Sealing assembly and vertical pump / mixer comprising the same

Abstract

A seal assembly for sealing a rotor shaft for a vertical axis pump / mixer against liquid flow between a housing and the rotor shaft, comprising: a stator bushing to be fastened to the housing; and an upper seal pair and a lower seal pair, both comprising a pair of seal rings forming a sliding surface between the pair of seal rings and the seal rings being slidable against each other, in each of the pair of seal rings a first seal ring being fixedly coupled to the stator bushing and a second seal ring being rotatable and coupled to the rotor shaft, the sliding surfaces of both the upper seal pair and the lower seal pair being cooled / lubricated by a sealing liquid when in use. The stator bushing comprises a sleeve forming a weir configured for an annular volume of sealing liquid, the stator bushing being provided with a fluid passage opening into the annular volume for providing sealing liquid to the annular volume, the height of the weir being greater along an axial direction than the height of the sliding surface of the upper seal pair, such that the sealing liquid level is higher than the sliding surface of the upper seal pair.

Description

Technical Field

[0001] This invention relates to a sealing assembly as described in the preamble of claim 1. This application generally relates to sealing assemblies, and more particularly to configurations and mechanisms for improving the effectiveness of seals in various industrial applications. Related fields include liquid mixing (e.g., dissolving, emulsifying, or dispersing) and pumping.

[0002] The present invention also relates to a vertical pump / mixer as described in the preamble of the second independent claim. Background Technology

[0003] Patent document EP0443473 discloses a turbo compressor shaft seal, particularly for a high-pressure turbo compressor, in which each of its gas-side and atmospheric-side sliding rings is biased toward the rotor ring of the shaft and associated with a liquid-blocking compartment, which is interconnected by an annular passage around the rotor ring. The compartments are connected in a closed-loop path with a circulating pump and a cooler, and leakage is returned to the liquid circulation section by a feed pump via a pressure transducer biased on one side by the pressure of the gas to be sealed and an adjustable spring force, and on the other side by the pressure of the liquid blockage. The surface area ratio K between the region of the atmospheric-side sliding ring biased toward the rotor ring by the liquid blockage pressure and the sealing region of the atmospheric-side sliding ring is substantially 0.45 to 0.60, and the thermal conductivity of the sliding ring and the rotor ring is greater than 250,000 N / mm². 2 Furthermore, its thermal conductivity is greater than 70 W / mK. However, this method exhibits limitations.

[0004] This application addresses the problem of preventing fluid leakage between the housing and rotor shaft in vertical axis pumps and mixers. The object of this invention is to provide a sealing assembly in which performance is significantly improved compared to prior art solutions. Summary of the Invention

[0005] The objectives of the present invention can be satisfied substantially as disclosed in the independent claims and in other claims that describe various embodiments of the invention in more detail.

[0006] This application provides a solution for maintaining an effective seal in environments where variations in rotational speed and pressure can damage conventional sealing methods. In particular, pump / mixer startup is one of the moments when conventional seals are likely to dry-run, causing significant wear or even damage. In some studies, approximately 70% of pump / mixer failures are due to mechanical seals. The most common cause of mechanical seal failure is dry-running of the sliding surface. This invention prevents dry-running by ensuring that cavitation cannot form on the upper sliding surface of double / twin mechanical seals. The design incorporates a stator bushing with a weir that creates an annular volume for the sealing fluid, ensuring the sealing surface remains lubricated and cooled. Additionally, the integration of fluid channels for a consistent sealing fluid supply and a filtration system to prevent contamination addresses the challenge of maintaining seal integrity over time, thereby reducing the risk of operational failure and increasing equipment lifespan.

[0007] The embodiments of the present invention are associated with various advantages and / or technical effects.

[0008] According to embodiments of the present invention, a sealing assembly for sealing a rotor shaft of a vertical axis pump / mixer to prevent fluid flow between the housing and the rotor shaft is disclosed. The sealing assembly includes: a stator bushing to be fastened to the housing; and an upper seal and a lower seal, both comprising a pair of sealing rings forming a sliding surface between the pair of sealing rings and the sealing rings being slidable against each other. In each of the pair of sealing rings, a first sealing ring is fixedly coupled to the stator bushing, while a second sealing ring is rotatably coupled to the rotor shaft. During use, the sliding surfaces of both the upper and lower seal pairs are cooled / lubricated with a sealing fluid. The stator bushing includes a sleeve forming a weir, the weir configuring an annular volume for sealing fluid. The stator bushing is provided with a fluid passage leading to the annular volume for supplying sealing fluid to the annular volume. The height of the weir in the axial direction is greater than the level of the sliding surface of the upper seal pair, such that the sealing fluid level is higher than the sliding surface of the upper seal pair.

[0009] The weir, which forms an annular volume for sealing fluid, ensures consistent and reliable accumulation of the sealing fluid, which improves cooling and lubrication of sliding surfaces, thereby reducing wear and extending the service life of the seal.

[0010] The height of the weir, which is greater in the axial direction than the height of the sliding surface of the upper seal pair, creates hydrostatic pressure. This hydrostatic pressure improves the sealing efficiency, thereby preventing liquid leakage over the seal and ensuring the integrity of pump or mixer operation.

[0011] Providing a fluid passage to the annular volume allows for a controlled and stable supply of the sealing fluid. This fluid passage can be customized to the operating requirements of the pump or mixer, thereby optimizing performance and reducing maintenance needs.

[0012] The watertightness of the sealing assembly provides the following advantages: it prevents liquid leakage between the housing and the rotor shaft, thereby ensuring efficient operation of the vertical axis pump / mixer.

[0013] The conductive properties of the sliding surface allow for effective heat dissipation, which improves the lifespan and performance of the sealing assembly during operation.

[0014] The flow rate of the sealing fluid ensures optimal lubrication and cooling of the sealing ring, thereby reducing wear and maintaining the integrity of the sealing surface.

[0015] Using a filtration system to prevent contaminants from condensing offers the advantage of maintaining a clean, sealed liquid environment, thereby extending the lifespan of the sealing components.

[0016] The layered design of the sealing components allows for effective management of the sealing fluid level, thereby ensuring consistent performance and reliability under a variety of operating conditions.

[0017] In one development, the component further includes a sealing fluid maintained at a constant pressure by an external pressure source. Maintaining the sealing fluid at a constant pressure by an external pressure source ensures a stable sealing environment that can adapt to fluctuations in operating conditions without compromising the effectiveness of the seal. The constant pressure of the sealing fluid minimizes the risk of vaporization or cavitation at the sealing surface, which can cause damage and lead to premature failure of the sealing assembly. The external pressure source can be adjusted to compensate for changes in process conditions or wear on the sealing surface, thereby maintaining optimal sealing performance over time and reducing downtime.

[0018] In one development, the component further includes a fluid channel terminating axially in the annular volume. This axially terminating fluid channel provides a direct path for the sealing fluid to reach the sealing surface, ensuring efficient cooling and lubrication without the need for complex wiring or additional components. The axial orientation of the fluid channel facilitates a more streamlined design for the stator bushing, potentially reducing manufacturing complexity and cost. The axial fluid channel design can also contribute to a more balanced distribution of the sealing fluid, resulting in more uniform wear of the sealing rings and improved reliability of the sealing assembly.

[0019] In one development, the component further includes a fluid channel terminating radially into an annular volume. This radially terminating fluid channel allows for a compact design of the sealing assembly, which can be beneficial in applications where space constraints are a concern. The radial orientation of the fluid channel provides a more uniform distribution of the sealing fluid around the circumference of the sealing ring, thus promoting consistent cooling and lubrication. The radial fluid channel design also facilitates easier access for maintenance or inspection of the sealing assembly, as it eliminates the need to disassemble components axially aligned with the rotor shaft.

[0020] In one development, the assembly further includes a stator bushing comprising a guide for positioning the stator bushing in the correct annular position relative to the housing during installation. The inclusion of a guide for positioning the stator bushing in the correct annular position relative to the housing ensures precise alignment during installation, which is crucial for the proper operation of the sealing assembly and, in particular, for sealing fluid flow. Proper annular positioning of the stator bushing reduces the likelihood of seal misalignment, which can lead to uneven wear, leakage, and potential seal failure. The guide simplifies the installation process, reducing the time and skill required to install the sealing assembly, which can result in labor cost savings and reduce the potential for installation errors.

[0021] In one development, the component further includes a fluid channel equipped with a filtration system to prevent contaminants from entering the annular volume. Including a fluid channel with a filtration system improves the reliability of the component by preventing contaminants from entering the annular volume, thereby reducing the risk of damage or wear to the sealing components. The filtration system within the fluid channel ensures the purity of the sealing fluid, which can lead to improved sealing performance and lifespan of the seal, thus minimizing maintenance requirements and operational downtime.

[0022] A vertical axis pump / mixer is disclosed, comprising a sealing assembly for sealing a rotor shaft of the vertical axis pump / mixer to prevent fluid flow between a housing and the rotor shaft. The sealing assembly includes: a stator bushing to be fastened to the housing; and an upper seal and a lower seal, both comprising a pair of sealing rings forming a sliding surface between the pair of sealing rings and the sealing rings being slidable against each other. In each of the pair of sealing rings, a first sealing ring is fixedly coupled to the stator bushing, while a second sealing ring is rotatably coupled to the rotor shaft. During use, the sliding surfaces of both the upper and lower seals are cooled / lubricated with a sealing fluid. The stator bushing includes a sleeve forming a weir, the weir configuring an annular volume for sealing fluid. The stator bushing is provided with a fluid passage leading to the annular volume for supplying sealing fluid to the annular volume. The height of the weir is greater than the height of the sliding surfaces of the upper seal pair, such that the sealing fluid level is higher than the sliding surfaces of the upper seal pair.

[0023] The stator bushing, configured with a sleeve that forms a weir (creating an annular volume for the sealing fluid), ensures a consistent and adequate supply of the sealing fluid to the sliding surfaces. This reduces friction and wear, thereby extending the service life of the seal. The design of the fluid passage leading to the annular volume allows for efficient delivery of the sealing fluid, ensuring proper lubrication and cooling of the sliding surfaces during operation, resulting in improved performance and a reduced risk of overheating.

[0024] In one development, the mixer further includes a sealing fluid supply system connected to the housing. This integration of the sealing fluid supply system to the housing provides dedicated and controlled flow of the sealing fluid to the sealing assembly, which optimizes seal performance and prevents contaminant ingress. The sealing fluid supply system facilitates easy maintenance and replenishment of the sealing fluid, which improves operational management and ensures that the sealing assembly operates within its intended parameters for maximum efficiency.

[0025] In vertical axis pumps / mixers, a constant pressure of the sealing fluid is maintained by an external pressure source. Using an external pressure source to regulate the sealing fluid pressure allows for precise control of the sealing conditions, thereby adapting to changing operational needs and improving the overall reliability and performance of the pump / mixer.

[0026] The exemplary embodiments of the invention presented in this patent application shall not be construed as limiting the applicability of the appended claims. The verb "comprising" is used in this patent application as an open-ended limitation, which does not exclude features that are present or not described. Unless expressly stated otherwise, the features described in the dependent claims may be freely combined with each other. Novel features considered characteristic of the invention are specifically set forth in the appended claims. Attached Figure Description

[0027] In the following description, the invention will be illustrated with reference to the accompanying exemplary schematic drawings, in which: Figure 1 The diagram illustrates an overview of a vertical mixer. Figure 2 The figure shows a cross-sectional view of a vertical pump including the sealing assembly. Figure 3 The illustration shows a sealing assembly according to an embodiment of the present invention. Figure 4 An embodiment of the fluid channel is illustrated.

[0028] The term "rotor shaft" is used in this document to refer to the shaft that rotates the rotor or impeller of a vertical axis pump / mixer.

[0029] The term "casing" is used in this document to refer to the housing used for the rotor shaft.

[0030] The term "stator bushing" is used herein to refer to a sealing assembly that includes a sealing ring and fluid passages, in the case of a vertical axis pump / mixer, where the stator bushing is fixed to the housing.

[0031] The term "seal" is used to refer to a seal that prevents fluid from flowing between the housing and the rotor shaft.

[0032] The terms “upper seal pair” and “lower seal pair” refer to a pair of sealing rings that are fixedly connected to each other and are in the upper or lower position when installed and used.

[0033] The term "sealing ring" refers to a pair of sealing rings that can move relative to each other and are connected to each other.

[0034] The term "first sealing ring" refers to a sealing ring that is fixedly connected to the stator bushing and is not rotatable.

[0035] The term "second sealing ring" refers to the sealing ring that is attached to the rotor shaft and rotates along the rotor shaft.

[0036] The term "fluid channel" refers to a fluid passage leading to an annular volume for supplying a sealing fluid to the annular volume.

[0037] The term "toroidal volume" is used in this article to refer to the volume of liquid that is in the form of a toroid.

[0038] The term "sleeve" refers to the shape or portion of an annular volume extending axially from the stator bushing and configured to seal the fluid. The term "weir" refers to the uppermost surface of the sleeve, which is configured to seal the annular volume of fluid. The height of the weir defines the position of the sealing fluid surface axially.

[0039] The term "vertical axis pump / mixer" refers to a pump or mixer having a vertically oriented rotor shaft and a housing or device configured for mixing liquids.

[0040] The term "sealing fluid" refers to a fluid used for sealing, cooling, and lubricating sealing rings.

[0041] The term "axial direction" refers to the axis of rotation parallel to the longitudinal axis, and the term "vertical direction" refers to the axis of rotation parallel to the longitudinal axis.

[0042] The term "constant pressure" refers to a pressure that is kept constant by an external pressure source.

[0043] The term "correct annular position" refers to the annular position of the stator bushing relative to the housing during installation, such that the fluid passages extending from the housing to the stator bushing are aligned both circumferentially and axially.

[0044] The term "guide device" refers to any device that can be used to set the stator bushing in the correct annular position during installation.

[0045] The term "filtration system" is used in this document to refer to a system that can filter contaminants from a sealed liquid to prevent contaminants from entering the annular volume. Detailed Implementation

[0046] Figure 1 A vertical axis mixer 13 for mixing liquids in a mixing container 130 is schematically depicted. A rotor 20 is connected to a rotor shaft, which is further connected to a gear G and a motor M. A housing 3 is provided at the top of the container where the rotor shaft passes through the container wall to rotatably connect the rotor shaft 2 to the container 130. A sealing assembly 1 is used between the rotor shaft 2 and the housing to prevent liquid leakage and to prevent liquid flow between the housing 3 and the rotor shaft 2.

[0047] Figure 2 A vertical axis pump 13 is schematically depicted, including a sealing assembly 1 for sealing the rotor shaft 2 of the vertical axis pump / mixer 13 to prevent fluid flow between the housing 3 and the rotor shaft 2. The sealing assembly 1 includes: a stator bushing 4 to be fastened to the housing 3; and an upper seal pair 6 and a lower seal pair 7, both of which are cooled / lubricated with a sealing fluid SL during use. The sealing assembly 1 also prevents pumped fluid from entering the bearing 21, which allows the rotor shaft 2 to rotate relative to the housing 3.

[0048] Figure 3 A schematic depiction of the rotor shaft 2 used to seal a vertical axis pump / mixer to prevent liquid from entering the housing ( Figure 3 A cross-sectional view of the sealing assembly 1 flowing between the rotor shaft 2 and the housing (not shown in the image). The sealing assembly 1 includes: a stator bushing 4 to be fastened to the housing; and a double seal 5 including an upper seal pair 6 and a lower seal pair 7. Each seal pair includes a pair of sealing rings 8, forming a sliding surface between the two sealing rings 8 and the sealing rings 8 being slidable against each other. In each of the two sealing rings 8, a first sealing ring 9 is fixedly coupled to the stator bushing 4, while a second sealing ring 10 is rotatable and coupled to the rotor shaft 2. When in use, the sliding surfaces 60, 70 of both the upper seal pair 6 and the lower seal pair 7 are cooled / lubricated with a sealing fluid SL. The stator bushing 4 includes a sleeve 14 forming a weir 15, which is configured with an annular volume 12 for sealing liquid SL. The stator bushing 4 is provided with a fluid passage 11 leading to the annular volume 12 for supplying sealing liquid SL to the annular volume 12. The height of the weir 15 is greater in the axial direction than the height 61 of the sliding surface 60 of the upper seal pair 6, such that the level of sealing liquid SL is higher than the sliding surface 60 of the upper seal pair 6.

[0049] exist Figure 3 The illustration shows an embodiment in which the fluid channel 11 terminating in the annular volume 12 is axial. Therefore, the fluid channel 11 leads to the bottom of the annular volume 12. Alternatively, the fluid channel 11 may terminate in the annular volume 12 radially, such as... Figure 4 As shown in the diagram. Essentially, these are equivalent alternatives, but it depends on which construction of the housing and stator bushing is more advantageous.

[0050] One aspect of the design is that the stator bushing 4 includes guides for positioning the stator bushing 4 in the correct annular position relative to the housing 3 during installation. As the fluid passage 11 passes through the housing and continues to the stator bushing 4, these two sections of the fluid passage 11 need to be aligned with each other. Positioning is straightforward in the axial direction, with opposing notches of different diameters present in both the housing and the stator bushing. However, since the sealing assembly is more or less rotationally symmetrical in shape, it is recommended that some type of guide be provided to ensure the correct annular position. This could be a cotter pin, a wedge, a groove for the cotter pin / wedge, or some other similar structure that forces the annular or circumferential position to be correct. The stator bushing 4 includes a plurality of O-rings 40 to seal the stator bushing 4 to the housing 3 during installation.

[0051] According to an embodiment not shown in the figure, the sealing fluid SL is maintained at a constant pressure by an external pressure source (i.e., a sealing fluid supply system 16 that supplies sealing fluid to the fluid passage 11). The stator bushing 4 includes an outlet for the sealing fluid. The outlet for the sealing fluid is located at a vertical level between the sliding surface 70 of the lower seal pair and the weir 15, such that even if the sealing fluid supply system is not pumping, there will be a small accumulation of sealing fluid located in the annular volume 12 and realized through the lower seal pair 70, so that neither the upper seal pair 6 nor the lower seal pair 7 may be dry-operating.

[0052] While the invention has been described herein by way of example with reference to embodiments currently considered to be the most preferred embodiments, it will be apparent to those skilled in the art that the basic ideas of the invention can be implemented in many ways as technology advances. Therefore, the invention and its embodiments are not limited to the examples and samples described above, but may vary within the scope of the patent claims and their legal equivalents. When such a combination is technically feasible, the details mentioned in conjunction with any of the foregoing embodiments may be used in conjunction with another embodiment.

[0053] List of reference numerals 1 Sealing assembly 2. Rotor shaft 20 Rotor / Impeller 21 bearings 3. Shell 4. Stator bushing 40 O-ring 5. Seals 6. Upper seal pair 60 Sliding surfaces of the upper seal pair 7. Lower seal pair 70 Sliding surfaces of the lower seal pair 8. Sealing ring 9 First sealing ring 10 Second sealing ring 11 Fluid Channels 12. Circular volume 13 Vertical Axis Pump / Mixer 130 containers 14 Sleeves 15 Weir 16 Sealed liquid supply system SL Sealed Liquid VA is the vertical axis.

Claims

1. A sealing assembly (1) for sealing a rotor shaft (2) of a vertical axis pump / mixer (13) to prevent liquid flow between a housing (3) and the rotor shaft (2), the sealing assembly (1) comprising: The stator bushing (4) to be fastened to the housing (3); and the upper seal pair (6) and the lower seal pair (7), both comprising a pair of sealing rings (8) forming a sliding surface between the pair of sealing rings (8) and the sealing rings (8) being able to slide against each other, in each of the pair of sealing rings (8), the first sealing ring (9) being fixedly coupled to the stator bushing (4), while the second sealing ring (10) being rotatable and coupled to the rotor shaft (2), the sliding surfaces (60, 70) of both the upper seal pair (6) and the lower seal pair (7) being sealed with a sealing fluid during use. (SL) Cooling / Lubrication, characterized in that the stator bushing (4) includes a sleeve (14) forming a weir (15), the weir being configured with an annular volume (12) for sealing liquid (SL), the stator bushing (4) being provided with a fluid passage (11) leading to the annular volume (12) for supplying sealing liquid (SL) to the annular volume (12), the height of the weir (15) being greater in the axial direction than the height of the sliding surface (60) of the upper seal pair (6), such that the level of sealing liquid (SL) is higher than the sliding surface (60) of the upper seal pair (6).

2. The sealing assembly (1) according to claim 1, wherein, The sealing fluid (SL) is kept at a constant pressure by an external pressure source.

3. The sealing assembly (1) according to claim 1, wherein, The fluid channel (11) terminating in the annular volume (12) is along the axial direction.

4. The sealing assembly (1) according to claim 1, wherein, The fluid channel (11) terminating in the annular volume (12) is in the radial direction.

5. The sealing assembly (1) according to any one of the preceding claims, wherein, The stator bushing (4) includes a guide device for positioning the stator bushing (4) in the correct annular position relative to the housing (3) during installation.

6. The sealing assembly (1) according to any one of the preceding claims, wherein, The fluid channel (11) is equipped with a filtration system to prevent contaminants from entering the annular volume (12).

7. The sealing assembly according to any one of the preceding claims, wherein, The stator bushing (4) includes a plurality of O-rings 40 for sealing the stator bushing (4) to the housing (3) during installation.

8. The sealing assembly according to any one of the preceding claims, wherein, The stator bushing (4) includes an outlet for the sealing liquid (SL).

9. The sealing assembly according to claim 8, wherein, The outlet for the sealing liquid is located at a vertical height between the sliding surface (70) of the lower seal pair and the weir (15).

10. A vertical axis pump / mixer (13) comprising a sealing assembly (1) for sealing a rotor shaft (2) of the vertical axis pump / mixer (13) to prevent liquid flow between a housing (3) and the rotor shaft (2), the sealing assembly (1) comprising: The stator bushing (4) to be fastened to the housing (3); and the upper seal pair (6) and the lower seal pair (7), both comprising a pair of sealing rings (8) forming sliding surfaces (60, 70) between the pair of sealing rings (8) and the sealing rings (8) being able to slide against each other, in each of the pair of sealing rings (8), the first sealing ring (9) being fixedly coupled to the stator bushing (4), while the second sealing ring (10) being rotatable and coupled to the rotor shaft (2), the sliding surfaces (60, 70) of both the upper seal pair (6) and the lower seal pair (7) being used in operation. A sealing liquid (SL) cooling / lubrication, characterized in that the stator bushing (4) includes a sleeve (14) forming a weir (15), the weir being configured with an annular volume (12) for the sealing liquid (SL), the stator bushing (4) being provided with a fluid passage (11) leading to the annular volume (12) for supplying the sealing liquid (SL) to the annular volume (12), the height of the weir (15) being greater in the axial direction than the height of the sliding surface (60) of the upper seal pair (6), such that the level of the sealing liquid (SL) is higher than the sliding surface (60) of the upper seal pair (6).

11. The vertical axis pump / mixer (13) according to claim 10, wherein, A sealing liquid (SL) supply system (16) is connected to the housing (3).

12. The vertical axis pump / mixer (13) according to claim 10, wherein, The sealing fluid (SL) is kept at a constant pressure by an external pressure source.

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