Integrated energy system model for steel industry park and low-carbon economic dispatching method suitable for steel industry

Abstract

The invention discloses an integrated energy system model in an iron and steel industry park and a low-carbon economic dispatching method suitable for the iron and steel industry, and belongs to the technical field of iron and steel production. According to the method, starting from a production system and an energy system, the minimum total system operation cost and the maximum energy utilization rate are taken as objective functions, and an optimized operation model considering participation of the multi-element hydrogen production and carbon capture equipment in the IES of the iron and steel industry park is established. Five examples are set for comparative analysis, and a constraint method is used for solving. Optimization results show that the steel production process is optimized by introducing electric hydrogen production and by-product gas hydrogen production in the steel industrial park. Experimental results show that the model provided by the invention effectively improves the energy utilization rate while ensuring that the economic cost is reduced, and carbon emission is further reduced through collaborative optimization of carbon capture and a hydrogen energy system. The results provide guidance for iron and steel enterprises to improve the energy utilization rate and reduce the system operation cost and carbon emission.

Description

Technical Field

[0001] This invention discloses an integrated energy system model for steel industrial parks and a low-carbon economic dispatching method applicable to the steel industry, belonging to the field of steel production technology. Background Technology

[0002] In existing technologies, steel production systems and energy systems are scheduled independently, and the coupling advantages of energy flow and material flow are not fully utilized, making it difficult to improve energy utilization efficiency.

[0003] Existing scheduling models mostly focus on a single objective of economic cost or carbon emissions, and cannot simultaneously balance economic and energy efficiency needs, making it difficult to achieve both total system cost control and energy utilization efficiency improvement.

[0004] The linkage between carbon emission reduction measures and economic incentive mechanisms is insufficient, resulting in limited carbon emission reduction effects and insufficient room for economic cost optimization. Summary of the Invention

[0005] To address the problems of existing technologies, this invention proposes an integrated energy system model for steel industrial parks and a low-carbon economic dispatch method applicable to the steel industry.

[0006] The technical solution adopted in this invention is as follows: starting from the production system and energy system, with the objective function of minimizing the total operating cost of the system and maximizing the energy utilization rate, an optimized operation model of the integrated energy system (IES) for steel industrial parks is established, taking into account the participation of multiple hydrogen production and carbon capture equipment.

[0007] An integrated energy system model for a steel industrial park includes a steel production system, an energy system, an energy control system, and a carbon capture and storage system. The steel production system and the energy system are deeply connected through a directional link. By-product gas and waste heat generated by the steel production system are directly connected to the energy system. The energy control system is connected to the energy system at one end to obtain power, and provides hydrogen energy to the steel production system at the other end. The carbon capture and storage system is connected to the steel production system to collect the flue gas emitted by the steel production system.

[0008] Specifically, the steel production system includes long-process production lines, short-process production lines, and shared processing equipment. The long-process production lines include coke ovens, sintering machines, blast furnace feed silos, blast furnaces, and converters. The short-process production lines include electric arc furnaces. The shared processing equipment is a rolling mill. In the long process, coal is fed into the coke oven via a conveying pipeline. The coke produced in the coke oven and the iron ore processed by the sintering machine are jointly transported to the blast furnace feed silos via a material conveyor belt, and then enter the blast furnace to smelt iron. The molten iron is fed into the converter for refining steel via a ladle conveyor track. In the short process, scrap steel is directly fed into the electric arc furnace for smelting steel via a scrap steel conveyor belt. The molten steel from both production lines is fed into the rolling mill via a ladle conveyor track for processing into steel products.

[0009] The energy system includes an energy source unit, an integrated multi-interface energy hub unit, and an energy conversion unit. The energy source unit includes a power grid, wind turbines, and photovoltaic equipment. The energy conversion unit includes a gas holder, waste heat power generation equipment, a fuel boiler, and a steam turbine. The power grid is connected to the energy hub via high-voltage transmission lines, while wind power and photovoltaic power are connected via low-voltage transmission lines. The energy hub distributes electrical energy to the waste heat power generation equipment, electrolyzer, fuel boiler, and steam turbine via four independent transmission cables. The gas holder supplies gas to the fuel boiler via branch gas pipelines. The steam generated by the fuel boiler is connected to the steam turbine via steam pipelines. The steam turbine and waste heat power generation equipment convert electrical energy and send it back to the energy hub via transmission cables, forming a closed-loop flow of electrical energy.

[0010] The energy control system, as the supply end of low-carbon metallurgy, consists of an electrolyzer and a hydrogen storage tank. The energy hub supplies power to the electrolyzer through a power transmission cable. The hydrogen produced by the electrolyzer is stored in the hydrogen storage tank through a hydrogen transmission pipeline. It is then connected to the hydrogen smelting interface of the blast furnace and the hydrogen refining interface of the converter through two branch pipelines, respectively, to provide hydrogen energy in a targeted manner to realize hydrogen-containing metallurgy.

[0011] As a low-carbon governance end, the carbon capture and storage system includes a carbon capture device with four independent air inlets and a carbon storage device. The flue gas emission outlets of the blast furnace, converter, fuel boiler and steam turbine are respectively connected to the corresponding air inlets of the carbon capture device through flue gas pipelines. The captured CO2 is connected to the carbon storage device through a dedicated CO2 conveying pipeline to achieve storage.

[0012] Meanwhile, the steel production system and the energy system are deeply integrated through a directional link. Coke oven gas, blast furnace gas, and converter gas generated by coke ovens, blast furnaces, converters, and electric arc furnaces are connected to gas holders through independent gas transmission pipelines. Waste heat generated by blast furnaces, converters, and rolling mills is connected to waste heat power generation equipment through dedicated waste heat recovery pipelines.

[0013] A low-carbon economic dispatching method applicable to the steel industry includes the following steps:

[0014] Step 1: Construct the integrated energy system model of the steel industrial park mentioned above. First, construct the basic structure of the steel industrial park IES containing hydrogen metallurgy and carbon capture equipment, and then analyze the internal structure of the steel production system and energy system in detail.

[0015] Step 2: Taking into account economic, energy efficiency and carbon efficiency factors, construct the corresponding objective function with the optimization objectives of minimizing the total daily production cost and maximizing the energy utilization rate of the integrated energy system of the steel industrial park;

[0016] Step 3: Considering the operational constraints of the integrated energy system (IES) of the steel industrial park, it is necessary to meet the real-time balance of electricity, heat, hydrogen and coal gas energy, and the energy supply should be equal to or greater than the energy demand.

[0017] Step 4: Select - Constraint method as a model solution method for solving the optimization problem of integrated energy system in steel industrial parks;

[0018] Step 5: Select the research object and explore the impact of hydrogen-coated carbon capture synergistic operation on the low-carbon economic operation of the integrated energy system of the steel industrial park. Optimize the scheduling with a 24-hour cycle and set up a case study for verification and analysis.

[0019] Step 6: Assuming energy utilization remains constant, if the following parameters are adjusted: hydrogen metallurgy ratio, carbon capture rate, and electricity price, observe the changes in cost, carbon emissions, and energy utilization of the integrated energy system in the steel industrial park.

[0020] Specifically, in Step 1, the basic structure of the IES (Environmental Engineering System) for a steel industrial park containing hydrogen metallurgy and carbon capture equipment is constructed. This basic structure is considered an organic coupling of the steel production system and the energy system. The steel production system, energy system, and energy efficiency and carbon efficiency are analyzed. Multiple energy sources, including electricity, heat, hydrogen, and by-product coal gas, are integrated to form a multi-energy complementary and efficient utilization system. The CO2 emissions from the carbon capture equipment system and the carbon emission models for the IES of the steel industrial park are as follows:

[0021] ;

[0022] In the formula: Calculate the actual carbon emissions at time t; Let t be the total carbon emissions generated by the integrated energy system of the steel industrial park at time t; Let t be the amount of carbon emissions captured by the carbon capture device at time t; Let be the electricity consumption at time t; Let be the amount of fuel consumed at time t; Let t be the energy consumption of the carbon capture equipment during operation; Let t be the output of the gas turbine; Let t be the carbon emissions generated during the hydrogen production process from coke oven gas at time t; Let g be the demand-side consumption of the g-th energy type at time t; Let g be the feedback quantity of the g-th type of energy at time t; , , , , These are the carbon dioxide emission coefficients for electricity, fuel, carbon capture equipment, gas turbines, and Class G energy sources, respectively. For carbon capture efficiency.

[0023] Traditional carbon trading mechanisms have a fixed price per unit of carbon allowance, limiting their ability to constrain carbon emissions. Tiered carbon trading mechanisms divide carbon emission allowances into multiple tiers, with excess allowances purchased at tiered prices; the more emissions, the higher the carbon price. The tiered carbon trading cost calculation model is as follows:

[0024] ;

[0025] In the formula: Let t be the tiered carbon trading cost of the integrated energy system of the steel industrial park at time t, in yuan; p be the benchmark price of carbon trading, in yuan / t; and L be the unit carbon trading range. Let t represent the carbon emissions of the system participating in carbon trading, and a and b represent the reward coefficient and penalty coefficient for carbon trading, respectively.

[0026] Specifically, in Step 2, energy supply is optimized by introducing hydrogen production technologies such as water electrolysis and coke oven gas, and carbon capture and geological storage technologies are used to achieve end-of-pipe emission reduction. In response to the cost increase caused by the short process of electric furnace, an optimization model is constructed with the goal of minimizing the total daily production cost of the system and maximizing energy utilization, taking into account the balance between economy, energy efficiency and carbon efficiency.

[0027] Specifically, in Step 3, the real-time energy balance constraints are satisfied, including power balance constraints, hydrogen balance constraints, and energy equipment operation constraints. The energy equipment operation constraints include the inability of charging and discharging in the energy storage equipment to occur simultaneously, the energy storage at the initial moment and the end of the scheduling cycle being equal, and carbon capture power consumption constraints.

[0028] Specifically, in Step 4, using - The constraint method is used to solve the optimization problem of the integrated energy system of the steel industrial park, obtaining the Pareto solution set. Finally, the Knee Point method is used to select the optimal solution. By calculating the curvature of the Pareto solution, the point with the largest curvature is selected. The "inflection point" is found on the Pareto front, which is the point where the rate of change of the objective improvement is the largest (usually representing the most reasonable solution in terms of trade-offs).

[0029] ;

[0030] In the formula: The objective function is... For the objective function The allowed upper limit, the range of values ​​is: From the minimum to the maximum value; n is the number of objective functions; m is the total number of objective functions; The first objective function is... - The objective to be optimized in the constraint method;

[0031] By addressing the issues of lowest cost and highest energy efficiency, coordination of operating costs and energy dispatch within the IES (Engineering, Procurement, and Construction) of steel industrial parks can be achieved. These two optimization problems aim to find a compromise that simultaneously satisfies the requirements of a low-carbon economy and energy conservation. First, the energy utilization rate target is transformed into... - Constraints: The primary objective remains the economic objective, which is to minimize unused energy (total energy input minus effectively utilized energy) to maximize energy utilization. Secondly, the discretization interval is determined by calculating the maximum and minimum energy utilization rates. Specific steps: Optimize the primary objective separately to obtain the minimum cost. When the cost is optimal, optimize the secondary objective (unutilized energy) to obtain the maximum value of unutilized energy (at which point energy utilization is worst). Directly optimize the secondary objective (unutilized energy) to obtain its minimum (i.e., the highest energy utilization rate). Then, divide the above interval into N equal parts. Values, gradually adjust the constraint boundaries ( Solve the single-objective optimization problem, use the MILP solver to output the optimal cost and the corresponding scheduling scheme, and finally collect all... point, In - In the constraint method, the minimum cost obtained by optimizing the main objective (economic objective) alone (i.e., the above) (corresponding to the optimal cost result), plot the economic cost-energy utilization rate Pareto curve, and select a compromise solution from the Pareto frontier (such as the solution ε corresponding to the inflection point of the cost growth rate).

[0032] Specifically, in Step 5, the example is set up with a daily crude steel output of 8640 tons for a steel plant in a steel industrial park in Yunnan Province, of which 5760 tons are produced through the long-process production and 2880 tons through the short-process production. Based on its historical data, five different scenarios are set up to analyze the production costs and carbon emissions in different scenarios.

[0033] 1) Scenario 1: A steel industrial park that integrates blast furnace long-process and electric arc furnace short-process production;

[0034] 2) Scenario 2: Based on Scenario 1, introduce electrolysis equipment and consider hydrogen production by electrolysis of water and hydrogen production from coke oven gas;

[0035] 3) Scenario 3: Based on Scenario 1, carbon capture and storage technology is introduced to capture carbon after combustion, transport it and store it underground;

[0036] 4) Scenario 4: Based on Scenario 1, construct an integrated energy system for the steel industrial park that integrates water electrolysis, coke oven gas hydrogen production, and carbon capture.

[0037] 5) Scenario 5: Based on Scenario 1, a comprehensive energy system for a steel industrial park is constructed, integrating water electrolysis, coke oven gas hydrogen production, and carbon capture. The power balance of the integrated energy system is compared with that of Scenarios 1-4, considering a tiered carbon trading mechanism. The power balance, gas, and hydrogen operation results of the integrated energy system are analyzed. The feasibility and advantages of the low-carbon economic dispatch model considering the integrated operation of hydrogen metallurgy and carbon capture are verified. Using Pareto optimality to balance cost and energy utilization, the solution corresponding to the "inflection point" P is selected as the optimal solution. Water electrolysis and coke oven gas jointly provide hydrogen energy for blast furnace production, replacing some coal, reducing CO2 emissions, and lowering energy purchase costs. By analyzing the output of the metallurgical process in each dispatch cycle, the impact of different carbon trading mechanisms on costs is compared. The optimized dispatch model for the integrated energy system of the steel industrial park prioritizes the tiered carbon pricing mechanism, and the higher carbon trading revenue under the tiered carbon pricing mechanism demonstrates a stronger incentive effect.

[0038] Specifically, in Step 6, the proportion of hydrogen replacing coke is gradually increased (10%~50%), and the impact of changes in the hydrogen metallurgy ratio on costs is compared; the changes in energy utilization, carbon cost, and total cost are analyzed when the proportion of CO2 capture changes from 60% to 90%; the original scenario is used as a benchmark, and the system operation results are obtained by using ordinary billing and time-of-use billing with fluctuations of -20% and +20% respectively.

[0039] The beneficial effects of this invention are:

[0040] 1. Enhanced System Synergy: By integrating the production system and the energy system, the diversified hydrogen production (hydrogen production by electricity and hydrogen production by by-product coal gas) and carbon capture equipment are deeply integrated into the optimization of the integrated energy system (IES) of the steel industrial park, giving full play to the coupling advantages of energy flow and material flow, and solving the problem of insufficient system synergy in the existing technology.

[0041] 2. Multi-objective collaborative optimization: An optimization model is established with the goal of "minimizing the total system operating cost and maximizing energy utilization", which realizes the dual optimization of economic cost and energy efficiency, and makes up for the deficiency of single optimization objective in the existing technology.

[0042] 3. Enhanced efficiency through technology coupling: By synergistically optimizing carbon capture and storage (CCS) technology, tiered carbon trading mechanism and hydrogen energy system, the linkage between carbon emission reduction measures and economic incentive mechanism has been strengthened. This has not only significantly reduced carbon emissions (carbon emissions in the park have been reduced by 12,480.8941 tons), but also effectively reduced system operating costs (total system costs have been reduced by 12.27%), thus solving the problem of the lack of existing technology coupling. Attached Figure Description

[0043] Figure 1 Here is a schematic diagram of an integrated energy system model for a steel industrial park.

[0044] Figure 2 For: use -Detailed process diagram of the constraint method to solve the proposed low-carbon economic dispatch model that considers the coordinated operation of hydrogen metallurgy and carbon capture.

[0045] Figure 3 For example: a graph showing the output of new energy sources versus the load forecast.

[0046] Figure 4 Here are the power balance diagrams for scenarios 1-4 in the specific embodiments;

[0047] Figure 5 For: Power balance diagram;

[0048] Figure 6 For: Gas balance diagram;

[0049] Figure 7 For example: Hydrogen balance diagram;

[0050] Figure 8 For: Pareto boundary map;

[0051] Figure 9 Here is a graph showing the output of metallurgical processes in each scheduling cycle under scenario 5.

[0052] Figure 10 The following is a comparison of various scenarios under different carbon trading mechanisms. The small image on the right is a magnified view of the part framed by the large image on the left. (Note: Total costs of 0, 1, and 2 in the figure correspond to the total costs under no carbon trading, benchmark carbon price, and tiered carbon price, respectively; carbon trading costs of 1 and 2 correspond to the carbon trading costs under benchmark carbon price and tiered carbon price, respectively.) Detailed Implementation

[0053] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0054] Example 1: As Figure 1-10 As shown, a low-carbon economic dispatching method applicable to the steel industry includes the following steps:

[0055] Step 1: Construct an integrated energy system model for the steel industrial park. First, build the basic structure of the steel industrial park IES containing hydrogen metallurgy and carbon capture equipment, and then analyze the internal structure of the steel production system and energy system in detail.

[0056] Step 2: Taking into account economic, energy efficiency and carbon efficiency factors, construct the corresponding objective function with the optimization objectives of minimizing the total daily production cost and maximizing the energy utilization rate of the integrated energy system of the steel industrial park;

[0057] Step 3: Considering the operational constraints of the integrated energy system (IES) of the steel industrial park, it is necessary to meet the real-time balance of electricity, heat, hydrogen and coal gas energy, and the energy supply should be equal to or greater than the energy demand.

[0058] Step 4: Select - Constraint method as a model solution method for solving the optimization problem of integrated energy system in steel industrial parks;

[0059] Step 5: Select the research object and explore the impact of hydrogen-coated carbon capture synergistic operation on the low-carbon economic operation of the integrated energy system of the steel industrial park. Optimize the scheduling with a 24-hour cycle and set up a case study for verification and analysis.

[0060] Step 6: Assuming energy utilization remains constant, if the following parameters are adjusted: hydrogen metallurgy ratio, carbon capture rate, and electricity price, observe the changes in cost, carbon emissions, and energy utilization of the integrated energy system in the steel industrial park.

[0061] Furthermore, in Step 1, we present the integrated energy system model for the steel industrial park.

[0062] The basic structure of the IES (Environmental Engineering System) for a steel industrial park is presented. The steel production system and energy system are modeled separately, and the system is analyzed from the perspectives of energy efficiency and carbon efficiency.

[0063] 1.1 System Structure

[0064] This invention provides an integrated energy system model for steel industrial parks. The core innovation of this integrated energy system model is the construction of a closed-loop coupled architecture integrating "steel production - energy regulation - hydrogen supply - carbon capture and storage". The four core systems are clearly defined and precisely and efficiently connected: the steel production system, as the core production end, includes long-process production lines (coke oven, sintering machine, blast furnace raw material silo, blast furnace, converter), short-process production lines (electric arc furnace), and shared processing equipment (rolling mill). In the long process, coal is fed into the coke oven via a conveyor pipeline. The coke produced by the coke oven and the iron ore processed by the sintering machine are transported together to the blast furnace raw material silo via a material conveyor belt, and then enter the blast furnace to smelt iron. The molten iron is then processed through the ladle. The conveyor rail connects to the converter for refining molten steel. In the short-process, scrap steel is directly fed into the electric arc furnace for molten steel via a scrap steel conveyor belt. Molten steel from both production lines is fed into the rolling mill via a ladle conveyor rail for processing into finished steel products. The energy system, as the core of energy regulation, encompasses energy sources (power grid, wind turbines, photovoltaic equipment), integrated multi-interface energy hub units, and energy conversion units (gas holders, waste heat power generation equipment, fuel boilers, steam turbines). The power grid is connected to the energy hub via high-voltage transmission lines, while wind power and photovoltaic power are connected via low-voltage transmission lines. The energy hub distributes electricity to the waste heat power generation equipment, electrolyzer, fuel boiler, and steam turbine via four independent transmission cables. The gas holder supplies gas to the fuel boiler via branch gas pipelines. Steam generated by the fuel boiler is piped to the steam turbine. The steam turbine and waste heat power generation equipment then transmit the converted electricity back to the energy hub via transmission cables, forming a closed-loop energy flow. The hydrogen energy unit, serving as the low-carbon metallurgical supply end, consists of an electrolyzer and a hydrogen storage tank. The energy hub supplies power to the electrolyzer via transmission cables. The hydrogen produced by the electrolyzer... The gas is stored in a hydrogen storage tank through a hydrogen transmission pipeline, and then connected to the hydrogen smelting interface of the blast furnace and the hydrogen refining interface of the converter through two branch pipelines respectively, to provide hydrogen energy in a targeted manner to realize hydrogen-containing metallurgy; the carbon capture and storage unit, as the low-carbon treatment end, includes a carbon capture device with four independent air inlets and a carbon storage device. The flue gas emission outlets of the blast furnace, converter, fuel boiler and steam turbine are respectively connected to the corresponding air inlets of the carbon capture device through flue gas pipelines. The captured CO2 is connected to the carbon storage device through a dedicated CO2 transmission pipeline for sealing. Meanwhile, the steel production system and energy system are deeply integrated through targeted links. Coke oven gas, blast furnace gas, and converter gas generated by coke ovens, blast furnaces, converters, and electric arc furnaces are connected to gas holders via independent gas transmission pipelines. Waste heat generated by blast furnaces, converters, and rolling mills is connected to waste heat power generation equipment via dedicated waste heat recovery pipelines. All systems are connected without redundancy through "dedicated equipment interface - dedicated transmission carrier - corresponding equipment interface", realizing full recovery of production by-products, closed-loop utilization of energy, targeted hydrogen supply, and full carbon emission source coverage and capture. This has built an integrated solution for the low-carbon transformation of the steel industry and provided an innovative path for the coordinated development of the park's economy and environment.

[0065] 1.2 Steel Production System Analysis

[0066] 1.2.1 Blast Furnace Long Process

[0067] The blast furnace-converter long process includes coking, ore beneficiation, and ironmaking. First, molten iron is produced in the blast furnace, then smelted into steel in the converter. The steel then undergoes a series of processes including refining, casting, and rolling to finally obtain the finished steel product. The blast furnace long process steelmaking model uses electricity, coal, and iron ore as the main input factors, and crude steel and gas as the output products. In the blast furnace long process, electricity is mainly used for the operation of auxiliary equipment and does not directly participate in the chemical reaction. This invention treats the daily crude steel production as a constant and establishes a production state model for the blast furnace, converter, and electric furnace. The relationship between blast furnace long process steelmaking production and material consumption is as follows:

[0068] (1)

[0069] In the formula: The efficiency coefficient of blast furnace long-process steelmaking; Coal conversion coefficient; The iron ore conversion coefficient; Let t be the crude steel production rate of the blast furnace long-process steelmaking at time t; and These represent the amount of coal and iron ore consumed in the long-process blast furnace steelmaking, in tons. This is the power consumption coefficient for long-process steelmaking in blast furnaces, which is the electrical energy required to produce 1 ton of crude steel. Let t be the power consumption of the long-process steelmaking in the blast furnace at time t, in MW.

[0070] 1.2.2 Short Process Electric Furnace

[0071] (2)

[0072] In the formula: Let t be the amount of scrap steel consumed in the short-process electric arc furnace. The scrap steel consumption coefficient for electric arc furnace short-process steelmaking; The power consumption coefficient per ton of steel is the electrical energy required (MW / t) to produce 1 ton of crude steel through the electric arc furnace short-process steelmaking process. The amount of crude steel produced by the electric arc furnace short-process at time t; Let t be the short-process power consumption of the electric furnace, in MW; , The power consumption for short-process circuits is defined by upper and lower limits.

[0073] 1.3 Energy System Analysis

[0074] 1.3.1 Gas

[0075] The energy system includes energy supply equipment, energy recovery, conversion and storage equipment. In the steel production process, blast furnaces, converters and other production equipment will generate coal gas. Among them, coke oven gas (COG) is generated in the coking process and is mainly composed of hydrogen and methane; blast furnace gas (BFG) is generated when coke is fed into the blast furnace for ironmaking, and is used as a reducing agent to reduce the iron in the iron ore; converter gas (LDG) is generated in the steelmaking process. Since crude steel is one of the final products of blast furnace smelting, this invention establishes a coal gas production model based on crude steel output as shown in equation (3).

[0076] (3)

[0077] In the formula: , , These represent the quantities of coke oven gas, blast furnace gas, and converter gas produced at time t in the long blast furnace process, in m. 3 ; , , These are the gas production coefficients for coke ovens, blast furnaces, and converters, respectively, m 3 / t steel.

[0078] 1.3.2 Waste heat power generation

[0079] A significant amount of waste heat is not fully utilized in the steel production process. This invention considers cokedry quenching (CDQ) waste heat recovery and power generation technology in the coking process. This technology recovers the heat generated in the coke oven, and the steam generated in the dry quenching boiler is sent to a steam turbine power generation system for electricity generation. The power output of the waste heat power generation equipment is [not specified]. With heat consumption power The relationship between them is as follows:

[0080] (4)

[0081] In the formula: Let t be the output power of waste heat power generation, in MW; The power generation coefficient of the waste heat power generation equipment; The efficiency of waste heat recovery in waste heat power generation equipment; Let t be the coke oven heat output power, in kJ; Coke burn-off rate; The calorific value of coke; Let t be the output of coke in the coke oven at time t; This represents the coal conversion coefficient.

[0082] 1.3.3 Fuel Boiler

[0083] In steel enterprises, the conversion of coal gas to steam mainly occurs on boiler equipment. Based on the fuel used, boilers can be classified as all-gas boilers, all-coal boilers, and mixed-fuel boilers. This invention considers all-gas boilers, and based on energy conservation, the energy input-output model expression can be obtained as follows:

[0084] (5)

[0085] In the formula, This represents the amount of steam of grade r produced in the boiler at time t, in kg. The enthalpy value of r-grade steam is expressed in kJ / kg. m represents the amount of gas (g) consumed in the boiler at time t. 3 ; The calorific value of gas is g, kJ / m³. 3 ; This refers to the conversion efficiency of the fuel boiler.

[0086] The relationship between the heat output of a fuel boiler and the power consumption of gas can be expressed as:

[0087] (6)

[0088] In the formula: Let t be the heat output of the fuel boiler, in MW; For the thermal conversion rate of fuel boilers; Let t be the gas consumption power of the gas boiler, in MW; Let t be the upper limit of the output of the gas-fired boiler, in MW.

[0089] 1.3.4 Steam Turbine

[0090] Steam turbines use steam as the power medium to convert steam into electricity. Their energy input-output model can be expressed as follows:

[0091] (7)

[0092] In the formula, m represents the steam consumption of stage r in the steam turbine at time t. 3 ; For the conversion efficiency of the steam turbine; Let t be the power generation of the steam turbine at time t, in MW; The enthalpy of the generated electricity is expressed in kJ / MW. , The upper and lower limits for steam absorption by the steam turbine; Let t be the turbine's heat output power, in MW. The power consumed by the steam turbine; The electro-conversion rate of the steam turbine; This represents the energy loss rate of the steam turbine.

[0093] 1.3.5 Hydrogen production by water electrolysis

[0094] Hydrogen is produced by water electrolysis. The water electrolysis model is as follows:

[0095] (8)

[0096] In the formula: Let t be the hydrogen production power of the electrolyzer at time t, in MW; The efficiency coefficient for electro-hydrogen production; Let t be the power consumption of the electrolytic cell. The output hydrogen quantity at time t; The conversion coefficient for hydrogen production via electro-hydrogen generation; , These are the upper and lower limits of the installed capacity of the electrolytic cell.

[0097] 1.3.6 Hydrogen production from by-product coal gas

[0098] (9)

[0099] In the formula: Let m be the hydrogen production rate of coke oven gas at time t. 3 ; To improve the efficiency of coke oven gas to hydrogen conversion; Let m be the gas consumption for hydrogen production from coke oven gas at time t. 3 ; , These represent the upper and lower limits of hydrogen production from coke oven gas.

[0100] 1.3.7 Storage Battery

[0101] This invention models an electric energy storage device.

[0102] (10)

[0103] In the formula: , Let be the charging and discharging power of the energy storage device at time t, in MW. Let be the output power of the energy storage device at time t, in MW; , These refer to the charging efficiency and discharging efficiency of energy storage devices, respectively. The energy dissipation coefficient of the energy storage device; Let MWh be the energy storage thermal capacity of the energy storage device at time t. The rated capacity of the energy storage device is MWh; h represents the time step (the time interval between two adjacent moments in the model).

[0104] 1.3.8 Hydrogen Storage Tank

[0105] (11)

[0106] In the formula: , Let m be the volume of hydrogen in the hydrogen storage tank at time t and time t-1. 3 ; Let m be the volume of hydrogen flowing into the hydrogen storage tank at time t-1. 3 ; Let t be the volume of hydrogen flowing out of the hydrogen storage tank at time t-1.

[0107] 1.3.9 Gas Holder

[0108] In the steel industry, coal gas, as an important secondary energy source, is primarily recovered and reused directly in the steel production process, serving as fuel for core production equipment such as coke ovens, blast furnaces, and converters. While ensuring stable production, surplus coal gas is diverted: a portion is stored in gas holders for emergencies, while the other portion is supplied to energy coupling equipment such as boilers and CHP (combined heat and power) units, converting it into electricity, heat, or steam to meet the energy demands of steel production. However, due to a mismatch between actual coal gas production and consumption, coal gas dissipation occurs.

[0109] (12)

[0110] In the formula: Let g be the volume of gas (COG, BFG, LDG) in the gas holder at time t, in m³. 3 ; Let m be the total amount of gas g produced at time t. 3 ; Let m be the amount of gas consumed by the production user at time t (g). 3 ; Let m be the amount of gas g flowing into the boiler at time t. 3 ; Let m be the amount of hydrogen produced by g of coal gas at time t. 3 ; Let m be the amount of gas g released at time t. 3 ; , These are the upper and lower limits of the cabinet, respectively, m 3 .

[0111] 1.4 Energy efficiency and carbon efficiency analysis

[0112] 1.4.1 Comprehensive energy utilization rate

[0113] After converting all types of energy within the steel industrial park's IES into electrical energy, the overall energy consumption level of the system is measured based on the ratio (%) of effectively utilized energy to total energy input.

[0114] (13)

[0115] in, Energy utilization rate of the integrated energy system in the steel industrial park; , , These represent the terminal effective energy consumed within the park, such as electrical energy, thermal energy, and hydrogen, in MW. The total amount of clean energy input to the new energy equipment (photovoltaic, wind power) systems within the park, in MW; MW represents all externally purchased energy sources for the system (electricity purchased from the grid, externally purchased fossil fuels, etc.).

[0116] 1.4.2 Carbon emission quotas

[0117] Carbon efficiency indicators can be reflected in the carbon dioxide emissions per unit of GDP, the carbon emissions consumed in producing a unit of goods or providing a unit of services, etc. This invention addresses the carbon emissions problem generated in the steel production process by considering a low-carbon scheduling model for carbon capture equipment and introducing a tiered carbon trading mechanism to achieve the goal of reducing the overall system cost.

[0118] 1) Carbon capture equipment model

[0119] The relationship between carbon capture equipment and the energy consumption required for CO2 capture is as follows:

[0120] (14)

[0121] In the formula: Let t be the carbon capture energy consumption of the carbon capture equipment at time t, in MW; Energy consumption required to process one unit of CO2, in MW / t; Let t be the amount of CO2 captured by the carbon capture device at time t; The minimum energy consumption for carbon capture equipment operation, in MW; The maximum energy consumption for carbon capture equipment operation Maximum carbon capture capacity, MW.

[0122] 2) Carbon emission model

[0123] Blast furnace ironmaking involves the reaction of iron ore and coke to reduce the iron oxide in the ore to elemental iron, producing molten iron. Hydrogen metallurgy, on the other hand, uses hydrogen as a reducing agent to react with iron ore, producing iron and water as products. Hydrogen production using natural gas and industrial by-product coal gas, or through carbon capture technology, is low-cost and can be applied on a large scale, but the process generates carbon emissions. Electrolysis of water to produce hydrogen has no direct carbon emissions and produces hydrogen with higher purity.

[0124] Carbon emission sources are distributed throughout various stages of the steel production process. This invention considers both direct and indirect carbon emissions. The carbon emissions from the integrated energy system for the steel industry constructed in this invention mainly originate from purchased electricity, the combustion of fossil fuels, the operation of fuel boilers and steam turbines, the coke oven gas-to-hydrogen process, and the utilization of by-product gas. The coke oven gas-to-hydrogen process generates waste flue gas, the carbon emission of which is calculated using the following formula:

[0125] (15)

[0126] In the formula: Let t be the carbon emissions from hydrogen production using coke oven gas, in kg; The carbon adsorption rate for hydrogen production from coke oven gas; The carbon emission coefficient for hydrogen production from coke oven gas; Let t be the amount of hydrogen produced during the coke oven gas hydrogen production process; This represents the density of hydrogen gas under standard conditions.

[0127] The basic structure of an IES (Environmental Engineering System) for a steel industrial park incorporating hydrogen metallurgy and carbon capture equipment is constructed. This basic structure is considered as an organic coupling of the steel production system and the energy system. The steel production system, energy system, and energy efficiency and carbon efficiency are analyzed, and multiple energy sources, including electricity, heat, hydrogen, and by-product coal gas, are integrated to form a multi-energy complementary system. The following is a model of CO2 emissions from the carbon capture system and the IES carbon emissions from the steel industrial park, along with a model of efficient utilization systems:

[0128] (16)

[0129] In the formula: Calculate the actual carbon emissions at time t; Let t be the total carbon emissions generated by the integrated energy system of the steel industrial park at time t; Let t be the amount of carbon emissions captured by the carbon capture device at time t; Let be the electricity consumption at time t; Let be the amount of fuel consumed at time t; Let t be the energy consumption of the carbon capture equipment during operation; Let t be the output of the gas turbine; Let t be the carbon emissions generated during the hydrogen production process from coke oven gas at time t; Let g be the demand-side consumption of the g-th energy type at time t; Let g be the feedback quantity of the g-th type of energy at time t; , , , , These are the carbon dioxide emission coefficients for electricity, fuel, carbon capture equipment, gas turbines, and Class G energy sources, respectively. For carbon capture efficiency.

[0130] 3) Carbon Trading Model

[0131] The system's carbon emissions mainly originate from energy consumption and chemical reactions during the production process. The historical intensity method is used to calculate the carbon emission quotas allocated to steel enterprises. This method calculates carbon emission quotas based on the industry's historical carbon emissions per unit output, emission reduction coefficients, and output. The corresponding model is as follows:

[0132] (17)

[0133] In the formula: Carbon quotas are set for the total amount of the system; For historical carbon emissions per ton of steel; This is the emission reduction factor; To measure the output of the blast furnace process at any given time; Let juti be the amount of crude steel produced by the electric furnace short-process at time t.

[0134] Carbon emissions participating in carbon trading in the system It is calculated from the difference between actual carbon emissions and the allowance, and is expressed as follows:

[0135] (18)

[0136] In the formula: Let t represent the carbon emissions generated by the system participating in carbon trading. This represents the actual carbon emissions of the system at time t. It is the carbon emission allowance of the system at time t.

[0137] The carbon emission cost of steel industrial parks is the quota trading cost based on the existing carbon emission trading mechanism, taking into account the free allocation of carbon quotas. The benchmark carbon trading cost, i.e., the carbon trading price, is fixed, and its calculation model is as follows:

[0138] (19)

[0139] In the formula: p is the benchmark price for carbon trading, in yuan / t.

[0140] Traditional carbon trading mechanisms have a fixed price per unit of carbon allowance, limiting their ability to constrain carbon emissions. Tiered carbon trading mechanisms divide carbon emission allowances into multiple tiers, with excess allowances purchased at tiered prices; the more emissions, the higher the carbon price. The tiered carbon trading cost calculation model is as follows:

[0141] (20)

[0142] In the formula: Let t be the tiered carbon trading cost of the integrated energy system of the steel industrial park at time t, in yuan; p be the benchmark price of carbon trading, in yuan / t; and L be the unit carbon trading range. Let t represent the carbon emissions of the system participating in carbon trading, and a and b represent the reward coefficient and penalty coefficient for carbon trading, respectively.

[0143] Specifically, in Step 2, energy supply is optimized by introducing hydrogen production technologies such as water electrolysis and coke oven gas, and carbon capture and geological storage technologies are used to achieve end-of-pipe emission reduction. In response to the cost increase caused by the short process of electric furnace, an optimization model is constructed with the goal of minimizing the total daily production cost of the system and maximizing energy utilization, taking into account the balance between economy, energy efficiency and carbon efficiency.

[0144] This invention considers a low-carbon economic scheduling model that integrates hydrogen metallurgy and carbon capture, specifically an optimized scheduling model that considers the synergy between the two, with the objective functions being minimizing the total daily operating cost and maximizing energy utilization. It also introduces a tiered carbon trading mechanism to control carbon emissions using carbon trading costs.

[0145] 2.1 Objective Function

[0146] Carbon dioxide emissions and energy efficiency are key indicators for measuring whether the steel industry has achieved low-carbon development. To effectively improve energy efficiency and carbon efficiency, this invention focuses on two dimensions: production process optimization and energy structure adjustment. During production, electrolytic water hydrogen production and coke oven gas hydrogen production technologies are introduced to optimize the energy supply structure. Simultaneously, carbon capture equipment performs end-of-pipe treatment of carbon emissions, and carbon dioxide geological storage technology is implemented to further reduce carbon emissions. The application of electric arc furnace short-process steelmaking increases system operating costs; therefore, this invention comprehensively considers economic, energy efficiency, and carbon efficiency factors, constructing a corresponding objective function with the optimization objectives of minimizing the system's total daily production cost and maximizing energy utilization.

[0147] 2.1.1 Total Daily Production Cost of the System

[0148] (twenty one)

[0149] in , These are carbon costs, gas emission costs, The cost of purchasing energy (fossil fuels such as coal and iron ore, hydrogen, and electricity), , This includes the cost of purchasing electricity and the cost of curtailing energy.

[0150] 1) Carbon cost

[0151] Carbon costs include carbon trading costs and carbon storage costs.

[0152] (twenty two)

[0153] In the formula: This represents the carbon storage cost coefficient.

[0154] 2) Cost of gas venting

[0155] (twenty three)

[0156] In the formula: This refers to the amount of gas emitted from the system. The cost of punitive measures for releasing gas.

[0157] 3) Cost of purchased energy

[0158] (twenty four)

[0159] (25)

[0160] In the formula: , These represent the purchase quantities of fossil fuels and hydrogen for the system at time t, respectively. , These are the unit purchase prices for fuel and hydrogen, respectively. The cost of purchasing electricity from the power grid; Purchase electricity for the system; It is a time-of-use electricity price.

[0161] 4) Costs of wind and solar power curtailment

[0162] (26)

[0163] In the formula: The total cost of curtailing wind and solar power; This is the sum of the wind curtailment costs for all time periods; This is the sum of the costs of wasted light across all time periods; , This refers to the penalty coefficient for wind and solar power curtailment. , The predicted power output of wind power and photovoltaic power at time t is in MW; Let t be the actual wind power absorption capacity at time t, in MW; Let t be the actual photovoltaic power output at time t, in MW.

[0164] 2.1.2 System Energy Utilization Rate

[0165] (27)

[0166] In the formula: , , As weight; For the system's energy utilization rate; This refers to the utilization efficiency of the equipment. This is an indicator for the utilization of new energy sources.

[0167] Furthermore, in Step 3, the real-time energy balance constraints are satisfied, including power balance constraints, hydrogen balance constraints, and energy equipment operation constraints. The energy equipment operation constraints include the inability of charging and discharging in the energy storage device to occur simultaneously, the energy storage being equal at the initial moment and at the end of the scheduling cycle, and carbon capture power consumption constraints.

[0168] 3.1 IES Operational Constraints in Steel Industrial Parks

[0169] 3.1.1 Energy supply and demand balance constraints

[0170] The system needs to maintain a real-time balance of energy sources such as electricity, heat, hydrogen, and coal gas, and the system's energy supply should be equal to or greater than its energy demand.

[0171] 1) Power balance constraint

[0172] (28)

[0173] In the formula: Let be the system electrical load at time t, in MW; Let be the power sold to the grid at time t, in MW; Let t be the charging power of the energy storage system at time t, in MW; Let t be the carbon capture energy consumption of the carbon capture equipment at time t, in MW; Let be the electricity consumption at time t, in MW; Let t be the output of the gas turbine, in MW; Let t be the power consumption of the electrolytic cell at time t, in MW; Let t be the power generation of the steam turbine at time t, in MW; Let t be the short-process power consumption of the electric furnace, in MW; Let t be the power consumption of the blast furnace in the long-process steelmaking process at time t, in MW; Let t be the output power of waste heat power generation, in MW; , Let be the charging and discharging power of the energy storage device at time t, in MW. Let t be the gas consumption power of the gas boiler, in MW.

[0174] 2) Hydrogen balance constraint

[0175] The hydrogen generated by the system flows to the ironmaking and steelmaking processes in the production system. Some of the hydrogen is directly used for blast furnace injection and is consumed. At the same time, hydrogen can replace some coal and play a key role in the reduction reaction. The remaining hydrogen is stored in hydrogen storage tanks.

[0176] (29)

[0177] In the formula: This refers to the amount of hydrogen injected into the blast furnace.

[0178] 3.1.2 Energy Equipment Operation Constraints

[0179] Considering the operating characteristics of the equipment, set operating constraints for the equipment.

[0180] 1) Energy storage equipment

[0181] For energy storage devices, charging and discharging cannot occur simultaneously.

[0182] (30)

[0183] (31)

[0184] In the formula: , This is a binary variable representing the charging and discharging state of the battery at time t; and MW represents the maximum charging power and maximum discharging power of the battery.

[0185] For the capacity of energy storage devices, the stored energy is equal at the initial moment and at the end of the scheduling cycle.

[0186] (32)

[0187] In the formula: , MW represents the upper and lower limits of the battery's energy storage capacity.

[0188] 2) Carbon capture power consumption constraints

[0189] (33)

[0190] In the formula: , The upper and lower limits of the ramp-up constraint for capturing power consumption; , The upper and lower limits of the ramp-up constraint for capturing power consumption.

[0191] Specifically, in Step 4, the optimization problem of the integrated energy system of the steel industrial park studied in this invention belongs to the multi-objective optimization problems (MOPs), which include two objective functions: minimizing total cost and maximizing energy utilization. These two objective functions have mutual influence and constraints, and in some cases, they even conflict with each other, making it difficult to achieve the optimal value at the same time.

[0192] - The constraint method takes one objective function in a multi-objective optimization model as the primary objective, and transforms the other objective functions into constraints. By successively modifying the range of these secondary objective functions, different objective function values ​​are obtained, thereby transforming the multi-objective optimization problem into a single-objective optimization problem for solution, simplifying the solution process, as shown in equation (34). Compared to intelligent algorithms, - The constraint method can provide an accurate Pareto optimal solution; therefore, this invention uses... - The constraint method is used to solve the optimization problem of the integrated energy system of the steel industrial park, obtaining the Pareto solution set. Finally, the Knee Point method is used to select the optimal solution. By calculating the curvature of the Pareto solution, the point with the largest curvature is selected. The "inflection point" is found on the Pareto front, which is the point where the rate of change of the objective improvement is the largest (usually representing the most reasonable solution in terms of trade-offs).

[0193] (34)

[0194] In the formula: The objective function is... For the objective function The allowed upper limit, the range of values ​​is: From the minimum to the maximum value; n is the number of objective functions; m is the total number of objective functions; The first objective function is... - The objective to be optimized in the constraint method.

[0195] By addressing the issues of lowest cost and highest energy efficiency, coordination of operating costs and energy dispatch within the IES (Engineering, Procurement, and Construction) of steel industrial parks can be achieved. These two optimization problems aim to find a compromise that simultaneously satisfies the requirements of a low-carbon economy and energy conservation. First, the energy utilization rate target is transformed into... - Constraints: The primary objective remains the economic objective, which is to minimize unused energy (total energy input minus effectively utilized energy) to maximize energy utilization. Secondly, the discretization interval is determined by calculating the maximum and minimum energy utilization rates. Specific steps: Optimize the primary objective separately to obtain the minimum cost. When the cost is optimal, optimize the secondary objective (unutilized energy) to obtain the maximum value of unutilized energy (at which point energy utilization is worst). Directly optimize the secondary objective (unutilized energy) to obtain its minimum (i.e., the highest energy utilization rate). Then, divide the above interval into N equal parts. Values, gradually adjust the constraint boundaries ( Solve the single-objective optimization problem, use the MILP solver to output the optimal cost and the corresponding scheduling scheme, and finally collect all... point, In - In the constraint method, when optimizing the main objective alone, the minimum cost obtained is plotted as an economic cost-energy utilization rate Pareto curve. From the Pareto frontier, a compromise solution is selected (such as the solution ε corresponding to the inflection point of the cost growth rate). Figure 2 The image shows the IES used in the steel industrial park. - The detailed process of using the constraint method to solve the proposed low-carbon economic dispatch model that considers the coordinated operation of hydrogen metallurgy and carbon capture.

[0196] Specifically, in Step 5, the example is set up with a daily crude steel output of 8640 tons for a steel plant in a steel industrial park in Yunnan Province, of which 5760 tons are produced through the long-process production and 2880 tons through the short-process production. Based on its historical data, five different scenarios are set up to analyze the production costs and carbon emissions in different scenarios.

[0197] 5) Scenario 5:

[0198] The following simulation case was used to verify the effectiveness and rationality of the proposed optimization model. All problems and algorithms were completed using Matlab 2023a software and the Gurobi solver on a computer equipped with a 2.9GHz Intel Core i7-10700 processor and 16GB of memory.

[0199] 4.1 Scene Setup

[0200] This embodiment selects a steel industrial park in Yunnan Province as the research object to explore the impact of hydrogen-coated carbon capture synergistic operation on the low-carbon economic operation of the system. Optimization scheduling is performed using a 24-hour cycle, and a numerical example is set up for verification and analysis. The solution approach is as follows: First, using... - The constraint method transforms the multi-objective optimization problem in the steel supply chain energy optimization model constructed in this paper into a single-objective optimization problem, that is, converting the multi-objective optimization model of the steel supply chain into a single-objective optimization model. Secondly, interval number linear programming is used to solve the transformed single-objective optimization model. The interval number linear programming method can effectively handle the interval number expression problem in the coefficients of the objective function and constraint conditions in the optimization model. The following sections will describe these problems in detail. - The main ideas, main solution process and key steps of the constraint method and interval number linear programming method.

[0201] The optimal scheduling model of the integrated energy system in the steel industrial park is a mixed-integer linear programming problem. The model is solved using MATLAB with the CPLEXGurobi tool.

[0202] The example assumes the steel plant's daily crude steel output is 8640t, of which 5760t is produced by the long process and 2880t by the short process. Based on its historical data, the following five scenarios are set up to analyze the impact of different system structures on the park's economic efficiency, carbon emissions, and energy utilization.

[0203] 1) Scenario 1: A steel industrial park that integrates blast furnace long-process and electric arc furnace short-process production;

[0204] 2) Scenario 2: Based on Scenario 1, introduce electrolysis equipment and consider hydrogen production by electrolysis of water and hydrogen production from coke oven gas;

[0205] 3) Scenario 3: Based on Scenario 1, carbon capture and storage technology is introduced to capture carbon after combustion, transport it and store it underground;

[0206] 4) Scenario 4: Based on Scenario 1, construct an integrated energy system for the steel industrial park that integrates water electrolysis, coke oven gas hydrogen production, and carbon capture.

[0207] 5) Scenario 5: Based on Scenario 1, a comprehensive energy system for a steel industrial park is constructed, integrating water electrolysis, coke oven gas hydrogen production, and carbon capture. The power balance of the integrated energy system is compared with that of Scenarios 1-4, considering a tiered carbon trading mechanism. The power balance, gas, and hydrogen operation results of the integrated energy system are analyzed. The feasibility and advantages of the low-carbon economic dispatch model considering the integrated operation of hydrogen metallurgy and carbon capture are verified. Using Pareto optimality to balance cost and energy utilization, the solution corresponding to the "inflection point" P is selected as the optimal solution. Water electrolysis and coke oven gas jointly provide hydrogen energy for blast furnace production, replacing some coal, reducing CO2 emissions, and lowering energy purchase costs. By analyzing the output of the metallurgical process in each dispatch cycle, the impact of different carbon trading mechanisms on costs is compared. The optimized dispatch model for the integrated energy system of the steel industrial park prioritizes the tiered carbon pricing mechanism, and the higher carbon trading revenue under the tiered carbon pricing mechanism demonstrates a stronger incentive effect.

[0208] 4.2 Comparison of IES Operation Scenarios in Steel Industrial Parks

[0209] The optimized scheduling results for the five scenarios are shown in Table 1.

[0210] Table 1 Production Costs and Carbon Emissions in Different Scenarios

[0211]

[0212] As shown in Table 1:

[0213] 1) Compared to Scenario 1, introducing a hydrogen energy system in a steel industrial park (Scenario 2) – by injecting hydrogen into blast furnaces to replace part of the coal, can optimize the system's coal procurement, reduce carbon emissions, and lower overall costs. This solution reduces carbon emissions by 5009.69 tons, lowers total costs by 10.68%, and reduces coal procurement by 1967.51 tons. Due to the use of water electrolysis for hydrogen production, electricity consumption increases, requiring the purchase of more electricity. Energy utilization efficiency improves by 5.61%, directly reducing unit production energy consumption, thereby reducing fuel costs and ultimately lowering the overall system cost.

[0214] 2) Compared to Scenario 1, the total cost of introducing a carbon capture and storage (CFS) system in the steel industrial park (Scenario 3) is slightly higher, increasing by 0.30%, but the carbon reduction effect is more significant, reducing carbon emissions by 12,029.47 tons. Although CFS technology can effectively reduce carbon emissions, the higher construction and operation costs of this technology lead to an increase in the total cost.

[0215] 3) Compared to Scenario 2, the newly added post-combustion carbon capture device in Scenario 3 significantly reduces system carbon emissions by 7019.78 tons. Due to the high cost of carbon capture and storage technology, the total system cost is higher than the baseline scenario without considering this system. In the steel industrial park, due to the large industrial load, the photovoltaic power station's power generation can almost fully meet the demand, resulting in less energy waste.

[0216] 4) Compared with scenario 1, scenario 4 considers the coordinated operation of hydrogen and carbon capture equipment, which reduces carbon emissions by 12,504.71 tons, reduces the total system cost by 10.49%, and improves energy utilization efficiency by 16.35%. This shows that the hydrogen doping-carbon capture and storage technology proposed in this paper can effectively operate the system to generate carbon emissions and reduce the total cost.

[0217] 5) Compared with scenario 3, scenario 4 takes into account the coordinated operation of carbon capture equipment, which reduces carbon emissions by 475.24t, reduces the total system cost by 10.76%, and increases energy utilization efficiency by 13.80%. This shows that the coordinated operation of hydrometallurgy and carbon capture and storage effectively reduces the system's carbon emissions, lowers the total cost, and improves energy utilization.

[0218] 6) Compared with scenarios 1 and 5, considering the tiered carbon trading mechanism, carbon emissions are reduced by 12,504.36 tons, the total system cost is reduced by 12.31%, and energy utilization efficiency is increased by 17.36%. This shows that the tiered carbon trading mechanism can effectively control the system's carbon emissions and reduce the total cost.

[0219] 7) Compared to Scenario 4, Scenario 5 controls carbon emissions through tiered carbon pricing and generates more revenue through carbon trading, thus increasing carbon emissions, with little improvement in energy utilization. Although energy purchase costs and energy disposal costs increase, the overall cost decreases.

[0220] In summary, it can be seen that hydrogen metallurgy technology improves utilization and keeps costs under control; the conventional carbon reduction steelmaking technology proposed by the Chinese Chemical Society reduces carbon emissions, although energy utilization is not significantly improved, but the total cost is increased; as described in Scenario 4, the integrated energy system of the steel industry park using hydrogen steelmaking, carbon capture equipment and carbon sequestration technology can not only achieve low-carbon economic operation of the park, but also improve energy utilization; through tiered carbon trading and enhanced reward and punishment mechanisms, high utilization can be converted into carbon revenue; and through the reward and punishment mechanism enhanced by tiered carbon trading, high utilization can also be converted into carbon income, thereby achieving long-term cost reduction.

[0221] Specifically, in Step 6, the proportion of hydrogen replacing coke is gradually increased (10%~50%), and the impact of changes in the hydrogen metallurgy ratio on costs is compared; the changes in energy utilization, carbon cost, and total cost are analyzed when the proportion of CO2 capture changes from 60% to 90%; the original scenario is used as a benchmark, and the system operation results are obtained by using ordinary billing and time-of-use billing with fluctuations of -20% and +20% respectively.

[0222] 5.1 Analysis of System Optimization Scheduling Results

[0223] Park scenery and load forecast output Figure 3 .

[0224] Depend on Figure 4 As can be seen, in Scenario 1, the generated electricity is mainly used for the BF-BOF and EAF production processes. Steel production is the only power-consuming equipment, and the overall power load output of the system is the smallest compared to the other scenarios. Scenario 2 adds an electrolytic cell to Scenario 1, which increases the system's power consumption and the amount of electricity purchased. Scenario 3 adds a post-combustion carbon capture device to Scenario 1. Although carbon capture consumes power, its power consumption is relatively small, and the overall system load output does not change much. Scenario 4 takes into account both the electrolytic cell and the carbon capture device, thus improving the power load output.

[0225] To verify the feasibility of the model proposed in this invention and the advantages of low-carbon economic dispatch, the unit output analysis of this invention is illustrated using scenario 5 as an example. The power balance, coal gas, and hydrogen operation results of scenario 5 are as follows: Figure 5 , Figure 6 and Figure 7 As shown.

[0226] Depend on Figure 5 As can be seen, in Scenario 4, the peak periods for wind power output are 1:00-5:00 and 22:00-24:00, while the peak period for photovoltaic power output is 10:00-14:00. The electricity generated by wind turbines, photovoltaic units, gas-steam turbines, waste heat power generation, and purchased electricity is used for electrical load, electrolytic cells, carbon capture equipment, electricity sales, and steel production. To meet load demand, the system will purchase more electricity during periods of low electricity prices. During the off-peak periods of 4:00 and 22:00, the system purchases electricity from the grid and stores the excess for use during peak periods when electricity is insufficient. The electrolytic cell utilizes surplus electricity to produce hydrogen, resulting in a significant improvement in system energy utilization compared to scenarios without considering the electrolytic cell. To reduce power consumption costs during periods of high electricity prices, the system does not purchase electricity during the peak period of 8:00-11:00. This reduces power consumption in the electric arc furnace short-process and increases power consumption in the blast furnace-converter long-process.

[0227] Due to production constraints, demand decreases at night, and industrial electricity consumption drops after 11 PM. power grid The total system load has decreased, resulting in wind curtailment where wind power generation is not being fully utilized.

[0228] Depend on Figure 6 As can be seen, in scenario 4, the blast furnace gas, coke oven gas and converter gas generated during the steel production process are used for the system's own needs. A portion of the surplus gas flows into the gas boiler and then generates steam for the system's power supply. Some of the coke oven gas is used to produce hydrogen. The other portion is stored in gas tanks to buffer the system's gas supply and demand.

[0229] Depend on Figure 7 As can be seen, in scenario 4, electrolyzed water, coke oven gas and purchased hydrogen together provide hydrogen energy for blast furnace production, replacing some coal, reducing CO2 emissions and lowering energy purchase costs.

[0230] Based on a set of typical scenarios and their probabilities, the Pareto front between total cost and energy utilization rate under different constraints in scenario 5 is obtained using an optimized scheduling model for the integrated energy system of a steel industrial park. Figure 8 As shown.

[0231] Figure 9 To illustrate the relationship between total cost and energy utilization rate under different constraints in Scenario 5, and to determine a solution that balances cost and energy utilization rate, this invention employs Pareto optimality to address the problem. As shown in the graph, as energy utilization rate increases, total cost first increases slowly and then increases dramatically. Calculations indicate that the point with the greatest curvature in this data set is point P in the graph. After point P, the increase in cost is significantly greater than the increase in energy utilization rate. Continuing to optimize in one objective direction (further increasing energy utilization rate) will lead to a significant increase in total cost. Therefore, the solution corresponding to the "inflection point" P (the point of abrupt change in slope) is chosen as the optimal solution. Electrolysis of water and coke oven gas jointly provide hydrogen energy for blast furnace production, replacing some coal, reducing CO2 emissions, and lowering energy purchase costs.

[0232] In scenario 5, the output of the metallurgical process in each scheduling cycle is as follows: Figure 9 Show:

[0233] In scenario 5, the long-process steel production maintains a relatively stable output, while the short-process steel production experiences reduced output due to electricity price fluctuations. Electric arc furnaces (EAFs) are energy-intensive and costly, resulting in significantly lower steel production compared to long-process steelmaking. In this invention, the short-process steel production accounts for approximately 33% of the total steel output. It can be seen that although steel production fluctuations are irregular, they are still affected by electricity price volatility. During peak electricity price periods, long-process blast furnaces prioritize production to reduce electricity consumption; during off-peak electricity price periods, short-process EAFs prioritize production to lower overall costs.

[0234] 5.2 Impact Analysis of Carbon Trading Mechanism

[0235] This case study focuses on the direct impact of the carbon pricing mechanism; therefore, the objective function is simplified to minimizing a single cost, and multi-objective optimization of energy utilization is not included. Scenario 1-4 all use the ordinary carbon price trading method, and the carbon emissions are shown in Table 2 (changes in the carbon trading mechanism will affect the amount of carbon emissions, but the change is very small here, so it is ignored). The carbon trading costs are calculated based on the benchmark carbon price and tiered carbon prices, and the comparison between the carbon trading costs and total costs is shown in the table.

[0236] Table 2. Analysis of the cost impact of different carbon trading mechanisms.

[0237]

[0238] As shown in the graph, scenarios 1 and 2 have relatively high carbon emissions, both exceeding carbon allowances. Enterprises need to purchase allowances, resulting in positive carbon trading costs. Without considering carbon emission trading costs, the total system cost is the lowest, lower than the scenario considering carbon trading. Under high carbon emission conditions, tiered carbon pricing incurs more penalty costs. Therefore, the carbon trading cost under tiered pricing is higher than the benchmark carbon price, thus increasing the total system cost. Tiered carbon pricing intensifies carbon price pressure, leading to the highest total cost.

[0239] Scenario 3 and Scenario 4 show significant emission reduction effects with low carbon emissions, allowing companies to generate revenue by selling excess allowances. However, without considering carbon trading costs, the total system cost is high, exceeding that of scenarios incorporating carbon trading. Selling allowances at the standard carbon price can generate some revenue, but the tiered carbon pricing mechanism provides rewards based on negative emissions, with higher returns under the tiered pricing system.

[0240] Furthermore, under a fixed carbon price, costs and benefits are relatively stable; under a tiered carbon trading mechanism, carbon prices change with emissions, strengthening the economic constraints on carbon emissions and encouraging enterprises to reduce emissions more actively. The model proposed in this invention considers the tiered carbon pricing mechanism, where higher carbon trading revenue under tiered pricing demonstrates a stronger incentive effect. Therefore, considering a reasonable carbon trading mechanism can reduce the overall carbon emissions of the system, help strengthen emission reduction targets, and promote the transformation to a low-carbon economy.

[0241] 5.3 Sensitivity Analysis

[0242] Assuming energy efficiency remains constant and unaffected, adjusting the following parameters may significantly change the results:

[0243] Assuming energy efficiency remains constant, observe the changes in system cost, carbon emissions, and other results by adjusting the following parameters: hydrogen metallurgy ratio, carbon capture rate, and electricity price.

[0244] 5.3.1 Hydrogen metallurgy ratio

[0245] In Scenario 5, the carbon substitution ratio is 10%, and the proportion of hydrogen replacing coke will be gradually increased (10%~50%).

[0246] Table 3. Impact of Changes in Hydrogen Metallurgy Ratio on Cost

[0247]

[0248] As shown in Table 3, as the hydrogen substitution rate increased from 10% to 50%, not only were cost savings achieved, but energy efficiency also saw a slight improvement. When the hydrogen substitution rate increased from 10% to 50%, energy procurement costs gradually decreased from approximately RMB 115 million to RMB 112 million. This indicates that replacing coke with hydrogen not only reduced coal consumption and energy expenditure but also significantly improved the efficiency of hydrogen utilization.

[0249] The total cost decreased from RMB 11,701,702.23 to RMB 11,266,833.67, a decrease of approximately 3.72%. The energy cost decreased by approximately 2.9%, which is basically consistent with the change in the total cost. This indicates that the energy cost is the key variable in the total cost. Further increasing the proportion of hydrogen can not only reduce costs but also significantly improve carbon emission reduction.

[0250] Currently, most hydrometallurgical technologies are still in the research and development stage, and many processes require more advanced technologies and equipment. If the proportion of hydrogen used continues to increase, considering the costs of hydrogen production, storage, and transportation, the overall cost may rise. Furthermore, increased system energy consumption may also affect overall energy efficiency. Therefore, companies may consider gradually increasing the application of hydrometallurgical technologies in the future.

[0251] 5.3.2 Carbon capture rate

[0252] The carbon cost and total cost changes for Scenario 5 as the CO2 capture ratio changes from 60% to 90%.

[0253] Table 4. Cost Changes in Scenario 5 When Carbon Capture Rate Changes

[0254]

[0255] As shown in Table 4, carbon costs are lowest at high capture rates (90%), but total costs are slightly higher; at low capture rates (60%), total costs are lowest, but carbon costs are significantly higher. As carbon capture rates increase, the amount of carbon dioxide captured increases, making carbon trading more profitable. Costs decrease with increasing capture rates, while energy utilization increases slightly due to the improved capture rate. When the capture rate increases from 60% to 90%, carbon costs decrease by approximately 4.85%. Inefficient carbon capture can lead to insufficient carbon allowances, requiring the purchase of additional allowances, thus increasing costs. For every 10% increase in capture rate, carbon costs decrease by an average of approximately RMB 2,600. Total costs increase slightly with increasing capture rates, by only 0.23%, with an average increase of approximately RMB 8,900 for every 10% increase in capture rate (linear fitting slope). The higher the capture rate, the lower the marginal benefit of carbon cost reduction.

[0256] The carbon capture rate used in this invention is 0.9, thus proving the rationality and superiority of the technology proposed in this invention.

[0257] 5.3.3 Electricity Price Fluctuations

[0258] The original scenario 5 uses a time-sharing billing mechanism, as shown in Table 5. Using the original scenario as a baseline, the system optimization scheduling results for scenario 5 are obtained by applying normal billing and time-sharing billing fluctuations of -20% and +20%, respectively, as shown in Table 6.

[0259] Table 5 TOU Electricity Price

[0260]

[0261] Table 6 shows the changes in system operation results when the rate changes.

[0262]

[0263] Table 6 shows the trend of the impact of electricity prices on the system:

[0264] Compared to time-of-use pricing, the industrial park adopts a conventional low electricity price (200 yuan / MWh). Prioritizing electricity procurement has driven the use of electric furnaces and electrolytic cells, resulting in a 5.4% increase in electricity purchases. With the increase in electricity purchases and the expansion of short-process production, concurrent long-process production has seen rising carbon costs due to limited scrap steel supply. Energy procurement costs have been reduced as electricity has replaced expensive fuel purchases. The fixed electricity price mechanism effectively avoids peak-valley price fluctuations during specific time periods, while also ensuring more stable dispatching and improved overall system efficiency. Although total costs and energy utilization show positive trends, energy waste remains significant.

[0265] The optimized operating results of the 400 CNY / MWh ordinary electricity price are not much different from the TOU electricity price. This is because the electricity price is close to the fluctuation range of the hourly / minute electricity price at this time. The amount of electricity purchased is reduced and replaced by high-priced fossil fuels, which increases the energy purchase cost and carbon cost.

[0266] In the high electricity price range (0.6-0.8 CNY / MWh), the lack of price incentives in conventional electricity pricing led the park to reduce non-essential electricity consumption, resulting in a decrease in purchased electricity volume. The increase in energy procurement costs was mainly due to increased coal consumption. To avoid paying the full peak electricity price, the purchase of raw materials also increased accordingly. Excessive grid purchase costs prompted a spontaneous adjustment in the energy use structure. Lower curtailment costs indicate improved utilization of wind and solar energy. As electricity prices rise, the total system cost further increases. Reduced use of electric arc furnaces and equipment led to a decrease in system efficiency.

[0267] Taking into account both economic efficiency and energy efficiency, while energy utilization rate remains relatively stable, the time-of-use pricing system offers significant economic benefits. Although energy curtailment exists, its low cost indicates more optimized system dispatch and the absence of significant redundant generation. Therefore, the time-of-use pricing system is a better choice, and enterprises should fully utilize this mechanism to concentrate the operation of high-energy-consuming equipment during off-peak hours.

[0268] In summary, this invention proposes an integrated energy system model for steel industrial parks, which coordinates the operation of energy utilization (EL) and carbon capture and storage (CFS). The model is solved using a constraint method, with the objective function being to minimize economic costs (including total cost and carbon cost) and maximize energy utilization efficiency. A Pareto boundary diagram is also plotted to ultimately obtain a compromise solution that better balances total system cost and energy efficiency. Algorithm analysis results show that this model achieves cost reduction and carbon reduction goals through hydrogen-electricity-carbon synergistic optimization, while simultaneously improving energy utilization efficiency. Specific conclusions are as follows:

[0269] 1) Compared with traditional steel production, taking into account water electrolysis for hydrogen production, by-product gas for hydrogen production, Chinese Chemical Society technology, and tiered carbon trading mechanism, the system effectively improves energy utilization, reduces system carbon emissions, reduces system operating costs, and promotes the low-carbon economic operation of the system.

[0270] 2) The synergistic optimization of hydrogen production from multiple sources in the electrolytic furnace and by-product gases helps improve the flexibility of hydrogen supply. Considering the application of hydrogen energy in steel production, using hydrogen to replace traditional fossil fuels as a reducing agent reduces carbon consumption in blast furnaces, thereby improving system economy and low-carbon performance.

[0271] 3) Increase carbon capture and storage technology, which can effectively reduce the carbon emissions of the system. As the capture rate increases, the carbon emission intensity decreases, reducing carbon trading costs and enhancing the low-carbon nature of the system.

[0272] 4) Integrate the tiered carbon trading mechanism into the existing multi-objective optimization model, and guide steel mills to reduce emissions in the higher tiers through price signals, effectively reducing total costs and carbon emissions.

[0273] The specific embodiments of the present invention have been described in detail above with reference to the figures. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A model for an integrated energy system in a steel industrial park, characterized in that, It includes a steel production system, an energy system, an energy control system, and a carbon capture and storage system. The steel production system and the energy system are deeply connected through a directional link. The by-product gas and waste heat generated by the steel production system are directly connected to the energy system. The energy control system is connected to the energy system on one end to obtain power, and provides hydrogen energy to the steel production system on the other end. The carbon capture and storage system is connected to the steel production system to collect the flue gas emitted by the steel production system.

2. The integrated energy system model for a steel industrial park according to claim 1, characterized in that, The steel production system includes long-process production lines, short-process production lines, and shared processing equipment. The long-process production lines include coke ovens, sintering machines, blast furnace feed silos, blast furnaces, and converters. The short-process production lines include electric arc furnaces. The shared processing equipment is a rolling mill. In the long process, coal is fed into the coke oven via a conveyor pipe. The coke produced in the coke oven and the iron ore processed by the sintering machine are jointly transported to the blast furnace feed silos via a material conveyor belt, and then enter the blast furnace to smelt iron. The molten iron is then fed into the converter for refining into steel via a ladle conveyor track. In the short process, scrap steel is directly fed into the electric arc furnace for smelting into steel via a scrap steel conveyor belt. The molten steel from both production lines is fed into the rolling mill via a ladle conveyor track for processing into steel products. The energy system includes an energy source unit, an integrated multi-interface energy hub unit, and an energy conversion unit. The energy source unit includes a power grid, wind turbines, and photovoltaic equipment. The energy conversion unit includes a gas holder, waste heat power generation equipment, a fuel boiler, and a steam turbine. The power grid is connected to the energy hub via high-voltage transmission lines, while wind power and photovoltaic power are connected via low-voltage transmission lines. The energy hub distributes electrical energy to the waste heat power generation equipment, electrolyzer, fuel boiler, and steam turbine via four independent transmission cables. The gas holder supplies gas to the fuel boiler via branch gas pipelines. The steam generated by the fuel boiler is connected to the steam turbine via steam pipelines. The steam turbine and waste heat power generation equipment convert electrical energy and send it back to the energy hub via transmission cables, forming a closed-loop flow of electrical energy. The energy control system, as the supply end of low-carbon metallurgy, consists of an electrolyzer and a hydrogen storage tank. The energy hub supplies power to the electrolyzer through a power transmission cable. The hydrogen produced by the electrolyzer is stored in the hydrogen storage tank through a hydrogen transmission pipeline. It is then connected to the hydrogen smelting interface of the blast furnace and the hydrogen refining interface of the converter through two branch pipelines, respectively, to provide hydrogen energy in a targeted manner to realize hydrogen-containing metallurgy. As a low-carbon governance end, the carbon capture and storage system includes a carbon capture device with four independent air inlets and a carbon storage device. The flue gas emission outlets of the blast furnace, converter, fuel boiler and steam turbine are respectively connected to the corresponding air inlets of the carbon capture device through flue gas pipelines. The captured CO2 is connected to the carbon storage device through a dedicated CO2 conveying pipeline to achieve storage. Meanwhile, the coke oven gas, blast furnace gas, and converter gas generated by the coke oven, blast furnace, converter, and electric arc furnace are connected to the gas holder through independent gas transmission pipelines, and the waste heat generated by the blast furnace, converter, and rolling mill is connected to the waste heat power generation equipment through dedicated waste heat recovery pipelines.

3. A low-carbon economic dispatching method applicable to the steel industry, characterized in that: Includes the following steps: Step 1: Construct an integrated energy system model for the steel industrial park. First, construct the basic structure of the steel industrial park IES containing hydrogen metallurgy and carbon capture equipment, and then analyze the internal structure of the steel production system and energy system in detail. Step 2: Taking into account economic, energy efficiency and carbon efficiency factors, construct the corresponding objective function with the optimization objectives of minimizing the total daily production cost and maximizing the energy utilization rate of the integrated energy system of the steel industrial park; Step 3: Considering the operational constraints of the integrated energy system (IES) of the steel industrial park, it is necessary to meet the real-time balance of electricity, heat, hydrogen and coal gas energy, and the energy supply should be equal to or greater than the energy demand. Step 4: Select - Constraint method as a model solution method for solving the optimization problem of integrated energy system in steel industrial parks; Step 5: Select the research object and explore the impact of hydrogen-coated carbon capture synergistic operation on the low-carbon economic operation of the integrated energy system of the steel industrial park. Optimize the scheduling with a 24-hour cycle and set up a case study for verification and analysis. Step 6: Assuming energy utilization remains constant, if the following parameters are adjusted: hydrogen metallurgy ratio, carbon capture rate, and electricity price, observe the changes in cost, carbon emissions, and energy utilization of the integrated energy system in the steel industrial park.

4. The low-carbon economic dispatching method applicable to the steel industry according to claim 3, characterized in that: In Step 1, the basic structure of the IES (Environmental Engineering System) for a steel industrial park containing hydrogen metallurgy and carbon capture equipment is constructed. This basic structure is considered an organic coupling of the steel production system and the energy system. The steel production system, energy system, and energy and carbon efficiency are analyzed. Multiple energy sources, including electricity, heat, hydrogen, and by-product coal gas, are integrated to form a multi-energy complementary and highly efficient utilization system. The CO2 emissions from the carbon capture system and the carbon emission model of the IES for the steel industrial park are as follows: ； In the formula: Calculate the actual carbon emissions at time t; Let t be the total carbon emissions generated by the integrated energy system of the steel industrial park at time t; Let t be the amount of carbon emissions captured by the carbon capture device at time t; Let be the electricity consumption at time t; Let be the amount of fuel consumed at time t; Let t be the energy consumption of the carbon capture equipment at time t. Let t be the output of the gas turbine; Let t be the carbon emissions generated during the hydrogen production process from coke oven gas at time t; Let g be the demand-side consumption of the g-th energy type at time t; Let g be the feedback quantity of the g-th type of energy at time t; , , , , These are the carbon dioxide emission coefficients for electricity, fuel, carbon capture equipment, gas turbines, and Class G energy, respectively. For carbon capture efficiency; The tiered carbon trading mechanism divides carbon emission allowances into multiple ranges. Excess allowances are purchased at tiered prices; the higher the emissions, the higher the carbon price. The tiered carbon trading cost calculation model is as follows: ； In the formula: Let t be the tiered carbon trading cost of the integrated energy system in the steel industrial park at time t; p is the benchmark price for carbon trading, in yuan / t; and L is the unit carbon trading range. Let t represent the carbon emissions of the system participating in carbon trading, and a and b represent the reward coefficient and penalty coefficient for carbon trading, respectively.

5. The low-carbon economic dispatching method applicable to the steel industry according to claim 3, characterized in that: In Step 2, energy supply is optimized by introducing hydrogen production technologies such as water electrolysis and coke oven gas, and carbon capture and geological storage technologies are used to achieve end-of-pipe emission reduction. To address the cost increase caused by the short process of electric furnace, an optimization model is constructed with the goal of minimizing the total daily production cost of the system and maximizing energy utilization, taking into account the balance between economy, energy efficiency and carbon efficiency.

6. The low-carbon economic dispatching method applicable to the steel industry according to claim 3, characterized in that: In Step 3, the real-time energy balance constraints are satisfied, including power balance constraints, hydrogen balance constraints, and energy equipment operation constraints. The energy equipment operation constraints include the inability of charging and discharging in the energy storage equipment to occur simultaneously, the equality of stored energy at the initial moment and the end of the scheduling cycle, and carbon capture power consumption constraints.

7. The low-carbon economic dispatching method applicable to the steel industry according to claim 3, characterized in that: In Step 4, using - The constraint method is used to solve the optimization problem of the integrated energy system in the steel industrial park, and a low-carbon economic dispatch model considering the coordinated operation of hydrogen metallurgy and carbon capture is constructed. First, the Pareto solution set is obtained, and finally, the Knee Point inflection point method is used to select the optimal solution. By calculating the curvature of the Pareto solution, the point with the largest curvature is selected, and the "inflection point" is found on the Pareto front, that is, the point where the rate of change of the target improvement is the largest. ； In the formula: The objective function is... For the objective function The allowed upper limit, the range of values ​​is: From the minimum to the maximum value; n is the number of objective functions; m is the total number of objective functions; The first objective function is... - The priority optimization objective in the constraint method; First, transform the energy utilization rate target into - Constraints: First, retain the economic objective as the primary objective, which is to minimize unused energy and maximize energy utilization. Second, determine the discretization interval by calculating the maximum and minimum energy utilization rates. Specific steps: Optimize the primary objective separately to obtain the minimum cost. When the cost is optimal, the secondary objective, namely the utilization of unused energy, is optimized to obtain the maximum value of unused energy. At this point, the energy utilization rate is the worst. Directly optimize the secondary objective to obtain its minimum value, which represents the highest energy utilization rate. Then, divide the above interval into N equal parts. Values, gradually adjust the constraint boundaries Solve the single-objective optimization problem, use the MILP solver to output the optimal cost and corresponding scheduling scheme, and finally collect all... point, In - In the constraint method, when optimizing the principal objective alone, the minimum cost is plotted as an economic cost-energy utilization rate Pareto curve, and a compromise solution is selected from the Pareto frontier.

8. The low-carbon economic dispatching method applicable to the steel industry according to claim 3, characterized in that: In Step 5, the example is set up with a daily crude steel output of 8640 tons for a steel plant in a steel industrial park in Yunnan Province, of which 5760 tons are produced through the long-process production and 2880 tons through the short-process production. Based on its historical data, five different scenarios are set up to analyze the production costs and carbon emissions in different scenarios. 1) Scenario 1: A steel industrial park that integrates blast furnace long-process and electric arc furnace short-process production; 2) Scenario 2: Based on Scenario 1, introduce electrolysis equipment and consider hydrogen production by electrolysis of water and hydrogen production from coke oven gas; 3) Scenario 3: Based on Scenario 1, carbon capture and storage technology is introduced to capture carbon after combustion, transport it and store it underground; 4) Scenario 4: Based on Scenario 1, construct an integrated energy system for the steel industrial park that integrates water electrolysis, coke oven gas hydrogen production, and carbon capture. 5) Scenario 5: Based on Scenario 1, a comprehensive energy system for a steel industrial park is constructed, integrating water electrolysis, coke oven gas hydrogen production, and carbon capture. Considering a tiered carbon trading mechanism, the power balance of Scenario 1-4 is compared. The power balance, gas, and hydrogen operation results of the integrated energy system for the steel industrial park, integrating water electrolysis, coke oven gas hydrogen production, and carbon capture, and considering a tiered carbon trading mechanism, are analyzed. This verifies the feasibility of the low-carbon economic dispatch model considering the integrated operation of hydrogen metallurgy and carbon capture, and the advantages of low-carbon economic dispatch. Using Pareto optimality to balance cost and energy utilization, the solution corresponding to the "inflection point" P is selected as the optimal solution. Water electrolysis and coke oven gas jointly provide hydrogen energy for blast furnace production, replacing some coal, reducing CO2 emissions, and lowering energy purchase costs. By analyzing the output of the metallurgical process in each dispatch cycle, the impact of different carbon trading mechanisms on costs is compared. The optimized dispatch model for the integrated energy system of the steel industrial park prioritizes the tiered carbon pricing mechanism, and the higher carbon trading revenue under the tiered carbon pricing mechanism demonstrates a stronger incentive effect.

9. The low-carbon economic dispatching method applicable to the steel industry according to claim 3, characterized in that: In Step 6, the proportion of hydrogen replacing coke is gradually increased by 10% to 50%, and the impact of changes in the hydrogen metallurgy ratio on costs is compared. The changes in energy utilization, carbon cost, and total cost when the proportion of CO2 capture changes from 60% to 90% are analyzed. The original scenario is used as a benchmark, and the system operation results are obtained by using ordinary billing and time-of-use billing with fluctuations of -20% and +20% respectively.

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