Experimental And Simulation Study Of Spray Scattering Desulfurization Tower

Nowadays,sulfur dioxide(SO2)pollution is very serious in China,which has brought huge negative impacts on people's health and social economy.Coal-fired power plants are one of the main sources of sulfur dioxide,so reducing the sulfur dioxide emissions of coal-fired power plants is very significant.The spray scattering tower combines the characteristics of the spray tower and the bubble tower,and has the excellent characteristics of high desulfurization rate,low energy consumption and wide load adaptability.Therefore,the gas-liquid two-phase flow and desulfurization characteristics in the spray scattering tower have also received widespread attention.According to the structure characteristics of the bubbling region of the spray scattering tower,the bubbling region experiment table was set up,and experiments were carried out under the conditions of different superficial gas velocity and immersion depth of the gas distributor,so as to explore the formation and breaking of bubbles and the gas-liquid two-phase flow in the bubbling region.The results are as follows:the diameter of bubbles formed on the surface of the gas distributor is about 10mm.The liquid phase moves upward above the gas distributor and downward near the bubble tower wall,forming a large-scale circulation.Moreover,the backmixing intensity of liquid phase is positively correlated with the superficial gas velocity and the immersion depth of the gas distributor.When the bubbles overflow the liquid surface,they break up,and small bubbles are formed and move with the liquid phase of backmixing.The gas holdup of bubbling bed increases with the increase of superficial gas velocity,and decreases with the increase of the immersion depth of the gas distributor.In the axial direction of the bubbling region,the gas holdup of the high bed is larger.The change of superficial gas velocity has little effect on the desulfurization effect in the bubbling area,and the increase of the gas distributor immersion depth will increase the desulfurization efficiency.Based on ammonia desulphurization technology and combined with the process characteristics of spray scattering tower,the spray scattering tower is divided into spray region and bubbling region,the mathematical model and physical model were established respectively for simulation,and the gas-liquid two-phase flow and the influence of PH value of slurry and other parameters on desulphurization in the tower is studied.The results are as follows:The mass fraction cloud map of sulfur dioxide in the spray scattering tower is closely related to the grout distribution cloud map,and the simulation results of the liquid phase flow in bubbling region agree with the experimental phenomena.The desulfurization rate of spray scattering tower increases with the increase of slurry PH,liquid-gas ratio and the immersion depth of gas distributor,while the desulfurization rate of spray scattering tower decreases slightly with the increase of flue gas flow rate.In all the simulation results,the sulfur dioxide concentration at the outlet of the spray scattering tower is generally lower than 35mg/Nm~3,the lowest can reach 10.16mg/Nm~3.Finally,based on the simulation results and combined with the actual operation parameters of the spray scattering tower,the corresponding guidance suggestions are proposed.