Supercritical carbon dioxide dry gas seal experiment device

Abstract

The invention provides a supercritical carbon dioxide dry gas seal experiment device, which comprises a test mechanism and a rotor assembly, and is characterized in that the rotor assembly is rotatably connected with the test mechanism; the testing mechanism comprises a bearing testing table, a cooling cavity, a dry gas sealing cavity and a shell which are connected in sequence, and a high-pressure cavity is formed between the dry gas sealing cavity and the shell; an oil seal assembly is installed in the cooling cavity, a balance seal assembly and a dry gas seal assembly are installed in the dry gas seal cavity, the balance seal assembly comprises a balance moving ring and a balance static ring assembly, and the dry gas seal assembly comprises a seal moving ring and a seal static ring assembly. The balance static ring assembly and the sealing static ring assembly are connected with the dry gas sealing cavity. The device can solve the problem that an experimental device in the prior art is difficult to simulate high-temperature and high-pressure working conditions of supercritical carbon dioxide and balance axial force generated by a high-pressure medium.

Description

Technical Field

[0001] This invention relates to the field of dry gas sealing technology, specifically to a supercritical carbon dioxide dry gas sealing experimental device. Background Technology

[0002] Carbon dioxide undergoes a change in properties when the temperature exceeds its critical temperature (Tc = 31.26℃) and the pressure exceeds its critical pressure (7.29 MPa). Its density becomes close to that of a liquid, its viscosity close to that of a gas, and its diffusion coefficient is 100 times that of a liquid, making it promising for a wide range of applications. Supercritical CO2 power generation, as a novel power generation technology, uses supercritical carbon dioxide as the working fluid to convert heat from a heat source into mechanical energy. This heat source can come from nuclear reactors, solar energy, geothermal energy, industrial waste heat, fossil fuel combustion, etc. Under the current energy and environmental protection circumstances, the excellent properties of supercritical carbon dioxide as the working fluid make its system highly promising for application and valuable for research.

[0003] Centrifugal compressors provide energy to the working fluid by rotating the impeller at high speed. They have advantages such as high efficiency, high pressure ratio and wide operating range under varying conditions. They are the core component of supercritical carbon dioxide Brayton cycle systems and one of the key devices that determine the overall operational stability of the system.

[0004] The inlet and outlet shafts of supercritical carbon dioxide compressors use dry gas seals, which require factory simulation experiments based on actual on-site operating conditions. However, existing experimental setups often struggle to fully simulate the harsh conditions of supercritical carbon dioxide under high temperature and pressure, and to balance the enormous axial forces generated by the high-pressure medium. This results in insufficient accuracy and reliability of experimental results, failing to truly reflect the performance of the dry gas seals in actual operation, and affecting the quality assessment and certification of the seals. Summary of the Invention

[0005] The purpose of this invention is to provide a supercritical carbon dioxide dry gas sealing experimental device, which can solve the problem in the existing technology that it is difficult to simulate the high temperature and high pressure conditions of supercritical carbon dioxide and balance the axial force generated by the high pressure medium in actual use.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] A supercritical carbon dioxide dry gas sealing experimental device includes a testing mechanism and a rotor assembly, wherein the rotor assembly is rotatably connected to the testing mechanism;

[0008] The testing mechanism includes a bearing test bench, a cooling chamber, a dry gas sealing chamber, and a housing connected in sequence. A high-pressure chamber is formed between the dry gas sealing chamber and the housing. An oil seal assembly is installed in the cooling chamber. A balance sealing assembly and a dry gas sealing assembly are installed in the dry gas sealing chamber. The balance sealing assembly includes a balance moving ring and a balance stationary ring assembly. The dry gas sealing assembly includes a sealing moving ring and a sealing stationary ring assembly. The balance stationary ring assembly and the sealing stationary ring assembly are connected to the dry gas sealing chamber.

[0009] Both the balancing ring and the sealing ring are mounted on the rotor assembly, and the balancing ring abuts against the sealing ring; the cooling chamber is provided with a liquid inlet and a liquid outlet, and the bearing test bench is provided with an oil inlet.

[0010] Preferably, the sealing stationary ring assembly includes a sealing stationary ring body and a first spring support mechanism, wherein the sealing stationary ring body is slidably connected to the first spring support mechanism, and the first spring support mechanism is fixedly installed in the dry gas sealing cavity.

[0011] Preferably, the balancing stationary ring assembly includes a balancing stationary ring body and a second spring support mechanism, wherein the balancing stationary ring body is slidably connected to the second spring support mechanism, and the second spring support mechanism is fixedly installed in the dry gas sealing cavity.

[0012] Preferably, the rotor assembly includes a rotating shaft, a bearing, and a bushing. The bushing and the bearing are mounted on the rotating shaft, and the rotating shaft is rotatably connected to the bearing test bench through the bearing. The balancing rotating ring and the sealing rotating ring are both mounted on the bushing.

[0013] Preferably, a heat-insulating sleeve for cooperating with the oil seal assembly is installed on the rotating shaft.

[0014] Preferably, the oil seal assembly includes a first oil seal and a second oil seal, the first oil seal being fixedly mounted on the bearing test bench, and the second oil seal being mounted on the cooling cavity.

[0015] Preferably, the heat insulation sleeve is provided with a lip structure for engaging with the second oil seal.

[0016] Preferably, the bushing is provided with a mounting groove, and the sealing ring and the balance ring are fixedly installed in the mounting groove; an elastic compensation element is installed in the mounting groove.

[0017] Preferably, an oil guide plate is connected inside the bearing test bench, and the top of the oil guide plate is provided with an inclined portion that is inclined toward the oil inlet.

[0018] Preferably, a sealing element is installed on the dry gas sealing cavity, and the sealing element is provided with a plurality of sealing parts arranged in a comb-like pattern.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] In this invention, both the balancing rotating ring and the sealing rotating ring mounted on the rotor assembly are provided with helical grooves. A first sealing end face is formed between the sealing rotating ring and the sealing stationary ring assembly, and a second sealing end face is formed between the balancing rotating ring and the balancing stationary ring assembly. When the rotor assembly rotates at high speed, the balancing rotating ring and the sealing rotating ring, which rotate with the rotor assembly, can pump the gas medium input into the dry gas sealing cavity through the air inlet into the first sealing end face and the second sealing end face, respectively. The gas pumped into the first sealing end face can form a stable gas film on the first sealing end face, effectively sealing the gap between the rotor assembly and the dry gas sealing cavity. At the same time, the balancing sealing assembly uses the reverse force generated on the balancing rotating ring by the medium pressure to counteract the axial thrust acting on the sealing rotating ring, thus protecting the rotor assembly. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the structure of the present invention.

[0023] Figure 2 For the present invention Figure 1 A magnified view of a portion of point A in the middle.

[0024] Figure 3 This is a schematic diagram of the spiral groove in this invention.

[0025] The attached diagram lists the components represented by each number as follows:

[0026] 101-Helical groove, 102-Rotor assembly, 103-Bearing test bench, 104-Cooling chamber, 105-Dry gas sealing chamber, 106-Housing shell, 107-High pressure chamber, 108-Oil seal assembly, 109-Balance sealing assembly, 110-Dry gas sealing assembly, 111-Balance moving ring, 112-Balance stationary ring assembly, 113-Sealing moving ring, 114-Sealing stationary ring assembly, 115-Sealing stationary ring body, 116-First spring support mechanism, 117-Balance stationary ring body, 118-Second spring support mechanism, 119-Shaft, 120-Bearing, 121-Shaft sleeve, 122-Heat insulation sleeve, 123-First oil seal, 124-Second oil seal. Detailed Implementation

[0027] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the embodiments of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0028] In the description of the embodiments of the present invention, it should be understood that the terms "length", "vertical", "horizontal", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing the embodiments of the present invention 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 the embodiments of the present invention.

[0029] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of the present invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0030] In this embodiment of the invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this embodiment of the invention according to the specific circumstances.

[0031] In embodiments of the present invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0032] The following disclosure provides many different implementations or examples for carrying out different structures of the embodiments of the present invention. To simplify the disclosure of the embodiments of the present invention, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the embodiments of the present invention. Furthermore, reference numerals and / or reference letters may be repeated in different examples of the embodiments of the present invention; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various implementations and / or arrangements discussed.

[0033] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0034] Example 1

[0035] See Figure 1 - Figure 3 This embodiment discloses a supercritical carbon dioxide dry gas sealing experimental device, including a testing mechanism and a rotor assembly 102, wherein the rotor assembly 102 is rotatably connected to the testing mechanism;

[0036] The testing mechanism includes a bearing 120 test bench 103, a cooling chamber 104, a dry gas sealing chamber 105, and a housing 106 connected in sequence. A high-pressure chamber 107 is formed between the dry gas sealing chamber 105 and the housing 106. An oil seal assembly 108 is installed in the cooling chamber 104. A balance sealing assembly 109 and a dry gas sealing assembly 110 are installed in the dry gas sealing chamber 105. The balance sealing assembly 109 includes a balance moving ring 111 and a balance stationary ring assembly 112. The dry gas sealing assembly 110 includes a sealing moving ring 113 and a sealing stationary ring assembly 114. The balance stationary ring assembly 112 and the sealing stationary ring assembly 114 are connected to the dry gas sealing chamber 105.

[0037] The balancing ring 111 and the sealing ring 113 are both mounted on the rotor assembly 102, and the balancing ring 111 abuts against the sealing ring 113. The cooling chamber 104 is provided with a liquid inlet and a liquid outlet, and the bearing 120 test bench 103 is provided with an oil inlet.

[0038] In this embodiment, the dry gas sealing cavity 105 formed between the rotor assembly 102 and the bearing 120 test bench 103 is provided with an air inlet and an exhaust port; the end of the rotor assembly 102 away from the housing 106 is connected to a drive device for driving the rotor assembly 102 to rotate, and the drive device is a conventional drive device in the prior art; the bearing 120 test bench 103, the cooling cavity 104, the dry gas sealing cavity 105 and the housing 106 are connected sequentially along the axial direction of the rotor assembly 102, and the housing 106 is provided with... Medium inlet; the bearing 120 test bench 103 is provided with an oil passage for supplying lubricating oil to the rotor assembly 102, and the oil passage is connected to the oil inlet; lubricating oil can be input into the bearing 120 cavity through the oil inlet and the oil passage to lubricate and cool the rotor assembly 102; the cooling chamber 104 is connected between the bearing 120 test bench 103 and the dry gas sealing chamber 105, and a cooling flow channel is provided in the cooling chamber 104; the two ends of the cooling flow channel are respectively connected to the liquid inlet and the liquid outlet; the cooling medium passes through the liquid inlet and the cooling chamber 104 in sequence. The flow channel and outlet circulate the liquid into the cooling flow channel to remove heat conducted from the dry gas sealing chamber 105 (used for testing the dry gas sealing effect) to the shaft; the oil seal assembly 108 is installed in the cooling chamber 104 to isolate the medium and assist in sealing; the dry gas sealing chamber 105 is equipped with a dry gas sealing assembly 110 for testing the dry gas sealing performance and a balancing seal for balancing axial forces; wherein, the medium inlet is used to connect to the gas source pipeline, and the high-pressure carbon dioxide gas source is input into the high-pressure chamber 107 through the gas source pipeline; a current is installed on the gas source pipeline. The existing technology uses a conventional electric heater, and the electric heating gas is used to heat the carbon dioxide gas input into the high-pressure chamber to the target temperature; the outer wall of the dry gas sealing chamber (105) is provided with a heat insulation layer (made of aluminum silicate fiber) to reduce heat loss; conventional shut-off valve, pressure regulating valve, safety valve, pressure and temperature sensor equipment are installed in sequence on the gas source pipeline; the liquid inlet and liquid outlet of the cooling chamber 104 are respectively used to connect to a conventional coolant circulation system in the prior art, and the coolant circulation system is used to circulate and input cooling medium into the cooling channel.

[0039] Based on the supercritical carbon dioxide dry gas sealing experimental apparatus described above, this embodiment also discloses a method for testing the sealing performance of supercritical carbon dioxide dry gas, including the following steps:

[0040] S1. Establish a simulated experimental environment;

[0041] S2, Drive rotor assembly 102 to accelerate to rated test speed;

[0042] S3, Data Acquisition and Monitoring;

[0043] S4. End test;

[0044] In S1, before the dry gas sealing experiment simulation begins, the coolant circulation system is started, and the low-temperature coolant begins to flow through the flow channel of the cooling chamber 104 to pre-cool the rotor assembly 102, preparing it to withstand the subsequent high-temperature conditions. At the same time, the drive device is started to drive the rotor assembly 102 to rotate at a low speed, and the medium is introduced into the dry gas sealing chamber 105 through the air inlet and exhaust port to check whether the rotor assembly 102 is running smoothly, and to initially observe whether there is any abnormal friction or vibration in the dry gas sealing assembly 110 and the balance sealing assembly 109. The shut-off valve on the gas source pipeline is slowly opened to introduce carbon dioxide gas into the high-pressure chamber 107, gradually increasing the temperature and pressure of the carbon dioxide in the high-pressure chamber 107 until the carbon dioxide pressure rises to the target experimental pressure.

[0045] In S2, the drive device drives the rotor assembly 102 to rotate to a rated speed. Both the balance ring 111 and the sealing ring 113 mounted on the rotor assembly 102 are provided with spiral grooves 101. A first sealing end face is formed between the sealing ring 113 and the sealing stationary ring assembly 114, and a second sealing end face is formed between the balance ring 111 and the balance stationary ring assembly 112. When the rotor assembly 102 rotates at high speed, the balance ring 111 and the sealing ring 113, rotating with the rotor assembly 102, can pump the gas medium input through the air inlet into the dry gas sealing chamber 105 into the first and second sealing end faces respectively. The gas pumped into the first sealing end face can form a stable gas film on the first sealing end face, effectively sealing the gap between the rotor assembly 102 and the dry gas sealing chamber 105. Simultaneously, the balance sealing assembly 109 uses the reverse force generated by the medium pressure on the balance ring 111 to counteract the axial thrust acting on the sealing ring 113, thus protecting the rotor assembly 102.

[0046] In S3, the outlet is connected to a conventional high-precision flow meter or mass spectrometer leak detector to monitor and record the flow rate of supercritical carbon dioxide leaking from the first sealing end face, thereby determining the dry gas sealing performance.

[0047] In S4, after detecting the leaked supercritical carbon dioxide flow rate by a high-precision flow meter or mass spectrometer leak detector connected to the outlet, the rotation speed of the rotor assembly 102 is gradually reduced by the drive device, and the carbon dioxide pressure in the high-pressure chamber 107 is slowly released to atmospheric pressure; when the rotor assembly 102 stops rotating, the coolant circulation system is shut off and the addition of lubricating oil to the oil inlet is stopped.

[0048] Further optimization involves the sealing stationary ring assembly 114, which includes a sealing stationary ring body 115 and a first spring support mechanism 116. The sealing stationary ring body 115 is slidably connected to the first spring support mechanism 116, which is fixedly installed within the dry gas sealing cavity 105. In this embodiment, the first spring support mechanism 116 includes a first spring seat and a first spring. The first spring seat is fixedly installed within the dry gas sealing cavity 105, and the sealing stationary ring body 115 is connected to the first spring seat via the first spring. One end of the first spring is fixedly connected to the sealing stationary ring body 115, and the other end is fixedly connected to the first spring seat. This allows the sealing stationary ring body 115 to cooperate with the sealing moving ring 113, forming a sealing gas film on the first sealing end face.

[0049] Further optimization involves the balancing stationary ring assembly 112, which includes a balancing stationary ring body 117 and a second spring support mechanism 118. The balancing stationary ring body 117 is slidably connected to the second spring support mechanism 118, which is fixedly installed within the dry gas sealing cavity 105. In this embodiment, the second spring support mechanism 118 includes a second spring seat and a second spring. The second spring seat is fixedly installed within the dry gas sealing cavity 105. The balancing stationary ring body 117 is connected to the second spring seat via the second spring. One end of the second spring is fixedly connected to the balancing stationary ring body 117, and the other end is fixedly connected to the second spring seat. The balancing stationary ring can cooperate with the balancing moving ring 111, allowing the gas film pressure in the second sealing end face to stably act on the balancing moving ring 111, counteracting the axial thrust acting on the sealing moving ring 113 and protecting the rotor assembly 102.

[0050] Further optimization involves the rotor assembly 102, which includes a shaft 119, a bearing 120, and a bushing 121. The bushing 121 and the bearing 120 are mounted on the shaft 119. The shaft 119 is rotatably connected to the bearing 120 test bench 103 via the bearing 120. The balance ring 111 and the sealing ring 113 are both mounted on the bushing 121. The shaft 119 is rotatably connected to the bearing 120 test bench 103 via the bearing 120, and lubricating oil can be supplied to the gap between the bearing 120 and the bearing 120 test bench 103 through the oil inlet and oil passage.

[0051] Further optimization involves mounting a heat insulation sleeve 122 on the rotating shaft 119 for cooperation with the oil seal assembly 108. In this embodiment, the heat insulation sleeve 122 is made of a low thermal conductivity material, such as polyetheretherketone (PEEK) or special nylons like PAI. The heat insulation sleeve 122 is tightly fitted onto the rotating shaft 119, forming a thermal resistance barrier in the axial direction, greatly reducing heat conduction from the high-temperature dry gas sealing cavity through the rotating shaft 119 to the low-temperature bearing 120 test bench 103. This effectively controls the temperature of the bearing 120 and the surrounding lubricating oil, preventing the bearing 120 from failing due to overheating and the lubricating oil from oxidizing and deteriorating due to high temperature, thereby ensuring the long-term stable operation of the bearing 120 test bench 103.

[0052] Further optimization involves the oil seal assembly 108 comprising a first oil seal 123 and a second oil seal 124. The first oil seal 123 is fixedly mounted on the bearing 120 test bench 103, and the second oil seal 124 is mounted on the cooling cavity 104. In this embodiment, the first oil seal 123 installed on the bearing 120 test stand 103 is used to seal the bearing 120 cavity formed between the bearing 120 and the bearing 120 test stand 103, preventing the lubricating oil entering the bearing 120 cavity through the oil inlet and oil passage from leaking outward from the bearing 120 test stand 103 side, and also preventing external impurities, dust, etc. from entering the bearing 120 cavity and affecting the normal operation and life of the bearing 120; the second oil seal 124 is used to cooperate with the heat insulation sleeve 122 to block the leakage of high pressure and high temperature supercritical carbon dioxide medium from the dry gas sealing cavity 105 to the bearing 120 side, clearly dividing the internal space of the experimental device into the high temperature and high pressure medium area dry gas sealing cavity 105 side and the low temperature and normal pressure lubricating oil area bearing 120 test stand 103 side.

[0053] Further optimization involves providing a lip structure on the heat insulation sleeve 122 for engaging with the second oil seal 124. The second oil seal 124 engages with the lip mechanism, forming an effective dynamic seal between them. The heat insulation sleeve 122 itself is used to block heat transfer, while the second oil seal 124 is used to block media leakage. The two are closely integrated in structure and function, jointly ensuring effective isolation between the high-temperature and low-temperature zones.

[0054] Further optimization involves providing a mounting groove on the bushing 121, in which the sealing ring 113 and the balance ring 111 are fixedly mounted; an elastic compensation element is installed in the mounting groove. In this embodiment, the elastic compensation element is a C-shaped sealing ring, which is pre-tightened between the bottom of the groove and the sealing ring 113 and the balance ring 111, providing a certain axial elastic pre-tightening force. Simultaneously, the elastic compensation element can absorb the axial thermal expansion difference of the rotor assembly 102 under hot operation and offset minor axial movement, ensuring the following and stability of the first and second sealing end faces during operation.

[0055] Further optimization involves an oil guide plate connected inside the bearing 120 test bench 103, with an inclined portion at the top of the oil guide plate tilted towards the oil inlet. In this embodiment, after the lubricating oil enters from the oil inlet 12, it falls onto the inclined portion 22 of the oil guide plate 21. This design guides the lubricating oil to flow more smoothly and centrally to the bearing 120 that requires lubrication, improving lubrication efficiency and ensuring that the bearing 120 is adequately lubricated and cooled. Simultaneously, the inclined structure helps to expel gases trapped in the lubricating oil and prevents oil splashing or stagnation in non-critical areas, optimizing the oil path distribution inside the bearing 120 cavity.

[0056] Further optimization involves installing a sealing element on the dry gas sealing chamber 105, with several sealing portions arranged in a comb-like pattern. These sealing portions provide multiple seals between the dry gas sealing chamber 105 and the high-pressure chamber 107, effectively preventing any leakage of supercritical carbon dioxide from the high-pressure chamber 107 to the outside, ensuring experimental safety and the stability of the test medium parameters. Furthermore, the comb-like structure is made of an elastic material, preventing instantaneous seal failure due to thermal expansion and contraction or pressure shock. Compared to the single sealing ring structure in existing technologies, the comb-like arrangement of sealing portions can distribute the sealing stress.

[0057] Example 2

[0058] See Figures 1-3 This embodiment is a further optimization based on Embodiment 1. In this embodiment, a method for state detection and control of the supercritical carbon dioxide dry gas sealing experimental device described in Embodiment 1 is provided. The method specifically includes:

[0059] Real-time acquisition of the pressure P of the medium inside the dry gas sealing cavity 105 during the dry gas sealing experiment. t and temperature T t Leakage rate Q t The effective value of radial vibration a of shaft 119 rms,t Based on the collected parameters, the comprehensive health index HI is calculated. t It is used to quantitatively characterize the real-time working status of the seal.

[0060] HI t The calculation method is as follows:

[0061] HI t =α·f P (P t )+β·f T (T t )+γ·f Q (Q t )+δ·f V (a rms,t )

[0062] Wherein, α, β, γ and δ are preset weighting coefficients, and α+β+γ+δ=1;

[0063] The f P (P t f is the pressure state function. P (P t The calculation method for ) is as follows:

[0064]

[0065] The P opt The target pressure for the current experimental phase is P. range This refers to the allowable pressure fluctuation range for the experiment;

[0066] The f T (T t ) is the temperature state function, f T (T t The calculation method for ) is as follows:

[0067]

[0068] The T opt The target temperature for the current experimental phase, T range This refers to the allowable temperature fluctuation range for the experiment;

[0069] The f Q (Q t ) is the leakage state function, where f is the leakage state function. Q (Q t The calculation method for ) is as follows:

[0070] f Q (Q t )=exp(-η·|Q t -Q norm |),

[0071] The Q norm η is the rated leakage rate under the target operating conditions, and η is the sensitivity coefficient.

[0072] The f V (a rms,t f is the vibration state function. V (a rms,t The calculation method for ) is as follows:

[0073]

[0074] The A base As the vibration reference value, the HI t The range of values ​​is (0,1], HI t A higher value indicates a healthier seal.

[0075] In the specific implementation process, when testing the performance of the dry gas seal at 250℃ and 10.0MPa supercritical carbon dioxide, the rotational speed n0 = 12000rpm and the pressure P0 = 10.0MPa were set; the rated leakage rate Q norm =0.5NL / min; weighting coefficients α=0.2, β=0.2, γ=0.4, δ=0.2; P rabge =1.0MPa, η=0.2, A base =0.5g;

[0076] Suppose that at a certain experimental time t, the following data is collected:

[0077] P t =10.1MPa, Q t =0.55NL / min, a rms,t =0.3g;

[0078] The values ​​of each state function can be calculated:

[0079] f P (P t ) = 1 - |10.1 - 10.0| / 1.0 = 0.90

[0080] f T (T t )=1-|251-250| / 30≈0.967

[0081] f Q (Q t )=exp(-2.0×|0.55-0.5|)=exp(-0.1)≈0.905

[0082] f V (a rms,t = 0.5 / (0.5+0.3) = 0.625

[0083] A comprehensive health index (HI) can be obtained. tThe value is 0.86, which directly indicates the sealing condition.

[0084] The execution of the supercritical carbon dioxide dry gas sealing performance testing method relies on an adaptive control system connected to the supercritical carbon dioxide dry gas sealing experimental device via a wired or wireless connection. The adaptive control system includes a controller, a sensing unit, and an execution unit. The sensing unit includes a pressure sensor and a temperature sensor installed on the dry gas sealing chamber 105, a high-precision flow meter installed in the leakage pipeline, and a vibration sensor installed on the test bench section on the bearing 120 side. The pressure sensor is used to measure the real-time pressure P of the medium inside the dry gas sealing chamber 105. t A temperature sensor is used to measure the real-time temperature Tt of the medium inside the dry gas seal cavity 105; a high-precision flow meter is used to measure the real-time leakage rate Q of the dry gas seal. t The vibration sensor is used to measure the radial vibration velocity a of the rotating shaft 119. rms,t ;

[0085] The execution unit includes a frequency converter electrically connected to the drive device and an electric actuator electrically connected to the intake pressure regulating valve. The frequency converter is used to adjust the output speed of the drive device, and the electric actuator is used to adjust the opening of the intake pressure regulating valve, thereby controlling the pressure of the medium entering the dry gas sealing chamber 105. The controller is connected to the sensing unit via wired or wireless means. The adaptive control system forms a closed-loop control circuit, and the sensing unit collects pressure P in real time. t Temperature Tt, real-time leakage rate Q t and vibration velocity a rms,t The signal is transmitted to the controller; the controller has the health index HI built in. t The computational model calculates and implements a segmented control strategy based on the real-time calculated HI. t The values ​​and trends of these values ​​are used to determine the system's current stage: healthy steady state, dynamic adjustment, or degradation protection. Subsequently, the speed adjustment Δn is calculated. set Finally, the controller Δn set The command is sent to the frequency converter in the execution unit, which adjusts the speed of the drive device accordingly, thereby realizing the active adjustment and optimization of the sealing conditions.

[0086] Based on real-time calculated HI t The following methods are used to determine the stage of the system—whether it is in a healthy steady state, undergoing dynamic adjustment, or is in degradation protection—based on the values ​​and trends of these values:

[0087] The default health index setting is HI. set The controller is based on the current comprehensive health index HI. t Health Index (HI) setThe magnitude and trend of the deviation are determined, and different deterministic calculation methods are used to generate speed adjustment commands at different control stages.

[0088] When HI t ≥HI set And within M consecutive control cycles |HI t -HI t-1 When |<δt, the system is determined to be in the first stage of a healthy and stable state. At this time, while maintaining the healthy state, the controller makes a small disturbance to the speed to explore the performance potential of the seal or optimize energy efficiency. The calculation method for the speed adjustment command is as follows:

[0089] Δn set =A·sin(2πft)+K opt ·(Q target -Q t )

[0090] Where A is the disturbance amplitude, f is the disturbance frequency, t is time, and K is... opt To optimize the coefficients, Q target The desired optimization target is the leakage rate.

[0091] When |HI t -HI set When |≤ΔH, but the system does not meet the conditions of the first stage, the system is determined to be in the second stage of dynamic adjustment; at this time, the controller uses a proportional-integral PI control algorithm to make HI t A rapid and smooth approach to HI set The calculation method for the speed adjustment command is as follows:

[0092]

[0093] Wherein, K p For proportionality coefficient, K i ΔH is the integral coefficient, and ΔH is the set health index deviation threshold.

[0094] When HI t ≤HI set When -ΔH is reached, a significant degradation in sealing performance is determined. At this point, the controller, with the core objective of improving system safety and protecting the seal, employs strong proportional control to rapidly reduce the speed to alleviate the load. In the third stage, the speed adjustment command is calculated as follows:

[0095] Δn set =-K safe ·(HI set -ΔH-HI t )

[0096] Wherein, K safeThe safety protection factor is significantly larger than K during the dynamic adjustment phase. p .

[0097] The controller's preset parameters are set as follows:

[0098] HI set =0.85, ΔH =0.10;

[0099] A = 5 rpm, f = 0.001 Hz, K opt = 8 rpm / (NL / min), Q target =0.50NL / min.

[0100] K p =25rpm, K i =1.5rpm / s, K safe =60rpm.

[0101] In practical use, when HI is continuously monitored τ The value stabilizes around 0.88 (>0.85) with fluctuations less than 0.01. The controller determines that it is entering the first stage: steady-state optimization control.

[0102] Current leakage rate Q t =0.48NL / min, the controller calculates the speed adjustment command:

[0103] Δn set =5·sin(2π·0.001·t)+8·(0.50-0.48≈0.16rpm

[0104] This instruction will increase the current speed by approximately 0.16 rpm, aiming to fine-tune the operating conditions to bring the leakage rate closer to the optimization target of 0.50 NL / min, while introducing extremely low-frequency small sinusoidal fluctuations to explore the system response.

[0105] If the current HI τ =0.721, HI set -HI τ =0.129, the absolute value of which is greater than ΔH0.10, but the rate of change has not reached the degradation protection threshold. The system is in the second stage: dynamic adjustment control.

[0106] Assume the integral value of the health index error over a past period is |∑(HI) set -HI t )·Δt|=2.8s;

[0107] The controller uses the PI formula for calculation:

[0108] Δn set=25×0.129+1.5×2.8=3.225+4.2=7.425rpm.

[0109] The controller outputs a command to increase the engine speed by approximately 7.4 rpm. This is intended to improve the sealing condition by increasing the film stiffness through increased engine speed, thereby improving HI. τ It rebounded to 0.85.

[0110] If a sudden abnormality occurs in the seal, HI is detected. t The speed dropped sharply from 0.80 to 0.65 within a short period of time. The controller immediately determined that it was entering the third stage: degradation protection control, and the controller calculated the speed adjustment command.

[0111] Δn s∈t =-60×(0.85-0.10-0.65)=-60×0.10=-6.0rpm

[0112] Controller output command: Immediately reduce engine speed by 6.0 rpm. If HI τ The rate continues to decrease; the Δn calculated in the next control cycle... s∈t The negative value will also increase, achieving a rapid and significant reduction in rotational speed, forcing the experiment to quickly exit the dangerous operating condition, and effectively protecting the seals and experimental equipment.

[0113] Adjusting the speed using a speed adjustment command calculation method ensures the transparency, repeatability, and operability of the control process.

[0114] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0115] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. It should be noted that any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A supercritical carbon dioxide dry gas sealed experimental apparatus, characterized in that: It includes a testing mechanism and a rotor assembly (102), the rotor assembly (102) being rotatably connected to the testing mechanism; The testing mechanism includes a bearing (120) test bench (103), a cooling chamber (104), a dry gas sealing chamber (105), and a housing (106) connected in sequence. A high-pressure chamber (107) is formed between the dry gas sealing chamber (105) and the housing (106). An oil seal assembly (108) is installed in the cooling chamber (104). A balance sealing assembly (109) and a dry gas sealing assembly (110) are installed in the dry gas sealing chamber (105). The balance sealing assembly (109) includes a balance moving ring (111) and a balance stationary ring assembly (112). The dry gas sealing assembly (110) includes a sealing moving ring (113) and a sealing stationary ring assembly (114). The balance stationary ring assembly (112) and the sealing stationary ring assembly (114) are connected to the dry gas sealing chamber (105). The balance ring (111) and the sealing ring (113) are both mounted on the rotor assembly (102), and the balance ring (111) abuts against the sealing ring (113); the cooling chamber (104) is provided with a liquid inlet and a liquid outlet, and the bearing (120) test bench (103) is provided with an oil inlet.

2. The supercritical carbon dioxide dry gas sealed experimental apparatus according to claim 1, characterized in that: The sealing stationary ring assembly (114) includes a sealing stationary ring body (115) and a first spring support mechanism (116). The sealing stationary ring body (115) is slidably connected to the first spring support mechanism (116), and the first spring support mechanism (116) is fixedly installed in the dry gas sealing cavity (105).

3. The supercritical carbon dioxide dry gas sealed experimental apparatus according to claim 1, characterized in that: The balance stationary ring assembly (112) includes a balance stationary ring body (117) and a second spring support mechanism (118). The balance stationary ring body (117) is slidably connected to the second spring support mechanism (118), and the second spring support mechanism (118) is fixedly installed in the dry gas sealing cavity (105).

4. The supercritical carbon dioxide dry gas sealed experimental apparatus according to claim 1, characterized in that: The rotor assembly (102) includes a rotating shaft (119), a bearing (120), and a bushing (121). The bushing (121) and the bearing (120) are mounted on the rotating shaft (119). The rotating shaft (119) is rotatably connected to the bearing (120) test bench (103) via the bearing (120). The balance ring (111) and the sealing ring (113) are both mounted on the bushing (121).

5. The supercritical carbon dioxide dry gas sealed experimental apparatus according to claim 4, characterized in that: A heat insulation sleeve (122) for cooperating with the oil seal assembly (108) is installed on the rotating shaft (119).

6. The supercritical carbon dioxide dry gas sealed experimental apparatus according to claim 5, characterized in that: The oil seal assembly (108) includes a first oil seal (123) and a second oil seal (124). The first oil seal (123) is fixedly installed on the bearing (120) test bench (103), and the second oil seal (124) is installed on the cooling cavity (104).

7. The supercritical carbon dioxide dry gas sealed experimental apparatus according to claim 6, characterized in that: The heat insulation sleeve (122) is provided with a lip structure for cooperating with the second oil seal (124).

8. The supercritical carbon dioxide dry gas sealed experimental apparatus according to claim 4, characterized in that: The bushing (121) is provided with an installation groove, and the sealing ring (113) and the balance ring (111) are fixedly installed in the installation groove; an elastic compensation component is installed in the installation groove.

9. The supercritical carbon dioxide dry gas sealed experimental apparatus according to claim 1, characterized in that: An oil guide plate is connected inside the bearing (120) test bench (103), and the top of the oil guide plate is provided with an inclined part that is inclined towards the oil inlet.

10. The supercritical carbon dioxide dry gas sealed experimental apparatus according to claim 1, characterized in that: A sealing element is installed on the dry gas sealing cavity (105), and the sealing element is provided with a plurality of sealing parts arranged in a comb-like pattern.

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