WO1990002880A1

WO1990002880A1 - Cleanable centrifugal pump without stuffing box

Info

Publication number: WO1990002880A1
Application number: PCT/EP1989/001044
Authority: WO
Inventors: Peter Mette; Wilfried Lehmann; Rainer Landowski
Original assignee: Otto Tuchenhagen Gmbh & Co Kg; Sihi Gmbh & Co Kg
Priority date: 1988-09-13
Filing date: 1989-09-08
Publication date: 1990-03-22
Also published as: EP0359136A1; DE3831068A1

Abstract

A cleanable centrifugal pump without stuffing box, in particular a side channel pump, comprises at least one impeller (5) driven by means of a magnetic, synchronously transmitting rotary coupling arranged inside the impeller (5). The two halves of the coupling are mutually separated by a dividing wall (6) which delimits the space for the fluid to be delivered against the atmosphere and is rigidly and sealingly connected to the pump housing (1). One half of the rotary coupling (7, 12) is mounted in or on the impeller and the dividing wall (6) penetrates the impeller (5) concentrically, serves as a bearing journal for the impeller and, together with the impeller, forms an annular bearing gap (13). The dividiing wall (6) is tubular and statically sealed on both sides of the impeller (5) in the housing of the centrifugal pump (1; 1a; 1b). The annular bearing gap (13) is connected, directly or indirectly, with a region of the suction connection piece (1c) and with a region of the delivery connection piece (1d).

Description

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Cleanable glandless centrifugal pump ----------------------------------------------- -------------------------------------

The invention relates to a cleanable glandless

Centrifugal pump according to the preamble of claim 1.

Centrifugal pumps of the type identified in the introduction are used where the requirement for increased occupational and operational safety as well as greatest environmental friendliness is a priority. Magnetically acting, synchronously transmitting rotating couplings use the attraction and repulsion forces between magnets in two coupling halves. They serve for the contactless transmission of torques, whereby, unlike the hysteresis and eddy current clutches, a slip between the two coupling halves cannot occur. Permanent magnetic synchronous clutches are known, which in connection with glandless centrifugal pumps are preferably designed as so-called central rotary couplings. They require a partition, the so-called can. This has the task of separating the space for the fluid to be pumped from the atmosphere. The inner magnet rotor, which is also equipped with permanent magnets, is arranged within this containment shell. This, in turn, is supported in a bearing flange and medium-lubricated plain bearings and transfers the torque given off by the motor to the impeller without slippage. A housing forms the end of this completely sealed unit. A shaft passage from the room for the fluid to be pumped is not available and therefore is only a static seal between the housing and the containment shell is required. An overview of glandless centrifugal pumps with permanent magnetic synchronous coupling according to the state of the art can be found in the magazine Chemische Industrie, 3/87, pages 4G to 49.

In the known centrifugal pumps, the inner magnet rotor is fastened to the impeller at an axial distance from it via a connecting part. The connecting part also serves to support the impeller and the inner magnet rotor within the housing. The containment shell encloses the inner magnet rotor and parts of the bearing arrangement. The lubrication of the slide bearing for the bearing of the impeller in connection with the inner magnet rotor is usually carried out via the pump to be pumped

Fluid.

The well-known design of the containment shell has a cavity which with the over the bearing gap of the plain bearing

Impeller housing is connected. Due to the

Mode of operation of the hydrodynamically operating plain bearing, the fluid to be delivered reaches the free spaces of the containment shell via the bearing gap. A complete exchange of the in some cases very complicated

Dead clearing the containment fluid located over the

Bearing gap of the plain bearing is excluded.

The known centrifugal pumps are from the aforementioned

For this reason, it is completely unsuitable if the fluid must be conveyed under hygienic or sterile or bacteriologically perfect conditions. Such requirements are particularly in the food and

Beverage industry, in pharmacy or in the sterile field of various fields of application. Centrifugal pumps that meet the above requirements must be automatically cleanable in the flow. In this context, one speaks of the so-called CIP cleaning ability (CIP: cleaning in place), which means that the facilities to be cleaned have an automatic supply of cleaning flow in all areas on the spot A cleaning of the product or. of

Allow product middle residues. In the centrifugal pumps described above, automatic cleaning of the critical areas, in particular the dead spaces within the containment shell, is not possible under the conditions to be demanded.

A glandless centrifugal pump has already been proposed (GM 19 82 247), one of which is a can

trained partition penetrates the impeller concentrically, serves as a cantilevered bearing journal and forms a bearing ring gap with it. This known solution does not disclose any information as to how a defined flow can be ensured in the critical areas, in particular in the bearing ring gap and in the dead space between the impeller hub that is not exposed to the flow and the rear housing wall. It is an object of the present invention to simplify the design of a cleanable glandless centrifugal pump of the type identified in the introduction in such a way that it is CIP-cleanable and allows the delivery of fluids under hygienic or sterile or bacteriological perfect conditions.

This task is characterized by the characteristics of the

Claim 1 solved. Advantageous embodiments of the centrifugal pump according to the invention describe the dependent ones

Claims 2 to 13. Due to the proposed training and sealing the

Partition, the glandless centrifugal pump has a particularly simple and easy-to-clean design.

Conventional centrifugal pumps are usually designed so that the hydraulic efficiency is as high as possible. This is achieved, among other things, by making the liquid-loaded gaps between stationary and moving components as small as possible. In the centrifugal pump according to the invention, there is a deviation from this dimensioning rule insofar as all the gaps located in areas that are critical in terms of cleaning technology, in particular the bearing gap, are subjected to a flow ensuring adequate cleaning. Due to the mechanism of action of the pump, there is a pressure difference in the fluid between the suction and pressure ports within the pump housing, which pressure difference is used to flow through the column in question in a defined radial and axial direction. A deterioration of the associated with this gap flow

hydraulic efficiency is accepted.

So that the bearing ring gap is flowed through with the fluid to be conveyed in a defined manner and on the one hand can be cleaned properly and on the other hand can develop its hydrodynamic load-bearing capacity, an advantageous embodiment of the centrifugal pump according to the invention provides that the bearing ring gap is connected on both sides to a hub-side annular space, the latter in each case via Column with a defined passage cross-section is connected to the space of the impeller blades. A further advantageous embodiment of the centrifugal pump according to the invention provides a hub-side annular space separated by the impeller into two subspaces, one of which has a first opening with a defined passage cross-section with the area of the suction nozzle and the other in the same way via a second opening with the Area of the pressure nozzle is connected. This results as a result of the formed between the suction and discharge nozzle

Pressure difference is a particularly pronounced, defined, in the radial and axial direction between stationary and moving components oriented gap flow within the housing of the conveyor.

Due to the arrangement of the bearing ring gap and its

Mutual connection to the hub-side annular space ensures that, in particular during cleaning, the cleaning liquid to be conveyed flows through the bearing ring gap in sufficient quantity, since its two ends are connected to areas which have different pressure levels due to the pressure distribution in the housing of the impeller.

In order to clean the critical area of the centrifugal pump, the bearing ring gap, particularly intensively, another advantageous embodiment of the centrifugal pump provides for measures to be taken in the bearing ring gap and / or at its entry

are provided that increase the kinetic energy of the gap flow in the bearing ring gap. Another embodiment of the centrifugal pump according to the invention provides that a bearing bush arranged in the impeller in

Area of the bearing ring gap is in turn designed as an impeller. As a result, the gap flow in this area is forced through an additional increase in its kinetic energy.

In order to intensify the cleaning of the bearing ring gap by forming flow turbulence during the cleaning trip, another embodiment of the centrifugal pump according to the invention provides that the bearing ring gap facing

Boundary surface of the partition wall and / or the bearing blocks are or are provided with axial or helical grooves or elevations. By arranging the impeller side half of the rotary coupling in a recess of a hub of the impeller, as is another embodiment of the centrifugal pump according to the

Invention provides is for a compact arrangement

Avoidance of dead spaces in this area.

The hermetically sealed chamber of the impeller-side half of the rotary coupling in the recess of the hub of the impeller, as is provided by a further embodiment of the centrifugal pump according to the invention, ensures a particularly easy-to-clean arrangement, which also promotes the conveyance of the fluid under hygienic or sterile conditions or bacteriologically perfect conditions guaranteed. According to another advantageous embodiment of the

Centrifugal pump according to the invention a compact and easy to clean arrangement of the impeller side half of the rotary coupling is achieved in that the latter is hermetically sealed by the hub and a cover part on the one hand and a bearing bush enclosing the partition wall on the other hand. As a result of the pressure distribution which arises via the housing of the centrifugal pump, forces act on the impeller which attempt to displace it in the axial and radial directions. Another sees that the connection between the bearing ring gap and the associated hub-side annular space is ensured under these conditions

Embodiment of the centrifugal pump according to the invention that the bearing bush is provided on both sides with a thrust surface limiting its axial displacement in the housing. The contact surface is designed in such a way that when it is in contact with the housing there is still sufficient liquid passage between the contact surface and the housing.

The same effect is achieved with another embodiment of the centrifugal pump according to the invention, in which the impeller on both sides towards the housing with a

Is provided contact surface which has the same properties with regard to its liquid permeability as the contact surfaces on the bearing bush.

Another sees to ensure wear resistance and hardness, chemical resistance and good temperature properties and also to keep power losses due to eddy current formation when cutting the partition with the magnetic field lines of the central rotary coupling small

Further development of the centrifugal pump according to the invention before that partition and bearing bush made of a wear-resistant, chemically resistant, high electrical resistance material, preferably a ceramic.

In order for a gap flow that is sufficient in terms of cleaning technology to be ensured under all operating conditions of the pump, in particular at low delivery heights, there is a method for operating the cleanable glandless ones

Centrifugal pump, regardless of Conveying task between the suction and pressure ports required pressure difference, in each application, to provide a minimum pressure difference to ensure the gap flow. An embodiment of the invention is shown in the drawing and will be described in more detail below.

1 shows a meridian section through an advantageous embodiment of the centrifugal pump according to the invention and

2 shows a meridian section through another embodiment of the centrifugal pump according to the invention with a

particularly effective connection of the hub side

Annulus on suction and pressure ports.

Figure 1 shows, representative of other centrifugal pumps, a meridian section through a so-called self-priming side channel pump. It should be particularly emphasized at this point that the present invention can also be used without restriction on so-called normal-suction centrifugal pumps or also on rotating positive displacement pumps. In the present exemplary embodiment, the self-priming side channel pump allows both the conveyance of gaseous and liquid fluids, a reversal of the conveying direction being possible by changing the direction of rotation. In the housing 1 of the centrifugal pump, which consists of a motor-side housing part 1b and a housing cover 1a, there is an open parallel-walled rotor with radially directed blades, hereinafter referred to as impeller 5, as the characteristic component. The housing cover 1a has a suction and a pressure port 1c or 1d, which are connected to a side channel le. The housing 1 is on its engine side Housing part 1b in connection with the housing cover 1a and connecting means 18 connected to a lantern housing 3, the latter being centered and fastened to a flange of a motor 2 via connecting means 17.

A pot-shaped hub 5a is formed on the impeller 5, a recess 5b receiving the half of the central rotary coupling 8, 9 on the impeller side. Part 8 is a multiplicity of rotationally symmetrically arranged “permanent magnets”, while part 9 has a magnetic effect

reinforcing soft angel cladding. The parts 8 and 9 of the impeller-side half of the central rotary coupling are hermetically sealed by the hub 5a and a cover part 10 welded to it on the one hand and a bearing bush 11 on the other hand. A bore formed on the inside of the bearing bush 11 is penetrated concentrically by a partition 6, which is tubular, the latter being accommodated on both sides in the housing parts 1a and 1b in a statically sealing manner via seals 15.

The tubular partition 6 serves the hub 5a of the impeller 5 in connection with the bearing bush 11 as

Bearing journal. Bearing bush 11 and partition B form one

Bearing ring gap 13. The latter is on both sides with one

Annular space 19 connected to the hub 5a of the impeller 5th

surrounds. Since the impeller 5 has a lateral play which is ensured under all operating conditions,

compared to the adjacent housing parts 1a and 1b in

Housing 1 of the centrifugal pump is arranged by

Column 20, which result from the aforementioned game, a connection between the hub-side annular space 19 and the space of the impeller blades. The partition 6 and the

Bearing bushing 11 preferably consist of a wear-resistant, chemically resistant, high electrical one

Resistant material. Ceramic materials, especially silicon carbides, have proven to be advantageous. The boundary surface of the partition 6 and / or the bearing bush 11 facing the bearing ring gap 13 are or are provided with axial or helical grooves or elevations 14, as a result of which the cleaning effect within the

Bearing ring gap 13 can intensify.

A motor shaft 4 is passed through the motor-side housing part 1b and extends through the tubular partition 6. The motor shaft 4 carries on its circumference in the area of the hub 5a of the impeller 5 another half of the central rotary coupling 7, 12, part 7 being permanent magnets arranged symmetrically distributed over the circumference, while part 12 is a soft iron ring which reinforces the magnetic effect represents.

A flywheel 21 is provided on the motor shaft 4 in the area of the lantern housing 3. While seals 15, the partition 6 opposite the housing parts 1a and 1b to the shaft-side part of the central rotary coupling 7, 12

seal, a housing seal 16 ensures a sealing of the housing parts 1a and 1b from their external environment.

When driving the motor shaft 4, the half of the central rotary coupling 7, 12 assigned to this transmits a torque to the half of the central rotary coupling 8, 9 on the impeller side. Under load, the two coupling halves 8, 9 and 7, 12 rotate against each other so far that the required between them Torque acts. The speed of the motor shaft 4 is

transfer synchronously to the impeller 5. Due to effective pressure differences in the housing 1 of the centrifugal pump, the latter fills with the fluid to be delivered, so that the hub-side annular space 19 and the bearing ring gap 13 connected to it are also acted upon with the fluid to be delivered. Due to pressure differences in the

Annulus 19 on both sides of the impeller 5 results in a Flow through the bearing ring gap 13, so that in it on the one hand the fluid flow required for the hydrodynamic lubrication effect and on the other the cleaning flow required for its cleaning with cleaning agent is ensured.

The cleaning of the hub-side annular space 19 is unproblematic, since a liquid exchange between the latter and the space of the impeller blades is readily provided via the column 20, the cleaning of the surfaces delimiting the hub-side annular space 19 by the rotating hub 5a of the area Impeller 5 is extremely intensely supported. To force the gap flow within the bearing ring gap 13, the bearing bush 11 is in this area

in turn trained as an impeller. There are several ways to do this. On the one hand, the blades can extend over the entire axial length of the bearing bush 11, on the other hand, the bearing bush is bladed either only at the entry of the bearing ring gap 13 or at its outlet, or on both sides.

The axial fixation of the impeller 5 with respect to the housing cover 1a and the motor-side housing part 1b takes place via thrust faces 22 which are formed on both sides of the bearing bush 11 in such a way that liquid passage is ensured even in the case of one of the thrust faces 22 on the housing.

The same effect as described above is achieved with contact surfaces 23 which are provided on both sides of the impeller 5 towards the housing parts 1a and 1b, respectively. The radial position of these contact surfaces 23 can vary within the radial extension of the impeller 5,

preferably completely inside or outside. The impeller-side half of the central rotary coupling 6, 9 is hermetically chambered within the recess 5b of the hub 5a, the cover part 10 being welded to the hub 5a and the bearing bush 11, which delimits the chamber for the central rotary coupling 8, 9 radially inward, with an absolutely tight seal the cover part 10 and the hub 5a is cast.

In principle, it is also possible for the shaft-side half of the rotary coupling to be equipped with electromagnets which correspond in function and mode of operation to the permanent magnets described above.

Figure 2 shows a meridian section through a further embodiment of the centrifugal pump according to the invention. In contrast to Figure 1, the pressure port 1d is formed on the motor-side housing part 1b. According to the invention it is provided that the hub-side annular space 19, into which the bearing ring gap 13 opens with its two ends, through the impeller 5 in two

Partial spaces are separated, of which the one arranged to the left of the impeller 5 has a defined opening via a first opening 20 ^*

Passage cross section is connected to the area of the suction port 1c and the other in the same way via a second opening 20 to the area of the pressure port 1d. As a result of the pressure difference present between the pressure nozzle 1d and the suction nozzle 1c during operation of the centrifugal pump, fluid reaches the area from the pressure nozzle 1d via the second opening 20 ^** into the one on the right of the impeller 5

Partial space of the hub-side annular space 19. From here, the fluid penetrates into the entire circumference of the bearing ring gap 13, flows through it, into the partial space of the hub-side located to the left of the impeller 5

Annulus 19 emerge. Via the first opening 20 ^*

the fluid reaches the area of the suction port 1c. Consequently quasi-recirculating to the main flow, a gap flow flowing through the critical areas of the delivery device is ensured as a result of the pressure difference present between the suction and pressure ports within the housing of the delivery device.

Claims

1. Cleanable glandless centrifugal pump, in particular a side channel pump, with at least one impeller which is driven by a magnetically acting, synchronously transmitting rotary coupling, the two halves of the

Coupling are separated from one another by a partition which delimits the space for the fluid to be conveyed from the atmosphere and is firmly and sealingly connected to the housing of the centrifugal pump;

Partition penetrates the impeller concentrically, serves as a bearing journal and forms a bearing ring gap with it, characterized in that

that the partition (6) is tubular and statically sealed on both sides of the impeller (5) in the housing of the centrifugal pump (1; 1a, 1b), and that

Bearing ring gap (13) directly or indirectly

is connected on the one hand to an area of the suction connector (1c) and on the other hand to an area of the pressure connector (1d).

2. Cleanable glandless centrifugal pump according to claim 1, characterized in that

that the bearing ring gap (13) is on both sides with a hub-side annular space (19) in connection, the latter via column (20) with defined

Passage cross section is connected to the space of the impeller blades.

3. Cleanable glandless centrifugal pump according to claim 1, characterized in that

that the bearing ring gap (13) is connected on both sides to a hub-side annular space (19), the latter being separated into two partial spaces by the impeller (5), one of which has a first Opening (20 ^* ) with a defined passage cross-section is connected to the area of the suction port (1c) and the other is connected in the same way via a second opening (20 ^** ) to the area of the pressure port (1d).

4. Cleanable glandless centrifugal pump according to one of the

Claims 1 to 3, characterized in

that measures are provided in the bearing ring gap and / or at its entry which increase the kinetic energy of the gap flow in the bearing ring gap.

5. Cleanable glandless centrifugal pump according to claim 4, with a bearing bush (11) arranged in the impeller (5), characterized in that

that the bearing bush (11) in the region of the bearing ring gap (13) is designed as an impeller.

B. Cleanable glandless centrifugal pump according to one of the

Claims 4 or 5, characterized in that

that the bearing ring gap (13) facing the boundary surface of the partition (6) and / or the bearing bush (11) with axial or helical grooves or elevations (14) are provided or is. 7. Cleanable glandless centrifugal pump according to one of the

Claims 1 to 6, characterized in

that the impeller side half of the rotary coupling (8, 9) is arranged in the recess (5b) of a hub (5a) of the impeller (5).

Cleanable glandless centrifugal pump according to claim 7, characterized in

that the impeller side half of the rotary coupling (8, 9) in the recess (5b) is hermetically sealed.

9. Cleanable glandless centrifugal pump according to claim 7 or 8, characterized in

that the impeller side half of the rotary coupling (8, 9) of the hub (5a) and a cover part (10) on the one hand and a partition (6) enclosing

Bearing bush (11) on the other hand is hermetically sealed.

10. Cleanable glandless centrifugal pump according to one of claims 5 to 9, characterized in

that the bearing bush (11) is provided on both sides with a thrust surface (22) which limits its axial displacement in the housing (1a, 1b). 11. Cleanable glandless centrifugal pump according to one of claims 1 to 10, characterized in that

that the impeller (5) is provided on both sides towards the housing (1a or 1b) with a contact surface (23).

12. Cleanable glandless centrifugal pump after one

of claims 1 to 11, characterized in

that partition (B) and bearing bush (11) consist of a wear-resistant, chemically resistant, high electrical resistance material, preferably a ceramic.

13. A method for operating the cleanable glandless centrifugal pump according to one of claims 1 to 12, characterized in that

that, regardless of the pressure difference required on the part of the conveying task between the suction and pressure ports (1c or 1d), a minimum pressure difference ensuring the gap flows is provided in every application.