A Cooperative Anti-Surge System and Method for Supercritical Carbon Dioxide Compressors Based on Working Fluid Inventory Adjustment and Import Status Constraints

Abstract

This invention discloses a collaborative anti-surge system and method for a supercritical carbon dioxide compressor based on working fluid inventory adjustment and inlet state constraints. The system includes: a supercritical carbon dioxide compressor compressing a closed-loop working fluid; a carbon dioxide working fluid inventory adjustment unit actively changing the operating state by adjusting the inventory through inlet gas replenishment or outlet temporary storage; a surge state measurement and feature extraction unit collecting operating parameters, surge signals, and adjustment unit status to extract features; an anti-surge reflux unit recirculating the outlet working fluid back to the inlet when the adjustment capacity is insufficient, the inlet does not meet the constraints, or in case of emergency anti-surge; and a controller connecting each unit, judging the surge risk and cause based on the information, calculating the adjustment capacity and inlet constraints, controlling the inventory adjustment unit to perform gas replenishment, temporary storage, or combined adjustment, or activating the anti-surge reflux unit when conditions are met. This invention achieves anti-surge control of a supercritical carbon dioxide compressor by collaboratively adjusting the carbon dioxide working fluid inventory and the anti-surge reflux.

Description

Technical Field

[0001] This invention relates to the field of supercritical carbon dioxide closed-cycle and compressor anti-surge control technology, and more specifically to a supercritical carbon dioxide compressor cooperative anti-surge system and method based on working fluid inventory adjustment and inlet state constraints. Background Technology

[0002] As a key component of supercritical carbon dioxide closed-loop systems, supercritical carbon dioxide compressors are highly susceptible to surge under conditions such as start-up / shutdown, variable load, low flow rate operation, downstream resistance changes, or fluctuations in the working fluid state. Existing anti-surge systems typically increase the working fluid flow by opening a regulating valve in the return pipeline connecting the compressor outlet and inlet to allow partial carbon dioxide recirculation from the outlet side. However, this control method has significant shortcomings: firstly, direct recirculation of high-temperature carbon dioxide from the outlet side not only leads to increased compressor inlet temperature but also causes energy loss within the closed-loop system; secondly, existing systems rely heavily on single controls based on flow rate, pressure, or pressure ratio, failing to fully utilize the working fluid inventory adjustment capability of the closed-loop system and making it difficult to address different surge causes such as insufficient inlet flow or increased outlet back pressure. Furthermore, the adjustment of working fluid inventory easily causes fluctuations in compressor inlet temperature and pressure. If the working fluid inventory recovers rapidly after the surge risk is eliminated, it can cause renewed fluctuations in the circulating pressure, pushing the compressor back towards the surge region.

[0003] Therefore, there is an urgent need to propose a collaborative anti-surge system suitable for supercritical carbon dioxide closed-loop systems. Based on detecting surge risk and accurately identifying its causes, the system can implement inlet gas replenishment or outlet working fluid temporary storage through buffer tanks, thereby keeping the compressor inlet temperature and pressure within the allowable range. Summary of the Invention

[0004] The purpose of this invention is to provide a collaborative anti-surge system and method for supercritical carbon dioxide compressors based on working fluid inventory adjustment and inlet state constraints. By collaboratively adjusting the carbon dioxide working fluid inventory and anti-surge reflux, anti-surge control of the supercritical carbon dioxide compressor is achieved.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A collaborative anti-surge system for supercritical carbon dioxide compressors based on working fluid inventory adjustment and import status constraints includes:

[0007] A supercritical carbon dioxide compressor is used to compress carbon dioxide working fluid in a closed cycle.

[0008] The carbon dioxide working fluid inventory adjustment unit is used to adjust the carbon dioxide working fluid inventory in the closed cycle. It actively changes the operating state of the supercritical carbon dioxide compressor by replenishing gas to the inlet side of the supercritical carbon dioxide compressor or temporarily storing the carbon dioxide working fluid at the outlet side of the supercritical carbon dioxide compressor.

[0009] The surge state measurement and feature extraction unit is used to collect the operating parameters of the supercritical carbon dioxide compressor, the surge signal, and the state of the carbon dioxide working fluid inventory adjustment unit, and extract features for judging the surge risk.

[0010] The anti-surge recirculation unit is used to allow the carbon dioxide working fluid on the outlet side of the supercritical carbon dioxide compressor to flow back to the high-pressure side of the supercritical carbon dioxide compressor when the inventory adjustment capacity of the carbon dioxide working fluid inventory adjustment unit is insufficient, the inlet condition does not meet the constraint conditions, or in an emergency anti-surge state.

[0011] The controller is connected to the supercritical carbon dioxide compressor, the surge state measurement and feature extraction unit, the carbon dioxide working fluid inventory adjustment unit, and the anti-surge reflux unit, respectively, and is used to determine the surge risk and cause of the supercritical carbon dioxide compressor based on the operating parameters and surge signal of the supercritical carbon dioxide compressor.

[0012] Calculate the regulation capacity of the carbon dioxide working fluid inventory regulation unit, determine the inlet state constraint of the supercritical carbon dioxide compressor, and select to control the carbon dioxide working fluid inventory regulation unit to perform gas replenishment to the inlet side of the supercritical carbon dioxide compressor, temporary storage or combined regulation at the outlet side, or control the anti-surge backflow unit to open when the predetermined conditions are met.

[0013] Furthermore, the carbon dioxide working fluid inventory adjustment unit includes: a carbon dioxide buffer storage tank, a high-pressure side filling tank adjustment valve, and a low-pressure side gas replenishment adjustment valve;

[0014] The low-pressure side of the carbon dioxide buffer storage tank is connected to the inlet of the supercritical carbon dioxide compressor in sequence through a low-pressure side gas supply branch and a compressor inlet pipeline.

[0015] The low-pressure side gas supply regulating valve is installed on the low-pressure side gas supply branch and is used to control the supply of carbon dioxide from the carbon dioxide buffer storage tank to the inlet of the supercritical carbon dioxide compressor.

[0016] The outlet side of the supercritical carbon dioxide compressor is connected to the high-pressure side of the carbon dioxide buffer tank in sequence through a high-pressure side filling tank branch and a high-pressure side filling tank regulating valve.

[0017] The high-pressure side filling tank regulating valve is installed on the high-pressure side filling tank branch and is used to control the temporary storage of carbon dioxide from the supercritical carbon dioxide compressor outlet into the carbon dioxide buffer storage tank.

[0018] Furthermore, the working pressure of the carbon dioxide buffer tank is set to be higher than the inlet pressure of the supercritical carbon dioxide compressor and lower than the outlet pressure of the supercritical carbon dioxide compressor.

[0019] Furthermore, the anti-surge return unit includes: an anti-surge regulating valve;

[0020] The anti-surge regulating valve is connected to the compressor outlet pipe and the compressor inlet pipe through the anti-surge return pipe.

[0021] Furthermore, the operating parameters of the supercritical carbon dioxide compressor collected by the surge state measurement and feature extraction unit include: the inlet temperature, inlet pressure, inlet flow rate, outlet pressure, rotational speed, dynamic pressure pulsation signal, and vibration signal of the supercritical carbon dioxide compressor;

[0022] The status of the carbon dioxide working fluid inventory adjustment unit includes: the pressure and temperature of the carbon dioxide buffer storage tank;

[0023] The surge state measurement and feature extraction unit is configured to perform sliding time window processing on dynamic pressure pulsation signals and vibration signals to extract features within a preset surge characteristic frequency band.

[0024] The features include: the energy proportion of the dynamic pressure surge characteristic frequency band, the energy proportion of the vibration surge characteristic frequency band, the energy growth rate of the dynamic pressure surge characteristic frequency band, and the coherence of the dynamic pressure signal and the vibration signal in the surge characteristic frequency band.

[0025] Furthermore, the surge risk and its causes include: insufficient inlet flow, increased outlet back pressure, or a combination thereof;

[0026] When the inlet flow rate of the supercritical carbon dioxide compressor decreases or the rate of decrease exceeds a preset value, but the outlet pressure or pressure ratio of the supercritical carbon dioxide compressor does not increase, it is judged as a surge risk due to insufficient inlet flow rate.

[0027] When the outlet pressure, pressure ratio, or outlet pressure rise rate of a supercritical carbon dioxide compressor exceeds a preset value, and the change in the inlet flow rate of the supercritical carbon dioxide compressor is not a major influencing factor, it is judged as a surge risk due to increased outlet back pressure.

[0028] When the inlet flow rate of the supercritical carbon dioxide compressor decreases and the outlet back pressure of the supercritical carbon dioxide compressor increases simultaneously to the corresponding conditions, it is judged as a compound surge risk.

[0029] This invention also provides a method for a synergistic anti-surge system for a supercritical carbon dioxide compressor based on working fluid inventory adjustment and inlet condition constraints, comprising the following steps:

[0030] S1. Collect the operating parameters of the supercritical carbon dioxide compressor and detect surge signals and buffer tank status;

[0031] S2. Based on the operating parameters and surge signal of the supercritical carbon dioxide compressor, determine the surge risk level of the supercritical carbon dioxide compressor and whether the surge risk level meets the conditions for active anti-surge.

[0032] When the conditions for active anti-surge are met, identify the cause of surge; the causes of surge include: insufficient inlet flow, increased outlet back pressure, or a combination thereof.

[0033] S3. Determine the available make-up gas volume and remaining storage capacity of the carbon dioxide buffer tank, and determine whether the inlet temperature and inlet pressure of the supercritical carbon dioxide compressor meet the constraints.

[0034] When the surge risk is of the insufficient inlet flow type and the inventory adjustment conditions are met, control the carbon dioxide buffer storage tank to replenish gas to the inlet of the supercritical carbon dioxide compressor.

[0035] When the surge risk is of the type of increased outlet back pressure and the inventory adjustment conditions are met, control the carbon dioxide on the outlet side of the supercritical carbon dioxide compressor to enter the carbon dioxide buffer storage tank.

[0036] When the surge risk is complex and the inventory adjustment conditions are met, import gas replenishment and temporary storage of working fluid on the export side are carried out simultaneously or in stages.

[0037] When inventory adjustment capacity is insufficient, import status does not meet requirements, or emergency anti-surge conditions are met, anti-surge reflux is activated.

[0038] S4. After the surge risk is eliminated, under the constraints of the inlet temperature, inlet pressure and surge risk of the supercritical carbon dioxide compressor, restore the carbon dioxide buffer tank inventory at a limited rate.

[0039] The present invention also provides an electronic device, including a processor and a memory, wherein the memory stores a computer program, and when the computer program is executed by the processor, it implements a method for coordinated anti-surge of a supercritical carbon dioxide compressor based on working fluid inventory adjustment and inlet state constraints.

[0040] The present invention also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements a method for coordinated anti-surge of a supercritical carbon dioxide compressor based on working fluid inventory adjustment and inlet state constraints.

[0041] According to specific embodiments provided by the present invention, the present invention has the following technical effects compared to the prior art:

[0042] This invention achieves a fundamental shift in the anti-surge strategy of supercritical carbon dioxide compressors from passive response to active defense by introducing a collaborative control mechanism between a carbon dioxide working fluid inventory adjustment unit and an anti-surge reflux unit. Relying on a surge state measurement and feature extraction unit, it accurately identifies surge risks and their causes. The controller comprehensively evaluates the working fluid inventory adjustment capability and inlet state constraints, prioritizing active adjustment methods such as inlet gas replenishment or outlet-side temporary storage to change the compressor's operating state. This effectively expands the compressor's stable operating margin while maintaining inlet parameters that meet constraints. When the inventory adjustment capability is insufficient or an emergency situation arises, the anti-surge reflux unit seamlessly connects. This collaborative anti-surge architecture not only significantly reduces the additional energy consumption and heat loss caused by traditional single anti-surge reflux, ensuring efficient, safe, and continuous operation of the closed-loop system under varying operating conditions, but also specifically solves the inlet state control problem caused by the high sensitivity of supercritical carbon dioxide working fluid properties, significantly improving the overall system's dynamic response speed, energy efficiency, and anti-surge robustness. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0044] The following description, in conjunction with the accompanying drawings, further illustrates the present invention of a supercritical carbon dioxide compressor synergistic anti-surge system and method based on working fluid inventory adjustment and import status constraint.

[0045] Figure 1 This is a schematic diagram of the overall structure of the supercritical carbon dioxide compressor anti-surge system based on working fluid inventory adjustment and import status constraints in Embodiment 1 of the present invention;

[0046] Figure 2 This is a flowchart of the collaborative anti-surge control in this invention;

[0047] Figure 3 This is a flowchart of the working fluid inventory recovery control process in this invention.

[0048] In the attached diagram: 1. Supercritical carbon dioxide compressor; 2. Compressor inlet pipeline; 3. Compressor outlet pipeline; 4. Carbon dioxide buffer tank; 5. High-pressure side filling branch; 6. High-pressure side filling regulating valve; 7. Low-pressure side make-up gas branch; 8. Low-pressure side make-up gas regulating valve; 9. Surge state measurement and feature extraction unit; 10. Anti-surge return pipeline; 11. Anti-surge regulating valve; 12. Controller. Detailed Implementation

[0049] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0050] To better understand the purpose, structure, and function of this invention, the invention will be described in further detail below with reference to the accompanying drawings.

[0051] Example 1

[0052] like Figure 1 As shown, this invention provides a synergistic anti-surge system for a supercritical carbon dioxide compressor based on working fluid inventory adjustment and inlet state constraints, comprising:

[0053] Supercritical carbon dioxide compressor 1, used to compress carbon dioxide working fluid in a closed cycle;

[0054] The carbon dioxide working fluid inventory adjustment unit is used to adjust the carbon dioxide working fluid inventory in the closed cycle. It actively changes the operating state of the supercritical carbon dioxide compressor 1 by supplementing gas to the inlet side of the supercritical carbon dioxide compressor 1 or temporarily storing the carbon dioxide working fluid at the outlet side of the supercritical carbon dioxide compressor 1.

[0055] The surge state measurement and feature extraction unit 9 is used to collect the operating parameters of the supercritical carbon dioxide compressor 1, the surge signal and the state of the carbon dioxide working fluid inventory adjustment unit, and extract features for judging the surge risk.

[0056] The anti-surge recirculation unit is used to allow the carbon dioxide working medium on the outlet side of the supercritical carbon dioxide compressor 1 to flow back to the high-pressure side of the supercritical carbon dioxide compressor 1 when the inventory adjustment capacity of the carbon dioxide working medium inventory adjustment unit is insufficient, the inlet status does not meet the constraint conditions, or in an emergency anti-surge state.

[0057] The controller is connected to the supercritical carbon dioxide compressor 1, the surge state measurement and feature extraction unit 9, the carbon dioxide working fluid inventory adjustment unit and the anti-surge reflux unit, respectively, and is used to determine the surge risk and cause of the supercritical carbon dioxide compressor 1 based on the operating parameters and surge signal of the supercritical carbon dioxide compressor 1.

[0058] Calculate the regulation capacity of the carbon dioxide working fluid inventory regulation unit, determine the inlet state constraint of the supercritical carbon dioxide compressor 1, and select to control the carbon dioxide working fluid inventory regulation unit to perform gas replenishment to the inlet side, temporary storage or combined regulation at the outlet side of the supercritical carbon dioxide compressor 1, or control the anti-surge backflow unit to open when the predetermined conditions are met.

[0059] In this embodiment, surge risk includes: normal state, active anti-surge state, and emergency anti-surge state.

[0060] When the surge characteristics do not meet the conditions for active anti-surge, the supercritical carbon dioxide compressor 1 continues to operate normally, and the controller continuously monitors and records the operating data.

[0061] When multiple surge characteristics reach preset conditions within multiple consecutive time windows, the controller determines that the supercritical carbon dioxide compressor 1 has reached the active anti-surge condition.

[0062] When dynamic pressure pulsation, vibration, flow rate or pressure fluctuations exceed the emergency threshold, or when a reverse flow trend occurs, the controller determines that the supercritical carbon dioxide compressor 1 has reached the emergency anti-surge condition.

[0063] The carbon dioxide working fluid inventory adjustment unit includes: a carbon dioxide buffer storage tank 4, a high-pressure side filling regulating valve 6, and a low-pressure side gas replenishment regulating valve 8;

[0064] The low-pressure side of the carbon dioxide buffer storage tank 4 is connected to the inlet of the supercritical carbon dioxide compressor 1 in sequence through the low-pressure side gas supply branch 7 and the compressor inlet pipeline 2.

[0065] The low-pressure side gas supply regulating valve is installed on the low-pressure side gas supply branch and is used to control the supply of carbon dioxide from the carbon dioxide buffer storage tank 4 to the inlet of the supercritical carbon dioxide compressor 1.

[0066] The outlet side of the supercritical carbon dioxide compressor 1 is connected to the high-pressure side of the carbon dioxide buffer storage tank 4 via the high-pressure side filling branch 5 and the high-pressure side filling regulating valve 6 in sequence.

[0067] The high-pressure side filling tank regulating valve 6 is installed on the high-pressure side filling tank branch 5 and is used to control the temporary storage of carbon dioxide from the outlet of the supercritical carbon dioxide compressor 1 into the carbon dioxide buffer storage tank 4.

[0068] In this embodiment, the inlet state constraints of the supercritical carbon dioxide compressor 1 include: inlet temperature constraints and inlet pressure constraints.

[0069] The compressor inlet temperature and inlet pressure are predetermined based on the compressor's allowable operating range.

[0070] Before performing low-pressure side gas replenishment, high-pressure side tank filling, or anti-surge backflow, the controller 12 determines whether the corresponding action will cause the inlet temperature or inlet pressure of the supercritical carbon dioxide compressor 1 to exceed the allowable range.

[0071] When low-pressure side air supply may cause the inlet temperature or inlet pressure to exceed the limit, controller 12 restricts the opening of the low-pressure side air supply regulating valve 8, or stops the inlet air supply and switches to other anti-surge modes.

[0072] When the high-pressure side filling tank causes the pressure on the low-pressure side of the closed-loop system to drop, and the inlet pressure of the supercritical carbon dioxide compressor 1 approaches the lower limit of the allowable limit, the controller 12 limits the high-pressure side filling tank flow rate, or simultaneously implements controlled low-pressure side gas replenishment.

[0073] When the anti-surge backflow causes the inlet temperature of the supercritical carbon dioxide compressor 1 to approach the upper limit of the allowable limit, the controller 12 limits the anti-surge backflow rate; if the surge risk continues to increase, emergency protection is activated.

[0074] Therefore, during the process of adjusting the working fluid inventory and preventing surge backflow, the inlet temperature and inlet pressure of the supercritical carbon dioxide compressor 1 are kept within the allowable range.

[0075] The working pressure of the carbon dioxide buffer tank 4 is set to be higher than the inlet pressure of the supercritical carbon dioxide compressor 1 and lower than the outlet pressure of the supercritical carbon dioxide compressor 1, so that carbon dioxide from the outlet side of the supercritical carbon dioxide compressor 1 can enter the carbon dioxide buffer tank 4, and carbon dioxide in the carbon dioxide buffer tank 4 can enter the inlet pipeline of the supercritical carbon dioxide compressor 1.

[0076] The anti-surge return unit includes: an anti-surge regulating valve 11;

[0077] The anti-surge regulating valve 11 is connected to the compressor outlet pipe 3 and the compressor inlet pipe 2 through the anti-surge return pipe 10.

[0078] When the working fluid inventory adjustment capacity is insufficient, the inlet status of the supercritical carbon dioxide compressor 1 does not meet the constraint conditions, or the supercritical carbon dioxide compressor 1 reaches the emergency anti-surge condition, the controller 12 opens the anti-surge regulating valve 11, so that part of the carbon dioxide on the outlet side of the supercritical carbon dioxide compressor 1 returns to the inlet of the supercritical carbon dioxide compressor 1 through the anti-surge return pipeline 10.

[0079] The operating parameters of the supercritical carbon dioxide compressor 1 collected by the surge state measurement and feature extraction unit 9 include: inlet temperature, inlet pressure, inlet flow rate, outlet pressure, rotational speed, dynamic pressure pulsation signal, and vibration signal of the supercritical carbon dioxide compressor 1.

[0080] The status of the carbon dioxide working fluid inventory adjustment unit includes: the pressure and temperature of the carbon dioxide buffer storage tank 4;

[0081] The surge state measurement and feature extraction unit is configured to perform sliding time window processing on dynamic pressure pulsation signals and vibration signals to extract features within a preset surge characteristic frequency band.

[0082] The features include: the energy proportion of the dynamic pressure surge characteristic frequency band, the energy proportion of the vibration surge characteristic frequency band, the energy growth rate of the dynamic pressure surge characteristic frequency band, and the coherence of the dynamic pressure signal and the vibration signal in the surge characteristic frequency band.

[0083] The controller 12 combines the above characteristics with the changes in the inlet flow rate, outlet pressure and pressure ratio of the supercritical carbon dioxide compressor 1 to determine the surge risk of the supercritical carbon dioxide compressor 1.

[0084] The controller is specifically used for:

[0085] Determine the surge risk level of supercritical carbon dioxide compressor 1, and identify the causes of surge risk when active anti-surge conditions are met; the causes of surge risk include: insufficient inlet flow, increased outlet back pressure, or a combination thereof;

[0086] The available make-up gas volume and remaining storage capacity of carbon dioxide buffer storage tank 4 are calculated based on the pressure, temperature and volume of carbon dioxide buffer storage tank 4.

[0087] In this embodiment, the controller 12 determines the inventory status of the carbon dioxide buffer tank 4 based on the pressure, temperature, and volume of the carbon dioxide buffer tank 4.

[0088] Inventory status includes: the quantity of available working fluid that can be replenished to the compressor inlet and the remaining storage capacity to receive working fluid from the compressor outlet.

[0089] When the working fluid inventory in carbon dioxide buffer tank 4 is higher than the minimum allowable inventory, carbon dioxide buffer tank 4 has the capacity for inlet gas replenishment.

[0090] When the pressure and the amount of working medium stored in the carbon dioxide buffer tank 4 are lower than the maximum allowable value, the carbon dioxide buffer tank 4 has the ability to receive the working medium from the outlet side of the supercritical carbon dioxide compressor 1.

[0091] Only when the working fluid inventory adjustment capability and the inlet state constraint of the supercritical carbon dioxide compressor 1 both meet the requirements will the working fluid inventory adjustment be given priority for anti-surge control.

[0092] Determine that the inlet temperature or inlet pressure of carbon dioxide buffer storage tank 4 exceeds the allowable range;

[0093] After the surge risk is eliminated, under the constraints of the inlet temperature, inlet pressure and surge risk of the supercritical carbon dioxide compressor 1, the buffer tank inventory is gradually restored according to the preset mass flow rate change rate or valve opening change rate.

[0094] Among them, surge risks and causes include: insufficient inlet flow, increased outlet back pressure, or a combination thereof;

[0095] When the inlet flow rate of supercritical carbon dioxide compressor 1 decreases or the rate of decrease in inlet flow rate exceeds a preset value, and the outlet pressure or pressure ratio of supercritical carbon dioxide compressor 1 does not increase, it is judged as a surge risk due to insufficient inlet flow rate.

[0096] When the outlet pressure, pressure ratio, or outlet pressure rise rate of the supercritical carbon dioxide compressor 1 exceeds the preset value, and the change in the inlet flow rate of the supercritical carbon dioxide compressor 1 is not the main influencing factor, it is judged as a surge risk of increased outlet back pressure.

[0097] When the inlet flow rate of supercritical carbon dioxide compressor 1 decreases and the outlet back pressure of supercritical carbon dioxide compressor 1 increases simultaneously to the corresponding conditions, it is judged as a compound surge risk.

[0098] When the inlet flow rate of supercritical carbon dioxide compressor 1 decreases and the outlet back pressure increases simultaneously, it is judged to be a compound surge risk.

[0099] The characteristics of dynamic pressure and vibration signals are used to verify whether flow instability is developing continuously, reducing misjudgments caused by instantaneous changes in inlet flow rate or outlet pressure alone.

[0100] During the processes of inlet gas replenishment, outlet side temporary storage, compound regulation, or anti-surge backflow, the operating status, inlet temperature, inlet pressure, and surge risk of the supercritical carbon dioxide compressor 1 are continuously monitored, and the opening degree of the corresponding valves is adjusted according to the monitoring results.

[0101] When the supercritical carbon dioxide compressor 1 reaches the emergency anti-surge condition, the anti-surge regulating valve 11 is opened quickly, and speed reduction, load limiting, or shutdown protection is implemented.

[0102] Before starting the recovery of the working fluid inventory, check whether the surge risk has been eliminated and determine whether the inlet temperature and inlet pressure of the supercritical carbon dioxide compressor 1 are within the allowable range.

[0103] If the conditions for starting inventory recovery are not met, maintain the current inventory status and continue to monitor the import status and surge risk.

[0104] During the anti-surge process, when the carbon dioxide buffer storage tank 4 replenishes carbon dioxide to the inlet of the supercritical carbon dioxide compressor 1, after the supercritical carbon dioxide compressor 1 has stabilized, the working medium is gradually replenished to the carbon dioxide buffer storage tank 4 through the high-pressure side charging tank branch.

[0105] When the carbon dioxide buffer tank 4 receives carbon dioxide from the outlet side of the supercritical carbon dioxide compressor 1 during the anti-surge process, and the inlet state of the supercritical carbon dioxide compressor 1 allows, the carbon dioxide in the carbon dioxide buffer tank 4 is gradually released to the low-pressure side through the low-pressure side gas supply branch.

[0106] The controller 12 gradually restores the carbon dioxide buffer tank 4's inventory according to the preset mass flow rate change rate or valve opening change rate, avoiding pressure fluctuations on the high and low pressure sides caused by rapid transfer of the working fluid.

[0107] During the inventory recovery process, the inlet temperature, inlet pressure, and surge risk of the supercritical carbon dioxide compressor 1 are continuously monitored.

[0108] When imports approach the permissible limit or the risk of a surge increases again, inventory recovery should be suspended or the rate of inventory recovery reduced.

[0109] When the import status is within the allowable range and the risk of surge does not increase, continue to restore the inventory of carbon dioxide buffer storage tank 4.

[0110] Once the carbon dioxide buffer tank 4 is restored to the target inventory level, the inventory restoration control ends, and the system returns to normal operation monitoring status.

[0111] Continue monitoring and adjustment as long as the risk of surge remains.

[0112] Once the surge risk is eliminated, the working fluid inventory will be restored to control.

[0113] In this embodiment, the controller 12 selects the following control method based on the cause of surge, the available replenishment volume of the carbon dioxide buffer tank 4, the remaining storage capacity, and the inlet temperature and inlet pressure of the supercritical carbon dioxide compressor 1:

[0114] (1) Carbon dioxide is supplied from the carbon dioxide buffer storage tank 4 to the inlet of the supercritical carbon dioxide compressor 1;

[0115] (2) The carbon dioxide at the outlet side of the supercritical carbon dioxide compressor 1 is temporarily stored in the carbon dioxide buffer storage tank 4;

[0116] (3) Simultaneously or at different times, the inlet gas supply of the supercritical carbon dioxide compressor 1 and the outlet gas storage of the supercritical carbon dioxide compressor 1 are implemented.

[0117] (4) Open the anti-surge return pipeline.

[0118] In summary, this embodiment has the following technical innovations:

[0119] (1) Using closed-loop working fluid inventory adjustment as an active anti-surge measure

[0120] This invention utilizes a carbon dioxide buffer tank 4 to perform short-term bidirectional transfer of the working fluid in a closed-loop system, and actively changes the compressor's operating state by supplementing gas at the inlet or temporarily storing the working fluid at the outlet.

[0121] (2) Select the working fluid transfer direction based on the cause of surge.

[0122] To address the surge risk caused by insufficient inlet flow, carbon dioxide buffer storage tank 4 is used to replenish gas to the inlet of supercritical carbon dioxide compressor 1; to address the surge risk caused by increased outlet back pressure, carbon dioxide on the outlet side of supercritical carbon dioxide compressor 1 is temporarily stored in carbon dioxide buffer storage tank 4; to address the combined surge risk, coordinated control of gas replenishment and temporary storage is implemented.

[0123] (3) Use import temperature and import pressure as inventory adjustment constraints.

[0124] The working fluid inventory adjustment is not initiated solely based on surge risk, but simultaneously assesses the inlet temperature and inlet pressure of the supercritical carbon dioxide compressor 1 to prevent gas replenishment, tank filling, or reflux operations from causing the inlet status of the supercritical carbon dioxide compressor 1 to exceed the allowable range.

[0125] (4) Prioritize inventory adjustment and supplement with traditional return flow

[0126] When the storage capacity and import status constraints of the carbon dioxide buffer storage tank 4 meet the requirements, the import replenishment or temporary storage on the export side shall be given priority; when the storage capacity is insufficient, the import status does not meet the requirements, or the emergency anti-surge conditions are met, the traditional anti-surge reflux shall be activated.

[0127] (5) Pressure pulsation and vibration characteristics are used together to identify surge risk.

[0128] This invention extracts the energy characteristics, growth characteristics, and coherence characteristics of dynamic pressure and vibration signals within the surge characteristic frequency band to confirm the development trend of flow instability and reduce misjudgments caused by fluctuations in a single parameter.

[0129] (6) Inventory recovery control constrained by import status

[0130] After the surge risk is eliminated, based on the inlet temperature, inlet pressure, and surge risk of the supercritical carbon dioxide compressor 1, the buffer tank inventory is gradually restored at a limited rate to reduce the risk of secondary surge caused by rapid inventory recovery.

[0131] Compared with the control method that only uses an anti-surge backflow valve, the present invention also has the following advantages:

[0132] (1) It can select either inlet replenishment or outlet temporary storage based on the cause of surge;

[0133] (2) It can increase the compressor inlet flow rate by utilizing the working fluid inventory in a closed-loop system;

[0134] (3) It can temporarily receive carbon dioxide from the high-pressure side when the outlet back pressure increases;

[0135] (4) It can reduce the direct reflux of high-temperature carbon dioxide at the outlet of supercritical carbon dioxide compressor 1;

[0136] (5) It can reduce unnecessary reflux losses;

[0137] (6) It can maintain stable compressor inlet temperature and inlet pressure during anti-surge process;

[0138] (7) It can reduce the risk of false triggering by using dynamic pressure and vibration signal characteristics;

[0139] (8) It can reduce the risk of secondary surge by restoring inventory at a limited rate;

[0140] (9) It can improve the stability of supercritical carbon dioxide closed cycle under variable load and abnormal disturbance conditions.

[0141] Example 2

[0142] The present invention also provides a method for the anti-surge system of a supercritical carbon dioxide compressor based on working fluid inventory adjustment and inlet state constraints in Example 1, comprising the following steps:

[0143] S1. Collect the operating parameters of supercritical carbon dioxide compressor 1, and detect surge signals and buffer tank status;

[0144] S2. Based on the operating parameters and surge signal of the supercritical carbon dioxide compressor 1, determine the surge risk level of the supercritical carbon dioxide compressor 1 and whether the surge risk level meets the conditions for active anti-surge.

[0145] When the conditions for active anti-surge are met, identify the cause of surge; the causes of surge include: insufficient inlet flow, increased outlet back pressure, or a combination thereof.

[0146] S3. Determine the available gas supply and remaining storage capacity of the carbon dioxide buffer tank 4, and determine whether the inlet temperature and inlet pressure of the supercritical carbon dioxide compressor 1 meet the constraints.

[0147] When the surge risk is of the insufficient inlet flow type and the inventory adjustment conditions are met, control the carbon dioxide buffer storage tank 4 to supply gas to the inlet of the supercritical carbon dioxide compressor 1.

[0148] When the surge risk is of the type of increased outlet back pressure and the inventory adjustment conditions are met, the carbon dioxide on the outlet side of the supercritical carbon dioxide compressor 1 is controlled to enter the carbon dioxide buffer storage tank 4.

[0149] When the surge risk is complex and the inventory adjustment conditions are met, import gas replenishment and temporary storage of working fluid on the export side are carried out simultaneously or in stages.

[0150] When inventory adjustment capacity is insufficient, import status does not meet requirements, or emergency anti-surge conditions are met, anti-surge reflux is activated.

[0151] S4. After the surge risk is eliminated, under the constraints of the inlet temperature, inlet pressure and surge risk of the supercritical carbon dioxide compressor 1, the inventory of the carbon dioxide buffer storage tank 4 is restored at a limited rate.

[0152] Specifically, in this embodiment, when the surge risk is of the insufficient inlet flow type, and the carbon dioxide buffer tank 4 has available replenishment gas volume and the inlet status meets the constraints, the low-pressure side replenishment gas regulating valve is opened.

[0153] Carbon dioxide in carbon dioxide buffer storage tank 4 enters the inlet of supercritical carbon dioxide compressor 1 through the low-pressure side make-up gas branch to increase the inlet flow of supercritical carbon dioxide compressor 1.

[0154] When the surge risk is of the type of increased outlet back pressure and the buffer tank has remaining storage capacity, open the high-pressure side filling regulating valve.

[0155] Some of the carbon dioxide from the outlet side of the supercritical carbon dioxide compressor 1 enters the carbon dioxide buffer storage tank 4 via the high-pressure side filling tank branch 5, in order to reduce the outlet pressure of the supercritical carbon dioxide compressor 1 or limit the rate of increase of the outlet pressure.

[0156] When the surge risk is complex and the inventory adjustment capacity and import status constraints meet the requirements, import replenishment and temporary storage on the export side can be implemented simultaneously or in stages.

[0157] The anti-surge regulating valve will be activated if any of the following conditions occur:

[0158] (1) The available replenishment gas volume of carbon dioxide buffer storage tank 4 is insufficient;

[0159] (2) The remaining storage capacity of carbon dioxide buffer tank 4 is insufficient;

[0160] (3) Imported gas replenishment or temporary storage on the export side may cause the import temperature or import pressure to exceed the limit;

[0161] (4) The risk of surge continues to increase even after adjustments to the working fluid inventory;

[0162] (5) The supercritical carbon dioxide compressor 1 reaches the emergency anti-surge condition.

[0163] After opening the anti-surge regulating valve 11, some of the carbon dioxide on the compressor outlet side returns to the compressor inlet through the anti-surge return pipeline 10.

[0164] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A collaborative anti-surge system for a supercritical carbon dioxide compressor based on working fluid inventory adjustment and inlet condition constraints, characterized in that, include: A supercritical carbon dioxide compressor (1) is used to compress carbon dioxide working fluid in a closed cycle. The carbon dioxide working fluid inventory adjustment unit is used to adjust the carbon dioxide working fluid inventory in the closed cycle. It actively changes the operating state of the supercritical carbon dioxide compressor (1) by supplementing gas to the inlet side of the supercritical carbon dioxide compressor (1) or temporarily storing the carbon dioxide working fluid at the outlet side of the supercritical carbon dioxide compressor (1). The surge state measurement and feature extraction unit (9) is used to collect the operating parameters of the supercritical carbon dioxide compressor (1), the surge signal and the state of the carbon dioxide working fluid inventory adjustment unit, and extract features for judging the surge risk. The anti-surge recirculation unit is used to allow the carbon dioxide working medium on the outlet side of the supercritical carbon dioxide compressor (1) to flow back to the high-pressure side of the supercritical carbon dioxide compressor (1) when the inventory adjustment capacity of the carbon dioxide working medium inventory adjustment unit is insufficient, the inlet state does not meet the constraint conditions, or the emergency anti-surge state is under conditions. The controller (12) is connected to the supercritical carbon dioxide compressor (1), the surge state measurement and feature extraction unit (9), the carbon dioxide working fluid inventory adjustment unit and the anti-surge reflux unit, respectively, and is used to determine the surge risk and cause of the supercritical carbon dioxide compressor (1) based on the operating parameters and surge signal of the supercritical carbon dioxide compressor (1); Calculate the regulation capacity of the carbon dioxide working fluid storage regulation unit, determine the inlet state constraint of the supercritical carbon dioxide compressor (1), and select to control the carbon dioxide working fluid storage regulation unit to perform gas replenishment to the inlet side, temporary storage or compound regulation to the outlet side of the supercritical carbon dioxide compressor (1), or control the anti-surge backflow unit to open when the predetermined conditions are met.

2. The supercritical carbon dioxide compressor coordinated anti-surge system based on working fluid inventory adjustment and import status constraints according to claim 1, characterized in that, The carbon dioxide working fluid inventory adjustment unit includes: a carbon dioxide buffer storage tank (4), a high-pressure side filling regulating valve (6), and a low-pressure side gas replenishment regulating valve (8). The low-pressure side of the carbon dioxide buffer tank (4) is connected to the inlet of the supercritical carbon dioxide compressor (1) in sequence through the low-pressure side gas supply branch (7) and the compressor inlet pipeline (2); The low-pressure side gas supply regulating valve is installed on the low-pressure side gas supply branch (7) and is used to control the supply of carbon dioxide from the carbon dioxide buffer tank (4) to the inlet of the supercritical carbon dioxide compressor (1). The outlet side of the supercritical carbon dioxide compressor (1) is connected to the high-pressure side of the carbon dioxide buffer tank (4) in sequence through the high-pressure side filling branch (5) and the high-pressure side filling regulating valve (6). The high-pressure side filling tank regulating valve (6) is installed on the high-pressure side filling tank branch (5) and is used to control the temporary storage of carbon dioxide from the outlet of the supercritical carbon dioxide compressor (1) into the carbon dioxide buffer storage tank (4).

3. The supercritical carbon dioxide compressor coordinated anti-surge system based on working fluid inventory adjustment and import status constraints according to claim 2, characterized in that, The working pressure of the carbon dioxide buffer tank (4) is set to be higher than the inlet pressure of the supercritical carbon dioxide compressor (1) and lower than the outlet pressure of the supercritical carbon dioxide compressor (1).

4. The supercritical carbon dioxide compressor coordinated anti-surge system based on working fluid inventory adjustment and import status constraints according to claim 1, characterized in that, The anti-surge return unit includes: an anti-surge regulating valve (11); The anti-surge regulating valve (11) is connected to the compressor outlet pipe (3) and the compressor inlet pipe (2) through the anti-surge return pipe (10).

5. The supercritical carbon dioxide compressor coordinated anti-surge system based on working fluid inventory adjustment and import status constraints according to claim 1, characterized in that, The operating parameters of the supercritical carbon dioxide compressor (1) collected by the surge state measurement and feature extraction unit (9) include: inlet temperature, inlet pressure, inlet flow rate, outlet pressure, speed, dynamic pressure pulsation signal, and vibration signal of the supercritical carbon dioxide compressor (1); The status of the carbon dioxide working fluid inventory adjustment unit includes: the pressure and temperature of the carbon dioxide buffer storage tank (4); The surge state measurement and feature extraction unit is configured to perform sliding time window processing on dynamic pressure pulsation signals and vibration signals to extract features within a preset surge characteristic frequency band. The features include: the energy proportion of the dynamic pressure surge characteristic frequency band, the energy proportion of the vibration surge characteristic frequency band, the energy growth rate of the dynamic pressure surge characteristic frequency band, and the coherence of the dynamic pressure signal and the vibration signal in the surge characteristic frequency band.

6. The supercritical carbon dioxide compressor coordinated anti-surge system based on working fluid inventory adjustment and import status constraints according to claim 1, characterized in that, The surge risks and causes include: insufficient inlet flow, increased outlet back pressure, or a combination thereof; When the inlet flow rate of the supercritical carbon dioxide compressor (1) decreases or the rate of decrease in inlet flow rate exceeds the preset value, and the outlet pressure or pressure ratio of the supercritical carbon dioxide compressor (1) does not increase, it is judged as a surge risk due to insufficient inlet flow rate. When the outlet pressure, pressure ratio or outlet pressure rise rate of the supercritical carbon dioxide compressor (1) exceeds the preset value, and the change in the inlet flow rate of the supercritical carbon dioxide compressor (1) is not the main influencing factor, it is judged as a surge risk of increased outlet back pressure. When the inlet flow rate of the supercritical carbon dioxide compressor (1) decreases and the outlet back pressure of the supercritical carbon dioxide compressor (1) increases simultaneously to the corresponding conditions, it is judged as a compound surge risk.

7. A method for coordinated anti-surge of a supercritical carbon dioxide compressor based on working fluid inventory adjustment and inlet state constraints, applied to the coordinated anti-surge system for a supercritical carbon dioxide compressor based on working fluid inventory adjustment and inlet state constraints as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Collect the operating parameters of the supercritical carbon dioxide compressor (1) and detect the surge signal and the status of the buffer tank; S2. Based on the operating parameters and surge signal of the supercritical carbon dioxide compressor (1), determine the surge risk level of the supercritical carbon dioxide compressor (1) and whether the surge risk level meets the active anti-surge conditions. When the conditions for active anti-surge are met, identify the cause of surge; the causes of surge include: insufficient inlet flow, increased outlet back pressure, or a combination thereof. S3. Determine the available gas supply and remaining storage capacity of the carbon dioxide buffer tank (4), and determine whether the inlet temperature and inlet pressure of the supercritical carbon dioxide compressor (1) meet the constraints. When the surge risk is of the insufficient inlet flow type and the inventory adjustment conditions are met, control the carbon dioxide buffer tank (4) to replenish gas to the inlet of the supercritical carbon dioxide compressor (1); When the surge risk is of the type of increased outlet back pressure and the inventory adjustment conditions are met, the carbon dioxide on the outlet side of the supercritical carbon dioxide compressor (1) is controlled to enter the carbon dioxide buffer storage tank (4). When the surge risk is complex and the inventory adjustment conditions are met, import gas replenishment and temporary storage of working fluid on the export side are carried out simultaneously or in stages. When inventory adjustment capacity is insufficient, import status does not meet requirements, or emergency anti-surge conditions are met, anti-surge reflux is activated. S4. After the surge risk is relieved, under the constraints of the inlet temperature, inlet pressure and surge risk of the supercritical carbon dioxide compressor (1), the inventory of the carbon dioxide buffer tank (4) is restored at a limited rate.

8. An electronic device, characterized in that, It includes a processor and a memory, wherein the memory stores a computer program, and when the computer program is executed by the processor, it implements the supercritical carbon dioxide compressor collaborative anti-surge method based on working fluid inventory adjustment and import state constraints as described in claim 7.

9. A computer-readable storage medium, characterized in that, The medium stores a computer program, which, when executed by a processor, implements the method for coordinated anti-surge of a supercritical carbon dioxide compressor based on working fluid inventory adjustment and inlet state constraints as described in claim 7.

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