Coke oven coking process management system

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　　The No. 7 and No. 8 coke ovens of Wuhan Iron and Steel Group Coking Co., Ltd. are both JN60 six-meter large-volume coke ovens with an annual output of 1.1 million tons of total coke. The equipment of these two coke ovens has a high degree of automation.: Coke oven machinery PLC unit automatic control system, switch PLC control system, three-vehicle interlocking positioning system, instrument control DCS system, these basic automation systems have improved the level of automation equipment of coke ovens ； However, because they are independent of each other, production data sharing and unified management cannot be achieved, and comprehensive optimization control of the coking process cannot be achieved. CADWATER.COM 　　The coke oven coking process management system (CPMS for short) performs real-time analysis and processing of coke oven production data to achieve stable and even heating of the coke oven, to achieve the purpose of improving the automatic control level of the coke oven, realizing automatic control of the heating system, stabilizing and improving coke quality, reducing energy consumption and extending the life of the coke oven. Since the 1970s, all major steel-producing countries in the world have used computers to control and manage coke oven production. Japan, Finland, Germany, South Korea, etc. * * All have been developed and implemented on coke ovens. The coke oven coking process control system has become an important symbol of coke oven modernization. WWW.CADWATER.COM 　　Wuhan Iron and Steel Co., Ltd. adopted a cooperative development method to introduce the coking process management system of Wuhan Iron and Steel Co., Ltd. No. 7 and No. 8 coke ovens from Voestalpine Finland Co., Ltd., which has international first-class standards and is the first in China to manage the entire process of coke oven production. It passed the acceptance assessment on July 16, 2004. CADWATER.COM 　　The foreign parts completed by Aussteel Finland were mainly: Manual planning model, dynamic planning model, temperature evaluation model, heating control model, human-machine interface ； The domestic part completed by Wuhan Iron and Steel Co., Ltd. is mainly: Instruments, instrument-controlled DCS system, portable infrared vertical fire channel temperature measuring instrument, automatic coke cake temperature measurement device for coke guide car, calorific value analyzer of machine side and coke side heating gas, exhaust gas oxygen content analyzer, waste gas temperature measurement device, heating gas temperature measurement device, exhaust gas temperature measurement device, switch PLC control system, coke oven machinery PLC control system, process control computer system, data communication software and data preprocessing program. CADWATER.COM 　　1. System composition of the coking process management system of Wuhan Iron and Steel Coke Oven No. 7 and No. 8: CADWATER.COM 　　The CPMS system carries out data communication with basic automation systems such as the three-vehicle interlocking system, the instrument control DCS system, and the switch PLC control system through communication application software, collects the production process data of No. 7 and 8 coke ovens, and processes it into the data required by the system through the data preprocessing program. Application software (including process models) performs real-time analysis, processing and reporting of coking process data ； Its heating control model calculates the "stop heating time" of the next exchange in each exchange cycle, transmits it to the coke oven switch PLC control system through communication software, and closes the loop to control the heating time during coke oven gas exchange. ； At the same time, the coking process conditions are displayed on the human-machine interface screen in the form of trend charts and other forms for operators to monitor the process. The control principle diagram of the CPMS system is shown in Figure 1, and the system structure diagram is shown in Figure 2. CADWATER.COM 　　The CPMS system includes the following parts: WWW.CADWATER.COM 　　1.1. On-site testing instruments CADWATER.COM 　　Straight line temperature, horizontal wall temperature, waste gas temperature, coke cake temperature, calorific value meter, exhaust gas oxygen content detection instrument, etc. CADWATER.COM 　　1.2. Basic automation system CADWATER.COM 　　Instrument control DCS system, switch PLC control system, three-vehicle chain positioning system, on-board PLC control system CADWATER.COM 　　1.3. Process computer system WWW.CADWATER.COM 　　1.4. Data communication CADWATER.COM 　　1.5. Data communication between process computer system and basic automation system. WWW.CADWATER.COM 　　1.6. Application software WWW.CADWATER.COM 　　Manual planning model, dynamic planning model, temperature evaluation model, heating control model, human-machine interface. WWW.CADWATER.COM 1.6.1. Manual planning model WWW.CADWATER.COM 　　The manual planning model is mainly based on the coal leveling and coke pushing time of each carbonization chamber. Factors that affect it include: Planned coking time, minimum time gap for continuous coke pushing, coke pushing sequence, number of coke pushing holes, coke oven maintenance time and operation interruption time, and messy carbonization chamber. WWW.CADWATER.COM 　　Wuhan Iron and Steel Coke Ovens No. 7 and 8 are produced in a 5-2 series sequence. The use of manual planning models when preparing coal loading and coke pushing plans allows operators to have time to perform equipment maintenance, so as to minimize the interference of maintenance time on the heating stability of the coke ovens. CADWATER.COM 　　1.6.2. Dynamic planning model CADWATER.COM 　　Based on the actual production situation of the coke oven group, the dynamic planning model analyzes and judges the coke maturity status of each carbonization chamber of the coke oven, calculates the next carbonization chamber number and coke pushing time, and transmits it to the operator on the coke pushing car to guide the operator in production. At the same time, the dynamic planning model is also the basis of the heating control model. WWW.CADWATER.COM 　　1.6.3. Temperature evaluation model CADWATER.COM 　　The temperature evaluation model measures the coke oven vertical fire channel temperature, coke cake temperature, and raw gas temperature through online detection instruments and manual measuring instruments, and provides this real-time information to operators through special screens and reports. Its main function is to help form a basis for manual heating control of the furnace group. WWW.CADWATER.COM 　　The temperature evaluation model consists of three software applications, which involve the following temperature: WWW.CADWATER.COM 　　 1.6.3.1 , straight line temperature, cross wall temperature ； It is measured by a portable infrared thermometer and the measured temperature is corrected to the temperature value at the same time. CADWATER.COM 　　 1.6.3.2 , coke cake temperature ； It is automatically measured online by a two-color infrared thermometer installed on the focus guide car. CADWATER.COM 　　The coke cake temperature measured during coke pushing can obtain secondary information about the coke cake temperature distribution and the temperature distribution on the transverse wall, thereby understanding the heating status of the carbonization chamber in the vertical and horizontal directions. Coke cake temperature data are also used in the coke oven heating control model. CADWATER.COM 　　 1.6.3.3 , raw gas temperature: The raw gas temperature is measured online at the riser tube of the coke oven to predict the end time of carbonization, and the equal time to start coal loading is obtained from the dynamic planning model. Each coke oven is equipped with temperature measuring thermocouples on 5 to 15 rising tubes. CADWATER.COM 　　1.6.4. Heating control model WWW.CADWATER.COM 　　Through the coke oven heating control model, CPMS effectively controls the coke oven heating, optimizes the control of the coking heating process, and optimizes the coke oven heat input to achieve energy saving effects. Use the set value of "exchange stop heating time" to adjust the coke oven heating input value to mature the coke cake within the coking time. WWW.CADWATER.COM 　　Coke oven heating control model includes: Integrated feedforward, feedback control and fuzzy logic control functions. That is, it consists of a combination of feedforward and feedback control. WWW.CADWATER.COM 　　The heating control model includes a dynamic planning model and a predictive energy model as feedforward controllers ； The coking index control model serves as a feedback controller ； The purpose of a fuzzy logic controller is to provide intelligent fine-tuning of the system. CADWATER.COM 　　Feedforward control: In principle, the predictive energy model of feedforward control is calculated based on the heat balance of the heat source and coal during the carbonization process, and also takes into account the loss of heat. The main parameters for calculation include the amount of coal loaded, the moisture content of the coal, the volatile matter of the coal, the flow rate of the heating gas, and the calorific value. The current coking time is known from a dynamic planning model, which calculates the energy demand setpoint based on the thermalization function. The calculated result is used as the set value of the heating stop time for each exchange. CADWATER.COM 　　Feedback control: The feedback control function is to correct the predicted energy demand according to the requirements of the coking index control model. The coking index (CI) is based on the coking time (T coking) function of the dynamic plan and the same time (t Tmax) of the maximum temperature of the waste gas in the riser (Tmax), and the following formula is obtained WWW.CADWATER.COM 　　CI=T coking/ t Tmax CADWATER.COM 　　The function of the coking index control model is to control the coalification process based on the calculated index and coking temperature. After each exchange, the coking index control model corrects the predicted energy demand based on the coking index. The setting of the coking index depends on the set coke cake temperature target value. CADWATER.COM 　　The coking index controller provides predicted coke cake temperature approximately 3 hours before coke push. If the coking index is not within the lower limit and upper limit, the controller will adjust it. WWW.CADWATER.COM 　　CPMS calculates the set value of energy demand for each exchange cycle (30 minutes) in feedforward control, calculates the intermediate heating stop time for the next exchange, and transmits it to the coke oven switch PLC through communication software, and is executed by the switch PLC control system. Thus, the control of the coking heating process can be optimized. WWW.CADWATER.COM 　　2. System application effect CADWATER.COM 　　Since the CPMS system was put into operation, the operation has been stable, the coke oven has been heated evenly, and the following objectives have been achieved. WWW.CADWATER.COM 　　2.1. Digitalization of coke oven management CADWATER.COM 　　The main control parameters in the coking production process can be displayed in real time on the computer interface, such as straight line temperature, cross wall temperature, coke cake temperature, riser gas temperature, gas flow, pressure, gas calorific value, coal weight, moisture, volatile matter, flue suction, exhaust gas temperature, exhaust gas oxygen content, preparation of operation plans, etc. These data can not only be used by operators to judge the production situation, but also can be processed in time if there are any deviations from the heating system and process regulations. ； Moreover, managers in workshops and factories can also understand the coke oven production status on the screen in a timely manner and achieve remote monitoring, which improves the management level of coke oven production. WWW.CADWATER.COM 　　The operation time of coke pushing and coal loading can be controlled more accurately within ±5 minutes, the coke pushing current can be truly recorded, and the straight and horizontal wall temperatures can be measured and recorded more accurately. The riser gas temperature, exhaust gas temperature and oxygen content in the exhaust gas, as well as the flow, pressure and calorific value of the heating gas are all tested online. These data during the production process can be understood at any time. The online detection of the coke cake temperature can not only understand the maturity of the released coke in time, but also analyze the temperature distribution of the cross wall of the carbonization chamber. WWW.CADWATER.COM 　　2.2. Realize intelligent control of coke oven heating CADWATER.COM 　　During the coking production process, factors such as weather changes, fluctuations in the moisture content of the coal, fluctuations in the pressure of the heating gas main pipe, fluctuations in the calorific value of the gas, and fluctuations in coking time will all affect the heating energy demand of the coke oven. CADWATER.COM 　　The CPMS system applies a temperature evaluation model and a heating control model to calculate the average energy demand of each exchange cycle based on the energy demand of the coke oven in the coking cycle. The coking index control model also corrects the predicted energy demand, calculates the heating stop time required for each exchange, and realizes intelligent control of coke oven heating. From the heating stop time calculated by the system for each exchange, it can be judged whether the set heating gas flow rate is appropriate. If the heating stop time is too long, it means that the heating gas supply is excessive. ； If the heating stop time is close to 0 for a long time, it means there is insufficient heating gas. CADWATER.COM 　　2.3. Stabilize and improve coke quality CADWATER.COM 　　In traditional coking management, once the heating system is established, it is generally not easily changed. Due to insufficient coal loading, fluctuations in coal moisture, gas pressure fluctuations, weather changes, and individual furnace numbers extending or shortening the coking time for some reason, etc., all will have a certain impact on coke maturity. WWW.CADWATER.COM 　　After adopting the heating control model, various parameters of the furnace group can be measured in real time to achieve: WWW.CADWATER.COM 　　2.3.1. Keep the heating of the furnace group in a balanced state, so that the heat demand and energy supply of the furnace group are basically balanced. CADWATER.COM 　　2.3.2. The heat supply of the combustion chamber may be inconsistent or the heat supply of the furnace group may fluctuate during a certain period of time. The dynamic scheduling model and heating control model can gradually make the heating situation of the entire furnace group consistent. WWW.CADWATER.COM 　　2.3.3. If there is a large deviation between the various measured parameters and the parameters specified in the heating system and procedures, the operator will be prompted to check the cause and deal with it in time. CADWATER.COM 　　Therefore, after adopting the CPMS control system, the coke oven temperature is stable and uniform, and the produced coke can avoid coking and overcooking. The quality of coke can be improved. WWW.CADWATER.COM 　　2.4. Extend the life of coke oven WWW.CADWATER.COM 　　The oven temperature of the coke oven group is uniform and stable, and the coke cake is in good maturity. ； Coke oven operating procedures are controlled and the coke pushing plan is strictly implemented. When pushing the coke, the coke cake will be pushed out smoothly, there will be no difficulty in pushing the coke, and the temperature of the furnace wall will not be too high or too low. Thereby extending the life of the coke oven body. CADWATER.COM 　　2.5. Energy saving and consumption reduction WWW.CADWATER.COM 　　The control system of CPMS adopts feedforward and feedback model control on the heat demand in the coking process based on the traditional heating system. Each exchange stops heating for a period of time according to the calculated "stop heating time" to achieve a basic balance between heat demand and heat supply, thereby achieving energy saving effects. CADWATER.COM 　　In July and August of 2004, the monthly average intermittent heating time calculated by the heating control model for No. 7 and No. 8 coke ovens was 108 S. ； maximum: 260 S, min.: 38.7 S. .The actual monthly average time to stop heating is 47.6S ； WWW.CADWATER.COM 　　3. Conclusion CADWATER.COM 　　CPMS improves the level of automated management of coke ovens, improves the operation control mode, and realizes intelligent control of coke ovens. Upgrade from manual heating control to automatic closed-loop control, and upgrade the coke oven control and management level from basic automation control to coking process management control. CADWATER.COM 　　It has a significant energy saving effect, and the gas consumption is reduced by 2%. CADWATER.COM 　　The furnace temperature is uniform and stable, achieving a balance between heat demand and heat supply, stabilizing and improving coke quality, and extending the service life of the coke oven. The coke oven operation is programmed and easy to operate, which reduces labor intensity and improves labor productivity.