Solid bowl decanter centrifuges
First Claim
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1. A method of centrifuging comprising the steps of rotating a bowl decanter at a first speed;
- rotating a scroll conveyor within the bowl at a second, slightly different speed for conveying separated solids to a solids discharge end of the bowl;
introducing the suspension to be centrifuged into a feed compartment formed in a hub portion of the scroll conveyor;
introducing a flocculating additive to the feed compartment substantially separate from the suspension;
mixing said suspension and flocculating additive within said feed compartment; and
delivering said mixed suspension and flocculating additive from the feed compartment to the bowl before substantial flocs have been formed.
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Abstract
A solid bowl decanter centrifuge of the scroll discharge type comprises a solid bowl which rotates at a first speed, and a scroll conveyor which is rotated within the bowl at a second, slightly different speed for conveying separated solids to a solids discharge end of the bowl. The suspension to be centrifuges, substantially unmixed with a flocculant, is introduced by a stationary feed pipe into a feed compartment which is a radial passage in the conveyor. The feed compartment provides high turbulence and shear forces which mix and expel the suspension and flocculant into the bowl before flocs have formed.
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Citations
10 Claims
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1. A method of centrifuging comprising the steps of rotating a bowl decanter at a first speed;
- rotating a scroll conveyor within the bowl at a second, slightly different speed for conveying separated solids to a solids discharge end of the bowl;
introducing the suspension to be centrifuged into a feed compartment formed in a hub portion of the scroll conveyor;
introducing a flocculating additive to the feed compartment substantially separate from the suspension;
mixing said suspension and flocculating additive within said feed compartment; and
delivering said mixed suspension and flocculating additive from the feed compartment to the bowl before substantial flocs have been formed. - View Dependent Claims (2, 3, 4)
- rotating a scroll conveyor within the bowl at a second, slightly different speed for conveying separated solids to a solids discharge end of the bowl;
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5. In a bowl decanter centrifuge of the scroll discharge type comprising a solid bowl, means for rotating said bowl at a first speed, a scroll conveyor, means for rotating the conveyor within the bowl at a second, slightly different speed for conveying separated solids to a solids discharge end of the bowl, a feed compartment formed in a hub portion of the scroll conveyor and communicating with the interior of the bowl through an aperture in the conveyor hub portion, a feed pipe for introducing to the feed compartment a suspension which is to be centrifuged, means for introducing a polyelectrolyte additive into the suspension so that the suspension entering the feed compartment is substantially unmixed with the additive, said feed compartment having a transverse interior wall surface and oppositely extending radial passage means, said transverse interior wall surface being aligned with and immediately downstream of the outlet of the feed pipe to create an area of high turbulence and high shear forces to mix the suspension and polyelectrolyte additive, said radial passage means extending directly from the feed pipe to prevent axial and circumferential movement of the suspension in the scroll and to deliver the mixed suspension and additive substantially immediately in opposite directions from the feed pipe into the bowl.
- 6. A solid bowl decanter centrifuge of the scroll discharge type comprising a solid bowl, means for rotating said bowl at a first speed, a scroll conveyor, means for rotating the conveyor within the bowl at a second, slightly different speed for conveying separated solids to a solids discharge end of the bowl, a feed compartment formed in a hub portion of the scroll conveyor and communicating with the interior of the bowl through an aperture in the conveyor hub portion, a stationary feed pipe for introducing to the interior of the feed compartment a suspension which is to be centrifuged, means for introducing into the suspension prior to its introduction to said feed compartment a flocculating additive which is substantially unmixed with the suspension entering the feed compartment, said feed compartment consisting essentially of a substantially radially extending passage disposed to expel the suspension and additive into the bowl immediately after they leave the stationary feed pipe with, therefore, substantially zero residence time in said feed compartment.
Specification