A compressed carbon dioxide energy storage method and system coupled with a cogeneration unit

Abstract

The application discloses a compressed carbon dioxide energy storage method and system coupled with a heat and power generator set, and the method comprises the following steps: S1, preparing energy storage medium and performing energy storage; S2, performing energy release; S3, performing collaborative regulation by an intelligent control module: collecting each energy flow parameter and each equipment stress parameter, performing grid division, reserving each key solution based on an epsilon-dominance solution distribution, constructing a target function and setting a constraint condition, then performing population updating on the target function to obtain a current optimal working condition and each equipment adjustment parameter; and the intelligent control module controls the equipment. The application takes CO2 separated and purified from boiler flue gas as a circulating working medium, adopts an energy conversion core cycle of compression heat storage-expansion energy release, combines a molten salt heat storage tank and intelligent control, realizes efficient energy storage, release and poly-generation utilization, and the core process comprises three stages of carbon medium preparation, energy storage and energy release, and is throughout poly-generation utilization and intelligent optimization control.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power engineering and engineering thermophysics, in particular to a compressed carbon dioxide energy storage method and system coupled with a heat and power generating unit. BACKGROUND

[0002] Under the background of energy shortage and environmental crisis, improving energy utilization is increasingly valued. Compressed carbon dioxide energy storage is a kind of energy storage technology that uses electricity to compress carbon dioxide to high pressure (liquid or supercritical state) for storage, and releases and expands to generate power when needed. A heat and power generating unit is a system that provides both electricity and heat. Combining compressed carbon dioxide energy storage with a heat and power generating unit can effectively use abundant carbon dioxide to obtain electricity and heat, effectively address energy shortages, and reduce greenhouse gas emissions, which helps to protect the environment.

[0003] Currently, some technologies have adopted a combination of liquid carbon dioxide compression energy storage and a thermal power generating unit. For example, the energy storage device uses a carbon dioxide high-pressure gas storage module, a carbon dioxide low-pressure gas storage module, an energy release module, and an energy storage module. The outlet of the carbon dioxide low-pressure gas storage module is connected to the inlet of the energy storage module, the carbon dioxide high-pressure gas storage module, the energy release module, and the carbon dioxide low-pressure gas storage module in sequence. The thermal power generating unit device is connected to the energy release module through a circulating pipeline, and the thermal power generating unit device is connected to the energy storage module through a circulating pipeline. However, the combination of a thermal power generating unit and liquid carbon dioxide can improve energy utilization through cogeneration, but is limited by the conversion method of "heat determines electricity", resulting in weak peak shaving capability, and the waste of resources such as waste heat and compression heat, leading to high resource waste. In addition, some technologies use molten salt heat storage combined with carbon dioxide compression energy storage, which uses high-cost molten salt heat storage equipment for compression and heat storage, and heats carbon dioxide during energy release for subsequent energy conversion.

[0004] However, the above-mentioned traditional heat and power generating unit has at least the following three problems:

[0005] 1) The thermal power generating unit cannot balance the stability of heat supply and the demand for grid peak shaving, and the contradiction between peak shaving and heat and power is difficult to solve;

[0006] 2) The low-load waste heat and compression heat of the boiler are not efficiently utilized, resulting in poor efficiency and low energy utilization rate;

[0007] 3) The economy is insufficient, the price of the molten salt heat storage equipment itself is high, and the poor efficiency of the energy storage process, lack of accurate adjustment related to electricity consumption, further increases the cost. SUMMARY

[0008] Aiming at the above three problems, the purpose of the present application is to provide a compressed carbon dioxide energy storage method and system coupled with a heat supply generator set, which realizes the dynamic coupling of electricity-heat-storage through a two-stage heat exchanger, effectively improving the energy comprehensive utilization efficiency; also through the updating calculation of epsilon-dominance and objective function, the current optimal working condition and the corresponding parameters are accurately obtained, so as to use the intelligent control module for precise equipment adjustment, further improve the energy efficiency, and also solve the adjustment problem between heat supply stability and power grid regulation; in addition, different priority auxiliary response mechanisms are set for the expander, which is used to stably and safely respond when the working condition needs to be changed, effectively improving the equipment safety.

[0009] The above technical problems are solved by the following technical solutions:

[0010] Firstly, a compressed carbon dioxide energy storage method coupled with a heat supply generator set is proposed, including the following steps:

[0011] S1, preparing energy storage medium and performing energy storage: using a separation device to separate and purify low-pressure gaseous CO2 from the flue gas of the boiler as an energy storage medium, and then performing compression and cooling on the CO2, and storing the CO2 in a liquefied form into a high-pressure LCO2 storage tank to obtain high-pressure liquid CO2; wherein the heat generated during cooling is transferred to a molten salt storage tank;

[0012] S2, energy release: the high-pressure liquid CO2 in the high-pressure LCO2 storage tank is output into a heater; the heat stored in the molten salt storage tank is used to convert the high-pressure liquid CO2 into a gaseous state; the high-temperature and high-pressure gaseous CO2 is used to drive the expander to operate, and the high-temperature and high-pressure gaseous CO2 is converted into low-temperature and low-pressure gaseous CO2 and enters a low-pressure GCO2 storage tank or is discharged into the boiler; at the same time, the expander drives the steam turbine to work for energy release;

[0013] S3, intelligent control module for collaborative regulation: using an intelligent control module to real-time collect each energy flow parameter and corresponding each device stress parameter during energy storage and energy release, grid dividing each parameter and retaining each key solution based on epsilon-dominance solution distribution; determining the energy flow dimension and the device stress dimension based on each key solution; based on the energy flow dimension and the device stress dimension, constructing an objective function , and setting a constraint condition for constraint; wherein, is the energy release power, is the energy storage power consumption, is the heat utilization efficiency, is the CO2 circulation purity retention rate, and x represents the working condition; based on the epsilon-non-dominated solution distribution, the population of the objective function is updated to obtain the current optimal working condition and the corresponding device adjustment parameter; the intelligent control module controls the device based on the current optimal working condition and each device adjustment parameter.

[0014] Preferably, the separation device in step S1 adopts an air separation system for separating the flue gas of the boiler into a first medium and a second medium; wherein the CO2 concentration of the first medium is ≤5%, for emission; the CO2 concentration of the second medium is >95%, for use as an energy storage medium. Using the air separation system ensures that the collected CO2 concentration is high enough for subsequent energy storage operation, while also reducing unnecessary waste gas emission and enhancing environmental friendliness.

[0015] Preferably, when the high-pressure LCO2 tank outputs high-pressure liquid CO2 in step S2, it also enters a dry ice preparation device for preparing dry ice; or it also enters a solution production unit for solution preparation. Allowing high-pressure liquid CO2 to be used for preparing dry ice or solution enhances economic benefits and expands the use scenarios.

[0016] Preferably, the divided grid in step S3 includes at least an energy consumption grid, an efficiency grid, and a device stress grid, each energy flow parameter and each device stress parameter are combined in various grids, and each parameter formed by each combination of the same operating condition is determined as each key solution based on ε-dominant solution distribution. By applying grid division and ε-dominant solution distribution-based solution distribution, the optimal solution can be found in a complex multi-dimensional parameter space.

[0017] Preferably, after constructing the objective function of the operating condition in step S3, the relationship between the variable x and the thermal utilization efficiency is fitted through experimental calibration or a mechanism model based on thermodynamic cycle equations.

[0018] Preferably, the constraint conditions include medium state constraints and energy conservation constraints; wherein the medium state constraints include: CO2 phase change boundary, limited pressure of each tank, temperature combination, melting point or boiling point of molten salt, temperature range of molten salt tank, and the temperature combination is the combination of post-energy storage temperature and post-energy release temperature; the energy conservation constraints include: heat generated during compression = heat absorbed by molten salt tank + heat loss, heat input during energy release = heat demand of expander + heat loss. Setting constraint conditions can not only protect equipment but also ensure the rationality of control.

[0019] Preferably, in step S3, the population is updated based on the joint of three types of populations to generate the current optimal operating condition, the three types of populations including a main population, an archive population, and an auxiliary population; wherein the main population is used to explore new operating conditions, the archive population stores ε-non-dominated solutions, and the auxiliary population updates the operating condition through parameter mutation or parameter crossover; the results of the main population exploration and the auxiliary population update are combined and then screened for non-inferior solutions to determine the current optimal operating condition; the intelligent control module controls the equipment according to the current optimal operating condition and each parameter of the three types of populations. Through population updating, the system can continuously optimize itself and maintain an optimal operating state, which is crucial for long-term stable operation.

[0020] Preferably, the molten salt storage tank comprises a molten salt heat storage tank and a molten salt cold storage tank, the molten salt in the molten salt storage tank is used to absorb heat generated during cooling and to convert high-pressure liquid CO2 into a gaseous state, the part of the molten salt with a temperature higher than a predetermined threshold is stored in the molten salt heat storage tank, and the part of the molten salt with a temperature lower than the predetermined threshold is stored in the molten salt cold storage tank. The heat absorption and supply by the molten salt storage tank effectively realizes heat circulation.

[0021] Preferably, the expander is provided with a jet generator and an automatic variable working condition control mechanism for auxiliary response when the intelligent control module controls the equipment; the control mechanism is as follows: the priority of operation is set from high to low: intake adjustment > impeller damping adjustment > exhaust adjustment; when the intake adjustment is performed, the opening degree of the output valve of the high-pressure LCO2 storage tank and the heat exchange power of the heater are adjusted according to the CO2 inlet pressure or CO2 flow demand of the expander; if a picometer trend of the built-in generator speed is detected, the CO2 temperature entering the expander is controlled by the hot flow adjustment valve, and the intake adjustment valve opening degree is reduced to reduce the CO2 intake and suppress the work, and the hot flow adjustment valve is linked to maintain the intake temperature stable and ensure the expander efficiency; when the impeller damping adjustment is performed, if the intake adjustment cannot suppress the increase of the generator speed, the corresponding valve opening degree of the jet generator or the impeller damping of the generator is adjusted to reduce the generator speed; when the exhaust adjustment is performed, the exhaust valve of the expander is opened and the exhaust valve opening degree is adjusted to release part of the CO2. The automatic variable working condition control mechanism of the expander ensures that the expander can safely and efficiently operate under various working conditions, reduces the risk of failure, prolongs the service life of the equipment, and facilitates long-term stable use.

[0022] Compared with the prior art, the present application has the following beneficial effects:

[0023] The technical scheme of the present application realizes dynamic coupling of electricity-heat-storage through the two-stage heat exchanger, effectively improves the energy comprehensive utilization efficiency; also accurately obtains the current optimal working condition and corresponding parameters through the update calculation of ε-dominance and objective function, so as to use the intelligent control module for precise equipment adjustment, further improves the energy efficiency, and solves the adjustment problem between heating stability and grid regulation; in addition, the expander is provided with an auxiliary response mechanism with different priorities for stable and safe response when the working condition needs to be changed, effectively improving the safety of the equipment. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 A compressed carbon dioxide energy storage method flow chart coupled with a heat supply generator set;

[0025] Figure 2 A main frame schematic diagram of a compressed carbon dioxide energy storage system coupled with a heat supply generator set;

[0026] Figure 3 This is a partial flowchart of a population update process.

[0027] Figure 4 This is a flowchart illustrating the operation of an expander under varying operating conditions according to a control mechanism. Detailed Implementation

[0028] The following will be combined with the present invention. Figures 1 to 4 The technical solutions in the embodiments of the present invention will be described in detail below.

[0029] like Figure 1 The diagram shows a flowchart of a compressed carbon dioxide energy storage method coupled with a heating and power generator set. By constructing a two-stage heat exchanger and combining it with intelligent control module control, dynamic coupling of electricity, heat, and storage is achieved. A variable operating condition control mechanism is also set for the expander to ensure equipment safety and long-term stability. Furthermore, using ε-domination and constructing an objective function for population updates, the optimal operating condition can be accurately found. For example, increasing the expander's power output to accelerate generator generation, or decreasing the expander's power output to reduce generator speed, thereby effectively regulating the operation of various devices and improving overall energy efficiency.

[0030] The method specifically includes the following steps:

[0031] S1. Preparation of Energy Storage Medium and Energy Storage: Low-pressure gaseous CO2 is separated and purified from the boiler flue gas using a separation device and used as the energy storage medium. The energy storage medium is then compressed by a compressor and cooled by a cooler, converting the low-pressure gaseous CO2 into high-pressure liquid CO2, which is stored in a high-pressure LCO2 storage tank (L represents liquid). During cooling, the heat generated is transferred to a molten salt thermal storage tank for storage.

[0032] The separation device can employ an air separation system, an industrial device used to separate different gaseous components from air. This system can separate boiler flue gas into a first medium and a second medium. The first medium has a CO2 concentration ≤5% and is released into the air; the second medium has a CO2 concentration >95% and is used as an energy storage medium. Using an air separation system ensures that the collected CO2 concentration is sufficiently high for subsequent energy storage operations, while also reducing unnecessary waste gas emissions and enhancing environmental friendliness.

[0033] S2, energy release: first, high-pressure LCO2 tank outputs high-pressure liquid CO2 into the heater, at the same time, the heat stored in the molten salt storage tank is used to convert high-pressure liquid CO2 into gas. Then, high-temperature and high-pressure gaseous CO2 is used to drive the expander to operate, and the expander drives the steam turbine to operate for energy release, thereby realizing the conversion of heat energy into mechanical energy and electrical energy; high-temperature and high-pressure gaseous CO2 is converted into low-temperature and low-pressure gaseous CO2, which enters the low-pressure GCO2 tank or is discharged into the boiler. G represents gaseous, and the low-pressure GCO2 tank is a low-pressure gaseous carbon dioxide storage tank.

[0034] In this embodiment, when the high-pressure LCO2 tank outputs high-pressure liquid CO2, it can also be divided into multiple paths for separate transmission, for example, into a dry ice preparation device for preparing dry ice, or into a solution production unit for solution preparation. Allowing high-pressure liquid CO2 to be used to prepare dry ice or solution enhances economic benefits and expands the use scenarios.

[0035] In this embodiment, the cooler and the heater are each connected with a molten salt storage tank, which includes a molten salt heat storage tank and a molten salt cold storage tank. The molten salt in the molten salt heat storage tank is used to absorb the heat generated during cooling and to provide heat when converting high-pressure liquid CO2 into gas. A large amount of molten salt is stored in the molten salt heat storage tank and the molten salt cold storage tank, and the part of the molten salt with a temperature higher than a predetermined threshold is stored in the molten salt heat storage tank, and the part of the molten salt with a temperature lower than the predetermined threshold is stored in the molten salt cold storage tank, so as to realize the transfer of heat by using molten salt.

[0036] S3, intelligent control module for collaborative regulation: the intelligent control module is used to collect each energy flow parameter and each device stress parameter corresponding to each device during energy storage and energy release in real time. The energy flow parameters: covering three types of energy or substance flow parameters, i.e. electricity (compressor power consumption, expander power generation), heat (molten salt heat storage power or heat release power, CO2 compression or expansion heat exchange power), and substance (CO2 medium flow, molten salt storage tank pressure change rate), the power can also be converted into corresponding electricity or energy based on time, which can reflect the core process of system energy conversion and transmission. The device stress dimensions: focusing on compressor impeller stress (reflecting rotation speed and inlet pressure), expander blade fatigue degree (reflecting airflow impact frequency and intensity), and molten salt storage tank pressure deformation (reflecting pressure fluctuation amplitude), etc., which reflect the device safe operation boundary. These parameters can all assist in reflecting whether the overall system is in an energy storage state, an energy release state or a transition state, i.e. a state between the energy storage state and the energy release state.

[0037] After obtaining the above parameters, each parameter is meshed, and the meshed grid at least includes an energy consumption grid, an efficiency grid, and a device stress grid. Each energy flow parameter and each device stress parameter is combined in each grid, and each parameter formed by each combination under the same operating condition is taken as each key solution based on the ε-dominant solution distribution, so that the optimal solution can be found in the complex multi-dimensional parameter space. For example, when the "compressor power consumption" is combined with the "molten salt heat storage power or heat release power", the compressor corresponds to three cases of accelerating work, stable work and deceleration of the expander, and the compressor corresponds to three power consumption cases of high power consumption, medium power consumption and low power consumption. The change of molten salt heat storage power or the increase and decrease of heat release power is also associated with the three cases of operation of the expander, for example, the molten salt heat storage power has three cases of high heat storage, medium heat storage and low heat storage, and the molten salt heat release power has three cases of high heat release, medium heat release and low heat release. If the numerical range of both falls into the same preset grid (i.e. the system state indicated by both belongs to the same working condition, for example, "compressor medium power consumption and molten salt medium heat storage" corresponds to "expander stable work"), it means that the running state corresponding to the two parameters is compatible in the grid. In the parameter combination in the same grid, the core of "optimization" is to evaluate based on the multi-objective function of the system. The compressor power consumption and the molten salt heat storage power or heat release power are combined, and if the working conditions indicated by both are in the same grid, the optimal principle of the system is selected.

[0038] The key solution directly maps the current core operating state of the system (such as energy storage or energy release mode, load level); as an input boundary condition for subsequent target function (feff(x)) optimization, it narrows down the parameter range of population update and improves optimization efficiency; the intelligent control module quickly locates the device adjustment direction based on the key solution (for example, when the key solution shows "low efficiency and stress safety", the compression ratio is adjusted to improve efficiency). In short, this process eliminates redundant parameter combinations based on the ε-dominant criterion, focuses on key solutions that determine the system operating condition, and provides simplified and effective input basis for subsequent multi-objective optimization and accurate device control.

[0039] The energy flow parameters correspond to the energy flow dimension, and the device stress parameters correspond to the device stress dimension. After the foregoing optimization selection, the screened energy flow dimension and device stress dimension can be obtained. Based on the energy flow dimension and the device stress dimension, the conversion efficiency of electricity-heat-carbon can be integrated to construct the target function , and the constraint condition is set to constrain; wherein x represents the working condition, is the energy release power, is the energy storage power consumption, is the heat utilization efficiency, i.e. the heat supply of the molten salt heat storage tank ÷ the heat production during compression, The CO2 circulation purity retention rate reflects the influence of separation and purification cost on efficiency. Based on the ε-non-dominated solution, the objective function is updated again to obtain the current optimal working condition and the corresponding adjustment parameters of each device; the intelligent control module controls the device based on the current optimal working condition and the adjustment parameters of each device.

[0040] In this embodiment, after constructing the objective function of the working condition, the relationship between the variable x and the heat utilization efficiency is fitted through experimental calibration or a mechanism model based on the thermodynamic cycle equation. The relationship between the two is fitted in order to establish a quantitative correlation between the heat utilization efficiency ηheat(x) in the objective function and the key variable x of the system, for example:

[0041] Reference of variable x: refers to the core parameter affecting the operation of the system, including CO2 compression ratio, molten salt heat storage temperature, heater heat exchange power, device operating pressure, etc.

[0042] The two fitting methods include:

[0043] 1) Experimental calibration: by actually running the system, changing the value of the variable x (such as adjusting different compression ratios), measuring the corresponding heat utilization efficiency (the ratio of molten salt heating capacity to compression heat generation capacity), and obtaining the relationship formula between x and ηheat(x) through data fitting (such as linear regression, curve fitting).

[0044] 2) Mechanism model: based on the thermodynamic cycle equation (such as the law of conservation of energy, heat transfer equation, etc.), the theoretical relationship between the variable x (such as temperature, pressure) and the heat utilization efficiency is derived, and the model parameters are corrected combined with the actual working condition to form a directly calculable correlation.

[0045] Through the fitting method, the heat utilization efficiency, which is a key indicator closely related to the operation of the expander, can be converted into a quantifiable and optimized function, providing a basis for subsequent population updating and optimal working condition solving based on the objective function.

[0046] In this embodiment, the constraint conditions include medium state constraints and energy conservation constraints; wherein the medium state constraints include: CO2 phase change boundary (such as critical temperature 31.1℃, critical pressure 7.38MPa), limited pressure of each storage tank, temperature combination (combination of temperature after energy storage and temperature after energy release, to avoid supercritical state out of control), melting point or boiling point of molten salt (such as eutectic salt of sodium nitrate-potassium nitrate about 220℃ melting point, 800℃ boiling point), temperature range of molten salt storage tank; the energy conservation constraints include: heat generation during compression = heat absorption of molten salt tank + heat loss, heat input during energy release = heat demand of expander + heat loss. Setting the constraint conditions can not only protect the equipment, but also ensure the rationality of the control.

[0047] For example, Figure 3The diagram shows a partial flowchart of a population update process. During population update, the current optimal operating condition is generated through the joint operation of three populations: the main population, the archived population, and the auxiliary population. The main population explores new operating conditions to indicate whether the operating conditions need to change. The archived population stores ε-non-dominated solutions, specifically storing non-dominated solutions selected through the ε-dominance criterion (i.e., optimal equilibrium solutions that cannot improve one objective without compromising another). The auxiliary population updates the operating condition through parameter mutation or parameter crossover. The results from the main population's exploration and the auxiliary population's updates are merged and further filtered for non-dominated solutions to determine the current optimal operating condition. The intelligent control module controls the equipment based on the current optimal operating condition and each parameter from the archived population. Through population update, the system can continuously self-optimize and maintain an optimal operating state, which is crucial for long-term stable operation.

[0048] like Figure 4 The diagram shown is an operating flow chart of an expander under varying operating conditions according to a control mechanism, combined with... Figure 4 As shown, the expander is equipped with a jet generator and an automatic variable operating condition control mechanism to assist in equipment control by the intelligent control module. The control mechanism is as follows: Operating priority is set from high to low: intake regulation > impeller damping regulation > exhaust regulation; during intake regulation, the opening of the high-pressure LCO2 storage tank's output valve and the heater's heat exchange power are adjusted according to the expander's CO2 inlet pressure or CO2 flow rate requirements; if a rapid increase in the speed of the built-in generator is detected, for example, if the continuous increase in speed exceeds a set time threshold, the heat flow regulating valve is activated to control the CO2 temperature entering the expander. The heat flow regulating valve is activated when a rapid increase in the speed of the expander's built-in generator is detected to maintain stable intake temperature and ensure expander efficiency; it works in conjunction with other components controlling the expander inlet side; the heat flow regulating valve is located on the heat exchange or carbon dioxide gas delivery path related to the expander intake and is used to regulate the temperature of the gas entering the expander. When adjusting the impeller damping, if the intake adjustment cannot prevent the generator speed from increasing, the opening of the corresponding valve on the jet generator or the impeller damping of the generator is adjusted to reduce the generator speed. When adjusting the exhaust, the exhaust valve of the expander is opened and its opening is adjusted to release some CO2. The expander's automatic variable operating condition control mechanism ensures that the expander can operate safely and efficiently under various operating conditions, reduces the risk of failure, extends equipment life, and facilitates long-term stable use.

[0049] When the adjustment of the jet flow generator is performed, if the intake adjustment cannot suppress the generator speed from rising, the corresponding valve opening degree of the jet flow generator is adjusted to spray fluid (such as gas or liquid at a specific pressure) to the impeller area. The sprayed fluid collides with and rubs against the impeller blades, increasing the resistance (i.e., impeller damping) that the impeller experiences when rotating. In this way of dynamic intervention, the damping effect can be enhanced in real time without interrupting the operation of the expander, thereby reducing the generator speed and ensuring the safe and stable operation of the equipment under variable working conditions.

[0050] As shown in Figure 2 Fig. 1 is a schematic diagram of a main frame of a compressed carbon dioxide energy storage system coupled with a heat and power generator set, which includes a plurality of devices: a boiler, an air separation system, a low-pressure GCO2 storage tank, a compressor, a cooler, a molten salt heat storage tank, a molten salt cold storage tank, an expander, a heater, a high-pressure LCO2 storage tank, a solution production unit, a dry ice preparation device, a steam turbine, and an intelligent control module for regulating other devices.

[0051] The air separation system is connected to the boiler and the low-pressure GCO2 storage tank, respectively. The first end of the low-pressure GCO2 storage tank is connected to the high-pressure LCO2 storage tank through the compressor and the cooler in sequence. The second end of the low-pressure GCO2 storage tank is connected to the high-pressure LCO2 storage tank through the expander and the heater in sequence. The molten salt heat storage tank and the molten salt cold storage tank are connected between the cooler and the heater, respectively. The expander is used to drive the steam turbine. The solution production unit and the dry ice preparation device are connected to the high-pressure LCO2 storage tank. In addition, a monitor is arranged at the inlet of the expander for real-time monitoring of the CO2 pressure, temperature, and flow rate at the inlet. At the same time, the generator speed and power of the expander are transmitted to the intelligent control module for identifying whether the system is in an energy storage state (carbon dioxide compression storage, expander standby or low load), an energy release state (carbon dioxide expansion work, full load or variable load), or a transition state (such as energy storage to energy release switching). The purpose is to ensure that the expander stably generates power, the generator speed or power fluctuation is within a safe and efficient range, and equipment damage (such as rapid speed rise and impeller overload) is avoided when the working condition needs to be changed.

[0052] In summary, the present application realizes dynamic coupling of electricity-heat-storage through two-stage heat exchangers, effectively improving the energy comprehensive utilization efficiency. Through the update calculation of ε-dominance and objective function, the current optimal working condition and corresponding parameters are accurately obtained, so that precise equipment adjustment is performed by the intelligent control module, further improving energy efficiency, and solving the adjustment problem between heat stability and grid regulation. In addition, different priority auxiliary response mechanisms are set for the expander to stably and safely respond when the working condition needs to be changed, effectively improving equipment safety, and having significant progress.

[0053] The above examples only illustrate the technical idea of the present application, and cannot be used to limit the protection scope of the present application. Any modification made according to the technical idea of the present application on the basis of the technical scheme falls within the protection scope of the present application.

Claims

1. A compressed carbon dioxide energy storage method coupled with a combined heat and power generator, characterized by, It comprises the following steps: S1, preparing energy storage medium and energy storage: The separation device is used to separate and purify low-pressure gaseous CO2 from the flue gas of the boiler as an energy storage medium. After compression and cooling, the CO2 is stored in the form of liquefaction in the high-pressure LCO2 storage tank to obtain high-pressure liquid CO2. The heat generated during cooling is transferred to the molten salt storage tank; S2, energy release: The high-pressure LCO2 storage tank outputs high-pressure liquid CO2 into the heater. The heat stored in the molten salt storage tank is used to convert the high-pressure liquid CO2 into a gaseous state. The high-temperature and high-pressure gaseous CO2 is used to drive the operation of the expander, which is converted into low-temperature and low-pressure gaseous CO2 and enters the low-pressure GCO2 storage tank or is discharged into the boiler. At the same time, the expander drives the turbine to work for energy release; S3, intelligent control module for collaborative control: The intelligent control module is used to collect each energy flow parameter and corresponding each device stress parameter during energy storage and energy release in real time. Each parameter is grid divided and each key solution is retained based on ε-dominant solution distribution. The energy flow dimension and device stress dimension are determined based on each key solution; Construct a target function based on energy flow dimension and equipment stress dimension At the same time, set constraints for constraints; wherein, is the energy release power generation, is the energy storage power consumption, is the heat utilization efficiency, is the CO2 circulation purity retention rate, represents the working condition; Based on the ε-non-dominated solution distribution, the population of the objective function is updated to obtain the current optimal working condition and the corresponding adjustment parameter of each device. The intelligent control module controls the device based on the current optimal working condition and the adjustment parameter of each device.

2. The compressed carbon dioxide energy storage method coupled with a cogeneration unit of claim 1, wherein, The separation device in step S1 adopts an air separation system, which is used to separate the flue gas of the boiler into a first medium and a second medium. The CO2 concentration of the first medium is ≤5%, which is used for emission. The CO2 concentration of the second medium is >95%, which is used as an energy storage medium.

3. The compressed carbon dioxide energy storage method coupled with a cogeneration unit of claim 1, wherein, In step S2, when the high-pressure LCO2 storage tank outputs high-pressure liquid CO2, it also enters the dry ice preparation device for dry ice preparation, or the solution production unit for solution preparation.

4. The compressed carbon dioxide energy storage method coupled with a cogeneration unit of claim 1, wherein, In step S3, the divided grid includes at least an energy consumption grid, an efficiency grid and a device stress grid. Each energy flow parameter and each device stress parameter is combined in each grid. Based on the ε-dominant solution distribution, each parameter of the same operating condition formed during each combination is taken as each key solution.

5. The compressed carbon dioxide energy storage method coupled with a cogeneration unit of claim 1, wherein, After the objective function of the working condition is constructed in step S3, the variable relationship with the heat utilization efficiency.

6. The compressed carbon dioxide energy storage method coupled with a cogeneration unit of claim 1, wherein, The constraint conditions include medium state constraints and energy conservation constraints. The medium state constraints include CO2 phase change boundary, limited pressure of each storage tank, temperature combination, melting point or boiling point of molten salt, temperature range of molten salt storage tank, and temperature combination of post-energy storage temperature and post-energy release temperature. The energy conservation constraints include heat generated during compression = heat absorbed by molten salt tank + heat loss, and heat input during energy release = heat demand of expander work + heat loss.

7. The compressed carbon dioxide energy storage method coupled with a cogeneration unit of claim 1, wherein, The population updating in step S3 is based on the combination of three types of populations to generate the current optimal working condition, the three types of populations including a main population, an archive population and an auxiliary population; the main population is used to explore new working conditions, the archive population stores ε-non-dominated solutions, and the auxiliary population updates working conditions through parameter mutation or parameter crossover; the results of the main population exploration and the auxiliary population update are combined and then screened for non-inferior solutions to determine the current optimal working condition; and the intelligent control module controls the equipment according to the current optimal working condition and the three types of populations.

8. The compressed carbon dioxide energy storage method coupled with a cogeneration unit of claim 1, wherein, The molten salt storage tank includes a molten salt heat storage tank and a molten salt cold storage tank, the molten salt in the molten salt storage tank is used to absorb heat generated during cooling and to convert high-pressure liquid CO2 into a gaseous state, the part of the molten salt with a temperature higher than a predetermined threshold is stored in the molten salt heat storage tank, and the part of the molten salt with a temperature lower than the predetermined threshold is stored in the molten salt cold storage tank.

9. The compressed carbon dioxide energy storage method coupled with a cogeneration unit of claim 1, wherein, The expander is provided with a jet generator and an automatic working condition changing control mechanism for assisting in response when the intelligent control module controls the equipment; the control mechanism is as follows: The priority of operation is set from high to low: intake adjustment > impeller damping adjustment > exhaust adjustment; When the intake adjustment is performed, the opening degree of the output valve of the high-pressure LCO2 storage tank and the heat exchange power of the heater are adjusted according to the CO2 inlet pressure or CO2 flow demand of the expander; if a flying trend of the built-in generator speed is detected, the CO2 temperature entering the expander is controlled by the hot flow regulating valve, the intake adjustment valve opening degree is reduced, the CO2 entering amount is reduced, and the work is suppressed, and the hot flow regulating valve is linked to maintain the intake temperature stable and ensure the expander efficiency; When the impeller damping adjustment is performed, if the intake adjustment cannot suppress the increase of the generator speed, the corresponding valve opening degree of the jet generator or the impeller damping of the generator is adjusted to reduce the speed of the generator; When the exhaust adjustment is performed, the exhaust valve of the expander is opened and the exhaust valve opening degree is adjusted to release part of the CO2.

Images