Compression or pumping device comprising a means for reducing the tangential speed of the stream of play

Abstract

The present invention relates to a fluid compression or pumping device, preferably for multiphase fluids, comprising a stator, a rotor, and a rotor shaft, each rotor being fixed to the rotor shaft, each rotor comprising blades extending substantially radially with respect to the longitudinal axis, and at least one being a shrouded rotor. The pump includes a gap between a shroud of the shrouded rotor and the housing, allowing flow through the gap in a direction opposite to the fluid flow through the shrouded rotor. Furthermore, the stator includes at least one means (35) for reducing the tangential velocity of the fluid arriving from the gap flow, positioned axially opposite the shroud of the shrouded rotor and / or said gap, upstream of the shrouded rotor.

Description

Technical field

[0001] The invention relates to the field of fluid compression or pumping devices, more particularly to the compression or pumping of multiphase fluids. The invention more specifically relates to a multiphase pump that can be used, in particular, in petroleum applications or for injecting and / or storing fluid in a geological reservoir.

[0002] A fluid compression or pumping device typically comprises one or more compression stages. Each compression stage includes at least one moving part with a rotating wheel (this moving part is also called a rotor or impeller) and at least one stationary part. The stationary part may include a stator (also called a stator or diffuser). These components may be housed within a casing of the compression device, with the stationary part also comprising the casing. The stator may be integrated into the casing.

[0003] The stator can be positioned upstream and / or downstream of a rotating wheel. When located downstream, its role is to straighten the fluid flow exiting the wheel, the flow being driven into rotation by the rotating wheel. Its purpose is to supply the next compression stage (another rotating wheel downstream of the stator) or to utilize the fluid flow directly. Such a stator serves to convert the kinetic energy of the fluid into potential energy. To achieve this, the stator typically includes blades.

[0004] The stator is stationary, while the rotating wheels are mobile, rotating around a longitudinal axis. The purpose of these rotating wheels is to increase the kinetic and potential energy of the fluid. They are generally attached to a rotating shaft and include blades.

[0005] More specifically, the invention relates to a pump intended to pump a fluid, for example a multiphase fluid. Previous technique

[0006] In the field of multiphase pumps, "shrouded rotor" technology has been under development for several years. For example, US patent applications 2011 / 0 280 706 A1 and EP 3 536 975 A1 concern multiphase pumps with shrouded rotors. This technology involves adding an external shroud that encloses the rotor blades. This rotor shroud improves the mechanical stability of the assembly. The frictional forces induced by the flow between this shroud and the external casing dampen vibrations.

[0007] However, the fluid flowing in the gap between the fairing and the housing moves in the opposite direction to the fluid passing through the rotor blades, constituting a secondary flow. Furthermore, this secondary flow, also called gap flow between the fairing and the housing, has a high tangential velocity, known as "swirl," which disrupts the main flow of fluid entering the rotor. In other words, "gap flow" refers to flow within the gap between two assembled mechanical parts, in this case, between the fairing and the housing.

[0008] Indeed, the fluid exiting the swashplate flow mixes with the fluid arriving from elsewhere towards the rotor inlet (passing through the blades). This mixing directly impacts the angle of incidence of the fluid entering the rotor and generates a reduction in performance.

[0009] There [ Fig.1] illustrates the impact of the tangential velocity resulting from the clearance flow on the fluid arriving at the leading edge of the blades 20. The [ Fig.1 ] represents a view developed in a longitudinal plane of the rotor.

[0010] U1 represents the blade velocity at the leading edge, U2 the blade velocity at the trailing edge. V1 represents the absolute fluid velocity at the leading edge and V2 the absolute fluid velocity at the trailing edge.

[0011] Ω corresponds to the rotational speed of the rotor.

[0012] The vector W1 is the relative velocity vector resulting from the velocities V1 and U1 at the leading edge; the vector W2 is the relative velocity vector resulting from the velocities V2 and U2 at the trailing edge. The angle β 2 is the angle formed between the vector W 2 and the transverse plane represented by dotted lines at the vanishing edge.

[0013] The work w per unit mass generated by such a machine can be written, using Euler's equation, in the form: w = U 2 → . V 2 → − U 1 → . V 1 → = U 2 V θ 2 − U 1 V θ 1 = r 2 Ω V θ 2 − r 1 Ω V θ 1

[0014] With V θ 1. The absolute tangential velocity at the leading edge V θ 2 the absolute tangential velocity at the trailing edge r 1 , r 2 the radii considered at the leading edge and trailing edge respectively.

[0015] If the fluid arriving at the leading edge were perpendicular to the transverse plane (represented by the dashed line), the velocity V1 would be horizontal in the figure (as represented by the dashed arrow). However, here, the velocity V1 forms a non-zero angle with the horizontal, as represented by the solid arrow. This is due to the angle δβdue to the tangential velocity of the fluid arriving from the game flow, as explained previously. This fluid exiting the game flow disturbs the fluid arriving towards the blades. This phenomenon is known as "pre-swirl," meaning "pre-vortex" or "pre-rotation." Thus, the angle of incidence of the fluid relative to the transverse plane (orthogonal to the longitudinal axis), which would be β 1 without the impact of the game flow is modified in β 1 + δβ Changing the angle of incidence of the fluid directly impacts the performance of the turbomachine.

[0016] US patent application 2014 / 0 205 444 A1 proposes anti-vortex devices positioned within the gap to limit dynamic rotor instabilities. However, this does not prevent tangential velocity at the outlet of the fluid from the gap flow.

[0017] We are also aware of patent application US2015 / 211543 A1, which proposes anti-vortex devices, positioned at the flow point between the fairing and the housing, to reduce tangential speed and rotor instabilities. However, this does not prevent tangential speed at the outlet of the backflow fluid.

[0018] Patent application WO 2014 / 153 345 A1 relates to a pump with a balancing piston, which does not include impellers. This balancing piston serves to counteract the thrust force in multiphase pumps with high differential pressures. An anti-vortex device is positioned between the balancing piston and the housing to stabilize the pressure field, particularly when the pump has a significant differential pressure.

[0019] Patent application EP 3 913 227 A1 relates to a multiphase pump with a shrouded rotor. Anti-vortex devices are provided on the stator at the clearance flow or at the fluid inlet to dampen vortices. However, this does not prevent a tangential velocity at the fluid outlet of the clearance flow.

[0020] The object of the invention is to reduce or eliminate the tangential velocity of the fluid exiting the clearance flow of a shrouded rotor in order to increase the performance of the device, while ensuring mechanical stability and reducing the vibration of the device. Summary of the invention

[0021] The invention relates to a fluid compression or pumping device, preferably for multiphase fluid, comprising a fixed part, at least one rotor and a rotor shaft, each rotor being fixed to the rotor shaft, the rotor shaft being configured to be driven in rotation about a longitudinal axis, each rotor comprising blades extending substantially radially with respect to the longitudinal axis and at least one of the at least one rotor being a shrouded rotor comprising a circumferential shroud connecting the peripheral radial ends of the blades, the fixed part comprising at least one stator and at least one external portion surrounding each rotor, the device comprising a clearance between the external surface of each circumferential shroud of the shrouded rotor and the internal surface of the external portion surrounding this shrouded rotor, allowing clearance flow in a direction opposite to the flow of the fluid through this shrouded rotor.In addition, the stator upstream of the shrouded rotor includes a means for reducing the tangential velocity of the fluid arriving from the clearance flow, each reduction means being positioned axially opposite the shroud of the shrouded rotor and / or said clearance, upstream of the shrouded rotor in the direction of the flow through the shrouded rotor.

[0022] Preferably, the device comprises several stators and / or several rotors, preferably with the stators and rotors following each other alternately along the longitudinal axis.

[0023] Advantageously, each rotor comprises at least one set of blades, each set of blades comprising blades regularly distributed around the rotor shaft, preferably each rotor comprises at least two sets of blades following each other longitudinally.

[0024] Preferably, the device comprises several shrouded rotors.

[0025] Advantageously, the circumferential fairing of the shrouded rotor extends longitudinally over a length that covers at least one of the blade sets, preferably all the blade sets, and even more preferably, the length of the fairing is equal to the length of the rotor concerned.

[0026] Preferably, the circumferential fairing is circumferentially complete or circumferentially incomplete with at least one opening.

[0027] According to one embodiment of the invention, the reduction means is formed by cavities in the stator to reduce the tangential velocity of the fluid arriving from the play flow, the cavities being opposite the outlet of the fluid from the play flow, the cavities being distributed circumferentially on the stator and separated from each other by interfaces, preferably some of the interfaces comprising extensions of stator blades.

[0028] Preferably, the cavities include crenellated or triangular section grooves developed in the circumferential direction.

[0029] Advantageously, the number of cavities between two successive rotor blades opposite the reduction means is between 3 and 10.

[0030] Advantageously, the ratio between the height of the cavities and the height of the blades is between 10% and 40%, preferably between 15% and 25%.

[0031] Preferably, the ratio between the depth of the cavities and the longitudinal length of the rotor is between 2% and 20%, preferably between 5% and 10%.

[0032] The invention also relates to a multiphase pump comprising a device according to one of the variants or combinations of variants described above.

[0033] The invention also relates to the use of the device as described according to one of the variants or combinations of variants described above or of the multiphase pump described above, for the extraction of oil or gas from a geological reservoir and / or for the injection of a fluid into a geological reservoir. List of figures

[0034] Other features and advantages of the device and / or pump according to the invention will become apparent from the following description of non-limiting examples of embodiments, with reference to the figures attached and described below. [ Figure 1 ] There [ Fig.1 ] (already described) represents the composition of the velocity components of the fluid arriving on the rotor blades of the device according to the prior art. [ Figure 2 ] There [ Fig.2] represents an embodiment of a compression or pumping device according to the invention. [ Figure 3 ] There [ Fig.3 ] represents different compositions of the shrouded rotor of the compression or pumping device according to the invention. [ Figure 4 ] There [ Fig.4 ] represents the effect of the fluid arriving from the clearance flow in the means of reducing the tangential velocity of a compression or pumping device according to the invention. [ Figure 5 ] There [ Fig.5 ] represents different variants of means for reducing the tangential velocity of a compression or pumping device according to the invention. [ Figure 6 ] There [ Fig.6 ] represents a first example of a stator with a means of reducing the tangential speed of a compression or pumping device according to the invention. [ Figure 7 ] There [ Fig.7] represents a second example of a stator with a means for reducing the tangential speed of a compression or pumping device according to the invention. [ Figure 8 ] There [ Fig.8 ] represents a comparison of fluid velocities via CFD simulations around an unshod rotor according to the prior art (a)), around a shod rotor according to the prior art (b)) and around a shod rotor and a stator comprising a means for reducing the tangential velocity of a compression or pumping device according to the invention (c)). [ Figure 9 ] There [ Fig.9 ] represents photographs of a prior art stator (a) and a stator comprising a means for reducing tangential velocity (b). [ Figure 10 ] There [ Fig.10 ] represents the composition of the velocity components of the fluid arriving at the rotor blades. [ Figure 11 ] There [ Fig.11] represents an example of an incomplete circumferential fairing of a compression or pumping device according to the invention. Description of the method of realization

[0035] The invention relates to a device for compressing or pumping fluid, preferably multiphase fluid. A "multiphase fluid" is defined as a fluid comprising at least two phases: for example, two separable liquid phases, a gaseous phase and a liquid phase, or a liquid phase and a solid phase. Of course, a multiphase fluid can comprise more than two phases.

[0036] The device of the invention comprises at least one stator, at least one rotor, and a rotor shaft. Each rotor is fixed to the rotor shaft, which is itself configured to rotate about a longitudinal axis. Consequently, the rotor shaft can drive each rotor in rotation, enabling the pumping or compression of the fluid.

[0037] Each rotor comprises blades extending substantially radially with respect to the longitudinal axis. Thus, the fluid arrives substantially along the longitudinal axis and is pumped or compressed as it passes through the rotor, between the rotor blades.

[0038] Furthermore, at least one rotor is a shrouded rotor comprising a circumferential shroud connecting the radial outer edges of the blades. In other words, the circumferential shroud forms an external casing of the shrouded rotor, integral to it. This external casing surrounds the outer edges of the blades. This circumferential shroud can, in particular, be formed by a cylindrical shroud with an annular cross-section or a tubular shroud.

[0039] For the purposes of this description, the internal and external ends are relative to each other, with the internal end being relatively closer to the longitudinal axis than the external end (also called the peripheral end).

[0040] The circumferential fairing can be circumferentially complete or incomplete (the latter referring to a partial ring). A complete circumferential fairing means a fairing that extends circumferentially all the way around the rotor in a single piece, without any openings, whereas an incomplete circumferential fairing does not extend circumferentially all the way around the rotor: an incomplete circumferential fairing may have at least one opening (preferably a small one) in the fairing. When the incomplete circumferential fairing has only one opening, it can be in a single piece. When the incomplete circumferential fairing has at least two openings, it can be in at least two separate parts separated by the openings.

[0041] The fixed part includes at least one external portion (a part of the housing) surrounding each rotor. This external portion protects the user from the rotating parts and also contains the fluid flowing through the device.

[0042] The device according to the invention also includes a gap between the outer surface of the circumferential shroud of the shrouded rotor (of each shrouded rotor when several rotors are shrouded) and the inner surface of the outer portion of the stator surrounding each shrouded rotor. This gap forms a substantially annular space between the shrouded rotor and the housing. This gap allows the rotor to rotate even when the housing is stationary. However, it results in a flow of fluid in the opposite direction to the main flow of fluid through each shrouded rotor (i.e., the flow of fluid passing through the blades of the shrouded rotor).

[0043] The fixed part may include a housing (with the various external portions surrounding each rotor) and at least one stator.

[0044] In addition, the stator upstream of the shrouded rotor (of each shrouded rotor when the device includes several shrouded rotors), in the direction of the main flow of the fluid in the shrouded rotor, includes a means for reducing the tangential velocity of the fluid arriving from the clearance flow, each reduction means being positioned axially opposite the circumferential shroud of the shrouded rotor concerned and / or said clearance, upstream of the shrouded rotor in the direction of the flow through the rotor concerned (i.e. through the rotor blades).

[0045] By "the stator upstream of the shrouded rotor, in the direction of the main flow of the fluid in the shrouded rotor", we mean the stator which precedes the rotor in the direction of the main flow, the one which is just in front of the rotor in question.

[0046] By reducing the tangential velocity of the fluid exiting the clearance flow and mixing with the fluid entering the rotor, the impact of this velocity on the fluid entering the rotor can be limited. This therefore improves the performance of the compression or pumping device according to the invention.

[0047] Furthermore, by positioning the reduction gear opposite the fairing and / or the clearance, disturbances to the fluid entering the rotor are minimized, thus reducing vibrations. This also helps to improve the device's lifespan.

[0048] Advantageously, the device can comprise several stators and / or several rotors, preferably with the stators and rotors arranged alternately along the longitudinal axis. This allows for multiple compression or pumping stages to improve the device's performance.

[0049] According to one variant of the invention, each rotor can comprise at least one series of blades, each series of blades comprising blades regularly distributed around the rotor shaft on the same transverse plane.

[0050] According to one aspect of the invention, each rotor may comprise at least two sets of blades, said at least two sets of blades being arranged longitudinally. By using at least two sets of blades for each rotor, the compression or pumping performance can be improved.

[0051] By "transverse plane", we mean a plane that is substantially perpendicular to the longitudinal axis.

[0052] At least one of the rotor blade sets may be helical in shape, and preferably the blade sets of each rotor are helical in shape.

[0053] The device may include several shrouded rotors. In this case, each stator preceding just upstream of each shrouded rotor in the direction of the main flow of the fluid in the shrouded rotor concerned may include a means for reducing the tangential velocity of the fluid arriving from the gap flow, each reduction means being positioned axially opposite the circumferential shroud of the shrouded rotor concerned and / or said gap, upstream of the shrouded rotor concerned in the direction of the main flow through the shrouded rotor concerned.

[0054] According to one aspect of the invention, the circumferential shroud of the shrouded rotor can extend longitudinally over a length sufficient to cover at least one set of blades, preferably all sets of blades, and, even more preferably, the length of the shroud is equal to the length of the rotor in question. In other words, the shroud can be total when its length is equal to that of the rotor in question, or partial when its length is strictly less than that of the rotor in question. A partial shroud allows for the maintenance of end-clearance flow within the rotor, generating mixing and enabling the homogenization of a liquid / gas flow. This is achieved at the cost of a reduction in the damping generated by the shroud, as the area of ​​high fluid friction (shroud / casing) is reduced.

[0055] Preferably, each reduction means can be formed by cavities in the stator to reduce the tangential velocity of the fluid arriving from the backflow. These cavities can be located opposite the backflow fluid outlet (i.e., opposite the backflow and / or the shroud, upstream of the rotor in the direction of the flow within the rotor). The cavities are thus as close as possible to the backflow fluid outlet. This positioning minimizes fluid disturbances caused by the fluid exiting the backflow. The cavities allow for fluid recovery and stop (or limit) the tangential velocity of the fluid exiting the backflow.

[0056] The cavities can be distributed circumferentially around the stator to ensure uniform tangential velocity reduction around the rotor, thus limiting vibrations. The cavities can be separated from each other by interfaces. These interfaces can, for example, form radial walls between the cavities. The increased number of cavities and interfaces generates fluid vortices within the cavities, which significantly reduces the tangential velocity of the fluid exiting the clearance flow before it mixes with the fluid entering the rotor.

[0057] Preferably, some of the interfaces may include extensions of the stator blades (more precisely, the blades of the stator wheel).

[0058] Preferably, the cavities may include crenellated grooves (rectangular in cross-section in a developed plane) or triangular grooves developed in the circumferential direction. Thus, opposite and upstream (in the direction of fluid flow in the rotor blades) of the gap and / or shroud, the stator may include an annular portion comprising crenellated or triangular grooves, separated by interfaces such as radial walls. This arrangement reduces the tangential velocity of the fluid exiting the gap flow.

[0059] When the cavities include triangular grooves, preferably right-angled, the depth d sB and the spacing w sB can be defined to satisfy the following equation where γ corresponds to the angle formed by the fluid exiting the clearance flow with respect to a plane orthogonal to the longitudinal direction: tan γ = w SB d SB

[0060] This allows for optimization of the reduction of tangential speed.

[0061] If we wish to fix the depth d sB, the spacing w sB between the cavities can be determined as a function of the number of cavities. N SB around the stator and depending on the number of stator blades N s and the outer radius R ext of the stator (radius of the cross-section through which the fluid passes in the stator) from the following equation: N SB = 2 π R ext N S w SB

[0062] Alternatively, if we want to fix the spacing w sB between the cavities, we can calculate the depth d sB.

[0063] Advantageously, the number of cavities between two successive rotor blades opposite the reduction means can be between 3 and 10. This configuration allows a sufficient reduction of the tangential speed.

[0064] According to one aspect of the invention, the ratio between the height of the cavities and the height of the blades can be between 10% and 40%, preferably between 15% and 25%.

[0065] Advantageously, the ratio between the depth of the cavities and the longitudinal length of the rotor can be between 2% and 20%, preferably between 5% and 10%.

[0066] These different configurations offer a good compromise between sufficient reduction of tangential velocity and complexity of implementation.

[0067] The invention also relates to a multiphase pump for a multiphase fluid, comprising a device as described according to one of the variants or combinations of variants of the present description.

[0068] The invention further relates to the use of the device as described according to one of the variants or combinations of variants described in this description or of the multiphase pump described previously, for the extraction of oil or gas from a geological reservoir and / or for the injection and / or storage of a fluid in a geological reservoir.

[0069] There [ Fig.2 ] illustrates, schematically and without limitation, an example of a fluid compression or pumping device according to the invention.

[0070] Diagram a) represents an overview and diagram b) represents a zoom at the level of the play flow and the fairing.

[0071] The fluid compression or pumping device according to the invention comprises a rotor 22, which is a shrouded rotor, and a fixed part. The fixed part comprises an external portion 30 (which forms part of the housing) surrounding the shrouded rotor 22 and a stator with a stator wheel 31 (the stator wheel 31 comprising stator blades).

[0072] The shrouded rotor 22 here comprises a series of helical blades 20, but could comprise several series without departing from the scope of the invention. The shrouded rotor 22 also includes a circumferential shroud 21a that surrounds the blades. Here, the shroud 21a is a full shroud that surrounds the series of blades and whose axial length is equal to the axial length of the rotor. However, the shroud could alternatively be a partial shroud.

[0073] The device includes a gap between the external surface of the fairing 21a and the internal surface of the external portion 30. This gap results in a flow through the gap 23a. Indeed, a portion of the fluid exiting the shrouded rotor 22 (having passed through the blades 20 of the rotor 22) is drawn into the gap and flows in the opposite direction to the main flow 24 of the fluid passing through the rotor 22.

[0074] The stator here includes, opposite the shroud 21a and the gap, a tangential velocity reduction means 35 to reduce the velocity of the fluid exiting the gap flow. This reduction means is positioned just upstream of the shrouded rotor 22, in the direction of the main fluid flow in the shrouded rotor 22, i.e., in the blades 20 of the shrouded rotor.

[0075] The fluid exiting the clearance flow 23a enters the tangential velocity reduction means 35, which limits the tangential velocity of this fluid. Through this mechanism, the fluid entering the rotor via the flow 24 is less disturbed by the fluid exiting the clearance flow.

[0076] There [ Fig.3 ] illustrates, schematically and without limitation, three variants of a fluid compression or pumping device according to the invention.

[0077] In each of the three variants, the fluid compression or pumping device comprises a shrouded rotor 22 and a fixed part. The fixed part includes an external portion 30 (forming part of the housing) that surrounds the rotor 22 and a stator with a stator wheel 31 (which includes stator blades).

[0078] The shrouded rotor 22 here comprises a series of helical blades 20, but could comprise several series of blades without departing from the scope of the invention.

[0079] In diagram a), the rotor also includes a circumferential fairing 21a that surrounds the blades. The fairing 21a is a full fairing that surrounds the blade assembly and whose axial length is equal to the axial length of the rotor. The fairing 21a generates a clearance flow 23a between the fairing 21a and the outer portion 30.

[0080] In diagram b), the shrouded rotor 22 also includes a circumferential shroud 21b that surrounds the blades. The shroud 21b is a partial shroud that surrounds the blade assembly but whose axial length is strictly less than the axial length of the rotor 22. The shroud 21b generates a clearance flow 23b between the shroud 21b and the outer portion 30.

[0081] In diagram c), the shrouded rotor 22 also includes a partial circumferential shroud 21c whose axial length is strictly less than the axial length of the rotor 22 and which is located in the main flow section. The shroud 21c generates a clearance flow 23c between the shroud 21c and the external portion 30.

[0082] There [ Fig.4 ] illustrates, schematically and without limitation, a view developed in a horizontal plane of a compression and pumping device according to the invention.

[0083] The device includes a shrouded rotor with a shroud 21.

[0084] Ω illustrates the rotational speed of the rotor.

[0085] The fluid passing through the gap flow has an absolute velocity V TL composed of a tangential velocity V θTL and an axial velocity In the ZTL .

[0086] The stator, located just upstream of the shrouded rotor, includes a tangential velocity reduction means 35 positioned to capture the fluid exiting the clearance flow (i.e., upstream of the shrouded rotor, the fluid circulating in the clearance flow having a flow opposite to that of the fluid passing through the rotor, and the "upstream" direction being understood as the direction of fluid circulation in the shrouded rotor). This reduction means 35 is opposite the shroud 21 and the clearance. Furthermore, this reduction means 35 includes slotted cavities 36, so that the fluid exiting the clearance flow 25 enters these cavities 36 to dissipate the tangential velocity.

[0087] For this purpose, as can be seen in the figure, the cavities 36 are separated by radial walls 37 which reduce the tangential velocity of the fluid.

[0088] The cavities 36 extend in the longitudinal and radial direction.

[0089] There [ Fig.5] illustrates, schematically and without limitation, different types of means of reducing the compression and pumping device according to the invention.

[0090] The different means of reduction 35 of diagrams a) to c) show developed views of these means of reduction.

[0091] Scheme a) includes a reduction means 35 with crenellated grooves 36 (of rectangular section); scheme b) includes a reduction means 35 with triangular grooves 37; scheme c) includes a reduction means 35 with grooves with curved portions 38.

[0092] Each reduction means 35 can include cavities (crenellated, triangular or complex shapes according to schemes a) to c)) of height h sB, the height being understood as the length in the radial direction, of depth d sB, the depth being understood as the longitudinal direction (along the longitudinal axis of the compression or pumping device), and the spacing between the cavities w sB.

[0093] For rectangular cavities corresponding to the crenellated grooves in diagram a), the depth d sB corresponds to the longitudinal length of the rectangle and the spacing w sB can correspond to twice (but a different value could be used) the circumferential length of the cavities.

[0094] For the triangular cavities in diagram b), the depth dsB corresponds to the maximum depth of the triangle's cross-section. When the triangle is a right triangle where the right angle forms a substantially longitudinal surface, and this surface is positioned so that the fluid exiting the clearance flow strikes it in a way that significantly reduces the tangential velocity, the depth dsB corresponds to the length of the side of the right triangle oriented in the longitudinal direction. The spacing wsB can correspond to the side located in the circumferential direction of the cavities.

[0095] For complex-shaped cavities (here curved) in diagram c), the depth dsB corresponds to the maximum depth of the cavity. This complex-shaped cavity may include a substantially longitudinal surface, this longitudinal surface being positioned such that the fluid exiting the flow path strikes this surface in such a way as to significantly reduce the tangential velocity. The depth dsB may, in particular, correspond to the longitudinal length of this longitudinal surface.

[0096] There [ Fig.6 ] illustrates, schematically and without limitation, a portion of a fixed part of a compression or pumping device according to the invention.

[0097] This fixed part comprises a housing with an outer portion 30 and a stator with a stator wheel 31. Furthermore, the stator includes a tangential speed reduction means 35 comprising slotted grooves positioned just upstream of the shrouded rotor (in the direction of fluid flow through the shrouded rotor) so as to capture fluid exiting the clearance flow (flow in the opposite direction to the flow through the shrouded rotor). These grooves are aligned with the shroud of the shrouded rotor and / or the clearance between the shroud and the outer portion 30 of the housing.

[0098] The crenellated grooves are separated here by radial walls forming an interface between the crenellated grooves.

[0099] There [ Fig.7 ] illustrates, schematically and without limitation, another portion of the fixed part of a compression or pumping device according to the invention.

[0100] This fixed part comprises a housing with an outer portion 30 and a stator with a stator wheel 31. Furthermore, the stator includes a tangential speed reduction means 35 comprising triangular grooves positioned just upstream of the shrouded rotor (in the direction of fluid flow through the shrouded rotor) so as to capture fluid exiting the clearance flow (flow in the opposite direction to the flow through the shrouded rotor). These grooves are aligned with the rotor shroud and / or the clearance between the shroud and the outer portion 30 of the housing.

[0101] The triangular grooves are separated here by interfaces (radial walls) forming an interface between the crenellated grooves.

[0102] On the figures 6 and 7 , it can be observed that the reduction means 35 also includes continuities of the stator wheel blades which thus form interfaces.

[0103] There [ Fig.11 ] illustrates, schematically and without limitation, a section in a plane perpendicular to the longitudinal axis of the device according to the invention.

[0104] The device includes a rotor 22 with several blades 20 (four blades in the figure but the rotor could include a different number of blades) and a stator which includes the outer part 30.

[0105] The rotor 20 includes a circumferential fairing 21a around the blades to form a shrouded rotor. This circumferential fairing 21a is circumferentially incomplete because it comprises different parts separated by openings 60. In this example, the incomplete circumferential fairing comprises four distinct parts separated by four openings, but another number of parts / openings could be used. The incomplete circumferential fairing is partially open or shrouded around its circumference. Alternatively, the circumferential fairing 21a could also consist of a single part whose circumferential ends are separated by a single opening.

[0106] In another alternative, the circumferential fairing 21a could be a complete circumferential fairing: this means that the circumferential fairing is then a single piece which covers the entire circumference around the rotor 22, without any openings. Examples

[0107] There [ Fig.8 ] illustrates comparisons of the tangential velocity at the rotor inlet (in the direction of fluid flow through the rotor) in meters per second for devices according to the prior art and according to the invention, derived from modeling. The [ Fig.8 ] is a cross-sectional view in a longitudinal plane.

[0108] Diagram a) illustrates an unfaired (unfaired) rotor of the prior art. Diagram b) illustrates a faired rotor of the prior art and diagram c) illustrates a faired rotor with a stator comprising a tangential speed reduction means 35 positioned upstream of the faired rotor and opposite the fairing and the gap between the fairing and the outer portion of the casing.

[0109] We observe a significant reduction in tangential velocity thanks to the tangential velocity reduction method in diagram c) compared to diagram b).

[0110] Furthermore, with a reduction means comprising slotted grooves according to the invention, a pressure increase of 2.9% and a hydraulic efficiency increase of 2.1% were observed compared with the prior art shrouded rotor solution (without reduction means opposite the shroud and / or clearance and upstream of the rotor).

[0111] With a reduction means comprising triangular grooves according to the invention, an increase in pressure of 8% and an increase in hydraulic efficiency of 1.2% were observed compared with the prior art shrouded rotor solution (without reduction means opposite the shroud 21 and / or the clearance and upstream of the rotor).

[0112] In addition, experimental tests were carried out to compare a shrouded rotor of a prior art device (without reduction means opposite the shroud and / or play and upstream of the rotor) and a shrouded rotor with reduction means opposite the shroud and / or play and upstream of the rotor of a device according to the invention.

[0113] There [ Fig.9 [The diagram illustrates a) a stator of a prior art device comprising a stator wheel 31, without a reduction means opposite the fairing and / or the clearance and upstream of the fairinged rotor, and b) a stator of a device according to the invention comprising a stator wheel 31, and a reduction means 35 opposite the fairing and / or the clearance and upstream of the fairinged rotor. The reduction means 35 here comprises triangular (right-angled) grooves.]

[0114] Diagrams a) and b) are photographs of the two stators tested.

[0115] Of course, the other parameters of the two devices are essentially identical (in particular the geometric data). The two devices therefore differ only with regard to the reduction means 35 present in the device of the invention and absent in the prior art device.

[0116] There [ Fig.10[ ] illustrates images taken during tests performed on a device according to the invention with a reduction means comprising triangular grooves. A small quantity of gas (approximately 5% gas volume fraction) was injected to serve as a tracer for the photos and videos taken during the tests. Diagram a) is an image at a flow rate representing 60% of the nominal flow rate of the device according to the invention, which corresponds substantially to the numerical value of 59.3° found by numerical simulations, and diagram b) is an image at a flow rate representing 100% of the nominal flow rate of the device according to the invention. The rotor rotation speed is 2,000 revolutions per minute for both images in diagrams a) and b).

[0117] Arrows 40a and 40b, along with vortices 41, have been added to these images for clarity. Arrows 40a and 40b represent the flow direction within the clearance flow. Arrow 40a is inclined at approximately 41% to the longitudinal axis, and arrow 40b is inclined at approximately 60% to the longitudinal axis. This indicates that the fluid exiting the clearance flow has a non-zero tangential velocity (resulting from the rotor's rotation and the flow rate through the rotor).

[0118] The vortices 41 in the triangular-shaped grooves of the reduction means show how the tangential velocity is reduced by the effect of the generated vortices.

Claims

1. A fluid compression or pumping device, preferably for multiphase fluids, comprising a fixed part, at least one rotor (22) and a rotor shaft, each rotor (22) being integral with the rotor shaft, the rotor shaft being configured to be driven in rotation about a longitudinal axis, each rotor (22) comprising blades (20) extending substantially radially with respect to the longitudinal axis, and at least one of the rotors being a shrouded rotor comprising a circumferential shroud (21, 21a, 21b, 21c) connecting the peripheral radial ends of the blades (20), the fixed part comprising at least one stator and at least one external portion (30) surrounding each rotor (22), the device comprising a clearance between the external surface of each circumferential shroud (21, 21a, 21b, 21c) of the shrouded rotor and the internal surface of the external portion (30) surrounding that rotor streamlined, allowing for clearance flow (23a, 23b,23c) in the opposite direction to the fluid flow through this shrouded rotor, , characterized in that the stator upstream of the shrouded rotor includes a means for reducing the tangential velocity of the fluid arriving from the clearance flow, each reduction means (35) being positioned axially opposite the shroud (21, 21a, 21b, 21c) of the shrouded rotor (22) and / or said clearance, upstream of the shrouded rotor (22) in the direction of the flow through the shrouded rotor.

2. Device according to claim 1, comprising several stators and / or several rotors, preferably the stators and rotors succeeding each other alternately along the longitudinal axis.

3. Device according to any one of the preceding claims, wherein each rotor (22) comprises at least one series of blades (20), each series of blades comprising blades (20) regularly distributed around the rotor shaft, preferably each rotor comprises at least two series of blades following each other longitudinally.

4. Device according to any one of the preceding claims, comprising several shrouded rotors.

5. Device according to the preceding claim, wherein the circumferential fairing (21, 21a, 21b, 21c) of the shrouded rotor extends longitudinally over a length enabling it to cover the series or at least one of the series of blades, preferably all the series of blades and even more preferably, the length of the fairing (21, 21a, 21b, 21c) is equal to the length of the rotor concerned.

6. Device according to any one of the preceding claims, wherein the circumferential fairing is circumferentially complete or circumferentially incomplete with at least one opening.

7. Device according to any one of the preceding claims, wherein each reduction means (35) is formed by cavities in the stator to reduce the tangential velocity of the fluid arriving from the clearance flow (23a, 23b, 23c), the cavities being opposite the outlet of the fluid from the clearance flow, the cavities being distributed circumferentially on the stator and separated from each other by interfaces, preferably some of the interfaces comprising extensions of stator blades.

8. Device according to the preceding claim, wherein the cavities comprise crenellated (36) or triangular (37) shaped grooves developed in the circumferential direction.

9. Device according to any one of claims 7 or 8, wherein the number of cavities between two successive rotor blades opposite the reduction means is between 3 and 10.

10. Device according to any one of claims 7 to 9, wherein the ratio between the height of the cavities and the height of the blades is between 10% and 40%, preferably between 15% and 25%.

11. Device according to any one of claims 7 to 10, wherein the ratio between the depth of the cavities and the longitudinal length of the rotor is between 2% and 20%, preferably between 5% and 10%.

12. Multiphase pump comprising a device according to one of the preceding claims.

13. Use of the device according to any one of claims 1 to 11 or of the multiphase pump according to claim 12, for the extraction of oil or gas from a geological reservoir and / or for the injection of a fluid into a geological reservoir.

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