EP4635631A1

EP4635631A1 - Centrifugal separator

Info

Publication number: EP4635631A1
Application number: EP24170424.6A
Authority: EP
Inventors: Kasper HÖGLUND
Original assignee: Alfa Laval Corporate AB
Current assignee: Alfa Laval Corporate AB
Priority date: 2024-04-16
Filing date: 2024-04-16
Publication date: 2025-10-22
Also published as: WO2025219036A1

Abstract

The disclosure concerns a centrifugal separator (2) comprising a stationary structure (4) delimiting a bowl space (10), a bowl (12), a spindle (14), and a sealing arrangement (32). The sealing arrangement (32) is configured for providing a sealing of the bowl space (10) around the rotational axis (16). A stationary sealing portion (36) of the sealing arrangement comprises a first sealing member (40) provided with a first sealing surface (42). A rotatable sealing portion (38) of the sealing arrangement comprises a second sealing member (44) provided with a second sealing surface (46). The first sealing member (40) is provided with at least one duct (48) extending between an outer surface (50) of the first sealing member (40) and an inner surface (52) of the first sealing member (40). A fluid supply path (54) extends from the stationary structure (4) via the at least one duct (48) to the bowl (12).

Description

TECHNICAL FIELD

The invention relates to a centrifugal separator.

BACKGROUND

The field of high-speed centrifugal separators with centrifuge bowls connected to spindles represents an aspect of industrial processes reliant on fluid separation. Within this context, the operation of these separators involves the continuous feeding of a fluid mixture into a separation space within the bowl, where it is then separated into distinct phases. These phases, typically a light and a heavy phase, are continuously conducted from the separation space. In certain applications, such as those involving sludge separation, an additional phase is intermittently discharged from the bowl's periphery.
To enable such discharge, mechanisms e.g., including axially movable slides are employed within the bowl body to intermittently open outlet openings for the sludge phase. The manipulation of these slides is controlled by the regulation of an operating liquid, ensuring efficient separation of the desired phases.
In the realm of hermetical centrifugal separators, which demand sealed environments for operation, challenges arise when additional fluids, like the aforementioned operating liquid, need to be introduced into the bowl during operation. Existing solutions, characterized by mechanical hermetical seals, employ stationary and rotatable sealing portions arranged around the rotational axis of the centrifugal separator. These sealing portions establish a mechanical hermetic seal of one or more of an inlet for the feed mixture, outlets for the light and heavy phases, and an interior space forming a bowl space within a casing of the centrifugal separator, the bowl being arranged in the bowl space.
However, the integration of mechanisms for introducing additional fluids while maintaining such hermetic sealing poses a challenge.
For the purpose of sealing a space within a casing, US 2020/306767A1 discloses a disc-type centrifuge configured to use clean water as sealing water to be supplied at high pressure to a sealing mechanism unit, thereby preventing foreign matter from entering the space inside the casing of the centrifuge and the processing objects (separated solids, etc.) from leaking out of the space inside the casing. The sealing water (clean water) is circulated between a sealing water tank and the sealing mechanism unit by a pump. The sealing mechanism unit is composed of a mechanical sealing mechanism including a rotating ring (seal ring), upper and lower fixed rings, and a sealing housing. In the region sealed by the sealing housing, sealing water (clean water) is supplied via a supply path formed in the sealing housing.

SUMMARY

It would be advantageous to enable the admission of an additional fluid to the centrifuge bowl within a mechanically hermetically sealed centrifugal separator. To better address this concern a centrifugal separator having the features defined in the independent claim is provided.
According to an aspect, there is provided a centrifugal separator comprising a stationary structure delimiting a bowl space, a bowl delimiting a separation space, a spindle connected to the bowl, and a sealing arrangement. The bowl and the spindle are configured to rotate about a rotational axis. The bowl is arranged within the bowl space and the spindle extends into the bowl space from an outside of the bowl space. The sealing arrangement is configured for providing a sealing of the bowl space around the rotational axis, wherein the sealing arrangement comprises a stationary sealing portion arranged around the rotational axis in the stationary structure and a rotatable sealing portion arranged around the rotational axis and to rotate with the bowl and the spindle. The stationary sealing portion comprises a first sealing member provided with a first sealing surface. The rotatable sealing portion comprises a second sealing member provided with a second sealing surface. The first and second sealing surfaces are arranged in sealing abutment. The first sealing member is provided with at least one duct extending between a radially outer surface of the first sealing member and a radially inner surface of the first sealing member. A fluid supply path extends from the stationary structure via the at least one duct to the bowl.
Since the stationary first sealing member is provided with at least one duct extending between the radially outer surface of the first sealing member and the radially inner surface of the first sealing member, and since the fluid supply path extends from the stationary structure via the at least one duct to the bowl - a fluid can be introduced into the bowl via the stationary first sealing member of the sealing arrangement.
Thus, the sealing arrangement not only forms a seal between the rotating parts of the centrifugal separator and the bowl space but also provides part of the fluid supply path utilised for leading an additional fluid into the bowl i.e., a fluid other than the process fluids being feed and separated in the centrifugal separator. Further advantages are e.g., a compact design since there is no need for a separate member for providing the fluid supply path to the bowl and the supply of the additional fluid can be controlled from outside the bowl since the fluid supply path leads from the stationary structure to the bowl.
The centrifugal separator is a high-speed centrifugal separator i.e., the spindle and bowl, forming the rotational system of the centrifugal separator, rotate at several thousand rotations per minute, such as at 3000 - 12000 rpm, during use of the centrifugal separator.
The stationary structure may comprise a casing or a housing, inside which the bowl space is formed. The spindle and the bowl may be driven to rotate about the rotational axis by a drive arrangement comprising e.g., an electric motor.
When the centrifugal separator is positioned for use thereof, the axial extension of the rotational axis may extend in a vertical direction. Accordingly, the bowl may have an upper portion and a lower portion.
Herein, terms like axial and radial relate to the rotational axis. For instance, an axial direction extends in parallel with the rotational axis of the rotor and a radial direction intersects the rotational axis and extends perpendicularly thereto. A circumferential or rotational direction extends around the rotational axis.
During use of the centrifugal separator, separation of a fluid feed mixture is performed in the separation space of the bowl. A separation aid e.g., comprising a stack of frustoconical separation discs, may be arranged in the separation space.
During use of the centrifugal separator, the fluid feed mixture is led into the separation space concentrically with the rotational axis or radially close to the rotational axis. A separated light phase is led out of the separation space concentrically with the rotational axis or radially close to the rotational axis. According to some examples, a separated heavy phase is led out of the separation space radially close to the rotational axis or concentrically with the rotational axis or alternatively, discharged through outlet openings at a periphery of the bowl. According to some examples, a sludge phase is separated from the fluid feed mixture and is discharged through outlet openings at a periphery of the bowl.
An axially moveable slide, herein also referred to as the slide, arranged in the bowl is configured for being controlled to intermittently, close and open the outlet openings at the periphery of the bowl.
The sealing arrangement forms a mechanical hermetical seal. A mechanical hermetical seal is alternatively referred to as a mechanical end-face seal.
Since the sealing arrangement is configured for providing a sealing of the bowl space around the rotational axis, the sealing arrangement seals off at least the spindle from the bowl space. Thus, matter within the bowl space is prevented from reaching the spindle and vice versa. Accordingly, unwanted leakage or contamination between the different components of the centrifugal separator may be prevented. Moreover, a pressure difference may be maintained between the bowl space and the separation space within the bowl, as well as between the bowl space and an outside of the bowl space.
In some centrifugal separators the pressure within the bowl space in the stationary structure is maintained at sub-atmospheric pressure at least during certain time periods of the operation of the relevant centrifugal separator. Namely, by reducing the friction between air in the bowl space and the bowl as the bowl rotates at high speed, energy consumption of the centrifugal separator can be reduced and/or heating of the bowl.
According to some examples, a pump may be directly, or indirectly, arranged in fluidly communication with the bowl space, the pump being configured to pump gas/air from the bowl space to produce a sub-atmospheric pressure within the bowl space.
Mentioned purely as examples, the additional fluid that can be supplied via the fluid supply path extending from the stationary structure via the at least one duct in the first sealing member to the bowl, may be an operating liquid utilised for operating an axially moveable slide inside the bowl, a control liquid utilised for operating e.g. a pilot valve inside the bowl, a cooling fluid to be supplied to a system of cooling channels in the bowl, etc.
According to some examples, the first sealing member may be provided with a third sealing surface. The rotatable sealing portion may comprise a third sealing member provided with a fourth sealing surface and the third and fourth sealing surfaces may be arranged in sealing abutment. In this manner, the sealing arrangement may be provided as a double seal.
In the sealing arrangement, the first sealing member is arranged between the second and third sealing members.
More specifically, the first sealing surface and the third sealing surface are arranged at opposite axial portions of the first sealing member. Accordingly, the first and second sealing surface face in opposite axial directions of the first sealing member. Thus, the third and fourth sealing surfaces are arranged at a different axial position of the sealing arrangement than the first and second sealing surfaces.
For instance, during use of the centrifugal separator, the second sealing member may be arranged in connection with the bowl and the third sealing member may be arranged in connection with the spindle. Thus, in a transitional region between the bowl and the spindle, the sealing arrangement seals off the bowl space from the rotatable system, which includes the bowl and the spindle.
According to some examples, the first sealing member may be provided with at least one liquid supply channel other than the at least one duct. In this manner, a liquid may be supplied to the sealing arrangement.
For instance, a cooling liquid may be supplied to the sealing arrangement via the liquid supply channel if the sealing arrangement should require cooling.
According to some examples, the first sealing member may be provided with at least one liquid return channel. The at least one liquid supply channel may be arranged in fluid communication with the at least one liquid return channel via a first circularly extending channel arranged between the first and second sealing members. In this manner, a cooling liquid may be led to, along, and from the first and second sealing surfaces in order to cool the first and second sealing members at the first and second sealing surfaces. Thus, an efficient cooling of the sealing arrangement may be provided.
According to some examples, the second sealing member may be arranged with limited axial mobility in relation to the bowl and the second sealing member may be biased in an axial direction towards the first sealing member. In this manner, the sealing abutment between the first and second sealing surfaces may be ensured.
According to some examples, including the third sealing member, the first sealing member may be arranged with limited axial mobility in relation to the stationary structure, and the first sealing member may be biased in an axial direction towards the third sealing member. In this manner, also the sealing abutment between the third and fourth sealing surfaces may be ensured.
When the first sealing member is arranged with limited axial mobility in relation to the stationary structure, the biasing of the second sealing member towards the first sealing member may be transferred to the first sealing member for achieving the biasing of the first sealing member towards the third sealing member.
According to some examples, the centrifugal separator may comprise an elastic sealing member configured to seal between the first sealing member and the stationary structure. The elastic sealing member may comprise a first portion extending circumferentially around the first sealing member and a second portion extending around the at least one duct at the radially outer surface of the first sealing member. In a pre-installed state of the elastic sealing member, the second portion may extend in a plane of the first portion and in an installed state of the elastic sealing member in the centrifugal separator, a plane of the second portion may extend perpendicularly to the plane of the first portion. In this manner, the elastic sealing member may be easily produced and installed in the centrifugal separator.
More specifically, since in the pre-installed state of the elastic sealing member, the second portion extends in a plane of the first portion, the elastic sealing member may be produced in in a mould, such as in a mould of an injection moulding tool, having a cavity extending mainly in one plane. Since the elastic sealing member is elastic, it is easily twisted upon installation at the first sealing member, and the second portion may be easily brought to extend perpendicularly to the plane of the first portion.
Installation of the elastic sealing member is easily accomplished by arranging the first portion around the first sealing member and twisting the second portion to be positioned around the duct. The alternative to using the present elastic sealing member is more complicated to install and would entail using two separate sealing members, such as two O-rings, one around the first sealing member and the other around the duct at the radially outer surface of the first sealing member.
The elastic sealing member, as such, forms as separate aspect. The elastic sealing member may be utilised in connection with a first sealing member, as discussed above, or in connection other portions of a centrifugal separator than at the first sealing member.
According to an aspect, there is provided an elastic sealing member for a centrifugal separator, the elastic sealing member being configured to seal between a peripheral outer surface of a circular member and a structure arranged around the circular member, wherein a duct extends from the outer surface through the circular member, wherein the elastic sealing member comprises a first portion configured to extend circumferentially around the first sealing member and a second portion extending around the duct at the outer surface of the circular member, and wherein in a pre-installed state of the elastic sealing member, the second portion extends in a plane of the first portion and in an installed state of the elastic sealing member at the circular member, a plane of the second portion extends perpendicularly to the plane of the first portion.
Since in the pre-installed state of the elastic sealing member, the second portion extends in the plane of the first portion and in the installed state of the elastic sealing member the plane of the second portion extends perpendicularly to the plane of the first portion - an easily produced and easily installed elastic sealing member is provided.
As discussed above, the elastic sealing member may be produced in in a mould, such as in a mould of an injection moulding tool, having a cavity extending mainly in one plane and installation is performed as one single unit for sealing both the circular member and around the duct at the outer surface of the circular member.
The elastic sealing member may be utilised in apparatuses other than a centrifugal separator.
Thus, according to a separate aspect, there is provided an elastic sealing member configured to seal between a peripheral outer surface of a circular member and a structure arranged around the circular member, wherein a duct extends from the outer surface through the circular member, wherein the elastic sealing member comprises a first portion configured to extend circumferentially around the circular member and a second portion extending around the duct at the outer surface of the circular member, wherein in a pre-installed state of the elastic sealing member, the second portion extends in a plane of the first portion and in an installed state of the elastic sealing member at the circular member, a plane of the second portion extends perpendicularly to the plane of the first portion.
Since in the pre-installed state of the elastic sealing member, the second portion extends in the plane of the first portion and in the installed state of the elastic sealing member the plane of the second portion extends perpendicularly to the plane of the first portion - the elastic sealing member can be easily produced and easily installed.
Further features of, and advantages with, the invention will become apparent when studying the appended claims and the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects and/or examples of the invention, including its particular features and advantages, will be readily understood from the examples discussed in the following detailed description and the accompanying drawings, in which:

Fig. 1 schematically illustrates a section through a centrifugal separator according to examples,
Fig. 2 schematically illustrates a section along a rotational axis of a portion of a centrifugal separator,
Fig. 3 schematically illustrates a section along a rotational axis of a portion of a centrifugal separator,
Fig. 4 schematically illustrates a sealing member,
Figs. 5a and 5b illustrate an elastic sealing member, and
Figs. 5c and 5d illustrate an elastic sealing member configured for use in a centrifugal separator.

DETAILED DESCRIPTION

Aspects and/or examples of the invention will now be described more fully. Like numbers refer to like elements throughout. Well-known functions or constructions will not necessarily be described in detail for brevity and/or clarity.
Fig. 1 schematically illustrates a section through a centrifugal separator 2 according to examples.
The centrifugal separator 2 comprises a stationary structure 4. The stationary structure 4 may comprise a casing 6 and a support structure 8. The casing 6 is mounted on the support 8. The stationary structure 4 delimits a bowl space 10. For instance, the casing 6 may delimit the bowl space 10.
The centrifugal separator 2 further comprises a bowl 12 and a spindle 14 connected to the bowl 12. The bowl 12 and the spindle 14 are configured to rotate about a rotational axis 16 during use of the centrifugal separator 2. During use of the centrifugal separator 2, the rotational axis 16 may extend vertically.
The bowl 12 is arranged within the bowl space 10 of the stationary structure 4. The spindle 14 extends into the bowl space 10 from an outside of the bowl space10. For instance, the spindle 14 may extend into the bowl space 10 from the support structure 8.
A separation space 18 is delimited by the bowl 12. A separation aid, such as a stack 20 of frustoconical separation discs is arranged in the separation space 18. Other kinds of separation aids e.g., radially extending vanes may alternatively be arranged in the separation space 18.
According to some examples, such as in the illustrated example, the centrifugal separator 2 comprises an electric motor 22 configured to transmit driving torque to the bowl 12 via the spindle 14.
Accordingly, the bowl 12 and the spindle 14 form part of a rotatable system of the centrifugal separator 2. The bowl 12 and the spindle 14 are driven to rotate about the rotational axis 16 by the electric motor 22. The electric motor 22 may be arranged in the stationary structure 4, such as in the support structure 8. In the illustrated examples, the spindle 14 is directly driven by the electric motor 22. In alternative examples, a transmission may be arranged between the electric motor 22 and the spindle 14.
An inlet 24 for a fluid feed mixture to be separated in the centrifugal separator 2 leading into the separation space 18 is arranged at an upper end of the bowl 12. Alternatively, the fluid feed mixture may be led into the separation space 18 via a hollow spindle from below the bowl 12.
An outlet 26 for separated light phase is arranged at an upper end of the bowl 12. Alternatively, the light phase may be led from the separation space via a hollow spindle downwardly from the bowl 12.
Optionally, there may be provided a further outlet (not shown) for a separated heavy phase arranged at an upper or lower end of the bowl 12.
In the illustrated example, the bowl 12 comprises a bowl body 26 provided with outlet openings 28. That is, the outlet openings 28 extend through the bowl body 26 to the separation space 18. The outlet openings 28 are arranged at a periphery of the bowl body 26. The outlet openings 28 are evenly distributed around the periphery of the bowl 12.
During use of the centrifugal separator 2, the outlet openings 28 are arranged for intermittent discharge of a heavy phase or a sludge phase separated in the separation space 18, depending on the fluid feed mixture to be separated and whether the centrifugal separator 2 has an outlet for separated heavy phase arranged at one of the upper and lower ends of the bowl 12 or not.
As known, the outlet openings 28 are intermittently openable by movement of an axially movable slide (not shown) within the bowl 12, see further below with reference to Fig. 2. When open, the outlet openings 28 fluidly connect the separation space 18 with the bowl space 10 outside the bowl 12.
A pilot valve 30 is arranged in the bowl body 26. The pilot valve 30 controls the movement of the axially movable slide and thus, the opening and closing of the outlet openings 28, see further below with reference to Fig. 2 .
The centrifugal separator 2 further comprises a sealing arrangement 32. The sealing arrangement 32 is configured for providing a sealing of the bowl space 10 around the rotational axis 16. In the example of Fig. 1 , the sealing arrangement 32 is arranged at lower end of the bowl 12.
The inside of the bowl space 10 may be sealed off from an outside of the bowl space 10, such as from an ambient environment 31 of the centrifugal separator 2. Thus, the bowl space 10 may form a space that can be subjected to a different pressure that than that of the ambient environment 31.
According to some examples, a pump 33 may be directly, or indirectly, arranged in fluid communication with the bowl space 10. The pump 33 is arranged to pump gas/air from the bowl space 10 to produce a sub-atmospheric pressure therein.
According to some examples, steam may be introduced into the bowl space 10 from an external steam producing source e.g., for disinfection purposes. According to other examples, an aerosol, vapour and/or steam may form in the bowl space 10 when a heavy phase or a sludge phase is discharged from the separation space 18.
For instance, the bowl space 10 may be sealed off from other portions of the stationary structure 4, such as from the support structure 8. Such sealing off may be provided by the sealing arrangement 32. A further sealing arrangement 35 may be arranged between an upper end of the bowl 12 or above the bowl 12 between the stationary structure 4 and the inlet 24 and/or the outlet 26. Thus, the bowl space 12 may be sealed off from the ambient environment 31 of the centrifugal separator 2 also at an end opposite to where the spindle 14 connects to the bowl 12.
When the bowl space 12 is sealed off, sub-atmospheric pressure may be maintained therein, at least during certain time periods. Similarly, aerosol, vapour, and/or steam may be prevented from escaping to the ambient environment 31. Further, aerosol, vapour, and/or steam may be prevented by the sealing arrangement 32 from reaching and harming inter alia the spindle 14.
Fig. 2 schematically illustrates a section along the rotational axis 16 of a portion of the centrifugal separator 2 shown in Fig. 1 . Accordingly, in the following reference is also made to Fig. 1 .
The portion of the centrifugal separator 2 shown in Fig. 2 includes a lower portion of the bowl 12, an upper portion of the spindle 14, a portion of the stationary structure 4, and the sealing arrangement 32.
The bowl 12 comprises an axially moveable slide 34 arranged therein. As discussed above, the slide 34 is arranged for closing and opening the outlet openings 28 at the periphery of the bowl body 26.
The axially moveable slide 34 forms at least part of a lower limitation of the separation space 18.
The sealing arrangement 32 is configured for providing a sealing of the bowl space 10 around the rotational axis 16. Thus, the sealing arrangement 32 seals off the spindle 14 and the bowl 12 from the bowl space 10 formed within the stationary structure 4.
The sealing arrangement 32 comprises a stationary sealing portion 36 arranged around the rotational axis 16 in the stationary structure 4. The sealing arrangement 32 comprises a rotatable sealing portion 38 arranged around the rotational axis 16 and arranged to rotate with the bowl 12 and the spindle 14.
The stationary sealing portion 36 comprises a first sealing member 40 provided with a first sealing surface 42. The rotatable sealing portion 38 comprises a second sealing member 44 provided with a second sealing surface 46. The first and second sealing surfaces 42, 46 are arranged in sealing abutment.
The first sealing member 40 is provided with at least one duct 48 extending between a radially outer surface 50 of the first sealing member 40 and a radially inner surface 52 of the first sealing member 40.
A fluid supply path 54 extends from the stationary structure 4 via the at least one duct 48 to the bowl 12. In Fig. 2 , the fluid supply path 54 is indicated with dotted arrows.
The fluid supply path 54 which includes the duct 48 enables introduction of a fluid into the bowl 12 via the stationary first sealing member 40 of the sealing arrangement 32. Thus, the sealing arrangement 32 has a double functionality by providing a sealing of the bowl space 10 around the rotational axis 16 as well as enabling introduction of a fluid into the bowl 12.
The fluid to be introduced into the bowl 12 is a different fluid than the fluids being introduced into the separation space 18 and being separated therein i.e., a different fluid than the fluid feed mixture and the separated light, heavy, and/or sludge phases.
The general idea of the fluid supply path 54 extending via the duct 48 in the first sealing member 40 is not limited to any specific fluid flowing through the fluid supply path 54. The fluids discussed herein are only examples of fluids that can be introduced into the bowl 12 via the fluid supply path. Accordingly, examples of fluids are an operating liquid utilised for operating the axially moveable slide 34 inside the bowl 12, a control liquid utilised for operating e.g. a pilot valve 30 inside the bowl 12, and a cooling fluid to be supplied to a system of cooling channels extending in the bowl body 26.
In the illustrated example, the fluid supply path 54 is configured for supplying a control liquid to a pilot valve 30 within the bowl 12 during use of the centrifugal separator 2.
In any known manner, the pilot valve 30 may be utilised for controlling axial positions of the axially moveable slide 34 and thus, discharge of a heavy phase or a sludge phase from the separation space 18, via the outlet openings 28 discussed above with reference to Fig. 1. An operating liquid may be supplied to an operating liquid chamber 62 arranged between the bowl body 26 and the slide 34 e.g., via an operating liquid channel 64 extending through the spindle 14. When the operating liquid chamber 62 is filled with operating liquid, the slide 34 maintains the outlet openings 28 closed. When the operating liquid chamber 62 is emptied of operating liquid, the slide 34 opens the outlet openings 28 and a discharge from the separation space 18 takes place. By controlling the supply of control liquid to the pilot valve 30 via the fluid supply path 54, the pilot valve 30 enables emptying and filling of the operating liquid chamber 62, and thus, control of the discharge of heavy phase or sludge phase.
Also in a centrifugal separator 2 without the outlet openings 28 and an axially movable slide 34, the fluid supply path 54 can be utilised for supplying a fluid to the bowl 12. For instance, a cooling fluid may be supplied to a system of cooling channels within the bowl body 26.
According to some examples, such as in the illustrated example, the fluid supply path 54 comprises a first conduit 58 leading at least partially through the stationary structure 4, the at least one duct 48 provided in the first sealing member 40, and a second conduit 60 leading at least partially through the bowl 12. In this manner, the fluid supply path 54 leading from the stationary structure 4, via the first sealing member 40, and at least partially through the bowl 12 may be formed.
The first conduit 58 may be formed partially by drilled or otherwise formed holes through the stationary structure 4. Other parts of the first conduit 58 through the stationary structure 4 may be formed by one or more rigid pipes and/or flexible tubes. Similarly, the second conduit 60 leading at least partially through the bowl 12 may be formed partially by drilled or otherwise formed holes through the bowl body 26. Alternatively, or additionally, parts of the second conduit 60 may be formed by one or more rigid pipes and/or flexible tubes.
According to some examples, such as in the illustrated example, an annular space 66 is formed around the spindle 14 and/or a portion of the bowl 12 radially inside the first sealing member 40 and at least partially axially delimited by the second sealing member 44. The fluid supply path 54 includes the annular space 66. In this manner, the fluid supply path 54 can transition from the duct 48 via the annular space 66 to the second conduit 60 in the bowl 12.
According to some examples, such as in the illustrated example, the first and second sealing surfaces 42, 46 extend perpendicularly to the rotational axis 16.
According to some examples, such as in the illustrated example, seen along the rotational axis 16, the second sealing member 44 is arranged at the bowl 12 and the first sealing member 40 is arranged around the spindle 14. In this manner, the sealing arrangement 32 may be arranged around the rotational axis 16 at an axial position where the bowl 12 is connected to the spindle 14.
The second sealing member 44 is arranged axially moveable within the bowl 12. The second sealing member 44 may be arranged with a limited axial mobility in relation to the bowl 12. The second sealing member 44 is biased in an axial direction towards the first sealing member 40. Thus, it is ensured that the sealing abutment between the first and second sealing surfaces 42, 46 is maintained.
For instance, the second sealing member 44 may be arranged in a circular recess 68 extending around the rotational axis 16 within the bowl body 26, which provides at least a limited axial mobility of the second sealing member 44. One or more suitable resilient members 70 are arranged within the circular recess 68, between the second sealing member 44 and an axially delimiting surface of the circular recess 68. Thus, the one or more resilient members 70 may bias the second sealing member 44 in the axial direction towards the first sealing member 40.
In the example of Fig. 2 , resilient members 70 in the form of helical springs are shown. Alternatively, a Belleville spring, such as a Belleville slotted disc spring may be utilised as a resilient member for biasing the second sealing member 44 in the axial direction towards the first sealing member 40. The Belleville slotted disc spring provides a spring constant particularly suitable for providing an even biasing force over the resilient range provided by the Belleville slotted disc spring.
The first sealing member 40 is rotationally fixed to the stationary structure 4. Thus, the first sealing member 40 remains stationary during use of the centrifugal separator 2. For instance, a first radial locking member 72 may extend from the stationary structure 4 into a first slot 74 within the first sealing member 40. The first slot 74 may enable axial mobility of the first sealing member 40 in relation to the first radial locking member 72 and the stationary structure 4, see further below.
The second sealing member 44 is rotationally fixed to the bowl 12. Thus, the second sealing member 44 rotates with the bowl 12 and the spindle 14 during use of the centrifugal separator 2. A second radial locking member 76 may extend from the bowl body 26 into a second slot 78 within the second sealing member 44. The second slot 78 enables axial mobility of the second sealing member 44 in relation to the bowl 12.
According to some examples, such as in the illustrated example, the first sealing member 40 is provided with a third sealing surface 80 and the rotatable sealing portion 38 comprises a third sealing member 82 provided with a fourth sealing surface 84. The third and fourth sealing surfaces 80, 84 are arranged in sealing abutment.
According to some examples, such as in the illustrated example, the third sealing member 82 is arranged around the spindle 14.
In the example including the third sealing member 82, the first sealing member 40 is arranged axially moveable in relation to the stationary structure 4. The first sealing member 40 may be arranged with limited axial mobility in relation to the stationary structure 4. The first sealing member 40 is biased in an axial direction towards the third sealing member 82. Thus, the sealing abutment between the third and fourth sealing surfaces 80, 84 is ensured.
The biasing of the first sealing member 40 towards the third sealing member 82 may be provided by the resilient members 70 arranged to bias the second sealing member 44 towards the first sealing member 40. Namely, the force applied to the second sealing member 44 by the resilient members 70, due to the axial mobility of the first sealing member 40, is translated to the first sealing member 40, which thus, is biased towards the third sealing member 82.
The third sealing member 82 is arranged in connection with the spindle 14.
The thus configured sealing arrangement 32 may provide a seal around the rotational axis 16, between the stationary structure 4 and the spindle 14. Also, the annular space 66 radially inside the first sealing member 40 may be sealed off towards the stationary structure 4, via the abutting third and fourth sealing surfaces 80, 84.
According to some examples, such as in the illustrated example, the third and fourth sealing surfaces 80, 84 extend perpendicularly to the rotational axis.
The third sealing member 82 is rotationally fixed to the spindle 14. Thus, the third sealing member 82 rotates with the spindle 14 and the bowl 12 during use of the centrifugal separator 2. A third radial locking member 86 may extend from the spindle 14 into a third slot 88 within the third sealing member 82.
A flange 90 on the spindle 14 may form an axial stop for the third sealing member 82, preventing it from moving in a direction axially away from the first sealing member 40.
Mentioned purely as examples, the first sealing member 40, at least at the first and third sealing surfaces 42, 80 may be made from graphite and the second and third sealing members 44, 82 at least at the second and fourth sealing surfaces 46, 84 may be made from silicon carbide.
O-rings (not shown) may be provided for sealing between the third sealing member 82 and the spindle 14, between the second sealing member 44 and the bowl body 26, and between the first sealing member 40 and the stationary structure 4. An elastic sealing member may be arranged between the first sealing member 40 and the stationary structure 4, see further below with reference to Figs. 5a - 5d .
Fig. 3 schematically illustrates a section along the rotational axis 16 of a portion of a centrifugal separator according to some examples. The centrifugal separator may be a centrifugal separator 2 as discussed above with reference to Figs. 1 and 2 . The section of Fig. 3 is taken at a different radial position than the section of Fig. 2 . In the following reference is also made to Figs. 1 and 2 .
Accordingly, again, the centrifugal separator 2 comprises a sealing arrangement 32 and is provided with a fluid supply path extending from the stationary structure 4 via at least one duct to the bowl 12. Again, the fluid supply path enables introduction of a fluid into the bowl 12 via the stationary first sealing member 40 of the sealing arrangement 32. In Fig. 3 , the fluid supply path is not visible due to it extending in a different radial position than in the shown section.
Again, the portion of the centrifugal separator 2 shown includes the lower portion of the bowl 12, the upper portion of the spindle 14, a portion of the stationary structure 4, and the sealing arrangement 32.
Again, the sealing arrangement 32 comprises a first sealing member 40, a second sealing member 44, and optionally, according to some examples, such as in the illustrated example, a third sealing member 82.
According to some examples, such as in the illustrated example, the first sealing member 40 is provided with at least one liquid supply channel 92 other than the at least one duct 48.
The liquid supply channel 92 is configured for a different liquid to flow therethrough than a fluid flowing through the at least one duct 48.
A liquid may be supplied to the sealing arrangement 32 via the liquid supply channel 92.
A cooling liquid may be supplied to two or more of the sealing surfaces 42, 46, 80, 84 of the sealing arrangement 32 via the liquid supply channel 92.
According to some examples, such as in the illustrated example, the first sealing member 40 is provided with an additional first sealing surface 42' arranged in parallel with and radially outside the first sealing surface 42. The additional first sealing surface 42' is arranged in sealing abutment with the second sealing surface 46 of the second sealing member 44. The at least one liquid supply channel 92 extends between the radially outer surface 50 of the first sealing member 40 and a first liquid supply opening 94, the first liquid supply opening 94 being arranged radially between the first sealing surface 42 and the additional first sealing surface 42'. In this manner, a cooling liquid can be supplied via the liquid supply channel 92 to the first, additional first, and second sealing surfaces 42, 42', 46 during use of the centrifugal separator.
Thus, the first and second sealing members 40, 44 can be cooled during use of the centrifugal separator, which enables a cool running and long lasting mechanical hermetical sealing arrangement 32 of the centrifugal separator. Therefore, the sealing arrangement 32 can be configured for sealing high pressure differences.
According to some examples, such as in the illustrated example, the first sealing member 40 is provided with an additional third sealing surface 80' arranged in parallel with and radially outside the third sealing surface 80. The additional third sealing surface 80' is arranged in sealing abutment with the fourth sealing surface 84 of the third sealing member 82. The at least one liquid supply channel 92 further extends between the radially outer surface 50 of the first sealing member 40 and a second liquid supply opening 96, the second liquid supply opening 96 being arranged radially between the third sealing surface 80 and the additional third sealing surface 80'. In this manner, a cooling liquid can be supplied via the liquid supply channel 92 to the third, additional third, and fourth sealing surfaces 80, 80', 84 during use of the centrifugal separator.
Thus, the first and third sealing members 40, 82 can be cooled during use of the centrifugal separator, which enables a cool running and long lasting mechanical hermetical sealing arrangement 32 of the centrifugal separator.
The first sealing member 40 is further discussed below with reference to Fig. 4 .
Fig. 4 schematically illustrates the first sealing member 40 discussed above with reference to Fig. 3 . In the following reference is also made to Figs. 2 and 3 .
In Fig. 4 , the at least one duct 48 of the fluid supply path 54 extending through the first sealing member 40 is shown.
Two radial sections of the first sealing member 40 are indicated in Fig. 4 . In one of the sections the liquid supply channel 92, through which a liquid may be supplied to the sealing arrangement 32 is shown. In the other of the sections, a liquid return channel 100 is shown, see further below.
As discussed above, the liquid supply channel 92 extends between the radially outer surface 50 of the first sealing member 40 and the first liquid supply opening 94 and the second liquid supply opening 96. The first liquid supply opening 94 is arranged radially between the first sealing surface 42 and the additional first sealing surface 42'. The second liquid supply opening 96 is arranged radially between the third sealing surface 80 and the additional third sealing surface 80'.
The first sealing member 40 is provided with at least one liquid return channel 100. The at least one liquid supply channel 92 is arranged in fluid communication with the at least one liquid return channel 100 via a first circularly extending channel 102 arranged between the first and second sealing members 40, 44.
During use of the centrifugal separator, a cooling liquid can be led to and from the first, additional first, and second sealing surfaces 42, 42', 46. Moreover, the cooling liquid can be led along theses surfaces in the first circularly extending channel 102 in order to cool the first and second sealing members 40, 44 at the first, additional first, and second sealing surfaces 42, 42', 46.
The first circularly extending channel 102 is indicated in Fig. 3 and specifically shown in Fig. 4 . The first liquid supply opening 94 opens up into the first circularly extending channel 102.
The first circularly extending channel 102 may be provided in the first and/or second sealing member 40, 44. In the example of Fig. 4 , the first circularly extending channel 102 is provided between the first sealing surface 42 and the additional first sealing surface 42' in the first sealing member 40.
According to some examples, such as in the illustrated example, the at least one liquid return channel 100 extends between a first liquid return opening 104 and the radially outer surface 50 of the first sealing member 40, the first liquid return opening 104 being arranged radially between the first sealing surface 42 and the additional first sealing surface 42'. In this manner, during use of the centrifugal separator, the cooling liquid can be returned from the first circularly extending channel 102 and the first, additional first, and second sealing surfaces 42, 42', 46 via the liquid return channel 100 e.g., to a reservoir for the cooling liquid.
According to some examples, such as in the illustrated example, the at least one liquid supply channel 92 further is arranged in fluid communication with the at least one liquid return channel 100 via a second circularly extending channel 106 arranged between the first and third sealing members 40, 82. In this manner, during use of the centrifugal separator, the cooling liquid can be led to and from the third, additional third, and fourth sealing surfaces 80, 80', 84. Moreover, the cooling liquid can be led along theses surfaces in the second circularly extending channel 106 in order to cool the first and third sealing members 40, 82 at the third, additional third, and fourth sealing surfaces 80, 80', 84.
According to some examples, such as in the illustrated example, the at least one liquid return channel 100 further extends between a second liquid return opening 108 and the radially outer surface 50 of the first sealing member 40, the second liquid return opening 108 being arranged radially between the third sealing surface 80 and the additional third sealing surface 80'.
The second circularly extending channel 106 is indicated in Fig. 3 and specifically shown in the sections of Fig. 4 . The second liquid return opening 108 opens up from the second circularly extending channel 106. The second circularly extending channel 106 may be provided in the first and/or third sealing members 40, 82. In the example of Fig. 4 , the second circularly extending channel 106 is provided between the third sealing surface 80 and the additional third sealing surface 80' in the first sealing member 40.
Thus, the first sealing member 40, during use of the centrifugal separator, is configured for the cooling liquid supplied via the liquid supply channel 92 to flow along the first, additional first, second, third, addition third, and fourth sealing surfaces 42, 42', 46, 80, 80', 84 for cooling thereof and be returned via the liquid return channel 100.
Figs. 5a and 5b illustrate an elastic sealing member 110. Figs. 5c and 5d illustrate an elastic sealing member 110 configured for use in a centrifugal separator.
The elastic sealing member 110 comprises a first portion 112 configured to extend circumferentially around a circular member and a second portion 114 extending around a duct at a radially outer surface of the circular member. The first portion 112 has a general circular extension in a first plane 116. Also the second portion 114 has a general circular extension. The second portion 114 is connected to the first portion 112 in a manner such that it interrupts the circular extension of the first portion 112. Thus, the elastic sealing member 110 is configured to seal around the circular member as well as around the duct. See also below with reference to Figs. 5c and 5d .
Fig. 5a shows the elastic sealing member 110 in a pre-installed state i.e., prior to extending around the circular member and the duct. In the pre-installed state, the second portion 114 extends in the first plane 116 i.e., in the same plane 116 as the first portion 112.
Fig. 5b shows the elastic sealing member 110 in an installed state i.e., as when extending around the circular member and the duct. In the installed state, a plane of the second portion 114 extends perpendicularly to the first plane 116 i.e., perpendicularly to the plane 116 of the first portion 112.
This elastic sealing member 110 is configured for use where otherwise two separate O-rings would have to be used, one around the circular member and one around the duct. Installation of the elastic sealing member 110 is considerably easier than the installation of two separate O-rings.
Since in the pre-installed state of the elastic sealing member 110, the second portion 114 extends in the plane 116 of the first portion 112, the elastic sealing member 110 can be easily produced in a mould, such as in a mould of an injection moulding tool. The mould can have an uncomplicated cavity extending mainly in one plane to form both the first and second portions 112, 114 in this cavity. Since the elastic sealing member 110 is elastic, the second portion 114 is easily brought to extend perpendicularly to the plane 116 of the first portion 112 by slightly twisting the elastic sealing member 110.
In the example of Figs. 5a and 5b , the elastic sealing member 110 comprises more than one second portion 114 for sealing around more than one duct.
The centrifugal separator discussed above with reference to Figs. 1 - 4 may comprise an elastic sealing member 110 configured to seal between the first sealing member 40 and the stationary structure 4, see also Figs. 2 - 4 .
Figs. 5c and 5d show the elastic sealing member 110 arranged around the first sealing member 40 in two different views.
As discussed above with reference to Figs. 5a and 5b , the elastic sealing member 110 comprise a first portion 112 extending circumferentially around the first sealing member 40 and a second portion 114 extending around the at least one duct 48 at the radially outer surface 50 of the first sealing member 40.
Again, in the pre-installed state of the elastic sealing member 110, the second portion 114 extends in the plane 116 of the first portion 112. In the installed state of the elastic sealing member 110 in the centrifugal separator, a plane of the second portion 114 extends perpendicularly to the plane 116 of the first portion 112.
The elastic sealing member 110 may be used to seal other circular members of a centrifugal separator than the first sealing member 40. Specifically, the elastic sealing member 110 can be used in connection with the sealing of circular members being provided with at least one duct extending therethrough. Thus, the circular member can be sealed against one or more adjacent portions of the centrifugal separator and the at least one duct may be sealed to enable leakage free conducting of a fluid from the one or more adjacent portions of the centrifugal separator to the duct of the circular member.
In the example of Figs. 5c and 5d , the elastic sealing member 110 comprises five second portions 114. Three of the second portions 114 extend around ducts 48 at the radially outer surface 50 of the first sealing member 40 and two of the second portions 114 extend around the liquid supply channel 92 and the liquid return channel 100 at the radially outer surface 50.
The terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items. It will be further understood that the terms "comprises," "comprising," "includes," and/or "including" when used herein specify the presence of stated features, integers, actions, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, actions, steps, operations, elements, components, and/or groups thereof.
It will be understood that, although the terms first, second, etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element without departing from the scope of the present disclosure.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
It is to be understood that the foregoing is illustrative of various examples and that the invention is defined only by the appended claims. A person skilled in the art will realize that the examples may be modified, and that different features of the examples may be combined to create examples other than those described herein, without departing from the scope of the invention, as defined by the appended claims.

Claims

A centrifugal separator (2) comprising a stationary structure (4) delimiting a bowl space (10), a bowl (12) delimiting a separation space (18), a spindle (14) connected to the bowl (12), and a sealing arrangement (32), wherein
the bowl (12) and the spindle (14) are configured to rotate about a rotational axis (16), wherein

the bowl (12) is arranged within the bowl space (10) and the spindle (14) extends into the bowl space (10) from an outside of the bowl space (10), wherein

the sealing arrangement (32) is configured for providing a sealing of the bowl space (10) around the rotational axis (16), wherein

the sealing arrangement (32) comprises a stationary sealing portion (36) arranged around the rotational axis (16) in the stationary structure (4) and a rotatable sealing portion (38) arranged around the rotational axis (16) and to rotate with the bowl (12) and the spindle (14), wherein

the stationary sealing portion (36) comprises a first sealing member (40) provided with a first sealing surface (42), wherein

the rotatable sealing portion (38) comprises a second sealing member (44) provided with a second sealing surface (46), wherein

the first and second sealing surfaces (42, 46) are arranged in sealing abutment, wherein

the first sealing member (40) is provided with at least one duct (48) extending between a radially outer surface (50) of the first sealing member (40) and a radially inner surface (52) of the first sealing member (40), and wherein

a fluid supply path (54) extends from the stationary structure (4) via the at least one duct (48) to the bowl (12).
The centrifugal separator (2) according to claim 1, wherein the first and second sealing surfaces (42, 46) extend perpendicularly to the rotational axis (16).
The centrifugal separator (2) according to claim 1 or 2, wherein the first sealing member (40) is provided with a third sealing surface (80), wherein the rotatable sealing portion (38) comprises a third sealing member (82) provided with a fourth sealing surface (84), and wherein the third and fourth sealing surfaces (80, 84) are arranged in sealing abutment.
The centrifugal separator (2) according to claim 3, wherein the third and fourth sealing surfaces (80, 84) extend perpendicularly to the rotational axis (16).
The centrifugal separator (2) according to any one of the preceding claims, wherein the first sealing member (40) is provided with at least one liquid supply channel (92) other than the at least one duct (48).
The centrifugal separator according to claim 5, wherein the first sealing member (40) is provided with an additional first sealing surface (42') arranged in parallel with and radially outside the first sealing surface (42), wherein
the additional first sealing surface (42') is arranged in sealing abutment with the second sealing surface (46) of the second sealing member (44), and wherein

the at least one liquid supply channel (92) extends between the radially outer surface (50) of the first sealing member (40) and a first liquid supply opening (94), the first liquid supply opening (94) being arranged radially between the first sealing surface (42) and the additional first sealing surface (42').
The centrifugal separator (2) according to claim 5 or 6, wherein the first sealing member (40) is provided with at least one liquid return channel (100), and wherein the at least one liquid supply channel (92) is arranged in fluid communication with the at least one liquid return channel (100) via a first circularly extending channel (102) arranged between the first and second sealing members (40, 44).
The centrifugal separator (2) according to claim 6 and 7, wherein the at least one liquid return channel (102) extends between a first liquid return opening (104) and the radially outer surface (50) of the first sealing member (40), the first liquid return opening (104) being arranged radially between the first sealing surface (42) and the additional first sealing surface (42').
The centrifugal separator (2) according to any one of claim 3 or 4 and any one of claim 6 - 8, wherein the first sealing member (40) is provided with an additional third sealing surface (80') arranged in parallel with and radially outside the third sealing surface (80), wherein
the additional third sealing surface (80') is arranged in sealing abutment with the fourth sealing surface (84) of the third sealing member (82), wherein

the at least one liquid supply channel (92) further extends between the radially outer surface (50) of the first sealing member (40) and a second liquid supply opening (96), the second liquid supply opening (96) being arranged radially between the third sealing surface (80) and the additional third sealing surface (80').
The centrifugal separator (2) according to any one of claims 7 - 9, wherein the at least one liquid supply channel (92) further is arranged in fluid communication with the at least one liquid return channel via a second circularly extending channel arranged between the first and third sealing members.
The centrifugal separator (2) according to claim 6 and 7, wherein the at least one liquid return channel further (100) extends between a second liquid return opening (108) and the radially outer surface (50) of the first sealing member (40), the second liquid return opening (108) being arranged radially between the third sealing surface (80) and the additional third sealing surface (80').
The centrifugal separator (2) according to any one of the preceding claims, wherein the fluid supply path (54) comprises a first conduit (58) leading at least partially through the stationary structure (4), the at least one duct (48) provided in the first sealing member (40), and a second conduit (60) leading at least partially through the bowl (12).
The centrifugal separator (2) according to any one of the preceding claims, wherein an annular space (66) is formed around the spindle (14) and/or a portion of the bowl (12) radially inside the first sealing member (40) and at least partially axially delimited by the second sealing member (44), and wherein the fluid supply path (54) includes the annular space (66).
The centrifugal separator (2) according to any one of the preceding claims, wherein the second sealing member (44) is arranged with limited axial mobility in relation to the bowl (12), and wherein the second sealing member (44) is biased in an axial direction towards the first sealing member (40).
The centrifugal separator (2) according to claims 3 and 14 and optionally any one of claims 4 - 13, wherein the first sealing member (40) is arranged with limited axial mobility in relation to the stationary structure (4), and wherein the first sealing member (40) is biased in an axial direction towards the third sealing member (82).
The centrifugal separator (2) according to any one of the preceding claims, comprising an elastic sealing member (110) configured to seal between the first sealing member (40) and the stationary structure (4), wherein
the elastic sealing member (110) comprises a first portion (112) extending circumferentially around the first sealing member (40) and a second portion (114) extending around the at least one duct (48) at the radially outer surface (50) of the first sealing member (40), wherein

in a pre-installed state of the elastic sealing member (110), the second portion (114) extends in a plane (116) of the first portion (112), and wherein

in an installed state of the elastic sealing member (110) in the centrifugal separator (2), a plane of the second portion (114) extends perpendicularly to the plane (116) of the first portion (112).
The centrifugal separator (2) according to any one of the preceding claims, wherein seen along the rotational axis (16), the second sealing member (44) is arranged at the bowl (12) and the first sealing member (40) is arranged around the spindle (14).
The centrifugal separator (2) according to claim 3 and optionally any one of claims 4 - 17, wherein the third sealing member (82) is arranged around the spindle (14).