WO1992007659A1

WO1992007659A1 - Feed distribution and control arrangement for centrifuge

Info

Publication number: WO1992007659A1
Application number: PCT/AU1990/000525
Authority: WO
Inventors: Charles Rodney Murry
Original assignee: NQEA AUSTRALIA Pty Ltd
Current assignee: NQEA AUSTRALIA Pty Ltd
Priority date: 1990-10-31
Filing date: 1990-10-31
Publication date: 1992-05-14
Anticipated expiration: 1993-04-30

Abstract

A tube (100) feeds a solid/liquid mixture (130) to the centre of a rotating perforated centrifuge basket (10) having a central cylindrical portion (40). Control of the feed is provided by moving the tube (100) vertically so that an annular gap (120) is formed in the region (50) between the conical end (60) and tube (100). The central member including end (60) to which is attached a cylindrical extension (not numbered) is stationary. Tube (100) is of such a diameter that when completely lowered it closes the gap (120). Member and end (60) may be hollow to allow introduction of steam, water, or other fluids into the region (50) for the purpose of heating or lubrication. The invention relates particularly to centrifuging massecuite.

Description

FEED DISTRIBUTION AND CONTROL ARRANGEMENT FOR CENTRIFUGE

TECHNICAL FIELD

The present invention relates to a feed distribution and control arrangement for centrifugal separating machines. In particular the invention relates to centrifuges for the separation of solid and liquid mixtures one example of which is massecuite.

Massecuite is a mixture of solid sugar crystals and molasses.

BACKGROUND ART

In the prior art two types of feed distribution and control are known. In one arrangement (known as side feeding) the mixture of solid and liquid is fed eccentrically on to the bottom of a rotating conical basket down the outside of a fixed metal probe. In another arrangement (known as centre feeding), a rotating distribution device attached to the basket is used and includes a tortuous path to help distribute the solid/liquid mixture. The latter arrangement is described in Australian patent 487,750.

Central feed systems of similar principles but having different configurations are described in Australian patent 487,425 and Australian patent application No. 23,234/77. The first arrangement provides a basically single stream to the centrifugal separator and for good operation requires the use of a complex and expensive iris control valve. With massecuites of high crystal content it is difficult or impossible to obtain a steady stream of feed mixture. The second arrangement when used in the processing of massecuite results in damage to the sugar crystals and still requires the use of a control valve ahead of the feeding unit.

Particularly in sugar centrifuges for high grade assecuites the avoidance of damage to the sugar crystals is important. The distribution of the solid/liquid mixture to the conically shaped rotating basket is important to the proper separation of the solid particles from the liquid carrier.

The present invention seeks at least to overcome these disadvantages in the prior art.

DISCLOSURE OF INVENTION

The present invention improves on prior art arrangements by providing for centrifugal separating machines a stationary feed distribution and control device to deliver the solid/liquid mixture to the centrifuge.

In accordance with the invention there is provided a feed distribution and control arrangement for a centrifugal separating machine having a centrifuge basket including a vertical central stationary member having a cylindrical extension joined to a co-axial frusto-conical member, and a co-axial outer sleeve member enclosing said central member to define therebetween a variable annular space for receiving a liquid/solid mixture, said outer sleeve being movable vertically to thereby vary the opening or closing of said annular space to control the flow rate of said mixture and the distribution thereof into a lower part of the centrifuge basket of said centrifugal separating machine. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows a broad schematic cross section of the apparatus according to the invention, and

Figure 2 shows an enlarged schematic of the area corresponding to the feed zone of the centrifuge.

MODES FOR CARRYING OUT THE INVENTION

As shown schematically in Figure 1 a rotating basket or drum 10 which is driven from below comprises a frusto-conical member 12 joined to a central cylindrical section 40 which houses drive shaft and bearings (not shown) . The basket 10 is perforated to allow escape of the liquid component of the mixture into chamber 20 while solids, for example, sugar crystals in a massecuite, move up the basket 10 and thence into chamber 30.

A cylindrical sleeve member 100 is arranged co- axially about cylindrical section 40 of the drum 10. Sleeve member 100 surrounds a central stationary conical member 60 fixed to a cylindrical extension 70 supported against the wall of bent tube 90 by radial webs 80. The mixture of liquid and solid is fed along tube 90 leading to sleeve 100 as indicated generally at arrow 85.

Instead of the bend in tube 90 other arrangements are possible such as a rectangular or cylindrical head box. The feed material may then be introduced into the head box by a branch pipe of about the same diameter as tube 90 in any convenient location and at any convenient angle. The cylindrical extension 70 may continue through the top of the head box in a manner similar to Figure 1 or may be terminated inside tube 90 or the head box by a suitable closure, for example near the top of radial webs 80.

Sleeve member 100 is movable vertically along the axis of the sleeve to define a loading or distribution region 50 for the centrifuge. Sleeve member 100 is of a diameter such that when it is completely lowered it closes the annular gap 120 between its lower edge and conical member 60.

Suitable mechanical means 110 are provided to control movement of the sleeve member 100. Means 110 may be either operated manually or automatically. By adjusting the height of sleeve member 100 the annular gap 120 can be adjusted to control the rate of flow of solid/liquid feed mixture while also enabling it to be distributed in a uniform curtain 130 on to the rotating distribution region 50 of basket 10.

Extension 70 may comprise a hollow column connected to cone 60 to be used for the introduction of steam, water, molasses, syrup or other fluids into the lower distribution area 50 for the purpose of heating or lubrication. Equally the inner surface of the feed material within sleeve member 100 can be heated or lubricated through the extension 70 and cone 60.

When extension 70 does not continue through the bend in pipe 90 or through the alternate head box, convenient connections may be made to extension 70 or cone 60 by pipes attached to or incorporated in the webs 80 and penetrating the wall of pipe 90 at convenient locations.above sleeve 100.

Also by using flexible connexions spray nozzles for steam, water, molasses, syrup or other fluids can be mounted on the outside of the sleeve member 100 to treat the material on the basket of the centrifuge.

The present invention provides a simple and effective arrangement for the distribution and also the control of the feed mixture in a centrifugal separating machine. Though the invention has been described above with respect to a driving arrangement in which the conical basket is driven from below with the discharge of the separated components occurring vertically other arrangements are possible within the knowledge of a person skilled in the art. Equally it is to be understood that the arrangement can be used with other solid/liquid mixtures than massecuite and with other basket or drum shapes.

Claims

1. A feed distribution and control arrangement for a centrifugal separating machine having a centrifuge basket including a vertical central stationary member having a cylindrical extension joined to a co-axial frusto-conical member, and a co-axial outer sleeve member enclosing said central member to define therebetween a variable annular space for receiving a liquid/solid mixture, said outer sleeve being movable vertically to thereby vary the opening or closing of said annular space to control the flow rate of said mixture and the distribution thereof into a lower part of the centrifuge basket of said centrifugal separating machine.

2. A feed distribution and control arrangement as claimed in claim 1 further including means to move said outer sleeve in a vertical direction.

3. A feed distribution and control arrangement as claimed in claim 2 further including feeding means to introduce a liquid/solid mixture to said variable annular space.

4. A feed distribution and control arrangement for a centrifugal separating machine as claimed in claim 3 further including means for heating and/or lubricating said variable annular space.

5. A feed distribution and control arrangement as claimed in claim 4 further including means for heating and/or lubricating said mixture in said feeding means.

6. A feed distribution and control arrangement as claimed in any one of the previous claims wherein said cylindrical extension and said coaxial frusto-conical member are hollow.

7. A feed distribution and control arrangement as claimed in claim 6 wherein said basket comprises a perforated rotating frusto-conical drum joined to a central cylindrical section, with said section housing drive means to rotate said basket.

8. A feed distribution and control arrangement as claimed in claim 7 further including means to space said cylindrical extension from said coaxial outer sleeve member.

9. A centrifugal separating machine including a feed distribution and control arrangement as claimed in any previous claim.