A high pressure carbon ring seal

Abstract

The utility model relates to a high pressure carbon ring seal, including sealed cavity, multiple carbon ring subassembly, multiple exhaust ring, end cover, axle sleeve and sealing washer, the sealed cavity outer circle is ladder axle, its boss side is equipment side, the other side is atmospheric side, sealed cavity installs in equipment cavity, and atmospheric side outer circle cooperates with equipment cavity inner wall, multiple carbon ring subassembly and exhaust ring interval installation are in sealed cavity, end cover is put together in sealed cavity end face, and carbon ring subassembly and exhaust ring are pressed and fixed in sealed cavity bottom, sealed cavity, end cover and carbon ring subassembly outer circle all have sealing groove and install sealing washer, axle sleeve is sleeved in equipment spindle outer circle and passes through end cover, sealed cavity, carbon ring subassembly and exhaust ring inner hole, the utility model discloses under the premise of not prolonging the whole seal length, as far as possible increase carbon ring subassembly and the quantity of isolated gas inlet, seal multiple slow decompression, avoid appearing carbon ring under high pressure working condition and leading to the seal failure situation of being crushed.

Description

Technical Field

[0001] This utility model belongs to the field of sealing technology, and in particular relates to a high-pressure carbon ring seal for use in high-pressure compressors. Background Technology

[0002] In modern industry, steam turbines, gas turbines, compressors, and blowers are increasingly widely used. As a currently advanced international gas seal, carbon ring seals are gaining popularity in these devices due to their advantages such as easy installation, excellent sealing performance, simple maintenance and repair, and the elimination of complex lubrication and cooling systems. The sealing material in carbon ring seals is carbon graphite. Compared to metal materials, graphite itself has lower strength. Limited by the performance of carbon ring materials, carbon ring seals are generally only used in low-to-medium pressure applications below 100 kg. However, with technological advancements, the operating conditions of equipment such as compressors are becoming increasingly complex and demanding, placing higher requirements on the seals used in these devices. High-pressure equipment is becoming more common, some even exceeding 130 kg. To prevent toxic and harmful gases from leaking into the atmosphere, the equipment needs to apply an isolation gas at the seal with a pressure higher than that of the sealed gas to prevent leakage. This pressure level exceeds the pressure limit that graphite carbon rings can withstand.

[0003] Aside from material limitations, carbon ring seals are floating ring seals, a gas-throttling, non-contact seal. Their sealing principle relies on the formation of a gas film between the floating ring and the shaft sleeve, creating a throttling and pressure reduction that prevents high-pressure gas from flowing to the low-pressure side. During equipment operation, leaking gas and isolation gas inside the equipment will press the carbon ring against the low-pressure side within the carbon ring mounting groove. The side of the carbon ring is tightly pressed against the inner surface of one side of the mounting groove to prevent high-pressure gas from leaking along the side of the carbon ring. While the side of the carbon ring is pressed against the inner surface of the mounting groove, it also floats up and down under the action of the gas film within the shaft hole, ensuring no contact between the inner hole and the shaft surface, thus preventing friction between the shaft and the carbon ring and avoiding damage to the shaft surface. If the medium pressure is too high, the carbon ring will be tightly pressed against the side of the mounting groove and unable to float up and down with the shaft movement, causing severe friction damage between the shaft and the inner hole of the carbon ring. This results in an enlarged inner hole of the carbon ring, excessive leakage, and the carbon ring becoming ineffective. To reduce the pressure difference across a single carbon ring, the number of carbon rings must be increased, and an isolation gas inlet must be added. The isolation gas is then depressurized multiple times inside the seal to reduce the pressure difference across the carbon ring near the compressor. However, due to the limitations of the total length of the equipment, increasing the number of carbon rings and isolation gas inlets is not feasible. Therefore, conventional carbon ring seals cannot be used normally under this condition. Utility Model Content

[0004] To address the shortcomings of existing technologies, this utility model provides a high-pressure carbon ring seal. This carbon ring seal can maximize the number of carbon ring components and isolation gas inlets without extending the overall seal length, thereby ensuring multiple slow pressure reductions on the seal. This prevents the carbon ring from being crushed due to excessive pressure difference before and after the carbon ring under high-pressure conditions, which could lead to seal failure.

[0005] A high-pressure carbon ring seal includes a sealing cavity, multiple sets of carbon ring assemblies, multiple exhaust rings, an end cap, a bushing, and a sealing ring. The outer circle of the sealing cavity is a stepped shaft, with the boss side facing the equipment and the other side facing the atmosphere. The sealing cavity is installed inside the equipment cavity, with the outer circle on the atmosphere side fitting against the inner wall of the equipment cavity. Multiple carbon ring assemblies and exhaust rings are installed at intervals inside the sealing cavity. The end cap is fitted onto the end face of the sealing cavity and presses and fixes the carbon ring assemblies and exhaust rings against the bottom of the sealing cavity. The outer circles of the carbon ring assemblies, exhaust rings, and end caps fit into the inner holes of the sealing cavity. The outer circles of the sealing cavity, end caps, and carbon ring assemblies are all machined with sealing grooves and fitted with sealing rings. The bushing is fitted onto the outer circle of the equipment spindle and passes through the inner holes of the end cap, sealing cavity, carbon ring assemblies, and exhaust rings.

[0006] The sealing rings include standard O-rings and irregular O-rings. The irregular O-rings are formed by connecting several O-rings with two or more connecting ribs.

[0007] Multiple sealing grooves are machined on the outer circumference of the sealed cavity on the atmospheric side. An external isolation gas inlet cavity is machined between adjacent sealing grooves. The external isolation gas inlet cavity is connected to the isolation gas inlet on the equipment cavity one by one. Several internal isolation gas inlet cavities are machined in the inner hole of the sealed cavity. Each internal isolation gas inlet cavity is connected to the corresponding external isolation gas inlet cavity through a gas hole.

[0008] One or more of the aforementioned external isolation gas inlet chambers are provided with several sets of partitions, which divide an inlet chamber into several independent spaces, each corresponding to a different isolation gas inlet; between each set of partitions is a groove of the same width and depth as the sealing groove on both sides, and the two ends of the groove are respectively connected to the sealing groove on both sides, forming a special-shaped sealing ring groove.

[0009] Each set of partitions consists of two partitions, each of which is arranged axially parallel.

[0010] The inner hole of the sealed cavity has a stepped tapering structure, divided into three sections from the equipment side to the atmosphere side, with the diameter decreasing sequentially. The inner isolation air inlet cavity is machined in the middle section of the inner hole.

[0011] The carbon ring assembly includes a friction ring, multiple conical springs, a cylindrical pin, and a sealing ring. A countersunk hole for the sealing ring is machined on one side of the friction ring. Multiple conical spring countersunk holes are evenly distributed at the bottom of the countersunk hole for the sealing ring. Conical springs and sealing rings are installed sequentially in the countersunk holes for the conical springs and the countersunk holes for the sealing ring. The bottom end of the conical spring abuts against the bottom of the countersunk hole for the conical spring, and the top end of the conical spring is tightly attached to the back of the sealing ring. The cylindrical pin is installed at the bottom of the friction ring and inserted into the waist-shaped groove on the back of the sealing ring. A threaded hole is machined on the back of the friction ring, and a cylindrical pin is installed in the threaded hole.

[0012] The exhaust ring and end cap have countersunk holes machined on their atmospheric side faces. A cylindrical pin on the back of the friction ring is inserted into the countersunk hole to ensure that the carbon ring assembly and the exhaust ring do not rotate axially.

[0013] The atmospheric side end face of the end cap and the outer circle of the exhaust ring are both machined with air holes that pass through the outer circle of the bushing.

[0014] By employing the above technical solution, this utility model application has at least the following beneficial effects:

[0015] 1. This utility model divides an air intake chamber into two or more chambers by adding partitions to one or more isolation gas intake chambers within a sealed cavity. A special-shaped sealing ring is then installed between the partitions for sealing, transforming the original single sealed cavity into multiple completely independent air intake spaces. This increases the number of air intake channels. Different pressure isolation gas is supplied to the sealing rings in different sections of the special-shaped sealing ring through different isolation gas inlets, ensuring that the number of sealing rings and isolation gas inlets is increased as much as possible without extending the overall seal length. This allows for multiple, gradual pressure reductions in the seal. This improvement prevents a sudden drop in pressure from high pressure to atmospheric pressure across the sealing ring. Excessive pressure difference across the sealing ring can press the sealing ring tightly against the exhaust ring, causing excessive friction between them. Under this friction, the sealing ring cannot float freely with the spindle's movement, leading to severe wear between the inner hole of the sealing ring and the bushing. The inner hole of the sealing ring enlarges, losing its sealing function, or even the sealing ring collapses due to the material's inability to withstand the immense pressure.

[0016] 2. This utility model has a compact structure, requires no major modifications to the original equipment, and has low manufacturing costs. Attached Figure Description

[0017] Figure 1 This utility model provides a structural schematic diagram of a high-pressure carbon ring seal;

[0018] Figure 2 This is a front view of the irregular-shaped sealing ring in this utility model;

[0019] Figure 3 This is a side view of the irregular-shaped sealing ring in this utility model;

[0020] Figure 4 This is a schematic diagram of the sealed cavity of this utility model;

[0021] Figure 5 This is a schematic diagram of the carbon ring assembly structure of this utility model;

[0022] in:

[0023] 1-End cap, 11-Air hole, 2-Carbon ring assembly, 21-Tower spring, 22-Cylindrical pin, 23-Friction ring, 24-Sealing ring, 3-Sealing cavity, 31-First sealing groove, 32-Outer isolation gas inlet cavity I, 33-Second sealing groove, 34-Atmospheric side inlet cavity, 341-Outer isolation gas inlet cavity II, 342-Outer isolation gas inlet cavity III, 35-Third sealing groove, 36-Inner isolation gas inlet cavity III, 37-Inner isolation gas inlet cavity II, 38-Inner isolation gas inlet cavity I, 39-Partition plate, 310-Irregular sealing groove, 4-Exhaust ring, 5-Equipment cavity, 51-Isolation gas inlet port I, 52-Isolation gas inlet port II, 53-Isolation gas inlet port III, 6-Sealing ring, 61-Irregular sealing ring, 611-Connecting rib, 7-Screw, 8-Shaft sleeve, 9-Main shaft. Detailed Implementation

[0024] To better explain and facilitate understanding of this utility model, the technical solution and effects of this utility model will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] like Figures 1-4 As shown, a high-pressure carbon ring seal includes a sealing cavity 3, three sets of carbon ring assemblies 2, two exhaust rings 4, an end cap 1, a bushing 8, and a sealing ring 6. The outer circumference of the sealing cavity 3 is a stepped shaft, with its boss side facing the equipment side and the other side facing the atmosphere. Screw mounting holes are provided on the boss end face of the sealing cavity 3. Screws pass through these holes to fix the sealing cavity 3 inside the equipment cavity 5. The outer circumference of the atmosphere side mates with the inner wall of the equipment cavity 5. The three sets of carbon ring assemblies 2 and the two exhaust rings 4 are spaced apart within the sealing cavity 3, arranged axially along the main shaft of the equipment. The end cap 1 is secured to the end face of the sealing cavity 3 by screws 7, pressing and fixing the carbon ring assemblies 2 and exhaust rings 4 against the bottom of the sealing cavity 3, ensuring that they cannot move axially. The outer circumference of the carbon ring assembly 2, the exhaust ring 4, and the end cap 1 mates with the inner hole of the sealing cavity 3. Sealing grooves are machined on the outer circumferences of the sealing cavity 3, the end cap 1, and the carbon ring assembly 2, and sealing rings 6 are installed to ensure that gas inside the equipment does not leak outwards along the gaps between the parts. The bushing 8 is fitted onto the outer circumference of the main shaft 9 of the equipment and passes through the inner holes of the end cap 1, the sealing cavity 3, the carbon ring assembly 2, and the exhaust ring 4.

[0026] The sealing ring 6 includes a standard O-ring and a non-standard O-ring 61. In this embodiment, the non-standard O-ring 61 is H-shaped and consists of two standard O-rings and two O-ring connecting ribs 611 in the middle. In this embodiment, standard O-rings are installed in the sealing grooves on the outer circumference of the end cap 1 and the carbon ring assembly 2.

[0027] The outer circumference of the sealed cavity 3 on the atmospheric side is sequentially machined with a first sealing groove 31, an external isolation gas inlet cavity I 32, a second sealing groove 33, an atmospheric side inlet cavity 34, and a third sealing groove 35 from the equipment side to the atmospheric side. The external isolation gas inlet cavity I 32 communicates with the isolation gas inlet I 51 opened on the equipment cavity 5. The atmospheric side inlet cavity 34 is provided with two sets of partitions 39, each set including two partitions 39. The four partitions 39 are arranged axially parallel. Between each set of partitions 39 is a groove with the same width and depth as the second sealing groove 33 and the third sealing groove 35. The two ends of the groove communicate with the second sealing groove 33 and the third sealing groove 35 respectively, and together with the second sealing groove 33 and the third sealing groove 35, they form a special-shaped sealing ring groove 310. Two sets of partitions 39 divide the atmospheric side air intake chamber 34 into two independent spaces: the external isolation air intake chamber II 341 and the external isolation air intake chamber III 342. The external isolation air intake chamber II 341 is connected to the isolation air inlet II 52 opened on the equipment cavity 5, and the external isolation air intake chamber III 342 is connected to the isolation air inlet III 53 opened on the equipment cavity 5.

[0028] In this embodiment, a standard O-ring is installed in the first sealing groove 31, and an H-shaped special-shaped sealing ring 61 is installed in the special-shaped sealing ring groove. The two types of sealing rings ensure that the isolation gas entering each air inlet cavity will not leak along the gap between the outer circle of the sealing cavity 3 and the inner hole of the equipment cavity 5.

[0029] The inner hole of the sealing cavity 3 has a stepped tapering structure, divided into three sections from the equipment side to the atmosphere side, with the diameter decreasing sequentially. The middle section of the inner hole is sequentially machined with inner isolation gas inlet chamber I 38, inner isolation gas inlet chamber II 37, and inner isolation gas inlet chamber III 36 from the equipment side to the atmosphere side. Air holes 11 are provided between the outer isolation gas inlet chamber I 32 and the inner isolation gas inlet chamber I 38, the outer isolation gas inlet chamber II 341 and the inner isolation gas inlet chamber III 36, and the outer isolation gas inlet chamber III 342 and the inner isolation gas inlet chamber II 37. The air holes 11 respectively guide the isolation gas introduced from the isolation gas inlet I 51, the isolation gas inlet II 52, and the isolation gas inlet III 53 to the corresponding positions on the outer circle of the end cover 1 and the exhaust ring 4.

[0030] The end cap 1 and the outer circle of the exhaust ring 4 are both machined with air holes 11 that pass through the outer circle of the bushing 8. The air holes 11 guide the isolation gas in the inner isolation gas inlet chamber I 38, inner isolation gas inlet chamber II 37 and inner isolation gas inlet chamber III 36 to the gap between the outer circle of the bushing 8 and the inner hole of the carbon ring assembly 2.

[0031] like Figure 5As shown, the carbon ring assembly includes a friction ring 23, multiple stacked springs 21, a cylindrical pin 22, and a sealing ring 24. A countersunk hole for the sealing ring is machined on one side of the friction ring 23. Multiple stacked spring countersunk holes are evenly distributed at the bottom of the sealing ring countersunk hole. Stacked springs 21 and sealing rings 24 are sequentially installed in the stacked spring countersunk holes and sealing ring countersunk holes of the friction ring 23. The bottom end of the stacked spring 21 abuts against the bottom of the stacked spring countersunk hole, and the top end of the stacked spring 21 is tightly against the back of the sealing ring 24. The cylindrical pin 22 is installed at the bottom of the friction ring 23 and inserted into the waist-shaped groove on the back of the sealing ring 24 to prevent the sealing ring 24 from rotating. A threaded hole is machined on the back of the friction ring 23, and the cylindrical pin 22 is installed in the threaded hole.

[0032] The exhaust ring 4 and the end cap 1 have countersunk holes machined on their atmospheric side end faces. The cylindrical pin 22 on the back of the friction ring 23 in the carbon ring assembly 2 is inserted into the countersunk hole to ensure that the carbon ring assembly 2 and the exhaust ring 4 do not rotate axially.

[0033] The working process and principle of the above-mentioned high-pressure carbon ring seal are as follows:

[0034] The equipment cavity is sequentially supplied with isolation gas at decreasing pressures through each isolation gas inlet from the equipment side to the atmosphere side. The isolation gas pressure at inlet I is higher than the pressure of the medium inside the equipment, ensuring that the gas medium can only flow into the equipment and cannot leak to the atmosphere. The isolation gas pressure at inlet III is lower than that at inlet I, and the isolation gas pressure at inlet II is lower than that at inlet III. With each isolation gas inlet, the isolation gas pressure decreases from a high pressure to a lower level, with the pressure before and after the sealing ring 24 decreasing progressively until it reaches atmospheric pressure.

[0035] This application divides one air intake chamber into two or more chambers by adding a partition to one or more isolation gas intake chambers in the sealed cavity 3, and processes the original ordinary standard O-ring seal into a special-shaped seal 61: such as the H-type used in the above embodiment, that is, two O-ring seals are connected into a whole by two connecting ribs 611, thereby dividing the air intake groove formed by a sealing groove into two or even several separate air intake spaces, increasing the number of air intake channels, and supplying isolation gas of different pressures between the two isolation gas intake chambers separated by the connecting rib of the H-shaped special-shaped seal 61 through different isolation gas inlets, so as to ensure that the number of sealing rings 24 and isolation gas inlets is increased as much as possible without extending the overall sealing length, and the seal is slowly depressurized multiple times.

[0036] The above improvements can prevent the pressure across the sealing ring 24 from dropping directly from high pressure to atmospheric pressure. If the pressure difference across the sealing ring 24 is too large, the sealing ring 24 will be pressed tightly against the exhaust ring. If the friction between the sealing ring 24 and the exhaust ring is too large, the sealing ring 24 will not be able to float with the spindle movement. The inner hole of the sealing ring 24 will wear severely with the bushing. The inner hole of the sealing ring 24 will become larger and unable to seal. In some cases, the sealing ring 24 may even collapse due to the inability of the material to withstand the huge pressure.

Claims

1. A high pressure carbon ring seal characterized by: The device includes a sealed cavity, multiple carbon ring assemblies, multiple exhaust rings, an end cap, a bushing, and a sealing ring. The outer circumference of the sealed cavity is a stepped shaft, with the boss side facing the equipment and the other side facing the atmosphere. The sealed cavity is installed inside the equipment cavity, with the outer circumference on the atmosphere side fitting against the inner wall of the equipment cavity. Multiple carbon ring assemblies and exhaust rings are installed at intervals inside the sealed cavity. The end cap is fitted onto the end face of the sealed cavity and presses and fixes the carbon ring assemblies and exhaust rings against the bottom of the sealed cavity. The outer circumferences of the carbon ring assemblies, exhaust rings, and end caps fit into the inner holes of the sealed cavity. The outer circumferences of the sealed cavity, end caps, and carbon ring assemblies are all machined with sealing grooves and fitted with sealing rings. The bushing is fitted onto the outer circumference of the equipment main shaft and passes through the inner holes of the end cap, sealed cavity, carbon ring assemblies, and exhaust rings.

2. A high pressure carbon ring seal according to claim 1, wherein: The sealing rings include standard O-rings and irregular O-rings. The irregular O-rings are formed by connecting several O-rings with two or more connecting ribs.

3. A high pressure carbon ring seal according to claim 1, wherein: Multiple sealing grooves are machined on the outer circumference of the sealed cavity on the atmospheric side. An external isolation gas inlet cavity is machined between adjacent sealing grooves. The external isolation gas inlet cavity is connected to the isolation gas inlet on the equipment cavity one by one. Several internal isolation gas inlet cavities are machined in the inner hole of the sealed cavity. Each internal isolation gas inlet cavity is connected to the corresponding external isolation gas inlet cavity through a gas hole.

4. A high pressure carbon ring seal according to claim 3, wherein: One or more of the aforementioned external isolation gas inlet chambers are provided with several sets of partitions, which divide an inlet chamber into several independent spaces, each corresponding to a different isolation gas inlet; between each set of partitions is a groove of the same width and depth as the sealing groove on both sides, and the two ends of the groove are respectively connected to the sealing groove on both sides, forming a special-shaped sealing ring groove.

5. A high pressure carbon ring seal according to claim 4, wherein: Each set of partitions consists of two partitions, each of which is arranged axially parallel.

6. A high pressure carbon ring seal according to claim 1 wherein: The inner hole of the sealed cavity has a stepped tapering structure, divided into three sections from the equipment side to the atmosphere side, with the diameter decreasing sequentially. The inner isolation air inlet cavity is machined in the middle section of the inner hole.

7. A high pressure carbon ring seal according to claim 1 wherein: The carbon ring assembly includes a friction ring, multiple conical springs, a cylindrical pin, and a sealing ring. A countersunk hole for the sealing ring is machined on one side of the friction ring. Multiple conical spring countersunk holes are evenly distributed at the bottom of the countersunk hole for the sealing ring. Conical springs and sealing rings are installed sequentially in the countersunk holes for the conical springs and the countersunk holes for the sealing ring. The bottom end of the conical spring abuts against the bottom of the countersunk hole for the conical spring, and the top end of the conical spring is tightly attached to the back of the sealing ring. The cylindrical pin is installed at the bottom of the friction ring and inserted into the waist-shaped groove on the back of the sealing ring. A threaded hole is machined on the back of the friction ring, and a cylindrical pin is installed in the threaded hole.

8. A high pressure carbon ring seal according to claim 7, wherein: The exhaust ring and end cap have countersunk holes machined on their atmospheric side faces. A cylindrical pin on the back of the friction ring is inserted into the countersunk hole to ensure that the carbon ring assembly and the exhaust ring do not rotate axially.

9. A high pressure carbon ring seal according to claim 1 wherein: The atmospheric side end face of the end cap and the outer circle of the exhaust ring are both machined with air holes that pass through the outer circle of the bushing.

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