WO2019008121A1

WO2019008121A1 - A supercentrifuge with automatic discharge of solid particles

Info

Publication number: WO2019008121A1
Application number: PCT/EP2018/068307
Authority: WO
Inventors: Riera Domenech MARC
Original assignee: Riera Nadeu, Sa
Priority date: 2017-07-06
Filing date: 2018-07-05
Publication date: 2019-01-10
Also published as: EP3424601A1

Abstract

A supercentrifuge comprising a rotor (10) defining a cylindrical inner chamber (11) with a lower opening (15) of at least 25 mm surrounded by a rotor tubular wall (16) connected to a static support through a low-friction bearing (30) having at least two overlapped rolling bearings (31); a piston (20) located within the inner chamber (11); a liquid injector (50) external to the rotor (10), the rotor (10) being suspended from its upper part; the outer rings (33) of said at least two roller bearings (31) are urged to each other and attached to an annular bearing box (35) which is connected with a static tubular wall (40) by a plurality of compressed elastic members (41), and an annular member (36) being interposed between the inner rings (32) of the rolling bearings.

Description

DESCRIPTION

A SUPERCENTRIFUGE WITH AUTOMATIC DISCHARGE OF SOLID PARTICLES

Technical field

The present invention is directed to a supercentrifuge with a piston for automatic discharging solid particles. It will be understood that a supercentrifuge is a device including a rotor which define an inner chamber in which a liquid to be clarified is clarified separating solid particles and clarified liquid using centrifugal force, said liquid to be clarified being typically blood or other human or animal fluids, or other fluids, and said piston pushing and ejecting the solid particles from the inner chamber.

A supercentrifuge according to this invention, is a centrifuge which is configured to centrifuge a liquid in an inner chamber around a vertical axis, typically a human blood or other human or animal fluid, to forces of 8000 G or above into a rotational inner chamber, up to 24.000 G or even a bit higher.

State of the Art

Supercentrifuge devices provided for the clarification of a fluid, separating the solid particles and the clarified liquid using centrifugal force are known, for example from document ES2403140A2 which describe a rotor defining an inner chamber having a lower opening. In this example, the rotor is suspended from the upper end, and the lower end is lacking any bearing or seal. Inside the inner chamber a piston is provided for the solid particles expulsion through said lower opening. In this example, the piston is impelled downwardly injecting pressurized gas in the upper inner chamber.

In order to move the piston upwardly the rotor is included into a pressurizing chamber. Injecting pressurized gas into said pressurizing chamber said pressurized gas enters the lower inner chamber of the rotor through the lower opening impelling the rotor upwards.

This solution requires keeping the rotor inside a pressurizing chamber, hindering the cleaning and maintenance operations of the rotor. Furthermore, the pressurized gas injected into the pressurizing chamber enters the lower region of the inner chamber where the liquid to be clarified is treated, and therefore said pressurized gas shall be an inert gas in order to prevent contamination of the lower inner chamber. EP2389253B1 discloses a solids discharge centrifugal separator comprising a dual piston separator bowl assembly, the assembly comprising: a separator bowl comprising an upper portion, a cylindrical middle portion, and a conical lower portion, wherein the upper portion comprises a spindle shaft capable of engaging a drive motor, the spindle shaft terminating at an upper end in an outlet port, wherein the lower portion comprises a cylindrical extension terminating at a lower end in an inlet/solids discharge port. The centrifugal separator comprising a lower bearing assembly with anti-rotation pins.

Document US2007049479A1 describe a similar solution in which facing the lower opening of the rotor there is a connector. When the rotor is stopped the connector is moved upwards being coupled to said lower opening of the rotor providing a hermetic seal allowing the injection of pressurized fluid into the inner chamber of the rotor. This solution also requires the use of a sanitized inert gas in order to prevent contamination of the lower inner chamber.

Document US2010167899A1 describe a supercentrifuge in which the rotor include bearing in the upper and in the lower ends thereof. In this solution, the lower opening of the inner chamber is a vertical tube surrounded by two overlapped roller bearings which are cooled by a cooling fluid. The rotor of a typical supercentrifuge rotates generating more than 8000 G in the inner surface of the inner chamber, rotating at very height speeds.

As bigger is the diameter of the bearings higher is the tangential velocity and also higher are the temperatures achieved in said roller bearings during the use of the supercentrifuge, produced by frictions and vibrations. At the high speeds used in a supercentrifuge said temperatures can be destructives for the roller bearings.

In US2010167899A1 the destruction of the roller bearings is prevented using a lower opening of a small diameter in a shape of a vertical tube, reducing the tangential velocity of the roller bearing, and also circulating a cooling fluid through the roller bearings. This solution requires injecting the liquid to be clarified vertically through said vertical tube, being said vertical tube also hermetically sealed permitting the injection of pressurized gas there through to impel upwards the piston using an inert gas, having the same contamination problem than the previously cited documents.

None of the previously cited documents describe a supercentrifuge with automatic discharging of solid particles from the inner chamber permitting an automatic continuous treatment of successive batches.

All those documents require a manual dismounting and cleaning operation between treatment of successive batches in order to eliminate all the solid particles of the inner chamber or of the evacuation conduits of the supercentrifuge, requiring a manual sanitation of all the elements in contact with said solid particles. This operation is expensive, reduces the productivity of the supercentrifuge and depends on the manual skills of the operator. Furthermore, the product traceability is not possible for part of each batch of product treated in the supercentrifuge described in the previously cited documents, because it remains within the evacuation conduits and is removed by the manual cleaning operations.

An additional problem of the previously cited documents is that the manual cleaning operations of the supercentrifuge can be dangerous for the operator, because the risk of being infected by pathogens if the liquid to be clarified is a human or animal fluid, or because the risk to poisoning or burns if the liquid to be clarified is a dangerous compound.

Document EP3025788B1 describe a supercentrifuge in which the piston is moved downwards impelled by a pressurized gas injected in the upper part of the inner chamber, and upwards creating vacuum in said upper part of the inner chamber. This solution doesn't require the injection of gas in the lower part of the inner chamber, where the liquid is clarified, preventing contamination problems, and requiring neither a hermetic seal in the lower opening of the rotor nor the inclusion of the rotor into a pressurized chamber. This document describes therefore a solution which permits an automatic ejection of the content of the inner chamber, but it requires the manual withdrawal of part of the evacuation conducts placed below the lower opening of the inner chamber to achieve said ejection without requiring further cleaning operations.

In the case of the solution proposed in this cited document, the solid fraction of the clarified liquid is ejected through the lower opening, and the liquid to be clarified is projected inside said inner chamber upwardly in an inclined direction through the lower opening. Both features require a lower opening having a diameter relatively big, defining an anti-friction guide ring also of big diameter and therefore with a very high tangential velocity, and having an overheating problem. No solution to this problem is provided in this document in order to reduce the overheating problem of the low-friction bearings, forcing to operate this supercentrifuge during short times and/or to operate it a low rotational velocity to prevent damage to the low-friction bearings, reducing the supercentrifuge capabilities.

The above cited document EP3025788B1 only describe the use of an anti-friction guide ring in the lower part of the rotor, surrounding the lower opening of the inner chamber. As cited above this element is not trivial because the high speeds of the rotor. US2016175854A1 discloses a multi-zone centrifuge adapted for selective high-speed rotation comprising a cylindrical bowl having an axis of rotation, a first cylindrical zone within the bowl and coaxial therewith, having an inner surface with a first radius R1 from the axis of rotation and a second cylindrical zone within the bowl and coaxial therewith and in fluid communication with the first zone, the second zone having an inner surface with a second radius R3 from the axis of rotation, the second radius R3 being greater than the first radius R1 . The centrifuge further has a lower bearing and a seal assembly removably disposed at a first end of the bowl. Brief description of the invention

The present invention is directed to a supercentrifuge with a piston for automatic discharging solid particles.

A supercentrifuge known in the art as per the patent EP3025788, is a device provided with:

• a rotor, suspended from its upper part, defining a cylindrical inner chamber, said rotor being configured to be rotated, by a motor, around a vertical axis at a speed providing at least 8.000 G, up to 24.000 G or higher, at the inner surface of the cylindrical inner chamber for the clarification of a liquid to be clarified separating solid particles and clarified liquid, said cylindrical inner chamber having a lower opening at its lower end concentric with the vertical axis and surrounded by a rotor tubular wall connected to a lower static support through a low-friction bearing concentric with said lower opening;

• a piston provided with valves located within the inner chamber defining a lower inner chamber and an upper inner chamber, said piston being movable along the vertical axis in a downward direction to automatic discharge solid particles settled and retained on the inner surface of the lower inner chamber through said lower opening, and in a upward direction to return the piston to the initial position, the piston being driven by application of vacuum or pressurized fluid within the upper inner chamber applied by a pumping system;

• a liquid injector external to the rotor, placed below the lower opening and not vertically aligned with said lower opening and directed upwards in an angle to project a liquid to be clarified into the lower inner chamber through the lower opening in a non-vertical direction, in order to not interfere the solid particles ejection during the discharge.

As previously indicated a supercentrifuge is a centrifuge which is configured to centrifuge a liquid in an inner chamber around a vertical axis, typically a human blood or other human or animal fluid, to forces of 8000 G or above into a rotational inner chamber, up to 24.000 G or even a bit higher.

Typically said inner chamber is a cylindrical inner chamber having a cylindrical inner surface on which during the centrifugal treatment the solid particles of the liquid to be clarified are settled and retained under said at least 8000 G force.

In the lower end of the inner chamber there is a lower opening of a diameter smaller than the inner diameter of the inner chamber. The centrifugal force of the rotor prevents the liquid contained within the inner chamber to flow down through said lower opening.

A piston is fitted inside the inner chamber, providing a leak seal between the piston and the perimetral inner surface of the inner chamber, typically the cylindrical inner surface, isolating the upper inner chamber from the lower inner chamber. Said piston is movable upwardly and downwardly direction along the inner chamber.

During the clarification process the piston is in the upper position into the inner chamber, and the rotor is activated by a motor, for example an electric motor connected to the upper end of the rotor. While the rotor is rotating a liquid injector, which is placed outside the rotor, below the lower opening of the inner chamber, projects the liquid to be clarified into the inner chamber through the lower opening.

Said liquid injector has a nozzle directed upwards in a non-vertical direction oriented to the lower opening of the inner chamber, but not being in front of said lower opening in the vertical axis direction, in such a way that the liquid jet ejected from the liquid injector through said nozzle enters the inner chamber through the lower opening contacting with any surface external to the inner chamber, preventing contamination.

The rotation of the rotor produces the uniform distribution of the liquid to be clarified on the inner surface of the lower inner chamber, and its clarification being the solid particles of the liquid to be clarified settled and retained on said inner surface of the inner chamber.

The clarified liquid, which is the fraction of the liquid more distant from the inner surface of the inner chamber, passes to the upper inner chamber through valves included in the piston. Said valves are at a distance of the perimeter of the piston, and therefore also at a distance of the inner surface of the inner chamber where the solid particles are settled. This position of the valves determines that the portion of the liquid conducted to the upper inner chamber is the clarified liquid.

From the upper inner chamber, the clarified liquid is extracted from the rotor through a rotor upper opening. When the clarification process is finished, or when the solid particles settled on the inner surface of the inner chamber reaches a predefined threshold, the liquid injection and the rotation of the rotor are stopped. The liquid which remains in the lower inner chamber flows down through the lower opening of the inner chamber by gravity.

Then the valves of the piston are closed and the upper inner chamber filled with pressurized gas injected by a pump, pushing the piston downwards in the vertical axis direction, pushing down the solid particles settled on the inner surface of the inner chamber and ejecting said solid particles from the lower inner chamber through the lower opening.

Then vacuum is created by a pumping system on the upper inner chamber and the piston is moved upwardly to the initial position, being the supercentrifuge ready to start the process again.

The activation system of the piston uses pressurized gas and vacuum applied on the upper inner chamber, therefore the lower inner chamber can be a non-hermetically sealed. This can be achieved non-including the rotor within a hermetic pressurized chamber, or being the lower opening of the inner chamber connected with the static tubular wall using a non- hermetic seal. This feature makes the present invention cheap and easy to build.

The automatic movement of the piston without introducing gas or any element within the lower inner chamber, where the liquid to be clarified should be treated, ensures that no contamination enters within the lower inner chamber. This feature permit starting the treatment of a new batch of liquid to be clarified without requiring a manual sanitation of the lower inner chamber.

In the supercentrifuge proposed in the present patent application, with a rotor suspended form its upper part, following new features are proposed:

• the static tubular wall, at the bottom of the inner chamber of the rotor, which is connected with the low-friction bearing, includes an inner passage vertical and concentric with said vertical axis, said inner passage having a diameter equal or bigger than the diameter of the lower opening of the rotor, connecting the lower opening of the inner chamber with a solid particles outlet in a vertical direction, permitting the evacuation of the inner chamber content by gravity without interfering with other elements external of the inner chamber;

• said low-friction bearing includes at least two overlapped rolling bearings, each roller bearing including an inner ring, an outer ring and roller elements there between, the outer rings of said at least two roller bearings are attached to an annular bearing box said bearing box being connected with a static tubular wall by a plurality of compressed elastic members which produce a centering force of the lower end of the rotor (10) correcting deviations.

The aim of the invention is to provide a supercentrifuge which evacuates automatically the content of the inner chamber after the clarification process without requiring manual dismounting and cleaning operations of the supercentrifuge between batches.

In order to achieve this objective, a static tubular wall, which is part of the structure of the supercentrifuge, define an inner passage vertical and preferably cylindrical, having an inner diameter equal or bigger than the diameter of the lower opening of the inner chamber. This inner passage is placed below and centered with the lower opening of the inner chamber, permitting the automatic vertical discharge of the content of the lower inner chamber by gravity or pushed downwardly by the piston, said content non-interfering with the static tubular wall reaching the solid particles outlet. Preferably said inner passage has a diameter equal or bigger than the rotor tubular wall.

The injection of the liquid to be clarified in an upward non-vertical direction projecting a jet of liquid to be clarified through the lower opening determines that the diameter of said lower opening is bigger than in other typical supercentrifuges. In order to prevent vibrations of the lower end of the rotor, produced due a non-centered weight of the rotor, said lower opening is surrounded by a low-friction bearing, but because of the oversized diameter of the lower opening, the low-friction bearings placed surrounding the lower opening have to be also of an increased diameter. As bigger is the low-friction bearing higher is the tangential speed achieved by said low-friction bearing and also higher is the temperature produced by the friction, which can produce an overheating problem.

In order to prevent overheating of said oversized low-friction bearings, the rotor is suspended from its upper part, for example using small diameter roller bearings connected to a vertical axis of the rotor concentric with the vertical axis. Being the rotor suspended from its upper part the loads transmitted through the low-friction bearings placed around the lower opening are reduced and the overheating problem is also reduced.

Furthermore, said low-friction bearing include, according to the present invention, two roller bearings, which produce lower temperature due the friction and which are more temperature resistant than other low-friction bearings. Said at least two overlapped rolling bearings are both concentric with the vertical axis of the rotor and are preferably of the same diameter. In order to prevent excessive vibrations or a decentering movement of the lower end of the rotor, said roller bearings are connected to a bearing box which is in torn connected with the static tubular wall through compressed elastic members. These compressed elastic members urge the roller bearings and the lower end of the rotor to the centered position regarding the rotation axis of the rotor, but allowing a radial movement when necessary, preventing the roller bearing to receive relevant horizontal loads. This feature also prevents the damage of said roller bearings.

It has been determined that 20 mm is the minimum diameter size of the rotor tubular wall necessary to surround a lower opening big enough to achieve a correct injection of the liquid to be clarified from the outside of the lower inner chamber by the ejection of a liquid jet in a non-vertical upward direction, and also the minimum diameter size necessary to achieve a complete and correct automatic ejection of the solid particles, by the downward movement of the piston, accumulated therein without requiring manual disassembling and cleaning operations of the rotor. Despite the above (and depending of the size of the inner chamber of the rotor) it is strongly recommended to have a diameter around or bigger than 40 mm.

The inner ring of the roller bearing is attached to the rotor tubular wall surrounding the lower opening and therefore its diameter is bigger than the lower opening diameter.

The outer ring is connected to said static tubular wall defining an inner passage concentric with said vertical axis, said inner passage having a diameter equal or bigger than the diameter of the lower opening of the rotor.

Because of said diameter size of the inner ring of the roller bearing the tangential velocity of the roller elements is extremely high during the rotation of the rotor, and its friction with the inner ring and the outer ring produces elevated temperatures which can damage the roller bearings.

In order to prevent the overheating of the roller elements and the inner and outer rings, an annular member can be interposed between the inner rings, being the outer rings urged to each other.

The annular member keeps the inner rings apart to each other, while the outer rings are urged to each other, pressing one against the others by a force parallel to the vertical axis.

This produces a small displacement of the outer ring relative to the correspondent inner ring of each roller bearing, being the roller element placed there between non-centered, and reducing the surface of contact of the roller element with the correspondent inner and outer ring, and therefore reducing the friction and the temperature produced by said friction.

Alternatively, the annular element is placed between the outer rings, being the inner rings urged to each other. In this case the effect achieved is exactly the same.

Preferably the liquid injector is at least partially integrated in a perforation of the static tubular wall, being said perforation connected with the inner passage. This feature, in combination with the above cited feature of the liquid injector being not vertically aligned with the lower opening, produces that the liquid injector does not interfere with the ejection of the content of the inner chamber through the inner passage of the static tubular wall. This permits the injection of the next batch through the liquid injector after ejection of the solid particles of the preceding batch without requiring a manual cleaning operation of the liquid injector, permitting an automatic continuous operation of the supercentrifuge.

According to an embodiment of the present invention the compressed elastic members urge the bearing box in a direction parallel to the vertical axis.

The annular bearing box can be retained between an upper static wall and lower static wall of the static tubular wall. In this case the compressed elastic members can be placed between the bearing box and said lower static wall, urging the bearing box against the upper static wall producing a friction force against the radial movement of said rotor tubular wall regarding the static tubular wall. The force produced by the springs push the bearing box against the upper static wall and the friction between the bearing box and the upper static wall permits the radial movement of the lower end of the rotor but preventing undesired vibrations.

Alternatively, the compressed elastic members can be placed between the bearing box and said upper static wall, urging the bearing box against the lower static wall producing a friction force against the radial movement of said rotor tubular wall regarding the static tubular wall. Preferably the compressed elastic members are springs.

According to an embodiment the annular member is interposed between the inner rings, and the annular bearing box have at least two segments movable to each other in a direction parallel to the vertical axis, each segment having protrusions retaining one outer rings, being the distance between the protrusions defined by the relative position between the at least two segments of the annular bearing box. Thanks to this feature the non-centered position of the roller element can be adjusted. Preferably the annular member is metallic, and has an angular extension inserted into the interspace existing between the inner and the outer rings of the rolling bearings, centering said annular member with the roller bearing and preventing its movement during rotation.

The liquid injector, responsible of the liquid injection within the lower inner chamber, is at least partially integrated in the static tubular wall and projects the liquid to be clarified through an opening provided on the static tubular wall facing the inner passage of the static tubular wall, in such a way that the liquid jet ejected from the liquid injector crosses upwardly in a inclined direction the inner passage, the lower opening and enters into the lower inner chamber where, the centrifugal force of the rotor spread the liquid to be clarified against the inner surface of the lower inner chamber and centrifuges said liquid with a force of at least 8.000 G. When the rotor stops its rotation, the supernatant liquid is drained through the lower opening, and the movement of the piston ejects the solid particles through the lower opening without interfering with the liquid injector which is not on the vertical projection of said lower opening.

According to the present invention the rotor tubular wall surrounding the lower opening can be an inner threaded tubular element different from the rotor which is threaded around the lower opening of the rotor. This permits the easy and fast removal and substitution of the roller bearing when necessary, substituting the roller bearings and the rotor tubular wall attached together at the same time.

According to an embodiment the high of the rotor tubular wall in the vertical axis direction is smaller than the inner diameter of the rotor tubular wall. Thanks to this feature the liquid to be clarified can be projected through the lower opening at an angle of 45° or lower regarding the horizontal.

It will be understood that references to geometric position, such as parallel, perpendicular, tangent, etc. allow deviations up to ± 5° from the theoretical position defined by this nomenclature.

It will also be understood that any range of values given may not be optimal in extreme values and may require adaptations of the invention to these extreme values, such adaptations being within reach of a skilled person.

Other features of the invention appear from the following detailed description of an embodiment.

Brief description of the Figures The foregoing and other advantages and features will be more fully understood from the following detailed description of an embodiment with reference to the accompanying drawings, to be taken in an illustrative and not limitative, in which:

Fig. 1 is a schematic view of a vertical section of the supercentrifuge coincident with the vertical axis of the rotor; being the piston in an intermediate position within the inner chamber;

Fig. 2 is the same schematic view shown in Fig. 1 , being the piston on the lowermost position within the inner chamber, being the lower inner chamber collapsed for the solid particles ejection from the inner chamber through the lower opening;

Fig. 3 is a zoom view of the lower part of the supercentrifuge shown on Fig. 1 ;

Fig. 4 is an exploded view of the elements shown on Fig. 3.

Detailed description of an embodiment

The accompanying figures show an illustrative and non-limiting exemplary embodiment of a supercentrifuge with a piston for discharging solid particles.

The present supercentrifuge schematically shown on Fig. 1 to 4, includes a rotor 10 including a metallic cylinder having a constant diameter and an upper end closed by a cap, said cylinder defining a vertical axis V.

Concentric with said vertical axis V there is a vertical hollow shaft connected with said cap, being the vertical hollow shaft connected to a motor and guided and supported by upper roller bearings. The rotor 10 is suspended from said vertical hollow shaft and its rotation is activated by the activation of the motor connected thereto.

The lower end of the metallic cylinder is threaded on its perimeter, and a lower lid is threaded thereto closing the inner chamber 11 defined within the rotor 10 between the metallic cylinder, the cap and the lower lid.

A piston 20 is slidably arranged within the inner chamber 11 of the rotor 10, having perimetral seals which separate said inner chamber 11 in an upper inner chamber 13, comprised between the piston 20 and the cap, and a lower inner chamber 12 comprised between the piston 20 and the lower lid.

The upper inner chamber 13 is connected with a clarified liquid outlet and with a pumping system not shown (for example a gas pump) through the vertical hollow shaft. The injection of pressurized gas produced by said pumping system in the upper inner chamber 13 moves the piston 20 downwards reducing the lower inner chamber 12 until the piston 20 reaches the lower lid collapsing the lower inner chamber 12, as shown on Fig. 2.

The creation of vacuum within said upper inner chamber 13 by said pumping system moves the piston 20 upwards to the initial uppermost position within the inner chamber 11 .

Said lower lid have a lower opening 15 on its center, concentric with the vertical axis V, being said lower opening 15 the inlet and outlet opening of the lower inner chamber 12.

In this embodiment said lower opening 15 is 50 mm in diameter, and the inner chamber 11 is 150 mm in diameter.

The lower opening 15 is surrounded by a rotor tubular wall 16. In this embodiment, the rotor tubular wall 16 is an element threaded to the lower lid of the rotor 10, but as will be obvious it can be part of the lower lid or part of the rotor 10 when no lower lid exists.

A static tubular wall 40 is connected to the supporting structure of the supercentrifuge, and has an upper part surrounding the rotor tubular wall 16 and a lower part defining an inner passage 42 vertically aligned with the vertical axis V and with the lower opening 15 of the inner chamber 11 . Said inner passage 42 has a diameter equal or slightly bigger than the lower opening 15 diameter, and define a free passage for the vertical ejection of the content of the lower inner chamber 12.

On the static tubular wall 40 surrounding the inner passage 42 there is an opening connected to a liquid injector 50 which projects a jet of liquid to be clarified upwards in a non-vertical direction, for example at 45° regarding the horizontal, through the inner passage 42 and the lower opening 15, injecting the liquid to be clarified within the lower inner chamber 12.

Between the rotor tubular wall 16 and the upper part of the static tubular wall 40 there is a low-friction bearing 30 which includes, in the present embodiment of the invention shown in detail in Figs. 3 and 4, two identical overlapped roller bearings 31. Each roller bearing 31 have an inner ring 32 attached to the outer perimeter of the rotor tubular wall 16 and an outer ring 33 attached to an annular bearing box 35. Between the inner ring 32 and the outer ring 33 there are roller elements 34 which permits the low-friction rotation of the roller bearing 31.

Said annular bearing box 35 is connected to the static tubular wall 40 through compressed elastic members 41 , which in this embodiment are compressed springs.

In this example, the annular bearing box 40 is retained between a lower static wall 44, which is an annular horizontal part of the static tubular wall 40 concentric with the vertical axis V, and an upper static wall 43 which is an annular horizontal lid concentric with the vertical axis V connected to the static tubular wall 40. The springs are compressed between cavities of the lower static wall 44 and the bearing box 35, and urges said bearing box 35 against the upper static wall 43 producing friction between them.

Said friction prevents excessive movement or vibration of the rotor tubular wall 16, and the compressed elastic members 41 urges the rotor tubular wall 16 to the centered position when is non-centered.

The annular bearing box 35 is made of two annular segments 37, 38 threaded to each other. Each segment 37, 38 include protrusions facing the rotor tubular wall 16, said projections retaining the outer rings 33. The distance between the protrusions of the two segments 37, 38 defined by the relative position between the at least two segments 37, 38 of the annular bearing box 35 permits the reduction of the distance between the two overlapped outer rings 33, urging one against the other.

Between the two overlapped inner rings 32 there is an annular member 36 interposed there between, which makes impossible to move the inner rings 32 closer.

This solution pushes the two overlapped outer rings 33 closer to each other than the two overlapped inner rings 32, being the roller elements 34 non-centered, guaranteeing that the contact surface between the roller element 34 and the outer and inner rings 32 and 33 is reduced and therefore the temperature produced by the friction is also reduced.

The vertical loads of the rotor 10 are supported by the roller bearing connected to the vertical hollow shaft, on the upper part of the rotor 10, being the diameter of the vertical hollow shaft and the correspondent roller bearing small enough to do not produce an excessive heating of this bearing.

The low-friction bearing 30 placed around the lower opening 15 is only responsible for the horizontal movements of the rotor 10, and therefore the reduced contact surface of the roller element 34 is not a problem for the load transmission because said loads are reduced or irrelevant.

For the clarification of a liquid, the piston 20 shall be placed on the uppermost position within the inner chamber 1 1 , and the motor shall rotate the rotor 10 producing at least 8.000 G of centrifugal force on the inner cylindrical surface of the inner chamber 11.

Then the liquid injector 50 projects a jet of liquid to be clarified upwards in a 45° inclination regarding the horizontal, crossing the inner passage 42 of the static tubular wall 40 and through the lower opening 15 of the rotor 10, feeding the lower inner chamber 12.

The centrifugal force spreads the liquid to be clarified on the cylindrical inner surface of the lower inner chamber 12, and the centrifugal force also separates the solid particles of the liquid to be clarified which are settled on the cylindrical inner surface of the lower inner chamber 12 producing clarified liquid.

The piston 20 is provided with valves on its perimeter, spaced away from the cylindrical inner surface of the inner chamber 11 , in such a way that the clarified liquid passes through said valves from the lower inner chamber 12 to the upper inner chamber 13, where said clarified liquid is extracted from the rotor 10 through the vertical hollow shaft.

Once the clarification process has been concluded, the rotor 10 is stopped, and the supernatant liquid contained in the lower inner chamber 12 is ejected thereof by gravity through the lower opening 15. Then the piston 20, having said valves closed, is pushed downwards injecting pressurized gas on the upper inner chamber 13. The movement of the piston 20 drags the solid particles settled on the cylindrical inner surface of the lower inner chamber 12 and pushes it through the lower opening 15 of the rotor 10, producing the automatic cleaning of the inner chamber 11 without requiring manual cleaning operation or dismounting process of the rotor 10.

It will be understood that various parts of one embodiment of the invention can be freely combined with parts described in other embodiments, even being said combination not explicitly described, provided there is no harm in such combination.

Claims

1 . A supercentrifuge with automatic discharge of solid particles, the supercentrifuge comprising:

- a rotor (10), suspended from its upper part, defining a cylindrical inner chamber (11 ), said rotor (10) being configured to be rotated by a motor around a vertical axis (V) at a speed providing at least 8.000 G at the inner surface of the cylindrical inner chamber (11 ) for the clarification of a liquid to be clarified separating solid particles and clarified liquid, said cylindrical inner chamber (11 ) having a lower opening (15) at its lower end concentric with the vertical axis (V) and surrounded by a rotor tubular wall (16) connected to a static tubular wall (40) through a low-friction bearing (30) concentric with said lower opening (15);

- a piston (20), provided with valves, located within the inner chamber (11 ) defining a lower inner chamber (12) and an upper inner chamber (13), said piston (20) being movable along the vertical axis (V) in a downward direction for an automatic discharge of solid particles settled and retained on the inner surface of the lower inner chamber (12) through said lower opening (15), and in a upward direction to return the piston (20) to the initial position, the piston (20) being driven by application of vacuum or pressurized fluid within the upper inner chamber (13) applied by a pumping system;

- a liquid injector (50) external to the rotor (10), placed below the lower opening (15), not vertically aligned with said lower opening (15) and directed upwards in an angle to project a liquid to be clarified into the lower inner chamber (12) through the lower opening (15) in a non-vertical direction;

characterized in that

the static tubular wall (40), which is in contact with the low-friction bearing (30), includes an inner passage (42) vertical and concentric with said vertical axis (V), said inner passage (42) having a diameter equal or bigger than the diameter of the lower opening (15) of the rotor (10), connecting the lower opening (15) of the inner chamber (11 ) with a solid particles outlet in a vertical direction;

said low-friction bearing (30) includes at least two overlapped rolling bearings (31 ), each roller bearing (31 ) including an inner ring (32), an outer ring (33) and roller elements (34) there between,

the outer rings (33) of said at least two roller bearings (31 ) are attached to an annular bearing box (35) said bearing box (35) being connected to the static tubular wall (40) by a plurality of compressed elastic members (41 ) which produce a centering force of the lower end of the rotor (10) correcting deviations.

2. Supercentrifuge according to any preceding claim wherein the rotor tubular wall (16) surrounding the lower opening (15) has an inner diameter of at least 20 mm up to at least 40 mm.

3. Supercentrifuge according to claim 2 wherein an annular member (36) is interposed between the inner rings (32), being the outer rings (33) urged to each other, or between the outer rings (33), being the inner rings (32) urged to each other.

4. Supercentrifuge according to claim 1 , 2 or 3 wherein the liquid injector (50) is at least partially integrated in a perforation of the static tubular wall (40), being said perforation connected with the inner passage (42).

5. Supercentrifuge according to claim 1 , 2, 3 or 4 wherein the compressed elastic members (41 ) urge the bearing box (35) in a direction parallel to the vertical axis (V).

6. Supercentrifuge according to claim 5 wherein the bearing box (35) is retained between an upper static wall (43) and lower static wall (44) of the static tubular wall (40).

7. Supercentrifuge according to claim 6 wherein the compressed elastic members (41 ) are placed between the bearing box (35) and said lower static wall (44), urging the bearing box (35) against the upper static wall (43) producing a friction force against the radial movement of said rotor tubular wall (16) regarding the static tubular wall (40).

8. Supercentrifuge according to claim 6 wherein the compressed elastic members (41 ) are placed between the bearing box (35) and said upper static wall (43), urging the bearing box (35) against the lower static wall (44) producing a friction force against the radial movement of said rotor tubular wall (16) regarding the static tubular wall (40).

9. Supercentrifuge according to any preceding claim wherein the compressed elastic members (41 ) are springs.

10. Supercentrifuge according to any preceding claim wherein the annular member (36) is interposed between the inner rings (32), and the annular bearing box (35) have at least two segments (37, 38) movable to each other in a direction parallel to the vertical axis (V), each segment (37, 38) having protrusions retaining one outer ring (33), being the distance between the protrusions defined by the relative position between the at least two segments (37, 38) of the annular bearing box (35).

11. Supercentrifuge according to any preceding claim wherein the annular member (36) is metallic.

12. Supercentrifuge according to any preceding claim wherein the annular member (36) has an angular extension inserted into the interspace existing between the inner and the outer rings (32, 33) of the rolling bearings (31 ).

13. Supercentrifuge according to any preceding claim wherein the liquid injector (50) is at least partially integrated in the static tubular wall (40) and projects the liquid to be clarified through an opening provided on the static tubular wall (40) facing the inner passage (42) of the static tubular wall (40).

14. Supercentrifuge according to any preceding claim wherein the rotor tubular wall (16) surrounding the lower opening (15) is an inner threaded tubular element different from the rotor (10) which is threaded around the lower opening (15) to the rotor (10).

15. Supercentrifuge according to any preceding claim wherein the high of the rotor tubular wall (16) in the vertical axis (V) direction is smaller than the inner diameter of the rotor tubular wall (16).