Method for coexistence energy storage operation of co2 process under thermal inertia of eo reaction

Abstract

The application provides a CO2 process symbiotic energy storage operation method under EO reaction thermal inertia, and relates to the technical field of chemical waste heat utilization and energy storage operation control.The application obtains an EO reaction waste heat energy supply state and a phase change heat storage unit heat storage state, forms an allowed heat extraction range based on a current heat extraction amount, an EO reaction load prediction amount, a reaction thermal inertia relationship and a heat extraction boundary, determines a total heat extraction amount in the allowed heat extraction range, and configures the total heat extraction amount to each temperature level phase change heat storage unit according to a temperature level descending relationship, determines a matching relationship between a compression driving power and a phase change heat storage heat release amount in combination with a green electricity signal, a heat storage state and a CO2 energy storage and utilization demand, calculates a physical property response according to a temperature and pressure disturbance to correct CO2 energy storage operation parameters, forms a whole life cycle carbon emission constraint in combination with equipment operation intensity, and generates an operation instruction of an EO reaction thermal safety limit.The application is beneficial to coordinating EO waste heat supply, CO2 energy storage and utilization, green electricity consumption and equipment life.

Description

Technical Field

[0001] This invention relates to the field of chemical waste heat utilization and energy storage operation control technology, and particularly to a method for co-existing energy storage operation of CO2 process under the thermal inertia constraint of EO reaction. Background Technology

[0002] In the ethylene oxide production process, the ethylene oxidation reaction continuously releases heat, and the reactor bed has a large heat capacity. Changes in heat recovery typically result in a lag in the reaction temperature response. Existing waste heat recovery methods are mostly configured around high-temperature steam generation, with insufficient utilization of medium- and low-temperature waste heat. Fluctuations in reaction load can also lead to instability in the available heat, making it difficult to provide a continuous and controllable heat source for energy storage processes.

[0003] CO2 energy storage systems require auxiliary heat during compression, expansion, and tank insulation. Existing solutions typically rely on electric heating or external fuel heating, failing to establish a stable process coupling with waste heat from chemical plants. Meanwhile, energy storage dispatch is primarily based on operational efficiency or electricity price response, neglecting the safety boundaries of ethylene oxide reaction temperatures, the lag characteristics of waste heat supply, and the need for green electricity consumption. This easily leads to an energy mismatch where waste heat emissions and external heating coexist.

[0004] Furthermore, CO2 energy storage processes often operate near a critical point, and the properties of the working fluid are highly sensitive to temperature and pressure disturbances. If existing control methods excessively pursue instantaneous efficiency, they may exacerbate equipment fatigue, seal wear, and working fluid leakage, causing carbon emissions during manufacturing, maintenance, and replacement to offset the emission reduction benefits during operation.

[0005] Therefore, how to improve the stability of waste heat utilization, reduce carbon emissions from auxiliary heat use, and ensure the long-term operational reliability of equipment while ensuring the safety of reaction heat has become a problem that related process co-existing energy storage technologies need to solve. Summary of the Invention

[0006] To address the problems of existing waste heat utilization processes in EO reactions where waste heat output fluctuates with reaction load, difficulty in coordinating heat and electricity demands in CO2 energy storage processes, the impact of near-critical CO2 property fluctuations on operational stability, and the lack of inclusion of equipment lifespan losses in low-carbon operation decisions, this invention provides a method for co-storage operation of CO2 processes under the thermal inertia constraint of EO reactions.

[0007] The present invention provides a method for co-existing energy storage operation of CO2 processes under the thermal inertia constraint of EO reaction, comprising:

[0008] S1. Obtain the operating status of the EO reaction waste heat supplying energy to the CO2 energy storage process and the heat storage status of the phase change heat storage unit. Based on the current heat recovery, the predicted EO reaction load, the reaction heat inertia relationship and the heat recovery boundary, screen candidate heat recovery capacity to form an allowable heat recovery range.

[0009] S2. Within the allowable heat extraction range, determine the total heat extraction capacity. Based on the temperature decrease relationship of the waste heat from the EO reaction along the heat exchange path, allocate the total heat extraction capacity to phase change heat storage units at different temperature levels to form a heat extraction distribution result.

[0010] S3. Receive the green electricity signal, and determine the energy matching relationship between the compression drive power and the heat release of the phase change thermal storage unit, in combination with the thermal storage status of the phase change thermal storage unit and the energy demand of the CO2 energy storage process.

[0011] S4. Calculate the physical property response based on the temperature and pressure disturbances at the operating point of the CO2 energy storage process, use the physical property response to correct the CO2 energy storage operating parameters, and form a full life cycle carbon emission constraint based on the operating intensity of the pressurization and expansion equipment. Combine the heat extraction and distribution results, energy consumption matching relationship, corrected CO2 energy storage operating parameters and full life cycle carbon emission constraint to generate CO2 process co-existing energy storage operation instructions subject to EO reaction heat safety limits.

[0012] Preferably, in step S1, the heat extraction boundary includes the reaction temperature boundary, the heat extraction ratio boundary, and the heat extraction change rate boundary; screening candidate heat extraction amounts to form an allowable heat extraction range includes: calculating the reaction temperature prediction trajectory corresponding to each candidate heat extraction amount based on the lumped heat balance relationship of the EO reactor, and including candidate heat extraction amounts whose reaction temperature prediction trajectory is within the reaction temperature boundary, whose candidate heat extraction amounts are within the heat extraction ratio boundary, and whose candidate heat extraction change rate is within the heat extraction change rate boundary into the allowable heat extraction range.

[0013] Preferably, in step S1, if there are no candidate heats that can be included in the allowable heat extraction range, the reaction temperature boundary is kept unchanged and the heat extraction ratio boundary and the heat extraction change rate boundary are adjusted; if the allowable heat extraction range is still not formed after adjustment, the allowable heat extraction range is set to the zero heat extraction range, so that step S2 determines the total heat extraction to zero, and step S3 corrects the phase change heat storage heat release based on the heat release capacity of the phase change heat storage unit.

[0014] Preferably, in step S2, the total heat output is decomposed into upstream heat output section ...

[0015] Preferably, in step S2, the upper limit of the allocation for each heat extraction section is determined based on the real-time heat extraction power of the heat extraction section and the heat storage power of the phase change heat storage unit. When the sum of the upper limits of each allocation is greater than zero, the total heat extraction is allocated according to the proportion of each upper limit. When the sum of the upper limits of each allocation is zero, the heat extraction of the upstream heat extraction section, the heat extraction of the midstream heat extraction section, and the heat extraction of the downstream heat extraction section are all set to zero.

[0016] Preferably, in step S3, the heat release of the first phase change heat storage unit corresponds to steam generation and turbine stage inlet heating, the heat release of the second phase change heat storage unit corresponds to turbine stage reheating, and the heat release of the third phase change heat storage unit corresponds to pump preheating and high-pressure CO2 storage tank insulation. The heat release of phase change heat storage is determined according to the above correspondence.

[0017] Preferably, in step S3, when the phase change thermal storage unit releases heat to the CO2 energy storage process, if the heat release capacity of the corresponding phase change thermal storage unit is lower than the heat demand in the energy demand of the CO2 energy storage process, and the adjacent high-temperature phase change thermal storage unit has heat release capacity, then the cross-stage heat supply is determined according to the direction from the first phase change thermal storage unit to the second phase change thermal storage unit and from the second phase change thermal storage unit to the third phase change thermal storage unit, and the cross-stage heat supply is corrected according to the grade loss corresponding to the cross-stage heat supply.

[0018] Preferably, in step S3, the compression drive power includes electric drive compression power and steam turbine auxiliary drive power; the energy demand level is determined according to the energy demand of the CO2 energy storage process, and the total compression power is determined according to the energy demand level; when the green electricity signal indicates that green electricity is available, the total compression power is configured as electric drive compression power; when the green electricity signal indicates that green electricity is unavailable and the first phase change thermal storage unit has heat that can be released, the steam turbine auxiliary drive power is used to reduce the total compression power, and the reduced power is used as the electric drive compression power.

[0019] Preferably, in step S4, pressure disturbance and temperature disturbance are introduced into the property calculation to calculate the relative changes in CO2 density, CO2 specific heat and CO2 viscosity, and synthesize the property response according to the corresponding weights; when the property response is not less than the property response threshold, the correction direction is determined according to the position of the CO2 energy storage process operating point relative to the CO2 critical point, and the CO2 energy storage operating parameters are corrected according to the priority order of pump inlet temperature, turbine inlet temperature and working fluid flow rate.

[0020] Preferably, in step S4, the normalized operating intensity of the liquid pressurization pump or CO2 turbine during the scheduling and control cycle is obtained, where the normalized operating intensity is the ratio of the equipment output power to the equipment rated power; the fatigue accumulation factor is calculated according to the normalized operating intensity, the scheduling and control cycle, and the equipment design life, and an implicit carbon penalty item is formed according to the fatigue accumulation factor, the equipment design life, and the implicit carbon emissions during the equipment manufacturing, transportation, and installation stages; the implicit carbon penalty item is included in the evaluation target of the CO2 process co-storage operation command, and when the fatigue accumulation factor exceeds the fatigue threshold, the upper limit of the compression drive power or the upper limit of the working fluid flow rate is lowered.

[0021] Compared with existing technologies, the advantages of this invention are as follows: This invention filters candidate heat recovery capacity by using the reaction heat inertia relationship and heat recovery boundary, enabling the waste heat from the EO reaction to form a controllable heating range within the thermal safety boundary, which helps solve the problems of passive waste heat recovery and unstable heat source output; through temperature level gradient distribution and phase change heat storage and release matching, it establishes a corresponding relationship between waste heat at different temperatures on the EO side and the CO2 energy storage heat utilization link, which helps reduce the emission of medium and low temperature waste heat and the demand for external auxiliary heating; through the matching of green electricity signals, energy demand, and compression drive power, it helps increase the proportion of low-carbon electricity participating in charging and storage operation; and through CO2 physical property response to correct operating parameters and incorporate fatigue accumulation and implicit carbon penalties into the evaluation targets of operating commands, it helps reduce equipment degradation and life-cycle carbon emissions caused by near-critical physical property fluctuations. Attached Figure Description

[0022] Figure 1 This is a schematic diagram illustrating the process symbiotic connection between the waste heat from the EO reaction and the CO2 energy storage process.

[0023] Figure 2 This is a flowchart illustrating the operation method of CO2 co-existing energy storage under the thermal inertia constraint of EO reaction.

[0024] Figure 3 This is a schematic diagram of the simulation results of the CO2 process co-storage operation under the thermal inertia constraint of EO reaction. Detailed Implementation

[0025] This embodiment provides a method for co-storage operation of CO2 process under the thermal inertia constraint of EO reaction, used to allocate the waste heat of EO reaction to the CO2 energy storage process via a phase change heat storage process. The controller performs heat extraction screening, cascaded heat storage allocation, green electricity and waste heat energy matching, CO2 operating parameter correction, and full life cycle carbon emission constraint calculation according to the scheduling control cycle of 10 minutes; the fast safety control process monitors the EO reaction temperature according to a 10-second fast control cycle and performs limit correction on the heat extraction control content. The internal calculations of thermal power, heat extraction power, heat release power, and compression drive power of the controller are uniformly stored and calculated in kW.

[0026] like Figure 1As shown, the waste heat from the EO reaction sequentially forms high-temperature waste heat, medium-temperature waste heat, and low-temperature waste heat along the heat exchange path. The high-temperature waste heat corresponds to the first phase change heat storage unit, the medium-temperature waste heat corresponds to the second phase change heat storage unit, and the low-temperature waste heat corresponds to the third phase change heat storage unit. The first phase change heat storage unit uses a medium-high temperature composite salt phase change material with a melting point of 250℃ or a low-melting-point metal composite phase change material, with a heat storage capacity of 15MWh; the second phase change heat storage unit uses a nitrate composite phase change material with a melting point of 200℃, a latent heat of 210kJ / kg, and a heat storage capacity of 20MWh; the third phase change heat storage unit uses an aluminum stearate composite salt or a pentaerythritol-stearic acid eutectic phase change material with a melting point of 155℃, a latent heat of 340kJ / kg, and a heat storage capacity of 12MWh. The three heat extraction sections are connected to the heat medium circulation pipeline through valve groups or branch lines with adjustable heat medium flow rates, so that the mass flow rate of the heat medium in each heat extraction section can be adjusted independently.

[0027] The first phase change thermal storage unit is designed with a heat transfer medium temperature range of 220℃ to 280℃ for steam generation and maintaining the target temperature at the first-stage inlet of the CO2 turbine. The second phase change thermal storage unit operates in a temperature range of 180℃ to 220℃ for interstage reheating of the CO2 turbine. The third phase change thermal storage unit operates in a temperature range of 150℃ to 180℃ for adjusting the subcooling temperature at the pump inlet and for heat preservation of the high-pressure CO2 storage tank. The designed heat transfer medium temperature range of the first phase change thermal storage unit represents the allowable working envelope of the material and heat exchanger. Actual heat charging and discharging are limited by the real-time heat transfer medium temperature, the heat exchange terminal difference, and the EO reaction temperature boundary. When the current available heat supply temperature of the first phase change thermal storage unit is insufficient to meet the heat exchange terminal difference for steam generation, the steam generation branch stops operating, and the first phase change thermal storage unit only undertakes supplementary heating at the first-stage inlet of the CO2 turbine or heat loss compensation along the path to meet the terminal difference conditions.

[0028] like Figure 2 As shown, the controller acquires the operating status of the EO reaction waste heat supplying energy to the CO2 energy storage process, and also acquires the heat storage status of each phase change thermal storage unit. The heat storage status of the phase change thermal storage unit is represented by the state of charge (SOC), which is determined by the ratio of the stored heat capacity to the rated heat storage capacity of the phase change thermal storage unit. The SOC control range for the first, second, and third phase change thermal storage units is 10% to 95%.

[0029] In S1, the controller executes the heat extraction screening process. In this embodiment, the EO reactor is a multi-tube fixed-bed reactor. The catalyst bed and equivalent solid heat capacity mass involved in the short-cycle thermal inertia calculation are taken as 50t, the equivalent isobaric specific heat is taken as 0.9kJ / (kg·K), and the equivalent heat capacity is denoted as... The value is taken as 45 MJ / K, but 45000 kJ / K is used in the calculation. The thermal inertia time constant of the EO reactor is 20 min, and the controller uses a calculation step size of 60 s to predict the reaction temperature trajectory in the next 30 min. A 10 min scheduling control cycle is used to match the thermal inertia of the reactor and the thermal response of the phase change regenerator, and a 10 s fast control cycle is used to handle the limit correction when the reaction temperature approaches the safety boundary within the scheduling control cycle.

[0030] The predicted EO reaction load is obtained from the production plan, raw material feed rate, and historical operating data in the plant's DCS system. This embodiment uses the normalized EO reaction load. The value ranges from 0 to 1, corresponding to the rated load. If the DCS system outputs a percentage load, then divide the percentage load by 100 as the final value. If the DCS system outputs the raw material feed mass flow rate, then the ratio of the current mass flow rate to the rated mass flow rate will be used as the input mass flow rate. Rated reaction exothermic power of the EO unit Take 32500kW, the first The reaction exotherm of the predicted step Calculate using the following formula:

[0031] ;

[0032] Lumped heat balance relationship of EO reactor for:

[0033] ;

[0034] in, The EO reaction temperature, The exothermic power of the EO reaction. This refers to the heat dissipation of the original process in the EO reactor. This is for the heat extracted into the phase change heat storage branch. The phase change heat storage branch and the original process heat dissipation path are configured with parallel heat exchange paths or independent heat exchangers, and the adjustment... The heat transfer is completed through the heat transfer medium flow rate of the phase change heat storage branch, without directly changing the flow rate of the circulating medium in the original process heat dissipation path.

[0035] When the original process heat dissipation path uses a single-phase cooling medium, the original process heat dissipation is calculated based on the mass flow rate of the cooling medium, the specific heat of the cooling medium at constant pressure, and the temperature difference between the inlet and outlet. When the original process heat dissipation path uses steam generation heat exchange, the original process heat dissipation is determined by the sensible heat of feedwater heating, the latent heat of vaporization, and the sensible heat of steam superheating; when steam does not superheat, the superheat sensible heat term is zero. The steam generation path satisfies the mass conservation law; under steady-state operation, the feedwater flow rate entering the system is equal to the sum of the steam flow rate formed by evaporation and the saturated liquid flow rate discharged; under the condition of total evaporation and no blowdown, the feedwater flow rate is equal to the steam flow rate.

[0036] The controller takes heat at the current time. A candidate heat extraction set is generated based on the baseline and combined with the predicted EO reaction load. The current heat extraction is higher than the activation threshold. At that time, the candidate calorific value is calculated within the range of -50% to +50% of the current calorific value. Step size generation, i.e., according to generate, Take values ​​of -50%, -49%, ..., 0%, ..., 49%, 50%. The current heat input does not exceed the activation threshold. At this time, the controller enters the heat recovery generation process, and the candidate heat of extraction is generated in 1% steps within the range of 35% to 45% of the heat of release of the EO reaction in the current predicted step. generate, Take 35%, 36%, ..., 45%; among which, The current prediction step is to determine the heat release of the EO reaction. The rated exothermic power of the EO unit is taken as 1%. The heat recovery and generation process is still screened based on the reaction temperature boundary, the heat recovery ratio boundary, and the heat recovery rate boundary, and the heat recovery rate is not based on the current heat recovery. As a denominator, it avoids computational deadlock in the zero-heat state.

[0037] For each candidate heat extraction, the controller uses forward Euler recursion to calculate the predicted reaction temperature trajectory:

[0038] ;

[0039] in, Take 60 seconds. Substituting 45000 kJ / K, kW is used in the heat balance recursion based on kJ / s. The recursive calculation for the next 30 minutes, if there is no updated original heat dissipation schedule, will... Step Take the current measured value If the DCS system provides an existing cooling medium flow plan, then the values ​​will be assigned according to the plan. The candidate heat extraction value will remain the current candidate value within a prediction window. Take the corresponding candidate and collect the heat.

[0040] The heat extraction boundaries include the reaction temperature boundary, the heat extraction ratio boundary, and the heat extraction rate of change boundary. The reaction temperature boundary is set between 220℃ and 255℃. The heat extraction ratio is defined as the ratio of the candidate heat extraction amount entering the phase change thermal storage branch to the heat release amount of the current predicted step EO reaction; the heat extraction ratio boundary is set between 35% and 45%. The heat extraction rate of change is defined as the average rate of change of the candidate heat extraction amount within the scheduling and control cycle. The current heat extraction amount is higher than the start-up threshold. At that time, the rate of change of heat extraction is based on the current actual heat extraction. The calculation is based on the current actual heat extraction. The candidate heat extraction is generated in the range of -50% to +50% of the current actual heat extraction, with a maximum change rate of 50% / 10min, or 5% / min. The range of candidate values ​​generated is consistent with the boundary of the heat extraction change rate.

[0041] The current heat extraction is not higher than the start-up threshold. At that time, the rate of change of heat is based on the rated reaction exothermic power of the EO device. As a calculation benchmark, the absolute increase in heat extraction within each scheduling control cycle is limited to no more than [a certain percentage]. Limit the average rate of change to Within this system, the actual heat extraction during the current scheduling and control cycle is limited to ensure a smooth start-up of the heat extraction recovery process from zero heat extraction. The reaction temperature boundary of 220℃ to 255℃ is determined by the activity, selectivity, and thermal safety requirements of the EO reaction catalyst. A heat extraction ratio of 35% to 45% is used to maintain the basic heat dissipation flow rate of the original process heat dissipation path, and a heat extraction change rate of 5% / min is used to match the 20-minute thermal inertia time constant of the fixed-bed reactor to reduce thermal shock.

[0042] If the predicted 30-minute reaction temperature trajectories corresponding to the candidate heat recovery are all between 220℃ and 255℃, the candidate heat recovery is within the heat recovery ratio boundary, and the rate of change of the candidate heat recovery does not exceed the rate of change boundary, then the candidate heat recovery meets the validity condition and is included in the allowable heat recovery range. For the heat recovery and generation process, after the candidate heat recovery meets the temperature trajectory condition and the heat recovery ratio condition, it is included in the recovery allowable set, and the controller then proceeds according to the following... The heat extraction rate of change boundary, which serves as the benchmark, forms the allowable heat extraction range that can be executed in the current scheduling and control cycle.

[0043] When no candidate heat recovery meets the validity criteria, the controller maintains the reaction temperature boundary at 220℃ to 255℃ and enters the retreat screening process. During the retreat screening process, the controller adjusts the heat recovery ratio boundary to 30% to 50%, the heat recovery change rate boundary to 8% / min, and regenerates the retreat candidate heat recovery set. The current heat recovery is higher than the start-up threshold. When the current heat extraction is within the range of -80% to +80% of the current heat extraction, the candidate heat extraction is generated in 1% increments; the current heat extraction is not higher than the activation threshold. At that time, the retreating candidate heat extraction is generated in 1% increments within the range of 30% to 50% of the current predicted step EO reaction heat release, and the absolute increase in heat extraction within each scheduling control cycle is limited to no more than The average rate of change of the retreat and recovery process is limited to Internally, the retreat boundary absorbs short-period disturbances using an equivalent heat capacity of 45 MJ / K, while maintaining the absolute safety boundary of the reaction temperature.

[0044] If the allowable heat extraction range cannot be formed after the retreat screening, the allowable heat extraction range is set to the zero heat extraction range. Zero heat extraction means that the heat entering the phase change heat storage branch is zero, but it does not mean that the EO reactor stops dissipating heat. At this time, the controller closes or limits the heat medium regulating valve of the phase change heat storage branch, and the original process heat dissipation path continues to bear the heat discharge of EO reaction; step S2 determines the total heat extraction to be zero based on the zero heat extraction range, and step S3 forms a heat compensation amount based on the current heat release of each phase change heat storage unit, and corrects the heat release of phase change heat storage with the heat compensation amount, so that the CO2 energy storage process can prioritize the use of the stored heat under the condition that it does not continue to extract heat from the EO reactor. If the heat dissipation of the original process is lower than the reaction heat safety requirement, the rapid safety control process prioritizes restricting the heat extraction control content of the CO2 energy storage side, and outputs an interlock signal to the DCS system to improve the heat exchange capacity of the original heat dissipation path.

[0045] In S2, the controller determines the total heat extraction within the allowable heat extraction range. When the allowable heat extraction range is the zero heat extraction range, the total heat extraction is 0. When the allowable heat extraction range is not the zero heat extraction range, the allowable heat extraction range is denoted as... The midpoint of the allowable heat extraction range is denoted as ,and The controller is determined according to the calculation method of the current heat demand gap of the CO2 energy storage process. and the ratio of heat demand gap Limited to between 0 and 1:

[0046] ;

[0047] in, The rated heat demand for CO2 energy storage processes.

[0048] The controller is based on the measured reaction temperature. Calculate the temperature penalty ratio:

[0049] ;

[0050] when When the temperature penalty ratio is 0; when At that time, the temperature penalty ratio increases as the measured reaction temperature decreases; when At that time, the temperature penalty ratio is locked at 1.

[0051] The candidate value for total heat extraction is determined by the following formula:

[0052] ;

[0053] The above calculations use the allowable heat extraction range as the boundary, and calculate the proportion of the heat demand gap. Temperature penalty ratio Two dimensionless input quantities serve as candidate values ​​for adjusting the total calorific value; among them... The total heat extraction candidate value increases as the current heat demand gap in CO2 energy storage processes widens, causing the total heat extraction candidate value to shift from the midpoint of the allowable heat extraction range. To the upper limit of the allowable heat extraction range Offset; Depending on the measured reaction temperature As it approaches the lower limit safety boundary, the value increases, causing the candidate value of total heat extraction to move from the current offset position towards the lower limit of the allowable heat extraction range. The decline. Through the above methods, the candidate value for total calorific value is... , and The changes occur continuously between these points.

[0054] Therefore, when hour, The current heat demand gap in CO2 energy storage processes no longer causes the total heat extraction to shift towards the upper limit of the allowable heat extraction range; when and hour, ;when and hour, .

[0055] The controller will Projecting the data onto the allowable heat extraction range yields the total heat extraction. :

[0056] ;

[0057] When the measured reaction temperature If the rapid safety control process has already triggered the lower limit protection, the total heat extraction will be prioritized according to the lower limit of the allowable heat extraction range. Selection: If the allowable heat extraction range is the zero heat extraction range, then the total heat extraction is set to 0. This priority rule takes precedence over the upward adjustment corresponding to the current heat demand gap in CO2 energy storage processes.

[0058] Therefore, when the current heat demand gap in the CO2 energy storage process increases, the total heat extraction shifts proportionally towards the upper limit of the allowable heat extraction range; when the measured reaction temperature is close to or below the lower limit safety boundary, the total heat extraction shifts proportionally towards the lower limit of the allowable heat extraction range. Compared to Reserved Temperature buffering allows the controller to smoothly reduce heat extraction when the reaction temperature approaches the lower limit, reducing the risk of exceeding the limit due to thermal inertia and preventing downstream heat demand from offsetting the thermal safety constraints of the EO reaction.

[0059] The current heat demand gap in the CO2 energy storage process is determined by subtracting the sum of the actual current heat supply power of each phase change thermal storage unit from the sum of the heat power required for turbine stage inlet reheat, interstage reheat, pump inlet temperature adjustment, and high-pressure CO2 tank insulation. The maximum heat release capacity of each phase change thermal storage unit is limited by both the heat exchange capacity on the heat release side and the heat release capacity of the state of charge (SOC). The heat exchange capacity on the heat release side is determined based on the mass flow rate of the heat medium in the heat release branch, the specific heat of the heat medium at constant pressure, and the temperature difference between the heating side and the heating side. The heat release capacity of the SOC is determined based on the amount of stored heat that can be released between the current SOC and the 10% lower limit SOC, as well as the scheduling and control cycle.

[0060] Once the total heat output is determined, the controller decomposes it into upstream heat output, midstream heat output, and downstream heat output according to the temperature sequence of the EO reaction waste heat in the heat exchange path. The upstream heat output is allocated to the first phase change heat storage unit, the midstream heat output to the second phase change heat storage unit, and the downstream heat output to the third phase change heat storage unit.

[0061] No. The real-time extractable heat power of each heat extraction section is determined based on the mass flow rate of the heat medium in the heat extraction section, the specific heat of the heat medium at constant pressure, and the temperature difference between the inlet temperature of the heat medium on the charging side of the phase change heat storage unit and the minimum allowable temperature of the heat medium returning to the EO reactor side. Among these factors, Choose 1, 2, or 3, corresponding to the upstream, midstream, and downstream heat extraction sections, respectively. The mass flow rate of the heat medium is collected in real time by mass flow meters on the heat medium pipelines of each heat extraction section, and controlled by the corresponding strain gauge pump speed or regulating valve opening. The unit of the heat medium's constant pressure specific heat is kJ / (kg·K), the unit of the heat medium's mass flow rate is kg / s, and the calculation results are entered into the controller in kW.

[0062] The minimum heat transfer medium temperature allowed to return to the EO reactor is determined jointly based on the lower limit of the operating temperature zone of the phase change heat storage unit, the heat transfer medium crystallization temperature, and the process verification temperature of the corresponding heat extraction section to avoid local overcooling and reduced catalyst activity. The highest value among these three is taken as the minimum heat transfer medium temperature returning to the EO reactor. The reflux control benchmark for the upstream heat extraction section of the first phase change heat storage unit is 220℃, the reflux control benchmark for the midstream heat extraction section of the second phase change heat storage unit is 180℃, and the reflux control benchmark for the downstream heat extraction section of the third phase change heat storage unit is 150℃. When the heat transfer medium crystallization temperature or process verification temperature is higher than the corresponding reflux control benchmark, the minimum heat transfer medium temperature is determined according to the higher temperature.

[0063] No. The heat storage capacity of each phase change thermal storage unit is determined based on the amount of heat that can be stored between the current state of charge (SOC) and 95% of the upper limit SOC, as well as the scheduling control cycle. When the rated thermal storage capacity is expressed in MWh, the controller first converts MWh to kWh, and then converts it to kW according to the scheduling control cycle. The upper limit for the allocation of each heat extraction segment is the lower of the real-time available heat output and the heat storage capacity of the corresponding phase change thermal storage unit. When the sum of the upper limits of the allocation for the upstream heat extraction segment corresponding to the first phase change thermal storage unit, the midstream heat extraction segment corresponding to the second phase change thermal storage unit, and the downstream heat extraction segment corresponding to the third phase change thermal storage unit is greater than zero, and the total heat extraction is not greater than the sum of the three upper limits, the total heat extraction of each heat extraction segment is allocated according to its respective upper limit. When the total heat extraction is greater than the sum of the three upper limits, the actual total allocation limit is the sum of the three upper limits, and the heat extraction of each heat extraction segment is taken from its corresponding upper limit. When the sum of the three upper limits is equal to zero, the heat extraction of each heat extraction segment is set to zero, thus forming the heat extraction allocation result.

[0064] In S3, the controller receives the green electricity signal and matches the green electricity signal, the thermal storage status of the phase change thermal storage unit, and the energy demand of the CO2 energy storage process. The energy demand of the CO2 energy storage process includes compression drive demand and heat demand. The controller determines the energy demand level based on the energy demand of the CO2 energy storage process. The energy demand level serves as a quantitative parameter for determining the total compression power, the priority of phase change thermal storage heat release, and the response intensity of steam turbine auxiliary drive power. The energy demand level ranges from 1 to 5, and is determined by the controller based on the deviation rate between the current stored energy and the target stored energy, as well as the ratio of the planned charging time to the rated charging time. The current stored energy represents the equivalent stored energy of the CO2 energy storage process, and is determined by weighting the current actual stored heat of the first, second, and third phase change thermal storage units according to the available energy coefficient based on temperature potential; the target stored energy is given by the dispatch command or the energy management system.

[0065] Equivalent energy storage is denoted as Determine using the following formula:

[0066] ;

[0067] in, For the first The current actual heat storage capacity of each phase change thermal storage unit For the first The effective heat release temperature corresponding to each phase change thermal storage unit The ambient thermodynamic temperature is 25℃, which corresponds to 298.15K. The effective heat release temperatures of the first, second, and third phase change thermal storage units can be taken as the corresponding phase change temperatures or as the outlet temperatures of the corresponding heat release branch. Using this method, the contribution of high-temperature thermal storage to the equivalent energy storage is higher than that of low-temperature thermal storage, and the energy demand level reflects both the quantity of thermal storage and the quality of heat supplied.

[0068] The energy demand level is first determined by the deviation rate between the current energy storage capacity and the target energy storage capacity: Level 1 is a deviation rate of no more than 10%; Level 2 is a deviation rate of more than 10% but no more than 30%; Level 3 is a deviation rate of more than 30% but no more than 60%; Level 4 is a deviation rate of more than 60% but no more than 80%; and Level 5 is a deviation rate of more than 80%. Subsequently, the basic level is adjusted according to the ratio of the planned charging time to the rated charging time: if the ratio is below 0.8, it is upgraded by one level; if the ratio is above 1.2, it is downgraded by one level; and if the ratio is between 0.8 and 1.2, it remains unchanged. The adjusted level is limited to between 1 and 5.

[0069] The controller determines the power correction factor based on the energy demand level. Levels 1, 2, 3, 4, and 5 correspond to 0.6, 0.8, 1.0, 1.1, and 1.2 respectively. The planned compression power is denoted as... The upper limit of compression power, which is jointly constrained by the equipment's rated power, CO2 pressure boundary, and compression power variation, is denoted as... The total compression power is determined by the following formula:

[0070] ;

[0071] in, The lowest value among the following three is taken: the rated power of the liquid pressurization pump, the allowable compression power when the high-pressure side pressure does not exceed 12.5 MPa, and the power achievable by the current compression power according to the rate of change limit. Therefore, when the energy demand level is 1 or 2, the total compression power is lower than the planned compression power; when the energy demand level is 3, the total compression power is selected according to the planned compression power; when the energy demand level is 4 or 5, the total compression power is selected towards the higher power side within the limits of the equipment's rated power, CO2 pressure boundary, and compression power change limit.

[0072] like Figure 1As shown, the CO2 low-pressure storage tank outlet conditions are 6 MPa and 10°C liquid CO2. The third phase change heat storage unit supplies heat to the pump inlet heat exchanger through an intermediate heat medium loop. The controller limits the temperature of the heat medium entering the pump inlet heat exchanger to 40°C to 50°C through a bypass mixing valve or a three-way temperature regulating valve, with constraints that the pump inlet heat exchanger wall temperature is lower than the CO2 saturation temperature at 6 MPa and the pump inlet CO2 outlet temperature is not higher than 18°C. The pump inlet heat exchanger adjusts the liquid CO2 to 15°C to 18°C, maintaining a 4°C to 7°C subcooling of the liquid CO2 at 6 MPa, thus preventing cavitation at the liquid pressurization pump inlet due to local pressure drop. After the liquid pressurization pump pressurizes CO2 to 12 MPa, the CO2 at the pump outlet is heated to 105°C via the charging and heating heat exchange branch and then input into the high-pressure CO2 storage tank. The charging and heating heat exchange branch is preferentially heated by the second phase change heat storage unit. When the heat release capacity of the second phase change heat storage unit is insufficient and the first phase change heat storage unit has heat release capacity, the first phase change heat storage unit will supplement the heating. The high-pressure CO2 storage tank operates at a static temperature of 55°C to 65°C and at 12 MPa and 105°C during charging and discharging.

[0073] The CO2 energy storage process employs a two-stage axial-flow CO2 turbine with a reheat heat exchanger between stages. Before entering the first-stage turbine, the CO2 output from the high-pressure CO2 storage tank is tested at 12 MPa and 105°C as the target inlet temperature. When the outlet temperature of the high-pressure CO2 storage tank meets this target condition, the first-stage inlet heat exchange branch corresponding to the first phase change heat storage unit compensates for heat loss from the pipeline and temperature drop caused by valve throttling. When the outlet temperature of the high-pressure CO2 storage tank is lower than the target condition, the first-stage inlet heat exchange branch corresponding to the first phase change heat storage unit provides supplementary heating to the CO2. The first-stage turbine outlet condition is 8 MPa and 75°C. The CO2 from the first-stage turbine outlet is heated to 120°C by the reheat heat exchanger corresponding to the second phase change heat storage unit before entering the second-stage turbine. The second-stage turbine outlet condition is 6 MPa and 55°C, consisting of gaseous or dense-phase CO2. The CO2 from the secondary turbine outlet is liquefied to 10°C by the chilled water heat exchanger provided by the refrigeration unit before re-entering the low-pressure CO2 storage tank, completing the closed-loop circulation of the working fluid. The operating temperature range of the second phase change heat storage unit is higher than the reheat target temperature on the CO2 side, which is used to ensure that the interstage reheat heat exchanger has a stable heat transfer temperature difference and to reserve a safety margin for the inlet material temperature of the secondary turbine and subsequent cooling load.

[0074] The heat released by the first phase change thermal storage unit corresponds to steam generation and turbine primary inlet heating. The steam generation branch generates 2.5 MPa, 225℃ steam and drives the steam turbine auxiliary liquid pressurization pump. When the current available heating temperature of the first phase change thermal storage unit cannot meet the heat exchange differential of the steam generation stage, the steam generation branch stops operating, while the CO2 primary inlet heating branch continues to perform supplementary heating or temperature maintenance based on the available temperature difference. The heat released by the second phase change thermal storage unit corresponds to interstage reheating of the turbine and is preferentially used in the charging and storage heating heat exchange branch for raising the CO2 temperature at the pump outlet to the high-pressure CO2 storage tank during charging and discharging operations. The heat released by the third phase change thermal storage unit corresponds to pump inlet temperature adjustment and high-pressure CO2 storage tank insulation.

[0075] The compression drive power includes the electric drive compression power and the steam turbine auxiliary drive power. The controller determines the planned compression power based on the target CO2 transfer mass, the planned storage time, and the pressure rise of the liquid pressurization pump, and adjusts the planned compression power according to the energy demand level to obtain the total compression power. The target CO2 transfer mass is determined by the CO2 mass difference between the target high-pressure storage tank state and the current high-pressure storage tank state; the CO2 mass is determined by the effective volume of the high-pressure storage tank and the CO2 density at the corresponding pressure and temperature. The liquid pressurization pump power is calculated based on the CO2 mass flow rate, the specific volume of liquid CO2 at the pump inlet, the pressure difference before and after the pump, and the pump efficiency. The pressure is expressed in Pa when substituting into the calculation, and the power output is uniformly expressed in kW. The specific volume of liquid CO2 at the pump inlet is obtained by bilinear interpolation through the CO2 property offline lookup table, based on the values ​​collected by the liquid pressurization pump inlet pressure sensor and temperature sensor. In this embodiment, the rated power of a single electric drive liquid pressurization pump is taken as 45kW. In industrial-scale systems, multiple liquid pressurization pumps can be configured in parallel.

[0076] When the green electricity signal indicates that green electricity is available, the controller will configure the total compression power determined according to the energy demand level as the electric drive compression power, and the steam turbine auxiliary drive power will be set to zero or kept in standby mode. The first phase change thermal storage unit will preferentially enter the heat storage or heat supply maintenance state. When the green electricity signal indicates that green electricity is unavailable and the first phase change thermal storage unit has heat that can be released, the controller will set the steam turbine auxiliary drive power according to the heat that can be released by the first phase change thermal storage unit and the energy demand level. The available steam auxiliary power of the first phase change thermal storage unit is calculated from the heat release power of the first phase change thermal storage unit, the steam generation heat exchange efficiency, and the steam turbine efficiency. The higher the energy demand level, the higher the proportion of the available steam auxiliary power is used, but the steam turbine auxiliary drive power does not exceed the total compression power. The controller subtracts the total compression power from the steam turbine auxiliary drive power, and uses the remaining power after subtraction as the electric drive compression power, thereby forming an energy matching relationship between the compression drive power and the heat release of the phase change thermal storage.

[0077] During the state switching process of the phase change thermal storage unit, the scheduling control cycle is responsible for generating the main switching commands for the charging and releasing states; the fast safety control cycle only limits, maintains, or cuts off the generated commands. In step S2, the controller determines the charging state based on the heat extraction and distribution results and the thermal storage state of the phase change thermal storage unit, and uses the existence of available thermal storage capacity of the corresponding phase change thermal storage unit as the switching condition for the charging state. In step S3, the controller determines the releasing state based on the energy demand of the CO2 energy storage process and the thermal storage state of the phase change thermal storage unit, and uses the existence of available heat release capacity of the corresponding phase change thermal storage unit as the switching condition for the releasing state. When the charging state switching condition or the releasing state switching condition is not met, the controller maintains the original operating state of the corresponding phase change thermal storage unit. The same phase change thermal storage unit is not simultaneously in the charging and releasing states within the same 10-second fast control cycle, and the state switching interval is not less than 1 minute. When the same phase change thermal storage unit simultaneously meets the conditions for switching between charging and releasing states within a scheduling and control cycle, if it is in a 1-minute switching lockout period, it maintains the original operating state; if the thermal safety of the EO reaction requires the corresponding phase change thermal storage unit to receive heat, it prioritizes maintaining the charging state; in other cases, the controller determines whether to switch to the releasing state based on the CO2 energy demand and the heat release capacity of adjacent units.

[0078] When a phase change thermal energy storage unit releases heat to the CO2 energy storage process, if the heat release capacity of the corresponding phase change thermal energy storage unit is lower than the heat demand in the CO2 energy storage process, and an adjacent high-temperature phase change thermal energy storage unit has heat release capacity, the controller will activate cross-stage heating. Cross-stage heating is limited to the direction from the first phase change thermal energy storage unit to the second phase change thermal energy storage unit, and from the second phase change thermal energy storage unit to the third phase change thermal energy storage unit. Activation conditions include a state of charge (SOC) of more than 80% for the previous phase change thermal energy storage unit, an SOC of less than 30% for the next phase change thermal energy storage unit, and a temperature difference of at least 20°C between the two phase change thermal energy storage units.

[0079] For each permitted cross-level heating path, the controller pre-calculates the grade loss based on the effective heating temperature on the supply side and the target heating temperature on the receiving side. The grade loss corresponding to cross-level heating is calculated using the following formula:

[0080] ;

[0081] in, This refers to cross-level heating, measured in kW. The effective heating temperature on the heating side. The target heating temperature is the temperature supplied to the heated side. During calculation, and All values ​​are calculated based on thermodynamic temperature (K), with the Celsius temperature value increased by 273.15 before being used in the calculation. The effective heating temperature on the heating side can be taken as the phase change temperature on the heating side, or it can be corrected based on the outlet temperature of the heat transfer medium in the heat release branch; the target heating temperature on the receiving side can be taken as the phase change temperature on the receiving side, or it can be corrected based on the actual heat exchange target of the receiving branch.

[0082] Grade loss ratio is defined as grade loss The ratio of the available energy released by the phase change thermal storage unit on the heating side to the available energy released on the heating side, according to... Confirmed. The controller uses the grade loss ratio as an evaluation parameter for the heat release distribution between cross-stage heating and phase change heat storage. For cross-stage heating paths calculated using a fixed phase change temperature, the grade loss ratio is used as a preset evaluation parameter for that path; for cross-stage heating paths using real-time heat release branch temperature correction, the grade loss ratio is updated with the effective heating temperature and the target heating temperature. When the grade loss ratio of a certain cross-stage heating path exceeds 15%, the controller lowers the available heating limit of that cross-stage heating path and corrects the cross-stage heating based on the lowered available heating limit, incorporating the corrected cross-stage heating into the phase change heat storage heat release.

[0083] In S4, the controller determines the physical property response at the operating point of the CO2 energy storage process under temperature and pressure disturbance calculation conditions. The CO2 critical point is 31.1℃ and 7.38MPa. The temperature and pressure disturbance calculation conditions include the pressure disturbance. and temperature disturbance ,in Take 0.1 MPa, Use 1℃. The temperature difference of 1℃ is the same as the value of 1K. The temperature entered into the property database is converted to thermodynamic temperature according to the database requirements.

[0084] CO2 density CO2 specific heat and CO2 viscosity Calculate the relative changes separately. For any physical property... relative change Calculate using the following formula:

[0085] ;

[0086] in, express , or ; This represents the corresponding physical property value for the current running point; The partial derivative of physical properties with respect to pressure under isothermal conditions; This represents the partial derivative of the physical properties with respect to temperature under constant pressure conditions.

[0087] The partial derivatives of local physical properties are calculated using the central difference method:

[0088] ;

[0089] ;

[0090] in, For the current operating point pressure, This is the current operating point temperature. CO2 property values ​​can be obtained using... Equations of state The calculation is performed using the equation of state or an experimentally verified CO2 property table. The pressure-temperature-property offline lookup table can be pre-entered into the engineering controller. During real-time operation, the property values ​​at the current operating point and disturbance point are obtained through bilinear interpolation, and then substituted into the central difference formula.

[0091] Comprehensive physical property response Synthesize using the following formula:

[0092] ;

[0093] in, , and These represent the relative changes in CO2 density, specific heat, and viscosity, respectively. Density fluctuations near the critical region have the greatest impact on the volumetric efficiency of liquid booster pumps, cavitation protection, and pressure stability of high-pressure storage tanks, and are assigned a weight of 0.5. Specific heat fluctuations directly affect the heat exchanger terminal temperature difference and heat load matching, and are assigned a weight of 0.3. Viscosity fluctuations mainly affect pipeline flow resistance and local pressure drop in valve assemblies, and are assigned a weight of 0.2. These three factors are normalized to form the comprehensive physical property response.

[0094] when When the CO2 energy storage process is in the linear stable region, the controller maintains the original CO2 energy storage operating parameters; when At that time, the CO2 energy storage process is in the weak nonlinear disturbance region, and the controller increases the sampling frequency while maintaining the scheduling control cycle unchanged; when At that time, the CO2 energy storage process is in a strongly nonlinear transition region, and the controller performs in-model trial calculations and corrections according to the priority order of pump inlet temperature, turbine inlet temperature, and working fluid flow rate; when At that time, the CO2 energy storage process is in a highly sensitive region, and the controller executes a forced correction procedure until... Keep it below 0.3 to reduce the risk of pump cavitation, pressure over-limit, or heat exchange terminal instability.

[0095] The calculation of physical property response and the correction of CO2 energy storage operating parameters are performed by a fast physical property correction process, which has a calculation cycle of 10 seconds and runs synchronously with the fast safety control process. The scheduling control cycle is responsible for generating the basic operating point and power target, while the fast physical property correction process is responsible for rapidly correcting the pump inlet temperature, turbine inlet temperature, and working fluid flow rate within the scheduling control cycle. The correction direction is determined based on the position of the CO2 energy storage process operating point relative to the CO2 critical point. Pressure and temperature are used together to determine the relative position between the current operating point and the critical point and to recalculate the physical property response; pressure is not used as an independent active correction target.

[0096] For the inlet side of the liquid booster pump, the controller prioritizes reducing or limiting the pump inlet preheating temperature to keep the CO2 at the pump inlet subcooled. For the high-pressure side and turbine side, when the current operating point temperature is higher than 31.1℃, the initial temperature calculation direction is the heating direction; when the current operating point temperature is lower than 31.1℃, the initial temperature calculation direction is the cooling direction. The initial calculation direction of the working fluid flow rate is determined based on the current high-pressure side pressure change trend; if the current high-pressure side pressure is increasing, the initial calculation direction of the working fluid flow rate is the decreasing flow direction; if the current high-pressure side pressure is decreasing, the initial calculation direction of the working fluid flow rate is the increasing flow direction; if the current high-pressure side pressure change is within the preset pressure dead zone, the initial calculation direction of the working fluid flow rate is the decreasing flow direction, and a reverse calculation is performed if the physical property response has not decreased. The working fluid flow rate correction is completed by changing the output of the liquid booster pump frequency converter or the opening of the circulating flow regulating valve, and the pressure change is used as the state response after flow correction in the next physical property response calculation.

[0097] exist At that time, the pump inlet temperature correction step size is 2℃; if after correction Still not lower than 0.3, the turbine inlet temperature correction step is 3℃; if The value should remain no less than 0.3, and the correction for the working fluid flow rate should not exceed 5% of the current flow rate. At that time, the pump inlet temperature correction step is 5℃, the turbine inlet temperature correction step is 8℃, and the working fluid flow rate correction range does not exceed 10% of the current flow rate.

[0098] The rapid property correction process employs a single-variable sequential trial-and-error method within the model. Pump inlet temperature is the first priority variable, turbine inlet temperature is the second priority variable, and working fluid flow rate is the third priority variable. Each priority variable is first corrected by a step size within the controller according to the initial trial-and-error direction and then calculated. Then, within the controller, a step size is adjusted in the opposite direction and the calculation is performed. If there exists in either of the two directions that makes The reduced correction result is retained by the controller. A lower intra-model correction result is obtained, and based on this correction state, the variable moves to the next priority variable; if neither direction can achieve this... If the value is reduced, the controller restores the variable to its pre-correction state and moves on to the next priority variable.

[0099] After completing one round of in-model calculations, the controller only converts the selected target pump inlet temperature, target turbine inlet temperature, or target working fluid flow rate into actuator commands, without sending intermediate variables from the forward and reverse calculation processes to the temperature control valve, regulating valve, or frequency converter. After the actuator commands are issued, the controller sets a response hold window of no less than 30 seconds; in this embodiment, it is set to 45 seconds. Within the response hold window, the controller maintains the issued target opening degree or target frequency. The response hold window only restricts non-protective reverse corrections and does not stop the property response calculation within the 10-second rapid property correction cycle. The property response calculation results obtained within the hold window are used for continuity judgment, trend confirmation, and the next target update after the response hold window ends. When the pump inlet subcooling, high-pressure side pressure, or EO reaction temperature reaches the safety boundary, the rapid safety control process can cover the response hold window and output protection commands. Thus, the 10-second calculation cycle matches the response time of the staged heat exchanger group (less than or equal to 30 seconds) and the response delay of the pump inlet CO2 temperature (approximately 30 seconds), avoiding execution oscillations caused by high-frequency forward and reverse adjustments.

[0100] After completing one round of trial calculations according to priority within the same rapid property correction cycle, if If it is already below 0.3, output the corrected CO2 energy storage operating parameters; if If the value is still not lower than 0.3 but has not reached the safety boundaries of pressure, temperature, and supercooling, then the sequential iteration will continue in the next rapid property correction cycle; if If the pressure remains above 0.3 and any safety boundary is breached, the controller will limit the total compression power and working fluid flow rate within the current scheduling control cycle and output a protection operation command. The pump inlet temperature is regulated by the temperature control valve corresponding to the pump inlet heat exchanger of the third phase change heat storage unit, the turbine inlet temperature is corrected by the regulating valve corresponding to the first-stage inlet heat exchange branch of the first phase change heat storage unit, and the working fluid flow rate is corrected by the liquid booster pump frequency converter or the circulating flow regulating valve. No correction shall cause the pump inlet CO2 to lose subcooling, nor shall it cause the high-pressure side pressure to exceed 12.5 MPa, thus forming the corrected CO2 energy storage operating parameters.

[0101] In S4, the controller also establishes life-cycle carbon emission constraints based on the operating intensity of the pressurization and expansion equipment. The pressurization and expansion equipment includes liquid pressurization pumps, steam turbine auxiliary drive equipment, and CO2 turbines. The controller collects data on the output power, rated power, cumulative operating time, vibration spectrum characteristics, bearing temperature, seal leakage, and maintenance status of the pressurization and expansion equipment during the scheduling control cycle, and uses the ratio of output power to rated power as the normalized operating intensity. For the first... Each device, normalized operating intensity Determine by the following formula:

[0102] ;

[0103] in, For the first The average output power of each device during the scheduling and control cycle. For the first The rated power of each device. For liquid booster pumps. For electric drive compression power; for steam turbine auxiliary drive equipment, For steam turbines, auxiliary drive power; for CO2 turbines, This refers to the turbine's output power.

[0104] The controller calculates the fatigue accumulation factor based on normalized operating intensity, scheduling control cycle, and equipment design life. The device in the Fatigue accumulation factor after one scheduling control cycle Increment by the following formula:

[0105] ;

[0106] in, The scheduling and control cycle is set to 10 minutes. For the first Total design life of each device.

[0107] If abnormal frequency components appear in the equipment vibration spectrum, the bearing temperature exceeds the equipment health threshold, or the leakage of seals shows an upward trend, the controller will adjust the degradation correction coefficient output by the equipment degradation monitor. The normalized running intensity has been corrected; the corrected normalized running intensity is: , Not less than 1.

[0108] The corrected fatigue accumulation factor increases according to the following formula:

[0109] ;

[0110] The controller generates a hidden carbon penalty based on the fatigue accumulation factor, equipment design life, and the implicit carbon emissions during the equipment manufacturing, transportation, and installation phases. Hidden carbon penalty rate for each device Determine by the following formula:

[0111] ;

[0112] in, For the first The initial embodied total carbon emissions during the manufacturing, transportation, and installation phases of each piece of equipment. For the first Total operating time corresponding to the design life of each piece of equipment. For the first The fatigue accumulation factor used by each device in the current scheduling and control cycle for calculating the implicit carbon penalty rate, when the device has not triggered degradation correction. When the equipment triggers degradation correction, the incremental result of the fatigue accumulation factor after the current scheduling and control cycle is taken. Take the incremental result of the corrected fatigue accumulation factor after the current scheduling and control cycle, and satisfy the following conditions: .

[0113] The occult carbon penalty rate is determined based on the ratio of cumulative damage to remaining lifetime. In the calculation of the occult carbon penalty rate, For the first The remaining lifetime factor of each device in the current scheduling and control cycle. This is the risk amplification factor of the fatigue accumulation factor relative to the remaining life factor; This represents the average depreciation rate of the initial embodied total carbon emissions during the manufacturing, transportation, and installation phases over the design life. With Increase As the load decreases, the risk of major repairs or replacements increases for the same operating intensity, and the implicit carbon penalty rate increases accordingly. Increase.

[0114] Implicit carbon penalty during the current scheduling and control cycle Determine by the following formula:

[0115] ;

[0116] in, This indicates the number of devices involved in the calculation of carbon emission constraints throughout the entire life cycle. This applies to liquid pressurization pumps, steam turbine auxiliary drive equipment, or CO2 turbines. This calculation method offsets carbon emissions from the manufacturing, transportation, and installation phases resulting from future overhauls or replacements to the current operating control cycle, enabling the controller to account for equipment lifespan degradation in current power allocation.

[0117] The controller incorporates implicit carbon penalties into the evaluation objectives of CO2 process co-existing energy storage operation commands. Evaluation Objectives It can be expressed as follows:

[0118] ;

[0119] in, For the first Evaluation objectives for each scheduling control cycle. For the first Operational evaluation items for each scheduling and control cycle. For the first Implicit carbon penalty amount within each scheduling and control cycle. This serves as a reference for the implicit carbon emissions of equipment participating in the lifecycle carbon emission constraint calculation over its design life. The controller selects the candidate operating command with the lower evaluation target from among the candidate operating commands that satisfy the EO reaction temperature boundary, CO2 pressure boundary, pump inlet subcooling boundary, and phase change thermal storage unit SOC boundary as the CO2 process co-storage operating command. Thus, the lifecycle carbon emission constraint participates in the determination of the upper limit of electric drive compression power, steam turbine auxiliary drive power, and working fluid flow rate through an implicit carbon penalty term.

[0120] When the fatigue accumulation factor of any pressurization and expansion equipment When the first fatigue threshold of 0.7 is exceeded, the controller will lower the upper limit of the corresponding equipment's output power to 80% of the rated power and recalculate the upper limit of the compression drive power or the upper limit of the working fluid flow rate; the upper limit of the compression drive power includes the upper limit of the electric drive compression power and the upper limit of the steam turbine auxiliary drive power. The fatigue accumulation factor of any pressurization and expansion equipment... When the second fatigue threshold of 0.85 is exceeded, the controller outputs a shutdown maintenance command or a bypass protection command and switches the CO2 energy storage process to the protection operation state. If the EO reaction heat safety requirements necessitate continued heat extraction, the controller prioritizes maintaining the original process heat dissipation path and restricts heat extraction from the phase change heat storage branch, ensuring that the carbon emission constraints throughout the entire life cycle do not exceed the EO reaction heat safety limit.

[0121] Rapid safety control process monitoring and measured reaction temperature The difference between the measured reaction temperature and the reaction temperature boundary. When the measured reaction temperature approaches the lower limit of 220℃ or the upper limit of 255℃ for several consecutive rapid control cycles, and the difference is less than the safety margin, the rapid safety control process adjusts the heat extraction control based on the direction of deviation of the measured reaction temperature from the reaction temperature boundary. The safety margin is 2℃, and the number of consecutive rapid control cycles is no less than three 10s cycles.

[0122] When the measured reaction temperature approaches the lower limit of 220°C, the rapid safety control process reduces the heat extraction entering the phase change thermal storage branch. In this embodiment, every 10-second rapid control cycle, the opening of the heat transfer regulating valve in the phase change thermal storage branch is reduced by 5%, or the heat extraction setpoint is reduced in 500kW increments, until the measured reaction temperature rises above the safety margin. When the measured reaction temperature approaches the upper limit of 255°C, the rapid safety control process restricts the CO2 energy storage side from further increasing heat extraction demand and outputs an interlock signal to enhance heat dissipation to the original process heat dissipation path. The heat extraction control content after the limit correction replaces the heat extraction control content in the CO2 process co-existing energy storage operation command within the current rapid control cycle and is fed back to the next scheduling control cycle.

[0123] Within each scheduling and control cycle, the controller generates CO2 process co-existing energy storage operation instructions based on heat extraction allocation results, energy consumption matching relationships, corrected CO2 energy storage operation parameters, and full life-cycle carbon emission constraints. These instructions include the opening degree of the heat extraction valve group in the phase change heat storage branch, the flow rate of the heat medium in each temperature heat extraction section, the charging and releasing status of each phase change heat storage unit, the opening degree of the heat release valve in the steam generation branch, the electric drive compression power, the steam turbine auxiliary drive power, the opening degree of the temperature control valve in the pump inlet heat exchanger, the opening degree of the regulating valve in the turbine inlet heat exchange branch, the working fluid flow correction amount, and the upper limit of equipment power limited by the fatigue accumulation factor. The rapid safety control process has the authority to overwrite and modify the heat extraction control content within the scheduling and control cycle, ensuring that the thermal safety limits of the EO reaction continue to apply to the CO2 process co-storage operation commands; the rapid property correction process has the authority to rapidly correct the CO2 energy storage operation parameters within the scheduling and control cycle, ensuring that the near-critical property response continues to apply to the CO2 process co-storage operation commands; and the full life cycle carbon emission constraints correct the upper limits of equipment power and working fluid flow within the scheduling and control cycle, allowing equipment lifespan loss and implicit carbon emissions to participate in the generation of operation commands.

[0124] like Figure 3 As shown in (a), in a simulation implementation, after a step disturbance occurs in the EO reaction load, the controller filters candidate heat extraction capacity based on the 30-minute reaction temperature prediction trajectory, causing the allowable heat extraction range to shrink or expand with the thermal inertia of the EO reaction and the state of charge (SOC) of the phase change thermal storage unit. The SOC of the first, second, and third phase change thermal storage units is maintained within the operating range of 10% to 95%. When the allowable heat extraction range has been set to zero heat extraction capacity, the controller regenerates non-zero candidate heat extraction capacity through a heat extraction recovery generation process, and gradually restores heat extraction from the phase change thermal storage branch when the reaction temperature prediction trajectory meets the boundary conditions.

[0125] like Figure 3 As shown in (b), when the green electrical signal is available, the total compression power determined according to the energy demand level is configured as the electric drive compression power; when the green electrical signal is unavailable and the first phase change heat storage unit has heat release capacity, the controller determines the steam turbine auxiliary drive power based on the heat release capacity of the first phase change heat storage unit and the energy demand level. The steam turbine auxiliary drive power is reduced by the total compression power, and the remaining power after reduction is used as the electric drive compression power. (Physical property response) When the threshold is approached, the rapid property correction process generates corrected CO2 energy storage operating parameters according to the priority order of pump inlet temperature, turbine inlet temperature and working fluid flow rate.

[0126] like Figure 3As shown in (c), the fast safety control process monitors the difference between the measured reaction temperature and the reaction temperature boundary within a 10-second fast control cycle. When the difference is less than the safety margin for several consecutive fast control cycles, the fast safety control process performs a limit correction on the heat extraction control content and feeds the limit correction result back to the next scheduling control cycle, so that the EO reaction thermal safety limit continues to act on the CO2 process co-storage operation command.

[0127] In this embodiment, a closed-loop control chain is formed between the EO reaction waste heat, the phase change thermal storage process, and the CO2 energy storage process, encompassing heat extraction screening, cascaded thermal storage, energy consumption matching, near-critical property correction, and life-cycle carbon emission constraints. The controller allocates EO reaction waste heat at different temperature levels to the phase change thermal storage unit without exceeding the EO reaction temperature boundary, and generates CO2 process co-existing energy storage operation commands based on green electricity signals, the thermal storage status of the phase change thermal storage unit, the energy demand of the CO2 energy storage process, property responses, and the cumulative fatigue status of the equipment.

[0128] The above embodiments are only used to illustrate the technical methods of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical methods of the present invention without departing from the spirit and scope of the technical methods of the present invention.

Claims

1. A method for co-existing energy storage operation of CO2 process under the thermal inertia constraint of EO reaction, characterized in that, The waste heat from the EO reaction is configured to be supplied to the CO2 energy storage process via a phase change heat storage unit. The phase change heat storage unit extracts heat from the waste heat from the EO reaction through a phase change heat storage branch. The phase change heat storage branch and the original process heat dissipation path of the EO reactor are configured in parallel heat exchange path or with independent heat exchangers. The waste heat from the EO reaction is sequentially formed into high-temperature waste heat, medium-temperature waste heat and low-temperature waste heat along the heat exchange path. The phase change heat storage unit includes a first phase change heat storage unit corresponding to the high-temperature waste heat, a second phase change heat storage unit corresponding to the medium-temperature waste heat and a third phase change heat storage unit corresponding to the low-temperature waste heat. The CO2 energy storage process is executed by a CO2 energy storage system, which includes a low-pressure CO2 storage tank, a pump inlet heat exchanger, a liquid pressurizing pump, a charging and heating heat exchange branch, a high-pressure CO2 storage tank, a primary inlet heat exchange branch, a CO2 turbine, an interstage reheat heat exchanger, and a chilled water heat exchanger. The CO2 turbine includes a primary turbine and a secondary turbine. The outlet of the low-pressure CO2 storage tank is connected to the inlet of the liquid pressurizing pump via the pump inlet heat exchanger. The outlet of the liquid pressurizing pump is connected to the high-pressure CO2 storage tank via the charging and heating heat exchange branch. The outlet of the high-pressure CO2 storage tank is connected to the inlet of the primary turbine via the primary inlet heat exchange branch. The outlet of the primary turbine is connected to the inlet of the secondary turbine via the interstage reheat heat exchanger. The outlet of the secondary turbine is connected to the low-pressure CO2 storage tank via the chilled water heat exchanger, forming a closed-loop CO2 working fluid circulation. Steam generated by the steam generation branch drives a steam turbine, which in turn drives the liquid pressurizing pump. The first phase change heat storage unit supplies heat to the steam generation branch and the first-stage inlet heat exchange branch, respectively for steam generation and turbine first-stage inlet heating; the second phase change heat storage unit supplies heat to the interstage reheat heat exchanger and the charging and storage heating heat exchange branch, respectively for turbine interstage reheat and pump outlet CO2 heating; the third phase change heat storage unit supplies heat to the pump inlet heat exchanger and the high-pressure CO2 storage tank, respectively for pump inlet temperature adjustment and high-pressure CO2 storage tank insulation. The method includes: S1. Obtain the operating status of the EO reaction waste heat supplying energy to the CO2 energy storage process and the heat storage status of the phase change heat storage unit. Based on the current heat recovery, the predicted EO reaction load, the reaction heat inertia relationship and the heat recovery boundary, screen candidate heat recovery capacity to form an allowable heat recovery range. S2. Within the allowable heat extraction range, determine the total heat extraction capacity. Based on the temperature decrease relationship of the waste heat from the EO reaction along the heat exchange path, allocate the total heat extraction capacity to phase change heat storage units at different temperature levels to form a heat extraction distribution result. S3. Receive the green electricity signal, and determine the energy matching relationship between the compression drive power and the heat release of the phase change thermal storage unit, in combination with the thermal storage status of the phase change thermal storage unit and the energy demand of the CO2 energy storage process. S4. Calculate the physical property response based on the temperature and pressure disturbances at the operating point of the CO2 energy storage process, correct the CO2 energy storage operating parameters using the physical property response, and form a full life cycle carbon emission constraint based on the operating intensity of the pressurization and expansion equipment. The step of forming a full life cycle carbon emission constraint based on the operating intensity of the pressurization and expansion equipment includes: obtaining the normalized operating intensity of the liquid pressurization pump or the CO2 turbine within the scheduling and control cycle, where the normalized operating intensity is the ratio of the equipment output power to the equipment rated power; calculating the fatigue accumulation factor according to the normalized operating intensity, scheduling and control cycle, and equipment design life, and forming an implicit carbon penalty term according to the fatigue accumulation factor, equipment design life, and the implicit carbon emissions during the equipment manufacturing, transportation, and installation stages; incorporating the implicit carbon penalty term into the evaluation target of the CO2 process co-existing energy storage operation command, and lowering the upper limit of the compression drive power or the upper limit of the working fluid flow rate when the fatigue accumulation factor exceeds the fatigue threshold; and generating a CO2 process co-existing energy storage operation command subject to EO reaction heat safety restrictions by combining the heat extraction and distribution results, energy consumption matching relationship, corrected CO2 energy storage operating parameters, and full life cycle carbon emission constraints.

2. The CO2 process co-existing energy storage operation method under the thermal inertia constraint of EO reaction according to claim 1, characterized in that, In step S1, the heat extraction boundary includes the reaction temperature boundary, the heat extraction ratio boundary, and the heat extraction change rate boundary; screening candidate heat extraction amounts to form an allowable heat extraction range includes: calculating the reaction temperature prediction trajectory corresponding to each candidate heat extraction amount based on the lumped heat balance relationship of the EO reactor, and including candidate heat extraction amounts whose reaction temperature prediction trajectory is within the reaction temperature boundary, whose candidate heat extraction amounts are within the heat extraction ratio boundary, and whose candidate heat extraction change rate is within the heat extraction change rate boundary into the allowable heat extraction range.

3. The CO2 process co-existing energy storage operation method under the thermal inertia constraint of EO reaction according to claim 2, characterized in that, In step S1, if there are no candidate heats that can be included in the allowable heat extraction range, the reaction temperature boundary remains unchanged and the heat extraction ratio boundary and the heat extraction change rate boundary are adjusted. If the allowable heat extraction range is still not formed after adjustment, the allowable heat extraction range is set to the zero heat extraction range, so that step S2 determines the total heat extraction to zero, and step S3 corrects the phase change heat storage heat release based on the heat release capacity of the phase change heat storage unit.

4. The CO2 process co-existing energy storage operation method under the thermal inertia constraint of EO reaction according to claim 1, characterized in that, In step S2, the total heat output is decomposed into the heat output of the upstream heat output section, the heat output of the midstream heat output section, and the heat output of the downstream heat output section according to the temperature order of the waste heat from the EO reaction in the heat exchange path, and then respectively allocated to the first phase change heat storage unit, the second phase change heat storage unit, and the third phase change heat storage unit.

5. The CO2 process co-existing energy storage operation method under the thermal inertia constraint of EO reaction according to claim 4, characterized in that, In step S2, the upper limit of the allocation for each heat extraction section is determined based on the real-time heat extraction power of the heat extraction section and the heat storage power of the phase change heat storage unit. When the sum of the upper limits of each allocation is greater than zero, the total heat extraction is allocated according to the proportion of each upper limit. When the sum of the upper limits of each allocation is zero, the heat extraction of the upstream heat extraction section, the heat extraction of the midstream heat extraction section, and the heat extraction of the downstream heat extraction section are all set to zero.

6. The CO2 process co-existing energy storage operation method under the thermal inertia constraint of EO reaction according to claim 1, characterized in that, In step S3, when the phase change thermal storage unit releases heat to the CO2 energy storage process, if the heat release capacity of the corresponding phase change thermal storage unit is lower than the heat demand in the energy demand of the CO2 energy storage process, and the adjacent high-temperature phase change thermal storage unit has heat release capacity, then the cross-stage heat supply is determined according to the direction from the first phase change thermal storage unit to the second phase change thermal storage unit and from the second phase change thermal storage unit to the third phase change thermal storage unit, and the cross-stage heat supply is corrected according to the grade loss corresponding to the cross-stage heat supply.

7. The CO2 process co-existing energy storage operation method under the thermal inertia constraint of EO reaction according to claim 1, characterized in that, In step S3, the compression drive power includes electric drive compression power and steam turbine auxiliary drive power; wherein, the electric drive compression power is the power used to drive the liquid pressurization pump with electricity; the steam turbine auxiliary drive power is the power used by the steam turbine to assist in driving the liquid pressurization pump; the energy demand level is determined according to the energy demand of the CO2 energy storage process, and the total compression power is determined according to the energy demand level; when the green electricity signal indicates that green electricity is available, the total compression power is configured as the electric drive compression power; when the green electricity signal indicates that green electricity is unavailable and the first phase change thermal storage unit has heat that can be released, the steam turbine auxiliary drive power is used to reduce the total compression power, and the reduced power is used as the electric drive compression power.

8. The CO2 process co-existing energy storage operation method under the thermal inertia constraint of EO reaction according to claim 1, characterized in that, In step S4, pressure disturbance and temperature disturbance are introduced into the property calculation to calculate the relative changes in CO2 density, CO2 specific heat and CO2 viscosity, and synthesize the property response according to the corresponding weights. When the property response is not less than the property response threshold, the correction direction is determined according to the position of the CO2 energy storage process operating point relative to the CO2 critical point, and the CO2 energy storage operating parameters are corrected according to the priority order of liquid pressurization pump inlet temperature, CO2 turbine inlet temperature and working fluid flow rate.

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