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
  • B04B1/10—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 concerns a centrifugal separator with a rotor, having a valve device located at its periphery.
• the valve device comprises a radially movable valve body arranged in a radial inner position and against the influence of the centri ⁇ fugal force to close an outlet passage for a liquid contained in a chamber within the rotor and in a radial outer position to keep said outlet passage open.
• a liquid mixture is intended to be centrifugally treated in a separation chamber within the rotor, a specific heavier compo ⁇ nent of the liquid mixture being separated and accumulated at the periphery of the separation chamber.
• the component accumulated in. this way is thrown out of the separation chamber through an outlet which is openable during operation.
• the outlet can be opened by axially moving by means of the pressure from the mixture of liquids contained in the separation chamber, a slide valve, which together with a rotor part defines the separation chamber, said pressure acting axially on the slide valve against the pressure action of a closing liquid which is contained in a closing chamber formed by the slide valve and the rotor wall. If the axial force acting on the slide valve by the pressure from the closing liquid is larger than the axial force by the pressure of the liquid mixture, the slide valve moves in a closing direction and is pressed into sealing abutment against a sealing surface.
• the opening and closing procedure can be controlled by letting closing liquid out of the closing chamber through a peri ⁇ pheral outlet passage provided with a contol valve.
• the control valve in turn can be controlled by means of a control liquid, which by its pressure acts radially inwards on a radially movable valve body against the influence of the centrifugal force.
• the pressure of the control liquid acts on the valve body in a direction closing the outlet passage for the closing liquid, whereas the centrifugal force thus is acting on the valve body in an opening direction.
• closing liquid and control liquid are supplied centrally through supply channels in the rotor.
• the supply channels for the control liquid has a peripherally located throttled outlet, out of which control liquid flows during most of the time of operation, while the control valve is kept closed by the pressure of the control liquid in the control channels.
• the control valve can be opened by cutting off the supply of control liquid, whereby the pres ⁇ sure acting on the valve body successively decreases and, finally, the valve body moves radially outwards as a consequence of the centrifugal force and opens the outlet passage for the closing liquid.
• control liquid means that large amounts of control liquid get lost because of the fact that such control liquid during most of the time of operation is forced out of the centrifuge rotor through the throttled outlet at a high pressure. With the control liquid even its content of energy is lost.
• the main object of the present invention is to provide a ce ⁇ tri- fugal separator of the Initially described kind, wherein a liquid contained in the rotor can be let out through a valve device giving a low flow resistance and being designed such that no control liquid has to be lost only for retainment of the valve device in a position in which said outlet passage is closed.
• a centrifugal separator of this kind with a valve device, which in addition to said valve body comprises two valve chambers, a first and a second valve chamber, means arranged to press the valve body radially inwards at an overpressure in the first valve chamber, a radially movable member, which forms a movable wall between said valve chambers and is exposed to pressures prevailing therein, a first and a separate second channel, for the supply of control liquids to the first and second valve chambers, respectively, which channels extend between the valve chambers and central parts of the rotor, and an outlet at the periphery of the rotor for draining of control liquid out of said second channel.
• This outlet has such a limited through flow capacity that upon supply of a predeter ⁇ mined minimum flow of control liquid to the second channel a certain overpressure is obtained in the second chamber, the movable member being arranged to be moved radially inwards by said overpressure in the second valve chamber, so that liquid is displaced out of the first valve chamber and further through the first channel towards the centre of the rotor.
• said outlet passage opens in a surface in the rotor, which is facing essentially ra- dially outwards, the valve body being movable radially to and from sealing abutment against said surface.
• a through- flow area of the openable flow path through the control valve is obtained, which increases quickly when the valve body moves in its opening direction.
• the first valve chamber of the valve device is located radially outside of the movable member, and the second valve chamber of the valve device is located radially inside of the same.
• the movable member is arranged to move radially inwards at an overpressure in the first valve chamber - against the influence of the centrifugal force and the pressure in the second valve chamber - and via an element, radially movable through and sealing against the wall of the second valve chamber to press the valve body mechanically toward closing of the outlet passage.
• the pressure therein will increase to such a degree that it overcomes the radial force on the movable member resulting from the pressure in the first valve chamber, whereby the valve body by the centrifugal force is brought to move radially outwards and to open the outlet passage.
• the first valve chamber of the valve device is located radially inside of the movable member and the second valve chamber is located radially outside of the same.
• the movable member is arranged to be pressed by centrifugal forces and the pressure in the first valve chamber radially outwards against the action of the pressure in the second valve chamber.
• a part of the valve body in this embodiment forms a radially inner wall, of the first valve chamber, which simultaneously operates as a pressure transmittning element for pressing the valve body radially inwards to sealing abutment against the rotor body at an overpressure in the first valve chamber.
• control liquid is supplied to the second valve chamber centrally via the second channel.
• the supply of control liquid then exceeds a predetermined minimum flow, which is deter- mined by the through flow capacity of the outlet of the second channel.
• the pressure in the second valve chamber hereby increases so much that it can move the movable member radially inwards, against the action of the centrifugal force and the pressure in the first valve chamber, and thereby displace the control liquid out of the first valve chamber and further through the first channel towards the centre of the rotor.
• control liquid to the second channel is cut off, whereby this channel and the second valve chamber are emptied of their contents out to the radius, at which the throttled outlet is located.
• the pressure in the second chamber then decreases and the movable member is thrown out. Because of the fact that the supply of control liquid to the first valve chamber is throttled, this means that the pressure in this valve chamber decreases, which influences the valve body. Hereby the valve body will be thrown radially outwards and will open the outlet passage.
• control liquid is supplied to the first valve chamber through the throttled inlet and the pressure in this increases again. When the pressure has reached a certain level It is able to move the valve body radially inwards into sealing abutment against the opening of the outlet passage.
• the movable member may be provided with a larger effective pressure area facing radially outwards to the second valve chamber than its effective pressure area which facing radially inwards to the first valve chamber.
• the liquid contained in said chamber can be constituted by any liquid present in the rotor, such as a liquid component separated in the separation chamber or the so called closing liquid in the closing chamber.
• the very closing liquid is intended to operate also as a control liquid.
• the closing chamber in this case will function as a first channel for the supply of control liquid to the first valve chamber.
• the valve body with a throttled channel, which extends radially through the valve body and connects the first valve chamber with said outlet passage, so that, when the valve body is in a closing position, the firs ' t channel, i.e. the closing chamber, communicates with the first valve chamber via the outlet passage.
• the moving member preferably may be provided with a larger effective pressure area facing radially outwards in the second valve chamber than its effective pressure surface facing radially inwards to the first valve chamber.
• figure 1 shows an axial section through a part of a centrifugal separator according to an embodiment of the invention
• figre 2 shows an axial section through a part of a centrifugal separator according to another embodiment of the invention
• figure 3 shows an axial section through a part of a centrifugal separator according to a preferred modification of the embodiment of the invention shown in figure 2, and
• figure 4 shows an axial section through a part of a centrifugal separator according a further embodiment of the invention.
• FIG. 1 there is shown a part of a centrifugal separator which has a rotor body, which consists of a lower rotor part 1 and an upper rotor part 2, which in a not shown manner are connected to each other, for instance by means of a locking joint.
• a rotor body which consists of a lower rotor part 1 and an upper rotor part 2, which in a not shown manner are connected to each other, for instance by means of a locking joint.
• Inside the lower rotor part 1 an axially movable slide valve 3 is arranged, which together with the upper rotor part 2 'forms a separation chamber 4.
• the slide valve 3 and the lower rotor part 1 define between themselves a closing chamber 5.
• the slide valve 3 is pressed by the pressure from a closing liquid being inside the closing chamber 5 to sealing abutment against the upper rotor part 2 against the action of the pressure from a mixture of liquids being inside the separation chamber 4, and thereby shutting off a connection between the separation chamber 4 and an outlet 6 for a specific heavier liquid component, which during separation has been thrown radially outwards and accumulated at the periphery of the separation chamber 4.
• the closing chamber 5 is connected to the outlet chamber 7 via an outlet passage 8, which extends essentially radially outwards from the closing chamber 5 and is able to be opened and closed by means of a valve device.
• This valve device comprises a radially movable valve body 9 arranged in the outlet chamber 7 which valve body 9, when the outlet passage is closed, is pressed to sealing abutment against an essentially radially outwards facing surface, to which the outlet passage 8 opens.
• the outlet chamber 7 is connected to the surroundings of the rotor via an outlet channel 10. Radially outside the outlet chamber 7 there is formed a valve cavity in the lower rotor part 1.
• valve cavity there is arranged a radially movable member 11, which divides the valve cavity into a radially outer first valve chamber 12 and a radially inner second valve chamber 13.
• a mechanically force transmitting element 14 is arranged radially movable through and sealed against a sleeve 15 in the separating wall 16 between the outlet chamber 7 and the second valve chamber 13.
• the first valve chamber 12 is separated from the surroundings of the rotor by means of a plug 17 and connected to a first channel 18 for the supply of control liquid from a centrally located supplying means (not shown) to this valve chamber 12.
• the second valve chamber 13 is connected to a second channel 19 for the supply of control liquid from a centrally located supplying means (not shown) to this second valve chamber 13.
• This second channel 19- is connected.to the surroundings of the rotor via an outlet 20, which has a limited through flow capacity.
• the centrifugal separator shown in figure 1 operates in the following manner:
• the closing liquid can be supplied centrally to the closing chamber 5.
• the pressure acting on the slide valve 3 from the closing liquid at this time will be increasing and pressing the slide valve 3 to sealing abutment against the upper rotor part 2.
• the mixture of liquid which is to be centrifugally treated, Is supplied to the separation chamber through a not shown central inlet.
• the rotational speed of the rotor increases and reaches after a while the operational speed, at which the components in the mixture of liquids is separated in the separation chamber 4.
• the specific heavier component is thrown radially outwards during the separation and accumulates at the periphery of the separation chamber 4, while one or more specific lighter components are guided radially inwards toward one or more central outlets (not shown).
• the total force, acting radially outwards on the movable member 11, increases thereby in such a degree that it is capable to move the movable member 11 and the valve body 9 radially outwards and to force the control liquid out of the first valve chamber 12 and further through the first channel 18 towards the centre of the rotor and to open the outlet passage 8 for the letting out of the closing liquid 5 contained in the closing chamber 5 Inside the radial level, at which the outlet passage 8 is connected to the closing chamber 5.
• the axial force acting on the slide valve 3 from the closing s) liquid remaining in the closing chamber 5 Is thereby decreasing and becomes smaller than the axial force from the mixture of 10 liquids contained in the separating chamber 4 on the same, whereby the connection between the separating chamber 4 and the outlet 6 is opened.
• control the time, during 25 which the passage between the separating chamber 4 and the outlet 6 is open This can be done by controlling the time, during which liquid is supplied to the second channel 19 and the closing chamber 5. It also can be done by controlling the supply flow for one or both of these liquids.
• the 30 control Is done by controlling the time, during which the control liquid is supplied to the second channel 19 and the second valve chamber 13 with a relatively heavy flow.
• the supply of closing liquid to the closing chamber 5 then can be done either continuously or intermittently. How much of 35 the liquid content in the separation chamber, which can be let out through the outlets 6, is determined by the radius at which the outlet passage 8 is connected to the closong chamber 5, i.e.
• Figure 2 shows an embodiment, in which the first valve chamber 12 is located radially inside the movable member 11 and the second valve chamber 13 is located radially outside the movable member 11.
• the first channel 18 has been provided with a throttling means 21 at the inl-et of the first valve chamber 12.
• the first valve chamber 12 is de ⁇ fined radially inwards by a separating wall, which at the same time functions as a pressure transmitting element 14 in order to press the valve body radially inwards at an overpressure in the first valve chamber 12.
• the element 14 constitutes an integrated part of the valve body 9.
• this embodiment corresponds to the one shown in figure 1.
• the embodiment shown in figure 2 functions in a way that differs somewhat from the way described above with reference to figure 1.
• the opening of the outlet 6 is activated by supplying control liquid to the second channel 19 and the second valve chamber 13.
• the pressure in the second valve chamber 13 will at this time be increasing enough to move the movable member 11 radially inwards and thereby to displace at least a part of the control liquid contained in the first valve chamber 13out of the same through the throttled inlet 21 and further through the first channel 18 towards the centre of the rotor.
• the valve body 9 remains in a position closing the outlet passage 8.
• the outlet passage 8 remains open during the time that is necessary for the amount of control liquid having earlier been forced out of the first valve chamber 12 and further through the channel 18 towards the centre of the rotor, to reflow into the first valve chamber 12 through the throttled inlet 21.
• the connection will be opened between the separation chamber 4 and the outlet 6. This connection will be kept open and will be shut off again according to the same procedure as the one already described in connection to the embodiment according to figure 1.
• the supply of the closing liquid to the closing chamber 5 in this one will be done either continuously or intermittently.
• Figure 3 shows a preferred modification of the embodiment of the invention shown in figure 2.
• the preferred embodiment differs from the above described embodiment by designing the radially movable member 11 with a radial outer portion 11a and a radial inner portion lib.
• the outer portion 11a has been given a larger effective pressure area facing radially outwards to the second valve chamber 13 than the effective pressure area of the inner portion lib facing radially inwards to the first valve chamber 12.
• the barrel, in which the movable member 11 moves has been divided in two, i.e.
• valve body 9 In both the embodiment according to figure 2 and the embodiment according to figure 3 it is possible to have the valve body 9 to move rapidly radially outwards when the supply of control liquid to the second channel 19 is cut off. This means that a wanted amount of the closing liquid rapidly can be let out of the closing chamber 5 by means of a small number of valve devices. The rapid letting out of closing liquid is of great importance to make it possible even for a predetermined amount of separated specific heavier component accumulated at the periphery of the separating chamber 4 to be let out rapidly, which is desirable at many applications.
• FIG 4 an embodiment of the invention is shown which especially has been adapted for centrifugal separators having such a slide valve 3 and in which the liquid flowing out through the outlet passage 8 consists of closing liquid.
• the closing liquid also functions as a control liquid, the closing chamber 5 functioning as a first channel for the supply of control liquid to the first valve•chamber 12.
• the throttled inlet to the first valve chamber 12 consists of a channel 23, which extends essentially radially through the valve body 9, in a way that, when the valve body 9 is in a position closing the outlet passage 8, the closing chamber 5 communicates with the first valve chamber 12 via the outlet passage 8 and the channel 23.
• this embodiment corresponds to the embodiment shown in figure 3.
• a portion of the supplied closing liquid passes through the throttled channel 23 into the first valve chamber 12 and fills it up. Because of the fact that the cross section area in the first valve chamber.12 is larger than the cross section area of the outlet passage 8, the valve bo'dy 9 is kept in a position closing the outlet passage 8 even -if there is no overpressure in the second valve chamber 13. Without opening of the outlet passage 8 a supply of control liquid to the second channel 19 hereby can be diminished to a flow, which is somewhat less than the throughflow capacity of the throttled outlet 20, in a way such that the movable member slowly is moving radially outwards.
• the speed of the movable member 11 has to be so low that the flow through the throttled channel 23 to the first valve chamber 12 can fill up the increasing of volume, which the first valve chamber 12 hereby undertakes.' As soon as the movable member 11 has reached its radially outermost end position, the supply of control liquid to the second channel 19 can be cut off completely.
• the mixture of liquids supplied to the separation chamber con ⁇ tains relatively large amounts of the specific heavier component, it is possible to omit to reduce the supply of control liquid to the second channel 19 before it is time again to open the outlet passage 8. Thereby, the movable member 11 is kept in its radial inner position until the supply of control liquid to the second channel 19 is cut off for the opening of the outlet passage 8.
• outlet passage 8 is connected to the closing chamber 5 at a radius which is smaller than the greatest radius of the closing chamber 5.

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• Centrifugal Separators (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20360022

Family Applications (1)

Country Status (4)

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• 1985
  • 1985-04-30 SE SE8502101A patent/SE8502101D0/xx unknown
• 1986
  • 1986-04-29 JP JP50254486A patent/JPS62502672A/ja active Pending
  • 1986-04-29 WO PCT/SE1986/000195 patent/WO1986006300A1/en not_active Application Discontinuation
  • 1986-04-29 EP EP19860902946 patent/EP0222816A1/de not_active Withdrawn

Non-Patent Citations (1)

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