WO1997030791A1 - Decanteuse-centrifugeuse, boite d'engrenages et procede de fonctionnement - Google Patents

Decanteuse-centrifugeuse, boite d'engrenages et procede de fonctionnement Download PDF

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Publication number
WO1997030791A1
WO1997030791A1 PCT/US1997/002989 US9702989W WO9730791A1 WO 1997030791 A1 WO1997030791 A1 WO 1997030791A1 US 9702989 W US9702989 W US 9702989W WO 9730791 A1 WO9730791 A1 WO 9730791A1
Authority
WO
WIPO (PCT)
Prior art keywords
spline
bowl
flexible spline
angular velocity
flexible
Prior art date
Application number
PCT/US1997/002989
Other languages
English (en)
Inventor
Chi-Chung Hao
Original Assignee
Baker Hughes Incorporated
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
Priority claimed from US08/607,316 external-priority patent/US5912152A/en
Application filed by Baker Hughes Incorporated filed Critical Baker Hughes Incorporated
Priority to EP97914798A priority Critical patent/EP0883443A1/fr
Priority to AU21919/97A priority patent/AU2191997A/en
Publication of WO1997030791A1 publication Critical patent/WO1997030791A1/fr

Links

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
    • B04B1/2016—Driving control or mechanisms; Arrangement of transmission gearing
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H49/00—Other gearings
    • F16H49/001—Wave gearings, e.g. harmonic drive transmissions
    • 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
    • B04B1/2016—Driving control or mechanisms; Arrangement of transmission gearing
    • B04B2001/2025—Driving control or mechanisms; Arrangement of transmission gearing with drive comprising a planetary gear

Definitions

  • This invention relates to a decanter centrifuge.
  • this invention relates to a gear box for a decanter centrifuge.
  • This invention also relates to an associated method for operating a decanter centrifuge.
  • a decanter centrifuge generally includes an outer bowl, an inner hub carrying a worm conveyor, a feed arrangement for slurry to be processed, and discharge ports for cake solids and clarified liquid.
  • the bowl includes a cylindrical section and a conical beach section.
  • the bowl and the hub are rotated at high, slightly different angular speeds so that heavier solid particles of a slurry introduced into the bowl are forced by centrifugation into a layer along the inner surface thereof.
  • the worm conveyor and the bowl By differential rotation of the worm conveyor and the bowl, the sediment is pushed or scrolled to a cake discharge opening at the smaller, conical end of the bowl. Additional discharge openings are provided in the bowl, usually at an end opposite of the conical section for discharging a liquid phase separated from the solid particles in the centrifuge apparatus.
  • a so-called harmonic drive may be used to differentially drive the bowl and the conveyor of a decanter centrifuge.
  • a harmonic drive includes a circular spline, a flexible spline and a wave generator component.
  • the circular spline and the flexible spline are drivingly coupled to the bowl and the conveyor, respectively, while the strain inducing element (the wave generator) is held stationary.
  • the conveyor screw is driven in the same direction as the centrifugal rotor and the centrifuge bowl but at a speed greater than that of the rotor and the bowl by a relatively small increment which is dependent on the gear reduction ratio of the harmonic drive.
  • the speed differential increment decreases if the wave generator is driven in the same direction of rotation as the circular spline. Conversely, the speed differential increment increases if the wave generator is driven in the opposite direction to the rotation of the circular spline.
  • centrifuges operate with the conveyor rotating at a higher angular velocity than the bowl. In the other centrifuges, the opposite is true.
  • These centrifuges are conventionally driven with planetary gear boxes. With such a power transmission, at least two stages of speed reduction are needed in order to achieve the desired speed ratio between the bowl and the conveyor.
  • a problem arises since the size of a planetary gear box is proportional to the number of speed changing stages and since centrifuge gear boxes are commonly held by cantilevered supports. When the weight of an overhanging gear box attains a certain level, it has a natural vibration frequency which is close to the centrifuge operating speed. Thus, resonant destabilization occurs.
  • a decanter centrifuge assembly comprises, in accordance with the present invention, a bowl, a screw conveyor disposed inside the bowl for rotation at a speed different from an angular velocity of the bowl, and a harmonic drive unit including a circular spline drivingly connected to the conveyor.
  • the harmonic drive unit further includes a flexible spline drivingly connected to the bowl and a wave generator disposed in contact with the flexible spline for distorting the flexible spline and enabling a transmission of rotary power between the flexible spline and the circular spline so that the circular spline rotates at an angular velocity which incrementally differs from a rate of rotation of the flexible spline.
  • the flexible spline is rotatably coupled to the circular spline, for example, via intermeshing teeth on the two splines.
  • the harmonic drive has a lubrication system with a skimmer tube for paring lubricating fluid from a pool in an outer casing of the harmonic drive.
  • a shaft coupled to the wave generator has a channel communicating with the skimmer tube.
  • the lubricating system is further provided with a plurality of spray nozzles communicating with the channel in the shaft and juxtaposed to respective bearing surfaces of the harmonic drive unit for spraying lubricating fluid onto the respective bearing surfaces.
  • the shaft extends along a longitudinal axis of the harmonic drive unit, the channel being coaxial with the rotation axis of the circular spline and the flexible spline.
  • the present invention is also directed to a method for operating a decanter centrifuge assembly having a bowl and a screw conveyor disposed inside the bowl for rotation at a speed different from an angular velocity of the bowl.
  • the method comprises rotating the bowl of the centrifuge assembly at a first predetermined angular velocity, transmitting rotary power from the bowl to a flexible spline of a harmonic drive unit so that the flexible spline rotates about a rotation axis at the first predetermined angular velocity, rotating a circular spline of the harmonic drive unit about the rotation axis at a second predetermined angular velocity differing incrementally from the first predetermined angular velocity, and transmitting rotary force from the circular spline to the conveyor of the centrifuge assembly to rotate the conveyor at the second predetermined angular velocity.
  • the second predetermined velocity i.e., the rotation speed of the circular spline and the conveyor of the centrifuge assembly
  • the gear ratio between the flexible spline and the circular spline and in part by the rotary input to the wave generator.
  • the rotary input to the wave generator may be zero (fixed wave generator) or positive or negative (rotation in one direction or the other).
  • the method further comprises paring lubricating fluid from a pool in an outer casing of the harmonic drive unit, guiding the pared lubricating fluid through a channel in a shaft extending coaxially to the rotation axis, and ejecting the pared lubricating fluid onto bearing surfaces of the harmonic drive unit from a plurality of spray nozzles communicating with the channel.
  • the shaft is maintained stationary or driven in one direction or another to provide a desired speed differential between the centrifuge bowl and the conveyor.
  • Such an alternative method might comprise rotating a circular spline of a harmonic drive unit about a rotation axis at a first predetermined angular velocity, transmitting rotary force from the circular spline to the conveyor of the centrifuge assembly to rotate the conveyor at the first predetermined angular velocity, maintaining a wave generator component of the harmonic drive unit stationary during rotating c ⁇ e circular spline, rotating a flexible spline of the harmonic drive about the rota axis at a second predetermined angular velocity differing incrementally from the first predetermined angular velocity, and transmitting rotary force from the flexible spline to the bowl of the centrifuge assembly to rotate the bowl at the second predetermined angular velocity.
  • Providing a decanter centrifuge with a harmonic gear drive as described herein enables rotation of the bowl and the conveyor at higher velocities.
  • the smaller size of the drive relative to planetary gear boxes eliminates the vibration problem alluded to above.
  • the internal oil jet lubrication system in accordance with the present invention is more efficient than the oil sump of conventional planetary gear boxes in controlling heat production in the gear box bearings.
  • a harmonic drive unit enables a variation in the differential speeds of the bowl and the conveyor by replacing the splines with another pair of splines having a different gear ratio.
  • it is not necessary to provide a motor for driving the wave generator.
  • the replacement of splines to achieve a new speed differential thus provides economies not available with planetary gear boxes, where a motor and a variable frequency drive are necessary for backdriving the sun gear or pinion to change a rotation speed differential in the field.
  • a harmonic gear unit is less expensive than a planetary gear drive of the same level.
  • the drawing shows a gear box 10 for a decanter centrifuge assembly having a bowl 12 and a screw conveyor 14 disposed inside the bowl for rotation at a speed different from an angular velocity of the bowl.
  • Gear box 10 includes a rigid circular spline 16 drivingly connected to conveyor 14 via at least one bolt 18 and flange 20 of a drive shaft 24 of conveyor 14.
  • Gear box 10 further comprises a flexible spline 26 which is partially inserted inside circular spline 1 6.
  • Flexible spline 26 is provided with a ring of outwardly oriented teeth (not shown) which partially mesh with inwardly facing teeth (not shown) on circular spline 1 6.
  • Flexible spline 26 is bolted at 28 to a force-transmitting assembly 30 in turn drivingly or drivably connected to centrifuge bowl 1 2, as indicated at 32.
  • Gear box 10 additionally includes a wave generator 34 disposed inside flexible spline 26 in contact therewith for distorting the flexible spline and enabling a transmission of rotary power between the flexible spline and circular spline 16 so that the circular spline rotates at an angular velocity which incrementally differs from a rate of rotation of the flexible spline.
  • Wave generator 34 is an elliptical member with ball bearings 36 and operates to maintain diametrically opposed teeth of flexible spline 26 in contact with teeth on circular spline 16. Other teeth of splines 16 and 26 are spaced from one another, and thus out of a driving relationship.
  • Circular spline 1 6, flexible spline 26 and wave generator 34 are conventional components of a harmonic drive assembly 35 which has two drive outputs and two drive inputs.
  • bowl 1 2 is rotated by a rotary drive 56 at a first predetermined angular velocity.
  • Rotary force is transmitted from bowl 12 to flexible spline 26 via force-transmitting assembly 30 to rotate the flexible spline about a rotation axis 46.
  • wave generator 34 rotary power is transmitted from flexible spline 26 to circular spline 16 so that the circular spline rotates at a second predetermined angular velocity which differs incrementally from the angular velocity of bowl 12 and flexible spline 26.
  • a shaft 38 coupled to wave generator 34 may be fixed to hold the wave generator stationary.
  • gear box 10 is provided with a lubrication system which includes a skimmer tube 40 supported on shaft 38 via a bracket 42. Skimmer tube 40 pares lubricating fluid from a pool (not shown) in an outer casing 44 of gear box 10.
  • Shaft 38 is coaxially disposed about rotation axis 46 of circular spline 16 and flexible spline 26 and has a longitudinally extending channel 48 communicating with skimmer tube 40.
  • Channel 48 is also coaxial with axis 46.
  • a plurality of generally radially oriented ancillary channels 50 extend from longitudinal channel 48 to respective spray nozzles 52 disposed in juxtaposition to bearing surfaces 54. Spray nozzles 52 thus communicate with skimmer tube 40 via longitudinal channel 48.
  • lubricating fluid is pared or skimmed from a pool in outer casing 44 of gear box 10.
  • the pared lubricating fluid is guided through channels 48 and 50 and then ejected onto bearing surfaces 54 of harmonic drive 35.
  • Other radially extending fluid guide channels 58 are connected to spray nozzles 60 juxtaposed to bearings 62.
  • rotary power transmission may extend along a path from circular spline, over flexible spline 26 and force-transmitting assembly 30 to bowl 12. Accordingly, it is to be understood that the drawings and descriptions herein are proffered by way of example to facilitate comprehension of the invention and should not be construed to limit the scope thereof.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Centrifugal Separators (AREA)

Abstract

L'invention concerne un ensemble de décanteuse-centrifugeuse. Cette décanteuse centrifugeuse comprend un bol (12), une vis sans fin (14) placée à l'intérieur du bol en vue de sa rotation à une vitesse différente de la vitesse angulaire du bol, ainsi qu'un réducteur à planétaire (35) et une clavette à rainure circulaire (16) reliée à la vis, de manière à assurer son entraînement. Le réducteur à planétaire comprend, en outre, une clavette à rainure flexible (26) reliée au bol, en vue d'assurer un entraînement, et un générateur d'ondes (34) placé en contact avec la clavette à rainure flexible pour assurer la déformation de cette dernière et permettre son entraînement à une vitesse de rotation dont l'incrémentation diffère de la vitesse de rotation de la clavette circulaire. La clavette flexible présente des dents partiellement en prise avec celles de la clavette circulaire.
PCT/US1997/002989 1996-02-26 1997-02-21 Decanteuse-centrifugeuse, boite d'engrenages et procede de fonctionnement WO1997030791A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP97914798A EP0883443A1 (fr) 1996-02-26 1997-02-21 Decanteuse-centrifugeuse, boite d'engrenages et procede de fonctionnement
AU21919/97A AU2191997A (en) 1996-02-26 1997-02-21 Decanter centrifuge, gear box and operating method

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US08/607,316 1996-02-26
US08/607,316 US5912152A (en) 1995-02-28 1996-02-26 Process for preparing sphingomyelin and ceramide from erythrocyte as a starting material and a curing agent or cosmetic formulated with ceramide

Publications (1)

Publication Number Publication Date
WO1997030791A1 true WO1997030791A1 (fr) 1997-08-28

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ID=24431754

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1997/002989 WO1997030791A1 (fr) 1996-02-26 1997-02-21 Decanteuse-centrifugeuse, boite d'engrenages et procede de fonctionnement

Country Status (3)

Country Link
EP (1) EP0883443A1 (fr)
AU (1) AU2191997A (fr)
WO (1) WO1997030791A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999065610A1 (fr) 1998-06-15 1999-12-23 Alfa Laval Ab Centrifugeuse de decantation
US8808154B2 (en) * 2010-09-13 2014-08-19 Hiller Gmbh Drive apparatus in a scroll centrifuge having a gearbox with a housing nonrotatably connected to a drive shaft

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3419211A (en) * 1967-10-23 1968-12-31 Hitachi Shipbuilding Eng Co Centrifugal machine with differential drive
US3482770A (en) * 1968-04-10 1969-12-09 Laval Separator Co De Variable speed power transmission

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3419211A (en) * 1967-10-23 1968-12-31 Hitachi Shipbuilding Eng Co Centrifugal machine with differential drive
US3482770A (en) * 1968-04-10 1969-12-09 Laval Separator Co De Variable speed power transmission

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999065610A1 (fr) 1998-06-15 1999-12-23 Alfa Laval Ab Centrifugeuse de decantation
US6712751B2 (en) * 1998-06-15 2004-03-30 Alfa Laval Ab Centrifugal separator for separating solids from a liquid mixture centrally fed through a gear device
US6716153B2 (en) * 1998-06-15 2004-04-06 Alfa Laval Ab Centrifugal separator for separating solids from a liquid mixture centrally fed through a gear device
CN1298432C (zh) * 1998-06-15 2007-02-07 阿尔法拉瓦尔有限公司 一种沉降式离心机
US8808154B2 (en) * 2010-09-13 2014-08-19 Hiller Gmbh Drive apparatus in a scroll centrifuge having a gearbox with a housing nonrotatably connected to a drive shaft

Also Published As

Publication number Publication date
AU2191997A (en) 1997-09-10
EP0883443A1 (fr) 1998-12-16

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