BR-112023018069-B1 - Interlock diffuser arrangement in a submersible electric pump.

BR112023018069B1BR 112023018069 B1BR112023018069 B1BR 112023018069B1BR-112023018069-B1

Abstract

INTERLOCKING DIFFUSER ARRANGEMENT IN A SUBMERSIBLE ELECTRIC PUMP. This is a submersible electric well pump that has non-rotating upper and lower diffusers mounted in a housing. A rotating propeller between the upper and lower diffusers has a lower casing. An outward-facing wall is at an upper end of the lower diffuser. A lower end of the upper diffuser has an inward-facing wall that fits tightly around the outward-facing wall of the lower diffuser. A key mounted between the inward-facing and outward-facing walls prevents relative rotation between the diffusers. The key extends axially above an upper end of the neck and radially into the inward-facing wall of the upper diffuser in close proximity to the lower casing, creating a sand dam.

Inventors

Zheng Ye
Mark Paquette

Assignees

BAKER HUGHES OILFIELD OPERATIONS LLC

Dates

Publication Date: 20260317
Application Date: 20220318
Priority Date: 20210322

Claims (11)

1. Submersible electric well pump characterized by comprising: a tubular housing having a longitudinal geometric axis; a non-rotating upper and lower diffuser mounted in the housing, wherein each of the diffusers has an outer wall in close contact with an inner wall of the housing; a drive shaft extending through the diffusers on the geometric axis; a propeller between the upper and lower diffusers and mounted on the drive shaft for simultaneous rotation, wherein the propeller has a lower casing; an outward-facing wall at an upper end of the lower diffuser having an outer diameter smaller than the outer wall of the lower diffuser, defining an upward-facing shoulder; the upper diffuser having an inward-facing wall that fits around the outward-facing wall of the lower diffuser, wherein the upper diffuser has a lower end that is contiguous with the upward-facing shoulder of the lower diffuser; a switch mounted between the inward-facing wall and the outward-facing wall to prevent relative rotation between the upper and lower diffusers; and wherein the key extends axially above an upper end of the outward-facing wall and radially into the inward-facing wall of the upper diffuser in close proximity to the lower casing, creating a sand dam to retard the agitation of the sand-laden water around the lower casing.
2. Pump, according to claim 1, characterized in that the key has an upper end that is closer to the lower casing than the upper end of the outward-facing wall; wherein the key is rectangular when viewed in cross-section; wherein it further comprises: an inward-facing slot in the inward-facing wall and an outward-facing slot in the outward-facing wall; wherein the key has an outer side that fits inside the inward-facing slot and an inner side that fits inside the outward-facing slot; an axial length of the key is not greater than an axial length of the inward-facing slot; and the axial length of the key is greater than an axial length of the outward-facing slot. wherein it further comprises: an inlet in the upper diffuser with an inward-facing inlet wall that converges in an upward direction; wherein the inward-facing wall joins and extends downward from the inlet wall, wherein the inward-facing wall is cylindrical and has an axial dimension greater than an axial dimension of the outward-facing wall; the upper end of the key is below a junction between the inlet wall and the inward-facing wall; wherein the key has an axial dimension greater than an axial dimension of the outward-facing wall and less than an axial distance from the upward-facing shoulder to the lower casing; wherein it further comprises a cushion secured with an interference fit within a lower diffuser receptacle to receive the downward thrust of the propeller; and an anti-rotation pin extending between the cushion and the receptacle to improve the non-rotation of the cushion relative to the lower diffuser.
3. Pump according to claim 2, characterized in that: the receptacle having a recessed hole with an upward-facing base; the cushion having an upper end with an external flange that enters the base; the pin being attached and projecting upwards from the base; and the flange having an opening that receives the pin.
4. Pump according to claim 3, characterized in that the opening has an elongated circumferential dimension and a radial dimension that is smaller than the circumferential dimension.
5. Submersible electric well pump characterized by comprising: a tubular housing having a cylindrical inner wall with a longitudinal geometric axis; a non-rotating upper and lower diffuser mounted in the housing; a drive shaft extending axially through the diffusers; a propeller between the upper and lower diffusers and mounted on the drive shaft for simultaneous rotation, wherein the propeller has a conical lower casing and a cylindrical skirt dependent on the lower casing that fits and engages in a cavity in the lower diffuser in a swivel sliding engagement; an upward-facing outer shoulder on the lower diffuser; an outward-facing wall extending upward from the upward-facing shoulder and spaced inward from the inner wall of the cabinet; a lower end of the upper diffuser having an inward-facing wall that fits around the outward-facing wall of the lower diffuser, wherein the lower end of the upper diffuser has a downward-facing edge that is contiguous with the upward-facing shoulder; a key mounted between the inward-facing wall and the outward-facing wall to prevent relative rotation between the upper and lower diffusers; and wherein the key extends axially above an upper end of the outward-facing wall and radially inward beyond the inward-facing wall towards the lower casing, creating a sand dam to slow the agitation of the sand-laden water around the lower casing.
6. Pump, according to claim 5, characterized in that the key has an upper end that is closer to the lower casing than an upper end of the outward-facing wall of the lower diffuser; wherein: the key has a clockwise-facing side and a counterclockwise-facing side, considering a direction of rotation of the propeller; the clockwise-facing side and the counterclockwise-facing side are flat and parallel to each other; wherein it further comprises: an inlet in the upper diffuser with an inlet wall facing inwards and converging in an upward direction; wherein the inlet wall joins and extends downwards from the inlet wall, wherein the inlet wall is cylindrical and has an axial dimension greater than an axial dimension of the outward-facing wall; and an inward-facing slot in the inlet wall; an outward-facing slot in the outward-facing wall; wherein the key fits within the inward-facing slot and the outward-facing slot; an axial length of the key is not greater than an axial length of the inward-facing slot; The axial length of the key is greater than the axial length of the outward-facing slot; wherein it further comprises: an inlet in the upper diffuser with an inward-facing inlet wall converging in an upward direction; wherein the inward-facing wall joins and extends downward from the inlet wall, wherein the inward-facing wall is cylindrical and has an axial dimension greater than an axial dimension of the outward-facing wall; an upper end of the key is below a junction between the inlet wall and the inward-facing wall; and wherein: the key has an axial dimension greater than an axial dimension of the outward-facing wall and less than an axial distance from the upward-facing shoulder to the lower casing.
7. Submersible electric well pump characterized by comprising: a tubular cabinet having a cylindrical inner wall with a longitudinal geometric axis; a plurality of non-rotating diffusers mounted in the cabinet; a drive shaft extending through the diffusers on the geometric axis; a plurality of impellers, each between two of the diffusers and mounted on the drive shaft for simultaneous rotation, wherein each of the impellers has a conical lower casing and a dependent cylindrical skirt that fits and engages in a cavity in a next lower diffuser of the diffusers in the rotating sliding engagement; an upward-facing outer shoulder on each of the diffusers; an outward-facing wall extending upward from each of the upward-facing shoulders and spaced inward from the inner wall of the cabinet; a lower end of a next upper diffuser of the diffusers having an inward-facing wall that fits around the outward-facing wall of the next lower diffuser of the diffusers, wherein the lower end of the next upper diffuser of the diffusers has a downward-facing edge that is in contiguity with the upward-facing shoulder of the next lower diffuser of the diffusers; an outward-facing slot extending axially in the outward-facing wall of each of the diffusers; an inward-facing slot extending axially in the inward-facing wall of each of the diffusers; a plurality of keys, wherein each of the keys is received, on the inner side, in one of the outward-facing slots and is received, on an outer side, in one of the inward-facing slots to prevent relative rotation between the upper and lower diffusers; wherein each of the keys has a lower end on the upward-facing shoulder and an upper portion projecting above the outward-facing slot of the diffuser in which it is carried; and the upper portion of each of the keys extends radially inward beyond the inward-facing wall towards the lower casing of a next upper propeller of the propellers, creating a sand dam to retard the agitation of the sand-laden water around the lower casing.
8. Pump, according to claim 7, characterized in that the upper portion of each of the keys has an upper end that is closer to the lower casing of the next upper propeller of the propellers than the upper end of the outward-facing slot in which each of the keys is mounted.
9. Pump according to claim 7, characterized in that: each of the keys projects from the inward-facing slot at a radial distance greater than a radial depth of the inward-facing slot.
10. Pump, according to claim 7, characterized in that: each of the keys has one side facing clockwise and one side facing counterclockwise, considering the direction of rotation of the propellers; and the side facing clockwise and the side facing counterclockwise are flat and parallel to each other.
11. Pump, according to claim 7, characterized by further comprising: an inlet in each of the diffusers with an inlet wall facing inwards and converging in an upward direction; wherein the inlet wall joins and extends downwards from the inlet wall, wherein the inlet wall is cylindrical and has an axial dimension greater than an axial dimension of the outward-facing wall; and an upper end of each of the keys is below a junction between the inlet wall and the inlet wall of each of the diffusers.

Description

FIELD OF REVELATION: [0001] This disclosure relates generally to electric submersible well pumps ("ESP"), particularly to a centrifugal pump having diffusers with an interlocking arrangement. BACKGROUND: [0002] Electric submersible well pumps are frequently used to pump well fluid from producing hydrocarbon wells. A typical ESP has a multi-stage centrifugal pump, where each stage has a diffuser and an impeller. The diffusers are stacked together in a pump housing and prevented from rotating. Each diffuser has a downward-facing shoulder that is contiguous with an upward-facing shoulder of the diffuser directly below. A bearing at the top of the diffuser stack has threads that engage the pump housing and which, when tightened, exert a compressive force on the diffuser stack. The coupling diffuser shoulders are perpendicular to the longitudinal geometric axis of the pump housing. [0003] In one type, each propeller and diffuser stage has an abrasion-resistant stage bearing that rotates with the drive shaft and typically transfers downward thrust and upward thrust to a coupling diffuser. The abrasion-resistant components serve to resist abrasion when the pump is pumping sandy well fluid. Each stage bearing has a rotating component that fits inside a non-rotating cushion of a coupling diffuser. In another type, the central propeller drivers contact each other to transfer downward thrust and upward thrust to the propellers above and below. The cushions and the rotating portions of the bearing that engage them are usually made of tungsten carbide. The cushions are normally pressed into a receptacle in each diffuser. To further prevent rotation, an upper portion of each diffuser is fixed or deformed over a cushion top. [0004] The propeller and diffuser are normally cast from an iron-nickel alloy. The hardness of the alloy is much lower than the hardness of the abrasion-resistant components. Producing a propeller and diffuser from harder material would reduce erosion from sand-laden well fluid. However, harder material is usually more brittle. Compressing the diffusers into a pile to a certain extent as is done in the prior art can cause cracking. Furthermore, attaching the cushions to the diffusers creates difficulties with more brittle diffusers. SUMMARY: [0005] A submersible electric well pump has a tubular housing with a longitudinal geometric axis. The upper and lower diffusers are mounted in a non-rotating manner in the housing. Each diffuser has an outer wall that closely meets an inner wall of the housing. A drive shaft extends through the diffusers along the geometric axis. A propeller between the upper and lower diffusers mounts the drive shaft for simultaneous rotation. The propeller has a lower casing with a skirt that fits and engages with a cavity in the lower diffuser in a swivel-sliding engagement. An outward-facing wall at an upper end of the lower diffuser has a smaller outer diameter than the outer wall of the lower diffuser, defining an upward-facing shoulder. A lower end of the upper diffuser has an inward-facing wall that fits relative to the outward-facing wall of the lower diffuser. The lower end of the upper diffuser is contiguous with the upward-facing shoulder of the lower diffuser. A key mounted between the inward-facing and outward-facing walls prevents relative rotation between the upper and lower diffusers. The key extends axially above an upper end of the neck and radially into the inward-facing wall of the upper diffuser in close proximity to the lower envelope, creating a sand dam to retard the agitation of sand-laden water around the lower envelope. [0006] In the embodiment shown, the key has an upper end that is closer to the lower casing than the upper end of the lower diffuser. The key may be rectangular when viewed in cross-section. [0007] In the embodiment shown, an inward-facing slot is formed in the inward-facing wall and an outward-facing slot is formed in the outward-facing wall. The key has an outer side that fits inside the inward-facing slot and an inner side that fits inside the outward-facing slot. An axial length of the key is not greater than an axial length of the inward-facing slot. The axial length of the key is greater than an axial length of the outward-facing slot. [0008] An inlet in the upper diffuser has an inlet wall facing inwards and converging in an upward direction. The inlet wall joins and extends downwards from the inlet wall. The inlet wall is cylindrical and has one axial dimension greater than one axial dimension of the outward wall. The upper end of the key is below a junction between the inlet wall and the inlet wall. [0009] The key has an axial dimension greater than an axial dimension of the outward-facing wall. This axial dimension may be less than an axial distance from the upward-facing shoulder to the lower casing. [0010] A cushion can be attached with an interference fit inside a lower diffuser receptacle to receive the downward thrust of t