Ironmaking system and method coupling solid oxide electrolysis with blast furnace waste heat utilization

Abstract

The present invention relates to an ironmaking system and method that couples solid oxide electrolysis with blast furnace waste heat utilization. The system comprises a solid oxide electrolysis system, a hot blast system, a heat exchange network, and a blast furnace body. The solid oxide electrolysis system, driven by the coupling of an external power source and blast furnace waste heat, produces hydrogen and oxygen by electrolyzing water. The hot blast system, fueled by blast furnace gas, continuously delivers high-temperature hot blast to the blast furnace. The heat exchange system uses the waste heat generated by the blast furnace to heat the fuel at the inlet of the solid oxide electrolysis cell and the hydrogen at the inlet of the blast furnace. The blast furnace body is used to reduce ore to smelt pig iron. By recycling waste heat from the blast furnace ironmaking process through the heat exchange network, heating the water at the inlet of the solid oxide electrolysis system and the hydrogen at the inlet of the blast furnace, the system effectively reduces the power consumption of the electrolytic hydrogen production process and is of great significance for the deep energy conservation and carbon reduction of blast furnace hydrogen-rich metallurgy technology.

Description

Technical Field

[0001] The present invention relates to an ironmaking system and method that couples solid oxide electrolysis with blast furnace waste heat utilization, belonging to the technical field of hydrogen energy utilization and blast furnace ironmaking, and specifically to a technical solution that uses hydrogen and oxygen generated by electrolysis in the process of blast furnace ironmaking, and improves the overall ironmaking efficiency by utilizing blast furnace waste heat. Background Art

[0002] The traditional blast furnace ironmaking process uses coke as a reducing agent and fuel to reduce iron ore to iron. Consequently, blast furnace ironmaking is accompanied by the production of large amounts of greenhouse gases, including carbon dioxide. With global warming and the intensification of the greenhouse effect, there is an urgent need to develop new steelmaking technologies to promote a green transformation of the steel industry and reduce energy consumption and carbon emissions during the ironmaking process. In recent years, hydrogen, a clean reducing agent and fuel, has been used to replace coke in blast furnace ironmaking due to its strong reducing power and clean, low-carbon properties. This has significant implications for energy conservation and carbon reduction in difficult-to-decarbonize sectors, such as blast furnace ironmaking.

[0003] Blast furnace hydrogen-rich smelting technology is one of the main hydrogen metallurgical processes. Its technical principle is to inject pure hydrogen or hydrogen-rich gas during the blast furnace smelting process to reduce the iron ore in the furnace, reduce the injection amount of coke / coal, and reduce the production of CO2 from the source.

[0004] However, the current blast furnace hydrogen-rich smelting technology has the following problems:

[0005] When a large amount of hydrogen is injected into the blast furnace, hydrogen reduction is a strong endothermic reaction, and the temperature inside the furnace drops. How to solve the heat compensation problem of the blast furnace is particularly critical; the blast furnace ironmaking process will produce blast furnace gas, blast furnace slag and other by-products, which contain a large amount of waste heat that is not fully utilized. Therefore, the waste heat utilization rate of blast furnace ironmaking is low, and attention should be paid to the waste heat recovery and utilization technology; in the blast furnace system that currently uses water electrolysis to produce hydrogen as the source of hydrogen, water electrolysis to produce hydrogen and the blast furnace are still two relatively independent systems, and the hydrogen metallurgical process has not yet been optimized from the perspective of the entire process. We continue to explore new hydrogen metallurgical systems that are deeply coupled with water electrolysis to produce hydrogen and blast furnace ironmaking.

[0006] The invention patent CN115341057A published on November 15, 2022, involves a blast furnace hydrogen-rich smelting system and method, including a power generation system, a water electrolysis system, a blowing system, a preheating system, and a hot air system. Renewable energy is used to generate electricity to drive water electrolysis, and the generated hydrogen is preheated by the preheating system and then enters the blast furnace body for use. On the one hand, the use of hydrogen can achieve the emission reduction effect of steel smelting. On the other hand, the use of renewable energy for power generation can solve the energy waste problem of renewable energy. However, this system does not take into account the effective utilization of waste heat resources in the blast furnace ironmaking process. It is only a blast furnace hydrogen-rich smelting system that simply couples water electrolysis to produce hydrogen with the blast furnace.

[0007] The invention patent CN116732259A published on September 12, 2023, relates to a smelting method and system for injecting hydrogen-rich gas into a blast furnace, which mainly includes heating and cracking green ammonia to obtain hydrogen and nitrogen, and mixing them with the remaining green ammonia to obtain hydrogen-rich gas, which then enters the blast furnace for smelting. The use of green ammonia as a carrier for hydrogen transportation solves the problems of poor hydrogen safety and transportation difficulties. At the same time, the injection of hydrogen-rich gas into the blast furnace indirectly realizes the stable injection of green pure hydrogen in the blast furnace, improves the indirect reduction degree of the blast furnace, and reduces carbon emissions in the ironmaking process. However, the system uses electric heating to preheat the hydrogen-rich gas to provide part of the heat for the blast furnace hydrogen-rich smelting. The hydrogen preheating process causes the system to consume a high amount of power.

[0008] The invention patent CN115522003A published on December 27, 2022, involves a hydrogen-rich blast furnace ironmaking system based on energy-to-mass conversion and its production control method, including an electrolytic water system, a hydrogen injection valve group, an oxygen injection valve group, and a hydrogen preheating system. The hydrogen produced by electrolytic water is pressurized by a compressor and sent to the hydrogen preheating system for preheating. The preheated hydrogen is injected into the blast furnace, and the oxygen produced by electrolytic water is injected into the blast furnace after adjusting the pressure and flow rate by the oxygen injection valve group. However, the system uses electric heating to preheat hydrogen, and the preheating process consumes high power. The electrolytic hydrogen production and the blast furnace are simply integrated, and the waste heat from the blast furnace ironmaking process is not effectively recovered, resulting in low waste heat utilization efficiency. Summary of the Invention

[0009] To overcome the above-mentioned deficiencies of the prior art, the present invention provides an ironmaking system and method that couples solid oxide electrolysis with blast furnace waste heat utilization, specifically adopting the following technical solutions:

[0010] An ironmaking system that couples solid oxide electrolysis with blast furnace waste heat utilization, comprising a solid oxide electrolysis system, a hot air system, a heat exchange system, and a blast furnace body;

[0011] The blast furnace body is used to reduce ore and smelt pig iron;

[0012] The solid oxide electrolysis system, driven by the coupling of an external power supply and waste heat from the blast furnace, produces hydrogen and oxygen by electrolyzing water; the anode outlet of the solid oxide electrolysis system is connected to a hot air system, through which air enters the hot air system; the cathode outlet of the solid oxide electrolysis system is connected to the blast furnace, and hydrogen is heated by a heat exchanger and injected into the blast furnace;

[0013] The air outlet at the top of the blast furnace body is connected to the hot air system, through which blast furnace gas enters the hot air system; the hot air system uses blast furnace gas as fuel to continuously deliver high-temperature hot air to the blast furnace body;

[0014] The slag outlet at the bottom of the blast furnace body is connected to a heat exchanger, and the sensible heat of the slag is recovered by the heat exchanger;

[0015] The heat exchange system connects various heat exchangers and uses the waste heat generated by the blast furnace body to heat the materials at the inlet of the solid oxide electrolysis cell and the hydrogen at the inlet of the blast furnace; the heat exchange system integrates the heat load of all components of the entire system to achieve the cascade recovery and utilization of heat in the electrolytic hydrogen production process and the blast furnace ironmaking process.

[0016] Wherein, the solid oxide electrolysis system comprises an electrolytic cell;

[0017] The cathode inlet of the electrolytic cell is a water inlet, which is sequentially connected to a water pump, a low-temperature heat exchanger and a high-temperature heat exchanger; the water vapor is heated to 800°C by the low-temperature heat exchanger and the high-temperature heat exchanger and enters the electrolytic cell;

[0018] The cathode outlet is connected to the steam heat exchanger at the outlet of the battery stack and the steam-water separator in sequence. The hydrogen outlet of the steam-water separator is connected to the hydrogen heat exchanger at the blast furnace inlet of the blast furnace body. The hydrogen is heated to 800℃~1200℃ by the hydrogen heat exchanger at the blast furnace inlet and injected into the blast furnace body.

[0019] The anode inlet of the electrolytic cell is an air inlet, which is connected to an air compressor and an air heat exchanger in sequence; the air is heated to 800°C by the air heat exchanger and enters the electrolytic cell;

[0020] The anode outlet is connected to the stack outlet air heat exchanger and the hot air system through a tee.

[0021] Wherein, the hot air system includes a hot air furnace;

[0022] The hot blast furnace is connected to the top air outlet of the blast furnace body through a dust collector and a desulfurizer. The hot blast furnace uses blast furnace gas as fuel, and burns to heat the cold air to 1200℃ before entering the blast furnace body. The flue gas outlet of the hot blast furnace is equipped with a hot blast furnace outlet flue gas heat exchanger.

[0023] Furthermore, a slag heat exchanger and a slag processing device are provided at the slag outlet at the bottom of the blast furnace body, and the sensible heat of the slag is recovered by the slag heat exchanger.

[0024] The present invention provides an ironmaking method that couples solid oxide electrolysis with blast furnace waste heat utilization, which is implemented using the aforementioned ironmaking system that couples solid oxide electrolysis with blast furnace waste heat utilization, and includes the following steps:

[0025] After being pressurized, water and air are passed into a heat exchanger and heated to 800°C. They are then passed into the cathode and anode of the solid oxide electrolysis system respectively. An external power supply is applied to the solid oxide electrolysis system, and the water vapor is electrolyzed into hydrogen and oxygen.

[0026] The air from the anode outlet of the solid oxide electrolysis system enters the hot air system, where it reacts with the blast furnace gas to release heat, and the cold air is heated to 1200°C and fed into the blast furnace body.

[0027] The hydrogen at the cathode outlet of the solid oxide electrolysis system is heated to 800°C in a heat exchanger and then enters the blast furnace body. The iron ore undergoes a reduction reaction with the hydrogen and coal powder to produce molten iron, blast furnace gas and slag. The blast furnace gas enters the hot air system from the air outlet at the top of the blast furnace body, and the slag enters the heat exchanger for cooling from the slag outlet at the bottom of the blast furnace body.

[0028] The technical solution of the present invention achieves the following beneficial effects:

[0029] (1) The ironmaking system coupled with solid oxide electrolysis and blast furnace waste heat utilization proposed in the present invention integrates the heat loads of the various components of the entire ironmaking system through a heat exchange network, realizes the cascade recovery and utilization of waste heat in the solid oxide electrolysis hydrogen production and blast furnace ironmaking processes, and improves the comprehensive energy utilization efficiency of electrolytic hydrogen production and blast furnace ironmaking.

[0030] (2) The ironmaking system coupled with solid oxide electrolysis and blast furnace waste heat utilization proposed in the present invention realizes the cascade utilization of heat within the system through a heat exchange network, and uses the heat generated by the blast furnace ironmaking process to preheat the water at the electrolytic cell inlet, providing heat compensation for the solid oxide electrolysis hydrogen production process, reducing the power consumption of the hydrogen production process, and reducing the power consumption rate of hydrogen production.

[0031] (3) The ironmaking system coupled with solid oxide electrolysis and blast furnace waste heat utilization proposed in the present invention uses the heat generated in the blast furnace ironmaking process to heat the hydrogen at the blast furnace inlet through a heat exchange network, thereby solving the heat compensation problem of blast furnace hydrogen-rich smelting and ensuring the smelting temperature of the blast furnace.

[0032] (4) The present invention proposes an ironmaking system that couples solid oxide electrolysis with blast furnace waste heat utilization, using hydrogen generated by water electrolysis to replace part of the coke as a reducing agent and exothermic agent, thereby reducing the ironmaking process's dependence on coke and significantly reducing carbon dioxide emissions, which is of great significance to energy conservation and carbon reduction in the ironmaking process. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the system structure of the present invention.

[0034] Figure 2 Schematic diagram of the heat exchange network of the present invention.

[0035] The specific meanings of the figure marks in the accompanying drawings are: 1-air compressor, 2-water pump, 3-air heat exchanger, 4-low-temperature heat exchanger, 5-high-temperature heat exchanger, 6-electrolyzer, 7-stack outlet air heat exchanger, 8-stack outlet steam heat exchanger, 9-steam-water separator, 10-blast furnace inlet hydrogen heat exchanger, 11-hot blast furnace outlet flue gas heat exchanger, 12-hot blast furnace, 13-dust collector, 14-desulfurizer, 15-blast furnace body, 16-slag heat exchanger, 17-slag treatment device, 18-heat exchange system. DETAILED DESCRIPTION

[0036] The present invention proposes an ironmaking system that couples solid oxide electrolysis with blast furnace waste heat utilization. The present invention will be further described below with reference to the accompanying drawings.

[0037] Example 1:

[0038] like Figure 1 As shown, this embodiment 1 discloses an ironmaking system that couples solid oxide electrolysis with blast furnace waste heat utilization, including a solid oxide electrolysis system, a hot air system, a heat exchange system 18 and a blast furnace body 15;

[0039] The blast furnace body 15 is used to reduce ore and smelt pig iron;

[0040] The solid oxide electrolysis system includes an electrolytic cell 6; the cathode inlet of the electrolytic cell 6 is a water inlet, which is connected in sequence to a water pump 2, a low-temperature heat exchanger 4 and a high-temperature heat exchanger 5; the water vapor is heated to 800°C through the low-temperature heat exchanger 4 and the high-temperature heat exchanger 5 and enters the electrolytic cell 6; the cathode outlet is connected to the stack outlet steam heat exchanger 8 and the steam-water separator 9 in sequence, and the hydrogen outlet of the steam-water separator 9 is connected to the blast furnace inlet hydrogen heat exchanger 10 of the blast furnace body 15; the hydrogen is heated to 800°C to 1200°C through the blast furnace inlet hydrogen heat exchanger 10 and is blown into the blast furnace body 15; the anode inlet of the electrolytic cell 6 is an air inlet, which is connected in sequence to an air compressor 1 and an air heat exchanger 3; the air is heated to 800°C through the air heat exchanger 3 and enters the electrolytic cell 6; the anode outlet is connected to the stack outlet air heat exchanger 7 and the hot air system through a tee.

[0041] The solid oxide electrolysis system, driven by the coupling of an external power supply and the waste heat of the blast furnace body 15, produces hydrogen and oxygen by electrolyzing water; the anode outlet of the solid oxide electrolysis system is connected to the hot air system, and air enters the hot air system; the cathode outlet is connected to the blast furnace body 15, and hydrogen is heated by a heat exchanger and blown into the blast furnace body 15.

[0042] The top air outlet of the blast furnace body 15 is connected to the hot air system, through which blast furnace gas enters the hot air system; the hot air system uses blast furnace gas as fuel to continuously transport high-temperature hot air to the blast furnace body 15; the hot air system includes a hot air furnace 12; the hot air furnace 12 is connected to the top air outlet of the blast furnace body 15 through a dust collector 13 and a desulfurizer 14, and the hot air furnace 12 uses blast furnace gas as fuel, and burns to heat the cold air to 1200°C before it enters the blast furnace body 15; the flue gas outlet of the hot air furnace 12 is provided with a hot air furnace outlet flue gas heat exchanger 11.

[0043] A slag heat exchanger 16 and a slag treatment device 17 are provided at the slag outlet at the bottom of the blast furnace body 15 , and the sensible heat of the slag is recovered by the slag heat exchanger 16 .

[0044] The heat exchange system 18 is connected to each of the above-mentioned heat exchangers, and uses the waste heat generated by the blast furnace body 15 to heat the materials at the inlet of the solid oxide electrolysis cell and the hydrogen at the inlet of the blast furnace; the heat exchange system 18 integrates the heat load of each component of the entire system, and realizes the cascade recovery and utilization of heat in the electrolytic hydrogen production process and the blast furnace ironmaking process.

[0045] The specific material flow process is as follows: water is pressurized by the water pump 2 and heated by the low-temperature heat exchanger 4 and the high-temperature heat exchanger 5 to become high-temperature water vapor, which is passed into the cathode of the electrolytic cell 6. The air is pressurized by the air compressor 1 and heated by the air heat exchanger 3, and passed into the anode of the electrolytic cell 6. Driven by an external power supply, the high-temperature water vapor undergoes an electrochemical reaction in the electrolytic cell 6 to produce hydrogen and oxygen. The mixed gas of hydrogen and residual water vapor at the cathode outlet of the electrolytic cell 6 is cooled by the steam heat exchanger 8 at the outlet of the stack, and then enters the steam-water separator 9 to separate hydrogen and water. The separated pure hydrogen is heated by the hydrogen heat exchanger 10 at the blast furnace inlet and then sent to the blast furnace body 15. The water is directly discharged from the system. The oxygen-enriched air at the anode outlet of the electrolytic cell 6 is divided into two parts, one part The oxygen-enriched air and blast furnace gas are burned in the hot blast furnace 12, and the heat generated heats the cold air into high-temperature hot air and then enters the blast furnace body 15. The flue gas generated by the combustion is cooled by the flue gas heat exchanger 11 at the hot blast furnace outlet and then discharged from the system. The ore, coal powder and hydrogen undergo a reduction reaction in the blast furnace pump body 15, and the molten iron produced by the reaction flows out from the iron outlet at the bottom of the blast furnace body 15. The slag enters the slag heat exchanger 16 from the slag outlet at the bottom of the blast furnace body 15 for cooling and then discharged to the slag treatment device 17. The blast furnace gas enters the hot blast furnace 12 from the top air outlet of the blast furnace body 15 after being purified by the dust collector 13 and the desulfurizer 14 for combustion and heating.

[0046] The heat exchange system 18 integrates the heat loads of various components of the entire ironmaking system through utilities. Using cold and hot fluids as media, it achieves cascaded heat recovery and utilization within the system, reducing utility load and improving heat integration efficiency. Heat exchange system 18 is connected to air heat exchanger 3, low-temperature heat exchanger 4, high-temperature heat exchanger 5, air heat exchanger 7 at the stack outlet, steam heat exchanger 8 at the stack outlet, steam-water separator 9, hydrogen heat exchanger 10 at the blast furnace inlet, flue gas heat exchanger 11 at the hot blast furnace outlet, and slag heat exchanger 16. There are four cold flows: water at the inlet of low-temperature heat exchanger 4, steam at the inlet of high-temperature heat exchanger 5, air at the inlet of air heat exchanger 3, and hydrogen at the inlet of blast furnace 15. There are five hot flows: blast furnace slag, a mixture of steam and hydrogen at the cathode outlet of the stack, air at the anode outlet of the stack, hot blast furnace flue gas, and hydrogen at the blast furnace inlet. The hot utility is the heating furnace, and the cold utility is cooling water.

[0047] Example 2:

[0048] This Example 2 uses the metallurgical system of the solid oxide electrolytic cell coupled with a blast furnace, wherein the blast furnace is a 5000m 3 , a large blast furnace with an annual production capacity of 3.83 million tons. Some parameters of the blast furnace ironmaking process are shown in Table 1.

[0049] Table 1 Parameters of blast furnace ironmaking system

[0050]

[0051]

[0052] like Figure 1 As shown, water is pressurized by a water pump 2 and then heated to 107°C by a low-temperature heat exchanger 4, and then heated to 800°C by a high-temperature heat exchanger 5 before being passed into the cathode of the electrolytic cell 6. Air is pressurized by a compressor 1 and then heated to 800°C by an air heat exchanger 3 before being passed into the anode of the electrolytic cell 6. High-temperature water vapor undergoes an electrochemical reaction in the electrolytic cell 6 to produce hydrogen and oxygen. The mixed gas (700°C) of hydrogen and remaining water vapor at the cathode outlet of the electrolytic cell 6 is cooled to 120°C by the steam heat exchanger 8 at the outlet of the stack, and enters the steam-water separator 9 to separate hydrogen and water. The separated pure hydrogen (40°C) is heated to 800°C by the hydrogen heat exchanger 10 at the blast furnace inlet and is sent into the blast furnace body 15, and water is directly discharged from the system. The anode outlet of the electrolytic cell 6 Part of the oxygen-enriched air (700℃) directly enters the hot blast stove 12, and the other part is cooled to 30℃ through the air heat exchanger 7 at the stack outlet and discharged; the oxygen-enriched air and blast furnace gas are burned in the hot blast stove 12, and the heat generated heats the 25℃ cold air into 1200℃ high-temperature hot air and then enters the blast furnace body 15. The 300℃ flue gas generated by the combustion is cooled to 30℃ through the flue gas heat exchanger 11 at the hot blast stove outlet and discharged; the slag (1500℃) generated in the ironmaking process enters the slag heat exchanger 16 from the slag outlet at the bottom of the blast furnace body 15 and is cooled to 30℃ and discharged from the system. The blast furnace gas (120℃) enters the hot blast stove 12 from the top air outlet of the blast furnace body 15 after being purified by the dust collector 13 and the desulfurizer 14 for combustion and heat supply.

[0053] Depend on Figure 1 It can be seen that the heat exchange system 18 has four cold streams and five hot streams. Table 2 gives the parameters of the cold and hot streams, where 10°C is the minimum heat exchange temperature difference of the heat exchange network. The heat exchange network process is as follows: Figure 2As shown. The slag heat exchanger 16 exchanges heat with the air heat exchanger, the blast furnace inlet hydrogen heat exchanger 10, the low-temperature heat exchanger 4, and the high-temperature heat exchanger 5 respectively, reducing the slag temperature from 1500°C to 127°C, and then exchanges heat with the air heat exchanger 3. The slag temperature is reduced to 30°C before being discharged; the steam heat exchanger 8 at the outlet of the stack, the flue gas heat exchanger 11 at the outlet of the hot blast furnace, and the steam-water separator 9 all exchange heat with the low-temperature heat exchanger 4, among which the hydrogen at 700°C at the cathode outlet of the stack and the water vapor are heated. After the mixed gas cools to 120°C, it enters the steam-water separator. The separated hydrogen and water cool to 40°C, and the 300°C flue gas at the hot blast furnace outlet cools to 30°C before being discharged. The air heat exchanger 7 at the stack outlet exchanges heat with the cold utility, cooling the 700°C oxygen-enriched air at the stack anode outlet to 30°C before being discharged. The hot utility exchanges heat with the high-temperature heat exchanger 5 and the air heat exchanger 3, raising the temperature of 107°C water vapor and 5°C air to 800°C before being passed into the stack. When the heat exchange network is used, the metallurgical system requires 127MW of hot utility and 0.12MW of cold utility. Without the heat exchange network, the required hot utility and cold utility are 323MW and 316MW, respectively, for a total utility energy saving of 511.88MW.

[0054] Table 2 System hot and cold logistics data

[0055]

[0056]

[0057] The calculation formula for the hydrogen production efficiency of the metallurgical system coupled with the solid oxide electrolytic cell and blast furnace is as follows:

[0058]

[0059] m H2 is the mass flow rate of hydrogen produced, kg / s; LHV H2 is the lower calorific value of hydrogen, which is 120MJ / kg; W stack is the power of the battery stack, kW; W pump is the power consumption of the pump and compressor, kW; W elec The electric heating power required for the steam generator and heater, kW.

[0060] The calculation formula for the comprehensive energy consumption of the metallurgical system of the solid oxide electrolytic cell coupled with the blast furnace is as follows:

[0061] E=W stack +W pump +W elec +V BFG ·(Q BFG +Q DW )

[0062] VBFG is the flow rate of blast furnace gas entering the hot blast stove, m 3 / s,Q BFG is the sensible heat of blast furnace gas, kJ / m 3 , Q DW is the low calorific value of blast furnace gas, kJ / m 3 .

[0063] The calculation formula for the comprehensive energy efficiency of the metallurgical system of the solid oxide electrolytic cell and blast furnace coupling is as follows:

[0064]

[0065] V hot is the flow rate of hot air entering the blast furnace, m 3 / s,C hot is the specific heat of hot air, kJ / m 3 , C cold is the specific heat of cold air, kJ / m 3 , t hot is the temperature of hot air, ℃, t cold is the temperature of cold wind, ℃.

[0066] Based on the parameters in Table 1, when the heat exchange network is not used, the hydrogen production efficiency of the metallurgical system coupled with a solid oxide electrolytic cell and a blast furnace is 44.58%, the overall energy consumption is 1096.30 MW, and the overall energy efficiency is 55.09%. When the heat exchange network is used, the system's hydrogen production efficiency is 62.96%, the overall energy consumption is 857.54 MW, and the overall energy efficiency is 70.43%. The heat exchange network achieves cascaded recovery and utilization of internal heat, reducing system energy consumption and significantly improving hydrogen production efficiency and overall system energy efficiency.

[0067] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An ironmaking system coupling solid oxide electrolysis with blast furnace waste heat utilization, characterized in that: It includes a solid oxide electrolysis system, a hot air system, a heat exchange system (18) and a blast furnace body (15); The blast furnace body (15) is used to reduce ore and smelt pig iron; In the solid oxide electrolysis system, water and air are pressurized and then introduced into a heat exchange system (18) for heating. Driven by the coupling of an external power source and the waste heat of the blast furnace body (15), the water and air are introduced into the electrolytic cell (6) and generate hydrogen and oxygen by electrolyzing water with low power consumption. The anode outlet of the solid oxide electrolysis system is connected to the hot air system, and the air enters the hot air system. The cathode outlet is connected to the blast furnace body (15). The hydrogen is heated by the heat exchanger and injected into the blast furnace body (15), providing a reducing agent and heat for the blast furnace body, thereby ensuring the temperature of the blast furnace smelting. The top air outlet of the blast furnace body (15) is connected to the hot air system, and the blast furnace gas enters the hot air system from the outlet; the hot air system uses the blast furnace gas as fuel to continuously deliver high-temperature hot air to the blast furnace body (15); The slag outlet at the bottom of the blast furnace body (15) is connected to a heat exchanger, and the sensible heat of the slag is recovered by the heat exchanger; The heat exchange system (18) integrates the heat loads of the various components of the entire ironmaking system based on the heat exchange network, determines the cascade utilization method of the heat within the system, connects the various heat exchangers, and uses the waste heat generated by the blast furnace body (15) to heat the inlet materials of the solid oxide electrolytic cell and the inlet hydrogen of the blast furnace; the heat exchange system (18) integrates the heat loads of the various components of the entire system, and realizes the cascade recovery and utilization of heat in the electrolytic hydrogen production process and the blast furnace ironmaking process; The solid oxide electrolysis system comprises an electrolytic cell (6); The cathode inlet of the electrolytic cell (6) is a water inlet, which is sequentially connected to a water pump (2), a low-temperature heat exchanger (4), and a high-temperature heat exchanger (5); water vapor is heated to 800° C. through the low-temperature heat exchanger (4) and the high-temperature heat exchanger (5) and then enters the electrolytic cell (6); The cathode outlet is connected to the stack outlet steam heat exchanger (8) and the steam-water separator (9) in sequence, and the hydrogen outlet of the steam-water separator (9) is connected to the blast furnace inlet hydrogen heat exchanger (10) of the blast furnace body (15); the hydrogen is heated to 800°C to 1200°C through the blast furnace inlet hydrogen heat exchanger (10) and injected into the blast furnace body (15); The anode inlet of the electrolytic cell (6) is an air inlet, which is sequentially connected to an air compressor (1) and an air heat exchanger (3); the air is heated to 800° C. through the air heat exchanger (3) and then enters the electrolytic cell (6); The anode outlet is connected to the stack outlet air heat exchanger (7) and the hot air system through a tee.

2. The ironmaking system coupled with solid oxide electrolysis and blast furnace waste heat utilization according to claim 1, characterized in that: The hot air system includes a hot air furnace (12); The hot blast furnace (12) is connected to the top air outlet of the blast furnace body (15) through a dust collector (13) and a desulfurizer (14). The hot blast furnace (12) uses blast furnace gas as fuel, burns and supplies heat to heat the cold air to 1200°C before entering the blast furnace body (15); a hot blast furnace outlet flue gas heat exchanger (11) is provided at the flue gas outlet of the hot blast furnace (12).

3. The ironmaking system coupled with solid oxide electrolysis and blast furnace waste heat utilization according to claim 1, characterized in that: A slag heat exchanger (16) and a slag treatment device (17) are provided at the slag outlet at the bottom of the blast furnace body (15), and the sensible heat of the slag is recovered by the slag heat exchanger (16).

4. A method for ironmaking by coupling solid oxide electrolysis with blast furnace waste heat utilization, characterized in that: The method is implemented by using an ironmaking system coupling solid oxide electrolysis with blast furnace waste heat utilization as claimed in any one of claims 1 to 3, comprising the following steps: After being pressurized, water and air are passed into a heat exchanger and heated to 800°C. They are then passed into the cathode and anode of the solid oxide electrolysis system respectively. An external power supply is applied to the solid oxide electrolysis system, and the water vapor is electrolyzed into hydrogen and oxygen. The air at the anode outlet of the solid oxide electrolysis system enters the hot air system, reacts with the blast furnace gas to release heat, and heats the cold air to 1200°C and is sent to the blast furnace body (15); The hydrogen at the cathode outlet of the solid oxide electrolysis system is heated to 800°C by a heat exchanger and then enters the blast furnace body (15). The iron ore reacts with the hydrogen and coal powder to produce molten iron, blast furnace gas and slag. The blast furnace gas enters the hot air system from the top air outlet of the blast furnace body (15), and the slag enters the heat exchanger from the slag outlet at the bottom of the blast furnace body (15) for cooling.

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