| In recent decades,My country cement production and consumption has been ranked first in the world,accounting for about 60% of the world’s total.Cement,electricity,heat production and other combustion-related industries are the main sources of NOx emissions.my country is paying more and more attention to the control of NOx.Selective catalytic reduction(SCR)technology is widely used due to its high denitrification efficiency.However,SCR technology is mostly concentrated in industries such as thermal power generation.With the emission of nitrogen oxides in the cement industry The standards have become stricter year by year,speeding up the research of selective reductive catalytic reduction(SCR)technology.This paper takes the SCR denitrification pilot system of a cement production line as the research object,combined with the relevant flue gas data of the cement plant,the distance of the rectifying grid at the entrance of the reactor,the height of the rectifying grid,the position of the rectifying grid,the number of baffles,and the angle of the baffles.Numerical simulation research is carried out on the influence of the uniformity of the flue gas field.The results show that the maximum incident angle is less than 90° and the eddy current above the catalyst disappears from the non-rectifying grid to the rectifying grid;when the rectifying grid spacing is 107 mm,the rectifying grid height is 200 mm,the rectifying position and the inlet When the bottom edge is flat,the relative standard deviation of the velocity at 100 mm of the upper layer of the first layer of catalyst is reduced to 19%;when the number of baffles is 7 and the angle of the baffle is 18.2°,it is most suitable.At this time,above the first layer of catalyst The relative standard deviation of the velocity at 100 mm is 11.91%,and the maximum incident angle is 3.14°.And under the best parameters,the flue gas with different components in a single gas phase,different loads were verified,and the different loads under the conditions of DPM dual-phase coupling were verified,and they all met the requirements.In order to obtain the characteristic parameters of the particles,the particle size of the ash sample was measured by the particle size distribution tester,and the ash sample was analyzed by crystal phase analysis and element composition analysis using X-ray diffractometer(XRD)and X-ray fluorescence spectrometer(XRF).According to the measured particle parameters,DPM dual-phase coupling,particle-wall collision model and user-defined function are used to compile particle collision source files,and particle numerical simulations are carried out on particles using Rosin-Rammler distribution conditions.Comparing with the results of a single gas phase simulation,it is found that the average velocity at 100 mm above the first layer of catalyst has a certain increase,the velocity standard deviation has a small change,and the velocity relative standard deviation is correspondingly reduced.Aiming at the problem of ash accumulation at the bottom of the selective reductive catalytic reduction(SCR)denitrification reactor of cement kilns,the discrete phase(DPM)model model,velocity deposition criterion,and user-defined functions are used to compile the source files of velocity deposition,and the SCR denitrification is analyzed by numerical simulation.The ash accumulation at the bottom of the reactor.In order to improve the ash accumulation at the bottom,a reactor structure with loose wind was designed,and the angle and number of loose wind inlets were optimized and analyzed.The results show that when the loose wind angle is 45°,the dust content of the flue gas basically tends to be the smallest.When three loose winds are used,the deposition rate of the bottom,wall surface(except the bottom surface)and the wall surface of the pipe is basically close.As the number continues to increase,the decrease in deposition rate is smaller. |
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