Zero-leakage dry gas seal device and method for supercritical carbon dioxide

Abstract

A zero-leakage dry gas seal device and method for supercritical carbon dioxide, relating to the field of seal device structures, and aiming to solve the technical problem that the excessively high temperature of existing barrier gas outlets impacts the oil temperature of bearings in gear boxes. The dry gas seal device comprises a main gas flow path (13), a primary gas flow branch (8), a barrier gas flow branch (6), a pressure reducing valve (10), and a temperature control assembly; one end of the primary gas flow branch (8) is communicated with the main gas flow path (13) and a seal cylinder (3); the barrier gas flow branch (6) is communicated with the main gas flow path (13) and a gear box (1); the pressure reducing valve (10) is arranged on the barrier gas flow branch (6); and the temperature control assembly is used for controlling the temperature of gas injection flow on the basis of the gas flow pressure of the gas injection flow introduced into the main gas flow path (13), so that the temperature of leakage gas flow of the dry gas seal device, the temperature of gas flow at an outlet of the barrier gas flow branch (6), and the oil inlet temperature of a bearing in the gear box (1) are matched, thereby effectively reducing the impact on the oil inlet temperature of the bearing in the gear box when introducing the gas injection flow.

Description

Supercritical carbon dioxide zero-leakage dry gas sealing device and method

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on February 5, 2024, with application number 2024101624114 and application name “A Supercritical Carbon Dioxide Zero-Leakage Dry Gas Sealing Device and Method”, the entire contents of which are incorporated by reference into the application. Technical Field

[0002] The present application relates to the field of sealing device structures, and in particular to a supercritical carbon dioxide zero-leakage dry gas sealing device and method. Background Art

[0003] The dry gas seal is the shaft sealing device for supercritical CO2 compressors or turbines and is crucial for ensuring efficient operation. It consists of a seal cylinder, a dynamic ring, a static ring, and supporting auxiliary springs, spring seats, and a shaft sleeve. To ensure safe operation of the dry gas seal, a dry gas seal barrier gas is required to effectively isolate the oil and gas in the downstream gearbox.

[0004] At present, the isolation gas usually uses carbon dioxide as the working fluid. In order to make the compressor or turbine structure compact and not introduce additional auxiliary boosting devices (including boosting pumps, storage tanks, heaters, etc.), the main gas system of the supercritical carbon dioxide compressor or turbine is usually extracted to serve as the gas source for the isolation gas. However, the pressure of the carbon dioxide working fluid in the main gas system is usually 6-20MPa, and the pressure of the isolation gas reaching the outlet after decompression is often slightly positive. Therefore, under the condition of large pressure difference, the temperature change of the isolation gas outlet airflow increases accordingly, so that the temperature difference between the isolation gas outlet airflow and the bearing oil inlet temperature in the gearbox becomes larger, which in turn affects the bearing oil inlet temperature in the gearbox. The bearing oil inlet temperature in the gearbox downstream of the isolation gas outlet needs to be within a certain temperature range to ensure the efficient operation of the rotating shaft bearing. Therefore, when the isolation gas is currently introduced, the temperature difference of the isolation gas outlet temperature is too large, which will have a greater impact on the gearbox bearings, thereby affecting the safe operation of the supercritical carbon dioxide compressor or turbine.

[0005] Application Contents

[0006] The main purpose of this application is to provide a supercritical carbon dioxide zero-leakage dry gas sealing device and method, aiming to solve the technical problem that the existing isolation gas outlet temperature is too high and affects the oil temperature of the gearbox bearing.

[0007] To achieve the above objectives, the present application provides a supercritical carbon dioxide zero-leakage dry gas sealing device, comprising a sealing cylinder and a dynamic ring and a static ring disposed inside the sealing cylinder, the dry gas sealing device further comprising:

[0008] A total air flow path, used to introduce an injection air flow into the sealing cylinder and the gear box; a main air flow branch, one end of the main air flow branch is connected to the total air flow path, and the other end of the main air flow branch is connected to the sealing cylinder; an isolation air flow branch, one end of the isolation air flow branch is connected to the total air flow path, and the other end of the isolation air flow branch is connected to the gear box, and the isolation air flow branch is connected in parallel with the main air flow branch; a pressure reducing valve, the pressure reducing valve is arranged on the isolation air flow branch; and a temperature control component, used to control the temperature of the injection air flow based on the air flow pressure of the injection air flow introduced into the total air flow path, so that the temperature of the leakage air flow of the dry gas sealing device, the temperature of the outlet air flow of the isolation air flow branch and the bearing oil inlet temperature in the gear box are adapted.

[0009] Optionally, an air injection hole is provided on the sealing cylinder, the air injection hole is located on a side of the dynamic ring facing away from the gear box, and the air injection hole is connected to the main air flow branch.

[0010] Optionally, the dry gas sealing device further includes a pressure reducing structure for sharing the pressure drop requirement borne by the pressure reducing valve.

[0011] Optionally, the pressure reducing structure includes a resistance member and a throttle hole, the resistance member is arranged on a side of the pressure reducing valve close to the total air flow path, and the throttle hole is arranged on a side of the pressure reducing valve away from the total air flow path.

[0012] Optionally, a pressure regulating groove is provided on a side of the gear box close to the sealing cylinder, and the pressure regulating groove is connected to the isolation airflow branch.

[0013] Optionally, the resistance member has a plurality of first protruding expansion portions, and the plurality of first protruding expansion portions are connected in series.

[0014] Optionally, the pressure regulating groove has a plurality of second protruding expansion portions, and the plurality of second protruding expansion portions are connected in series, and the plurality of second protruding expansion portions are arranged in a symmetrical or staggered manner.

[0015] To achieve the above objectives, the present application also provides a supercritical carbon dioxide zero-leakage dry gas sealing method, which uses the supercritical carbon dioxide zero-leakage dry gas sealing device as described above to control the temperature of the introduced injection gas flow.

[0016] Optionally, the air flow pressure of the air injection air flow introduced into the total air flow path is 6 MPa-20 MPa.

[0017] Optionally, the relationship between the airflow pressure and temperature of the air injection airflow introduced into the total airflow path is as follows: min =-0.0032P 3 +0.0041P 2+6.0759P+42.262; T max =0.0118P 3 -0.5304P 2 +11.581P+48.113;

[0018] Among them, T min is the lowest temperature of the injected gas flow; T max is the maximum temperature of the introduced gas injection flow; P is the gas flow pressure of the introduced gas injection flow.

[0019] Beneficial effects that this application can achieve:

[0020] A supercritical carbon dioxide zero-leakage dry gas sealing device proposed in an embodiment of the present application includes a sealing cylinder and a dynamic ring and a static ring arranged inside the sealing cylinder. The dry gas sealing device also includes a total air flow path, a main air flow branch, an isolation air flow branch, a pressure reducing valve and a temperature control component. When the dry gas sealing device is working, an injection air flow will be introduced into the total air flow path, and the injection air flow will then be divided into two paths. One injection air flow enters the sealing cylinder through the main air flow branch, and the other injection air flow enters the gear box through the isolation air flow branch. At the same time, the air flow in the isolation air flow branch is decompressed by the pressure reducing valve. In addition, during the operation of the dry gas sealing device, the temperature of the injection air flow introduced into the total air flow path is controlled by the temperature control component, so that the temperature of the leakage air flow of the dry gas sealing device and the temperature of the outlet air flow of the isolation air flow branch are adapted to the bearing oil inlet temperature in the gear box, that is, the leakage air flow of the dry gas sealing device and the outlet air flow of the isolation air flow branch will not excessively affect the bearing oil inlet temperature in the gear box, effectively reducing the impact of the injection air flow on the bearing oil inlet temperature in the gear box when the injection air flow is introduced, thereby ensuring the safe operation of the supercritical carbon dioxide compressor or turbine. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG1 is a schematic structural diagram of a supercritical carbon dioxide zero-leakage dry gas sealing device according to an embodiment of the present application, wherein the second protruding and enlarged parts are arranged in a symmetrical manner;

[0022] FIG2 is a partial enlarged schematic diagram of point A in FIG1 ;

[0023] FIG3 is a schematic structural diagram of a supercritical carbon dioxide zero-leakage dry gas sealing device according to an embodiment of the present application when the second protruding expansion portion is arranged in a staggered manner;

[0024] FIG4 is a partial enlarged schematic diagram of point B in FIG2 .

[0025] Among them, the accompanying drawings are marked as follows: 1-gearbox; 2-spring; 3-sealing cylinder; 4-dynamic ring; 5-static ring; 6-isolation air flow branch; 7-air injection hole; 8-main air flow branch; 9-throttle hole; 10-pressure reducing valve; 11-resistance member; 12-pressure regulating groove; 13-total air flow path; 14-first sudden expansion part; 15-second sudden expansion part.

[0026] The realization of the objectives, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0028] It should be noted that all directional indications in the embodiments of the present application (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0029] In this application, unless otherwise specified or limited, the terms "connection" and "fixation" should be understood in a broad sense. For example, "fixation" can mean fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. For those skilled in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0030] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present application, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the meaning of "and / or" appearing throughout the text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme in which A and B are satisfied at the same time. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement it. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0031] Analysis revealed that due to the narrow flow gap between the dynamic and static rings, it is important to manage impurities in the dry gas seal to prevent wear on the dynamic and static rings, which could lead to dry gas seal failure. For example, oil and gas from the downstream gearbox could cross-contaminate the sealing surfaces of the dynamic and static rings. Therefore, to ensure the safe operation of the dry gas seal, a dry gas seal isolation gas is required to effectively isolate the oil and gas in the downstream gearbox. Compressed air is typically used as the source of this dry gas seal isolation gas in scenarios where external leakage is permitted. However, in zero-leakage loop scenarios, introducing external air reduces the purity of the supercritical carbon dioxide (SCCO) working fluid, rendering the SCCO purity substandard. Therefore, SCCO also needs to be used as the isolation gas. To achieve a compact compressor or turbine structure and eliminate the need for additional auxiliary boosting devices (including booster pumps, storage tanks, heaters, etc.), the isolation gas source is typically extracted from the main gas system of the SCCO compressor or turbine. However, the CO2 working fluid pressure in the main gas system is typically 6-20 MPa, while the outlet pressure of the barrier gas after decompression is often slightly positive. Therefore, under conditions of large pressure differentials, the temperature variation of the barrier gas outlet airflow increases, and the temperature difference between the barrier gas outlet airflow and the bearing oil inlet temperature in the gearbox increases, which in turn affects the bearing oil inlet temperature in the gearbox. The bearing oil inlet temperature in the gearbox downstream of the barrier gas outlet must be within a certain temperature range to ensure the efficient operation of the shaft bearing. Therefore, when introducing barrier gas, a large temperature difference at the barrier gas outlet can have a significant impact on the gearbox bearings, thereby affecting the safe operation of the supercritical CO2 compressor or turbine.

[0032] Therefore, it is necessary to control the outlet temperature of the isolation gas under large pressure difference to reduce the impact of the isolation gas on the bearing oil inlet temperature in the gearbox.

[0033] 1 , an embodiment of the present application provides a supercritical carbon dioxide zero-leakage dry gas sealing device, comprising a sealing cylinder 3 and a dynamic ring 4 and a static ring 5 arranged inside the sealing cylinder 3 , a total air flow path 13 , a main air flow branch 8 , an isolation air flow branch 6 , a pressure reducing valve 10 and a temperature control assembly.

[0034] As known from the prior art, a spring 2 is typically installed on the side of the stationary ring 5 facing away from the dynamic ring 4 to exert a contact force, ensuring close contact between the dynamic and static rings 5 ​​under static conditions. During dry gas seal operation, the dynamic and static rings 4 and 5 cooperate, and the gas injection flow from the main gas flow path 13 forms a rigid air film between the dynamic and static rings 4 and 5. When the static pressure of the fluid and the closing force of the spring 2 load equal the opening force generated within the air film, a stable gap is formed between the radial surfaces.

[0035] The total air flow path 13 is used to introduce the injection air flow into the sealing cylinder 3 and the gear box 1. One end of the total air flow path 13 serves as the input end of the injection air flow. The injection air flow is input through the port of the total air flow path 13, and after flowing through the total air flow path 13, it flows to the main air flow branch 8 and the isolation air flow branch 6 respectively, and is used to introduce the injection air flow into the sealing cylinder 3 and the gear box 1 respectively.

[0036] The main airflow branch 8 is used to introduce an injection airflow into the sealing cylinder 3. One end of the main airflow branch 8 is connected to the main airflow path 13, and the other end of the main airflow branch 8 is connected to the sealing cylinder 3. The injection airflow flows through the main airflow branch 8 and then flows into the sealing cylinder 3, forming a rigid air film between the dynamic ring 4 and the static ring 5.

[0037] Isolation airflow branch 6 is used to introduce an injection airflow into gearbox 1. One end of isolation airflow branch 6 is connected to main airflow path 13, and the other end of isolation airflow branch 6 is connected to gearbox 1. Isolation airflow branch 6 is connected in parallel with main airflow branch 8. After passing through isolation airflow branch 6, the injection airflow flows into gearbox 1, thereby isolating the oil and gas.

[0038] The pressure reducing valve 10 is provided on the isolation airflow branch 6 and is used to reduce the pressure of the isolation air in the isolation airflow branch 6 so as to achieve a slightly positive pressure of the airflow at the outlet of the isolation airflow branch 6 .

[0039] The temperature control component is used to control the temperature of the injection air flow based on the air flow pressure of the injection air flow introduced into the total air flow path 13, so that the temperature of the leakage air flow of the dry gas sealing device, the temperature of the outlet air flow of the isolation air flow branch 6 and the bearing oil inlet temperature in the gearbox 1 are adapted.

[0040] It is understood that a zero-leakage dry gas seal device refers to a dry gas seal that is directly and hermetically connected to the gearbox 1. Therefore, when considering the impact on the bearing oil inlet temperature in the gearbox 1, it is necessary to take into account the temperature changes of the leakage airflow of the dry gas seal device. The temperature of the leakage airflow of the dry gas seal device is basically consistent with the temperature of the outlet airflow of the isolation airflow branch 6. Therefore, by controlling the temperature of the injection airflow introduced into the total airflow path 13, the temperature of the leakage airflow of the dry gas seal device and the temperature of the outlet airflow of the isolation airflow branch 6 are adapted to the bearing oil inlet temperature in the gearbox 1.

[0041] Specifically, when the injection airflow is introduced into the total airflow path 13, the airflow pressure and temperature of the injection airflow are controlled so that the temperature of the leakage airflow of the dry gas sealing device and the temperature of the outlet airflow of the isolation airflow branch 6 are adapted to the bearing oil inlet temperature in the gearbox 1, thereby reducing the pressure difference between the leakage airflow formed after the injection airflow flows from the main airflow branch 8 into the dry gas sealing device and the outlet airflow of the injection airflow from the isolation airflow branch 6 into the gearbox 1, thereby effectively reducing the influence of the introduction of the injection airflow on the bearing oil inlet temperature in the gearbox 1. Among them, making the temperature of the leakage airflow of the dry gas sealing device and the temperature of the outlet airflow of the isolation airflow branch 6 adapted to the bearing oil inlet temperature in the gearbox 1 means making the temperature of the leakage airflow of the dry gas sealing device and the temperature of the outlet airflow of the isolation airflow branch 6 close to the bearing oil inlet temperature in the gearbox 1.

[0042] The supercritical carbon dioxide zero-leakage dry gas sealing device proposed in the above embodiment includes a sealing cylinder 3 and a dynamic ring 4 and a static ring 5 arranged inside the sealing cylinder 3. The dry gas sealing device also includes a total air flow path 13, a main air flow branch 8, an isolation air flow branch 6, a pressure reducing valve 10 and a temperature control component. When the dry gas sealing device is working, an injection air flow will be introduced into the total air flow path 13, and the injection air flow will then be divided into two paths. One injection air flow enters the sealing cylinder 3 through the main air flow branch 8, and the other injection air flow enters the gear box 1 through the isolation air flow branch 6. At the same time, the air flow in the isolation air flow branch 6 is decompressed by the pressure reducing valve 10. In addition, during the operation of the dry gas sealing device, the temperature of the injection air flow introduced into the total air flow path 13 is controlled by the temperature control component, so that the temperature of the leakage air flow of the dry gas sealing device and the temperature of the outlet air flow of the isolation air flow branch 6 are adapted to the bearing oil inlet temperature in the gear box 1, that is, the leakage air flow of the dry gas sealing device and the outlet air flow of the isolation air flow branch 6 will not excessively affect the bearing oil inlet temperature in the gear box 1, effectively reducing the influence on the bearing oil inlet temperature in the gear box 1 when the injection air flow is introduced, thereby ensuring the safe operation of the supercritical carbon dioxide compressor or turbine.

[0043] As an optional embodiment, referring to Figures 1 and 2, an air injection hole 7 is formed in the sealing cylinder 3. The air injection hole 7 is located on the side of the dynamic ring 4 facing away from the gearbox 1 and is connected to the main air flow branch 8. After flowing through the main air flow branch 8, the air injection air flows from the air injection hole 7 into the sealing cylinder 3, forming a rigid air film between the dynamic ring 4 and the static ring 5.

[0044] The principle for distributing the pressure drop in the isolated airflow branch 6 is that the minimum isentropic expansion temperature at the throat of the pressure reducing valve 10 is higher than zero degrees Celsius. When the temperature at the throat of the pressure reducing valve 10 is lower than zero degrees Celsius, moisture in the external air working fluid will cause frost to form on the valve stem surface of the pressure reducing valve 10, which may cause the pressure reducing valve 10 to become stuck and difficult to automatically control. Therefore, in order to prevent the minimum isentropic expansion temperature at the throat of the pressure reducing valve 10 from being lower than or equal to zero degrees Celsius, it is necessary to limit the front-to-rear pressure difference of the pressure reducing valve 10. Optionally, the dry gas sealing device also includes a pressure reducing structure for sharing the pressure drop requirement borne by the pressure reducing valve 10.

[0045] In this embodiment, the pressure reducing structure is used to share the pressure drop requirement borne by the pressure reducing valve 10, that is, by arranging the pressure reducing structure on the isolation airflow branch 6, the isolation airflow branch 6 can be gradually reduced in pressure, and the throat of the pressure reducing valve 10 can be prevented from frosting, thereby effectively sharing the large pressure drop requirement borne by the pressure reducing valve 10, and providing support for the design and safe operation of the supercritical carbon dioxide compressor or turbine.

[0046] In some embodiments, the pressure difference before and after the pressure reducing valve 10 does not exceed 9-11 MPa, and the remaining pressure drop requirement is borne by the pressure reducing structure.

[0047] As an optional embodiment, referring to Figures 1 and 2, the pressure reducing structure includes a resistance member 11 and a throttle hole 9, the resistance member 11 is arranged on the side of the pressure reducing valve 10 close to the total air flow path 13, and the throttle hole 9 is arranged on the side of the pressure reducing valve 10 away from the total air flow path 13.

[0048] In this embodiment, the resistance member 11 is arranged on the side of the pressure reducing valve 10 close to the total air flow path 13, and the throttle hole 9 is arranged on the side of the pressure reducing valve 10 away from the total air flow path 13, that is, the pressure reducing valve 10 is located between the resistance member 11 and the throttle hole 9. After the injection air flow enters the isolation air flow branch 6 from the total air flow path 13, it flows through the resistance member 11, the pressure reducing valve 10 and the throttle hole 9 in sequence to achieve step-by-step pressure reduction.

[0049] As an optional embodiment, referring to FIG. 1 and FIG. 2 , a pressure regulating groove 12 is opened on one side of the gear box 1 close to the sealing cylinder 3 , and the pressure regulating groove 12 is connected to the isolation airflow branch 6 .

[0050] In this embodiment, the isolation airflow branch 6 is connected to the gearbox 1 through the pressure regulating groove 12, so that the injection airflow flows into the gearbox 1 through the pressure regulating groove 12 to achieve the effect of oil and gas isolation.

[0051] To effectively share the significant pressure drop of the pressure reducing valve 10, the resistance element 11, located upstream of the pressure reducing valve 10, needs to bear a relatively large pressure drop. Therefore, referring to Figures 1 and 2, the resistance element 11 has a plurality of first flared portions 14, which are connected in series. Because the temperature and pressure upstream of the resistance element 11 are relatively high, the resistance element 11 adopts a multi-stage series structure with equal diameters and gradually staggered flared portions, allowing it to withstand a pressure differential that is approximately 1 / 3-2 / 3 of the pressure differential borne by the pressure reducing valve 10.

[0052] Specifically, the resistance member 11 may include several first protruding expansion parts 14 and connecting tubes, the diameter of the first protruding expansion part 14 is larger than the diameter of the connecting tube, and the diameter of the connecting tube is greater than or equal to the diameter of the isolated airflow branch 6, and the first protruding expansion part 14 and the connecting tube are staggered to form a structure with multiple protruding expansion parts.

[0053] At the same time, in order to further increase the front and rear pressure difference of the pressure regulating groove 12, referring to Figures 1 to 4, the pressure regulating groove 12 has a plurality of second protruding expansion parts 15, and the plurality of second protruding expansion parts 15 are connected in series, and the second protruding expansion parts 15 are arranged in a symmetrical or staggered manner.

[0054] In this embodiment, when the second protruding expansions 15 are arranged symmetrically, that is, they are symmetrical about the mid-vertical plane, they can facilitate the flow of gas injection and also effectively increase the pressure differential across the pressure-surge tank 12. When the second protruding expansions 15 are arranged in a staggered manner, that is, due to the size constraints of the gearbox 1, the overall airflow length of the pressure-surge tank 12 is limited. However, the staggered arrangement of the second protruding expansions 15 can increase the number of protruding expansion structures within this limited airflow length, thereby further increasing the pressure differential across the pressure-surge tank 12 to meet greater pressure differential requirements and thus be suitable for a wider range of applications.

[0055] Specifically, the pressure regulating groove 12 may include several second protruding expansion parts 15 and connecting groove bodies. The diameter of the second protruding expansion parts 15 is larger than the diameter of the connecting groove body. The second protruding expansion parts 15 and the connecting groove body are staggered to form a structure with multiple protruding expansion parts.

[0056] The embodiments of the present application also provide a supercritical carbon dioxide zero-leakage dry gas sealing method, which uses the supercritical carbon dioxide zero-leakage dry gas sealing device described in the above embodiments to control the temperature of the introduced injection gas flow.

[0057] Specifically, the supercritical carbon dioxide zero-leakage dry gas sealing method includes:

[0058] Before introducing the injection air flow into the total air flow path 13, the temperature control component adjusts the temperature of the introduced injection air flow based on the air flow pressure of the injection air flow, controls the temperature of the introduced injection air flow within a preset range, and then introduces the injection air flow into the sealing cylinder 3 and the gear box 1 through the total air flow path 13, so that the temperature of the leakage air flow of the dry gas sealing device and the temperature of the outlet air flow of the isolation air flow branch 6 are adapted to the bearing oil inlet temperature in the gear box 1.

[0059] The specific working process is as follows: when the temperature of the introduced injection air flow is controlled to be within a preset range, the injection air flow is introduced from one end of the total air flow path 13, and the injection air flow is divided into two paths after flowing through the total air flow path 13. Among them, one injection air flow enters the sealed cylinder 3 through the main air flow branch 8; when the other injection air flow flows through the isolation air flow branch 6, the pressure reducing valve 10 will perform pressure reduction treatment on it, and the injection air flow will flow into the gear box 1 after pressure reduction. The temperature change degree of the outlet air flow after the injection air flow enters the sealed cylinder 3 and the gear box 1 after temperature control by the temperature control component is controlled, so as not to excessively affect the bearing oil inlet temperature in the gear box 1, and effectively reduce the influence of the introduction of the injection air flow on the bearing oil inlet temperature in the gear box 1, thereby ensuring the safe operation of the supercritical carbon dioxide compressor or turbine.

[0060] As an optional implementation, the air flow pressure of the air injection air flow introduced into the total air flow path 13 is 6 MPa-20 MPa, which can be better suitable for the dry gas sealing device and effectively isolate the oil and gas in the downstream gearbox 1.

[0061] As an optional embodiment, the relationship between the air flow pressure and temperature of the injection air flow introduced into the total air flow path 13 is as follows: min =-0.0032P 3 +0.0041P 2 +6.0759P+42.262; T max =0.0118P 3 -0.5304P 2 +11.581P+48.113;

[0062] Among them, T min is the lowest temperature of the injected gas flow; T max is the maximum temperature of the introduced gas injection flow; P is the gas flow pressure of the introduced gas injection flow.

[0063] In this embodiment, in order to minimize temperature variations in the leakage airflow from the dry gas seal and the outlet airflow from the isolated airflow branch 6, and to ensure that the deviation in the bearing oil inlet temperature in the gearbox 1 is controlled within a range of ±0.4°C, the leakage airflow from the dry gas seal and the outlet airflow from the isolated airflow branch 6 can deviate as high as 62°C and as low as 20°C.

[0064] Specifically, when the air flow pressure of the injected air flow introduced into the total air flow path 13 is 20 MPa, the maximum temperature of the injected air flow does not exceed 162°C, and the minimum temperature of the injected air flow is not lower than 139°C.

[0065] As an optional implementation, during the operation of the dry gas sealing device, the air flow pressure downstream of the dynamic ring 4 and the static ring 5 is maintained in the range of 0.11 MPa(a)-0.15 MPa(a).

[0066] In this embodiment, while ensuring that the outlet airflow velocity of the isolated airflow branch 6 is not less than 5m / s, the reverse flow of oil and gas can be effectively prevented. Considering that the source of the injection airflow comes from the main circuit system where the compressor or turbine is located, in order to reduce the power loss caused by the injection airflow, it is necessary to minimize the amount of injection airflow used. Under the condition of a certain geometric dimension, by reducing the airflow pressure of the injection airflow, the airflow density of the injection airflow is controlled, thereby effectively improving the airflow velocity and the use effect. In addition, if the bearing oil pressure in the gearbox 1 is too high, it will lead to increased power consumption of the configured oil circuit system, increased bearing wear loss, and may cause lubricating oil to splash out of the bearing. Therefore, it is necessary to control the airflow pressure downstream of the dynamic ring 4 and the static ring 5 within the range of 0.11MPa(a)-0.15MPa(a).

[0067] As an optional implementation manner, the total mass of the leakage airflow and the isolation airflow is no more than 5% of the mass of the bearing oil inlet in the gearbox 1 .

[0068] In this embodiment, if the bearing oil inlet temperature is too high, the lubricating oil viscosity will be too high, resulting in increased unit losses and excessive bearing temperature rise, which may trigger an alarm shutdown. If the bearing oil inlet temperature is too low, the lubricating oil will oxidize and deteriorate, triggering bearing failure accidents and other problems. Therefore, the bearing inlet temperature is controlled within the range of 36-46°C. Since the leakage airflow and isolation airflow of the dry gas seal device flow directly through the bearing in a zero-leakage scenario, if the total mass of the leakage airflow and isolation airflow is too high, the bearing inlet oil temperature will be more susceptible to airflow temperature fluctuations. Therefore, to reduce the sensitivity of airflow temperature to bearing oil temperature, the total mass of the leakage airflow and isolation airflow downstream of the dynamic ring 4 and the static ring 5 is no more than 5% of the bearing inlet oil mass in the gearbox 1. In this case, when the temperature of the leakage airflow of the dry gas seal device and the temperature of the outlet airflow of the isolation airflow branch 6 deviate from the preset operating range of the bearing inlet oil temperature by 4°C, the bearing inlet oil temperature will only deviate by 0.1°C, greatly improving safety and operational convenience.

[0069] The above are only preferred embodiments of the present application and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A supercritical carbon dioxide zero-leakage dry gas sealing device, comprising a sealing cylinder and a dynamic ring and a static ring arranged inside the sealing cylinder, wherein: The dry gas sealing device further comprises: The main air flow path is used to introduce the air injection flow into the sealing cylinder and the gear box; a main airflow branch, one end of which is connected to the main airflow path, and the other end of which is connected to the sealing cylinder; an isolated air flow branch, one end of the isolated air flow branch being connected to the main air flow path, the other end of the isolated air flow branch being connected to the gear box, and the isolated air flow branch being connected in parallel with the main air flow branch; a pressure reducing valve, the pressure reducing valve being arranged on the isolated air flow branch; and A temperature control component is used to control the temperature of the injection air flow based on the air flow pressure of the injection air flow introduced into the total air flow path, so that the temperature of the leakage air flow of the dry gas sealing device and the temperature of the outlet air flow of the isolation air flow branch are adapted to the bearing oil inlet temperature in the gearbox.

2. The supercritical carbon dioxide zero-leakage dry gas sealing device according to claim 1, wherein: An air injection hole is provided on the sealing cylinder. The air injection hole is located on the side of the dynamic ring facing away from the gear box, and the air injection hole is communicated with the main air flow branch.

3. The supercritical carbon dioxide zero-leakage dry gas sealing device according to claim 1, wherein: The dry gas sealing device further includes a pressure reducing structure for sharing the pressure drop requirement borne by the pressure reducing valve.

4. The supercritical carbon dioxide zero-leakage dry gas sealing device according to claim 3, wherein: The pressure reducing structure includes a resistance member and a throttle hole. The resistance member is arranged on a side of the pressure reducing valve close to the total air flow path, and the throttle hole is arranged on a side of the pressure reducing valve away from the total air flow path.

5. The supercritical carbon dioxide zero-leakage dry gas sealing device according to claim 4, wherein: A pressure regulating groove is provided on one side of the gear box close to the sealing cylinder, and the pressure regulating groove is communicated with the isolation airflow branch.

6. The supercritical carbon dioxide zero-leakage dry gas sealing device according to claim 5, wherein: The resistance element has a plurality of first protruding expansion portions, and the plurality of first protruding expansion portions are connected in series.

7. The supercritical carbon dioxide zero-leakage dry gas sealing device according to claim 6, wherein: The pressure regulating groove has a plurality of second protruding expansion parts, and the plurality of second protruding expansion parts are connected in series, and the plurality of second protruding expansion parts are arranged in a symmetrical or staggered manner.

8. A supercritical carbon dioxide zero-leakage dry gas sealing method, wherein: The temperature of the introduced gas injection flow is controlled using the supercritical carbon dioxide zero-leakage dry gas sealing device as described in any one of claims 1 to 7.

9. The supercritical carbon dioxide zero-leakage dry gas sealing method according to claim 8, wherein: The air flow pressure of the air injection air flow introduced into the total air flow path is 6 MPa-20 MPa.

10. The supercritical carbon dioxide zero-leakage dry gas sealing method according to claim 9, wherein: The relationship between the air flow pressure and temperature of the gas injection air flow introduced into the total air flow path is as follows: min =-0.0032P 3 +0.0041P 2 +6.0759P+42.262; T max =0.0118P 3 -0.5304P 2 +11.581P+48.113; Among them, T min is the lowest temperature of the injected gas flow; T max is the maximum temperature of the introduced gas injection flow; P is the gas flow pressure of the introduced gas injection flow.

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