EP2789395B1 - Solid bowl screw centrifuge with an energy recovery device - Google Patents

Description

The invention relates to a solid bowl screw centrifuge with a rotatable in operation about a longitudinal axis of the centrifuge drum, at least one outflow opening for discharging clarified Good from the centrifuge drum is formed, which is provided with a discharge opening radially outwardly limiting weir edge, and an energy recovery device is designed to recover energy of the effluent, clarified good. Furthermore, the invention also relates to such an energy recovery device for attachment to a front side of a centrifuge drum.

In generic Vollmantelschneckenzentrifugen it is well known to provide on the centrifuge drum frontally more outlet openings, through which the clarified Good can flow out via a respectively associated weir edge. The weir edge forms the radially inner edge of an associated weir plate, which is mounted radially adjustable on the end face of the centrifuge drum.

So that the kinetic energy of the outflowing material can be used again for driving the rotary motion of the centrifuge drum, energy recovery devices are now provided at such weir edges. So Among other things, it is known to provide on the front side of a centrifuge drum deflection devices with which the flow of material of the clarified Guts is diverted in the tangential direction. The then not axially, but tangentially against the direction of rotation of the centrifuge drum exiting Good the centrifuge drum transmits a pulse in the direction of rotation, which drives the centrifuge drum accordingly in the direction of rotation. Such deflectors are made, for example WO 2012 013624 A2 known.

Out US Pat. No. 7,022,061 B2 is a solid bowl screw centrifuge with a rotatable about a longitudinal axis in operation centrifuge drum known, at the end face two outflow openings, a first outflow opening and a second outflow opening are provided for the discharge of clarified Good from the centrifuge drum. The first outflow opening has a weir edge which delimits the outflow opening radially outward. Before the second outflow opening, an energy recovery device for recovering energy of the effluent, clarified material is formed, which is designed as a flow-through from the effluent, clarified Good Abströmrohr.

Underlying task

The invention has for its object to provide a Vollmantelschneckenzentrifuge whose energy recovery device is particularly effective.

Inventive solution

This object is achieved with a solid bowl screw centrifuge according to claim 1. The object is also achieved with an energy recovery device, which is adapted for attaching directly axially outside of an associated outflow opening and designed as a flowed through by the outflowing, clarified Good Abströmrohr.

In the solid bowl screw centrifuge according to the invention, the outflow opening in the end face of the centrifuge drum extends essentially transversely to the longitudinal axis of the centrifuge. At the outflow opening is located radially outwardly the weir edge, which can be at least slightly advantageous aligned obliquely to the longitudinal axis. Immediately axially outside the discharge opening is located substantially at the height or the radius of the weir edge, the energy recovery device according to the invention, which is designed as a over its entire circumference substantially closed tube. The pipe of this type thus forms axially outside the discharge opening a discharge line which is closed over its entire circumference. This outflow tube acts with respect to the longitudinal axis radially outward like an outflow channel or a discharge channel and is at the same time closed radially in relation to the longitudinal axis.

The solution according to the invention is based on the recognition that the energy-recovering effect of energy recovery devices of the type mentioned is based, in particular, on the fact that this energy recovery device is closed on its radially inner side. With this design, the flowing through the energy recovery device Good is protected within this against external, aerodynamic influences. On the outside of the rotating at high speed centrifuge drum otherwise the local air acts considerably on the outflowing Good, whereby this loses part of its energy content by friction with this air. With the solution according to the invention, this energy loss is avoided, so that more energy can be recovered from the effluent. With the solution according to the invention, the outflowing material, in contrast to previously known solutions, can be deflected in a particularly homogeneous and targeted manner from the axial direction substantially in the tangential direction. At the same time energy losses, which would result from a derivative of the outflowing material in the radial direction can be avoided. With the discharge pipe according to the invention arranged axially outside the outflow opening, the outflowing material during the deflection is largely kept at the radius of the associated weir edge, whereby, like will be explained below, even smaller changes in the radius of the flow path can be advantageous.

In such a solid bowl screw centrifuge, the centrifuge drum can be advantageously configured to be rotatable in two mutually opposite directions of rotation. In this case, the outflowing, clarified material is preferably deflected counter to a respective direction of rotation of the centrifuge drum with the outflow pipe. The energy recovery device according to the invention can also be designed with two active surfaces as outflow tubes, of which the one active surface in a first direction of rotation and the second direction of rotation in the second direction unfolds effect.

In the solid bowl screw centrifuge according to the invention, the outflow tube is advantageously designed at least with a section with a substantially straight flow path which is inclined at an angle between 45 ° and 85 °, preferably between 55 ° and 65 °, of the longitudinal axis of the centrifuge drum. The outflow pipe according to the invention preferably also has at least one section with a substantially straight flow path, which is inclined to the tangential direction at the outflow opening by an angle of 4 ° to 28 °, preferably 8 ° radially inwardly. The bottom surface of such a section is particularly advantageous at least partially flat or largely designed flat. Such a bottom surface can be manufactured inexpensively. In addition, the material flowing therefrom over a longer distance undergoes a uniform and thus comparatively easy model-technically comprehensible acceleration. The acceleration leads to an increased conversion of the centrifugal force pulse into a tangentially directed motion pulse. It is converted into tangential drive energy as a particularly large proportion of the centrifugal force energy. The flat portion of the bottom surface is particularly preferably inclined to the tangential direction by an angle of 4 ° to 28 °, preferably 8 ° radially inwardly. Such an orientation of the deflected Gutstrahls leads in comparison to a purely tangential flow to a targeted predefined deceleration of the exiting stream and thus to a precisely predetermined accumulation effect. This jamming brings an increase in the potential energy of the flowing material and thus an improved subsequent conversion into tangential kinetic energy with it.

Furthermore, the outflow pipe according to the invention preferably has a Abstrommündung with a flow path or flow direction, which is inclined with respect to the longitudinal axis of the centrifuge drum at an angle between 70 ° and 90 °, preferably between 77 ° and 83 °. With the flow direction of this type, the outflowing material is deflected from initially axially to substantially tangentially, ie transversely thereto. A deflection to less than 90 ° with respect to the longitudinal axis has the advantage that the emerging from the Abstrommündung Good is less strongly directed against the end face of the centrifuge drum and therefore there occur less friction losses.

The solution according to the invention also advantageously provides a solid shell screw centrifuge, in which the outflow pipe is designed in the flow direction of the discharged, clarified material with a constant large flow cross section. Alternatively, the outflow pipe is designed in the flow direction of the outflowing, clarified material with decreasing, in particular conically tapered, flow cross section. The non-tapered flow shape reduces the risk of clogging of the discharge tube during operation of the associated solid bowl centrifuge. The tapered tube shape creates an additional stowage effect resulting in improved energy recovery.

Preferably, in the solid bowl screw centrifuge according to the invention, the outflow pipe is further designed with a round, in particular circular or elliptical cross section. Alternatively, the discharge pipe is designed with a rectangular, in particular square cross-section. The two mentioned cross-sectional shapes lead to particularly cost-recoverable energy recovery devices. Furthermore, these cross sections are particularly suitable in order to allow the effluent to flow off in advance. A rectangular cross-section also has the advantage that the outflowing material exits at the associated Abströmmündung on a wide plane to a predefined radius.

Finally, in the case of the solid bowl screw centrifuge according to the invention, preferably the outflow pipe is still designed on its outer wall turned in the direction of rotation with an adapted aerodynamic outer wall shape. With this outer wall shape, the flow resistance of the energy recovery device and thus the associated energy loss can be reduced. Under aerodynamically adapted outer wall form is understood to mean a shape that offers the lowest possible flow resistance for incoming air. Such a shape is rounded, has no edges and is provided with a smooth, less rough surface.

Brief description of the drawings

Fig. 1

einen Längsschnitt einer Zentrifugentrommel mit Wehrplatte und Energierückgewinnungseinrichtung einer Vollmantelschneckenzentrifuge gemäß dem Stand der Technik,

Fig. 2

den Längsschnitt II - II in Fig. 1,

Fig. 3

eine Seitenansicht einer Zentrifugentrommel mit Wehrplatte und Energierückgewinnungseinrichtung eines ersten Ausführungsbeispiels einer Vollmantelschneckenzentrifuge gemäß der Erfindung,

Fig. 4

den Längsschnitt IV - IV gemäß Fig. 3,

Fig. 5

die Ansicht V gemäß Fig. 4,

Fig. 6

eine Seitenansicht einer Zentrifugentrommel mit Wehrplatte und Energierückgewinnungseinrichtung eines zweiten Ausführungsbeispiels einer Vollmantelschneckenzentrifuge gemäß der Erfindung,

Fig. 7

den Längsschnitt VII - VII gemäß Fig. 6,

Fig. 8

die Ansicht VIII gemäß Fig. 7,

Fig. 9

eine Seitenansicht einer Zentrifugentrommel mit Wehrplatte und Energierückgewinnungseinrichtung eines dritten Ausführungsbeispiels einer Vollmantelschneckenzentrifuge gemäß der Erfindung,

Fig. 10

den Längsschnitt X - X gemäß Fig. 9,

Fig. 11

die Ansicht XI gemäß Fig. 10,

Fig. 12

eine Seitenansicht einer Zentrifugentrommel mit Wehrplatte und Energierückgewinnungseinrichtung eines vierten Ausführungsbeispiels einer Vollmantelschneckenzentrifuge gemäß der Erfindung,

Fig. 13

den Längsschnitt XIII - XIII gemäß Fig. 12,

Fig. 14

die Ansicht XIV gemäß Fig. 13,

Fig. 15

eine Seitenansicht einer Zentrifugentrommel mit Wehrplatte und Energierückgewinnungseinrichtung eines fünften Ausführungsbeispiels einer Vollmantelschneckenzentrifuge gemäß der Erfindung,

Fig. 16

den Längsschnitt XVI - XVI gemäß Fig. 15,

Fig. 17

die Ansicht XVII gemäß Fig. 16,

Fig. 18

den Längsschnitt XVIII - XVIII gemäß Fig. 19 einer Zentrifugentrommel mit Wehrplatte und Energierückgewinnungseinrichtung eines sechsten Ausführungsbeispiels einer Vollmantelschneckenzentrifuge gemäß der Erfindung,

Fig. 19

eine Seitenansicht der Zentrifugentrommel gemäß Fig. 18,

Fig. 20

den Längsschnitt XX - XX gemäß Fig. 21 einer Zentrifugentrommel mit Wehrplatte und Energierückgewinnungseinrichtung eines siebten Ausführungsbeispiels einer Vollmantelschneckenzentrifuge gemäß der Erfindung und

Fig. 21

eine Seitenansicht der Zentrifugentrommel gemäß Fig. 20.

An exemplary embodiment of the solution according to the invention will be explained in more detail below with reference to the attached schematic drawings. It shows:

Fig. 1

a longitudinal section of a centrifuge drum with weir plate and energy recovery device of a solid bowl screw centrifuge according to the prior art,

Fig. 2

the longitudinal section II - II in Fig. 1 .

Fig. 3

a side view of a centrifuge drum with weir plate and energy recovery device of a first embodiment of a solid bowl screw centrifuge according to the invention,

Fig. 4

the longitudinal section IV - IV according to Fig. 3 .

Fig. 5

the view V according to Fig. 4 .

Fig. 6

a side view of a centrifuge drum with weir plate and energy recovery device of a second embodiment of a solid bowl screw centrifuge according to the invention,

Fig. 7

the longitudinal section VII - VII according to Fig. 6 .

Fig. 8

the view VIII according to Fig. 7 .

Fig. 9

a side view of a centrifuge drum with weir plate and energy recovery device of a third embodiment of a solid bowl screw centrifuge according to the invention,

Fig. 10

the longitudinal section X - X according to Fig. 9 .

Fig. 11

the view XI according to Fig. 10 .

Fig. 12

a side view of a centrifuge drum with weir plate and energy recovery device of a fourth embodiment of a solid bowl screw centrifuge according to the invention,

Fig. 13

the longitudinal section XIII - XIII according to Fig. 12 .

Fig. 14

the view XIV according to Fig. 13 .

Fig. 15

a side view of a centrifuge drum with weir plate and energy recovery device of a fifth embodiment of a solid bowl screw centrifuge according to the invention,

Fig. 16

the longitudinal section XVI - XVI according to Fig. 15 .

Fig. 17

the view XVII according to Fig. 16 .

Fig. 18

the longitudinal section XVIII - XVIII according to Fig. 19 a centrifuge drum with weir plate and energy recovery device of a sixth embodiment of a solid bowl screw centrifuge according to the invention,

Fig. 19

a side view of the centrifuge drum according to Fig. 18 .

Fig. 20

the longitudinal section XX - XX according to Fig. 21 a centrifuge drum with weir plate and energy recovery device of a seventh embodiment of a solid bowl screw centrifuge according to the invention and

Fig. 21

a side view of the centrifuge drum according to Fig. 20 ,

Detailed description of the embodiments

In the Fig. 1 and 2 is represented by a solid bowl screw centrifuge 10 whose centrifuge drum 12 with its end face or end wall 14. On the end wall 14 one of a plurality of axially, in the direction of a longitudinal axis 18 of the centrifuge drum 12 through the end wall 14 protruding outflow openings 16 is illustrated. On the outside in front of the discharge opening 16, a weir plate 20 is stationary, but adjustably mounted on the end wall 14. The weir plate 20 protrudes up to the discharge opening 16 so that it covers the outside at its radially outer region. In this case, the weir plate 20 at its radially inwardly directed edge to a weir edge 22. The weir edge 22 according to the prior art extends along the end wall 14 and thus transversely to the longitudinal axis 18. The weir edge 22 holds in the centrifuge drum 12 clarified Good 24 back, so that in operation of the solid bowl centrifuge 10 this clarified Good 24 there with a Pond depth 26 accumulates and subsequently flows largely continuously over the weir edge 22 away.

In the flow direction of the clarified material 24 behind or downstream of the weir edge 22 is located axially on the outside of the weir plate 20, an energy recovery device 28 according to the prior art. This energy recovery device 28 is designed as a discharge channel or a discharge channel 30 which has a flat bottom surface 32 that extends tangentially at the height of the weir edge 22. To the bottom surface 32 extends as part of the outflow channel 30 perpendicular to a deflection surface 34, which extends arcuately according to the prior art in front of the viewed in the longitudinal direction open region of the discharge opening 16.

The deflecting surface 34 deflects the clarified good 24, which flows axially through the discharge opening 16 radially inwards, under the weir edge 22 in an inflow direction 38, in a tangential direction to a discharge direction 40. In this case, the centrifuge drum 12 rotates in a direction of rotation 36 and the clarified Good 24 is so deflected by the deflection surface 34 that it emerges tangentially from the energy recovery device 28 against this direction of rotation 36. With the exit, the clarified Good 24 "pushes" from the centrifuge drum 12, whereby it transmits to this part of its pulse and contributes to an energy recovery at the centrifuge drum 12. This "repulsion" is mitigated by the internal fluid friction in the clarified Good 24 and the fact that the centrifuge drum 12 at the same time continues to rotate in the direction of rotation 36. The centrifuge drum 12 thus gives way to the repulsion partially.

In the Fig. 3 to 5 is a first embodiment of a solid bowl screw centrifuge 10 illustrated with the centrifuge drum 12, on which an energy recovery device 42 according to the invention is arranged. The energy recovery device 42 also has the weir plate 20 of conventional type in front of the associated outflow opening 16. On the weir plate 20 is axially outside a discharge pipe 44 which is flowed through by the exiting through the discharge opening 16, outflowing, clarified Good.

In this case, the outflow pipe 44 is located directly in front of the otherwise open region of the outflow opening 16 with respect to its cross section, so that it is completely covered on the outside by the outflow pipe 44. Accordingly, no air flow can act on the passage of the clarified Guts at the outlet opening 16 from the outside, resulting in a particularly uniform, in particular purely laminar flow with appropriate purity of the discharged, clarified Guts. The outlet pipe 44 is located at the height or the radius of the weir edge 20, so that the material flowing through it undergoes virtually no change in position in the radial direction and accordingly no energy losses result.

At its periphery, the discharge pipe 44 is completely closed and as such forms a tubular conduit with an inlet port 46 in front of the discharge port 16 and a discharge port 48 at its other, outer end. there acts in relation to the longitudinal axis radially outer part of this tube as a discharge channel or a discharge channel and is at the same time radially inwardly closed with respect to the longitudinal axis of the centrifuge drum 12. As a result, the material flowing out through the energy recovery device 42 is also protected inside the outflow pipe 44 against external, aerodynamic influences. The material is deflected homogeneously and without turbulence purposefully from the axial direction or inflow direction 38 substantially in the tangential direction or outflow direction 40.

With the outflow pipe 44, the outflowing material during the deflection is largely maintained on the radius of the weir edge 22, wherein the outflow pipe 44 in the side view ( Fig. 3 ) straight flow path 50 which is inclined to the tangential direction 52 at the discharge opening 16 by an angle 54 of 6 ° to 8 ° radially inwardly. An associated bottom surface 56 of the outflow pipe 44 is flat or largely designed flat and also at an angle 54 of 6 ° to 8 ° obliquely to the tangential direction 52. At the same time, the outflow pipe 44 according to the Fig. 3 to 5 a rectangular flow cross-section 56, which is starting from the Einströmmündung 46 continuously tapered to Abströmmündung 48. With such a taper, the outflowing material is additionally jammed and bundled into a beam.

In the embodiment of an energy recovery device 42 according to the Fig. 6 to 8 the local outflow pipe 44 is designed with an oval flow cross section 56. The flow cross-section 56 of this type likewise tapers over the flow path of the outflowing material through the outflow pipe 44. In this case, the outflow pipe 44 downstream of the inlet orifice 46 has a section with a longitudinal section ( Fig. 7 ) substantially straight flow path 58, which is inclined to the longitudinal axis 18 of the centrifuge drum at an angle 60 between 55 ° and 65 °. Overall, this design for the outflow pipe 44 is a teardrop shape (see Fig. 6 ), which is aerodynamically particularly advantageous.

The Fig. 9 to 11 show an embodiment of an energy recovery device 42, in which the outflow pipe 44 is designed with a substantially circular flow cross-section 56. At the same time, the flow path 58, which is essentially straight in longitudinal section, extends over the entire length of the outflow pipe 44, so that it is designed overall as a straight, cylindrical pipe. The solution of this kind is very inexpensive to produce.

In the Fig. 12 to 14 an embodiment of an energy recovery device 42 is illustrated, in which the associated outflow pipe 44 is designed in front of the discharge opening 16 as an inclined conical tube. The tube is inclined to the longitudinal axis 18 at an angle 60 of 60 °, conically over its entire length and designed to be rectangular in the flow cross-section 56. The height of the flow cross-section 56 is kept constant over the length of the outflow pipe 44.

The in the 15 to 17 illustrated energy recovery device 42 is designed with a kinked outflow pipe 44 having a behind a first portion at an angle 60 to the longitudinal axis 18 of 30 ° a second portion with an angle 64 to the longitudinal axis 18 of 75 °. This second section forms a flow direction 62 at the associated exhaust port 48, so that the local flow path or flow direction 62 with respect to the longitudinal axis 18 of the centrifuge drum 12 is also inclined at an angle 64 of 75 °. With the flow direction 62 of this type, the outflowing material is deflected in principle transversely to the longitudinal axis 18, but at the same time is not deflected so strongly against the end wall 14 that energy losses occur there due to fluid friction during the outflow.

Finally, in the embodiments according to the Fig. 15 to 21 the local outflow pipe 44 is designed on its outer wall 66 facing in the direction of rotation 36 with an adapted aerodynamic outer wall form 68. The outer wall shape 68 is such that the wall thickness, starting from the inlet port 46 decreases steadily in the flow direction of the outflowing material to Abströmmündung 48. Thus, the outside of the outer wall 66 with respect to the air flowing there when rotating the centrifuge drum 12 is flatter and thus designed less in terms of the flow resistance. At the same time, this form of wall thickness is advantageous in view of a high rigidity of the outflow pipe 44 in relation to its weight.

In the embodiment according to FIGS. 18 and 19 is this shape design of a discharge pipe 44 with a continuously tapering, inner flow cross-section 56 and a continuous arc shape similar to those in Figs Fig. 3 to 5 combined. The embodiment according to the FIGS. 20 and 21 also shows a continuous arc shape of the discharge pipe 44, wherein the flow cross-section 56 is kept the same size over the entire flow length. With such a flow cross-sectional profile, clogging of the outflow pipe 44 with outflowing material is additionally prevented.

LIST OF REFERENCE NUMBERS

10

Solid bowl screw centrifuge

12

centrifuge drum

14

bulkhead

16

outflow

18

Longitudinal axis of the centrifuge drum

20

weir plate

22

weir edge

24

clarified good

26

pond depth

28

Energy recovery device according to the prior art

30

Outflow channel according to the prior art

32

Floor surface according to the prior art

34

Deflecting surface according to the prior art

36

direction of rotation

38

Inflow direction of the clarified material (axial)

40

Outflow direction of the clarified material (tangential)

42

Energy recovery device according to the invention

44

outflow pipe

46

Einströmmündung

48

Abströmmündung

50

in the side view straight flow path

52

tangential

54

Angle between tangential direction and plane flow path in side view

56

Flow area

58

in longitudinal section straight flow path

60

Angle between longitudinal axis and plane flow path in longitudinal section

62

Flow direction at the Abströmenündung

64

Angle between longitudinal axis and flow direction at the Abströmenündung

66

in the direction of rotation facing outer wall of the outlet pipe

68

aerodynamic outer wall shape

Claims (10)

1. Solid-bowl screw centrifuge (10) with a centrifuge drum (12) which can rotate about a longitudinal axis (18) during operation, on the front side (14) of which at least one discharge opening (16) for discharging clarified product (24) from the centrifuge drum (12) is formed, being provided with a weir edge (22) delimiting the discharge opening (16) towards the outside radially, and an energy recovery device (28; 42) for recovering energy from the clarified discharged product (24) is formed, being designed as a discharge pipe (44) through which the clarified discharged product (24) flows,
   characterised in that the energy recovery device (42) designed as the discharge pipe (44) through which the clarified discharged product (24) flows is arranged on the outside in front of the discharge opening (16) having the weir edge (22).
2. Solid-bowl screw centrifuge according to claim 1, wherein, with the discharge pipe (44), the clarified discharged product (24) is deflected opposite a respective direction of rotation (36) of the centrifuge drum (12).
3. Solid-bowl screw centrifuge according to claim 1 or 2, wherein the discharge pipe (44) has at least one section having an essentially straight flow path (50) which is set at an inclination by an angle (54) of 4° to 28°, preferably 8°, radially inwards to the tangential direction (52) at the discharge opening (16).
4. Solid-bowl screw centrifuge according to one of claims 1 to 3, wherein the discharge pipe (44) has at least one section with an essentially straight flow path (58) which is set at an inclination at an angle (60) between 45° and 85°, preferably between 55° and 65°, to the longitudinal axis (18) of the centrifuge drum (12).
5. Solid-bowl screw centrifuge according to one of claims 1 to 4, wherein the discharge pipe (44) has a discharge mouth (48) with a direction of flow (62) which is set at an inclination at an angle (64) between 70° and 90°, preferably between 77° and 83°, with respect to the longitudinal axis (18) of the centrifuge drum (12).
6. Solid-bowl screw centrifuge according to one of claims 1 to 5, wherein the discharge pipe (44) is designed with a flow cross section (56) of a constant size in the direction of flow of the clarified discharged product (24).
7. Solid-bowl screw centrifuge according to one of claims 1 to 5, wherein the discharge pipe (44) is designed with a diminishing, in particular conically tapering, flow cross section (56) in the direction of flow of the clarified discharged product (24).
8. Solid-bowl screw centrifuge according to one of claims 1 to 7, wherein the discharge pipe (44) is designed with a round, in particular circular or elliptical, flow cross section (56).
9. Solid-bowl screw centrifuge according to one of claims 1 to 7, wherein the discharge pipe (44) is designed with a rectangular, in particular square, flow cross section (56).
10. Solid-bowl screw centrifuge according to one of claims 1 to 9, wherein the discharge pipe (44) is designed with an adapted aerodynamic exterior wall shape (68) on its exterior wall (66) facing in the direction of rotation (36).

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