WO1993022062A1 - Decanter centrifuge - Google Patents

Decanter centrifuge Download PDF

Info

Publication number
WO1993022062A1
WO1993022062A1 PCT/SE1993/000376 SE9300376W WO9322062A1 WO 1993022062 A1 WO1993022062 A1 WO 1993022062A1 SE 9300376 W SE9300376 W SE 9300376W WO 9322062 A1 WO9322062 A1 WO 9322062A1
Authority
WO
WIPO (PCT)
Prior art keywords
centrifuge
spiral screw
slurry
blade
angle
Prior art date
Application number
PCT/SE1993/000376
Other languages
French (fr)
Inventor
Lars Åke LARSON
Original Assignee
Noxon Ab
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Noxon Ab filed Critical Noxon Ab
Publication of WO1993022062A1 publication Critical patent/WO1993022062A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
    • B04B—CENTRIFUGES
    • B04B1/00—Centrifuges with rotary bowls provided with solid jackets for separating predominantly liquid mixtures with or without solid particles
    • B04B1/20—Centrifuges with rotary bowls provided with solid jackets for separating predominantly liquid mixtures with or without solid particles discharging solid particles from the bowl by a conveying screw coaxial with the bowl axis and rotating relatively to the bowl
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
    • B04B—CENTRIFUGES
    • B04B1/00—Centrifuges with rotary bowls provided with solid jackets for separating predominantly liquid mixtures with or without solid particles
    • B04B1/20—Centrifuges with rotary bowls provided with solid jackets for separating predominantly liquid mixtures with or without solid particles discharging solid particles from the bowl by a conveying screw coaxial with the bowl axis and rotating relatively to the bowl
    • B04B1/2008—Centrifuges with rotary bowls provided with solid jackets for separating predominantly liquid mixtures with or without solid particles discharging solid particles from the bowl by a conveying screw coaxial with the bowl axis and rotating relatively to the bowl with an abrasion-resistant conveyor or drum

Definitions

  • the present invention refers to a centrifuge for special slurry centrifuging, and consists of a rotating spiral screw for the feeding of slurry, and a rotating drum.
  • the objective of the present invention is to achieve a possibility for improved dry content, a higher slurry capacity, and thereby a higher degree of efficiency. This is achieved in that a greater sedimentation surface is obtained on the side of the spiral screw turned towards the centre shaft, at the same time as improved compression of the slurry is achieved by means of the angular setting of the spiral screw in the direction of transport, whereby dewatering increases in similarity with the available slurry volume.
  • Decanting centrifuges are used to a large extent for the dewatering of slurry from industrial processes and from sewage purification, where large volumes of slurry are obtained, e.g. after chemical and/or biological sedimentation of sewage water.
  • the slurry can contain large volumes of nutrients which can be supplied as fertilizer, or it can contain substances which are toxic and which must therefore be eliminated before deposition to the recipient takes place.
  • the maximum volume of water must be eliminated by centrifuging to reduce the costs of subsequent handling and drying phases.
  • the objective is therefore to achieve the highest possible dry contents. Dry contents of approx. 30-35% can normally be achieved with the standard decanting centrifuges on the market.
  • a decanting centrifuge consists of a drum with a cylindrical and a conical part, which are driven with a motor.
  • revolutions of the drum are normally approx. 1500-2800 rpm.
  • a spiral screw is arranged, which is also rotating, either by means of the drum motor or by means of a separate motor.
  • the blade of the spiral screw forms an angle which is less that 90 ' to the lengthwise axis of the centrifuge in the direction towards the front end of the centrifuge, which implies that the blade of the spiral screw is angled forward in the direction of transport, while the blade of the spiral screw forms 90 ' to the inner jacket surface of the drum.
  • Standard centrifuges on the market aiways have the blade of the spiral screw angled slightly forward in the direction of transport.
  • the slurry types in question are sewage water purification slurries, which are very heterogeneous in their composition, and industrial slurry such as from the cellulose industry, where the slurry is more homogeneous in its composition. In both cases the slurry most often contains material with a water content, such as cellulose fibres, metal hydroxide flocculates and the like.
  • the blade of the spiral screw displays an angle to the lengthwise axis of the centrifuge in the direction of transport which is greater than 90 ' , which implies that the screw sweeps backwards from the direction of transport to the inner jacket surface of the drum, which angle can also be varied and becomes less towards the front outlet end of the centrifuge.
  • the blade consists of yet another angle which to the inner jacket surface of the drum forms an angle of approx. 90 ° .
  • Fig. 1 shows a decanting centrifuge in cross-section with today's type of spiral screw blade with an angle which is less than 90 ° to the lengthwise axis of the centrifuge.
  • Fig. 2 shows a decanting centrifuge in cross-section with the backward sweeping spiral screw blade of the present invention with an angle greater than 90 ° to the lengthwise axis of the centrifuge, and also that this angle diminishes towards the front outlet end of the centrifuge.
  • Fig. 3 shows a partial enlargement of the blade of the spiral screw and its different angles, and how they diminish towards the front outlet end of the centrifuge, and also the rubber wearing surface of the blade.
  • Fig. 1 Shows a centrifuge with spiral screw blade of the conventional type.
  • Fig. 1 the drum 1 of the centrifuge is shown, which is cylindrical at one end and at the other is conically tapered towards a cylindrical outlet part.
  • the drum 1 is enclosed in its cylindrical part by an end-piece 2 which consists of a connection 3 to a bearing housing 4 and also of inlets for the reject water outlet pipe 5.
  • the connection 3 also consists of an inlet 6 for a pipe 7 for slurry intake.
  • a front end- piece 8 provided with an inlet for a bearing housing 9 outgoing shaft.
  • the slurry outlet 11 In the front cylindrical part 10 of the drum 1 there is the slurry outlet 11.
  • An internal rotor 12 is mounted on the outgoing shaft of the bearing housing 9, which consists of a mixer chamber 13 connected to the pipe 7.
  • the ingoing slurry is homogenized in the mixer chamber 13 and is supplied with additional slurry dewatered chemicals of the polyaluminium hydroxide sulphate type, polyacrylates or other polymers.
  • a spiral screw 14 is arranged on the outside of the rotor.
  • the blade of the spiral screw also displays through holes 15 for passage of the fiuid in the centrifuge.
  • a wearing surface is arranged on the blade of the spiral screw in the form of a wolfram carbide coating.
  • the blade 14 forms an angle ⁇ which is less than 90 ° to the lengthwise shaft of the centrifuge in the direction towards the front end of the centrifuge, which implies that the blade of the spiral screw is angled forwards in the direction of transport.
  • the centrifuge generally functions as a standard decanting centrifuge, whereby slurry with low dry content is introduced into the inlet pipe 7 and distributed out into the drum 1 from the mixer chamber 13, where the heavier parts of the slurry are sedimented towards the inner jacket surface of the drum on the basis of gravitation forces, and the fiuid, usually water, is forced and collected towards the centre of the drum 1.
  • the slurry is fed towards the front end.
  • Fig. 2 Shows a centrifuge with blade according to the present invention, otherwise as in Fig. 1.
  • the drum 1 and spiral screw 14 are shown.
  • the blade of the spiral screw displays a backward angle and forms an angle ⁇ 2 which is greater than 90 ° to the lengthwise axis of the centrifuge in the direction towards the front end of centrifuge, while the spiral blade forms an angle ⁇ z which is approx. 90 ° to the inner jacket surface of the drum.
  • the sedimenting surface of the blade increases and the slurry is then pressed down to the inner jacket surface of the drum and is compressed.
  • a wearing surface is arranged on the spiral screw blade, in the form of a rubber coating.
  • Fig. 3 Shows the blade of the spiral screw and its different angles in accordance with the present invention.
  • the blade of the spiral screw has, however, and angle of ⁇ x » 90 ' to the inner jacket surface along the entire centrifuge.

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  • Centrifugal Separators (AREA)

Abstract

The present invention refers to a decanting centrifuge for special slurry centrifuging, and consists of an inlet pipe (7), with mixer chamber (13), and drum (1) with spiral screw (14) for the feeding of slurry, and slurry and reject outlet (11, 6), whereby the angle β of the spiral screw is in the direction of transport greater than 90°, which implies that the blade of the spiral screw sweeps backwards and that the angle η of the blade to a plane at right angles to the lengthwise axis is approx. 20-45° in the first part of the centrifuge and that it is successively diminished to approx. 10° in the outlet end of the centrifuge, while the blade of the spiral screw has an angle of η to the inner jacket surface of the drum which is approx. 90°. The blade has a wearing surface of rubber coating.

Description

DESCRIPTION Technical field
The present invention refers to a centrifuge for special slurry centrifuging, and consists of a rotating spiral screw for the feeding of slurry, and a rotating drum.
The objective of the present invention is to achieve a possibility for improved dry content, a higher slurry capacity, and thereby a higher degree of efficiency. This is achieved in that a greater sedimentation surface is obtained on the side of the spiral screw turned towards the centre shaft, at the same time as improved compression of the slurry is achieved by means of the angular setting of the spiral screw in the direction of transport, whereby dewatering increases in similarity with the available slurry volume.
Background of the invention
Decanting centrifuges are used to a large extent for the dewatering of slurry from industrial processes and from sewage purification, where large volumes of slurry are obtained, e.g. after chemical and/or biological sedimentation of sewage water. The slurry can contain large volumes of nutrients which can be supplied as fertilizer, or it can contain substances which are toxic and which must therefore be eliminated before deposition to the recipient takes place. For final drying and handling of the slurry the maximum volume of water must be eliminated by centrifuging to reduce the costs of subsequent handling and drying phases.
The objective is therefore to achieve the highest possible dry contents. Dry contents of approx. 30-35% can normally be achieved with the standard decanting centrifuges on the market.
A decanting centrifuge consists of a drum with a cylindrical and a conical part, which are driven with a motor.
The revolutions of the drum are normally approx. 1500-2800 rpm. Inside the drum a spiral screw is arranged, which is also rotating, either by means of the drum motor or by means of a separate motor.
The blade of the spiral screw forms an angle which is less that 90' to the lengthwise axis of the centrifuge in the direction towards the front end of the centrifuge, which implies that the blade of the spiral screw is angled forward in the direction of transport, while the blade of the spiral screw forms 90' to the inner jacket surface of the drum. Standard centrifuges on the market aiways have the blade of the spiral screw angled slightly forward in the direction of transport.
When the drum is rotated a slurry containing a slurry segment is thrown out towards the periphery of the drum, and its water segment is forced out from the slurry and towards the centre of the drum. The water is eliminated by means of reject outlet ducts and then out in a reject outlet. By means of rotating the drum and the spiral screw with different revolutions a transport effect 50 is obtained so that the slurry is fed towards the conical end of the drum, where there is a slurry outlet. If the drum and spiral screw have the same revolutions there will be no feed. The spiral screw can be individually fashioned depending on which type of slurry is to be handled.
The slurry types in question are sewage water purification slurries, which are very heterogeneous in their composition, and industrial slurry such as from the cellulose industry, where the slurry is more homogeneous in its composition. In both cases the slurry most often contains material with a water content, such as cellulose fibres, metal hydroxide flocculates and the like.
The requirement, however, is always to achieve the highest final dry content as possible, a clean reject water, and the continuity of operations.
Description of the present invention
Surprisingly it has now proved possible to increase the dry content by means of the present invention, which is characterized by, that the blade of the spiral screw displays an angle to the lengthwise axis of the centrifuge in the direction of transport which is greater than 90', which implies that the screw sweeps backwards from the direction of transport to the inner jacket surface of the drum, which angle can also be varied and becomes less towards the front outlet end of the centrifuge. In addition the blade consists of yet another angle which to the inner jacket surface of the drum forms an angle of approx. 90°.
Further characteristics are indicated in the patent claims.
By means of the present invention a greater sedimentation surface is achieved along the blade. And also on the basis of the angle of the spiral screw in the direction of transport, a greater compression of the slurry is achieved, and thereby improved dewatering. Which gives a greater dry content in the outgoing slurry, a higher slurry capacity, and thereby a higher degree of efficiency. The invention will in the following be described in more detail with reference to the enclosed drawing.
Fig. 1 shows a decanting centrifuge in cross-section with today's type of spiral screw blade with an angle which is less than 90° to the lengthwise axis of the centrifuge.
Fig. 2 shows a decanting centrifuge in cross-section with the backward sweeping spiral screw blade of the present invention with an angle greater than 90° to the lengthwise axis of the centrifuge, and also that this angle diminishes towards the front outlet end of the centrifuge.
Fig. 3 shows a partial enlargement of the blade of the spiral screw and its different angles, and how they diminish towards the front outlet end of the centrifuge, and also the rubber wearing surface of the blade. Fig. 1 Shows a centrifuge with spiral screw blade of the conventional type.
In Fig. 1 the drum 1 of the centrifuge is shown, which is cylindrical at one end and at the other is conically tapered towards a cylindrical outlet part. The drum 1 is enclosed in its cylindrical part by an end-piece 2 which consists of a connection 3 to a bearing housing 4 and also of inlets for the reject water outlet pipe 5. The connection 3 also consists of an inlet 6 for a pipe 7 for slurry intake. At its front end the drum 1 is enclosed by a front end- piece 8 provided with an inlet for a bearing housing 9 outgoing shaft. In the front cylindrical part 10 of the drum 1 there is the slurry outlet 11.
An internal rotor 12 is mounted on the outgoing shaft of the bearing housing 9, which consists of a mixer chamber 13 connected to the pipe 7.
The ingoing slurry is homogenized in the mixer chamber 13 and is supplied with additional slurry dewatered chemicals of the polyaluminium hydroxide sulphate type, polyacrylates or other polymers.
A spiral screw 14 is arranged on the outside of the rotor. The blade of the spiral screw also displays through holes 15 for passage of the fiuid in the centrifuge. A wearing surface is arranged on the blade of the spiral screw in the form of a wolfram carbide coating. The blade 14 forms an angle α which is less than 90° to the lengthwise shaft of the centrifuge in the direction towards the front end of the centrifuge, which implies that the blade of the spiral screw is angled forwards in the direction of transport.
The centrifuge generally functions as a standard decanting centrifuge, whereby slurry with low dry content is introduced into the inlet pipe 7 and distributed out into the drum 1 from the mixer chamber 13, where the heavier parts of the slurry are sedimented towards the inner jacket surface of the drum on the basis of gravitation forces, and the fiuid, usually water, is forced and collected towards the centre of the drum 1. By means of the differential revolutions between the drum and spiral screw the slurry is fed towards the front end.
Fig. 2 Shows a centrifuge with blade according to the present invention, otherwise as in Fig. 1. In Fig. 2 the drum 1 and spiral screw 14 are shown. The blade of the spiral screw displays a backward angle and forms an angle β2 which is greater than 90° to the lengthwise axis of the centrifuge in the direction towards the front end of centrifuge, while the spiral blade forms an angle δz which is approx. 90° to the inner jacket surface of the drum. The sedimenting surface of the blade increases and the slurry is then pressed down to the inner jacket surface of the drum and is compressed.
In addition a wearing surface is arranged on the spiral screw blade, in the form of a rubber coating.
Fig. 3 Shows the blade of the spiral screw and its different angles in accordance with the present invention.
In Fig. 3 the angle βx > 90' and the same blade angle γx = 20 - 45' in the first part of the centrifuge are shown.
These angles are then successively diminished towards the outlet end of the centrifuge to the angle βx - 90' and the angle γx - 10°.
The blade of the spiral screw has, however, and angle of δx » 90' to the inner jacket surface along the entire centrifuge.

Claims

PATENT CLAIMS
1. Decanting centrifuge for special slurry centrifuging, and consists of an inlet pipe 7, with mixer chamber 14, and drum 1 with spiral screw 14 for the feeding of slurry, and slurry and reject outlet 11, 6, characterized by, that the blade of the spiral screw 14 displays an angle β towards the lengthwise axis of the centrifuge in the direction of transport which is greater than 90°, whereby the blade of the spiral screw in the first part of the centrifuge, displays an angle γ backwards from the direction of transport, which is 20- 45° towards a plane arranged at right angles to the lengthwise axis, and that the blade of the spiral screw 14 to the inner jacket surface of the drum displays an angle of approx. 90°.
2. Decanting centrifuge as per claim 2 characterized by, the named angle γ in the front end of the centrifuge successively diminishing to approx. 10°.
3. Decanting centrifuge as per claim 1 - 2 characterized by, that the spiral screw 14 displays a wearing surface on rubber.
PCT/SE1993/000376 1992-04-29 1993-04-28 Decanter centrifuge WO1993022062A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9201347-3 1992-04-29
SE9201347A SE501213E (en) 1992-04-29 1992-04-29 Centrifuge

Publications (1)

Publication Number Publication Date
WO1993022062A1 true WO1993022062A1 (en) 1993-11-11

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE1993/000376 WO1993022062A1 (en) 1992-04-29 1993-04-28 Decanter centrifuge

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AU (1) AU4275493A (en)
SE (1) SE501213E (en)
WO (1) WO1993022062A1 (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0600628A2 (en) * 1992-12-01 1994-06-08 THOMAS BROADBENT & SONS LIMITED Decanter-type centrifuges
WO1996014935A1 (en) * 1994-11-09 1996-05-23 Incentra Decanter centrifuge
EP0787532A1 (en) * 1996-01-31 1997-08-06 Baker Hughes Incorporated Decanter centrifuge and associated method for producing cake with reduced moisture content and high throughput
CN107930870A (en) * 2017-12-18 2018-04-20 江苏鑫华能环保工程股份有限公司 Whirlwind cyclone and cyclone with centrifugal guide vane

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102500473A (en) * 2011-11-25 2012-06-20 成都西部石油装备有限公司 Centrifugal machine for treating drilling fluid

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2734681A (en) * 1941-08-14 1956-02-14 schmiedel
US2743864A (en) * 1954-03-05 1956-05-01 Bird Machine Co Centrifuge with inclined conveyor blade and vanes for rapid collection of fine particles from suspensions
US3275230A (en) * 1963-07-11 1966-09-27 Flottweg Motorenwerk Dr Georg Bowl centrifuge
US4298161A (en) * 1978-10-23 1981-11-03 Wilkinson Rubber Linatex Limited Centrifuge
EP0076476A2 (en) * 1981-10-02 1983-04-13 Werner Dr. Stahl Decanter centrifuge
US4449967A (en) * 1982-06-17 1984-05-22 Pennwalt Corporation Conveyor flight configuration

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2734681A (en) * 1941-08-14 1956-02-14 schmiedel
US2743864A (en) * 1954-03-05 1956-05-01 Bird Machine Co Centrifuge with inclined conveyor blade and vanes for rapid collection of fine particles from suspensions
US3275230A (en) * 1963-07-11 1966-09-27 Flottweg Motorenwerk Dr Georg Bowl centrifuge
US4298161A (en) * 1978-10-23 1981-11-03 Wilkinson Rubber Linatex Limited Centrifuge
EP0076476A2 (en) * 1981-10-02 1983-04-13 Werner Dr. Stahl Decanter centrifuge
US4449967A (en) * 1982-06-17 1984-05-22 Pennwalt Corporation Conveyor flight configuration

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0600628A2 (en) * 1992-12-01 1994-06-08 THOMAS BROADBENT & SONS LIMITED Decanter-type centrifuges
EP0600628A3 (en) * 1992-12-01 1994-12-28 Broadbent & Sons Ltd Thomas Decanter-type centrifuges.
US5584791A (en) * 1992-12-01 1996-12-17 Thomas Broadbent & Sons Ltd. Decanting centrifuges with improved compression
WO1996014935A1 (en) * 1994-11-09 1996-05-23 Incentra Decanter centrifuge
US6123656A (en) * 1994-11-09 2000-09-26 Incentra Decanter centrifuge
US5840007A (en) * 1995-06-06 1998-11-24 Baker Hughes Incorporated Decanter centrifuge for producing cake with reduced moisture content and high throughput
US6110096A (en) * 1995-06-06 2000-08-29 Baker Hughes Incorporated Decanter centrifuge for producing cake with reduced moisture content and high throughput
EP0787532A1 (en) * 1996-01-31 1997-08-06 Baker Hughes Incorporated Decanter centrifuge and associated method for producing cake with reduced moisture content and high throughput
CN107930870A (en) * 2017-12-18 2018-04-20 江苏鑫华能环保工程股份有限公司 Whirlwind cyclone and cyclone with centrifugal guide vane
CN107930870B (en) * 2017-12-18 2024-04-16 江苏鑫华能环保工程股份有限公司 Cyclone with centrifugal guide vane and cyclone

Also Published As

Publication number Publication date
SE9201347L (en) 1993-11-15
AU4275493A (en) 1993-11-29
SE501213E (en) 1999-10-11
SE501213C2 (en) 1994-12-12
SE9201347D0 (en) 1992-04-29

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