Methane and methanol co-production capacity configuration method coupling green electricity hydrogen production and carbon capture technology

Abstract

The invention discloses a methane-methanol co-production capacity configuration method coupling green electricity hydrogen production and carbon capture technology, which comprises the following steps: obtaining load data and meteorological data in an energy supply area, and obtaining a load curve, an illumination curve and a wind speed curve of the energy supply area through a clustering method; establishing a steady-state model of the equipment according to the operation mechanism of the equipment in the integrated energy system and the coupling relation between the equipment; establishing a mixed integer linear programming model according to the coupling relationship and the steady-state model, and solving the mixed integer linear programming model; and the investment cost of the electrolytic cell is changed, a CPLEX solver is called to solve the mixed integer linear programming model, and capacity configuration optimization results of the methanation equipment and the methanation equipment are obtained. According to the method provided by the invention, a configuration scheme and a scheduling plan of the comprehensive energy system can be scientifically planned, and the capacity of methanation equipment and methanation equipment can be determined in an auxiliary manner on the basis of sensitivity analysis of the investment cost of the electrolytic cell.

Description

Technical Field

[0001] The present invention relates to the field of energy system planning, and in particular to a methane-methanol co-production capacity configuration method coupling green electricity hydrogen production and carbon capture technology. Background Art

[0002] With the acceleration of industrialization worldwide, energy demand has increased year by year, and the environmental problems caused by thermal power generation have become increasingly severe. Carbon dioxide emissions remain high, causing irreversible impacts on the environment where humans live. It is imperative to reduce industrial carbon dioxide emissions. At the same time, the reduction in the cost of renewable energy power generation has stimulated the development of renewable energy in the direction of scale. However, renewable energy represented by wind turbines and photovoltaics has a high degree of uncertainty and randomness when outputting. In order to better absorb renewable energy power generation under fluctuating conditions, the previous integrated energy system would configure energy storage devices such as batteries and heat storage tanks to store energy. But a question that follows is how large a scale of energy storage equipment should be configured to meet the renewable energy consumption under fluctuating output conditions. The larger the scale of the energy storage system, the more electricity it can absorb, and the investment cost of the system will also increase significantly. How to find a balance between the investment cost of the energy storage system and the amount of energy consumption has become the key to the configuration of the integrated energy system.

[0003] An integrated energy system is a technology that optimizes and integrates multiple energy resources to improve energy efficiency, reduce environmental impact, and enhance energy supply reliability. It has broad applications in optimizing regional energy supply, reducing fossil fuel input, and achieving efficient energy utilization. However, the current integrated energy system does not fully consider more abundant forms of energy storage in the design of the energy storage subsystem, and the energy storage potential of the system still has room for development. In terms of the system configuration optimization plan, there is also a lack of reasonable planning methods to scientifically size the equipment in the system, which limits the advantages of the integrated energy system. Summary of the invention

[0004] Purpose of the invention: In view of the above problems, the purpose of the present invention is to provide a methane-methanol co-production capacity configuration method that couples green electricity hydrogen production and carbon capture technology.

[0005] Technical solution: A methane-methanol co-production capacity configuration method for coupling green electricity hydrogen production and carbon capture technology of the present invention is applied to a comprehensive energy system. The capacity configuration method includes:

[0006] Obtain load data and meteorological data in the energy supply area, and obtain the load curve, light curve and wind speed curve of the energy supply area through clustering method;

[0007] According to the operation mechanism of each device in the integrated energy system and the coupling relationship between them, the steady-state model of the equipment is established;

[0008] According to the coupling relationship and the steady-state model, a mixed integer linear programming model is established and solved;

[0009] By changing the investment cost of the electrolyzer, the CPLEX solver is called to solve the mixed integer linear programming model to obtain the capacity configuration optimization results of the methanation equipment and methanolization equipment.

[0010] Furthermore, the integrated energy system includes the energy supply side, the energy conversion side, and the user demand side;

[0011] The energy supply side includes thermal power units, wind turbines and photovoltaic power generation units;

[0012] The energy conversion side includes carbon capture systems, electrolyzers, carbon storage tanks, hydrogen storage tanks, methanolization equipment and methanization equipment;

[0013] The demand side includes the user side and the chemical market side;

[0014] The input end of the carbon capture system is respectively connected to the thermal power unit, wind turbine and photovoltaic power unit, the output end of the carbon capture system is connected to the input end of the carbon storage tank, and the output end of the carbon storage tank is respectively connected to the input end of the methanation equipment and the input end of the methanolation equipment; the input end of the electrolyzer is respectively connected to the thermal power unit, wind turbine and photovoltaic power unit, the output end of the electrolyzer is connected to the input end of the hydrogen storage tank, and the output end of the hydrogen storage tank is respectively connected to the input end of the methanolation equipment and the input end of the methanation equipment, the input end of the methanolation equipment and the input end of the methanation equipment are also respectively connected to the thermal power unit, wind turbine and photovoltaic power unit, the output end of the methanolation equipment and the output end of the methanation equipment are connected to the chemical market end; the user end is respectively connected to the thermal power unit, wind turbine and photovoltaic power unit.

[0015] Furthermore, establishing a steady-state model of the equipment includes:

[0016] (1) Establish the output model of photovoltaic generator set, the expression is:

[0017]

[0018] In the formula, is the output power of the photovoltaic generator set, is the rated capacity of the photovoltaic generator set, η PV is the photovoltaic efficiency; η represents the conversion coefficient between the photovoltaic output power per unit area and its area; GHI t is the solar energy available per unit area for photovoltaic power generation at time t;

[0019] (2) Establish the output model of the wind turbine generator, expressed as:

[0020]

[0021] In the formula, E WT,t (v) is the output power of the wind turbine at wind speed v at time t; v t is the wind speed at time t, v ci is the cut-in speed of the wind turbine, v co is the cut-out speed of the wind turbine, v r is the rated wind speed of the wind turbine, E r is the rated output power of the wind turbine;

[0022] (3) Establish the power consumption model of the carbon capture system, expressed as:

[0023]

[0024] In the formula, is the CO2 emission of thermal power units, e PGU is the carbon emission intensity of thermal power units, P PGU,t is the power of the thermal power unit; is the total amount of carbon dioxide captured by the carbon capture system, η CCS for carbon capture efficiency; The amount of carbon dioxide actually captured by the carbon capture system for the power-to-green fuel process, is the amount of carbon dioxide dissipated during the capture process of the carbon capture system; P CCS,t The electricity consumption of the carbon capture system, is the electricity consumption per unit of carbon capture;

[0025] (4) Establish the power consumption model of the electrolytic cell, expressed as:

[0026]

[0027] Where P EL,t is the power of the electrolytic cell, λ H2 is the power consumption coefficient of hydrogen production in the electrolyzer, is the hydrogen production of the electrolyzer;

[0028] (5) Establish the power consumption model of methanogenation equipment, expressed as:

[0029]

[0030] In the formula, is the amount of methane synthesis, is the chemical conversion coefficient of methane, is the amount of carbon dioxide used to synthesize methane; The electricity consumed to synthesize methane, is the power consumption coefficient for synthesizing methane;

[0031] (6) Establish the power consumption model of methanolization equipment, the expression is:

[0032]

[0033] In the formula, is the amount of methanol synthesized, is the chemical conversion coefficient of methanol, is the amount of carbon dioxide used to synthesize methanol; The electricity consumed for the synthesis of methanol is is the power consumption coefficient of methanol synthesis;

[0034] (7) Establish a hydrogen storage capacity model in the hydrogen storage tank, expressed as:

[0035]

[0036] In the formula, and are the volumes of hydrogen in the hydrogen storage tank at the current moment and the previous moment respectively; and They are respectively the air intake and steam extraction in the hydrogen storage tank at the last moment; is a 0-1 variable that expresses the working state of the hydrogen storage tank, 1 represents that the hydrogen storage tank is in the intake state, and 0 represents that the hydrogen storage tank is in the exhaust state;

[0037] (8) Establish a carbon dioxide storage model in the carbon storage tank, and the expression is:

[0038]

[0039] In the formula, and are the volumes of carbon dioxide in the carbon storage tank at the current moment and the previous moment respectively; and They are respectively the air intake and air extraction in the carbon storage tank at the last moment; A 0-1 variable that expresses the working state of the carbon tank. 1 represents that the carbon tank is in the intake state, and 0 represents that the carbon tank is in the extraction state.

[0040] Furthermore, in the mixed integer linear programming model, the objective function is to minimize the annualized index of the integrated energy system operation, and the expression is:

[0041] F D =min(C inv +C om +C tari +C tax )

[0042] In the formula, C invrepresents the fixed investment cost of system equipment, C om represents the fixed operating cost of the system equipment, C tari represents the acquisition cost of resources, C tax represents the carbon tax penalty cost;

[0043] Constraints include power balance constraints, material balance constraints and equipment operation constraints.

[0044] Furthermore, the fixed investment cost of system equipment C inv The expression is:

[0045]

[0046] In the formula, k is the device type, I k is the investment cost of equipment per unit capacity, E k is the capacity of the device; k is the equivalent annual cost of the equipment;

[0047] Fixed operating cost of system equipment C om The expression is:

[0048]

[0049] In the formula, ζ k It is the ratio of the investment cost of the equipment to the fixed operating cost;

[0050] Resource acquisition cost C tari The expression is:

[0051]

[0052] Where P fuel,t The amount of coal burned m fuel,t The cost factor, is the selling price of methane products, is the selling price of methanol products;

[0053] Carbon tax penalty cost C tax The expression is:

[0054]

[0055] In the formula, Carbon tax fines for CO2, The amount of carbon dioxide emitted into the atmosphere.

[0056] Furthermore, the expression of the power balance constraint is:

[0057]

[0058] In the formula, EPGU.t is the output power of the thermal power unit, E WT.t is the output power of the wind turbine, E PV.t is the output power of the photovoltaic generator set, E load.t is the electric load demand of the comprehensive energy system, E CCS.t The electrical energy consumed by the carbon capture system, E EL.t The electrical energy consumed by the electrolytic cell;

[0059] Equipment operating constraints include:

[0060] The upper and lower limits of thermal power unit output and ramp constraints, the upper and lower limits of carbon capture system power, the upper and lower limits of electrolyzer power and ramp constraints, the upper and lower limits of methane synthesis equipment output and ramp constraints, the gas storage capacity and inlet and outlet gas constraints of hydrogen storage equipment, and the gas storage capacity and inlet and outlet gas constraints of carbon dioxide storage equipment;

[0061] Among them, the upper and lower limit constraints and climbing constraints of thermal power units are expressed as:

[0062]

[0063] In the formula, is the rated power of the thermal power unit;

[0064] The upper and lower power constraints of the carbon capture system are expressed as:

[0065]

[0066] In the formula, is the rated power of the carbon capture system;

[0067] The upper and lower limits of the electrolyzer power and the climbing constraints are expressed as:

[0068]

[0069] In the formula, is the rated capacity of the electrolyzer;

[0070] The upper and lower output constraints and ramp constraints of the methane synthesis equipment are expressed as:

[0071]

[0072] In the formula, is the rated capacity of the methane synthesis equipment;

[0073] The gas storage capacity and inlet and outlet gas constraints of hydrogen storage equipment are expressed as:

[0074]

[0075] In the formula, and Respectively represent the amount of hydrogen in the hydrogen storage tank at the current moment and the previous moment, and They represent the gas intake and gas output in the hydrogen storage tank at the last moment, It is a logical variable, representing the state of the hydrogen storage tank. Its value range is only 0 and 1. 0 represents the hydrogen storage tank is out of gas, and 1 represents the hydrogen storage tank is in gas.

[0076] The gas storage capacity and inlet and outlet gas constraints of the carbon dioxide storage equipment are expressed as:

[0077]

[0078] In the formula, and Respectively represent the amount of hydrogen in the carbon storage tank at the current moment and the previous moment, and They represent the air intake and air output in the carbon storage tank at the last moment respectively; It is a logical variable that represents the state of the carbon tank. Its value range is only 0 and 1. 0 represents the carbon tank outlet, and 1 represents the carbon tank intake.

[0079] Furthermore, solving the mixed integer linear programming model includes:

[0080] The capacity of each device in the integrated energy system is taken as the decision variable. The intermediate variables, objective function and constraints that appear in the operation and scheduling process are input into the CPLEX solver to solve the mixed integer linear programming problem. The capacity of the equipment on the energy conversion side of the optimized integrated energy system and the optimized scheduling results under the working conditions are obtained.

[0081] Furthermore, by changing the investment cost of the electrolyzer, the CPLEX solver is called to solve the mixed integer linear programming model, and the capacity configuration optimization results of the methanation equipment and methanolization equipment are obtained, including:

[0082] The investment cost of the electrolyzer is adjusted up and down by 50%, and other set parameters are kept unchanged. The CPLEX solver is called again to obtain the sensitivity analysis results of the methane and methanol sales prices. Based on the sensitivity analysis results, the capacities of the methanation equipment and methanolation equipment are determined.

[0083] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0084] 1. The electrolyzer added in the present invention enriches the energy storage form of the comprehensive energy system, converts the electrical energy generated by renewable energy into the chemical energy of hydrogen, and further combines it with carbon dioxide to generate high-value green fuel, which is beneficial to the utilization of renewable energy and carbon dioxide emission reduction, promotes the consumption of renewable energy, and has the effect of energy time and space translation;

[0085] 2. The method proposed in the present invention can make scientific planning for the configuration scheme and scheduling plan of the integrated energy system, and assist in determining the capacity of the methanation equipment and methanolization equipment based on the sensitivity analysis of the electrolyzer investment cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0086] Figure 1 Flow chart of the capacity configuration method for methane methanol co-production for coupling green electricity hydrogen production and carbon capture technology;

[0087] Figure 2 It is a structural diagram of the integrated energy system;

[0088] Figure 3 Optimize flow charts for capacity configuration;

[0089] Figure 4 The load data and meteorological data curve for the energy supply area in a typical week;

[0090] Figure 5 This is the result diagram of the day-ahead power optimization dispatch;

[0091] Figure 6 Results plot to aid in determining capacity of a methane / methanol plant. DETAILED DESCRIPTION

[0092] In order to make the objectives, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0093] The methane-methanol co-production capacity configuration method for coupling green electricity hydrogen production and carbon capture technology described in this embodiment is applied to a comprehensive energy system, and the flow chart is as follows Figure 1 As shown, the capacity configuration method includes:

[0094] Obtain load data and meteorological data in the energy supply area, and obtain the load curve, light curve and wind speed curve of the energy supply area through clustering method;

[0095] According to the operation mechanism of each device in the integrated energy system and the coupling relationship between them, the steady-state model of the equipment is established;

[0096] According to the coupling relationship and the steady-state model, a mixed integer linear programming model is established and solved;

[0097] By changing the investment cost of the electrolyzer, the CPLEX solver is called to solve the mixed integer linear programming model to obtain the capacity configuration optimization results of the methanation equipment and methanolization equipment.

[0098] Furthermore, if Figure 2 As shown, the integrated energy system includes the energy supply side, energy conversion side and user demand side;

[0099] The energy supply side includes thermal power generation unit 1, wind power generator 2 and photovoltaic power generation unit 3;

[0100] The energy conversion side includes a carbon capture system 4, an electrolyzer 5, a carbon storage tank 6, a hydrogen storage tank 9, a methanolization device 8 and a methanation device 7;

[0101] The demand side includes the user side 10 and the chemical market side 11;

[0102] The input end of the carbon capture system 4 is respectively connected to the thermal power unit 1, the wind turbine 2 and the photovoltaic power generation unit 3, the output end of the carbon capture system 4 is connected to the input end of the carbon storage tank 6, and the output end of the carbon storage tank 6 is respectively connected to the input end of the methanation device 7 and the input end of the methanolation device 8; the input end of the electrolyzer 5 is respectively connected to the thermal power unit 1, the wind turbine 2 and the photovoltaic power generation unit 3, the output end of the electrolyzer 5 is connected to the input end of the hydrogen storage tank 9, and the output end of the hydrogen storage tank 9 is respectively connected to the input end of the methanolation device 8 and the input end of the methanation device 7, the input end of the methanolation device 8 and the input end of the methanation device 7 are also respectively connected to the thermal power unit 1, the wind turbine 2 and the photovoltaic power generation unit 3, the output end of the methanolation device 8 and the output end of the methanation device 7 are connected to the chemical market end 11; the user end 10 is respectively connected to the thermal power unit 1, the wind turbine 2 and the photovoltaic power generation unit 3.

[0103] On the energy supply side of the integrated energy system, thermal power unit 1, wind turbine 2 and photovoltaic power generation unit 3 provide the system with a source of electricity, giving priority to meeting the electricity load demand at the user end, and then selling the excess electricity to the user. The carbon capture system 4 captures the CO2 emitted by the thermal power unit 1, and sends the CO2 to the carbon storage tank 6 for storage for subsequent scheduling. The electrolyzer 5 generates H2 through water electrolysis technology, and sends the H2 to the hydrogen storage tank 9 for storage for subsequent scheduling. The methanation equipment 7 and the methanolization equipment 8 consume part of the energy to call the CO2 in the carbon storage tank and the H2 in the hydrogen storage tank, and synthesize methane and methanol in the methanation equipment 7 and the methanolization equipment 8 respectively, so as to achieve carbon emission reduction and resource utilization, and sell them to the chemical market to obtain economic benefits. The hydrogen storage tank 9 and the carbon storage tank 6 store the excess H2 and CO2 generated during the peak periods of photovoltaic power output and wind power generation output, and are used to maintain the economic benefits of producing methane and methanol during the low periods of photovoltaic power output and wind power generation output, thereby realizing the energy storage and time-space translation functions.

[0104] Furthermore, establishing a steady-state model of the equipment includes:

[0105] (1) Establish the output model of photovoltaic generator set, the expression is:

[0106]

[0107] In the formula, is the output power of the photovoltaic generator set, is the rated capacity of the photovoltaic generator set, η PV is the photovoltaic efficiency; η represents the conversion coefficient between the photovoltaic output power per unit area and its area; GHI t is the solar energy available per unit area for photovoltaic power generation at time t;

[0108] (2) Establish the output model of the wind turbine generator, expressed as:

[0109]

[0110] In the formula, E WT,t (v) is the output power of the wind turbine at wind speed v at time t; v t is the wind speed at time t, v ci is the cut-in speed of the wind turbine, v co is the cut-out speed of the wind turbine, v r is the rated wind speed of the wind turbine, E r is the rated output power of the wind turbine;

[0111] (3) Establish the power consumption model of the carbon capture system, expressed as:

[0112]

[0113]

[0114] In the formula, is the CO2 emission of thermal power units, e PGU is the carbon emission intensity of thermal power units, P PGU,t is the power of the thermal power unit; is the total amount of carbon dioxide captured by the carbon capture system, η CCS for carbon capture efficiency; The amount of carbon dioxide actually captured by the carbon capture system for the power-to-green fuel process, is the amount of carbon dioxide dissipated during the capture process of the carbon capture system; P CCS,t The electricity consumption of the carbon capture system, is the electricity consumption per unit of carbon capture;

[0115] (4) Establish the power consumption model of the electrolytic cell, expressed as:

[0116]

[0117] Where P EL,t is the power of the electrolyzer, is the power consumption coefficient of hydrogen production in the electrolyzer, is the hydrogen production of the electrolyzer;

[0118] (5) Establish the power consumption model of methanogenation equipment, expressed as:

[0119]

[0120] In the formula, is the amount of methane synthesis, is the chemical conversion coefficient of methane, is the amount of carbon dioxide used to synthesize methane; The electricity consumed to synthesize methane, is the power consumption coefficient for synthesizing methane;

[0121] (6) Establish the power consumption model of methanolization equipment, the expression is:

[0122]

[0123] In the formula, is the amount of methanol synthesized, is the chemical conversion coefficient of methanol, is the amount of carbon dioxide used to synthesize methanol; The electricity consumed for the synthesis of methanol is is the power consumption coefficient of methanol synthesis;

[0124] (7) Establish a hydrogen storage capacity model in the hydrogen storage tank, expressed as:

[0125]

[0126] In the formula, and are the volumes of hydrogen in the hydrogen storage tank at the current moment and the previous moment respectively; and They are respectively the air intake and steam extraction in the hydrogen storage tank at the last moment; is a 0-1 variable that expresses the working state of the hydrogen storage tank, 1 represents that the hydrogen storage tank is in the intake state, and 0 represents that the hydrogen storage tank is in the exhaust state;

[0127] (8) Establish a carbon dioxide storage model in the carbon storage tank, and the expression is:

[0128]

[0129] In the formula, and are the volumes of carbon dioxide in the carbon storage tank at the current moment and the previous moment respectively; and They are respectively the air intake and air extraction in the carbon storage tank at the last moment; A 0-1 variable that expresses the working state of the carbon tank. 1 represents that the carbon tank is in the intake state, and 0 represents that the carbon tank is in the extraction state.

[0130] In the mixed integer linear programming model, the objective function is to minimize the annualized index of the integrated energy system operation, and the expression is:

[0131] F D =min(C inv +C om +C tari +C tax )

[0132] In the formula, C inv represents the fixed investment cost of system equipment, C om represents the fixed operating cost of the system equipment, C tari represents the acquisition cost of resources, C tax represents the carbon tax penalty cost;

[0133] Among them, the fixed investment cost of system equipment is C inv is the investment cost of purchasing photovoltaic panels, wind turbines, carbon capture systems, methanation equipment, methanolization equipment, electrolyzers, hydrogen storage tanks, carbon storage tanks and other equipment, expressed as:

[0134]

[0135] In the formula, k is the device type, I k is the investment cost of equipment per unit capacity, E k is the capacity of the device; k is the equivalent annual cost of the equipment, expressed as:

[0136]

[0137] In the formula, n is the useful life of the equipment and i is the interest.

[0138] Fixed operating cost of system equipment C om The operating and maintenance costs of photovoltaic panels, wind turbines, carbon capture systems, methanation equipment, methanolization equipment, electrolyzers, hydrogen storage tanks, carbon storage tanks and other equipment during operation are expressed as follows:

[0139]

[0140] In the formula, ζk It is the ratio of the investment cost of the equipment to the fixed operating cost;

[0141] Resource acquisition cost C tari The expression is:

[0142]

[0143] Where P fuel,t The amount of coal burned m fuel,t The cost factor, is the selling price of methane products, is the selling price of methanol products;

[0144] Carbon tax penalty cost C tax The expression is:

[0145]

[0146] In the formula, Carbon tax fines for CO2, is the amount of carbon dioxide emitted into the atmosphere;

[0147] In the mixed integer linear programming model, the constraints include power balance constraints, material balance constraints, and equipment operation constraints. The expression of the power balance constraint is:

[0148]

[0149] In the formula, E PGU.t is the output power of the thermal power unit, E WT.t is the output power of the wind turbine, E PV.t is the output power of the photovoltaic generator set, E load.t is the electricity load demand of the integrated energy system IES, E CCS.t The electrical energy consumed by the carbon capture system, E EL.t The electrical energy consumed by the electrolytic cell.

[0150] The material balance constraint means that the gas in and out of the hydrogen storage tank and the carbon storage tank and the consumed gas remain conserved;

[0151] The gas storage capacity and inlet and outlet gas constraints of hydrogen storage equipment are expressed as:

[0152]

[0153] In the formula, and Respectively represent the amount of hydrogen in the hydrogen storage tank at the current moment and the previous moment; and They represent the gas intake and gas output in the hydrogen storage tank at the last moment respectively; It is a logical variable, representing the state of the hydrogen storage tank. Its value range is only 0 and 1. 0 represents the hydrogen storage tank is out of gas, and 1 represents the hydrogen storage tank is in gas.

[0154] The gas storage capacity and inlet and outlet gas constraints of the carbon dioxide storage equipment are expressed as:

[0155]

[0156] In the formula, and Respectively represent the amount of hydrogen in the carbon storage tank at the current moment and the previous moment; and They represent the air intake and air output in the carbon storage tank at the last moment respectively; It is a logical variable that represents the state of the carbon tank. Its value range is only 0 and 1. 0 represents the carbon tank outlet, and 1 represents the carbon tank intake.

[0157] Equipment operating constraints include:

[0158] The upper and lower limits of thermal power unit output and ramp constraints, the upper and lower limits of carbon capture system power, the upper and lower limits of electrolyzer power and ramp constraints, the upper and lower limits of methane synthesis equipment output and ramp constraints, the gas storage capacity and inlet and outlet gas constraints of hydrogen storage equipment, and the gas storage capacity and inlet and outlet gas constraints of carbon dioxide storage equipment;

[0159] Among them, the upper and lower limit constraints and climbing constraints of thermal power units are expressed as:

[0160]

[0161] In the formula, is the rated power of the thermal power unit;

[0162] The upper and lower power constraints of the carbon capture system are expressed as:

[0163]

[0164] In the formula, is the rated power of the carbon capture system;

[0165] The upper and lower limits of the electrolyzer power and the climbing constraints are expressed as:

[0166]

[0167] In the formula, is the rated capacity of the electrolyzer;

[0168] The upper and lower output constraints and ramp constraints of the methane synthesis equipment are expressed as:

[0169]

[0170] In the formula, is the rated capacity of the methane synthesis equipment;

[0171] The gas storage capacity and inlet and outlet gas constraints of hydrogen storage equipment are expressed as:

[0172]

[0173] In the formula, and Respectively represent the amount of hydrogen in the hydrogen storage tank at the current moment and the previous moment; and They represent the gas intake and gas output in the hydrogen storage tank at the last moment respectively; It is a logical variable that represents the status of the hydrogen storage tank. Its value range is only 0 and 1. 0 represents the hydrogen storage tank is out of gas, and 1 represents the hydrogen storage tank is in of gas.

[0174] The gas storage capacity and inlet and outlet gas constraints of the carbon dioxide storage equipment are expressed as:

[0175]

[0176] In the formula, and Respectively represent the amount of hydrogen in the carbon storage tank at the current moment and the previous moment; and They represent the air intake and air output in the carbon storage tank at the last moment respectively; It is a logical variable that represents the state of the carbon tank. Its value range is only 0 and 1. 0 represents the carbon tank outlet, and 1 represents the carbon tank intake.

[0177] Solving a mixed integer linear programming model involves:

[0178] The capacity of each device in the integrated energy system is taken as the decision variable. The intermediate variables, objective function and constraints that appear in the operation and scheduling process are input into the CPLEX solver to solve the mixed integer linear programming problem. The capacity of the equipment on the energy conversion side of the optimized integrated energy system and the optimized scheduling results under the working conditions are obtained.

[0179] When solving the mixed integer linear programming model, the cost of the current electrolyzer investment equipment is fixed and used as the benchmark value. Then the decision variables in the integrated energy system are determined, that is, the capacity of all equipment that needs to be configured in the system, and the decision variables and intermediate variables are defined using the YALMIP toolbox. Based on the coupling relationship and stability model between energies, the equality and inequality constraints of the planning problem are established. Considering that the carbon storage tank and the hydrogen storage tank have two states of gas intake and gas consumption, in the process of defining the intermediate variables, 0-1 logical variables are set to express the state of the gas storage tank, and a logical relationship that conforms to the material balance in the gas storage tank is established to determine the feasible domain of the mixed integer linear programming. Based on the economic parameters in the energy market, the lowest annualized index of system operation is used as the objective function, and it is input into the CPLEX solver to solve the mixed integer linear programming problem. The solution idea is to use the exhaustive method for 0-1 logical variables, divide the planning problem into N linear programming problems, further compare the objective function among the N optimal solutions, and obtain the result of the overall mixed integer linear programming. After the capacity of the equipment in the system is determined, the operating boundaries of the equipment are determined. On the basis of determining the operating boundaries of the equipment, the output of each device is constrained, and the intermediate variables in the optimization process are determined through the global optimization of the solver.

[0180] The economic parameters in the energy market include the investment cost of wind turbines, the investment cost of photovoltaic panels, the investment cost of electrolyzers, the investment cost of methanation equipment, the investment cost of methanolation equipment, the investment cost of hydrogen storage tanks, the investment cost of carbon storage tanks, time-of-use electricity prices in the region, the market price of methane, the market price of methanol, the selling price of coal, and the carbon tax penalty price.

[0181] The set parameters include: equipment capacity of existing thermal power units, carbon dioxide emission intensity of thermal power units, relationship curve between coal consumption rate and load ratio of thermal power units, cut-in speed, rated speed, cut-out speed of wind turbines, power consumption coefficient of electrolyzer, maximum capture efficiency of carbon capture system, power consumption coefficient of capture of carbon capture system, power consumption coefficient of synthetic methane, power consumption coefficient of synthetic methanol, chemical conversion factor of methane, and chemical conversion factor of methanol.

[0182] When the price of methane or methanol changes in the chemical market, the integrated energy system can adjust the chemical product structure in the system, including the output relationship between methane products and methanol products, according to the goal of minimizing the objective function, that is, whether to focus more on the production of methane or methanol. The optimal configuration results of the equipment in the integrated energy system are obtained based on the mixed integer linear programming solution. Based on the optimized configuration capacity, the dispatch instructions of each equipment in the integrated energy system are further obtained.

[0183] By changing the investment cost of the electrolyzer, the CPLEX solver is called to solve the mixed integer linear programming model, and the capacity configuration optimization results of the methanation equipment and methanolization equipment are obtained, including:

[0184] The investment cost of the electrolyzer is adjusted up and down by 50%, and other set parameters are kept unchanged. The CPLEX solver is called again to obtain the sensitivity analysis results of the methane and methanol sales prices. Based on the sensitivity analysis results, the capacities of the methanation equipment and methanolation equipment are determined.

[0185] If the process is to configure the equipment capacity, no sensitivity analysis is performed; if the change in the market price of the electrolyzer is considered, the capacity of the methanation equipment and methanolization equipment is obtained through sensitivity analysis. The flowchart for calling the CPLEX solver is as follows Figure 3 As shown, when the maximum number of iterations is reached, the call is stopped and the optimal configuration result is output.

[0186] by Figure 2 The IEPU system shown in the figure is the research object. Figure 4 A case analysis is conducted based on the total horizontal PV radiation, wind speed forecast data and historical data of power load in a typical week. Figure 4 Figure (a) shows the wind speed data in a typical week; Figure (b) shows the historical data of the power load in a typical week; Figure (c) shows the light radiation data in a typical week. The relevant technical parameters and economic parameters are listed in Table 1 and Table 2, respectively. Table 3 gives the market price and carbon tax fines of the relevant products. The capacity configuration results of the equipment are listed in Table 4, and the consumption of renewable energy is listed in Table 5.

[0187] Depend on Figure 5 It can be seen that the optimized scheduling can supply the electrolyzer with a large amount of hydrogen for methanogenesis and methanol synthesis when the photovoltaic output is large during the day. The excess hydrogen and carbon dioxide are stored in hydrogen storage tanks and carbon storage tanks respectively to maintain the methane production at night, which verifies the role of the comprehensive energy system proposed in the present invention in promoting the consumption of renewable energy, and has the effect of energy time and space translation. In addition, the thermal power unit can adjust its output according to the changes in photovoltaic output and load, that is, maintain the power lower limit operation when the photovoltaic output is large to ensure the minimum coal demand and carbon emissions; at night, in addition to meeting the load demand, the minimum power operation of the electrolyzer is guaranteed to avoid hydrogen production from thermal power, which shows that the thermal power unit has the function of maintaining the low-carbon, economical and stable operation of the system.

[0188] Figure 6 The scheduling results are obtained based on the sensitivity analysis of the electrolyzer equipment investment cost. Through the sensitivity analysis of the electrolyzer investment cost, when the electrolyzer price in the market changes, the results can assist in determining the capacity of the methanation equipment and methanolization equipment in the integrated energy system.

[0189] Table 1

[0190]

[0191]

[0192] Table 2

[0193]

[0194] Table 3

[0195]

[0196] Table 4

[0197]

[0198] Table 5

[0199]

Claims

1. A method for configuring the capacity of methane-methanol co-production by coupling green electricity hydrogen production and carbon capture technology, characterized in that: Applied to integrated energy systems, the capacity configuration method includes: Obtain load data and meteorological data in the energy supply area, and obtain the load curve, light curve and wind speed curve of the energy supply area through clustering method; According to the operation mechanism of each device in the integrated energy system and the coupling relationship between them, the steady-state model of the equipment is established; According to the coupling relationship and the steady-state model, a mixed integer linear programming model is established and solved; By changing the investment cost of the electrolyzer, the CPLEX solver is called to solve the mixed integer linear programming model to obtain the capacity configuration optimization results of the methanation equipment and methanolization equipment.

2. The method for configuring methane-methanol co-production capacity by coupling green electricity hydrogen production and carbon capture technology according to claim 1, characterized in that: The integrated energy system includes the energy supply side, energy conversion side and user demand side; The energy supply side includes thermal power units, wind turbines and photovoltaic power generation units; The energy conversion side includes carbon capture systems, electrolyzers, carbon storage tanks, hydrogen storage tanks, methanolization equipment and methanization equipment; The demand side includes the user side and the chemical market side; The input end of the carbon capture system is respectively connected to the thermal power unit, wind turbine and photovoltaic power unit, the output end of the carbon capture system is connected to the input end of the carbon storage tank, and the output end of the carbon storage tank is respectively connected to the input end of the methanation equipment and the input end of the methanolation equipment; the input end of the electrolyzer is respectively connected to the thermal power unit, wind turbine and photovoltaic power unit, the output end of the electrolyzer is connected to the input end of the hydrogen storage tank, and the output end of the hydrogen storage tank is respectively connected to the input end of the methanolation equipment and the input end of the methanation equipment, the input end of the methanolation equipment and the input end of the methanation equipment are also respectively connected to the thermal power unit, wind turbine and photovoltaic power unit, the output end of the methanolation equipment and the output end of the methanation equipment are connected to the chemical market end; the user end is respectively connected to the thermal power unit, wind turbine and photovoltaic power unit.

3. The method for configuring methane-methanol co-production capacity by coupling green electricity hydrogen production and carbon capture technology according to claim 2 is characterized in that: Establishing a steady-state model of the equipment includes: (1) Establish the output model of photovoltaic generator set, the expression is: In the formula, is the output power of the photovoltaic generator set, is the rated capacity of the photovoltaic generator set, η PV is the photovoltaic efficiency; η represents the conversion coefficient between the photovoltaic output power per unit area and its area; GHI t is the solar energy available per unit area for photovoltaic power generation at time t; (2) Establish the output model of the wind turbine generator, expressed as: In the formula, E WT,t (v) is the output power of the wind turbine at wind speed v at time t; v t is the wind speed at time t, v ci is the cut-in speed of the wind turbine, v co is the cut-out speed of the wind turbine, v r is the rated wind speed of the wind turbine, E r is the rated output power of the wind turbine; (3) Establish the power consumption model of the carbon capture system, expressed as: In the formula, is the CO2 emission of thermal power units, e PGU is the carbon emission intensity of thermal power units, P PGU,t is the power of the thermal power unit; is the total amount of carbon dioxide captured by the carbon capture system, η CCS for carbon capture efficiency; The amount of carbon dioxide actually captured by the carbon capture system for use in the electricity-to-green fuel process, is the amount of carbon dioxide dissipated during the capture process of the carbon capture system; P CCS,t The electricity consumption of the carbon capture system, is the electricity consumption per unit of carbon capture; (4) Establish the power consumption model of the electrolytic cell, expressed as: Where P EL,t is the power of the electrolyzer, is the power consumption coefficient of hydrogen production in the electrolyzer, is the hydrogen production of the electrolyzer; (5) Establish the power consumption model of methanogenation equipment, expressed as: In the formula, is the amount of methane synthesis, is the chemical conversion coefficient of methane, is the amount of carbon dioxide used to synthesize methane; The electricity consumed to synthesize methane, is the power consumption coefficient for synthesizing methane; (6) Establish the power consumption model of methanolization equipment, the expression is: In the formula, is the amount of methanol synthesized, is the chemical conversion coefficient of methanol, is the amount of carbon dioxide used to synthesize methanol; The electricity consumed for the synthesis of methanol is is the power consumption coefficient of methanol synthesis; (7) Establish a hydrogen storage capacity model in the hydrogen storage tank, expressed as: In the formula, and are the volumes of hydrogen in the hydrogen storage tank at the current moment and the previous moment respectively; and They are respectively the air intake and steam extraction in the hydrogen storage tank at the last moment; is a 0-1 variable that expresses the working state of the hydrogen storage tank, 1 represents that the hydrogen storage tank is in the intake state, and 0 represents that the hydrogen storage tank is in the exhaust state; (8) Establish a carbon dioxide storage model in the carbon storage tank, and the expression is: In the formula, and are the volumes of carbon dioxide in the carbon storage tank at the current moment and the previous moment respectively; and They are respectively the air intake and air extraction in the carbon storage tank at the last moment; A 0-1 variable that expresses the working state of the carbon tank. 1 represents that the carbon tank is in the intake state, and 0 represents that the carbon tank is in the extraction state.

4. The method for configuring methane-methanol co-production capacity by coupling green electricity hydrogen production and carbon capture technology according to claim 3 is characterized in that: In the mixed integer linear programming model, the objective function is to minimize the annualized index of the integrated energy system operation, and the expression is: F D =min(C inv +C om +C tari +C tax ) In the formula, C inv represents the fixed investment cost of system equipment, C om represents the fixed operating cost of the system equipment, C tari represents the acquisition cost of resources, C tax represents the carbon tax penalty cost; Constraints include power balance constraints, material balance constraints and equipment operation constraints.

5. The method for configuring methane-methanol co-production capacity by coupling green electricity hydrogen production and carbon capture technology according to claim 4 is characterized in that: Fixed investment cost of system equipment C inv The expression is: In the formula, k is the device type, I k is the investment cost of equipment per unit capacity, E k is the capacity of the device, σ k is the equivalent annual cost of the equipment; Fixed operating cost of system equipment C om The expression is: In the formula, ζ k It is the ratio of the investment cost of the equipment to the fixed operating cost; Resource acquisition cost C tari The expression is: Where P fuel,t The amount of coal burned m fuel,t The cost factor, is the selling price of methane products, is the selling price of methanol products; Carbon tax penalty cost C tax The expression is: In the formula, Carbon tax fines for CO2, The amount of carbon dioxide emitted into the atmosphere.

6. The method for configuring methane-methanol co-production capacity by coupling green electricity hydrogen production and carbon capture technology according to claim 5, characterized in that: The expression of the power balance constraint is: In the formula, E PGU.t is the output power of the thermal power unit, E WT.t is the output power of the wind turbine, E PV.t is the output power of the photovoltaic generator set, E load.t is the electric load demand of the comprehensive energy system, E CCS.t The electrical energy consumed by the carbon capture system, E EL.t The electrical energy consumed by the electrolytic cell; Equipment operating constraints include: The upper and lower limits of thermal power unit output and ramp constraints, the upper and lower limits of carbon capture system power, the upper and lower limits of electrolyzer power and ramp constraints, the upper and lower limits of methane synthesis equipment output and ramp constraints, the gas storage capacity and inlet and outlet gas constraints of hydrogen storage equipment, and the gas storage capacity and inlet and outlet gas constraints of carbon dioxide storage equipment; Among them, the upper and lower limit constraints and climbing constraints of thermal power units are expressed as: In the formula, is the rated power of the thermal power unit; The upper and lower power constraints of the carbon capture system are expressed as: In the formula, is the rated power of the carbon capture system; The upper and lower limits of the electrolyzer power and the climbing constraints are expressed as: In the formula, is the rated capacity of the electrolyzer; The upper and lower output constraints and ramp constraints of the methane synthesis equipment are expressed as: In the formula, is the rated capacity of the methane synthesis equipment; The gas storage capacity and inlet and outlet gas constraints of hydrogen storage equipment are expressed as: In the formula, and Respectively represent the amount of hydrogen in the hydrogen storage tank at the current moment and the previous moment, and They represent the gas intake and gas output in the hydrogen storage tank at the last moment respectively; It is a logical variable, representing the state of the hydrogen storage tank. Its value range is only 0 and 1. 0 represents the hydrogen storage tank is out of gas, and 1 represents the hydrogen storage tank is in gas. The gas storage capacity and inlet and outlet gas constraints of the carbon dioxide storage equipment are expressed as: In the formula, and Respectively represent the amount of hydrogen in the carbon storage tank at the current moment and the previous moment, and They represent the air intake and air output in the carbon storage tank at the last moment respectively; It is a logical variable that represents the state of the carbon tank. Its value range is only 0 and 1. 0 represents the exhaust of the carbon tank, and 1 represents the intake of the carbon tank.

7. The method for configuring methane-methanol co-production capacity by coupling green electricity hydrogen production and carbon capture technology according to claim 4, characterized in that: Solving a mixed integer linear programming model involves: The capacity of each device in the integrated energy system is taken as the decision variable. The intermediate variables, objective function and constraints that appear in the operation and scheduling process are input into the CPLEX solver to solve the mixed integer linear programming problem. The capacity of the equipment on the energy conversion side of the optimized integrated energy system and the optimized scheduling results under the working conditions are obtained.

8. The method for configuring methane-methanol co-production capacity by coupling green electricity hydrogen production and carbon capture technology according to claim 7, characterized in that: By changing the investment cost of the electrolyzer, the CPLEX solver is called to solve the mixed integer linear programming model, and the capacity configuration optimization results of the methanation equipment and methanolization equipment are obtained, including: The investment cost of the electrolyzer is adjusted up and down by 50%, and other set parameters are kept unchanged. The CPLEX solver is called again to obtain the sensitivity analysis results of the methane and methanol sales prices. Based on the sensitivity analysis results, the capacities of the methanation equipment and methanolation equipment are determined.

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