US3620442A - Centrifuge slurry supply - Google Patents

Centrifuge slurry supply Download PDF

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Publication number
US3620442A
US3620442A US807750A US3620442DA US3620442A US 3620442 A US3620442 A US 3620442A US 807750 A US807750 A US 807750A US 3620442D A US3620442D A US 3620442DA US 3620442 A US3620442 A US 3620442A
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United States
Prior art keywords
shaft
openings
slurry
orifice
bowl
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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.)
Expired - Lifetime
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US807750A
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English (en)
Inventor
John J Halloran Jr
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Combustion Engineering Inc
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Combustion Engineering Inc
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Filing date
Publication date
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    • 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
    • B04B2001/2033—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 feed accelerator inside the conveying screw

Definitions

  • the shaft has rectangular openings in the area of the slurry feed with rectangular orifice plates of hardened material fastened inside the shaft.
  • the orifice plate is sealed to the shaft so that it forms a lip. retaining a pool of slurry within the shaft.
  • the orifice plate is also smaller than the opening and overlaps the trailing edge of the opening.
  • a TT'OENE Y CENTRIFUGE SLURRY SUPPLY BACKGROUND OF THE INVENTION This invention relates to centrifuges for separating solids from liquids and in particular to an arrangement for feeding the slurry into the rotating bowl of a centrifuge.
  • the bowl rotates at high speed to develop the centrifugal force which separates the liquid and solids.
  • a conveyor is rotated also at high speed, but at a speed varying slightly from that of the bowl.
  • a helix on the outside of the conveyor operates to urge the solids towards the solids discharge end due to the differential rotation between the conveyor and the bowl.
  • a stationary slurry feed pipe is centrally located to introduce the material into the centrifuge. The slurry must, therefore, pas through the conveyor shaft before it gets to the bowl.
  • the conveyor is generally fonned of a large hollow tubular shaft.
  • One method of allowing the slurry to pass therethrough has been to use simple round openings in the shaft. This results in a concentrated stream of slurry passing into the bowl.
  • a layer of the solid material forms on the bowl surface underlying the slurry at any given time.
  • This layer of solids has been found effective in improving the balance of the centrifuge and in promoting the separation of the very fine particles. It is believed that this buildup inherently reduces the clearance and therefore leakage between the rotating conveyor helix and the rotating bowl.
  • the stream of slurry from these round openings has been found to create such an impact in the bowl that it disturbs this underlying layer of solids so that separation in a centrifuge is reduced with excessive solids being carried into the liquid effluent.
  • Tubular noules either extending radially outward from the shaft or generally tangent to the shaft have been added in some designs to reduce this turbulence
  • These nozzles operate to increase the angular speed of the discharge through shaft to a lower relative velocity when the stream strikes the pool in the bowl. This has been effective to increase stability of the centrifuge and improve its separating performance.
  • the opening through the conveyor shaft through which the slurry flows is rectangular in shape, or at least has the trailing edge generally linear and parallel to shaft axis.
  • a similarly shaped orifice plate of hardened material may be fastened inside the shaft and sealed around the edges, thus forming a darn around the openings. The trailing edge of the orifice plate overlaps the opening through the shaft.
  • the use of the rectangular orifice plate and the straight trailing edge spreads the flow of slurry evenly across the orifice opening. This results in a wider, less concentrated stream of slurry into the bowl which causes only surface disturbance of the material in the bowl avoiding the penetration that occurs when a round opening is used.
  • the straight edge also avoids the concentration of solids in one location so that wear is spread uniformly across the orifice plate. While in a tubular outlet under transverse acceleration, a rotational flow through the cross section of the pipe is set up increasing wear. This does not occur with a rectangular opening.
  • the orifice plate is simply mounted on the inside of the shaft with the centrifugal force of rotation helping to keep the orifice plate against the shaft.
  • the trailing edge of the orifice can overlap the orifice opening at the trailing edge of the opening. In this manner most, if not all, of the wear occurs on the orifice plate which is made of a hardened material with minimal wear occurring in the shah.
  • the orifice plate can be sealed around the opening so that it forms a dam within the shaft. This results in a pool of slurry building up inside the shaft which rotates at the speed of the shaft. The slurry being added meets this rotating pool rather than the shaft itself thereby avoiding excessive erosion of the shaft material.
  • the rotating pool serves to accelerate the slurry being fed toward the speed of the shaft thereby achieving some angular velocity before the discharge through the orifice into the bowl.
  • FIG. 1 is a general arrangement of a centrifuge
  • FIG. 2 is a detailed sectional side elevation in the area of the openings through the conveyor shaft
  • FIG. 3 is a side sectional view of the orifice plate opening through the shaft.
  • FIG. 4 is a plan view of FIG. 3.
  • This longitudinal movement of the solids is accomplished by use of rotating conveyor 22. While the bowl 15 is rotating at about 1,000 rpm, the conveyor shaft is rotating at only L0 1 0 rpm. This differential rotation of IO revolutions per minute operates to urge the solid coal particles towards the discharge end by means of the helical flights 23. These helical flights are mounted on a generally impervious tubular frame 24 of the conveyor.
  • Discharge from the slurry feed pipe 13 passes to the rotating bowl through the rectangular openings 27 in the shaft.
  • Four of these openings are located around the periphery of the shaft at different longitudinal positions. Each of the openings occurs at a location between the locations of the flights. Each opening is 4 1% inches in the longitudinal direction and 3 inches wide with at least the trailing edge being parallel to the shaft axis. Since the rotating shaft must be stiff in order to maintain the clearance between the flights and the bowl and must also be strong due to the high forces encountered, the material removed from the shafl should be minimized. The length of the openings, therefore, is relatively large with the 4 inch openings amounting to over two-thirds of the distance available between flights.
  • the slurry flows out along the trailing edge of the opening of this rotating shaft. Therefore, a 4 inch wide stream flows from each opening into the bowl. By spreading this stream out into 4 inch wide streams, a relatively thin stream is formed at each location so that impact in the bowl is minimized.
  • an orifice plate 28 is mounted inside each opening in the shafi.
  • This plate may be of alumina or any other wear resistant material.
  • the opening in the orifice plate is also 4 inches long but only 2 Vi inches wide with the trailing edge 29 of the plate overlapping the opening in the shaft by V2 inch. Referring to FIG. 3 since the rotating bowl 24 is moving at high speed to the leh, the relative direction of discharge through the openings would be upwardly and to the right. The overlap of this orifice plate prevents excessive wear from occurring on the relatively soft material on the shaft so that essentially all wear occurs on the orifice plate itself.
  • the orifice plate is maintained in place by the use of holddown plates 30 which overlap the orifice plate 30 and are bolted to the shaft with bolts 32. These bolts pass from the outside of the shaft so that no wear occurs on the head of the bolts. Centrifugal force tends to maintain the orifice plate in position while the centrifuge is in operation.
  • a rubber gasket 33 is placed between the orifice plate and the shaft. This soft gasket not only reduces breakage of the relatively brittle orifice plates in the event of a slight mismatch of surfaces but also effectively seals against leakage between the orifice plate and the shaft.
  • the orifice plate operates as a dam so that a rotating pool of slurry is formed inside the conveyor shafi. Flow passing from the slurry pipe 13 into the interior of the shaft impinges on this pool rather than on the shaft itself so as to avoid excessive sliding and wear of the shaft.
  • the rotating pool operates to accelerate the slurry being fed to an angular velocity approaching that of the conveyor shaft so as to reduce the relative velocities when the slurry passes onto the bowl.
  • a centrifuge for separating a slurry into its solid and liquid components comprising: a centrally located slurry feed pipe; a rotating bowl concentric with said feed pipe; a rotating conveyor within said bowl and concentric of said slurry feed pipe which rotates at a speed slightly different than said bowl, said conveyor having a generally impervious tubular shaft and having on the outer portion of said shah means to urge solids longitudinally along said bowl; said feed pipe feeding slurry to the interior of said shaft at a feed location; said shaft having openings therethrough in the area of the feed location; and said openings having at least a trailing edge generally linear and parallel to the axis of said shafi.
  • An apparatus as in claim 2 having rectangular orifice members fastened inside said shaft at the location of said openings.
  • An apparatus as in claim 1 having orifice members fastened inside said shah at the location of said openings, said orifice having at least a trailing edge generally linear and parallel to the axis of said shaft.

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  • Centrifugal Separators (AREA)
US807750A 1969-03-17 1969-03-17 Centrifuge slurry supply Expired - Lifetime US3620442A (en)

Applications Claiming Priority (1)

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US80775069A 1969-03-17 1969-03-17

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GB (1) GB1238821A (sv)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3955756A (en) * 1971-06-21 1976-05-11 Flottweg-Werk, Dr. Georg Bruckmayer Gmbh & Co. Kg Solid-shell screw-conveyor centrifuge
WO1993010905A1 (en) * 1991-11-27 1993-06-10 Baker Hughes Incorporated Feed accelerator system including feed slurry accelerating nozzle apparatus
WO1993010906A1 (en) * 1991-11-27 1993-06-10 Baker Hughes Incorporated Feed accelerator system including accelerating cone
US5403486A (en) * 1991-12-31 1995-04-04 Baker Hughes Incorporated Accelerator system in a centrifuge
US20020132718A1 (en) * 2000-08-31 2002-09-19 Koch Richard James Centrifuge for separating fluid components
US20030096691A1 (en) * 2000-08-31 2003-05-22 Koch Richard James Centrifuge systems and methods
US7018326B2 (en) 2000-08-31 2006-03-28 Varco I/P, Inc. Centrifuge with impellers and beach feed
US20160368002A1 (en) * 2015-06-19 2016-12-22 Andritz S.A.S. Decanter centrifuge
US20210394203A1 (en) * 2020-06-22 2021-12-23 National Oilwell Varco, L.P. Decanter centrifuge nozzle

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3368747A (en) * 1965-10-20 1968-02-13 Pennsalt Chemicals Corp Centrifuge
US3428248A (en) * 1967-09-26 1969-02-18 Combustion Eng Continuous centrifuge apparatus
US3447742A (en) * 1965-10-21 1969-06-03 Alfa Laval Ab Sludge-separating centrifuge

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3368747A (en) * 1965-10-20 1968-02-13 Pennsalt Chemicals Corp Centrifuge
US3447742A (en) * 1965-10-21 1969-06-03 Alfa Laval Ab Sludge-separating centrifuge
US3428248A (en) * 1967-09-26 1969-02-18 Combustion Eng Continuous centrifuge apparatus

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3955756A (en) * 1971-06-21 1976-05-11 Flottweg-Werk, Dr. Georg Bruckmayer Gmbh & Co. Kg Solid-shell screw-conveyor centrifuge
WO1993010905A1 (en) * 1991-11-27 1993-06-10 Baker Hughes Incorporated Feed accelerator system including feed slurry accelerating nozzle apparatus
WO1993010906A1 (en) * 1991-11-27 1993-06-10 Baker Hughes Incorporated Feed accelerator system including accelerating cone
US5423734A (en) * 1991-11-27 1995-06-13 Baker Hughes Incorporated Feed accelerator system including feed slurry accelerating nozzle apparatus
US5527258A (en) * 1991-11-27 1996-06-18 Baker Hughes Incorporated Feed accelerator system including accelerating cone
US5651756A (en) * 1991-11-27 1997-07-29 Baker Hughes Inc. Feed accelerator system including feed slurry accelerating nozzle apparatus
US5403486A (en) * 1991-12-31 1995-04-04 Baker Hughes Incorporated Accelerator system in a centrifuge
US5527474A (en) * 1991-12-31 1996-06-18 Baker Hughes Incorporated Method for accelerating a liquid in a centrifuge
US20020132718A1 (en) * 2000-08-31 2002-09-19 Koch Richard James Centrifuge for separating fluid components
US20030096691A1 (en) * 2000-08-31 2003-05-22 Koch Richard James Centrifuge systems and methods
US6780147B2 (en) 2000-08-31 2004-08-24 Varco I/P, Inc. Centrifuge with open conveyor having an accelerating impeller and flow enhancer
US6790169B2 (en) 2000-08-31 2004-09-14 Varco I/P, Inc. Centrifuge with feed tube adapter
US7018326B2 (en) 2000-08-31 2006-03-28 Varco I/P, Inc. Centrifuge with impellers and beach feed
US20160368002A1 (en) * 2015-06-19 2016-12-22 Andritz S.A.S. Decanter centrifuge
KR20160150048A (ko) * 2015-06-19 2016-12-28 안드리츠 에스.아.에스. 디캔터 원심분리기
US9931643B2 (en) * 2015-06-19 2018-04-03 Andritz S.A.S. Decanter centrifuge with wear-resistant accelerator inserts
US20210394203A1 (en) * 2020-06-22 2021-12-23 National Oilwell Varco, L.P. Decanter centrifuge nozzle
US11772104B2 (en) * 2020-06-22 2023-10-03 National Oilwell Varco, L.P. Decanter centrifuge nozzle

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Publication number Publication date
GB1238821A (sv) 1971-07-14

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