Numerical Simulations Of NO_x Formation And Optimization Of Sncr Denitration Technology In Precalciner Of Cement Industry

With the development of air pollution prevention and control work in China,and the gradual stringent NO_x emission standards of the cement industry,decreasing the concentration of NO_x has become one of the necessary conditions for sustainable development of the cement industry.In this paper,using the method of computational fluid dynamics to simulate the 4000t·d^-1 TTF precalciner of Hebei Cement Companyby standard k-?model,DPM model,random orbit model,P1 radiation model,component transmission model NO formation and SNCR denitrification.The cold simulation of the precalciner shows:There are three spout zones and four reflow zones in the precalciner.The spout zones are respectively in the tertiary air and the kiln flue gas meeting,the lower part of the necking and the upper necking,and the reflow zones are respectively in the vicinity of the pyramidal wall of the lower part of theprecalciner and the above the tertiary air inlet.The thermal simulation of the precalciner shows:The temperature of the precalciner is 1025¹300K,there are two high temperature zones and one low temperature zone.Pulverized coal combustion and raw material decomposition are mainly concentrated in the lower part of the lower part of the cylinder and the lower part of the middle cylinder.The lower part of the decomposition content of NO in the decomposition furnace is650mg·m^-3,and the content of pulverized coal is larger.The upper part of the decomposition furnace is basically the same and the distribution is uniform.The effects of three single factors on the distribution and removal rate of NO in spray ammonia position,spray angle and ammonia content were obtained:The effect of sprayed ammonia on the distribution and removal rate of NO in the precalciner was significant,and the NO removal rate was the highest when the sprayed ammonia position was at the bottom of the upper column.The effect of spray angle on the distribution and removal rate of NO in the decomposition furnace is very small.The amount of ammonia used in the precalciner NO content and removal rate is large,when the ammonia dosage was0.015⁰.020kg·s^-1,NO removal rate increases with the increase of ammonia consumption.The response surface method was used to study the interaction between the ammonia injection?X₁?,the ammonia injection angle?X₂?and the amount of ammonia?X₃?on the NO content at the outlet of the calciner.The second order response surface model was obtained and could be used in the predictionNO content of exports.