Pulping and papermaking integrated energy system planning method for carbon transaction and equipment transformation scene

Abstract

The invention discloses a pulping and papermaking integrated energy system planning method for a carbon transaction and equipment transformation scene. The method comprises the steps of establishing a transformation equipment model which can be applied to a pulping and papermaking industry integrated energy system; selecting the optimal comprehensive energy consumption cost of the pulping and papermaking industry comprehensive energy system as a planning target, considering energy balance and equipment operation constraint conditions, and establishing an optimal planning model of the comprehensive energy consumption cost of the pulping and papermaking industry comprehensive energy system of a carbon quota mechanism; differentiated scenes are designed from different factor angles of carbon transaction and equipment transformation scheme combination, known quantities and to-be-solved quantities in the scenes are determined, and an optimal planning model is solved to obtain a planning scheme; and analyzing and comparing parameters such as equipment planning capacity and system comprehensive energy consumption cost in different carbon transactions and equipment transformation scenes. According to the method, a pulping and papermaking industry comprehensive energy system planning model is adopted, the comprehensive energy consumption cost condition of the pulping and papermaking industry can be further calculated, and theoretical support is provided for planning and dispatching schemes of the pulping and papermaking industry.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy system planning methods, and specifically to a pulp and papermaking integrated energy system planning method for carbon trading and equipment transformation scenarios. Background Art

[0002] As an energy-intensive industry, the pulp and paper industry is characterized by high energy consumption and high carbon emissions. Carbon emission reduction and energy storage and conversion technologies have given the pulp and paper industry a certain degree of environmental sustainability. However, due to the oversimplified energy flow and equipment model problems in the comprehensive energy system planning of the pulp and paper industry, there is a gap in the comprehensive energy system planning method of the pulp and paper industry that comprehensively considers carbon emission reduction and energy storage and conversion technologies.

[0003] Carbon quota allocation and trading mechanism is of great significance to reducing carbon emissions in the comprehensive energy system of the pulp and paper industry. The carbon quota mechanism includes a mandatory compliance mechanism and a carbon emission reduction credit mechanism. Emission-controlled enterprises use the carbon quota mechanism to offset a certain proportion of carbon quota settlement to improve the ecological benefits of the enterprise while bringing economic benefits to the enterprise. However, the current carbon quota mechanism project generally focuses on issues such as mechanism optimization and market supply and demand structure, and there is a gap in the carbon quota allocation and trading mechanism model suitable for the comprehensive energy system planning of the pulp and paper industry.

[0004] In addition, traditional integrated energy system planning methods for the pulp and paper industry usually comprehensively consider constraints such as energy balance and equipment operation, analyze the equipment planning capacity and system economy of the integrated energy system for the pulp and paper industry, but ignore the comprehensive impact of the combination of equipment transformation plans and the additionality of the carbon quota mechanism on system planning. Summary of the invention

[0005] In order to solve the above technical problems, the present invention proposes a pulp and paper industry comprehensive energy system planning method for carbon trading and equipment transformation scenarios, which can guide the formulation of a comprehensive energy system planning scheme for the pulp and paper industry.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] The method for planning a comprehensive energy system for pulp and papermaking in a carbon trading and equipment transformation scenario is characterized by comprising the following steps:

[0008] S1, establish a transformation equipment model that can be applied to the integrated energy system of the pulp and paper industry, including carbon capture equipment, steam accumulator, booster pump, and electric boiler;

[0009] S2, select the optimal comprehensive energy cost of the pulp and paper industry comprehensive energy system as the planning target, consider the energy balance and equipment operation constraints, and establish the optimal planning model of the comprehensive energy cost of the pulp and paper industry comprehensive energy system with a carbon quota mechanism;

[0010] S3, design differentiated scenarios from the perspective of different factors of carbon trading and equipment transformation scheme combination, determine the known quantities and unknown quantities in each scenario, and solve the optimal planning model to obtain the planning scheme;

[0011] S4, analyze and compare the equipment planning capacity, system comprehensive energy cost, system purchased energy cost, system carbon trading cost, system operating cost, system carbon capture cost, and system equipment investment cost in different carbon trading and equipment transformation scenarios.

[0012] As a further improvement of the present invention, the transformation equipment model of the comprehensive energy system of the pulp and paper industry can be applied in step S1, wherein the carbon capture equipment model is:

[0013]

[0014] Where: is the electric power consumed by the carbon capture equipment in the tth hour, in MW / yr; W C The energy required to capture one ton of carbon dioxide for the carbon capture equipment, in MWh / t; emi c It is the carbon dioxide produced by burning one ton of standard coal, in t / tce; is the coal consumption of coal-fired cogeneration unit, alkali recovery cogeneration unit and lime kiln at hour t, in t / h; is the carbon capture coefficient of the coal-fired cogeneration unit, alkali recovery cogeneration unit and lime kiln at hour t; Maximum carbon capture coefficient of coal-fired cogeneration unit, alkali recovery cogeneration unit and lime kiln; Cap CC Plan the capacity of the carbon capture equipment in MW; Plan the maximum capacity of the carbon capture equipment in MW;

[0015] The steam accumulator model is:

[0016]

[0017] 0≤m cha,t ≤f cha,t m cha,max

[0018] 0≤m dis,t ≤f dis,t m dis,max

[0019]

[0020] f cha,t ,f dis,t ∈{0,1}

[0021] fcha,t p valve ≤p cha,t

[0022] Where: Cap SA Plan the capacity of the steam accumulator in MW; Plan the maximum capacity of the steam accumulator in MW; m cha,t m dis,t is the mass flow rate of steam charging and discharging in the steam accumulator at hour t, in t / h; f cha,t is the state characterizing quantity of the steam accumulator charging at the t hour, the value is 1 when charging, and the value is 0 when not charging; f dis,t It is the state characterizing quantity of steam accumulator steam release at the t hour, the value is 1 when steam is released, and the value is 0 when steam is not released; is the heat storage of the steam accumulator at the end of hour t, in MWh; cha,t is the steam enthalpy value of the steam accumulator at the tth hour, in MJ / t; h LP is the steam enthalpy of the steam accumulator, in MJ / t; Δt is the number of hours in the planning period; p valve is the pressure threshold of the steam accumulator charging valve, in MPa; p cha,t is the charging pressure of the steam accumulator at the tth hour, in MPa;

[0023] The booster pump model is:

[0024] p cha,min ≤p cha,t ≤p cha,max

[0025] h cha,t =c1p cha,t T cha +c2T cha +c3p cha,t +c4

[0026]

[0027] 0≤P t PU ≤Cap PU

[0028]

[0029] Where: p cha，min p cha,max It is the minimum and maximum value of the pressure of the booster pump charging the steam accumulator, in MPa; T cha is the charging temperature of the booster pump to the steam accumulator, in K; c1c2c3c4 are the quasi-linear fitting coefficients of steam enthalpy; Cap is the power consumed by the booster pump in the tth hour, in MW; PU Plan the capacity of the booster pump in MW; The maximum planned capacity of the booster pump, in MW;

[0030] The electric boiler model is:

[0031]

[0032] 0≤P t EB ≤Cap EB

[0033]

[0034] Where: Cap EB Indicates the planned capacity of the electric boiler, in MW; Indicates the maximum planned capacity of the electric boiler, in MW; is the electric power consumed by the electric boiler in hour t, in MW; is the heating power of the electric boiler at hour t, in MW; The maximum heating power of the electric boiler, in MW; is the mass flow rate of steam emitted by the electric boiler at hour t, in t / h; is the maximum mass flow rate of steam emitted by the electric boiler, in t / h; Γ represents the ratio of the maximum uphill and downhill climbing rate of the electric boiler to the maximum planned capacity; η EB It is the electric-heat conversion efficiency of the electric boiler.

[0035] As a further improvement of the present invention, the comprehensive energy cost of the comprehensive energy system of the pulp and paper industry in step S2 includes: system outsourced energy cost, system carbon trading cost, system operation cost, system carbon capture cost, and system equipment investment cost. The system outsourced energy cost model is:

[0036]

[0037] Where: E sp is the cost of purchased energy, in $; r e,t r ge,t is the electricity price and green electricity price at hour t, in $ / MWh; P e,t P ge,t is the electricity price and green electricity purchase amount at hour t, in MWh; r coal is the unit price of coal, in $ / t; r loss The penalty unit price for abandoned steam is $ / t; is the quality of discarded steam, in t;

[0038] The carbon trading mechanism model is:

[0039]

[0040]

[0041] Where: ε grid,carb is the carbon emission factor of electricity; CA t is the carbon emission of the comprehensive energy system of the pulp and paper industry at the t hour, in t; FCA t The number of carbon quotas allocated to the comprehensive energy system of the pulp and paper industry at hour t, in t; is the power output of the coal-fired cogeneration unit and the alkali recovery cogeneration unit at the tth hour, in MW; b e,coal The power supply benchmark for coal-fired units; r,coal f is the heating correction factor of the coal-fired unit; l,coal The correction factor for the cooling mode of the coal-fired unit is set to 1; f f,coal The load output factor correction factor for coal-fired units is set to 1; is the thermal output of the coal-fired cogeneration unit and the alkali recovery cogeneration unit at hour t, in MW; LHV is the mass flow rate of black liquor consumed by the alkali recovery cogeneration unit in the tth hour, in t / h; BL is the lower calorific value of black liquor, in MJ / t; b h,coal It is the heating benchmark for coal-fired units; is the carbon trading cost, in $, when the parameter is greater than 0, it is cost, and when the parameter is less than 0, it is benefit; c carb,eua c carb,cer is the unit price of carbon quota and certified voluntary emission reduction, in $ / t; EUA is the carbon quota trading volume, in t; CER is the certified voluntary emission reduction, in t; λ is the decline rate of the carbon quota baseline value; μ CER The maximum offset ratio for certified voluntary emission reductions;

[0042] The system operation cost model is:

[0043]

[0044] Where: is the unit operating cost of the coal-fired cogeneration unit, alkali recovery cogeneration unit, booster pump, carbon capture equipment, and electric boiler at hour t, in $ / MW; is the unit operating cost of the steam accumulator at hour t, in $ / MWh; is the unit operating cost of the medium-pressure and low-pressure steam bus waste heat recovery devices at hour t, in $ / MW; is the unit operating cost of the lime kiln at hour t, in $ / MW; is the steam mass flow rate recovered from the medium-pressure and low-pressure steam busbars at hour t, in t / h; h HP h MP is the enthalpy of medium-pressure and low-pressure steam at the tth hour, in MJ / t; is the heat generated by the lime kiln in hour t, in MW;

[0045] The system carbon capture cost model is:

[0046]

[0047] Where: E cc is the carbon capture cost, in $; r CC is the carbon capture unit price, in $ / t;

[0048] The system equipment investment cost model is:

[0049]

[0050] Where: E inv is the system equipment investment cost, in $; is the investment cost of carbon capture equipment, electric boiler, steam accumulator and booster pump, in $; h is the annual return on investment of the equipment; τ CC τ EB τ SA τ PU is the service life of carbon capture equipment, electric boiler, steam accumulator and booster pump, in years; I CC I EB I PU is the unit investment cost of carbon capture equipment, electric boiler, and booster pump, in $ / MW; I SA is the unit investment cost of the steam heat accumulator, in $ / MWh;

[0051] The system planning objective function is:

[0052]

[0053] Where: Obj is the comprehensive cost of the system, in $.

[0054] As a further improvement of the present invention, in step S2, the comprehensive energy system planning of the pulp and paper industry is subject to relevant conditions, including energy balance and equipment operation constraints:

[0055] 1) Energy balance constraints;

[0056] Energy balance constraints include electrical energy balance constraints, thermal energy balance constraints, and process energy supply constraints:

[0057] P t CHP +P t e +P t ge +P t AR =P t CC +P t EB +P t PU +P t eload

[0058]

[0059] Where: is the electrical load of the process at the tth hour, in MW; H2M χ M2L are the medium pressure and low pressure steam bus recovery factors, respectively; are the medium pressure and low pressure steam load mass flow rates, in t / h; δ en , n = 1, 2…, 8 is the power demand per unit product of each dispatchable process at hour t; δ hn , n=1,2…,8 is the heat energy demand per unit product of each dispatchable process in hour t; are the power load and thermal load demands of other processes except the dispatchable process in hour t, in MW;

[0060] 2) Equipment operation constraints;

[0061] Equipment operation constraints include coal-fired cogeneration units, alkali recovery cogeneration units, and lime kiln operation constraints:

[0062] Coal-fired cogeneration unit operation constraints:

[0063]

[0064]

[0065] Where: and It is the upper and lower limits of the electrical output of the coal-fired cogeneration unit, in MW; and is the upper and lower limits of the thermal output of the coal-fired cogeneration unit, in MW; k CHP,min and k CHP,max is the electric-to-heat conversion coefficient of the coal-fired cogeneration unit corresponding to the minimum and maximum electrical output; Cm is the slope of the cogeneration supply curve; The mass flow rate of high-pressure, medium-pressure and low-pressure steam supplied by the coal-fired cogeneration unit at hour t, in t / h; is the maximum downhill and uphill climbing rate of the coal-fired cogeneration unit, in MW; ζ CHP is the correction factor of the electric and thermal output of the coal-fired cogeneration unit; η CHP is the thermal efficiency of the coal-fired cogeneration unit; LHV coal is the lower calorific value of coal, in MJ / t;

[0066] Alkali recovery cogeneration unit operation constraints:

[0067]

[0068] Where: and It is the upper and lower limits of the electrical output of the alkali recovery cogeneration unit, in MW; and It is the upper and lower limits of the thermal output of the alkali recovery cogeneration unit, in MW; k AR,min and k AR,max is the electric-to-heat conversion coefficient of the alkali recovery cogeneration unit corresponding to the minimum and maximum electrical output; The mass flow rate of high-pressure steam supplied by the alkali recovery cogeneration unit at hour t, in t / h; is the maximum downhill and uphill climbing rate of the alkali recovery cogeneration unit, in MW; ζ AR is the correction coefficient of the electric and thermal output of the alkali recovery cogeneration unit; η AR is the thermal efficiency of the alkali recovery cogeneration unit;

[0069] Lime kiln operation constraints:

[0070]

[0071]

[0072] Where: m m,t is the amount of lime mud consumed by the lime kiln in the tth hour, in t; M m is the total amount of lime mud consumed daily by the lime kiln, in t; η LK is the efficiency of the lime kiln; ΔH m is the enthalpy change of lime mud to limestone conversion process, in MW / t; is the mass flow rate of medium-pressure steam generated by the lime kiln at hour t, in t / h; is the coal consumption of the lime kiln in the tth hour, in t / h; It is the thermal output of the lime kiln in the tth hour, in MW.

[0073] As a further improvement of the present invention, in step S3, the method of designing a differentiated scenario from the perspective of different factors of carbon trading and equipment transformation scheme combination includes:

[0074] S31, setting the carbon capture equipment, steam accumulator, booster pump, and electric boiler models in claim 2 as a combination of four equipment transformation solutions;

[0075] S32, based on the carbon quota allocation and trading mechanism in the same period, solve the optimal cost model of the comprehensive energy stock system of the pulp and paper industry; add the four equipment transformation scheme combinations in S31 in sequence, and solve the optimal cost model of the comprehensive energy system of the pulp and paper industry considering the equipment transformation scheme combination;

[0076] S33, set up four carbon trading periods according to the carbon quota allocation and trading mechanism;

[0077] S34, select the optimal cost model of the comprehensive energy system of the pulp and paper industry after equipment transformation, substitute the parameters of the carbon quota allocation and trading mechanism in different periods, correct the carbon trading related information of the objective function of the S32 optimization model, and solve the optimal cost model of the comprehensive energy system of the pulp and paper industry considering carbon trading.

[0078] Beneficial effects:

[0079] The present invention establishes a carbon quota allocation and trading mechanism model and a system transformation equipment model that can be applied to the comprehensive energy system planning of the pulp and paper industry. Through the links of baseline emissions, carbon quota allocation, carbon quota trading settlement, etc., the methodological basis and top-level design of the carbon quota mechanism are concretized into a carbon quota subsidy mechanism model applicable to the comprehensive energy system planning of the pulp and paper industry, providing conditions for establishing a mathematical model for the comprehensive energy system planning of the pulp and paper industry based on the carbon quota mechanism. Then, the equipment combination of carbon capture equipment, steam accumulator, booster pump, and electric boiler is comprehensively considered to establish a comprehensive energy system planning model for the pulp and paper industry in carbon trading and equipment transformation scenarios. By solving the planning model, the equipment planning capacity and system comprehensive energy cost parameters in different scenarios can be further analyzed and compared, that is, the equipment planning capacity, system comprehensive energy cost, system outsourcing energy cost, system carbon trading cost, system operation cost, system carbon capture cost, and system equipment investment cost of the pulp and paper mill in each scenario can be calculated and compared. Thus, the impact of the system transformation equipment combination and the carbon quota mechanism on the comprehensive economy of the pulp and paper mill can be quantitatively compared. This can guide the formulation of comprehensive energy system planning schemes for the pulp and paper industry, clarify the importance of carbon quota mechanism and system transformation equipment combination to the comprehensive energy economy of the pulp and paper industry, and improve the comprehensive economic benefits of the comprehensive energy system of the pulp and paper industry through carbon quota mechanism scenarios and diversified equipment transformation scenarios in different periods. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] Figure 1 is a flow chart of the steps of the method of the present invention;

[0081] Figure 2 is a schematic diagram of a comprehensive energy system for pulp and paper industry taking into account all system transformation equipment in an embodiment of the present invention;

[0082] Figure 3 This is a schematic diagram of energy flow balance of the comprehensive energy system of the pulp and paper industry modified in an embodiment of the present invention;

[0083] Figure 3 (a) is the electric bus balance diagram, (b) is the high-pressure steam bus mass flow balance diagram, (c) is the medium-pressure steam bus mass flow balance diagram, and (d) is the low-pressure steam bus mass flow balance diagram; Figure 3 The horizontal axis is the typical day hour number.

[0084] Figure 4 is a diagram comparing the system comprehensive costs in an embodiment of the present invention;

[0085] Figure 4 (a) is a cost comparison chart under different system transformation scenarios, and (b) is a cost comparison chart under different carbon trading periods. DETAILED DESCRIPTION

[0086] The following is a detailed description of the technical solution of the application in conjunction with the accompanying drawings. The described embodiments are only part of the embodiments involved in this patent. All non-innovative embodiments of other researchers in this field based on this embodiment are within the scope of protection of this patent.

[0087] Example 1

[0088] The integrated energy system planning method for the pulp and paper industry in the scenario of carbon trading and equipment transformation is shown in the flowchart of the method steps. Figure 1 The schematic diagram of the comprehensive energy system of the pulp and paper industry considering all system transformation equipment is shown in Figure 2 As shown, the following steps are included:

[0089] S1, establish a transformation equipment model that can be applied to the integrated energy system of the pulp and paper industry, including carbon capture equipment, steam accumulator, booster pump, and electric boiler;

[0090] S2, select the optimal comprehensive energy cost of the pulp and paper industry comprehensive energy system as the planning target, consider the energy balance and equipment operation constraints, and establish the optimal planning model of the comprehensive energy cost of the pulp and paper industry comprehensive energy system with a carbon quota mechanism;

[0091] S3, design differentiated scenarios from the perspective of different factors of carbon trading and equipment transformation scheme combination, determine the known quantities and unknown quantities in each scenario, and solve the optimal planning model to obtain the planning scheme;

[0092] S4, analyze and compare parameters such as equipment planning capacity and system comprehensive energy cost in different carbon trading and equipment transformation scenarios.

[0093] Further: In step S1, the transformation equipment model applicable to the comprehensive energy system of the pulp and paper industry includes carbon capture equipment, steam accumulator, booster pump, and electric boiler, wherein the carbon capture equipment model is:

[0094]

[0095] Where: is the electric power consumed by the carbon capture equipment in the tth hour, in MW / yr; W C The energy required to capture one ton of carbon dioxide for the carbon capture equipment, in MWh / t; emi c It is the carbon dioxide produced by burning one ton of standard coal, in t / tce; is the coal consumption of coal-fired cogeneration unit, alkali recovery cogeneration unit and lime kiln at hour t, in t / h; is the carbon capture coefficient of the coal-fired cogeneration unit, alkali recovery cogeneration unit and lime kiln at hour t; Maximum carbon capture coefficient of coal-fired cogeneration unit, alkali recovery cogeneration unit and lime kiln; Cap CC Plan the capacity of the carbon capture equipment in MW; Plan the maximum capacity of the carbon capture equipment in MW;

[0096] The steam accumulator model is:

[0097]

[0098] 0≤m cha,t ≤f cha,t m cha,max (7)

[0099] 0≤m dis,t ≤f dis,t m dis,max (8)

[0100]

[0101] f cha,t ,f dis,t ∈{0,1}(12)

[0102] f cha,t p valve≤p cha,t (13)

[0103] Where: Cap SA Plan the capacity of the steam accumulator in MW; Plan the maximum capacity of the steam accumulator in MW; m cha,t m dis,t is the mass flow rate of steam charging and discharging in the steam accumulator at hour t, in t / h; f cha,t is the state characterizing quantity of the steam accumulator charging at the t hour, the value is 1 when charging, and the value is 0 when not charging; f dis,t is the state characterizing quantity of steam accumulator steam release at the t hour, the value is 1 when steam is released, and the value is 0 when steam is not released; is the heat storage of the steam accumulator at the end of hour t, in MWh; cha,t is the steam enthalpy value of the steam accumulator at the tth hour, in MJ / t; h LP is the steam enthalpy of the steam accumulator, in MJ / t; Δt is the number of hours in the planning period; p valve is the pressure threshold of the steam accumulator charging valve, in MPa; p cha,t is the charging pressure of the steam accumulator at the tth hour, in MPa;

[0104] The booster pump model is:

[0105] p cha,min ≤p cha,t ≤p cha,max (14)

[0106] h cha,t =c1p cha,t T cha +c2T cha +c3p cha,t +c4 (15)

[0107]

[0108] 0≤P t PU ≤Cap PU (17)

[0109]

[0110] Where: p cha,min p cha,max It is the minimum and maximum value of the pressure of the booster pump charging the steam accumulator, in MPa; T cha is the charging temperature of the booster pump to the steam accumulator, in K; c1c2c3c4 are the quasi-linear fitting coefficients of steam enthalpy; Cap is the power consumed by the booster pump in the tth hour, in MW; PU Plan the capacity of the booster pump in MW; The maximum planned capacity of the booster pump, in MW;

[0111] The electric boiler model is:

[0112]

[0113] 0≤P t EB ≤Cap EB (20)

[0114]

[0115]

[0116] Where: Cap EB Indicates the planned capacity of the electric boiler, in MW; Indicates the maximum planned capacity of the electric boiler, in MW; is the electric power consumed by the electric boiler in hour t, in MW; is the heating power of the electric boiler at hour t, in MW; The maximum heating power of the electric boiler, in MW; is the mass flow rate of steam emitted by the electric boiler at hour t, in t / h; is the maximum mass flow rate of steam emitted by the electric boiler, in t / h; Γ represents the ratio of the maximum uphill and downhill climbing rate of the electric boiler to the maximum planned capacity; η EB It is the electric-heat conversion efficiency of the electric boiler.

[0117] Further: the comprehensive energy cost of the comprehensive energy system of the pulp and paper industry in step S2 includes: system outsourced energy cost, system carbon trading cost, system operation cost, system carbon capture cost, and system equipment investment cost. The system outsourced energy cost model is:

[0118]

[0119] Where: E sp is the cost of purchased energy, in $; r e,t r ge,t is the electricity price and green electricity price at hour t, in $ / MWh; P e,t P ge,t is the electricity price and green electricity purchase amount at hour t, in MWh; r coal is the unit price of coal, in $ / t; r loss The penalty unit price for abandoned steam is $ / t; is the quality of discarded steam, in t;

[0120] The carbon trading mechanism model is:

[0121]

[0122] Where: ε grid,carb is the carbon emission factor of electricity; CA t is the carbon emission of the comprehensive energy system of the pulp and paper industry at the t hour, in t; FCA t The number of carbon quotas allocated to the comprehensive energy system of the pulp and paper industry at hour t, in t; is the power output of the coal-fired cogeneration unit and the alkali recovery cogeneration unit at the tth hour, in MW; b e,coal The power supply benchmark for coal-fired units; r,coal f is the heating correction factor of the coal-fired unit; l,coal is the cooling mode correction factor of the coal-fired unit (set to 1); f f,coal is the load output factor correction factor of the coal-fired unit (set to 1); is the thermal output of the coal-fired cogeneration unit and the alkali recovery cogeneration unit at hour t, in MW; LHV is the mass flow rate of black liquor consumed by the alkali recovery cogeneration unit in the tth hour, in t / h; BL is the lower calorific value of black liquor, in MJ / t; b h,coal It is the heating benchmark for coal-fired units; is the carbon trading cost, in $, when the parameter is greater than 0, it is cost, and when the parameter is less than 0, it is benefit; c carb,eua c carb,cer is the unit price of carbon quota and certified voluntary emission reduction, in $ / t; EUA is the carbon quota trading volume, in t; CER is the certified voluntary emission reduction, in t; λ is the decline rate of the carbon quota baseline value; μ CER The maximum offset ratio for certified voluntary emission reductions;

[0123] The system operation cost model is:

[0124]

[0125] Where: is the unit operating cost of the coal-fired cogeneration unit, alkali recovery cogeneration unit, booster pump, carbon capture equipment, and electric boiler at hour t, in $ / MW; is the unit operating cost of the steam accumulator at hour t, in $ / MWh; is the unit operating cost of the medium-pressure and low-pressure steam bus waste heat recovery devices at hour t, in $ / MW; is the unit operating cost of the lime kiln at hour t, in $ / MW; is the steam mass flow rate recovered from the medium-pressure and low-pressure steam busbars at hour t, in t / h; h HP h MP is the enthalpy of medium-pressure and low-pressure steam at the tth hour, in MJ / t; is the heat generated by the lime kiln in hour t, in MW;

[0126] The system carbon capture cost model is:

[0127]

[0128] Where: E cc is the carbon capture cost, in $; r CC is the carbon capture unit price, in $ / t;

[0129] The system equipment investment cost model is:

[0130]

[0131] Where: E inv is the system equipment investment cost, in $; is the investment cost of carbon capture equipment, electric boiler, steam accumulator and booster pump, in $; h is the annual return on investment of the equipment; τ CC τ EB τ SA τ PU is the service life of carbon capture equipment, electric boiler, steam accumulator and booster pump, in years; I CC I EB I PU is the unit investment cost of carbon capture equipment, electric boiler, and booster pump, in $ / MW; I SA is the unit investment cost of the steam heat accumulator, in $ / MWh;

[0132] The system planning objective function is:

[0133]

[0134] Where: Obj is the comprehensive cost of the system, in $;

[0135] Further: In step S2, in step S2, the integrated energy system planning of the pulp and paper industry is subject to relevant conditions, including energy balance and equipment operation constraints:

[0136] 1) Energy balance constraints;

[0137] Energy balance constraints include electrical energy balance constraints, thermal energy balance constraints, and process energy supply constraints:

[0138] P t CHP +P t e +P t ge +P t AR =P t CC +P t EB +P t PU +P t eload (36)

[0139]

[0140]

[0141] Where: is the electrical load of the process at the tth hour, in MW; H2M χ M2L are the medium pressure and low pressure steam bus recovery factors, respectively; are the medium pressure and low pressure steam load mass flow rates, in t / h; δ en (n=1,2…,8) is the power demand per unit product of each dispatchable process at hour t; δ hn (n=1,2…,8) is the heat energy demand per unit product of each dispatchable process in hour t; are the power load and thermal load demands of other processes except the dispatchable process in hour t, in MW;

[0142] 2) Equipment operation constraints;

[0143] Equipment operation constraints include coal-fired cogeneration units, alkali recovery cogeneration units, and lime kiln operation constraints:

[0144] Coal-fired cogeneration unit operation constraints:

[0145]

[0146] Where: and It is the upper and lower limits of the electrical output of the coal-fired cogeneration unit, in MW; and is the upper and lower limits of the thermal output of the coal-fired cogeneration unit, in MW; k CHP,min and k CHP,max is the electric-to-heat conversion coefficient of the coal-fired cogeneration unit corresponding to the minimum and maximum electrical output; C m is the slope of the CHP supply curve; The mass flow rate of high-pressure, medium-pressure and low-pressure steam supplied by the coal-fired cogeneration unit at hour t, in t / h; is the maximum downhill and uphill climbing rate of the coal-fired cogeneration unit, in MW; ζ CHP is the correction factor of the electric and thermal output of the coal-fired cogeneration unit; is the thermal efficiency of the coal-fired cogeneration unit; LHV coal is the lower calorific value of coal, in MJ / t;

[0147] Alkali recovery cogeneration unit operation constraints:

[0148]

[0149] Where: and It is the upper and lower limits of the electrical output of the alkali recovery cogeneration unit, in MW; and It is the upper and lower limits of the thermal output of the alkali recovery cogeneration unit, in MW; k AR,min and k AR,max is the electric-to-heat conversion coefficient of the alkali recovery cogeneration unit corresponding to the minimum and maximum electrical output; The mass flow rate of high-pressure steam supplied by the alkali recovery cogeneration unit at hour t, in t / h; is the maximum downhill and uphill climbing rate of the alkali recovery cogeneration unit, in MW; ζ AR is the correction coefficient of the electric and thermal output of the alkali recovery cogeneration unit; η AR is the thermal efficiency of the alkali recovery cogeneration unit;

[0150] Lime kiln operation constraints:

[0151]

[0152] Where: m m,t is the amount of lime mud consumed by the lime kiln in the tth hour, in t; M m is the total amount of lime mud consumed daily by the lime kiln, in t; η LK is the efficiency of the lime kiln; ΔH m is the enthalpy change of lime mud to limestone conversion process, in MW / t; is the mass flow rate of medium-pressure steam generated by the lime kiln at hour t, in t / h; is the coal consumption of the lime kiln in the tth hour, in t / h; is the thermal output of the lime kiln at hour t, in MW;

[0153] In the embodiment, the comprehensive energy system data of a pulp and paper mill in Jiangsu is substituted into the model for calculation and solution. The specific data of the equipment operation parameters involved are shown in Table 1. The conventional electricity price and green electricity price data of the pulp and paper mill area are shown in Table 2.

[0154] Table 1 Pulp and paper mill equipment operating parameter data in the embodiment

[0155]

[0156]

[0157] Table 2 Conventional electricity price and green electricity price data for the area where the pulp and paper mill is located in the embodiment

[0158]

[0159] Further: In step S3, the differentiated scenario method is designed from the perspective of different factors of carbon trading and equipment transformation scheme combination, including:

[0160] S31, the carbon capture equipment, steam accumulator, booster pump, and electric boiler models in claim 2 are set as four equipment transformation scheme combinations, and scenario A, scenario B, scenario C, and scenario D are generated in sequence according to the specific combination strategy. Scenario A represents no equipment is added, scenario B represents only adding carbon capture equipment, scenario C represents adding carbon capture equipment and electric boiler, and scenario D represents adding carbon capture equipment, steam accumulator, booster pump, and electric boiler. The specific scenario classification is shown in Table 3;

[0161] Table 3 Pulp and paper mill comprehensive energy system transformation scenario division table in the embodiment

[0162]

[0163] Note: ● indicates that the technology / equipment is applied, and × indicates that the technology / equipment is not applied.

[0164] S32, based on the carbon quota allocation and trading mechanism in the same period, solve the optimal cost model of the comprehensive energy stock system of the pulp and paper industry; add the four equipment transformation scheme combinations in S31 in sequence, and solve the optimal cost model of the comprehensive energy system of the pulp and paper industry considering the equipment transformation scheme combination;

[0165] S33, according to the carbon quota allocation and trading mechanism, four carbon trading periods are set up. Based on the forecast of the carbon market situation every five years from 2025 to 2040, the carbon trading periods A, B, C and D are divided, and the changes in the maximum offset ratio of certified voluntary emission reductions and the decline rate of carbon quota baseline values ​​are included in the scenario evolution, and different carbon quota unit prices and certified voluntary emission reduction unit prices are substituted in different carbon trading periods. The specific classification of carbon trading periods is shown in Table 4;

[0166] Table 4 Carbon trading period division table in the embodiment

[0167]

[0168] S34, select the optimal cost model of the comprehensive energy system of the pulp and paper industry after equipment transformation, substitute the parameters of the carbon quota allocation and trading mechanism in different periods, correct the carbon trading related information of the objective function of the S32 optimization model, and solve the optimal cost model of the comprehensive energy system of the pulp and paper industry considering carbon trading;

[0169] Further: in step S4, analyze and compare the equipment planning capacity, system comprehensive energy cost, system purchased energy cost, system carbon trading cost, system operating cost, system carbon capture cost, and system equipment investment cost in different carbon trading and equipment transformation scenarios.

[0170] Table 5 compares and analyzes the equipment planning capacity, system comprehensive energy cost, system purchased energy cost, system carbon trading cost, system operation cost, system carbon capture cost, and system equipment investment cost of the four equipment transformation scenarios. The purchased energy cost is divided into fossil energy consumption cost, conventional electricity and green electricity consumption cost, so as to analyze the impact of equipment transformation on system economy in detail. In addition, the cost comparison of equipment technology application change plan is shown in Figure 4 (a). The planning results specifically include carbon quota trading volume, certified voluntary emission reduction trading volume and equipment planning capacity. Among them, the positive value of the trading volume indicates the purchase of quotas, and the negative value indicates the sale of quotas.

[0171] Table 5 Comparison of equipment transformation scenario planning results in the embodiment

[0172]

[0173] The comparison between scenario A and scenario B shows the benefits of carbon capture equipment, which reduces the overall system cost by about 9.3%. The planned addition of 13.5MW of carbon capture equipment directly increases the equipment investment by 0.024*105$ and the carbon capture cost by 17.35*105$, and causes the system to increase clean energy consumption by 17.35*105$ and fossil energy consumption by 11.9*105$, but at the same time generates carbon trading benefits of 111.24*105$. Overall, the carbon emission reduction benefits of carbon capture equipment offset the increase in other costs.

[0174] The comparison between scenario B and scenario C aims to evaluate the economic benefits of electric boilers, which can reduce the overall system cost by about 2.3%. The planned addition of 50MW electric boiler capacity reduces the capacity of carbon capture equipment by 1.28MW, but increases the equipment investment by 0.475*105$. Among them, the reduction in carbon capture equipment capacity is because the electric boiler supplements the energy supply of the low-pressure steam bus, reduces the output of the waste heat recovery device of the low-pressure steam bus, and then leads to a reduction in the output of the lime kiln that supplies energy to the medium-pressure steam bus, and a reduction in the planned capacity of the carbon capture equipment. This reduces the system operating cost of 64.56*105$ and the carbon capture cost of 12.11*105$. However, the reduction in the capacity of carbon capture equipment leads to a loss of carbon trading benefits of 57.68*105$. In addition, the planned addition of electric boiler capacity increases the system clean energy consumption, but reduces the output of the lime kiln by 28.22*105$.

[0175] The comparison between scenario C and scenario D shows the benefits of using steam accumulator and booster pump, which can reduce the overall system cost by about 1.88% and increase the equipment investment by 1.627*105$. However, due to the steam charging and discharging process of the steam accumulator, the system's heat and electricity demand is reduced, which leads to a decrease in the system's clean energy consumption by 9.93*105$. At the same time, the system's expected carbon capture equipment planning capacity is reduced by 1.04MW, and the carbon capture cost is reduced by 0.45*105$ and the carbon trading income is reduced by 1.58*105$.

[0176] In summary, the integration of carbon capture equipment, steam accumulator, booster pump and electric boiler reduced the system comprehensive cost by 5.19*106$. In addition, the daily carbon emissions of the pulp and paper integrated energy system were significantly reduced from 1,251.2tce to 799tce, a total reduction of 452.2tce.

[0177] In order to further analyze the reasons for the reduction in system carbon emissions and comprehensive costs after the technical transformation, the coordinated operation of the planned equipment on a typical day was analyzed.

[0178] Figure 3 (a) shows the power balance of the pulp and paper integrated energy system with the addition of carbon capture equipment, steam accumulator, booster pump, and electric boiler in scenario D. During the afternoon and nighttime flat valley electricity prices, the system increases its power demand, purchases conventional electricity and green electricity from the grid, and increases the output of electric boilers (especially from 1:00 to 8:00). During other periods of a typical day, the power load is mainly met by coal-fired cogeneration units and alkali recovery cogeneration units. Among them, the coal-fired cogeneration unit provides a relatively stable output, while the alkali recovery cogeneration unit meets the demand fluctuations caused by conventional electricity and green electricity consumption.

[0179] Figure 3(b)-(d) show the mass flow balance of high, medium and low pressure steam buses. The high pressure steam bus is mainly supplied by the alkali recovery cogeneration unit, and its steam supply flow remains stable at 36.83t / h during the flat and valley electricity price period. During the valley electricity price period (9:00-11:00, 18:00-22:00), the heat output of ARCHP decreases.

[0180] There is a steady demand for heat in the medium-pressure steam bus. However, during off-peak electricity prices, the heat transferred from the high pressure to the medium-pressure steam bus is reduced, prompting the lime kiln to increase its heating value to meet the demand. The medium-pressure steam demand peaks in the morning (4:00 to 8:00) and afternoon (12:00 to 17:00), with peaks of 9.23t / h and 8.52t / h, respectively.

[0181] The demand for low-pressure steam busbar is mainly determined by the production process and the steam accumulator charging volume, and is mainly supplied by the low-pressure steam busbar waste heat recovery device, coal-fired cogeneration unit, electric boiler and steam accumulator discharge process. During the peak electricity price period (9:00-11:00, 18:00-22:00), the demand for low-grade heat is extremely small, while during the off-peak electricity price period, the demand for low-pressure steam increases to 154.9t / h to 184.5t / h. During the flat valley electricity price period, the system responds to the increased demand by increasing the output of the electric boiler and the steam accumulator discharge volume. Conversely, during the peak electricity price period, the output of the electric boiler is reduced, and the system charges steam into the steam accumulator, thereby ensuring a constant heat storage capacity throughout the planning period.

[0182] Table 6 compares and analyzes the equipment planning capacity, system comprehensive energy cost, system purchased energy cost, system carbon trading cost, system operation cost, system carbon capture cost, and system equipment investment cost during the four carbon trading periods. The purchased energy cost is divided into fossil energy consumption cost, conventional electricity and green electricity consumption cost, so as to analyze the impact of the carbon trading period on the system economy in detail. In addition, the comparison of various cost parameters of the system during the carbon trading period is detailed in Figure 4 (b) The planning results specifically include carbon quota trading volume, certified voluntary emission reduction trading volume and equipment planning capacity. Among them, the positive value of the trading volume indicates the purchase of quotas, and the negative value indicates the sale of quotas.

[0183] Table 6 Comparison of planning results during the carbon trading period in the embodiment

[0184]

[0185]

[0186] In periods A to D, as the decline rate of carbon quota prices, certified voluntary emission reduction prices, the maximum offset ratio of certified voluntary emission reductions, and the carbon quota baseline value gradually increased, the pulp and paper integrated energy system reduced carbon emissions by adding carbon capture equipment, steam accumulators, booster pumps, and electric boilers. Therefore, the system's carbon trading income increased and the system's overall cost decreased.

[0187] Specifically, from period A to C, the planned capacity of carbon capture equipment, steam accumulator, and booster pump increased, resulting in a continuous increase in the sales of carbon quotas. Considering the investment and operation and maintenance costs of carbon capture equipment in period A, the price of carbon quotas has limited incentives for carbon reduction in carbon capture equipment. Therefore, the actual carbon emissions are still greater than the free allocated quotas, and the system needs to purchase about 7 tons of carbon quotas to offset carbon emissions. Therefore, the system purchases 50.22 tons of certified emission reductions at a low price to offset carbon quotas, and sells 43.24 tons of carbon quotas at a high price to obtain high carbon trading income. In periods B and C, the prices of carbon quotas and certified emission reductions fully stimulate carbon fixation in carbon capture equipment, so the system is able to sell about 834 tons and 785 tons of carbon quotas to offset carbon emissions. In period D, although the total amount of carbon quotas sold by the system decreased to about 756t, the system's carbon trading income still increased due to the high prices of carbon quotas and certified emission reductions. The high carbon trading income of the system exceeds the cost reduction through the flexible use of heat energy by the steam accumulator, which makes the system reduce the planned capacity of the steam accumulator and booster pump and tend to increase the purchase of green electricity. Therefore, the system carbon trading income is 65.31*105$ more than that of period C, and the comprehensive cost of the system is reduced by 54.86*105$.

[0188] In summary, the embodiment of the present invention establishes a comprehensive energy system planning model for the pulp and paper industry in carbon trading and equipment transformation scenarios. A transformation equipment model applicable to the comprehensive energy system of the pulp and paper industry is established, including carbon capture equipment, steam accumulators, booster pumps, and electric boilers. The methodological basis and top-level design of the carbon quota and certified voluntary emission reduction mechanism are concretized into a carbon quota mechanism model and a certified voluntary emission reduction mechanism model applicable to the comprehensive energy system planning of the pulp and paper industry, providing conditions for establishing a comprehensive energy system planning for the pulp and paper industry based on carbon trading. Then, the combined parameter requirements of the carbon trading and equipment transformation schemes are comprehensively considered to establish a comprehensive energy system planning model for the pulp and paper industry applicable to carbon trading and equipment transformation scenarios. In the embodiment, the carbon quota and certified voluntary emission reduction mechanism are mainly converted into carbon quota prices and certified voluntary emission reduction mechanism price parameters, taking into account the maximum offset ratio of certified voluntary emission reductions and the decline rate of the carbon quota baseline value, and solving the planning model under four equipment transformation scenarios and the planning model of four carbon trading periods in turn, which can further analyze and compare the equipment planning capacity and system economic parameters in different scenarios, that is, calculate and compare the equipment planning capacity of the comprehensive energy system of the pulp and paper industry in each scenario, the system comprehensive energy cost, the system purchased energy cost, the system carbon trading cost, the system operating cost, the system carbon capture cost, and the system equipment investment cost. Thereby, the impact of carbon trading and equipment transformation scenarios on the planning results of the comprehensive energy system of the pulp and paper industry can be quantitatively compared. The embodiment verifies the reliability and scientificity of the transformation equipment model, carbon quota mechanism model, and certified voluntary emission reduction mechanism model applicable to the comprehensive energy system planning of the pulp and paper industry through the model solution results. It can guide the formulation of the comprehensive energy system planning scheme for the pulp and paper industry, and explain the importance of system transformation equipment, carbon quota mechanism, and certified voluntary emission reduction mechanism to the comprehensive cost of the pulp and paper energy supply system and equipment planning capacity. Furthermore, the comprehensive energy system planning model for the pulp and paper industry based on the transformation equipment model, carbon quota mechanism model, and certified voluntary emission reduction mechanism model can reduce the comprehensive cost of the comprehensive energy system of the pulp and paper industry in different carbon trading periods and diversified equipment transformation scenarios.

[0189] The present invention verifies the scenario adaptability and planning potential of the comprehensive energy system planning model for the pulp and paper industry in carbon trading and equipment transformation scenarios, and has engineering application value.

[0190] The above description is only a preferred embodiment of the present invention and does not constitute any other form of limitation to the present invention. Any modification or equivalent change made based on the technical essence of the present invention still falls within the scope of protection required by the present invention.

Claims

1. A method for planning an integrated energy system for pulp and papermaking in carbon trading and equipment transformation scenarios, characterized in that: The steps include: S1, establish a transformation equipment model that can be applied to the integrated energy system of the pulp and paper industry, including carbon capture equipment, steam accumulator, booster pump, and electric boiler; S2, select the optimal comprehensive energy cost of the pulp and paper industry comprehensive energy system as the planning target, consider the energy balance and equipment operation constraints, and establish the optimal planning model of the comprehensive energy cost of the pulp and paper industry comprehensive energy system with a carbon quota mechanism; S3, design differentiated scenarios from the perspective of different factors of carbon trading and equipment transformation scheme combination, determine the known quantities and unknown quantities in each scenario, and solve the optimal planning model to obtain the planning scheme; S4, analyze and compare the equipment planning capacity, system comprehensive energy cost, system purchased energy cost, system carbon trading cost, system operating cost, system carbon capture cost, and system equipment investment cost in different carbon trading and equipment transformation scenarios.

2. The method for planning a comprehensive energy system for pulp and papermaking in a carbon trading and equipment transformation scenario according to claim 1 is characterized by: The transformation equipment model that can be applied to the comprehensive energy system of the pulp and paper industry in step S1, wherein the carbon capture equipment model is: Where: is the electric power consumed by the carbon capture equipment in the tth hour, in MW / yr; W C The energy required to capture one ton of carbon dioxide for the carbon capture equipment, in MWh / t; emi c It is the carbon dioxide produced by burning one ton of standard coal, in t / tce; is the coal consumption of coal-fired cogeneration unit, alkali recovery cogeneration unit and lime kiln at hour t, in t / h; is the carbon capture coefficient of the coal-fired cogeneration unit, alkali recovery cogeneration unit and lime kiln at hour t; Maximum carbon capture coefficient of coal-fired cogeneration unit, alkali recovery cogeneration unit and lime kiln; Cap CC Plan the capacity of the carbon capture equipment in MW; Plan the maximum capacity of the carbon capture equipment in MW; The steam accumulator model is: 0≤m cha,t ≤f cha，t m cha，max 0≤m dis，t ≤f dis，t m dis,max f cha，t ,f dis，t ∈{0,1} f cha，t p valve ≤p cha，t Where: Cap SA Plan the capacity of the steam accumulator in MW; Plan the maximum capacity of the steam accumulator in MW; m cha，t m dis，t is the mass flow rate of steam charging and discharging in the steam accumulator at hour t, in t / h; f cha，t is the state characterizing quantity of the steam accumulator charging at the t hour, the value is 1 when charging, and the value is 0 when not charging; f dis,t is the state characterizing quantity of steam accumulator steam release at the t hour, the value is 1 when steam is released, and the value is 0 when steam is not released; is the heat storage of the steam accumulator at the end of hour t, in MWh; cha，t is the steam enthalpy value of the steam accumulator at the tth hour, in MJ / t; h LP is the steam enthalpy of the steam accumulator, in MJ / t; Δt is the number of hours in the planning period; p valve is the pressure threshold of the steam accumulator charging valve, in MPa; p cha，t is the charging pressure of the steam accumulator at the tth hour, in MPa; The booster pump model is: p cha，min ≤p cha，t ≤p cha，max h cha，t =c1p cha，t T cha +c2T cha +c3p cha，t +c4 0≤P t PU ≤Cap PU Where: p cha，min p cha，max It is the minimum and maximum value of the pressure of the booster pump charging the steam accumulator, in MPa; T cha is the charging temperature of the booster pump to the steam accumulator, in K; c1c2c3c4 are the quasi-linear fitting coefficients of steam enthalpy; Cap is the power consumed by the booster pump in the tth hour, in MW; PU Plan the capacity of the booster pump in MW: The maximum capacity of the booster pump is planned in MW: The electric boiler model is: 0≤P t EB ≤Cap EB Where: CapE B Indicates the planned capacity of the electric boiler, in MW; Indicates the maximum planned capacity of the electric boiler, in MW; is the electric power consumed by the electric boiler in hour t, in MW; is the heating power of the electric boiler at hour t, in MW; The maximum heating power of the electric boiler, in MW; is the mass flow rate of steam emitted by the electric boiler at hour t, in t / h; is the maximum mass flow rate of steam emitted by the electric boiler, in t / h; Γ represents the ratio of the maximum uphill and downhill climbing rate of the electric boiler to the maximum planned capacity; η EB It is the electric-heat conversion efficiency of the electric boiler.

3. The method for planning a comprehensive energy system for pulp and papermaking in a carbon trading and equipment transformation scenario according to claim 1 is characterized by: The comprehensive energy cost of the comprehensive energy system of the pulp and paper industry in step S2 includes: system outsourced energy cost, system carbon trading cost, system operation cost, system carbon capture cost, and system equipment investment cost. The system outsourced energy cost model is: Where: E sp is the cost of purchased energy, in $; r e，t r ge，t is the electricity price and green electricity price at hour t, in $ / MWh; P e，t P ge，t is the electricity price and green electricity purchase amount at hour t, in MWh; r coal is the unit price of coal, in $ / t; r loss The penalty unit price for abandoned steam is $ / t; is the quality of discarded steam, in t; The carbon trading mechanism model is: Where: εgrid,carb is the carbon emission factor of electricity; CA t is the carbon emission of the comprehensive energy system of the pulp and paper industry at the t hour, in t; FCA t The number of carbon quotas allocated to the comprehensive energy system of the pulp and paper industry at hour t, in t; is the power output of the coal-fired cogeneration unit and the alkali recovery cogeneration unit at the tth hour, in MW; b e，coal The power supply benchmark for coal-fired units; r，coal f is the heating correction factor of the coal-fired unit; l，coal The correction factor for the cooling mode of the coal-fired unit is set to 1; f f，coal The load output factor correction factor for coal-fired units is set to 1; is the thermal output of the coal-fired cogeneration unit and the alkali recovery cogeneration unit at hour t, in MW; LHV is the mass flow rate of black liquor consumed by the alkali recovery cogeneration unit in the tth hour, in t / h; BL is the lower calorific value of black liquor, in MJ / t; b h，coal It is the heating benchmark for coal-fired units; is the carbon trading cost, in $, when the parameter is greater than 0, it is cost, and when the parameter is less than 0, it is benefit; c carb,eua c carb,cer is the unit price of carbon quota and certified voluntary emission reduction, in $ / t; EUA is the carbon quota trading volume, in t; CER is the certified voluntary emission reduction, in t; λ is the decline rate of the carbon quota baseline value; μ CER The maximum offset ratio for certified voluntary emission reductions; The system operation cost model is: Where: is the unit operating cost of the coal-fired cogeneration unit, alkali recovery cogeneration unit, booster pump, carbon capture equipment, and electric boiler at hour t, in $ / MW; is the unit operating cost of the steam accumulator at hour t, in $ / MWh; is the unit operating cost of the medium-pressure and low-pressure steam bus waste heat recovery devices at hour t, in $ / MW; is the unit operating cost of the lime kiln at hour t, in $ / MW; The mass flow rate of steam recovered from the medium-pressure and low-pressure steam busbars at hour t, in t / h; h HP h MP is the enthalpy of medium-pressure and low-pressure steam at the tth hour, in MJ / t; is the heat generated by the lime kiln in hour t, in MW; The system carbon capture cost model is: Where: E cc is the carbon capture cost, in $; r CC is the carbon capture unit price, in $ / t; The system equipment investment cost model is: Where: E inv is the system equipment investment cost, in $; is the investment cost of carbon capture equipment, electric boiler, steam accumulator and booster pump, in $; h is the annual return on investment of the equipment; τ CC τ EB τ SA τ PU is the service life of carbon capture equipment, electric boiler, steam accumulator and booster pump, in years; I CC I EB I PU is the unit investment cost of carbon capture equipment, electric boiler, and booster pump, in $ / MW; I SA is the unit investment cost of the steam heat accumulator, in $ / MWh; The system planning objective function is: Where: Obj is the comprehensive cost of the system, in $.

4. The method for planning a comprehensive energy system for pulp and papermaking in a carbon trading and equipment transformation scenario according to claim 1 is characterized by: In step S2, the integrated energy system planning of the pulp and paper industry is subject to relevant conditions, including energy balance and equipment operation constraints: 1) Energy balance constraints; Energy balance constraints include electrical energy balance constraints, thermal energy balance constraints, and process energy supply constraints: Where: is the electrical load of the process at the tth hour, in MW; H2M χ M2L are the medium pressure and low pressure steam bus recovery factors, respectively; are the medium pressure and low pressure steam load mass flow rates, in t / h; δ en , n = 1, 2…, 8 is the power demand per unit product of each dispatchable process at hour t; δ hn , n=1,2…,8 is the heat energy demand per unit product of each dispatchable process in hour t; are the power load and thermal load demands of other processes except the dispatchable process in hour t, in MW; 2) Equipment operation constraints; Equipment operation constraints include coal-fired cogeneration units, alkali recovery cogeneration units, and lime kiln operation constraints: Coal-fired cogeneration unit operation constraints: Where: and It is the upper and lower limits of the electrical output of the coal-fired cogeneration unit, in MW; and is the upper and lower limits of the thermal output of the coal-fired cogeneration unit, in MW; k CHP,min and k CHP,max is the electric-to-heat conversion coefficient of the coal-fired cogeneration unit corresponding to the minimum and maximum electrical output; C m is the slope of the CHP supply curve; The mass flow rate of high-pressure, medium-pressure and low-pressure steam supplied by the coal-fired cogeneration unit at hour t, in t / h; is the maximum downhill and uphill climbing rate of the coal-fired cogeneration unit, in MW; ζ CHP is the correction factor for the electric and thermal output of the coal-fired cogeneration unit; η CHP is the thermal efficiency of the coal-fired cogeneration unit; LHV coal is the lower calorific value of coal, in MJ / t; Alkali recovery cogeneration unit operation constraints: Where: and It is the upper and lower limits of the electrical output of the alkali recovery cogeneration unit, in MW; and It is the upper and lower limits of the thermal output of the alkali recovery cogeneration unit, in MW; k AR,min and k AR,max is the electric-to-heat conversion coefficient of the alkali recovery cogeneration unit corresponding to the minimum and maximum electrical output; The mass flow rate of high-pressure steam supplied by the alkali recovery cogeneration unit at hour t, in t / h; is the maximum downhill and uphill climbing rate of the alkali recovery cogeneration unit, in MW; ζ AR is the correction coefficient of the electric and thermal output of the alkali recovery cogeneration unit; η AR is the thermal efficiency of the alkali recovery cogeneration unit; Lime kiln operation constraints: Where: m m,t is the amount of lime mud consumed by the lime kiln in the tth hour, in t; M m is the total amount of lime mud consumed daily by the lime kiln, in t; η LK is the efficiency of the lime kiln; ΔH m is the enthalpy change of lime mud to limestone conversion process, in MW / t; is the mass flow rate of medium-pressure steam generated by the lime kiln at hour t, in t / h; is the coal consumption of the lime kiln in the tth hour, in t / h; It is the thermal output of the lime kiln in the tth hour, in MW.

5. The method for planning a comprehensive energy system for pulp and papermaking in a carbon trading and equipment transformation scenario according to claim 1 is characterized by: In step S3, the differentiated scenario methods are designed from the perspectives of different factors of carbon trading and equipment transformation scheme combinations, including: S31, setting the carbon capture equipment, steam accumulator, booster pump, and electric boiler models in claim 2 as a combination of four equipment transformation solutions; S32, based on the carbon quota allocation and trading mechanism in the same period, solve the optimal cost model of the comprehensive energy stock system of the pulp and paper industry; add the four equipment transformation scheme combinations in S31 in sequence, and solve the optimal cost model of the comprehensive energy system of the pulp and paper industry considering the equipment transformation scheme combination; S33, set up four carbon trading periods according to the carbon quota allocation and trading mechanism; S34, select the optimal cost model of the comprehensive energy system of the pulp and paper industry after equipment transformation, substitute the parameters of the carbon quota allocation and trading mechanism in different periods, correct the carbon trading related information of the objective function of the S32 optimization model, and solve the optimal cost model of the comprehensive energy system of the pulp and paper industry considering carbon trading.

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