WO2016025259A1

WO2016025259A1 - Centrifugal pump with integral filter system

Info

Publication number: WO2016025259A1
Application number: PCT/US2015/043743
Authority: WO
Inventors: Stefan Werner
Original assignee: Imo Industries, Inc.
Priority date: 2014-08-15
Filing date: 2015-08-05
Publication date: 2016-02-18

Abstract

A filtration system for a multi-stage centrifugal pump eliminates particulate contaminant matter from the pumped fluid. The pump includes at least one stage, the at least one stage comprising an impeller. A drainage conduit is provided adjacent to the pump casing and is connected to the drainage conduit opening so that particulate contaminant material, along with a first portion of pumped fluid, ejected from the impeller passes through the drainage conduit opening and into the drainage conduit. A pipe or other connection near the bottom of the pump can collect the particulate contaminant. In some arrangements a filter element is coupled to the outer diameter of the impeller or to a surface of the pump casing to further eliminate contaminant matter from the pumped fluid.

Description

CENTRIFUGAL PUMP WITH INTEGRAL FILTER SYSTEM

Cross-Reference to Related Applications

[0001] This is a non-provisional of pending US provisional patent application serial number 62/037,752, filed August 15, 2014, the entirety of which application is incorporated by reference herein.

Field of the Disclosure

[0002] The disclosure is generally related to the field of centrifugal pumps, and more particularly to a centrifugal pump having an integral filter arrangement

Background of the Disclosure

[0003] For pumping systems servicing machine tool coolant loops, foreign matter can be introduced into the coolant when such matter is generated during processing of workpieces. The foreign matter is often returned with the coolant to a coolant tank where a certain percentage is eliminated using a strainer or the like. Small pieces of foreign matter can pass by the strainer and can remain in the coolant as a contaminant.

[0004] In some installations a filter is used to remove these small dimensioned contaminants. Problems with such filters include frequent clogging, and thus, the filters require periodical maintenance to replace or clean the filter elements. Although

"maintenance free" filters such as cyclone filters have been used, they suffer from poor performance in removal of contaminants. In addition, such conventional filter arrangements consume large amounts of added space, and produce increased cost in terms of equipment (filter material) as well as increased operational energy. [0005] Thus, there is a need for an improved filter arrangement for removing contaminants from pumped fluids. There is also a need for an improved filter arrangement that does not consume a large amount of space, and which does not substantially increase cost in terms of equipment and operational energy.

Summary

[0006] A pump is disclosed, comprising at least one stage. The at least one stage may include an impeller. The at least one stage further may include a drainage conduit opening. The pump may further include a casing, and a drainage conduit adjacent to the casing. The drainage conduit may be connected to the drainage conduit opening such that particulate material and a first portion of pumped fluid that is ejected from the impeller through the drainage conduit opening is directed into the drainage conduit.

[0007] A filter element may be connected to the impeller. The filter element may have a height. The filter element may be sized to prevent the particulate material from rejoining a flow path of a second portion of pumped fluid that is directed toward a next adjacent stage of said pump. The filter element may rotate with the impeller during operation. The height may be selected such that the filter element does not impact any internal surfaces of the pumps during operation.

[0008] The pump may further include a protective layer on a surface of the pump adjacent to the drainage conduit opening. The protective layer may comprise a relative hard material or an elastomeric material. [0009] An impeller is disclosed, comprising an impeller portion, and a filter portion coupled to a surface of the impeller portion for filtering fluid pumped by the impeller portion. The filter portion may be coupled to an outer surface of the impeller portion, such as at the outer diameter of the impeller portion. The filter portion may comprise a cylindrical element having an inside diameter corresponding to an outside diameter of the impeller portion.

[0010] The filter portion may be coupled to the impeller portion by at least one of welding, brazing and adhesive. The filter portion may have a mesh size of 5 μιη to 160 μιη. The filter portion is coupled to the impeller portion such that the filter portion and the impeller portion rotate together.

Brief Description of the Drawings

[0011] By way of example, specific embodiments of the disclosed device will now be described, with reference to the accompanying drawings, in which:

[0012] FIG. 1 is a side view of an exemplary pump according to the disclosure;

[0013] FIG. 2 is a cross-section view of the pump of FIG. 1;

[0014] FIG. 3 is a partial cross-section view of the pump of FIG. 2 including the disclosed integral filter system;

[0015] FIG. 4 is a top view of an exemplary impeller with the exemplary filter element of FIG. 3; and

[0016] FIG. 5 is a cross-section view taken alone line 5-5 of FIG. 4. Detailed Description

[0017] FIG. 1 shows an exemplary vertical multistage centrifugal pump 1 having a motor 2, a shaft 4, a coupling 6, a shaft seal 8, a plurality of impellers 10 coupled to the shaft, and a casing 12.

[0018] FIG. 2 is a cross-section of a portion of the pump 1 showing the internal arrangement of impellers 10 within a respective plurality of chambers 14. As will be understood, the plurality of chambers 14 generally form the pump casing 12. The pump casing 12 is coupled to the motor via a flange 16. A suction strainer 18 may be disposed at the inlet 20 of the pump 1 to prevent large particles or foreign matter from entering the pump interior. Thus arranged, fluid may enter the inlet 20 of the pump and may pass through a plurality of stages formed by a plurality of impellers 10 and chambers 14. The fluid is then discharged through the pump outlet 22.

[0019] As noted, it may be desirable to remove small-dimensioned contaminants from the pumped fluid. Referring to FIG. 3, an arrangement is shown in which an integral filter system is provided in the plurality of stages to remove such contaminants. As will be described in greater detail, the integral filter system exploits the centrifugal forces generated by the impellers to separate the contaminants from the pumped fluid and to prevent the contaminants from re-entering the main fluid flow path.

[0020] In the illustrated embodiment, the pump 1 includes a plurality of individual stages (1, 2, . . . N, N+l), each including an impeller 10a, 10b . . . 10η, lOn+i. It will be appreciated that the illustrated number of stages is merely exemplary, and greater or fewer stages can be provided.

[0021] The pump 1 may include a drainage conduit 30 disposed inboard of the circumference of the casing 12 to enable a quantity of fluid and contaminant particles to be directed out of the pump. The drainage conduit 30 may run substantially the height "CH" of the casing 12 so that contaminant particles removed from each of the pump stages can be directed out of the casing via an outlet 32 disposed in a lower portion of the pump.

[0022] In an alternative embodiment, the casing 12, or the casing portion that forms the outer limit of the drainage conduit 30, can be configured so that each pump stage (1, 2 . . . N, N+l) has its own discrete casing section. As such, individual stages may be stacked in variable numbers to suit a particular application, eliminating the need to manufacture a casing having a custom (variable) length.

[0023] In order to direct contaminant particles to the drainage conduit 30, each stage of the pump may include a circumferential shroud element 34. The shroud elements 34 may each have an upper portion 36 connected to an upper surface of the associated chamber 14, and a lower portion 38 that extends downward, substantially parallel to, and spaced apart from, the pump casing 12. The lower portion 38, along with the pump casing 12, thus forms a drainage conduit opening and also forms part of the drainage conduit 30.

[0024] Each stage of the pump 1 may further include a flow shaping shroud element 39 that serves to shape the flow of the pumped fluid after it exits the associated impeller. As can be seen, the flow shaping shroud elements 39 have a curved portion 39a configured to direct the flow of the pumped fluid upward toward the next adjacent stage. The flow shaping shroud elements 39 may also have a drainage flow directing portion 39b that, along with the casing 12 forms an inner surface of the drainage conduit 30. As can be seen, the drainage flow, with contaminants, flows between the drainage flow directing portion 39b and the lower portion 38 of the associated shroud element 34 where it is directed to the drainage conduit 30.

[0025] As can be seen in FIG. 3, fluid (with contaminant particles entrained) is expelled from the circumference of the impeller 10 and travels in the direction of arrow "A" to the next stage (or out of the pump in the case of the final stage). As fluid flows out of the impeller 10, the centrifugal forces applied to the fluid and contaminants as they leave the impeller cause the relatively heavier contaminants to be forced outward toward the drainage conduit 30. This flow path (of contaminants) is illustrated by arrow "B."

[0026] Thus, a first portion of the pumped fluid is filtered as it is directed to the next adjacent stage. A second portion of the pumped fluid is ejected, along with the contaminants, into the drainage conduit 30. In this way the disclosed arrangement functions in the manner of a cyclone separator. Once in the drainage conduit 30, the contaminant particles, along with a limited amount of pumped fluid, flow downward due to the pressure formed by the pump stages until they enter the outlet 32.

[0027] To reduce wear adjacent to the drainage conduit 30 due to relatively high speed fluid and contaminant impact, a protective layer 33 comprising a relative hard or elastomeric material can be provided on the shroud elements 34. In one embodiment the protective layer 33 can be a polymer material. In other embodiments the protective layer 33 can be a ceramic material or a hard metal. In other embodiments the shroud elements themselves may be thicker in the outlet region to accommodate expected wear.

[0028] In the illustrated embodiment the outlet 32 is positioned adjacent to the first stage of the pump 1. It will be appreciated, however, that it could be formed at one or more other locations about the pump, and multiple outlets are also contemplated. Pipe or tubing (not shown) can be coupled to the outlet 32 either directly or via appropriate fittings. In this manner a quantity of contaminant rich fluid may be directed to a drain, a conveyor or other devices appropriate for removing dirt out of the tank.

[0029] At least some of the impellers 10b - lOn+i can further include a filter element 24 coupled to an outer surface of the impeller. In one exemplary embodiment the filter element 24 can be coupled to the outer diameter of the impeller. In another embodiment the filter element 24 can be coupled to another surface of the pump 1 , such as a surface of the associated chamber 14. The filter element 24 can comprise a cylindrical shape. For embodiments in which the filter element 24 is coupled to the outer diameter 26 of the impeller the filter element 24 can have an inner diameter that corresponds to the outer diameter of the impeller 10. In some embodiments the filter element 24 is fixed to the impeller 10 by welding, brazing, adhesive, or the like. This arrangement is shown in greater detail in FIGS. 4 and 5.

[0030] The filter element 24 may have a height "H" sized to position an upper edge 28 of the filter element adjacent to a bottom surface of the next adjacent stage without contacting that bottom surface. As arranged, the filter element 24 rotates along with its associated impeller 10 without impacting or otherwise engaging any other portion of the pump 1. For embodiments in which the filter element 24 is not coupled to the impeller, but is instead coupled to another surface of the pump (such as a surface of the chamber 14), the filter element may be stationary as the impeller rotates. As fluid flows through the filter element 24 on its way to the next stage (in the direction of arrow "A," contaminants larger than a predetermined size are prevented from passing through the filter element. Thus, the filter element 24 may have a mesh size selected to prevent contaminants larger than a predetermined size from passing therethrough. Exemplary mesh size stages can be: 160 μιη, 100 μιη, 60 μιη, 40 μιη, 30 μιη + additional finer stages such as 20 μιη, 15 μιη, 10 μιη, 7 μιη, 5 μιη as desired. In some embodiments the mesh size decreases with each successive pump stage. The finer the stage, the more flow resistance the filters produce, so it can be desirable to equip only as many stages as necessary with a filter element. The same holds true for the drainage conduit openings which also produce a loss of flow. In some embodiments it may be reasonable to equip the last stages with a cyclone filter function (i.e., the last stages would not include a filter element), and to not use a finer mesh than e.g. 15 μιη for the last stage that incorporates a filter. This is because, for example, emulsions may be separated into oil and water when the mesh size gets too low.

[0031] Vortices, induced by guide vanes or other means will serve to detach contaminant particles from the filter element 24 and thus will ensure that the filter element does not clog over time. These vortices will also facilitate movement of the contaminant particles into the drainage conduit 30. [0032] As can be seen, the disclosed multi-stage filter with self-cleaning filter elements and multistage cyclone separators are integrated in a centrifugal pump 1 without the additional of substantial additional space. Only the outer diameter of the pump may be slightly increased as compared to a traditional pump.

[0033] As will be appreciated the disclosed arrangement also avoids backflow from the drain path (via the drainage conduit 30) back into the pump. Although the fluid pressure of the upper stages will be higher than the pressure of the lower stages, with the disclosed design such a condition will not cause flow in the drainage conduit 30 to flow out into the lower stages. This is because the area at which the outer and the inner flow of the drainage path meet works like an injector pump. That is, the outer flow acts to pull the inner flow into the drainage conduit 30. Further, because at every lower stage more flow is directed to the drainage conduit 30, flow speed in the drainage conduit increases as it moves toward the next lower pump stage. With higher speed the static pressure drops so that the pressure difference between the inner and the outer drain areas may be very low, and in some cases the inner pressure at the lower stages may be higher than the outer pressure (i.e., the pressure in the drainage conduit 30).

[0034] Based on the foregoing information, it will be readily understood by those persons skilled in the art that the present invention is susceptible of broad utility and application. Many embodiments and adaptations of the present invention other than those specifically described herein, as well as many variations, modifications, and equivalent arrangements, will be apparent from or reasonably suggested by the present invention and the foregoing descriptions thereof, without departing from the substance or scope of the present invention. Accordingly, while the present invention has been described herein in detail in relation to its preferred embodiment, it is to be understood that this disclosure is only illustrative and exemplary of the present invention and is made merely for the purpose of providing a full and enabling disclosure of the invention. The foregoing disclosure is not intended to be construed to limit the present invention or otherwise exclude any such other embodiments, adaptations, variations, modifications or equivalent arrangements; the present invention being limited only by the claims appended hereto and the equivalents thereof. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for the purpose of limitation

Claims

1. A pump, comprising:

at least one stage, comprising:

an impeller, and

a drainage conduit opening;

a casing, and

a drainage conduit adjacent to the casing, the drainage conduit connected to the drainage conduit opening such that particulate material and a first portion of pumped fluid that is ejected from the impeller through the drainage conduit opening is directed into the drainage conduit.

2. The pump of claim 1, further comprising a filter element connected to the impeller, the filter element having a height.

3. The pump of claim 1, further comprising a filter element connected to a casing surface of the pump, the filter element having a height.

4. The pump of claim 2 or 3, wherein the filter element is sized to prevent the particulate material from rejoining a flow path of a second portion of pumped fluid that is directed toward a next adjacent stage of said pump.

5. The pump of claim 2 or 3, wherein the filter element rotates with the impeller during operation.

6. The pump of claim 2 or 3, wherein the height is selected such that the filter element does not impact any internal surfaces of the pumps during operation.

7. The pump of claim 1, further comprising a protective layer on a surface of the pump adjacent to the drainage conduit opening.

8. The pump of claim 7, wherein the protective layer comprises a relative hard material or an elastomeric material.

9. The pump of claim 1, wherein the pump has a plurality said stages.

10. An impeller, comprising:

an impeller portion, and

a filter portion coupled to the impeller portion, the filter portion for filtering fluid pumped by the impeller portion.

11. The impeller of claim 10, wherein the filter portion is coupled to an outside diameter of the impeller portion.

12. The impeller of claim 11, wherein the filter portion comprises a cylindrical element having an inside diameter corresponding to an outside diameter of the impeller portion.

13. The impeller of claim 10, wherein the filter portion is coupled to the impeller portion by at least one of welding, brazing and adhesive.

14. The impeller of claim 10, wherein the filter portion has a mesh size of 5 μιη to 160 μιη.

15. The impeller of claim 14, wherein the filter portion is coupled to the impeller portion such that the filter portion and the impeller portion rotate together.