Fluid machine with optimized cooling of the slip ring seal

Abstract

The present invention relates to a fluid machine having a housing and a shaft rotating in the housing, wherein the shaft is sealed relative to the housing by means of at least one slip ring seal, and the rotation of the shaft generates a swirling flow of working fluid in the region of the slip ring seal, characterized in that at least one drive member driven by the shaft is provided in the immediate vicinity of the slip ring seal, the drive member being used to generate a secondary flow superimposed on the fluid flow in the region of the slip ring seal for convective cooling of the slip ring seal.

Description

Technical Field

[0001] The present invention relates to a fluid machine having a housing and a shaft rotating in the housing, wherein the shaft is sealed relative to the housing by means of at least one slip ring seal, and the rotation of the shaft generates a swirling flow of working fluid in the region of the slip ring seal. Summary of the Invention

[0002] Fluid machinery includes all machines that are traversed by a working fluid or a fluid loaded with solid matter and are equipped with bladed impellers for converting mechanical energy (e.g., the rotational energy of a shaft) into flow energy (e.g., the total pressure of the fluid). Depending on the direction of energy transfer—whether from the shaft of the fluid machinery to the flowing medium or from the medium to the shaft—a distinction is made between "working machinery" (e.g., centrifugal pumps, turbine compressors, fans) and "power machinery" (e.g., steam turbines, gas turbines, wind turbines, liquid turbines, and especially hydraulic turbines).

[0003] The extension of a rotating shaft from the housing of fluid machinery is typically sealed reliably and safely using slip ring seals. Heat generated by friction at the sealing contact of the slip ring seal can cause localized temperature rise; to extend the seal's service life and improve its reliability, this localized temperature rise should be minimized.

[0004] Cooling of slip ring seals by means of the working fluid flowing around the seal is often insufficient, influenced by structural design and application. In particular, unfavorable flow conditions may arise in the slip ring seal region due to structural design, resulting in inadequate heat dissipation by means of the working fluid. The formation of localized vortices and / or recirculation zones in the slip ring seal region can, for example, cause the heat absorbed by the working fluid in the slip ring seal to be transported only locally and circulated, rather than being carried away from the slip ring seal and released to the housing. In practice, this situation has so far been addressed by external cooling circuits specifically designed to cool the seal. However, external circuits require additional structural measures, which increases mechanical complexity and raises manufacturing and maintenance costs.

[0005] The following should be based on Figure 1The diagram illustrates the unfavorable flow conditions in the area of ​​the slip ring seal mentioned above. This diagram only shows the relevant section of the housing 1 of the fluid machinery along with the slip ring seal installed there. A portion of the rotating working shaft 5 of the fluid machinery, particularly a centrifugal pump, can be seen. The shaft 5 extends outward from the housing at one end, and the shaft extension is sealed by a slip ring seal consisting of a stationary mating ring 3 and a slip ring 4. The stationary mating ring 3 is fixed to the housing 1 by a mating bracket 2, wherein the connection is sealed by a static seal 9. The rotating slip ring 4 is anti-rotationally mounted on the shaft 5. Reference numeral 6 indicates the static seal, and reference numeral 7 indicates a preload element by which the slip ring 4 is preloaded axially toward the mating ring 3. Furthermore, a sealing gap 8 is provided in the housing 1 toward the pump bearing housing, through which the working fluid can reach the area of ​​the slip ring seal from the pump space. The rotating shaft generates a swirling flow of the working fluid in the area of ​​the slip ring seal.

[0006] Specifically, the descending surface profile 4a of the rotating slip ring 4 towards the stationary mating ring 3 causes localized vortices 11 to form in the immediate vicinity of the slip ring seal within the housing space. These localized vortices are separated from the remaining flow 13 of the working fluid by the jet 12 extending radially / axially outward from the slip ring seal towards the housing. Due to the locally confined vortex / recirculation 11, the heat energy absorbed by the working fluid there and generated by frictional work in the sealing contact cannot be effectively dissipated, as heat exchange can only occur at the interface between the vortex 11 and the jet 12. The same applies to particles worn off from the sliding surface. In addition to the vortices 11, several smaller, undesirable vortices 14 are also generated due to the separation of the inner and outer profiles of the housing 1 and the mating support 2, particularly in angular regions or in the regions of radial steps, especially in the axial transition between rings 3 and 4.

[0007] The object of this invention is to achieve improved flow of the working fluid in the region of the slip ring seal through structural measures, thereby enabling better heat dissipation and cooling of the slip ring seal. Furthermore, the convective transport of particles from the slip ring seal contact region should be optimized.

[0008] This objective is achieved by a fluid machine having the features of claim 1. Starting from the fluid machine of this type, it is proposed that at least one shaft-driven drive member be disposed in the immediate vicinity of the slip ring seal, the drive member being adapted to generate a secondary flow superimposed on the swirling flow in the region of the slip ring seal. By arranging an additional, shaft-rotating drive member immediately adjacent to the slip ring seal and by appropriately designing the drive member, a specifically defined secondary flow can be actively generated in the region of the slip ring seal, which ensures improved heat removal and / or particle removal because it prevents the formation of localized unfavorable vortices and enables efficient convective removal of heat energy by the working fluid. Convective removal of abrasive particles in the region of the sealing contact is also facilitated, i.e., improved flushing of the slip ring seal is achieved. The secondary flow is particularly a wide-range flow circulating within the available structural space of the housing. The swirling flow of the working fluid in the region of the slip ring seal can be generated by the rotating shaft.

[0009] Fluid machinery can be pumps, especially centrifugal pumps.

[0010] At least one drive member can be placed directly on the shaft, or instead arranged on a member that rotates with the shaft, such as on a preload element of a slip ring for axial preload rotation. The drive member can be designed as a rotating disk or a rotating bladed impeller. Preferably, the rotating drive member or these rotating drive members are designed such that a pressure ratio is generated near the slip ring seal, which, in addition to the swirling of the working fluid, also constructs one or more secondary flows with axial and radial components. One or more secondary flows are directed to the most critical surfaces of the slip ring seal assembly that require cooling. Not only the axial flow component, but also the radial flow component should be understood as the flow direction relative to the axis. In particular, at least one secondary flow is directed to the surface of the slip ring seal, especially the surface of the ring of the slip ring seal. Targeted guidance along the relevant surfaces of the mating support is also conceivable.

[0011] Particularly advantageous is the arrangement of one or more flow guiding members in the space between the slip ring seal and the housing, particularly in the radial and / or axial space. Thus, for example, such flow guiding members can be arranged in the center of the space between the outer housing wall and the slip ring seal. The flow guiding members extend not only in the axial direction but also in the radial direction, preferably extending annularly around the slip ring seal within the housing space. Such flow guiding members enable cyclic secondary flow in a flow path formed by the flow guiding members themselves and optionally one or more other members, such as the housing, slip ring, preload element, or mating support. For example, it is conceivable that such flow guiding members define an axial flow channel between the housing wall and the flow guiding members, and a channel extending parallel to this axial flow channel between the slip ring seal and the flow guiding members. The radial section of the flow channel is preferably formed by the end surface of the housing or by the mating support and the flow guiding members.

[0012] The material used as the flow guiding member can be designed as a solid material or alternatively as a hollow material. The possible cavity can preferably be filled with a working fluid or other fluid or material. The support of the flow guiding member in the fluid machinery can preferably be achieved through one or more fixing points, by which the member is fixed to the inner wall of the housing or to a mating support of the slip ring seal. Particularly advantageously, the member has an internal structure with optimized thermal conductivity and / or one or more fixing points have high thermal conductivity, thereby ensuring good heat dissipation from the member to the housing or mating support.

[0013] Of particular advantage is that, based on the embodiments of the invention, the external circuit for cooling and / or flushing the slip ring seal can be completely eliminated, and cooling and / or flushing of the slip ring seal can be provided solely by the working fluid.

[0014] Furthermore, it is possible to provide one or more guiding elements in the region of the housing wall adjacent to the secondary flow or slip ring seal, and / or in the region of the mating support of the stationary mating ring, and / or in the region of the drive component, and / or in the region of the pre-tightening device, and / or in the region of the ring of the slip ring seal, in order to avoid the formation of undesirable vortices in corner regions or at radial steps. For example, it is conceivable to optimize the corners and edges of the housing components or the transitions between different components, especially the transitions between slip rings, so as to minimize radial steps and, for example, avoid localized unfavorable vortices due to flow separation.

[0015] Similarly, it is conceivable to optimize the heat exchange of surfaces wetted by the working fluid through appropriate texture structures or other microscopic or macroscopic properties. Suitable surface design can also improve the achievable drag effect of drive components. Attached Figure Description

[0016] Further advantages and features of the invention will now be explained in more detail with reference to the embodiments shown in the accompanying drawings. Wherein: Figure 1 A schematic structure of a fluid machine according to the prior art is shown. Figure 2 An embodiment of a fluid machine according to the invention is shown. Detailed Implementation

[0017] It has already been described in detail in the opening section. Figure 1 Therefore, a repeated description is omitted here. The fluid machinery according to the invention and Figure 1 The same components in the same implementation scheme are indicated by the same reference numerals. The following discussion will primarily focus on modifications made to optimize the flow pattern of the working fluid in the region of the slip ring seal.

[0018] Figure 2 The diagram shows the relevant section of the centrifugal pump. Relative to... Figure 1 The main modification of the implementation scheme lies in the provision of a rotating drive member 20 actively driven by the shaft 5. This drive member can be designed, for example, as a disc with a viscous drag effect or a bladed impeller. The rotating member 20 is used to generate a pressure ratio near the slip ring seal, which causes the formation of one or more secondary flows (including axial and radial flow components in addition to swirling flow), thereby selectively guiding the working fluid to the most critical, coolable surfaces of the slip ring seal assembly. The drive member 20 is here positioned circumferentially around the preload element 7 and rotates with the shaft 5 during normal operation of the fluid machinery, but alternatively, it can also be mounted directly on the shaft. It is also conceivable that the preload element 7 itself or specific sections of the shaft 5 can also be used as drive members, with certain modifications to their outer contours.

[0019] Generated by rotating drive component 20 Figure 2The flow path, indicated by arrows, has axial and radial components and circulates around a flow guide member 50 located at the center of the radial space between the housing 1 and the slip ring seals 30 and 40. The flow guide member 50 can be made of a solid material or designed to be hollow, wherein, in the latter case, the member 50 can be filled with working fluid or other fluids or materials. The flow guide member 50 is supported at the housing 1 by a plurality of fixing points (not shown here) and extends circumferentially around the shaft or slip ring seal. The internal structure of the flow guide member 50 and the fixing points are optimized for heat dissipation, and they are particularly made of materials with high thermal conductivity, such as aluminum or copper. The outer contour of the flow guide member 50 is preferably designed for one or more operating points and / or ranges of operating points of the fluid machinery.

[0020] As can be seen from the diagram, secondary flow is generated in the region of the housing end facing the pump bearing housing via the drive member 20, and first flows axially towards the mating bracket 2 between the flow guide member 50 and the circumferential wall of the housing 1. The guide element 21 in the regions of the housing corners and edges, or in the transition region to the mating bracket 2, minimizes undesirable vortex formation in the step and edge regions, and thereby ensures a non-separating flow deflection with high flow velocities. In the region of the mating bracket 2, the working fluid is guided radially downward toward the slip ring seal and there flows axially back to the drive member 20 between the flow guide member 50 and the slip rings 30, 40 together with the preload element 7.

[0021] Furthermore, the circumferential surfaces 30a and 40a of slip rings 30 and 40 are optimized in terms of flow technology to avoid radial steps in the transition region and thereby further minimize the risk of forming local vortices. An embodiment of the surface profile of the circumferential surface 30a of the stationary mating ring 30 enables seamless flow deflection towards the rotating slip ring 40, thereby allowing the working fluid to flow along profiles 30a and 40a at the highest possible flow velocity (Reynolds number). The surface profile 40a of the rotating slip ring 40 prevents the generation of undesirable axial / radial jets. In particular, the profile of the circumferential surface of the slip ring is adapted to the profile of the opposing surface of the flow guiding member 50.

[0022] The secondary flow circulating in a large space can effectively remove the heat energy absorbed in the region of slip rings 30 and 40 from the slip ring seal and release it outward, for example, through the flow guiding member 50 and its heat-conducting fixed point.

[0023] The following is a summary of the main features of the modification schemes for fluid machinery in the slip ring seal area.

[0024] The objective of this invention is to specifically design a flow state through structural measures that optimizes the convective cooling of the slip ring seal and thereby reduces the temperature within and near the sealing contact. Here, the flow should be generated as rapidly as possible (high Reynolds number) in the form of a secondary flow superimposed on the swirling flow, having axial and radial velocity components along the surface to be cooled. Therefore, this flow state forms an internal loop that is generated without requiring additional active equipment.

[0025] The secondary flow is driven by the rotational motion itself. Here, the fluid's adhesion to the rotating wall, combined with the rotational inertia (centrifugal force), can be fully utilized. Specifically, at edges with increased surfaces compared to a uniform profile, such as at edges of cross-sectional transitions or in disc-shaped areas, a drag effect based on fluid adhesion can be used to generate a radial velocity component. This can be achieved using the profile 40a of the rotating slip ring seal, the surface of the pre-tightening device 7, or the surface of the component 20 additionally mounted on the shaft 5 or the pre-tightening device 7 for this purpose. Flow guidance can be achieved by one or more components 21, 50, mounted in the radial space between the shaft 5 / slip ring seal 30, 40 and the housing 1, and connected to the housing 1 and / or the stationary mating support 2 at one or more points. Targeted flow guidance along the slip ring seal 30, 40 also enables optimized and controlled removal of particles (e.g., particles generated in the contact area or from other sources and deposited there), and, if necessary, targeted delivery of these particles to the filtration device. In this invention, no external joints, additional fluid loops, or additional heat exchange devices are required. Instead, cooling is achieved internally through targeted flow guidance driven by rotational motion (as the energy source).

[0026] Built-in components 20, 21, and 50 can be integrated not only during the initial design of the slip ring seal but also subsequently added to existing products. The built-in components can be optimized for specific operating points (speed, pressure, temperature, fluid density, and viscosity) and / or operating point ranges, such as the primary operating points or ranges reached.

[0027] The wetted surface of the built-in component can be optimized for heat exchange with the fluid, for example, through texture or other microscopic and macroscopic surface properties. Furthermore, surface properties can be intentionally configured to produce better drag on the fluid. Heat transferred from the fluid to the built-in component 50 can be discharged from the slip ring seal area through heat transfer within the built-in component 50 and through the connection of the built-in component to the housing 1, the mating bracket 2, or, if necessary, the shaft 5. The built-in component can be made of one or more materials and manufactured using various processes, such as die casting (aluminum), injection molding (plastic), 3D printing, and machining (turning and milling).

Claims

1. A fluid machine having a housing (1) and a shaft (5) rotating within the housing, wherein, The shaft (5) is sealed relative to the housing (1) by means of at least one slip ring seal (30, 40), and the rotation of the shaft generates a swirling flow of the working fluid in the region of the slip ring seal. Its features are, At least one drive member (20) driven by the shaft (5) is provided in the immediate vicinity of the slip ring seal (30, 40), the drive member being used to generate at least one secondary flow of the working fluid superimposed on the region of the slip ring seal (30, 40) for convective cooling of the slip ring seal (30, 40).

2. The fluid machinery according to claim 1, characterized in that, The drive member (20) is arranged on the preload element (7), which is used to preload the rotating slip ring (40) of the slip ring seal in the axial direction.

3. The fluid machinery according to any one of the preceding claims, characterized in that, The resulting secondary flow has axial and radial flow components.

4. The fluid machinery according to any one of the preceding claims, characterized in that, The secondary flow is directed along the surfaces (30a, 40a) of the rings (30, 40) of the slip ring seal.

5. The fluid machinery according to any one of the preceding claims, characterized in that, In order to guide the secondary flow, one or more flow guiding members (50) are arranged in the space between the slip ring seal (30, 40) and the housing (1).

6. The fluid machinery according to claim 5, characterized in that, The secondary flow circulates around at least one of the flow guiding members (50).

7. The fluid machinery according to any one of claims 5 or 6, characterized in that, The at least one flow guiding member (50) is hollow or completely filled, especially by means of the working fluid or filled with other fluids or materials.

8. The fluid machinery according to any one of claims 5 to 7, characterized in that, The at least one flow guide member (50) is fixed at the housing (1) and / or at the mating bracket (2) of the stationary mating ring (30) of the slip ring seal by one or more fixing points.

9. The fluid machinery according to claim 8, characterized in that, The internal structure of the at least one flow guiding member (50) and / or the one or more fixing points are optimized for heat dissipation, that is, they have good thermal conductivity so that the heat released by the secondary flow can be released through the fixing points to the housing (1) and / or the mating bracket (2).

10. The fluid machinery according to any one of the preceding claims, characterized in that, The fluid machinery does not have an external circuit for cooling and / or flushing the slip ring seal.

11. The fluid machinery according to any one of the preceding claims, characterized in that, The driving component (20) is a rotating disk with a viscous drag effect, or a rotating bladed impeller, or a different rotating structure used to generate the pressure gradient required to drive the secondary flow.

12. The fluid machinery according to any one of the preceding claims, characterized in that, Reduce the radial steps in the transition region between different contours in the secondary flow region, especially minimize the radial steps in the transition region between the rings (30, 40) of the slip ring seal.

13. The fluid machinery according to any one of the preceding claims, characterized in that, The surface wetted by the working fluid is optimized for heat exchange by means of texture structure or other micro or macro properties.

14. The fluid machinery according to any one of the preceding claims, characterized in that, One or more guide elements (21) for non-separating flow guidance are provided in the corner or transition region of the housing (1) and / or the mating bracket (2) of the stationary mating ring (30), and / or in the region of the drive member (20), and / or in the region of the pre-tightening device (7), and / or in the region of the ring (30, 40).

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