CN109248541B - Hydrogen recovery system collaborative optimization method and system - Google Patents

Hydrogen recovery system collaborative optimization method and system Download PDF

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CN109248541B
CN109248541B CN201710563835.1A CN201710563835A CN109248541B CN 109248541 B CN109248541 B CN 109248541B CN 201710563835 A CN201710563835 A CN 201710563835A CN 109248541 B CN109248541 B CN 109248541B
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pressure swing
swing adsorption
hydrogen
membrane separation
unit
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CN109248541A (en
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王阳峰
张英
张龙
张胜中
孟凡忠
高明
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Sinopec Dalian Petrochemical Research Institute Co ltd
China Petroleum and Chemical Corp
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China Petroleum and Chemical Corp
Sinopec Dalian Research Institute of Petroleum and Petrochemicals
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
    • B01D53/04—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography with stationary adsorbents
    • B01D53/047—Pressure swing adsorption
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/22—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by diffusion
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
    • C01B3/50—Separation of hydrogen or hydrogen containing gases from gaseous mixtures, e.g. purification
    • C01B3/56—Separation of hydrogen or hydrogen containing gases from gaseous mixtures, e.g. purification by contacting with solids; Regeneration of used solids
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation

Abstract

The invention provides a hydrogen recovery system collaborative optimization method and a system, wherein the method comprises the following steps: establishing a mathematical simulation model of a hydrogen recovery system, wherein the hydrogen recovery system comprises a pressure swing adsorption unit and a membrane separation unit; carrying out mathematical solving on a mathematical simulation model of a hydrogen recovery system to obtain the composition and flow of product hydrogen output by the hydrogen recovery system; judging whether the composition and the flow of product hydrogen in the solution result meet preset calculation requirements or not, if so, establishing an integral optimization model of the hydrogen recovery system, and respectively establishing subsystem optimization models of a pressure swing adsorption unit and a membrane separation unit in the hydrogen recovery system; and respectively carrying out optimization solution on the subsystem optimization models of the pressure swing adsorption unit and the membrane separation unit, and determining the optimization solution result of the overall optimization model according to the optimization solution result of each subsystem optimization model. The present invention can maximize the hydrogen recovery efficiency.

Description

Hydrogen recovery system collaborative optimization method and system
Technical Field
The invention relates to the technical field of refinery hydrogen resource optimization research, in particular to a hydrogen recovery system collaborative optimization method and system.
Background
With the trend of aggravation and deterioration of processed crude oil and the enhancement of upgrading requirements of product quality, hydrogen is increasingly important for ensuring the production of qualified products in refineries, and the high hydrogen production cost and the high hydrogen production device investment make the recovery of hydrogen particularly important.
For refineries, the common hydrogen recovery technologies mainly include pressure swing adsorption technology and membrane separation technology. The pressure swing adsorption method is to utilize silica gel, active carbon, molecular sieve and other solid adsorbent in vertical pressure container to adsorb various impurities in mixed gas selectively so as to separate gas. The membrane separation method is a process of enriching gases on two sides of a membrane by taking the gas partial pressure difference on the two sides of the membrane as a driving force and utilizing the difference of permeation rates of different gases in the membrane to realize separation.
The optimization research of the hydrogen recovery device of the current refinery mainly comprises the following aspects:
(1) in production operation, technicians conduct optimization operation on the hydrogen recovery device in charge of the hydrogen recovery device according to experience and theoretical guidance. In general, they have less intensive research on the performance characteristics of other hydrogen recovery devices in a company, cannot consider the cooperative optimization among the hydrogen recovery devices in the whole company range from the system point of view, and cannot fully exert the effective total force of the hydrogen recovery devices.
(2) Optimization research of various hydrogen recovery devices. The main emphasis is on the optimization of the device, the combination optimization, raw material optimization and the like among the hydrogen recovery devices are not fully researched, and the efficient and economic recovery of the hydrogen is not optimized from the perspective of the whole hydrogen recovery system.
(3) Optimizing and researching a refinery hydrogen resource system. The hydrogen recovery part mainly focuses on simple measurement and calculation of energy consumption and hydrogen recovery efficiency of the hydrogen recovery device, and optimization operation analysis, inter-device collaborative optimization research, device feeding adaptability analysis and the like of the hydrogen recovery device cannot be carried out.
Therefore, it is a research direction of those skilled in the art to provide an efficient hydrogen recovery system optimization method to solve the problems of the prior art.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a hydrogen recovery system collaborative optimization method and system, which can maximize the hydrogen recovery benefit and improve the economic benefit of enterprises.
Specifically, the invention provides the following technical scheme:
in a first aspect, the present invention provides a hydrogen recovery system collaborative optimization method, including:
step S1: establishing a mathematical simulation model of a hydrogen recovery system, the hydrogen recovery system comprising: at least one of a pressure swing adsorption unit and a membrane separation unit; the pressure swing adsorption unit comprises at least one pressure swing adsorption device, the membrane separation unit comprises at least one membrane separation device, and a compressor module is selectively arranged in the pressure swing adsorption device and the membrane separation device according to preset requirements;
step S2: setting flow rates of hydrogen-containing streams entering all pressure swing adsorption devices in the pressure swing adsorption unit and all membrane separation devices in the membrane separation unit according to design parameters and operation parameters of the pressure swing adsorption unit and the membrane separation unit in the hydrogen recovery system, setting initial values of adsorption equilibrium kinetic parameters of all pressure swing adsorption devices in the pressure swing adsorption unit, and setting initial values of component permeation rate parameters of all membrane separation devices in the membrane separation unit; wherein the hydrogen-containing stream in the hydrogen recovery system comprises a hydrogen-containing stream entering and exiting the pressure swing adsorption unit, the membrane separation unit, and a hydrogen-containing stream discharged to the refinery gas system;
step S3: performing mathematical solution on a mathematical simulation model of the hydrogen recovery system to obtain the composition and flow of product hydrogen output by the hydrogen recovery system;
step S4: judging whether the composition and the flow of the product hydrogen in the solving result of the step S3 meet the preset calculation requirement, if so, executing a step S5; if the preset calculation requirement is not met and the iteration number does not reach the preset limit number, correcting one or more of the flow rate of the hydrogen-containing stream entering each pressure swing adsorption device in the pressure swing adsorption unit and entering each membrane separation device in the membrane separation unit, the initial values of the adsorption equilibrium kinetic parameters of each pressure swing adsorption device in the pressure swing adsorption unit and the initial values of the component permeation rate parameters of each membrane separation device in the membrane separation unit in the step S2, and returning to the step S3; if the preset calculation requirement is not met and the iteration number reaches the preset limit number, executing step S5;
step S5: establishing an integral optimization model of the hydrogen recovery system, and respectively establishing subsystem optimization models of a pressure swing adsorption unit and a membrane separation unit in the hydrogen recovery system;
step S6: initializing an integral optimization model of the hydrogen recovery system, and respectively initializing subsystem optimization models of a pressure swing adsorption unit and a membrane separation unit; wherein initializing the global optimization model of the hydrogen recovery system comprises: setting a first iteration number upper limit of an integral optimization model, and flow rates of hydrogen-containing streams entering all pressure swing adsorption devices in the pressure swing adsorption unit and all membrane separation devices in the membrane separation unit; wherein initializing the subsystem optimization models of the pressure swing adsorption unit and the membrane separation unit comprises: setting a second iteration upper limit of each subsystem optimization model, and receiving the flow of hydrogen-containing streams which enter each pressure swing adsorption device in the pressure swing adsorption unit and each membrane separation device in the membrane separation unit and are set by the integral optimization model;
step S7: respectively carrying out optimization solution on the subsystem optimization models of the pressure swing adsorption unit and the membrane separation unit, and determining the optimization solution result of the overall optimization model according to the optimization solution result of each subsystem optimization model;
wherein the objective function of the overall optimization model is as follows: maximizing product hydrogen recovery benefits of a hydrogen recovery system, wherein the product hydrogen recovery benefits of the hydrogen recovery system are equal to the sum of the product hydrogen recovery benefits of the pressure swing adsorption unit and the membrane separation unit;
the constraint conditions of the overall optimization model comprise: the difference between the preset flow rate of the hydrogen-containing stream entering the pressure swing adsorption unit and the flow rate of the hydrogen-containing stream actually processed by the pressure swing adsorption unit in the hydrogen recovery system is smaller than a preset relaxation factor, and the difference between the preset flow rate of the hydrogen-containing stream entering the membrane separation unit and the flow rate of the hydrogen-containing stream actually processed by the membrane separation unit in the hydrogen recovery system is smaller than a preset relaxation factor; the constraints of the overall optimization model further comprise: the pure hydrogen amount in the hydrogen-containing stream of the hydrogen recovery system is more than or equal to the pure hydrogen amount in the product hydrogen obtained by the pressure swing adsorption unit and the membrane separation unit; the pure hydrogen amount in the hydrogen-containing stream of the hydrogen recovery system is equal to the sum of the pure hydrogen amount in the product hydrogen obtained by the pressure swing adsorption unit and the membrane separation unit and the pure hydrogen content in the hydrogen-containing stream discharged to the gas system;
the objective function of the optimization model of the pressure swing adsorption unit subsystem is as follows: the minimum difference value between the preset flow rate of the hydrogen-containing stream entering the pressure swing adsorption unit in the hydrogen recovery system and the flow rate of the hydrogen-containing stream actually treated by the pressure swing adsorption unit;
the objective function of the optimization model of the membrane separation unit subsystem is as follows: the minimum difference value of the preset flow rate of the hydrogen-containing stream entering the membrane separation unit and the flow rate of the hydrogen-containing stream actually processed by the membrane separation unit in the hydrogen recovery system;
the constraint conditions of the pressure swing adsorption unit subsystem optimization model are as follows: the inlet and outlet of each pressure swing adsorption device in the pressure swing adsorption unit meet the requirements of material conservation and component conservation, the pressure of the raw material gas is greater than or equal to the pressure requirement of the inlet of the pressure swing adsorption device, the processing load of the pressure swing adsorption device is within the processing capacity range of the pressure swing adsorption device, the hydrogen and hydrogen purity of the product is greater than or equal to a preset purity value, and the preset component gas in the raw material gas cannot penetrate through a preset adsorption layer;
the constraint conditions of the optimization model of the membrane separation unit subsystem are as follows: the inlet and outlet of each membrane separation device in the membrane separation unit meet the requirements of material conservation and component conservation, the pressure of the raw material gas is greater than or equal to the pressure requirement of the inlet of the membrane separation device, the processing load of the membrane separation device is within the processing capacity range of the membrane separation device, and the raw material gas does not contain specified gas components;
step S8: judging whether the optimization solving result of the integral optimization model is converged, and if so, ending the optimization solving process of the hydrogen recovery system; if the iteration times reach the first iteration time upper limit without convergence, ending the optimization solving process of the hydrogen recovery system; if not, and the iteration number does not reach the first iteration number upper limit, returning to the step S7 to continue the optimization solution until the optimization models of the subsystems reach the second iteration number upper limit.
Further, the design parameters of the pressure swing adsorption unit and the membrane separation unit in the hydrogen recovery system include: the height, internal diameter, temperature, pressure, processing capacity, adsorbent loading, type, pore volume and specific surface area of each pressure swing adsorption unit; the design temperature, pressure, selectivity and processing capacity of each membrane separation unit; limiting the processing load of the compressor module in each pressure swing adsorption unit; process load limitations of the compressor modules in each membrane separation unit;
the operating parameters of the pressure swing adsorption unit and the membrane separation unit in the hydrogen recovery system comprise: the operating temperature, pressure and adsorption time of each pressure swing adsorption unit; the operating temperature and pressure of each membrane separation device; flow rate, composition and pressure of the hydrogen-containing stream.
Further, establishing a mathematical simulation model of the hydrogen recovery system, comprising:
and respectively establishing a mathematical simulation model of each pressure swing adsorption device in the pressure swing adsorption unit, a mathematical simulation model of each membrane separation device in the membrane separation unit, a mathematical simulation model of a compressor module in each pressure swing adsorption device and a mathematical simulation model of a compressor module in each membrane separation device.
Further, establishing a mathematical simulation model of each pressure swing adsorption device in the pressure swing adsorption unit, comprising:
establishing a mathematical simulation model of each pressure swing adsorption device in the pressure swing adsorption unit by adopting an adsorption equilibrium equation, a mass transfer rate equation and a total mass transfer equilibrium equation;
wherein the adsorption equilibrium equation is:
Figure BDA0001347787010000041
wherein, thetaiRepresenting the coverage rate of a gas component i on the adsorbent in the mixed gas to be measured; q. q.siRepresenting the equilibrium adsorption quantity of a gas component i in the mixed gas to be measured on the adsorbent; q. q.smax,iRepresenting the maximum adsorption amount of the gas component i in the mixed gas to be measured on the adsorbent; b isiRepresents the langmuir adsorption constant of gas component i on the adsorbent; b isjRepresents the langmuir adsorption constant of gas component j on the adsorbent; piRepresenting the partial pressure of a gas component i in the mixed gas to be measured; pjWhich represents the partial pressure of the gas component j in the mixed gas to be measured.
Further, establishing a mathematical simulation model of each pressure swing adsorption device in the pressure swing adsorption unit, comprising:
establishing a mathematical simulation model of each pressure swing adsorption device in the pressure swing adsorption unit by adopting an adsorption equilibrium equation, a mass transfer rate equation and a total mass transfer equilibrium equation;
wherein the adsorption equilibrium equation is:
Figure BDA0001347787010000051
Figure BDA0001347787010000052
Figure BDA0001347787010000053
wherein, thetaiRepresenting the coverage rate of a gas component i on a certain layer of adsorbent in the mixed gas to be adsorbed; piRepresents the partial pressure of the gas component i in the mixed gas to be adsorbed; b isiIndicating gasLangmuir adsorption constant of bulk component i on the layer of adsorbent; b isijRepresents the langmuir adsorption constant of component i on the layer of adsorbent in a binary gas mixture comprising component i and component j; kijRepresenting the degree of influence of component j on the adsorption of component i when a binary gas mixture comprising component i and component j is adsorbed on the layer of adsorbent; ki,mixRepresents the adsorption influence parameter of all gas components in the mixed gas to be adsorbed on the gas component i.
In a second aspect, the present invention further provides a hydrogen recovery system, including:
a first modeling unit for building a mathematical simulation model of a hydrogen recovery system, the hydrogen recovery system comprising: at least one of a pressure swing adsorption unit and a membrane separation unit; the pressure swing adsorption unit comprises at least one pressure swing adsorption device, the membrane separation unit comprises at least one membrane separation device, and a compressor module is selectively arranged in the pressure swing adsorption device and the membrane separation device according to preset requirements;
the first initial value setting unit is used for setting the flow of hydrogen-containing streams entering each pressure swing adsorption device in the pressure swing adsorption unit and each membrane separation device in the membrane separation unit according to the design parameters and the operation parameters of the pressure swing adsorption unit and the membrane separation unit in the hydrogen recovery system, setting the initial values of adsorption equilibrium kinetic parameters of each pressure swing adsorption device in the pressure swing adsorption unit, and setting the initial values of component permeation rate parameters of each membrane separation device in the membrane separation unit; wherein the hydrogen-containing stream in the hydrogen recovery system comprises a hydrogen-containing stream entering and exiting the pressure swing adsorption unit, the membrane separation unit, and a hydrogen-containing stream discharged to the refinery gas system;
the first solving unit is used for carrying out mathematical solving on a mathematical simulation model of the hydrogen recovery system to obtain the composition and the flow of product hydrogen output by the hydrogen recovery system;
the first judgment unit is used for judging whether the composition and the flow of the product hydrogen in the solving result of the first solving unit meet the preset calculation requirement or not, and if the composition and the flow of the product hydrogen in the solving result of the first solving unit meet the preset calculation requirement, the second modeling unit is executed; if the preset calculation requirement is not met and the iteration number does not reach the preset limit number, correcting one or more of the flow of the hydrogen-containing stream entering each pressure swing adsorption device in the pressure swing adsorption unit and each membrane separation device in the membrane separation unit, the initial values of the adsorption equilibrium kinetic parameters of each pressure swing adsorption device in the pressure swing adsorption unit and the initial values of the component permeation rate parameters of each membrane separation device in the membrane separation unit in the first initial value setting unit, and returning the corrected values to the first solving unit; if the preset calculation requirement is not met and the iteration number reaches the preset limit number, executing a second modeling unit;
the second modeling unit is used for establishing an integral optimization model of the hydrogen recovery system and respectively establishing subsystem optimization models of a pressure swing adsorption unit and a membrane separation unit in the hydrogen recovery system;
the second initial value setting unit is used for initializing the integral optimization model of the hydrogen recovery system and respectively initializing the subsystem optimization models of the pressure swing adsorption unit and the membrane separation unit; wherein initializing the global optimization model of the hydrogen recovery system comprises: setting a first iteration number upper limit of an integral optimization model, and flow rates of hydrogen-containing streams entering all pressure swing adsorption devices in the pressure swing adsorption unit and all membrane separation devices in the membrane separation unit; wherein initializing the subsystem optimization models of the pressure swing adsorption unit and the membrane separation unit comprises: setting a second iteration upper limit of each subsystem optimization model, and receiving the flow of hydrogen-containing streams which enter each pressure swing adsorption device in the pressure swing adsorption unit and each membrane separation device in the membrane separation unit and are set by the integral optimization model;
the second solving unit is used for respectively carrying out optimization solving on the subsystem optimization models of the pressure swing adsorption unit and the membrane separation unit and determining the optimization solving result of the overall optimization model according to the optimization solving result of each subsystem optimization model;
wherein the constraint conditions of the overall optimization model comprise: the difference between the preset flow rate of the hydrogen-containing stream entering the pressure swing adsorption unit and the flow rate of the hydrogen-containing stream actually processed by the pressure swing adsorption unit in the hydrogen recovery system is smaller than a preset relaxation factor, and the difference between the preset flow rate of the hydrogen-containing stream entering the membrane separation unit and the flow rate of the hydrogen-containing stream actually processed by the membrane separation unit in the hydrogen recovery system is smaller than a preset relaxation factor; the constraints of the overall optimization model further comprise: the pure hydrogen amount in the hydrogen-containing stream of the hydrogen recovery system is more than or equal to the pure hydrogen amount in the product hydrogen obtained by the pressure swing adsorption unit and the membrane separation unit; the pure hydrogen amount in the hydrogen-containing stream of the hydrogen recovery system is equal to the sum of the pure hydrogen amount in the product hydrogen obtained by the pressure swing adsorption unit and the membrane separation unit and the pure hydrogen content in the hydrogen-containing stream discharged to the gas system;
the objective function of the optimization model of the pressure swing adsorption unit subsystem is as follows: the minimum difference value between the preset flow rate of the hydrogen-containing stream entering the pressure swing adsorption unit in the hydrogen recovery system and the flow rate of the hydrogen-containing stream actually treated by the pressure swing adsorption unit;
the objective function of the optimization model of the membrane separation unit subsystem is as follows: the minimum difference value of the preset flow rate of the hydrogen-containing stream entering the membrane separation unit and the flow rate of the hydrogen-containing stream actually processed by the membrane separation unit in the hydrogen recovery system;
the constraint conditions of the pressure swing adsorption unit subsystem optimization model are as follows: the inlet and outlet of each pressure swing adsorption device in the pressure swing adsorption unit meet the requirements of material conservation and component conservation, the pressure of the raw material gas is greater than or equal to the pressure requirement of the inlet of the pressure swing adsorption device, the processing load of the pressure swing adsorption device is within the processing capacity range of the pressure swing adsorption device, the hydrogen and hydrogen purity of the product is greater than or equal to a preset purity value, and the preset component gas in the raw material gas cannot penetrate through a preset adsorption layer;
the constraint conditions of the optimization model of the membrane separation unit subsystem are as follows: the inlet and outlet of each membrane separation device in the membrane separation unit meet the requirements of material conservation and component conservation, the pressure of the raw material gas is greater than or equal to the pressure requirement of the inlet of the membrane separation device, the processing load of the membrane separation device is within the processing capacity range of the membrane separation device, and the raw material gas does not contain specified gas components;
the second judgment unit is used for judging whether the optimization solution result of the integral optimization model is converged or not, and if the optimization solution result is converged, the optimization solution process of the hydrogen recovery system is ended; if the iteration times reach the first iteration time upper limit without convergence, ending the optimization solving process of the hydrogen recovery system; and if the system is not converged and the iteration times do not reach the upper limit of the first iteration times, returning to the second solving unit to continue the optimization solving until the optimization model of each subsystem reaches the upper limit of the second iteration times.
Further, the design parameters of the pressure swing adsorption unit and the membrane separation unit in the hydrogen recovery system include: the height, internal diameter, temperature, pressure, processing capacity, adsorbent loading, type, pore volume and specific surface area of each pressure swing adsorption unit; the design temperature, pressure, selectivity and processing capacity of each membrane separation unit; limiting the processing load of the compressor module in each pressure swing adsorption unit; process load limitations of the compressor modules in each membrane separation unit;
the operating parameters of the pressure swing adsorption unit and the membrane separation unit in the hydrogen recovery system comprise: the operating temperature, pressure and adsorption time of each pressure swing adsorption unit; the operating temperature and pressure of each membrane separation device; flow rate, composition and pressure of the hydrogen-containing stream.
Further, the first modeling unit is specifically configured to, when establishing the mathematical simulation model of the hydrogen recovery system:
and respectively establishing a mathematical simulation model of each pressure swing adsorption device in the pressure swing adsorption unit, a mathematical simulation model of each membrane separation device in the membrane separation unit, a mathematical simulation model of a compressor module in each pressure swing adsorption device and a mathematical simulation model of a compressor module in each membrane separation device.
Further, when the first modeling unit establishes the mathematical simulation model of each pressure swing adsorption device in the pressure swing adsorption unit, the first modeling unit is specifically configured to:
establishing a mathematical simulation model of each pressure swing adsorption device in the pressure swing adsorption unit by adopting an adsorption equilibrium equation, a mass transfer rate equation and a total mass transfer equilibrium equation;
wherein the adsorption equilibrium equation is:
Figure BDA0001347787010000081
wherein, thetaiRepresenting the coverage rate of a gas component i on the adsorbent in the mixed gas to be measured; q. q.siRepresenting the equilibrium adsorption quantity of a gas component i in the mixed gas to be measured on the adsorbent; q. q.smax,iRepresenting the maximum adsorption amount of the gas component i in the mixed gas to be measured on the adsorbent; b isiRepresents the langmuir adsorption constant of gas component i on the adsorbent; b isjRepresents the langmuir adsorption constant of gas component j on the adsorbent; piRepresenting the partial pressure of a gas component i in the mixed gas to be measured; pjWhich represents the partial pressure of the gas component j in the mixed gas to be measured.
Further, when the first modeling unit establishes the mathematical simulation model of each pressure swing adsorption device in the pressure swing adsorption unit, the first modeling unit is specifically configured to:
establishing a mathematical simulation model of each pressure swing adsorption device in the pressure swing adsorption unit by adopting an adsorption equilibrium equation, a mass transfer rate equation and a total mass transfer equilibrium equation;
wherein the adsorption equilibrium equation is:
Figure BDA0001347787010000091
Figure BDA0001347787010000092
Figure BDA0001347787010000093
wherein, thetaiRepresenting the coverage rate of a gas component i on a certain layer of adsorbent in the mixed gas to be adsorbed; piMeans gas component of the mixed gas to be adsorbedi partial pressure; b isiRepresents the langmuir adsorption constant of gas component i on the layer of adsorbent; b isijRepresents the langmuir adsorption constant of component i on the layer of adsorbent in a binary gas mixture comprising component i and component j; kijRepresenting the degree of influence of component j on the adsorption of component i when a binary gas mixture comprising component i and component j is adsorbed on the layer of adsorbent; ki,mixRepresents the adsorption influence parameter of all gas components in the mixed gas to be adsorbed on the gas component i.
According to the technical scheme, the hydrogen recovery system collaborative optimization method and the system provided by the invention do not focus on the optimization of a pressure swing adsorption device or a membrane separation device per se like the prior art, but fully research the combined collaborative optimization and raw material collaborative optimization among the hydrogen recovery devices, and optimize the efficient and economic recovery of hydrogen from the perspective of the whole hydrogen recovery system; the invention considers the cooperative optimization among the hydrogen recovery devices in the whole enterprise range from the system perspective, and fully exerts the effective resultant force of each hydrogen recovery device; compared with the prior art, the method can effectively improve the operation level of the hydrogen recovery system, maximize the hydrogen recovery and improve the economic benefit of enterprises.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a flow chart of a method for collaborative optimization of a hydrogen recovery system according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a hydrogen recovery system co-optimization system according to another embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
An embodiment of the present invention provides a hydrogen recovery system collaborative optimization method, referring to a flow chart shown in fig. 1, the method including the following steps:
step 101: establishing a mathematical simulation model of a hydrogen recovery system, the hydrogen recovery system comprising: at least one of a pressure swing adsorption unit and a membrane separation unit; the pressure swing adsorption unit comprises at least one pressure swing adsorption device, the membrane separation unit comprises at least one membrane separation device, and compressor modules are selectively arranged in the pressure swing adsorption device and the membrane separation device according to preset requirements.
In this step, a mathematical simulation model of the hydrogen recovery system is established, which specifically includes: and respectively establishing a mathematical simulation model of each pressure swing adsorption device in the pressure swing adsorption unit, a mathematical simulation model of each membrane separation device in the membrane separation unit and a mathematical simulation model of compressor modules in each pressure swing adsorption device and each membrane separation device, wherein the mathematical simulation models of the hydrogen recovery system can be established through hydrogen-containing material flow connection. It is understood that the compressor module described in this step is specifically directed to a compressor associated with a hydrogen recovery system, such as a desorption gas compressor of a pressure swing adsorption plant, a feed and permeate gas compressor of a membrane separation plant, and the like, excluding a recycle hydrogen compressor and other process stream compressors.
In an alternative embodiment of this step, creating a mathematical simulation model of each pressure swing adsorption unit in the pressure swing adsorption unit comprises:
and establishing a mathematical simulation model of each pressure swing adsorption device in the pressure swing adsorption unit by adopting an adsorption equilibrium equation, a mass transfer rate equation and a total mass transfer equilibrium equation.
It is to be understood that, in this alternative embodiment, establishing a mathematical simulation model of the pressure swing adsorption apparatus using the adsorption equilibrium equation, the mass transfer rate equation, and the total mass transfer equilibrium equation refers to establishing a mathematical simulation model of each adsorption layer in the pressure swing adsorption apparatus using the adsorption equilibrium equation, the mass transfer rate equation, and the total mass transfer equilibrium equation, respectively. Wherein, the calculation result of the raw material gas passing through a certain adsorption layer is used as the inlet initial value of the next adsorption layer simulation calculation. Specifically, assuming constant pressure and temperature, the flow model adopts an axial dispersion piston flow model, the flow rate change caused by adsorption is calculated by a total mass transfer equilibrium equation, the mass transfer rate equation adopts a linear driving force model (LDF), and the adsorption equilibrium equation is described by an expanded Langmuir model.
In this alternative embodiment, each model equation is as follows:
mass transfer equilibrium equation of gas component i in infinitesimal volume:
Figure BDA0001347787010000111
wherein D isLRepresents the bed axial diffusion coefficient, m2/s；CiRepresents the total gas phase concentration of component i, mol/m3(ii) a v represents the air flow velocity, m/s; rhoPDenotes the gas phase density in kg/m at the adsorption pressure P3(ii) a Epsilon represents the porosity of the molecular adsorption bed and is dimensionless;
Figure BDA0001347787010000112
represents the adsorption equilibrium concentration of the component i, mol/kg.
The total mass transfer equilibrium equation:
Figure BDA0001347787010000113
wherein C represents the gas phase concentration of the bed layer, mol/m3(ii) a The other parameters are as defined above.
Mass transfer rate equation:
Figure BDA0001347787010000114
wherein k isiRepresents the gas-solid mass transfer coefficient, s;
Figure BDA0001347787010000115
represents the gas phase concentration of an adsorption bed of the component i, and mol/kg;
Figure BDA0001347787010000116
represents the adsorption equilibrium concentration of the component i, mol/kg.
During specific calculation, an adsorption tower bed layer (a pressure swing adsorption device) is divided into different micro-element sections from the bottom to the top of the tower according to different types of adsorbents (according to actual calculation requirements, the same adsorbent layer can also be divided into a plurality of micro-element sections), a calculation result of an outlet of each micro-element section is used as an initial calculation value of a next micro-element section inlet and is sequentially calculated to the top of the adsorption tower, and if the deviation between the calculation result of the top of the adsorption tower and the actual value is larger, the calculation result is returned to the first micro-element section at the bottom of the tower, and corresponding parameters are modified and adjusted. Each infinitesimal section is modeled and solved simultaneously by adopting the control equations. The adsorption quantity of different components passing through the adsorbent is calculated by an adsorption equilibrium equation, the time of the component passing through the micro-element section is calculated by a mass transfer rate equation, and a mass transfer material equilibrium equation (a total mass transfer material equation and a single-component material equation) mainly calculates the properties (concentration, flow and the like) of the component at the outlet of the micro-element section by describing a material equilibrium relation of the component entering and exiting the micro-element section.
Wherein the adsorption equilibrium equation is:
Figure BDA0001347787010000121
wherein, thetaiRepresenting the coverage rate of a gas component i on the adsorbent in the mixed gas to be measured; q. q.siRepresenting the equilibrium adsorption quantity of a gas component i in the mixed gas to be measured on the adsorbent; q. q.smax,iRepresenting the maximum adsorption amount of the gas component i in the mixed gas to be measured on the adsorbent; b isiRepresenting a gas component i on the adsorbentLangmuir adsorption constant of 106Pa-1；BjRepresents the Langmuir adsorption constant of gas component j on the adsorbent, 106Pa-1；PiRepresenting the partial pressure of gas component i in the gas mixture to be measured, 106Pa；PjRepresents the partial pressure of gas component j in the mixed gas to be measured, 106Pa。
In another alternative embodiment of this step, creating a mathematical simulation model of each pressure swing adsorption unit in the pressure swing adsorption unit comprises:
establishing a mathematical simulation model of each pressure swing adsorption device in the pressure swing adsorption unit by adopting an adsorption equilibrium equation, a mass transfer rate equation and a total mass transfer equilibrium equation;
in this alternative embodiment, the mass transfer rate equation and the total mass transfer equilibrium equation are the same as in the previous alternative embodiment, and reference may be made to the previous alternative embodiment specifically, and the adsorption equilibrium equation in this alternative embodiment is different from the above embodiment. In this alternative embodiment, the adsorption equilibrium equation is described using a modified langmuir model.
In this alternative embodiment, the adsorption equilibrium equation is:
Figure BDA0001347787010000122
Figure BDA0001347787010000123
Figure BDA0001347787010000124
wherein, thetaiRepresenting the coverage rate of a gas component i on a certain layer of adsorbent in the mixed gas to be adsorbed; piDenotes the partial pressure of the gas component i in the gas mixture to be adsorbed, 106Pa；BiShows the Langmuir adsorption constant of gas component i on the adsorbent of the layer, 106Pa-1；BijRepresents the langmuir adsorption constant of component i on the layer of adsorbent in a binary gas mixture comprising component i and component j; kijRepresenting the degree of influence of component j on the adsorption of component i when a binary gas mixture comprising component i and component j is adsorbed on the layer of adsorbent; ki,mixRepresents the adsorption influence parameter of all gas components in the mixed gas to be adsorbed on the gas component i.
It should be noted that the adsorption equilibrium equation used in this embodiment is based on the modified langmuir model. The following is an introduction of the improved langmuir model:
in the current field of adsorption separation, single-component langmuir models or extended langmuir models are mainly used to describe the phase equilibrium problem of the adsorption process. On one hand, the single-component Langmuir model is suitable for researching the adsorption process of single-component gas, does not consider the mutual influence among different components, and cannot describe the adsorption process of multi-component gas mixture; on the other hand, the expanded langmuir model is a model widely applied in recent years for describing a multi-component gas-solid adsorption process, theoretically, adsorption equilibrium constants of various components in a mixed atmosphere on an adsorbent need to be determined through experiments and then calculated, but because the gas adsorption equilibrium constants of more than two components are extremely difficult to obtain, when the model is actually applied, the single-component langmuir adsorption constant of the component is still adopted to replace the adsorption equilibrium constant of the component in a mixed gas, and the inaccuracy of calculation of the equilibrium adsorption amount of the mixed gas is certainly increased through the simplified treatment. In response to this technical problem, the present embodiment provides an improved langmuir model, which can accurately determine the adsorption amount of the multi-component adsorption process.
The establishment process of the adsorption equilibrium equation provided in this embodiment is given below:
a. through experimental means or data retrieval, single-component Langmuir models of each gas component in the mixed gas to be measured on the same adsorbent S are respectively obtained, and the single-component Langmuir adsorption constant B of each gas component is obtainedi(ii) a Wherein the mixed gas to be measured contains n gas components in total, 1≤i≤n；
b. According to the gas composition of the mixed gas to be measured, preparing the gas of each two components into a binary gas mixture, and co-preparing to obtain the gas mixture
Figure BDA0001347787010000131
A group of binary gas mixtures; when each two-component gas is prepared into a binary gas mixture, the molar ratio of the two-component gases in the binary gas mixture can be any molar ratio, and preferably, the molar ratio of the two-component gases is 1: 1.
c. Respectively acquiring the Langmuir adsorption constant B of each gas component in each group of binary gas mixtures on the adsorbentijWherein B isijRepresents the langmuir adsorption constant of component i on said adsorbent S in a binary gas mixture comprising component i and component j; this step can be obtained experimentally.
d. Respectively obtaining a binary interaction parameter K among the gas components in each group of binary gas mixtureijWherein, K isij＝Bij/Bi，KijRepresents the degree of influence of component j on the adsorption of component i when a binary gas mixture comprising component i and component j is adsorbed on the adsorbent S; wherein, if 0 < KijIf the value is less than 1, the gas component j has an inhibiting effect on the adsorption process of the gas component i; if Kij1 means that the gas component j has no influence or little influence on the adsorption process of the gas component i; when i ═ j, Kij1 is ═ 1; if KijAnd > 1, the gas component j has the promotion effect on the adsorption process of the gas component i. Wherein, KijCloser to 1, meaning less influence of the component, KijA larger deviation of 1 indicates a stronger influence of the composition.
e. D, obtaining a binary interaction parameter K among the gas components in the binary gas mixture according to the step dijObtaining the adsorption parameter K of all gas components in the mixed gas to be measured on the gas component ii,mix(ii) a In this step, the ratio of all gas components to gas component i in the mixed gas to be measured is obtained specifically in the following mannerAdsorption parameter Ki,mix：
Figure BDA0001347787010000141
Wherein, yjRepresents a regulation factor, y, for the influence of the adsorption of gas component j on gas component ijIs the gas volume proportion of the gas component j in the gas mixture to be measured.
f. According to the adsorption parameter K of all gas components in the mixed gas to be measured on the gas component ii,mixEstablishing a gas-solid adsorption equilibrium equation of the mixed gas to be measured:
Figure BDA0001347787010000142
wherein, thetaiDenotes the coverage of gas component i on the adsorbent in the gas mixture to be determined, PiRepresenting the partial pressure of gas component i in the gas mixture to be measured, 106Pa，BiDenotes the Langmuir adsorption constant of gas component i on the adsorbent, 106Pa-1；。
g. The equation is solved and the adsorption amount of each gas component on the adsorbent S is obtained.
In an alternative embodiment of this step, establishing a mathematical simulation model of each membrane separation device in the membrane separation unit comprises:
neglecting the flow resistance of the fluid on both sides of the membrane, assuming that the gas composition on the feed side changes linearly and the gas composition on the permeate side is in a fully mixed form, the mathematical model of the gas permeation quantity of component i is as follows:
Figure BDA0001347787010000143
wherein Q isiRepresents the air permeability of component i; j. the design is a squareiRepresents the permeability coefficient; a represents the membrane area; pFIndicates the raw material side film surface pressure; x is the number ofiFRepresents the concentration of gas component i in the feed gas; x is the number ofiRRepresents the concentration of gas component i in the retentate gas; ppDenotes the osmotic gas pressure; y isiPRepresents the concentration of gas component i in the permeate gas.
In an alternative embodiment of this step, creating a mathematical simulation model of each compressor module in the pressure swing adsorption unit and the membrane separation unit comprises:
Figure BDA0001347787010000151
Ccomp＝c×Power
wherein Power represents the compressor Power calculation; c1Represents the isobaric specific heat of the gas; t represents the gas inlet temperature; η represents the compressor efficiency coefficient; pin、PoutIndicating the inlet and outlet pressure of the compressor; r represents a gas heat capacity ratio; ρ represents the gas density of the gas entering the compressor; rho0Represents the gas density in the standard state; f represents the gas flow into the compressor; c represents a unit electricity charge; ccompRepresenting the compressor power consumption cost.
Step 102: setting flow rates of hydrogen-containing streams entering various pressure swing adsorption devices in the pressure swing adsorption unit and various membrane separation devices in the membrane separation unit according to design parameters and operation parameters of the pressure swing adsorption unit, the membrane separation unit and the compressor unit in the hydrogen recovery system, setting initial values of adsorption equilibrium kinetic parameters of various pressure swing adsorption devices in the pressure swing adsorption unit, and setting initial values of component permeation rate parameters of various membrane separation devices in the membrane separation unit; wherein the hydrogen-containing stream in the hydrogen recovery system comprises hydrogen-containing streams entering and exiting the pressure swing adsorption unit and the membrane separation unit, and hydrogen-containing streams discharged to the refinery gas system.
In this step, the design parameters of the pressure swing adsorption unit and the membrane separation unit in the hydrogen recovery system include: the height, internal diameter, temperature, pressure, processing capacity, adsorbent loading, type, pore volume and specific surface area of each pressure swing adsorption unit; the design temperature, pressure, selectivity and processing capacity of each membrane separation unit; limiting the processing load of the compressor module in each pressure swing adsorption unit; process load limitations of the compressor modules in each membrane separation unit;
the operating parameters of the pressure swing adsorption unit and the membrane separation unit in the hydrogen recovery system comprise: the operating temperature, pressure and adsorption time of each pressure swing adsorption unit; the operating temperature and pressure of each membrane separation device; flow rate, composition and pressure of the hydrogen-containing stream.
In this step, the adsorption equilibrium kinetic parameters include: diffusion coefficient, mass transfer coefficient, pelect number and langmuir adsorption equilibrium constant.
For example, it is assumed that design parameters and operation parameters of the pressure swing adsorption unit and the membrane separation unit in the hydrogen recovery system are as shown in tables 1 to 3 below. A portion of the hydrogen containing stream is shown in table 4.
TABLE 1 design parameters and operating parameters of pressure swing adsorption units
1#PSA 2#PSA
Design parameters of adsorption tower part
Diameter, m 3.2 2.8
Height, m 8.39 7.6
Sorbent packing
Molecular sieves 40.5 29
Activated carbon 8 5.6
Silica gel 1.8 1.2
Activated alumina 0.7 0.6
Operating parameters of adsorption column
Adsorption pressure, MPa 2.1 2.1
Temperature of raw material at DEG C 30～40 30～40
Process flow 10-1-6 VPSA，6-2-3
Single column adsorption time, s 225 217
TABLE 2 Membrane separation device design parameters and operating parameters
Figure BDA0001347787010000162
TABLE 3 compressor design parameters and operating parameters
Figure BDA0001347787010000161
Figure BDA0001347787010000171
Table 4 partial hydrogen containing stream information
Figure BDA0001347787010000172
Step 103: and carrying out mathematical solution on the mathematical simulation model of the hydrogen recovery system to obtain the composition and flow of the product hydrogen output by the hydrogen recovery system.
Step 104: judging whether the composition and the flow of the product hydrogen in the solution result of the step 103 meet the preset calculation requirement, and if so, executing a step 105; if the preset calculation requirement is not met and the iteration number does not reach the preset limit number, correcting one or more of the flow of the hydrogen-containing stream entering each pressure swing adsorption device in the pressure swing adsorption unit and entering each membrane separation device in the membrane separation unit, the initial values of the adsorption equilibrium kinetic parameters of each pressure swing adsorption device in the pressure swing adsorption unit and the initial values of the component permeation rate parameters of each membrane separation device in the membrane separation unit in the step 102, and returning to the step 103; if the preset calculation requirement is not met and the number of iterations has reached the preset limit number, step 105 is executed.
Step 105: and establishing an integral optimization model of the hydrogen recovery system, and respectively establishing subsystem optimization models of a pressure swing adsorption unit and a membrane separation unit in the hydrogen recovery system.
Step 106: initializing an integral optimization model of the hydrogen recovery system, and respectively initializing subsystem optimization models of a pressure swing adsorption unit and a membrane separation unit; wherein initializing the global optimization model of the hydrogen recovery system comprises: setting a first iteration number upper limit of an integral optimization model, and flow rates of hydrogen-containing streams entering all pressure swing adsorption devices in the pressure swing adsorption unit and all membrane separation devices in the membrane separation unit; wherein initializing the subsystem optimization models of the pressure swing adsorption unit and the membrane separation unit comprises: setting the upper limit of the second iteration times of each subsystem optimization model, and receiving the flow of the hydrogen-containing streams which enter each pressure swing adsorption device in the pressure swing adsorption unit and each membrane separation device in the membrane separation unit and are set by the integral optimization model.
Step 107: and respectively carrying out optimization solution on the subsystem optimization models of the pressure swing adsorption unit and the membrane separation unit, and determining the optimization solution result of the overall optimization model according to the optimization solution result of each subsystem optimization model.
Wherein the objective function of the overall optimization model is as follows: maximizing product hydrogen recovery benefits of a hydrogen recovery system, wherein the product hydrogen recovery benefits of the hydrogen recovery system are equal to the sum of the product hydrogen recovery benefits of the pressure swing adsorption unit and the membrane separation unit;
the constraint conditions of the overall optimization model comprise: the difference between the preset flow rate of the hydrogen-containing stream entering the pressure swing adsorption unit and the flow rate of the hydrogen-containing stream actually processed by the pressure swing adsorption unit in the hydrogen recovery system is smaller than a preset relaxation factor, and the difference between the preset flow rate of the hydrogen-containing stream entering the membrane separation unit and the flow rate of the hydrogen-containing stream actually processed by the membrane separation unit in the hydrogen recovery system is smaller than a preset relaxation factor; the constraints of the overall optimization model further comprise: the pure hydrogen amount in the hydrogen-containing stream of the hydrogen recovery system is more than or equal to the pure hydrogen amount in the product hydrogen obtained by the pressure swing adsorption unit and the membrane separation unit; the pure hydrogen amount in the hydrogen-containing stream of the hydrogen recovery system is equal to the sum of the pure hydrogen amount in the product hydrogen obtained by the pressure swing adsorption unit and the membrane separation unit and the pure hydrogen content in the hydrogen-containing stream discharged to the gas system;
the objective function of the optimization model of the pressure swing adsorption unit subsystem is as follows: the minimum difference value between the preset flow rate of the hydrogen-containing stream entering the pressure swing adsorption unit in the hydrogen recovery system and the flow rate of the hydrogen-containing stream actually treated by the pressure swing adsorption unit;
the objective function of the optimization model of the membrane separation unit subsystem is as follows: the minimum difference value of the preset flow rate of the hydrogen-containing stream entering the membrane separation unit and the flow rate of the hydrogen-containing stream actually processed by the membrane separation unit in the hydrogen recovery system;
the constraint conditions of the pressure swing adsorption unit subsystem optimization model are as follows: the inlet and outlet of each pressure swing adsorption device in the pressure swing adsorption unit meet the requirements of material conservation and component conservation, the pressure of the raw material gas is greater than or equal to the pressure requirement of the inlet of the pressure swing adsorption device, the processing load of the pressure swing adsorption device is within the processing capacity range of the pressure swing adsorption device, the hydrogen and hydrogen purity of the product is greater than or equal to a preset purity value, and the preset component gas in the raw material gas cannot penetrate through a preset adsorption layer;
the constraint conditions of the optimization model of the membrane separation unit subsystem are as follows: the inlet and outlet of each membrane separation device in the membrane separation unit meet the requirements of material conservation and component conservation, the pressure of the raw material gas is greater than or equal to the pressure requirement of the inlet of the membrane separation device, the processing load of the membrane separation device is within the processing capacity range of the membrane separation device, and the raw material gas does not contain specified gas components.
Step 108: judging whether the optimization solving result of the integral optimization model is converged, and if so, ending the optimization solving process of the hydrogen recovery system; if the iteration times reach the first iteration time upper limit without convergence, ending the optimization solving process of the hydrogen recovery system; if not, and the iteration number does not reach the first iteration number upper limit, returning to step 107 to continue the optimization solution until the optimization model of each subsystem reaches the second iteration number upper limit.
The above steps 105-108 will be described in detail below.
The objective function of the overall optimization model is as follows: the hydrogen recovery system maximizes the product hydrogen recovery benefits. Wherein, the total recovery benefit of the hydrogen recovery system is equal to the sum of the recovery benefits of each hydrogen recovery device, and the benefit f of each subsystemi(Xi) And respectively calculating the total recovery benefits of the hydrogen recovery system in each subsystem as follows:
Figure BDA0001347787010000191
the constraint conditions of the overall optimization model comprise A and B:
a: the equation consistency constraint of the hydrogen recovery system and the subsystem i is as follows:
Figure BDA0001347787010000192
……
Figure BDA0001347787010000193
……
Figure BDA0001347787010000201
wherein the content of the first and second substances,
Figure BDA0001347787010000202
representing the actual recovery process of the sub-system i for the hydrogen-containing stream rjThe flow of (2) is a constant transmitted to the system level by the subsystem i;
Figure BDA0001347787010000203
representing a predetermined subsystem i in the hydrogen recovery system to recover a process hydrogen-containing stream rjIs a system level variable, and epsilon represents a preset relaxation factor. It is understood that subsystem i herein denotes a pressure swing adsorption unit or a membrane separation unit. N represents the number of pressure swing adsorption units or membrane separation units contained in the pressure swing adsorption unit or membrane separation unit.
B: flow restriction
The pure hydrogen quantity in the hydrogen-containing stream of the hydrogen recovery system is necessarily more than or equal to the pure hydrogen quantity in the product hydrogen obtained by the hydrogen recovery subsystem; the amount of pure hydrogen in the hydrogen-containing stream of the hydrogen recovery system is equal to the sum of the pure hydrogen obtained by the hydrogen recovery subsystem and the content of the pure hydrogen in the hydrogen-containing stream discharged to the gas system.
Figure BDA0001347787010000204
Figure BDA0001347787010000205
Wherein the content of the first and second substances,
Figure BDA0001347787010000206
representing a hydrogen-containing stream rjThe flow rate of (a);
Figure BDA0001347787010000207
representing a hydrogen-containing stream rjHydrogen purity of (d);
Figure BDA0001347787010000208
representing the product hydrogen flow of the subsystem i;
Figure BDA0001347787010000209
representing the product hydrogen purity of the subsystem i;
Figure BDA00013477870100002010
representing the flow of the hydrogen-containing stream discharged to the gas system;
Figure BDA00013477870100002011
indicating the hydrogen purity of the hydrogen-containing stream discharged to the gas system.
The computational expression for the hydrogen recovery efficiency is given below:
fi＝fi-product H2 value-fi-supplementary heat value loss cost-fi-compressor power cost
Figure BDA00013477870100002012
Figure BDA00013477870100002013
Figure BDA00013477870100002014
Wherein f isi-product H2 valueRepresenting the value of the subsystem i for recovering hydrogen; f. ofi-supplementary heat value loss costRepresents the cost of supplementing the loss of fuel gas heating value due to hydrogen recovery; f. ofi-compressor power costRepresents the compressor power cost associated with subsystem i; c. CiRepresenting the product hydrogen price of the subsystem i;
Figure BDA0001347787010000211
representing the product hydrogen flow of the subsystem i;
Figure BDA0001347787010000212
representing the lower heating value of the product hydrogen stream of subsystem i; LCVNGRepresents the lower heating value of the unit volume of natural gas; c. CNGExpressing the price of natural gas per unit volume; power represents the compressor Power calculation; c1Represents the isobaric specific heat of the gas;t represents the gas inlet temperature; η represents the compressor efficiency coefficient; pin、PoutIndicating the inlet and outlet pressure of the compressor; r represents a gas heat capacity ratio; ρ represents a gas density; f represents the gas flow into the compressor; c represents a unit electricity charge; ccompRepresenting the compressor power consumption cost.
(II) the objective function of each subsystem optimization model is as follows:
Figure BDA0001347787010000213
wherein the content of the first and second substances,
Figure BDA0001347787010000214
representing the actual recovery process of the sub-system i for the hydrogen-containing stream rjThe flow of (2) is a constant transmitted to the system level by the subsystem i;
Figure BDA0001347787010000215
representing a predetermined subsystem i in the hydrogen recovery system to recover a process hydrogen-containing stream rjIs a system level variable.
The constraint conditions of each subsystem optimization model are respectively as follows:
pressure swing adsorption apparatus:
the inlet and outlet of the pressure swing adsorption device need to meet the requirements of material conservation and component conservation; the pressure of the raw material gas is required to be more than or equal to the pressure requirement of the inlet of the device; the processing load of the device is restricted by the processing capacity; the hydrogen purity of the product is more than or equal to a certain set value, and the preferred value is 99.9 percent; when the raw material of the swing adsorption device is constant, H should be ensured2O does not penetrate the silica gel bed, i.e. tAdsorption＜tH2O，C2 +Heavy hydrocarbons not penetrating the bed of activated carbon, i.e. tAdsorption＜tC2+，CH4Does not penetrate molecular sieve bed layer, and avoids adsorbent poisoning, i.e. tAdsorption＜tCH4(ii) a The device processing load is constrained by the processing capacity.
Figure BDA0001347787010000216
Figure BDA0001347787010000217
Figure BDA0001347787010000218
Figure BDA0001347787010000219
Figure BDA0001347787010000221
Figure BDA0001347787010000222
Figure BDA0001347787010000223
Figure BDA0001347787010000224
Wherein, FPRepresenting the hydrogen flow of the product of the pressure swing adsorption device; fStripping gasIndicating the flow rate of desorption gas of the pressure swing adsorption device;
Figure BDA0001347787010000225
represents the content of component s in the hydrogen-containing stream rj; y isP, component sRepresenting the content of a hydrogen component s in a product of a pressure swing adsorption device; y isStripping gas, component sRepresenting the content of a desorbed gas component s of the pressure swing adsorption device;
Figure BDA0001347787010000226
indicating the purity of the product hydrogen of the pressure swing adsorption device;
Figure BDA0001347787010000227
indicating the feed
Figure BDA0001347787010000228
The adsorption operation time of the pressure swing adsorption device is shortened;
Figure BDA0001347787010000229
indicating the feed
Figure BDA00013477870100002210
When the component H in the raw material2The penetration time of the O from the bottom of the tower to the final silica gel bed layer;
Figure BDA00013477870100002211
indicating the feed
Figure BDA00013477870100002212
When the components in the raw materials
Figure BDA00013477870100002213
The penetration time of the heavy hydrocarbon from the bottom of the tower to the final penetration of the activated carbon bed layer;
Figure BDA00013477870100002214
indicating the feed
Figure BDA00013477870100002215
When the component CH in the raw material4The penetration time from the bottom of the tower to the final penetration of the molecular sieve bed;
Figure BDA00013477870100002216
representing the pressure of the hydrogen-containing stream rj; pin，PSAIndicating the pressure required by the inlet of the pressure swing adsorption device;
Figure BDA00013477870100002217
representing the handling capacity of the pressure swing adsorption device;
Figure BDA00013477870100002218
indicating pressure swing adsorptionLower limit of device processing capacity;
Figure BDA00013477870100002219
represents the upper limit of the processing capacity of the pressure swing adsorption unit.
② a membrane separation device:
the inlet and outlet of the membrane separation device need to meet the requirements of material conservation and component conservation; the pressure of the raw material gas is required to be more than or equal to the pressure requirement of the inlet of the membrane separation device; the processing load of the device is restricted by the processing capacity; the feed gas cannot contain CO impurities.
Figure BDA00013477870100002220
Figure BDA00013477870100002221
Figure BDA0001347787010000231
Figure BDA0001347787010000232
Figure BDA0001347787010000233
Wherein the content of the first and second substances,
Figure BDA0001347787010000234
representing a hydrogen-containing stream rjThe content of the gas component s; y isPermeate gas, component sRepresents the content of component s in the permeate gas; y isResidual gas, component sRepresents the content of the gas component s in the retentate gas;
Figure BDA0001347787010000235
representing a hydrogen-containing stream rjThe content of gas component CO.
③ the compressor module:
the hydrogen-containing stream entering and exiting the compressor needs to satisfy flow balance and component balance, and the expression is as follows:
Fcomp，in＝Fcomp，out
Fcomp，in×ycomponent s, in＝Fcomp，out×yComponent s, out
Wherein, Fcomp，inRepresents compressor inlet flow; fcomp，outRepresents the compressor outlet flow; y isComponent s, inRepresents the compressor inlet component s content; y isComponent s, outIndicating the compressor outlet component s content.
And (III) setting a first iteration upper limit of the overall optimization model and a second iteration upper limit of each subsystem optimization model. Wherein the upper limit of the first iteration times is 5-50; the upper limit of the second iteration number is 5-40. For example, the upper limit of the first iteration number of the overall optimization model is set to be 15, and the preset relaxation factor is set to be 0.0001. And setting the upper limit of the second iteration times of each subsystem optimization model to be 10 times.
The optimization solving is carried out by adopting a special solver when the optimization model of each subsystem is solved, and the solving method can adopt a Kriging approximate model method, a genetic algorithm, an ant colony algorithm and the like. Since the solution method is well known, it will not be described in detail here. When the overall optimization model is optimized and solved, a special solver is also adopted for solving, and the solving method can adopt an existing gradient method, a gradient projection method and the like. Since the solution method is well known, it will not be described in detail here. After the solution of each subsystem optimization model is finished, judging whether the optimization solution result of the whole optimization model is converged, and if so, finishing the optimization solution process of the hydrogen recovery system; if the iteration times reach the first iteration time upper limit without convergence, ending the optimization solving process of the hydrogen recovery system; if not, and the iteration number does not reach the first iteration number upper limit, returning to step 107 to continue the optimization solution until the optimization model of each subsystem reaches the second iteration number upper limit.
Wherein, the following table 5 shows the comparison of the overall performance of the hydrogen recovery system before and after the optimization by the collaborative optimization method of the present invention. As can be seen from the results, the optimized system can recover 2740Nm3/h more hydrogen, and has remarkable economic benefit.
TABLE 5 comparison of overall Performance of Hydrogen recovery System before and after optimization
Figure BDA0001347787010000241
According to the technical scheme, the hydrogen recovery system collaborative optimization method provided by the embodiment of the invention does not focus on the optimization of a pressure swing adsorption device or a membrane separation device per se like the prior art, but fully researches the combination collaborative optimization and the raw material collaborative optimization among all hydrogen recovery devices, and optimizes the efficient and economic recovery of hydrogen from the perspective of the whole hydrogen recovery system; the invention considers the cooperative optimization among the hydrogen recovery devices in the whole enterprise range from the system perspective, and fully exerts the effective resultant force of each hydrogen recovery device; compared with the prior art, the method can effectively improve the operation level of the hydrogen recovery system, maximize the hydrogen recovery and improve the economic benefit of enterprises.
Another embodiment of the present invention further provides a hydrogen recovery system collaborative optimization system, referring to fig. 2, the system including: a first modeling unit 21, a first initial value setting unit 22, a first solving unit 23, a first judging unit 24, a second modeling unit 25, a second initial value setting unit 26, a second solving unit 27, and a second judging unit 28, wherein:
a first modeling unit 21 for building a mathematical simulation model of a hydrogen recovery system, the hydrogen recovery system comprising: at least one of a pressure swing adsorption unit and a membrane separation unit; the pressure swing adsorption unit comprises at least one pressure swing adsorption device, the membrane separation unit comprises at least one membrane separation device, and a compressor module is selectively arranged in the pressure swing adsorption device and the membrane separation device according to preset requirements;
a first initial value setting unit 22, configured to set flow rates of hydrogen-containing streams entering the pressure swing adsorption devices in the pressure swing adsorption unit and entering the membrane separation devices in the membrane separation unit, set initial values of adsorption equilibrium kinetic parameters of the pressure swing adsorption devices in the pressure swing adsorption unit, and set initial values of component permeation rates of the membrane separation devices in the membrane separation unit according to design parameters and operation parameters of the pressure swing adsorption unit and the membrane separation unit in the hydrogen recovery system; wherein the hydrogen-containing stream in the hydrogen recovery system comprises a hydrogen-containing stream entering and exiting the pressure swing adsorption unit, the membrane separation unit, and a hydrogen-containing stream discharged to the refinery gas system;
the first solving unit 23 is configured to perform mathematical solving on the mathematical simulation model of the hydrogen recovery system to obtain a composition and a flow rate of product hydrogen output by the hydrogen recovery system;
the first judging unit 24 is configured to judge whether the composition and the flow of the product hydrogen in the solution result of the first solving unit meet preset calculation requirements, and if the composition and the flow of the product hydrogen in the solution result of the first solving unit meet the preset calculation requirements, execute the second modeling unit; if the preset calculation requirement is not met and the iteration number does not reach the preset limit number, correcting one or more of the flow of the hydrogen-containing stream entering each pressure swing adsorption device in the pressure swing adsorption unit and each membrane separation device in the membrane separation unit, the initial values of the adsorption equilibrium kinetic parameters of each pressure swing adsorption device in the pressure swing adsorption unit and the initial values of the component permeation rate parameters of each membrane separation device in the membrane separation unit in the first initial value setting unit, and returning the corrected values to the first solving unit; if the preset calculation requirement is not met and the iteration number reaches the preset limit number, executing a second modeling unit;
the second modeling unit 25 is used for establishing an overall optimization model of the hydrogen recovery system and respectively establishing subsystem optimization models of a pressure swing adsorption unit and a membrane separation unit in the hydrogen recovery system;
a second initial value setting unit 26, configured to initialize an overall optimization model of the hydrogen recovery system, and initialize subsystem optimization models of the pressure swing adsorption unit and the membrane separation unit, respectively; wherein initializing the global optimization model of the hydrogen recovery system comprises: setting a first iteration number upper limit of an integral optimization model, and flow rates of hydrogen-containing streams entering all pressure swing adsorption devices in the pressure swing adsorption unit and all membrane separation devices in the membrane separation unit; wherein initializing the subsystem optimization models of the pressure swing adsorption unit and the membrane separation unit comprises: setting a second iteration upper limit of each subsystem optimization model, and receiving the flow of hydrogen-containing streams which enter each pressure swing adsorption device in the pressure swing adsorption unit and each membrane separation device in the membrane separation unit and are set by the integral optimization model;
the second solving unit 27 is used for respectively carrying out optimization solving on the subsystem optimization models of the pressure swing adsorption unit and the membrane separation unit, and determining the optimization solving result of the overall optimization model according to the optimization solving result of each subsystem optimization model;
wherein the constraint conditions of the overall optimization model comprise: the difference between the preset flow rate of the hydrogen-containing stream entering the pressure swing adsorption unit and the flow rate of the hydrogen-containing stream actually processed by the pressure swing adsorption unit in the hydrogen recovery system is smaller than a preset relaxation factor, and the difference between the preset flow rate of the hydrogen-containing stream entering the membrane separation unit and the flow rate of the hydrogen-containing stream actually processed by the membrane separation unit in the hydrogen recovery system is smaller than a preset relaxation factor; the constraints of the overall optimization model further comprise: the pure hydrogen amount in the hydrogen-containing stream of the hydrogen recovery system is more than or equal to the pure hydrogen amount in the product hydrogen obtained by the pressure swing adsorption unit and the membrane separation unit; the pure hydrogen amount in the hydrogen-containing stream of the hydrogen recovery system is equal to the sum of the pure hydrogen amount in the product hydrogen obtained by the pressure swing adsorption unit and the membrane separation unit and the pure hydrogen content in the hydrogen-containing stream discharged to the gas system;
the objective function of the optimization model of the pressure swing adsorption unit subsystem is as follows: the minimum difference value between the preset flow rate of the hydrogen-containing stream entering the pressure swing adsorption unit in the hydrogen recovery system and the flow rate of the hydrogen-containing stream actually treated by the pressure swing adsorption unit;
the objective function of the optimization model of the membrane separation unit subsystem is as follows: the minimum difference value of the preset flow rate of the hydrogen-containing stream entering the membrane separation unit and the flow rate of the hydrogen-containing stream actually processed by the membrane separation unit in the hydrogen recovery system;
the constraint conditions of the pressure swing adsorption unit subsystem optimization model are as follows: the inlet and outlet of each pressure swing adsorption device in the pressure swing adsorption unit meet the requirements of material conservation and component conservation, the pressure of the raw material gas is greater than or equal to the pressure requirement of the inlet of the pressure swing adsorption device, the processing load of the pressure swing adsorption device is within the processing capacity range of the pressure swing adsorption device, the hydrogen and hydrogen purity of the product is greater than or equal to a preset purity value, and the preset component gas in the raw material gas cannot penetrate through a preset adsorption layer;
the constraint conditions of the optimization model of the membrane separation unit subsystem are as follows: the inlet and outlet of each membrane separation device in the membrane separation unit meet the requirements of material conservation and component conservation, the pressure of the raw material gas is greater than or equal to the pressure requirement of the inlet of the membrane separation device, the processing load of the membrane separation device is within the processing capacity range of the membrane separation device, and the raw material gas does not contain specified gas components;
a second judging unit 28, configured to judge whether an optimization solution result of the overall optimization model converges, and if so, end the optimization solution process of the hydrogen recovery system; if the iteration times reach the first iteration time upper limit without convergence, ending the optimization solving process of the hydrogen recovery system; and if the system is not converged and the iteration times do not reach the upper limit of the first iteration times, returning to the second solving unit to continue the optimization solving until the optimization model of each subsystem reaches the upper limit of the second iteration times.
In an alternative embodiment, the design parameters of the pressure swing adsorption unit and the membrane separation unit in the hydrogen recovery system include: the height, internal diameter, temperature, pressure, processing capacity, adsorbent loading, type, pore volume and specific surface area of each pressure swing adsorption unit; the design temperature, pressure, selectivity and processing capacity of each membrane separation unit; limiting the processing load of the compressor module in each pressure swing adsorption unit; process load limitations of the compressor modules in each membrane separation unit;
the operating parameters of the pressure swing adsorption unit and the membrane separation unit in the hydrogen recovery system comprise: the operating temperature, pressure and adsorption time of each pressure swing adsorption unit; the operating temperature and pressure of each membrane separation device; flow rate, composition and pressure of the hydrogen-containing stream.
In an alternative embodiment, the first modeling unit 21 is specifically configured to, when establishing the mathematical simulation model of the hydrogen recovery system:
and respectively establishing a mathematical simulation model of each pressure swing adsorption device in the pressure swing adsorption unit, a mathematical simulation model of each membrane separation device in the membrane separation unit, a mathematical simulation model of a compressor module in each pressure swing adsorption device and a mathematical simulation model of a compressor module in each membrane separation device.
In an alternative embodiment, the first modeling unit 21 is specifically configured to, when establishing the mathematical simulation model of each pressure swing adsorption device in the pressure swing adsorption unit:
establishing a mathematical simulation model of each pressure swing adsorption device in the pressure swing adsorption unit by adopting an adsorption equilibrium equation, a mass transfer rate equation and a total mass transfer equilibrium equation;
wherein the adsorption equilibrium equation is:
Figure BDA0001347787010000271
wherein, thetaiRepresenting the coverage rate of a gas component i on the adsorbent in the mixed gas to be measured; q. q.siRepresenting the equilibrium adsorption quantity of a gas component i in the mixed gas to be measured on the adsorbent; q. q.smax,iRepresenting the maximum adsorption amount of the gas component i in the mixed gas to be measured on the adsorbent; b isiRepresents the langmuir adsorption constant of gas component i on the adsorbent; b isjRepresents the langmuir adsorption constant of gas component j on the adsorbent; piRepresenting the partial pressure of a gas component i in the mixed gas to be measured; pjWhich represents the partial pressure of the gas component j in the mixed gas to be measured.
In an alternative embodiment, the first modeling unit 21 is specifically configured to, when establishing the mathematical simulation model of each pressure swing adsorption device in the pressure swing adsorption unit:
establishing a mathematical simulation model of each pressure swing adsorption device in the pressure swing adsorption unit by adopting an adsorption equilibrium equation, a mass transfer rate equation and a total mass transfer equilibrium equation;
wherein the adsorption equilibrium equation is:
Figure BDA0001347787010000272
Figure BDA0001347787010000273
Figure BDA0001347787010000274
wherein, thetaiRepresenting the coverage rate of a gas component i on a certain layer of adsorbent in the mixed gas to be adsorbed; piRepresents the partial pressure of the gas component i in the mixed gas to be adsorbed; b isiRepresents the langmuir adsorption constant of gas component i on the layer of adsorbent; b isijRepresents the langmuir adsorption constant of component i on the layer of adsorbent in a binary gas mixture comprising component i and component j; kijRepresenting the degree of influence of component j on the adsorption of component i when a binary gas mixture comprising component i and component j is adsorbed on the layer of adsorbent; ki,mixRepresents the adsorption influence parameter of all gas components in the mixed gas to be adsorbed on the gas component i.
The hydrogen recovery system collaborative optimization system according to the embodiment of the present invention can be used for executing the hydrogen recovery system collaborative optimization method according to the above embodiment, and the principle and technical effect are similar, and will not be described in detail here.
In the description of the present invention, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The above examples are only for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims (10)

1. A hydrogen recovery system collaborative optimization method is characterized by comprising the following steps:
step S1: establishing a mathematical simulation model of a hydrogen recovery system, the hydrogen recovery system comprising: at least one of a pressure swing adsorption unit and a membrane separation unit; the pressure swing adsorption unit comprises at least one pressure swing adsorption device, the membrane separation unit comprises at least one membrane separation device, and a compressor module is selectively arranged in the pressure swing adsorption device and the membrane separation device according to preset requirements;
step S2: setting flow rates of hydrogen-containing streams entering all pressure swing adsorption devices in the pressure swing adsorption unit and all membrane separation devices in the membrane separation unit according to design parameters and operation parameters of the pressure swing adsorption unit and the membrane separation unit in the hydrogen recovery system, setting initial values of adsorption equilibrium kinetic parameters of all pressure swing adsorption devices in the pressure swing adsorption unit, and setting initial values of component permeation rate parameters of all membrane separation devices in the membrane separation unit; wherein the hydrogen-containing stream in the hydrogen recovery system comprises a hydrogen-containing stream entering and exiting the pressure swing adsorption unit, the membrane separation unit, and a hydrogen-containing stream discharged to the refinery gas system;
step S3: performing mathematical solution on a mathematical simulation model of the hydrogen recovery system to obtain the composition and flow of product hydrogen output by the hydrogen recovery system;
step S4: judging whether the composition and the flow of the product hydrogen in the solving result of the step S3 meet the preset calculation requirement, if so, executing a step S5; if the preset calculation requirement is not met and the iteration number does not reach the preset limit number, correcting one or more of the flow rate of the hydrogen-containing stream entering each pressure swing adsorption device in the pressure swing adsorption unit and entering each membrane separation device in the membrane separation unit, the initial values of the adsorption equilibrium kinetic parameters of each pressure swing adsorption device in the pressure swing adsorption unit and the initial values of the component permeation rate parameters of each membrane separation device in the membrane separation unit in the step S2, and returning to the step S3; if the preset calculation requirement is not met and the iteration number reaches the preset limit number, executing step S5;
step S5: establishing an integral optimization model of the hydrogen recovery system, and respectively establishing subsystem optimization models of a pressure swing adsorption unit and a membrane separation unit in the hydrogen recovery system;
step S6: initializing an integral optimization model of the hydrogen recovery system, and respectively initializing subsystem optimization models of a pressure swing adsorption unit and a membrane separation unit; wherein initializing the global optimization model of the hydrogen recovery system comprises: setting a first iteration number upper limit of an integral optimization model, and flow rates of hydrogen-containing streams entering all pressure swing adsorption devices in the pressure swing adsorption unit and all membrane separation devices in the membrane separation unit; wherein initializing the subsystem optimization models of the pressure swing adsorption unit and the membrane separation unit comprises: setting a second iteration upper limit of each subsystem optimization model, and receiving the flow of hydrogen-containing streams which enter each pressure swing adsorption device in the pressure swing adsorption unit and each membrane separation device in the membrane separation unit and are set by the integral optimization model;
step S7: respectively carrying out optimization solution on the subsystem optimization models of the pressure swing adsorption unit and the membrane separation unit, and determining the optimization solution result of the overall optimization model according to the optimization solution result of each subsystem optimization model;
wherein the objective function of the overall optimization model is as follows: maximizing product hydrogen recovery benefits of a hydrogen recovery system, wherein the product hydrogen recovery benefits of the hydrogen recovery system are equal to the sum of the product hydrogen recovery benefits of the pressure swing adsorption unit and the membrane separation unit;
the constraint conditions of the overall optimization model comprise: the difference between the preset flow rate of the hydrogen-containing stream entering the pressure swing adsorption unit and the flow rate of the hydrogen-containing stream actually processed by the pressure swing adsorption unit in the hydrogen recovery system is smaller than a preset relaxation factor, and the difference between the preset flow rate of the hydrogen-containing stream entering the membrane separation unit and the flow rate of the hydrogen-containing stream actually processed by the membrane separation unit in the hydrogen recovery system is smaller than a preset relaxation factor; the constraints of the overall optimization model further comprise: the pure hydrogen amount in the hydrogen-containing stream of the hydrogen recovery system is more than or equal to the pure hydrogen amount in the product hydrogen obtained by the pressure swing adsorption unit and the membrane separation unit; the pure hydrogen amount in the hydrogen-containing stream of the hydrogen recovery system is equal to the sum of the pure hydrogen amount in the product hydrogen obtained by the pressure swing adsorption unit and the membrane separation unit and the pure hydrogen content in the hydrogen-containing stream discharged to the gas system;
the objective function of the optimization model of the pressure swing adsorption unit subsystem is as follows: the minimum difference value between the preset flow rate of the hydrogen-containing stream entering the pressure swing adsorption unit in the hydrogen recovery system and the flow rate of the hydrogen-containing stream actually treated by the pressure swing adsorption unit;
the objective function of the optimization model of the membrane separation unit subsystem is as follows: the minimum difference value of the preset flow rate of the hydrogen-containing stream entering the membrane separation unit and the flow rate of the hydrogen-containing stream actually processed by the membrane separation unit in the hydrogen recovery system;
the constraint conditions of the pressure swing adsorption unit subsystem optimization model are as follows: the inlet and outlet of each pressure swing adsorption device in the pressure swing adsorption unit meet the requirements of material conservation and component conservation, the pressure of the raw material gas is greater than or equal to the pressure requirement of the inlet of the pressure swing adsorption device, the processing load of the pressure swing adsorption device is within the processing capacity range of the pressure swing adsorption device, the hydrogen and hydrogen purity of the product is greater than or equal to a preset purity value, and the preset component gas in the raw material gas cannot penetrate through a preset adsorption layer;
the constraint conditions of the optimization model of the membrane separation unit subsystem are as follows: the inlet and outlet of each membrane separation device in the membrane separation unit meet the requirements of material conservation and component conservation, the pressure of the raw material gas is greater than or equal to the pressure requirement of the inlet of the membrane separation device, the processing load of the membrane separation device is within the processing capacity range of the membrane separation device, and the raw material gas does not contain specified gas components;
step S8: judging whether the optimization solving result of the integral optimization model is converged, and if so, ending the optimization solving process of the hydrogen recovery system; if the iteration times reach the first iteration time upper limit without convergence, ending the optimization solving process of the hydrogen recovery system; if not, and the iteration number does not reach the first iteration number upper limit, returning to the step S7 to continue the optimization solution until the optimization models of the subsystems reach the second iteration number upper limit.
2. The hydrogen recovery system co-optimization method according to claim 1, wherein the design parameters of the pressure swing adsorption unit and the membrane separation unit in the hydrogen recovery system include: the height, internal diameter, temperature, pressure, processing capacity, adsorbent loading, type, pore volume and specific surface area of each pressure swing adsorption unit; the design temperature, pressure, selectivity and processing capacity of each membrane separation unit; limiting the processing load of the compressor module in each pressure swing adsorption unit; process load limitations of the compressor modules in each membrane separation unit;
the operating parameters of the pressure swing adsorption unit and the membrane separation unit in the hydrogen recovery system comprise: the operating temperature, pressure and adsorption time of each pressure swing adsorption unit; the operating temperature and pressure of each membrane separation device; flow rate, composition and pressure of the hydrogen-containing stream.
3. The hydrogen recovery system co-optimization method according to claim 1, wherein establishing a mathematical simulation model of the hydrogen recovery system comprises:
and respectively establishing a mathematical simulation model of each pressure swing adsorption device in the pressure swing adsorption unit, a mathematical simulation model of each membrane separation device in the membrane separation unit, a mathematical simulation model of a compressor module in each pressure swing adsorption device and a mathematical simulation model of a compressor module in each membrane separation device.
4. The hydrogen recovery system co-optimization method of claim 3, wherein establishing a mathematical simulation model of each pressure swing adsorption unit in the pressure swing adsorption unit comprises:
establishing a mathematical simulation model of each pressure swing adsorption device in the pressure swing adsorption unit by adopting an adsorption equilibrium equation, a mass transfer rate equation and a total mass transfer equilibrium equation;
wherein the adsorption equilibrium equation is:
Figure FDA0002838765940000041
wherein, thetaiRepresenting the coverage rate of a gas component i on the adsorbent in the mixed gas to be measured; q. q.siRepresenting the equilibrium adsorption quantity of a gas component i in the mixed gas to be measured on the adsorbent; q. q.smax,iRepresenting the maximum adsorption amount of the gas component i in the mixed gas to be measured on the adsorbent; b isiRepresents the langmuir adsorption constant of gas component i on the adsorbent; b isjRepresents the langmuir adsorption constant of gas component j on the adsorbent; piRepresenting the partial pressure of a gas component i in the mixed gas to be measured; pjWhich represents the partial pressure of the gas component j in the mixed gas to be measured.
5. The hydrogen recovery system co-optimization method of claim 3, wherein establishing a mathematical simulation model of each pressure swing adsorption unit in the pressure swing adsorption unit comprises:
establishing a mathematical simulation model of each pressure swing adsorption device in the pressure swing adsorption unit by adopting an adsorption equilibrium equation, a mass transfer rate equation and a total mass transfer equilibrium equation;
wherein the adsorption equilibrium equation is:
Figure FDA0002838765940000042
Figure FDA0002838765940000043
Figure FDA0002838765940000044
wherein, thetaiRepresenting the coverage rate of a gas component i on a certain layer of adsorbent in the mixed gas to be adsorbed; piRepresents the partial pressure of the gas component i in the mixed gas to be adsorbed; b isiRepresents the langmuir adsorption constant of gas component i on the layer of adsorbent; b isijRepresents the langmuir adsorption constant of component i on the layer of adsorbent in a binary gas mixture comprising component i and component j; kijRepresenting the degree of influence of component j on the adsorption of component i when a binary gas mixture comprising component i and component j is adsorbed on the layer of adsorbent; y isjThe gas volume proportion of the gas component j in the mixed gas to be measured; ki,mixRepresents the adsorption influence parameter of all gas components in the mixed gas to be adsorbed on the gas component i.
6. A hydrogen recovery system co-optimization system, comprising:
a first modeling unit for building a mathematical simulation model of a hydrogen recovery system, the hydrogen recovery system comprising: at least one of a pressure swing adsorption unit and a membrane separation unit; the pressure swing adsorption unit comprises at least one pressure swing adsorption device, the membrane separation unit comprises at least one membrane separation device, and a compressor module is selectively arranged in the pressure swing adsorption device and the membrane separation device according to preset requirements;
the first initial value setting unit is used for setting the flow of hydrogen-containing streams entering each pressure swing adsorption device in the pressure swing adsorption unit and each membrane separation device in the membrane separation unit according to the design parameters and the operation parameters of the pressure swing adsorption unit and the membrane separation unit in the hydrogen recovery system, setting the initial values of adsorption equilibrium kinetic parameters of each pressure swing adsorption device in the pressure swing adsorption unit, and setting the initial values of component permeation rate parameters of each membrane separation device in the membrane separation unit; wherein the hydrogen-containing stream in the hydrogen recovery system comprises a hydrogen-containing stream entering and exiting the pressure swing adsorption unit, the membrane separation unit, and a hydrogen-containing stream discharged to the refinery gas system;
the first solving unit is used for carrying out mathematical solving on a mathematical simulation model of the hydrogen recovery system to obtain the composition and the flow of product hydrogen output by the hydrogen recovery system;
the first judgment unit is used for judging whether the composition and the flow of the product hydrogen in the solving result of the first solving unit meet the preset calculation requirement or not, and if the composition and the flow of the product hydrogen in the solving result of the first solving unit meet the preset calculation requirement, the second modeling unit is executed; if the preset calculation requirement is not met and the iteration number does not reach the preset limit number, correcting one or more of the flow of the hydrogen-containing stream entering each pressure swing adsorption device in the pressure swing adsorption unit and each membrane separation device in the membrane separation unit, the initial values of the adsorption equilibrium kinetic parameters of each pressure swing adsorption device in the pressure swing adsorption unit and the initial values of the component permeation rate parameters of each membrane separation device in the membrane separation unit in the first initial value setting unit, and returning the corrected values to the first solving unit; if the preset calculation requirement is not met and the iteration number reaches the preset limit number, executing a second modeling unit;
the second modeling unit is used for establishing an integral optimization model of the hydrogen recovery system and respectively establishing subsystem optimization models of a pressure swing adsorption unit and a membrane separation unit in the hydrogen recovery system;
the second initial value setting unit is used for initializing the integral optimization model of the hydrogen recovery system and respectively initializing the subsystem optimization models of the pressure swing adsorption unit and the membrane separation unit; wherein initializing the global optimization model of the hydrogen recovery system comprises: setting a first iteration number upper limit of an integral optimization model, and flow rates of hydrogen-containing streams entering all pressure swing adsorption devices in the pressure swing adsorption unit and all membrane separation devices in the membrane separation unit; wherein initializing the subsystem optimization models of the pressure swing adsorption unit and the membrane separation unit comprises: setting a second iteration upper limit of each subsystem optimization model, and receiving the flow of hydrogen-containing streams which enter each pressure swing adsorption device in the pressure swing adsorption unit and each membrane separation device in the membrane separation unit and are set by the integral optimization model;
the second solving unit is used for respectively carrying out optimization solving on the subsystem optimization models of the pressure swing adsorption unit and the membrane separation unit and determining the optimization solving result of the overall optimization model according to the optimization solving result of each subsystem optimization model;
wherein the constraint conditions of the overall optimization model comprise: the difference between the preset flow rate of the hydrogen-containing stream entering the pressure swing adsorption unit and the flow rate of the hydrogen-containing stream actually processed by the pressure swing adsorption unit in the hydrogen recovery system is smaller than a preset relaxation factor, and the difference between the preset flow rate of the hydrogen-containing stream entering the membrane separation unit and the flow rate of the hydrogen-containing stream actually processed by the membrane separation unit in the hydrogen recovery system is smaller than a preset relaxation factor; the constraints of the overall optimization model further comprise: the pure hydrogen amount in the hydrogen-containing stream of the hydrogen recovery system is more than or equal to the pure hydrogen amount in the product hydrogen obtained by the pressure swing adsorption unit and the membrane separation unit; the pure hydrogen amount in the hydrogen-containing stream of the hydrogen recovery system is equal to the sum of the pure hydrogen amount in the product hydrogen obtained by the pressure swing adsorption unit and the membrane separation unit and the pure hydrogen content in the hydrogen-containing stream discharged to the gas system;
the objective function of the optimization model of the pressure swing adsorption unit subsystem is as follows: the minimum difference value between the preset flow rate of the hydrogen-containing stream entering the pressure swing adsorption unit in the hydrogen recovery system and the flow rate of the hydrogen-containing stream actually treated by the pressure swing adsorption unit;
the objective function of the optimization model of the membrane separation unit subsystem is as follows: the minimum difference value of the preset flow rate of the hydrogen-containing stream entering the membrane separation unit and the flow rate of the hydrogen-containing stream actually processed by the membrane separation unit in the hydrogen recovery system;
the constraint conditions of the pressure swing adsorption unit subsystem optimization model are as follows: the inlet and outlet of each pressure swing adsorption device in the pressure swing adsorption unit meet the requirements of material conservation and component conservation, the pressure of the raw material gas is greater than or equal to the pressure requirement of the inlet of the pressure swing adsorption device, the processing load of the pressure swing adsorption device is within the processing capacity range of the pressure swing adsorption device, the hydrogen and hydrogen purity of the product is greater than or equal to a preset purity value, and the preset component gas in the raw material gas cannot penetrate through a preset adsorption layer;
the constraint conditions of the optimization model of the membrane separation unit subsystem are as follows: the inlet and outlet of each membrane separation device in the membrane separation unit meet the requirements of material conservation and component conservation, the pressure of the raw material gas is greater than or equal to the pressure requirement of the inlet of the membrane separation device, the processing load of the membrane separation device is within the processing capacity range of the membrane separation device, and the raw material gas does not contain specified gas components;
the second judgment unit is used for judging whether the optimization solution result of the integral optimization model is converged or not, and if the optimization solution result is converged, the optimization solution process of the hydrogen recovery system is ended; if the iteration times reach the first iteration time upper limit without convergence, ending the optimization solving process of the hydrogen recovery system; and if the system is not converged and the iteration times do not reach the upper limit of the first iteration times, returning to the second solving unit to continue the optimization solving until the optimization model of each subsystem reaches the upper limit of the second iteration times.
7. The system for collaborative optimization of a hydrogen recovery system according to claim 6, wherein design parameters of a pressure swing adsorption unit and a membrane separation unit in the hydrogen recovery system include: the height, internal diameter, temperature, pressure, processing capacity, adsorbent loading, type, pore volume and specific surface area of each pressure swing adsorption unit; the design temperature, pressure, selectivity and processing capacity of each membrane separation unit; limiting the processing load of the compressor module in each pressure swing adsorption unit; process load limitations of the compressor modules in each membrane separation unit;
the operating parameters of the pressure swing adsorption unit and the membrane separation unit in the hydrogen recovery system comprise: the operating temperature, pressure and adsorption time of each pressure swing adsorption unit; the operating temperature and pressure of each membrane separation device; flow rate, composition and pressure of the hydrogen-containing stream.
8. The system for collaborative optimization of a hydrogen recovery system according to claim 6, wherein the first modeling unit, when building the mathematical simulation model of the hydrogen recovery system, is specifically configured to:
and respectively establishing a mathematical simulation model of each pressure swing adsorption device in the pressure swing adsorption unit, a mathematical simulation model of each membrane separation device in the membrane separation unit, a mathematical simulation model of a compressor module in each pressure swing adsorption device and a mathematical simulation model of a compressor module in each membrane separation device.
9. The system of claim 8, wherein the first modeling unit, when building the mathematical simulation model of each pressure swing adsorption unit in the pressure swing adsorption unit, is specifically configured to:
establishing a mathematical simulation model of each pressure swing adsorption device in the pressure swing adsorption unit by adopting an adsorption equilibrium equation, a mass transfer rate equation and a total mass transfer equilibrium equation;
wherein the adsorption equilibrium equation is:
Figure FDA0002838765940000081
wherein, thetaiRepresenting the coverage rate of a gas component i on the adsorbent in the mixed gas to be measured; q. q.siRepresenting the equilibrium adsorption quantity of a gas component i in the mixed gas to be measured on the adsorbent; q. q.smax,iRepresenting the maximum adsorption amount of the gas component i in the mixed gas to be measured on the adsorbent; b isiRepresents the langmuir adsorption constant of gas component i on the adsorbent; b isjRepresents the langmuir adsorption constant of gas component j on the adsorbent; piRepresenting the partial pressure of a gas component i in the mixed gas to be measured; pjWhich represents the partial pressure of the gas component j in the mixed gas to be measured.
10. The system of claim 8, wherein the first modeling unit, when building the mathematical simulation model of each pressure swing adsorption unit in the pressure swing adsorption unit, is specifically configured to:
establishing a mathematical simulation model of each pressure swing adsorption device in the pressure swing adsorption unit by adopting an adsorption equilibrium equation, a mass transfer rate equation and a total mass transfer equilibrium equation;
wherein the adsorption equilibrium equation is:
Figure FDA0002838765940000091
Figure FDA0002838765940000092
Figure FDA0002838765940000093
wherein, thetaiRepresenting the coverage rate of a gas component i on a certain layer of adsorbent in the mixed gas to be adsorbed; piRepresents the partial pressure of the gas component i in the mixed gas to be adsorbed; b isiRepresents the langmuir adsorption constant of gas component i on the layer of adsorbent; b isijRepresents the langmuir adsorption constant of component i on the layer of adsorbent in a binary gas mixture comprising component i and component j; kijDenotes a binary gas mixture comprising component i and component j in this layerDegree of influence of component j on the adsorption of component i when adsorbed on the adsorbent; y isjThe gas volume proportion of the gas component j in the mixed gas to be measured; ki,mixRepresents the adsorption influence parameter of all gas components in the mixed gas to be adsorbed on the gas component i.
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