A heating furnace oxygen-enriched combustion control system and control method

Abstract

The present application relates to a kind of heating furnace oxygen-enriched combustion control system and control method, belong to steel heating furnace combustion control technical field.System includes heating furnace, mixed coal gas supply branch, air supply branch, oxygen supply branch, calorific value module, working condition acquisition unit, residual oxygen detection unit, mixing module, oxygen-enriched control module and safety module.Calorific value module detects mixed coal gas heat value in real time, oxygen-enriched control module determines theoretical air-fuel ratio accordingly, and air and oxygen supply are adjusted in combination with heating furnace temperature rising rate, combustion pulse load rate, gas load and slab working condition in furnace linkage;Residual oxygen detection signal is used for air-fuel ratio and oxygen-enriched concentration correction in one way, and another way is used for oxygen path safety interlock.The present application improves the adaptability of oxygen-enriched combustion to gas heat value and production load variation, low heat value gas utilization rate and improves combustion control and oxygen path operation safety.

Description

Technical Field

[0001] This invention belongs to the field of combustion control technology for steel rolling furnaces, and relates to an oxygen-enriched combustion control system and control method for a heating furnace. Background Technology

[0002] In the steel rolling process, walking beam furnaces, pusher furnaces, and other similar furnaces typically use one or more of the following as fuel: coke oven gas, blast furnace gas, and natural gas, and use air as a combustion medium to burn the fuel entering the furnace, in order to meet the furnace temperature and heating curve requirements for heating the steel billet.

[0003] With the rising costs of high-calorific-value fuels such as natural gas and coke oven gas, increasing the proportion of relatively low-cost blast furnace gas is an important way to reduce fuel costs for heating furnaces, while ensuring production capacity and billet heating quality. However, blast furnace gas has a relatively low calorific value. When using conventional air-assisted combustion, as the proportion of blast furnace gas in the mixed gas increases, issues such as insufficient flame temperature, decreased heating furnace heating rate, and incomplete combustion can easily occur, limiting the further utilization of blast furnace gas.

[0004] Oxygen-enriched combustion improves the combustion conditions of low-calorific-value coal gas by supplementing the combustion air with oxygen, thereby increasing the oxygen concentration of the combustion medium. However, the combustion load in the actual production process of the heating furnace is not constant; it is affected by various factors such as the calorific value of the coal gas, the charging and unloading rhythm, the quantity and position of slabs in the furnace, the rate of change of furnace temperature, and the pulse combustion state.

[0005] Existing oxygen-enriched combustion control methods mainly rely on preset oxygen concentrations or fixed oxygen flow rates, which are insufficient to adapt to changes in the actual operating conditions of the heating furnace. For example, when the composition of the mixed gas changes, if a fixed air-fuel ratio is still used, an unreasonable ratio of fuel to combustion medium is likely to occur; when there are significant changes in the number of slabs in the furnace or the charging and unloading rhythm, a fixed combustion load cannot adapt to the furnace heat load demand in a timely manner; and when the gas load is low, maintaining a high oxygen supply may lead to localized excessive oxygen enrichment.

[0006] In addition, existing furnace residual oxygen detection technology is usually mainly used for combustion ratio adjustment and fails to participate in the safety interlock control of the oxygen supply system at the same time, resulting in insufficient linkage between combustion control and oxygen circuit safety control.

[0007] Therefore, there is a need to provide a heating furnace oxygen-enriched combustion control scheme that can comprehensively adjust information such as gas calorific value, furnace operating conditions, furnace temperature changes, pulse combustion load, and residual oxygen in the furnace, so as to improve the adaptability of oxygen-enriched combustion control to different production conditions. Summary of the Invention

[0008] The present invention aims to solve the problem of insufficient adaptability of existing heating furnaces to operating conditions such as fluctuations in the calorific value of gas, changes in the charging and unloading rhythm, changes in the load on slabs in the furnace, and low gas load during oxygen-enriched combustion, and provides a heating furnace oxygen-enriched combustion control system and control method.

[0009] This invention determines the theoretical air-fuel ratio benchmark by real-time detection of the calorific value of the mixed gas, and combines the heating furnace heating rate, combustion pulse load rate, mixed gas load and the working conditions of the slab in the furnace to link and regulate the air and oxygen supply. At the same time, it uses the residual oxygen content in the furnace to correct the ratio parameters and participates in the safety interlock control of the oxygen supply branch, thereby forming a multi-variable closed-loop oxygen-enriched combustion control.

[0010] To achieve the above objectives, the present invention provides an oxygen-enriched combustion control system for a heating furnace, comprising a heating furnace, a mixed gas supply branch, an air supply branch, an oxygen supply branch, a calorific value module, an operating condition acquisition unit, a residual oxygen detection unit, a mixing module, an oxygen-enriched control module, a safety module, and a combustion nozzle.

[0011] The mixed gas supply branch includes a mixed gas source and a gas control module connected to the mixed gas source; the air supply branch includes an air source and an air control module connected to the air source; the oxygen supply branch includes an oxygen source and an oxygen control module connected to the oxygen source.

[0012] The output of the oxygen control module is connected to the mixing module via the safety module, and the safety module is used to provide safety interlock protection for the oxygen supply branch.

[0013] The output ends of the mixed gas supply branch and the air supply branch are respectively connected to the mixing module, the output end of the mixing module is connected to the oxygen enrichment control module, and the oxygen enrichment control module is connected to the furnace of the heating furnace through the combustion nozzle.

[0014] The calorific value module is installed in the mixed gas supply branch and is used to detect the calorific value of the mixed gas in real time and transmit the detected real-time calorific value to the oxygen enrichment control module.

[0015] The oxygen-enriched control module determines the theoretical air-fuel ratio that matches the current mixed gas based on the real-time calorific value of the mixed gas, and uses the theoretical air-fuel ratio as the basic ratio benchmark for the supply of mixed gas, air and oxygen.

[0016] By dynamically adjusting the theoretical air-fuel ratio based on the actual calorific value of the mixed gas, the basic combustion ratio can be adjusted according to changes in the gas composition and calorific value, reducing the ratio deviation caused by fluctuations in the calorific value of the gas when using a fixed air-fuel ratio.

[0017] The operating condition acquisition unit is located on the side of the heating furnace and is used to collect information on steel charging, steel tapping, slab position in the furnace, and slab inventory in the furnace, and transmit the collected operating condition information to the oxygen enrichment control module.

[0018] Furthermore, the operating condition acquisition unit can also collect information on steel loading frequency, steel tapping frequency, cumulative time of a single slab in the furnace, and spatial distribution of slabs in the furnace.

[0019] The oxygen-enriched control module judges the trend of furnace heat load change based on steel charging information, steel tapping information and the amount of slab in the furnace, and corrects the overall combustion heat load of the heating furnace and the heat load distribution of different furnace sections based on the position of the slab in the furnace and the cumulative time in the furnace, and adjusts the supply of mixed gas, air and oxygen accordingly.

[0020] The residual oxygen detection unit is installed inside the furnace of the heating furnace to detect the residual oxygen content in the flue gas inside the furnace, and the detected residual oxygen content signal is output in two channels.

[0021] The first residual oxygen content signal is transmitted to the oxygen-enriched control module for closed-loop correction of the theoretical air-fuel ratio and oxygen-enriched concentration control parameters.

[0022] The second residual oxygen content signal is transmitted to the safety module for safety interlock determination of the oxygen supply branch. When the residual oxygen content meets the preset abnormal interlock conditions, the safety module executes the oxygen supply branch cut-off protection.

[0023] The oxygen-enriched control module is also used to determine the heating rate of the heating furnace based on the real-time furnace temperature.

[0024] When the measured heating rate is lower than the lower limit of the preset heating rate range, the valve opening of the oxygen control module is increased to increase the oxygen concentration in the combustion medium and enhance the combustion intensity; when the measured heating rate is higher than the upper limit of the preset heating rate range, the valve opening of the oxygen control module is decreased to reduce the combustion intensity.

[0025] The oxygen-enriched control module can also acquire the pulse combustion control signal of the heating furnace and determine the combustion pulse load rate.

[0026] The combustion pulse load rate is the ratio of the actual number of pulse ignition matching times to the theoretically set total number of pulse actions.

[0027] When the combustion pulse load rate decreases, the oxygen enrichment control module reduces the valve opening of the oxygen control module; when the combustion pulse load rate increases, the valve opening of the oxygen control module increases, so that the oxygen supply matches the pulse combustion condition.

[0028] The oxygen-enriched control module also acquires the instantaneous flow rate of the mixed gas in real time and determines the current gas load percentage based on the instantaneous flow rate of the mixed gas and the rated gas load.

[0029] When the current gas load percentage is lower than the preset load threshold, the oxygen enrichment control module reduces the valve opening of the oxygen control module according to the current gas load percentage, so that the oxygen supply is adapted to the actual gas load.

[0030] The oxygen enrichment control module determines the real-time oxygen concentration in the oxygen-enriched combustion medium based on the air volume flow rate and oxygen volume flow rate.

[0031] The real-time oxygen concentration is determined according to the following relationship:

[0032] in, This indicates the real-time oxygen concentration in the oxygen-enriched combustion medium. Indicates air volume flow rate, This indicates the volumetric flow rate of oxygen.

[0033] In the conventional oxygen-enriched mode, the oxygen concentration of the oxygen-enriched combustion medium is controlled in a closed loop at 21% to 30%.

[0034] When the real-time oxygen concentration is below the lower limit of the target oxygen-enriched concentration range, increase the oxygen supply; when the real-time oxygen concentration is above the upper limit of the target oxygen-enriched concentration range, decrease the oxygen supply.

[0035] Furthermore, the system is configured with a high-concentration oxygen-enriched mode, in which the oxygen concentration in the oxygen-enriched combustion medium is controlled at 30% to 60%, and the oxygen circuit safety interlock parameters corresponding to the safety module are adjusted simultaneously.

[0036] Based on the above control system, the present invention also provides a method for controlling oxygen-enriched combustion in a heating furnace, comprising the following steps: S1. The supply control of mixed gas, air and oxygen is respectively implemented. The pressure and flow of mixed gas are regulated by the gas control module, the flow of air is regulated by the air control module, and the flow of oxygen is regulated by the oxygen control module. The safety interlock monitoring of the oxygen supply branch is implemented by the safety module. S2. The calorific value of the mixed gas is collected in real time through the calorific value module. The steel charging information, steel tapping information, slab position information in the furnace and slab inventory information in the furnace are collected through the working condition acquisition unit. The residual oxygen content in the furnace is collected through the residual oxygen detection unit. S3. Determine the corresponding theoretical air-fuel ratio based on the real-time calorific value of the mixed gas, and use the theoretical air-fuel ratio as the basis for the proportioning of the mixed gas, air and oxygen supply. S4. Based on the theoretical air-fuel ratio, and combined with the heating furnace heating rate, combustion pulse load rate, mixed gas load, and operating condition information collected by the operating condition acquisition unit, the oxygen and air supply are adjusted in a coordinated manner to control the oxygen concentration in the oxygen-enriched combustion medium. S5. The air-fuel ratio and oxygen enrichment concentration control parameters are corrected using the residual oxygen content. At the same time, the safety interlock judgment is performed based on the residual oxygen content. When the residual oxygen content meets the preset abnormal interlock conditions, the oxygen supply branch is cut off through the safety module. S6. The prepared combustion medium is fed into the furnace chamber of the heating furnace through the combustion nozzle for combustion.

[0037] The beneficial effects of this invention are as follows: (1) The calorific value of the mixed gas is detected in real time by the calorific value module, and the theoretical air-fuel ratio is dynamically determined according to the actual calorific value, so that the basic combustion ratio can adapt to the changes in the composition and calorific value of the mixed gas, which is conducive to improving the adaptability of the combustion ratio.

[0038] (2) Use the working condition acquisition unit to obtain information such as steel loading, steel tapping, slab position and slab inventory, and correct the combustion heat load accordingly so that the combustion load can match the actual heating demand of the slab in the furnace.

[0039] (3) Introduce the heating furnace heating rate, combustion pulse load rate and gas load into the oxygen enrichment control process so that the oxygen supply is no longer adjusted only according to the fixed oxygen enrichment concentration, thereby improving the adaptability of oxygen enrichment control to dynamic working conditions.

[0040] (4) When the gas load decreases, the oxygen supply is reduced simultaneously, which can reduce the situation of excessive supply of oxygen-enriched medium under low fuel load conditions.

[0041] (5) The oxygen concentration of the oxygen-enriched combustion medium is controlled in real time by air flow and oxygen flow, and a conventional oxygen-enriched mode and a high-concentration oxygen-enriched mode are set to meet the oxygen-enriched control requirements under different combustion conditions.

[0042] (6) The residual oxygen detection unit is used to form two signal loops: ratio control and safety interlock. This allows the residual oxygen data in the furnace to participate in both combustion parameter correction and safety interlock control of the oxygen supply branch, thereby improving the synergy between combustion control and oxygen circuit safety control.

[0043] (7) By improving the adaptability of the oxygen-enriched combustion system to low-calorific-value mixed gas, it is beneficial to increase the utilization rate of low-cost gas such as blast furnace gas, thereby reducing the fuel cost of heating furnace.

[0044] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0045] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein: Figure 1 This is a schematic diagram of the overall structure of the oxygen-enriched combustion control system for the heating furnace of the present invention; Reference numerals in the attached diagram: 1. Oxygen-enriched control integrated unit; 2. Heating furnace; 3. Oxygen-enriched control module; 4. Mixing module; 5. Oxygen source; 6. Oxygen control module; 7. Safety module; 8. Air source; 9. Air control module; 10. Mixed coal gas source; 11. Coal gas control module; 12. Calorific value module; 13. Combustion nozzle; 14. Residual oxygen detection unit; 15. Operating condition acquisition unit. Detailed Implementation

[0046] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0047] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures, and should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0048] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0049] Example 1 This embodiment provides an oxygen-enriched combustion control system for a heating furnace.

[0050] like Figure 1 As shown, the control system includes an oxygen enrichment regulation integrated unit 1, a heating furnace 2, an oxygen enrichment control module 3, a mixing module 4, an oxygen source 5, an oxygen control module 6, a safety module 7, an air source 8, an air control module 9, a mixed coal gas source 10, a coal gas control module 11, a calorific value module 12, a combustion nozzle 13, a residual oxygen detection unit 14, and an operating condition acquisition unit 15.

[0051] The oxygen enrichment control module 3, the mixing module 4, and the safety module 7 are integrated into the oxygen enrichment regulation integrated unit 1.

[0052] The mixed gas source 10 is used to provide the mixed gas required for combustion in the heating furnace 2. The mixed gas can be formed from blast furnace gas and other fuel gases according to production needs. The mixed gas source 10 is connected to the gas control module 11, which regulates the pressure and flow rate of the mixed gas.

[0053] Air source 8 is connected to air control module 9, and the supply flow of combustion air is adjusted through air control module 9.

[0054] Oxygen source 5 is connected to oxygen control module 6, and the oxygen supply is adjusted through oxygen control module 6.

[0055] The output of the oxygen control module 6 is connected to the safety module 7, which is used to perform safety monitoring and interlock protection on the oxygen supply branch.

[0056] Safety module 7 can monitor the pressure and leakage status during the oxygen supply process, and execute the oxygen supply branch cut-off action when the preset interlocking conditions are met.

[0057] The mixed gas supply branch, the air supply branch, and the oxygen supply branch passing through the safety module 7 enter the mixing module 4 according to the control requirements. The combustion medium output from the mixing module 4 enters the oxygen enrichment control module 3, and after being adjusted by the oxygen enrichment control module 3 according to the current control parameters, it is sent into the furnace of the heating furnace 2 through the combustion nozzle 13 for combustion.

[0058] The calorific value module 12 is located on the mixed gas supply side and is used to detect the low calorific value of the mixed gas online and transmit the real-time detected calorific value of the gas to the oxygen enrichment control module 3.

[0059] The oxygen-enriched control module 3 determines the corresponding theoretical air-fuel ratio based on the real-time calorific value of the current mixed gas, and uses the theoretical air-fuel ratio as the basis for adjusting the current supply of mixed gas, air and oxygen.

[0060] When the ratio of different fuels in the mixed gas changes, resulting in a change in the real-time calorific value, the oxygen enrichment control module 3 updates the theoretical air-fuel ratio accordingly, so that subsequent air and oxygen supply adjustments are based on the updated theoretical air-fuel ratio.

[0061] This reduces the impact of changes in the calorific value of the gas on the control of the fixed air-fuel ratio.

[0062] The operating condition acquisition unit 15 is set on the 2nd side of the heating furnace to acquire the steel loading action, steel tapping action, and the running status of the slab in the furnace.

[0063] The operating condition acquisition unit 15 specifically collects the frequency of steel loading, the frequency of steel tapping, the position of the slab in the furnace, the cumulative time of a single slab in the furnace, and the total amount of slabs in the furnace, and sends the above operating condition data to the oxygen enrichment control module 3.

[0064] When the steel loading action increases or the total amount of slabs in the furnace increases, the heating load of the heating furnace 2 changes accordingly. The oxygen-enriched control module 3 predicts the trend of furnace heat load change based on the working condition data fed back by the working condition acquisition unit 15, and adjusts the total combustion heat load accordingly.

[0065] Meanwhile, the oxygen-enriched control module 3 adjusts the required heat load for different furnace sections based on the furnace section where the slab is located and the time the slab has been heated in the furnace, so as to match the combustion supply with the slab heating process.

[0066] The oxygen-enriched control module 3 also collects the real-time furnace temperature of each heating zone in the heating furnace 2, and calculates the furnace temperature change per unit time based on the continuous furnace temperature data, thereby obtaining the heating rate.

[0067] The oxygen enrichment control module 3 is pre-set with a target heating rate range.

[0068] When the actual heating rate is lower than the lower limit of the target heating rate range, it indicates that the current heating intensity is insufficient. The oxygen enrichment control module 3 increases the valve opening of the oxygen control module 6 to increase the oxygen supply.

[0069] When the actual heating rate is higher than the upper limit of the target heating rate range, the oxygen enrichment control module 3 reduces the valve opening of the oxygen control module 6 to reduce the oxygen supply.

[0070] When the actual heating rate is within the target heating rate range, the oxygen supply remains in its current regulation state or is slightly adjusted.

[0071] For the heating furnace 2, which operates in pulse combustion mode, the oxygen-enriched control module 3 reads the pulse combustion control signal and calculates the combustion pulse load rate based on the pulse combustion operating status.

[0072] The combustion pulse load rate is determined according to the following formula: Combustion pulse load rate = Actual number of pulse ignition matching times ÷ Total number of theoretically set pulse actions.

[0073] When the combustion pulse load rate decreases, the oxygen enrichment control module 3 reduces the valve opening of the oxygen control module 6; when the combustion pulse load rate increases, the oxygen enrichment control module 3 correspondingly increases the valve opening of the oxygen control module 6, so that the oxygen supply status is adapted to the pulse combustion load.

[0074] Meanwhile, the oxygen-enriched control module 3 obtains the instantaneous flow rate of the mixed gas through the gas control module 11, and determines the current gas load percentage based on the real-time instantaneous flow rate of the mixed gas and the rated gas load.

[0075] When the current gas load percentage is lower than the set gas load threshold, it indicates that the heating furnace 2 is currently in a low fuel load state.

[0076] At this time, the oxygen-enriched control module 3 reduces the valve opening of the oxygen control module 6 according to the current gas load percentage, so that the oxygen supply decreases synchronously with the gas supply, thus avoiding the oxygen supply from remaining at a high level under low gas load conditions.

[0077] The oxygen enrichment control module 3 also acquires the air volume flow rate corresponding to the air control module 9 and the oxygen volume flow rate corresponding to the oxygen control module 6 in real time, and calculates the real-time oxygen concentration in the oxygen-enriched combustion medium based on the two.

[0078] Real-time oxygen concentration is calculated using the following formula:

[0079] in, This indicates the real-time oxygen concentration in the oxygen-enriched combustion medium. Indicates air volume flow rate, This represents the oxygen volumetric flow rate. 0.21 represents the oxygen volume fraction in the air.

[0080] In the standard oxygen-enriched mode, the target oxygen concentration range is set to 21%–30%.

[0081] When the calculated real-time oxygen concentration is lower than the lower limit of the target oxygen enrichment concentration range, the oxygen enrichment control module 3 increases the valve opening of the oxygen control module 6 to increase the oxygen flow rate.

[0082] When the calculated real-time oxygen concentration is higher than the upper limit of the target oxygen enrichment concentration range, the oxygen enrichment control module 3 reduces the valve opening of the oxygen control module 6 and reduces the oxygen flow rate.

[0083] At the same time, the oxygen-enriched control module 3, in conjunction with the theoretical air-fuel ratio corresponding to the real-time calorific value of the gas fed back by the calorific value module 12, synchronously adjusts the air supply of the air control module 9, so that the oxygen-enriched concentration control is coordinated with the current gas air-fuel ratio control.

[0084] Depending on the production conditions, the control system can also switch to a high-concentration oxygen-enriched mode.

[0085] In the high-concentration oxygen-enriched mode, the target oxygen-enriched concentration range is adjusted to 30%–60%.

[0086] When switching to the high-concentration oxygen-enriched mode, the safety interlock parameters of the safety module 7 for the oxygen supply branch are adjusted accordingly to match the safety control parameters with the high-concentration oxygen-enriched working condition.

[0087] The residual oxygen detection unit 14 is installed on the furnace side of the heating furnace 2 to detect the residual oxygen content in the flue gas in the furnace in real time.

[0088] In this embodiment, the residual oxygen detection unit 14 can use a zirconia residual oxygen analyzer to detect the residual oxygen content in the furnace flue gas online.

[0089] The residual oxygen content signal output by the residual oxygen detection unit 14 forms two control paths.

[0090] The first residual oxygen content signal is transmitted to the oxygen enrichment control module 3.

[0091] When the residual oxygen content is higher than the upper limit of the preset residual oxygen control range, it indicates that the current supply of combustion medium is relatively large, and the oxygen enrichment control module 3 reduces the supply of air and oxygen.

[0092] When the residual oxygen content is lower than the lower limit of the preset residual oxygen control range, it indicates that the current supply of combustion medium is insufficient, and the oxygen enrichment control module 3 will increase the supply of oxygen enrichment combustion medium accordingly.

[0093] Therefore, the residual oxygen content is used as a feedback quantity to further correct the aforementioned adjustment results obtained based on the calorific value of the gas, the heating rate, the combustion pulse load rate, the gas load, and the slab operating conditions.

[0094] The second residual oxygen content signal is transmitted to safety module 7.

[0095] When the residual oxygen content continues to meet the preset abnormal interlocking conditions, the safety module 7 determines that the current combustion state is abnormal and executes the oxygen supply branch cut-off action.

[0096] Through the above two signal processing, the residual oxygen detection unit 14 participates in both the combustion ratio closed-loop correction and the safety interlock control of the oxygen supply branch.

[0097] Example 2 This embodiment provides a method for controlling oxygen-enriched combustion in a heating furnace. The control method is implemented using the oxygen-enriched combustion control system for the heating furnace described in Embodiment 1, and specifically includes the following steps.

[0098] S1. Supply the combustion medium.

[0099] The mixed gas source 10 outputs mixed gas, and the pressure and flow rate of the mixed gas are regulated by the gas control module 11.

[0100] Air source 8 outputs air, and the air flow is regulated by air control module 9.

[0101] Oxygen source 5 outputs oxygen, the oxygen supply is regulated by oxygen control module 6, and the oxygen is sent to safety module 7, which implements safety interlock monitoring of the oxygen supply branch.

[0102] S2. Collect multi-source operating condition information.

[0103] The calorific value module 12 detects the calorific value of the mixed gas in real time and transmits the detected real-time calorific value of the mixed gas to the oxygen-enriched control module 3.

[0104] The operating condition acquisition unit 15 collects the steel loading information, steel tapping information, slab position information in the furnace, and slab inventory information in the furnace of the heating furnace 2.

[0105] The residual oxygen detection unit 14 detects the residual oxygen content in the flue gas inside the furnace of the heating furnace 2.

[0106] S3. Determine the basic mixing ratio standard.

[0107] The oxygen enrichment control module 3 determines the theoretical air-fuel ratio corresponding to the current calorific value of the mixed gas based on the real-time calorific value of the mixed gas collected by the calorific value module 12, and uses the theoretical air-fuel ratio as the basic ratio benchmark for adjusting the flow rates of the mixed gas, air and oxygen.

[0108] S4. Perform multivariate linkage oxygen enrichment regulation.

[0109] First, the heating rate is determined based on the real-time furnace temperature data of the heating furnace 2, and the corresponding oxygen supply correction is determined based on the position of the heating rate relative to the preset target heating rate range.

[0110] Secondly, the pulse combustion control signal is read, and the combustion pulse load rate is determined based on the actual number of pulse ignition matching times and the theoretically set total number of pulse actions. The corresponding oxygen supply correction is then determined based on the combustion pulse load rate.

[0111] Next, the instantaneous flow rate of the mixed gas is obtained, and the current gas load percentage is determined based on the real-time instantaneous gas flow rate and the rated gas load. When the current gas load percentage is lower than the preset load threshold, the oxygen supply is reduced.

[0112] Meanwhile, based on the steel loading information, steel tapping information, slab position in the furnace and slab inventory in the furnace collected by the operating condition acquisition unit 15, the overall combustion heat load of the heating furnace 2 and the combustion heat load of different furnace sections are corrected.

[0113] In the above control process, the theoretical air-fuel ratio determined based on the real-time calorific value of the mixed gas is used as the basic ratio benchmark. The real-time oxygen concentration is calculated based on the air volume flow rate and oxygen volume flow rate, and the air control module 9 and oxygen control module 6 are adjusted in a closed loop.

[0114] In the standard oxygen-enriched mode, the real-time oxygen concentration is controlled at 21% to 30%.

[0115] When switching to high-concentration oxygen-enriched mode according to production needs, the real-time oxygen concentration will be controlled between 30% and 60%, and the oxygen supply safety interlock parameters corresponding to safety module 7 will be adjusted simultaneously.

[0116] S5. Perform residual oxygen feedback correction and oxygen circuit safety interlock control.

[0117] One of the residual oxygen content signals collected by the residual oxygen detection unit 14 is transmitted to the oxygen enrichment control module 3 for feedback correction of the current theoretical air-fuel ratio and oxygen enrichment concentration adjustment parameters.

[0118] When the residual oxygen content is higher than the upper limit of the preset residual oxygen control range, the supply of combustion-supporting medium is reduced; when the residual oxygen content is lower than the lower limit of the preset residual oxygen control range, the supply of oxygen-enriched combustion-supporting medium is increased.

[0119] Another path of the residual oxygen content signal is transmitted to security module 7.

[0120] When the detected residual oxygen content meets the preset abnormal interlocking conditions, safety module 7 executes the oxygen supply branch cut-off protection.

[0121] S6, Providing combustion supply.

[0122] After the above proportioning and linkage control, the combustion medium is sent into the furnace of the heating furnace 2 through the combustion nozzle 13 for combustion. Under the condition of meeting the requirements of slab heating temperature and heating process, the supply status of mixed gas, air and oxygen is dynamically adjusted according to the actual production conditions.

[0123] By implementing the above control process, the oxygen-enriched combustion control can simultaneously respond to changes in gas calorific value, furnace temperature, pulse combustion load, gas load, slab load in the furnace, and residual oxygen in the furnace, forming a multi-variable linkage closed-loop control.

[0124] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A heating furnace oxygen-enriched combustion control system, characterized in that, It includes a heating furnace, a mixed gas supply branch, an air supply branch, an oxygen supply branch, a calorific value module, an operating condition acquisition unit, a residual oxygen detection unit, a mixing module, an oxygen enrichment control module, a safety module, and a combustion nozzle. The mixed gas supply branch includes a mixed gas source and a gas control module connected to the mixed gas source. The air supply branch includes an air source and an air control module connected to the air source. The oxygen supply branch includes an oxygen source and an oxygen control module connected to the oxygen source. The output of the oxygen control module is connected to the mixing module via the safety module. The safety module is used for safety interlock protection of the oxygen supply branch. The outputs of the mixed gas supply branch and the air supply branch are respectively connected to the mixing module. The output of the mixing module is connected to the oxygen enrichment control module. The oxygen enrichment control module is connected to the furnace of the heating furnace via the combustion nozzle. The calorific value module is used to collect the real-time calorific value of the mixed gas in the mixed gas supply branch and transmit the real-time calorific value to the oxygen enrichment control module. The oxygen enrichment control module determines the corresponding theoretical air-fuel ratio based on the real-time calorific value and uses the theoretical air-fuel ratio as the ratio benchmark for the supply of mixed gas, air and oxygen. The operating condition acquisition unit is used to collect the steel charging information, steel tapping information, slab position information in the furnace, and slab inventory information in the furnace of the heating furnace, and transmits the collected operating condition information to the oxygen enrichment control module. The oxygen enrichment control module corrects the supply of mixed gas, air and oxygen according to the operating condition information. The residual oxygen detection unit is installed inside the furnace of the heating furnace to collect the residual oxygen content in the furnace and transmit the residual oxygen content signal to the oxygen enrichment control module and the safety module respectively. The oxygen enrichment control module corrects the air-fuel ratio and oxygen enrichment concentration control parameters according to the residual oxygen content, and the safety module executes the safety interlock control of the oxygen supply branch according to the residual oxygen content. The oxygen-enriched control module is configured to, based on the theoretical air-fuel ratio and in conjunction with at least two of the following: furnace heating rate, combustion pulse load rate, mixed gas load, operating condition information, and residual oxygen content, to coordinate and regulate the oxygen control module and the air control module in order to control the oxygen concentration in the combustion medium fed into the furnace.

2. The oxygen-enriched combustion control system for the heating furnace according to claim 1, characterized in that, The calorific value module detects the lower heating value of the mixed gas in real time. The oxygen enrichment control module has a correspondence between calorific value and air-fuel ratio. It dynamically updates the theoretical air-fuel ratio based on the lower heating value and uses the updated theoretical air-fuel ratio as the benchmark value for the ratio of air flow, oxygen flow, and mixed gas flow.

3. The oxygen-enriched combustion control system for the heating furnace according to claim 1, characterized in that, The operating condition acquisition unit is also used to collect information on the frequency of steel charging, the frequency of steel tapping, the cumulative time of a single slab in the furnace, and the spatial distribution of slabs in the furnace. The oxygen-enriched control module determines the trend of furnace heat storage demand based on the frequency of steel charging and tapping, and corrects the overall combustion heat load of the heating furnace and the heat load distribution of different furnace sections based on the spatial distribution of slabs in the furnace, the cumulative time in the furnace, and the total amount of slabs in the furnace, and adjusts the supply of mixed gas, air and oxygen accordingly.

4. The oxygen-enriched combustion control system for the heating furnace according to claim 1, characterized in that, The residual oxygen detection unit divides the residual oxygen content signal into a first signal and a second signal. The first signal is transmitted to the oxygen enrichment control module. When the residual oxygen content is higher than the upper limit of the preset residual oxygen range, the oxygen enrichment control module reduces the supply of air and oxygen. When the residual oxygen content is lower than the lower limit of the preset residual oxygen range, the oxygen enrichment control module increases the supply of oxygen-enriched combustion medium. The second signal is transmitted to the safety module. When the residual oxygen content meets the preset abnormal interlocking conditions, the safety module cuts off the oxygen supply branch.

5. The oxygen-enriched combustion control system for the heating furnace according to claim 1, characterized in that, The oxygen-enriched control module is used to calculate the heating rate per unit time based on the real-time furnace temperature of the heating furnace. When the heating rate is lower than the lower limit of the preset heating rate range, the valve opening of the oxygen control module is increased. When the heating rate is higher than the upper limit of the preset heating rate range, the valve opening of the oxygen control module is decreased.

6. The oxygen-enriched combustion control system for the heating furnace according to claim 1, characterized in that, The combustion pulse load rate is the ratio of the actual number of pulse ignition matching times to the theoretically set total number of pulse actions. The oxygen enrichment control module adjusts the valve opening of the oxygen control module according to the combustion pulse load rate. Specifically, the valve opening of the oxygen control module is reduced when the combustion pulse load rate decreases, and the valve opening of the oxygen control module is increased when the combustion pulse load rate increases.

7. The oxygen-enriched combustion control system for the heating furnace according to claim 1, characterized in that, The oxygen-enriched control module acquires the instantaneous flow rate of the mixed gas in real time, and determines the current gas load percentage based on the instantaneous flow rate of the mixed gas and the rated gas load. When the current gas load percentage is lower than the preset load threshold, the valve opening of the oxygen control module is reduced according to the current gas load percentage.

8. The oxygen-enriched combustion control system for the heating furnace according to claim 1, characterized in that, The oxygen enrichment control module determines the real-time oxygen concentration in the oxygen-enriched combustion medium based on the air volume flow rate and oxygen volume flow rate, and controls the real-time oxygen concentration in a closed loop at 21% to 30% in the normal oxygen enrichment mode; the oxygen enrichment control module is also configured with a high-concentration oxygen enrichment mode, in which the real-time oxygen concentration is controlled at 30% to 60%, and the oxygen circuit safety interlock parameters corresponding to the safety module are adjusted synchronously.

9. A method for controlling oxygen-enriched combustion in a heating furnace, applied to the oxygen-enriched combustion control system of the heating furnace according to any one of claims 1 to 8, characterized in that, Includes the following steps: S1. The supply control of mixed gas, air and oxygen is performed respectively. The oxygen enters the safety module after being regulated by the oxygen control module. The safety module performs safety interlock monitoring of the oxygen supply branch. S2. The real-time calorific value of the mixed gas is collected through the calorific value module, and the steel charging information, steel tapping information, slab position information and slab inventory information of the heating furnace are collected through the operating condition acquisition unit. The residual oxygen content in the furnace is collected through the residual oxygen detection unit. S3. Determine the corresponding theoretical air-fuel ratio based on the real-time calorific value of the mixed gas, and use the theoretical air-fuel ratio as the basis for the proportioning of the mixed gas, air and oxygen supply. S4. Based on the theoretical air-fuel ratio, and combined with the heating furnace heating rate, combustion pulse load rate, mixed gas load, and the operating condition information collected by the operating condition acquisition unit, determine the adjustment amount of oxygen supply and air supply, and perform closed-loop regulation of oxygen concentration in the oxygen-enriched combustion medium. S5. The residual oxygen content is used for ratio parameter correction and safety interlock judgment, wherein the theoretical air-fuel ratio and oxygen enrichment concentration control parameters are corrected according to the residual oxygen content, and the oxygen supply branch is cut off by the safety module when the residual oxygen content meets the preset abnormal interlock conditions. S6. The oxygen-enriched combustion medium and mixed gas, which are proportioned according to the adjustment amount, are fed into the furnace of the heating furnace through the combustion nozzle for combustion.

10. The oxygen-enriched combustion control method for a heating furnace according to claim 9, characterized in that, The real-time oxygen concentration of the oxygen-enriched combustion medium is calculated based on the air volume flow rate and the oxygen volume flow rate, wherein the real-time oxygen concentration is: in, This indicates the real-time oxygen concentration in the oxygen-enriched combustion medium. Indicates air volume flow rate, This indicates the oxygen volumetric flow rate. In the normal oxygen-enriched mode, the real-time oxygen concentration is controlled in a closed loop between 21% and 30%. When the real-time oxygen concentration is lower than the lower limit of the target oxygen-enriched concentration range, the oxygen supply is increased. When the real-time oxygen concentration is higher than the upper limit of the target oxygen-enriched concentration range, the oxygen supply is decreased. When switching to the high-concentration oxygen-enriched mode, the target oxygen-enriched concentration range is adjusted to 30% to 60%.

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