| The coking industry plays an important role in the economic development of our country.The traditional coking technology has reached a high level in the furnace structure and environmental protection facilities.However,the progress of the society makes the coking industry still a high energy consumption and serious pollution industry.Therefore,coking enterprises will target heat recovery coke ovens with clean coal conversion technology.In the early days,people obtained the parameters of the furnace through experiments and actual measurements,which consumed a lot of manpower and material resources.In recent years,with the development of computer technology,numerical simulation technology has been widely used in the study of the characteristics of coke oven thermal conditions due to its high efficiency,fast speed and low energy consumption.In this thesis,a new type of heat recovery coke oven in a factory is taken as the research object,and the three-dimensional geometric structure of the simplified carbonization chamber is established.The diffusion characteristics of volatiles from Mazhen coal(MZ)in the furnace were obtained by coupling the chemical infiltration devolatilization(CPD)model with the porous medium model.According to the release amount of volatile matter,the steady-state simulation calculation process is divided into five intervals.By analyzing the changes of flow field and temperature field,the influence of volatile matter release law on the stability of carbonization indoor working conditions and the burning loss of coal cake is studied.The results show that when the equivalence ratio of volatile release to air volume is close to 1,the main combustion reaction area moves from the lower part of the carbonization chamber to the middle part,and the high temperature range on the surface of the coal cake is reduced,thereby reducing the burning loss on the surface of the coal cake.In addition,the full combustion of volatiles makes the furnace temperature higher,which can accelerate the coking rate of coal cake.When the bulk density is 1100 kg/m~3and the air inlet velocity is 13.3 m/s,the temperature distribution on the surface of the coal cake is more uniform.The carbonization chamber has a better temperature gradient and a larger high temperature area,which is beneficial to shorten the time of coke maturation and improve the efficiency and quality of coke production.The simulation results of 60 h complete coking cycle transient working condition show that when the reaction is carried out for 15 h,the release of volatile matter rarely leads to weak combustion reaction.When the reaction is carried out for 30 h,the main temperature range of the surface of the coal cake is 1200K～1400K,which is conducive to accelerating the rate of coke maturity.The surface temperature distribution of the coal cake at 45 h and 60 h is lower than the maturity temperature range of the coke,so it is not conducive to the maturity of the coke.In order to explore the calculation accuracy of CPD model applied to the numerical simulation of heat recovery coke oven and the influence of coal type on the thermal conditions in the furnace,three kinds of coking coal(Jielizhang JLZ,Mazhen MZ,Luogen LG)were selected for pyrolysis experiments,and the simulation results were compared and analyzed.The results show that the experimental results of MZ coal pyrolysis and the calculation results of CPD model have the same change trend in the law of volatile release.When applied to numerical simulation,the calculation results of the two also have high similarity.Comparing the temperature field of the three coal samples in the heat recovery coke oven and the temperature distribution along the X axis,the results show that the MZ coal has a higher temperature range in the carbonization chamber,and the temperature gradient on the surface of the coal cake is more uniform,which can not only improve the quality of coke maturity,but also improve the efficiency of coke maturity. |
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