Supercritical carbon dioxide dry gas sealing gas film rigidity testing device

Abstract

The invention relates to the field of dry gas sealing performance testing devices, and provides a supercritical carbon dioxide dry gas sealing gas film rigidity testing device, which comprises a sealing cavity assembly, a gas film rigidity testing device, a gas film rigidity testing device, a gas film rigidity testing device, a gas film rigidity testing device and a gas film rigidity testing device, wherein the sealing cavity assembly comprises a lower cavity, a middle cavity and an upper cavity; the fixing ring assembly comprises a fixing ring, and the fixing ring is installed on the lower portion of the upper cavity and located in the middle cavity; the compensation ring assembly comprises 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 transducer which are sequentially arranged from top to bottom; the force transducer is used for indirectly testing the closing force of the compensation ring; a throttling gap is formed between the auxiliary labyrinth seal and the lower cavity in the radial direction, the first leakage cavity is communicated with the second leakage cavity through the throttling gap, and the medium pressure in the second leakage cavity is close to the atmospheric pressure. On-line regulation and control of the closing force of the dry gas sealing compensation ring and on-line testing of the sealing opening force and the gas film thickness are achieved in a mode of finely adjusting the compression amount of the elastic element, and the device has the advantages of being convenient to adjust, high in testing precision and the like.

Description

Technical Field

[0001] The present application relates to the field of dry gas sealing performance testing devices, and in particular to a supercritical carbon dioxide dry gas sealing gas film stiffness testing device. Background Art

[0002] Dry gas sealing technology is the key technology to achieve low leakage and high stability of axial end sealing of core equipment such as compressors and expanders in supercritical CO2 Brayton cycle power generation systems. Dry gas sealing is to open a fluid dynamic pressure groove on the end face of the seal dynamic ring or static ring, and use the fluid dynamic pressure effect of the dynamic pressure groove when the dynamic ring rotates to pump the sealing medium in the sealing cavity into the sealing end face, and form a considerable opening force on the sealing end face, balance the closing force generated by the elastic element on the back of the compensation ring and the static pressure of the medium in the sealing cavity, and form a non-contact fluid film with a certain stiffness. The opening force of the dry gas seal shows a decelerating and decreasing change law as the sealing gap increases, which is the key to the dry gas seal being able to maintain a stable film thickness under external disturbances. The air film stiffness value is equal to the ratio of the slight change in the opening force to the corresponding slight change in the air film thickness. It is necessary to obtain the relationship curve between the sealing opening force and the air film thickness, and then obtain the sealing air film stiffness under different air film thicknesses. As a key performance indicator reflecting the ability of dry gas seals to resist axial disturbances, accurate numerical calculation and testing of air film stiffness are essential.

[0003] At present, there are test devices for steady-state performance parameters such as dry gas seal film thickness and leakage rate under different media, rotation speeds and pressure conditions. However, there has been no report on a supercritical CO2 dry gas seal film stiffness test platform. There are many difficulties in its design, mainly manifested as follows: (1) Supercritical CO2 is a very high-pressure medium. Generally, the sealing chamber medium pressure of supercritical CO2 dry gas seals exceeds 8MPa, or even reaches 14MPa. Once the dry gas seal gap is too large, the high-pressure medium in the main seal chamber will leak through the seal gap to the leakage chamber on the inner diameter side of the seal end face, causing a sharp increase in the leakage chamber pressure, thereby posing a safety risk. (2) In order to measure the film stiffness, it is necessary to quantitatively construct and accurately test the slight changes in the sealing closing force, and measure the corresponding changes in the film thickness. Based on the balance between the seal opening force and the closing force, the relationship curve between the opening force and the film stiffness and the film thickness can be obtained. However, it is difficult to construct and accurately test the slight changes in the sealing closing force. Summary of the invention

[0004] In order to solve the above problems, the present application provides a supercritical carbon dioxide dry gas seal air film stiffness test device, which is cleverly designed. The present application indirectly achieves fine-tuning of the compression amount of the elastic element by fine-tuning the gas pressure in the back pressure chamber, thereby achieving online regulation of the closing force of the dry gas seal compensation ring and online testing of the seal opening force and air film thickness. It can realize the dry gas seal air film stiffness test under different working conditions, and has the advantages of convenient adjustment and high test accuracy. In addition, by adding an auxiliary labyrinth seal with throttling and pressure reduction function between the first leakage chamber and the second leakage chamber, on the one hand, the pressure in the second leakage chamber can be reduced and close to atmospheric pressure, and at the same time, it can also play a role of safety sealing when a large amount of dry gas seal suddenly leaks and causes the pressure in the first leakage chamber to rise sharply. On the other hand, it can reduce the pressure resistance requirements of the test instrument on the leakage pipeline connected to the second leakage chamber, and also reduce the test influence on the opening force of the dry gas seal secondary seal caused by the excessive pressure in the second leakage chamber. The technical scheme adopted in this application is as follows:

[0005] A supercritical carbon dioxide dry gas sealing gas film stiffness testing device, comprising: a sealing cavity assembly, a fixing ring assembly, a compensating ring assembly and an auxiliary labyrinth seal;

[0006] The sealing cavity assembly includes a lower cavity, a middle cavity and an upper cavity, 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; the fixing ring assembly includes a fixing 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, and the compensation ring assembly includes 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 arranged in order from top to bottom; the outer side of the compensation ring is a main sealing cavity, 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 to test the sealing end face gap of the dry gas sealing pair; the fixed ring and the compensation ring constitute 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, and the two ends of the elastic element are respectively abutted against the push ring assembly and the first movable ring seat assembly; a 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 online, and by adjusting the gas pressure in the back pressure cavity, the compression amount of the elastic element can be indirectly changed to indirectly adjust the closing force of the compensation ring; the bottom of the second movable ring seat assembly abuts against the force sensor, the space where the force sensor is located is connected to the second leakage cavity, and the force sensor is used to indirectly test the closing force of the compensation ring;

[0008] The 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 with the second leakage cavity through the throttling gap, and the medium pressure in the second leakage cavity is close to atmospheric pressure.

[0009] By fine-tuning the gas pressure in the back pressure chamber, the compression amount of the elastic element can be fine-tuned indirectly, thereby realizing online regulation of the closing force of the dry gas seal compensation ring and online testing of the seal opening force and the thickness of the gas film. The dry gas seal gas film stiffness test under different working conditions can be realized, which has the advantages of convenient adjustment and high test accuracy. In addition, by adding an auxiliary labyrinth seal with throttling and pressure reduction function between the first leakage chamber and the second leakage chamber, on the one hand, the pressure in the second leakage chamber can be reduced and close to the atmospheric pressure, and at the same time, it can also play a role of safety sealing when a large amount of leakage suddenly occurs in the dry gas seal and the pressure in the first leakage chamber increases sharply. On the other hand, it can reduce the pressure resistance requirements of the test instrument on the leakage pipeline connected to the second leakage chamber, and also reduce the test influence on the opening force of the dry gas seal secondary seal caused by the excessive pressure in the second leakage chamber.

[0010] In some embodiments, the supercritical carbon dioxide dry gas sealing air film stiffness testing device also includes a gas-assisted system, which includes a main sealing chamber air inlet pipeline, a back pressure chamber air inlet pipeline, a safety pressure relief pipeline, a leakage gas collection pipeline and a parameter acquisition module; the main sealing chamber air inlet pipeline is connected to the main sealing chamber, the back pressure chamber air inlet pipeline is connected to the back pressure chamber, the safety pressure relief pipeline is connected to the first leakage chamber, the leakage gas collection pipeline is connected to the second leakage chamber, and the parameter acquisition module can collect data from the ranging component and the force sensor.

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

[0012] In some embodiments, a first pressure sensor and a first pressure regulating valve for measuring and controlling the pressure of the main sealing chamber are provided on the air inlet pipe of the main sealing chamber, and a second pressure sensor and a second pressure regulating valve for measuring and controlling the pressure of the back pressure chamber are provided on the air inlet pipe of the back pressure chamber; the parameter acquisition module can collect data from the first pressure sensor and the second pressure sensor.

[0013] In some embodiments, 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 seat outer sealing ring for isolating the back pressure chamber and the second leakage chamber.

[0014] In some embodiments, a first ring platform is provided on the inner side of the compensation ring near its lower end surface, and a second ring platform is provided on the outer side of the compensation ring near its sealing end surface, 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.

[0015] By arranging the first ring platform and the second ring platform on the compensation ring, and making the inner diameters of the first movable ring seat and the second movable ring seat 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 equal to the inner diameter of the second ring platform, the total gas pressure in the main sealing chamber received by the whole formed by the compensation ring and the push ring assembly can be equal to the total gas pressure in the main sealing chamber received by the first movable ring seat, and the two forces can offset each other in the calculation process, thereby reducing the number of parameters involved in the calculation of the closing force, thereby avoiding the parameter measurement error from being ultimately transmitted to the closing force, and ensuring the calculation accuracy of the closing force.

[0016] In some embodiments, there are a plurality of force sensors, and the plurality of force sensors are evenly spaced around the axis of the second movable ring seat.

[0017] In some embodiments, the ranging assembly includes a sensor mounting seat, a displacement sensor and a displacement sensor induction ring; the sensor mounting seat is installed on the inner diameter of the fixing ring, the displacement sensor is installed on the sensor mounting seat, and the displacement sensor induction ring is installed on the inner diameter of the compensation ring.

[0018] The present application provides a supercritical carbon dioxide dry gas sealing air film stiffness testing device, which has at least one of the following beneficial effects:

[0019] 1. The present application provides a supercritical carbon dioxide dry gas seal air film stiffness test device, which indirectly achieves the fine adjustment of the elastic element compression by fine-tuning the gas pressure in the back pressure chamber, thereby achieving online regulation of the closing force of the dry gas seal compensation ring and online testing of the seal opening force and air film thickness, and can achieve dry gas seal air film stiffness testing under different working conditions, with the advantages of convenient adjustment and high test accuracy. In addition, by adding an auxiliary labyrinth seal with throttling and pressure reduction function between the first leakage chamber and the second leakage chamber, on the one hand, the pressure in the second leakage chamber can be reduced and close to atmospheric pressure, and at the same time, it can also play a role of safety sealing when a large amount of dry gas seal suddenly leaks and causes the pressure in the first leakage chamber to rise sharply. On the other hand, it can reduce the pressure resistance requirements of the test instrument on the leakage pipeline connected to the second leakage chamber, and also reduce the test influence on the opening force of the dry gas seal secondary seal caused by the excessive pressure in the second leakage chamber.

[0020] 2. The present application provides a supercritical carbon dioxide dry gas sealing air film stiffness testing device, which, by arranging a first ring stage and a second ring stage on the compensation ring, and making the inner diameters of the first movable ring seat and the second movable ring seat equal to the outer diameter of the first ring stage, and the outer diameters of the first movable ring seat and the second movable ring seat equal to the inner diameter of the second ring stage, can make the total gas pressure of the whole formed by the compensation ring and the push ring assembly in the main sealing chamber equal to the total gas pressure of the first movable ring seat in the main sealing chamber, and thus these two forces can offset each other in the calculation process, thereby reducing the number of parameters involved in the closing force calculation, thereby avoiding the parameter measurement error from being ultimately transmitted to the closing force, and ensuring the calculation accuracy of the closing force. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The following will further explain the above characteristics, technical features, advantages and implementation methods of a supercritical carbon dioxide dry gas sealing gas film stiffness testing device in a clear and understandable manner with reference to the accompanying drawings:

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

[0023] Figure 2 yes Figure 1 Schematic diagram of the sealed cavity assembly and its internal structure in the embodiment;

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

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

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

[0027] Description of Figure Numbers:

[0028] Lower cavity 11, leakage gas outlet 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 outlet 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 stage 311, second ring stage 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 seal ring 341, first movable ring seat outer seal ring 342, first movable ring seat 343, second movable ring seat assembly 35, second movable ring seat inner seal ring 351, second movable ring seat outer seal ring 352 , second movable ring seat 353, displacement sensor induction ring 36, force sensor 37, auxiliary labyrinth seal 4, throttling gap 41, main sealing chamber air inlet pipeline 51, first pressure sensor 511, first temperature sensor 512, first pressure regulating valve 513, main sealing chamber 514, back pressure chamber air inlet pipeline 52, second pressure sensor 521, second pressure regulating valve 522, back pressure chamber 523, safety pressure relief pipeline 53, pressure relief gas pressure gauge 531, safety valve 532, pressure relief gas collecting tank 533, first leakage chamber 534, leakage gas collecting pipeline 54, leakage gas flowmeter 541, leakage gas pressure gauge 542, leakage gas collecting tank 543, second leakage chamber 544, parameter acquisition module 55. DETAILED DESCRIPTION

[0029] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the specific implementation methods of the present application will be described below with reference to the accompanying drawings. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings and other implementation methods can be obtained based on these drawings without creative work.

[0030] In order to simplify the drawings, only the parts related to the present application are schematically shown in each figure, and they do not represent the actual structure of the product. In addition, in order to simplify the drawings and facilitate understanding, in some figures, only one of the parts with the same structure or function is schematically drawn or marked. In this article, "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 appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0032] In this document, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

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

[0034] Reference Figure 1-Figure 5 , the present application provides a supercritical carbon dioxide dry gas sealing gas film stiffness testing device, comprising: a sealing cavity assembly, a fixing ring assembly 2, a compensation ring assembly 3 and an auxiliary labyrinth seal 4;

[0035] The sealed cavity assembly includes a lower cavity 11, a middle cavity 12 and an upper cavity 13, the upper cavity 13 is connected to the middle cavity 12, the middle cavity 12 is connected to the lower cavity 11, and a 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 axially fastened and connected by screws.

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

[0037] The compensation ring assembly 3 is located in the middle cavity 12, and the compensation ring assembly 3 includes 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 arranged in order from top to bottom; 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, and a distance measuring assembly is arranged in the first leakage cavity 534, and the distance measuring assembly is used to test the sealing end face clearance of the dry gas sealing pair; the fixed ring 21 and the compensation ring 31 constitute a dry gas sealing pair to be tested; the lower end face of the compensation ring 31 is connected to the upper end face of the push ring assembly 32, The two ends of the elastic element 33 are respectively abutted against the push ring assembly 32 and the first movable ring seat assembly 34; a back pressure chamber 523 is axially arranged between the first movable ring seat assembly 34 and the second movable ring seat assembly 35; the gas pressure in the back pressure chamber 523 can be adjusted online, and by adjusting the gas pressure in the back pressure chamber 523, the compression amount of the elastic element 33 can be indirectly changed to indirectly adjust the closing force exerted on the compensation ring 31; the bottom of the second movable ring seat assembly 35 is abutted against the force sensor 37, and the space where the force sensor 37 is located is connected to the second leakage chamber 544, and the force sensor 37 is used to indirectly test the closing force of the compensation ring 31;

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

[0039] refer to Figure 1 , Figure 2In one embodiment, the supercritical carbon dioxide dry gas sealing air film stiffness testing device also includes a gas-assisted system, which includes a main sealing chamber air inlet pipeline 51, a back pressure chamber air inlet pipeline 52, a safety pressure relief pipeline 53, a leakage gas collection pipeline 54 and a parameter acquisition module 55; the main sealing chamber air inlet pipeline 51 is connected to the main sealing chamber 514, the back pressure chamber air inlet pipeline 52 is connected to the back pressure chamber 523, the safety pressure relief pipeline 53 is connected to the first leakage chamber 534, the leakage gas collection pipeline 54 is connected to the second leakage chamber 544, and the parameter acquisition module 55 can collect data from the ranging component and the force sensor 37.

[0040] Specifically, a main sealing chamber air inlet hole 121 is provided on the middle cavity 12, and the supercritical CO2 medium in the main sealing chamber air inlet pipeline 51 enters the main sealing chamber 514 through the main sealing chamber air inlet hole 121. A back pressure chamber air inlet hole 122 is also provided on the middle cavity 12, and the high-pressure gas in the back pressure chamber air inlet pipeline 52 enters the back pressure chamber 523 through the back pressure chamber air inlet hole 122. The high-pressure gas in the back pressure chamber 523 can be a supercritical CO2 medium, or a conventional medium such as nitrogen and air. A pressure relief gas outlet hole 131 is provided on the upper cavity 13, and the CO2 medium leaking from the dry gas seal end face to be tested in the first leakage cavity 534 can enter the safety pressure relief pipeline 53 through the pressure relief gas outlet hole 131, and the released CO2 medium finally flows into the pressure relief gas collection tank 533 for recovery and storage. The lower cavity 11 is provided with a leakage gas outlet hole 111 , and the CO 2 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 into the atmosphere or enters the leakage gas collection tank 543 .

[0041] refer to Figure 1 , Figure 2 In one embodiment, a safety valve 532 is provided on the safety pressure relief pipeline 53, and the safety valve 532 is opened to automatically release pressure when the medium pressure in the first leakage chamber 534 exceeds a preset threshold.

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

[0043] refer to Figure 1 , Figure 2In one embodiment, the main seal chamber air 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 seal chamber 514, and the back pressure chamber air 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 chamber 523; the parameter acquisition module 55 can acquire data from the first pressure sensor 511 and the second pressure sensor 521. Preferably, the main seal chamber air inlet pipeline 51 is also provided with a first temperature sensor 512 for testing the temperature of the medium.

[0044] refer to 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 rate and pressure.

[0045] refer to 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 chamber 523 and the main sealing chamber 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 seat outer sealing ring 352 for isolating the back pressure chamber 523 and the second leakage chamber 544.

[0046] refer to Figure 1-Figure 3 In one embodiment, a first ring platform 311 is provided on the inner side of the compensation ring 31 near its lower end surface, and a second ring platform 312 is provided on the outer side of the compensation ring 31 near its sealing end surface. The inner diameters of the first movable ring seat 343 and the second movable ring seat 353 are equal to the outer diameter of the first ring platform 311, and the outer diameters of the first movable ring seat 343 and the second movable ring seat 353 are equal to the inner diameter of the second ring platform 312.

[0047] It is worth noting that by arranging the first ring platform 311 and the second ring platform 312 on the compensation ring 31, and making the inner diameters 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 diameters 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 total gas pressure of the whole formed by the compensation ring 31 and the push ring assembly 32 in the main sealing chamber 514 can be equal to the total gas pressure of the first movable ring seat 343 in the main sealing chamber 514, and then the two forces can offset each other in the calculation process, thereby reducing the number of parameters involved in the calculation of the closing force, thereby avoiding the parameter measurement error from being ultimately transmitted to the closing force, and ensuring the calculation accuracy of the closing force.

[0048] refer to Figure 1 , Figure 2 In one embodiment, there are multiple force sensors 37, and the multiple force sensors 37 are evenly spaced around the axis of the second movable ring seat 353. The number of the force sensors 37 is preferably three.

[0049] refer to Figure 1 , Figure 2 In one embodiment, the distance measuring assembly includes a sensor mounting seat 22, a displacement sensor 23 and a displacement sensor induction 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 induction 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 sealing end faces. The fixed ring 21 and the compensation ring 31 constitute a dry gas sealing pair to be tested, and the micron-level gap between the sealing end faces of the two is indirectly obtained by testing the gap change between the probe of the displacement sensor 23 and the end face of the displacement sensor induction ring 36.

[0050] In order to have a clearer understanding of the present application, the working principle of the present application is introduced below: The dry gas seal air film stiffness value is equal to the ratio of the slight change in the seal opening force to the slight change in the air film thickness. In actual operation, according to the principle of axial force balance between the closing force on the lower side of the assembly formed by the compensation ring 31 and the push ring assembly 32 and the opening force of the sealing end face of the compensation ring 31, the seal opening force can be indirectly changed by changing the seal closing force, and the corresponding change in the thickness of the seal air film (sealing fluid film) can be measured to obtain the relationship curve between the seal opening force and the thickness of the air film (fluid film), and then the air film stiffness values ​​under different air film thicknesses can be obtained according to the definition of air film stiffness.

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

[0052] Reference Figure 3-Figure 5 , the axial 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 test principle of the supercritical CO2 dry gas sealing gas film stiffness. The combination of the compensation ring 31 and the push ring assembly 32 is taken as the force analysis object, and its upper end face is subjected to the fluid film opening force Fo, and the lower end face is subjected to the main sealing chamber medium pressure Fp2, the first leakage chamber medium pressure Fp4 and the spring force Fsp of the elastic element 33; the push ring assembly 32 includes a push ring auxiliary seal 321 and a push ring 322, and there is also a friction force F between the push ring auxiliary seal 321 and the wall of the mounting seat (a part of the middle cavity 12) f3The first movable ring seat assembly 34 is taken as the force analysis object. Its upper end face is subjected to the main sealing chamber medium pressure Fp2 and the spring force Fsp of the elastic element 33, its lower end face is subjected to the back pressure chamber medium pressure Fp1, and its inner and outer diameters are subjected to the friction force F between the first movable ring seat inner seal ring 341, the first movable ring seat outer seal ring 342 and the wall surface of the mounting seat. f1 The second movable ring seat assembly 35 is taken as the force analysis object. Its upper end face is subjected to the back pressure chamber medium pressure Fp1, its lower end face is subjected to the support reaction force F1 of the force sensor 37 and the second leakage chamber medium pressure Fp3, and its inner and outer diameters are subjected to the friction force F between the second movable ring seat inner seal ring 351, the second movable ring seat outer seal ring 352 and the mounting seat wall. f2 .

[0053] In the installed state, the elastic element 33 is compressed and generates an upward spring force on the upper push ring assembly 32 and the compensation ring 31, and generates a downward spring force on the lower first movable ring seat assembly 34. When the medium pressure in the back pressure chamber 523 increases, under the action of the back pressure chamber medium pressure Fp1, the upper first movable ring seat 34 moves upward and increases the compression of the elastic element 33, and the lower second movable ring seat 35 moves downward and increases the supporting reaction force F1 of the force sensor 37. The axial force balance equations are respectively listed with 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:

[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 sensor 37 and the opening force Fo of the sealing fluid membrane can be obtained as follows:

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

[0059] Where, the medium pressure of the second leakage chamber 544 is close to the atmospheric pressure, and Fp3 can be ignored; the friction force F of the inner and outer diameter sealing rings of the first movable ring seat is f1 Friction force F between the inner and outer diameter seal rings of the second movable ring seat f2 If they are equal, the relationship between them can be simplified to:

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

[0061] Where, F1 can be measured by force sensor 37, F f3 It can be obtained by calibration before the test. Fp4 can be obtained by multiplying the end surface area of ​​the first ring platform 311 exposed in the first leakage cavity 534 by the medium pressure in the first leakage cavity 534. On this basis, the sealing fluid film opening force Fo can be obtained.

[0062] The present application realizes micro-control and precise testing of the closing force of the dry gas sealing pair by regulating the pressure of the back pressure chamber 523 and a plurality of circumferentially uniformly distributed force sensors 37, and realizes the testing of the thickness of the gas film on the sealing end face by means of the displacement sensor 23 and the displacement sensor induction ring 36, thereby realizing the precise testing of the gas film stiffness under different gas film thicknesses of the supercritical CO2 dry gas seal.

[0063] It is worth noting that a safety pressure relief pipeline 53 with an automatic pressure relief function is added to the upper part of the first leakage chamber 534, which ensures the rapid release of gas pressure when the pressure in the first leakage chamber 534 is too high, thereby improving the reliability and safety of the test device; an auxiliary labyrinth seal 4 is added to the lower part of the first leakage chamber 534, and the throttling effect of the auxiliary labyrinth seal gap is utilized to lower the medium pressure in the second leakage chamber 544, thereby ensuring that the gas pressure in the leakage gas collection pipeline 54 is at a lower value, thereby further improving the safety of the test device.

[0064] It should be noted that the above embodiments can be freely combined as needed. The above are only preferred implementations of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application, and these improvements and modifications should also be regarded as the protection scope of the present application.

Claims

1. A supercritical carbon dioxide dry gas sealing film stiffness testing device, characterized in that: include: A sealed cavity assembly, the sealed cavity assembly comprising a lower cavity, a middle cavity and an upper cavity, 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 comprising a fixing ring, the fixing ring being installed at the lower part of the upper cavity and located in the middle cavity; A compensation ring assembly, wherein the compensation ring assembly is located in the middle cavity, and the compensation ring assembly comprises 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 which are arranged in order from top to bottom; 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 to test the sealing end face gap of the dry gas sealing pair; the fixed ring and the compensation ring constitute 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, and the two ends of the elastic element are respectively abutted against the push ring assembly and the first movable ring seat assembly; a back pressure cavity is arranged 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 regulated online, and by regulating the gas pressure in the back pressure cavity, the compression amount of the elastic element can be indirectly changed to indirectly regulate the closing force exerted on the compensation ring; The bottom of the second movable ring seat assembly abuts against the force sensor, the space where the force sensor is located is connected to the second leakage chamber, and 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, a throttling gap is formed radially between the auxiliary labyrinth seal and the lower cavity, 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.

2. A supercritical carbon dioxide dry gas sealing air film stiffness testing device according to claim 1, characterized in that: It also includes a gas-assisted system, which includes a main sealing chamber air inlet pipeline, a back-pressure chamber air inlet pipeline, a safety pressure relief pipeline, a leakage gas collection pipeline and a parameter acquisition module; the main sealing chamber air inlet pipeline is connected to the main sealing chamber, the back-pressure chamber air inlet pipeline is connected to the back-pressure chamber, the safety pressure relief pipeline is connected to the first leakage chamber, the leakage gas collection pipeline is connected to the second leakage chamber, and the parameter acquisition module can collect data from the ranging component and the force sensor.

3. A supercritical carbon dioxide dry gas sealing air film stiffness testing device according to claim 2, characterized in that: A safety valve is provided on the safety pressure relief pipeline, and the safety valve is opened to automatically relieve pressure when the medium pressure in the first leakage chamber exceeds a preset threshold.

4. A supercritical carbon dioxide dry gas sealing air film stiffness testing device according to claim 2, characterized in that: A first pressure sensor and a first pressure regulating valve for measuring and controlling the pressure of the main sealing chamber are provided on the main sealing chamber air inlet pipeline, and a second pressure sensor and a second pressure regulating valve for measuring and controlling the pressure of the back pressure chamber are provided on the back pressure chamber air inlet pipeline; the parameter acquisition module can collect data from the first pressure sensor and the second pressure sensor.

5. A 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 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 to 5, characterized in that: A first ring platform is provided on the inner side of the compensation ring near its lower end surface, and a second ring platform is provided on the outer side of the compensation ring near its sealing end surface. 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. A supercritical carbon dioxide dry gas sealing air film stiffness testing device according to claim 6, characterized in that: There are multiple force sensors, and the multiple force sensors are arranged around the axis of the second movable ring seat at uniform intervals.

8. A supercritical carbon dioxide dry gas sealing film stiffness testing device according to claim 7, characterized in that: The distance measuring assembly includes a sensor mounting seat, a displacement sensor and a displacement sensor induction ring; the sensor mounting seat is installed on the inner diameter of the fixing ring, the displacement sensor is installed on the sensor mounting seat, and the displacement sensor induction ring is installed on the inner diameter of the compensation ring.

Images