A method and system for optimizing the production capacity of a coal mill

Abstract

The application provides a coal mill capacity optimization control method and system, which adopts a three-stage progressive control architecture, including: first-stage safety protection control, which stops PID regulation and executes over-temperature protection when the inlet temperature exceeds the preset upper safety limit; second-stage temperature stabilization control, which dynamically adjusts the coal supply amount according to the outlet temperature deviation to stabilize the outlet temperature in the qualified interval; and third-stage capacity optimization control, which synchronously corrects the inlet temperature set value and the coal supply amount according to whether the outlet negative pressure is higher or lower than the preset negative pressure interval after the outlet temperature is stabilized. The application solves the problem that the parallel regulation of multiple parameters in the prior art easily leads to system oscillation by triggering the interlocking of each stage of control, and adopts a reverse temperature rising strategy in the low negative pressure interval, so that the maximum capacity can be quickly restored under abnormal working conditions, and the capacity efficiency of the coal mill equipment is fully utilized.

Description

Technical Field

[0001] This invention relates to the field of iron and steel metallurgy technology, specifically to a method and system for optimizing and controlling the production capacity of a coal mill. Background Technology

[0002] The coal mill is the core grinding equipment for pulverized coal preparation in the blast furnace pulverized coal injection system. It has the characteristic of simultaneously drying and grinding raw coal. The output of the coal mill directly determines the stability of subsequent blast furnace injection. Therefore, the automatic control of the coal mill has always been a research focus in this field. There are many factors affecting the output of the coal mill, including the inlet temperature, outlet temperature, outlet negative pressure, loading force, main exhaust fan volume, raw coal grindability, and coal feed rate.

[0003] Currently, some automatic control methods have been applied to coal pulverizing systems of coal mills. For example, multi-loop parallel control methods are used to control the coal mill load, inlet negative pressure, and outlet temperature separately, as well as multivariable inference predictive control methods. However, although the above automatic control methods can take into account the controllability of some parameters, under abnormal operating conditions (such as a sudden deterioration in the grindability of raw coal leading to coal accumulation inside the coal mill and a sharp change in outlet negative pressure), the coal mill takes a long time to recover from the abnormal state to its maximum capacity, and cannot fully utilize the capacity efficiency of the coal mill equipment.

[0004] The purpose of this invention is to provide a method and system for optimizing and controlling the production capacity of a coal mill, so as to solve the problems mentioned in the background art. Summary of the Invention

[0005] To achieve the above objectives, the present invention provides a method for optimizing and controlling the production capacity of a coal mill, comprising the following steps: S1, Level 1 Safety Protection Control: Real-time acquisition of the coal mill inlet temperature. If the inlet temperature exceeds the preset safety upper limit, stop the temperature PID regulation, forcibly reduce the opening of the heat source supply valve, match the amount of combustion air according to the preset air-fuel ratio, and execute over-temperature protection. S2. If there are no abnormalities in the first-level safety protection control and the inlet temperature does not exceed the preset safety limit, the second-level temperature stabilization control is entered: the coal mill outlet temperature is collected in real time, and the coal feed rate is dynamically adjusted according to the deviation between the outlet temperature and the reference temperature setting value, so that the coal mill outlet temperature is stabilized in the qualified range. S3. After the outlet temperature stabilizes within the qualified temperature range, the third-level capacity optimization control is entered: the negative pressure at the outlet of the coal mill is collected in real time, and the inlet temperature setpoint and coal feed rate of the coal mill are adjusted simultaneously when the outlet negative pressure is higher or lower than the preset negative pressure range. By adopting a three-level progressive control architecture, with each level interlocked and triggered sequentially, system oscillations caused by simultaneous adjustment of multiple parameters are avoided, thus improving control stability.

[0006] As a further improvement to the present invention, in the first-level safety protection control: The preset safety limit is 330℃. When the inlet temperature is greater than or equal to 330℃, the temperature PID regulation will stop, the heat source supply valve will be forced to the minimum safe opening, and the combustion air will be mixed according to the preset air-fuel ratio. By employing 330℃ over-temperature protection and PID / stop PID segmented control, both over-temperature safety and temperature stability are taken into account, preventing system oscillation.

[0007] As a further improvement of the present invention, in the second-stage temperature stabilization control, the reference temperature setting value of the coal mill is 75℃, and the qualified temperature range is 75℃±1℃; when the outlet temperature exceeds the qualified temperature range, the coal feed rate is adjusted according to the preset step size, and after each adjustment, a preset time is delayed before the next adjustment is performed. By precisely controlling and adjusting the outlet temperature to 75℃±1℃ and then delaying the process, the quality of the pulverized coal is guaranteed and spontaneous combustion of the pulverized coal is prevented.

[0008] As a further improvement of the present invention, in the third-level capacity optimization control, the preset negative pressure range at the coal mill outlet is 7.6 kPa to 7.9 kPa; When the outlet negative pressure is below 7.6 kPa, increase the setpoint of the coal mill inlet temperature and simultaneously increase the coal feed rate; When the outlet negative pressure is higher than 7.9 kPa, reduce the setpoint of the coal mill inlet temperature and reduce the coal feed rate simultaneously. By setting a preset negative pressure range of 7.6 kPa to 7.9 kPa and adjusting it in reverse under high / low negative pressure, a precise response to changes in the grindability of raw coal is achieved.

[0009] As a further improvement of the present invention, when the outlet negative pressure is between 6.7 kPa and 7.6 kPa, the set value of the coal mill inlet temperature is increased by 5°C. When the outlet negative pressure is between 6.5 kPa and 6.7 kPa, increase the setpoint of the coal mill inlet temperature by 10°C. When the outlet negative pressure is less than 6.5 kPa, increase the setpoint of the coal mill inlet temperature by 20°C; When the outlet negative pressure is greater than 7.9 kPa, reduce the inlet temperature setpoint of the coal mill by 10°C; By using a four-level segmented adjustment of the negative pressure range, the mill employs a reverse heating strategy of raising the temperature by 5℃, 10℃ and 20℃ in the low negative pressure range. This allows for the rapid recovery of maximum production capacity when the mill experiences abnormal coal accumulation. In the high negative pressure range, a strategy of lowering the temperature by 10℃ is used to prevent over-grinding, thus enabling the mill to adaptively adjust itself when it deviates from the optimal negative pressure range.

[0010] As a further improvement of the present invention, the lower limit of the allowable working range of the inlet temperature is 300°C. When the inlet temperature drops to 300°C, the current temperature and coal feed rate are maintained and do not continue to decrease. The 300℃ lower limit protection prevents the flue gas furnace from going out or the coal mill from failing to operate normally due to excessively low inlet temperature.

[0011] As a further improvement of the present invention, when the inlet temperature reaches 330°C and the outlet negative pressure is higher than 7.9 kPa, the inlet temperature is kept constant and the air volume of the main exhaust fan is increased until the main exhaust fan reaches the rated maximum air volume. When the inlet temperature reaches the upper limit of 330℃, the output is further increased by increasing the air volume of the main exhaust fan, so that the coal mill can reach the maximum output under the current coal quality conditions.

[0012] As a further improvement of the present invention, when the outlet negative pressure is lower than 7.6 kPa, the inlet temperature setpoint of the coal mill is increased and the coal feed rate is increased simultaneously. The outlet negative pressure is continuously monitored. When the outlet negative pressure recovers to the range of 7.6 kPa to 7.9 kPa, the third-level capacity optimization control is restarted. After the negative pressure at the outlet returns to the preset range, the third-level capacity optimization control is automatically restarted, enabling rapid recovery of the coal mill's capacity after abnormal operating conditions.

[0013] As a further improvement of the present invention, the loading force of the coal mill is kept at a constant value of 10 MPa; The loading force is kept constant at 10MPa, eliminating the interference of loading force fluctuations on the judgment of grinding efficiency and output.

[0014] A coal mill capacity optimization control system, comprising: The inlet temperature detection module is used to collect the inlet temperature of the coal mill in real time. The outlet temperature detection module is used to collect the coal mill outlet temperature in real time. The outlet negative pressure detection module is used to collect the outlet negative pressure of the coal mill in real time. The coal feed rate adjustment module is used to adjust the coal feed rate of the coal feeder. The heat source supply regulation module is used to regulate the amount of heat source supplied and the amount of combustion air. The main exhaust fan adjustment module is used to adjust the air volume of the main exhaust fan; The control module is connected to the inlet temperature detection module, outlet temperature detection module, outlet negative pressure detection module, coal feed rate adjustment module, heat source supply adjustment module, and main exhaust fan adjustment module.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention adopts a three-level progressive control architecture of "first-level safety protection control → second-level temperature stabilization control → third-level capacity optimization control". The control logic of each level is interlocked and triggered step by step. Under the premise of ensuring safe operation and temperature stability, the adaptive optimization of the coal mill capacity is achieved through the fine-grained range judgment and graded adjustment of the outlet negative pressure. This solves the problem that the parallel adjustment of multiple parameters in the prior art is prone to system oscillation. Attached Figure Description

[0016] Figure 1 This is a flowchart of the control logic for the setpoint of the coal mill inlet temperature according to the present invention; Figure 2 This is a flowchart of the coal mill inlet temperature regulation process of the present invention; Figure 3 This is a flowchart of the coal mill outlet temperature regulation process of the present invention; Figure 4 This is a flowchart illustrating the logic for determining the negative pressure range at the coal mill outlet and adjusting the inlet temperature setpoint, as described in this invention. Figure 5 This is a block diagram illustrating the control principle of the coal mill capacity optimization control system of the present invention.

[0017] In the diagram: 1. Inlet temperature detection module; 2. Outlet temperature detection module; 3. Outlet negative pressure detection module; 4. Control module; 5. Coal feed rate adjustment module; 6. Heat source supply adjustment module; 7. Main exhaust fan adjustment module. Detailed Implementation

[0018] To facilitate understanding of the present invention, a more comprehensive description of the present invention will be given below with reference to the accompanying drawings, which illustrate several embodiments of the present invention. However, the present invention can be implemented in different forms and is not limited to the embodiments described in the text. Rather, these embodiments are provided to make the disclosure of the present invention more thorough and complete.

[0019] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0021] The present invention will be further described in detail below with reference to the accompanying drawings.

[0022] Please see Figure 1-5 This invention provides a method for optimizing and controlling the production capacity of a coal mill, comprising the following steps: S1, Level 1 Safety Protection Control: Real-time acquisition of the coal mill inlet temperature. If the inlet temperature exceeds the preset safety upper limit, stop the temperature PID regulation, forcibly reduce the opening of the heat source supply valve, match the amount of combustion air according to the preset air-fuel ratio, and execute over-temperature protection. S2. If there are no abnormalities in the first-level safety protection control and the inlet temperature does not exceed the preset safety limit, the second-level temperature stabilization control is entered: the coal mill outlet temperature is collected in real time, and the coal feed rate is dynamically adjusted according to the deviation between the outlet temperature and the reference temperature setting value, so that the coal mill outlet temperature is stabilized in the qualified range. S3. After the outlet temperature stabilizes within the qualified temperature range, the third-level capacity optimization control is entered: the negative pressure at the outlet of the coal mill is collected in real time, and the inlet temperature setpoint and coal feed rate of the coal mill are adjusted simultaneously when the outlet negative pressure is higher or lower than the preset negative pressure range.

[0023] In the first level of safety protection control: Furthermore, the preset safety upper limit is 330℃. When the inlet temperature is greater than or equal to 330℃, the temperature PID regulation is stopped, the heat source supply valve is forcibly reduced to the minimum safe opening, and the combustion air is mixed according to the preset air-fuel ratio.

[0024] Specifically, the control module 4 sends an instruction to the heat source supply regulation module 6 to force the gas valve opening to be reduced to the minimum safe opening. In this embodiment, the minimum safe opening is 1% opening. At the same time, the opening of the combustion air valve is adjusted according to the preset air-fuel ratio so that the amount of combustion air matches the amount of gas. In this embodiment, the aforementioned stop temperature PID regulation refers to pausing the automatic adjustment function of the proportional-integral-derivative controller. Instead of calculating the gas valve opening in real time based on the temperature deviation, the gas valve is fixed at a preset minimum safe opening, so that the system is in an open-circuit ignition state, preventing overshoot and oscillation caused by continuous PID regulation.

[0025] If the actual inlet temperature does not exceed 330℃, the control module 4 calculates the absolute value of the deviation between the actual inlet temperature and the set inlet temperature, and engages PID control: if the difference between the actual inlet temperature and the set inlet temperature exceeds 2℃, the control module 4 calculates the gas quantity adjustment amount through the PID controller, sends an instruction to the heat source supply adjustment module 6 to reduce the gas supply, and simultaneously reduces the combustion air quantity according to the preset air-fuel ratio; if the difference between the actual inlet temperature and the set inlet temperature is less than 2℃, the control module 4 calculates the gas quantity adjustment amount through the PID controller, sends an instruction to the heat source supply adjustment module 6 to increase the gas supply, and simultaneously increases the combustion air quantity according to the preset air-fuel ratio. When the actual inlet temperature exceeds 330℃, control module 4 stops temperature PID regulation, fixes the gas valve opening to the minimum safe opening of 1%, and matches the combustion air volume according to the preset air-fuel ratio, so that the system can operate stably in an open-loop manner, preventing system oscillation and overshoot caused by continuous integral action of PID.

[0026] Furthermore, in the second-stage temperature stabilization control, the reference temperature setting of the coal mill is 75℃, and the qualified temperature range is 75℃±1℃. If the outlet temperature exceeds the qualified temperature range, the coal feed rate is adjusted according to the preset step size, and the next adjustment is performed after a preset time delay after each adjustment.

[0027] Control module 4 calculates the deviation between the actual outlet temperature and the setpoint reference temperature. If the actual outlet temperature exceeds the setpoint by more than 1°C, control module 4 sends an instruction to coal feed rate adjustment module 5 to increase the coal feed rate by a preset step size, thereby increasing the pulverized coal production and outlet temperature of the pulverizer. In this embodiment, if the actual outlet temperature is lower than the setpoint by more than 1°C, control module 4 sends an instruction to coal feed rate adjustment module 5 to decrease the coal feed rate by a preset step size, reducing the amount of raw coal entering the pulverizer. If the absolute value of the deviation between the actual outlet temperature and the setpoint is no greater than 1°C, control module 4 maintains the current coal feed rate unchanged. After each coal feed rate adjustment action, the system delays for a preset time before performing the next deviation judgment and adjustment. In this embodiment, the preset delay is 60 seconds to allow the grinding conditions and temperature field inside the pulverizer to fully stabilize before proceeding to the next round of adjustment, avoiding system oscillations caused by frequent coal feed rate adjustments.

[0028] Furthermore, in the third-level capacity optimization control, the preset negative pressure range at the coal mill outlet is 7.6 kPa to 7.9 kPa; When the outlet negative pressure is below 7.6 kPa, increase the setpoint of the coal mill inlet temperature and simultaneously increase the coal feed rate; When the outlet negative pressure is higher than 7.9 kPa, reduce the setpoint of the coal mill inlet temperature and reduce the coal feed rate simultaneously.

[0029] When the outlet negative pressure is lower than 7.6 kPa, it indicates that the outlet negative pressure of the coal mill is too low, the amount of coal stored inside the coal mill is too small, the raw coal has good grindability, and there is room for production increase. The control module 4 increases production by increasing the inlet temperature setpoint of the coal mill and simultaneously increasing the coal feed rate. When the inlet temperature reaches 330℃ and the outlet negative pressure is higher than 7.9 kPa, the control module 4 maintains the inlet temperature unchanged and increases the air volume of the main exhaust fan through the main exhaust fan adjustment module 7 to continue to increase the output until the main exhaust fan reaches the rated maximum air volume, so that the coal mill reaches the maximum output under the current coal quality conditions.

[0030] When the outlet negative pressure is higher than 7.9 kPa and the inlet temperature does not reach 330℃, it indicates that the amount of coal stored inside the coal mill is too large and the grindability of the raw coal is deteriorated. The load needs to be reduced. The control module 4 reduces the load by lowering the inlet temperature setpoint of the coal mill and simultaneously reducing the coal feed rate.

[0031] Furthermore, when the outlet negative pressure is between 6.7 kPa and 7.6 kPa, the setpoint for the coal mill inlet temperature is increased by 5°C. When the outlet negative pressure is between 6.5 kPa and 6.7 kPa, increase the setpoint of the coal mill inlet temperature by 10°C. When the outlet negative pressure is less than 6.5 kPa, increase the setpoint of the coal mill inlet temperature by 20°C; When the outlet negative pressure is greater than 7.9 kPa, reduce the inlet temperature setpoint of the coal mill by 10°C.

[0032] Furthermore, the lower limit of the allowable operating range for the inlet temperature is 300℃. If the inlet temperature drops to 300℃, the current temperature and coal feed rate will be maintained and will not be further reduced.

[0033] In this embodiment, four different adjustment strategies are adopted according to the different ranges of the outlet negative pressure: When the outlet negative pressure is between 6.7 kPa and 7.6 kPa, the control module 4 increases the mill inlet temperature setpoint by 5°C and simultaneously increases the coal feed rate; when the outlet negative pressure is between 6.5 kPa and 6.7 kPa, the control module 4 increases the mill inlet temperature setpoint by 10°C to increase the fluidity of the coal powder inside the mill by moderately raising the temperature, thereby disrupting the initial formation of the material layer accumulation, and simultaneously adjusts the coal feed rate; when the outlet negative pressure is less than 6.5 kPa, the control module 4 increases the mill inlet temperature setpoint by 20°C to significantly improve the internal temperature field of the mill, enhance the fluidity of the coal powder, accelerate the discharge of accumulated coal, and simultaneously adjust the coal feed rate; when the outlet negative pressure is greater than 7.9 kPa, the control module decreases the mill inlet temperature setpoint by 10°C to prevent mill vibration caused by excessive material layer thickness and stabilize the grinding conditions.

[0034] Furthermore, when the inlet temperature reaches 330℃ and the outlet negative pressure is higher than 7.9kPa, the inlet temperature is kept constant, and the air volume of the main exhaust fan is increased until the main exhaust fan reaches its rated maximum air volume.

[0035] Furthermore, after the outlet negative pressure is lower than 7.6 kPa and the setpoint of the coal mill inlet temperature is increased and the coal feed rate is increased simultaneously, the outlet negative pressure is continuously monitored. When the outlet negative pressure recovers to the range of 7.6 kPa to 7.9 kPa, the third-level capacity optimization control is restarted.

[0036] Furthermore, the loading force on the coal mill is kept constant at 10 MPa.

[0037] The loading force of a coal mill refers to the grinding pressure exerted by the mill rollers on the raw coal on the grinding disc. Controlled by a hydraulic system, the stability of the loading force ensures a constant grinding pressure of the rollers on the raw coal, eliminating the interference of loading force fluctuations on the judgment of the mill's output. This allows the system to accurately judge the mill's operating condition and make corresponding adjustments based on changes in inlet temperature, outlet temperature, and outlet negative pressure. In this embodiment, the mill loading force is controlled in a closed loop through a proportional relief valve in the hydraulic station, with a set value of 10 MPa and a control accuracy of ±0.2 MPa.

[0038] In the three-level progressive control architecture adopted in this invention, the logical relationships between the control logic at each level are as follows: The first-level safety protection control has the highest priority. When the inlet temperature exceeds the preset safety upper limit of 330℃, the first-level control directly intervenes, forcibly reducing the opening of the heat source supply valve and matching the combustion air volume according to the preset air-fuel ratio, and executing over-temperature protection. At this time, the second-level and third-level controls do not start. If the first-level safety protection control is normal and the inlet temperature does not exceed the preset safety upper limit of 330℃, the second-level temperature stabilization control can be started. By adjusting the coal feed rate, the outlet temperature is stabilized within the qualified range of 75℃±1℃. Only after the second-level temperature stabilization control stabilizes the outlet temperature within the qualified temperature range can the third-level capacity optimization control be started. Depending on whether the outlet negative pressure is higher or lower than the preset range of 7.6kPa~7.9kPa, the set value of the coal mill inlet temperature and the coal feed rate are simultaneously corrected. The above-mentioned step-by-step interlocking control logic ensures that the system operates within a safe temperature range, avoids system oscillation caused by simultaneous adjustment of multiple parameters, and improves the stability and reliability of the control system.

[0039] A coal mill capacity optimization control system, comprising: Inlet temperature detection module 1 is used to collect the inlet temperature of the coal mill in real time; Outlet temperature detection module 2 is used to collect the coal mill outlet temperature in real time; The outlet negative pressure detection module 3 is used to collect the coal mill outlet negative pressure in real time. Coal feed rate adjustment module 5 is used to adjust the coal feed rate of the coal feeder; Heat source supply regulation module 6 is used to regulate the amount of heat source supply and the amount of combustion air. Main exhaust fan adjustment module 7 is used to adjust the air volume of the main exhaust fan; Control module 4 is connected to inlet temperature detection module 1, outlet temperature detection module 2, outlet negative pressure detection module 3, coal feed rate adjustment module 5, heat source supply adjustment module 6, and main exhaust fan adjustment module 7 via signals.

[0040] In this embodiment, temperature sensors are installed on the inlet and outlet pipes of the coal mill, and pressure sensors are installed on the outlet pipe of the coal mill. This embodiment includes a gas regulating valve installed on the flue gas furnace gas pipeline and an air regulating valve installed on the combustion air pipeline. The air volume is controlled by adjusting the speed of the main exhaust fan motor. The control module 4 is signal-connected to the inlet temperature detection module 1, the outlet temperature detection module 2, the outlet negative pressure detection module 3, the coal feed rate regulation module 5, the heat source supply regulation module 6, and the main exhaust fan regulation module 7. In this embodiment, it is a programmable logic controller or a distributed control system used to execute the coal mill capacity optimization control method provided by this invention.

[0041] The present invention has been described by way of example in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvement made by adopting the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, shall be within the protection scope of the present invention.

Claims

1. A method for optimizing and controlling the production capacity of a coal mill, characterized in that: Includes the following steps: S1, Level 1 Safety Protection Control: Real-time acquisition of the coal mill inlet temperature. If the inlet temperature exceeds the preset safety upper limit, stop the temperature PID regulation, forcibly reduce the opening of the heat source supply valve, match the amount of combustion air according to the preset air-fuel ratio, and execute over-temperature protection. S2. If there are no abnormalities in the first-level safety protection control and the inlet temperature does not exceed the preset safety limit, the second-level temperature stabilization control is entered: the coal mill outlet temperature is collected in real time, and the coal feed rate is dynamically adjusted according to the deviation between the outlet temperature and the reference temperature setting value, so that the coal mill outlet temperature is stabilized in the qualified range. S3. After the outlet temperature stabilizes within the qualified temperature range, the third-level capacity optimization control is entered: the negative pressure at the outlet of the coal mill is collected in real time, and the inlet temperature setpoint and coal feed rate of the coal mill are adjusted simultaneously when the outlet negative pressure is higher or lower than the preset negative pressure range.

2. The method for optimizing and controlling the production capacity of a coal mill according to claim 1, characterized in that: In the first level of safety protection control: The preset safety upper limit is 330℃. When the inlet temperature is greater than or equal to 330℃, the temperature PID regulation will stop, the heat source supply valve will be forced to reduce to the minimum safe opening, and the combustion air will be mixed according to the preset air-fuel ratio.

3. The method for optimizing and controlling the production capacity of a coal mill according to claim 1, characterized in that: In the second-stage temperature stabilization control, the reference temperature setting of the coal mill is 75℃, and the qualified temperature range is 75℃±1℃. If the outlet temperature exceeds the qualified temperature range, the coal feed rate is adjusted according to the preset step size, and the next adjustment is performed after a preset time delay after each adjustment.

4. The method for optimizing and controlling the production capacity of a coal mill according to claim 2, characterized in that: In the third-level capacity optimization control, the preset negative pressure range at the coal mill outlet is 7.6 kPa to 7.9 kPa; When the outlet negative pressure is below 7.6 kPa, increase the setpoint of the coal mill inlet temperature and simultaneously increase the coal feed rate; When the outlet negative pressure is higher than 7.9 kPa, reduce the setpoint of the coal mill inlet temperature and reduce the coal feed rate simultaneously.

5. The method for optimizing and controlling the production capacity of a coal mill according to claim 4, characterized in that: When the outlet negative pressure is between 6.7 kPa and 7.6 kPa, increase the setpoint of the coal mill inlet temperature by 5°C. When the outlet negative pressure is between 6.5 kPa and 6.7 kPa, increase the setpoint of the coal mill inlet temperature by 10°C. When the outlet negative pressure is less than 6.5 kPa, increase the setpoint of the coal mill inlet temperature by 20°C; When the outlet negative pressure is greater than 7.9 kPa, reduce the inlet temperature setpoint of the coal mill by 10°C.

6. The method for optimizing and controlling the production capacity of a coal mill according to claim 1, characterized in that: The lower limit of the allowable operating range for inlet temperature is 300℃. If the inlet temperature drops to 300℃, the current temperature and coal feed rate will be maintained and will not be further reduced.

7. The method for optimizing and controlling the production capacity of a coal mill according to claim 4, characterized in that: When the inlet temperature reaches 330℃ and the outlet negative pressure is higher than 7.9kPa, keep the inlet temperature constant and increase the air volume of the main exhaust fan until the main exhaust fan reaches the rated maximum air volume.

8. The method for optimizing and controlling the production capacity of a coal mill according to claim 4, characterized in that: When the outlet negative pressure is below 7.6 kPa, the inlet temperature setpoint of the coal mill is increased and the coal feed rate is increased simultaneously. The outlet negative pressure is continuously monitored. When the outlet negative pressure recovers to the range of 7.6 kPa to 7.9 kPa, the third-level capacity optimization control is restarted.

9. The method for optimizing and controlling the production capacity of a coal mill according to claim 1, characterized in that: The loading force on the coal mill is kept constant at 10 MPa.

10. A coal mill capacity optimization control system, used to execute a coal mill capacity optimization control method according to any one of claims 1 to 9, characterized in that, include: Inlet temperature detection module (1) is used to collect the inlet temperature of the coal mill in real time; The outlet temperature detection module (2) is used to collect the coal mill outlet temperature in real time. The outlet negative pressure detection module (3) is used to collect the outlet negative pressure of the coal mill in real time; The coal feed rate adjustment module (5) is used to adjust the coal feed rate of the coal feeder. Heat source supply regulation module (6) is used to regulate the amount of heat source supply and the amount of combustion air; The main exhaust fan regulating module (7) is used to regulate the air volume of the main exhaust fan; The control module (4) is connected to the inlet temperature detection module (1), the outlet temperature detection module (2), the outlet negative pressure detection module (3), the coal feed rate adjustment module (5), the heat source supply adjustment module (6), and the main exhaust fan adjustment module (7).

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