CA2984293A1

CA2984293A1 - Sleeves and a method of manufacturing sleeves for rotating equipment applications

Info

Publication number: CA2984293A1
Application number: CA2984293A
Authority: CA
Inventors: Pradeep Dass
Original assignee: 1589549 Alberta Ltd
Current assignee: 1589549 Alberta Ltd
Priority date: 2016-11-01
Filing date: 2017-11-01
Publication date: 2018-05-01

Abstract

A sleeve for use in rotating equipment has a sleeve body having an inner surface, an outer surface, a first end and a second end. At least one groove is formed in and extends axially along the inner surface of the sleeve body, the groove being open at the first end and closed at the second end of the sleeve body.

Description

SLEEVES AND A METHOD OF MANUFACTURING SLEEVES FOR ROTATING
EQUIPMENT APPLICATIONS
TECHNICAL FIELD
[0001] This relates to protective sleeves for use on a rotating shaft of rotating equipment.
BACKGROUND

[0002] Bush bearings or sleeves are used in downhole or surface equipment with rotating shafts, such as pumps including ESP (Electric Submersible Pumps) and ESTSP
(Electric Submersible Twin Screw Pumps), motors, etc. These may be used under hydrodynamic and/or hydrostatic pressures. As used herein, this type of equipment with a rotating shaft within a housing, may be generally classified as rotating equipment.

[0003] In most downhole equipment, various forms of sleeves and/or bushings are used in various materials. Common materials include tungsten carbide, silicon carbide, silicon nitride, bronze, Ni Resist or various other materials with a low coefficient of friction, including elastomers and plastics, such as PEEK. Similar materials are also used in surface equipment.
As used herein, the term sleeve is intended to refer generally to bearings, bushings, and other types of protective sleeves commonly found in rotating equipment.

[0004] The purpose of these sleeves is primarily for radial loading, although it is not uncommon to provide projections at the ends to carry some axial load as well.
Generally, the sleeves or bearings have square grooves running axially through the internal diameter or outer diameter, depending on where the sleeves are to be locked on the shaft. The keys are located within these grooves. Since square grooves create stress at the keyway corners, some tend to use rounded keys. The rounded keys seem to demonstrate an improvement over square grooves, though it may tend to run over the key under severe radial loading.

[0005] In the case of ESP and ESTSP pumping a multiphase fluid, severe radial loads are applied to the sleeves and cracks are seen widely. This can bring about premature failure of the rotating equipment. Gas and low viscosity fluids passing through the sleeves also increase the failure rate. Some designs even use keyless profiles with side projections that hold the sleeves in place. However, even these are susceptible to premature cracks under high gas or when in low lubricity conditions.
SUMMARY

[0006] There is provided a sleeve for use in rotating equipment. The sleeve comprises a sleeve body having an inner surface, an outer surface, a first end and a second end. At least one groove is formed in and extends axially along the inner surface of the sleeve body. The groove is open at the first end and closed at the second end of the sleeve body.

[0007] According to other aspects, the sleeve may further comprise one or more of the following features, alone or in combination: the sleeve may comprise two or more grooves;
the at least one groove may have a rectangular cross-section or a rounded cross-section; and the at least one groove may axially extend between 0.5 to 0.75 of the inner surface of the sleeve body.

[0008] According to an aspect, there is provided a method of operating rotating equipment, the rotating equipment having a housing, an inner bearing surface that is fixed relative to the housing, and a rotating shaft that rotates relative to the housing and the inner bearing surface. The method comprises the steps of: providing a sleeve having an inner surface, an outer surface, a first end a second end, and at least one groove formed in and extending axially along the inner surface of the sleeve body, the groove being open at the first end and closed at the second end of the sleeve body; installing the sleeve on the rotating shaft, the rotating shaft having an external profile that engages the sleeve surface such that the sleeve rotates with the shaft, and the outer surface of the sleeve engages the inner bearing surface of the rotating downhole equipment a non-rotating bearing surface of the rotating downhole; and rotating the sleeve within the housing.

[0009] According to other aspects, the method may comprise one or more of the following features, alone or in combination: the external profile may comprise removable keys that simultaneously engage the grooves of the sleeve and corresponding grooves of the shaft; at least one groove may be formed in and extend axially along the inner surface of the sleeve body, the groove being open at the second end and closed at the first end of the sleeve body; the at least one groove may have a rectangular cross-section or a rounded cross-section;

and the at least one groove may axially extend between 0.5 to 0.75 of the inner surface of the sleeve body.

[0010] According to an aspect, there is provided, in combination, a rotating equipment assembly and a sleeve. The rotating equipment assembly comprises a housing, an inner bearing surface that is fixed relative to the housing, and a rotating shaft that rotates relative to the housing and the inner bearing surface, the rotating shaft having an external profile. The sleeve comprises a sleeve body having an inner surface, an outer surface, a first end and a second end, and at least one groove formed in and extending axially along the inner surface of the sleeve body. The groove is open at the first end and closed at the second end of the sleeve body. The groove is engaged with the external profile of the rotating shaft such that the sleeve is rotationally fixed with the rotating shaft.

[0011] According to other aspects, the combination may comprise one or more of the following features, alone or in combination: removable keys that simultaneously engage the external profile of the shaft and the at least one grooves of the shaft; the sleeve may comprise two or more grooves; the at least one groove of the sleeve may have a rectangular cross-section or a rounded cross-section; the at least one groove of the sleeve may axially extend between 0.5 to 0.75 of the inner surface of the sleeve body; the rotating equipment assembly may be a rotary pump, and the shaft may be a drive shaft of the rotary pump.

[0012] In other aspects, the features described above may be combined together in any reasonable combination as will be recognized by those skilled in the art.
BRIEF DESCRIPTION OF THE DRAWINGS

[0013] These and other features will become more apparent from the following description in which reference is made to the appended drawings, the drawings are for the purpose of illustration only and are not intended to be in any way limiting, wherein:
FIG. 1 is a perspective view of sleeves mounted to a rotating shaft.
FIG. 2 is a perspective view of a prior art sleeve for rotating equipment.
FIG. 3 is a perspective view of a sleeve for rotating equipment.
FIG. 4 is a cross-sectional view of rotating equipment having installed sleeves.

DETAILED DESCRIPTION

[0014] A sleeve for rotating equipment, generally identified by reference numeral 10, will now be described with reference to FIG. 1 through 4.

[0015] The presently described sleeve is designed to reduce the risk of premature failure.
It was initially designed for ESTSP and ESP applications; however the same design can be easily adapted for any rotating equipment where sleeves are used. The sleeve may have particular benefits in applications where the sleeve will be immersed in either fluid or in very high gas applications.

[0016] Referring to FIG. 1, there is shown sleeves 10 mounted to a rotating shaft 12. The depicted shaft 12 includes a rotor 14, although it will be understood that sleeve 10 and shaft 12 may be used in other rotating equipment as well. Referring to FIG. 4, sleeve 10 engages an inner bearing surface 15 of a housing 16.

[0017] Referring to FIG. 3, sleeve 10 has one or more grooves 18 on an inner surface 20 that do not extend the full length of sleeve 10. It has been found that the stress of grooves 18 can be minimized if grooves 18 are cut off before the end on the other end. A
preferred embodiment includes multiple grooves 18, such as splines, with a blind at one end. It will be understood that the number of grooves may vary. For example, there may be two grooves 18, or a single groove 18, or additional grooves, depending on the torque to be transferred from shaft 12 to sleeve 10. It has been found that this design has a particular utility in multiphase applications where there is a very high proportion of gas, and the sleeves are under severe stress at the key grooves. Referring to FIG. 4, sleeve 10 is installed on shaft 12 by engaging grooves 18 with a corresponding profile carried by shaft 12, which may include removable keys 24 that engage grooves 18 and corresponding grooves 22 on shaft 12, or permanent splines (not shown) carried by shaft 12.

[0018] Referring to FIG. 2, previous sleeves 11 have been formed with a groove 19 extending from one end of the sleeve 11 to the other. In a sleeve or bushing where the groove goes from one end to the other, it has been found that cracks propagate swiftly to the other end, and may give rise to a failed sleeve and complete destruction of the rotating equipment.
When using a round groove, a square groove, or any other groove with a blind end, it has been found that the stress is minimized and crack propagation is minimized. By providing a blind end, the stress is minimized at the weakest point, which is the key groove. In one example, the provided groove ran about halfway along the length of the sleeve.
In another example, the grooves started at either end and ran for a total of about one half the length of the sleeve. The actual length of the groove, or the length of the groove relative to the sleeve, may vary depending on the circumstances, such as loads to be applied.

[0019] Various testing methods can be used to find out the best overall length of key and number of keys per sleeve by using a model analysis and physical testing. The final design will be based on the material, diameter, rpm and the operating conditions, such as the fluid the sleeves will be immersed in during rotation. The design is extremely useful for multiphase or high gas applications, but may also be used in single liquids or other mediums for more reliability.

[0020] When using multiple key grooves on the sleeves, the grooves may all start from one end and be blind at the other at a pre-determined axial length, or the grooves may extend in from either end of the sleeve, and be blinded before the respective groove reaches the end of the other groove. The length of groove and where it needs to stop or be blinded is determined by the material, coefficient of friction of the material, groove size, key type, intended operating conditions, such as the fluid(s) it is going to be immersed in during rotation, etc.

[0021] Preferably, grooves 18 extend no more than three-quarters of the length of sleeve 10, or between one-half to three quarters of the length of sleeve 10. The design of grooves 18 will depend on the torque to be transferred from shaft 12 to sleeve 10, which will help determine the number of grooves 18, the length of grooves 18, etc.

[0022] Sleeve 10 is preferably used in situations in which there may be low lubricity as a constant operating condition, or a risk of low lubricity. For example, the components in ESPs are generally cooled and lubricated by the fluid that is pumped through them.
If the fluid were to have a higher gas content, there would be less liquid to cool and lubricate the bearings, resulting in more heat being generated as sleeve 10 rotates against bearing surface 15. As sleeves are generally made from materials that are quite brittle with low ductility, such as tungsten carbide, silicon carbide, silicon nitride, or other type of bearing material, any cracking, such as may be caused by excessive heat, may result in failure of the sleeve. It has been found that by providing shorter grooves 18 that do not extend the full length of sleeve 10, the risk of cracking can be reduced, or if cracking occurs, may be localized at least temporarily to the portion of sleeve 10 along which grooves 18 extend, leaving the remainder of sleeve 10 able to operate and avoid additional damage to the equipment that would result from the complete failure of sleeve 10.

[0023] In one example, testing was successfully completed by varying the fluids from 100 % liquid to 97 % gas with full a full load continuously applied without any cracks or crack propagation of any kind being observed. The design described herein may be adapted for use in various hydrodynamic or hydrostatic sleeves under severe loading conditions. It has been found that, by designing sleeve 10 in this manner, sleeves can be used in conditions that otherwise would result in the failure of sleeve 10, and conditions under which the failure of sleeve 10 would be predicted or expected.

[0024] In this patent document, the word "comprising" is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article "a" does not exclude the possibility that more than one of the elements is present, unless the context clearly requires that there be one and only one of the elements.

[0025] The scope of the following claims should not be limited by the preferred embodiments set forth in the examples above and in the drawings, but should be given the broadest interpretation consistent with the description as a whole.

Claims

What is Claimed is:

1. A sleeve for use in rotating equipment, comprising:
a sleeve body having an inner surface, an outer surface, a first end and a second end;
at least one groove formed in and extending axially along the inner surface of the sleeve body, the groove being open at the first end and closed at the second end of the sleeve body.

2. The sleeve of claim 1, further comprising two or more grooves.

3. The sleeve of claim 1, wherein the at least one groove has a rectangular cross-section or a rounded cross-section.

4. The sleeve of claim 1, wherein the at least one groove axially extends between 0.5 to 0.75 of the inner surface of the sleeve body.

5. A method of operating rotating equipment having a housing, an inner bearing surface that is fixed relative to the housing, and a rotating shaft that rotates relative to the housing and the inner bearing surface, the method comprising the steps of:
providing a sleeve having an inner surface, an outer surface, a first end a second end, and at least one groove formed in and extending axially along the inner surface of the sleeve body, the groove being open at the first end and closed at the second end of the sleeve body;
installing the sleeve on the rotating shaft, the rotating shaft having an external profile that engages the sleeve surface such that the sleeve rotates with the shaft, and the outer surface of the sleeve engages the inner bearing surface of the rotating downhole equipment a non-rotating bearing surface of the rotating downhole; and rotating the sleeve within the housing.

6. The method of claim 1, wherein the external profile comprises removable keys that simultaneously engage the grooves of the sleeve and corresponding grooves of the shaft.

7. The method of claim 5, further comprising at least one groove formed in and extending axially along the inner surface of the sleeve body, the groove being open at the second end and closed at the first end of the sleeve body.

8. The method of claim 5, wherein the at least one groove has a rectangular cross-section or a rounded cross-section.

9. The method of claim 5, wherein the at least one groove axially extends between 0.5 to 0.75 of the inner surface of the sleeve body.

10. In combination:
a rotating equipment assembly, comprising:
a housing;
an inner bearing surface that is fixed relative to the housing; and a rotating shaft that rotates relative to the housing and the inner bearing surface, the rotating shaft having an external profile; and a sleeve, comprising:
a sleeve body having an inner surface, an outer surface, a first end and a second end;
at least one groove formed in and extending axially along the inner surface of the sleeve body, the groove being open at the first end and closed at the second end of the sleeve body, the groove being engaged with the external profile of the rotating shaft such that the sleeve is rotationally fixed with the rotating shaft.

11. The combination of claim 10, further comprising removable keys that simultaneously engage the external profile of the shaft and the at least one grooves of the shaft.

12. The combination of claim 10, wherein the sleeve comprises two or more grooves.

13. The combination of claim 10, wherein the at least one groove of the sleeve has a rectangular cross-section or a rounded cross-section.

14. The combination of claim 10, wherein the at least one groove of the sleeve axially extends between 0.5 to 0.75 of the inner surface of the sleeve body.

15. The combination of claim 10, wherein the rotating equipment assembly is a rotary pump, and the shaft is a drive shaft of the rotary pump.