GB2169225A - Centrifugal separator - Google Patents

Abstract

A centrifugal separator (Figure 1) for purification of gas oil on ships comprises a chamber (1) provided with a cover (2), a vertical shaft (4) and discs in the shape of truncated cones. The frustro-conical discs (5) (5a) and (7) are formed in one piece with the shaft (4), which comprises a central passage (25) for transporting liquid to be treated and at its base some radial passages (27) for distribution of said liquid into the chamber. The discs (5) and (5a) comprise staggered vertical partitions (22). A security recuperator (Figure 3) comprising inlet (52), float (54), valve (56) and exit (53) may be provided at the centrifuge exit (39) which acts to return liquid to the supply pump in the event of improper function of the centrifuge. <IMAGE>

Description

SPECIFICATION Centrifugal separator The present invention relates to a centrifugal separator which is particularly suitable for purifying liquids containing materials in suspension or for separating liquids of different densities. The apparatus according to the invention is particularly appropriate for the purification of gas-oil on ships by separation of the water and of the sediments which it contains.

Known centrifugal separators are complex apparatus, difficult to repair on a ship even by a skilled mechanic.

Such apparatus essentially comprise a chamber provided with a distributor for liquid to be separated comprising a vertical shaft on which are threaded, in a predetermined order, frustro-conical discs for distribution into thin layers, the flow of liquid to be treated. The frustro-conical discs comprise holes and ribs. The driving of these separators is in general provided by a gearing system formed of a worm and a tooth wheel.

It is desirable to construct a simple and robust centrifugal separator which can be dismantled and repaired or cleaned in a few minutes without difficulty in its place of use.

The present invention provides a centrifugal separator for liquids possibly containing materials in suspension, comprising a chamber provided with a cover, a vertical shaft and a plurality of integral frustro-conical discs, the shaft defining a central passage for the supply of liquid to be treated and having at its base radial passages for distribution of said liquid into the chamber, and staggered vertical partitions extending from at least some of said discs.

The assembly and dismantling of such a centrifugal separator does not require the minute detail demanded for the manipulation of known centrifugal separators.

An embodiment of the invention will now be described by way of example only, with reference to the accompanying diagrammatic drawings in which: Figure 1 is an elevational view in axial section of the centrifugal separator according to the invention incorporated into a working housing, Figure 2 is a view in section of the shaft of the centrifugal separator taken on line ll-ll, and Figure 3 is an axial section of an example of a security recuperator which can be used with the centrifugal separator of the invention.

The centrifugal separator shown in Figure 1 comprises: - a watertight chamber 1 provided with a cover 2, the part exterior to the base of the chamber comprising a thread 3; - a vertical shaft 4 and frustro-conical discs 7, 5 and 5a formed in one piece with the shaft 4, by casting or machining from a single piece; - a separation cup 6 which covers the upper frustro-conical disc 7 of the shaft 4.

The chamber 1 is fixed by its lower part onto a shaft 10 provided with a tapped hole correspond ing to the thread 3, said shaft being mounted rotat ably in a thrust bearing 8 fixed to the base 13 of the housing 9, said shaft carrying a pulley 11 driven by the intermediary of a belt connected to en gine means. The thrust bearing 8 comprises roller bearings 12.

The hollow shaft 4 carrying the discs 5, 5a and 7 is extended at its upper end by a supply pipe 14, held fixed by the upper bearing 15 comprising a spring 16, a water-tight seal and fixing means to the cover 19. The spring 16 acts to apply the seal in its optimum position and allows compensation for the expansion of the whole of the apparatus.

According to another embodiment, the pipe 14 can equally be mounted rotatably in the upper bearing 15.

The cover 2 of the chamber is maintained on the chamber by an annular locking part 20 comprising a screw thread corresponding to a screw thread on the upper outer edge of the chamber 1.

The shaft 4 of the centrifugal separator comprises at least three solid discs of frustro-conical shape, the upper disc 7 comprising six grooves 21 on its upper part. The other discs 5 and 5a each comprise vertical partitions 22 advantageously three vertical partitions, which are disposed staggered as shown in Figure 2, the vertical partitions 22 in dotted lines being those of the lower disc of the shaft, those in full line being those of the intermediate disc. Each vertical partition 22 extends from one disc to the other, is formed of the same material as the discs and is fixed to the shaft 4 and to the discs by solder. The vertical partitions 22 ensure the stirring of the solution to be separated.

The speed of rotation of the apparatus is advantageously in the range 5800 rpm.

Each disc comprises on its periphery orifices 23 and in the proximity of the shaft 4 orifices 24.

There are preferably six orifices 23 and six orifices 24 in each disc. Together the orifices 23 define a passage or exterior crossing and the orifices 24 together define a passage or interior crossing in the separator.

The shaft 4 comprises a central passage 25 for conducting liquid to be treated and in its frustro conical base 26, six radial passages 27 for distribution of the said liquid into the chamber 1. The base 26 of the shaft comprises at its lower end a boss 28 corresponding to the cavity 29 in the base of the chamber 1.

The separation cup 6 is defined by a frustro-conical part 30 and by a cylindrical part 31 coaxial with the shaft 4, which defines at its upper end a circular orifice 32.

The cover 2 of the chamber is defined by a frustro-conical part and by several cylindrical parts which respectively rest on the cap 6 and the shaft 4 and comprise circular orifices 33 and 34 for the outlet of liquids.

The housing 9 comprises a cover 35 fixed to said housing by appropriate fixing means 36, for example by butterfly or wing nuts as shown in Figure 1.

The cover 35 comprises an internal envelope 37 arranged in such a manner as to provide a recovery chamber for the dense liquid, which leaves the centrifugal separator by the circular orifice 33 and is recovered by the pipe 39.

The cover 35 of the housing 9 comprises a flange 41 on which is fixed, by appropriate means, the cover 19. The space between the cover 35 and the housing 9 and the cover 19 constitutes a second recovery chamber 40 for the less dense liquid, which is drawn off from this chamber by the pipe 39a.

The water tightness of the centrifugal separation system is ensured by known water tight joints, such as those represented at 42.

The described apparatus is particularly suitable for the purification of gas-oil by separation of sediments and of the water which it contains. Before operation of the apparatus it is essential to fill the chamber 1 with a certain quantity of water. By the centrifugal force, the water is projected against the walls of the chamber where it becomes stable.

The fuel to be treated is lead under pressure through the funnel 43, arriving in the chamber by the radial passages 27; the sediments become deposited along the walls of the chamber and the liquids are separated by the centrifugal force; the heavy liquid, for example water, leaves the chamber by the exterior passage provided by the separation cup 6 and arrives in the chamber 38 where it is drawn off; the lighter liquid, for example the gas-oil, leaves the chamber by the interior passage provided between the shaft and the separation cup and arrives in the chamber 40 where it is drawn off.

For the cleaning of the apparatus, it is sufficient to unscrew the nuts 36, to vertically raise the assembly 15, 19 and 35 guided by a window hinge and to rotate it. One can then easily lift the shaft 4 from the chamber 1. This shaft consisting only of fixed elements can easily be cleaned and remounted without risk of errors. The chamber 1 and the shaft 4 are advantageously formed in stainless steel.

The described separation system can be coupled with a security recuperator which allows the liquid to be purified to be returned to the supply pump in the case where this would escape by the orifice 39 for recovery of heavy liquid on account of a badfunctioning of the centrifugal separator, which can occur when the indispensible film of water for good-functioning of the separator has dispersed.

An example of such a security recuperator is shown in Figure 3. This recuperator is formed by a housing 50 provided with a cover 51 comprising an entrance orifice 52 for liquid and an exit orifice 53 for liquid. This housing contains a float 54 provided on a vertical axle 55 comprising a valve 56 and a valve seat 57, and level bosses 58. The cover 51 is provided with a blind nut 59. The shaft is guided in the interior of the housing by the cross pieces 60 and 60a provided with orifices for the passage of liquid. In the case where too large a quantity of liquid issuing from 39 is discharged into the housing 50, the float 54 is displaced upwardly and causes the opening of the valve 56 thus permitting liquid to be evacuated and recycled to the supply pump.

Claims (8)

1. A centrifugal separator for liquids possibly containing materials in suspension, comprising a chamber provided with a cover, a vertical shaft and a plurality of integral frustro-conical discs, the shaft defining a central passage for the supply of liquid to be treated and having at its base radial passages for distribution of said liquid into the chamber, and staggered vertical partitions extending from at least some of said discs.

2. A centrifugal separator for liquids according to claim 1, wherein each disc defines orifices on its periphery and in a central portion in the region of the shaft.

3. A centrifugal separator for liquids according to claim 1 or 2, wherein the uppermost disc comprises grooves.

4. A centrifugal separator for liquids according to any one of claims 1 to 3, wherein the vertical shaft is connected at its upper end to the cover of the chamber and at its lower end to the base of the chamber.

5. A centrifugal separator for liquids according to any one of claims 1 to 4, wherein the shaft carrying the discs is elongated at its upper end by a supply pipe fixedly mounted in a bearing on a cover of a housing.

6. A centrifugal separator for liquids according to any one of claims 1 to 5, wherein the chamber is fixed at its lower end on a shaft mounted rotatably in a thrust bearing fixed to the base of a separator housing, said shaft being driven by the intermediary of a belt connected to engine means.

7. A centrifugal separator for liquids according to any one of claims 1 to 6, wherein, at the outlet of an evacuation pipe for a dense liquid, there is mounted a security recuperator with float.

8. A centrifugal separator substantially as herein described with reference to the accompanying drawings.