US3540834A

US3540834A - Apparatus for pumping liquids containing solids

Info

Publication number: US3540834A
Application number: US759472A
Authority: US
Inventors: Robert W Allerton
Original assignee: Worthington Corp
Current assignee: Edison International Inc
Priority date: 1968-09-12
Filing date: 1968-09-12
Publication date: 1970-11-17
Anticipated expiration: 1987-11-17

Description

Nov. 17, 1970 w, ALLERTON 3,540,834

APPARATUS FOR PUMPING LIQUIDS CONTAINING SOLIDS Filed Sept. 12, 1968 2 SheetsSheet 1 *2 ll 28 z \x\ I N 35 3| 32 55 I6 38 39 44 SI I "T 3 m 50 m- 4 l ROBERT W. ALLERTO N H6 2 BY Nov. 17, 1-970 w. ALLERTON 3, ,8

APPARATUS FOR PUMPING LIQUIDS CONTAINING SOLIDS Filed Sept. 12, 1968 2 Sheets-Sheet 2 ROBERT W. ALLERTON United States Patent O U.S. Cl. 415-204 12 Claims ABSTRACT OF THE DISCLOSURE A pump for handling fluid containing solids wherein the pump impeller has vanes formed on the backside thereof and therefor takes its suction from the backside of the pump casing. Solids, heavier than the fluid, are centrifuged outward in the pump casing and passed through the pump discharge without contacting the impeller vanes. The discharge from the pump impeller is directed in a whirling motion into the stream containing solids providing momentum to this stream and further preventing solids from contacting the impeller:

BACKGROUND OF THE INVENTION This invention relates generally to centrifugal pumps and more particularly to pumps handling fluids containing solids.

The problems encountered heretofore in pumping fluids containing solids are essentially as follows:

Solids become entrapped in the pump casing or between the pump casing and the impeller; and

Solids contacting the impeller and the impeller vanes cause erosion and damage to the impeller,

In a system where the fluid acts merely as a carrier for the solids, the solids may be damaged.

When solids become entrapped in the pump casing, the pumping capacity is reduced, or in some instances, may result in no flow through the pump thereby causing overheating and .eventual pump failure.

Where the solids become entrapped between the impeller and the pump casing thereby preventing the impeller from rotating, the pump capacity will drop to 0, the impeller may break off from the impeller hub, or the drive means for the pump may stall and overheat.

Constant impingement on the impeller and impeller vanes of solids such as stones, gravel, sticks, etc. and the eroding effect of the impingement will obviously cause an eventual loss in capacity, head and efliciency of the pump.

Where the fluid acts merely as a carrier for solids which have an end use after being pumped, the solids may become damaged in the pump casing by contacting the impeller or by becoming wedged between the impeller and the pump casing. The present invention overcomes the above outlined problems by providing an impeller with vanes and an impeller inlet on the backside of the impeller such that the impeller takes its suction from the rear of the pump casing away from the main stream containing solids, and discharges a stream of fluid, in a whirling motion, into the stream of liquid containing solids thereby providing momentum to impart pumping action to the stream.

Solids, heavier than the liquid are centrifuged outward and are promptly passed out through the pump discharge nozzle.

PRIOR ART Pertinent prior art patents are U.S. Pats. 3,171,357; 2,635,548; and 2,785,930.

Patent No. 3,171,357 discloses a solids handling pump wherein an annular vortex is created in front of the impeller positioned at the rear of the pumping chamber. A shroud, on the impeller, or as part of the pump casing wall, is required to direct the liquid leaving the impeller back towards the center of rotation.

Patent No. 2,635,548 discolses a solids handling pump in which an impeller, positioned in the rear wall of the pump housing substantially outside the swirl chamber, does not produce a vortex but merely imparts energy to a revolving liquid mass.

Patent 2,785,930 has a pumping chamber construction similar to Patent No. 2,635,548 but feeds liquid to be pumped through an axial bore in the impeller.

None of the above listed prior art patents discloses the unique structure of the present invention whereby an impeller is provided with impeller vanes and an impeller inlet on the back of the impeller away from the pump inlet, and whereby the discharge from the impeller is into the solids bearing stream thereby providing momentum and pumping action to this stream.

SUMMARY OF THE. INVENTION Thus, the present invention covers an eflective means for pumping liquids containing solids including a pump casing having a pumping chamber formed therein, a shaft rotatably mounted and extending through the pump casing into the pumping chamber, and-an impeller, having impeller vanes and an impellere inlet on the backside thereof, rotatably mounted on the shaft and disposed within the pumping chamber such that solids are prevented from impinging on the impeller vanes. Solids, which are heavier than the liquid, are, by centrifugal force, centrifuged outward in the pumping chamber, and are passed out through the'discharge nozzle aided by the momentum imparted to. this stream by the stream of fluid discharging from the impeller.

Accordingly, it is an object of this invention to provide means for effectively pumping liquids containing solids.

Another object of the invention is to provide a solids handling pump wherein the impeller is not contacted by the solids being pumped.

Another object of the invention is to provide a pump wherein solids cannot become entrapped in the pump casing.

Still another object of the invention is to provide a pump wherein solids cannot become entrapped between the pump casing and the impeller.

These and other objects and advantages of the invention are believed made clear by the following description thereof taken in conjunction with the accompanying drawings wherein:

IN THE DRAWINGS FIG. 1 is a sectional elevation of the present invention diseclosing the pump casing, impeller, shaft, stufliing box head, and the bearing support frame.

FIG. 2 is a section taken on line 22 of FIG. 1.

FIG. 3 is a front elevation of the impeller of the invention.

FIG. 4 is an elevation of the rear of the impeller shown in FIG. 3.

FIG. 5 is a section taken on line 55 of FIG. 3.

FIG. 6 is a projected view of the vane shown in phantom in FIG. 5.

Referring now to FIGS. 1 and 2 the pump assembly employing the novel impeller of the invention is seen comprising essentially a pump casing 10, a stufling box head 11 associated with the pump casing to prevent leakage of pumped fluid therefrom, a bearing frame 12 for supporting

bearings

13 and 14, secured to stufling box head 11, and a drive means (not shown) such as an electric motor or gasoline engine, operatively associated with a shaft 16 for driving the shaft which extends through bearing frame 12, stuffing box head 11, and pump casing into a pumping chamber 17 where it rotatably supports the impeller 18.

Pump casing 10, of the volute type and generally circular in cross-section, is designed to pass large diameter solids through a discharge nozzle 19 formed integrally thereon tangent to the casing circumference and vertically spaced from the casing horizontal center line. The suction flange 20 is secured to the pump casing 10 in any suitable manner, in this instance by a plurality of bolts 21, and has an opening 22 extending therethrough for receiving a suction pipe 23 which is operatively associated at its other end with a source of fluid containing solids to be pumped (not shown).

An opening 24 on top of pump casing 10 is threaded to receive a petcock 25 for venting the casing when required, such as for priming of the pump, and a similar opening 26 is provided at the lowest point of the casing for receiving a plug 27 to provide a means for draining the casing when required, for instance prior to storage.

Formed within pump casing 10 and bounded by suction flange 20 and the inboard end to stuffing zox head 11 is a pumping chamber 17 in which impeller 18 is rotatably supported by shaft 16 for imparting pumping action to the fluids having solids entrained therein as will be described under Operation.

Stuffing box head 11, shown as being secured to pump casing 10 by a plurality of through bolts 28, is axially displaced from the casing by means of a casing spacer 29 disposed therebetween. The axial position of the impeller 18 in pumping chamber 17 is determined by the thickness of this spacer which can be made thicker or thiner or entirely omitted depending upon the desired axial position of the impeller.

Formed as part of stuffing box head 11 is an axially extending, generally cylindrically shaped member 30 disposed about the shaft 16 and having an annular space 31 formed therein for receiving a plurality of packing rings 32 and a split seal cage 33 to prevent leakage along the shaft of fluid being pumped. A shaft sleeve 34 rotatably disposed about the shaft 16 between the shaft and the packing rings to prevent scoring of the shaft by the packing, and a packing gland 35 dimensioned to slidably engage annular space 31 to further contain the packing rings, are also provided, all as will be familiar to those skilled in this art.

Referring again briefly to bearing frame 12, the

outer races

36 and 37 of

bearings

13 and 14 are secured, as by press fit, in

annular spaces

38 and 39 thereof and

inner races

40 and 41 are disposed about shaft 16 for rotation therewith. Bearing covers 42 and 43 are provided at the respective ends of bearing frame 12 for protecting the bearings from outside contamination such as dirt, dust, and moisture, and in addition, a water shield 44 is provided outboard of bearing 14 for further protecting this hearing against any leakage of fluid that may occur past packing gland 35.

Bearing frames such as described above are well known to persons skilled in this art and therefore will need no further explanation.

Referring now to FIGS. 3-6 the unique impeller of the invention, of the single suction, fixed flow type, is shown generally at 18 comprising a hub portion 45, a generally conical shaped member 46 extending axially forward of the hub, integral therewith, and six arcuately spaced vanes 47 formed on conical shaped member 46 for imparting pumping action to the fluids in pumping chamber 17.

Hub portion 45, cylindrical in shape, has an axial bore 48 extending therethrough for mounting the impeller on shaft 16 for rotation therewith in pumping chamber 17. A keyway 49 formed in bore 48 extends the axial length thereof for receiving a key 50 to lock the impeller in rotative assembly with shaft 16 as best seen in FIG. 1.

Formed integrally with hub portion 45 and extending axially forward thereof is generally conically shaped member 46 terminating in a radial planar face 51 parallel to and remote from the rear face 52 of hub portion 45. An axially extending cylindrical bore 53 symmetrical about the impeller horizontal center line, and of larger diameter than axial bore 48 of hub portion 45 extends through conical member 46 terminating at one end at radial planer surface 51 and at the other end communicating with axial bore 48-. As clearly shown in FIG. 1 this construction allows for the assembly of impeller washer 54 and impeller nut 55 on shaft 16 after impeller 18 is mounted thereon and locked in position by key 50.

As best seen in FIG. 5, slant surface 56 of conical member 46 makes an angle of 30 with the horizontal center line of impeller 18 and slopes from the hub portion 45 towards the radial planar face 51. Planar face 51 in turn is chamfered as shown at 57 sloping rearward and making an angle of with slant surface 56.

Formed on slant surface 56 are six arcuately spaced vanes 47 for providing impelling action to fluid entering the impeller from the hub end remote from suction flange 20 of pump casing 10 Vanes 47 can be formed integrally with conical member 46 or can be welded or attached thereto by any other suitable means.

As seen in FIGS. 5 and 6 vanes 47 are of generally wing shape or air foil shape and extend substantially the entire axial length of slant surface 56 having a slightly concave surface 59 as the leading surface in the direction of rotation and a slightly convex surface 60 as the trailing surface and are so positioned on slant surface 56 as to provide a mixed flow, i.e. combined axial and radial discharge therefrom into the pumping chamber.

OPERATION In operation, after the pump has been primed, the fluid to be pumped, containing solids, enters pumping chamber 17 through opening 22 in suction flange 20 where, due to an annular vortex created by the rotating impeller, and due to their being heavier than the fluid, the solids are centrifuged outward in the pumping chamber and are promptly passed out through the discharge nozzle 19. Fluid, now relatively free of solids, is drawn into the impeller 18 at the backend or stuffing box end of the pumping chamber 17, remote from radial planar face 51 of impeller 18, and is discharged from the impeller vanes 47 into the solids carrying stream in a whirling motion in a mixed flow, i.e. combined axial and radical direction, thereby imparting momentum to the stream and thus further preventing solids from impinging on the impeller vanes.

Thus, what has been disclosed is a solids handling pump wherein the solids in a fluid stream being pumped are prevented from impinging on the impellervanes.

It will be understood that the invention is not to be limited to the specific construction or arrangement of the parts shown and that they may be modified widely Within the invention defined by the claims.

What is claimed is:

1. A centrifugal pump for pumping fluids containing solids, comprising:

(a) a casing;

(b) a generally circular pumping chamber formed in said casing and having an inlet and an outlet, said inlet being arranged to deliver fluid containing solids approximately centrally of said pumping chamber and said outlet being arranged to receive said fluid containing solids from the circumference of said pumping chamber;

(c) a shaft extending through said casing and into said pumping chamber;

(d) an impeller rotatably mounted on said shaft and disposed in said pumping chamber, said impeller comprising a body portion and vanes on said body portion, said body portion terminating in a generally planar and face spaced from and facing said inlet, and said vanes extending axially away from said inlet and the generally planar end face and inclined about the body portion whereby on the rotation of said impeller produces a fluid flow directed axially towards said inlet and radially towards the circumference of said pumping chamber to simultaneously prevent solids from striking the vanes and centrifuge the flui containing solids towards the outlet; and,

(e) means for rotating said shaft to thereby rotate said impeller.

2. A pump according to claim 1, wherein said body portion of said impeller is generally frustoconically shaped and the larger end of said generally frustoconically shaped body portion is disposed adjacent said generally planar end face.

3. A pump according to claim 2, wherein said impeller further includes a chamfered portion connecting said planar end face with said generally frustoconically shaped portion.

4. A pump according to claim 1, wherein said generally planar end face of said impeller is circular, the inlet is 'circular, the diameter of said planar end face is greater than the diameter of the inlet, and said impeller is arranged so that it is generally coaxially disposed with respect to the central axis of the inlet.

5. A pump according to claim 4, wherein the impeller is mounted on the end of the shaft.

6. A pump according to claim 5, wherein the shaft is horizontally disposed.

7. A pump according to claim 1, wherein said generally planar end face defines an area larger than the inlet opening, and the impeller is disposed so that the inlet is entire- 1y directed towards the area defined by said generally a planar end face.

l impeller is mounted on the end of said shaft.

9. An impeller for a centrigual pump, comprising a body portion which terminates in a generally planar end face forming the upstream end of said impeller, and vanes on said body portion disposed downstream from said generally planar end face, said vanes being shaped to provide fluid flow directed axially away from said generally planar end face and radially outwardly.

10. An impeller according to claim 9, wherein said body portion is tapered in the downstream direction.

11. An impeller according to claim 10, wherein said body portion is frustoconically shaped.

12. An impeller according to claim 11, further comprising a c hamfered portion connecting said planar end face to the larger end of said generally frustoconically shaped portion.

References Cited HENRY F. RADUAZO, Primary Examiner US. Cl. X.R. 4l5219; 103-115