A supercritical carbon dioxide dry gas seal gas film stiffness testing device

Abstract

The application relates to the field of dry gas seal performance test devices, and provides a supercritical carbon dioxide dry gas seal gas film stiffness test device, which comprises a sealing cavity assembly, a fixed ring assembly and a compensation ring assembly. The sealing cavity assembly comprises a lower cavity, a middle cavity and an upper cavity. The fixed ring assembly comprises a fixed ring which is installed at the lower part of the upper cavity and located in the middle cavity. The compensation ring assembly comprises compensation rings, a push ring assembly, an elastic element, a first movable ring seat assembly, a second movable ring seat assembly and a force transducer which are sequentially arranged from top to bottom. The force transducer is used for indirectly testing the closing force of the compensation rings. An auxiliary labyrinth seal is formed between the lower cavity and the radial direction and forms a throttling gap. A first leakage cavity is connected with a second leakage cavity through the throttling gap, and the medium pressure in the second leakage cavity is close to atmospheric pressure. The application realizes the on-line regulation and control of the closing force of the compensation rings of the dry gas seal, the on-line test of the sealing opening force and the gas film thickness by means of fine adjustment of the compression amount of the elastic element, and has the advantages of convenient adjustment, high test precision and the like.

Description

TECHNICAL FIELD

[0001] The application relates to the field of dry gas seal performance test devices, in particular to a supercritical carbon dioxide dry gas seal gas film stiffness test device. BACKGROUND

[0002] The dry gas seal technology is a key technology for realizing low leakage and high stable operation of shaft end seals of heart devices such as compressors and expanders of a supercritical CO2 Brayton cycle power generation system. The dry gas seal is to open a fluid dynamic pressure groove on the end face of a dynamic ring or a static ring, to pump the sealing medium in a sealing cavity into the sealing end face by the fluid dynamic pressure effect of the dynamic pressure groove when the dynamic ring rotates, to form an observable opening force on the sealing end face, to balance and compensate the closing force generated by the elastic element on the back of the ring and the static pressure of the medium in the sealing cavity, and to form a non-contact fluid film with certain stiffness. The opening force of the dry gas seal presents a decelerating and decreasing change rule with the increase of the sealing gap, which is the key to the stable film thickness of the dry gas seal under external disturbance. The gas film stiffness value is equal to the ratio of the slight change of the opening force to the slight change of the corresponding gas film thickness, and the relationship curve of the sealing opening force with respect to the gas film thickness needs to be obtained, and then the sealing gas film stiffness under different gas film thicknesses is obtained. As a key performance index reflecting the axial disturbance resistance of the dry gas seal, the accurate numerical calculation and test of the gas film stiffness are crucial.

[0003] At present, there are test devices for the steady-state performance parameters such as the gas film thickness and the leakage rate of the dry gas seal under different medium, speed and pressure conditions, but there is no related report on the gas film stiffness test platform of the supercritical CO2 dry gas seal. The design has many difficulties, mainly as follows: (1) the supercritical CO2 is a medium with very high pressure, and the medium pressure in the sealing cavity of the supercritical CO2 dry gas seal is generally more than 8 MPa, and even reaches 14 MPa. Once the sealing gap of the dry gas seal is too large and the high-pressure medium in the main sealing cavity leaks in large quantities to the leakage cavity located on the inner diameter side of the sealing end face through the sealing gap, the pressure in the leakage cavity will rise sharply, causing safety risks; (2) in order to measure the gas film stiffness, it is necessary to quantitatively construct and accurately test the slight change of the sealing closing force, and to correspondingly measure the change amount of the gas film thickness, and to obtain the relationship curve of the opening force and the gas film stiffness with respect to the gas film thickness according to the balance of the opening force and the closing force, and it is difficult to construct and accurately test the slight change of the sealing closing force. SUMMARY

[0004] The application provides a supercritical carbon dioxide dry gas seal gas film stiffness testing device, which is characterized by ingenious design. The application indirectly realizes the fine adjustment of the compression amount of the elastic element by adjusting the gas pressure in the back pressure cavity, thereby realizing the online adjustment and control of the closing force of the dry gas seal compensation ring and the online testing of the sealing opening force and the gas film thickness, and the gas film stiffness of the dry gas seal under different working conditions can be tested. The application has the advantages of convenient adjustment, high testing precision and the like. In addition, an auxiliary labyrinth seal with throttling and pressure reduction functions is additionally arranged between the first leakage cavity and the second leakage cavity. On the one hand, the pressure in the second leakage cavity is reduced and approaches to the atmospheric pressure, and the auxiliary labyrinth seal can also play a safe sealing role when the dry gas seal suddenly leaks a large amount of gas and the pressure in the first leakage cavity rapidly rises. On the other hand, the pressure resistance requirement of the testing instrument on the leakage pipeline connected to the second leakage cavity is reduced, and the influence of the test on the dry gas seal sealing opening force caused by the excessively high pressure in the second leakage cavity is also reduced. The technical scheme of the application is as follows:

[0005] A supercritical carbon dioxide dry gas seal gas film stiffness testing device, comprising a sealing cavity assembly, a fixed ring assembly, a compensation ring assembly and an auxiliary labyrinth seal.

[0006] The sealing cavity assembly comprises a lower cavity, a middle cavity and an upper cavity. The upper cavity is connected with the middle cavity, and the middle cavity is connected with the lower cavity. The second leakage cavity is formed between the lower cavity and the middle cavity. The fixed ring assembly comprises a fixed ring, which is installed at the lower part of the upper cavity and located in the middle cavity.

[0007] The compensation ring assembly is located in the middle cavity. The compensation ring assembly comprises, from top to bottom, a compensation ring, a push ring assembly, an elastic element, a first movable ring seat assembly, a second movable ring seat assembly and a force sensor. The outer side of the compensation ring is a main sealing cavity, and the inner side of the compensation ring is a first leakage cavity. A distance measuring assembly is arranged in the first leakage cavity, and the distance measuring assembly is used for testing the gap between the sealing end faces of the dry gas seal pair. The fixed ring and the compensation ring form a dry gas seal pair to be tested. The lower end surface of the compensation ring is connected to the upper end surface of the push ring assembly, and the elastic element is abutted to the push ring assembly and the first movable ring seat assembly at two ends. The back pressure cavity is axially arranged between the first movable ring seat assembly and the second movable ring seat assembly. The gas pressure in the back pressure cavity can be adjusted and controlled online. By adjusting and controlling the gas pressure in the back pressure cavity, the compression amount of the elastic element can be indirectly changed to indirectly control the closing force of the compensation ring. The bottom of the second movable ring seat assembly is abutted to the force sensor, and the space where the force sensor is located is connected with the second leakage cavity. The force sensor is used for indirectly testing the closing force of the compensation ring.

[0008] The auxiliary labyrinth seal is installed in the middle cavity, and a throttling gap is formed between the auxiliary labyrinth seal and the lower cavity in a radial direction, the first leakage cavity is connected with the second leakage cavity through the throttling gap, and the medium pressure in the second leakage cavity is close to atmospheric pressure.

[0009] The fine adjustment of the compression amount of the elastic element is indirectly realized by fine adjustment of the gas pressure in the back pressure cavity, and then the online regulation and control of the closing force of the compensation ring of the dry gas seal and the online testing of the opening force and the gas film thickness of the dry gas seal are realized. The gas film stiffness of the dry gas seal under different working conditions can be tested, and the method has the advantages of convenient adjustment, high testing precision, etc. In addition, by additionally arranging an auxiliary labyrinth seal with a throttling and pressure reducing effect between the first leakage cavity and the second leakage cavity, on the one hand, the pressure in the second leakage cavity is reduced and approaches atmospheric pressure, and on the other hand, when a large amount of leakage occurs in the dry gas seal and the pressure in the first leakage cavity rises sharply, the auxiliary labyrinth seal can play a safe sealing role, and on the other hand, the pressure resistance requirement of the testing instrument on the leakage pipeline connected to the second leakage cavity is reduced, and the influence of the test on the opening force of the dry gas seal caused by the excessively high pressure in the second leakage cavity is also reduced.

[0010] In some embodiments, the supercritical carbon dioxide dry gas seal gas film stiffness testing device further comprises a gas auxiliary system, the gas auxiliary system comprises a main sealing cavity gas inlet pipeline, a back pressure cavity gas inlet pipeline, a safety pressure relief pipeline, a leakage gas collection pipeline and a parameter acquisition module; the main sealing cavity gas inlet pipeline is connected with the main sealing cavity, the back pressure cavity gas inlet pipeline is connected with the back pressure cavity, the safety pressure relief pipeline is connected with the first leakage cavity, the leakage gas collection pipeline is connected with the second leakage cavity, and the parameter acquisition module can acquire data of the distance measuring assembly and the force sensor.

[0011] In some embodiments, a safety valve is arranged on the safety pressure relief pipeline, and the safety valve is opened to automatically release pressure when the medium pressure in the first leakage cavity exceeds a preset threshold value.

[0012] In some embodiments, a first pressure sensor and a first pressure regulating valve for measuring and controlling the pressure of the main sealing cavity are arranged on the main sealing cavity gas inlet pipeline, and a second pressure sensor and a second pressure regulating valve for measuring and controlling the pressure of the back pressure cavity are arranged on the back pressure cavity gas inlet pipeline; the parameter acquisition module can acquire data of the first pressure sensor and the second pressure sensor.

[0013] In some embodiments, the first movable ring seat assembly comprises a first movable ring seat, a first movable ring seat inner sealing ring and a first movable ring seat outer sealing ring for isolating the back pressure cavity and the main sealing cavity; and the second movable ring seat assembly comprises a second movable ring seat, a second movable ring seat inner sealing ring and a second movable ring seat outer sealing ring for isolating the back pressure cavity and the second leakage cavity.

[0014] In some embodiments, the inner side of the compensation ring is provided with a first ring platform near the lower end surface thereof, and the outer side of the compensation ring is provided with a second ring platform near the sealing end surface thereof, the inner diameter of the first movable ring seat and the second movable ring seat is equal to the outer diameter of the first ring platform, and the outer diameter of the first movable ring seat and the second movable ring seat is equal to the inner diameter of the second ring platform.

[0015] By providing the first ring platform and the second ring platform on the compensation ring, and by making the inner diameter of the first movable ring seat and the second movable ring seat equal to the outer diameter of the first ring platform, and by making the outer diameter of the first movable ring seat and the second movable ring seat equal to the inner diameter of the second ring platform, the total gas pressure acting on the whole formed by the compensation ring and the push ring assembly in the main sealing cavity is equal to the total gas pressure acting on the first movable ring seat in the main sealing cavity, and thus the two forces can be offset in the calculation process, the number of parameters participating in the calculation in the calculation of the closing force is reduced, and thus the parameter measurement error is finally prevented from being transmitted to the closing force, and the calculation accuracy of the closing force is ensured.

[0016] In some embodiments, the number of the force sensors is multiple, and the multiple force sensors are arranged at uniform intervals around the axis of the second movable ring seat.

[0017] In some embodiments, the displacement measuring assembly comprises a sensor mounting seat, a displacement sensor, and a displacement sensor sensing ring; the sensor mounting seat is mounted on the inner diameter of the fixed ring, the displacement sensor is mounted on the sensor mounting seat, and the displacement sensor sensing ring is mounted on the inner diameter of the compensation ring.

[0018] The supercritical carbon dioxide dry gas seal gas film stiffness testing device provided by the present application has at least one of the following advantages:

[0019] 1. The supercritical carbon dioxide dry gas seal gas film stiffness testing device provided by the present application indirectly realizes the fine adjustment of the compression amount of the elastic element by fine adjustment of the gas pressure in the back pressure cavity, thereby realizing the online adjustment and control of the dry gas seal compensation ring closing force and the online testing of the sealing opening force and the gas film thickness, and realizing the dry gas seal gas film stiffness testing under different working conditions, and has the advantages of convenient adjustment, high testing precision, etc. In addition, by additionally arranging an auxiliary labyrinth seal with a throttling pressure reduction function between the first leakage cavity and the second leakage cavity, on the one hand, the pressure in the second leakage cavity is reduced and approaches to the atmospheric pressure, and on the other hand, when a large amount of leakage occurs in the dry gas seal, the pressure in the first leakage cavity is rapidly increased, the auxiliary labyrinth seal plays a safe sealing role, on the other hand, the pressure resistance requirement of the testing instrument on the leakage pipeline connected to the second leakage cavity is reduced, and the influence of the test of the dry gas seal opening force caused by the too high pressure in the second leakage cavity is also reduced.

[0020] 2. The supercritical carbon dioxide dry gas seal gas film stiffness testing device provided by the application, by setting the first ring table and the second ring table on the compensation ring, and making the inner diameter of the first movable ring seat and the second movable ring seat equal to the outer diameter of the first ring table, and the outer diameter of the first movable ring seat and the second movable ring seat equal to the inner diameter of the second ring table, the total gas pressure borne by the whole formed by the compensation ring and the push ring assembly in the main sealing cavity is equal to the total gas pressure borne by the first movable ring seat in the main sealing cavity, and then the two forces can be offset in the calculation process, the number of parameters participating in the calculation in the closing force calculation is reduced, and finally the parameter measurement error is avoided from being transmitted to the closing force, the calculation accuracy of the closing force is ensured. BRIEF DESCRIPTION OF DRAWINGS

[0021] The above-mentioned characteristics, technical features, advantages and implementation modes of the supercritical carbon dioxide dry gas seal gas film stiffness testing device will be further described in a clear and understandable manner in combination with the preferred embodiments and the accompanying drawings:

[0022] Figure 1 is a schematic diagram of an embodiment of the testing device of the application;

[0023] Figure 2 is Figure 1 is a schematic diagram of the sealing cavity assembly and the internal structure thereof in the embodiment;

[0024] Figure 3 is a schematic diagram of the force borne by the combined assembly formed by the compensation ring and the push ring assembly;

[0025] Figure 4 is a schematic diagram of the force borne by the first movable ring seat assembly;

[0026] Figure 5 is a schematic diagram of the force borne by the second movable ring seat assembly.

[0027] BRIEF DESCRIPTION OF DRAWINGS

[0028] Lower cavity 11, leakage gas leading hole 111, middle cavity 12, main sealing cavity air inlet hole 121, back pressure cavity air inlet hole 122, upper cavity 13 pressure relief gas leading hole 131, fixed ring assembly 2, fixed ring 21, sensor mounting seat 22, displacement sensor 23, compensation ring assembly 3, compensation ring 31, first ring table 311, second ring table 312, push ring assembly 32, push ring auxiliary seal 321, push ring 322, elastic element 33, first movable ring seat assembly 34, first movable ring seat inner sealing ring 341, first movable ring seat outer sealing ring 342, first movable ring seat 343, second movable ring seat assembly 35, second movable ring seat inner sealing ring 351, second movable ring seat outer sealing ring 352, second movable ring seat 353, displacement sensor sensing ring 36, force sensor 37, auxiliary labyrinth seal 4, throttle gap 41, main sealing cavity air inlet pipeline 51, first pressure sensor 511, first temperature sensor 512, first pressure regulating valve 513, main sealing cavity 514, back pressure cavity air inlet pipeline 52, second pressure sensor 521, second pressure regulating valve 522, back pressure cavity 523, safety pressure relief pipeline 53, pressure relief gas pressure gauge 531, safety valve 532, pressure relief gas collection tank 533, first leakage cavity 534, leakage gas collection pipeline 54, leakage gas flow meter 541, leakage gas pressure gauge 542, leakage gas collection tank 543, second leakage cavity 544, parameter acquisition module 55. DETAILED DESCRIPTION

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, specific implementation manners of the present application will be described below with reference to the drawings. Obviously, the drawings described below are only some of the embodiments of the present application, and for those skilled in the art, other drawings can be obtained from these drawings without creative labor, and other embodiments can also be obtained.

[0030] In order to make the drawing simple, only the parts related to the present application are shown in each drawing, and they do not represent the actual structure of the product. In addition, in order to make the drawing simple and easy to understand, in some drawings, only one of the parts with the same structure or function is shown, or only one of them is marked. In this paper, "one" not only means "only one", but also means "more than one".

[0031] It should be further understood that the term "and / or" used in the specification and claims of the present application means any combination of one or more of the associated listed items and all possible combinations, and includes these combinations.

[0032] In this document, unless otherwise explicitly stated and limited, the terms "mounting", "connected", "connecting" should be interpreted broadly, for example, can be fixed connection, can also be detachable connection, or integral connection; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0033] In addition, in the description of the present application, the terms "first", "second" and the like are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0034] Referring to Figures 1-5 The present application provides a supercritical carbon dioxide dry gas seal gas film stiffness test device, comprising: a sealed cavity assembly, a fixed ring assembly 2, a compensation ring assembly 3 and an auxiliary labyrinth seal 4;

[0035] The sealed cavity assembly comprises a lower cavity 11, a middle cavity 12 and an upper cavity 13, the upper cavity 13 is connected with the middle cavity 12, the middle cavity 12 is connected with the lower cavity 11, and the second leakage cavity 544 is formed between the lower cavity 11 and the middle cavity 12, specifically, the lower cavity 11, the middle cavity 12 and the upper cavity 13 are connected in the axial direction by screws.

[0036] The fixed ring assembly 2 comprises a fixed ring 21, which is installed at the lower part of the upper cavity 13 and located in the middle cavity 12;

[0037] A compensation ring assembly 3 is located in the middle cavity 12, and comprises, from top to bottom, a compensation ring 31, a push ring assembly 32, an elastic element 33, a first movable ring seat assembly 34, a second movable ring seat assembly 35, and a force sensor 37; the outer side of the compensation ring 31 is a main sealing cavity 514, and the inner side of the compensation ring 31 is a first leakage cavity 534, which is provided with a distance measuring assembly for testing the gap between the sealing end faces of the dry gas seal pair; the fixed ring 21 and the compensation ring 31 form the dry gas seal pair to be tested; the lower end surface of the compensation ring 31 is connected to the upper end surface of the push ring assembly 32, and the elastic element 33 is abutted to the push ring assembly 32 and the first movable ring seat assembly 34 at both ends; the first movable ring seat assembly 34 and the second movable ring seat assembly 35 are axially provided with a back pressure cavity 523; the gas pressure in the back pressure cavity 523 can be controlled online, and by controlling the gas pressure in the back pressure cavity 523, the compression amount of the elastic element 33 can be indirectly changed to indirectly control the closing force received by the compensation ring 31; the bottom of the second movable ring seat assembly 35 is abutted to the force sensor 37, the space where the force sensor 37 is located is in communication with the second leakage cavity 544, and the force sensor 37 is used for indirectly testing the closing force of the compensation ring 31.

[0038] An auxiliary labyrinth seal 4 is installed in the middle cavity 12, and forms a throttling gap 41 with the lower cavity 11 in the radial direction; the first leakage cavity 534 is in communication with the second leakage cavity 544 through the throttling gap 41, and the medium pressure in the second leakage cavity 544 is close to atmospheric pressure. Since the space where the force sensor 37 is located is in communication with the second leakage cavity 544, the gas pressure in the second leakage cavity 544 will generate an upward gas pressure on the second movable ring seat 353, thereby affecting the testing accuracy of the force sensor 37 on the closing force of the compensation ring 31. Therefore, the closer the pressure in the second leakage cavity 544 is to atmospheric pressure, the higher the testing accuracy of the force sensor 37 on the closing force of the compensation ring 31.

[0039] Reference Figure 1 、 Figure 2In one embodiment, the supercritical carbon dioxide dry gas seal gas film stiffness test device further comprises a gas auxiliary system, the gas auxiliary system comprises a main sealing cavity gas inlet pipeline 51, a back pressure cavity gas inlet pipeline 52, a safety relief pipeline 53, a leakage gas collection pipeline 54 and a parameter acquisition module 55; the main sealing cavity gas inlet pipeline 51 is in communication with the main sealing cavity 514, the back pressure cavity gas inlet pipeline 52 is in communication with the back pressure cavity 523, the safety relief pipeline 53 is in communication with the first leakage cavity 534, the leakage gas collection pipeline 54 is in communication with the second leakage cavity 544, and the parameter acquisition module 55 can acquire data of the distance measuring assembly and the force sensor 37.

[0040] Specifically, the middle cavity 12 is provided with a main sealing cavity gas inlet hole 121, and the supercritical CO2 medium in the main sealing cavity gas inlet pipeline 51 enters the main sealing cavity 514 through the main sealing cavity gas inlet hole 121. The middle cavity 12 is also provided with a back pressure cavity gas inlet hole 122, and the high-pressure gas in the back pressure cavity gas inlet pipeline 52 enters the back pressure cavity 523 through the back pressure cavity gas inlet hole 122. The high-pressure gas in the back cavity 523 can be supercritical CO2 medium, or can be nitrogen, air or other conventional medium. The upper cavity 13 is provided with a relief gas outlet hole 131, and the CO2 medium leaked from the dry gas seal end face to be tested in the first leakage cavity 534 can enter the safety relief pipeline 53 through the relief gas outlet hole 131, and the discharged CO2 medium finally flows into the relief gas collection tank 533 for recycling and preservation. The lower cavity 11 is provided with a leakage gas outlet hole 111, and the CO2 medium in the second leakage cavity 544 enters the leakage gas collection pipeline 54 through the leakage gas outlet hole 111, and is finally discharged to the atmospheric environment or enters the leakage gas collection tank 543.

[0041] Reference Figure 1 , Figure 2 In one embodiment, the safety relief pipeline 53 is provided with a safety valve 532, which automatically opens the relief when the medium pressure in the first leakage cavity 534 exceeds the preset threshold.

[0042] Specifically, the safety relief pipeline 53 is also provided with a relief gas pressure gauge 531 for monitoring the gas pressure in the first leakage cavity 534, and the relief can only be automatically opened when the gas pressure in the first leakage cavity 534 exceeds the relief threshold of the safety valve 532.

[0043] Reference Figure 1 , Figure 2In one embodiment, the main sealing cavity gas inlet pipeline 51 is provided with a first pressure sensor 511 and a first pressure regulating valve 513 for measuring and controlling the pressure of the main sealing cavity 514, and the back pressure cavity gas inlet pipeline 52 is provided with a second pressure sensor 521 and a second pressure regulating valve 522 for measuring and controlling the pressure of the back pressure cavity 523; the parameter acquisition module 55 can acquire the data of the first pressure sensor 511 and the second pressure sensor 521. Preferably, the main sealing cavity gas inlet pipeline 51 is further provided with a first temperature sensor 512 for testing the temperature of the medium.

[0044] Reference Figure 1 , Figure 2 In one embodiment, the leakage gas collection pipeline 54 is provided with a leakage gas flow meter 541 and a leakage gas pressure gauge 542 for testing the leakage gas flow and pressure.

[0045] Reference Figure 1 , Figure 2 In one embodiment, the first movable ring seat assembly 34 includes a first movable ring seat 343 and a first movable ring seat inner sealing ring 341 and a first movable ring seat outer sealing ring 342 for isolating the back pressure cavity 523 and the main sealing cavity 514; the second movable ring seat assembly 35 includes a second movable ring seat 353 and a second movable ring seat inner sealing ring 351 and a second movable ring seat outer sealing ring 352 for isolating the back pressure cavity 523 and the second leakage cavity 544.

[0046] Reference Figures 1-3 In one embodiment, the inner side of the compensation ring 31 near the lower end face thereof is provided with a first ring platform 311, and the outer side of the compensation ring 31 near the sealing end face thereof is provided with a second ring platform 312, the inner diameter of the first movable ring seat 343 and the second movable ring seat 353 is equal to the outer diameter of the first ring platform 311, and the outer diameter of the first movable ring seat 343 and the second movable ring seat 353 is equal to the inner diameter of the second ring platform 312.

[0047] It is worth noting that by providing the first ring platform 311 and the second ring platform 312 on the compensation ring 31, and making the inner diameter of the first movable ring seat 343 and the second movable ring seat 353 equal to the outer diameter of the first ring platform 311, and the outer diameter of the first movable ring seat 343 and the second movable ring seat 353 equal to the inner diameter of the second ring platform 312, the overall total gas pressure of the compensation ring 31 and the push ring assembly 32 formed by the main sealing cavity 514 is equal to the total gas pressure of the first movable ring seat 343 in the main sealing cavity 514, and thus the two forces can be offset in the calculation process, reducing the number of parameters involved in the calculation of the closing force, and thus avoiding the final transmission of parameter measurement error to the closing force, ensuring the calculation accuracy of the closing force.

[0048] Reference Figure 1 , Figure 2 In one embodiment, the number of force sensors 37 is multiple, and the multiple force sensors 37 are arranged at uniform intervals around the axis of the second movable ring seat 353. The number of force sensors 37 is preferably 3.

[0049] Reference Figure 1 , Figure 2 In one embodiment, the displacement sensing assembly includes a sensor mounting seat 22, a displacement sensor 23, and a displacement sensor sensing ring 36; the sensor mounting seat 22 is mounted on the inner diameter of the fixed ring 21, the displacement sensor 23 is mounted on the sensor mounting seat 22, and the displacement sensor sensing ring 36 is mounted on the inner diameter of the compensation ring 31. The displacement sensor 23 is preferably an eddy current sensor, which is used to test the micron-level gap change between the dry gas seal end faces. The fixed ring 21 and the compensation ring 31 form a dry gas seal pair to be tested, and the micron-level gap between the two sealing end faces is indirectly obtained by testing the gap change between the probe of the displacement sensor 23 and the end face of the displacement sensor sensing ring 36.

[0050] In order to more clearly understand the working principle of the present application, the working principle of the present application is introduced as follows: the gas film stiffness value of the dry gas seal is equal to the ratio of the small change amount of the sealing opening force to the small change amount of the gas film thickness. In actual operation, according to the axial force balance principle of the closing force on the lower side of the combined assembly formed by the compensation ring 31 and the push ring assembly 32 and the sealing end face opening force of the compensation ring 31, the sealing opening force can be indirectly changed by changing the sealing closing force, and the corresponding sealing gas film (sealing fluid film) thickness change amount is measured, the change relationship curve of the sealing opening force about the gas film (fluid film) thickness is obtained, and then the gas film stiffness value under different gas film thicknesses can be obtained according to the definition of the gas film stiffness.

[0051] When the present application is used for testing the axial gas film stiffness of the supercritical CO2 dry gas seal, the change in the gas film thickness between the end faces of the dry gas seal pair can be indirectly obtained by the micron-level gap change between the probe of the test displacement sensor 23 and the end face of the displacement sensor sensing ring 36. The slight adjustment of the closing force on the dry gas seal pair is achieved by changing the pressure of the back pressure cavity 523. The specific principle is as follows: the upper part of the first movable ring seat assembly 34 is the main sealing cavity 514 and the elastic element 33, and the lower part is the back pressure cavity 523; when the gas pressure of the back pressure cavity 523 at the lower part of the first movable ring seat 343, the gas pressure of the main sealing cavity 514 at the upper part, the force of the elastic element 33, and the auxiliary sealing friction force of the inner and outer diameters of the first movable ring seat are balanced, the first movable ring seat 343 is in a static state; when the gas pressure on the lower part of the first movable ring seat 343 is gradually increased by increasing the pressure of the back pressure cavity 523, the first movable ring seat 343 moves upward and the compression amount of the elastic element 33 increases, and when the spring force increment caused by the increase in the compression amount of the elastic element 33 is balanced with the gas pressure force of the back pressure cavity 523, the first movable ring seat 343 is again in a new balanced state. Thus, the change in the medium pressure of the back pressure cavity 523 can be converted into the change in the closing force on the dry gas seal pair, achieving the slight regulation and control of the closing force of the dry gas seal pair. The precise testing of the closing force on the dry gas seal pair is achieved by the three force sensors 37 below the second movable ring seat 353. The specific principle is as follows: the first movable ring seat assembly 34 and the second movable ring seat assembly 35 are symmetrical in structure and identical in size, and when the back pressure cavity 523 is filled with medium under pressure, the gas pressure acting upward on the first movable ring seat 343 and downward on the second movable ring seat 353 is the same in size and opposite in direction, and the friction forces of the auxiliary sealing rings at the inner and outer diameters of the first movable ring seat and the second movable ring seat are the same in size and opposite in direction, so the axial force measured by the three force sensors 37 is equal to the sum of the gas pressure of the main sealing cavity at the upper part of the first movable ring seat 343 and the force of the elastic element 33; by referring to the above force analysis and combining the force analysis law, the force state of other components or parts can be obtained, thereby achieving the slight regulation and control and precise testing of the closing force and opening force of the dry gas seal pair.

[0052] Referring to Figures 3-5 The axial force force analysis of the compensation ring 31 and the push ring assembly 32, the first movable ring seat assembly 34 and the second movable ring seat assembly 35 is carried out to more clearly explain the testing principle of the gas film stiffness of the supercritical CO2 dry gas seal. The combined part of the compensation ring 31 and the push ring assembly 32 is taken as the object of force analysis, the upper end face thereof is subjected to the fluid film opening force Fo, and the lower end face is subjected to the spring force Fsp of the elastic element 33, the medium pressure Fp2 of the main sealing cavity, and the medium pressure Fp4 of the first leakage cavity; the push ring assembly 32 comprises a push ring auxiliary seal 321 and a push ring 322, and there is also a friction force Ff between the push ring auxiliary seal 321 and the wall surface of the mounting seat (which belongs to a part of the middle cavity body 12); the first movable ring seat assembly 34 comprises a first movable ring seat 343 and a first elastic element 33, and the second movable ring seat assembly 35 comprises a second movable ring seat 353 and a second elastic element 332. f3The upper end surface of the first movable ring seat assembly 34 is subjected to the medium pressure Fp2 of the main sealing cavity and the spring force Fsp of the elastic element 33, the lower end surface is subjected to the medium pressure Fp1 of the back pressure cavity, the inner and outer diameters are subjected to the friction force F between the first movable ring seat inner sealing ring 341, the first movable ring seat outer sealing ring 342 and the wall surface of the mounting seat f1 The upper end surface of the second movable ring seat assembly 35 is subjected to the medium pressure Fp1 of the back pressure cavity, the lower end surface is subjected to the support reaction force F1 of the force transducer 37 and the medium pressure Fp3 of the second leakage cavity, the inner and outer diameters are subjected to the friction force F between the second movable ring seat inner sealing ring 351, the second movable ring seat outer sealing ring 352 and the wall surface of the mounting seat f2 .

[0053] In the installed state, the elastic element 33 is compressed and generates upward spring force on the upper push ring assembly 32 and the compensation ring 31, and downward spring force on the lower first movable ring seat assembly 34. When the medium pressure in the back pressure cavity 523 rises, under the action of the back pressure cavity medium pressure Fp1, the upper first movable ring seat 34 moves upward and the compression amount of the elastic element 33 increases, and the lower second movable ring seat 35 moves downward and the support reaction force F1 of the force transducer 37 increases. Taking the compensation ring 31 and the push ring assembly 32, the first movable ring seat assembly 34 and the second movable ring seat assembly 35 as the force objects respectively, the axial force balance equations are:

[0054] F o =F p4 +F sp +F p2 -F f3

[0055] F p1 =F sp +F p2 +F f1

[0056] F p1 =F1+F p3 +F f2

[0057] The relationship between the reading F1 of the force transducer 37 and the opening force Fo of the sealing fluid film is:

[0058] F o =F1+F p3 +F p4 +(F f2 -F f1 )-F f3

[0059] In the formula, the medium pressure of the second leakage cavity 544 is close to atmospheric pressure, and Fp3 can be ignored; the friction force F f1 and the friction force F f2 are equivalent, and the relationship between the two can be simplified as:

[0060] F o = F1+F p4 -F f3

[0061] In the formula, F1 can be measured by the force sensor 37, F f3 can be obtained by calibration before the test, and Fp4 can be obtained by multiplying the end surface area of the first ring table 311 exposed in the first leakage cavity 534 by the medium pressure in the first leakage cavity 534, on the basis of which the opening force Fo of the sealing fluid film can be obtained.

[0062] The present application realizes the micro-regulation and precise test of the closing force of the dry gas seal pair by regulating the pressure of the back pressure cavity 523 and the plurality of circumferentially distributed force sensors 37, realizes the test of the gas film thickness of the sealing end surface through the displacement sensor 23 and the displacement sensor sensing ring 36, and further realizes the precise test of the gas film stiffness of the supercritical CO2 dry gas seal under different gas film thicknesses.

[0063] It is worth noting that the safety pressure relief pipeline 53 with automatic pressure relief function is additionally arranged on the upper part of the first leakage cavity 534, which ensures the rapid release of gas pressure when the pressure of the first leakage cavity 534 is too high, and improves the reliability and safety of the test device; the auxiliary labyrinth seal 4 is additionally arranged on the lower part of the first leakage cavity 534, which makes the medium pressure in the second leakage cavity 544 relatively low by using the throttling effect of the auxiliary labyrinth seal gap, ensures that the gas pressure in the leakage gas collection pipeline 54 is at a relatively low value, and further improves the safety of the test device.

[0064] It should be noted that the above embodiments can be freely combined as needed. The above is only the preferred embodiment of the present application, and it should be pointed out that for ordinary skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, which should be considered as the protection scope of the present application.

Claims

1. A device for testing the stiffness of a supercritical dry carbon dioxide gas-sealed film, characterized in that, include: A sealing cavity assembly, comprising a lower cavity, a middle cavity, and an upper cavity, wherein the upper cavity is connected to the middle cavity, the middle cavity is connected to the lower cavity, and a second leakage cavity is formed between the lower cavity and the middle cavity; A fixing ring assembly, the fixing ring assembly including a fixing ring, the fixing ring being installed in the lower part of the upper cavity and located in the middle cavity; A compensation ring assembly is located within the central cavity. The compensation ring assembly includes, from top to bottom, a compensation ring, a push ring assembly, an elastic element, a first movable ring seat assembly, a second movable ring seat assembly, and a force sensor. The outer side of the compensation ring is a main sealing cavity, and the inner side of the compensation ring is a first leakage cavity. A ranging assembly is installed in the first leakage cavity to test the gap between the sealing end faces of the dry gas sealing pair. The fixed ring and the compensation ring form the dry gas sealing pair to be tested. The lower end face of the compensation ring is connected to the upper end face of the push ring assembly. The two ends of the elastic element abut against the push ring assembly and the first movable ring seat assembly, respectively. A back pressure cavity is provided axially between the first movable ring seat assembly and the second movable ring seat assembly. The gas pressure in the back pressure cavity can be adjusted online. By adjusting the gas pressure in the back pressure cavity, the compression of the elastic element can be indirectly changed, thereby indirectly controlling the closing force on the compensation ring. The bottom of the second movable ring assembly abuts against the force sensor, and the space where the force sensor is located is connected to the second leakage cavity. The force sensor is used to indirectly test the closing force of the compensation ring. An auxiliary labyrinth seal is installed in the middle cavity, and a throttling gap is formed radially between the auxiliary labyrinth seal and the lower cavity. The first leakage cavity is connected to the second leakage cavity through the throttling gap, and the medium pressure in the second leakage cavity is close to atmospheric pressure.

2. The supercritical carbon dioxide dry gas sealing film stiffness testing device according to claim 1, characterized in that, It also includes a gas-assisted system, which comprises a main sealing cavity inlet pipe, a back pressure cavity inlet pipe, a safety pressure relief pipe, a leak gas collection pipe, and a parameter acquisition module. The main sealing cavity inlet pipe is connected to the main sealing cavity, the back pressure cavity inlet pipe is connected to the back pressure cavity, the safety pressure relief pipe is connected to the first leak cavity, the leak gas collection pipe is connected to the second leak cavity, and the parameter acquisition module is capable of acquiring data from the ranging component and the force sensor.

3. The supercritical carbon dioxide dry gas sealing film stiffness testing device according to claim 2, characterized in that, The safety relief pipeline is equipped with a safety valve, which automatically releases pressure when the medium pressure in the first leakage chamber exceeds a preset threshold.

4. The supercritical carbon dioxide dry gas sealing film stiffness testing device according to claim 2, characterized in that, The main sealing chamber inlet pipe is equipped with a first pressure sensor and a first pressure regulating valve for measuring and controlling the pressure of the main sealing chamber, and the back pressure chamber inlet pipe is equipped with a second pressure sensor and a second pressure regulating valve for measuring and controlling the pressure of the back pressure chamber; the parameter acquisition module can acquire data from the first pressure sensor and the second pressure sensor.

5. The supercritical carbon dioxide dry gas sealing film stiffness testing device according to claim 1, characterized in that, The first movable ring seat assembly includes a first movable ring seat and a first movable ring seat inner sealing ring and a first movable ring seat outer sealing ring for isolating the back pressure chamber and the main sealing chamber; the second movable ring seat assembly includes a second movable ring seat and a second movable ring seat inner sealing ring and a second movable ring seat outer sealing ring for isolating the back pressure chamber and the second leakage chamber.

6. A supercritical carbon dioxide dry gas sealing film stiffness testing device according to any one of claims 1-5, characterized in that, The compensation ring has a first ring platform on its inner side near its lower end face, and a second ring platform on its outer side near its sealing end face. The inner diameters of the first movable ring seat and the second movable ring seat are equal to the outer diameter of the first ring platform, and the outer diameters of the first movable ring seat and the second movable ring seat are equal to the inner diameter of the second ring platform.

7. The supercritical carbon dioxide dry gas sealing film stiffness testing device according to claim 6, characterized in that, The force sensors are multiple, and the multiple force sensors are arranged at uniform intervals around the axis of the second movable ring seat.

8. The supercritical carbon dioxide dry gas sealing film stiffness testing device according to claim 7, characterized in that, The ranging assembly includes a sensor mounting base, a displacement sensor, and a displacement sensor sensing ring; the sensor mounting base is installed on the inner diameter of the fixed ring, the displacement sensor is installed on the sensor mounting base, and the displacement sensor sensing ring is installed on the inner diameter of the compensation ring.

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