Low-carbon ironmaking system and method based on online upgrading and heating injection of industrial exhaust gas

Abstract

This invention discloses a low-carbon ironmaking system and method based on online upgrading and heating injection of industrial tail gas, including an industrial tail gas storage tank, a gas compressor, a first pipeline gas composition detection device, a second pipeline gas composition detection device, a gas pressure and flow control system, a pipeline gas temperature sensor, a first three-way valve, a group A gas upgrading furnace, a group B gas upgrading furnace, a second three-way valve, and a blast furnace injection device. This invention relies on the efficient mass and heat transfer reaction environment of the high-temperature molten steel pool and leverages the high decomposition rate of CO2 and hydrocarbon gases in the iron-based melt to achieve the two major tasks of upgrading and heating industrial tail gas in the molten steel reaction pool and then using it for blast furnace injection. This can efficiently utilize the chemical energy in industrial tail gas and achieve synergistic carbon reduction and emission reduction in the steel production process.

Description

Technical Field

[0001] This invention relates to the field of low-carbon ironmaking in blast furnaces during the iron and steel metallurgical process, and particularly to a low-carbon ironmaking system and method based on online upgrading and temperature-increasing injection of industrial tail gas. Background Technology

[0002] The steel production process generates a large amount of industrial waste gas, including coke oven gas, blast furnace gas, and converter gas. These waste gases contain a large amount of combustible gas components, such as carbon monoxide, hydrogen, methane, and other hydrocarbons, which have a certain calorific value. Currently, these waste gases are mainly used as fuel for sintering machine ignition, hot blast stoves, steel rolling heating furnaces, and ladle baking furnaces. They generate heat through combustion to heat the target object and complete the process tasks.

[0003] However, the main components of the aforementioned industrial exhaust gases, such as carbon monoxide and hydrogen, not only provide heat through combustion but also possess chemical energy. They can be used as reducing agents for iron and other metal oxides in the blast furnace ironmaking process, resulting in higher added value and synergistic carbon reduction effects. However, the exhaust gases also contain carbon dioxide. When a large amount of carbon dioxide enters the blast furnace vortex zone from the tuyeres, it undergoes a strong endothermic reaction with the carbon elements in the coke and pulverized coal, affecting the heat balance within the blast furnace. Therefore, when injecting the aforementioned exhaust gases into blast furnaces, it is generally necessary to purify the gas using solution absorption or pressure swing adsorption methods, i.e., removing carbon dioxide from the gas before injection. In traditional blast furnace smelting, combustion gases such as air and oxygen need to be heated to about 1200°C in a hot blast stove before entering the blast furnace through the tuyeres. They carry a large amount of physical heat to provide heat for the reduction reaction of metal oxides and to melt slag and iron. Therefore, if industrial exhaust gas is used as injection gas in the blast furnace ironmaking process, it also needs to be heated to meet the heat requirements of the blast furnace. Currently, methods such as hot blast stoves, electric heating, and plasma heating are commonly used to increase the temperature of industrial exhaust gas used for injection. However, due to the presence of carbon monoxide gas, a carbon precipitation reaction occurs during the heating process, and the generated carbon black blocks the internal channels of the heating element, reducing the heat conversion efficiency.

[0004] Therefore, how to safely and efficiently use industrial tail gases with high chemical energy, such as coke oven gas, blast furnace gas, and converter gas, for blast furnace injection, reduce pretreatment processes before industrial tail gas injection to lower equipment operation difficulty, and achieve online quality improvement and temperature enhancement of industrial tail gas are key technical problems that urgently need to be solved in the field of low-carbon ironmaking. Summary of the Invention

[0005] To address the aforementioned problems, this invention first provides a low-carbon ironmaking system based on online upgrading and temperature-increasing injection of industrial tail gas. This system includes an industrial tail gas storage tank, a gas compressor, a first pipeline gas composition detection device, a second pipeline gas composition detection device, a gas pressure and flow control system, a pipeline gas temperature sensor, a first three-way valve, a group A gas upgrading furnace, a group B gas upgrading furnace, a second three-way valve, and a blast furnace injection device. The industrial tail gas source after dust removal is configured to connect to the industrial tail gas storage tank via the first pipeline. The gas outlet of the industrial tail gas storage tank connects to the gas compressor via the second pipeline. After pressurization, the gas flows through a third pipeline to the first pipeline gas composition detection device. The gas pressure and flow control system is connected via the fourth pipe, and then connected to the first three-way valve via the fifth pipe. The first outlet of the first three-way valve is connected to the gas inlet of the A-group gas reformer via the sixth pipe. The second outlet of the first three-way valve is connected to the gas inlet of the B-group gas reformer via the seventh pipe. The gas outlet of the A-group gas reformer is connected to the first inlet of the second three-way valve B via the eighth pipe. The gas outlet of the B-group gas reformer is connected to the second inlet of the second three-way valve via the ninth pipe. The outlet of the second three-way valve is connected to the pipeline gas temperature sensor via the tenth pipe, and then connected to the second pipeline gas composition detection device via the eleventh pipe. Finally, it is connected to the blast furnace injection device via the twelfth pipe.

[0006] Furthermore, Group A gas reformers include two gas reformers A1 and A2 connected in series; Group B gas reformers include two gas reformers B1 and B2 connected in series; and gas reformers A1 and A2 are connected in parallel with gas reformers B1 and B2 respectively through a third three-way valve and a fourth three-way valve.

[0007] Furthermore, the gas reforming furnace uses induction coils or plasma heating to supply heat to the molten pool.

[0008] Furthermore, the gas-modified furnace is equipped with a slag reduction ferrite regeneration device, which uses an external DC power supply to electrolyze the molten steel and slag or adds a carbonaceous reducing agent into the molten pool to reduce the slag.

[0009] Furthermore, the gas reforming furnace is equipped with a sealing device, and a sealed silo for iron-based raw materials and high-purity magnesium oxide is installed on the upper part of the furnace body.

[0010] The present invention also provides a low-carbon ironmaking method based on online modification and temperature-increasing injection of industrial tail gas, comprising the following steps: (1) providing the aforementioned low-carbon ironmaking system based on online modification and temperature-increasing injection of industrial tail gas; (2) preparation stage: iron-containing raw materials are loaded into the gas modification furnaces of group A and group B as molten pool metal phase raw materials, and high-purity magnesium oxide is added as slag regulator, and the metal phase raw materials are melted by electricity.

[0011] (3) Industrial tail gas upgrading and heating stage: Adjust the power of the heating elements of each gas upgrading furnace in Group A to the operating power, adjust the power of the heating elements of each gas upgrading furnace in Group B to the heat preservation power, open the first outlet and close the second outlet in the first three-way valve, and introduce the industrial tail gas in the industrial tail gas storage tank into the gas upgrading furnace through the bottom blowing element placed at the bottom of each gas upgrading furnace in Group A after adjusting the gas pressure and flow rate, so as to upgrade and heat the industrial tail gas. Even if the CO2 gas in the industrial tail gas reacts with the liquid iron in the molten pool to become CO gas, the hydrocarbons in the industrial tail gas will be cracked into reducing gases including CO and H2 in the high temperature molten pool. At the same time, the slag reduction iron regeneration device is started. The external DC power electrolysis power or carbonaceous reducing agent addition acceleration rate is set according to the industrial tail gas flow rate and its CO2 gas concentration. At the same time, the first inlet in the second three-way valve is opened and the second inlet is closed. After the industrial tail gas is upgraded and heated, the composition and temperature are detected and then blown into the blast furnace through the blast furnace injection device.

[0012] (4) Gas Reformer Furnace Reversal Stage: Adjust the power of the heating elements in each gas reformer furnace in Group A to the heat preservation power, and adjust the power of the heating elements in each gas reformer furnace in Group B to the operating power. Close the first outlet and open the second outlet of the three-way valve A. After adjusting the gas pressure and flow rate, introduce the industrial tail gas from the industrial tail gas storage tank into the gas reformer furnace through the bottom blowing elements placed at the bottom of each gas reformer furnace in Group B. Reform and heat the industrial tail gas, so that the CO2 gas in the industrial tail gas reacts with the liquid iron in the molten pool to form CO gas. Hydrocarbons are cracked into reducing gases, including CO and H2, in the high-temperature molten pool. At the same time, the slag reduction ferrite regeneration device is started. The external DC power supply electrolysis power or carbonaceous reducing agent addition acceleration rate is set according to the industrial tail gas flow rate and CO2 gas concentration. Meanwhile, the first inlet of the three-way valve B is closed and the second inlet is opened. After the composition and temperature of the industrial tail gas after the reforming and heating are detected, it is blown into the blast furnace through the blast furnace injection device. Iron raw materials and high-purity magnesium oxide are added to the molten pool of the gas reforming furnace in group A. After the newly added iron-based raw materials and slag in the molten pool are completely melted, the heat preservation and standby stage begins.

[0013] Furthermore, the external DC power supply for the slag reduction ferrite regeneration device has a current range of 1-300kA and a voltage range of 10-1000V. The external DC power supply current is adjusted by real-time monitoring of the ferrous oxide content in the slag. The acceleration rate of carbonaceous reducing agent addition is calculated according to the following formula:

[0014]

[0015] In the formula:

[0016] m—acceleration rate of carbonaceous reducing agent, kg / h;

[0017] V — Industrial exhaust gas flow rate input to this low-carbon ironmaking system, Nm³ 3 / h;

[0018] —The volume percentage of carbon dioxide in the industrial exhaust gas input to this low-carbon ironmaking system, -;

[0019] n——The number of furnaces in each group of gas reformers in this low-carbon ironmaking system, -;

[0020] ω C —The mass fraction of carbon in the carbonaceous reducing agent used in this method, -.

[0021] Furthermore, Group A gas reformers include two gas reformers A1 and A2 connected in series; Group B gas reformers include two gas reformers B1 and B2 connected in series; and gas reformers A1 and A2 are connected in parallel with gas reformers B1 and B2 respectively through a third three-way valve and a fourth three-way valve.

[0022] Furthermore, in the first state, gas reformers A1 and A2 are in operation, gas reformer B1 is in shutdown, and gas reformer B2 is in heat preservation state; at this time, the industrial exhaust gas passes sequentially through the first three-way valve, the third three-way valve, and the second three-way valve, flowing through gas reformers A1 and A2 for reforming and heating; in the second state, gas reformers A1 and B2 are in operation, gas reformer A2 is in shutdown, and gas reformer B1 is in heat preservation state; at this time, the industrial exhaust gas passes sequentially through the first three-way valve, the third three-way valve, the fourth three-way valve, and the second three-way valve, flowing through gas reformers A1 and B2 for reforming and heating; in the third In the first state, gas reformers B1 and B2 are in operation, gas reformer A1 is in shutdown, and gas reformer A2 is in heat preservation. At this time, the industrial exhaust gas passes sequentially through the first three-way valve, the fourth three-way valve, and the second three-way valve, flowing through gas reformers B1 and B2 for reforming and heating. In the second state, gas reformers B1 and A2 are in operation, gas reformer B2 is in shutdown, and gas reformer A1 is in heat preservation. At this time, the industrial exhaust gas passes sequentially through the first three-way valve, the fourth three-way valve, the third three-way valve, and the second three-way valve, flowing through gas reformers B1 and B2 for reforming and heating. Then, the process switches back to the first state.

[0023] Furthermore, industrial exhaust gas includes coking coal gas, blast furnace gas, and converter gas.

[0024] The beneficial effects of this invention include:

[0025] (1) The chemical energy in industrial tail gas is efficiently utilized to reduce iron and other metal oxides in the blast furnace ironmaking process, which has higher utilization added value and process synergistic carbon reduction effect, and gets rid of the traditional path of using coal gas for heating and power generation.

[0026] (2) In response to the technical challenges of removing carbon dioxide from industrial waste gas and heating it before use in blast furnace injection, a method is proposed that relies on the efficient mass and heat transfer reaction environment of the high-temperature molten steel pool to simultaneously complete the two tasks of waste gas modification and heating in the steelmaking reaction pool. This method can convert carbon dioxide into carbon monoxide and crack hydrocarbons in the waste gas to generate carbon monoxide and hydrogen, thereby increasing the concentration of reducing gas in the waste gas. The high-temperature molten pool environment is used to heat the waste gas, resulting in a fast heating rate without carbon precipitation reaction, which reduces the difficulty of equipment operation and maintenance.

[0027] (3) Unlike the switching of the entire group of gas reformers A and B in working and heat preservation states, the above-mentioned series and parallel connection of the four gas reformers in gas reformer A and B groups and the sequential seamless switching of the three states of working, heat preservation and shutdown can ensure that at any time, while two gas reformers are working in series, one gas reformer is in a shutdown state, without consuming energy for heat preservation, thus greatly saving heat preservation energy consumption.

[0028] The following will further explain the concept, specific structure, and technical effects of the present invention in conjunction with the accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of a low-carbon ironmaking system and method based on online upgrading and heating injection of industrial exhaust gas in a preferred embodiment of the present invention.

[0030] Figure 2 This is a schematic diagram showing the switching of the working states of the two gas reforming furnaces A and B in a preferred embodiment of the present invention.

[0031] Reference numerals in the attached drawings: 1-Industrial exhaust gas storage tank, 2-Gas compressor, 3-First pipeline gas composition detection device, 4-Gas pressure and flow control system, 5-First three-way valve, 6-Gas reformer group A, 7-Gas reformer group B, 8-Second three-way valve, 9-Pipeline gas temperature sensor, 10-Second pipeline gas composition detection device, 11-Blast furnace injection device, 12-Third three-way valve, 13-Fourth three-way valve. Detailed Implementation

[0032] The following description, with reference to the accompanying drawings, illustrates several preferred embodiments of the present invention to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.

[0033] In this embodiment, a low-carbon ironmaking system and method based on online upgrading and temperature-increasing injection of industrial exhaust gas according to the present invention is applied to an effective volume of 480m³. 3 blast furnace.

[0034] like Figure 1 As shown, a low-carbon ironmaking system based on online upgrading and temperature-increasing injection of industrial tail gas includes: an industrial tail gas storage tank 1, a gas compressor 2, a first pipeline gas composition detection device 3, a gas pressure and flow control system 4, a first three-way valve 5, a gas upgrading furnace A group 6, a gas upgrading furnace B group 7, a second three-way valve 8, a pipeline gas temperature sensor 9, a second pipeline gas composition detection device 10, and a blast furnace injection device 11.

[0035] The gas reformer has a capacity of 100t, and there are 5 gas reformers in each group. Blast furnace gas is used as the industrial tail gas feedstock, and its volume fraction is: 25.37% CO2, 19.82% CO, 2.03% H2, and the remainder is nitrogen.

[0036] The industrial exhaust gas source after dust removal is connected to the industrial exhaust gas storage tank through pipeline P1. The gas outlet of the industrial exhaust gas storage tank is connected to the gas compressor through pipeline P2. After pressurization, the gas is connected to the first pipeline gas composition detection device 3 through pipeline P3. After composition detection, it is connected to the gas pressure and flow control system 4 through pipeline P4. After the gas pressure and flow are adjusted, it is connected to the first three-way valve 5 through pipeline P5. The first outlet of the first three-way valve 5 is connected to the gas inlet of gas reformer A group 6 through pipeline P6. The second outlet of the first three-way valve 5 is connected to the gas inlet of gas reformer B group 7 through pipeline P7. The gas outlet of gas reformer A group 6 is connected to the first inlet of the second three-way valve 8 through pipeline P8. The gas outlet of gas reformer B group 7 is connected to the second inlet of the second three-way valve 8 through pipeline P9. The outlet of the second three-way valve 8 is connected to the pipeline gas temperature sensor 9 through pipeline P10, then to the second pipeline gas composition detection device 10 through pipeline P11, and finally to the blast furnace injection device through pipeline P12.

[0037] The specific implementation steps of a low-carbon ironmaking method based on online upgrading and temperature-increasing injection of industrial exhaust gas according to the present invention include:

[0038] (1) Preparation stage: 100t pig iron is loaded into the gas reforming furnace A group 6 and B group 7 as molten pool metal phase raw materials, and 5t high-purity magnesium oxide is added as slag regulator. The metal phase raw materials are melted by electricity and the molten pool temperature is raised to above 1600℃.

[0039] (2) Industrial tail gas reforming and heating stage: Adjust the power of the heating elements of each gas reformer in group A6 to an operating power of 50,000 kW, and adjust the power of the heating elements of each gas reformer in group B7 to a heat preservation power of 15,000 kW. Open the first outlet of the first three-way valve 5 and close the second outlet. After adjusting the gas pressure and flow rate, the industrial tail gas in the industrial tail gas storage tank is introduced into the gas reformer through the bottom blowing elements placed at the bottom of each gas reformer in group A6. The industrial tail gas flow rate is 30,000 Nm³. 3 / h, the gas flow rate supplied to each gas reformer is 6000 Nm³. 3 The industrial tail gas is upgraded and heated by reacting CO2 gas with liquid iron in the molten pool to form CO gas. At the same time, the slag reduction ferrite regeneration device is started. The carbonaceous reducing agent addition rate is calculated and set to 700 kg / h based on the industrial tail gas flow rate and CO2 gas concentration. The first inlet of the second three-way valve 8 is opened and the second inlet is closed. After the upgraded and heated industrial tail gas is detected by the pipeline gas temperature sensor and the second pipeline gas composition detection device 10, the temperature of the upgraded and heated industrial tail gas is 1150℃, and its composition is 4.02% CO2, 41.17% CO, 2.03% H2, and the remainder is nitrogen. It is then blown into the blast furnace through the blast furnace injection device.

[0040] (3) Gas reforming furnace reversal stage: After the system has been running for 6 hours, adjust the power of the heating elements of each gas reforming furnace in group A 6 to the heat preservation power of 15000kW, adjust the power of the heating elements of each gas reforming furnace in group B 7 to the operating power of 50000kW, close the first outlet of the first three-way valve and open the second outlet, and introduce the industrial tail gas in the industrial tail gas storage tank into the gas reforming furnace through the bottom blowing element placed at the bottom of each gas reforming furnace in group B 7 after adjusting the gas pressure and flow rate, and reform and heat the industrial tail gas, that is, the CO2 gas in the industrial tail gas reacts with the liquid iron in the molten pool to become CO gas, and at the same time start the slag reduction ferrite regeneration device, and set the external DC power electrolysis power or carbonaceous reducing agent addition acceleration rate according to the industrial tail gas flow rate and its CO2 gas concentration, and at the same time close the first inlet of the second three-way valve 8 and open the second inlet, and after detecting the composition and temperature of the reformed and heated industrial tail gas, blow it into the blast furnace through the blast furnace injection device 11. Iron-based raw materials and high-purity magnesium oxide are added to the molten pool through hopper 6 of group A of the gas reformer. After the newly added iron-based raw materials and slag in the molten pool have completely melted, the system enters the heat preservation and standby stage. After the system has run another cycle, the gas reformer switching stage is repeated, with group 6 of gas reformer A entering the heat preservation and standby stage, and group 7 of gas reformer B entering the reforming and heating stage.

[0041] In other embodiments, the gas-modified furnace has a tonnage of 5t-100t and can supply heat to the molten steel pool using induction coils or plasma heating. The gas-modified furnace should be equipped with a sealing device to prevent air from entering the oxidized molten steel and should be able to withstand a pressure of 0.5MPa. A sealed silo for iron-based raw materials and high-purity magnesium oxide is also installed on the upper part of the furnace. The gas-modified furnace should be equipped with a slag reduction ferrite regeneration device, which can be achieved by electrolyzing the molten steel and slag with an external DC power supply or by adding a carbonaceous reducing agent into the molten pool.

[0042] Industrial exhaust gases include coking coal gas, blast furnace gas, converter gas, and other gases containing carbon monoxide, hydrogen, or hydrocarbons.

[0043] The gas reforming furnace has an operating power of 3000-50000kW and an insulation power of 1000-20000kW.

[0044] The external DC power supply for the ferrous regeneration device in slag reduction has a current range of 1-300kA and a voltage range of 10-1000V. The current of the external DC power supply is adjusted by real-time monitoring of the ferrous oxide content in the slag. The acceleration rate of carbonaceous reducing agent addition is calculated according to the following formula:

[0045]

[0046] In the formula:

[0047] m—acceleration rate of carbonaceous reducing agent, kg / h;

[0048] V — Industrial exhaust gas flow rate input to this low-carbon ironmaking system, Nm³ 3 / h;

[0049] —The volume percentage of carbon dioxide in the industrial exhaust gas input to this low-carbon ironmaking system, -;

[0050] n——The number of furnaces in each group of gas reformers in this low-carbon ironmaking system, -;

[0051] ω C —The mass fraction of carbon in the carbonaceous reducing agent used in this method, -.

[0052] The number of gas reformers in each group is determined according to the requirements of the blast furnace injection process and the furnace capacity of the gas reformer.

[0053] In such Figure 2 In the illustrated embodiment, gas reformer group A6 includes two gas reformers A1 and A2 connected in series; gas reformer group B7 includes two gas reformers B1 and B2 connected in series; and gas reformers A1 and A2 are connected in parallel with gas reformers B1 and B2 respectively through three-way valves 12 and 13.

[0054] exist Figure 2 In state (1), gas reformers A1 and A2 are in working condition, gas reformer B1 is in shutdown (no external heating), and B2 is in heat preservation condition; at this time, the industrial tail gas passes through three-way valves 5, 12 and 8 in sequence, and flows through gas reformers A1 and A2 for reforming and heating; in state (2), gas reformers A1 and B2 are in working condition, gas reformer A2 is in shutdown condition, and B1 is in heat preservation condition; at this time, the industrial tail gas passes through three-way valves 5, 12, 13 and 8 in sequence, and flows through gas reformers A1 and B2 for reforming and heating; In state (3), gas reformers B1 and B2 are in working state, gas reformer A1 is in shutdown state, and A2 is in heat preservation state; at this time, the industrial tail gas passes through three-way valves 5, 13 and 8 in sequence, and flows through gas reformers B1 and B2 for reforming and heating; in state (4), gas reformers B1 and A2 are in working state, gas reformer B2 is in shutdown state, and A1 is in heat preservation state; at this time, the industrial tail gas passes through three-way valves 5, 13, 12 and 8 in sequence, and flows through gas reformers B1 and B2 for reforming and heating; then switch back to state (1).

[0055] Unlike the complete switching between working and heat preservation states of gas reformer groups A and B, the above-mentioned seamless switching between the series and parallel connection of the four gas reformers in groups A and B, as well as the sequential switching between working, heat preservation, and shutdown states, ensures that at any given time, while two gas reformers are working in series, one gas reformer is in a shutdown state, eliminating the need for heat preservation and thus greatly saving heat preservation energy consumption.

[0056] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A low-carbon ironmaking method based on online upgrading of industrial off-gas for temperature-raising injection, characterized in that, Comprising the steps of: (1) providing a low-carbon ironmaking system based on online upgrading of industrial tail gas for temperature-raising injection, comprising an industrial tail gas storage tank, a gas pressurizing machine, a first pipeline gas component detection device, a second pipeline gas component detection device, a gas pressure flow control system, a pipeline gas temperature sensor, a first three-way valve, a group A gas upgrading furnace, a group B gas upgrading furnace, a second three-way valve, and a blast furnace injection device; the dedusted industrial tail gas source is connected to the industrial tail gas storage tank through a first pipeline, the gas outlet of the industrial tail gas storage tank is connected to the gas pressurizing machine through a second pipeline, the pressurized gas is connected to the first pipeline gas component detection device through a third pipeline, then connected to the gas pressure flow control system through a fourth pipeline, then connected to the first three-way valve through a fifth pipeline, the first outlet of the first three-way valve is connected to the gas inlet of the group A gas upgrading furnace through a sixth pipeline, the second outlet of the first three-way valve is connected to the gas inlet of the group B gas upgrading furnace through a seventh pipeline, the gas outlet of the group A gas upgrading furnace is connected to the first inlet of the second three-way valve through an eighth pipeline, the gas outlet of the group B gas upgrading furnace is connected to the second inlet of the second three-way valve through a ninth pipeline, the outlet of the second three-way valve is connected to the pipeline gas temperature sensor through a tenth pipeline, connected to the second pipeline gas component detection device through an eleventh pipeline, and then connected to the blast furnace injection device through a twelfth pipeline; (2) preparation stage: iron-containing raw materials are loaded into the group A and group B gas upgrading furnaces as molten pool metal phase raw materials, and high-purity magnesium oxide is added as a slag modifier, and the metal phase raw materials are melted by passing electricity; (3) industrial tail gas upgrading and temperature-raising stage: the power of each gas upgrading furnace heating element in the group A gas upgrading furnace is adjusted to the operating power, the power of each gas upgrading furnace heating element in the group B gas upgrading furnace is adjusted to the heat preservation power, the first outlet of the first three-way valve is opened and the second outlet is closed, the industrial tail gas in the industrial tail gas storage tank is introduced into the gas upgrading furnace through the bottom blowing elements placed at the bottom of each gas upgrading furnace in the group A gas upgrading furnace after adjusting the gas pressure and flow, the industrial tail gas is upgraded and temperature-raised, that is, the CO2 gas in the industrial tail gas reacts with the liquid iron in the molten pool to become CO gas, the hydrocarbons in the industrial tail gas are cracked into reducing gases including CO and H2 in the high-temperature molten pool, and at the same time, the molten slag reduction iron regeneration device is started, the external direct current power electrolysis power or the carbonaceous reducing agent addition rate is set according to the flow of the industrial tail gas and the CO2 gas concentration, at the same time, the first inlet of the second three-way valve is opened and the second inlet is closed, and after detecting the components and temperature of the upgraded and temperature-raised industrial tail gas, the industrial tail gas is injected into the blast furnace through the blast furnace injection device. (4) Gas reforming furnace reversing stage: adjust the power of each gas reforming furnace heating element in group A to the holding power, adjust the power of each gas reforming furnace heating element in group B to the operating power, close the first outlet and open the second outlet in three-way valve A, adjust the industrial tail gas in the industrial tail gas storage tank to flow through the bottom blowing element placed at the bottom of each gas reforming furnace in group B to the gas reforming furnace, and then the industrial tail gas is reformed and heated, so that the CO2 gas in the industrial tail gas reacts with the liquid iron in the molten pool to become CO gas, and the hydrocarbons in the industrial tail gas are cracked into reducing gases including CO and H2 in the high-temperature molten pool, and at the same time, the molten slag reduction iron regeneration device is started, the electrolysis power of the external direct current power supply or the addition rate of the carbonaceous reducing agent is set according to the flow rate of the industrial tail gas and the CO2 gas concentration, at the same time, the first inlet and the second inlet in three-way valve B are closed and opened, and then the industrial tail gas after reforming and heating is detected for composition and temperature, and then blown into the blast furnace through the blast furnace injection device; iron-based raw materials and high-purity magnesium oxide are added to the molten pool of group A gas reforming furnace, and then after the newly added iron-based raw materials and slag in the molten pool are completely melted, the holding standby stage is entered; Wherein, group A gas reforming furnace includes two gas reforming furnaces A1 and A2 connected in series; group B gas reforming furnace includes two gas reforming furnaces B1 and B2 connected in series; and gas reforming furnaces A1 and A2 are connected in parallel with gas reforming furnaces B1 and B2 through third three-way valve and fourth three-way valve respectively; Wherein, in the first state, gas reforming furnaces A1 and A2 are in working state, gas reforming furnace B1 is in shutdown state, and gas reforming furnace B2 is in holding state; at this time, the industrial tail gas flows through gas reforming furnaces A1 and A2 for reforming and heating in sequence through first three-way valve, third three-way valve and second three-way valve; in the second state, gas reforming furnaces A1 and B2 are in working state, gas reforming furnace A2 is in shutdown state, and gas reforming furnace B1 is in holding state; at this time, the industrial tail gas flows through gas reforming furnaces A1 and B2 for reforming and heating in sequence through first three-way valve, third three-way valve, fourth three-way valve and second three-way valve; in the third state, gas reforming furnaces B1 and B2 are in working state, gas reforming furnace A1 is in shutdown state, and gas reforming furnace A2 is in holding state; at this time, the industrial tail gas flows through gas reforming furnaces B1 and B2 for reforming and heating in sequence through first three-way valve, fourth three-way valve and second three-way valve; in the fourth state, gas reforming furnaces B1 and A2 are in working state, gas reforming furnace B2 is in shutdown state, and gas reforming furnace A1 is in holding state; at this time, the industrial tail gas flows through gas reforming furnaces B1 and B2 for reforming and heating in sequence through first three-way valve, fourth three-way valve, third three-way valve and second three-way valve; and then switch back to the first state.

2. The low-carbon ironmaking process based on online upgrading of industrial off-gas for temperature-increasing injection of claim 1, wherein, The industrial tail gas includes coke coal gas, blast furnace gas and converter gas.

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