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Publication numberUS3447742 A
Publication typeGrant
Publication dateJun 3, 1969
Filing dateOct 21, 1966
Priority dateOct 21, 1965
Also published asDE1532678A1
Publication numberUS 3447742 A, US 3447742A, US-A-3447742, US3447742 A, US3447742A
InventorsJohn Thorbjorn Eriksson, Birger Torsten Arne Moller
Original AssigneeAlfa Laval Ab
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Sludge-separating centrifuge
US 3447742 A
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Description  (OCR text may contain errors)

June 3, 1969 J sso ET AL 3,447,742

SLUDGE-SEPARAT ING CENTRIFUGE Filed Oct. 21, 1966 Ell-gel- Ensen Arne Nil/sf Y United States Patent US. Cl. 233-7 1 Claim ABSTRACT OF THE DISCLOSURE The centrifugal rotor has an outlet for separated sludge and a separate level-maintaining outlet for separated liquid, the mixture of liquid and sludge being fed into the rotor from the discharge opening of a supply pipe. A screw conveyor has a shaft mounted for rotation in the rotor and is operable to convey centrifugally separated sludge to the sludge outlet; and a circular disc is fixed to this shaft at an axial location between the discharge opening of the supply pipe and the sludge outlet, the disc being coaxial with the screw conveyor and having its periphery lying radially outside the level-maintaining outlet. A second circular disc is fixed to the shaft at an axial location between the discharge opening of the supply pipe and the level-maintaining outlet, the second disc also being coaxial with the screw conveyor and having its periphery lying radially outside the level-maintaining outlet but radially inside the periphery of the first disc.

The present invention relates to sludge-separating centrifuges of the type having a screw conveyor by which centrifugally separated sludge is discharged at one end of the rotor, a level-maintaining outlet at the other end of the rotor for the discharge of separated liquid, a circular disc in the rotor fixed to the shaft of the screw conveyor and coaxial with the screw conveyor, the periphery of this disc lying radially outside the level-maintaining outlet, and a supply pipe extending into the rotor.

When separating a liquid containing fat and water in centrifuges of this kind, it has been found that sludge discharged from the centrifuge has a certain fat content. According to the present invention, this fat content can be avoided by providing a disc similar to that previously mentioned but located axially beyond the opening of the supply pipe, reckoned from the level-maintaining outlet. The disc so located constitutes a barrier for the fat layer, which is formed by the centrifuging as the radially innermost layer, so that the sludge which the screw conveyor removes from the water layer cannot come into contact with the fat. In this way, the sludge discharged from the centrifuge will be free from fat.

The invention is described more in detail below in ref erence to the accompanying drawing, in which the single illustration is a vertical sectional view of an embodiment of the new centrifuge.

In the drawing, a centrifuge rotor 1 has a conical part 13 and is provided at its opposite ends with trunnions 11 and 11a which, by bearings and 10a, are rotatably journalled in a stationary housing 12. Inside the rotor is a screw conveyor 2 arranged to rotate about the same axis as the rotor but driven by shaft 2a at a speed of rotation somewhat different from that of the rotor. The screw conveyor serves to feed centrifugally separated sludge along the conical wall 13 of the rotor to a sludge outlet 14 through which the sludge is discharged under centrifugal force. In the larger end wall 8 of the rotor is an overflow outlet 5. A stationary supply pipe 6 for the material to be treated extends into the rotor. This pipe is coaxial with the rotor and passes through the hollow trunnion 11a. Rotor 1 is driven in any suitable manner, as through gearing (not shown) connected to trunnion 11.

When a centrifuge of the type initially described is in operation, the material fed from supply pipe 6 forms an annulus 15 at the inside of the rotor, due to the action of centrifugal force. The centrifugal force divides this annulus into annular layers, due to the different specific gravities of the components of the feed mixture. For example, if a mixture of water, oil and sludge is to be separated, the mixture is divided centrifugally into an oil layer located nearest the rotation axis, then a water layer, and then a sludge layer located farthest from the rotor axis. As screw conveyor 2 feeds the sludge along the inside of the rotor wall towards its outlet 14, the sludge will thus pass through the oil layer lying nearest the rotor axis and contacting the conical wall 13 of the rotor. It is obvious that the sludge will then entrain a substantial quantity of oil, which is lost.

According to the present invention, a circular disc 4 is fixed to the shaft 3 of the screw conveyor 2 and is coaxial with the screw conveyor, the periphery of this disc lying radially outside the overflow outlet 5. Disc 4 is located axially beyond the opening 7 of the supply pipe 6, reckoned from the outlet 5, and forms a dam which prevents the separated oil layer from flowing in the direction toward the sludge outlet 14. Consequently, when the sludge phase is fed radially inward through the liquid phase by the screw conveyor, the sludge will not pass through any oil layer but only through a water layer. The sludge will thus be completely free from oil. The location where the circular disc 4 is fixed to the screw conveyor shaft 3 will be seen from the drawing.

It may happen that solid fat lumps are contained in the material which is fed to the centrifuge through the supply pipe 6. These fat lumps often contain substantial quantities of sludge particles. Normally, these lumps will float on the annular liquid surface and discharge through the outlet 5, whereby the separated fat phase will contain contaminating sludge. In order to prevent this, a circular disc 4a is fixed to the screw conveyor shaft 3 at an axial location between the opening 7 of the supply pipe 6 and the level-maintaining outlet 5. The periphery of the disc 4a lies radially outside the level-maintaining outlet 5 and prevents the floating fat lumps from reaching that outlet. After some time they melt, whereupon the released sludge is centrifugally separated and joins the sludge conveyed to the sludge outlet 14. Obviously, the diameter of the discs is chosen so that the disc 4 extends radially through at least the whole thickness of the oil layer, whereas the disc 4a mainly breaks only the surface of the oil layer.

We claim:

1. In a sludge-separating centrifuge, the combination of a centrifugal rotor, a supply pipe extending into the rotor and having an opening for discharging a mixture of liquid and sludge into the rotor, the rotor having an outlet for centrifugally separated sludge and a separate level-maintaining outlet for centrifugally separated liquid, a screw conveyor in the rotor operable to convey centrifugally separated sludge to said sludge outlet, said conveyor having a shaft mounted for rotation in the rotor, a circular disc fixed to said shaft at an axial location between said discharge opening of the supply pipe and said sludge outlet, said disc being coaxial with the rotation axis of the screw conveyor and having its periphery lying radially outside said level-maintaining outlet, and a second circular disc fixed to said shaft at an axial location between said discharge opening of the supply pipe and said level-maintaining outlet, the second disc also being coaxial with the rotation axis of the screw conveyor and having its periphery lying radially outside said 4 level-maintain ing outlet but radially inside said periphery FOREIGN PATENTS 0f the 1,753,992 10/1957 Germany.

References 364,348 1/1932 Great Britain.

UNITED STATES PATENTS 3,228,594 1/1966 Amero 2337 0 r HENRY T. KLINKSIEK, Primary Examiner.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3228594 *Feb 5, 1965Jan 11, 1966Clifford L AmeroCentrifugal separator
*DE1753992B Title not available
GB364348A * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3534902 *Feb 7, 1969Oct 20, 1970Gilreath Lafayette ECombined centrifugal and magnetic separator mechanism
US3620442 *Mar 17, 1969Nov 16, 1971Combustion EngCentrifuge slurry supply
US3727831 *Aug 31, 1970Apr 17, 1973Georgia Kaolin CoMethod and apparatus for classifying fine particle materials
US3795361 *Sep 6, 1972Mar 5, 1974Pennwalt CorpCentrifuge apparatus
US3885734 *Jan 10, 1974May 27, 1975Pennwalt CorpCentrifuge apparatus
US4209128 *Apr 6, 1979Jun 24, 1980Yara Engineering CorporationMethods and apparatus for classifying fine particle solids
US5306225 *May 17, 1993Apr 26, 1994Tsukishima Kikai Co., Ltd.Decanter centrifuge having a disc-like dip weir with a hole
US5509882 *Sep 12, 1994Apr 23, 1996Tetra Laval Holdings & Finance S.A.Decanter centrifuge having an offset conveyor flight to aid rinsing
US5653673 *Jun 7, 1995Aug 5, 1997Amoco CorporationWash conduit configuration in a centrifuge apparatus and uses thereof
US5971907 *May 19, 1998Oct 26, 1999Bp Amoco CorporationContinuous centrifugal separator with tapered internal feed distributor
US6561965Oct 20, 2000May 13, 2003Alfa Laval Inc.Mist pump for a decanter centrifuge feed chamber
US6572524 *Jul 14, 2000Jun 3, 2003Alfa Laval Inc.Decanter centrifuge having a heavy phase solids baffle
US6749552 *Oct 18, 2000Jun 15, 2004Westfalia Separator Industry GmbhScrew-type solid bowl centrifuge having a baffle plate arrangement
US7056273May 27, 2003Jun 6, 2006Westfalia Separator AgSolid bowl screw centrifuge comprising a peeling disk, and method for the operation thereof
US7074173Apr 25, 2003Jul 11, 2006Westfalia Separator AgCentrifuge having a centrifugal drum and a groove including a seal
US7156801 *Apr 9, 2003Jan 2, 2007Alfa Laval Copenhagen A/SDecanter centrifuge with a screw conveyor having a varying pitch
US7229399 *May 27, 2004Jun 12, 2007Alfa Laval Corporate AbScrew conveyor for a decanter centrifuge
US7510519 *Jul 30, 2004Mar 31, 2009Westfalia Separator AgSolid bowl screw centrifuge comprising a centripetal pump with a throtting device
US7908764May 5, 2008Mar 22, 2011Decanter Machines, Inc.Hyperbaric centrifuge system
US8042281Sep 20, 2010Oct 25, 2011Decanter Machine, Inc.Hyperbaric centrifuge system
CN100467132CMay 27, 2004Mar 11, 2009阿尔法拉瓦尔股份有限公司A screw conveyor for a decanter centrifuge
DE2344507A1 *Sep 4, 1973Mar 14, 1974Pennwalt CorpDekantierzentrifuge
WO1996006046A1 *Aug 17, 1995Feb 29, 1996Juergen G BeverSewage clarification plant
WO1999059725A1May 5, 1999Nov 25, 1999Bp Amoco CorpContinuous centrifugal separator with tapered internal feed distributor
WO2001032314A1 *Oct 18, 2000May 10, 2001Westfalia Separator Ind GmbhScrew-type solid bowl centrifuge
WO2010037101A1Sep 29, 2009Apr 1, 2010Investigacion De Tecnologia Avanzada, S.A. De C.V.Method for the production of whole nixtamalized corn flour
Classifications
U.S. Classification494/53
International ClassificationB04B1/20
Cooperative ClassificationB04B2001/2083, B04B2001/2041, B04B1/20
European ClassificationB04B1/20