A method for automatically compensating for oxygen content control to adjust the air-fuel ratio of a heating furnace

Abstract

This invention discloses a method for automatically compensating for oxygen content and controlling the air-fuel ratio of a heating furnace. Based on the oxygen content-combustion load curve, the input variables are determined, the oxygen content compensation coefficient is calculated, and the target oxygen content value is obtained. The oxygen content is then compensated, and subsequently, the target air-fuel ratio value, the air volume required for burner combustion, and the required fuel gas volume are calculated. The air and fuel gas volumes of the heating furnace are adjusted in real time. This method automatically compensates for oxygen content and adjusts the air-fuel ratio in real time during the combustion process, precisely controlling the combustion ratio and dynamically controlling the air and fuel gas volumes. This ensures that the heating furnace maintains optimal combustion conditions, guaranteeing stable and high-efficiency combustion while saving fuel gas consumption and air overflow. It also reduces energy waste caused by excessively high oxygen content, lowers the load on the combustion fan and exhaust fan, and achieves energy saving and emission reduction.

Description

Technical Field

[0001] This invention relates to the technical field of combustion control system for annealing furnaces in stainless steel cold rolling production lines, and particularly to a method for automatically compensating for oxygen content and adjusting the air-fuel ratio of the heating furnace. Background Technology

[0002] In the continuous rolling annealing and pickling line of the cold rolling DRAPL unit, the heating equipment used for stainless steel annealing is a natural gas heater. When heating stainless steel strip in a natural gas heater, controlling the oxygen content and air-fuel ratio during combustion is crucial. A high oxygen content and air-fuel ratio increase the required air volume for combustion, leading to increased consumption of air in the natural gas heater and a higher load on the combustion air motor. It also results in excessive oxidation of the stainless steel strip surface. Conversely, a low oxygen content and air-fuel ratio cause incomplete combustion, uneven heating of the stainless steel strip, and residual oxygen. However, the required oxygen content and air-fuel ratio vary in different temperature zones within the heater, such as the high-temperature and low-temperature sections. Targeted and precise control of the oxygen content and air-fuel ratio in each temperature zone is inherently difficult. Furthermore, the inherent oxidation resistance of stainless steel, along with the influence of production line speed, combustion load, and errors in gas and air flow, means that the actual oxygen content and air-fuel ratio within the heater furnace are not constant but fluctuate within a certain range, further complicating the control of gas and air supply.

[0003] Currently, the control of oxygen content and air-fuel ratio in heating furnaces is done manually. Specifically, the oxygen content is manually set, and the gas and air supply is determined. For a certain period during the heating process, the gas and air are supplied at a constant oxygen content. Manually adjusting the oxygen content and air-fuel ratio for each temperature zone of the heating furnace is not only cumbersome and inefficient, but also results in fluctuations in the actual oxygen content and air-fuel ratio within the furnace chamber, even after a constant gas and air supply. These fluctuations tend to be too high or too low, making it difficult to maintain optimal values ​​and thus affecting the annealing quality of stainless steel. Furthermore, manual settings are prone to human error, particularly the oversight of factors such as combustion load, leading to inaccurate control of oxygen content and air-fuel ratio, which can cause problems with stainless steel quality and furnace gas consumption. Summary of the Invention

[0004] The purpose of this invention is to provide a method for automatically compensating for oxygen content and controlling the air-fuel ratio of a heating furnace.

[0005] The technical solution to achieve the objective of this invention is: a method for automatically compensating for oxygen content and controlling the air-fuel ratio of a heating furnace, comprising the following steps:

[0006] S1. Through testing, determine the correspondence between burner combustion load and oxygen content under suitable combustion conditions in the heating furnace, and establish an oxygen content-combustion load curve; the oxygen content-combustion load curve refers to the curve of oxygen content changing with combustion load under suitable combustion conditions in the heating furnace.

[0007] S2. Parameters during the heating process of the heating furnace are measured in real time. These parameters include natural gas flow rate, air flow rate, burner combustion load, and oxygen content process value. The real-time measured natural gas flow rate is Gq1; the real-time measured air flow rate is Aq1; and the real-time measured oxygen content process value is O2pv1.

[0008] S3. Referring to the real-time measured burner combustion load, the operator manually inputs the set oxygen content, which is O2sp1;

[0009] S4. Based on the oxygen content-combustion load curve, confirm the oxygen content of the furnace under suitable combustion conditions corresponding to the burner combustion load measured in real time. The oxygen content of the furnace under suitable combustion conditions corresponding to the burner combustion load measured in real time is O2sp2.

[0010] S5. Compare O2sp1 and O2sp2, and use the larger value of O2sp1 and O2sp2 as the input variable for compensation control. The input variable for compensation control is O2max.

[0011] S6. Based on the real-time measured oxygen content process value, a control signal is calculated and output by a PID controller; the PID controller calculates and outputs the control signal u(t), and the calculation formula used by the PID controller to calculate the control signal is u(t) = Kp*e(t) + Ki*∫e(t)dt + Kd*(de(t) / dt)+Disv; where e(t) is the difference between O2sp1 and O2pv1, Kp is the proportional coefficient, Ki is the integral coefficient, Kd is the derivative coefficient, and Disv is the disturbance variable. Kp, Ki, Kd, ​​and Disv are all determined by experimental data;

[0012] S7. The oxygen content compensation coefficient is fx, which is determined by the following formula: fx=η*u(t) + β; where β is the regression coefficient and η is the oxygen content compensation efficiency factor; both β and η are determined by experimental data;

[0013] S8. The target oxygen content is O2. SP Calculate the target oxygen content using the following formula: O2 SP = fx*O2max; The target oxygen content value refers to the value of the oxygen content to be adjusted;

[0014] S9. The target air-fuel ratio is Vae. Calculate the target air-fuel ratio using the following formula: Vae = (O2) SP / (21.0-O2 SP )*Vf+1)*Va; where Vf and Va are heating parameters determined based on the composition of natural gas;

[0015] S10. The amount of air required for burner combustion is Aq, and the amount of fuel gas required is Gq. Calculate the amount of air required for burner combustion and the amount of fuel gas required according to the following formulas: Aq=Vae*Gq1, Gq= Aq1 / Vae;

[0016] S11. Based on the amount of air and gas required for combustion, control the air flow valve and gas flow valve of the heating furnace to adjust the amount of air and gas in the heating furnace in real time.

[0017] Furthermore, the heating furnace includes four heating sections arranged sequentially along the stainless steel conveying direction, namely Zone 1, Zone 2, Zone 3, and Zone 4. When controlling the air-fuel ratio in Zone 1, η = 0.75 and β = 1 in step S7; when controlling the air-fuel ratio in Zone 2, η = 0.35 and β = 1 in step S7; when controlling the air-fuel ratio in Zone 3, η = 0.3 and β = 1 in step S7; and when controlling the air-fuel ratio in Zone 4, η = 0.7 and β = 1 in step S7.

[0018] Furthermore, in step S9, Vf = 8.810542, Va = 9.835623.

[0019] This invention discloses a method for automatically compensating for oxygen content and controlling the air-fuel ratio in a heating furnace. During combustion, the oxygen content is automatically compensated, and the air-fuel ratio is adjusted in real time. This allows for precise control of the combustion mix and dynamic control of the air and fuel flow in the furnace, ensuring optimal combustion conditions. This guarantees stable and efficient combustion while also saving fuel consumption and reducing air overflow. It minimizes energy waste caused by excessive oxygen content, reduces the load on the combustion fan and exhaust fan, achieving energy conservation, emission reduction, and reduced environmental pollution. Our company has reduced natural gas consumption per ton of steel by 0.5 m³ after implementing this method. 3 / t~1.0m 3 / t, the electricity consumption of the combustion fan and exhaust fan is reduced by 0.7KW / t, resulting in an annual saving of approximately 4 million yuan in natural gas costs and approximately 400,000 yuan in electricity costs.

[0020] The present invention provides a method for automatically compensating for oxygen content to control and adjust the air-fuel ratio of a heating furnace. Compared with the traditional manual adjustment method, which is cumbersome, inefficient, and prone to human error, this method achieves dynamic adjustment of the air-fuel ratio by automatically compensating for oxygen content. It eliminates the need for frequent and multiple manual adjustments, making the operation simple, time-saving, and labor-saving. Furthermore, the real-time automatic adjustment can effectively avoid the untimely nature and human error of manual operation, ensuring the real-time performance and accuracy of the adjustment.

[0021] The present invention provides a method for automatically compensating for oxygen content to control and adjust the air-fuel ratio of a heating furnace. During the oxygen content compensation process, the calculation variables are taken from three related values ​​of oxygen content. The operator manually inputs the set oxygen content (i.e., O2sp1), the real-time measured process value of oxygen content (i.e., O2pv1), and the real-time measured oxygen content under the suitable combustion state of the heating furnace corresponding to the burner combustion load (i.e., O2sp2), rather than other unrelated variables, which ensures the accuracy of the adjustment. Furthermore, the PID controller uses the following formula to calculate the control signal: u(t) = Kp*e(t) + Ki*∫e(t)dt + Kd*(de(t) / dt)+Disv. This formula includes proportional, integral, and derivative adjustments. These three adjustments work together. When the difference between O2sp1 and O2pv1 is large, the proportional coefficient plays a major role; when the difference between O2sp1 and O2pv1 is small but persistent, the integral coefficient gradually takes effect; and when the rate of change of the difference between O2sp1 and O2pv1 is too large, the derivative coefficient takes effect. In other words, control that includes proportional, integral, and derivative adjustments can adapt to various situations and is effective in all situations. Furthermore, when calculating the target oxygen content, this invention also uses the larger of O2sp1 and O2sp2 as the input variable for compensation control, so that the air supply is slightly larger, to prevent insufficient combustion during low-temperature combustion and to ensure that the residual gas from incomplete combustion can still be completely burned. This makes the application of this invention more comprehensive and the application effect better. Attached Figure Description

[0022] Figure 1 This invention relates to an oxygen content-combustion load curve diagram for automatic oxygen content compensation control and adjustment of the air-fuel ratio in a heating furnace. In the diagram, the line containing the circular measuring point is the oxygen content-combustion load curve for the high-temperature section of the heating furnace; the line containing the square measuring point is the oxygen content-combustion load curve for the low-temperature section of the heating furnace; and the line containing the triangular measuring point is the oxygen content-combustion load curve diagram after the operator manually inputs and sets the oxygen content.

[0023] Figure 2 This is a flowchart of the method for automatically compensating for oxygen content and controlling the air-fuel ratio of a heating furnace according to the present invention. Implementation

[0024] The preferred embodiment of the method for automatically compensating for oxygen content and controlling the air-fuel ratio of a heating furnace according to the present invention will be described in detail below with reference to the accompanying drawings:

[0025] A method for automatically compensating for oxygen content and controlling the air-fuel ratio of a heating furnace includes the following steps:

[0026] S1. Through testing, determine the correspondence between burner combustion load and oxygen content under suitable combustion conditions in the heating furnace, and establish an oxygen content-combustion load curve; the oxygen content-combustion load curve refers to the curve of oxygen content changing with combustion load under suitable combustion conditions in the heating furnace.

[0027] S2. Parameters during the heating process of the heating furnace are measured in real time. These parameters include natural gas flow rate, air flow rate, burner combustion load, and oxygen content process value. The real-time measured natural gas flow rate is Gq1; the real-time measured air flow rate is Aq1; and the real-time measured oxygen content process value is O2pv1.

[0028] S3. Referring to the real-time measured burner combustion load, the operator manually inputs the set oxygen content based on experience. The set oxygen content is O2sp1.

[0029] S4. Based on the oxygen content-combustion load curve, confirm the oxygen content of the furnace under suitable combustion conditions corresponding to the burner combustion load measured in real time. The oxygen content of the furnace under suitable combustion conditions corresponding to the burner combustion load measured in real time is O2sp2.

[0030] S5. Compare O2sp1 and O2sp2, and use the larger value of O2sp1 and O2sp2 as the input variable for compensation control. The input variable for compensation control is O2max.

[0031] S6. Based on the real-time measured oxygen content process value, a control signal is calculated and output by a PID controller; the PID controller calculates and outputs the control signal u(t), and the calculation formula used by the PID controller to calculate the control signal is u(t) = Kp*e(t) + Ki*∫e(t)dt + Kd*(de(t) / dt)+Disv; where e(t) is the difference between O2sp1 and O2pv1, Kp is the proportional coefficient, Ki is the integral coefficient, Kd is the derivative coefficient, and Disv is the disturbance variable. Kp, Ki, Kd, ​​and Disv are all determined by experimental data;

[0032] S7. The oxygen content compensation coefficient is fx, which is determined by the following formula: fx=η*u(t) + β; where β is the regression coefficient and η is the oxygen content compensation efficiency factor; both β and η are determined by experimental data;

[0033] S8. The target oxygen content is O2. SP Calculate the target oxygen content using the following formula: O2 SP = fx*O2max; The target oxygen content value refers to the value of the oxygen content to be adjusted;

[0034] S9. The target air-fuel ratio is Vae. Calculate the target air-fuel ratio using the following formula: Vae = (O2) SP / (21.0-O2 SP )*Vf+1)*Va; where Vf and Va are heating parameters determined based on the composition of natural gas;

[0035] S10. The amount of air required for burner combustion is Aq, and the amount of fuel gas required is Gq. Calculate the amount of air required for burner combustion and the amount of fuel gas required according to the following formulas: Aq=Vae*Gq1, Gq= Aq1 / Vae;

[0036] S11. Based on the amount of air and gas required for combustion, control the air flow valve and gas flow valve of the heating furnace to adjust the amount of air and gas in the heating furnace in real time.

[0037] The present invention relates to a method for automatically compensating for oxygen content and controlling the air-fuel ratio of a heating furnace. During the heating and annealing process of stainless steel strip in the heating furnace, the burner combustion load can be selected according to the amount of stainless steel strip fed into the heating furnace. After selecting the burner combustion load, combustion-related parameters such as natural gas flow rate, air flow rate, burner combustion load, oxygen content, and furnace temperature can all be measured during combustion.

[0038] This invention discloses a method for automatically compensating for oxygen content and controlling the air-fuel ratio in a heating furnace. During the heating and annealing of stainless steel strip in the furnace, the burner combustion load can be gradually increased from zero to 100%. After each adjustment of the burner combustion load, different natural gas and air flow rates can be supplied. Under different oxygen contents, the annealing quality of the stainless steel strip is assessed. Based on the annealing quality of the stainless steel strip, the correspondence between burner combustion load and oxygen content under suitable combustion conditions in the heating furnace can be determined. Thus, by gradually increasing the burner combustion load from zero to 100%, and determining the correspondence between the combustion load of different burners and oxygen content under suitable combustion conditions in the heating furnace, an oxygen content-combustion load curve can be established. After establishing the oxygen content-combustion load curve, for each burner combustion load, the corresponding oxygen content that allows the heating furnace to operate under suitable combustion conditions can be found according to the oxygen content-combustion load curve.

[0039] The present invention relates to a method for automatically compensating for oxygen content and controlling the air-fuel ratio of a heating furnace. After the burner combustion load is measured in real time, the operator manually inputs the set oxygen content based on experience. After the operator manually inputs the set oxygen content based on experience, the heating furnace starts combustion and, in the initial stage of combustion, combustion is carried out according to the set oxygen content manually input by the operator.

[0040] This invention discloses a method for automatically compensating for oxygen content and controlling the air-fuel ratio in a heating furnace. After combustion in the furnace, the oxygen content has three relevant values: the oxygen content manually input by the operator (O2sp1); the real-time measured oxygen content process value (O2pv1); and the real-time measured oxygen content under suitable combustion conditions corresponding to the burner combustion load (O2sp2). During combustion in the furnace, these three relevant oxygen content values ​​are substituted into the following formula to automatically compensate for the oxygen content: O2 SP = fx*O2max. In this formula, O2max is the input variable for compensation control, and O2max is taken from the larger value between O2sp1 and O2sp2; fx is the oxygen content compensation coefficient, fx=η*u(t) + β, u(t) = Kp*e(t) + Ki*∫e(t)dt+ Kd*(de(t) / dt)+Disv, e(t) is the difference between O2sp1 and O2pv1, that is, fx is also calculated by substituting O2sp1 and O2pv1 into the formula.

[0041] The present invention relates to a method for automatically compensating for oxygen content and controlling the air-fuel ratio of a heating furnace. In the formulas fx=η*u(t) + β and u(t) = Kp*e(t) + Ki*∫e(t)dt + Kd*(de(t) / dt)+Disv, β, η, Kp, Ki, Kd and Disv can all be determined by experimental data.

[0042] This invention relates to a method for automatically compensating for oxygen content and controlling the air-fuel ratio of a heating furnace, such as... Figure 2 As shown, after compensating for the oxygen content, the target air-fuel ratio, the amount of air required for burner combustion, and the amount of fuel gas required can be calculated sequentially, where Vae = (O2) SP / (21.0-O2 SP The formula is: Aq = Vae * Gq1, Gq = Aq1 / Vae. After obtaining the required air and gas flow rates for burner combustion, the air and gas flow rates of the heating furnace can be adjusted in real time by controlling the air and gas flow valves.

[0043] This invention relates to a method for automatically compensating for oxygen content and controlling the air-fuel ratio of a heating furnace, using the formula Vae=(O2) SP / (21.0-O2 SPIn Vf+1)Va, Vf and Va can be determined based on the composition of natural gas.

[0044] This invention discloses a method for automatically compensating for oxygen content and controlling the air-fuel ratio in a heating furnace. During combustion, the oxygen content is automatically compensated, and the air-fuel ratio is adjusted in real time. This allows for precise control of the combustion mix and dynamic control of the air and fuel flow in the furnace, ensuring optimal combustion conditions. This guarantees stable and efficient combustion while also saving fuel consumption and reducing air overflow. It minimizes energy waste caused by excessive oxygen content, reduces the load on the combustion fan and exhaust fan, achieving energy conservation, emission reduction, and reduced environmental pollution. Our company has reduced natural gas consumption per ton of steel by 0.5 m³ after implementing this method. 3 / t~1.0m 3 / t, the electricity consumption of the combustion fan and exhaust fan is reduced by 0.7KW / t, resulting in an annual saving of approximately 4 million yuan in natural gas costs and approximately 400,000 yuan in electricity costs.

[0045] The present invention provides a method for automatically compensating for oxygen content to control and adjust the air-fuel ratio of a heating furnace. Compared with the traditional manual adjustment method, which is cumbersome, inefficient, and prone to human error, this method achieves dynamic adjustment of the air-fuel ratio by automatically compensating for oxygen content. It eliminates the need for frequent and multiple manual adjustments, making the operation simple, time-saving, and labor-saving. Furthermore, the real-time automatic adjustment can effectively avoid the untimely nature and human error of manual operation, ensuring the real-time performance and accuracy of the adjustment.

[0046] The present invention provides a method for automatically compensating for oxygen content to control and adjust the air-fuel ratio of a heating furnace. During the oxygen content compensation process, the calculation variables are taken from three related values ​​of oxygen content. The operator manually inputs the set oxygen content (i.e., O2sp1), the real-time measured process value of oxygen content (i.e., O2pv1), and the real-time measured oxygen content under the suitable combustion state of the heating furnace corresponding to the burner combustion load (i.e., O2sp2), rather than other unrelated variables, which ensures the accuracy of the adjustment. Furthermore, the PID controller uses the following formula to calculate the control signal: u(t) = Kp*e(t) + Ki*∫e(t)dt + Kd*(de(t) / dt)+Disv. This formula includes proportional, integral, and derivative adjustments. These three adjustments work together. When the difference between O2sp1 and O2pv1 is large, the proportional coefficient plays a major role; when the difference between O2sp1 and O2pv1 is small but persistent, the integral coefficient gradually takes effect; and when the rate of change of the difference between O2sp1 and O2pv1 is too large, the derivative coefficient takes effect. In other words, control that includes proportional, integral, and derivative adjustments can adapt to various situations and is effective in all situations. Furthermore, when calculating the target oxygen content, this invention also uses the larger of O2sp1 and O2sp2 as the input variable for compensation control, so that the air supply is slightly larger, to prevent insufficient combustion during low-temperature combustion and to ensure that the residual gas from incomplete combustion can still be completely burned. This makes the application of this invention more comprehensive and the application effect better.

[0047] This invention discloses a method for automatically compensating for oxygen content and controlling the air-fuel ratio of a heating furnace. The heating furnace may include, but is not limited to, four heating sections sequentially distributed along the stainless steel conveying direction, namely Zone 1, Zone 2, Zone 3, and Zone 4. Furthermore, the values ​​of η and β in step S7 may be, but are not limited to, as follows: when controlling the air-fuel ratio in Zone 1, η = 0.75 and β = 1 in step S7; when controlling the air-fuel ratio in Zone 2, η = 0.35 and β = 1 in step S7; when controlling the air-fuel ratio in Zone 3, η = 0.3 and β = 1 in step S7; and when controlling the air-fuel ratio in Zone 4, η = 0.7 and β = 1 in step S7.

[0048] In the method for automatically compensating for oxygen content and controlling the air-fuel ratio of a heating furnace according to the present invention, in step S9, the values ​​of Vf and Va can be, but are not limited to, Vf=8.810542, Va=9.835623. When Vf=8.810542 and Va=9.835623, high-precision adjustment can be achieved, and the air-fuel ratio control is more accurate.

[0049] For those skilled in the art, without departing from the concept of this invention, several simple deductions or substitutions can be made, and all such deductions or substitutions should be considered to fall within the scope of protection of this invention.

Claims

1. A method for automatically compensating for oxygen content and controlling the air-fuel ratio of a heating furnace, characterized in that: Includes the following steps: S1. Through testing, determine the correspondence between burner combustion load and oxygen content under suitable combustion conditions in the heating furnace, and establish an oxygen content-combustion load curve; the oxygen content-combustion load curve refers to the curve of oxygen content changing with combustion load under suitable combustion conditions in the heating furnace. S2. Parameters during the heating process of the heating furnace are measured in real time. These parameters include natural gas flow rate, air flow rate, burner combustion load, and oxygen content process value. The real-time measured natural gas flow rate is Gq1; the real-time measured air flow rate is Aq1; and the real-time measured oxygen content process value is O2pv1. S3. Referring to the real-time measured burner combustion load, the operator manually inputs the set oxygen content, which is O2sp1; S4. Based on the oxygen content-combustion load curve, confirm the oxygen content of the furnace under suitable combustion conditions corresponding to the burner combustion load measured in real time. The oxygen content of the furnace under suitable combustion conditions corresponding to the burner combustion load measured in real time is O2sp2. S5. Compare O2sp1 and O2sp2, and use the larger value of O2sp1 and O2sp2 as the input variable for compensation control. The input variable for compensation control is O2max. S6. Based on the real-time measured oxygen content process value, a control signal is calculated and output by a PID controller; the PID controller calculates and outputs the control signal u(t), and the calculation formula used by the PID controller to calculate the control signal is u(t) = Kp*e(t) + Ki*∫e(t)dt + Kd*(de(t) / dt)+Disv; where e(t) is the difference between O2sp1 and O2pv1, Kp is the proportional coefficient, Ki is the integral coefficient, Kd is the derivative coefficient, and Disv is the disturbance variable. Kp, Ki, Kd, ​​and Disv are all determined by experimental data; S7. The oxygen content compensation coefficient is fx, which is determined by the following formula: fx=η*u(t) + β; where β is the regression coefficient and η is the oxygen content compensation efficiency factor; both β and η are determined by experimental data; S8. The target oxygen content is O2. SP Calculate the target oxygen content using the following formula: O2 SP = fx*O2max; The target oxygen content value refers to the value of the oxygen content to be adjusted; S9. The target air-fuel ratio is Vae. Calculate the target air-fuel ratio using the following formula: Vae = (O2) SP / (21.0-O2 SP )*Vf+1)*Va; where Vf and Va are heating parameters determined based on the composition of natural gas; S10. The amount of air required for burner combustion is Aq, and the amount of fuel gas required is Gq. Calculate the amount of air required for burner combustion and the amount of fuel gas required according to the following formulas: Aq=Vae*Gq1, Gq= Aq1 / Vae; S11. Based on the amount of air and gas required for combustion, control the air flow valve and gas flow valve of the heating furnace to adjust the amount of air and gas in the heating furnace in real time.

2. The method for automatically compensating for oxygen content and controlling the air-fuel ratio of a heating furnace according to claim 1, characterized in that: The heating furnace includes four heating sections arranged sequentially along the stainless steel conveying direction, namely Zone 1, Zone 2, Zone 3, and Zone 4. When controlling the air-fuel ratio in Zone 1, η = 0.75 and β = 1 in step S7; when controlling the air-fuel ratio in Zone 2, η = 0.35 and β = 1 in step S7; when controlling the air-fuel ratio in Zone 3, η = 0.3 and β = 1 in step S7; and when controlling the air-fuel ratio in Zone 4, η = 0.7 and β = 1 in step S7.

3. The method for automatically compensating for oxygen content and controlling the air-fuel ratio of a heating furnace according to claim 1, characterized in that: In step S9, Vf = 8.810542, Va = 9.835623.

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