FIELD OF THE INVENTION

[0001] The present technology relates to a pump based on a Tesla turbine acting as a pump.

BACKGROUND

[0002] A Tesla turbine pump consists of a set of smooth discs which are rotated to impart motion to a fluid. The fluid enters between the discs near the center, is given energy by the rotating discs, then exits at the periphery. A Tesla turbine does not generally use friction; instead, it uses the boundary-layer effect on the discs to impart motion to the fluid.

[0003] US 4,402,647 discloses a vaneless fluid impeller of the friction type including a plurality of co-rotating aligned spaced annular discs mounted for rotation about a common axis.

[0004] US 4,773,819 discloses a pump for pumping a slurry includes a rotary pump having a plain disc impeller disposed in a cylindrical chamber of a housing with an inlet coaxial of the impeller into the housing.

[0005] US 5,191 ,247 discloses a cooling fan positioned within the casing of an electric motor comprising a plurality of closely spaced frustoconical discs carried by the motor shaft which draw intake air past the motor rotor and stator when they are rotated.

[0006] US 6,261 ,052 discloses an apparatus comprising a longitudinally extending housing having a fluid inlet port and a fluid outlet port; and, at least one plurality of spaced apart members, each member rotatably mounted in the housing and having a pair of opposed surfaces to transmit motive force between fluid introduced through the fluid inlet port and the spaced apart members, the surface area of the opposed surfaces varying between at least some of the immediately adjacent spaced apart members.

[0007] US 2006/0216149 discloses several disc assemblies of a bladeless compressor, pump or turbine.

[0008] US 6,227,796 discloses an impeller comprising a fluid induction core of flow passages spiraling axially about the impeller’s rotational axis and a stack of circular discs extending radially and concentrically from the induction core. SUMMARY

[0009] In accordance with the invention, there is provided a liquid pump comprising: a housing having an inlet disposed at an upstream end and an outlet disposed at a downstream end opposite the inlet; a shaft extending through the housing along a center axis of the housing and configured to be rotated about a rotation axis by a motor; and one or more pumping stages connected along the shaft in a co-axial arrangement, each pumping stage comprising a disc impeller comprising multiple axially spaced discs, each disc having a central opening such that when the disc impeller is rotated, liquid entering the disc impeller through the central openings is driven outwards between gaps between the discs and towards the outlet, wherein the size of the central opening of the discs vary with axial position, the discs with a larger central opening being positioned towards the inlet.

[0010] Each pumping stage may comprise a respective inlet and outlet.

[0011] The inlet may be configured to receive fluid in a direction aligned with (e.g. parallel to) the rotation axis. The outlet may be configured to direct fluid in a direction aligned with (e.g. parallel to) the rotation axis.

[0012] The disc impeller may comprise disc mounts configured to connect the discs together, the disc mounts being aligned with the rotation axis and being circumferentially elongated.

[0013] The discs in each pumping stage may lie parallel to each other.

[0014] The discs in each pumping stage may be rigid.

[0015] Each stage may be separated by one or more components which directs fluid from the outer extent of the discs in one stage to the central openings of the next stage.

[0016] The disc impeller may comprise disc mounts configured to connect the discs together, the disc mounts being positioned towards the inlet and/or the central axis.

[0017] The disc impeller may be of unitary construction.

[0018] The disc impeller may be formed from a single block of metal. [0019] The disc impeller may be formed by additive manufacturing techniques (e.g. 3D printing or sintering).

[0020] The disc impeller may be formed by subtractive manufacturing techniques (e.g. CNC machining).

[0021] The disc impeller may be formed from steel.

[0022] The spacing between successive discs (e.g. the opposing surfaces of two neigbouring discs) may be between 2-20 mm.

[0023] Each disc may extend radially away from, and be concentric with, the rotation axis.

[0024] The surface of each disc may lie between the rotation axis and a plane perpendicular to the rotation axis which intersects the rotation axis and the side of the disc closest to the inlet. The surface of each receiving disc may form an a frustoconical shape.

[0025] Each disc may have an outer extent, and wherein the size of the outer extent of the discs may vary with axial position, the discs with a larger outer extent being positioned towards the inlet.

[0026] Each disc may form an outlet gap with the housing, wherein the size of the outlet gaps of the discs varies with axial position, the discs with a smaller outlet gap being positioned towards the inlet.

[0027] At least one of the discs may be connected to the shaft indirectly via another of the discs. At least one of the discs may not be connected to the shaft directly (e.g. with an armature connecting the disc to the shaft).

[0028] The inner surface of the discs around the central opening may be angled inwardly away from the inlet.

[0029] Each stage may have between 2 and 12 discs.

[0030] The disc closest to the inlet may comprise a lip, the lip being configured to prevent fluid passing from the inlet directly into space between a planar surface of the disc closest to the inlet and the housing.

[0031] Each pumping stage may comprise a stator configured to draw liquid from the housing inwardly towards the rotation axis. [0032] According to a further aspect, there is provided a method of pumping liquid comprising: placing a liquid pump as described herein such that liquid is in fluid communication with the inlet; and rotating the shaft.

[0033] The liquid may contain solid particulates.

[0034] The liquid may comprise oil.

[0035] The pump may comprise more than 10 stages. The pump may comprise up to 200 stages.

[0036] The discs may have an outside diameter of between 50 to 350 mm.

[0037] The axial dimension of each stage may be between 30-100 mm.

[0038] The pump may be configured to operate between 2500-5000 rpm.

[0039] The pump may be configured to provide a pumping rate of between 100 and 1 ,000 m ³ /day. The pump may be configured to provide a pumping rate of up to 10,000 m ³ /day.

[0040] The pump may be configured to pump oil, water or a mixture of the two (e.g. an emulsion).

[0041] The pump may be configured to pump one or more of the following:

• Light crude oil having an API gravity higher than 31.1° (i.e., less than 870 kg/m ³ );

• Medium oil having an API gravity between 22.3 and 31.1° (i.e., 870 to 920 kg/m ³ ); and

• Heavy crude oil having an API gravity below 22.3° (i.e., 920 to 1000 kg/m ³ ).

[0042] The pump may be configured to pump fluids containing up to 5% solids by volume. The pump may be configured to pump fluids containing up to 40% solids by volume.

[0043] The impeller, shaft and/or other rotating components may be symmetric about at least one mirror plane aligned with the rotation axis. This may help enable the pump to run smoothly. [0044] A stator may be a stationary component (e.g. fixed with respect to the housing) configured to direct fluid flow from the outside of the housing towards a centrally located axial outlet. The stator may comprise one or more blades.

[0045] The pump may be used downhole to extract fluid from a well; to remove water and/or oil from an oil well; to manage brine and other fluids within a salt dome; and/or to move fluid within a geothermal well.

[0046] The pump may be used in oil production which uses particulates (e.g. sand). One example is cold heavy oil production with sand (CHOPS) which involves introducing sand during the completion procedure, maintenance of sand influx during the productive life of the well, and implementation of methods to separate the sand from the oil for disposal. The sand is then produced along with oil, water, and gas and then separated.

BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Various objects, features and advantages of the invention will be apparent from the following description of particular embodiments of the invention, as illustrated in the accompanying drawings. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of various embodiments of the invention. Similar reference numerals indicate similar components.

Figure 1a is an axial cross-section of an embodiment of a pump.

Figure 1b is a transverse cut-through view looking down from A-A as shown in figure 1a.

Figure 1 c is a side view of the impeller stage of the embodiment of figure 1a. Figure 2 is a perspective cut-through view of multiple stages of an embodiment of a pump.

Figure 3 is a profile of an impeller for an embodiment of a pump.

DETAILED DESCRIPTION

Introduction

[0048] Pumps are typically used in the industry (e.g. the oil industry) to pump liquids. Often these liquids will contain solids (e.g. sand or rock fragments) which can damage pump components. For example, solids could damage seals by getting between the components which are contacting each other (e.g. the vanes and the housing in a vane pump), or by impacting moving components (e.g. the impeller in a centrifugal pump).

[0049] Tesla turbine pumps may help address some of these issues. A Tesla turbine pump uses the boundary layer effect to transfer energy from a series of blades to a fluid (e.g. a liquid). As a result of this effect, the fluid follows a rapidly accelerated spiral path along the disc faces until it reaches a suitable exit. The boundary layer is formed through a combination of the fluid’s adhesion and viscosity. The boundary layer helps isolate the discs from the fluid, and any contained solids, moving through the pump.

[0050] The present technology relates to ensuring that the fluid can move more easily though the impeller stage while limiting the damage on the moving component of the pump.

[0051] Various aspects of the invention will now be described with reference to the figures. For the purposes of illustration, components depicted in the figures are not necessarily drawn to scale. Instead, emphasis is placed on highlighting the various contributions of the components to the functionality of various aspects of the invention. A number of possible alternative features are introduced during the course of this description. It is to be understood that, according to the knowledge and judgment of persons skilled in the art, such alternative features may be substituted in various combinations to arrive at different embodiments of the present invention.

Pump Stage

[0052] Figure 1a-c are various views of one stage of an embodiment of a Tesla turbine pump. Figure 1a is an axial cross-section through the pump in a plane aligned with the pump axis. Figure 1b is a transverse cut-through view looking down from A- A (shown in figure 1a). Figure 1c is a side view of the impeller stage.

[0053] In this case, the pump comprises: a housing 101 having an inlet 103 disposed at an upstream end and an outlet 104 disposed at a downstream end opposite the inlet; a shaft 105 extending through the housing along a center axis 120 of the housing and configured to be rotated about a rotation axis by a motor (not shown); and one or more pumping stages connected along the shaft in a co-axial arrangement, each pumping stage comprising a disc impeller comprising multiple axially spaced discs 102a-d, each disc having a central opening such that when the disc impeller is rotated, liquid enters the disc impeller through the central openings and is driven outwards between gaps between the discs and towards the outlet, wherein the size of the central opening of the discs vary with axial position, the discs with a larger central opening being positioned towards the inlet.

[0054] In addition to the receiver discs 102a-d which have central openings for receiving fluid from the inlet axially and redirecting the received fluid laterally, the disc impeller also includes a blocking disc 102e. The blocking disc is positioned furthest away from the inlet and does not have any central opening for receiving fluid. This means that any fluid which is not redirected by the first receiving discs 102a-d will be redirected laterally by the blocking disc. All of the discs in this case extend radially and concentrically away from the rotation axis.

[0055] It will be appreciated that for designs which the central openings do not diminish in size as you move away from the inlet, when fluid being pumped into the inlet, there may be turbulence when the flow strikes an component which does not permit any through flow (such as a moving blocking disc or a stationary part of the housing). In this case, the diminishing size of the central openings may help each disc to redirect a portion of the flow, thereby leading to improved laminar flow. This is particularly important where the fluid contains solids because laminar flow may help ensure that the solids do not come into contact with solid components of the pump.

[0056] In this case, the pump also comprises an optional stator before the outlet. This stator is configured to redirect rotationally flowing liquid at the edges of the housing inwards towards the centrally located outlet. Because the stator is not configured to move, it can be built more robustly because excess weight in this component may not cause an increased power demand on the motor driving the impeller stage.

[0057] Having the inlet and the outlet centrally located allows a composite pump to be formed by multiple stages arranged coaxially.

[0058] In this case, as shown in figures 1 b-1 c the disc impeller comprises disc mounts 107aa-ab, 107ba-bb, 107ca-cc, 107da-db configured to connect the discs together, the disc mounts being aligned with the rotation axis and being circumferentially elongated.

[0059] In this case, the receiver discs 102a-d are not directly connected to the shaft. Instead, the disc towards the outlet 102e is directly connected to the shaft. Each disc closer to the inlet is connected to its neighbor towards the outlet. For example, disc 102d is connected to disc 102e; disc 102c is connected to disc 102d and so on. That is, at least one of the discs is supported only via the mounts connecting the disc to one or more neighbouring discs. Avoiding the direct connection to the shaft may help reduce turbulence by reducing the blockages within the central channel formed by the central openings.

[0060] In this case, as shown in figure 1b, the mounts 107ca-cc are circumferentially elongated. That is, they have a greater dimension along a circumference around the rotation axis than along a radius from the rotation axis. Although this reduces the space for fluid passing out from the central channel, the elongated shape reduces the potential for impact between the relatively stationary fluid and the moving mounts, while providing the required structural rigidity. The mounts are positioned towards the central channel so that the fluid can apply a corrective force in the event that the discs deviate away from a plane perpendicular to the rotation axis.

[0061] In this case, the disc impeller is of unitary construction. In this case, the shaft and discs are formed using a single block of steel using subtractive method such as using a CNC (computer numerical control) machine. In this case, the CNC machine is configured to remove material from the block.

[0062] In this case, the spacing between opposing surfaces of neighbouring discs (i.e. corresponding to the gap through which liquid can flow) is between 0.5-20 mm. This may permit smooth flow of viscous liquids such as oil which may contain particulates. The spacing between opposing surfaces of neighbouring discs may be between 10% and 40% of the discs in the stage (i.e. between the top of the uppermost disc and the bottom of the lowermost disc).

[0063] In this case, each disc has an outer extent, wherein the size of the outer extent of the discs does not vary with axial position. It will be appreciated that other configurations are possible. Multiple-Stage Embodiment

[0064] Figure 2 is a transverse cut-through perspective view of multiple stages of a pump.

[0065] In this case, the pump comprises: a housing 20T having an inlet 203’ disposed at an upstream end and an outlet 104 disposed at a downstream end opposite the inlet; a shaft (not shown) extending through the housing along a center axis of the housing and configured to be rotated about a rotation axis by a motor (not shown); and multiple pumping stages 290, 290’, 290” connected along the shaft in a co axial arrangement, each pumping stage comprising a disc impeller comprising multiple axially spaced discs 202’a-c each disc having a central opening such that when the disc impeller is rotated, liquid enters the disc impeller through the central openings and is driven outwards between gaps between the discs and towards the outlet, wherein the size of the central opening of the discs vary with axial position, the discs with a larger central opening being positioned towards the inlet.

[0066] The pump is configured such that each impeller stage has a corresponding housing module. The connected housing modules make up the housing.

[0067] In this case, each stage of the pump comprises complementary connectors on the upstream end and on the downstream end of housing modules. This means that a series of identical stages can be connected end on end to form a pump with multiple stages. The outlet of one stage 290 is configured to direct liquid into the inlet 203’ of a connecting neighbouring stage 290’.

[0068] In addition to the receiver discs 202’a-c which have central openings for receiving fluid from the inlet and redirecting the received fluid laterally, the disc impeller also includes a blocking disc 202’d. The blocking disc is positioned furthest away from the inlet and does not have any central opening for receiving fluid. This means that any fluid which is not redirected by the first receiving discs 202’a-c will be redirected laterally by the blocking disc. All of the discs in this case extend radially and concentrically away from the rotation axis. [0069] It will be appreciated that the components of the impeller configured to contribute to pumping the fluid are rotationally symmetric. This may help ensure smooth operation of the pump by improving the balance. It may also allow the pump to be operated across a wide range of speeds. For example, a pump comprising a conventional centrifugal impeller may only operate in a narrow range of speeds.

[0070] The inner surface of the housing adjacent to the outside edge of the discs may be rotationally symmetric. This may allow the pump to be more easily manufactured and ensure a consistent flow from the discs to the outlet.

[0071] Unlike the embodiment of figure 1a, in this case, the receiving disc 202’a which is closest to the inlet 203’ comprises a lip 23T which engages with the housing of the neighbouring stage 290”. This lip is configured to rotate with respect to the stationary inlet channel about the rotation axis. This lip is configured to direct water passing from the inlet 203’ into spaces between the planar surfaces of two rotating discs rather than into a space between the planar surface of the receiving disc 202’a towards the inlet and the housing. This may help ensure that the fluid from the inlet is accelerated consistently as all the fluid will pass between two rotating discs.

[0072] The disc closest to the outlet also comprises an engagement member 232’, in this case to engage with a complementary connector in the housing of the next stage. The engagement member 232’ may help with alignment. In this case, the engagement is ring shaped to facilitate rotation about the rotation axis.

[0073] It will be appreciated that for designs which the central openings do not diminish in size as you move away from the inlet, when fluid being pumped into the inlet, there may be turbulence when the flow strikes an object which does not permit any through flow (such as a moving blocking disc or a stationary part of the housing). In this case, the diminishing size of the central openings may help each disc to redirect a portion of the flow, thereby leading to improved laminar flow. This is particularly important where the fluid contains solids and laminar flow may help ensure that the solids do not come into contact with solid components of the pump. Reducing turbulence on the inlet side may be important in a multistage pump where fluid is being pumped into the inlet of each subsequent stage by the preceding pump stages (e.g. as opposed to being sucked in by the discs as may be the case in a single stage arrangement).

[0074] In this case, the inlet 203’ and the outlet 204’ are both centrally located which allows a composite pump to be formed by multiple stages arranged coaxially. It will be appreciated that any number of stages could be combined together (e.g. up to 100 stages or more).

[0075] Although not shown, the impellers of the embodiment of figure 2 comprises disc mounts configured to connect the discs together, the disc mounts being aligned with the rotation axis and being circumferentially elongated.

[0076] In this case, the receiver discs 202’a-c are not directly connected to the shaft. Instead, the disc towards the outlet 202’d is directly connected to the shaft. Each disc closer to the inlet is connected to its neighbor towards the outlet. For example, disc 202’c is connected to disc 202’d; disc 202’b is connected to disc 202’c and so on. Avoiding the direct connection to the shaft may help reduce turbulence by reducing the blockages within the central channel formed by the central openings.

[0077] In this case, as shown in figure 1b, the mounts are circumferentially elongated. That is, they have a greater dimension along a circumference around the rotation axis than along a radius from the rotation axis. Although this reduces the space for fluid passing out from the central channel, the elongated shape reduces the potential for impact between the relatively stationary fluid and the moving mounts, while providing the required structural rigidity. The mounts are positioned towards the central channel so that the fluid can apply a corrective force in the event that the discs deviate away from a plane perpendicular to the rotation axis.

[0078] In this case, the disc impeller is of unitary construction. The shaft connector 239’ and discs are formed using a single block of steel using a CNC (computer numerical control) machine. In this case, the CNC machine is configured to remove material from the block. In this case, each stage has a shaft connector 239’ comprising a hollow closed channel through which the shaft can pass.

[0079] In this case, the spacing between opposing surfaces of successive discs is between 2-20 mm.

[0080] In this case, to further direct the fluid towards the gaps between the rotating discs, the inner surface of the discs around the central opening are angled inwardly away from the inlet. This may help direct the fluid flow which is not passing between the discs to be directed towards other discs while reducing turbulence.

[0081] On the outer extent of the discs, some turbulence may be mitigated by configuring the stage such that each disc forms an outlet gap with the housing, and wherein the size of the outlet gaps of the discs vary with axial position, the discs with a smaller outlet gap being positioned towards the inlet. In this case, the increasing gap is provided by the discs having the same diameter and the housing increasing in diameter away from the inlet and towards the outlet. This means that as fluid is added from the gaps between each successive disc, there is more room for this additional fluid to be accommodated.

[0082] In other embodiments, providing a larger gap for fluid exiting the impeller towards the outlet side may be provided by the size of the outer extent of the discs varying with axial position, the discs with a larger outer extent being positioned towards the inlet.

Impeller Profile

[0083] Figure 3 shows a profile for an impeller for a pump stage. The impeller is similar to that of figure 2. The impeller stage would be formed by rotating this profile about the rotation axis. Mounts are not shown.

[0084] The disc impeller comprises multiple axially spaced discs 302a-c each disc having a central opening such that when the disc impeller is rotated, liquid enters the disc impeller through the central openings and is driven outwards between gaps between the discs and towards the outlet, wherein the size of the central opening of the discs vary with axial position, the discs with a larger central opening being positioned towards the inlet.

[0085] In addition to the receiver discs 302a-c which have central openings for receiving fluid from the inlet and redirecting the received fluid laterally, the disc impeller also includes a blocking disc 302d. The blocking disc is positioned furthest away from the inlet and does not have any central opening for receiving fluid. This means that any fluid which is not redirected by the first receiving discs 302a-c will be redirected laterally by the blocking disc. All of the discs in this case extend radially and concentrically away from the rotation axis.

[0086] In this case, the receiving disc 302a which is closest to the inlet 303 comprises a lip 331 which engages with the housing of the neighbouring stage. This lip is configured to direct water passing from the inlet 303 into spaces between the planar surfaces of two rotating discs rather than into a space between the planar surface of the receiving disc 302a towards the inlet and the housing. This may help ensure that the fluid from the inlet is accelerated consistently as all the fluid will pass between two rotating discs. [0087] The disc closest to the outlet also comprises an engagement member 332, in this case to engage with a complementary connector in the housing of the next stage. In this case, the engagement is ring shaped to facilitate rotation about the rotation axis.

[0088] In this case, the stage has a shaft connector 339 comprising a hollow closed channel through which the shaft can pass.

Other Options

[0089] In other embodiments, the surface of the disc may lie between the rotation axis and a plane perpendicular to the rotation axis. That is, the surface of each receiving disc may form an a frustoconical shape. The frustoconical shape may be configured such that the outer extent of the disc is axially further away from the inlet than the inner extent of the disc.

[0090] The mounts may be configured to be angled inwardly between the outsides of the central openings of the two connected discs. This may help reduce turbulence and/or reduce wear on the discs by ensuring that the area of the discs inside the mounts is reduced. It will be appreciated that having a rotating disc surface inside the mount may drive a portion of the fluid into the disc.

[0091] Although the present invention has been described and illustrated with respect to preferred embodiments and preferred uses thereof, it is not to be so limited since modifications and changes can be made therein which are within the full, intended scope of the invention as understood by those skilled in the art.