Discharge of solid particles from centrifugal machines

Claim 2

In a process of discharging particles from a centrifugal machine having a rotating centrifuge basket with a lip, a method of modifying the flight of solid particles discharged from the lip of said centrifuge basket, said particles having a radial component of velocity considered in a direction radially outwardly of the basket, wherein the improvement comprises creating a pneumatic zone extending around said basket lip and directing a series of jets of gas into said pneumatic zone so as at least to reduce the radial component of velocity of the particles discharged from said lip.

Claim 3

The process as set forth in claim 1 consisting essentially of directing the jets of gas at an acute angle relative to tangential planes taken with respect to the basket lip, said jets of gas being adapted to have a velocity sufficient to both reduce the particles'' speed in said tangential planes and to reverse the component of velocity in a circumferential direction around the basket whereby to cause the particles to move around the basket in the opposite direction to the direction of rotation of the basket.

Claim 4

The method as set forth in claim 1 consisting essentially of directing the jets of gas at an obtuse angle relative to tangential planes taken with respect to the basket lip, said jets of gas being adapted to have a velocity sufficient to both reduce the particles'' speed in said tangential planes and to cause the particles to move around the basket in the direction of rotation of the basket.

Claim 5

The method as set forth in claim 1 consisting essentially of pneumatically conveying separated particles away from the machine.

Claim 6

The method as set forth in claim 4 consisting essentially of introducing auxiliary gas into said pneumatic zone for assisting pneumatic conveyance of the particles.

Claim 7

The method as set forth in claim 5 consisting essentially of heating said auxiliary gas.

Claim 8

The method as set forth in claim 1 which consists essentially of directing the jets of gas substantially opposite to tangential planes taken with respect to the basket, said jets being adapted to have a velocity substantially equal to that of particles discharged from said basket.

Claim 9

The method as set forth in claim 1 which consists essentially of heating said first-mentioned gas.

Claim 10

A centrifugal machine having a perforated frustoconical centrifugal basket with a discharge lip and including means for introducing into said basket slurry to be separated, wherein the improvement consists essentially of: a stationary hollow casing surrounding said basket which casing defines an annular pneumatic zone around said lip, said casing having an outlet, a toroidal manifold forming part of said casing and surrounding said pneumatic zone, means for introducing a pressurized gas into said manifold, a shallow annular passage between said casing and said manifold, means located within said passage for establishing a plurality of jets of gas directed into said pneumatic zone, which jets of gas are directed so as at least to reduce a radial component of velocity, considered in a direction radially outward of said basket, of solid particles separated from said slurry and dischargEd over said lip, while said particles are located in said pneumatic zone.

Claim 11

A centrifugal machine having a perforated frustoconical centrifugal basket with a discharge lip and including means for introducing into said basket slurry to be separated, wherein the improvement consists essentially of: a stationary hollow casing surrounding said basket which casing defines an annular pneumatic zone around said lip, said casing having an outlet, a toroidal manifold forming part of said casing and surrounding said pneumatic zone, means for introducing a pressurized gas into said manifold, a shallow annular passage between said casing and said manifold, means located within said passage for establishing a plurality of jets of gas directed into said pneumatic zone, which jets of gas are directed so as at least to reduce a radial component of velocity, considered in a direction radially outward of said basket, of solid particles separated from said slurry and dischargEd over said lip, while said particles are located in said pneumatic zone.

Claim 12

A centrifugal machine as set forth in claim 9 wherein the means for establishing the plurality of jets of gas comprises a plurality of guide vanes.

Claim 13

A centrifugal machine as set forth in claim 10 wherein the vanes are angled at an acute angle relative to tangential planes taken with respect to the basket lip.

Claim 14

A centrifugal machine as set forth in claim 10 wherein the vanes are angled at an obtuse angle relative to tangential planes taken with respect to the basket lip.

Claim 15

A centrifugal machine as set forth in claim 10 wherein the vanes lie in substantially tangential planes taken with respect to the basket lip.

Claim 16

A centrifugal machine as set forth in claim 13 wherein the casing has an inner periphery surrounding and adjacent to said lip, and an outer periphery adjacent to said shallow annular passage, said outer periphery being deeper than said inner periphery.

Claim 17

A centrifugal machine as set forth in claim 10 wherein the vanes are straight.

Claim 18

A centrifugal machine as set forth in claim 10 wherein the vanes are curved.

Claim 19

A centrifugal machine as set forth in claim 9 wherein the casing is of gradually increasing cross-sectional area in a direction leading towards the outlet.

Claim 20

A centrifugal machine as set forth in claim 17 wherein the casing is of volute form.

Claim 21

A centrifugal machine as set forth in claim 17 wherein the casing increases in cross section abruptly towards the outlet.

Claim 22

A centrifugal machine as set forth in claim 17 wherein a conveyor duct is provided at the outlet to said casing for pneumatically conveying separated particles from said centrifugal machine.

Claim 23

A centrifugal machine as set forth in claim 20 wherein additional gas means are provided for assisting the flow of particles along said conveyor duct.

Claim 24

A centrifugal machine as set forth in claim 20 wherein reduced pressure means are provided for applying a reduced pressure to the end of said conveyor duct remote from said centrifugal machine.