Patent Application
20240360841
This invention relates generally to the field of pumping systems, and more particularly, but not by way of limitation, to a pumping system that includes rotationally fixed, nested diffusers.
Submersible pumping systems are often deployed into wells to recover petroleum fluids from subterranean reservoirs. Typically, a submersible pumping system includes a number of components, including an electric motor coupled to one or more pump assemblies. Production tubing is connected to the pump assemblies to deliver the petroleum fluids from the subterranean reservoir to a storage facility on the surface. The pump assemblies often employ axially and centrifugally oriented multi-stage turbomachines. Each of the components in a submersible pumping system must be engineered to withstand the inhospitable downhole environment.
Most downhole turbomachines include one or more impeller and diffuser combinations, commonly referred to as “stages.” The impellers rotate within adjacent stationary diffusers. A shaft keyed only to the impellers transfers mechanical energy from the motor. During use, the rotating impeller imparts kinetic energy to the fluid. A portion of the kinetic energy is converted to pressure as the fluid passes through the downstream diffuser. To reduce wear and improve efficiency, it is important to minimize surface-to-surface contact between the spinning impeller and the stationary diffusers.
The diffusers and impellers are typically contained within the pump housing. During manufacture, each diffuser-impeller stage is stacked inside the pump housing. After stacking the requisite number of diffusers into the housing, a compression sleeve may be used to provide a standard spacing between the diffusers during operation. During the compression process, however, the side walls of the diffusers tend to deform, thereby compromising the structural and operational characteristics of the diffuser. Furthermore, metal fatigue, temperature variances and mechanical shock can reduce the captured compression and allow diffusers to rotate within the pump housing. Such spinning causes localized heating, inefficient pumping, and can result in failure of the pump housing.
In the past, pump manufactures have used a slot-and-key arrangement to rotationally fix the diffusers to one another and the pump housing. Although generally effective at preventing the rotation of diffusers, the slot-and-key connections can weaken the pump components, create fluid interference and turbulence, and increase the manufacturing and assembly costs. There is, therefore, a need for an improved system for maintaining the stationary position of diffusers within the pump housing. It is to these and other deficiencies in the prior art that the present disclosure is directed.
Embodiments disclosed herein are generally directed at improved diffusers for use in a pumping system. The diffusers each include a first end, a second end, and a central portion between the first end and the second end. The diffusers further include a projection on the first end and a receiver on the second end. The projection has a projection inner surface and a projection outer surface, where the projection outer surface has a non-circular shape. The receiver includes a receiver outer surface and a receiver inner surface. The receiver inner surface has the same non-circular shape as the projection outer surface.
In other embodiments, the present disclosure is directed at a pumping system that has a motor and a pump driven by the motor. The pump includes a housing and first and second pump stages inside the housing. The pump further includes a first impeller and a first diffuser within the first pump stage, where the first diffuser has a first end, a second end, and a projection on the second end. The projection has a projection outer surface that has a non-circular shape. The pump also includes a second impeller and a second diffuser within the second pump stage, where the second diffuser has a first end, a second end, and a receiver on the first end. The receiver includes a receiver inner surface that has a non-circular shape that is complementary to the non-circular shape of the projection outer surface of the first diffuser, which permits the projection of the first diffuser to nest within the receiver of the second diffuser such that the first diffuser cannot rotate with respect to the second diffuser.
In yet other embodiments, the present disclosure is directed to a pump for use within a pumping system, where the pump includes a first stage and a second stage adjacent to the first stage. The first stage includes a first impeller and a first diffuser, and the second stage includes a second impeller and a second diffuser. The first diffuser and second diffuser each include means for nesting the first diffuser and second diffuser together in a rotationally fixed arrangement within the pump.
The pumping system 100 includes a pump 108, a motor 110 and a seal section 112. The seal section 112 shields the motor 110 from mechanical thrust produced by the pump 108. The motor 110 is provided with power from the surface by a power cable. Although only one pump 108 and one motor 110 are shown, it will be understood that more can be connected when appropriate. In the embodiment depicted in
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To optimize pumping efficiency, each diffuser 122 should remain stationary within the housing 120 as the impeller 124 and shaft 126 rotate. Unlike the prior art use of compression sleeves or a key-and-slot combinations, the diffusers 122 constructed in accordance with exemplary embodiments include a keyless nesting mechanism in which a shaped projection 140 on a first end of the diffuser 122 mates within a matching receiver 142 on a second, opposite end of an adjacent diffuser 122. The projection 140 and receiver 142 each have complementary, non-circular shapes that prevent adjacent, nested diffusers 122 from rotating with respect to one another when the projection 140 of a first diffuser 122 is nested within the receiver 142 of an adjacent second diffuser 122.
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Thus, a series of adjacent diffusers 122 can be ganged together in this nested configuration to prevent the entire line of diffusers 122 from rotating with respect to one another within the pump housing 120. One or more of the diffusers 122 can be connected to the housing 120 or another fixed component within the pump 108 using conventional mechanisms, such as a slot-and-key arrangement. The incorporation of the projection 140 and receiver 142 in the diffusers 122 provides a cost-effective and efficient nesting mechanism for preventing the rotation between adjacent diffusers 122.
Although the projection 140 and receiver 142 have been disclosed as having oblong or ellipse shapes, in other embodiments the receiver 142 and projection 142 have other non-circular shapes, including oval shapes and lobed shapes, where the shape and size of the projection outer surface 146 cannot rotate within the receiver inner surface 148 once the projection 140 has been nested inside the receiver 142. In exemplary embodiments, the projection 140 and receiver 142 include complementarily shaped mating surfaces that can be efficiently and cost-effectively manufactured. It will be appreciated that the anti-rotation nesting mechanism based on the projection 140 and receiver 142 can be applied to diffusers other than the specific diffuser 122 depicted in
In some embodiments, diffusers 122 within the same pump housing 120 will have differently shaped projections 140 and receivers 142. Using multiple sets of matching projections 140 and receivers 142 can facilitate assembly of the pump 108, particularly where different diffusers are used within the same pump 108, by ensuring the diffuser 122 and impellers 124 are properly ordered during assembly. For example, diffusers 122 in radial flow stages 118 near the intake 114 can be provided with a first set of matching projections 140 and recesses 142, while diffusers 122 in axial flow stages 118 near the discharge 116 are provided with a second set of matching projections 140 and recesses 142, where the first and second set of matching projections 140 and recesses 142 are not interchangeable.
It is to be understood that even though numerous characteristics and advantages of various embodiments of the present invention have been set forth in the foregoing description, together with details of the structure and functions of various embodiments of the invention, this disclosure is illustrative only, and changes may be made in detail, especially in matters of structure and arrangement of parts within the principles of the present invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. It will be appreciated by those skilled in the art that the teachings of the present invention can be applied to other systems without departing from the scope and spirit of the present invention.
