Method and system for optimal operation of a multi-energy coupling complementary hydrogen production system

Abstract

The application discloses a kind of multi-energy coupling complementary hydrogen production system's optimization operation method and system, belong to electrical engineering field, method includes: establishing water electrolysis hydrogen production sub-model, biomass hydrogen production sub-model and natural gas hydrogen production sub-model;With the oxygen generated by water electrolysis hydrogen production is complementary utilization by biomass hydrogen production and natural gas hydrogen production, the hydrocarbon fuel generated by biomass hydrogen production is complementary utilized by natural gas hydrogen production as the criterion, construct material complementary utilization constraint, with biomass hydrogen production and natural gas hydrogen production coupling to form global heat balance as the criterion, construct heat complementary utilization constraint;According to each sub-model, each complementary utilization constraint and system operation constraint, with smooth hydrogen production maximum as target, construct multi-energy coupling complementary hydrogen production optimization model;After linearization processing to nonlinear term in model, solution is obtained, to obtain optimal hydrogen production plan.The comprehensive energy utilization efficiency of system is improved, carbon emission is reduced.

Description

Technical Field

[0001] This invention belongs to the field of electrical engineering, and more specifically, relates to an optimized operation method and system for a multi-energy coupled complementary hydrogen production system. Background Technology

[0002] Hydrogen is a promising secondary energy source. The petrochemical industry consumes 10 million tons of hydrogen annually for refineries to reduce the sulfur content of diesel fuel and improve heavy residue oil. Considering the safety requirements of the petrochemical industry, refineries need a stable hydrogen supply without installing hydrogen storage devices.

[0003] Currently, fossil fuel-based hydrogen production is the primary source of hydrogen supply, with natural gas steam reforming being the most common method. Traditional fossil fuel-based hydrogen production suffers from high pollution and high energy consumption, failing to meet the urgent requirements of energy utilization and environmental protection. Replacing fossil fuels with renewable energy for hydrogen production is a crucial means of reducing carbon emissions. Current major renewable energy hydrogen production methods include water electrolysis, biomass hydrogen production, photovoltaic electrolysis, and photocatalytic hydrogen production. However, green hydrogen is not economically competitive with fossil fuel-based hydrogen production, and the volatility of renewable energy sources makes it difficult to meet the safe and stable hydrogen production requirements of the traditional petrochemical industry. Coupling multiple energy sources for hydrogen production is considered an effective method to address these issues.

[0004] Existing research on multi-energy coupled hydrogen production mostly focuses on the energy aspect, aiming to organically combine chemical processes and thermodynamic cycles through the comprehensive and cascaded utilization of energy. However, it neglects the coupling relationships between different energy sources. Therefore, further exploration of multi-energy coupled complementary hydrogen production methods to fully leverage the complementary effects of matter and energy is of great significance. Summary of the Invention

[0005] To address the shortcomings and improvement needs of existing technologies, this invention provides an optimized operation method and system for a multi-energy coupled complementary hydrogen production system. Its purpose is to solve the problems of high pollution and high energy consumption in hydrogen production from single fossil fuels, as well as the high price and high volatility of hydrogen production from single renewable energy sources.

[0006] To achieve the above objectives, according to one aspect of the present invention, an optimized operation method for a multi-energy coupled complementary hydrogen production system is provided. The system utilizes water, biomass, and natural gas for coupled complementary hydrogen production. The method includes: S1, establishing a sub-model for hydrogen production via water electrolysis, a sub-model for hydrogen production via biomass, and a sub-model for hydrogen production via natural gas; S2, constructing a material complementarity utilization constraint based on the criterion that oxygen produced by water electrolysis is complementarily utilized by biomass hydrogen production and natural gas hydrogen production, and that hydrocarbon fuel produced by biomass hydrogen production is complementarily utilized by natural gas hydrogen production; and constructing a heat complementarity utilization constraint based on the criterion that biomass hydrogen production and natural gas hydrogen production form a global thermal balance; S3, constructing a multi-energy coupled complementary hydrogen production optimization model based on the aforementioned sub-models for water electrolysis, biomass hydrogen production, and natural gas hydrogen production, the material complementarity utilization constraint, the heat complementarity utilization constraint, and the system operation constraint, with the objective of maximizing stable hydrogen production; and S4, linearizing the nonlinear terms in the multi-energy coupled complementary hydrogen production optimization model and then solving it to obtain an optimal hydrogen production plan, enabling the system to produce hydrogen according to the optimal hydrogen production plan.

[0007] Furthermore, the biomass-based hydrogen production model is as follows:

[0008]

[0009]

[0010]

[0011] in, This refers to the oxygen consumption in the biomass hydrogen production process. This represents the total consumption of biomass. The hydrogen production capacity of the biomass hydrogen production module. This represents the actual amount of biomass consumed for hydrogen production. denoted as hydrocarbon fuel produced by biomass gasification, m as the oxygen consumption coefficient of the biomass hydrogen production process, x1 as the hydrogen production coefficient of the biomass unit, and x5 as the methane production coefficient of the biomass unit.

[0012] Furthermore, x1 and x5 satisfy:

[0013]

[0014] in, The heat of wood formation, The heat of formation of liquid water, The heat of oxygen formation. The heat of formation of nitrogen gas. The heat of hydrogen formation. The heat of formation of carbon monoxide. The heat of formation of carbon dioxide. The heat of formation of water vapor. The heat of formation of methane. This refers to the specific heat capacity of hydrogen. The specific heat capacity of carbon monoxide. This represents the specific heat capacity of carbon dioxide. The specific heat capacity of water, The specific heat capacity of methane, denoted as , where is the specific heat capacity of nitrogen, w is the moisture content per kmol of wood, x2 is the coefficient corresponding to the production of carbon monoxide from biomass gasification, x3 is the coefficient corresponding to the production of carbon dioxide from biomass gasification, x4 is the coefficient corresponding to the production of water vapor from biomass gasification, and ΔT is the difference between the gasification temperature in the reduction zone and the ambient temperature.

[0015] Furthermore, the sub-model for hydrogen production from natural gas is as follows:

[0016]

[0017]

[0018] in, These are the oxygen consumption and oxygen consumption coefficient of the natural gas-to-hydrogen module. This represents the total consumption of natural gas. These are the hydrogen production capacity and hydrogen production coefficient of the natural gas-to-hydrogen module, respectively.

[0019] Furthermore, and satisfy:

[0020]

[0021] in, These represent the molar flow rate and enthalpy of reactant j in the natural gas-to-hydrogen module, respectively. ΔH represents the molar flow rate and enthalpy of product i in the natural gas to hydrogen production module, respectively, and ΔH is the enthalpy change between reactants and products. When the molar flow rate of natural gas entering the natural gas to hydrogen production module is 1 mol / s, These are equal to the molar flow rates of the reactant oxygen and the product hydrogen, respectively.

[0022] Furthermore, the system utilizes the high temperature generated during biomass hydrogen production to preheat the gas in the natural gas hydrogen production intake channel, establishing a complementary heat utilization constraint:

[0023]

[0024]

[0025]

[0026] T 0 ≤Tt gas ≤T bio_out

[0027] in, These represent the molar flow rate and enthalpy change of product i from the biomass hydrogen production module, respectively. These represent the molar flow rate and enthalpy change of reactant j in the biomass hydrogen production module, respectively. These represent the oxygen consumption coefficient and hydrogen production coefficient of the natural gas to hydrogen module, respectively, T. t gas Let T be the feed temperature of the natural gas to hydrogen production module, F1(·) represent the functional relationship between the feed temperature and oxygen consumption, and F2(·) represent the functional relationship between the feed temperature and hydrogen production rate. 0 For ambient temperature, T bio _ out The temperature at which hydrogen is produced from biomass.

[0028] Furthermore, the system operation constraints include: start-up and shutdown constraints for each hydrogen production module, operating status constraints for each hydrogen production module, operation constraints for the energy storage module, operation constraints for the oxygen storage module, operation constraints for the gas storage module, and stable hydrogen production constraints.

[0029] Furthermore, the working state constraints of each hydrogen production module include working range constraints, ramp-up constraints, and the relationship constraints between the module feed and the raw materials actually used for hydrogen production; the linearization process in S4 includes: linearizing the constraints of the electrolysis water hydrogen production sub-model, the natural gas hydrogen production sub-model, and the relationship constraints between the module feed and the raw materials actually used for hydrogen production.

[0030] Furthermore, in S4, the Big M method is used to linearize the constraint on the relationship between the module feed and the raw materials actually used for hydrogen production.

[0031] According to another aspect of the present invention, a multi-energy coupled complementary hydrogen production system is provided, wherein the system produces hydrogen using the optimal hydrogen production plan obtained by the optimized operation method of the multi-energy coupled complementary hydrogen production system as described above.

[0032] In summary, the above-described technical solutions conceived in this invention can achieve the following beneficial effects:

[0033] (1) Utilize the oxygen produced by electrolysis of water to produce hydrogen as a gasification agent for biomass hydrogen production and to regulate the thermal effect of hydrogen production through the chemical chain of natural gas pure oxidation; utilize the hydrocarbon fuel produced by biomass hydrogen production as a feedstock for natural gas hydrogen production; at the same time, use the high-temperature gas generated by biomass hydrogen production to preheat the gas inlet of natural gas hydrogen production to increase the feed temperature of natural gas hydrogen production and reduce the energy consumption of natural gas separation; realize the transformation of fluctuating energy input to stable hydrogen output, improve the overall energy utilization efficiency of the system, and reduce carbon emissions;

[0034] (2) A multi-energy coupled complementary hydrogen production system of solar energy, biomass and natural gas is proposed, which can meet the stable hydrogen demand under the carbon emission requirements; and an optimized operation model of the proposed multi-energy coupled complementary hydrogen production system is established. Under the premise of meeting the operation constraints and the stable hydrogen production constraints, the optimal hydrogen production plan is obtained to maximize hydrogen production. Attached Figure Description

[0035] Figure 1 A flowchart illustrating the optimized operation method of a multi-energy coupled complementary hydrogen production system provided in this embodiment of the invention;

[0036] Figure 2 This is a schematic diagram of the structure of a multi-energy coupled complementary hydrogen production system provided in an embodiment of the present invention;

[0037] Figure 3 The diagram shows the operation results of the multi-energy coupled complementary hydrogen production system provided in the embodiment of the present invention. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0039] In this invention, the terms "first," "second," etc. (if present) in the invention and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0040] Figure 1 A flowchart illustrating the optimized operation method of a multi-energy coupled complementary hydrogen production system provided in an embodiment of the present invention. (See also...) Figure 1 , combined Figures 2-3 The optimized operation method of the multi-energy coupled complementary hydrogen production system in this embodiment is described in detail. The method includes operations S1-S4.

[0041] Operation S1 establishes sub-models for hydrogen production via water electrolysis, biomass, and natural gas.

[0042] The system utilizes a complementary coupling of water, biomass, and natural gas to produce hydrogen. Accordingly, the system includes a water electrolysis hydrogen production module, a biomass hydrogen production module, and a natural gas hydrogen production module, and individual hydrogen production models for each of these three modules should be established.

[0043] The sub-model for hydrogen production by water electrolysis is as follows:

[0044] P t pv ≥P t pv_ele +P t pv_es (1)

[0045] P t ele =P t pv_ele +P t es_ele (2)

[0046] I t cell =f(P t ele′ (3)

[0047]

[0048]

[0049]

[0050]

[0051]

[0052] Among them, P t pv To contribute to photovoltaic power, P t pv _ ele The power P is directly supplied by photovoltaics to the water electrolysis hydrogen production module. t pv _ es To store electrical energy in the energy storage module, P t ele P is the power of the water electrolysis hydrogen production module. t es _ ele The power provided to the energy storage module P is the operating current of the water electrolysis hydrogen production module. t ele′ represents the actual power used for hydrogen production by the water electrolysis hydrogen production module, f(·) represents the functional relationship between the output power of the water electrolysis hydrogen production module and the operating current, k1 is the unit conversion factor characterizing W→MW, and N cell For the number of electrolytic cells, The voltage is the operating voltage of the water electrolysis hydrogen production module, where E is the Nernst voltage. For ohmic overvoltage, To activate overvoltage, U rev Where is the reversible voltage, R is the ideal gas constant, and T is the reversible voltage. cell The electrolytic cell operating temperature is given, n is the number of moles of electrons participating in the entire reaction, and F is the Faraday coefficient. For hydrogen partial pressure, The partial pressure of oxygen. R represents the activity of water. cell For internal equivalent ohmic current, α an The anode charge transfer coefficient, Let i be the current density. an Where α is the anode current density cat i is the cathode charge transfer coefficient. cat Where A is the cathode current density. cell The effective area of ​​the electrolytic cell. The hydrogen production rate of the water electrolysis hydrogen production module is given by k2, where k2 is the unit conversion factor characterizing the change from mol / s to Nm3 / s, and h is the hydrogen production rate. F For Faraday efficiency, This represents the oxygen production of the water electrolysis hydrogen production module.

[0053] Equations (1) and (2) indicate that photovoltaic power can directly supply electricity to the water electrolysis hydrogen production module or store it in the energy storage module, while the electricity required for water electrolysis hydrogen production comes from the photovoltaic or energy storage module. Equation (3) indicates the output model of the water electrolysis hydrogen production module as the relationship between power and current, as shown in Equation (4). Equation (5) indicates the operating voltage of the water electrolysis hydrogen production module. Including Nernst voltage E and Ohmic overvoltage Activation overvoltage Equation (6) describes the relationship between current and current density. The hydrogen production and oxygen production of the water electrolysis hydrogen production module are shown in Equations (7) and (8), respectively.

[0054] In this embodiment, a thermodynamic equilibrium model is used to model the biomass hydrogen production module. It is assumed that the pyrolysis products burn in the reduction zone and reach equilibrium before leaving the gasifier. Using wood as biomass, the global gasification reaction equation is:

[0055] CH1. 44 O 0.66+wH2O+mO2+3.76mN2=x1H2+x2CO+x3CO2+x4H2O+x5CH4+3.76mN2 (9)

[0056] Where w is the moisture content per kmol of wood, m is the oxygen consumption coefficient of the biomass hydrogen production process, x1 is the hydrogen production coefficient of the biomass device, x2 is the corresponding coefficient for carbon monoxide production by biomass gasification, x3 is the corresponding coefficient for carbon dioxide production by biomass gasification, x4 is the corresponding coefficient for water vapor production by biomass gasification, and x5 is the methanogenesis coefficient of the biomass device.

[0057] Based on the chemical reactions occurring in the gasifier, the element conservation equations are written, including the conservation of carbon, hydrogen, and oxygen, as shown in equations (10), (11), and (12), respectively:

[0058] 1 = x² + x³ + x⁵ (10)

[0059] 2w + 1.44 = 2x1 + 2x4 + 4x5 (11)

[0060] w + 0.66 + 2m = x² + 2x³ + x⁴ (12)

[0061] The equilibrium constant of the reaction can be expressed as:

[0062]

[0063]

[0064] Assuming the reaction process is adiabatic, the heat balance equation for the gasification process can be expressed as:

[0065]

[0066] in, The heat of wood formation, The heat of formation of liquid water, The heat of oxygen formation. The heat of formation of nitrogen gas. The heat of hydrogen formation. The heat of formation of carbon monoxide. The heat of formation of carbon dioxide. The heat of formation of water vapor. The heat of formation of methane. This refers to the specific heat capacity of hydrogen. The specific heat capacity of carbon monoxide. This represents the specific heat capacity of carbon dioxide. The specific heat capacity of water, The specific heat capacity of methane, ΔT is the specific heat capacity of nitrogen, and ΔT is the difference between the vaporization temperature in the reduction zone and the ambient temperature.

[0067] In addition, the equilibrium constant K is the temperature T bio The function can be expressed in terms of Gibbs free energy:

[0068]

[0069]

[0070]

[0071] Where ΔG is the standard Gibbs free energy of formation, and ΔH is the enthalpy change between reactants and products.

[0072] By solving the above equations for element conservation, heat conservation, and chemical equilibrium, i.e., equations (9) to (18), the calculation results of the thermodynamic equilibrium model can be obtained, thereby determining the oxygen consumption, hydrogen production, and hydrocarbon fuel production of biomass hydrogen production:

[0073]

[0074]

[0075]

[0076] in, This refers to the oxygen consumption in the biomass hydrogen production process. This represents the total consumption of biomass. The hydrogen production capacity of the biomass hydrogen production module. This represents the actual amount of biomass consumed for hydrogen production. Hydrocarbon fuel produced by biomass gasification.

[0077] The natural gas module employs chemical loop autothermal reforming for hydrogen production. The autothermal reforming unit consists of an air reactor and a fuel reactor. In the fuel reactor, fuel gas is oxidized by an oxygen carrier (oxidized state denoted as MeO, reduced state denoted as Me) into a hydrogen-containing gas mixture, while MeO is reduced to Me and transferred to the air reactor. In the air reactor, Me is converted back to MeO through a strongly exothermic reaction. The heat required for the endothermic reaction in the fuel reactor must be provided by the circulating solids produced at a higher temperature in the air reactor. The gaseous products of the air and fuel reactors can be calculated using the chemical reaction equilibrium equation, mass balance equation, and heat balance equation based on the minimum Gibbs energy.

[0078]

[0079] ΔX s =X AR -XFR (twenty three)

[0080]

[0081]

[0082]

[0083] Where, N s For oxygen-carrying circulation flow rate, y NiO_ox M represents the fraction of NiO in the oxygen carrier after complete oxidation. NiO Where ΔX is the molecular weight of NiO. s Due to the difference in oxygen carrier conversion rates between fuel reactors and air reactors, The amount of oxygen transferred per mole of feed through a chemical reaction with NiO; N gas X represents the input hydrocarbon fuel quantity, taken as 1 mol / s; AR X represents the conversion rate of the oxygen carrier at the outlet of the air reactor. FR The conversion rate of the oxygen carrier at the outlet of the fuel reactor. This represents the molar flow rate of oxygen in the air reactor. The conversion rate of oxygen consumed in the air reactor. These represent the molar flow rate and enthalpy of reactant j in the natural gas-to-hydrogen module, respectively. Here, ΔH represents the molar flow rate and enthalpy of product i from the natural gas to hydrogen module, respectively; ΔH is the enthalpy change between reactants and products; h j h is the enthalpy of component j. 0j Let T be the enthalpy of component j at 298 K. gas C represents the gas temperature. pi (·) represents the heat capacity of component j. When the molar flow rate of natural gas entering the natural gas to hydrogen production module is 1 mol / s, These are equal to the molar flow rates of the reactant oxygen and the product hydrogen, respectively.

[0084] Equations (22)-(23) correspond to the mass balance equations of the air reactor and (24) corresponds to the mass balance equation of the fuel reactor, with NiO used as the oxygen carrier. Equation (25) expresses the relationship between the enthalpy of the reactants, the enthalpy of the products, and the enthalpy change. When ΔH = 0, the system reaches the self-heating state.

[0085] By solving the above equations, i.e., equations (19) to (26), the gas production of natural gas to hydrogen production is determined, including the oxygen consumption and hydrogen production of the natural gas to hydrogen production module:

[0086]

[0087]

[0088] in, These are the oxygen consumption and oxygen consumption coefficient of the natural gas-to-hydrogen module. This represents the total consumption of natural gas. These are the hydrogen production capacity and hydrogen production coefficient of the natural gas-to-hydrogen module, respectively.

[0089] Operation S2 establishes a constraint on the complementary utilization of materials based on the principle that oxygen produced by water electrolysis is used in complementary biomass hydrogen production and natural gas hydrogen production, and hydrocarbon fuel produced by biomass hydrogen production is used in complementary natural gas hydrogen production. It also establishes a constraint on the complementary utilization of heat based on the principle that biomass hydrogen production and natural gas hydrogen production are coupled to form a global thermal balance.

[0090] The main purpose of multi-energy coupling and complementary hydrogen production is to effectively utilize the complementarity of matter and energy to improve energy efficiency. (See also...) Figure 2 The illustrated multi-energy coupled complementary hydrogen production system incorporates solar energy, biomass, and natural gas as inputs. The hydrogen outputs from each module are coupled to meet stable hydrogen production requirements. The complementary utilization of resources includes both oxygen and hydrocarbon fuels.

[0091] Oxygen coupling is the core and link in a multi-energy coupled complementary hydrogen production system. Oxygen is a byproduct of the water electrolysis hydrogen production module. It can be divided into three parts: storage in the oxygen storage module. Direct supply to biomass hydrogen production module Direct supply of natural gas to hydrogen production module As shown in equation (29). The oxygen consumed by the biomass hydrogen production module. Oxygen consumed by the natural gas to hydrogen production module Both are provided by the water electrolysis hydrogen production module and the oxygen storage module as shown in equations (30) and (31).

[0092]

[0093]

[0094]

[0095] in, These refer to the amount of oxygen supplied by the oxygen storage module to the biomass module and the natural gas module, respectively.

[0096] Hydrocarbon fuel produced by biomass hydrogen production modules A portion is directly supplied to the natural gas-to-hydrogen module. A portion is stored in the gas storage module. As shown in equation (32). The fuel required for the natural gas to hydrogen production module is purchased externally. Biomass hydrogen production module and gas storage module Provided, as shown in Equation (33). Equation (34) specifies the upper limit for the purchase of natural gas. Restrictions have been imposed.

[0097]

[0098]

[0099]

[0100] The biomass hydrogen production module is coupled with the natural gas hydrogen production module to achieve global thermal equilibrium. The high-temperature gas generated by the gasification of the biomass hydrogen production module is used to preheat the intake gas of the natural gas hydrogen production module. The preheated intake gas includes oxygen from the water electrolysis hydrogen production module, methane from the biomass hydrogen production module and external supply, and water vapor.

[0101] The system utilizes the high temperature generated during biomass hydrogen production through gasification to preheat the gas in the natural gas hydrogen production inlet channel. The constraint for the complementary utilization of heat is as follows:

[0102]

[0103]

[0104]

[0105] T 0 ≤T t gas ≤T bio _ out (38)

[0106] in, These represent the molar flow rate and enthalpy change of product i from the biomass hydrogen production module, respectively. These represent the molar flow rate and enthalpy change of reactant j in the biomass hydrogen production module, respectively. These represent the oxygen consumption coefficient and hydrogen production coefficient of the natural gas to hydrogen module, respectively, T. t gas Let T be the feed temperature of the natural gas to hydrogen production module, F1(·) represent the functional relationship between the feed temperature and oxygen consumption, and F2(·) represent the functional relationship between the feed temperature and hydrogen production rate. 0 For ambient temperature, T bio _ out The temperature at which hydrogen is produced from biomass.

[0107] Equation (35) shows that the heat provided by the gas exiting the biomass module needs to be greater than the heat obtained by the gas entering the natural gas module. Considering the complementary use of heat, the feed temperature of the natural gas module changes, and the coefficient... Will change with temperature Tt gas The temperature changes as shown in equations (36)-(37). Equation (38) limits the range of variation of the feed temperature.

[0108] Operation S3, based on the electrolysis hydrogen production sub-model, biomass hydrogen production sub-model, natural gas hydrogen production sub-model, material complementary utilization constraints, heat complementary utilization constraints, and system operation constraints, constructs a multi-energy coupled complementary hydrogen production optimization model with the goal of maximizing stable hydrogen production.

[0109] According to an embodiment of the present invention, the system operation constraints include: start-up and shutdown constraints of each hydrogen production module in the system, operating status constraints of each hydrogen production module, operation constraints of the energy storage module, operation constraints of the oxygen storage module, operation constraints of the gas storage module, and stable hydrogen production constraints.

[0110] 1) Start-up and shutdown constraints for the hydrogen production module:

[0111] Considering the startup characteristics of each hydrogen production module, the reactor cannot produce hydrogen until it is heated to a certain temperature, and this preheating time is usually not negligible. The hydrogen production module enters the startup state τ cycles after the startup action occurs (s changes from 0 to 1). The hydrogen production module shuts down relatively quickly; once the supply stops, hydrogen production is interrupted.

[0112] In summary, the mathematical model for the start-up and shutdown characteristics of the hydrogen production module considering the start-up delay is given by equations (39) to (41). As shown in equation (42), the initial state of s is determined by the working state during the last period of the day. In addition, considering the impact of start-up and shutdown operations on the module's life cycle, the upper limit of the number of start-up and shutdown operations per day is limited in equations (43) and (44).

[0113]

[0114]

[0115]

[0116] s0 = s T (42)

[0117]

[0118]

[0119] in, For module start / stop actions, only the first action period is set to 1; s boot_max / s shut_max This is the maximum number of times a module can be started and stopped in a day.

[0120] 2) Operating status constraints of the hydrogen production module:

[0121] Furthermore, the working state constraints of each hydrogen production module include working range constraints, ramping constraints, and the relationship constraints between module feed and the raw materials actually used for hydrogen production, as shown in equations (45) to (47), respectively.

[0122]

[0123] |R t -R t-1 |≤s t ΔR max +(1-s t )R max (46)

[0124] R t ′=s t R t (47)

[0125] Considering the module start-up delay, the operating range constraints of the three hydrogen production modules are uniformly expressed as Equation (45); Equation (46) is the ramp-up constraint; Equation (47) represents the relationship constraint between the module feed and the actual raw materials used for hydrogen production. R is the feed rate of the three modules; R max and R min These represent the upper and lower limits of the module's feed rate, respectively; ΔR max This represents the maximum ramp rate for changes in module feed.

[0126] 3) Operational constraints of energy storage devices, including:

[0127] 3.1) Operational constraints of energy storage modules:

[0128]

[0129] in, This represents the current capacity of the energy storage module. This is the upper limit of the energy storage module capacity. P is a 0-1 state variable for the energy storage module. es_max This represents the upper limit of the power of the energy storage module.

[0130] 3.2) Operational constraints of the oxygen storage module:

[0131]

[0132] in, This represents the current capacity of the oxygen storage module. This is the upper limit of the oxygen storage module capacity. N is a 0-1 state variable for the oxygen storage module. os_max This sets the upper limit for the oxygen storage / release rate of the oxygen storage module.

[0133] 3.3) Operational constraints of the gas storage module:

[0134]

[0135] in, This represents the current capacity of the gas storage module. This is the upper limit of the gas storage module capacity. N represents the 0-1 state variable of the gas storage module. gs_max This is the upper limit for the rate at which the gas storage module stores / releases gas.

[0136] 4) Constraints on stable hydrogen production:

[0137]

[0138] in, To meet hydrogen production needs, e t To account for fluctuations in hydrogen production, equation (51) sets the hydrogen production to fluctuate within 2% of the demand.

[0139] Operation S4 linearizes the nonlinear terms in the multi-energy coupled complementary hydrogen production optimization model and then solves the solution to obtain the optimal hydrogen production plan, enabling the system to produce hydrogen according to the optimal hydrogen production plan.

[0140] The optimization model contains nonlinear constraints, such as equations (5), (27)-(28), and (47), which will lead to computational difficulties. Therefore, the above nonlinear terms are linearized. Specifically, the linearization process in operation S4 includes linearizing the constraints on the relationship between the water electrolysis hydrogen production sub-model, the natural gas hydrogen production sub-model, and the module feed and the actual raw materials used for hydrogen production.

[0141] The output model of the water electrolysis hydrogen production module is processed using a piecewise linearization method, as shown in equation (52):

[0142]

[0143] Where N is the total number of segments, g n h n These are the principal coefficient and constant coefficient of each segment, δ. n,t For each segment, the corresponding state variables are... These are the inflection points of the independent variables for each segment.

[0144] The piecewise linearization method is used to process the oxygen consumption model and hydrogen production model of the natural gas hydrogen production module. Taking the oxygen consumption equation as an example, it is shown in equation (53):

[0145]

[0146] In this context, the symbols “+” and “-” represent the two quadratic terms in the first row of equation (53), respectively; δ λ,t Δ λ,tThese are the introduced continuous auxiliary variables and binary auxiliary variables, ψ, respectively. λ a λ b λ It is a constant parameter.

[0147] According to an embodiment of the present invention, in operation S4, the Big M method is used to linearize the constraint on the relationship between the module feed and the actual feedstock used for hydrogen production. By introducing artificial variables and using a very large M as coefficients, the problem is transformed into a mixed-integer linear problem:

[0148]

[0149] Using the linearization techniques described above, the established multi-energy coupled complementary hydrogen production optimization model is transformed into a mixed-integer linear programming problem that is easy to solve using existing solvers, as follows:

[0150]

[0151] st(1), (2), (7), (8), (25), (33)-(50), (52)-(54) (55)

[0152] Furthermore, the optimal hydrogen production plan can be obtained by solving the problem using the software GUROBI on the MATLAB platform. This optimal hydrogen production plan simultaneously utilizes the complementarity of matter and heat to improve energy efficiency and reduce carbon emissions.

[0153] In this embodiment, the established multi-energy coupled complementary hydrogen production optimization model was calculated, with a time interval of 15 minutes, resulting in scheduling results for 96 time periods. The main technical indicators of the water electrolysis hydrogen production module, biomass hydrogen production module, and natural gas hydrogen production module are shown in Table 1. The maximum feed rates of each module are 6MW, 18mol / s, and 3.5mol / s, respectively. The maximum capacities of the electricity storage, oxygen storage, and gas storage modules are 5MW·h, 5000Nm³, and 5000Nm³, respectively. 3 200Nm 3 .

[0154] Table 1

[0155]

[0156] Based on this, the optimal hydrogen production plan is as follows: Figure 3 As shown in Table 2, the energy utilization efficiency calculation results indicate that the energy utilization efficiency of the method in this embodiment is improved by 9.57% compared with hydrogen production from a single energy source.

[0157] Table 2

[0158]

[0159] The carbon emission calculation results are shown in Table 3, indicating that carbon emissions are reduced by 43% compared with existing industrial hydrogen production technologies.

[0160] Table 3

[0161]

[0162] This invention also provides a multi-energy coupled complementary hydrogen production system, which employs, for example... Figures 1-3 The optimal hydrogen production plan is obtained by the optimized operation method of the multi-energy coupled complementary hydrogen production system shown.

[0163] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An optimized operation method for a multi-energy coupled complementary hydrogen production system, characterized in that, The system utilizes a complementary coupling of water, biomass, and natural gas to produce hydrogen, and the method includes: S1. Establish sub-models for hydrogen production via water electrolysis, biomass, and natural gas. S2, with the principle that the oxygen produced by water electrolysis is complemented by biomass hydrogen production and natural gas hydrogen production, and the hydrocarbon fuel produced by biomass hydrogen production is complemented by natural gas hydrogen production, constructs a material complementarity utilization constraint; with the principle that biomass hydrogen production and natural gas hydrogen production are coupled to form a global thermal balance, constructs a heat complementarity utilization constraint. S3. Based on the aforementioned sub-models for hydrogen production through water electrolysis, biomass, and natural gas, as well as constraints on complementary utilization of materials, complementary utilization of heat, and system operation, a multi-energy coupled complementary hydrogen production optimization model is constructed with the goal of maximizing stable hydrogen production. S4. After linearizing the nonlinear terms in the multi-energy coupled complementary hydrogen production optimization model, the optimal hydrogen production plan is obtained, so that the system produces hydrogen according to the optimal hydrogen production plan. The biomass hydrogen production sub-model is as follows: in, This refers to the oxygen consumption in the biomass hydrogen production process. This represents the total consumption of biomass. The hydrogen production capacity of the biomass hydrogen production module. This represents the actual amount of biomass consumed for hydrogen production. Hydrocarbon fuel produced by biomass gasification The oxygen consumption coefficient is the oxygen consumption coefficient in the biomass hydrogen production process. The hydrogen production coefficient of the biomass plant, The methanogenesis coefficient of a biomass plant; oxygen consumption coefficient Hydrogen production coefficient and methanogenesis coefficient Calculated from the following relationship: In the formula, The moisture content per kmol of wood. The oxygen consumption coefficient is the oxygen consumption coefficient in the biomass hydrogen production process. The hydrogen production coefficient of the biomass plant, The corresponding coefficient for carbon monoxide production from biomass gasification. This represents the coefficient corresponding to the carbon dioxide production from biomass gasification. The corresponding coefficient for water vapor produced by biomass gasification. The methanogenesis coefficient of a biomass plant; , The equilibrium constant of the reaction, The heat of wood formation, The heat of formation of liquid water, The heat of oxygen formation. The heat of formation of nitrogen gas. The heat of hydrogen formation. The heat of formation of carbon monoxide. The heat of formation of carbon dioxide. The heat of formation of water vapor. The heat of formation of methane. This refers to the specific heat capacity of hydrogen. The specific heat capacity of carbon monoxide. This represents the specific heat capacity of carbon dioxide. The specific heat capacity of water, The specific heat capacity of methane, The specific heat capacity of nitrogen is... This is the difference between the vaporization temperature in the reduction zone and the ambient temperature. It is the equilibrium constant. Generate the Gibbs function for the standard. The enthalpy change between reactants and products. , For temperature; The natural gas hydrogen production sub-model is as follows: in, , These are the oxygen consumption and oxygen consumption coefficient of the natural gas-to-hydrogen module. This represents the total consumption of natural gas. , These are the hydrogen production capacity and hydrogen production coefficient of the natural gas-to-hydrogen module, respectively. oxygen consumption coefficient Hydrogen production coefficient Calculated from the following relationship: In the formula, This refers to the oxygen-carrying circulation flow rate. This represents the fraction of NiO in the oxygen carrier after complete oxidation. The molecular weight of NiO is... Due to the difference in oxygen carrier conversion rates between fuel reactors and air reactors, The amount of oxygen transferred per mole of feed through chemical reaction with NiO; The input hydrocarbon fuel quantity is taken as 1 mol / s; The conversion rate of the oxygen carrier at the outlet of the air reactor. The conversion rate of the oxygen carrier at the outlet of the fuel reactor. This represents the molar flow rate of oxygen in the air reactor. The conversion rate of oxygen consumed in the air reactor. , Reactants from the natural gas to hydrogen module j molar flow rate, enthalpy , The products of the natural gas to hydrogen production module are respectively i molar flow rate, enthalpy The enthalpy change between reactants and products. Components j enthalpy value, Components j Enthalpy at 298K For gas temperature, Components j The heat capacity; The constraints on the complementary utilization of materials are: in, The oxygen production of the water electrolysis hydrogen production module, , , The amount of oxygen stored in the oxygen storage module, directly supplied to the biomass hydrogen production module, and directly supplied to the natural gas hydrogen production module are determined by the water electrolysis hydrogen production module. , These refer to the amount of oxygen supplied by the oxygen storage module to the biomass module and the natural gas module, respectively. , The amounts of hydrocarbon fuel directly supplied by the biomass hydrogen production module to the natural gas hydrogen production module and stored in the gas storage module are respectively the amount of hydrocarbon fuel that the biomass hydrogen production module directly supplies to the natural gas hydrogen production module and the amount that is stored in the gas storage module. , These represent the amount of hydrocarbon fuel purchased from the natural gas hydrogen production module and the amount of hydrocarbon fuel provided by the gas storage module, respectively. A purchase cap on hydrocarbon fuels; The constraint for the complementary use of heat is: in, , The products of the biomass hydrogen production module are respectively i The molar flow rate and enthalpy change, , These are the reactants from the biomass hydrogen production module. j The molar flow rate and enthalpy change, , These are the oxygen consumption coefficient and hydrogen production coefficient of the natural gas to hydrogen module, respectively. This refers to the feed temperature of the natural gas to hydrogen production module. This represents the functional relationship between the feed temperature and oxygen consumption in natural gas-to-hydrogen production. This represents the functional relationship between the feed temperature and the hydrogen production rate in natural gas-to-hydrogen production. For ambient temperature, The temperature at which hydrogen is produced from biomass.

2. The optimized operation method of the multi-energy coupled complementary hydrogen production system as described in claim 1, characterized in that, System operation constraints include: start-up and shutdown constraints for each hydrogen production module, operating status constraints for each hydrogen production module, operation constraints for the energy storage module, operation constraints for the oxygen storage module, operation constraints for the gas storage module, and stable hydrogen production constraints.

3. The optimized operation method of the multi-energy coupled complementary hydrogen production system as described in claim 2, characterized in that, The operating status constraints of each hydrogen production module include operating range constraints, ramp-up constraints, and the relationship constraints between module feed and the raw materials actually used for hydrogen production. The linearization process in S4 includes linearizing the constraints on the relationship between the water electrolysis hydrogen production sub-model, the natural gas hydrogen production sub-model, the module feed, and the raw materials actually used for hydrogen production.

4. The optimized operation method of the multi-energy coupled complementary hydrogen production system as described in claim 3, characterized in that, In S4, the Big M method is used to linearize the constraint on the relationship between the module feed and the raw materials actually used for hydrogen production.

5. A multi-energy coupled complementary hydrogen production system, characterized in that, The system uses the optimal hydrogen production plan obtained by the optimized operation method of the multi-energy coupled complementary hydrogen production system as described in any one of claims 1-4.

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