Low-nitrogen combustion control method and system for annealing furnace

Abstract

The invention relates to the technical field of annealing furnace control, in particular to a low-nitrogen combustion control method and system for an annealing furnace, and the method comprises the steps that the hearth temperature of each heating zone in a heating section of the annealing furnace is obtained; calculating a PID adjustment coefficient of each heating zone at the current moment through a PID algorithm; calculating a global coordination index of each heating zone at the current moment; and the target air-fuel ratio and the gas valve opening degree of each heating zone at the current moment are determined, and the air valve opening degree of each heating zone at the current moment is determined according to the target air-fuel ratio and the gas valve opening degree of each heating zone at the current moment. By performing partition cooperative control on the heating section, the overhigh temperature caused by PID excessive adjustment in a single area is avoided, and generation of thermal NOx is reduced from the source.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of annealing furnace control. More particularly, the present application relates to a low-nitrogen combustion control method and system for an annealing furnace. BACKGROUND

[0002] The annealing furnace is one of the commonly used heat treatment equipment in the mechanical manufacturing industry, and its basic function is to heat and cool the metal material or workpiece to achieve the purposes of softening, reducing hardness, improving plasticity and toughness, homogenizing chemical composition, removing internal stress, etc., so as to achieve the expected physical and mechanical properties. When the annealing furnace is used to anneal the metal material at high temperature, fuel needs to be used for heating, and harmful gases such as nitrogen oxides will be generated during the combustion process. Nitrogen oxides are one of the main components of air pollution, which has certain harm to the environment and human health. Therefore, it is necessary to reduce or control the generation amount of nitrogen oxides (NOx) as much as possible during the combustion process, i.e. low-nitrogen combustion.

[0003] In the prior art, an independent PID controller is usually used to adjust the temperature of the heating section of the annealing furnace. However, the independent PID controller only adjusts according to the local temperature error, ignores the coupling relationship between the upstream and downstream partitions, and is easy to cause the temperature of a certain region to be adjusted excessively or insufficiently. If the temperature of a certain place of the annealing furnace is too high or is adjusted too quickly, it will cause the local flame temperature to rise sharply, thereby promoting the generation of NOx and increasing the emission of nitrogen oxides, which is not conducive to achieving low-nitrogen combustion. SUMMARY

[0004] To solve the technical problem that the independent PID adjustment may cause the temperature of a certain place of the heating section of the annealing furnace to be too high, thereby causing more NOx to be generated, the present application provides solutions in the following aspects.

[0005] In a first aspect, a low-nitrogen combustion control method for an annealing furnace comprises: obtaining the furnace temperature of each heating partition in the heating section of the annealing furnace, wherein the heating section of the annealing furnace comprises a plurality of heating partitions which are sequentially connected in series along the material transmission direction; calculating the PID adjustment coefficient of each heating partition at the current time through a PID algorithm, wherein the PID adjustment coefficient of the i-th heating partition is related to the furnace temperature of the i-th heating partition at each time, i is a positive integer; calculating the global coordination index of each heating partition at the current time, wherein the global coordination index of the i-th heating partition at the current time is related to the PID adjustment coefficient of each heating partition at the current time; determining the target air-fuel ratio and the fuel gas valve opening degree of each heating partition at the current time, and determining the air valve opening degree of each heating partition at the current time according to the target air-fuel ratio and the fuel gas valve opening degree of each heating partition at the current time, wherein for the i-th heating partition, the target air-fuel ratio at the current time is determined according to the PID adjustment coefficient of the i-th heating partition at the current time and the global coordination index of the i-th heating partition at the current time, and the air valve opening degree at the current time is determined according to the target air-fuel ratio at the current time and the fuel gas valve opening degree at the current time. j j j j j ​​​​For each heating zone, the target air-fuel ratio adjustment coefficient at the current moment is inversely proportional to the global coordination index at the current moment, and the gas valve opening at the current moment is directly proportional to the global coordination index at the current moment.

[0006] Preferably, calculate the first j The heating zone is in the first k The formula for the PID control coefficient at time t is: .

[0007] in C j ( k ) is the first j The heating zone is in the first k PID control coefficient at time t, For the preset first j One proportional gain parameter, For the preset first j One integral gain parameter, For the preset first j Each differential gain coefficient e j ( k ) is the first j The heating zone is in the first k The furnace temperature at any given moment e j ( k -1) is the first j The heating zone is in the first k The furnace temperature at time -1 The time interval between two moments. E j For the first j A desired furnace temperature, k It is a positive integer. q Represents an index.

[0008] Preferably, calculate the first j The heating zone is in the first k The formula for the global coordination index at time t is: .

[0009] in, U j ( k ) is the first j The heating zone is in the first k Global coordination index at any given moment. C j+1 ( k ) is the first j +1 heating zone in the k PID control coefficient at time t,C j-1 ( k ) is the first j -1 heating zone in the k The PID control coefficient at time t, the first j The heating zone receives the first j -1 heating zone output material, the first j The heating zone directs to the first j +1 heating zone outputs material ω j,1 , ω j,2 , ω j,3 and ω j,4 All are preset weighting coefficients, and .

[0010] Preferably, calculate the first j The heating zone is in the first k The formula for the target air-fuel ratio at any given time is: ; in, AFR stoich To achieve a preset target air-fuel ratio for theoretical fuel measurement, AFR j ( k ) is the first j The heating zone is in the first k The target air-fuel ratio at any given time α The amplitude coefficient is the preset size and α >0, β The sensitivity adjustment coefficient is set to a preset size and β >0, tanh() is the hyperbolic tangent function.

[0011] Preferably, calculate the first j The heating zone is in the first k The formula for the gas valve opening at any given time is: .

[0012] in, U offset The activation threshold is set to a preset size. V max This represents the maximum opening degree of the gas valve. γ The sigmoid gain parameter is of a preset size, and exp() is an exponential function with the natural constant e as its base.

[0013] Preferably, according to the first j The heating zone is in the first kThe target air-fuel ratio and the gas valve opening at the time instant determine the air valve opening of the first heating zone at the time instant j The target air-fuel ratio and the gas valve opening at the time instant determine the air valve opening of the first heating zone at the time instant k The target air-fuel ratio and the gas valve opening at the time instant determine the air valve opening of the first heating zone at the time instant j The target air-fuel ratio and the gas valve opening at the time instant determine the air valve opening of the first heating zone at the time instant j The target air-fuel ratio and the gas valve opening at the time instant determine the air valve opening of the first heating zone at the time instant k The target air-fuel ratio and the gas valve opening at the time instant determine the air valve opening of the first heating zone at the time instant j The target air-fuel ratio and the gas valve opening at the time instant determine the air valve opening of the first heating zone at the time instant k The target air-fuel ratio and the gas valve opening at the time instant determine the air valve opening of the first heating zone at the time instant j The target air-fuel ratio and the gas valve opening at the time instant determine the air valve opening of the first heating zone at the time instant j The target air-fuel ratio and the gas valve opening at the time instant determine the air valve opening of the first heating zone at the time instant k The target air-fuel ratio and the gas valve opening at the time instant determine the air valve opening of the first heating zone at the time instant

[0014] The target air-fuel ratio and the gas valve opening at the time instant determine the air valve opening of the first heating zone at the time instant j The target air-fuel ratio and the gas valve opening at the time instant determine the air valve opening of the first heating zone at the time instant k The target air-fuel ratio and the gas valve opening at the time instant determine the air valve opening of the first heating zone at the time instant wherein, R j is the target air-fuel ratio of the first heating zone at the time instant, k is the gas flow of the first heating zone at the time instant, j is the target air flow of the first heating zone at the time instant. k j k j k

[0015] The target air-fuel ratio and the gas valve opening at the time instant determine the air valve opening of the first heating zone at the time instant j The target air-fuel ratio and the gas valve opening at the time instant determine the air valve opening of the first heating zone at the time instant j The target air-fuel ratio and the gas valve opening at the time instant determine the air valve opening of the first heating zone at the time instant j The target air-fuel ratio and the gas valve opening at the time instant determine the air valve opening of the first heating zone at the time instant j The target air-fuel ratio and the gas valve opening at the time instant determine the air valve opening of the first heating zone at the time instant

[0016] The target air-fuel ratio and the gas valve opening at the time instant determine the air valve opening of the first heating zone at the time instant j The target air-fuel ratio and the gas valve opening at the time instant determine the air valve opening of the first heating zone at the time instant j The target air-fuel ratio and the gas valve opening at the time instant determine the air valve opening of the first heating zone at the time instant j The target air-fuel ratio and the gas valve opening at the time instant determine the air valve opening of the first heating zone at the time instant j The target air-fuel ratio and the gas valve opening at the time instant determine the air valve opening of the first heating zone at the time instant​​​​​​​

[0017] In a second aspect, a low-nitrogen combustion control system for an annealing furnace includes a processor and a memory having stored therein a computer program, the processor executing the computer program to implement a low-nitrogen combustion control method for an annealing furnace as recited in any one of the SUMMARY.

[0018] The present application has the beneficial effects that: The present application divides the heating section into multiple heating sub-zones in series along the material conveying direction, and respectively collects temperature and performs PID adjustment for each heating sub-zone. The present application avoids excessively high temperature in a single region due to PID over-adjustment by partitioning and cooperatively controlling the heating section, and reduces the generation of thermal NOx from the source. At the same time, a global coordination index is introduced to incorporate the PID adjustment coefficients of the upstream and downstream sub-zones and the overall average level into the correction, avoiding over or under temperature control in a certain region, so that the temperature distribution of the entire heating section is more stable. BRIEF DESCRIPTION OF DRAWINGS

[0019] The above and other objects, features and advantages of the exemplary embodiments of the present application will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: Figure 1 is a step flow chart schematically showing a low-nitrogen combustion control method for an annealing furnace according to an embodiment of the present application; Figure 2 is a structural block diagram schematically showing a low-nitrogen combustion control system for an annealing furnace according to an embodiment of the present application. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings of the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0021] The specific embodiments of the present application will be described in detail below with reference to the drawings.

[0022] Figure 1 is a step flow chart schematically showing a low-nitrogen combustion control method for an annealing furnace according to an embodiment of the present application.

[0023] As Figure 1 shown, a low-nitrogen combustion control method for an annealing furnace includes steps S1 to S5.

[0024] Step S1: Obtain the furnace temperature of each heating zone in the heating section of the annealing furnace.

[0025] The heating section of the annealing furnace includes multiple heating zones connected in series along the material conveying direction.

[0026] It should be noted that within the heating section of the annealing furnace, the entire space is divided into multiple independent heating zones, arranged one after another along the direction of material movement. For example, the material first enters the first heating zone, is heated, leaves the first heating zone and enters the second heating zone, then from the second heating zone to the third heating zone, and so on.

[0027] Step S2: Calculate the PID adjustment coefficient of each heating zone at the current moment using the PID algorithm.

[0028] Among them, the j The PID control coefficient of the heating zone is related to the first heating zone. j The furnace temperature at each heating zone is related to the temperature of the furnace at different times. j It is a positive integer.

[0029] In one embodiment, the calculation of the first j The heating zone is in the first k The formula for the PID control coefficient at time t is: .

[0030] in C j ( k ) is the first j The heating zone is in the first k PID control coefficient at time t, For the preset first j One proportional gain parameter, For the preset first j One integral gain parameter, For the preset first j Each differential gain coefficient e j ( k ) is the first j The heating zone is in the first k The furnace temperature at any given moment e j ( k -1) is the first j The heating zone is in the first k The furnace temperature at time -1 The time interval between two moments. E j For the first j A desired furnace temperature,k It is a positive integer. q Represents an index.

[0031] It should be noted that different heating zones have different expected optimal furnace temperatures. For example, the heating zone near the heating section inlet is responsible for preheating, so its expected optimal furnace temperature is lower; the heating zone in the middle of the heating section needs to quickly raise the material to near the annealing target temperature, so its expected optimal furnace temperature is higher than that of other heating zones; the heating zone near the heating section outlet is used for temperature homogenization, so its expected optimal furnace temperature is lower than that of the heating zone located in the middle of the heating section.

[0032] Among them, the j The optimal furnace temperature for each heating zone is the [missing value]. j The desired furnace temperature is determined by the specific heating zone. Since the desired optimal furnace temperature differs across heating zones, the PID algorithm gain parameters for each zone are different (PID algorithm gain parameters include: proportional gain parameter, integral gain parameter, and derivative gain coefficient). j The PID algorithm gain parameter corresponding to the heating zone is the first... j The first proportional gain parameter, the first j The integral gain parameter and the first j Each differential gain coefficient.

[0033] Furthermore, for any heating zone, the PID algorithm gain parameter has a negative value, and its unit is °C. -1 The unit of the integral gain parameter is ℃. -1 ·s -1 The unit of the differential gain parameter is ℃. -1 •s. The gain parameter of the PID algorithm for any heating zone is an empirical value.

[0034] It should be noted that the calculation of the first... j The heating zone is in the first k In the formula for the PID control coefficient at time t, the proportional part, i.e. For the first k The system reacts instantly to temperature errors at any given time, with the actual temperature (i.e., ) than the expected temperature (i.e. The lower the value, the better. The smaller the value, the larger the value of the proportional part; the integral part, i.e. For the first k The temperature errors of all times prior to time step [time] are accumulated; the differential part, i.e. To predict future temperature error trends. jThe larger the PID control coefficient of a heating zone, the more heat that zone needs to add.

[0035] Step S3: Calculate the global coordination index of each heating zone at the current moment.

[0036] Among them, the j The global coordination index of each heating zone at the current moment is related to the PID control coefficient of each heating zone at the current moment.

[0037] In one embodiment, the calculation of the first j The heating zone is in the first k The formula for the global coordination index at time t is: .

[0038] in, U j ( k ) is the first j The heating zone is in the first k Global coordination index at any given moment. C j+1 ( k ) is the first j +1 heating zone in the k PID control coefficient at time t, C j-1 ( k ) is the first j -1 heating zone in the k The PID control coefficient at time t, the first j The heating zone receives the first j -1 heating zone output material, the first j The heating zone directs to the first j +1 heating zone outputs material ω j,1 , ω j,2 , ω j,3 and ω j,4 All are preset weighting coefficients, and .

[0039] It should be noted that the first j -1 heating zone is the first j The upstream heating zone of the first heating zone; the first j +1 heating zone is the first jThe invention relates to a downstream heating zone of a heating zone. It corrects the PID control coefficients of each heating zone based on the PID control coefficients of the upstream and downstream heating zones, as well as the average of the PID control coefficients of all heating zones. This prevents over- or under-temperature adjustment of the heating zone due to upstream and downstream temperature variations. Simultaneously, the PID control parameters of each heating zone are referenced to the overall average level, preventing any particular heating zone's PID control parameter from being too large or too small. This helps the control system converge faster and reduces temperature fluctuations. Based on this, adjusting the temperature of the heating zone according to the global coordination index prevents the temperature from becoming too high or too low, and also prevents excessively rapid temperature changes. This avoids excessive NOx gas generation in the annealing furnace due to the heating zone temperature exceeding the desired temperature by a large margin.

[0040] Step S4: Determine the target air-fuel ratio and gas valve opening for each heating zone at the current moment.

[0041] Among them, for the first j For each heating zone, the target air-fuel ratio adjustment coefficient at the current moment is inversely proportional to the global coordination index at the current moment, and the gas valve opening at the current moment is directly proportional to the global coordination index at the current moment.

[0042] In one embodiment, the calculation of the first j The heating zone is in the first k The formula for the target air-fuel ratio at any given time is: .

[0043] in, AFR stoich To achieve a preset target air-fuel ratio for theoretical fuel measurement, AFR j ( k ) is the first j The heating zone is in the first k The target air-fuel ratio at any given time α The amplitude coefficient is the preset size and α >0, β The sensitivity adjustment coefficient is set to a preset size and β >0, tanh() is the hyperbolic tangent function.

[0044] It should be noted that when the first j The heating zone is in the first k The global coordination index at time t, i.e. U j ( k The larger value indicates that for the first... j The desired temperature for the heating zone is relatively high, at which point the... jThe combustion load required by each heating zone is large. In order to ensure stable combustion and complete burning of fuel to avoid generation of more NOx gas, the target air-fuel ratio of the first heating zone at the first time is large. j k

[0045] In one embodiment, the formula for calculating the gas valve opening degree of the first heating zone at the first time is: j k .

[0046] wherein, U offset is a preset size of an activation threshold, V max is a maximum opening degree of the gas valve, γ is a preset size of a Sigmoid gain parameter, and exp() is an exponential function with a natural constant e as the base.

[0047] It should be noted that the formula for calculating the gas valve opening degree of the first heating zone at the first time is a Sigmoid function, and the activation threshold j k determines the center point position of the Sigmoid function curve, and the Sigmoid gain parameter U offset determines the steepness of the Sigmoid function curve. The values of the activation threshold γ U offset and the Sigmoid gain parameter γ are empirical values.

[0048] Step S5: determining the air valve opening degree of each heating zone at the current time according to the target air-fuel ratio and the gas valve opening degree of each heating zone at the current time.

[0049] In one embodiment, determining the air valve opening degree of the first heating zone at the first time according to the target air-fuel ratio and the gas valve opening degree of the first heating zone at the first time includes: converting the target air-fuel ratio gas valve opening degree of the first heating zone at the first time into a gas flow rate through a preset first gas flow rate-valve opening degree characteristic curve; calculating a target air flow rate according to the target air-fuel ratio of the first heating zone at the first time and the gas flow rate; and converting the target air flow rate into an air valve opening degree through a preset first air flow rate-valve opening degree characteristic curve. j k j k j j k j k j In one embodiment, determining the air valve opening degree of the first heating zone at the first time according to the target air-fuel ratio and the gas valve opening degree of the first heating zone at the first time includes: converting the target air-fuel ratio gas valve opening degree of the first heating zone at the first time into a gas flow rate through a preset first gas flow rate-valve opening degree characteristic curve; calculating a target air flow rate according to the target air-fuel ratio of the first heating zone at the first time and the gas flow rate; and converting the target air flow rate into an air valve opening degree through a preset first air flow rate-valve opening degree characteristic curve.​​​​​​​​​​​​​​​j the target air flow of the first heating zone at the first time instant is converted into an air valve opening degree. k

[0050] In one embodiment, the formula for calculating the target air flow from the target air-fuel ratio of the first heating zone at the first time instant and the fuel gas flow is: j k wherein, R j k is the target air-fuel ratio of the first heating zone at the first time instant, j is the fuel gas flow of the first heating zone at the first time instant, k is the target air flow of the first heating zone at the first time instant. j k j k

[0051] In one embodiment, obtaining the first fuel gas flow-valve opening degree characteristic curve comprises: obtaining a plurality of sampling points of the fuel gas valve of the first heating zone, wherein the sampling points of the fuel gas valve comprise the opening degree of the fuel gas valve and the fuel gas flow; and fitting the plurality of sampling points of the fuel gas valve of the first heating zone to obtain the first fuel gas flow-valve opening degree characteristic curve. j j In one embodiment, obtaining the first air flow-valve opening degree characteristic curve comprises: obtaining a plurality of sampling points of the air valve of the first heating zone, wherein the sampling points of the air valve comprise the opening degree of the air valve and the air flow; and fitting the plurality of sampling points of the air valve of the first heating zone to obtain the first air flow-valve opening degree characteristic curve. j j

[0052] It should be noted that, since the actual flow of the fuel gas valve and the air valve at different opening degrees is not strictly linearly related to the valve opening degree, it is necessary to determine the actual flow through sampling points in advance, and to obtain the corresponding characteristic curve of each fuel gas valve or air valve through fitting. j j j j

[0053] It should be noted that, since the actual flow of the fuel gas valve and the air valve at different opening degrees is not strictly linearly related to the valve opening degree, it is necessary to determine the actual flow through sampling points in advance, and to obtain the corresponding characteristic curve of each fuel gas valve or air valve through fitting.

[0054] Figure 2 is a structural block diagram schematically showing a low-nitrogen combustion control system for an annealing furnace according to one of the embodiments.

[0055] The application also provides a low-nitrogen combustion control system for an annealing furnace. As shown in​​​​​​​​​​​​​​​​​Figure 2 As shown, the system comprises a processor and a memory having computer program instructions stored therein, which when executed by the processor implement a low nitrogen combustion control method for an annealing furnace according to the first aspect of the present application.

[0056] The system further comprises other components such as communication interface and the like, which are well known to those skilled in the art, and their settings and functions are known in the art, thus not described here in detail.

[0057] In the present application, the aforementioned memory can be any tangible medium that contains or stores a program that can be used by or in connection with an instruction execution system, apparatus, or device. For example, the computer-readable storage medium can be any suitable magnetic storage medium or magneto-optical storage medium, such as Resistive Random Access Memory (RRAM), Dynamic Random Access Memory (DRAM), Static Random-Access Memory (SRAM), Enhanced Dynamic Random Access Memory (EDRAM), High-Bandwidth Memory (HBM), Hybrid Memory Cube (HMC), and the like, or any other medium that can be used to store the desired information and that can be accessed by an application, module, or both. Any such computer storage media can be part of the device or accessible or connectable thereto. Any applications or modules described in the present application can be implemented using computer-readable / executable instructions that can be stored or otherwise held by such computer-readable media.

[0058] In the description of the present specification, the meaning of "a plurality of", "several" is at least two, such as two, three or more, and the like, unless otherwise explicitly specified.

[0059] Although the present specification has shown and described a number of embodiments of the present application, it will be apparent to those skilled in the art that many modifications, changes and substitutions can be made thereto without departing from the spirit and scope of the present application. It is to be understood that various alternatives to the embodiments of the application described herein can be employed in practicing the present application.

Claims

1. A low-nitrogen combustion control method for an annealing furnace, characterized by, Comprising: obtaining the hearth temperature of each heating sub-zone in a heating section of the annealing furnace, wherein the heating section of the annealing furnace comprises a plurality of heating sub-zones connected in series along a material conveying direction; PID adjustment coefficients of each heating sub-zone at the current time are calculated by the PID algorithm, wherein the PID adjustment coefficient of the first heating sub-zone is related to the furnace temperature of the first heating sub-zone at each time, the PID adjustment coefficient of the second heating sub-zone is related to the furnace temperature of the second heating sub-zone at each time, and the PID adjustment coefficient of the nth heating sub-zone is related to the furnace temperature of the nth heating sub-zone at each time. j j j is a positive integer.​​ calculating the global coordination index of each heating subzone at the current time, wherein the global coordination index of the i-th heating subzone at the current time is related to the PID regulation coefficient of each heating subzone at the current time; j calculating the global coordination index of each heating subzone at the current time, wherein the global coordination index of the i-th heating subzone at the current time is related to the PID regulation coefficient of each heating subzone at the current time; The target air-fuel ratio and the fuel valve opening degree of each heating sub-zone at the current time are determined, and the air valve opening degree of each heating sub-zone at the current time is determined according to the target air-fuel ratio and the fuel valve opening degree of each heating sub-zone at the current time, wherein for the first heating sub-zone, the target air-fuel ratio adjustment coefficient at the current time is inversely proportional to the global coordination index at the current time, and the fuel valve opening degree at the current time is proportional to the global coordination index at the current time. j ​ 2. The low nitrogen combustion control method for an annealing furnace according to claim 1, characterized by, The formula for calculating the PID regulation coefficient of the first heating zone at the first moment of time is: j The formula for calculating the PID regulation coefficient of the first heating zone at the first moment of time is: k The formula for calculating the PID regulation coefficient of the first heating zone at the first ； in C j ( k ) is the first j The heating zone is in the first k PID control coefficient at time t, For the preset first j One proportional gain parameter, For the preset first j One integral gain parameter, For the preset first j Each differential gain coefficient e j ( k ) is the first j The heating zone is in the first k The furnace temperature at any given moment e j ( k -1) is the first j The heating zone is in the first k The furnace temperature at time -1 The time interval between two moments. E j For the first j A desired furnace temperature, k It is a positive integer. q Represents an index.

3. The low nitrogen combustion control method for an annealing furnace according to claim 2, wherein The formula for the global coordination index of the nth heating zone at the mth moment is: j k The formula for the global coordination index of the nth heating zone at the mth moment is:​ ； wherein, U j k is a global coordination index of the first heating sub-zone at the first time point, j k C j+1 k is a PID adjustment coefficient of the first heating sub-zone at the second time point, j k C j-1 k is a PID adjustment coefficient of the first heating sub-zone at the third time point, j k j j j j ω j,1 ω j,2 ω j,3 ω j,4 are preset weight coefficients, and .​​​​​​​​​​​​​​​​ 4. The low nitrogen combustion control method for an annealing furnace according to claim 3, characterized by, The formula for calculating the target air-fuel ratio of the first heating zone at the first time point is: j The formula for calculating the target air-fuel ratio of the first heating zone at the first time point is: k The formula for calculating the target air-fuel ratio of the ； wherein, AFR stoich a fuel theoretical metering target air-fuel ratio of a preset size, AFR j ( k ) a target air-fuel ratio of the first j heating zone at the first k time, α a magnitude coefficient of a preset size and α > 0, β a sensitivity adjustment coefficient of a preset size and β > 0, tanh() is a hyperbolic tangent function.

5. The low NOx combustion control method for an annealing furnace according to claim 4, wherein The formula for calculating the gas valve opening of the first heating zone at the first time point is: j The formula for calculating the gas valve opening of the second heating zone at the second time point is: k The formula for calculating the gas valve opening of the third heating zone at the third time point is: ； wherein, U offset is a preset size of an activation threshold, V max is a maximum opening of the gas valve, γ is a preset size of a Sigmoid gain parameter, exp() is an exponential function with base of natural constant e.

6. The low NOx combustion control method for an annealing furnace according to claim 1, wherein According to the j The heating zone is in the first k The target air-fuel ratio and gas valve opening at each moment are determined. j The heating zone is in the first k The air valve opening at any given time includes: Through the preset first j The gas flow-valve opening characteristic curve will be the first j The heating zone is in the first k The target air-fuel ratio and gas valve opening at any given time are converted into gas flow rate. According to the first j The target air flow is calculated according to the target air-fuel ratio of the first k heating zone at the first moment and the fuel gas flow. The first air flow-valve opening characteristic curve is preset j The first heating zone is converted into an air valve opening by the first air flow-valve opening characteristic curve at the first time point j The first heating zone is converted into an air valve opening by the first air flow-valve opening characteristic curve at the first time point k The first heating zone is converted into an air valve opening by the first air flow-valve opening characteristic curve at the first time point 7. A low-nitrogen combustion control method for an annealing furnace according to claim 6, characterized by, According to the first j heating zone at the first k moment, and the gas flow of the formula for calculating the target air flow is: Wherein, R j ( k ) is the target air-fuel ratio of the first j heating zone at the first k moment, is the gas flow of the first j heating zone at the first k moment, is the target air flow of the first j heating zone at the first k moment.

8. The low NOx combustion control method for an annealing furnace according to claim 6, wherein Obtain the first j The gas flow rate-valve opening characteristic curve includes: Obtain the j Multiple sampling points of gas valves in each heating zone, where the sampling points of gas valves include the opening degree of gas valves and gas flow rate; For the first j The gas valves of each heating zone are fitted using multiple sampling points to obtain the first... j A gas flow rate-valve opening characteristic curve.

9. The low NOx combustion control method for an annealing furnace according to claim 6, wherein Obtain the first j The airflow-valve opening characteristic curve includes: Obtain the j Multiple sampling points of air valves in each heating zone, where the sampling points of air valves include the opening degree of air valves and air flow rate; For the first j The air valves of each heating zone are fitted together using multiple sampling points to obtain the first... j An airflow-valve opening characteristic curve.

10. A low nitrogen combustion control system for an annealing furnace, comprising a processor and a memory, characterized in that, The memory stores a computer program, and the processor executes the computer program to implement the low-nitrogen combustion control method for the annealing furnace according to any one of claims 1-9.

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