DK2822693T3

DK2822693T3 - Drum centrifuge with an inlet accelerator and an outlet brake device

Info

Publication number: DK2822693T3
Application number: DK13715122.1T
Authority: DK
Inventors: Alfons Kellnberger
Original assignee: Flottweg Se
Priority date: 2012-03-10
Filing date: 2013-03-07
Publication date: 2018-09-03
Also published as: DE102012004548A1; EP2822693A2; WO2013135233A2; DE102012004548B4; WO2013135233A3; EP2822693B1

Description

Background of the invention

The invention relates to a drum centrifuge comprising a rotatable drum, a rotor which is rotatable relative to the drum, an intake acceleration device for taking in and accelerating medium to be centrifuged in circumferential direction into the drum and a discharge decelerating device for removing and decelerating clarified medium in circumferential direction from the drum, in which the intake acceleration device is rotatable separately from the rotor and is coupled to the discharge decelerating device in a manner that transmits rotational energy. Such a drum centrifuge is known from US 4 334 647 A.

Drum centrifuges of the aforementioned kind are used to separate flowable media into different heavy phases. Here medium is introduced into the drum and exposed to high centrifugal force in the latter, whereby a light phase floats to the top of a heavy phase and this results in phase separation. The light phase flows radially inwards from the drum, whereas the heavy phase is deposited on the inner side of the drum, i.e. radially outwardly. The deposited heavy phase can be lifted out of the light phase by means of the rotor, which is preferably designed in the form of a screw which rotates relative to the drum with a low speed differential, and removed from the drum in this way. When introducing the medium into the drum the latter has to be accelerated from its low flow speed to the high rotational speed of the drum. It is known to provide an intake acceleration device in order to cope with this acceleration using a comparatively small amount of energy. Such an intake acceleration device is known for example in the form of an acceleration rotor with channels, in which the medium to be introduced flows radially outwards from radially inwards and is accelerated in circumferential direction of the drum. This form of acceleration makes it possible to deposit the medium without impact as far as possible on the surface of the so-called pool, which is formed by the medium already located in the drum.

It is also known that energy can be recovered for driving the rotational movement of the drum from the medium flowing out of the drum centrifuge, in particular a light phase. For this usually at the outlet of the light phase or the centrate a discharge decelerating device or recovery device is provided to which the outflowing medium transmits energy. The discharge decelerating device is coupled to the drum according to known drum centrifuges so that the latter is driven by the latter.

Generally so-called damming rings, damming plates or scraping devices are known as discharge devices for removing the light phase from a drum centrifuge. By means of such removal devices however the kinetic energy of the removed medium is lost.

Underlying problem

The invention is based on the problem of creating a solid bowl wall centrifuge by means of which it is possible to achieve a highly effective energy efficiency with minimal structural effort.

Solution of the invention

Said problem is addressed according to the invention by a drum centrifuge, in which a rotatable drum, a rotor rotatable relative to the drum, an intake acceleration device for taking in and accelerating medium to be centrifuged in circumferential direction into the drum and a discharge decelerating device for removing and decelerating clarified medium in circumferential direction from the drum. Here the intake acceleration device is rotatable separately from the rotor and coupled to the discharge decelerating device in a manner that transmits rotational energy. According to the invention the energy-transmitting coupling of the intake acceleration device with the discharge decelerating device is formed as a direct coupling by means of a shaft, which is arranged between the intake acceleration device and the discharge decelerating device on the inside of the rotor.

By means of the solution according to the invention the energy required for accelerating the medium to be introduced is brought from the discharge decelerating device to the intake acceleration device or provided at the latter. This is achieved by coupling the intake acceleration device to the discharge decelerating device, which at least mostly returns the rotational energy of the discharge decelerating device to the intake acceleration device.

The drum centrifuge according to the invention has in particular the advantage that the kinetic energy of medium flowing through or out of the discharge decelerating device can be largely recovered or returned by a comparatively small number of structural components. The effectiveness of the energy recovery is therefore particularly high. According to the invention the rotational energy of the discharge decelerating device with a rotatable coupling element is transferred directly to the intake acceleration device. Such a direct coupling has a particularly low frictional resistance and can take up comparatively little space.

The drum of the drum centrifuge according to the invention is preferably designed as a solid bowl wall drum and the associated rotor is designed as a screw, wherein such a centrifuge is also referred to as a solid bowl centrifuge. Furthermore, the solution according to the invention can also be applied advantageously in screening screw centrifuges and in many screwless centrifuges.

According to the invention the torque-transmitting coupling of the intake acceleration device with the discharge decelerating device is formed by means of a shaft. The intake acceleration device is coupled to the discharge decelerating device by means of the shaft. Such a shaft can be arranged between an intake area inside the rotor and an outlet area on and end face of the drum as a comparatively small and light component. The shaft then has a low mass and a particularly small inertia moment at the same time as having high flexural strength. In this way it reacts particularly rapidly to acceleration and deceleration and bending vibrations caused by self-resonance can be avoided.

By means of the shaft preferably at the same time an intake section is formed for medium to be introduced. The shaft then at the same time forms a path over which medium to be centrifuged is introduced into the drum. For this purpose the shaft is preferably designed as a hollow shaft. Such a hollow cylindrical shaft can transmit comparatively high torques with a small inertia moment.

Particularly preferably the unit formed by the intake acceleration device and the discharge decelerating device can be driven from outside the drum. Such an external drive makes it possible to influence the formed unit, in particular in that the latter is additionally driven or decelerated in order in particular to add or remove power. For driving or braking particularly preferably the shaft is brought out of the drum and coupled to a motor or a generator operated brake. In this way also energy from the inside, i.e. from the discharge decelerating device, can be transmitted externally e.g. to a generator. In general however, the intake acceleration device can also be driven by means of a motor. Due to the direct coupling of the discharge decelerating device to the intake acceleration device according to the invention the energy recovery then has a direct effect on said power input.

The intake acceleration device is formed particularly advantageously by radial channels. Such channels run through a circular acceleration rotor essentially in radial direction and are designed to be preferably curved. By means of the curvature the medium, which is supplied through the channels, can be directed specifically in its direction of movement and movement speed. The thus directed medium can then be deposited as intended with low impact onto the surface of the pool.

The intake acceleration device is also preferably designed such that the introduced medium is guided to the latter in radial and axial direction. In this way an additional axial movement component is added to the supplied medium, by means of which it is guided via the intake acceleration device and finally reaches the pool. Such a movement thus comprises, apart from the radial movement component, an axial movement component, whereby an additional degree of freedom can be used for guiding and directing the medium. For this the intake acceleration device is preferably designed to be conical. A cone used for this can be produced inexpensively and can be configured in many different ways. In particular, ribs can be formed on the latter in order to transmit the desired acceleration energy to the medium to be supplied.

In a further advantageous embodiment the discharge decelerating device is designed to have a scraping device. Such a scraping device is often already provided in conventional drum centrifuges and can be reconfigured according to the invention in a simple manner to thereby provide a recovery of energy coupled with the intake acceleration device.

The discharge decelerating device is preferably designed to have a turbine impeller. Such an impeller in turbine form can be adapted specifically to the respective application. It is therefore possible to provide a variation of the energy recovery, in particular when processing different media in a type of drum centrifuge.

With regard to the mechanical bearing of the intake acceleration device the latter is preferably supported relative to the rotor and inside the rotor itself. A bearing provided for this purpose in the rotor for the intake acceleration device transmits introduced transverse forces directly and with a short flow of force to the rotor. The rotor itself is also supported in a stable manner in the drum even in known drum centrifuges, so that in general this ensures the distribution of forces of the intake acceleration device in an inexpensive and also stable manner.

In this respect the discharge decelerating device is preferably supported relative to the drum and inside the drum. By means of such a support of the discharge decelerating device relative to the drum the same advantages are achieved as above. Furthermore, it is possible by means of this bearing that the unit consisting of the intake acceleration device and the discharge decelerating device is arranged as a whole inside the drum and (if desired) does not need to be guided outwardly.

Brief description of the drawings

In the following an embodiment of the solution according to the invention is explained in more detail with reference to the accompanying schematic drawings. In the latter:

Fig. 1 is a longitudinal cross-section of a first embodiment of a drum centrifuge according to the invention,

Fig. 2 is a longitudinal cross-section of a second embodiment of a drum centrifuge according to the invention,

Fig. 3 is a longitudinal cross-section of a third embodiment of a drum centrifuge according to the invention,

Fig. 4 is a longitudinal cross-section of a fourth embodiment of a drum centrifuge according to the invention,

Fig. 5 is a longitudinal cross-section of a fifth embodiment of a drum centrifuge according to the invention,

Fig. 6 is a longitudinal cross-section of a sixth embodiment of a drum centrifuge according to the invention,

Fig. 7 is a longitudinal cross-section of a seventh embodiment of a drum centrifuge according to the invention und

Fig. 8 is a longitudinal cross-section of an eighth embodiment of a drum centrifuge according to the invention.

Detailed description of the embodiments

Fig. 1 shows a drum centrifuge 10, which is designed to have an essentially cylindrical housing 12. In the housing 12 an essentially circular cylindrical and slightly conical drum 16 is mounted rotatably about an axis 14. The rotatable bearing is formed by a first drum bearing 18 (on the left in the Figure) on a first support 20 and by a second drum bearing 22 (on the right in the Figure) on a second support 24. The drum 16 is shifted into high speed during the operation of the drum centrifuge 10 by a drum drive 26 (here in the form of a pulley driven by a not shown electric motor).

In the drum 16 there is a rotor 28 in the form of a screw. The rotor 28 is rotatable relative to the drum 16 and can also be driven by means of a rotor drive 30 (again in the form of a pulley) from outside the housing 12. The rotor 28 in the form of a screw comprises an essentially circular cylindrical and also partly conical screw hub 32 which also may be stepped in diameter and which is designed to be at least partly hollow. The screw hub 32 is surrounded on the outside by a screw coil 34 which extends radially close to the inside of the drum 16. The screw coil 32 also has a cylindrical and a conical section. So that the rotor 28 is rotatable relative to the drum 16 (in relation to the Figures) on the left side a first rotor bearing 36 is provided in the drum 16. On the right side the rotor 28 is supported by a second rotor bearing 38 on an extension of the drum 16 projecting inwards.

The arrangement of this kind is used for centrifuging and separating a medium into a plurality of different heavy phases, wherein the medium is introduced through an intake section 40 into the drum 16. The intake section 40 is formed by means of a straight, central inlet pipe, which extends attached in a fixed position along the axis 14 inside the rotor 28 and thus the screw hub 32. The medium supplied to the inside of the screw hub 32 reaches an inlet 42 through the screw hub 32. The inlet 42 is formed by an intake acceleration device 44 in the form of a radial channel disc (cf. Fig. 1, 3, 5, 6, 7 and 8) or an intake acceleration device 46 in the form of a conical disc (cf. Fig. 2 and 4) and a plurality of intake openings 48 which direct the medium through the screw hub 32.

The intake acceleration devices 44 and 46 rotate during the operation of the drum centrifuge 10. They are used to supply kinetic energy specifically to the introduced medium, in that it is directed radially and is thereby accelerated in circumferential direction until it flows through an intake opening 48 in the screw hub 32. Radially outside the intake openings 48 the supplied medium is then deposited or introduced onto a pool 50 forming in the drum 16 with the previously supplied medium. Said depositing or introduction can thus be performed with little impact, thereby avoiding energy loss caused by friction in the medium.

In the pool 50 a light phase 52 or a clarified centrate and a heavy phase 54 are separated due to the created centrifugal force, from which the heavy phase 54 is removed by means of the screw coils 34 from an outlet 56 in the drum. The thus removed heavy phase 54 then flows down through a discharge opening 58 in the housing 12.

The light phase 52 floats on the heavy phase 54 and reaches an outlet 60, where it flows out through a discharge opening 62. In the embodiments according to Fig. 1, 2 and 3 at the outlet 60 a discharge decelerating device 64 with a scraping disc 66 is provided for recovering the kinetic energy provided in the outflowing medium. The scraping disc 66 is designed to have radial channels 68, which are each followed in flow direction by an axial channel 70 through which the light phase 52 is directed outwards under pressure to the second support 24. In the discharge decelerating device 64 according to Fig. 8 a scraping disc 66 is provided with a pipe channel 72 with an adjustable radius, which at the same time diverts the medium of the removed light phase 52 in tangential direction. In the embodiments according to Fig. 4 to 7 a discharge decelerating device 74 is designed in the form of a turbine wheel 76 which is provided radially on the exterior with turbine blades 78. The turbine blades 78 are supplied with flow of medium of the outflowing light phase 52 and direct the latter to the discharge opening 62 which opens in said embodiments into the housing 12.

The said intake acceleration devices 44 and 46 are coupled to the associated discharge decelerating devices 64 and 74 respectively directly by means of a shaft 80 on the inside of the rotor 28 in a torque transmitting manner. For this purpose in particular the radial channel disc (Fig. 1, 3, 5, 6, 7 and 8) and the conical disc (Fig. 2 and 4) of the intake acceleration devices 44 and 46 are connected to the shaft 80 and the scraping disc 66 and the turbine wheel 76 are coupled to the shaft 80. In the embodiments according to Fig. 1 to 6 said coupling is configured directly, whereas in the embodiments according to Fig. 7 and 8 the coupling is formed by a drive disc 82 and a pot section 84. The construction with the pot section 84 makes it possible for the unit of intake acceleration device and discharge decelerating device coupled on the inside of the rotor 28 to also be accessible outside the housing 12 and in particular driven there. In the embodiments according to Fig. 3 and 6 it is also possible to have an external drive with a drive disc 82. For this a pipe section 86 is formed adjoining the shaft 80, which forms the connection externally for the drive disc 82 provided there.

The shaft 80 is supported, on the left in Figures, by means of a bearing 88 on the inside of the rotor 28 on a radially extending rotor disc 90 against the screw hub 32. On the side of the discharge decelerating devices 64 and 74 (on the right in the Figures) the shaft 80 in the embodiments according to Fig. 1 to 6 is supported axially on the exterior by the scraping disc 66 or the turbine wheel 76 directly against the drum 16. In the embodiments according to Fig. 7 (turbine wheel 76) and Fig. 8 (adjustable scraping disc 66) a bearing 94 is provided for supporting the shaft 80 which bearing surrounds the pot section 84 externally and supports it against the second support 24. Radial inwardly from said bearing 94 the second drum bearing 22 is arranged which supports the drum 16 internally against the pot section 84 and thereby indirectly also against the second support 24.

For securing the intake section 40 configured as an inlet pipe, lastly in the embodiments according to Fig. 3, 6, 7 and 8 a third support 96 is provided. Said third support 96 supports the intake pipe on the outer end section against the second support 24 and thereby encloses the drive disc 82 provided in this area such that the latter is accessible for a (not shown) belt drive.

Lastly, it should be noted that all of the features which are described in the application materials and in particular in the dependent claims, despite the formal reference back to one or more specific claims, are also protected individually or in any combination.

List of reference numerals 10 drum centrifuge 12 housing 14 axis 16 drum 18 drum bearing 20 support 22 drum bearing 24 support 26 drum drive 28 rotor 30 rotor drive 32 screw hub 34 screw coil 36 first rotor bearing 38 second rotor bearing 40 intake section 42 inlet 44 intake acceleration device in the form of a radial channel disc 46 intake acceleration device in the form of a conical disc 48 intake opening in the screw hub 50 pool 52 light phase 54 heavy phase 56 outlet for the heavy phase 58 discharge opening in the housing for the heavy phase 60 outlet for the light phase 62 discharge opening for the light phase 64 discharge decelerating device in the form of a scraping device 66 scraping disc 68 radial channel 70 axial channel 72 pipe channel 74 discharge decelerating device in the form of a turbine wheel 76 turbine wheel 78 turbine blade 80 shaft 82 drive disc 84 pot section 86 pipe section 88 bearing 90 rotor disc 92 bearing 94 bearing 96 support

Claims

A drum centrifuge (10) having a rotatable drum (16), a rotor (28) rotatable relative to the drum (16), an inlet acceleration device (44; 46) for introducing and accelerating in peripheral direction of medium which must be centrifuged, in the drum (16) and an outlet braking device (64; 74) for emptying and braking in the circumferential direction of the clarified medium from the drum (16), whereby the inlet acceleration device (44; 46) can rotate separately relative to the rotor (28) and rotary energy transferring is coupled to the outlet brake device (64; 74), characterized in that the rotational energy transferring coupling of the inlet acceleration device (44; 46) with the outlet brake device (64; 74) is formed by direct coupling. shaft (80) disposed between the inlet acceleration device (44; 46) and the outlet brake device (64; 74) in the interior of the rotor (28).

The drum centrifuge according to claim 1, wherein an inlet section is formed simultaneously with the shaft (80).

The drum centrifuge according to claim 1 or 2, wherein the unit formed by the inlet acceleration device (44; 46) and the outlet brake device (64; 74) is designed to be driven from the outside of the drum (16).

Drum centrifuge according to one of claims 1 to 3, wherein the inlet acceleration device (44) is formed with radial channels.

The drum centrifuge according to any one of claims 1 to 3, wherein the inlet acceleration device (46) is formed so that the medium introduced thereto is guided in a radial and axial direction.

A drum centrifuge according to any one of claims 1 to 5, wherein the outlet brake device (64) is realized with a vane wheel disk (66).

Drum centrifuge according to one of claims 1 to 5, wherein the outlet brake device (74) is realized with a turbine wheel (76).

The drum centrifuge according to one of claims 1 to 7, wherein the inlet acceleration device (44; 46) relative to the rotor (28) is housed within the rotor (28).

The drum centrifuge (10) according to one of claims 1 to 8, wherein the outlet braking device (64; 74) relative to the drum (16) is housed within the drum (16).