GB2064997A - Screen bowl decanter centrifuges - Google Patents
Screen bowl decanter centrifuges Download PDFInfo
- Publication number
- GB2064997A GB2064997A GB7943277A GB7943277A GB2064997A GB 2064997 A GB2064997 A GB 2064997A GB 7943277 A GB7943277 A GB 7943277A GB 7943277 A GB7943277 A GB 7943277A GB 2064997 A GB2064997 A GB 2064997A
- Authority
- GB
- United Kingdom
- Prior art keywords
- bowl
- solids
- screen
- centrifuge
- frusto
- Prior art date
- Legal status (The legal status 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 status listed.)
- Withdrawn
Links
- 239000007787 solid Substances 0.000 claims abstract description 29
- 239000007788 liquid Substances 0.000 claims abstract description 10
- 239000000463 material Substances 0.000 claims description 2
- 230000008901 benefit Effects 0.000 description 3
- 239000003245 coal Substances 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 238000001035 drying Methods 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
- 238000004062 sedimentation Methods 0.000 description 1
- 125000006850 spacer group Chemical group 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
- B04B—CENTRIFUGES
- B04B3/00—Centrifuges with rotary bowls in which solid particles or bodies become separated by centrifugal force and simultaneous sifting or filtering
- B04B3/04—Centrifuges with rotary bowls in which solid particles or bodies become separated by centrifugal force and simultaneous sifting or filtering 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
Landscapes
- Centrifugal Separators (AREA)
Abstract
A screen bowl decanter centrifuge has a horizontally rotatable bowl (10) within which a scroll conveyor (42) is coaxially journalled for rotation at a slightly different speed for conveying solids towards a solids discharge end of the bowl. The other end of the bowl has a liquids outlet (24). The bowl (10) has an imperforate frusto-conical portion (18) which converges towards the solids discharge end and a perforate screen portion (20) downstream of the imperforate frusto-conical portion (18) in the direction of solids discharge for assisting dewatering of the solids. In order to improve dewatering and to reduce the conveying torque requirements on the conveyor (42), the perforate screen portion (20) is of divergent frusto-conical configuration, considered in the direction of solids discharge. <IMAGE>
Description
SPECIFICATION
Improvements in screen bowl decanter centrifuges
The present invention is concerned with screen bowl decanter centrifuges.
Conventional screen bowl decanter centrifuges comprise a horizontally rotatable bowl within which a scroll conveyor is coaxially journalled for rotation at a slightly different speed for conveying solids, deposited by centrifugal action on the internal surface of the bowl, towards a solids discharge end of the bowl, the other end of the bowl having a liquids outlet. The majority of the bowl is usually cylindrical but at the solids discharge end there is a frusto-conical portion which converges towards the discharge end and provides a sloping ramp up which solids are drawn by the conveyor out of the liquid pool contained in the bowl. The ramp thus provides a drying area for such solids conveyed out of the liquid pool.In known screen bowl centrifuges, the frusto-conical ramp section is supplemented by a coaxially disposed, cylindrical screen section located downstream of the ramp in the conveying direction.
Thus, sedimentation is carried out in the cylindrical/ conical section of the bowl but then the solids conveyed out of the liquid pool are conveyed over the screen section thereby improving the dewatering action.
The latter machine configuration is particularly useful with materials which drain easily. Consequently they find frequent application in the dewatering of coal and other minerals. In such applications, however, it is highly desirable to use very large machines in view of the quantity of product to be treated. A severe limitation on the design and manufacture of very large centrifugal machines is, however, the torque requirement, i.e. the torque required to drive the conveyor. A number of factors contribute to this torque requirement but the frictional effect of the product being conveyed over the screen provides a major component.If a reduction in the conveying torque could be attained, this would have the dual benefit of removing some of the design limitations affecting the gearbox associated with the conveyor drive, thus reducing its size and cost, and of giving a very useful reduction in the total power consumption.
It is thus a primary objective of the present invention to provide a screen bowl decanter centrifuge in which the torque requirement on the scroll conveyor is reduced.
In accordance with the present invention, this is achieved by constructing the screen section of the bowl so that it is of divergent conical form, considered in the direction towards the solids outlet end.
The advantage of this arrangement is that the provision of a divergent screen section significantly reduces the conveying torque requirements since the centrifugal forces on the solids assist their passage along the screen section. However, the angle of the divergent section should be less than the frictional angle of the solids product with which the centrifuge is being used so as to ensure that the solids do not simply flow outwardly over the divergent surfaces with negligible travei time. In the case of coal, for example, the friction angle is typically 22".
In general, an angle of about 15may be most appropriate.
An additional advantage is that the larger diameter of the screen section encountered by the solids as they are conveyed towards the outlet end of the bowl provides a higher G factor and thus improves dewatering. At the same time, the diverging nature of the screen section means that, as the solids move towards the discharge and, an increasingly large screen area becomes available so that there is consequently a progressive reduction in the height of the solids pile above the screen. Naturaily, this further improves the drainage facility.
The invention is described further hereinafter by way of example, with reference to the accompanying drawing which is a diagrammatic longitudinal section through one embodiment of a screen bowl decanter centrifuge in accordance with the invention.
The illustrated centrifuge includes a bowl 10 which isjournalled in bearings 12,14 for rotation about a horizontal axis. The bowl includes a cylindrical portion 16, an imperforatefrusto-conical portion 18 and a frusto conical screen portion 20. The righthand end of the cylindrical bowl portion (as viewed in the drawing) is closed by a radial wall 22 containing one or more apertures 24 serving to define a weir for determining the depth of an annular liquids pool which is established in the bowl. The level of this pool is indicated in the drawing by a chain line 26 and it will be noted that this encounters the conical section 18 about two-thirds along its length.
The screen portion 20 is located immediately downstream of the conical portion 18 and, as shown in the enlargement contained within the circle, includes a thin screen member 28 which contains fine perforations or apertures 30 and which is supported by a frusto-conical backing member 32 having much larger apertures 34 permitting unrestricted passage of liquids passing through the perforations 30. The left-hand end of the screen section 20 is closed by a further transverse wall 36.
Coaxially journalled within the bowl 10 in bearings 38,40 is a scroll conveyor 42 comprising a helical flight 44 carried by a shaft 46. The shaft 46 is hollow in the regions adjacent to the bowl sections 16 and 18 whereby to define an inlet chamber 48 into which a slurry to be processed is introduced by way of a stationary inlet pipe 50. The chamber 48 has one or more outlets 52 for introducing the slurry into the bowl in the region of the imperforate frusto-conical portion 18.
Obviously, it is impossible to assemble a machine of this type using a solid conveyor. Thus, the conveyor portion 44a in the region of the divergent screen section 20 is formed on a separate sleeve 54 which is slipped over a reduced diameter portion of the main conveyor hub and keyed to it by means 56 capable of imparting the necessary drive. Adjustable spacers may be provided between the sleeve 54 and the main hub 46 in order to permit adjustment and control of the gap between the screen 20 and the conveyor portion 44a.
Claims (4)
1. A screenbowl decanter centrifuge of the type comprising a horizontally rotatable bowl within which a scroll conveyor is coaxiallyjournalled for rotation at a slightly different speed for conveying solids, deposited by centrifugal action on the internal surface of the bowl, towards a solids discharge end of the bowl, the other end of the bowl having a liquids outlet, the bowl having an imperforate frustoconical portion, which converges towards the solids discharge end and provides a sloping ramp up which solids are drawn by the conveyor out of the liquid pool contained in the bowl, and a perforate screen portion downstream of the imperforate frustoconical portion in the direction of solids discharge for assisting dewatering of the solids, wherein the perforate screen portion is of divergent frustoconical configuration, considered in the direction of solids discharge.
2. A centrifuge as claimed in claim 1, in which for a given solids material with which the centrifuge is to operate, the angle of said divergent frusto-conical screen portion is less than the friction angle of such solids.
3. A centrifuge as claimed in claim 1 or 2, in which the perforate frusto-conical screen portion comprises a thin screen member containing relativeliy fine apertures supported by an outer, frustoconical backing member having much larger apertures permitting unrestricted passage of liquid passing through thefinerapertures of the screen member.
4. A screen bowl decanter centrifuge substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7943277A GB2064997A (en) | 1979-12-15 | 1979-12-15 | Screen bowl decanter centrifuges |
| ZA00807719A ZA807719B (en) | 1979-12-15 | 1980-12-09 | Screen bowl decanter centrifuges |
| AU65250/80A AU6525080A (en) | 1979-12-15 | 1980-12-10 | Screen bowl decanter centrifuges |
| DE19803046946 DE3046946A1 (en) | 1979-12-15 | 1980-12-12 | DECANTER CENTRIFUGE |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7943277A GB2064997A (en) | 1979-12-15 | 1979-12-15 | Screen bowl decanter centrifuges |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2064997A true GB2064997A (en) | 1981-06-24 |
Family
ID=10509877
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB7943277A Withdrawn GB2064997A (en) | 1979-12-15 | 1979-12-15 | Screen bowl decanter centrifuges |
Country Status (4)
| Country | Link |
|---|---|
| AU (1) | AU6525080A (en) |
| DE (1) | DE3046946A1 (en) |
| GB (1) | GB2064997A (en) |
| ZA (1) | ZA807719B (en) |
Cited By (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2548925A1 (en) * | 1983-07-11 | 1985-01-18 | Kloeckner Humboldt Deutz Ag | FULL-SIDED SCREW CENTRIFUGE FOR THE SEPARATION OF A SOLID-LIQUID MIXTURE |
| US4826608A (en) * | 1986-07-19 | 1989-05-02 | Klockner-Humboldt-Deutz Aktiengesellschaft | Worm centrifuge |
| EP0381491A3 (en) * | 1989-02-01 | 1991-05-15 | Baker Hughes Incorporated | Screen bowl centrifuge |
| EP0553793A3 (en) * | 1992-01-31 | 1993-09-01 | Kloeckner-Humboldt-Deutz Aktiengesellschaft | Apparatus and method for the wet-mechanical treatment of solids |
| WO1994001219A1 (en) * | 1992-07-06 | 1994-01-20 | Klöckner-Humboldt-Deutz Aktiengesellschaft | Process and device of gravity concentration of solid materials |
| US5378364A (en) * | 1992-09-14 | 1995-01-03 | Baker Hughes Incorporated | Conical screen basket centrifuge |
| US5584791A (en) * | 1992-12-01 | 1996-12-17 | Thomas Broadbent & Sons Ltd. | Decanting centrifuges with improved compression |
| 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 |
| US5958235A (en) * | 1997-08-22 | 1999-09-28 | Baker Hughes Incorporated | Continuous-feed filtering- or screening-type centrifuge with reslurrying and dewatering |
| WO1999062639A1 (en) * | 1998-06-03 | 1999-12-09 | Baker Hughes Incorporated | Cantilever centrifuge with outwardly tapered second conical bowl section |
| US6077210A (en) * | 1991-12-31 | 2000-06-20 | Baker Hughes Incorporated | Feed accelerator system including accelerating vane apparatus |
| US7153255B2 (en) * | 2002-03-20 | 2006-12-26 | Hiller Gmbh | Screw centrifuge for the wet mechanical separation of solids |
| WO2009120834A1 (en) * | 2008-03-28 | 2009-10-01 | Andritz Separation, Inc. | Screen bowl centrifuge |
| WO2019229444A1 (en) | 2018-05-31 | 2019-12-05 | Thomas Broadbent & Sons, Limited | A screen bowl decanter centrifuge |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3150975C2 (en) * | 1981-12-23 | 1985-05-09 | Krauss-Maffei AG, 8000 München | Tumbling centrifuge |
-
1979
- 1979-12-15 GB GB7943277A patent/GB2064997A/en not_active Withdrawn
-
1980
- 1980-12-09 ZA ZA00807719A patent/ZA807719B/en unknown
- 1980-12-10 AU AU65250/80A patent/AU6525080A/en not_active Abandoned
- 1980-12-12 DE DE19803046946 patent/DE3046946A1/en not_active Withdrawn
Cited By (21)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2145944A (en) * | 1983-07-11 | 1985-04-11 | Kloeckner Humboldt Deutz Ag | A screw-type centrifuge for separating solid-liquid mixtures |
| FR2548925A1 (en) * | 1983-07-11 | 1985-01-18 | Kloeckner Humboldt Deutz Ag | FULL-SIDED SCREW CENTRIFUGE FOR THE SEPARATION OF A SOLID-LIQUID MIXTURE |
| US4826608A (en) * | 1986-07-19 | 1989-05-02 | Klockner-Humboldt-Deutz Aktiengesellschaft | Worm centrifuge |
| EP0381491A3 (en) * | 1989-02-01 | 1991-05-15 | Baker Hughes Incorporated | Screen bowl centrifuge |
| US6077210A (en) * | 1991-12-31 | 2000-06-20 | Baker Hughes Incorporated | Feed accelerator system including accelerating vane apparatus |
| EP0553793A3 (en) * | 1992-01-31 | 1993-09-01 | Kloeckner-Humboldt-Deutz Aktiengesellschaft | Apparatus and method for the wet-mechanical treatment of solids |
| WO1994001219A1 (en) * | 1992-07-06 | 1994-01-20 | Klöckner-Humboldt-Deutz Aktiengesellschaft | Process and device of gravity concentration of solid materials |
| US5378364A (en) * | 1992-09-14 | 1995-01-03 | Baker Hughes Incorporated | Conical screen basket centrifuge |
| US5584791A (en) * | 1992-12-01 | 1996-12-17 | Thomas Broadbent & Sons Ltd. | Decanting centrifuges with improved compression |
| 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 |
| US5958235A (en) * | 1997-08-22 | 1999-09-28 | Baker Hughes Incorporated | Continuous-feed filtering- or screening-type centrifuge with reslurrying and dewatering |
| WO1999062639A1 (en) * | 1998-06-03 | 1999-12-09 | Baker Hughes Incorporated | Cantilever centrifuge with outwardly tapered second conical bowl section |
| US6241901B1 (en) | 1998-06-03 | 2001-06-05 | Baker Hughes Incorporated | Centrifuge with thickened-feed accelerator between inner and outer bowl sections |
| US7153255B2 (en) * | 2002-03-20 | 2006-12-26 | Hiller Gmbh | Screw centrifuge for the wet mechanical separation of solids |
| WO2009120834A1 (en) * | 2008-03-28 | 2009-10-01 | Andritz Separation, Inc. | Screen bowl centrifuge |
| CN101980789B (en) * | 2008-03-28 | 2012-06-20 | 安德里兹分离有限公司 | Sedimentation filter centrifuge |
| US8246842B2 (en) | 2008-03-28 | 2012-08-21 | Andritz Separation, Inc. | Screen bowl centrifuge |
| RU2482922C2 (en) * | 2008-03-28 | 2013-05-27 | Андритц Сепарейшн, Инк. | Centrifuge with screen bowl |
| WO2019229444A1 (en) | 2018-05-31 | 2019-12-05 | Thomas Broadbent & Sons, Limited | A screen bowl decanter centrifuge |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3046946A1 (en) | 1981-09-24 |
| ZA807719B (en) | 1981-12-30 |
| AU6525080A (en) | 1981-06-25 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |