIV Experiment Of Gas-solid Two Phase Flow In Powder Particle Spouted Bed

90%of sulfur dioxide emissions came from coal.In the air,sulfur dioxide was oxidized to sulfuric acid and sulphate under appropriate meteorological conditions,resulting in haze and serious acid rain problems.At present,a variety of desulfurization technology have been developed by the scholars.With high desulfurization efficiency,high utilization rate of desulfurization agent and the small environmental pollution,the powder-particle spouted bed semi-dry flue gas desulfurization technology will become a very promising desulfurization technology.In this paper,the process of desulfurization in powder-particle spouted bed was numerically simulated accorded to the experimental data.A mathematical model of water vaporization was established for investigation of heat and mass transfer in process of semi-dry flue gas desulfurization.The results of water vaporization in the powder-particle spouted bed were numerically investigated by two fluid model(TFM).The results showed that the water vaporization occurred in the spouted region and the outside of the annulus region.The water vapor generated in the spouted and the annulus region and entered the surrounding area of the bed as the air flows.At the entrance of the slurry and the top of the fountain region,the volume fraction of the water phase was large.The gas temperature was highest at the entrance of the spouted bed,the second is the spouted region,the outside of the fountain region and the outside of the annulus region.The steps of the desulfurization reaction were analyzed.By simplifying the assumption,the entire process was converted into a mass transfer controlled process between the two phases.The reaction model was established to study the desulfurization reaction characteristics of semi-dry flue gas desulfurization.The two-fluid model was used to simulate the desulfurization reaction process in the powder-particle spouted bed,and the simulation results were compared with the results of experiments.The results showed that the area with the most liquid water distribution is in the annulus region,also the annular region was the main area of desulfurization reaction.The reacted production was accumulated in the annulus region and the exit of spouted bed.When desulfurization reaction achieved stability,the desulfurization efficiency in powder-particle was slightly increased compared with the literature simulation value,but still slightly lower than the experimental value,further improvements are needed to improve the accuracy of the simulaiton.The longitudinal vortex generator was adopted in the gas-solid two phase flow system in the spouted bed so as to strengthen the particles radial mixing betweem spout and annulus zone.In order to examine the enhancement of mixing between gas and solid phases in spouted bed.The PIV technique was used to study the spouted bed with vertical vortex generators.The results showed that the longitudinal vortex enhanced the radial mixing of the gas and particles in the spouted region and the annular region.The effect of sphere longitudinal vortex generators on strengthen particle radial movement was better than that of cylindrical vortex generators.In addition,there exist an optimal diameter of the sphere and the distance between two spheres,at which the effect of longitudinal vortex generator on strengthen the particles radial mixing was optimal.