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CHAPTER 9

CENTRIFUGALSEPARATIONS

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MATERI

9.1. Introduction.

9.2. Shape of the Free Surface of the Liquid

9.3. Centrifugal Pressure

9.4. Separation of Immiscible Liquids of DifferentDensities

9.5. Sedimentation in A Centrifugal Field

9.6. Filtration in A Centrifuge

9.7. Mechanical Design

9.8. Centrifugal Equipment

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9.1. INTRODUCTION

Accelerations is several thousand times to gravity

Benefits: Greater rates of separation;

the possibility of achieving separations which are either

not practically feasible, or actually impossible, in the

gravitational field; and

a substantial reduction of the size of the equipment

Two distinctly different ways:

By introducing a fluid with a high tangential velocity into a

cylindrical or conical vessel, as in the hydrocyclone and

in the cyclone separator (Ch. 1) By the use of the centrifuge. In this case the fluid is

introduced into some form of rotating bowl and is rapidly

accelerated

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USECENTRIFUGE

Separating particles on the basis of their size or

density Separating immiscible liquids of different densities

(dispersions or emulsions)

Filtration of a suspension

Drying of solids and, in particular, crystals

Breaking down of emulsions and colloidal

suspensions

Separation of gases (in the nuclear industry)

Mass transfer processes (desorption of oxygen

from sea water)

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9.8. CENTRIFUGAL EQUIPMENT

9.8.1. Classification of centrifuges

9.8.2. Simple bowl centrifuges

9.8.3. Disc centrifugesgeneral

9.8.4. Disc centrifuges

various types9.8.5. Decanting centrifuges

9.8.6. Pusher-type centrifuges

9.8.7. Tubular-bowl centrifuge

9.8.8. The ultra-centrifuge

9.8.9. Multistage centrifuges

9.8.10. The gas centrifuge

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SIMPLEBOWLCENTRIFUGES

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DISCCENTRIFUGES

GENERAL

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9.8.6. PUSHER-TYPECENTRIFUGES

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9.2. SHAPE OF THE FREE SURFACE OF

THE LIQUID

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9.5. SEDIMENTATION IN A

CENTRIFUGAL FIELD

Centrifuges are extensively used for separating fine

solids from suspension in a liquid.

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EXAMPLE9.1

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9.6. FILTRATION IN A CENTRIFUGE

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EXAMPLE9.3

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9.8. CENTRIFUGAL EQUIPMENT

9.8.1. Classification of centrifuges

9.8.2. Simple bowl centrifuges

9.8.3. Disc centrifugesgeneral

9.8.4. Disc centrifuges

various types9.8.5. Decanting centrifuges

9.8.6. Pusher-type centrifuges

9.8.7. Tubular-bowl centrifuge

9.8.8. The ultra-centrifuge

9.8.9. Multistage centrifuges

9.8.10. The gas centrifuge