Gas working medium rotating shaft sealing device and method for judging working condition of sealing structure

Abstract

The invention relates to the field of mechanical engineering, in particular to a gas working medium rotating shaft sealing device and a method for judging the working condition of a sealing structure, and the sealing device comprises an end cover which is used for being matched with a working medium cavity so as to fix a rotating shaft and enable the rotating shaft to rotate along the axis; one end of the rotating shaft is arranged in the working medium cavity, and the other end extends out of the working medium cavity; the first sealing structure is arranged on one side, close to the working medium cavity, of the end cover and is in slidable sealing contact with the peripheral surface of the rotating shaft; the second sealing structure is arranged on one side, far away from the working medium cavity, of the end cover and is in slidable sealing contact with the peripheral surface of the rotating shaft; the first sealing structure and the second sealing structure define a containing space in the end cover. The end cover is provided with a leakage channel in the radial direction, and the leakage channel extends into the containing space. And the pressure relief alarm device is arranged on the leakage channel and is configured to actively relieve pressure and / or give an alarm when the air pressure in the accommodating space is greater than a preset value.

Description

Technical Field

[0001] The invention relates to the field of mechanical engineering, and in particular to a gas working medium rotary shaft sealing device and a method for judging the working condition of a sealing structure. Background Art

[0002] For gas working medium rotating machinery, the power drive shaft (such as centrifugal compressor, screw compressor, vane compressor, scroll compressor, Roots supercharger, etc.) or power output shaft (such as various positive displacement organic Rankine cycle expanders, natural gas turbo expanders, etc.) exposed outside the mechanical equipment body is the most likely mechanical part to cause working medium gas leakage. In order to avoid leakage of gas working medium, a sealing device is usually installed on the rotating shaft, although the sealing methods of the rotating shaft vary according to the working medium pressure, shaft speed, and working medium type (such as mechanical seal, dry gas seal, skeleton seal, skeleton-free lip seal, filler seal, etc.).

[0003] by Figure 1 For example, when the rotating shaft seal device (A) of the gas working fluid rotating machinery shown in the figure just starts to leak slightly, it is difficult for people to detect it in time. It can only be discovered when the leakage is large, such as by frequently applying soap solution every day, installing expensive corresponding working fluid gas sensors, etc. This will cause property losses when the working fluid gas with relatively expensive value leaks, and it will also bring major safety hazards when facing flammable and explosive working fluid gases. Summary of the invention

[0004] The present invention provides a gas working medium rotating shaft sealing device, comprising: an end cover, used to cooperate with a working medium chamber to fix the rotating shaft and enable the rotating shaft to rotate along the axis; one end of the rotating shaft is arranged in the working medium chamber, and the other end extends outside the working medium chamber; a first sealing structure is arranged on a side of the end cover close to the working medium chamber, and is in slidable sealing contact with the outer peripheral surface of the rotating shaft; a second sealing structure is arranged on a side of the end cover away from the working medium chamber, and is in slidable sealing contact with the outer peripheral surface of the rotating shaft; the first sealing structure and the second sealing structure enclose a containing space in the end cover; the end cover is radially provided with a leakage channel, and the leakage channel extends into the containing space; a pressure relief alarm device is arranged on the leakage channel, and is configured to actively relieve pressure and / or issue an alarm when the gas pressure in the containing space is greater than a preset value.

[0005] In some embodiments, the second sealing structure comprises a replaceable lip-tooth sealing ring; wherein the pressure value of the gas leakage resistance of the first sealing structure is greater than the pressure value of the gas leakage resistance of the second sealing structure.

[0006] In some embodiments, the pressure relief alarm device includes a micro-pressure safety valve, which is configured to release gas when the air pressure in the accommodation space is greater than a first preset pressure value, or to release gas manually; wherein the first preset pressure value is less than the pressure value of the gas leakage resistance of the second sealing structure.

[0007] In some embodiments, the alarm device includes a passive micro-pressure buzzer, and the passive micro-pressure buzzer works when the air pressure in the accommodation space is greater than a second preset pressure value; wherein the second preset pressure value is less than the first preset pressure value.

[0008] In some embodiments, the alarm device comprises a pressure gauge.

[0009] In some embodiments, the end cover is further provided with an oil drain hole along the radial direction.

[0010] The present invention also provides a method for judging the working condition of a sealing structure, which is used to judge the working condition of the first sealing structure in the aforementioned gas working medium rotary shaft sealing device, comprising: step 1, calculating the amount of gas discharged in one opening and closing cycle of the micro-pressure safety valve, including: Defining the gas equation ; Wherein, P represents the pressure in the accommodation space; V represents the volume of the accommodation space; n represents the molar amount of the working fluid gas in the accommodation space; R represents the gas constant; T represents the temperature of the working fluid gas in the accommodation space; Assuming that the working gas temperature remains unchanged, based on the gas state equation, the molar amount n of the working gas in the containing space at the moment the micro-pressure safety valve is opened is determined as ; Determine the molar amount n' of the working fluid gas in the containing space at the moment of closing the micro-pressure safety valve: ; Wherein, P' represents the pressure in the containing space at the moment when the micro-pressure safety valve is closed, and ; Step 2, calculate the gas leakage rate; assuming that the time of an opening and closing cycle of the micro-pressure safety valve is Δt, the leakage rate ; Step 3: When the leakage rate is greater than a leakage rate threshold, it is indicated that the first sealing structure needs to be repaired or replaced.

[0011] The present invention also provides a gas working fluid rotating machinery, comprising a rotating shaft, a working fluid chamber and the aforementioned gas working fluid rotating shaft sealing device, wherein the gas working fluid rotating shaft sealing device is detachably mechanically connected to the working fluid chamber; the rotating shaft passes through the end cover and is used to rotate driven by the gas working fluid.

[0012] In some embodiments, the installation portion of the rotating shaft corresponding to the second sealing structure is at least quenched; the surface hardness of the installation portion is greater than 58HRC, and the surface roughness is not less than 0.8μm.

[0013] The technical solution of the present invention has at least the following beneficial effects: (1) The structure is simple, the cost is low, and the implementation is easy. It can be directly modified on the existing equipment. (2) The gas leakage can be directly observed, and the alarm or pressure relief can be issued in time, thereby avoiding safety hazards and reducing the labor intensity of manual inspection. (3) It has strong adaptability to various rotating shaft main sealing devices, can predict the sealing status in advance, and judge whether the seal needs to be replaced or repaired at a low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0015] Figure 1 It is a structural schematic diagram of an existing gas working medium rotary machine; Figure 2 This is a schematic structural diagram of a gas working medium rotary shaft sealing device in a working state according to an embodiment of the present invention; Figure 3 Schematic diagram of the cross-sectional structure of the end cover of the gas working medium rotary shaft sealing device in an embodiment of the present invention.

[0016] In the figure: A-rotating shaft sealing device; 1-bearing; 2-end cover O-ring; 3'-end cover; 4-first sealing structure; 5-sealing structure sleeve; 6'-leakage channel; 7'-second sealing structure; 8'-lip-tooth seal ring gland; 9-oil drain hole; 10-rotating shaft; 15-accommodating space; 16-auxiliary oil drain hole; 20-pressure relief alarm device; 11-micro-pressure safety valve; 12-passive micro-pressure buzzer; 13-fastening bolts; 14-pressure gauge. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0018] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. In addition, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0020] Example refer to Figure 2 , Figure 2 This is a schematic diagram of the working state of the gas working medium rotating shaft sealing device provided by the present invention.

[0021] The gas working fluid rotary machine may include a rotating shaft, a working fluid chamber and a gas working fluid rotating shaft sealing device, wherein the gas working fluid rotating shaft sealing device is separably mechanically connected to the working fluid chamber; the rotating shaft passes through the end cover and is used to rotate driven by the gas working fluid.

[0022] In order to improve the sealing effect of the gas working medium rotary shaft sealing device and timely detect the leakage of more expensive working medium gas (such as inert gas, etc.) and flammable and explosive working medium gas (such as hydrogen or oxygen, etc.), this specification provides a gas working medium rotary shaft sealing device, which includes a bearing 1, an end cover O-ring 2, an end cover 3', a first sealing structure 4, a sealing structure sleeve 5, a leakage channel 6', a second sealing structure 7', a lip-tooth seal ring gland 8', an oil leakage hole 9, a rotating shaft 10, a containing space 15, an auxiliary oil leakage hole 16, a pressure relief alarm device 20, a micro-pressure safety valve 11, a passive micro-pressure buzzer 12, a fastening bolt 13 and a pressure gauge 14. It should be noted that in order to save space, some process structures (such as the fastening bolt 13) and supporting structures (such as the lip-tooth seal ring gland 8') are no longer described in detail.

[0023] Combined with Figure 3 The end cover 3' is used to cooperate with the working medium cavity to fix the rotating shaft 10 and enable the rotating shaft 10 to rotate along the axis; one end of the rotating shaft 10 is arranged in the working medium cavity, and the other end extends outside the working medium cavity.

[0024] The first sealing structure 4 is arranged on the side of the end cover 3' close to the working medium cavity, and is in slidable sealing contact with the outer peripheral surface of the rotating shaft 10. The first sealing structure 4 can be implemented by adopting a variety of sealing technologies, such as mechanical sealing, dry gas sealing, skeleton sealing, etc., depending on the working medium pressure, shaft speed and working medium type. In some embodiments, the first sealing structure 4 can be Figure 1 The sealing device (A) of the rotating shaft 10 is consistent with that of the conventional equipment (such as Figure 1 Directly retrofit on gas working medium rotating machinery).

[0025] The second sealing structure 7' is arranged on the side of the end cover 3' away from the working medium chamber, and is in slidable sealing contact with the outer peripheral surface of the rotating shaft 10. The second sealing structure 7' is used to provide an early warning when a micro-leakage occurs in the main sealing device.

[0026] Since the purpose of the second sealing structure 7' is not to achieve secondary sealing, but to facilitate the observation of micro-leakage, in some embodiments, the second sealing structure 7' includes a replaceable lip-tooth seal. Specifically, the second sealing structure 7' can be a frameless lip-tooth seal. The installation of the frameless lip-tooth seal will not increase the rotational resistance of the rotating shaft 10 too much. Therefore, in some embodiments, the interference should be smaller. Correspondingly, the pressure value of the gas leakage resistance of the first sealing structure 4 is greater than the pressure value of the gas leakage resistance of the second sealing structure 7', such as the pressure value of the gas leakage resistance of the first sealing structure 4 is more than 10 times the pressure value of the gas leakage resistance of the second sealing structure 7'.

[0027] The first sealing structure 4 and the second sealing structure 7 ′ enclose a receiving space 15 in the end cover 3 ′; the end cover 3 ′ is radially provided with a leakage channel 6 ′, which extends into the receiving space 15 .

[0028] The pressure relief alarm device 20 is disposed on the leakage channel 6' and is configured to actively relieve pressure and / or sound an alarm when the air pressure in the accommodation space 15 is greater than a preset value. The preset value may include a first preset pressure value and a second preset pressure value, etc., which may be determined by the mechanical manual and are not limited in this specification.

[0029] It should be noted that the volume of the leakage channel 6 ′ can be ignored, or it can be regarded as a part of the accommodating space 15 to facilitate subsequent calculations.

[0030] In some embodiments, the pressure relief alarm device 20 includes a micro-pressure safety valve 11, which is configured to release gas when the gas pressure in the accommodating space 15 is greater than a first preset pressure value, or to release gas manually.

[0031] In some embodiments, the first preset pressure value is less than the gas leakage resistance pressure value of the second sealing structure 7' to avoid leakage of the second sealing structure 7' before pressure relief. Preferably, the gas leakage resistance pressure value of the second sealing structure 7' is at least twice the first preset pressure value.

[0032] In some embodiments, the micro-pressure safety valve 11 or the entire pressure relief alarm device 20 can be arranged at a position far away from the gas working medium rotating machinery to facilitate the direct discharge or recovery of toxic or flammable and explosive gases.

[0033] In some embodiments, the alarm device includes a passive micro-pressure buzzer 12. When the air pressure in the accommodation space 15 is greater than a second preset pressure value, the passive micro-pressure buzzer 12 works. The passive micro-pressure buzzer 12 does not require independent power supply and does not affect the pressure of the accommodation space 15. It is suitable for modification of existing gas working medium rotating machinery.

[0034] In some embodiments, the second preset pressure value is less than the first preset pressure value, that is, the air pressure in the accommodation space 15 is too high (greater than the second preset pressure value but less than the first preset pressure value), and a buzzer sound and / or an alarm are issued, and when the pressure is further increased (exceeding the first preset pressure value), active pressure relief is performed. In some embodiments, when an alarm is issued, an alarm instruction can also be sent at the same time, so as to remind through other devices such as light, electricity, etc.

[0035] In some embodiments, the alarm device further comprises a pressure gauge 14, which can be used to monitor the sealing condition and obtain the actual pressure reading for subsequent calculations.

[0036] Considering the reduction of rotation resistance and the increase of the service life of the second sealing structure 7', a small amount of lubricating oil not exceeding the center line of the rotating shaft may be placed in the accommodating space 15 to prevent the sealing device from heating up, or in the case where a small amount of lubricating oil has passed through the first sealing structure 4, in some embodiments, the end cover 3' is further provided with an oil drain hole 9 along the radial direction for the discharge of the lubricating oil. In addition, in order to facilitate the manual active discharge of the lubricating oil from the leakage channel 6', in some embodiments, the end cover may also be provided with an auxiliary oil drain hole 16 along the radial direction.

[0037] In some embodiments, the leakage channel 6' can also be actively replenished with lubricating oil regularly to ensure the normal operation of the equipment.

[0038] In order to ensure the good operation of the gas working medium rotary machinery and reduce the influence of the second sealing structure 7', in some embodiments, the installation part of the rotating shaft 10 corresponding to the second sealing structure 7' is at least quenched; the surface hardness of the installation part is greater than 58 HRC, and the surface roughness is not less than 0.8 μm.

[0039] In mechanical engineering, perfect sealing does not exist. The gas working medium rotary shaft sealing device can detect leakage in time and discharge or recycle it as needed by storing and monitoring the gas working medium slightly leaked from the first sealing structure in the accommodation space. The structure is simple, easy to modify on the existing device, and can reduce the leakage loss of gas working medium, avoid safety hazards, and reduce the labor intensity of manual detection.

[0040] This specification also provides a method for judging the working condition of a sealing structure, which is used to judge the working condition of a first sealing structure. Specifically, the method includes: Step 1, calculate the amount of gas discharged in one opening and closing cycle of the micro-pressure safety valve, including: Defining the gas equation ; Wherein, P represents the pressure in the accommodation space; V represents the volume of the accommodation space; n represents the molar amount of the working fluid gas in the accommodation space; R represents the gas constant; and T represents the working fluid gas temperature in the accommodation space. The pressure in the accommodation space can be obtained by, for example, a pressure gauge, the volume of the accommodation space can be calculated by the design value of the device, and the gas constant can be directly obtained according to the actual situation of the working fluid gas.

[0041] Assuming that the working gas temperature (T) remains unchanged, based on the gas state equation, the molar amount n of the working gas in the space of the micro-pressure safety valve at the moment of opening is determined as ; Determine the molar amount n' of the working gas in the space of the micro-pressure safety valve at the moment of closing: ; Wherein, P' represents the pressure in the accommodation space of the micro-pressure safety valve at the moment of closing, and ; Step 2: Calculate the gas leakage rate; Assuming that the time of one opening and closing cycle of the micro-pressure safety valve is Δt, the leakage rate ; The unit of leakage rate is mol / s (mole per second).

[0042] Step 3: When the leakage rate is greater than the leakage rate threshold, it is indicated that the first sealing structure needs to be repaired or replaced. The leakage rate threshold can be specified before the gas working medium rotating machine according to the actual working environment or determined by manual inspection.

[0043] Through this judgment method, the first sealing structure can be monitored at low cost according to the state of the micro-pressure safety valve, and repaired or replaced in time to reduce losses.

[0044] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A gas working medium rotating shaft sealing device, include: An end cover is used to cooperate with the working medium cavity to fix the rotating shaft and enable the rotating shaft to rotate along the axis; one end of the rotating shaft is arranged in the working medium cavity, and the other end extends outside the working medium cavity; A first sealing structure, provided on a side of the end cover close to the working medium chamber, and in slidable sealing contact with the outer peripheral surface of the rotating shaft; A second sealing structure is provided on a side of the end cover away from the working medium chamber and is in slidable sealing contact with the outer peripheral surface of the rotating shaft; The first sealing structure and the second sealing structure enclose a containing space in the end cover; the end cover is provided with a leakage channel in a radial direction, and the leakage channel extends into the containing space; The pressure relief alarm device is arranged on the leakage channel and is configured to actively relieve pressure and / or sound an alarm when the air pressure in the accommodating space is greater than a preset value.

2. The gas working medium rotary shaft sealing device according to claim 1, wherein the second sealing structure comprises a replaceable lip-tooth sealing ring; in, The pressure value of the first sealing structure to resist gas leakage is greater than the pressure value of the second sealing structure to resist gas leakage.

3. The gas working medium rotary shaft sealing device according to claim 1, wherein the pressure relief alarm device comprises a micro-pressure safety valve, and the micro-pressure safety valve is configured to release gas when the gas pressure in the accommodating space is greater than a first preset pressure value, or to release gas manually; in, The first preset pressure value is less than the pressure value of the second sealing structure that can withstand gas leakage.

4. The gas working medium rotary shaft sealing device according to claim 3, wherein the alarm device comprises a passive micro-pressure buzzer, and when the air pressure in the accommodation space is greater than a second preset pressure value, the passive micro-pressure buzzer operates; in, The second preset pressure value is smaller than the first preset pressure value.

5. The gas working medium rotating shaft sealing device according to claim 3, in: The alarm device also includes a pressure gauge.

6. The gas working medium rotating shaft sealing device according to claim 1, in: The end cover is also provided with an oil drain hole along the radial direction.

7. A method for judging the working condition of a sealing structure, used for judging the working condition of a first sealing structure in the gas working medium rotary shaft sealing device according to claim 3, include: Step 1, calculating the amount of gas discharged during one opening and closing cycle of the micro-pressure safety valve, comprising: Defining the gas equation ; Wherein, P represents the pressure in the accommodation space; V represents the volume of the accommodation space; n represents the molar amount of the working fluid gas in the accommodation space; R represents the gas constant; T represents the temperature of the working fluid gas in the accommodation space; Assuming that the working gas temperature remains unchanged, based on the gas state equation, the molar amount n of the working gas in the containing space at the moment the micro-pressure safety valve is opened is determined as ; Determine the molar amount n' of the working fluid gas in the containing space at the moment of closing the micro-pressure safety valve: ; Wherein, P' represents the pressure in the containing space at the moment when the micro-pressure safety valve is closed, and ; Step 2, calculate the gas leakage rate; assuming that the time of an opening and closing cycle of the micro-pressure safety valve is Δt, the leakage rate ; Step 3: When the leakage rate is greater than a leakage rate threshold, it is indicated that the first sealing structure needs to be repaired or replaced.

8. A gas working fluid rotating machine, comprising a rotating shaft, a working fluid chamber and a gas working fluid rotating shaft sealing device as described in any one of claims 1 to 6, wherein the gas working fluid rotating shaft sealing device is detachably mechanically connected to the working fluid chamber; the rotating shaft passes through the end cover and is used to rotate driven by the gas working fluid.

9. The gas working medium rotary machine according to claim 8, wherein the installation portion of the rotating shaft corresponding to the second sealing structure is at least quenched; the surface hardness of the installation portion is greater than 58HRC, and the surface roughness is not less than 0.8μm.

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