Classifications

• • 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
  • B04B1/04—Centrifuges with rotary bowls provided with solid jackets for separating predominantly liquid mixtures with or without solid particles with inserted separating walls
  • B04B1/08—Centrifuges with rotary bowls provided with solid jackets for separating predominantly liquid mixtures with or without solid particles with inserted separating walls of conical shape
• • 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
  • B04B11/02—Continuous feeding or discharging; Control arrangements therefor
• • 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
  • B04B11/08—Skimmers or scrapers for discharging ; Regulating thereof
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
  • B04B—CENTRIFUGES
  • B04B7/00—Elements of centrifuges
  • B04B7/08—Rotary bowls
  • B04B7/12—Inserts, e.g. armouring plates
  • B04B7/14—Inserts, e.g. armouring plates for separating walls of conical shape

Definitions

• the subject of the invention is a laminar flow centrifugal separator.
• This separator has been designed for fluid mixtures containing solids, liquids or gases in various proportions, but above all mixtures containing solid suspensions in liquid phases, which must be separated into at least one liquid fraction. and a fraction containing the solid. A good separation of the constituents of the mixture is then sought and a solid fraction is obtained in a compact form, called cake, with a relatively low residual content of the suspension liquid. Even when the formation of a cake leads to a strong resistance to flow, or even a large section reduction of the latter, it is generally sought to extract this solid fraction of the separator, and if possible continuously despite its compact nature as it forms in the rotating bowl, without allowing it to accumulate there. This objective is not usually achieved with existing separators, many of which instead require periodic stops of the process, detrimental to its performance, to remove the cake. Separators that provide for continuous removal of the solid fraction normally do not provide cakes having sufficient dryness.
• WO-A-2007/133161 discloses a separator which has certain surface similarities with the invention.
• I l comprises as main part a rotating bowl of biconical form in which the separation takes place.
• the mixture is introduced into the bowl by a hollow conduit, which corresponds to the axis of support and rotation of the bowl.
• the heavier solid fraction is directed to the periphery of the bowl and more particularly in the bulge zone corresponding to the junction of the cones.
• the opening of peripheral holes at this point allows to take it, while the fluid fraction rises to the top of the bowl, as we add the mixture, and out through an opening at the top of the bowl to the opposite of the introductory opening.
• Plate separators have been improved to prevent solid build-up and unbalance in the centrifuge.
• One solution proposed is to perforate the plates or set up separation discs at the bottom and top of the lining (WO-A-2012/033440).
• This guy The invention relates more particularly to the treatment of liquids or gases that are slightly charged (washing).
• the improvements provided by the invention depend mainly on the creation of a smooth laminar flow inside the rotating bowl: it has been found that a more compact and dry solid cake was obtained by means of such a device. flow, which produces better phase separation.
• a general form of the invention is a centrifugal separator comprising a rotating bowl with a peripheral wall, a separation structure located in the bowl and rotating synchronously with the bowl, an inlet duct of a mixture situated on an axis of rotation. of the bowl and opening in the bowl, the bowl comprising at least one outlet for liquid or gaseous fractions of the mixture at a first axial side of the bowl, wherein the separation structure comprises a stack of cones divided into angular sectors forming sectors separated by angular intervals, the angular intervals being covered by the immediately adjacent cone sectors, and the sectors have peripheral ends at an identical distance from the peripheral wall.
• the discontinuous conical structures composed of sectors separated by intervals allow a progressive and steady axial movement of the mixture therethrough.
• the flow of the fluid is much more regular than in previous designs and is essentially spiral without abrupt changes of direction between the ends of the bowl.
• the velocity field is also much more uniform. The consequence is that a laminar flow can be obtained without difficulty, and that the separation of the fluid fraction and the solid fraction is much better. This one is deposited on the peripheral wall of the bowl, as it is usual, and can then be removed. Neither the deposition of the solid fraction nor its possible removal simultaneously with the separation actually disturb the flow, which remains essentially spiral.
• the peripheral wall of the bowl is defined by a rectilinear generatrix in front of the sectors (As opposed to the biconical form for example), and even better that the bowl is cylindrical and the cones all identical to each other.
• the invention is generally better implemented when the cake corresponding to the solid fraction can be removed regularly and gradually. It is then recommended that the opening be located on a second axial side of the bowl, opposite said first side where the fluid fraction exits, extends over a circumference of the bowl and is adjacent to an edge of a side wall of the bowl. It is then possible to add an inclined scraper through the opening and extending in front of an inner face of the side wall of the bowl; a transmission provides a differential speed of rotation between the bowl and the scraper from a single drive motor of the separator, which imposes a small relative speed of the scraper inside the bowl, which performs the desired scraping.
• the centrifugal separator can be advantageously equipped with two motors, one for the rotation of the bowl and the other for the rotation of the solids extraction system. This arrangement makes it possible to independently drive the centrifugal part and the scraper and draw-off part without the coupling constraints linked to a differential.
• - Figure 1 is an external view of an embodiment of the separator; - Figure 2 reveals more particularly its motor parts (in configuration to a drive motor);
• FIG. 3 shows a configuration with two drive motors.
• FIG. 4 is a view of its rotating components which ensure the separation of the fractions and the removal of the cake.
• FIG. 5 further illustrates the separator as a whole, this time in section
• FIGS. 6A, 6B and 6C show more particularly the packing of the rotating bowl and the variant embodiments.
• the separator comprises a rotating bowl 1, consisting of a cylindrical drum forming a side wall 8, and a central axis 2.
• the central axis 2 and the bowl rotating 1 are held between a top static head 3 and a lower chassis 4, which are maintained at invariable positions.
• the mixture is introduced through a conduit 5 contained in the central axis 2, here by the top and the static head 3, and arrives in the rotating bowl 1 through openings 6 which can be located at the bottom of the conduit 5 or distributed over its height.
• the central axis 2 carries conical structures composed of separate sectors 7 and similar to flowers, superimposed over all or part of the height of the barrel to the liquid recovery manifold 20, and inclined by extending towards the side wall 8 of the rotating bowl 1 and down.
• the sectors 7 are angularly offset from one stage to another, so that their gaps 9 are covered by an upper sector 7 and a purely axial flow through the stack of structures is impossible.
• the liquid fraction of the mixture obtained by separation and comprising clarified liquid with a low solid content, is discharged from the rotating bowl 1 by a rotating collector 20 housed in the static head 3 and then an upper orifice 10.
• the solid fraction is deposited on the inner face of the side wall 8 before leaving the rotating bowl 1 and out of the separator through a lower orifice 11, as will be described later.
• a motor 12 rotates an extraction screw 19 and a wiper 15 described later via a differential 26 and a first transmission 13 comprising a toothed belt 27 and toothed wheels.
• a second transmission 14 which drives the rotating bowl 1 (and in particular its side wall 8, the central axis 2, the collector 20, the deflector 22 and the sectors 7) at a speed of rotation which may be different from that of the wiper 15 and the extraction screw 19 and further comprises a toothed belt 28 and toothed wheels.
• a support 21 supports the weight of the rotating bowl 1 and the central axis 2 while allowing their rotation. This support 21 may be annular large diameter to support the rotating bowl 1 on its entire periphery.
• the scraper 15 comprises one or more inclined blades 17, mounted on a common circular support 18 and which extend inside the rotating bowl 1, over part of its height, in front of the internal face of the lateral wall 8.
• support 18 extends under an inverted conical base 22 called deflector, connected to the central axis 2, of the rotating bowl 1; the blades 17 extend through a bottom opening 23 of the rotating bowl 1, between the base 22 and the bottom of the side wall 8, and so enter that one. Since the speed of rotation of the wiper 15 is slightly different from that of the rotating bowl 1 during the evacuation of the solids, the inclination of the blades 17 combined with their movement in the rotating bowl 1 makes the solid cake descend progressively downwards. separator. He leaves the rotating bowl 1 through the opening 23 and pays on the conveyor screw 19 located under the support 18, which carries it to the outlet orifice 11.
• two motors 29 and 30 replace the motor 12 and respectively drive the transmissions 13 and 14 at the desired speeds, no differential being necessary.
• the entire contents of the rotating bowl 1 rotates at the same speed and is therefore subject to regular conditions, which promote laminar flow.
• the simple geometric shapes of the side wall 8 and the stacked and angularly offset sectors 7 produce a regular angular component of the flow. As the flow is regular, the separation of the solid fraction and the fluid fraction is much less disturbed, and its result is therefore much better.
• the invention makes it possible to obtain high dryness values greater than 65%, of the solid fraction according to the nature of the suspensions treated. It can be applied to difficult-to-filterable solids, in particular crystals of irregular and elongated shapes, examples of which are co-precipitates of actinide oxalates used in the nuclear industry. It can find employment in other processes of this industry, or, to quote completely different examples, in the agribusiness, the pharmacy, the cosmetology, the biofuels, the environment, etc. where solid products are often organic products of irregular shapes.
• the invention is not limited to the separation of solid-liquid two-phase mixtures in which the solid is heavier: on the contrary, it is applicable to fluid mixtures of all types and makes it possible to envisage three-phase separations by adding a third draw point; the solid fraction mentioned in this description according to the mainly envisaged application is more generally a heavy fraction, and the fluid fraction a light fraction.
• the removal of the solid fraction simultaneously with the separation is not necessary for the proper operation of the separator, even if it allows a continuous operation which is very often appreciated; the favorable separation characteristics remain even with a large deposit of the solid fraction.
• the invention is equally suitable for repulping solids washing processes where the solid fraction is resuspended with a solvent and subjected to a second separation to improve its quality.
• the embodiment described here lends itself well to a modularity by replacing parts, the rotating bowl 1 and the central axis 2 carrying sectors 7 can in particular be easily replaced by other internal linings, of different sizes, of different geometries according to needs.
• FIG. 6A shows a stack of sectors 7 according to the above description
• FIG. 6B a sector stack 7 whose sectors 7 belonging to neighboring stacks are platelets which extend axially and radially in the apparatus
• Figure 6C illustrates other extensions 32 longer, which extend similarly to a sector 7 of the neighboring stack, but which is further away.
• the extensions 31 or 32 serve to better drive the mixture in rotation and help the circulation of the liquid fraction by a regular spiral path; the partitioning they introduce hardly changes the flow.
• the sectors 7 may be metal or reinforced plastic for example. Their deformation under centrifugal forces is often acceptable, and it can be reduced by wedges or spacers.
• the sectors 7 of the neighboring cones may be successively angularly offset, giving a helical component of the flow satisfactory for usual values of spacing cones.
• Calibrated spacers 33 can separate the cones, being for example alternately threaded with them on the central axis 2, with the ability to vary the spacing of the cones.
• a spring 34 may be arranged in the stack of cones, for example between the upper cone and the manifold 20. This spring 34 may be an elastic washer or any other device having the same purpose.
• the separator may be provided with a plurality of outlet orifices 10, in the case where the fluid fraction is composite and formed of several constituents of different densities.
• the outlet orifice - or the outlet orifices - may be equipped with a movable ring 35 which gives it an adjustable opening, in order to adjust the characteristics of the flow through the separator and in particular its flow rate.
• the conveying screw can become ever narrower downwards, as shown in FIG. 5, in order to further compress the cake and to express residual liquid.
• the scraper 15 and the conveying screw 19 may have a portion 36 threaded onto the central axis 2 in order to maintain their coaxiality and to promote good cohesion of the separator.
• peripheral wall 8 of the rotating bowl 1 is transparent so as to enable the completion of the process to be followed.

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• Centrifugal Separators (AREA)

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Publications (1)

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ID=47424972

Family Applications (1)

Country Status (11)

Cited By (1)

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Citations (6)

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• 2012
  • 2012-06-29 FR FR1256276A patent/FR2992574B1/fr not_active Expired - Fee Related
• 2013
  • 2013-06-27 US US14/409,640 patent/US10092909B2/en active Active
  • 2013-06-27 KR KR20157002450A patent/KR20150032316A/ko not_active Ceased
  • 2013-06-27 CN CN201380031288.2A patent/CN104394996B/zh not_active Expired - Fee Related
  • 2013-06-27 EP EP13735231.6A patent/EP2866944B1/fr active Active
  • 2013-06-27 JP JP2015519102A patent/JP6510406B2/ja not_active Expired - Fee Related
  • 2013-06-27 WO PCT/EP2013/063550 patent/WO2014001469A1/fr not_active Ceased
  • 2013-06-27 IN IN2400MUN2014 patent/IN2014MN02400A/en unknown
  • 2013-06-27 ES ES13735231.6T patent/ES2593071T3/es active Active
  • 2013-06-27 CA CA2877072A patent/CA2877072A1/fr not_active Abandoned
  • 2013-06-27 RU RU2015102798A patent/RU2640539C2/ru not_active IP Right Cessation

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