EP2961929A1

EP2961929A1 - Screw pump

Info

Publication number: EP2961929A1
Application number: EP14717658.0A
Authority: EP
Inventors: Eduardo Nuss; Arthur Zinke; Aluisio Loth; Klaus Heizinger; Lorenz Lessmann; Sérgio Krahn; Rui Keunecke; Silvio Beneduzzi; Egon Weege; André THEILACKER; Sidney Guedes; Petra Lutke; Robert Kurz; Josef Strassl; Johann Kreidl; Hisham Kamal; Horst ENGL; George Balcerczyk; Mathias Gradl; Gunther Herr
Original assignee: Netzsch Pumpen and Systeme GmbH
Current assignee: Netzsch Pumpen and Systeme GmbH
Priority date: 2013-03-01
Filing date: 2014-02-25
Publication date: 2016-01-06
Also published as: RU2015141527A; AR094939A1; CN105121783A; KR20150121219A; DE102013102032A1; BR112015020434A2; JP2016508573A; WO2014131391A1

Abstract

Disclosed is a screw pump for delivering a fluid medium. The screw pump comprises a pump housing for the medium to be delivered, said housing having an inlet and an outlet. Said screw pump comprises at least two screws. Said at least two screws consist respectively of a shaft having at least two shaft sections and a profiled section arranged therebetween, said profiled sections of the at least two screws engaging at least partially with each other. The at least two screws are arranged so that they can rotate at least partially in the pump housing. The first screw is designed as a drive screw. Said drive screw is associated with a direct first drive. According to the invention, a second drive is associated with at least one second screw.

Description

Screw Pump

The present invention relates to a screw pump according to the features of the preamble of claim 1.

State of the art

The screw pump is a so-called positive displacement pump in which the shape of the rotating displacer is similar to a spindle screw. The screw pump consists of two or more counter-rotating rotors and a pump housing that encloses the rotors. The rotors are formed with a regular, thread-shaped profiling and engage gear-like in one another. The rotors are also referred to as screw spindles and have a first shaft section, a profile section with a helical or helical profile and a second shaft section. The cavities, which are formed by the three construction elements pump housing, first screw and second screw, form the delivery chambers for the pumped medium. As the screw spindles rotate, the delivery chambers move in a machine direction and convey the medium from the suction side (= inlet) to the pressure side (= outlet).

This type of pump is particularly suitable for incompressible, also viscous media and for generating high pressures. Screw pumps are used both for the transport of single-phase and multiphase fluid media. A two-spindle twin-screw pump comprises a drive spindle (main rotor) which is arranged together with at least one driven spindle (secondary rotor) in a pump housing. The torque generated by the drive is transmitted from the drive spindle via gears to the driven spindle. The flow rate is from both ends, i. from the so-called suction sides of the

Pump, transported to the middle or pressure side of the pump.

The object of the invention is to simplify the pump design itself and, consequently, the installation of the screw pump.

The above object is achieved by a screw pump comprising the features in claim 1. Further advantageous embodiments are described by the subclaims. Beschreibunq

The invention relates to a screw pump for conveying a fluid medium, in particular for conveying viscous and / or abrasive media containing. The screw pump includes a pump housing having an inlet and an outlet for the medium to be delivered. At least two spindles are arranged in the pump housing. The spindles each consist of a shaft with at least two shaft sections and a profile section arranged therebetween. The profile sections of the at least two spindles are at least partially engaged with each other. The at least two spindles are rotatably mounted and at least partially arranged in the pump housing. The directly adjacent two spindles, whose profile sections at least partially engage each other, each rotate in an opposite direction of rotation. In particular, the first spindle rotates clockwise and the second spindle rotates counterclockwise or vice versa. The inlet for the medium to be pumped is on the suction side with the outside

Profile section of the spindles. The outlet for the medium to be conveyed is on the pressure side with the inner profile section in connection. A first of the at least two spindles is assigned a direct first drive. This first spindle is also called a drive spindle. According to the invention, at least a second of the at least two spindles is assigned a second direct drive.

The first drive and the second drive are preferably arranged substantially opposite one another, on each of the shaft ends of the spindles lying outside the pump housing.

According to a preferred embodiment, the screw pump comprises two spindles in a double-flow arrangement. Of the

Flow of the medium is from both ends, i. from the so-called suction sides of the screw pump, transported to the center or pressure side of the screw pump. Both spindles are each assigned a drive, i. it is in particular a screw pump with two directly driven spindles in a double-flow arrangement.

According to one embodiment of the invention, the drive is arranged on the respective spindles at a first end region, wherein the spindles preferably so are arranged parallel to each other lying side by side, that the respective drive-near areas of the spindles are located on the respective opposite side of the pump housing. The pump housing has a shaft bushing for each spindle for an external bearing for supporting a shaft section of the spindles between the first drive-near end portion and the profile area. The shaft passage of the first and the second spindle are located on opposite sides of the pump housing. The so-called drive end respectively opposite free shaft end of the spindles is preferably disposed respectively within the pump housing. According to a preferred embodiment, the free shaft end of the spindles is rotatably mounted within the pump housing, wherein the respective bearings are arranged substantially opposite each other.

The at least two spindles each having its own drive of a screw pump according to the invention are each assigned an outer bearing for a drive-near shaft region of the respective spindle, an inner bearing for the opposite free shaft end of the respective spindle and a sealing element for sealing the outer bearing. Compared to the screw pumps according to the known prior art thus only two instead of four shaft bushings must be sealed. The pump housing thus has only 50% of potential leak points compared to conventionally known pumps. Preferably, for the first drive and at least a second

Drive used identical electric motors. In particular, the speed at which the spindles are moved must be matched to the profiling of the profile section, so that the helices of the profile section form the delivery chambers and do not wedge together. The identical electric motors used may each be synchronous motors or asynchronous motors. The drives of the spindles can each be assigned a control via which the drives can each be controlled individually. In particular, the rotational speeds of the drives can be controlled individually via the controls in order to operate the spindles synchronously in each case. If, for example, asynchronous motors are used, it may happen that minimum

Speed differences occur during the rotation of the spindles. Here it is particularly important that the profile sections of the spindles follow the gearing law, so that the faster spindle entrains the slower accordingly, without the spindles becoming wedged and thus possibly being damaged. According to one embodiment of the invention, the opposite free shaft end of the spindles is rotatably mounted in each case in a so-called bushing. The liner is assigned a connection element. About the connection element of the bushing, a lubricant can be supplied. This is particularly necessary if the medium to be delivered does not have good lubricating properties or contains abrasives. The lubricant used is in particular clean and pressurized lubricating fluid. The pressure of the supplied lubricating fluid must be higher than the applied suction pressure of the screw pump. The lubricant mixes on exiting the bearings with the pumped medium and is discharged with this.

If, on the other hand, the conveyed medium has good lubricating properties and does not contain abrasives, lubrication of the free end mounted in the respective bush takes place through the conveyed medium itself. In this case, it is provided that spindles comprise bores along their longitudinal axis extend from the free end to the middle of the profile section. Via a transverse bore in the central region of the profile section, a fluid connection between the high-pressure interior of the screw pump and the bearing bushes can thus be produced. Due to the present in the screw pump pressure gradient medium to be conveyed from the high pressure side passes through the holes in the liners and lubricates this sufficient. Subsequently, the medium which has passed through the bores to the bearing points again mixes with the conveyed medium and is discharged therewith. This is an internal circuit where the pumped medium is also used as a lubricant for the bearings of the shaft ends of the spindles.

Figures describe

In the following, embodiments of the invention and their advantages with reference to the accompanying figures will be explained in more detail. The proportions of the individual elements to one another in the figures do not always correspond to the actual size ratios, since some shapes are simplified and other shapes are shown enlarged in relation to other elements for better illustration.

Figure 1 shows a schematic view of a conventional two-spindle screw pump according to the prior art. Figure 2 shows a first embodiment of a screw pump according to the invention.

Figure 3 shows a second embodiment of a screw pump according to the invention. Figures 4 and 5 show different perspective views of a screw pump according to the invention.

Figures 6 and 7 each show a sectional view through a screw pump according to the invention.

For identical or equivalent elements of the invention, identical reference numerals are used. Furthermore, for the sake of clarity, only reference symbols are shown in the individual figures, which are required for the description of the respective figure. The illustrated embodiments are only examples of how the device according to the invention can be designed and do not represent a final limitation. FIG. 1 shows a conventional two-spindle screw pump 1 according to the prior art comprising a drive spindle 3 in a double-flow design, a driven double-flow spindle 4, which are mounted in a pump housing 2 with or without wear body 6. The wear body 6 is a plug-in housing within the pump housing 2, in which the spindles 3, 4 run. If the wear body 6 run in, especially if the wear body 6 is worn, it can be easily replaced,

The spindles 3, 4 each comprise a first shaft section A1-3 or A1-4, a profile section P3, P4 and a second shaft section A2-3, A2-4. The pump housing 2 has four outer bearing points 7-3a, 7-3b, 7-4a and 7-4b and four shaft passages 5 for the spindles 3, 4. In the shaft passages 5, the spindles 3, 4 are rotatably mounted and at the outer bearing points 7-3a, 7-3b, 7-4a and 7-4b enter the spindles 3, 4 from the pump housing 2. At the shaft passages 5 mechanical seals 8 are provided as sealing elements for sealing the pump housing 2 to the outside. The drive spindle 3 is driven directly via a drive M. The torque generated by the drive M is from the

Drive spindle 3 via gears 9-3a, 9-3b, 9-4a and 9-4b transmitted to the driven spindle 4. The conventional two-spindle screw pump 1 according to the prior art is preferably used for pumping lubricating fluids or non-lubricating and multiphase fluids. Due to their design with many individual parts, in particular four shaft bushings 5 with mechanical seals 8, four outer bearing points 7-3a, 7-3b, 7-4a and 7-4b or shaft bearings and at least one pair of gears 9-3a, 9-3b, 9- 4a and 9-4b, the assembly of the illustrated screw pump 1 is complicated.

Figure 2 shows a first embodiment of a screw pump 10a according to the invention with a pump housing 12, which comprises two drive spindles 14-1 and 14-2. The two drive spindles 14-1 and 14-2 each comprise a drive-side first shaft section A1-1 or A2-1, a profile section P1, P2 and a bearing section L1, L2 for supporting the free end 16-1, 16-2 of the respective ones Drive spindle 14-1, 14-2 within the pump housing 12. The profile areas P1, P2 of the drive spindles 14-1, 14-2 in turn each have two opposing spindle windings with toothed profile. The profile is preferably designed especially for the rolling operation.

Each of the two drive spindles 14-1, 14-2 is directly driven by its own drive M1, M2, in particular by its own drive motor.

In contrast to the prior art shown in Figure 1, the screw pump 10a according to the invention comprises only two outer bearing points 7-1, 7-2, two shaft bushings 5 with mechanical seals 8 as sealing elements. The screw pump 10a according to the invention thus has only half of the shaft passages 5 to be sealed. Furthermore, no gearwheels 9-3a, 9- 3b, 9-4a, 9-4b (cf., FIG. 1) are required for transmitting the torque. As a result, the screw pump 10a according to the invention is cost-effective in the first place

Production and on the other cheaper in maintenance, as it contains less maintenance-prone components.

The mutually parallel drive spindles 14-1, 14-2 are mounted in the region of their bearing sections L1, L2 in so-called bushings 20-1, 20-2 within the pump housing 12. The drive spindles 14-1, 14-2 are arranged in opposite directions, so that the drives M1, M2 are arranged on opposite sides of the pump housing 12. Preferably, in the screw pump 10a thus constructed, the drive motors M1, M2 may be configured both as a synchronous motor and an asynchronous motor. This depends in particular on the medium to be delivered.

If the medium to be pumped does not have good lubricating properties or contains abrasives, lubrication of the liners 20-1, 20-2 via connection elements 22-1, 22-2 can be supplied with clean and pressurized lubricating fluid. The pressure of the supplied lubricating fluid must be higher than the applied suction pressure of the screw pump 10a. The lubricating fluid exiting at the liners 20-1, 20-2 mixes with the conveyed medium during the pumping process and is discharged therewith.

FIG. 3 shows a second embodiment of a screw pump 10b according to the invention. In this, the lubrication of the liners 20-1, 20-2 by the medium to be delivered itself, wherein the lubricating fluid due to the pressure gradient from the high pressure side in the spindle center via the holes 24-1 and 24-2 within the spindles 14-1, 14-2 in the liners 20-1, 20-2 passes. In this case, the medium to be pumped must be free of impurities and abrasives and have good lubricating properties.

Figures 4 and 5 show different perspective views of a screw pump according to the invention 0 and Figures 6 and 7 each show a sectional view through a screw pump 10 according to the invention. For the description of the reference numerals reference is made in particular to Figures 2 and 3. The drives M1, M2 of the spindles 14-1, 14-2 are each assigned a control S1, S2, via which the drives M1, M2 can be controlled individually. In particular, the speeds of the drives M1, M2 can be controlled individually via the controls S1, S2 in order to be able to operate the spindles 14-1, 14-2 synchronously in each case. If the spindles 14-1, 14-2 are operated, for example, with conventionally used asynchronous motors, it may happen that minimal speed differences occur. Here it is particularly important that the profile sections P1, P2 of the spindles 14-1, 14-2 follow the gearing law, so that the faster spindle 14-1 or 14-2 entrains the slower by means of gearing law. According to a further embodiment of the invention, not shown, a coupling of the controls S1, S2 or a common control for the drives M1, M2 of the spindles 14-1, 14-2 is provided

The invention has been described with reference to a preferred embodiment. However, it will be apparent to those skilled in the art that modifications or changes may be made to the invention without departing from the scope of the following claims.

LIST OF REFERENCES

1 screw pump

2 pump housings

3 drive spindle

4 driven spindle

5 shaft passage

6 wearing bodies

7 external depository

8 mechanical seals

9 gear

10 screw pump 12 pump housing

14 drive spindle

16 free end

20 bushing

22 connection element

24 hole

A shaft section

L bearing section

M drive

P profile section

S control

Claims

Expectations

Screw spindle pump (10) for conveying a fluid medium with a pump housing (2, 12) having an inlet and an outlet for the medium to be conveyed, with at least two spindles (3, 4, 14-1, 14-2) each consisting of one Shaft with at least two shaft sections (A1, A2) and a profile section (P) arranged between them, the profile sections (P) of the at least two spindles (3,4,14-1, 14-2) being at least partially in engagement with one another and where the at least two spindles (3,

4, 14-1, 14-2) are rotatably mounted at least partially in the pump housing (2, 12), a first of the at least two spindles (3, 14-1) being designed as a drive spindle, which is a direct first drive (M , M1), characterized in that at least a second of the at least two spindles (14-2) is assigned a second direct drive (M2).

Screw spindle pump (10) according to claim 1, wherein the first drive (M1) and the second drive (M2) are arranged largely opposite one another, each outside the pump housing (12).

Screw spindle pump (10) according to claim 1 or 2, wherein the screw spindle pump (10) comprises two spindles (14-1, 14-2) in a double-flow arrangement, each of the two spindles (14-1, 14-2) having its own drive (M1, M2) is assigned.

Screw spindle pump (10) according to one of the preceding claims, wherein the at least two spindles (14-1, 14-2), each with its own drive (M1, M2), are each arranged with a first end region on their respective drive (M1, M2), wherein the pump housing (12) has a shaft bushing (5) for an external bearing (7) for each spindle (14-1, 14-2) for supporting a shaft section of the spindles (14-1, 14-2) between the first one close to the drive End area and the profile area (P1, P2) and wherein the opposite free shaft end (16-1, 16-2) of the spindles (14-1, 14-2) is arranged and / or mounted within the pump housing (12).

5. Screw spindle pump (10) according to claim 4, wherein the opposite free shaft end (16-1, 16-2) of the spindles (14-1, 14-2) is rotatably mounted within the pump housing (12).

6. Screw spindle pump (10) according to one of the preceding claims, wherein the at least two spindles (14-1, 14-2), each with its own drive (M1, M2), each have an external bearing

(7) for a shaft area (A1) close to the drive of the respective spindle (14-1, 14-2), an internal bearing for the opposite free shaft end (16-1, 16-2) of the respective spindle (14-1, 14-2 ) and a sealing element (8) for sealing the shaft bushing (5) on the pump housing (2) is assigned 7. Screw spindle pump (10) according to one of the preceding claims, wherein for the first drive (M1) and the at least one second drive (M2) identical electric motors are used.

8. Screw spindle pump (10) according to claim 7, wherein the electric motors are synchronous motors or asynchronous motors.

9. Screw spindle pump (10) according to one of claims 5 to 8, wherein the opposite free shaft end (16-1, 16-2) of the spindles (14-1, 14-2) in a liner (20-1, 20-2 ) is rotatably mounted, the bushing (20-1, 20-2) being assigned a connecting element (22-1, 22-2), wherein a lubricant can be supplied via the connecting element (22-1, 22-2).

10. Screw spindle pump (10) according to one of claims 5 to 8, wherein the opposite free shaft end (16-1, 16-2) of the spindles (14-1, 14-2) in a liner (20-1, 20-2 ) is rotatably mounted, the spindles (14-1, 14-2) each comprising at least one bore (24-1, 24-2) for the passage of the conveyed medium to the bushings (20-1, 20-2).