Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
  • B04B—CENTRIFUGES
  • B04B11/00—Feeding, charging, or discharging bowls
  • B04B11/06—Arrangement of distributors or collectors in centrifuges
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
  • B04B—CENTRIFUGES
  • B04B1/00—Centrifuges with rotary bowls provided with solid jackets for separating predominantly liquid mixtures with or without solid particles
  • B04B1/10—Centrifuges with rotary bowls provided with solid jackets for separating predominantly liquid mixtures with or without solid particles with discharging outlets in the plane of the maximum diameter of the bowl
  • B04B1/14—Centrifuges with rotary bowls provided with solid jackets for separating predominantly liquid mixtures with or without solid particles with discharging outlets in the plane of the maximum diameter of the bowl with periodical discharge

Definitions

• the present invention relates to a centrifugal separator for the separation of a liquid mixture into two components having different densities, which centrifugal separator comprises a rotor supported at the top of a vertical drive shaft and having a separation chamber and an inlet and two outlets, one central outlet and one peripheral outlet, for the respective mixture components, a stack of frusto-conical separation discs arranged in the separation chamber coaxially with the rotor, means forming centrally in the stack of separation discs an inlet chamber, which is open upwardly for receiving mixture to be separated and which through inlet passages communicates with the separation chamber, equipment for discharging the separated components out of the rotor through said outlets during rotation of the rotor, said equipment comprising first members arranged during operation of the rotor to maintain a free liquid surface at a predetermined radial level in the rotor inlet chamber and second members operable for intermittent opening and closing of the periphe ⁇ ral outlet, and means for introducing into the separation chamber an additional liquid having a density larger
• a liquid mixture may be separated into two different liquid components and a third component consisting substantially of solids.
• An additional liquid having a density larger than that of the separated light liquid component may be introduced into the rotor either together with the liquid mixture or separately in order to displace separated light liquid component out of the separation chamber through the central outlet of the rotor for this liquid component.
• the additional liquid is of the same kind as the heavy liquid component separated in the rotor.
• the rotor has two central outlets for the respec- tive separated liquid components. Both of these outlets are situated in the upper part of the rotor and are axially separated from each other, the outlet for separated heavy liquid component communicating with the radially outermost part of the separation chamber through an outlet channel situated above the stack of conical separation discs.
• an emulsion may be avoided in connection with the introduction of the additional liquid into the rotor, under the presumption that the outlet channel in the rotor, connecting the separation chamber with the central outlet of the rotor for separated heavy liquid component, is filled up with heavy liquid component.
• centrifuge rotor of this kind the liquid mixture is introduced into the rotor without getting into contact with the surrounding atmosphere, usually through a channel extending through the rotor drive shaft. Examples of arrangements for the introduction of a liquid mixture and an additional liquid into a rotor through a hollow rotor drive shaft are shown in US-A-3,750,940 and WO 88/02663.
• the object of the present invention has been to provide in connection with a so called open centrifuge rotor a means for introducing an additional liquid into the rotor separation chamber, which means is designed such that it will be cheap to produce and enable introduction of additional liquid into the rotor without formation of an emulsion therein. It should be possible to use the said means in a centrifuge rotor having only one central outlet for a separated liquid compo ⁇ nent.
• This object can be obtained according to the invention in a centrifugal separator of the initially defined kind in a way such that the walls delimiting the afore-mentioned channel between the separation chamber and the said receiving chamber in the rotor extend radially inwardly past said predetermined radial level and are arranged positively to entrain in the rotor rotation additional liquid introduced into the recei ⁇ ving chamber through the stationary members, before the additional liquid gets into contact with separated liquid component.
• the supplied additional liquid will thus be acce- lerated to the rotational speed of the rotor in the receiving chamber and in the radially innermost part of the said chan ⁇ nel, before it meets the separated liquid component which is present in the channel at some distance from the receiving chamber.
• the walls delimiting the channel form an angle with the rotor axis at least in the part of the channel being situated radially outside of said predetermined level, up to which liquid from the separation chamber may reach at the longest.
• the centrifuge rotor may be arranged to receive additional liquid from said stationary members at different axial levels in the rotor.
• said receiving chamber is formed in the lower part of the inlet chamber, the statio ⁇ nary members extending into the rotor through the upper open end of the inlet chamber and further through the inlet cham ⁇ ber down to the receiving chamber.
• Fig 1 shows a centrifuge rotor the rotor body of which com- prises a lower part 1 and an upper part 2, which parts are axially held together by means of a locking ring 3.
• a screw or a nut 4 keeps the rotor body fastened to the uppermost part of a vertical drive shaft 5.
• a stationary inlet pipe 6 for a liquid mixture to be treated within the rotor extends from above axially into the rotor and opens in an inlet chamber 7.
• the inlet chamber 7 which is thus open axially upwardly is delimited centrally within the rotor by a slightly conical thin walled member 8 that is connected with the rotor body.
• a separation chamber 9 in which there is situated a stack of frusto-conical separation discs 10 arranged coaxi- ally with the rotor and axially spaced from each other.
• the separation discs turn their base portions downwardly towards the drive shaft 5.
• the stack of separation discs 10 rests on a frusto-conical partition 11 formed in one piece with the lower part of the member 8 delimiting the inlet chamber 7.
• a frusto-conical partition 11 formed in one piece with the lower part of the member 8 delimiting the inlet chamber 7.
• the partition 11 rests on a hollow frusto-conical body 13, the upper part of which extends into the inlet chamber 7 immediately above the nut 4.
• a number of inlet passages 14 are delimited by means of the wings 12, said inlet passages connecting the inlet chamber 7 with the sepa ⁇ ration chamber 9.
• the hollow fruso-conical body 13 rests on a central portion of the lower rotor body part 1 and has on its underside at least one radial groove 15.
• the cross sectional area of the groove is substantially unchanged along the length of the groove and is substantially smaller than the cross sectional area of each of the inlet passages 14.
• the groove 15 has a width taking up only a small part of the circumference of the receiving chamber 16.
• a narrow stationary tube 17 extends into and axially through the inlet pipe 6 to the central receiving chamber 16.
• the lowermost end portion of the tube 17 supports on its outside a conical flange or deflector 18, which is formed such that mixture introduced into the rotor through the inlet tube 6 is conducted into the inlet chamber 7 but is prevented from flowing into the receiving chamber 16.
• a central outlet chamber 19 which through a passage 20 communi ⁇ cates with the separation chamber radially inside the separa ⁇ tion discs 10.
• the passage 20 forms a central overflow outlet from the separation chamber 9 for a liquid separated therein.
• the outlet member 21 is connected with an outlet conduit 22.
• the lower rotor body part 1 has several ports 23 distributed around the rotor axis. These ports form peripheral outlets from the separation chamber, which may be kept closed or open during the rotation of the rotor.
• the separation chamber communicates with the ports 23, i.e. the peripheral outlets of the separation chamber are then open.
• valve slide 24 For operation of the valve slide 24 during rotation of the rotor hydraulic forces are used partly from liquid present in the separation chamber 9, partly from a separate operating liquid which can be supplied to the rotor body through a stationary supply pipe 25.
• the valve slide 24 seals at its centre portion and at its peripheral portion radially against the lower rotor body part 1 and delimits therewith a so called closing chamber 26 for operating liquid.
• the closing chamber extends around the rotor axis and has at least one central supply channel 27 and at least one peripheral outlet channel 28 for operating liquid.
• the closing chamber 26 is kept filled with operating liquid.
• the outlet channel 28 is dimensioned so that this will be possible.
• the operating liquid by its pressure keeps the valve slide 24 in its upper position, so that the peripheral outlets 23 of the separation chamber are closed.
• the supply of operating liquid through the supply pipe 25 is interrupted during a longer or shorter period.
• the closing chamber 26 then is drained completely or partly through the outlet channel 28, the valve slide 24 being pressed downwardly to its opening position by the pressure of liquid present in the separation chamber 9.
• the valve slide 24 is pressed back to its closing position.
• the displacement liquid in the form of wings or annular discs coaxial with the rotor, may be arranged the displacement liquid is gradually accelerated up to the rotational speed of the rotor. If not before so when the displacement liquid has entered the channel 15, it is thus caused to rotate with the same speed as the rotor. Only after this the displacement liquid gets into contact with the separated liquid present in the rotor, i.e. at the liquid surface 31 in the channel 15. The two different kinds of liquids will thus get into contact with each other in an area where both of them rotate with the same speed in the rotor, meaning that there is a minimum risk for the formation of an emulsion from the liquids.
• the displacement liquid flows further into the separation chamber 9 through the channel 15.
• the displacement liquid collects at the periphery of the rotor radially outside the separation discs 10, and when gradually more displacement liquid is supplied the interface layer between this liquid and separated liquid moves radially inwardly in the separation chamber.
• the separated liquid is thus displaced towards the centre of the rotor and flows out through the outlet passage 20 and further through the outlet member 21 to the outlet conduit 22.
• the supply of mix ⁇ ture through the inlet pipe 6 may be interrupted, if desired.
• the peripheral outlets 23 are uncovered during a short while, separated sludge and dis ⁇ placement liquid being thrown out therethrough.
• the channel 15 is then emptied of displacement liquid.
• the periphe ⁇ ral outlets are again closed and normal operation of the centrifuge rotor is resumed, the channel 15 is filled with separated liquid from the separation chamber 9 into the level 31 (fig 2).
• the recei- ving chamber for displacement liquid is situated in the lower part of the rotor inlet chamber for mixture to be separated.
• the receiving cham ⁇ ber for displacement liquid is, instead, situated above the inlet chamber for mixture to be separated.
• Fig 3 shows a centrifuge rotor substantially of the same kind as the centrifuge rotor in fig 1. Means corresponding to each other in fig 1 and 3 have been given the same reference numerals, the letter a having been added in fig 3.
• a body 13a having an annular central portion and a frusto-conical portion there-around.
• the frusto-conical portion has on its upper side, which abuts against the under ⁇ side of the rotor body part 2, at least one radial groove 15a.
• the central annular portion of the body 13a delimits a radially inwardly open annular receiving chamber 16a.
• the groove 15a on the upper side of the body 13a forms a channel which connects the receiving chamber 16a with the separation chamber 9a.
• a channel 32 extends axially through the central portion of the body 13a and connects the separation chamber 9a with the passage 20a.
• Axially through the inlet pipe 6a there is extending a narro ⁇ was pipe 17a for displacement liquid.
• the pipe 17a is bent 90° at the level of the receiving chamber 16a and extends out through the wall of the inlet pipe 6a for introduction of displacement liquid into the receiving chamber 16a.
• the working mode intended for the centrifuge rotor according to fig 3 is the same as that for the centrifuge rotor in fig 1 and 2.
• all of the limiting walls of the groove or the channel 15 and 15a, respectively extend radi- ally inside the level 31 and 31a, respectively, at which a free liquid surface is formed during normal operation of the rotor.
• displacement liquid introduced into the receiving chamber 16 and 16a, respectively will safely be brought to the same rotational speed as the rotor before it gets into contact with liquid having been separated in the rotor and being present in the groove or the channel 15 and 15a, respectively.
• separate entrainment members in the form of wings, e.g. similar to the wings 12 in fig 1 and 2, may be arranged in the receiving chamber 16.
• wings of this kind distributed around the rotor axis may extend in a particular embodiment of the invention radially and axially in an annular space all the way from the recei ⁇ ving chamber 16 to the separation chamber 9 and, thus, deli- between themselves channels corresponding to the channels and 15a in fig 1 and fig 3, respectively.

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• Centrifugal Separators (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20380759

Family Applications (1)

Country Status (6)

Cited By (3)

Citations (8)

• 1990
  • 1990-10-29 SE SE9003439A patent/SE467294B/sv not_active IP Right Cessation
• 1991
  • 1991-10-07 JP JP3517474A patent/JPH05503245A/ja active Pending
  • 1991-10-07 BR BR919106116A patent/BR9106116A/pt unknown
  • 1991-10-07 KR KR1019920701540A patent/KR920703208A/ko not_active Application Discontinuation
  • 1991-10-07 EP EP91919854A patent/EP0507924A1/en not_active Withdrawn
  • 1991-10-07 WO PCT/SE1991/000674 patent/WO1992007658A1/en not_active Application Discontinuation

Patent Citations (8)

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