A supercritical carbon dioxide turbine dry gas seal cooperative heat insulation cooling system and method based on internal and external temperature difference control

Abstract

The application discloses a supercritical carbon dioxide turbine dry gas seal cooperative heat insulation cooling system and method based on internal and external temperature difference control, and belongs to the technical field of supercritical carbon dioxide turbine sealing and cooling. The system comprises a supercritical carbon dioxide turbine, a dry gas seal assembly, a water cooling system, a CO2 heat insulation cooling system, a temperature detection unit and a controller. The water cooling system is used for cooling the turbine casing and the sealing shell; the CO2 heat insulation cooling system delivers low-temperature CO2 to the sealing cavity of the dry gas seal assembly, and forms a heat insulation cooling gas flow between the turbine hot end and the dry gas seal body; and the controller cooperatively adjusts the cooling water and CO2 cooling gas flow according to the detected dry gas seal body temperature, external structure temperature and temperature difference between the two. The application significantly reduces the dry gas seal body temperature, suppresses thermal deformation caused by uneven temperature distribution, reduces cooling medium consumption, and greatly improves the reliability and safety of the supercritical carbon dioxide turbine dry gas seal operation.

Description

Technical Field

[0001] This invention belongs to the technical field of supercritical carbon dioxide turbine sealing and cooling, specifically relating to a supercritical carbon dioxide turbine dry gas seal synergistic thermal insulation cooling system and method based on internal and external temperature difference control. Background Technology

[0002] Supercritical carbon dioxide turbines operate under high temperature, high pressure, and high speed conditions. Heat from the turbine's hot end can be transferred to the dry gas seal area at the shaft end through the high-temperature working fluid, turbine casing, and sealing housing. When the temperature of the dry gas seal body is too high, it can easily cause thermal deformation of the sealing ring, changes in the sealing end face clearance, aging of auxiliary seals, and increased leakage, which may lead to dry gas seal failure in severe cases.

[0003] Existing dry gas seal cooling technologies typically employ water cooling or gas cooling. Water cooling is primarily used to reduce the temperature of external structures such as the turbine casing and seal housing; gas cooling is mainly used to reduce the temperature of the sealing cavity and the vicinity of the dry gas seal body. However, existing technologies still have the following problems: (1) When water cooling is used alone, it mainly reduces the temperature of the external structure, and has limited direct cooling effect on the dry gas seal body and the sealing cavity; (2) When the water cooling flow rate is too high, the temperature of the external structure may be too low, while the dry gas sealing body is still at a high temperature, resulting in an increase in the temperature difference between the inside and outside. (3) When CO2 cooling is used alone, it is difficult to reduce the temperature of the turbine casing and the sealed housing at the same time; (4) Existing water cooling and CO2 cooling are usually controlled separately, lacking coordinated control to allocate cooling capacity according to the thermal state of different areas of the dry gas seal; (5) Controlling only a single temperature measuring point makes it difficult to suppress the uneven temperature between the dry gas sealing body and the external structure.

[0004] Therefore, there is a need for a cooling system and method that can coordinately adjust the cooling water flow rate and CO2 cooling gas flow rate based on the dry gas seal body temperature, the external structure temperature, and the temperature difference between the two. Summary of the Invention

[0005] This invention provides a supercritical carbon dioxide turbine dry gas seal synergistic thermal insulation cooling system and method based on internal and external temperature difference control, which solves the technical problems of existing cooling technologies that are difficult to coordinate internal and external temperature distribution, avoid excessive temperature difference and unreasonable distribution of cooling capacity.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A supercritical carbon dioxide turbine dry gas seal synergistic thermal insulation cooling system based on internal and external temperature difference control includes: a supercritical carbon dioxide turbine, a dry gas seal assembly, a water cooling system, a CO2 thermal insulation cooling system, a temperature detection unit, and a controller.

[0007] The supercritical carbon dioxide turbine includes a turbine casing and a turbine hot end located inside the turbine casing. The dry gas sealing assembly is located at the shaft end of the supercritical carbon dioxide turbine. The dry gas sealing assembly includes a dry gas sealing body, a sealing housing, and a sealing cavity. The dry gas sealing body is installed inside the sealing housing, and at least a portion of the sealing cavity is located between the dry gas sealing body and the hot end of the turbine. The water cooling system is used to cool the turbine casing and the sealing housing; The CO2 thermal insulation cooling system is used to deliver low-temperature CO2 cooling gas to the sealing cavity, so that the low-temperature CO2 forms a thermal insulation cooling airflow between the turbine hot end and the dry gas sealing body. The temperature detection unit is used to detect the temperature of the dry gas seal body and the temperature of the external structure. The controller is connected to the water cooling system, the CO2 insulation cooling system and the temperature detection unit respectively. Based on the temperature of the dry gas seal body, the temperature of the external structure and the temperature difference between the two, the controller adjusts the cooling water flow rate of the water cooling system and the CO2 cooling gas flow rate of the CO2 insulation cooling system respectively.

[0008] Furthermore, the water cooling system includes a water pump, cooling water pipelines, a water cooling channel, and a water flow regulating device. The water cooling channel is located inside the turbine casing and / or sealed housing. Cooling water is driven by the water pump to flow through the water cooling channel to remove heat from the external structure. The controller changes the cooling water flow rate by adjusting the water pump speed or the opening of the water flow regulating device.

[0009] Furthermore, the CO2 heat insulation and cooling system includes a CO2 compression system, a CO2 cooling gas supply pipeline, and a CO2 regulating valve; the CO2 cooling gas supply pipeline is connected to the sealing cavity, and the CO2 gas supply port is located on the side of the dry gas sealing body near the hot end of the turbine; the CO2 compression system supplies gas stably at a preset gas supply pressure to maintain the heat insulation and cooling airflow. The controller changes the CO2 cooling gas flow rate by adjusting the opening of the CO2 regulating valve or the gas supply of the CO2 compression system.

[0010] Furthermore, the temperature detection position of the dry gas seal body is set near the dry gas seal body, the sealing end face, or inside the sealing cavity; the temperature detection position of the external structure is set at the turbine casing and / or the sealing housing.

[0011] Furthermore, the temperature detection unit can also detect the cooling water temperature, CO2 cooling gas temperature, cooling water flow rate, and CO2 cooling gas flow rate.

[0012] Furthermore, the controller is pre-set with the allowable temperature range of the dry gas sealing body, the allowable temperature range of the external structure, the allowable temperature difference between the inside and outside, the cooling water flow rate adjustment range, and the CO2 cooling gas flow rate adjustment range.

[0013] Furthermore, the controller is configured to perform the following adjustment methods: When the temperature of the dry gas seal body, the temperature of the external structure, and the temperature difference between the inside and outside are all within the allowable range, the water cooling system and the CO2 thermal insulation cooling system operate according to the basic flow rate, and the controller continuously collects temperature data. When the temperature of the dry gas seal body exceeds the internal temperature control value and the external structure temperature is within the allowable range, the controller increases the CO2 cooling gas flow rate while keeping the cooling water flow rate constant or making a slight adjustment. When the external structure temperature exceeds the external temperature control value and the dry gas seal body temperature is within the allowable range, the controller increases the cooling water flow rate while maintaining the current CO2 cooling gas flow rate. When the temperature of the dry gas seal body and the temperature of the external structure both exceed the corresponding control values, and the temperature difference between the inside and outside is within the allowable range, the controller simultaneously increases the cooling water flow rate and the CO2 cooling gas flow rate; the adjustment amount of the cooling water flow rate is determined according to the temperature deviation of the external structure, and the adjustment amount of the CO2 cooling gas flow rate is determined according to the temperature deviation of the dry gas seal body. When the temperature of the dry gas sealing body is higher than the temperature of the external structure and the temperature difference between the two exceeds the preset temperature difference allowable range, the controller (6) increases the CO2 cooling gas flow rate and limits the cooling water flow rate from continuing to increase; When the temperature of the external structure is higher than the temperature of the dry gas seal body and the temperature difference between the two exceeds a preset value, the controller (6) increases the cooling water flow rate and maintains or limits the CO2 cooling gas flow rate. When both the cooling water flow rate and the CO2 cooling gas flow rate reach the upper limit of adjustment, and the temperature of the dry gas seal body or the temperature of the external structure still exceeds the safe value, the controller (6) issues an alarm and performs turbine load reduction or shutdown protection.

[0014] This invention also provides a method for synergistic thermal insulation cooling of supercritical carbon dioxide turbine dry gas seal based on internal and external temperature difference control, comprising the following steps: Step S1: Collect temperature parameters. The temperature T of the dry gas seal body is collected in real time through the temperature detection unit. i External structural temperature T o ; Step S2: Calculate the internal and external temperature difference. The controller uses the formula ΔT=T i -T o Calculate the internal and external temperature difference between the dry gas seal body and the external structure; Step S3: Determine the operating status. The controller retrieves preset thresholds and determines T respectively. i T o Whether ΔT falls within their respective allowable ranges; Step S4: Determine the cooling adjustment method, based on T i T o ΔT determines the adjustment direction of cooling water flow rate and CO2 cooling airflow rate; Step S5: Coordinated execution adjustment, the controller drives the water pump, water flow adjustment device, CO2 regulating valve and CO2 compression system to complete the corresponding flow adjustment, and low temperature CO2 continuously forms a heat insulation cooling airflow between the turbine hot end and the dry gas seal body; Step S6: Cyclic monitoring, continuously collecting T data in real time during the adjustment process. i T o Repeat steps S2-S5 to dynamically correct the cooling medium flow rate; Step S7: Abnormal protection judgment. When both cooling water flow rate and CO2 cooling gas flow rate reach the maximum adjustment limit, T i or T o If the load still exceeds the safety threshold, the controller will trigger an audible and visual alarm and issue a load reduction or shutdown protection command to the supercritical carbon dioxide turbine.

[0015] Furthermore, the cooling adjustment method in step S4 includes: If T i T o ΔT is within the allowable range, and the water cooling system and CO2 insulation cooling system maintain stable basic flow rate operation; If only T i Exceeding the upper limit of internal temperature, T o Within permissible limits, prioritize increasing the CO2 cooling gas supply flow rate, while keeping the cooling water flow rate unchanged or slightly adjusted. If only T o Exceeding the upper limit of external temperature, T i Within permissible limits, prioritize increasing cooling water flow rate, while maintaining the current CO2 cooling gas flow rate. If T i T o When the temperature exceeds the corresponding upper limit and ΔT is within the allowable range, the cooling water flow rate and CO2 cooling gas flow rate are adjusted simultaneously. The flow rate adjustment of the two types of media are matched to the external temperature deviation and the dry gas seal body temperature deviation, respectively. If T i >T o Furthermore, if ΔT exceeds the upper limit of the allowable value, increase the CO2 cooling gas flow rate to enhance the heat insulation cooling airflow of the sealed cavity, while limiting the cooling water flow rate to continue to increase or appropriately reducing the cooling water flow rate; If T o >Ti Furthermore, if ΔT exceeds the upper limit of the allowable value, the cooling water flow rate will be increased, while the CO2 cooling gas flow rate will be maintained or limited.

[0016] The beneficial effects of this invention are: (1) Achieve precise cooling in internal and external zones, significantly improving overall cooling efficiency. This invention clearly defines the cooling areas. The water-cooling system is specifically designed for heat dissipation from external metal structures such as the turbine casing and sealing shell. Low-temperature CO2 cooling gas is introduced into the sealing cavity, forming a flowing, heat-insulating cooling airflow between the turbine's hot end and the dry gas sealing body. This airflow not only prevents the high-temperature working fluid from the turbine from convectively transferring heat to the sealing body, but also directly removes the heat accumulated in the dry gas sealing body and sealing cavity. This overcomes the shortcomings of water cooling alone being unable to cool the sealing core and CO2 cooling alone being insufficient to reduce heat accumulation in the casing. It provides simultaneous internal and external heat dissipation, complete cooling coverage, and significantly better cooling performance than a single cooling solution.

[0017] (2) Effectively suppresses thermal deformation and thermal stress caused by temperature difference In existing technologies, excessive water cooling flow often leads to overcooling of the external structure while the internal sealing body remains at a high temperature, creating a huge temperature difference of "cold outside and hot inside," which causes severe thermal deformation. This invention uses the internal and external temperature difference as the core control parameter. The controller monitors the temperature difference between the dry gas sealing body and the external structure in real time. When the dry gas sealing body temperature is much higher than the shell temperature and the temperature difference exceeds the limit, the water cooling flow is actively limited and the CO2 cooling gas supply is increased. When the shell temperature is significantly higher than the sealing body temperature, water cooling is prioritized and the CO2 cooling gas volume is constrained. From a control logic perspective, this actively reduces the internal and external temperature difference, lowers the thermal stress on the sealing component, and avoids abnormal gaps at the sealing end faces.

[0018] (3) To achieve on-demand distribution of the two cooling media, thereby reducing media consumption and unit operating energy consumption. The controller independently adjusts the corresponding cooling medium flow rate based on the degree of overheating of the internal and external components: when the dry gas seal body temperature is too high, CO2 cooling gas is increased first; when the external structure temperature is too high, cooling water is increased first; and when both internal and external temperatures are simultaneously overheating, the adjustment is matched according to their respective temperature deviations. This on-demand coordinated control method avoids blind adjustment of a single cooling method, ensuring that the cooling medium flow rate matches the actual heat load, improving cooling efficiency, and significantly reducing cooling water circulation power consumption and CO2 cooling gas consumption, thus lowering the long-term energy consumption of the entire cooling system.

[0019] (4) Effectively reduces the risk of dry gas seal leakage and high temperature failure, and improves the reliability of unit operation. This invention can stably control the temperature of the dry gas seal body within a safe range, avoiding problems such as accelerated aging of auxiliary seals, thermal deformation of the sealing ring, and increased media leakage caused by high temperatures. At the same time, a safety protection mechanism is set up. When the cooling water flow rate and CO2 cooling gas flow rate both reach the upper limit of adjustment, but the temperature still exceeds the safety threshold, the system can automatically trigger an alarm and execute turbine load reduction or shutdown protection, avoiding unit shutdown caused by high temperature failure of the dry gas seal, extending the service life of the dry gas seal, and ensuring long-term stable and continuous operation of the supercritical carbon dioxide turbine. Attached Figure Description

[0020] For ease of explanation, the present invention will be described in detail below with reference to specific embodiments and accompanying drawings.

[0021] Figure 1 This is a schematic diagram of the system structure in this embodiment; Figure 2 This is a flowchart of the collaborative cooling control system in this embodiment.

[0022] In the picture: 1-Supercritical carbon dioxide turbine; 2-Dry gas sealing assembly; 3-Water cooling system; 4-CO2 thermal insulation cooling system; 5-Temperature detection unit; 6-Controller. Detailed Implementation

[0023] The following are specific embodiments of the present invention described in conjunction with the accompanying drawings, further illustrating the technical solutions of the present invention. However, the present invention is not limited to these embodiments. Specific details, such as particular configurations and components, are provided in the following description merely to aid in a comprehensive understanding of the embodiments of the present invention. Therefore, those skilled in the art should understand that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present invention. Furthermore, for clarity and brevity, descriptions of known functions and structures have been omitted.

[0024] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other.

[0025] like Figure 1 As shown, this embodiment provides a supercritical carbon dioxide turbine dry gas seal synergistic thermal insulation cooling system based on internal and external temperature difference control, including a supercritical carbon dioxide turbine 1, a dry gas seal assembly 2, a water cooling system 3, a CO2 thermal insulation cooling system 4, a temperature detection unit 5, and a controller 6.

[0026] The supercritical carbon dioxide turbine 1 includes a turbine casing and a turbine hot end located inside the turbine casing. During operation, the turbine hot end is in a high-temperature and high-pressure environment, and heat is transferred to the shaft end through the high-temperature working fluid, the turbine casing, and the sealing shell.

[0027] The dry gas seal assembly 2 is located at the shaft end of the supercritical carbon dioxide turbine 1. The dry gas seal assembly 2 includes a dry gas seal body, a seal housing, and a seal cavity. The dry gas seal body is installed inside the seal housing, and the seal cavity is formed around the dry gas seal body. At least a portion of the seal cavity is located between the dry gas seal body and the hot end of the turbine, serving to block heat transfer.

[0028] The water-cooling system 3 is used to cool external structures such as the turbine casing and sealing housing. In this embodiment, the water-cooling system 3 includes a water pump, cooling water pipes, a water-cooling channel, and a water flow regulating device. The water-cooling channel is specifically located inside the turbine casing and / or the sealing housing. During operation, cooling water flows through the water-cooling channel driven by the water pump, carrying away heat from the external structures, thereby reducing the temperature of the turbine casing and sealing housing. The controller 6 can change the flow rate of the cooling water by adjusting the speed of the water pump or the opening of the water flow regulating device.

[0029] The CO2 thermal insulation cooling system 4 is used to supply low-temperature CO2 cooling gas to the sealing cavity. This system includes a CO2 compression system, a CO2 cooling gas supply pipeline, and a CO2 regulating valve. The CO2 cooling gas supply pipeline is connected to the sealing cavity, and the CO2 gas inlet is preferably located on the side of the dry gas sealing body closer to the turbine hot end. The CO2 compression system supplies gas stably according to a preset supply pressure, so that after the low-temperature CO2 enters the sealing cavity, a thermal insulation cooling gas flow is formed between the turbine hot end and the dry gas sealing body. This gas flow not only hinders the convective heat transfer from the high-temperature working fluid at the turbine hot end to the dry gas sealing body, but also removes heat from the dry gas sealing body and the sealing cavity. The controller 6 changes the flow rate of the CO2 cooling gas by adjusting the opening of the CO2 regulating valve or the supply volume of the CO2 compression system.

[0030] The temperature detection unit 5 is used to detect the temperature of the dry gas seal body and the external structure in real time. Specifically, the detection position for the dry gas seal body temperature is set near the dry gas seal body, the sealing end face, or inside the sealing cavity to reflect the thermal state of the internal cooling object; the detection position for the external structure temperature is set on the turbine casing and / or the sealing shell to reflect the thermal state of the external cooling object; the external structure temperature can be the higher value of the turbine casing temperature and the sealing shell temperature, or a combined external structure temperature can be determined based on the temperatures at both locations. In addition, the temperature detection unit 5 can also detect parameters such as cooling water temperature, CO2 cooling gas temperature, cooling water flow rate, and CO2 cooling gas flow rate.

[0031] The controller 6 is communicatively connected to the water-cooling system 3, the CO2 insulation cooling system 4, and the temperature detection unit 5. The controller 6 has pre-stored control programs and preset thresholds, including the allowable temperature range of the dry gas seal body, the allowable temperature range of the external structure, the allowable temperature difference between the inside and outside, the cooling water flow rate adjustment range, and the CO2 cooling gas flow rate adjustment range. Based on the dry gas seal body temperature, the external structure temperature, and the temperature difference between them, the controller 6 adjusts the cooling water flow rate of the water-cooling system 3 and the CO2 cooling gas flow rate of the CO2 insulation cooling system 4, respectively, executing coordinated cooling control logic.

[0032] Based on the above system, this embodiment also provides a method for supercritical carbon dioxide turbine dry gas seal-based synergistic thermal insulation cooling based on internal and external temperature difference control, the control process of which is as follows: Figure 2 As shown, the specific steps are as follows: Step S1: Collect temperature parameters Temperature detection unit 5 collects the temperature T of the dry gas seal body in real time. i and external structural temperature T o The data is then transmitted to controller 6.

[0033] Step S2: Calculate the temperature difference between inside and outside. Controller 6 calculates the temperature based on the received temperature data using the formula ΔT=T i -T o Calculate the internal and external temperature difference between the dry gas seal body and the external structure.

[0034] Step S3: Determine the running status Controller 6 retrieves preset thresholds and determines T respectively. i Is it within the allowable temperature range of the dry gas seal body? (T) o Whether it is within the allowable temperature range of the external structure, and whether ΔT is within the allowable temperature difference range between the inside and outside.

[0035] Step S4: Determine the cooling regulation method Controller 6 according to T i T o The specific numerical values ​​of ΔT determine the direction of adjustment for cooling water flow rate and CO2 cooling airflow. Specific adjustment strategies include the following operating conditions: Normal operating condition: If T i T o ΔT is within the allowable range, indicating that the current cooling capacity meets the requirements. The water cooling system 3 and the CO2 insulation cooling system 4 are operating stably according to the basic flow rate, and the controller 6 continuously monitors the data.

[0036] The temperature of the dry gas seal body is too high: if only T i Exceeding the internal temperature control limit, and T oIf the flow rate is within the allowable range, it indicates insufficient internal insulation or cooling. In this case, controller 6 prioritizes increasing the CO2 cooling gas supply flow rate to enhance the heat insulation and cooling airflow within the sealing cavity, thereby reducing the temperature of the dry gas seal body; the cooling water flow rate remains unchanged or is only slightly adjusted.

[0037] The external structure temperature is too high: if only T o Exceeding the external temperature control limit, and T i If the flow rate is within the acceptable range, it indicates insufficient cooling of the external structure. In this case, controller 6 prioritizes increasing the cooling water flow rate; the CO2 cooling gas flow rate remains at its current level.

[0038] Both internal and external temperatures are high: if T i T o If the temperature exceeds the corresponding upper limit of the control range, and ΔT is within the allowable range, controller 6 will simultaneously increase the cooling water flow rate and the CO2 cooling gas flow rate. The adjustment amount of the cooling water flow rate is determined based on the temperature deviation of the external structure, and the adjustment amount of the CO2 cooling gas flow rate is determined based on the temperature deviation of the dry gas seal body.

[0039] The dry gas seal body temperature is high and the temperature difference exceeds the limit: when T i >T o When ΔT exceeds the upper limit of the allowable value, it indicates that the external structure has been strongly cooled, while the internal area is still affected by the hot end. At this time, the controller 6 increases the CO2 cooling gas flow rate to enhance the heat insulation cooling airflow of the sealed cavity, while limiting the cooling water flow rate to continue to increase, or appropriately reducing the cooling water flow rate to prevent the increase of thermal deformation stress caused by external overcooling.

[0040] The external structure temperature is high and the temperature difference exceeds the limit: when T o >T i When ΔT exceeds the upper limit of the allowable value, controller 6 increases the cooling water flow rate and maintains or limits the CO2 cooling gas flow rate.

[0041] Step S5: Coordinated Execution Adjustment According to the determined adjustment method, controller 6 drives the water pump, water flow regulating device, CO2 regulating valve, and CO2 compression system to complete the corresponding flow regulation. Low-temperature CO2 continuously forms a heat-insulating cooling airflow between the turbine hot end and the dry gas seal body, working together with the water cooling system to maintain temperature stability.

[0042] Step S6: Loop Monitoring During the adjustment process, the system continuously collects T data in real time. i T o Repeat steps S2-S5 to dynamically adjust the cooling medium flow rate until all temperature parameters return to the allowable range.

[0043] Step S7: Anomaly Protection Determination If both the cooling water flow rate and the CO2 cooling gas flow rate reach their maximum adjustment limits, but T i or T o If the load still exceeds the safety threshold, controller 6 will trigger an audible and visual alarm and send a load reduction or shutdown protection command to the supercritical carbon dioxide turbine to prevent equipment damage.

[0044] Through the above embodiments, the present invention achieves the synergistic effect of water cooling and CO2 thermal insulation cooling. Based on the thermal state difference between the dry gas seal body and the external structure, the cooling capacity is rationally allocated, effectively controlling the internal and external temperature difference, avoiding the problem of uneven temperature caused by a single cooling method, and improving the reliability of dry gas seal operation.

[0045] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0046] In the description of this application, it should be understood that the terms "upper" and "lower" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

Claims

1. A supercritical carbon dioxide turbine dry gas seal synergistic thermal insulation cooling system based on internal and external temperature difference control, characterized in that, include: A supercritical carbon dioxide turbine (1) includes a turbine casing and a turbine hot end located inside the turbine casing. Dry gas sealing assembly (2), the dry gas sealing assembly (2) is disposed at the shaft end of the supercritical carbon dioxide turbine (1), the dry gas sealing assembly (2) includes a dry gas sealing body, a sealing housing and a sealing cavity, the dry gas sealing body is installed in the sealing housing, and at least a portion of the sealing cavity is located between the dry gas sealing body and the turbine hot end; Water cooling system (3), the water cooling system (3) is used to cool the turbine casing and the sealing housing; CO2 thermal insulation cooling system (4), the CO2 thermal insulation cooling system (4) is used to deliver low temperature CO2 cooling gas to the sealing cavity, so that low temperature CO2 forms a thermal insulation cooling airflow between the turbine hot end and the dry gas sealing body; Temperature detection unit (5), the temperature detection unit (5) is used to detect the temperature of the dry gas seal body and the temperature of the external structure; The controller (6) is connected to the water cooling system (3), the CO2 heat insulation cooling system (4) and the temperature detection unit (5) respectively. Based on the temperature of the dry gas seal body, the temperature of the external structure and the temperature difference between the two, the controller (6) adjusts the cooling water flow rate of the water cooling system (3) and the CO2 cooling gas flow rate of the CO2 heat insulation cooling system (4).

2. The supercritical carbon dioxide turbine dry gas seal synergistic thermal insulation cooling system based on internal and external temperature difference control according to claim 1, characterized in that, The water cooling system (3) includes a water pump, cooling water pipeline, water cooling channel and water flow regulating device. The water cooling channel is set in the turbine casing and / or sealed housing. The cooling water is driven by the water pump to flow through the water cooling channel to carry away the heat of the external structure. The controller (6) changes the cooling water flow rate by adjusting the water pump speed or the opening of the water flow rate regulating device.

3. The supercritical carbon dioxide turbine dry gas seal synergistic thermal insulation cooling system based on internal and external temperature difference control according to claim 1, characterized in that, The CO2 heat insulation and cooling system (4) includes a CO2 compression system, a CO2 cooling gas supply pipeline and a CO2 regulating valve; the CO2 cooling gas supply pipeline is connected to the sealing cavity, and the CO2 gas supply port is located on the side of the dry gas sealing body near the hot end of the turbine; the CO2 compression system supplies gas stably at a preset gas supply pressure to maintain the heat insulation and cooling airflow. The controller (6) changes the CO2 cooling gas flow rate by adjusting the opening of the CO2 regulating valve or the gas supply of the CO2 compression system.

4. The supercritical carbon dioxide turbine dry gas seal synergistic thermal insulation cooling system based on internal and external temperature difference control according to claim 1, characterized in that, The temperature detection location for the dry gas seal body is set near the dry gas seal body, the sealing end face, or inside the sealing cavity; the temperature detection location for the external structure is set at the turbine casing and / or the sealing housing.

5. The supercritical carbon dioxide turbine dry gas seal synergistic thermal insulation cooling system based on internal and external temperature difference control according to claim 1, characterized in that, The temperature detection unit can also detect the cooling water temperature, CO2 cooling gas temperature, cooling water flow rate, and CO2 cooling gas flow rate.

6. The supercritical carbon dioxide turbine dry gas seal synergistic thermal insulation cooling system based on internal and external temperature difference control according to claim 1, characterized in that, The controller (6) is pre-set with the allowable range of dry gas seal body temperature, allowable range of external structure temperature, allowable range of internal and external temperature difference, cooling water flow rate adjustment range, and CO2 cooling gas flow rate adjustment range.

7. A supercritical carbon dioxide turbine dry gas seal synergistic thermal insulation cooling system based on internal and external temperature difference control according to claim 6, characterized in that, The controller (6) is configured to perform the following adjustment: When the temperature of the dry gas seal body, the temperature of the external structure and the temperature difference between the inside and outside are all within the allowable range, the water cooling system and the CO2 heat insulation cooling system operate according to the basic flow rate, and the controller (6) continuously collects temperature data. When the temperature of the dry gas seal body exceeds the internal temperature control value and the external structure temperature is within the allowable range, the controller (6) increases the CO2 cooling gas flow rate, while the cooling water flow rate remains unchanged or is slightly adjusted. When the external structure temperature exceeds the external temperature control value and the dry gas seal body temperature is within the allowable range, the controller (6) increases the cooling water flow rate while the CO2 cooling gas flow rate remains at its current state. When the temperature of the dry gas seal body and the temperature of the external structure both exceed the corresponding control value, and the temperature difference between the inside and outside is within the allowable range, the controller (6) simultaneously increases the cooling water flow rate and the CO2 cooling gas flow rate; the adjustment amount of the cooling water flow rate is determined according to the temperature deviation of the external structure, and the adjustment amount of the CO2 cooling gas flow rate is determined according to the temperature deviation of the dry gas seal body. When the temperature of the dry gas sealing body is higher than the temperature of the external structure and the temperature difference between the two exceeds the preset temperature difference allowable range, the controller (6) increases the CO2 cooling gas flow rate and limits the cooling water flow rate from continuing to increase; When the temperature of the external structure is higher than the temperature of the dry gas seal body and the temperature difference between the two exceeds a preset value, the controller (6) increases the cooling water flow rate and maintains or limits the CO2 cooling gas flow rate. When both the cooling water flow rate and the CO2 cooling gas flow rate reach the upper limit of adjustment, and the temperature of the dry gas seal body or the temperature of the external structure still exceeds the safe value, the controller (6) issues an alarm and performs turbine load reduction or shutdown protection.

8. A method for synergistic thermal insulation cooling of supercritical carbon dioxide turbine dry gas seal based on internal and external temperature difference control, characterized in that, Includes the following steps: Step S1: Collect temperature parameters. The temperature T of the dry gas seal body is collected in real time through the temperature detection unit. i External structural temperature T o ; Step S2: Calculate the internal and external temperature difference. The controller uses the formula ΔT=T i -T o Calculate the internal and external temperature difference between the dry gas seal body and the external structure; Step S3: Determine the operating status. The controller retrieves preset thresholds and determines T respectively. i T o Whether ΔT falls within their respective allowable ranges; Step S4: Determine the cooling adjustment method, based on T i T o ΔT determines the adjustment direction of cooling water flow rate and CO2 cooling airflow rate; Step S5: Coordinated execution adjustment, the controller drives the water pump, water flow adjustment device, CO2 regulating valve and CO2 compression system to complete the corresponding flow adjustment, and low temperature CO2 continuously forms a heat insulation cooling airflow between the turbine hot end and the dry gas seal body; Step S6: Cyclic monitoring, continuously collecting T data in real time during the adjustment process. i T o Then repeat steps S2-S5 to dynamically correct the cooling medium flow rate.

9. A method for supercritical carbon dioxide turbine dry gas seal synergistic thermal insulation cooling based on internal and external temperature difference control, as described in claim 8, is characterized in that... The cooling adjustment methods in step S4 include: If T i T o ΔT is within the allowable range, and the water cooling system and CO2 insulation cooling system maintain stable basic flow rate operation; If only T i Exceeding the upper limit of internal temperature, T o Within permissible limits, prioritize increasing the CO2 cooling gas supply flow rate, while keeping the cooling water flow rate unchanged or slightly adjusted. If only T o Exceeding the upper limit of external temperature, T i Within permissible limits, prioritize increasing cooling water flow rate, while maintaining the current CO2 cooling gas flow rate. If T i T o When the temperature exceeds the corresponding upper limit and ΔT is within the allowable range, the cooling water flow rate and CO2 cooling gas flow rate are adjusted simultaneously. The flow rate adjustment of the two types of media are matched to the external temperature deviation and the dry gas seal body temperature deviation, respectively. If T i >T o Furthermore, if ΔT exceeds the upper limit of the allowable value, increase the CO2 cooling gas flow rate to enhance the heat insulation cooling airflow of the sealed cavity, while limiting the cooling water flow rate to continue to increase or appropriately reducing the cooling water flow rate; If T o >T i Furthermore, if ΔT exceeds the upper limit of the allowable value, the cooling water flow rate will be increased, while the CO2 cooling gas flow rate will be maintained or limited.

10. A method for supercritical carbon dioxide turbine dry gas seal synergistic thermal insulation cooling based on internal and external temperature difference control, as described in claim 8, is characterized in that... It also includes step S7: abnormal protection determination. When both the cooling water flow rate and the CO2 cooling gas flow rate reach the maximum adjustment limit, T i or T o If the load still exceeds the safety threshold, the controller triggers an audible and visual alarm and issues a load reduction or shutdown protection command to the supercritical carbon dioxide turbine.

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