Burner safety control system for negative pressure furnace

Abstract

The invention discloses a combustor safety control system for a negative pressure furnace, relates to the technical field of combustion control of negative pressure furnaces, and aims to solve the technical problems that single closed-loop control response of an existing negative pressure furnace combustor is lagged, and the system stability is poor. According to the system, a double-closed-loop control framework of cooperative work of an inner-layer combustion stability closed loop and an outer-layer negative pressure closed loop is constructed, flame characteristic parameters and the gas / air proportion serve as core control objects of the inner-layer closed loop, the opening degree of a gas proportional valve and the rotating speed of a draught fan are adjusted in real time through a PID algorithm, and the combustion state is kept stable; the outer-layer closed loop dynamically adjusts the opening degree of the hearth baffle valve based on the inner-layer adjusting result so as to maintain the negative pressure within a preset range; when any closed loop is abnormal, the system automatically triggers a cross-closed-loop compensation mechanism, and the other closed loop optimizes self-adjusting parameters in real time to realize dynamic compensation. Through double-closed-loop cooperation and abnormal compensation design, the control response speed and operation safety of the negative pressure furnace combustor are greatly improved, the problem of response lag of single closed-loop control is effectively solved, and the method is suitable for safety control of various industrial negative pressure furnace combustion systems.

Description

Technical Field

[0001] This invention relates to the field of combustion control technology for negative pressure furnaces, and in particular to a safety control system for burners used in negative pressure furnaces. Background Technology

[0002] Negative pressure furnaces are widely used in chemical, metallurgical, and energy industries. Maintaining a negative pressure state inside the furnace effectively prevents safety issues such as flame overflow and flue gas leakage. As the core component of a negative pressure furnace, the burner's combustion stability directly determines the furnace's operational safety and energy efficiency.

[0003] Existing control schemes for negative pressure furnace burners mostly employ single closed-loop control: one type is closed-loop control that only targets the combustion state, maintaining flame stability by adjusting the gas / air ratio, but it cannot adapt to changes in furnace negative pressure in real time, and is prone to incomplete combustion or even flameout due to negative pressure fluctuations; the other type is closed-loop control that only targets furnace negative pressure, maintaining negative pressure by adjusting the opening of the damper valve, but the response lags behind changes in the combustion state, and when the combustion conditions change abruptly, the negative pressure adjustment cannot keep up in time, which can easily lead to abnormal furnace pressure.

[0004] Some improvement schemes attempt to link combustion status with negative pressure control, but this is only a simple sequential control (first adjusting combustion parameters, then adjusting negative pressure parameters with a lag), and does not form a true dual closed-loop collaboration. There are still problems such as response lag and lack of compensation mechanism under abnormal operating conditions, which cannot meet the high safety and high stability operation requirements of industrial negative pressure furnaces. Summary of the Invention

[0005] The purpose of this invention is to propose a safety control system for burners in negative pressure furnaces, which aims to solve the problems of slow response, lack of abnormal compensation mechanism, and poor system stability in the existing single closed-loop control of negative pressure furnace burners.

[0006] The present invention is implemented as follows: a burner safety control system for a negative pressure furnace, the system comprising a combustion state monitoring module, an inner combustion stability closed-loop control unit, an outer negative pressure closed-loop control unit, and an anomaly compensation module. The combustion status monitoring module is used to collect flame characteristic parameters, gas flow rate, air flow rate and furnace negative pressure value of the negative pressure furnace burner, and transmit the collected data to the inner and outer closed-loop control units in real time.

[0007] The inner combustion stability closed-loop control unit is connected to the combustion state monitoring module. It takes flame characteristic parameters and gas / air ratio as control objects, and has a built-in PID adjustment algorithm to adjust the gas ratio valve opening and fan speed in real time according to the collected flame characteristic parameters, gas flow rate and air flow rate. The outer negative pressure closed-loop control unit is communicatively connected to the combustion state monitoring module and the inner combustion stability closed-loop control unit, respectively. Taking the furnace negative pressure value as the control object, the furnace baffle valve opening is dynamically adjusted based on the adjustment result of the inner combustion stability closed-loop control unit to maintain the furnace negative pressure within a preset range. The anomaly compensation module is communicatively connected to the inner combustion stability closed-loop control unit and the outer negative pressure closed-loop control unit, respectively, and is used to monitor the operating status of the two closed loops. When an anomaly is detected in either closed loop, the other closed loop is triggered to automatically optimize its PID adjustment parameters or baffle valve adjustment parameters for compensation, so as to ensure the overall stable operation of the system.

[0008] Beneficial effects of the present invention This invention proposes a safety control system for burners in negative pressure furnaces. The system constructs a dual-closed-loop control architecture with an inner combustion stability closed loop and an outer negative pressure closed loop working in tandem. The inner closed loop uses flame characteristic parameters and the gas / air ratio as the core control objects, adjusting the gas proportional valve opening and fan speed in real time through a PID algorithm to maintain stable combustion. The outer closed loop dynamically adjusts the furnace baffle valve opening based on the inner loop's adjustment results to maintain negative pressure within a preset range. When any closed loop malfunctions, the system automatically triggers a cross-closed-loop compensation mechanism, with the other closed loop dynamically compensating by optimizing its own adjustment parameters in real time. Through dual-closed-loop collaboration and anomaly compensation design, this invention significantly improves the control response speed and operational safety of negative pressure furnace burners, effectively solving the response lag problem of single-closed-loop control. It is applicable to the safety control of combustion systems in various industrial negative pressure furnaces. Attached Figure Description

[0009] Figure 1 This is a structural diagram of a burner safety control system for a negative pressure furnace according to a preferred embodiment of the present invention. Detailed Implementation

[0010] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. For ease of explanation, only the parts related to the embodiments of this invention are shown. It should be understood that the specific embodiments described herein are merely for explaining this invention and are not intended to limit this invention.

[0011] This invention proposes a safety control system for burners in negative pressure furnaces. The system employs a dual-closed-loop control architecture, with an inner closed-loop for combustion stability and an outer closed-loop for negative pressure working in tandem. The inner closed-loop uses flame characteristic parameters and the gas / air ratio as its core control objects, employing a PID algorithm to adjust the gas proportional valve opening and fan speed in real time to maintain stable combustion. The outer closed-loop, based on the inner loop's adjustment results, dynamically adjusts the furnace baffle valve opening to maintain negative pressure within a preset range. When any closed loop malfunctions, the system automatically triggers a cross-loop compensation mechanism, with the other closed loop dynamically compensating by optimizing its own adjustment parameters in real time. This invention, through dual-closed-loop collaboration and anomaly compensation design, significantly improves the control response speed and operational safety of negative pressure furnace burners, effectively solving the response lag problem of single-loop control. It is applicable to the safety control of combustion systems in various industrial negative pressure furnaces.

[0012] Figure 1 This is a structural diagram of a burner safety control system for a negative pressure furnace according to a preferred embodiment of the present invention. The system includes a combustion state monitoring module, an inner combustion stability closed-loop control unit, an outer negative pressure closed-loop control unit, and an anomaly compensation module.

[0013] The combustion status monitoring module is used to collect flame characteristic parameters, gas flow rate, air flow rate and furnace negative pressure value of the negative pressure furnace burner, and transmit the collected data to the inner and outer closed-loop control units in real time.

[0014] Furthermore, in a specific embodiment, flame characteristic parameters can be acquired by a flame sensor such as a flame ion current sensor; the flame characteristic parameters include at least two of flame brightness, flame shape, flame temperature, and flame ion current; the gas flow rate can be acquired by a gas flow meter such as a gas vortex flow meter; the air flow rate can be acquired by an air flow meter such as an air thermal flow meter; and the furnace negative pressure value can be acquired by a negative pressure sensor. Among them, flame sensors (such as flame ionization current sensors) can be installed on the inner wall of the furnace next to the burner nozzle of the negative pressure furnace, facing the flame combustion area, to collect flame characteristic parameters such as flame ionization current and flame temperature in real time; gas flow meters (such as gas vortex flow meters) can be installed in series in the gas inlet pipe of the burner, located in the pipe section between the gas proportional valve and the burner nozzle, to accurately collect the real-time flow during the gas delivery process; air flow meters (such as air thermal flow meters) can be installed in series in the air inlet pipe of the burner, located in the pipe section between the fan outlet and the burner nozzle, to collect the real-time air flow delivered to the burner by the fan; negative pressure sensors can be installed in the upper middle part of the side wall of the negative pressure furnace, in a position where there is no direct flame blowing and no flue gas vortex, to stably collect the real-time negative pressure value inside the furnace. The acquisition signals of each sensor and flow meter are transmitted in real time to the PLC of the dual closed-loop control unit through industrial communication lines, providing a precise and real-time data source for subsequent adjustment calculations.

[0015] The inner combustion stability closed-loop control unit is connected to the combustion state monitoring module. It takes flame characteristic parameters and gas / air ratio as control objects, and has a built-in PID adjustment algorithm to adjust the gas ratio valve opening and fan speed in real time according to the collected flame characteristic parameters, gas flow rate and air flow rate. The PID control algorithm of the inner combustion stability closed-loop control unit includes the following steps: S11: Set target values ​​for flame characteristic parameters and gas / air ratio; S12: Calculate the first deviation between the actual and target values ​​of the collected flame characteristic parameters, and the second deviation between the actual and target values ​​of the fuel gas / air ratio; S13: Input the first and second deviations into the PID algorithm (proportional integral derivative algorithm), and output the gas proportional valve opening adjustment amount and the fan speed adjustment amount; S14: Adjust the gas proportional valve and fan according to the adjustment amount, and feed back the adjusted parameters to step S12 in real time to form a closed-loop control.

[0016] In a specific implementation, the inner combustion stability closed-loop control unit can be a PLC (Programmable Logic Controller) (such as model S7-1200), with a built-in PID adjustment algorithm, and set target values ​​for flame ionization current, flame temperature, and natural gas / air ratio; The outer negative pressure closed-loop control unit is communicatively connected to the combustion state monitoring module and the inner combustion stability closed-loop control unit, respectively. Taking the furnace negative pressure value as the control object, the furnace baffle valve opening is dynamically adjusted based on the adjustment result of the inner combustion stability closed-loop control unit to maintain the furnace negative pressure within a preset range. In a specific implementation, the outer negative pressure closed-loop control unit can share the same PLC with the inner combustion stability closed-loop control unit to set the furnace negative pressure preset range. The opening degree of the dynamically adjustable baffle valve is: The real-time values ​​of the gas proportional valve opening and fan speed output by the inner combustion stability closed-loop control unit are obtained, and the theoretical value of furnace negative pressure is calculated based on the preset mapping relationship (through experimental calibration, such as the theoretical value of furnace negative pressure decreases by 5Pa for every 100r / min increase in fan speed). The theoretical value of the furnace negative pressure is compared with the actual value of the collected negative pressure to calculate the negative pressure deviation; The baffle valve opening adjustment command is dynamically output based on the negative pressure deviation, and the adjustment range is positively correlated with the inner layer adjustment amount.

[0017] The anomaly compensation module is communicatively connected to the inner combustion stability closed-loop control unit and the outer negative pressure closed-loop control unit, respectively, and is used to monitor the operating status of the two closed loops. When an anomaly is detected in either closed loop, the other closed loop is triggered to automatically optimize its PID adjustment parameters or baffle valve adjustment parameters for compensation, so as to ensure the overall stable operation of the system.

[0018] In a specific implementation, the anomaly compensation module can be integrated into the PLC mentioned above (a PLC shared by the outer negative pressure closed-loop control unit and the inner combustion stability closed-loop control unit), with preset anomaly judgment conditions. The anomaly determination conditions of the anomaly compensation module include: Inner closed loop: Flame characteristic parameter deviation exceeds the first preset threshold (e.g., temperature deviation ±50℃) and the duration is ≥ the first preset duration (e.g., 5s), or gas / air ratio deviation exceeds the second preset threshold (±10%) and the duration is ≥ the second preset duration (e.g., 3s). Outer closed loop: The negative pressure value in the furnace deviates from the preset range by more than the third preset threshold (e.g., ±15Pa) and the duration is ≥ the third preset duration (e.g., 8s). When any anomaly detection condition is met, the anomaly compensation module sends a compensation command to the other closed loop, which then optimizes its own adjustment parameters based on a preset compensation coefficient.

[0019] The compensation coefficient is pre-calibrated based on the rated power, furnace volume and gas type of the negative pressure furnace (for example, the compensation coefficient is calibrated based on the negative pressure furnace as follows: when the inner layer is abnormal, the adjustment range of the outer layer baffle valve increases by 20%; when the outer layer is abnormal, the proportional coefficient of the inner layer PID parameter increases by 15% and the integral time decreases by 10%), and stored in the parameter library of the abnormality compensation module.

[0020] The following describes the specific implementation of the present invention in detail using a natural gas negative pressure furnace with a rated power of 1000kW and a furnace volume of 5m³ as an example.

[0021] Step 1: System Setup The combustion status monitoring module uses: a flame ionization current sensor (range 0-10mA, accuracy ±0.1mA), an infrared flame temperature sensor (range 0-1200℃, accuracy ±1℃), a gas vortex flow meter (range 0-100m³ / h, accuracy ±0.5%), an air thermal flow meter (range 0-1000m³ / h, accuracy ±0.5%), and a negative pressure sensor (range -50 to 0Pa, accuracy ±0.1Pa). The inner combustion stability closed-loop control unit adopts a PLC (model S7-1200) with a built-in PID regulation algorithm, and sets the target value of flame ionization current to 6mA, flame temperature to 900℃, and natural gas / air ratio to 1:11. The outer layer negative pressure closed-loop control unit shares the same PLC with the inner layer, and sets the furnace negative pressure preset range to -15 to -10 Pa; The anomaly compensation module is integrated into the PLC, with preset anomaly judgment conditions: inner closed loop (ion current deviation ≥1mA and lasting ≥5s, or temperature deviation ≥50℃ and lasting ≥5s, or gas / air ratio deviation ≥10% and lasting ≥3s); outer closed loop (negative pressure deviation from preset range ≥15Pa and lasting ≥8s); the compensation coefficient is calibrated according to the negative pressure furnace as follows: when the inner layer is abnormal, the adjustment range of the outer layer baffle valve increases by 20%; when the outer layer is abnormal, the proportional coefficient of the inner layer PID parameter increases by 15% and the integral time decreases by 10%.

[0022] Step 2: Closed-loop control of inner combustion stability The combustion status monitoring module collects real-time data on flame ionization current (5.2mA), temperature (850℃), gas flow rate (8m³ / h), and air flow rate (80m³ / h), and calculates the gas / air ratio to be 1:10 (deviation 9.1%). The inner closed-loop control unit's calculation deviations are as follows: ion current deviation 0.8mA (not reaching the abnormal threshold), temperature deviation 50℃ (reaching the abnormal threshold but not lasting for the duration), and gas / air ratio deviation 9.1% (not reaching the abnormal threshold). Inputting the deviation into the PID algorithm will increase the gas proportional valve opening by 5% and the fan speed by 50 r / min. After adjustment, the gas flow rate becomes 8.8 m³ / h, the air flow rate becomes 88 m³ / h, the gas / air ratio is restored to 1:11, the flame ionization current becomes 6 mA, and the temperature becomes 900℃. The parameters are fed back to the monitoring module, completing the inner closed-loop adjustment.

[0023] Step 3: Outer layer negative pressure closed-loop control The outer closed-loop control unit obtains the adjusted fan speed (increased by 50 r / min) from the inner layer, and calculates a theoretical decrease in negative pressure of 2.5 Pa based on the mapping relationship (original negative pressure -12 Pa, theoretical value becomes -14.5 Pa). The negative pressure sensor collects the actual negative pressure value of -16Pa and calculates the negative pressure deviation as 1.5Pa. The opening of the output baffle valve is increased by 3%, and the negative pressure in the furnace becomes -14.5Pa after adjustment. This is fed back to the monitoring module to complete the outer closed-loop regulation.

[0024] Step 4: Example of anomaly compensation When air leakage occurs in the furnace, the negative pressure sensor collects a negative pressure value of -30Pa (15Pa deviates from the preset range). After 8 seconds, the abnormality compensation module determines that the outer closed loop is abnormal. The anomaly compensation module sends a compensation command to the inner closed loop, which adjusts the proportional coefficient of the PID parameters from 2.0 to 2.3 (an increase of 15%) and the integral time from 10s to 9s (a decrease of 10%). The inner closed loop, based on optimized PID parameters, reduces the opening of the output gas proportional valve by 8% and the fan speed by 80 r / min, thereby reducing the combustion intensity. Based on the inner layer adjustment results, the outer closed loop calculates a theoretical increase of 4Pa in negative pressure. With the damper valve opening reduced by 5%, the furnace negative pressure is finally restored to -14Pa, and the system returns to stability.

[0025] Step 5: Continuous Control The system repeats steps 2-4, collecting parameters in real time, adjusting the dual closed loop, and compensating for anomalies to achieve continuous and safe control of the negative pressure furnace burner.

[0026] The core of this invention lies in the dual-closed-loop coordination and anomaly compensation mechanism. The above embodiments are merely preferred implementations of this invention and are not intended to limit the invention. In practical applications, the target parameters, anomaly judgment conditions, and compensation coefficients can be adjusted according to the specifications of the negative pressure furnace and the type of gas, all of which fall within the protection scope of this invention.

[0027] Those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by program instructions and related hardware. The program can be stored in a computer-readable storage medium, such as ROM, RAM, disk, optical disk, etc.

[0028] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A burner safety control system for a negative pressure furnace, characterized in that, The system includes a combustion state monitoring module, an inner combustion stability closed-loop control unit, an outer negative pressure closed-loop control unit, and an anomaly compensation module. The combustion status monitoring module is used to collect flame characteristic parameters, gas flow rate, air flow rate and furnace negative pressure value of the negative pressure furnace burner, and transmit the collected data to the inner and outer closed-loop control units in real time.

2. The inner combustion stability closed-loop control unit is connected to the combustion state monitoring module. It takes flame characteristic parameters and gas / air ratio as control objects, and has a built-in PID adjustment algorithm to adjust the gas ratio valve opening and fan speed in real time according to the collected flame characteristic parameters, gas flow rate and air flow rate. The outer negative pressure closed-loop control unit is communicatively connected to the combustion state monitoring module and the inner combustion stability closed-loop control unit, respectively. Taking the furnace negative pressure value as the control object, the furnace baffle valve opening is dynamically adjusted based on the adjustment result of the inner combustion stability closed-loop control unit to maintain the furnace negative pressure within a preset range. The anomaly compensation module is communicatively connected to the inner combustion stability closed-loop control unit and the outer negative pressure closed-loop control unit, respectively, and is used to monitor the operating status of the two closed loops. When an anomaly is detected in either closed loop, the other closed loop is triggered to automatically optimize its PID adjustment parameters or baffle valve adjustment parameters for compensation, so as to ensure the overall stable operation of the system.

3. The burner safety control system for a negative pressure furnace according to claim 1, characterized in that, The flame characteristic parameters include at least two of the following: flame brightness, flame shape, flame temperature, and flame ion current. According to claim 1, the burner safety control system for a negative pressure furnace is characterized in that the PID adjustment algorithm of the inner combustion stability closed-loop control unit includes the following steps: Set target values ​​for flame characteristic parameters and gas / air ratio; Calculate the first deviation between the actual and target values ​​of the collected flame characteristic parameters, and the second deviation between the actual and target values ​​of the fuel gas / air ratio; Input the first and second deviations into the PID algorithm to output the gas proportional valve opening adjustment and the fan speed adjustment. Adjust the gas proportional valve and fan according to the adjustment amount, and provide real-time feedback on the adjusted parameters to form a closed-loop control.

4. The burner safety control system for a negative pressure furnace according to claim 1, characterized in that, The opening degree of the dynamically adjustable baffle valve is: The real-time values ​​of the gas proportional valve opening and fan speed output by the inner combustion stability closed-loop control unit are obtained, and the theoretical value of furnace negative pressure is calculated based on the preset mapping relationship. The theoretical value of the furnace negative pressure is compared with the actual value of the collected negative pressure to calculate the negative pressure deviation; The baffle valve opening adjustment command is dynamically output based on the negative pressure deviation, and the adjustment range is positively correlated with the inner layer adjustment amount.

5. The burner safety control system for a negative pressure furnace according to claim 1, characterized in that, The anomaly determination conditions of the anomaly compensation module include: Inner closed loop: Flame characteristic parameter deviation exceeds the first preset threshold and the duration is ≥ the first preset duration, or gas / air ratio deviation exceeds the second preset threshold and the duration is ≥ the second preset duration; Outer closed loop: The negative pressure value in the furnace deviates from the preset range by more than the third preset threshold and the duration is greater than or equal to the third preset duration; When any anomaly detection condition is met, the anomaly compensation module sends a compensation command to the other closed loop, which then optimizes its own adjustment parameters based on a preset compensation coefficient.

6. The burner safety control system for a negative pressure furnace according to claim 5, characterized in that, The compensation coefficient is pre-calibrated based on the rated power of the negative pressure furnace, the furnace volume, and the gas type, and is stored in the parameter library of the abnormal compensation module.

7. The burner safety control system for a negative pressure furnace according to claim 1, characterized in that, Flame characteristic parameters are collected by a flame sensor; gas flow rate is collected by a gas flow meter. Air flow rate is collected by an air flow meter; furnace negative pressure value is collected by a negative pressure sensor.

8. The burner safety control system for a negative pressure furnace according to claim 7, characterized in that, The flame sensor is installed on the inner wall of the furnace next to the burner nozzle of the negative pressure furnace, facing the flame combustion area, to collect flame characteristic parameters in real time. The gas flow meter is installed in series in the gas inlet pipeline of the burner, in the section of the pipeline between the gas proportional valve and the burner nozzle, to collect the real-time flow during the gas delivery process. An air flow meter is installed in series in the air inlet duct of the burner, in the section of the duct between the fan outlet and the burner nozzle, to collect the air flow rate delivered to the burner by the fan in real time. The negative pressure sensor is installed in the upper middle part of the side wall of the negative pressure furnace, in a position where there is no direct flame blowing and no flue gas vortex, to collect the real-time negative pressure value inside the furnace.

9. The burner safety control system for a negative pressure furnace according to claim 1, characterized in that, The outer negative pressure closed-loop control unit and the inner combustion stability closed-loop control unit share the same PLC.

10. The burner safety control system for a negative pressure furnace according to claim 9, characterized in that, The anomaly compensation module is integrated into the PLC and has preset anomaly detection conditions.

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