Patent Publication Number: US-3877635-A

Title: Centrifugal separator with velocity reducer

Description:
[ Apr. 15, 1975 United States Patent [1 1 Donkin CENTRIFUGAL SEPARATOR WITH VELOCITY REDUCER Robert G, Donkin, 5408 E. 38 St., Tulsa, Okla. 74135 Filed: Jan. 2, 1973 Appl. No.: 320,132  
 Inventor:  
 References Cited UNITED STATES PATENTS 1,101,548 6/1914 Hoffman 233/27 1,429,320 9/1922 Bouillon 233/15 X FOREIGN PATENTS OR APPLICATIONS 374,281 4/1907 France 233/27 Primary Examiner-George H. Krizmanich [57] ABSTRACT This invention describes an improved type of centrifu- 63 J T i: lilh /la 3* gal separator, which comprises a rotating assembly into which a mixture of fluids is introduced through the axis. The least dense component leaves the rotating chamber through the axis of the device, while the higher density component is thrown outwardly to the outermost radius of the rotating chamber. There are a plurality of orifices along the outer circumference of the chamber and means wherein the high velocity fluid is converted from high velocity to high pressure. Each of these velocity reducing means is connected by a spiral conduit to a chamber adjacent the axis of the rotating assembly. This chamber which carries the high density fluid component is connected to an outlet pipe and valve.  
 The spiral is designed, by its length and differing radii of the two ends, to provide a resultant force on the fluid from the velocity reducing means, causing a flow of high density fluid to the outlet of the system.  
 This centrifugal separator is novel in that the fluid is at all times entirely encased in the rotating assembly and differs from conventional systems in which the outlet of the higher density fluid from the rotating assembly is through openings into a static housing which surrounds the rotating chamber.  
 3 Claims, 4 Drawing Figures O 55 2a 7&#39; i 22 32 |||i|| llu.  
 PATENTED 3, 877, 635 sum 1 of 2 PATENIEUAPR 1 51975 sum 2 95 g CENTRIFUGAL sEPA AToR&#39; \WITII VELOCITY REDUCER BACKGROUND ,OF- THE- INVENTION This invention lies in the. field of apparatus for separating fluid component mixtures wherein two components are of differing density or specific gravity.  
  Public demand forecologically sound industrail operations and their translation into Federal and local statutes has increased the need for apparatus of this type for the purpose of separating chemical mixtures of liquids and/or gases, with or&#39;without entrained solids.  
  This invention provides a means for industry to effectively and efficiently clean and recycle various fluids, integral to their basic processes.  
  It is common knowledge that to separate components of a mixture of fluids which are of small differences of specific gravity or density, it is necessary to provide a high acceleration to the two components. This will provide a sizable differential force acting on each of the two components, to pull them apart and cause them to flow to separate outlets of the device.  
  In the prior art all devices of this type provide for a rotating assembly into which the mixture is inserted. This assembly has a short radius outlet and a large radius outlet for the lighter and heavier components of the mixture respectively. However, it has been universally the case that the large radius outlet empties into a stationary housing around the rotating assembly. This housing is at least partially filled with the fluid being separated &#39;l&#39;his fluid may include heavy viscous liquids, sludge. etc.. so that the friction between the rotating assembly and the liquid in the housing may be very high, and wasteful of energy.  
 SUMMARY OF THE INVENTION It is a primary object of this invention to provide a simple. unitary rotating assembly. of high operating efficiency. for the separation of liquid mixtures. gaseous mixtures and including solid particles.  
  It is a further object to provide a closed system in which various liquid mixtures can be introduced and continuously withdrawn. Examples of the many potential applications ofthis device are the separation of produced oil from water in oil producing operations; separating and discharging clean water while recovering oil being skimmed from the surface in oil spill cleanup operations; separating the solid matter from the liquid in slurry transportation systems, and so on.  
  These and other objects are realized and the limitations of the prior art are overcome in this invention by providing a unitary. closed rotating system into which fluid mixtures can be continuously introduced and out of which are provided two streams on a continuous ba sis. one containing the lighter fluid elements and the other containing the heavier or more dense elements of the mixture. By making the system a closed one. there is no need for the stationary enclosure normally utilized in the prior art devices. There is consequently a reduction-in the power loss due to friction between the rotating assembly and the static assembly through the medium of the fluid filling thelannular space.  
  The device comprises acentral shaft which is held fixed in separate posts. This shaft is drilled from each end along its axis and has radial ports drilled into the central opening near the middle of the shaft. The rotating assembly is mounted outside of and around the shaft with appropriate bearings and with seals to restrain the leakage of fluid from inside of the chamber at the low pressure of the input fluid. With the shaft stationary the rotating assembly is driven at high speed by means such as belts, so as to rotate at an adjustable high rate of rotation. The shape of the rotating assembly is substantially an ellipsoidal surface of revolution. Along the outer periphery of the chamber are a plurality of openings, which can be orifices, designed to exert a back pressure on the fluid in the chamber, which with rotation is thrown outwardly against the outer periphery of the chamber and through the orifices into velocity/pressure conversion elements. In these plurality of elements the high velocity fluid is brought to a reduced velocity and correspondingly its velocity energy is converted to pressure energy.  
  There are a plurality of spiral conduits connected to the velocity-to-pressure conversion elements. so that the fluid at high pressure now enters the spirals which are reduced in radius and eventually end at a radius only slightly larger than the radius of the shaft on which the rotating assembly is placed. The spiral is directed in the direction of rotation so that by its own inertia. fluid which enters into the open end at large radius of the spiral will be forced down the spiral to successively smaller radii until it empties into the annular chamber from which it is drawn off. i  
  The back pressure on the fluid in the rotating assembly is controlled either by means of the size of the orifices in the velocity reducing elements or by means of a valve in the output line from the annular chamber. This is the fluid which is drawn off at the outer radius of the chamber and carried by means of the spiral conduits to the outlet of the system. If there were no back pressure on the orifices at the outer portion of the rotating assembly. all the fluid would leave by those orifices and there would be no separation. By increasing the back pressure at the outlets it is possible to keep the inner volume of the rotating chamber completely filled, and therefore to effect separation.  
 BRIEF DESCRIPTION OF THE DRAWINGS form the spiral conduits.  
 DESCRIPTION OF THE PREFERRED EMBODIMENT FIGS. 1 and 2 show a vertical section taken from the side, and an axial view partly in section. The device, indicated generally by the numeral l0, constitutes at least two separate parts, a rotating chamber 12. which is used to separate and accelerate the fluid and a rotating spiral section. indicated generally by the numeral I4, which takes the highly accelerated fluid after being converted to a high pressure and brings it back to a small radius adjacent the outer surface of the stationary shaft.  
  The main support of the device is a shaft 16 which is supported in supports 52 and 54 mounted on steel legs 18 and base plate 19 as is well known in the art. The shaft 16 has drilled openings 32 and 38, one from each end, which proceed toward the center and leave a solid portion 35 of the shaft at the center. Radial ports 33 and 37 are drilled into the shaft to the central opening on either side of the solid portion 35. There is provision for fluid inlet 20 in accordance with the arrow 22 at one end and fluid outlet in accordance with the outlet pipe 23 and outlet arrow 24 at the outlet end.  
  The rotating assembly 12 comprises an ellipsoidal housing 26, which rotates about the outer surface of the stationary shaft. Seals are provided at 55 and 56 to prevent leakage along the shaft of the fluid mixture pumped in through the conduit 20, through the bore 32 and ports 33,-into the inner volume 34 of the chamber 26. The inside of .the chamber 26 has a plurality of somewhat radial; vanes 40, in the general arched shape shown in FIG. 1. These are shown better in FIG. 3 which indicates that,they are curved in the direction opposite to thedirection of rotation, as shown by the arrow 43. The purpose&#39;of the vanes is to provide a rotational drag on the fluid in the space 34 and cause it to be accelerated to the velocity of the rotating chamber. There area series of openings 41 in each of the vanes at the outer periphery of the inner surface which per- :mitsthe equalization of fluid and particularly of liquid,  
 thafmight be entrained in the vanes so that there will be a concentric distribution of such liquid to prevent outof balance operations. There is an annular disc construction 36 mounted on the shaft over the solid portion 3,5. This disc 36 is made to rotate with the chamber by means not shown. The purpose of the disc or diaphragm 36 is for controlling the flow of fluid which enters the space 34 through the openings 33, and to prevent the direct flow of such fluid out of the ports 37 without being thrown outwardly into the region of the vanes, so as to acquire the velocity of the rotating chamber.  
  When the inner space 34 of the chamber is filled with fluid and it is being rotated at high speed by means of belts running in the sheave 65 and driven by a suitable motor, the fluid in the space 34, will because of its high rotational speed be subjected to centrifugal forces. The less dense fluid component will be drawn toward the center and the higher density components will be driven toward the periphery. Thus the lower density component will pass through the ports 37, through the conduit 38 and out the pipe 23 in accordance with arrows 24. The high density fluid component will flow through a plurality of radial orifices 44 which are placed along the midline of the housing, and go into chambers 42 which are for the purpose of converting the high velocity fluid to a low velocity, high pressure fluid. These are velocity losers or velocity killer elements, which correspondingly build up the fluid pressure to a high value inside of the elements 42.  
  The fluid now has been separated. In the prior art devices the orifices 44 would lead to an annular space between the rotating chamber 26 and a static housing surrounding the device. However, this invention differs in that the high pressure fluid now in the elements 42 are carried by spiral conduits 48 from the outer diameter of the rotating assembly down to a minimum diameter at the end 64&#39;,&#39;as shown in FIG. 1, into an annular chamber 58 adjacent the shaft 16. The annular chamber 58 is connected by a plurality of ports 59 into a second chamber 60 which is stationary, from which the fluid flows through valve 62 in accordance with arrow 63.  
  It is thus seen that the spiral conduits provide a very useful purpose in carrying the high pressure, high density fluid component to a smaller radius where it can be conveniently withdrawn on a continuous controlled ba- SIS.  
  The spiral as shown in FIG. 2 is directed in the direction of rotation as shown by arrow 43. Thus the action of the spiral is to force fluid down the conduit because of its pressure differential and inertia. Even though the liquid entering the conduit 48 at each of the terminals 42 is high pressure, and is opposed by only a small component of centrifugal force effect on the fluid in the spiral conduit, the resultant action of the spiral is to provide an inclined plane down which the fluid is driven by differential pressure toward the center and to the outlet valve 62.  
  The purpose of the orifices 44 is threefold. The first is to provide a means by which the high velocity fluid in the chamber 34 can be directed against a plurality of orifices 47 where their direction is changed and the fluid is mixed. Here the velocity head of the fluid is reduced and the energy converted to a pressure head, which then communicates with a spiral conduit 48. The second purpose of the orifices is to provide a back pressure on the flow of fluid through the separator. For a single use, with a known mixture of fluids, a specific design and size of orifice could be determined to provide the optimum back pressure. However, it is possible to make the orifices larger so that their controlling back pressure is less and provide a control valve 62 by means of which the back pressure can be adjusted to any desired value. The third purpose is to provide replaceable orifices made of erosion resisting metal or ceramic to resist enlargement and wear caused by the extremely abrasive action of the high velocity fluids passing through said orifices.  
  The action of the spiral conduits 48 is indicated schematically in FIG. 4 where the fluid enters the conversion elements 42 through an orifice in accordance with arrow 53 and then into the conduit 48 and by the conduit through an outlet 64 into the chamber 58 adjacent the shaft 16. It is clear from the drawings in FIGS. 1 and 4 that the spiral is headed in the direction of rotation of the assembly.  
  While the use of six velocity conversion elements and correspondingly six spiral conduits have been shown, it is clear that any desired number can be used. Also, the shape of the housing 26 is shown as an ellipsoid of revolution. There can be a variety of shapes which will operate satisfactorily and any one of these can be used. It may be desirable in cases where a high value of acceleration is required, for example, to have one shape or another, so as to provide a minimum stress in the metal of the chamber 26.  
  By this simple unitary design which operates without the use of a static housing, high efficiency can be achieved and high speeds of revolution can be provided that will successfully separate fluid mixtures of a minimum differential density.  
  While the invention has been described with a certain degree of particularity it is manifest that many changes may be made in the details of construction and the arrangement of components. It is understood that the invention is not to be limited to the specific embodiments set forth herein by way of exemplifying the invention, but the invention is to be limited only by the scope of the attached claim or claims, including the full range of equivalency to which each element or step thereof is entitled.  
 What is claimed is:  
  l. A self-contained, single chambered, centrifugal separator, comprising:  
 a. a hollow stationary shaft means and means to support said stationary shaft;  
 b. a chamber in the shape ofa figure of revolution rotatable in bearings on and sealed about said stationary shaft, a plurality of spaced vanes inside said chamber, which are part of said chamber and independent of said shaft and means to rotate said chamber about said stationary shaft;  
 c. a plurality of peripheral openings spaced circumferentially about said chamber;  
 (1. means to introduce a fluid mixture, to &#39;be separated, through said hollow stationary shaft into the inside of said chamber at its smallest radius;  
 e. conversion means to accept fluid flowing out of said peripheral openings and to convert its velocity head to pressure head;  
 f. a plurality of conduits which are in the form of spirals which enclose the center of rotation of the device, directed at their outer ends in the direction of rotation of said chamber, respectively connected to said plurality of conversion means, said spiral conduits sealably connected at their inner ends to an annular collection chamber rotating as part of said chamber about said stationary shaft, said annular collection chamber forming the discharge of the high density fluid component, whereby said fluids are fully enclosed throughout their flow through said separator; and  
 g. means to remove the low density fluid component from said chamber at its smallest radius through said hollow stationary shaft.  
 2. A centrifugal separator comprising:  
 a. a hollow stationary shaft having axial openings bored from each end except for a selected length, at least two radial ports drilled through said shaft one to each of the inner ends of each of said axial openings, and means to support and clamp said stationary shaft;  
 b. a rotatable housing sealed in bearings so as to rotate about said stationary shaft, said drilled ports positioned inside said housing, a plurality of equally spaced vanes longitudinally arranged insidr of and part of said housing and rotating with saii housing;  
 c. means to introduce a fluid mixture to be separatet into one end of said stationary shaft and througl one of said axial openings and a first of said port: into the interior of said housing and to remove fluic from the second of said ports through the other 0 said axial openings in said stationary shaft;  
 (1. means to rotate said housing about said stationar shaft;  
 e. a plurality of radial orifices spaced equally abou the periphery of said housing leading to an equa plurality of velocity-to-pressure conversion mean: whereby the highly accelerated fluid inside saic housing will flow through said orifices into saic velocity-to-pressure conversion means;  
 f. an equal plurality of conduits which are in the forrr of spirals which enclose the center of rotation, fac ing at their outer ends in the direction of rotatior of said housing, connected respectively to said conversion means, the inner ends of said spiral conduits sealably connected to an annular collectior chamber rotating as part of said housing about saic stationary shaft; and  
 g. means to conduct fluid from said rotating annular collection chamber to an annular passage surrounding and part of said stationary shaft.  
 3. A self-contained, single chambered, centrifugal separator, comprising:  
 a. a rotatable ellipsoid-of-revolution-shaped chamber, a plurality of vanes spaced circumferentially about the inner periphery of said chamber;  
 b. means to rotate said chamber about a fixed hollow stationary shaft, and means to introduce a fluid mixture into said chamber and to remove fluid from said chamber through said hollow shaft and means to support and clamp said shaft in a stationary horizontal position;  
 c. a plurality of spaced orifices around the periphery of said rotatable chamber leading to a respective plurality of conversion means to convert velocity head to pressure head;  
 . a plurality of conduits which are in the form of spirals which enclose the center of rotation attached at their outer ends respectively to said conversion means and sealably connected at their inner ends to an annular collection chamber which rotates as an integral part of said rotatable chamber about said shaft, and means to conduct and control the flow of fluid out of said annular collection chamber.