Optimization Design Of Low-temperature SCR Cyclonic Fluidized Reactor

At present,low-temperature activity of commercial deNOx catalysts have poor stability.The low-temperature flue gas NH3-SCR deNOx process has problems such as high overall energy consumption for heating the flue gas and poor water and sulfur resistance of the catalyst at low temperatures.In this paper,a cyclonic fluidized reactor and process for low-temperature flue gas deNOx are designed.The deNOx process uses catalytic particles as the heat carrier,by regulating the high-temperature catalyst rotation in the reactor,the low-temperature flue gas SCR deNOx heat transfer,mass transfer and reaction processes are enhanced.By setting up a test apparatus,the effects of physical parameters,structural parameters,and operating conditions on the fluidization performance of the cyclonic reactor and the state of particle self-rotation movement in the reactor were studied experimentally.Based on the detection results,numerical simulations were used to investigate the fluid-solid coupling heat transfer law under the control of particle self-rotation.The main conclusions are as follows:(1)The decrease in superficial gas velocity and the increase in particle feed rate increase the bed pressure drop of the cyclonic reactor,and the fluidization degree of bed layer has a V-shaped distribution in height.There is a positive correlation between particle self-rotation speed and superficial gas velocity,the particle self-rotation speed reaches a maximum value of 19,572 rad/s near the top of the inner column of reactor under the superficial gas velocity of 4.58 m/s.After particles are fluidized to the position as twice as the height of inner column,the particle self-rotation speed rapidly drops to 200～1500 rad/s.Self-rotation centrifugal force dominates the desorption of reaction products on the surface and in the pores of catalytic particles.(2)When the direction of particle self-rotation is perpendicular to the direction of inlet gas velocity,temperature uniformity of catalyst surface can be improved.Significant effect can be made as the self-rotation speed reaches 5 rad/s,the temperature uniformity can be increased by 27.1%一 37.7%compared with non-rotating particle after Is,and the uniformity can be increased by a maximum of 49.5%at a self-rotation speed of 500 rad/s.It takes up to 1.46 s,4.78 s,and 7.89 s that the average surface temperature of particles with diameters of 1 mm,3 mm,and 5 mm decreases from 300℃ to 150℃ which is the lowest temperature required for high-efficiency SCR reaction of NOx with NH3.The research results have guiding significance for the feasibility and regulation of low-temperature flue gas deNOx method with thermal catalyst in cyclonic fluidized reactor.