BR112020001126A2 - Pumping system drive shaft conversion adapter - Google Patents

Abstract

It is a pump for use in a motorized pumping system that has a pump drive shaft with a lower ring groove and an upper ring groove. The pump also includes a lower adapter and an upper adapter. The bottom adapter has a pair of bottom ring halves configured to fit the bottom ring groove and the top adapter has a pair of top ring halves configured to fit the top ring groove. The pump additionally includes a plurality of stages that each have a stationary diffuser and a rotary impeller. The rotary impellers are connected to the drive shaft with a specially shaped connection that allows the impeller to move axially along the drive shaft. Also disclosed is a method for converting a compression drive shaft to a float drive shaft that includes the steps of placing an upper adapter in the upper ring groove, placing one or more impellers on the driving shaft, placing one or more standard spacers on the drive shaft and place a lower adapter in the lower ring groove.

Description

"PUMPING SYSTEM DRIVE SHAFT CONVERTER ADAPTER" RELATED DEPOSIT REQUESTS

[0001] This application claims the benefit of provisional patent application U.S. Serial No. 62 / 535,224 filed on July 20, 2017 entitled "Pumping System Shaft Conversion Adapter", the disclosure of which is hereby incorporated by reference.

FIELD OF THE INVENTION

[0002] This invention refers, in general, to the field of submersible pumping systems and, more particularly, but not by way of limitation, to a mechanism for converting drive shafts used in multistage centrifugal pumps.

BACKGROUND

[0003] Multistage centrifugal pumps are used in a variety of submersion and surface applications. In these pumps, each "stage" includes a rotating impeller and a stationary diffuser. A specially shaped drive shaft to fit impellers only transfers the mechanical energy from the motor. During use, the rotating impeller transmits kinetic energy to the fluid. A portion of the kinetic energy is converted into pressure as the fluid passes through the downstream diffuser. As the fluid is pressurized and moved through the pump, a force is exerted against the impellers in the opposite direction. This force is often called "downward thrust". The "upward thrust" occurs as the fluid moving through the impeller pushes the impeller upward. Centrifugal pumps have a flow equilibrium point at which the upward and downward thrust generated by the impellers are balanced. Lower flow rates cause excessive downward thrust, while higher flow rates can cause excessive upward thrust. To prevent damage to the pump, the upward thrust and downward thrust must be controlled using one or more thrust bearings.

[0004] In many multi-stage pumps, impellers are placed on the pump drive shaft and compressed between a pair of two-piece rings located at opposite ends of the pump drive shaft. This design is often called a "fixed impeller" pump and the thrust generated by the impeller assembly is transferred to the "compression drive shaft" through the lower two-piece ring. The thrust is carried by the compression drive shaft in a large thrust bearing that is often located in a seal section that is adjacent to the pump.

[0005] In some cases, it is desirable to use a "floating impeller" design in which the impellers are not all connected under compression. In a floating impeller design, impellers can move in an axial direction along the drive shaft during operation and the downward thrust generated by the impellers is not transferred through the drive shaft to a dedicated thrust bearing. Instead, the downward thrust created by the impellers is compensated for by "rolling stages" positioned at intervals in the pump. Impellers need to be free to move independently between rolling stages to transfer thrust to rolling stages.

[0006] A standard "floating" drive shaft uses pressure snap rings to keep impellers, spacers and other components on the drive shaft and allow free axial movement of the impellers. Existing floating drive shafts therefore contain specific grooves at specified locations on the drive shaft to accommodate pressure snap rings. These grooves are not typically present on a compression drive shaft. Efforts to adapt compression drive shafts to accommodate a floating impeller design are expensive and time consuming, as the pressure snap ring grooves need to be added to the compression drive shaft. Therefore, there is a need to develop an adapter system that facilitates easy conversion from a compression drive shaft to a floating drive shaft. It is for these and other objects that the present invention is directed.

SUMMARY OF THE INVENTION

[0007] In one aspect, embodiments of the present invention include a pump for use in a motorized pumping system. The pump includes a drive shaft that has a lower ring groove and an upper ring groove. The pump also includes a lower adapter and an upper adapter. The bottom adapter has a pair of bottom ring halves configured to fit the bottom ring groove and the top adapter has a pair of top ring halves configured to fit the top ring groove. The pump additionally includes a plurality of stages that each have a stationary diffuser and a rotary impeller. The rotary impellers are connected to the drive shaft by a specially shaped connection that allows the impeller to move axially along the drive shaft.

[0008] In another aspect, one embodiment of the invention includes a method for converting a compression drive shaft into a floating drive shaft, wherein the compression shaft includes an upper ring groove and a groove bottom ring which have the capacity, respectively, to hold an upper two-piece ring and a lower two-piece ring to apply compression to a stack of impellers arranged along the compression drive shaft. The method includes the steps of placing an upper adapter in the upper ring groove, placing one or more impellers on the drive shaft, placing one or more standard spacers on the driving shaft, and placing a lower adapter in the lower ring groove.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is an elevation view of a submersible pumping system.

[0010] Figure 2 is a cross-sectional view of the pump of the submersible pumping system of Figure 1.

[0011] Figure 3 is a cross-sectional "close-up" view of the various stages of the pump in Figure 2.

[0012] Figure 4 is a cross-sectional perspective view in "close-up" of the upper adapter near the pump head.

[0013] Figure 5 is a cross-sectional view of the pump head with an upper adapter.

[0014] Figure 6 is a cross-sectional perspective view in "close-up" of the lower adapter at the base of the pump.

[0015] Figure 7 is a cross-sectional view of the pump base with the lower adapter.

[0016] Figure 8 is a close-up cross-sectional view of the top adapter.

[0017] Figure 9 is a close-up cross-sectional view of the bottom adapter.

[0018] Figure 10 is a perspective view of the bottom adapter.

WRITTEN DESCRIPTION

[0019] Figure 1 shows an elevation view of a pumping system 100 attached to production pipe 102. Pumping system 100 and production pipe 102 are arranged in a well 104, which is drilled for the production of a fluid, such as water or oil. As used herein, the term "petroleum" refers widely to all mineral hydrocarbons, such as crude oil, gas and combinations of oil and gas. Production piping 102 connects pumping system 100 to a wellhead 106 located on the surface. Although the pumping system 100 is primarily designed to pump oil products, it will be understood that the present invention can also be used to move other fluids. It will also be understood that, although each component of the pumping system is first developed in a submersible application, some or all of these components can also be used in surface pumping operations.

[0020] It will be understood that, although pumping system 100 is shown in a vertical deployment in Figure 1, pumping system 100 can also be used in non-vertical applications, which include horizontal and non-vertical wells 104. Consequently, references to "upper" and "lower" in this disclosure are merely used to describe the relative positions of components of the pumping system 100 and should not be construed as an indication that the pumping system 100 needs to be installed in a vertical orientation.

[0021] Pumping system 100 includes a pump 108, a motor 110 and a sealing section 112. In some embodiments, motor 110 is an electric motor that receives power from a surface-mounted motor control unit (not shown) ). When energized, motor 110 drives a drive shaft that makes pump 108 run. The sealing section 112 provides the expansion of motor lubricants during operation and isolates the motor 110 from the well fluids that pass through the pump 108. Although only one of each component is shown, it will be understood that more components can be connected when appropriate. It may be desirable to use combinations of motor in parallel, multiple sealing sections, multiple pump assemblies or other downhole components not shown in Figure 1. For example, in certain applications it may be desirable to place a sealing section 112 below the motor

110.

[0022] Referring to Figure 2, a cross-sectional view of pump 108 is shown therein. Pump 108 includes a pump housing 114, a head 116, a base 118, a drive shaft 120 and a plurality of stages 122. As shown in the "close-up" view of Figure 3, each of the plurality of stages 122 includes a diffuser 124 and an impeller 126. Impellers 126 are connected to drive shaft 120 by a specially shaped connection that allows axial movement of impeller 126 along drive shaft 120. Thus, impellers 126 allow a limited amount of axial "fluctuation" between adjacent diffusers 124.

[0023] As shown in Figure 3, stages 122 of pump 108 are configured as floating stages 128 or with rolling stages 130. In each floating stage 128, impeller 126 transfers hydraulic load to the lower or upstream impeller 126 via a standard spacer 132 that passes through diffuser 124 without interference or contact. At each bearing stage 130, impeller 126 transfers thrust downward through a spacer 132 to a bearing spacer 136 through contact with a bearing pad 134 on the adjacent diffuser 124. In this way, the hydraulic charge created by a set of impellers 126 is transferred to a diffuser 124 in a rolling stage 130. It will be recognized that some or all of stages 122 can be configured as a rolling stage 130. As illustrated in Figures 2, 6 and 7, pump 108 may include also a separate lower bearing support 138 which includes a bearing pad 134 which displaces the thrust that passes through a bearing spacer 136.

[0024] Referring to Figures 4 and 5, cross-sectional views in "close-up" of a portion of the upper end of pump 108 are shown therein. The drive shaft 120 includes a standard upper ring groove 140 that is configured to receive a conventional two-piece ring (not shown), which would be used in a fixed impeller pump to capture the compression of the impeller stack. The two-piece ring has been replaced by an upper adapter 142 in the floating impeller design of pump 108. A close-up cross-sectional view of the upper adapter 142 is shown in Figure 8. The upper adapter 142 includes two halves of upper ring 144a and 144b. Each of the two upper ring halves 144a and 144b has a width that is configured to fit snugly in the upper ring groove 140. Each of the upper ring halves 144a and 144b additionally includes an upper adapter snap ring groove 146 and an upper adapter shoulder 148.

[0025] During assembly, the two upper ring halves 144a and 144b are placed in the upper ring groove 140 and brought together. An upper adapter snap ring 150 can then be placed in the upper adapter snap ring groove 146 to hold the two upper ring halves 144a and 144b together in the upper ring groove 140. In other embodiments , pressure screws or claws are used to hold the two upper ring halves 144a and 144b together. Once assembled, the upper adapter 142 remains attached to the drive shaft 120 to contain and position the standard spacers 132 and impellers 126 so that they can move axially along the drive shaft 120. The upper adapter 142 provides a lock and an upper limit for the downstream displacement of the upper impeller 126 and the spacers 132.

[0026] Referring to Figures 6 and 7, seen in cross-section in "close-up" of the lower end of the pump 108 are shown in them. The drive shaft 120 includes a lower ring groove 152 that is configured to receive a conventional two-piece ring (not shown), which would be used in a fixed impeller pump to capture the compression of the impeller stack. The two-piece ring has been replaced by a lower adapter 154 in the floating impeller design of pump 108. Cross-section and perspective views of lower adapter 154 are shown in Figures 9 and 10, respectively. The lower adapter 154 includes two lower ring halves 156a and 156b. Each of the two lower ring halves 156a and 156b has a width that is configured to fit snugly into the lower ring groove 152. Each of the lower ring halves 156a and 156b additionally includes a lower adapter snap ring groove 158 and a lower adapter shoulder 160.

[0027] During assembly, the two lower ring halves 156a and 156b are placed in the lower ring groove 152 and brought together. A lower adapter snap ring 162 can then be placed in the lower adapter snap ring groove 158 to hold the two lower ring halves 156a and 156b together in the lower ring groove 152. In other embodiments , pressure screws or claws are used to hold the two lower ring halves 156a and 156b together. Once assembled, the lower adapter 154 remains attached to the drive shaft 120 to contain and position the standard spacers 132 and the impellers 126 so that they can move axially along the drive shaft 120.

[0028] As best illustrated in Figure 6, the lower adapter 154 can be used in combination with the lower bearing support 138 to compensate for the downward thrust that is created along the drive shaft 120 and to enable the drive shaft 120 is lifted downstream in the event that the upward thrust forces exceed the downward thrust forces. The outer diameter of the lower adapter 154 is smaller than the inner diameter of the lower bearing support

138. This distance allows the lower adapter 154 to move within the lower bearing support 138, where the lower adapter shoulder 160 can push the bearing spacer 136 and any standard spacers 132 downstream along the drive shaft 120 within the tolerances provided by the spaces between the various components connected to the drive shaft 120.

[0029] Thus, the upper adapter 142 and the lower adapter 154 provide an efficient mechanism for positioning and retaining standard spacers 132, bearing spacers 136, impellers 126 and other components arranged along the outside of drive shaft 120. The upper adapter 142 and lower adapter 154 allow the conversion of a conventional compression drive shaft into a "floating" drive shaft without additional machining operations of the drive shaft 120. The ability to quickly and easily convert a drive shaft from compression on a floating drive shaft reduces inventory demands and improves parts interchangeability. Drive shafts removed from older fixed impeller pumps can be easily retrieved, converted and installed into a floating impeller pump with the top and bottom adapters 142 and 154.

[0030] It should be understood that, although numerous features and advantages of various embodiments of the present invention have been established in the previous description, along with details of the structure and functions of various embodiments of the invention, this disclosure is illustrative only and can be made changes to certain details, especially in terms of structure and part arrangement within the principles of the present invention, to the extent indicated by the broad general meaning of the terms in which the appended claims are expressed. It will be recognized 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.

Claims (20)

1. Pump for use in a motorized pumping system, the pump being characterized by comprising: a drive shaft, the drive shaft including a lower ring groove and an upper ring groove; a lower adapter, the lower adapter comprising a pair of lower ring halves configured to fit the lower ring groove; an upper adapter, the upper adapter comprising a pair of upper ring halves configured to fit the upper ring groove; a plurality of stages, each of the plurality of stages comprising: a stationary diffuser; and a rotating impeller connected to the drive shaft by a specially shaped connection that allows the impeller to move axially along the drive shaft. Pump according to claim 1, characterized in that the lower adapter additionally comprises a lower adapter pressure snap ring configured to hold the pair of lower ring halves together in the lower ring groove. Pump according to claim 1, characterized in that the upper adapter additionally comprises an upper adapter snap ring configured to hold the pair of lower ring halves together in the upper ring groove. Pump according to claim 1, characterized in that the lower adapter comprises a lower adapter shoulder that has an external adapter shoulder diameter. Pump according to claim 4, characterized in that it additionally comprises a lower bearing support that has an internal diameter that is greater than the external diameter of the adapter shoulder. Pump according to claim 5, characterized in that the lower bearing support comprises a bearing pad. 7. Pump according to claim 6, characterized in that it additionally comprises a bearing spacer connected to the drive shaft and configured to contact the bearing pad of the lower bearing support. 8. Submersible pumping system characterized by: an electric motor; a sealing section; and a multistage centrifugal pump driven by the motor, the pump comprising: a drive shaft, the drive shaft including a lower ring groove and an upper ring groove; a lower adapter, the lower adapter comprising a pair of lower ring halves configured to fit the lower ring groove; an upper adapter, the upper adapter comprising a pair of upper ring halves configured to fit the upper ring groove; and a plurality of stages, each of which among the plurality of stages comprises: a stationary diffuser; and a rotating impeller connected to the drive shaft by a specially shaped connection that allows the impeller to move axially along the drive shaft. A submersible pumping system according to claim 8, characterized in that the lower adapter additionally comprises a lower adapter pressure snap ring configured to hold the pair of lower ring halves together in the lower ring groove. 10. Submersible pumping system according to claim 8, characterized in that the upper adapter additionally comprises an upper adapter pressure snap ring configured to hold the pair of lower ring halves together in the upper ring groove. 11. Submersible pumping system according to claim 8, characterized in that the lower adapter comprises a lower adapter shoulder that has an adapter shoulder outside diameter. 12. Submersible pumping system according to claim 11, characterized in that it additionally comprises a lower bearing support that has an internal diameter that is greater than the external diameter of the adapter shoulder. 13. Submersible pumping system according to claim 12, characterized in that the lower bearing support comprises a bearing pad. 14. Submersible pumping system according to claim 13, characterized in that it additionally comprises a bearing spacer connected to the drive shaft and configured to contact the bearing pad of the lower bearing support. 15. Submersible pumping system according to claim 8, characterized in that the drive shaft does not include any ring groove other than the lower ring groove and the upper ring groove. 16. Method for converting a compression drive drive shaft into a floating drive drive shaft, the compression drive shaft including an upper ring groove and a lower ring groove which are respectively capable of holding a two-piece upper ring and a two-piece lower ring to apply compression to a stack of impellers arranged along the compression drive shaft, the method being characterized by comprising the steps of: placing an upper adapter in the upper ring groove ; place one or more impellers on the drive shaft; place one or more standard spacers on the drive shaft; and place a lower adapter in the lower ring groove. 17. Method according to claim 16, characterized in that it further comprises the step of placing one or more bearing spacers on the drive shaft before the step of placing a lower adapter in the lower ring groove. Method according to claim 16, characterized in that the step of placing an upper adapter in the upper ring groove further comprises: placing a first upper ring half in the upper ring groove; placing a second upper ring half in the upper ring groove; and securing the first and second upper ring halves together. Method according to claim 18, characterized in that the step of securing the first and second upper ring halves together further comprises placing an upper adapter snap ring over the first and second upper ring halves. 20. Method according to claim 16, characterized in that the step of placing a lower adapter in the lower ring groove further comprises: placing a first lower ring half in the lower ring groove; placing a second lower ring half in the lower ring groove; and securing the first and second lower ring halves together.