Systematic carbon emissions reduction method for whole process of steel production and casting

Abstract

Disclosed in the present invention is a systematic carbon emissions reduction method for a whole process of steel production and casting, comprising the steps of: hydrogen injection in a blast furnace. Hydrogen comes from a nuclear hydrogen production system, hydrogen production based on water electrolysis, and hydrogen production based on coke oven gas-steam reforming; electric energy consumed by hydrogen production based on water electrolysis comes from gas power generation, steam residual pressure power generation, solar power generation, wind energy power generation, and nuclear power generation; combustible gas used for gas power generation is coke oven gas, blast furnace gas, and converter gas; steam in steam residual pressure power generation comes from a sintering waste heat boiler; steam in hydrogen production based on coke oven gas-steam reforming is low-pressure steam after residual pressure power generation; the final product is a cast steel profile, a casting material of a high-carbon spheroidal graphite cast iron profile having a carbon content of 2-4% and a silicon content of 2-4%, and a casting material of a high-carbon spheroidal graphite cast steel profile having a carbon content of 1-2% and a silicon content of 1-1.9%; the waste of the final product enters a converter or an electric furnace for cyclic smelting.

Description

A systematic carbon reduction method for the entire steel and casting process Technical Field

[0001] The present invention relates to iron and steel metallurgy, and in particular to a method for systematically reducing carbon emissions throughout the entire steel and casting process. Background Art

[0002] To address global climate change, reducing CO2 greenhouse gas emissions and promoting low-carbon production have become key priorities. The energy-intensive steel industry is the largest contributor to carbon emissions among the 31 manufacturing sectors. In 2022, my country's crude steel output reached 1.013 billion tons, ranking first in the world, and CO2 emissions reached 2.1 billion tons, accounting for approximately 15-17% of China's total carbon emissions. The blast furnace-converter process, based on carbon metallurgy and ore, accounts for approximately 90% of steel production. Blast furnace ironmaking is the largest CO2-emitting process, contributing approximately 70%-90% of total CO2 emissions from steel production. Using hydrogen to replace carbon as a reducing agent and fuel in the ironmaking process, where hydrogen reacts with water as a product, can further significantly reduce CO2 emissions and fundamentally achieve low-carbon blast furnace production. The use of green hydrogen in hydrogen-rich, low-carbon blast furnace production has become a hot topic in the research and development of transformative technologies for steelmaking. At the same time, building and optimizing new systems is also necessary to further achieve the comprehensive and effective utilization of waste heat and waste energy throughout the traditional blast furnace-converter long process, minimizing process energy consumption and further reducing energy consumption and carbon emissions. Furthermore, the hydrogen currently used in factories primarily comes from byproducts obtained from the separation of coke oven gas, and obtaining hydrogen through water electrolysis requires a large amount of electricity. Therefore, it is necessary to introduce stable green energy sources into the non-carbon steelmaking process to produce sufficient hydrogen in order to truly achieve the goal of reducing carbon emissions throughout the entire process. At the same time, existing approaches to carbon reduction primarily focus on the source and process of steel production, while ignoring the carbon sequestration effect of the end products.

[0003] Summary of the Invention

[0004] To solve the above problems, the present invention provides a systematic carbon reduction method for the entire process of steel and casting, comprising the steps of: injecting hydrogen into a blast furnace;

[0005] Hydrogen comes from nuclear energy hydrogen production system, water electrolysis hydrogen production system, coke oven gas-steam reforming hydrogen production system; among them,

[0006] The nuclear energy hydrogen production system includes a nuclear energy power generation subsystem, a hydrogen production thermal cycle subsystem, and a hydrogen-rich blast furnace-converter subsystem. The nuclear energy power generation subsystem generates electricity through a high-temperature helium Brayton / Rankine cycle and outputs water vapor to the hydrogen production thermal cycle subsystem. The nuclear energy hydrogen production heating cycle system undergoes a thermochemical reaction to produce hydrogen and oxygen. The hydrogen is heated in the nuclear energy heating cycle system, and the oxygen releases heat in the nuclear energy heating cycle system. After achieving thermal energy conversion, the high-temperature hydrogen and low-temperature oxygen are input into the hydrogen-rich blast furnace-converter subsystem.

[0007] The electricity consumed by water electrolysis for hydrogen production comes from gas-fired power generation, steam waste pressure power generation, solar power generation, wind power generation, and off-peak power from the grid. The combustible gases used in gas-fired power generation are coke oven gas, blast furnace gas, and converter gas. The steam used in steam waste pressure power generation comes from sintering waste heat boilers.

[0008] The water vapor from coke oven gas-steam reforming to produce hydrogen is low-pressure water vapor after residual pressure power generation;

[0009] The end products are cast steel profiles, casting materials for high-carbon ductile iron profiles with a carbon content of 2-4% and a silicon content of 2-4%, and casting materials for high-carbon ductile steel profiles with a carbon content of 1-2% and a silicon content of 1-1.9%;

[0010] The waste from the end products enters the converter or electric furnace for recycling smelting.

[0011] Furthermore, the nuclear power generation subsystem includes a nuclear reactor, a first steam turbine, a first generator, a steam generator, a first compressor, a second steam turbine, a second generator, a condenser, a condensate pump, a low-pressure heater, a deaerator, a feedwater pump, and a high-pressure heater;

[0012] High-temperature helium is output from the nuclear reactor to the first steam turbine and the hydrogen production thermal cycle subsystem. The high-temperature helium expands in the first steam turbine, generating work to drive the first generator to generate electricity. The first steam turbine then outputs low-pressure helium to the steam generator. The steam generator converts the heat energy of the low-pressure helium into industrial water through a Rankine cycle, which is then sent to the second steam turbine. The low-pressure, low-temperature helium is then compressed by the first compressor and re-entered as reactor coolant into the nuclear reactor cycle.

[0013] Part of the water vapor is introduced into the hydrogen production thermal cycle subsystem by the second steam turbine; the water vapor expands in the second steam turbine to drive the second generator to generate electricity, and then enters the condenser. The electricity generated by the second generator is input into the hydrogen production thermal cycle subsystem. The condensate output by the condenser passes through the condensate pump and is combined with the industrial wastewater provided by the hydrogen-rich blast furnace-converter subsystem. It passes through the low-pressure heater, deaerator, feed water pump, and high-pressure heater in sequence and enters the steam generator tube side to remove oxygen and other gases in the water, and then serves as part of the feed water for the steam Rankine cycle.

[0014] Furthermore, the hydrogen production thermal cycle subsystem includes a first pressure reducing valve, a second pressure reducing valve, an iodine-sulfur cycle hydrogen and oxygen production device, a gas mixing chamber, a high-temperature low-pressure heater, and a temperature control system;

[0015] The nuclear reactor outputs high-temperature helium to the second pressure reducing valve, and together with part of the water vapor drawn from the second steam turbine to the second pressure reducing valve, the helium is reduced to the working pressure of the iodine-sulfur cycle hydrogen and oxygen production unit. The output high-temperature helium and high-temperature water vapor together provide heat energy for the iodine-sulfur cycle hydrogen and oxygen production unit. The high-temperature water vapor supplements the water vapor required for the thermochemical reaction of the iodine-sulfur cycle hydrogen and oxygen production unit. The iodine-sulfur cycle hydrogen and oxygen production unit undergoes a thermochemical reaction to produce high-temperature hydrogen and oxygen. The produced high-temperature hydrogen enters the gas mixing chamber and combines with the coke oven gas and carbon monoxide produced by the hydrogen-enriched blast furnace-converter subsystem to form a high-temperature reducing atmosphere. The high-temperature helium, whose pressure and temperature are stabilized by the second pressure reducing valve and the temperature control system, exchanges heat energy in the high-temperature low-pressure heater and then enters the hydrogen-enriched blast furnace-converter subsystem. The high-temperature oxygen releases heat through the low-pressure heater and the high-pressure heater to achieve heat energy conversion before being input into the hydrogen-enriched blast furnace-converter subsystem.

[0016] Furthermore, the hydrogen-rich blast furnace-converter subsystem includes a hydrogen-rich blast furnace, a converter, a slag waste heat recovery device, a third generator, and a top gas purification device; the top gas purification device includes a desulfurization tower, a capture tower, a regeneration tower, a dust collector, a top gas dechlorination and desulfurization wastewater treatment device, a second compressor, and a carbon dioxide storage tank;

[0017] The high-temperature reducing atmosphere generated undergoes a reduction reaction in the hydrogen-rich blast furnace, producing molten iron that enters the converter. Low-temperature oxygen enters the hydrogen-rich blast furnace and undergoes an oxidation reaction with the converter to produce product steel. At the same time, the slag waste heat is utilized to pass through the slag waste heat recovery device and adopt the Carona cycle power generation system to achieve heat and electrical energy conversion, so that the third generator generates electricity and does work for the furnace top gas purification device and the furnace top gas dechlorination and desulfurization wastewater treatment device;

[0018] The top gas discharged from the hydrogen-rich blast furnace passes through the dust collector and then enters the top gas purification device, and then enters the desulfurization tower, capture tower, and regeneration tower in sequence, and then the remaining gas components are discharged into the air;

[0019] The top gas is input into the desulfurization tower of the top gas purification device, and the blast furnace gas washing wastewater output enters the condensate pump circulation to provide the industrial water required by the iodine-sulfur cycle hydrogen and oxygen production device;

[0020] The capture tower captures carbon monoxide and inputs it into the gas mixing chamber to circulate and supplement the reducing atmosphere;

[0021] The regeneration tower extracts carbon dioxide and inputs it into the second compressor and the carbon dioxide storage tank.

[0022] Furthermore, the CO2 generated by the combustion of coke oven gas, blast furnace gas and converter gas in gas-fired power generation is captured and stored through carbon capture technology.

[0023] Furthermore, the electricity generated by gas-fired power generation, steam waste pressure power generation, solar power generation, wind power generation, and nuclear power generation is incorporated into the steel plant's internal power grid and transmitted to the water electrolysis hydrogen production equipment.

[0024] Furthermore, the steam generated by the sintering waste heat boiler is transported to the waste pressure power generation device by being incorporated into the high-pressure steam pipeline.

[0025] Furthermore, the low-pressure steam after the excess pressure power generation is transported to the coke oven gas-steam reforming hydrogen production reactor through a low-pressure steam pipeline.

[0026] This invention replaces fossil fuels by injecting hydrogen into blast furnaces, thereby reducing carbon entering the steel production process at the source. This approach reduces carbon emissions by approximately 20% per unit by replacing carbon with hydrogen. Furthermore, high-carbon cast iron and ductile iron profiles replace traditional construction and machinery steel, locking the carbon entering the steel production process into the final product. This high-carbon final product will be recycled as scrap iron and steel in electric furnaces and converters, rather than being emitted as carbon dioxide, achieving a final carbon sequestration rate of over 25%. The present invention also introduces a nuclear energy hydrogen production system around the main line of the above process. Through nuclear energy hydrogen production, the carbon footprint is completely eliminated from the source, and the waste heat and by-products of the entire steel production process are comprehensively utilized. The sintering waste heat is used to produce water vapor, and the water vapor is used for reforming hydrogen production and residual pressure power generation. The water vapor after residual pressure power generation can also be used for reforming hydrogen production with coke oven gas, etc., thereby systematically integrating and maximizing the utilization of various resources in the steel production process, thereby achieving systematic carbon reduction in the entire process from source to end of the steel and casting process.

[0027] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG1 is a process flow chart of a method for systematically reducing carbon emissions in the entire steel and casting process according to the present invention;

[0029] FIG2 is a process flow chart of the nuclear energy hydrogen production system in the method of the present invention. DETAILED DESCRIPTION

[0030] The following describes several preferred embodiments of the present invention with reference to the accompanying drawings to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.

[0031] As shown in Figure 1, a systematic carbon reduction method for the entire process of steel and casting according to the present invention mainly includes two parts: source carbon reduction and end carbon fixation. Source carbon reduction refers to the process of injecting hydrogen into the blast furnace during the blast furnace ironmaking process, using hydrogen to replace carbon as a reducing agent and fuel in the ironmaking process to the maximum extent, thereby reducing the carbon element entering the steel smelting from the source, while end carbon fixation refers to the use of electric furnace steelmaking, with high-carbon cast iron profiles (carbon content 2-4%) and ductile iron profiles (silicon content 1-1.9%, carbon content 1-2%) as the end products to replace traditional commonly used construction steel (carbon content of about 0.2%), and fix more carbon elements in the end products, that is, achieving the purpose of low-carbon steel production through end carbon fixation.

[0032] Continuing with Figure 1, it can be seen that in the method of the present invention, the hydrogen used for blast furnace hydrogen injection primarily comes from two sources: water electrolysis and coke oven gas steam reforming. The electricity consumed by water electrolysis can come from nuclear power generation, gas-fired power generation, steam residual pressure power generation, and off-peak power from the grid. The combustible gases used in gas-fired power generation are coke oven gas (COG) produced during the coking process in steel mills, blast furnace gas (BFG) produced during blast furnace ironmaking, and converter gas (BOF) produced during converter steelmaking. The combustible components of coke oven gas are hydrogen (55%-60%) and methane (23%-27%), along with a small amount of carbon monoxide (5%-8%). The combustible components of blast furnace gas are carbon monoxide, accounting for approximately 25%; and the combustible components of converter gas are carbon monoxide, accounting for 60%-80%. The CO2 generated by the combustion of coke oven gas, blast furnace gas, and converter gas can be captured and stored using carbon capture technology. Steam waste pressure power generation uses a back-pressure unit to convert heat into electricity by exploiting steam pressure differences. Steam for waste pressure power generation is recovered from the high-temperature flue gas in the sintering process through a waste heat boiler and transported via a high-pressure steam pipeline to a waste pressure power generation unit, where it generates electricity. Coke oven gas-steam reforming hydrogen production involves reforming coke oven gas with steam to produce hydrogen and carbon monoxide. The carbon monoxide is then converted and separated to produce hydrogen. Coke oven gas is a byproduct of the coking process in steel mills, while steam can come directly from waste heat boilers or from low-pressure steam generated after waste pressure power generation. The low-pressure steam is transported via a low-pressure steam pipeline to the coke oven gas-steam reforming hydrogen production reactor. Hydrogen production based on water electrolysis and coke oven gas-steam reforming, combined with hydrogen injection into blast furnaces, can reduce carbon emissions per ton of product by 25% at the source.

[0033] In the actual production process, due to the huge amount of hydrogen injection required, obtaining hydrogen through water electrolysis consumes a large amount of electricity. If the electricity for hydrogen production by water electrolysis still comes from coal-fired power generation, it is impossible to truly achieve green metallurgy.

[0034] Therefore, in a further embodiment of the present invention, a nuclear energy hydrogen production system is provided, comprising a nuclear energy power generation subsystem, a hydrogen production thermal cycle subsystem, and a hydrogen-rich blast furnace-converter subsystem; wherein the nuclear energy power generation subsystem generates electricity through a high-temperature helium Brayton / Rankine cycle and outputs water vapor to the hydrogen production thermal cycle subsystem, the nuclear energy hydrogen production heating cycle system undergoes a thermochemical reaction to produce hydrogen and oxygen, the hydrogen is heated in the nuclear energy heating cycle system using thermal energy and electrical energy, the oxygen releases waste heat in the nuclear energy heating cycle system, and the high-temperature hydrogen and low-temperature oxygen are input into the hydrogen-rich blast furnace-converter subsystem as a reducing oxidizing atmosphere after thermal energy conversion.

[0035] As shown in Figure 2, the nuclear power generation subsystem includes a nuclear reactor 1, a first steam turbine 2, a first generator 3, a steam generator 4, a first compressor 5, a second steam turbine 7, a second generator 8, a condenser 9, a condensate pump 10, a low-pressure heater 11, a deaerator 12, a feedwater pump 13, and a high-pressure heater 14.

[0036] The hydrogen production thermal cycle subsystem includes a first pressure reducing valve 6 , a second pressure reducing valve 15 , an iodine-sulfur cycle hydrogen and oxygen production device 16 , a gas mixing chamber 17 , a high-temperature low-pressure heater 18 , and a temperature control system 19 .

[0037] The nuclear reactor 1 outputs high-temperature helium with a temperature of 900-1000°C and a pressure of 7-8 MPa. The high-temperature helium pipeline material is made of 310S austenitic stainless steel containing Al, and is input into the first turbine 2 of the nuclear power generation subsystem and the second pressure reducing valve 15 of the hydrogen production thermal cycle subsystem respectively.

[0038] Part of the high-temperature helium introduced into the nuclear power generation subsystem expands in the first steam turbine 2 to generate work, driving the first generator 3 to generate electricity. The first steam turbine 2 outputs low-pressure helium to the steam generator 4. The low-pressure helium output by the first steam turbine 2 is mixed with the low-pressure helium circulated by the hydrogen production thermal cycle subsystem, and the low-pressure helium has a temperature of 600-700°C. The low-pressure helium converts heat energy in the steam generator 4 to industrial water through a Rankine cycle, and is sent to the second steam turbine 7. The low-pressure helium is discharged at a temperature of 300-400°C to the first compressor 5. The low-pressure and low-temperature helium passes through the first compressor 5, and the compressed helium at a temperature of 350-450°C is input into the nuclear reactor 1.

[0039] The industrial water after heat exchange with low-pressure helium is sent to the steam generator 4 to be heated to form water vapor. Part of the water vapor is introduced by the second steam turbine 7 to the first pressure reducing valve 6 of the hydrogen production thermal cycle subsystem for pressure reduction and then sent to the iodine-sulfur cycle hydrogen and oxygen production device 16; the remaining water vapor expands in the second steam turbine 7 to generate work to drive the second generator 8 to generate electricity and then enters the condenser 9. The electric energy generated by the second generator 8 is input into the temperature control system 19 of the hydrogen production thermal cycle subsystem. The condensate output by the condenser 9 passes through the condensate pump 10 and, combined with the industrial wastewater provided by the hydrogen-rich blast furnace-converter subsystem, passes through the low-pressure heater 11, deaerator 12, feed water pump 13, and high-pressure heater 14 in sequence to enter the pipe side of the steam generator 4 as feed water for the Rankine cycle.

[0040] The remaining high-temperature helium outputted from the nuclear reactor 1 is decompressed by the second pressure reducing valve 15. The remaining high-temperature helium, together with the water vapor decompressed by the second pressure reducing valve 6, provides the required heat energy for the iodine-sulfur cycle hydrogen and oxygen production device 16 operating at a temperature of 800-900°C and a pressure of 4-5 MPa. The high-temperature water vapor also serves to replenish the water required for the thermochemical reaction of the iodine-sulfur cycle hydrogen and oxygen production device 16. The iodine-sulfur cycle hydrogen and oxygen production device 16 undergoes a thermochemical reaction to produce high-temperature hydrogen and oxygen, including:

[0041] Bunsen reaction (20-120°C): IS+SO2+2H2O→2HI+H2SO4

[0042] Sulfuric acid decomposition reaction (800-900°C): 2HI→I2+H2

[0043] Hydroiodic acid decomposition reaction (400-500°C):

[0044] Among them, considering the problems of high temperature and acid corrosion, the iodine-sulfur cycle hydrogen and oxygen production device 16 and its pipelines are made of Al-containing 310S austenitic stainless steel; the high-temperature hydrogen generated enters the mixing chamber 17 and forms a high-temperature reducing atmosphere with the coke oven gas and the carbon monoxide generated by the top gas purification device 24 of the hydrogen-rich blast furnace-converter subsystem, and the high-temperature helium of 1000-1100°C after being electrically heated by the second pressure reducing valve 15 and the temperature control system 19 is heated in the GH3536 nickel-based alloy high-temperature low-pressure heater 18. After the energy exchange and temperature rise to 950-1050℃, it enters the hydrogen-rich blast furnace-converter subsystem, and the low-temperature helium after transferring heat energy drops to 750-850℃, and merges with the low-temperature helium with a temperature of 300-500℃ after the heat energy loss through the iodine-sulfur cycle hydrogen and oxygen production device 16, and finally forms helium with a temperature of 600-700℃ and enters the nuclear power generation subsystem for recycling; while the high-temperature oxygen releases heat through the low-pressure heater 11 and the high-pressure heater 14, realizes heat energy conversion, and then is input into the hydrogen-rich blast furnace-converter subsystem for recycling.

[0045] The hydrogen-rich blast furnace-converter subsystem includes a hydrogen-rich blast furnace 20, a converter 21, a slag waste heat recovery device 22, a third generator 23, a top gas purification device 24, a dust collector 25, a top gas dechlorination and desulfurization wastewater treatment device 26, a second compressor 27, and a carbon dioxide storage tank 28.

[0046] The high-temperature reducing atmosphere generated by the hydrogen production thermal cycle subsystem is injected from the lower part of the hydrogen-rich blast furnace 20 or the furnace waist, and the gas pipeline and the furnace airflow distribution device are made of GH3536 nickel-based alloy; the hydrogen-rich blast furnace 20 undergoes a reduction reaction to produce molten iron that enters the converter 21, and low-temperature oxygen enters the hydrogen-rich blast furnace 20 and the converter 21 to undergo an oxidation reaction to produce product steel. At the same time, the slag waste heat is utilized to pass through the slag waste heat recovery device 22, and the Carona cycle power generation system is adopted to realize the conversion of heat energy and electrical energy, so that the third generator 23 generates electricity and does work for the furnace top gas purification device 24 and the furnace top gas dechlorination and desulfurization wastewater treatment device 26.

[0047] The top gas generated by the reduction-oxidation reaction in the hydrogen-rich blast furnace 20 passes through the dust collector 25 and the top gas purification device 24 in sequence, and then the remaining harmless gas components are discharged into the air;

[0048] The top gas input top gas purification device 24 includes a desulfurization tower 241, a capture tower 242, and a regeneration tower 243; the desulfurization tower 241 is connected to the capture tower 242, the dust collector 25, and the top gas dechlorination and desulfurization wastewater treatment device 26; the top gas dechlorination and desulfurization wastewater treatment device 26 is connected to the condensate pump 10; the capture tower 242 is connected to the regeneration tower 243 and the gas mixing chamber 17; and the regeneration tower 243 is connected to the second compressor 27;

[0049] After passing through the dust collector 25, the top gas passes through the desulfurization tower 241 to remove toxic atmospheres such as hydrogen chloride, carbonyl sulfide, and hydrogen sulfide. The resulting top gas washing wastewater is treated by the top gas dechlorination and desulfurization wastewater treatment device 26 and then enters the condensate pump 10 to be circulated as industrial water for the Rankine cycle. The initially purified top gas is further passed through the capture tower 242 to capture carbon monoxide and input into the mixing chamber 17 for circulation adjustment and replenishment of the reducing atmosphere. Finally, the purified top gas is passed through the regeneration tower 243 to extract carbon dioxide. The extracted carbon dioxide is input into the second compressor 27 for compression and storage in the carbon dioxide storage tank 28 for use in other industries. Finally, the finally purified and harmless top gas is discharged.

[0050] This invention replaces fossil fuels by injecting hydrogen into blast furnaces, thereby reducing carbon entering the steel production process at the source. This approach reduces carbon emissions by approximately 20% per unit of consumption. Furthermore, high-carbon cast iron and ductile iron profiles replace traditional construction and machinery steel, locking the carbon entering the steel production process into the final product. This high-carbon final product will be recycled as scrap iron and steel in electric furnaces and converters, rather than being emitted as carbon dioxide. This results in a carbon sequestration rate of over 25% per ton of final product. The present invention also introduces a nuclear energy hydrogen production system around the main line of the above process. Through nuclear energy hydrogen production, the carbon footprint is completely eliminated from the source, and the waste heat and by-products of the entire steel production process are comprehensively utilized. The sintering waste heat is used to produce water vapor, and the water vapor is used for reforming hydrogen production and residual pressure power generation. The water vapor after residual pressure power generation can also be used for reforming hydrogen production with coke oven gas, etc., thereby systematically integrating and maximizing the utilization of various resources in the steel production process, and further proposes the use of nuclear energy as the main green energy for hydrogen production by electrolysis of water, and specifically provides a nuclear energy hydrogen production system, thereby achieving systematic carbon reduction in the entire steel and casting process.

[0051] The preferred embodiments of the present invention have been described in detail above. It should be understood that numerous modifications and variations based on the concepts of the present invention are possible without inventive effort by those skilled in the art. Therefore, any technical solution that can be derived by one skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A systematic carbon reduction method for the entire process of steel and casting, It is characterized in that Includes steps: Hydrogen injection in blast furnaces; hydrogen comes from nuclear energy hydrogen production system, water electrolysis hydrogen production system, coke oven gas-steam reforming hydrogen production system; among them, The nuclear energy hydrogen production system includes a nuclear energy power generation subsystem, a hydrogen production thermal cycle subsystem, and a hydrogen-rich blast furnace-converter subsystem; among which, The nuclear power generation subsystem comprises a nuclear reactor (1), a first steam turbine (2), a first generator (3), a steam generator (4), a first compressor (5), a second steam turbine (7), a second generator (8), a condenser (9), a condensate pump (10), a low-pressure heater (11), a deoxidizer (12), a feed water pump (13), and a high-pressure heater (14); the hydrogen production thermal cycle subsystem comprises a first pressure reducing valve (6), a second pressure reducing valve (15), an iodine-sulfur cycle hydrogen production and oxygen production device (16), a gas mixing chamber (17), a high-temperature low-pressure heater (18), and a temperature control system (19); the hydrogen-rich blast furnace-converter subsystem comprises a hydrogen-rich blast furnace (20), a converter (21), a slag waste heat recovery device (22), a third generator (23), a furnace top gas purification device (24), a dust collector (25), a furnace top gas dechlorination and desulfurization wastewater treatment device (26), a second compressor (27), and a carbon dioxide storage tank (28); wherein, The nuclear reactor (1) outputs high-temperature helium with a temperature of 900-1000°C and a pressure of 7-8 MPa, which is respectively input into the first steam turbine (2) of the nuclear power generation subsystem and the second pressure reducing valve (15) of the hydrogen production thermal cycle subsystem; the high-temperature helium expands in the first steam turbine (2) to drive the first generator (3) to generate electricity, and the electricity is supplied to the water electrolysis hydrogen production system; the low-pressure helium output by the first steam turbine (2) and the low-pressure helium circulated by the hydrogen production thermal cycle subsystem are mixed at a temperature of 600-700°C and are transported to the steam generator (4); the low-pressure helium uses its heat energy in the steam generator (4) to convert industrial water into water vapor through a Rankine cycle and is transported to the second steam turbine (7), and discharges low-temperature low-pressure helium with a temperature of 300-400°C to the first compressor (5), and the low-pressure low-temperature helium is transported to the first compressor (5) through the first compressor. (5), returning the helium gas with a temperature of 350-450°C after compression to the nuclear reactor (1); part of the water vapor generated by the steam generator (4) is transported to the first pressure reducing valve (6) of the hydrogen production thermal cycle subsystem, and then is decompressed and sent to the iodine-sulfur cycle hydrogen production and oxygen production device (16); the remaining water vapor expands in the second steam turbine (7) to drive the second generator (8) to generate electricity, and then enters the condenser (9). The electric energy generated by the second generator (8) is input into the temperature control system (19) of the hydrogen production thermal cycle subsystem. The condensate output by the condenser (9) passes through the condensate pump (10) and is combined with the industrial wastewater provided by the hydrogen-rich blast furnace-converter subsystem, and then passes through the low-pressure heater (11), the deaerator (12), the feed water pump (13), and the high-pressure heater (14) in sequence to enter the tube side of the steam generator (4) as the feed water of the Rankine cycle; The high-temperature helium of the nuclear reactor (1) input to the second pressure reducing valve (15) is decompressed and then input to the iodine-sulfur cycle hydrogen production and oxygen production device (16), and together with the water vapor after the pressure reduction by the first pressure reducing valve (6), provides the required heat energy for the iodine-sulfur cycle hydrogen production and oxygen production device (16) with an operating temperature of 800-900°C and a working pressure of 4-5MPa, wherein the water vapor also serves to supplement the heat of the iodine-sulfur cycle hydrogen production and oxygen production device (16). The role of water required for chemical reaction; the high-temperature hydrogen produced by the iodine-sulfur cycle hydrogen production and oxygen production device (16) enters the gas mixing chamber (17) and mixes with the coke oven gas and the carbon monoxide produced by the top gas purification device (24) of the hydrogen-rich blast furnace-converter subsystem to form a high-temperature reducing atmosphere, enters the high-temperature low-pressure heater (18), and exchanges heat energy with the 1000-1100°C high-temperature helium after being electrically heated by the second pressure reducing valve (15) and the temperature control system (19) in the high-temperature low-pressure heater (18) and the temperature is raised to 950-1050°C, and then enters the hydrogen-rich blast furnace-converter subsystem; and the heat energy is transferred The low-temperature helium is cooled to 750-850°C and then merged with the low-temperature helium of 300-500°C after the heat energy loss in the iodine-sulfur cycle hydrogen and oxygen production device (16), and finally forms helium of 600-700°C, which is circulated into the nuclear power generation subsystem, that is, mixed with the low-pressure helium output by the first steam turbine (2) and then enters the steam generator (4); the high-temperature oxygen generated by the iodine-sulfur cycle hydrogen and oxygen production device (16) releases heat through the high-pressure heater (14) and the low-pressure heater (11), and is then input into the hydrogen-rich blast furnace-converter subsystem after heat energy conversion with the water inlet of the steam generator (4); The high-temperature reducing atmosphere generated by the hydrogen production heat cycle subsystem is sprayed through the lower part of the hydrogen-rich blast furnace (20) or the furnace waist; the hydrogen-rich blast furnace (20) undergoes a reduction reaction to generate molten iron which enters the converter (21); low-temperature oxygen enters the hydrogen-rich blast furnace (20) and the converter (21) undergoes an oxidation reaction to produce product steel; while the slag waste heat passes through the slag waste heat recovery device (22), and the Carona cycle power generation system is used to achieve heat and electric energy conversion, so that the third generator (23) generates electricity to provide work to the furnace top gas purification device (24) and A top gas dechlorination and desulfurization wastewater treatment device (26); the top gas generated by the reduction and oxidation reaction of the hydrogen-rich blast furnace (20) passes through the dust collector (25) and, and then the remaining harmless gas components are discharged into the air; the top gas after the dust collector (25) passes through the desulfurization tower (241) of the top gas purification device (24), and the top gas washing wastewater formed is treated by the top gas dechlorination and desulfurization wastewater treatment device (26) and then enters the condensate pump (10), as the industrial water of the Rankine cycle, to achieve circulation: The electricity consumed by water electrolysis to produce hydrogen also comes from gas-fired power generation, steam waste pressure power generation, solar power generation, wind power generation and off-peak power of the power grid; the combustible gases used in gas-fired power generation are coke oven gas, blast furnace gas and converter gas; the steam for steam waste pressure power generation comes from sintering waste heat boilers; The water vapor from coke oven gas-steam reforming to produce hydrogen is low-pressure water vapor after residual pressure power generation; The end product is cast steel profile, casting material of high carbon ductile iron profile with carbon content of 2-4% and silicon content of 2-4%, and casting material of high carbon ductile steel profile with carbon content of 1-2% and silicon content of 1-1.9%; The waste from the final products enters the converter or electric furnace for recycling smelting.

2. The method for systematic carbon reduction in the entire process of steel and casting as claimed in claim 1, in, The top gas input top gas purification device (24) includes a desulfurization tower (241), a capture tower (242), and a regeneration tower (243); the desulfurization tower (241) is connected to the capture tower (242), the dust collector (25) and the top gas dechlorination and desulfurization wastewater treatment device (26); the top gas dechlorination and desulfurization wastewater treatment device (26) is connected to the condensate pump (10); the capture tower (242) is connected to the regeneration tower (243) and the gas mixing chamber 17; the regeneration tower (243) is connected to the second compressor (27).

3. The method for systematic carbon reduction in the entire process of steel and casting as claimed in claim 2, in, Carbon dioxide is extracted from the furnace top gas through a regeneration tower (243), and the extracted carbon dioxide is input into a second compressor (27) for compression and then stored in a carbon dioxide storage tank (28).

4. The method for systematic carbon reduction in the entire process of steel and casting as claimed in claim 1, in, The electricity generated by gas-fired power generation, steam waste pressure power generation, solar power generation and wind power generation is integrated into the internal power grid of the steel plant and transmitted to the water electrolysis hydrogen production equipment.

5. The method for systematic carbon reduction in the entire process of steel and casting as claimed in claim 1, in, The steam generated by the sintering waste heat boiler is transported to the waste pressure power generation device by being incorporated into the high-pressure steam pipeline.

6. The method for systematic carbon reduction in the entire process of steel and casting as claimed in claim 1, in, The low-pressure steam after the excess pressure power generation is transported to the coke oven gas-steam reforming hydrogen production reactor through a low-pressure steam pipeline.

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