Method for applying two-stage process control technology to automatic combustion of lime kiln

Abstract

The invention relates to the technical field of metallurgical automation control, and particularly discloses a method for applying a two-stage process control technology to automatic combustion of a lime kiln, an automatic combustion control system of the lime kiln comprises data acquisition and two-stage process control, the data acquisition is realized through Kepware, and first-stage PLC data is acquired and stored in a database table; the set value of the secondary process control calculation is stored in the database table and is issued to the primary PLC through the Kepware; the preheater center temperature presetting module controls the center temperature of a preheater by adjusting the opening degree of a coal gas adjusting valve, and the center temperature of the lime kiln preheater is automatically controlled through fuzzy control, case reasoning, a Bang-Bang controller and rule operation. Automatic combustion of the lime kiln is achieved, the kiln temperature, the kiln pressure and the discharging temperature of the lime kiln are accurately controlled within the set range, reasonable matching of pulverized coal, coal gas and air is achieved through case-based reasoning, energy is saved, consumption is reduced, and labor intensity is relieved.

Description

Technical Field

[0001] The present invention relates to the technical field of metallurgical automation control, and particularly relates to a method for applying a secondary process control technology to the automatic combustion of a lime kiln. Background Art

[0002] The lime kiln is only equipped with relatively complete basic automation equipment. The lime kiln calcination process mainly relies on the main control operator to rely on information such as the temperature at the kiln tail, the center temperature of the preheater, and the quality of lime inspection and testing, combined with manual experience to operate the kiln temperature adjustment. The lime kiln uses pulverized coal and converter gas as the calcination fuel for the lime kiln. Due to fluctuations in gas calorific value and gas pipeline network pressure, inconsistent incoming material components, and various factors such as the external environment, it is difficult for the operator to control the kiln temperature and the reasonable ratio of pulverized coal, gas, and air, resulting in energy consumption waste. The operator needs to operate multiple systems such as feeding, preheating, lime kiln, and dust collection, and it is difficult to observe the calcination data in real time. There are problems such as untimely adjustment of furnace temperature, furnace pressure, and the frequencies of the primary and secondary fans, resulting in large fluctuations in furnace temperature, affecting the firing and environmental pollution. In the production process of the lime kiln, it is necessary to ensure both the lime firing quality and increase the output of active lime. Precise control of the calcination temperature is particularly important. Since the lime kiln calcination process is very complex, with characteristics such as non-linearity, time-variation, and large lag, traditional basic automation cannot meet the requirements of automatic combustion control of the lime kiln. Therefore, a method for applying a secondary process control technology to the automatic combustion of a lime kiln is needed to solve the problems of high energy consumption and high labor intensity of manual operation caused by the inability of existing lime kilns to achieve automatic combustion control. Summary of the Invention

[0003] Aiming at the problems existing in the prior art, the purpose of the present invention is to provide a method for applying a secondary process control technology to the automatic combustion of a lime kiln.

[0004] The technical solution adopted by the present invention to solve its technical problems is: A method for applying a secondary process control technology to the automatic combustion of a lime kiln, comprising the following steps:

[0005] S1. The automatic combustion control system of the lime kiln includes data acquisition and secondary process control. The data acquisition collects the data of the primary PLC through Kepware and stores it in the database table, and the set value calculated by the secondary process control is stored in the database table and sent to the primary PLC through Kepware;

[0006] S2. The secondary process control includes a fuzzy control module for the center temperature of the preheater, a pre-setting module for the center temperature of the preheater, a regulation module for the current of the main motor of the kiln, a regulation module for the outlet temperature of the preheater, a pressure control module for the kiln head and kiln tail, and a regulation module for the cooling and discharging temperature;

[0007] S3. The pre - set module for the central temperature of the pre - heater controls the central temperature of the pre - heater by adjusting the opening of the gas regulating valve. It uses fuzzy control, case - based reasoning, Bang - Bang controller, and rule - based operation to automatically control the central temperature of the lime kiln pre - heater.

[0008] Specifically, for the data acquisition in step S1, Kepware is used to collect the data required for the secondary process control in the primary PLC and store it in the oracle database. The set value is calculated and stored in the oracle database through the secondary process control model, and the set value is sent to the primary PLC through the Advanced Tags function in Kepware.

[0009] Specifically, for the data acquisition in step S1, the data interface module, data storage module, and data pre - processing module are used to collect the coal powder consumption, gas flow rate, primary and secondary side fan flow rates, pre - heater temperature, furnace pressure, current of the main kiln motor, and pre - heater outlet temperature.

[0010] Specifically, the fuzzy control module for the central temperature of the pre - heater in step S2 includes fuzzy input and output, fuzzy quantification, and fuzzy rules. The fuzzy input is the deviation e(t) between the set central temperature of the pre - heater and the actual central temperature of the pre - heater, and the change rate ec(t) of the temperature rise deviation of the central temperature of the pre - heater; the fuzzy output is the increment u(dg). The membership functions of each fuzzy variable all adopt triangular membership functions.

[0011] Fuzzy quantification means that the fuzzy controller needs to convert the accurate measured quantity into a linguistic variable of a fuzzy subset. The domain conversion relationship is determined according to the historical firing data of the lime kiln. The fuzzy subsets, domain multipliers, quantization factors, and subset domains of the deviation between the central temperature of the pre - heater and the actual central temperature of the pre - heater, the change rate of the central temperature rise, and the gas increment are designed.

[0012] The fuzzy rule is that when the temperature rise rate of the central temperature of the pre - heater increases and the central temperature of the pre - heater is much higher than the set temperature, the gas is reduced.

[0013] When the temperature rise rate of the central temperature of the pre - heater increases and the central temperature of the pre - heater is lower than and close to the set temperature, the gas is reduced.

[0014] When the temperature rise rate of the central temperature of the pre - heater decreases and the central temperature of the pre - heater is much lower than the set temperature, the gas is increased.

[0015] When the temperature rise rate of the central temperature of the pre - heater decreases and the central temperature of the pre - heater is higher than and close to the set temperature, the gas is increased.

[0016] Specifically, the control module for the current of the main kiln motor in step S2 increases the coal powder and gas consumption to raise the furnace temperature and reduce the current of the main kiln motor.

[0017] Specifically, the preheater outlet temperature control module in step S2 is configured to, when the preheater outlet temperature is higher than the process requirement, increase the temperature of the furnace by reducing the consumption of pulverized coal and gas to lower the preheater outlet temperature.

[0018] Specifically, the kiln head and kiln tail pressure control module in step S2 is configured to, when the pressure at the kiln head of the furnace is higher than the process requirement, reduce the pressure at the kiln head of the furnace by increasing the air volume drawn by the kiln head induced draft fan; when the pressure at the kiln tail of the furnace is higher than the process requirement, reduce the pressure at the kiln tail of the furnace by increasing the air volume discharged by the kiln tail exhaust fan.

[0019] Specifically, the cooling discharge temperature control module in step S2 is configured to, when the cooling discharge temperature is higher than the process requirement, reduce the cooling discharge temperature by increasing the air volume of the secondary side fan.

[0020] Specifically, the fuzzy control in step S3 is such that the fluctuation range of the central temperature of the lime kiln preheater is from 920 °C to 980 °C, the overall change of the central temperature of the lime kiln preheater is stable, and the influence of gas regulation on the furnace temperature has a long lag. Fuzzy control is used for automatic combustion control, adopting a Bang - Bang controller and setting rule operations.

[0021] Specifically, the case - based reasoning in step S3 is that factors such as the pulverized coal composition of the lime kiln, the calorific value and pressure fluctuations of the gas, the frequencies of the primary and secondary side fans, and the errors in calculating the consumption of pulverized coal, gas consumption, and the set frequencies of the primary and secondary side fans through secondary process control will cause changes in the consumption of pulverized coal, gas consumption, and the set frequencies of the primary and secondary side fans. In the case where the theoretical model and domain knowledge are incomplete, imitating manual operation experience, different pusher times are selected within the required range of the central temperature of the preheater, and the parameters of the consumption of pulverized coal, gas consumption, and the set frequencies of the primary and secondary side fans are stored as good cases. When the pusher time changes, the system automatically searches for cases of the consumption of pulverized coal, gas consumption, and the set frequencies of the primary and secondary side fans according to the set pusher time. The similarities of the K cases found are calculated using weighted distance, and finally a set of the best similar cases of the consumption of pulverized coal, gas consumption, and the set frequencies of the primary and secondary side fans is obtained for the consumption of pulverized coal, gas consumption, and the set frequencies of the primary and secondary side fans at the current pusher time. At the same time, the cases continuously select better cases and eliminate inferior cases for self - learning during the implementation process.

[0022] The present invention has the following beneficial effects:

[0023] The method for applying the secondary process control technology designed by the present invention in the automatic combustion of lime kilns adjusts the consumption of pulverized coal, the consumption of gas, the set frequencies of the primary and secondary side fans, and the frequencies of the head and tail fans of the kiln to control the kiln temperature, kiln pressure, and blanking temperature respectively, so as to achieve the automatic combustion of the lime kiln. Through case-based reasoning, a reasonable ratio of pulverized coal, gas, and air is achieved, energy is saved and consumption is reduced, and the labor intensity is alleviated.

[0024] The method for applying the secondary process control technology designed by the present invention in the automatic combustion of lime kilns achieves precise control of the kiln temperature, kiln pressure, and blanking temperature of the lime kiln within the set range, rationally matches the consumption of pulverized coal and gas for different pusher times, reduces fuel consumption, and realizes the automatic combustion of the lime kiln. Brief Description of the Drawings

[0025] Figure 1 It is a framework diagram of the automatic combustion control system of the lime kiln.

[0026] Figure 2 It is a framework diagram of the secondary process control system for the automatic combustion of the lime kiln.

[0027] Figure 3 It is a flow chart of the central temperature control of the preheater.

[0028] Figure 4 It is a framework diagram of the input-output relationship of the kiln main motor current control module.

[0029] Figure 5 It is a framework diagram of the input-output relationship of the preheater outlet temperature control module.

[0030] Figure 6 It is a framework diagram of the input-output relationship of the head and tail furnace chamber pressure control module of the kiln.

[0031] Figure 7 It is a framework diagram of the input-output relationship of the cooler blanking temperature control module.

[0032] Figure 8 It is a functional architecture diagram of data acquisition.

[0033] Figure 9 It is a functional architecture diagram of model control.

[0034] Figure 10 It is a graph of the change in the central temperature of the preheater during manual firing.

[0035] Figure 11 It is a graph of the change in the central temperature of the preheater during automatic firing. Detailed Implementation Modes

[0036] The following will further describe in detail the technical solutions in the embodiments of the present invention in combination with the accompanying drawings in the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0037] As Figures 1 - 3 shown, a non-road mobile machinery access identification and control method based on two-dimensional code, the lime kiln automatic combustion control system includes data acquisition and secondary process control. The data acquisition collects the primary PLC data through Kepware and stores it in the database table, and the set value calculated by the secondary process control is stored in the database table and sent to the primary PLC through Kepware. The secondary process control includes a preheater center temperature fuzzy control module, a preheater center temperature preset module, a kiln main motor current regulation module, a preheater outlet temperature regulation module, a kiln head and tail pressure control module, and a cooling and feeding temperature regulation module. The present invention introduces a secondary process control technology based on fuzzy control and case-based reasoning, which significantly improves the lime kiln furnace temperature control accuracy. On the premise of ensuring the firing quality, it realizes the reasonable ratio of gas, pulverized coal and air, improves the lime firing quality and production efficiency, saves energy costs, and reduces environmental pollution.

[0038] The data acquisition uses Kepware to collect the data required for the secondary process control in the primary PLC and stores it in the oracle database. The set value is stored in the oracle database through the control calculation of the secondary process control model, and the set value is sent to the primary PLC through the Advanced Tags function in Kepware. The data acquisition collects the pulverized coal consumption, gas flow rate, primary and secondary side fan flow rates, preheater temperature, furnace pressure, kiln main motor current, and preheater outlet temperature through the data interface module, data storage module, and data preprocessing module. The system uses the oracle database and uses Kepware6.4 to establish the primary and secondary data transmission and communication. Using the.NET development platform and the Visual Studio 2022 integrated development environment, the monitoring screen and the secondary process control program are written in c# and c++ respectively.

[0039] 1. Basic control module of secondary process control: The preheater center temperature preset module controls the preheater center temperature by adjusting the opening of the gas regulating valve, and automatically controls the preheater center temperature of the lime kiln by using fuzzy control, case-based reasoning, Bang-Bang controller and rule operation.

[0040] 1.1 The preheater center temperature fuzzy control module includes fuzzy input and output, fuzzy quantization and fuzzy rules.

[0041] The fuzzy inputs are the deviation e(t) between the set temperature of the preheater center and the actual temperature of the preheater center, and the rate of change ec(t) of the temperature rise deviation of the preheater center; the fuzzy output is the increment u(dg). The membership functions of each fuzzy variable all adopt triangular membership functions.

[0042] 1.2 Fuzzy quantization.

[0043] The definition of the fuzzy subsets is shown in Table 1:

[0044]

[0045]

[0046] The fuzzy controller needs to convert the accurate measured quantity into the language variable of the fuzzy subset. The domain conversion relationship is determined according to the historical furnace burning data of the lime kiln. Design the fuzzy subsets, domain multipliers, quantization factors, and subset domains of the deviation between the preheater center temperature and the actual temperature of the preheater center, the rate of change of the preheater center temperature rise, and the gas increment. Taking the fuzzy regulation of gas as an example, the specific design is as follows:

[0047]

[0048] 1.3 Fuzzy rules.

[0049] When the temperature rise rate of the preheater center increases and the temperature of the preheater center is much higher than the set temperature, the gas is reduced.

[0050] When the temperature rise rate of the preheater center increases and the temperature of the preheater center is lower than and close to the set temperature, the gas is reduced.

[0051] When the temperature rise rate of the preheater center decreases and the temperature of the preheater center is much lower than the set temperature, the gas is increased.

[0052] When the temperature rise rate of the preheater center decreases and the temperature of the preheater center is higher than and close to the set temperature, the gas is increased.

[0053] 1.4 Fuzzy control of the preheater center temperature.

[0054] In actual application, according to the actual situation on site, the temperature fluctuation range of the preheater center of the lime kiln is from 920°C to 980°C. Then the basic domain of its set deviation e is [-45, +45], and the corresponding quantization domain is E: [-15, 15]. The basic domain of the rate of change of the deviation ec is [-25, +25], and the corresponding quantization domain is E: [-10, 10]. Then the quantization factors Ke and Kec of the error E and the rate of change of the error Ec are initially set as:

[0055] Ke = N / Xe = 15 / 45 = 0.33;

[0056] Kec = N / Xec = 10 / 25 = 0.5;

[0057] The basic domain of the fuzzy increment is [-100, +100], and the corresponding quantization domain is U: [-50, +50]. Then the scale factor of the increment u is initially set as:

[0058] Ku = u / N = 50 / 100 = 0.5;

[0059] The overall change of the central temperature of the lime kiln preheater is relatively stable, and the influence of gas regulation on the furnace temperature has a long lag. Certain rules need to be added for automatic combustion control using fuzzy control:

[0060] Rule 1

[0061] Fuzzy control belongs to computer system control, and a scan cycle needs to be set. The scan cycle depends on the condition of the lime kiln. When the kiln condition is stable, the scan cycle can be a bit longer. In this system, 20 minutes is set as a scan cycle to monitor the central temperature of the preheater. The central temperature of the preheater is divided into three regulation ranges: ±5° to ±10°, ±10° to ±20°, and above ±20°. When the change rate of the central temperature deviation of the preheater exceeds the set limit of its respective change rate in the three different regulation ranges, the furnace temperature is regulated.

[0062] Rule 2

[0063] The system sets 10 minutes as a scan cycle to monitor the outlet temperature of the preheater and the main motor current of the rotary kiln. When the outlet temperature of the preheater is greater than 240 degrees (according to process requirements), the gas is not allowed to be increased; when the main motor current of the rotary kiln exceeds 500 A (according to process requirements), the gas is not allowed to be reduced; when the main motor current of the rotary kiln is lower than 440 A (according to process requirements), the gas is not allowed to be reduced.

[0064] Rule 3

[0065] When the temperature change of the rotary kiln significantly deviates from the set value, there is a lag phenomenon in the control of the central temperature of the preheater. At this time, the response of controlling the furnace temperature with a fuzzy controller is slow. Therefore, a Bang - Bang control is designed to compensate for the fuzzy control, and the maximum or minimum adjustment is given in a timely manner to make the central temperature of the preheater return to the normal range as soon as possible. The output of the Bang - Bang controller is as follows:

[0066]

[0067] In the formula, U BB represents the output of the Bang - Bang controller, e(k) represents the deviation between the set value and the actual value of the central temperature of the preheater, b represents the deviation threshold of the central temperature of the preheater, which is initially determined to be ±25°C; U max is the maximum value of the gas supply; U min is the minimum value of the gas supply.

[0068] 2. Pre - setting the central temperature of the pre - heater based on case - based reasoning.

[0069] 2.1 Case - based reasoning.

[0070] Factors such as the pulverized coal composition in the lime kiln, the calorific value and pressure fluctuations of the gas, the frequencies of the primary - side and secondary - side fans, and the errors in calculating the pulverized coal consumption, gas consumption, and the set frequencies of the primary - side and secondary - side fans through secondary - process control will cause changes in the pulverized coal consumption, gas consumption, and the set frequencies of the primary - side and secondary - side fans. In actual complex production, operators often set the pulverized coal consumption, gas consumption, and the set frequencies of the primary - side and secondary - side fans based on experience to obtain better combustion effects. Case - based reasoning provides a means to learn from past successful cases. In the case of incomplete theoretical models and domain knowledge, it imitates manual operation experience. Select different pusher times within the required range of the pre - heater central temperature, and store the pulverized coal consumption, gas consumption, and the set frequencies of the primary - side and secondary - side fans as good cases. When the pusher time changes, the system automatically searches for cases of pulverized coal consumption, gas consumption, and the set frequencies of the primary - side and secondary - side fans according to the set pusher time. Calculate the similarity of the K cases found using the weighted distance. The formula is as follows:

[0071]

[0072] In the formula:

[0073] C: The current instance;

[0074] Cj: The j - th case in the case base;

[0075] f i： The i - th eigenvalue of the current hot blast stove;

[0076] The i - th operating condition eigenvalue of case Cj;

[0077] ai: The minimum value of the i - th characteristic attribute in the case;

[0078] bi: The maximum value of the i - th characteristic attribute in the case.

[0079] Finally, a set of optimal similar cases of pulverized coal consumption, gas consumption, and the set frequencies of the primary - side and secondary - side fans is obtained for the pulverized coal consumption, gas consumption, and the set frequencies of the primary - side and secondary - side fans at the current pusher time. At the same time, the case continuously selects better cases and eliminates inferior cases during the implementation process for self - learning.

[0080] The case design is shown in Table 2:

[0081]

[0082] The value range of the case input attributes

[0083] Condition attribute Value range Pusher time 38s - 200s Preheater center temperature 900°～1000° Preheater center outlet temperature 200°～260° Kiln tail temperature 550°～700° Colorimetric temperature 1000°～1200° Primary side fan 30 - 45Hz Secondary side fan 26 - 35Hz Rotary kiln motor current 400A - 550A Gas outlet pressure 8 - 14kpa Preheater outlet temperature <260°

[0084] Output attribute

[0085]

[0086] 2.2 Additional rules for case-based reasoning.

[0087] Rule 1

[0088] When the calorific value and pressure of the gas fluctuate, the outlet temperature of the preheater, and the current of the rotary kiln motor exceed the range, in order to prevent excessive adjustment, it is necessary to dynamically set the coal powder consumption, gas consumption, and the set frequencies of the primary and secondary side fans, and set the adjustment range.

[0089] Rule 2

[0090] When manually switching the automatic combustion of the lime kiln or the pusher time changes, the initial coal powder consumption, gas consumption, and the set frequencies of the primary and secondary side fans adopt the set values of case-based reasoning.

[0091] Rule 3

[0092] Setting of the center temperature of the preheater: When the current pusher time changes, the automatic combustion system uses the average center temperature of the preheater in the case library with the same pusher time as the initial set temperature of the preheater center; reduce manual intervention, calculate the coal powder consumption, gas consumption, and the set frequencies of the primary and secondary side fans through case-based reasoning, and in special cases (such as particularly large fluctuations in the calorific value and pressure of the gas), manual temperature setting compensation is required on the automatic combustion interface. The automatic combustion system of the lime kiln adjusts the coal powder consumption, gas consumption, and the set frequencies of the primary and secondary side fans around the initial set temperature of the preheater, the outlet temperature of the preheater center, and the current of the main motor of the rotary kiln and the temperature of the cooler discharge.

[0093] 3. Regulation of the current of the main motor of the kiln.

[0094] When the current of the main motor of the kiln is higher than the process requirements, increase the coal powder and gas consumption to raise the furnace temperature and reduce the current of the main motor of the kiln, and vice versa. The input-output relationship of the current control module of the main motor of the kiln is as Figure 4 shown.

[0095] 4. Regulation of the outlet temperature of the preheater.

[0096] When the outlet temperature of the preheater is higher than the process requirements, reduce the coal powder and gas consumption to raise the furnace temperature and lower the outlet temperature of the preheater, and vice versa. The input-output relationship of the outlet temperature control module of the preheater is as Figure 5 shown.

[0097] 5. Control of the pressure at the head and tail of the furnace hearth.

[0098] When the pressure at the kiln head is higher than the process requirement, the air volume drawn by the induced draft fan at the kiln head is increased to reduce the pressure at the kiln head of the furnace, and vice versa; when the pressure at the kiln tail of the furnace is higher than the process requirement, the air volume discharged by the exhaust fan at the kiln tail is increased to reduce the pressure at the kiln tail of the furnace, and vice versa. The input-output relationship of the pressure control module at the kiln head and kiln tail of the furnace is as Figure 6 shown.

[0099] 6. Control of the discharging temperature of the cooler.

[0100] When the discharging temperature of the cooler is higher than the process requirement, the air volume of the secondary side fan is increased to reduce the discharging temperature of the cooler, and vice versa. The input-output relationship of the discharging temperature control module of the cooler is as Figure 7 shown.

[0101] The program of the model control system is divided into two functional modules: one is data acquisition ShyDataAQ, and the other is model control ShySU. Its program function architecture is as Figure 8 and Figure 9 shown.

[0102] Through fuzzy control, case-based reasoning and additional rules, the automatic combustion control of the lime kiln is stable, reducing manual intervention. The automatic furnace burning is more stable than manual furnace burning and has a higher control accuracy. The manual control of the preheating center temperature before and after improvement is as Figure 10 and Figure 11 shown.

[0103] Since the secondary process control has been applied to the automatic combustion of Lime Kiln No. 4 in Phase 4 of a steel plant since August 2024, under various production rhythms, the furnace temperature is controlled within the range of ±20°, the temperature at the outlet of the preheater is below 240 degrees, the current of the rotary kiln motor is below 450 - 500, the coal powder consumption, gas consumption, and the frequencies of the primary and secondary side fans are adjusted smoothly, the calcination is stable, and the qualified rate of firing reaches 84%, meeting the production requirements.

[0104] The present invention is not limited to the above embodiments. Anyone should know that structural changes made under the inspiration of the present invention, as long as they have the same or similar technical solutions as the present invention, shall fall within the protection scope of the present invention.

[0105] The technologies, shapes, and structures not described in detail in the present invention are all well-known technologies.

Claims

1. A method for applying a secondary process control technology in the automatic combustion of a lime kiln, characterized in that, It includes the following steps: S1. The automatic combustion control system of the lime kiln includes data acquisition and secondary process control. The data acquisition collects the data of the primary PLC through Kepware and stores it in the database table, and the set value calculated by the secondary process control is stored in the database table and sent to the primary PLC through Kepware. S2. The secondary process control includes a preheater center temperature fuzzy control module, a preheater center temperature preset module, a kiln main motor current regulation module, a preheater outlet temperature regulation module, a kiln head and kiln tail pressure control module, and a cooling and discharging temperature regulation module. S3. The preheater center temperature preset module controls the preheater center temperature by adjusting the opening of the gas regulating valve, and uses fuzzy control, case-based reasoning, Bang-Bang controller and rule operation to automatically control the preheater center temperature of the lime kiln.

2. The method for applying the secondary process control technology in the automatic combustion of a lime kiln according to claim 1, characterized in that, In the data acquisition in step S1, Kepware is used to collect the data required for the secondary process control in the primary PLC and store it in the oracle database. The set value is stored in the oracle database through the control calculation of the secondary process control model, and the set value is sent to the primary PLC through the Advanced Tags function in Kepware.

3. The method for applying the secondary process control technology in the automatic combustion of a lime kiln according to claim 1, characterized in that, The data acquisition in step S1 collects the coal powder consumption, gas flow rate, primary and secondary side fan flow rates, preheater temperature, furnace pressure, kiln main motor current, and preheater outlet temperature through a data interface module, a data storage module, and a data preprocessing module.

4. The method for applying the secondary process control technology in the automatic combustion of a lime kiln according to claim 1, characterized in that, The preheater center temperature fuzzy control module in step S2 includes fuzzy input and output, fuzzy quantization, and fuzzy rules. The fuzzy input is the deviation e(t) between the preheater center temperature setting and the actual preheater center temperature and the change rate ec(t) of the preheater center temperature rise; the fuzzy output is the increment u(dg), and the membership function of each fuzzy variable adopts a triangular membership function. Fuzzy quantization means that the fuzzy controller needs to convert the accurate measured quantity into a linguistic variable of a fuzzy subset. The domain conversion relationship is determined according to the historical firing data of the lime kiln. Design the fuzzy subset, domain multiplier, quantization factor, and subset domain of the deviation between the preheater center temperature and the actual preheater center temperature, the preheater center temperature rise change rate, and the gas increment. The fuzzy rule is that when the preheater center temperature rise rate increases and the preheater center temperature is much higher than the set temperature, reduce the gas. When the preheater center temperature rise rate increases and the preheater center temperature is lower than and close to the set temperature, reduce the gas. When the preheater center temperature rise rate decreases and the preheater center temperature is much lower than the set temperature, increase the gas. When the preheater center temperature rise rate decreases and the preheater center temperature is higher than and close to the set temperature, increase the gas.

5. The method for applying the secondary process control technology in the automatic combustion of a lime kiln according to claim 1, characterized in that, The kiln main motor current regulation module in step S2 increases the coal powder and gas consumption to increase the furnace temperature and reduce the kiln main motor current.

6. The method for applying the secondary process control technology in the automatic combustion of a lime kiln according to claim 1, characterized in that, The preheater outlet temperature regulation module in step S2 is that when the preheater outlet temperature is higher than the process requirement, reduce the coal powder and gas consumption to increase the furnace temperature and reduce the preheater outlet temperature.

7. The method for applying the secondary process control technology in the automatic combustion of a lime kiln according to claim 1, characterized in that, The pressure control module at the kiln head and tail in step S2 is as follows: when the pressure at the kiln head of the furnace is higher than the process requirement, the air volume drawn by the induced draft fan at the kiln head is increased to reduce the pressure at the kiln head of the furnace; when the pressure at the kiln tail of the furnace is higher than the process requirement, the air volume discharged by the exhaust fan at the kiln tail is increased to reduce the pressure at the kiln tail of the furnace.

8. The method for applying the secondary process control technology in the automatic combustion of a lime kiln according to claim 1, characterized in that, The cooling and discharging temperature regulation module in step S2 is as follows: when the discharging temperature of the cooler is higher than the process requirement, the air volume of the secondary side fan is increased to reduce the discharging temperature of the cooler.

9. The method for applying the secondary process control technology in the automatic combustion of a lime kiln according to claim 1, characterized in that, The fuzzy control in step S3 is that the fluctuation range of the central temperature of the lime kiln preheater is from 920 °C to 980 °C, the overall change of the central temperature of the lime kiln preheater is stable, and the influence of gas regulation on the furnace temperature has a long lag. The Bang-Bang controller is used for automatic combustion control with fuzzy control and the rule operation is set.

10. The method for applying the secondary process control technology in the automatic combustion of a lime kiln according to claim 1, characterized in that, The case-based reasoning in step S3 is that factors such as the pulverized coal composition of the lime kiln, the calorific value and pressure fluctuation of the gas, the frequencies of the primary side and secondary side fans, and the errors in calculating the pulverized coal consumption, gas consumption, and the set frequencies of the primary side and secondary side fans through the secondary process control will cause changes in the pulverized coal consumption, gas consumption, and the set frequencies of the primary side and secondary side fans. In the case of incomplete theoretical models and domain knowledge, the manual operation experience is imitated. Different pusher times are selected within the required range of the central temperature of the preheater, and the parameters of the pulverized coal consumption, gas consumption, and the set frequencies of the primary side and secondary side fans are stored as good cases. When the pusher time changes, the system automatically searches for cases of pulverized coal consumption, gas consumption, and the set frequencies of the primary side and secondary side fans according to the set pusher time. The similarity of the K cases found is calculated using the weighted distance. Finally, a set of optimal similar cases of pulverized coal consumption, gas consumption, and the set frequencies of the primary side and secondary side fans is obtained for the current pusher time. At the same time, the system continuously selects better cases and eliminates inferior cases for self-learning during the implementation process.

Images