Experimental And Simulation Study On Optimization Of Flow Field In Wet Desulfurization Tower

According to the Emission Standards for Air Pollutants from Thermal Power Plants,the national limit value for sulfur dioxide emissions is 35 mg/Nm3,and energy saving,high efficiency and environmental protection have become the current optimization goals for power plants.In order to study the FGD technology limestonegypsum wet FGD technology faces a series of problems of ultra-low emission transformation,such as low efficiency and unstable FGD.This paper takes Zhangjiakou 300 MW power plant as the research object,builds a test bench and uses numerical simulation method to reduce the spray tower of the power plant according to 1:30,and studies the influence of tray opening rate and number of spray layers in the desulfurization tower on improving the stability of desulfurization efficiency.The study shows that the smaller the opening rate and the more the number of spray layers,the higher the desulfurization efficiency.The results of the study can provide guidance for the improvement of desulfurization efficiency in desulfurization towers,as well as scientific guidance for the improvement of desulfurization systems in coal-fired power plants.First,the principle of desulfurization technology is elaborated,including the principle of desulfurization reaction and five desulfurization systems,of which there are three zones in the desulfurization tower,namely,spray zone,mist removal zone and absorption and oxidation zone.The spraying zone is the main area where the desulfurization process occurs,so trays are added to the spraying zone of the desulfurization tower to improve the flow field inhomogeneity and increase the gasliquid contact time.The effects of the aperture rate and the number of spray layers on the desulfurization efficiency were also studied after the addition of trays.The results show that,due to the reduction of tray aperture rate increases the contact time between flue gas and spraying liquid,improves the liquid-gas ratio and increases the desulfurization efficiency;increasing the number of spraying layers helps to expand the contact area between flue gas and spraying liquid,the Ca/S ratio in the reaction changes,and the amount of absorbent injected into the absorption tower increases accordingly,which is positively correlated with the desulfurization efficiency.Secondly,numerical simulation studies were conducted using different optimization schemes of the desulfurization tower to discuss the effects of different local optimization schemes of tray opening rate and deflector on the internal flow field and desulfurization efficiency of the desulfurization tower.The simulation results show that by adding deflector plates and trays,the partial flow phenomenon can be effectively eliminated and the uniformity of the flow field can be improved;at the same time,the flow field with 32%,34%,38%and 45%aperture ratio is simulated to verify the experimental results.Finally,the best desulfurization efficiency of 99.99%is obtained based on the test results,while the numerical simulation shows that the flow field uniformity corresponding to different opening rates is consistent with the test results,with the opening rate from 32%to 45%and the flow field getting thinner and thinner,and the corresponding desulfurization efficiency in the test is also in a decreasing state.