EP3601796B1 - Double-plate and double-cylinder pump - Google Patents

Description

The present invention relates to the field of pumps, in particular for high pressure and high flow rate pumping, in particular for drilling operations ranging from a few hundred meters to a few kilometers.

In the field of hydrocarbon production, it is currently observed that boreholes have to reach ever greater depths, which implies working with ever higher injection pressures. Oil companies and petroleum service companies therefore need very high pressure pumps (for example for the injection of drilling mud) to reach the required depths. These must also be reliable, economical, flexible and compact, in order to meet the ever more demanding demands of the energy sector.

In general, crankshaft pumps are the most widespread in all sectors of industry: capital goods, the oil, gas and agrifood industries, the automotive sector, construction (heating, wells, air conditioning, etc. water pumps, etc.) and more specifically for the treatment of water and waste (water and sanitation network). To date, pumps of this type have a limited number of pistons (of the order of 5), due to the limitations of the size of the crankshaft, which is also subjected to strong stresses and to sudden pressure variations which may intervene in the repression. These pumps therefore have limits in terms of power, pressure / flow rate (limited by "water hammers" generated by the sinusoidal pressure of the crankshaft), weight, efficiency and service life. In addition, they do not allow to have a variable displacement and therefore lack flexibility of use.

Another positive displacement pump technology is the barrel pump, also known as a plate pump. For this type of pump, the pistons are distributed in a circle, unlike crankshaft pumps where the pistons are aligned. The pumps designed with a barrel, operate using a plate system or a rotating barrel, which actuates the different pistons one after the other. When a piston is in the intake phase, the opposite piston is in the discharge mode, which provides a constant flow upstream and downstream of the pump. The distribution of the positions of the pistons with a guide by the barrel ensures a progressive distribution of the forces during the rotation of the shaft driven by the motor.

• Excellent rapport poids / puissance
• Très bon rapport qualité / prix
• Rendements mécaniques et volumétriques intéressants
• Possibilité de cylindrée variable en réglant l'inclinaison du plateau.

Mainly intended for pumping at lower pressure and flow (they are mainly used in pumping hydraulic oils), they offer many advantages:

• Excellent power-to-weight ratio
• Very good value for money
• Interesting mechanical and volumetric performance
• Possibility of variable displacement by adjusting the inclination of the plate.

• Les pompes à barillet fixe (figure 1) : dans cette configuration de pompe 1, où le barillet est fixe, c'est le plateau incliné 2 qui tourne (entraîné par l'arbre 5) afin de générer le mouvement des pistons 3 dans leurs chemises 4. La liaison entre les pistons 3 et le plateau 2 est alors assuré par des patins rotulés qui frottent sur le plateau 2. L'avantage ici est d'avoir une très faible inertie des pièces en rotation.
• Les pompes à barillet rotatif (figure 2) : au sein de la pompe 1, c'est le plateau 2 qui est fixe et le barillet 6 portant les pistons 3 est en rotation, assurant ainsi le mouvement des pistons 3 dans leurs chemises 4. La liaison piston 3 - plateau 2 est assurée de la même manière que pour la première configuration. L'avantage de cette architecture est que l'on peut aisément rendre le plateau réglable en inclinaison et ainsi avoir la possibilité de cylindrée variable. En revanche, l'inertie des pièces en rotation augmente de façon non négligeable puisque le barillet et l'ensemble des pistons sont mis en rotation.
• Les pompes à barillet avec plateau oscillant : le barillet est fixe dans cette architecture et l'on a deux plateaux, un premier plateau incliné est en rotation et transfère au second plateau uniquement le mouvement d'oscillation. Ainsi on peut lier les pistons au second plateau oscillant sans la nécessité d'éléments frottant, par exemple avec une bielle liée au piston et au plateau par des liaisons rotules. C'est la seule architecture adaptée au pompage haute pression du fait de l'absence d'éléments frottant (on en trouve d'ailleurs quelques-unes sur le marché de la géothermie). Elle offre également un excellent rendement mécanique.

In general, there are three main barrel pump architectures:

• Fixed barrel pumps ( figure 1 ): in this configuration of pump 1, where the barrel is fixed, it is the inclined plate 2 which rotates (driven by the shaft 5) in order to generate the movement of the pistons 3 in their liners 4. The connection between the pistons 3 and the plate 2 is then provided by ball-jointed pads which rub on the plate 2. The advantage here is to have a very low inertia of the rotating parts.
• Rotary barrel pumps ( figure 2 ): within the pump 1, it is the plate 2 which is fixed and the barrel 6 carrying the pistons 3 is in rotation, thus ensuring the movement of the pistons 3 in their liners 4. The piston 3 - plate 2 connection is ensured in the same way as for the first configuration. The advantage of this architecture is that we can easily make the tilt adjustable plate and thus have the possibility of variable displacement. On the other hand, the inertia of the rotating parts increases significantly since the barrel and all of the pistons are rotated.
• Barrel pumps with oscillating plate: the barrel is fixed in this architecture and there are two plates, a first inclined plate is in rotation and transfers to the second plate only the oscillation movement. Thus, the pistons can be linked to the second swash plate without the need for friction elements, for example with a connecting rod linked to the piston and to the plate by ball joints. It is the only architecture suitable for high pressure pumping due to the absence of friction elements (there are also some on the geothermal market). It also offers excellent mechanical performance.

In the case of such barrel pumps, the number and diameter of the pistons, as well as the inclination of the plate, condition the desired flow rate for the pump. In fact, when this operates, the pistons are in turn under high pressure, then at atmospheric pressure, so that the barrel / piston assembly impresses a load on the plate, the modulus of which is spatially heterogeneous. Indeed, with regard to the inlet pipe (atmospheric pressure) the load is relatively low, while with regard to the discharge pipe, the load is maximum.

Moreover, when barrel pumps, whether with rotating barrel, rotary or oscillating plate, are used in the field of very great depth drilling combining high pressure and high flow, the forces applied by a large number of pistons can generate considerable forces on the plate and the mechanical links between the components which, under extreme conditions, can generate a deformation of the plate or the breakage of a link. In addition, the connections between the pistons and the plate provided, for example, by ball-jointed pads, must be designed with a minimum of friction.

This imbalance of load applied to the plate can induce significant forces on the plate and on the mechanical links of the system, which leads to more bulky and more massive parts making the pump more energy intensive. In addition, the connections between the pistons and the plate, for example by ball-jointed pads, can be inconceivable if the applied load is too great.

We also know the patent CN 103696920 which describes a hydraulic pump comprising two plates and two barrels each with a set of pistons. According to this design, the plates are placed at the opposite ends of the pump and the barrels are in the center, the pump then having only one inlet and only one outlet. However, such a pump involves independently sizing each of the plates, which can be difficult in high pressure and high flow applications. In addition, such a configuration of the various elements of the pump does not allow a common adjustment of the inclination of the plates.

We know the document GB 827 589 A which describes a hydraulic pump comprising two pumping assemblies each comprising a plate, the plates being placed back to back and being inclined at the same angle with respect to a drive shaft.

We also know the document WO 00/50773 A2 which concerns a balanced double rotary pump, comprising two rotating barrels of cylinders and axial pistons, the axially facing pistons moving in the same direction.

We also know the document WO 2013/113109 A1 which describes a hydroelectric production system and a pump suitable for this system comprising two pumping assemblies each comprising a plate, the plates being placed back to back and being inclined at the same angle with respect to a drive shaft.

To overcome these drawbacks, the present invention relates to a double barrel, double plate and double inlet / outlet pump, the elements of each of the barrel-plate-inlet-delivery assemblies being distributed along a drive shaft so as to reduce the stresses on the plates and the various mechanical connections, and thus reduce the risk of breakage.

The device according to the invention

The invention relates to a barrel pump comprising at least one drive shaft, a first pumping assembly and a second pumping assembly, each pumping assembly being formed of elements comprising at least one plate, a cylinder block, a pipe. intake and a discharge pipe, said cylinder block comprising at least two compression chambers distributed circumferentially, at least two pistons being in translation respectively in said compression chambers of said cylinder block of each of said assemblies, said plate of each of said two assemblies being inclined relative to the axis of rotation of said drive shaft, said drive shaft generating a relative rotational movement between said plate and said cylinder block of each of said two assemblies.

According to the invention, said elements of said second set are distributed symmetrically with respect to said elements of said first set in a plane perpendicular to the axis of rotation of said drive shaft, and said plates of said two sets are interconnected at said plane. of symmetry.

According to the invention, said intake and discharge pipes of the same assembly are placed in symmetry with respect to the axis of said drive shaft.

According to one implementation of the invention, said plates of said two sets can be formed in a single block.

According to one embodiment option, said plates of said two assemblies can be interconnected by connecting means passing through said plane of symmetry.

According to one implementation, said connecting means may comprise a pivot connection arranged at a point located at the periphery of said two plates.

According to an alternative embodiment of the invention, said relative rotational movement may be a rotational movement of said plate of each of said assemblies.

According to another implementation option of the invention, said relative rotational movement may be a rotational movement of said cylinder block of each of said assemblies.

According to one implementation, the angle of inclination of said plate of each of said assemblies with respect to the axis of said drive shaft may be between 70 and 90 ° in absolute value.

Advantageously, said pump may include means for controlling the inclination of said plate of each of said assemblies with respect to the axis of said drive shaft.

Furthermore, the invention relates to a use of said barrel pump for a drilling operation, in particular for the injection of drilling mud into a wellbore.

Brief presentation of figures

• La figure 1, déjà décrite, illustre une pompe à barillet fixe selon l'art antérieur.
• La figure 2, déjà décrite, illustre une pompe à barillet rotatif selon l'art antérieur.
• La figure 3 illustre une pompe selon un premier mode de réalisation de l'invention.
• La figure 4 illustre une pompe selon un second mode de réalisation de l'invention.

Other characteristics and advantages of the device according to the invention will become apparent on reading the following description of non-limiting examples of embodiments, with reference to the appended figures and described below.

• The figure 1 , already described, illustrates a fixed barrel pump according to the prior art.
• The figure 2 , already described, illustrates a rotary barrel pump according to the prior art.
• The figure 3 illustrates a pump according to a first embodiment of the invention.
• The figure 4 illustrates a pump according to a second embodiment of the invention.

Detailed description of the invention

The present invention relates to a barrel pump. The purpose of the barrel pump is to pump a fluid (for example: water, oil, gas, drilling muds, etc.) by means of a linear displacement of several pistons. This type of pump has the advantage of being compact, of having interesting mechanical and volumetric efficiency, an excellent weight / power ratio. The barrel pump according to the invention may have a fixed barrel, a rotary barrel, or else a swash plate.

• un arbre d'entraînement : celui-ci est entraîné en rotation, par rapport au carter par une source d'énergie extérieure, notamment une machine motrice (par exemple thermique ou électrique), en particulier au moyen d'une transmission (par exemple une boîte de vitesses) ;
• un premier ensemble d'éléments de pompage, comprenant au moins un plateau, un bloc cylindre (appelé barillet), une conduite d'admission et une conduite de refoulement et un second ensemble d'éléments de pompage, comprenant au moins les mêmes éléments que le premier ensemble de pompage, les éléments de chacun de ces ensembles étant distribués le long de l'arbre d'entrainement. De manière classique, un bloc cylindre comporte au moins deux chambres de compression (appelés également chemises) réparties circonférentiellement (en d'autres termes les chambres de compression sont réparties selon un cercle), et au moins deux pistons en translation respectivement dans les chambres de compression, la translation des pistons au sein des chambres de compression réalisent le pompage du fluide. Les plateaux de chaque ensemble peuvent avoir sensiblement la forme de disque. Toutefois, les plateaux peuvent avoir n'importe quelle forme. Seules les chambres de compression (et les pistons) sont réparties sur un cercle. Par ailleurs, de manière classique, le fluide à pomper passe par la conduite d'admission d'un des ensembles, entre dans une chambre de compression de cet ensemble, est comprimé puis refoulé de la pompe par la conduite de refoulement de cet ensemble.

The barrel pump according to the invention generally comprises a casing, and within a casing comprises:

• a drive shaft: this is driven in rotation, relative to the housing by an external energy source, in particular a prime mover (for example thermal or electric), in particular by means of a transmission (for example a gearbox) ;
• a first set of pumping elements, comprising at least a plate, a cylinder block (called a barrel), an inlet pipe and a discharge pipe and a second set of pumping elements, comprising at least the same elements as the first pumping assembly, the elements of each of these assemblies being distributed along the drive shaft. Conventionally, a cylinder block comprises at least two compression chambers (also called liners) distributed circumferentially (in other words the compression chambers are distributed in a circle), and at least two pistons in translation respectively in the pressure chambers. compression, the translation of the pistons within the compression chambers perform the pumping of the fluid. The trays of each set may have substantially the shape of a disc. However, the trays can have any shape. Only the compression chambers (and the pistons) are distributed in a circle. Furthermore, conventionally, the fluid to be pumped passes through the inlet pipe of one of the assemblies, enters a compression chamber of this assembly, is compressed and then discharged from the pump via the discharge line of this assembly.

• le plateau de chacun des deux ensembles est incliné par rapport à l'axe de rotation dudit arbre d'entrainement. L'inclinaison des plateaux influe sur la course des pistons dans les chambres de compression et détermine ainsi la cylindrée de la pompe ;
• ledit arbre d'entrainement induit un mouvement relatif en rotation entre ledit plateau et ledit bloc cylindre de chacun desdits deux ensembles. Ainsi, selon l'invention, l'arbre d'entrainement peut tout aussi bien entrainer en rotation le plateau que le barillet ;
• la distribution des éléments du second ensemble est en symétrie par rapport à celle des éléments du premier ensemble selon un plan perpendiculaire à l'axe de rotation de l'arbre d'entrainement, les plateaux des deux ensembles étant reliés entre eux au niveau du plan de symétrie. Ainsi, la pompe à barillet selon l'invention comporte, d'une extrémité à une autre, des premières conduites d'admission et de refoulement, un premier barillet, un premier plateau, un deuxième plateau, un deuxième barillet, et des deuxièmes conduites d'admission et de refoulement, le tout étant traversé par un arbre d'entraînement.

Furthermore, according to the invention:

• the plate of each of the two sets is inclined relative to the axis of rotation of said drive shaft. The inclination of the plates influences the stroke of the pistons in the compression chambers and thus determines the displacement of the pump;
• said drive shaft induces a relative rotational movement between said plate and said cylinder block of each of said two assemblies. Thus, according to the invention, the drive shaft can equally well drive the plate in rotation as the barrel;
• the distribution of the elements of the second set is symmetrical with respect to that of the elements of the first set along a plane perpendicular to the axis of rotation of the drive shaft, the plates of the two sets being connected between them at the level of the plane of symmetry. Thus, the barrel pump according to the invention comprises, from one end to another, first intake and delivery pipes, a first cylinder, a first plate, a second plate, a second barrel, and second pipes. inlet and outlet, the whole being crossed by a drive shaft.

Thus, according to the invention, the plates of each of the pumping assemblies are inclined at the same angle, in absolute value, and face each other. The forces applied to each of the plates by the translational movement of the pistons in each of the compression chambers of each of the cylinder blocks have the same standard but are in the opposite direction. The plates of the two assemblies being interconnected, this configuration makes it possible to reduce the axial loads supported by the plates and by the mechanical plate-piston connections.

According to the invention, the intake pipe and the discharge pipe of each of the pumping assemblies are placed in symmetry with respect to the axis of the drive shaft, or in other words the intake and discharge pipes. of the same set face each other with respect to the drive shaft. Thus, the balance of the axial forces at the level of the plate can be balanced more easily.

According to a first variant embodiment of the invention, the drive shaft drives the plates of each of the two assemblies in rotation, the rotational movement being considered with respect to the pump casing. Thus, this first variant describes a fixed barrel pump. According to this variant, the rotary plate of a given set is inclined relative to the drive shaft at the same angle of inclination as the plate of the other set, each of the plates being moreover driven in rotation by the 'drive shaft.

According to a second alternative embodiment of the invention, the drive shaft rotates the cylinder block or barrel of each of the two pumping assemblies, the rotational movement being considered relative to the pump casing. Thus, this second variant describes a pump with a rotating barrel. According to this variant, the plates of each pumping assembly are fixed and inclined by the same angle of inclination in absolute value. For this variant, the rotating barrel of each pumping assembly induces a translational movement of the pistons in their respective compression chamber, via the connection of the pistons with the plate of their respective pumping assembly.

According to a third variant of implementation of the invention, each of the two pumping assemblies comprises at least two plates parallel to each other (and therefore both inclined at the same angle at the same time): a driven rotary plate in rotation by the drive shaft, and a swash plate driven in oscillation by the turntable, the swash plate being in a pivot connection along the axis of the turntable relative to the turntable. Thus, according to this variant, the rotary plate transmits only the oscillation movement to the swash plate and does not transmit the rotational movement. According to this design, the pistons of each of the compression chambers of a given pumping assembly are driven by the swash plate of this set, for example by means of connecting rods (the connecting rods connect, by means of ball joints, the swash plate and the pistons so as to transform the oscillation movement into translational movement of the pistons), and the translation of the pistons within the compression chambers perform the pumping of the fluid. According to this variant of the invention, the rotary plate can be driven by the drive shaft by means of a finger ball joint, the position of the finger ball joint determining the inclination of the two plates (rotary and oscillating) by compared to the drive shaft. It will be recalled that a ball joint with a finger is a connection between two elements (here the drive shaft and the rotary plate), which has four degrees of connection and two degrees of relative movement; only two relative rotations are possible, the three translations and the last rotation being linked. In general, it is a ball joint with a finger preventing rotation.

According to one embodiment of the invention which can be applied for any one of the variants described above, the plates of the two sets are formed from a single block. This makes it possible to reduce the fragility of the contact between the two plates, and therefore to improve the reliability of the pump according to the invention.

According to one embodiment of the invention which can be applied for any one of the variants described above, the plates of the two sets are interconnected by connecting means. Advantageously, the connecting means of the plates of the two assemblies comprise a pivot connection placed at a point situated substantially at the periphery of the two plates. Conventionally, the pivot connections are formed by bearings or bearings, promoting the relative movement of the elements. This pivot connection allows adjustment of the inclination of the plates of each pumping assembly. Preferably, the connecting means of the plates of the two assemblies comprise, in addition to a pivot connection, at least one spacer element of variable length placed so as to reinforce the assembly formed by the two inclined plates and connected to each other by the pivot link.

Advantageously, the inclination of the plate (s) of each of the assemblies is continuously adjustable by means for controlling the inclination of the plates, which allows a variable displacement. Indeed, the inclination of the plates influences the stroke of the pistons. Thus, the pump according to this variant allows good flexibility thanks to the continuous variation of the unit displacement. In addition, the pump according to this fourth variant allows the pump to be gradually put into operation: for example, during start-up, the angle of inclination may be small, and subsequently, it may be increased depending on the desired conditions. (fluid flow and pressure). This increases the reliability of the pump. According to an exemplary embodiment, the means for controlling the inclination of the plates interact with the connecting means connecting the plates of the two pumping assemblies. According to one embodiment of the invention in which the connecting means comprise a pivot connection and a variable height spacer element as described above, the means for controlling the inclination of the plates cooperate with the means of adjustment of the height of the spacer element, so as to increase or decrease the spacing between the plates. According to one embodiment of the invention, the means for controlling the inclination of the plates is provided by a worm.

According to one implementation of the invention, the pump according to the invention may include, in each cylinder block, a number of pistons between three and fifteen, preferably between five and eleven. Thus, a high number of pistons provides a continuous flow upstream and downstream of the pump.

According to one embodiment of the invention which can be applied to any one of the variants described above, the angle of inclination of the plate (s) (a rotary plate in the case of the first variant, a fixed plate in the case of the second variant, or a rotating plate and a swash plate in the case of the third variant) of each set of pumping elements is between 70 ° and 90 ° in absolute value with respect to the axis of the 'drive shaft. In other words, the plate (s) of one of the assemblies is inclined between 0 and 20 ° relative to the plane of symmetry of the first and second pumping assemblies, and the plate (s) of the other assembly is inclined between -20 ° and 0 with respect to this same plane of symmetry.

The figure 3 presents, in an illustrative and non-limiting manner, a section passing through the axis of rotation of the drive shaft of a barrel pump according to one embodiment of the invention. The pump 1 according to this illustrated embodiment is a pump of the rotary barrel type. This pump comprises a drive shaft 12, which is rotatably mounted in a housing (not shown). The rotation of the drive shaft 12 is performed by an external source, not shown, for example an electric machine and a gearbox. The pump 1 comprises two pumping assemblies distributed symmetrically with respect to one another along a plane of symmetry perpendicular to the axis of rotation of the shaft. The first (respectively second) assembly comprises a fixed plate 2 (respectively 3), a rotating barrel (or cylinder block) 4 (respectively 5), an inlet pipe 8 (respectively 9), a discharge pipe 10 (respectively 11 ). In this figure, are shown two pistons 6, 7 per cylinder block, these pistons being arranged within their respective compression chamber and being connected to their respective plate by a ball joint. The drive shaft 12 drives the barrel 4, 5 of each pumping assembly. The plates of each of the pumping assemblies are inclined relative to a plane perpendicular to the axis of rotation of the drive shaft by the same angle of inclination in absolute value. According to this implementation of the invention, the fixed plates 2, 3 of each set of pumping elements are linked together by a pivot connection 13 and by a spacer element 14, the length of which can be variable. Thus, the plates facing each other directly and undergoing the same stress but in opposite directions, it is clear that the axial loads on the plate and on the mechanical plate-piston connections are reduced.

The figure 4 presents a variant of the pump as presented in figure 3 . In fact, the pump according to this non-limiting example of the embodiment of the pump according to the invention comprises, in addition, means for controlling the inclination of the plates 15 of each pumping assembly, in the form of an endless screw controlling the 'variable length spacer element.

The invention also relates to the use of the pump according to the invention for a drilling operation, in particular for the injection of drilling mud into a wellbore. Indeed, the pump according to the invention making it possible to balance the distribution of the axial loads, it is possible to size a pump according to the invention so as to withstand high pressures and high flow rates. Indeed, this improvement in the distribution of the axial loads can make it possible to multiply the number of pistons to achieve the flow rate. desired, and with a smaller radial size (more pistons and smaller diameter). For example, the pump according to the invention can be sized to operate up to pressures of the order of 1500 bars, that is to say 150 MPa. In addition, the pump according to the invention can be sized to operate at flow rates varying from 30 to 600 m ³ / h.

Claims (10)

1. Wobble pump (1) comprising at least one drive shaft (12), a first pumping assembly and a second pumping assembly, each pumping assembly being formed by elements comprising at least one plate (2, 3), a cylinder block (4, 5), an intake duct (8, 9) and a discharge duct (10, 11), said cylinder block (4, 5) comprising at least two compression chambers distributed circumferentially, at least two pistons (6, 7) being in translation mode respectively in said compression chambers of said cylinder block (4, 5) of each of said assemblies, said plate (2, 3) of each of said two assemblies being inclined with respect to the axis of rotation of said drive shaft (12), said drive shaft (12) generating a relative rotational movement between said plate (2, 3) and said cylinder block (4, 5) of each of said two assemblies, characterized in that said elements of said second assembly are distributed symmetrically with respect to said elements of said first assembly on a plane at right angles to the axis of rotation of said drive shaft (12), and in that said plates (2, 3) of said two assemblies are linked together at said plane of symmetry, and in that said intake (8, 9) and discharge (10, 11) ducts of a same assembly are placed in symmetry with respect to the axis of said drive shaft (12).
2. Pump according to Claim 1, wherein said pump (1) comprises control means (15) for controlling the inclination of said plate (2, 3) of each of said assemblies with respect to the axis of said drive shaft (12) .
3. Pump according to Claim 1, wherein said plates (2, 3) of said two assembles are formed in a single block.
4. Pump according to one of Claims 1 and 2, wherein said plates (2, 3) of said two assemblies are linked to one another by link means (13, 14) passing through said plane of symmetry.
5. Pump according to Claim 4, wherein said link means (13, 14) comprise a pivot link (13) positioned at a point situated at the periphery of said two plates (2, 3).
6. Pump according to one of the preceding claims, wherein said relative rotational movement is a rotational movement of said plate (2, 3) of each of said assemblies.
7. Pump according to Claim 6, wherein each of said assemblies additionally comprises an oscillating plate, said oscillating plate of each of said assemblies being pivotingly linked with said plate in rotation (2, 3) of said same assembly.
8. Pump according to one of Claims 1 to 5, wherein said relative rotational movement is a rotational movement of said cylinder block (4, 5) of each of said assemblies.
9. Pump according to one of the preceding claims, wherein the angle of inclination of said plate (2, 3) of each of said assemblies with respect to the axis of said drive shaft (12) is between 70 and 90° in absolute terms.
10. Use of said wobble pump according to one of the preceding claims for a drilling operation, in particular for the injection of drilling mud in a borehole.

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