The invention relates to a device for separating into multiple components a fluid, such as gas, water, oil and more particularly an emulsion such as a mixture of water and oil, milk and so on, which device consists of a drum consisting of a cylindrical outer casing, a bottom and a cover, which bottom and cover can be or are attached hermetically to the outer casing, and wherein a cylindrical inner casing is mounted coaxially on the drum, thereby creating a space bounded by the outer surface of the cylindrical inner casing, the inner surface of the cylindrical outer casing, the bottom and the cover, in which space a large number of elongate elements are arranged extending from the inner casing as far as the outer casing, which drum can be set into rotation about its axis of symmetry or axis of rotation using drive means, in addition to supply means for feeding the fluid to the space close to the one outer end of the cylindrical casings and discharge means for discharging the fluid from the space close to the other outer end of the cylindrical casings .

Such a device is known from the PCT patent WO 00 32297 of applicant. A device is described in this patent application with which solids can be separated from a fluid.

The object of the invention is a device with which it is possible to separate into its components a fluid consisting of a mixture of liquids, such as an emulsion of oil in water and fat in milk or a gas in which a liquid is suspended in finely distributed manner.

This objective is achieved with the device according to the invention in that the cover is provided with two concentric circular outflow openings which are separated from

each other and the centres of which coincide with the axis of rotation, wherein the outflow opening with the greater diameter is separated by a wall from the outflow opening with the smaller diameter, and that the discharge means comprise two outlets separated from each other, wherein the one or first outlet discharges the fluid situated close to the outer casing from the space via the outflow opening with the greater diameter and the other or second outlet discharges the fluid situated close to the inner casing from the space via the outflow opening with the smaller diameter.

It is possible with the device according to the invention to rapidly separate an emulsion, such as a mixture of water and oil or a mixture of milk and fat, into a fraction with a high specific weight and a fraction with a low specific weight. The device is also suitable for rapid separation of a gas, in which a liquid is present in finely distributed state, into a gas fraction and a liquid fraction. By carrying the fluid through the brush space when the drum is in uniform rotation the fluid will then likewise be in uniform rotation as seen in the plane perpendicular to the axis of rotation, because the brush bristles carry the fluid with them in the rotating movement. Because the distance between the brush bristles is very small, very high rotation speeds can be applied without the liquid becoming turbulent. By supplying fluid constantly there will be a laminar flow of the fluid transversely of the direction of rotation, parallel to the axis of rotation. Under the influence of the centripetal and centrifugal forces the fluid will begin increasingly to separate as seen in the direction of the rotation axis into a layer with a high specific weight and into a layer with a low specific weight, and after separation both layers can be discharged individually.

It is generally per se known to separate an emulsion of for instance water and oil into its components using centrifuging. Such a known device is the disc centrifuge. A drawback of this known device is that when the flow rate changes the efficiency hereby falls rapidly, or that an undesirable quantity of water is entrained with the separated oil because the separating surface between water and oil must lie a determined distance from the rotation axis in order to obtain proper operation of the device. In contrast, the device according to the invention allows a variable separating surface. An additional advantage of the device according to the present invention is that solid particles which are present in the emulsion and which are deposited during rotation against the inner wall of the outer cylinder wall can be easily removed when the inner cylinder with the brush bristles can rotate independently of the drum. The solid particles deposited on the inner wall of the outer wall can then be removed from the drum in simple manner.

The elongate elements are preferably brush bristles which are fixed at one outer end to the inner cylinder wall and these together thus form a brush roller, and the space consists of three parts, viz. a brush space, in which part the elongate wire-like elements are arranged and through which the fluid flows from the feed to the discharge, a supply space for feed of the fluid to the space and a discharge space for discharge of the fluid from the drum, and that an intermediate plate arranged between the brush space and the discharge space separates the brush space from the discharge space, and the discharge space is divided into two parts by a wall, a first and a second part, with an opening in the intermediate plate close to the outer cylinder casing, through which opening the fluid flows via the one part of the discharge space to the outflow opening with the larger radius

forming the first outlet, and that a second opening is arranged in the intermediate plate close to the inner cylinder casing, which second opening discharges the fluid via the second part of the discharge space via the second circular outflow opening with the smaller radius . The drum preferably rotates about a vertical axis and the internal cylindrical inner casing extends through the smaller outflow opening, and the feed consists of a tube which protrudes freely of the drum in the internal cylindrical inner casing. A uniform weight distribution during rotation is obtained due to the vertical arrangement, and placing of the feed freely of the drum in the inner cylindrical casing achieves that the supply of the fluid through a stationary tube which does not co-rotate can be fed to the device. By arranging means in the discharge space, such as blades or radially running channels is achieved that the rotation energy of the radially outflowing fluid for discharge is decreased, whereby not only is rotation energy given back to the centrifuge but the pressure on the discharge side is moreover reduced.

The application of a method for separating substances mixed with each other, such as an emulsion, using a device according to the invention, according to which method the drum is first set into rotation empty together with the cylindrical inner casing, the fluid for separating is then supplied via the feed to the space in the drum once the drum is making a desired number of rotations per unit of time, wherein a determined quantity of a solid is also added to the fluid until a desired quantity of solid has been introduced into the drum, whereafter the fluid is supplied continuously without the added solid, achieves that the brush bristles are fixedly connected on the one side to the cylindrical inner casing as well as on the side of the cylindrical outer casing

because the solid comes to lie against the outer wall and will thereby also anchor the free outer ends of the brush bristles .

The invention will be further elucidated with reference to the drawing. In the drawing:

Fig. 1 shows a cross-section of a device according to the invention.

Fig. 2 is a cross-section through a device according to the invention as shown in figure 1, wherein the device is shown tilted.

Figure 1 shows a device according to the invention. The device consists of a drum 1, consisting of a cylindrical outer casing 2, a bottom 3 and a cover 4. Bottom 3 and cover 4 are hermetically attached to the outer casing close to the periphery. A double-walled cylindrical inner casing 5, 6 is arranged co-axially in drum 1, whereby a space 7 is created bounded by outer surface 8 of the cylindrical inner casing 6, inner surface 9 of the cylindrical outer casing 2, bottom 3 and cover 4. Arranged in this space 7 are a large number of elongate elements 10 in the form of brush bristles which are fixed at one outer end to inner casing 5 and which extend as far as outer casing 2. Drum 1 can be set into rotation about its axis of symmetry 12 using drive means 11. The fluid is supplied to the underside of space 7 via a feed tube 13. Cover 4 is provided with two concentric circular outflow openings 14 and 15 which are separated from each other and the centres of which coincide with the axis of rotation, wherein the first outflow opening 14 with the greater diameter is separated by a wall 16 from the second outflow opening 15 with the smaller diameter.

The elongate elements are brush bristles 10 which are fixed with one outer end to the inner cylinder wall 5, and these together thus form a brush roller. Space 7 consists of

three parts, viz. a feed space 17 for feeding the fluid to space 7, a brush space 18, in which part the elongate wire- like elements 10 are arranged and around which the fluid flows from the feed to the discharge, and a discharge space 19 for discharging the fluid from drum 1. Arranged between the brush space and the discharge space is an intermediate plate 20 which separates brush space 18 from discharge space 19. Discharge space 19 is divided into two parts by a wall 16, a first and a second part. Arranged in intermediate plate 20 close to the outer cylinder casing is an opening 21 through which the fluid flows via the one part of discharge space 19 to outflow opening 14 with the larger radius which forms the first outlet. A second opening 22 is arranged in intermediate plate 19 close to the inner cylinder casing, which second opening 22 discharges the fluid via the second part of the discharge space via the second circular outflow opening 15 with the smaller radius.

Figure 2 shows a part of the same device as shown in figure 1, wherein it is tilted through 45'. When the device rotates the liquid in space 7, under the influence of the centrifugal and centripetal forces, will then be pressed against the outer wall and separated in layers. The solid particles present in the fluid with a higher specific weight than the fluid will be deposited onto inner surface 9 of outer wall 2. The fluid itself, if it consists for instance of water with oil in solution, will be separated into two, wherein a separating surface 23 will be created. The separating surface will be set subject to the specific weight of the two liquids and the radius of the two outflow openings 14, 15 of the two liquids, thus the large radius 24 (R _water ) and the small radius 25 (R _oi i) . The distance (R _sv ) of the separating surface to the rotation axis can be calculated in roughly approximate manner from the following formula:

Pwater \ " sv ~ ^ oil ) ⁼ Pwater ( " sv ~ " water '

The separating surface will be set subject to the applied radii of the two outflow openings 14 and 15. The most advantageous situation can then be set experimentally, wherein a good separation of the water and the oil can be obtained.

Figure 3 shows in partial cross-section the upper part of the drum. The fraction of the fluid with the highest specific weight flows out of the drum as according to arrow 26 and the fraction with the lowest specific weight moves via throughflow openings 27 and outflow opening 15 and will be collected in collecting container 28, whereafter it can be discharged.

The method for separating mixed together substances such as an emulsion of water with oil or milk with fat using a device is now as follows: the drum is first set into rotation together with the cylindrical inner casing while the drum is still empty, and the fluid for separating is supplied via the feed to the space in the drum once the drum has been brought to a desired number of rotations per unit of time. The supply is then controlled such that the best possible separation of the two substances is obtained at the egress of the drum. Since it may occur that the bristles of the brush do not connect properly to the cylindrical outer wall of the drum, a determined quantity of a solid can be added to the fluid for a determined period of time until a desired quantity of solid has been introduced into the drum, whereafter the fluid is supplied continuously without the added solid. This can prevent the possible occurrence of a flow along the outer surface because the outer ends of the brush bristles do not connect sufficiently to the cylindrical outer wall .