Research On Coordinated Control Of Cement Raw Material Decomposition And Denitrification Process

In the process of cement production,the decomposition furnace is the main place for the decomposition of raw cement.It has the mission to make the raw cement achieve the decomposition rate required by the process before entering the rotary kiln.At the same time,the coal consumption of the decomposition furnace accounts for about 60%,the NOx produced accounts for about 60%of the total NOx.In order to reduce the NOx emission concentration,keeping up with the country’s increasingly strict environmental protection standards,the entire cement production industry is facing pressure to reduce emissions.If reducing the NOx concentration only through the denitration link will not only cause an increase in the cost of energy consumption of the enterprise,but also a larger amount of ammonia water injected into the decomposition furnace will also reduce the temperature of the decomposition furnace to a certain extent,and affect the stable control of the decomposition furnace temperature.To make the NOx concentration in the cement production process meet the environmental protection requirements and the amount of ammonia used is small,need to start from the source of NOx generation,that is,reduce the temperature of the decomposition furnace to reduce the production of fuel-type NOx,but blindly reducing the temperature of the decomposition furnace will cause the decomposition rate of the material into the kiln cannot meet the technological requirements.Therefore,it is necessary to coordinate and optimize the two links through the idea of coordinated control.In this project,through the coordinated control of the raw meal decomposition and denitration process in the cement production process,it is beneficial to make the decomposition furnace in a state of optimal control,which can not only reduce the generation of NO_X to a certain extent at the source,but also make the temperature of the decomposition furnace outlet more stable;comprehensive consideration of the changes in the real-time working conditions of the calciner makes the denitration process also run in the state of optimal control,and finally make the two links reach the optimal state,and promote the realization of energy saving and consumption reduction goals of enterprises.The main research results are as follows:(1)In-depth analysis of the process of cement raw meal decomposition and denitrification process,on this basis,further analyzed the necessity of coordinated control between the two and the control difficulties in coordinated control.Based on the idea of coordinated control,the optimal control for the decomposition of raw meal first selects the fineness of raw meal,the three rate value is the same,the lower decomposition furnace temperature corresponding to the higher decomposition rate is used as the data for modeling the pre-set decomposition furnace temperature model the generalized regression neural network(GRNN)established a preset model of the decomposition furnace temperature,and then selected ammonia flow feedback,F-CaO,decomposition furnace outlet temperature feedback in the denitration process based on the actual situation on site and the experience of excellent operators.Variables such as secondary air temperature and kiln current are given the setpoint compensation value of the decomposition furnace temperature through expert rules,which is added to the temperature preset value calculated by the GRNN neural network to obtain the optimized setpoint value of the decomposition furnace temperature,which is to ensure the decomposition of raw meal under the premise that the rate is qualified,the temperature set point of the calciner with less NO_X is optimized,and this set point is used as the target value of the calciner temperature automatic control system.The decomposition furnace temperature automatic control system is composed,and through the data collected from the field,the decomposition furnace coal injection and the decomposition furnace outlet temperature are established,and a fuzzy PID controller determines the control parameters simulation.(2)For the optimal control of the denitration process,firstly,according to the actual situation on site,combined with the excellent operator’s time operation experience,the variables such as the temperature feedback of the calciner outlet,the coal injection amount of the calciner,the CO content and the NO_X concentration feedback are selected through the expert rules the optimized set value of NO_X concentration is used as the target value of automatic control in the denitration process,and then the typical working conditions in the denitration process are selected for model identification,and the relationship model between ammonia flow and NO_X concentration in the denitration process is obtained.Finally,the denitration prediction control is determined The parameters of the controller were designed for the denitration prediction controller,and the simulation verification of the controller was completed using MATLAB.(3)Based on the.Net development platform,the C#programming language was used to complete the development of the coordinated control system,and the software debugging and practical application were completed in the cement plant.After a week of software operation,the research plan through the use of coordinated control was found.On the premise that the quality of the cement meets the requirements of environmental protection,it can save about 1.3tons of ammonia per day,reduce the company’s investment in environmental protection,and promote the company to a further step toward the goal of energy saving.