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

A systematic carbon emissions reduction method for whole process of steel production and casting, characterized by comprising the steps of:

• blast furnace hydrogen injection;
• wherein the hydrogen is sourced from a nuclear-based hydrogen production system, a water electrolysis hydrogen production system, and a coke oven gas-steam reforming hydrogen production system;
• wherein,
• the nuclear-based hydrogen production system comprises a nuclear power generation subsystem, a hydrogen production thermal cycle subsystem, and a hydrogen-enriched blast furnace-converter subsystem;
• wherein,
• 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 deaerator (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 and oxygen production unit (16), a gas mixing chamber (17), a high-temperature low-pressure heater (18), and a temperature control system (19);
• the hydrogen-enriched blast furnace-converter subsystem comprises a hydrogen-enriched blast furnace (20), a converter (21), a slag waste heat recovery device (22), a third generator (23), a top gas purification unit (24), a dust remover (25), a 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 at 900-1000° C. and 7-8 MPa, which is directed to the first steam turbine (2) of the nuclear power generation subsystem and to 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 perform work, driving the first generator (3) to generate electricity, which is supplied to the water electrolysis hydrogen production system;
• the low-pressure helium output from the first steam turbine (2) mixes with recirculated low-pressure helium from the hydrogen production thermal cycle subsystem to form a stream at 600-700° C., which is conveyed to the steam generator (4);
• the low-pressure helium transfers its thermal energy in the steam generator (4) to convert industrial water into steam via a Rankine bottoming cycle, said steam being fed to the second steam turbine (7);
• the helium is then exhausted as low-temperature, low-pressure helium at 300-400° C. to the first compressor (5);
• said helium is compressed in the first compressor (5) and returned to the nuclear reactor (1) at 350-450° C.;
• a portion of the steam generated by the steam generator (4) is directed to the first pressure reducing valve (6) of the hydrogen production thermal cycle subsystem and, after pressure reduction, to the iodine-sulfur cycle hydrogen and oxygen production unit (16);
• the remainder of the steam expands in the second steam turbine (7) to perform work, driving the second generator (8) to generate electricity, and is then discharged into the condenser (9);
• the electricity generated by the second generator (8) is supplied to the temperature control system (19) of the hydrogen production thermal cycle subsystem;
• the condensate from the condenser (9) is pressurized by the condensate pump (10) and, combined with industrial wastewater provided by the hydrogen-enriched blast furnace-converter subsystem, passes sequentially through the low-pressure heater (11), the deaerator (12), the feed water pump (13), and the high-pressure heater (14) before entering the tube side of the steam generator (4) as feedwater for the Rankine cycle;
• the high-temperature helium from the nuclear reactor (1), after being fed to the second pressure reducing valve (15) and pressure-reduced, is input to the iodine-sulfur cycle hydrogen and oxygen production unit (16);
• together with the steam from the first pressure reducing valve (6) (after pressure reduction), it provides the necessary thermal energy for the iodine-sulfur cycle hydrogen and oxygen production unit (16) operating at 800-900° C. and 4-5 MPa, wherein the steam also serves to supplement the water required for the thermochemical reaction in said unit (16);
• the high-temperature hydrogen produced by the iodine-sulfur cycle hydrogen and oxygen production unit (16) enters the gas mixing chamber (17) and mixes with coke oven gas and carbon monoxide from the top gas purification unit (24) of the hydrogen-enriched blast furnace-converter subsystem to form a high-temperature reducing atmosphere;
• said atmosphere enters the high-temperature low-pressure heater (18) and is heated to 950-1050° C. through heat exchange with 1000-1100° C. helium that has passed through the second pressure reducing valve (15) and been electrically heated by the temperature control system (19);
• the heated reducing atmosphere is then introduced into the hydrogen-enriched blast furnace-converter subsystem;
• after transferring thermal energy, the temperature of the helium drops to 750-850° C.;
• this cooled helium merges with 300-500° C. low-temperature helium that has experienced thermal loss in the iodine-sulfur cycle hydrogen and oxygen production unit (16), ultimately forming 600-700° C. helium which is recirculated into the nuclear power generation subsystem by mixing with the low-pressure helium output from the first steam turbine (2) and entering the steam generator (4);
• the high-temperature oxygen produced by the iodine-sulfur cycle hydrogen and oxygen production unit (16) releases heat through the high-pressure heater (14) and the low-pressure heater (11), undergoes thermal energy exchange with the feedwater entering the steam generator (4), and is then introduced into the hydrogen-enriched blast furnace-converter subsystem;
• the high-temperature reducing atmosphere produced by the hydrogen production thermal cycle subsystem is injected into the hydrogen-enriched blast furnace (20) through the lower shaft or bosh region;
• reduction reactions occur in the hydrogen-enriched blast furnace (20), producing molten iron which is charged into the converter (21);
• low-temperature oxygen is introduced into the hydrogen-enriched blast furnace (20) and the converter (21) to facilitate oxidation reactions, yielding steel products;
• simultaneously, waste heat from slag is recovered by the slag waste heat recovery device (22);
• utilizing a Kalina cycle power generation system, thermal energy is converted into electrical energy, enabling the third generator (23) to generate electricity to power the top gas purification unit (24) and the top gas dechlorination and desulfurization wastewater treatment device (26);
• the top gas generated from the reduction and oxidation reactions in the hydrogen-enriched blast furnace (20) passes sequentially through the dust remover (25) and the top gas purification unit (24), after which the remaining harmless gaseous components are discharged into the atmosphere;
• the top gas, after passing through the dust remover (25), is treated through the desulfurization tower (241) of the top gas purification unit (24);
• the resulting top gas washing wastewater is treated by the top gas dechlorination and desulfurization wastewater treatment device (26) and then fed to the condensate pump (10) for reuse as industrial water in the Rankine cycle, achieving circular utilization;
• the electrical energy consumed by the water electrolysis hydrogen production system is additionally sourced from gas-fired power generation, steam residual pressure power generation, solar power generation, wind power generation, and off-peak grid electricity;
• the combustible gases used for gas-fired power generation are coke oven gas, blast furnace gas, and converter gas;
• the steam for steam residual pressure power generation is sourced from sintering waste heat boilers;
• the steam for the coke oven gas-steam reforming hydrogen production is low-pressure steam obtained after residual pressure power generation;
• the end products are cast steel sections and casting materials comprising high-carbon ductile cast iron profiles with a carbon content of 2-4% and a silicon content of 2-4%, and high-carbon ductile cast steel profiles with a carbon content of 1-2% and a silicon content of 1-1.9%;
• scrap from the end products is introduced into the converter or electric arc furnaces for recycling and smelting.