An integrated system for the cogeneration of electricity, heat and hydrogen and hydrogen metallurgy for absorbing surplus electricity and an operating method thereof

Abstract

The present invention discloses an integrated system for the cogeneration of electricity, heat and hydrogen and hydrogen metallurgy for absorbing surplus electricity and an operation method thereof, wherein the system comprises a solar power generation system, a water electrolysis hydrogen production system, a cascade heating system and a hydrogen-rich metallurgical system; the electricity generated by the solar power generation system is used for water electrolysis hydrogen production; the cascade heating system extracts part of the hot molten salt in the hot molten salt storage tank to heat the hydrogen produced by water electrolysis, the hydrogen is mixed with carbon monoxide to form a reducing gas, which is sent to an electric heater for heating to obtain high-temperature reducing gas, the electricity in the electric heater comes from the surplus electricity in the power grid and the surplus electricity of the solar power generation system; the high-temperature reducing gas is sprayed into the hydrogen-rich metallurgical system, and the iron ore is reduced to molten iron by a reduction melting furnace; when the solar energy fluctuates, the stable and safe operation of the system is maintained by adjusting the inlet and outlet flow difference of the molten salt storage tank, the hydrogen production rate and the hydrogen production temperature; the present invention can absorb the surplus electricity in the power grid, and at the same time significantly reduce the carbon emissions of the metallurgical process, thereby promoting the high-quality coordinated development of renewable energy and high-carbon industries.

Description

Technical Field

[0001] The present invention belongs to the field of renewable energy utilization, and specifically relates to an electric heat and hydrogen cogeneration and hydrogen metallurgy integrated system and an operation method for absorbing surplus electricity. Background Art

[0002] Achieving carbon peak and carbon neutrality are long-term goals set by my country for sustainable development and climate change response. The steel industry is a key sector for carbon emissions. As the world's largest steel producer, China's steel production accounts for over 50% of the global total. Using hydrogen to partially replace carbon monoxide reducing gas in metallurgy is a key technology for my country's steel industry's green and low-carbon transformation. Hydrogen produced by electrolyzing water using electricity generated by renewable energy sources such as solar energy is called "green hydrogen." Using "green hydrogen" in metallurgy can significantly reduce carbon emissions across the entire process, contributing to the early realization of my country's "dual carbon" goals. However, hydrogen metallurgy is a highly endothermic process. To maintain heat during the process, the reducing gas must be heated. Traditionally, this high-temperature reducing gas is produced through the combustion of solid fuels. Therefore, there is an urgent need to develop a "green hydrogen" production and heating technology to significantly reduce carbon emissions in metallurgical processes, promote the large-scale integration of renewable energy, and advance the construction of my country's new power system. Summary of the Invention

[0003] In response to the problems of high carbon emissions in the steel industry and the consumption of surplus electricity in the power grid, the purpose of the present invention is to propose an integrated system and operation method for the cogeneration of electricity, heat and hydrogen and hydrogen metallurgy to consume surplus electricity. The present invention obtains "green hydrogen" through the cogeneration of electricity, heat and hydrogen, which is used in metallurgical processes, thereby reducing carbon emissions in the steel industry. By adjusting the molten salt flow rate, the reducing gas temperature, the proportion of hydrogen in the reducing gas, etc., the integrated system is ensured to operate safely and stably under various lighting conditions.

[0004] The technical solution adopted by the present invention to solve its technical problem is:

[0005] An integrated system for the cogeneration of electricity, heat and hydrogen and hydrogen metallurgy for absorbing surplus electricity, characterized by comprising a solar power generation system, a water electrolysis hydrogen production system, a cascade heating system and a hydrogen-rich metallurgy system;

[0006] The solar power generation system includes a heliostat 2, an absorber 3, a cold molten salt pump 4, a cold molten salt storage tank 5, a hot molten salt storage tank 6, a hot molten salt pump 7, a steam generator 8 and a generator 9; the heliostat 2 reflects the light of the sun 1 into the absorber 3, the cold molten salt outlet of the cold molten salt storage tank 5 is connected to the cold molten salt inlet of the absorber 3 through the cold molten salt pump 4, the hot molten salt outlet of the absorber 3 is connected to the hot molten salt inlet of the hot molten salt storage tank 6, the hot molten salt inlet of the steam generator 8 is connected to the hot molten salt outlet of the hot molten salt storage tank 6 through the hot molten salt pump 7, the cold molten salt outlet of the steam generator 8 is connected to the cold molten salt inlet of the cold molten salt tank 5, the steam generator 8 is connected to the generator 9, and the generator 9 outputs electricity to the outside;

[0007] The electrolysis water hydrogen production system includes an electrolytic cell 11; the electrolytic cell 11 inputs the electricity generated by the generator 9 and outputs hydrogen;

[0008] The cascade heating system includes a hot molten salt diverter valve 10, a molten salt-hydrogen heat exchanger 12 and an electric heater 13; the hot molten salt in the hot molten salt storage tank 6 is fed into the hot molten salt inlet of the molten salt-hydrogen heat exchanger 12 through the hot molten salt pump 7 and the hot molten salt diverter valve 10, the cold molten salt outlet of the molten salt-hydrogen heat exchanger 12 is connected to the cold molten salt storage tank 5, the molten salt-hydrogen heat exchanger 12 is connected to the hydrogen outlet of the electrolyzer 11, and the high-temperature hydrogen outlet of the molten salt-hydrogen heat exchanger 12 is connected to the electric heater 13. A reducing gas mixed with carbon monoxide and hydrogen needs to be fed into the electric heater 13 to output high-temperature reducing gas;

[0009] The hydrogen-rich metallurgical system includes a reduction melting furnace 14 ; high-temperature reducing gas from the outlet of the electric heater 13 is fed into the reduction melting furnace 14 to reduce iron ore and generate molten iron, thereby completing the hydrogen-rich metallurgical process.

[0010] Furthermore, the solar power generation system adopts tower solar thermal power generation technology, and the temperatures of cold and hot molten salts are 290°C and 565°C respectively. When solar energy fluctuates, the power of the cold molten salt pump 4 is adjusted to change the flow rate of the cold molten salt to maintain the temperature of the hot molten salt at the outlet of the absorber 3.

[0011] The power generation of the generator 9 is regulated by adjusting the heat exchange amount of the steam generator 8 by changing the power of the molten salt pump 7 .

[0012] The hot molten salt flow rate at the outlet of the hot molten salt tank 6 is equal to the sum of the molten salt flow rates entering the steam generator 8 and the molten salt-hydrogen heat exchanger 12 .

[0013] The steam generator 8 and the molten salt-hydrogen heat exchanger 12 are both partition-type heat exchangers.

[0014] The hydrogen production technologies that can be selected in the electrolytic cell 11 include: alkaline water electrolysis, proton exchange membrane electrolysis, and high-temperature solid oxide electrolysis.

[0015] When the hydrogen production technology selected in the electrolytic cell 11 is high-temperature solid oxide electrolysis, the hot molten salt diverter valve 10 is closed, the molten salt-hydrogen heat exchanger 12 stops operating, and the reducing gas obtained by mixing hydrogen and carbon monoxide produced by the electrolytic cell 11 is sent to the electric heater 13.

[0016] The driving power of the electric heater 13 can be selected from: surplus power in the power grid and surplus power in the solar power generation system.

[0017] The temperature range of the high-temperature reducing gas at the outlet of the electric heater 13 is 900° C. to 1000° C., and the volume ratio of hydrogen to the reducing gas is 40% to 78%.

[0018] An operating method for an integrated system of electric heat and hydrogen cogeneration and hydrogen metallurgy for absorbing surplus electricity is as follows:

[0019] 1) When the system is operating under design conditions, the inlet and outlet molten salt flows of the molten salt storage tank 6 are the same, the driving power of the electric heater 13 is entirely derived from the surplus power in the power grid, the high-temperature reducing gas entering the reduction melting furnace 14 is at a temperature of 950° C., and the proportion of hydrogen in the reducing gas is 60%;

[0020] 2) When there is sufficient sunlight and the surplus power in the power grid is sufficient to drive the electric heater 13 to maintain the temperature of the reducing gas at 950°C, the flow rate of the molten salt out of the molten salt tank 6 is maintained, and the flow rate of the molten salt into the molten salt tank 6 is increased. When the molten salt storage tank has no capacity margin, the flow rate of the molten salt out of the molten salt tank 6 is increased, the power generation of the generator 9 is increased, the hydrogen production rate of the electrolyzer 11 is increased, and the amount of carbon monoxide fed into the electric heater 13 is reduced;

[0021] 3) When the sunlight is insufficient and the surplus power in the power grid is sufficient to drive the electric heater 13 to maintain the temperature of the reducing gas at 950°C, the flow rate of hot molten salt flowing out of the hot molten salt tank 6 is increased, and the flow rate of cold molten salt flowing out of the cold molten salt tank 4 is reduced. When there is no hot molten salt available in the hot molten salt storage tank, the hydrogen production rate of the electrolytic water tank 11 is reduced, and the amount of carbon monoxide fed to the electric heater 13 is increased;

[0022] 4) When there is sufficient sunlight and the surplus power in the power grid is insufficient to drive the electric heater 13 to maintain the temperature of the reducing gas at 950°C, the flow of hot molten salt entering the steam generator 8 is increased, the power generation of the generator 9 is increased, and part of the power generated by the generator 9 is fed into the electric heater 13 to maintain the reducing gas temperature at 950°C;

[0023] 5) When the sunlight is insufficient and the surplus power in the power grid is insufficient to drive the electric heater 13 to maintain the temperature of the reducing gas at 950°C, the hydrogen production rate of the electrolytic water tank 11 is reduced, the temperature of the reducing gas at the outlet of the electric heater 13 is reduced, and the amount of carbon monoxide fed into the electric heater 13 is increased.

[0024] Compared with the prior art, the advantages of the present invention are as follows:

[0025] (1) The carbon emissions in the metallurgical process are reduced by using molten salt and surplus electricity cascade heating, thereby improving energy efficiency.

[0026] (2) Through the comprehensive control of parameters such as the molten salt flow rate at the inlet and outlet of the molten salt storage tank, hydrogen production rate, reducing gas temperature, and the proportion of hydrogen in reducing gas, the integrated system's adaptability to solar energy fluctuations is enhanced, the overall performance and operating efficiency of the system are improved, and a strong guarantee is provided for safe and stable operation under various light intensities. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the system of the present invention. Specific implementation methods

[0028] The present invention will be further described below with reference to the accompanying drawings and examples.

[0029] The present invention provides an integrated system and operation method for the cogeneration of electricity, heat and hydrogen and hydrogen metallurgy to absorb surplus electricity. The specific implementation method is as follows:

[0030] like Figure 1 As shown, an integrated system of electric thermal hydrogen cogeneration and hydrogen metallurgy for absorbing surplus electricity includes a solar power generation system, a water electrolysis hydrogen production system, a cascade heating system and a hydrogen-rich metallurgy system;

[0031] The solar power generation system includes a heliostat 2, an absorber 3, a cold molten salt pump 4, a cold molten salt storage tank 5, a hot molten salt storage tank 6, a hot molten salt pump 7, a steam generator 8 and a generator 9; the heliostat 2 reflects the light of the sun 1 into the absorber 3, the cold molten salt outlet of the cold molten salt storage tank 5 is connected to the cold molten salt inlet of the absorber 3 through the cold molten salt pump 4, the hot molten salt outlet of the absorber 3 is connected to the hot molten salt inlet of the hot molten salt storage tank 6, the hot molten salt inlet of the steam generator 8 is connected to the hot molten salt outlet of the hot molten salt storage tank 6 through the hot molten salt pump 7, the cold molten salt outlet of the steam generator 8 is connected to the cold molten salt inlet of the cold molten salt tank 5, the steam generator 8 is connected to the generator 9, and the generator 9 outputs electricity to the outside;

[0032] The electrolysis water hydrogen production system includes an electrolytic cell 11; the electrolytic cell 11 inputs the electricity generated by the generator 9 and outputs hydrogen;

[0033] The cascade heating system includes a hot molten salt diverter valve 10, a molten salt-hydrogen heat exchanger 12 and an electric heater 13; the hot molten salt in the hot molten salt storage tank 6 is fed into the hot molten salt inlet of the molten salt-hydrogen heat exchanger 12 through the hot molten salt pump 7 and the hot molten salt diverter valve 10, the cold molten salt outlet of the molten salt-hydrogen heat exchanger 12 is connected to the cold molten salt storage tank 5, the molten salt-hydrogen heat exchanger 12 is connected to the hydrogen outlet of the electrolyzer 11, and the high-temperature hydrogen outlet of the molten salt-hydrogen heat exchanger 12 is connected to the electric heater 13. A reducing gas mixed with carbon monoxide and hydrogen needs to be fed into the electric heater 13 to output high-temperature reducing gas;

[0034] The hydrogen-rich metallurgical system includes a reduction melting furnace 14 ; high-temperature reducing gas from the outlet of the electric heater 13 is fed into the reduction melting furnace 14 to reduce iron ore and generate molten iron, thereby completing the hydrogen-rich metallurgical process.

[0035] As a preferred embodiment of the present invention, the solar power generation system adopts tower solar thermal power generation technology, and the temperatures of cold and hot molten salts are 290°C and 565°C respectively, converting unstable and fluctuating solar energy into stable thermal energy storage in molten salt. The setting of the molten salt working temperature zone meets the principle of energy-quality-energy-potential matching and has a high energy absorption efficiency; when solar energy fluctuates, the power of the cold molten salt pump 4 is adjusted to change the flow rate of the cold molten salt to maintain the temperature of the hot molten salt at the outlet of the absorber 3, thereby ensuring the temperature stability of the hot molten salt storage tank 6, enhancing the adaptability of the integrated system to solar energy fluctuations, and providing a strong guarantee for the safe and stable operation of the system under various light intensities.

[0036] As a preferred embodiment of the present invention, the power generation of the generator 9 is regulated by adjusting the heat exchange of the steam generator 8 by changing the power of the molten salt pump 7, and then adjusting the power generation of the generator 9. This method is simple, convenient, and easy to implement, avoiding the complexity of the system.

[0037] As a preferred embodiment of the present invention, the hot molten salt flow rate at the outlet of the hot molten salt tank 6 is equal to the sum of the molten salt flow rates entering the steam generator 8 and the molten salt-hydrogen heat exchanger 12 .

[0038] As a preferred embodiment of the present invention, the steam generator 8 and the molten salt-hydrogen heat exchanger 12 are both partition-type heat exchangers, in which the hot working medium and the cold working medium are separated and do not interfere with each other. The heat exchanger has high efficiency and small end difference, which improves the energy utilization efficiency of the system.

[0039] As a preferred embodiment of the present invention, the hydrogen production technology selected in the electrolyzer 10 is alkaline water electrolysis, proton exchange membrane electrolysis or high-temperature solid oxide electrolysis, and hydrogen is produced by electricity generated by renewable energy. The produced hydrogen is "green hydrogen", and the carbon emissions during the hydrogen production process are zero, reducing carbon emissions during system operation.

[0040] As a preferred embodiment of the present invention, the driving power of the electric heater 13 can be selected from: surplus electricity in the power grid, surplus electricity in the solar power generation system, and the surplus electricity is used to heat the reducing gas, thereby improving the power grid's ability to absorb surplus electricity and ensuring the safe and stable operation of the power system.

[0041] As a preferred embodiment of the present invention, the temperature range of the high-temperature reducing gas at the outlet of the electric heater 13 is 900°C to 1000°C, which not only provides sufficient heat for the reducing gas to reduce the iron ore, so that the metallization rate of the iron ore is as high as 90% or more, but also avoids energy waste and improves the overall performance and operating efficiency of the system; the proportion of hydrogen in the reducing gas is 40% to 78%, which not only reduces the carbon emissions of the metallurgical process, but also reduces the energy consumption of the metallurgical process, and improves the economy and environmental friendliness of the system operation.

[0042] like Figure 1 As shown, a method for operating an integrated system of electric heat and hydrogen cogeneration and hydrogen metallurgy for absorbing surplus electricity is characterized by:

[0043] 1) When the cogeneration system is operating at the designed operating conditions, the inlet and outlet molten salt flows of the molten salt storage tank 6 are the same, the driving power of the electric heater 13 is entirely derived from the surplus power in the power grid, the high-temperature reducing gas entering the reduction melting furnace 14 is at a temperature of 950° C., and the proportion of hydrogen in the reducing gas is 60%;

[0044] 2) When there is sufficient sunlight and the surplus power in the power grid is sufficient to drive the electric heater 13 to maintain the temperature of the reducing gas at 950°C, the flow rate of the molten salt out of the molten salt tank 6 is maintained, and the flow rate of the molten salt into the molten salt tank 6 is increased. When the molten salt storage tank has no capacity margin, the flow rate of the molten salt out of the molten salt tank 6 is increased, the power generation of the generator 9 is increased, the hydrogen production rate of the electrolyzer 11 is increased, and the amount of carbon monoxide fed into the electric heater 13 is reduced;

[0045] 3) When the sunlight is insufficient and the surplus power in the power grid is sufficient to drive the electric heater 13 to maintain the temperature of the reducing gas at 950°C, the flow rate of hot molten salt flowing out of the hot molten salt tank 6 is increased, and the flow rate of cold molten salt flowing out of the cold molten salt tank 4 is reduced. When there is no hot molten salt available in the hot molten salt storage tank, the hydrogen production rate of the electrolytic water tank 11 is reduced, and the amount of carbon monoxide fed to the electric heater 13 is increased;

[0046] 4) When there is sufficient sunlight and the surplus power in the power grid is insufficient to drive the electric heater 13 to maintain the temperature of the reducing gas at 950°C, the flow of hot molten salt entering the steam generator 8 is increased, the power generation of the generator 9 is increased, and part of the power generated by the generator 9 is fed into the electric heater 13 to maintain the reducing gas temperature at 950°C;

[0047] 5) When the sunlight is insufficient and the surplus power in the power grid is insufficient to drive the electric heater 13 to maintain the temperature of the reducing gas at 950°C, the hydrogen production rate of the electrolytic water tank 11 is reduced, the temperature of the reducing gas at the outlet of the electric heater 13 is reduced, and the amount of carbon monoxide fed into the electric heater 13 is increased.

[0048] The present invention discloses an integrated system and operation method for cogeneration of electric heat and hydrogen and hydrogen metallurgy for absorbing surplus electricity. The electricity generated by the solar power generation system is used for electrolysis of water to produce hydrogen. The cascade heating system extracts part of the molten salt in the molten salt storage tank to heat the hydrogen produced by electrolysis of water. The hydrogen is mixed with carbon monoxide to form a reducing gas, which is sent to an electric heater for heating to obtain high-temperature reducing gas. The electricity in the electric heater comes from the surplus electricity in the power grid and the surplus electricity of the solar power generation system. The high-temperature reducing gas is sprayed into the hydrogen-rich metallurgical system to generate molten iron through a reduction melting furnace. When the solar energy fluctuates, the system is maintained in stable and safe operation by adjusting the inlet and outlet flow difference of the molten salt storage tank, the hydrogen production rate, and the hydrogen production temperature. The present invention greatly reduces carbon emissions in the metallurgical process through green hydrogen-rich metallurgy, cascade heating substitution and other methods, realizes electricity / heat / hydrogen cogeneration, and can absorb surplus electricity in the power grid, promote the high proportion of renewable energy connected to the grid, and promote the construction of my country's new power system.

Claims

1. A method for operating an integrated system for the cogeneration of electricity, heat and hydrogen and hydrogen metallurgy to absorb surplus electricity, the system comprising a solar power generation system, a water electrolysis hydrogen production system, a cascade heating system and a hydrogen-rich metallurgy system; The solar power generation system comprises a heliostat (2), a heat absorber (3), a cold molten salt pump (4), a cold molten salt storage tank (5), a hot molten salt storage tank (6), a hot molten salt pump (7), a steam generator (8) and a generator (9); the heliostat (2) reflects light from the sun (1) to the heat absorber (3); the cold molten salt outlet of the cold molten salt storage tank (5) is connected to the cold molten salt inlet of the heat absorber (3) via the cold molten salt pump (4); the hot molten salt outlet of the heat absorber (3) is connected to the hot molten salt inlet of the hot molten salt storage tank (6); the hot molten salt inlet of the steam generator (8) is connected to the hot molten salt outlet of the hot molten salt storage tank (6) via the hot molten salt pump (7); the cold molten salt outlet of the steam generator (8) is connected to the cold molten salt inlet of the cold molten salt storage tank (5); the steam generator (8) is connected to the generator (9); and the generator (9) outputs electricity to the outside; The water electrolysis hydrogen production system comprises an electrolytic cell (11); the electrolytic cell (11) inputs the electricity generated by the generator (9) and outputs hydrogen; The cascade heating system comprises a hot molten salt diverter valve (10), a molten salt-hydrogen heat exchanger (12) and an electric heater (13); the hot molten salt in the hot molten salt storage tank (6) is fed into the hot molten salt inlet of the molten salt-hydrogen heat exchanger (12) through a hot molten salt pump (7) and a hot molten salt diverter valve (10); the cold molten salt outlet of the molten salt-hydrogen heat exchanger (12) is connected to the cold molten salt storage tank (5); the molten salt-hydrogen heat exchanger (12) is connected to the hydrogen outlet of the electrolyzer (11); the high-temperature hydrogen outlet of the molten salt-hydrogen heat exchanger (12) is connected to the electric heater (13); a reducing gas mixed with carbon monoxide and hydrogen needs to be fed into the electric heater (13) to output high-temperature reducing gas; The hydrogen-rich metallurgical system includes a reduction melting furnace (14); high-temperature reducing gas from the outlet of the electric heater (13) is fed into the reduction melting furnace (14) to reduce iron ore and generate molten iron, thereby completing the hydrogen-rich metallurgical process; Its characteristics are: The operation method is as follows: 1) When the system is operating under design conditions, the inlet and outlet molten salt flows of the molten salt storage tank (6) are the same, the driving power of the electric heater (13) is entirely derived from the surplus power in the power grid, the temperature of the high-temperature reducing gas entering the reduction melting furnace (14) is 950°C, and the proportion of hydrogen in the reducing gas is 60%; 2) When there is sufficient sunlight and the surplus power in the power grid is sufficient to drive the electric heater (13) to maintain the temperature of the reducing gas at 950° C., the flow rate of the molten salt flowing out of the molten salt storage tank (6) is maintained, and the flow rate of the molten salt flowing into the molten salt storage tank (6) is increased. When the molten salt storage tank has no capacity margin, the flow rate of the molten salt flowing out of the molten salt storage tank (6) is increased, the power generation of the generator (9) is increased, the hydrogen production rate of the electrolyzer (11) is increased, and the amount of carbon monoxide fed into the electric heater (13) is reduced; 3) When the sunlight is insufficient and the surplus power in the power grid is sufficient to drive the electric heater (13) to maintain the temperature of the reducing gas at 950°C, the flow rate of the hot molten salt flowing out of the hot molten salt storage tank (6) is increased, and the flow rate of the cold molten salt flowing out of the cold molten salt storage tank (5) is reduced. When there is no hot molten salt available in the hot molten salt storage tank, the hydrogen production rate of the electrolytic water tank (11) is reduced, and the amount of carbon monoxide fed to the electric heater (13) is increased; 4) When there is sufficient sunlight and the surplus power in the power grid is insufficient to drive the electric heater (13) to maintain the temperature of the reducing gas at 950°C, the flow rate of the hot molten salt entering the steam generator (8) is increased, the power generation of the generator (9) is increased, and part of the power output of the generator (9) is sent to the electric heater (13) to maintain the reducing gas at 950°C; 5) When the sunlight is insufficient and the surplus power in the power grid is insufficient to drive the electric heater (13) to maintain the temperature of the reducing gas at 950°C, the hydrogen production rate of the electrolytic water tank (11) is reduced, the temperature of the reducing gas at the outlet of the electric heater (13) is reduced, and the amount of carbon monoxide fed into the electric heater (13) is increased.

2. The method for operating an integrated system for electricity, heat, hydrogen and hydrogen metallurgy for absorbing surplus electricity according to claim 1, characterized in that: The solar power generation system adopts tower solar thermal power generation technology. The temperatures of cold and hot molten salts are 290°C and 565°C respectively. When solar energy fluctuates, the power of the cold molten salt pump (4) is adjusted to change the flow rate of the cold molten salt to maintain the temperature of the hot molten salt at the outlet of the heat absorber (3).

3. The method for operating an integrated system for electricity, heat, hydrogen and hydrogen metallurgy for absorbing surplus electricity according to claim 1, characterized in that: The power generation of the generator (9) is regulated by adjusting the heat exchange capacity of the steam generator (8) by changing the power of the molten salt pump (7).

4. The method for operating an integrated system for electricity, heat, hydrogen and hydrogen metallurgy for absorbing surplus electricity according to claim 1, characterized in that: The hot molten salt flow rate at the outlet of the hot molten salt storage tank (6) is equal to the sum of the molten salt flow rates entering the steam generator (8) and the molten salt-hydrogen heat exchanger (12).

5. The method for operating an integrated system for electricity, heat, hydrogen and hydrogen metallurgy for absorbing surplus electricity according to claim 1, characterized in that: The steam generator (8) and the molten salt-hydrogen heat exchanger (12) are both partition-type heat exchangers.

6. The method for operating an integrated system for electricity, heat, hydrogen and hydrogen metallurgy for absorbing surplus electricity according to claim 1, characterized in that: The hydrogen production technology selected in the electrolytic cell (11) is alkaline water electrolysis, proton exchange membrane electrolysis or high-temperature solid oxide electrolysis.

7. The method for operating an integrated system for electricity, heat, hydrogen and hydrogen metallurgy for absorbing surplus electricity according to claim 1, characterized in that: When the hydrogen production technology selected in the electrolytic cell (11) is high-temperature solid oxide electrolysis, the hot molten salt diverter valve (10) is closed, the molten salt-hydrogen heat exchanger (12) stops operating, and the reducing gas obtained by mixing hydrogen and carbon monoxide produced in the electrolytic cell (11) is sent to the electric heater (13).

8. The method for operating an integrated system for electricity, heat, hydrogen and hydrogen metallurgy for absorbing surplus electricity according to claim 1, characterized in that: The driving power of the electric heater (13) is selected from the surplus power in the power grid or the surplus power in the solar power generation system.

9. The method for operating an integrated system for absorbing surplus electricity, comprising: The temperature range of the high-temperature reducing gas at the outlet of the electric heater (13) is 900° C. to 1000° C., and the volume ratio of hydrogen to the reducing gas is 40% to 78%.

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