Patent Publication Number: US-2005119103-A1

Title: Centrifugal separator

Description:
FIELD OF THE INVENTION  
      The present invention relates to a separator for separating separable constituents in a fluid.  
     BACKGROUND OF THE INVENTION  
      It is known to use a centrifuge to separate suspended particles in a liquid as well as insoluble liquids. Most centrifuges rely on batch operation whereby a quantity of liquid for separation is inserted in a centrifuge, the centrifuge rotated separating the constituents in the liquid, the centrifuge stopped and the separated constituents removed.  
      Alternatively a screen or filter is used whereby particles of a size greater than the screen or filter are trapped within the centrifuge and particles of a lesser size pass through the screen or filter and are thereby separated. The problem with this type of separator is that the screen or filter can become clogged or blocked and must be regularly cleaned. A screen or filter can also impede flow.  
      The present invention provides a new centrifugal separator that is able to be operated either on a batch or continuous basis and does not require a screen or filter that may become blocked.  
     SUMMARY OF THE INVENTION  
      According to the present invention, there is provided a centrifugal separator for separating separable constituents of a fluid to be separated, including:  
      a body rotatable about an axis, the body having a cavity therein;  
      a divider dividing the cavity into a first sub-cavity arranged for fluid to flow in a direction having a radial component and a second sub-cavity arranged for fluid to flow in a direction having a component that is towards the axis of rotation;  
      an inlet leading into the first sub-cavity at or near the axis of rotation of the body;  
      a first outlet in communication with a settling region of the cavity between or connecting the first sub-cavity to the second sub-cavity; and  
      a second outlet leading from the second sub-cavity at or near the axis of rotation of the body;  
      whereby in use, fluid to be separated enters the cavity via the inlet, rotation of the body and the fluid therein causes a centrifugal force to be applied to fluid flowing through the cavity, a first constituent of the fluid tends to collect in the settling region and a second constituent of the fluid tends to flow into the second sub-cavity, the second constituent in the second sub-cavity exits the cavity via the second outlet and the first constituent collected in the settling region exits the cavity via the first outlet.  
      Preferably a third sub-cavity connects the settling region to the first outlet. The third sub-cavily is arranged for fluid flow in a direction having a component that is towards the axis of rotation of the body. In a first embodiment, the first outlet is at or near the axis of rotation. Preferably the third sub-cavity is separated into a plurality of chambers by dividing walls, with each chamber extending towards the axis of rotation.  
      Preferably the size of the cavity decreases radially from the axis of rotation. Preferably the divider is shaped such that the shape of the first sub-cavity increases along the path of flow of fluid though the first sub-cavity. Preferably the size of the second sub-cavity decreases along the path of flow of fluid through the second sub-cavity. Preferably the divider is shaped to space the first sub-cavity from the second sub-cavity.  
      Preferably the first sub-cavity is provided with a plurality of radially extending fins. Preferably the first sub-cavity is divided into a plurality of chambers by the fins. Preferably the second sub-cavity is provided with a plurality of radially extending second fins. Preferably the second sub-cavity is divided into a plurality of chambers by the second fins. Preferably each first fin is integrally formed with a corresponding one of the second fins.  
      Preferably the separator includes a drive means for rotating the body. Preferably the speed of rotation of the body is controlled, whereby the extent of separation of the constituents can be controlled.  
      Preferably the separator includes a means for controlling the rate of flow of fluid to be separated in through the inlet. Preferably the separator includes a means for controlling the rate of flow of fluid from the first outlet. Preferably the separator includes a means for controlling the rate of flow of the fluid from the second outlet.  
      Preferably a shaft extends through the axis of rotation, the body arranged to be rotated by rotation of the shaft. Preferably the shaft extends through the body.  
      In a second embodiment, the settling region includes a collection region for holding the collected first constituent until it is removed via the first outlet. Preferably the collection region is spaced from the axis of rotation.  
      Preferably the body is substantially disc shaped. Preferably the body includes a first part and a second part. In a third embodiment, the parts are in the form of discs. Preferably the discs are separable. Preferably the first outlet is provided by a gap between the body parts when the parts are separated. Preferably the size of the gap is adjustable.  
      Preferably the divider is in the form of a radially extending planar disc. In one variation a circumferential region of the divider includes a first flange extending transversely to a radial line extending from the axis of rotation. Preferably the circumferential region includes a second flange extending transversely to the radial line from the axis of rotation and at an angle to the first flange greater than the angle of the first flange to the divider.  
      Preferably the inlet is provided with a raceway. Preferably the first outlet is provided with a raceway.  
      Preferably the separator includes a first collection means for collecting the first constituent as it exits the first outlet. Preferably the separator includes a second collection means for collecting the second constituent as it exits the second outlet.  
      In another variation, the collection region is contained within a bulb shaped portion of the body.  
      Preferably a separation zone precedes the collection region in the course of flow of fluid. Preferably the separation zone is divided into an inner separation zone and an outer separation zone by a parting means. Preferably the parting means is a circular knife. Preferably the collection region follows the outer separation zone in the course of flow of the fluid. Preferably a third outlet leads from the inner separation zone. Preferably the separator includes a third collection means for collecting the constituents exiting the third outlet.  
      Preferably the inlet extends the inside of the shaft. Preferably the second outlet extends into the inside of the shaft. Preferably the third outlet extends into the inside of the shaft.  
      Preferably the first outlet is closed and sealed by a seal in the gap between the parts of the body when the gap between the parts is closed. More preferably the first outlet is open when the gap between the parts is opened. Alternatively the gap is in communication with a valve/seal means. Preferably the first outlet is unsealed and open when the gap between the parts is moved to be partly closed. More preferably the first outlet is closed and sealed by the seal means when the gap between the parts is opened.  
      In the present specification, the term “fluid to be separated” is to be understood to mean an emulsion, suspension, mixture, or the like of constituents such as liquid and gas, liquid and liquid, gas and solid particles, liquid and solid particles, solid particles and solid particles, gas and gas or combinations thereof where the constituents are to be separated from one another. Typically, the constituents will be immiscible.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      In order to provide a better understanding, a preferred embodiment of the present invention will now be described, in detail, by way of example only, with reference to the accompanying drawings, in which:  
       FIG. 1  is a cross-sectional side elevation of a centrifugal separator in accordance with the present invention;  
       FIG. 2  is a cross-sectional view of the section  2 - 2  of the separator of  FIG. 1 ;  
       FIG. 3  is a cross-sectional view of the section  3 - 3  of the separator of  FIG. 1 ;  
       FIG. 4  is an enlarged cross-sectional side elevation of a top portion of the separator of  FIG. 1  showing an upper bearing;  
       FIG. 5  is an enlarged cross-sectional side elevation of a portion of  FIG. 1  showing a lower bearing;  
       FIG. 6  is a cross-sectional side elevation of a preferred embodiment of the separator of the present invention;  
       FIG. 7  is a cross-section side elevation of a lower section of the separator of  FIG. 6 ;  
       FIG. 8  is a plan view of the section A-A of  FIG. 6  showing the lower section of  FIG. 7 ;  
       FIG. 9  is a cross-sectional side elevation of an upper section of the separator of  FIG. 6 ;  
       FIG. 10  is a plan view looking from the section B-B of  FIG. 6  of the upper section of  FIG. 9 ;  
       FIG. 11  is a cross-sectional view of a first set of paddles of the separator of  FIG. 6 ;  
       FIG. 12  is a cross-sectional view of a divider of the separator of  FIG. 6 ;  
       FIG. 13  is a cross-sectional view of a second set of paddles of the separator of  FIG. 6 ;  
       FIG. 14  is a part cross-sectional side elevation of an alternative separator in accordance with the present invention;  
       FIG. 15  is a part cross-sectional side elevation of a further alternative separator in accordance with the present invention;  
       FIG. 16  is a part cross-section side elevation of yet another alternative separator in accordance with the present invention;  
       FIG. 17  is a side elevation of a separator housed in a chassis for use;  
       FIG. 18  is a cross-sectional side view of a separator mounted on a jack within the chassis of  FIG. 17 ;  
       FIG. 19  is a part cross-sectional side elevation of the separator of  FIG. 6  in use;  
       FIG. 20  is a part cross-sectional side elevation of yet another alternative separator in accordance with the present invention;  
       FIG. 21  is a cross-sectional side elevation of a further embodiment of a separator in accordance with the present invention;  
       FIG. 22  is a part cross-sectional side elevation of the separator of  FIG. 21 ;  
       FIG. 23  is a part cross-sectional side elevation of the separator of  FIG. 21 , with an alternative seal of an outlet;  
       FIG. 24  is a part cross-sectional side elevation of the separator of  FIG. 21 , with another alternative seal of the outlet, in a closed configuration; and  
       FIG. 25  is a part cross-sectional side elevation of the separator and seal of  FIG. 24 , with the outlet in an open configuration. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      Referring to  FIG. 1 , there is shown a separator  10  which includes a body  12  coupled to or integrally formed with a shaft  14 . The body  12  and shaft  14  are rotatably mounted to a frame  16 , with the shaft aligned with the axis of rotation.  
      The body  12  includes a first part  18  and a second part  20  secured together by bolts  19 . Inside the body  12  is a cavity  22 , notionally divided into a first sub-cavity  24  and a second sub-cavity  26  by a first divider  28 , and a third sub-cavity  38  by a second divider  30 . The first sub-cavity  24  is regarded as a part of the cavity  22  having a radially extending component. The second sub-cavity  26  is regarded as a part of the cavity  22  having a directional component towards the axis of rotation of the body  12  through which some of the separated fluid flows. The third sub-cavity  38  is regarded as a part of the cavity  22  also having a directional component towards the axis of rotation of the body  12  through which the rest of the separated fluid flows. Fluid will generally be travelling in a direction having a radial component when it is within the first sub-cavity  24  and in a direction having a component towards the axis of rotation when it is within the second sub-cavity  26  and third sub-cavity  38 . Either between or coinciding with the first sub-cavity  24  and the second sub-cavity  26 , is a settling region  34  that leads to a first outlet  52  via the third sub-cavity  38 . The second sub-cavity  26  leads to an outlet  50  in line with the axis of rotation. Outlet  52  from the body is close to the axis of rotation.  
      An inlet  58  into the cavity  22  (and to the first sub-cavity  24 ) coincides with the axis of rotation.  
      The peripheral surfaces of the first and second sub-cavities  24  and  26  are somewhat conical and slope through the settling region  34  towards an entry to the third sub-cavity  38 . This allows heavier constituents to flow down the slopes to the entry.  
      The divider  28  is shaped to minimise turbulence within the cavity  22  and to provide an expanding cross-sectional area as fluid flows through the first sub-cavity  24 . These features encourage settling within the settling region  34  as fluid travels through the separator  10 . The divider  28  is also shaped to provide a narrowing cross-sectional area as fluid travels through the second sub-cavity  26  towards the axis of rotation, which also encourages settling.  
      A plurality of fins  32  and  36  are provided in the first and second sub-cavities  24  and  26 . These fins  32  and  36  are preferably integrally formed such that a single fin  35  forms first  32  and second  36  fins within the first and second sub-cavities  24  and  26 , respectively. The fins  35  are shown extending radially in  FIG. 2 . The fins  35  partition the first sub-cavity into a plurality of first channels  70  and the second sub-cavity into a plurality of second channels. They also impart rotational velocity to fluid travelling through the first sub-cavity  24  while also further minimising turbulence of the fluid by reducing slip in the fluid. When the fluid enters the second sub-cavity  26 , the fins  35  recover the rotational velocity of the fluid passing through the second channels thereby conserving energy. As a result, a large portion of the energy required to rotate fluid at a high rotational velocity is recovered, so that the overall energy required to be input is less than would be required by a screen or filter centrifuge.  
      The third sub-cavity  38  is formed of a plurality of passageways  72  in between islands  74 . Each of the passageways  72  is able to recover rotational energy imparted as the constituent flows through the third sub-cavity  38  to the first outlet  52 . This further contributes to the conservation of energy.  
      The shaft  14  is coupled to a spindle  44  around which a belt can be placed. A motor rotates the belt and thus the separator  10 .  
      Referring to  FIG. 4 , the shaft  14  and upper portion of the body  12  is rotatably coupled to a top member  62  of the frame  16  by bearings  46 . The top member  62  is spaced from a bottom member  64 . Separating the top member  62  and bottom member  64  is a cylindrical cage member  66  which provides a protective barrier around the rotating body  14 . The rotating body  14  can be rotating at high velocities. The frame  16  is not only used for mounting purposes, it is also used for safety purposes. The inside of the cage member  66  my be lined with a thermally resistant material, which may act as a break if the body broke free.  
      Referring to  FIG. 5 , a bottom of the separator body  12  is coupled to the bottom member  62  by a bearing  48 .  
      The divider  28  may be formed of a very lightweight material so that it has a specific gravity less than the fluid flowing through the separator  10 . This will urge the divider  28  to remain in-line with the axis of rotation of the body  12 . The cavity  22  can be formed by molding the shape of the inside of the body  12  to the desired shape of the inside of the cavity  22 . Preferably the shape will be molded from a material  40  and  42  having a specific gravity greater than the fluid to be separated.  
      The method of use and operation of this embodiment of the present invention will now be described with reference to the accompanying drawings.  
      The fluid to be separated contains at least a first constituent and a second constituent. The fluid to be separated enters the inlet  58 . A swirl device may be provided at the inlet  58  to provide the fluid to be separated with an initial rotational impedus. The fluid to be separated is divided by a point  60  of the divider  28 . The fluid to be separated travels substantially radially at first within each of the passages  70  between the first fins  32  where it increases in rotational velocity as it moves radially through the first sub-cavity  24 .  
      The fluid to be separated then enters an expanding portion of the first sub-cavity  24 . Due to centrifugal force applied to the rotating fluid to be separated, a high artificial gravity is experienced by the fluid to be separated. Due to the artificial gravity and assisted by the turbulence minimising features described above, particles of a higher specific gravity will tend to move along the peripheral surface in the settling zone  34 , into the entry to the third sub-cavity. Particles with a higher specific gravity are regarded as the first constituent and will tend to congregate and move towards the extreme most radial perimeter within the settling zone, ie. the entry to the third sub-cavity. The second constituent with a lesser specific gravity will tend to “float” towards the axis of rotation. This second constituent then moves into the second sub-cavity  26  and travels through the second channels between the fins  36  moving closer towards the axis of rotation. The first constituent enters the opening of the passageways  72  in the third sub-cavity and travels through passages  72  back towards the axis of rotation. As the first constituent and the second constituent travel towards the axis of rotation, rotational energy is recovered by fins  26  or islands  74 . The first constituent then exits the first outlet  52  and travels into a pipe  56  where it is then taken away. The second constituent exits the separator by the second outlet  50  where it travels through pipe  54  and is then taken away.  
      The fluid to be separated is preferably pressure fed into the separator  10  to assist in the flow through of the constituents. In particular, the separated first constituent can become highly viscous or paste-like depending on its nature, so pressurisation assists to avoid clogging. In addition, suction could be applied to the outlet  52 .  
      Depending on the speed of rotation, the degree of separation of the constituents can be controlled. Furthermore, separated second constituent exiting pipe  54  can be recycled through the separator or another separator to remove a further amount of first constituent, if any, remaining in separated fluid. Equally, the separated first constituent could be recycled to further refine the degree of separation.  
      Furthermore, depending on the amount of first constituent in the fluid to be separated, the size of the first and second sub-cavities and settling region may be varied accordingly. If only a very minor amount of second constituent is to be separated, the size of the passages  72  can be diminished so that this passageway does not become flooded with the first constituent.  
      Additional control can be provided by controlling the flow of fluid to be separated entering the inlet  58  by using for example a valve. Controlling the flow of separated fluid including the second constituent exiting by the pipe  54  can be controlled such as by using another valve. Furthermore, separated first constituent exiting by pipe  56  can also be controlled by, for example using yet another valve. Using these various control mechanisms, the degree of separation of constituents in the fluid to be separated can be further controlled.  
      Referring to  FIG. 6  there is shown another embodiment of the present invention, with a separator  110  which includes a body  112  rotatably mounted to a shaft  114 . Preferably the shaft  114  is split into a first section  138  and a second section  140  with a gap  142  between the two section  138  and  140 . Furthermore the shaft is preferably hexagonal in cross-section so as to be keyed with receiving coupling collars  152  and  154  of the body  112 .  
      The body  112  is formed of a first part in the form of a disc  172  and a second part in the form of a disc  158 . The discs  172  and  158  taper towards one another along a radial line extending from the shaft  114 . The disc  172  is fixably, slidably coupled to the shaft section  138  by coupling collar  152 . The disc  158  is fixably, slidably coupled to the shaft section  140  by coupling collar  154 . A cavity  116  is provided within the body  112  between the discs  172  and  158 . Extending into the cavity  116  from the coupling collar  152  is a divider  118  in the form of a planar disc having a circumferential edge tapering to a point. The tapering of the first and second discs also causes the cavity  116  to taper radially away from the shaft  114 . The divider  118  divides the cavity  116  into a first sub-cavity  120 , and a second sub-cavity  122 , with a collection region  124  joining the first sub-cavity  120  to the second sub-cavity  122 . The collection region  124  commences from the circumferential edge of the divider  118 .  
      An inlet  126  is provided into the first sub-cavity  120 . The inlet  126  may by in the form of a raceway into which a pipe can extend to insert fluid to be separated into the separator  16 . Other forms of inlet may be provided as would be suitable for the particular application of the separator  110 . One alternative is described below in relation to FIGS.  21  to  25 .  
      A first outlet  130  leads from the collection region  124 . The outlet  130  is provided by a gap between each of the discs  172  and  158 . A second outlet  128  leads from the second sub-cavity  122  out of the body  114  of the separator adjacent the shaft  114 .  
      It is preferred to have the circumferential edge of the divider  118  as far away from the shaft  114  as possible. Although, the distance of the edge from the outlet  130  may provide a method of controlling the amount of separation occurring.  
      Referring to  FIGS. 7 and 8 , a lower part  146  of the separator  110  is described in more detail. The second section  140  of the shaft  114  can be seen extending through coupling collar  154 . Extending upwardly from the coupling collar  154  is another collar  166 . The inside surface of the collar  166  is spaced from the second shaft section  140  to form a socket  174 . Within an inside surface of the second disc  158 , near the shaft  114 , is an annular funnel  170 . The funnel  170  extends underneath the collar  166  and leads to a plurality of channels  164  that form the second outlet  128 . Radially extending from the collar  166  are a plurality of baffles  150  (similar to the fins of the previous embodiment). Each of the baffles  150  tapers along its length away from the shaft  114  so as to conform with the inside surface of the second disc  158 . Each of the baffles  150  is fixed to the second disc  158  by grub screws  160 . At a perimeter of the second disc  158  is a raised portion having a surface  168 . The surface  168  is perpendicular to the length of the shaft  114 . A corresponding surface  180  is provided on the first disc half  172  as shown in  FIG. 9 . An O-ring  162  extends around the raised portion so that it protrudes from the surface  168  and is recessed within the raised portion.  
      Referring to  FIGS. 9 and 10  an upper part  144  of the body  112  is shown. A first section  138  of the shaft  114  is shown coupled to the coupling collar  152 . The shaft section  138  extends part way through the inside of the collar  152 . A shaft socket  182  formed in the lower part of the collar  152 . The shaft socket  182  is for receiving a portion of the second shaft section  140  that protrudes past the second half  146  of the body  112  as mentioned in relation to  FIG. 8 . When the first half of the body mates with the second half of the body a separation gap  142  is provided between each of the shaft sections  138  and  140 . A gap is also formed at the first outlet  130  between surfaces  168  and  180 . The degree of insertion of the second shaft section  140  into the shaft socket  178  can be adjusted, which determines the size of the separation gap  142 , the size of the second sub-cavity  122  and importantly the distance between the surfaces  168  and  180  and thus the size of the first outlet  130 .  
      Coupled to the socket section of the coupling collar  152  is the divider  118 . A diverter  178  is attached to the coupling collar  152  for diverting fluid to be separated into the first sub-cavity  120  through the inlet  126 . A series of holes  186  extend into the diverter  178  for attaching the divider  118  by grub screws  160 . Extending between the first disc  172  and the divider  118  are a series of radially extending baffles  148 . The baffles  148  have holes  186  for receiving grub screws  160  to attach to the divider  118  and the first disc  172 .  
      The baffles  148  are shown in isolation in  FIG. 11 , with each baffle  146  being shaped to sit between the first disc  172  and the divider  118 . A curved edge  188  is shown. The curved edge  188  minimises turbulence in the fluid to the separated as it enters through the inlet  126 .  
      The divider  181  is shown in isolation in  FIG. 12 . The circumferential edge  184  is indicated. A hole  190  is for the divider  118  to slide over the coupling collar  152 .  
      A set of second baffles  150  is shown in  FIG. 13  attached to the collar  166 , which has a hole  192  within forming the socket  76  and for receiving the coupling collar  154 .  
      Referring to  FIG. 17  an example of an assembly for operating the separator  110  is shown. The assembly includes a frame  220  within which is housed the separator  110 . The separator  110  is orientated so that the shaft  114  extends vertically with the inlet  126  situated above the second outlet  128 . It is noted that the separator need not operate in that orientation, although it would generally be preferred to operate in this orientation. The separator shaft  114  is mounted to the frame  120  by a bearing. A pulley or spindle  230  is coupled to the shaft  114 . The bottom of the shaft  14  sits on a thrust bearing which in turn sits upon a jack  228 . The jack assembly  228  is able to raise the second section  140  of the shaft and thus alter the size of the separation gap  142  and thus the distance between the first half  144  of the body in relation to the second half  148  of the body and in particular the gap that forms the first outlet  130 . The pulley or spindle  230  is connected via a drive belt  232  to another pulley  230  mounted on the end of a motor  222 . Accordingly the motor  222  is able to rotate the shaft  114  and thus the body  112  of the separator  110 . Controlling the speed of the motor controls the rotation of the separator  110 . A feed tank  224  feeds fluid to be separated into the separator into the inlet  126  of the separator  110  via a pipe  226 . A collection means (not shown) is provided at each of the outlets.  
      It will be appreciated that a variety of assemblies may be used, depending upon the particularly application of the separator.  
      Referring to  FIG. 18 , the jack assembly  228  is shown in more detail. It can be seen that the second section of the shaft  140  has a spigot projecting into a thrust bearing  240 . A roller bearing  242  provides additional stability to the shaft section  140 . A mounting plate  245  houses the bearings  240  and  242 . The mounting plate  245  sits on a column  248 , which is slidable within a sleeve  246 . The sleeve  246  is coupled to a base  254 , which is in turn bolted to the frame  220 . A threaded extendable/retractable member  250  of a jack is able to raise or lower the column  248  within the sleeve  246  by rotating a crank coupling  252  (using a cranking handle) geared to the member  250 . A collection means  244  extends from a top of the mounting plate  245  to collect fluid exiting the second outlet  128 . It can be seen that if the shaft section  138  is not permitted to move vertically then the adjustment of the jack will cause the shaft section  140  to move relative to the shaft section  138 , which in turn adjusts the distance between the first part  144  and second part  146  of the separator and in particular adjusts the gap which forms the first outlet  130 .  
      Also in this figure, it can be seen that the baffle  148  extends further towards the collection region  124  than the baffle  148  shown in  FIG. 6 . Also in this embodiment minor variations are made to the collar  166 .  
      Referring to  FIG. 19 , the method of use and operation of this embodiment of the present invention is described. Fluid to be separated enters the inlet  126  of the separator  110  from pipe  226 .  
      The shaft  114  is rotated as indicated by the arrow C. Fluid entering the cavity encounters baffles  148  and is imparted with rotational momentum as the fluid moves towards the collection region  124 . The baffles  128  impart angular velocity to the fluid and serve to reduce turbulence in the fluid, which otherwise slips against the rotating body and shears causing turbulence. As the fluid reaches the end of the divider  118  particles entrained within the fluid have centrifugal force exerted on them and tend to collect in the collection region  124  under what is in effect high artificial gravity. The particles tend to settle over the first outlet  130  within the collection region  124 . Depending on the operation required, the particles are collected or allowed to exit the separator via the outlet  130  continuously or in batches. Fluid is more readily able to make a sharp turn around the circumferential edge of the divider  118  and travel into the second sub-cavity  122 . Fluid tends to do this rather than particles due to the high centrifugal forces which cause particles (or fluid) having a higher specific gravity to settle in preference to fluid or other particles having a lower specific gravity. It is also noted that in the collected region  124  it is desirable to keep turbulence to a minimum to allow the specific gravities to sort the particles and fluid.  
      Under the influence of normal gravity or back pressure or suction, fluid having a lower specific gravity tends to move through the second sub-cavity  122  past the baffles  150  towards the outlet  128 . As the fluid substantially devoid of particles moves towards the shaft it releases rotational energy to the baffles  150  so that energy is conserved by the separator and fluid exiting the second outlet  128  is less turbulent. Fluid is then able to exit the second outlet  128  where it is collected by a collection means  244 . The collection means  244  may simply be in the form of an annular cup, which drains via a pipe  260 .  
      With a continuous flow of fluid to be separated into the separator, continual depositing of particles occurs. Particles collecting in the collection region  124  are compressed together and slowly moves through the outlet  130 .  
      Smaller particles will tend to displace fluid between larger particles as they settle. The displaced fluid improves lubricity between particles and effectively jostles them further assisting the compacting process. The gap between the surfaces  168  and  180  controls the size of the outlet  130  and thus the rate at which particles can exit. Generally this gap will be very small. Particles may be in a thick paste like state with minimal fluid and will ooze through the outlet  130 . It is important to control the rate of outlet of the particles through the outlet  130  to minimise turbulence within the collection chamber  124  and allow settling of the particles. This may require the size of the separation gap  142  being varied through phases to allow adequate collection of particles before their release through the outlet  130 . Once released due to the high centrifugal force exerted on the particles they will tend to fly free where they may then be collected within a C-shaped annular collection means  262  and then drained by an outlet pipe  264  or be disposed of in some other manner.  
      In some instances the particles are to be kept and the fluid is to be discarded and in other instances the particles discarded and the fluid is kept and in yet other cases both the fluid and particles are kept depending on the application of the separator. The output of the first and second outlets can be dealt with appropriately.  
      It is noted that when describing the operation of the separator the term “particles” is used to refer to solids, liquids or gasses that have higher specific gravity or higher settling velocity than the other constituent of the fluid to be separated, which may also be a solid, liquid or gas. In some instances there may also be a carrier fluid, particularly where solid particles are to be separated from other solid particles each having different specific gravities or particle sizes. It is noted that separation can be conducted by specific gravity or by particle mass or by particle size. The speed of rotation of the separation is believed to control the type and rate (effectiveness) of separation. The flow rate of fluid into or out of the separator can also be controlled, which can also control the rate of separation.  
      Referring to  FIG. 14 , another alternative collection means  204  is shown in schematic form. The collection means  204  is in the form of a member  194  which is a grotesque J-shape in cross section. The member is coupled to the outside of the second disc  158  by grub screws  202 . A gap  196  is provided between the outlet  130  and the member  194 . Also, the gap  196  extends around the back of the J and is curved to leave a gap  200  between the member  194  and the disc  172 . This allows particles that have exited the outlet  130  to collect within the gap  196  and build up. The gap  196  can then be drained via a raceway.  
      Referring to  FIG. 15 , another schematic variation of a collection means is shown. In this embodiment, the member  194  is affixed to the disc  172  by the grub screws  202 . Particles that have exited the outlet  130  accumulate in the gap  196 , where they accumulate and flow down the back  198  of the J member  194  and then drip under the influence of gravity into a collection tray.  
      Referring to  FIG. 16 , an alternative separator is shown with an enlarged collection region  214 . In this case the discs  172  and  158  together have a bulb portion  108 . The inside of the bulb portion  208  serves to enlarge the collection region  214 . In addition, the divider  118  is provided with a first flange  210  and a second flange  212  which extend in opposite directions at an angle of approximately 60° to the plane of the remainder of the divider  118 . Both flanges  210  and  212  provide a fork-like appearance to the circumference of the divider  118 . Each of the flanges  210  and  212  end in a ridge, around which the fluid to be separated must travel. This assists in separation of the particles from the remainder of the fluid. It can therefore be seen that fluid entrained with particles  132  that enters the inlet and is then subjected to centrifugal force by the separator tends to have particles  136  collect within the larger collection region, which tapers towards the second outlet  130 . Fluid substantially devoid of particles  134  may then leave via the second outlet. This apparatus can assist where the specific gravity of the particles is similar to the fluid and where the particles would tend to float within the collection region rather then being separated according to their specific gravity. In this case they have a greater time to dwell in the collection region and can therefore clump together. Clumping tends to reduce their tendency to float or hover in the collection region  124 . They will therefore effectively “sink” into the mass of the rest of the particles which will then tend to continue to compact them together as they move towards the outlet  130 .  
      Increasing the size of the collection region  24  can affect the time particles have to settle. This therefore provides a means of controlling the particle settling time.  
      Referring to  FIG. 20 , an alternative to the separator of  FIG. 16  is shown. In this case, the outlet  130  is covered by member  194 , J shaped in cross section, which loops over to overlap with a lip  195  on the other side of the outlet  130 . The overlapping of member  194  has the advantage of providing a seal between the inwardly extending part  198  of the member  194  and the lip  195  when the upper and lower parts are separated somewhat. In some cases, particularly when the speed of rotation is great (or the diameter of the discs are large) hydrostatic forces can force the seal  162  to fail. In this case the forces pressuring the discs to part only serve to assist in sealing between  195  and  198 .  
      The build up of collected particles  136  can be released in batches, either via outlet  130  or by flushing out of outlet  164 .  
      It can be advantageous to seal the inlet and outlets from the atmosphere so that the cavity is completely full of fluid in use. Pressurising the fluid flow can further assist this.  
      Referring to  FIG. 21 , there is shown another embodiment, separator  110 ′. The separator  110 ′ has many similar features to the separator  110 . Like numerals represent like features. The following description concentrates on the differences between separator  110  and separator  110 ′. Separator  110 ′ includes a body  112  rotatably mounted to a shaft  114 . Shaft  114  is split into a first section  138  and a second section  40 . The majority of the body  112  is disposed between the two section  138  and  140 .  
      The body  112  is formed of a first bowl shaped disc  172  and a second planar disc  158 . A part of the disc  172  tapers towards disc  158 . The disc  172  is coupled to the shaft section  138 . The disc  158  is coupled to the shaft section  140 .  
      A cavity  116  is provided within the body  112  between the discs  172  and  158 . Extending into the cavity  116  is a divider  118  in the form of a thick planar disc having a tapering circumferential edge substantially parallel with the tapering part of the disc  178 . The divider  118  divides the cavity  116  into a first sub-cavity  120 , and a second sub-cavity  122 , with a collection region  124  joining the first sub-cavity  120  to the second sub-cavity  122 . A second divider  285  extends radially from the axis of rotation between the first divider  18  and the second disc  158 . A third cavity  284  is provided between the first divider  118  and the second divider  285 . The second cavity  122  is defined by the void between the second divider  285  and the disc  158 .  
      An inlet  126  is provided into the first sub-cavity  120  from a pipe or channel  260  within the inside of the shaft section  138 . A separation zone  125  is defined between the commencement of the tapering circumferential edge of the divider  118  and the second disc  158 . A first outlet  130  leads from the collection region  124 . The outlet  130  is provided by a gap between each of the discs  172  and  158 . The outlet is shown to be closed by a seal  286 . A second outlet  128  leads from the second sub-cavity  122 . The outlet  128  is formed by a sleave  165  over the shaft section  140 . A third outlet  274  leads from the third cavity  284 . The third outlet is in the form of tube or channel extending through the inside of the shaft section  140 . An entry  281  to the third cavity  284  leads from the separation zone  125 . The second divider  285  includes a parting means in the form of a circular knife  270 . The knife  270  has a blade tip  278  pointing towards the direction of flow of fluid in the collection region  116 . This will part the flow of fluid, with fluid closer to the axis of rotation entering the third cavity  284 , through the entry  281 , and fluid further away from the axis of rotation entering the second cavity  122  or collection region  124 .  
      The position of the blade tip  278  can be moved by placing more or less circular shims  280  between the knife  270  and the planar body of the second separator  285 .  
      The second disc  158  is fixed in relation the first disc  172 . An A-frame (in cross-section) support  262  is longitudinally movable in relation to the shaft  114 . The support  262  abuts a thrust washer  266  which in turn abuts an internally threaded collar  264 . The collar  264  is akin to a nut that screws onto a threaded bolt, with the equivalent of the bolt being an external thread  268  located on the sleave  265 . By rotating the collar  264  the position of the support  262  and thus the disc  158  may be altered. Alternative means for moving the support  262  can be provided as appropriate. Such alternatives may include mechanised or hydraulic means that can move the support  262  while the separator  110 ′ is rotating.  
      Extending between the first disc  172  and the divider  118  are a plurality of radially extending baffles or fins  148  that follow the contour of the first cavity  120 . Extending between the first divider  118  and the second divider  285  are a plurality of radially extending baffles or fins  272  that follow the contour of the third cavity  284 . Extending between the second divider  285  and the second disc  158  are a plurality of radially extending baffles or fins  150  that follow the contour of the second cavity  122 .  
      Referring to  FIG. 22 , in use particles under the influence of centrifugal forces are driven towards the inside surface of tapered portion of the first disc as they travel through the separation zone  125 . The particles  292  are shown collecting the in the collection region  124 . In this embodiment the separator is configured to collect particles in a batch mode. Once enough particles are collected in the collection region, or the batch of fluid has been processed, the outlet  130  may be opened to allow the particles to be removed. The flow of fluid from the second outlet  128  can be used to detect the filling of the collection region  124 .  
      The seal of the outlet  130  is in the form of a circular sealing member  286  that is coupled to the perimeter of the second disc  158  by a flexible bridging member. The sealing member  286  is coupled to the support  262 . The sealing member  286  may be inserted in a circular recess  288  provided in outer end region of the first disc  172  by moving the support  262 . In doing so, the bridging member will flex. The sealing member  286  may be in the form of a reinforced rubber ring having an oversized insert  290  at the inner edge of the bridging member for threading in a keyway of the second disc  172 . The ring may be fixed to the support  262  by an adhesive and or mechanical means. The sealing member  286  forms a seal at the outlet  130  when inserted in the recess  288 .  
      Referring to  FIG. 23 , an alternative form of outlet  130  is shown. The seal of the outlet is in the form of a flexible, resilient, member  294  coupled to the second disc  158 . The member  294  normally extends substantially parallel to the second disc  158 . The member  294  has a head  296 . A correspondingly shaped (semi-circular in cross-section) recess  298  is provided in the end region of the first disc  172 . The support  262  includes a positioning tip  300 . When the support  262  is moved towards the second disc  158 , the tip  300  engages with and pushes the member  294  towards the recess  298 . This closes the outlet  130  until the head  296  is tightly pushed into the recess  298 , whereupon the outlet  130  is sealed. If the support  262  is moved away from the second disc  158 , pressure on the head is released and the seal ends. The outlet opens as the member  294  returns to its normal position. Any particles settled in the collection region  124  may be removed. If the particles are tightly packed they may not be inclined to exit. The passage  302  through the outlet  130  may be tapered to expand in volume radially to assist in removal of collected particles.  
      Referring to  FIGS. 24 and 25 , another alternative form of outlet  130  is shown. The seal of the outlet is also in the form of a flexible member  308  that extends between the second disc  158  and a circular flange  304 . The flange  304  extends from the support  262  toward the first disc  172 . A backing member  306  supports the back of the member  308  when the outlet is closed. The backing member  306  is in the form of an inclined ring fixed to the support  262  and flange  304 . A circular recess  288  provided in outer end region of the first disc  172  for receiving tip of the flange  304 . A surface  310  is angled to abut the member  308  when the outlet is fully closed to form a seal between the first disc  152  and the member  308 .  
      As the support  262  is moved towards the second disc  158 , the tip of the flange  304  engages with recess  288 . This closes the outlet  130  with the member  308  providing a seal. The member  308  is supported by the backing member  308 . If the support  262  is moved away from the second disc  158 , the flange  306  parts from the recess  288 , the backing member  306  parts from the back of the member  308  and the member  308  moves away from the surface  310 . The outlet opens as the member  308  continues to move away from the surface  310 . Any particles packed/settled in the collection region  124  may be removed. The passage  302  through the outlet  130  is tapered to expand in volume radially to assist in removal of collected particles.  
      The inner layer of fluid parted by the parting means  270  may not be totally devoid of particles. If this is the case particles may be inclined to settle if the dwell time of the fluid flow is sufficient, such as in places where the flow is subject to eddying. In  FIG. 21  on the right hand side the parting means  270  provides a sharp bend in the passage into the third cavity  284 . On the left hand side the drawing is modified to show an arrangement to stop settling of particles from the fluid that has been parted from the rest of the fluid flow. If particles were allowed to settle, then the build up could provide clogging or blockage of the flow. The arrangement to prevent settling of particles here is shown in more detail in  FIG. 24 .  
      At a bend  283  in the passage between the outermost circumferential tip of the first divider and the parting means  270 , the passage is narrowed by providing a curved surface  282  of the parting means  270  closer to the first divider  118  than the gap between the knife tip and the divider  118  and the thickness of the third cavity  284 . This will cause the fluid flow to speed up as it moves though a reduced volume. Due to the increase in velocity of the fluid (jetting) any particles remaining in the fluid will be less inclined to settle.  
      The method of use of the separator  110 ′ is similar to separator  110 . Fluid to be separated is enters the inlet  126 . The shaft  114  is rotated. Fluid entering the cavity encounters baffles  148  and is imparted with rotational momentum as the fluid moves radially though the first cavity  120 . As the fluid reaches the tapered part of the divider  118  particles entrained within the fluid have centrifugal force exerted on them and tend to layer on the inner surface on the first disc  172 . The parting means  270  separates the flow of fluid with fluid having less particles entering the third cavity and fluid having more particles entering the collection region  124 . Still under the influence of the centrifugal force the particle entrained in fluid in the collection region  124  tend to settle over the first outlet  130 . Depending on the operation required the particles by be collected or allowed to exit the separator via the outlet  130  continuously or in batches.  
      It is noted that in the separator  110 ′, if the first outlet is closed, the second outlet effectively operated as an open first outlet in the separator  110  and the third outlet of separator  110 ′ effectively operates as the second outlet of separator  110 . In addition collected particles can be removed in batches from the first outlet.  
      Fluid substantially devoid of particles moves towards the axis of rotation releases rotational energy to the baffles  150  or baffles  272  so that energy is conserved by the separator and fluid exiting the second outlet  128  or third outlet  274  is less turbulent.  
      The advantages of the present invention will be clear to the skilled addressee. These include: 
          a screen or filter is not involved and therefore does not need to be cleaned, in effect the separator of the present invention is self cleaning;     the separator need not be operated in a particular orientation, although it may be preferred to use the influence of gravity to assist the fluid moving from the inlet down to the first outlet;     due to the control provided at the first outlet the collection of particles within the collection region need not always by operated in batches, although it may be operated as such;     controlling the outlet of particles from the collection region also assists in better separation and therefore the separator of the present invention is highly efficient; and     energy used to rotate the separator and fluid passing therethough is conserved by recovering the rotational energy imparted on the fluid as it travels through the second sub-cavity.        

      Modifications and variations may be made to the present invention without departing from the basic inventive concept. Such modifications may include: 
          altering the method of control of the rate of constituent leaving the first outlet;     altering the orientation of the separator in use;     changing the relative size of the cavity so that it may be shorter and wider (more disc like) or longer and thinner (more cylinder like);     in addition a series of separators may be provided to progressively refine the separation of the outlet of one separator by the operation of a second separator;     the number of baffles/fins may vary to the point where a large number of baffled are provided so that in effect the cavity may become a series of radially extending channels rather than voids with baffles extending therein.        

      Such modifications and variations are intended to fall within the scope of the present invention, the nature of which is to be determined from the foregoing description.