US3079866A

US3079866A - Modified centrifugal pump

Info

Publication number: US3079866A
Application number: US827472A
Authority: US
Inventors: George D Walker
Original assignee: Texaco Inc
Current assignee: Texaco Inc
Priority date: 1959-07-16
Filing date: 1959-07-16
Publication date: 1963-03-05
Anticipated expiration: 1980-03-05

Description

March 5, 1963 e. D. WALKER 3,079,866

MODIFIED CENTRIFUGAL PUMP Filed July 16, 1959 llnited iitates harem 7 3,979,865 MGDHF IE1) SENTREFUGAL PUB/ll George D. Walker, Port Arthur, Tex, assignor to Texaco, inc, New York, N.Y., a corporation of Belaware Filed July 16, I359, Ser. No. 827,472 4 Claims. (til. 193-103) This invention relates generally to centrifugal pumps and in one specific aspect, relates to a single stage, centrifugal pump for operation with liquids containing an appreciable amount of suspended solids.

Single stage, centrifugal pumps are characterized by shrouded impellers and a reduction in the width of the volutes or spiral vanes from the juncture with the hub of the impeller to the periphery. This reduction in width or choice effect is to help impart velocity to the liquid as it is displaced radially along the impeller. It also provides an opportunity for solids, such as coke and the like, in suspension in the liquid being pumped to become lodged in' the passages defined by the vanes and the shrouds of the impeller and to cause plugging or unbalance of the rotating impeller. In either case, it is necessary to shut down the pump and to remove the accumulated solids.

Accordingly, it is an object of the present invention to provide an improved centrifugal pump for use with liquids containing a considerable amount of solids.

Another object of the invention is to provide a structure by which solids contained in the liquid being pumped may be prevented from accumulating in the rotating element.

Still another object of the invention is to provide a modification of the impeller of a centrifugal pump which can be used to reduce the size of solids carried by a pumped liquid to such small particles that they may be carried down through the pump without difficulty.

These and other objects, features and advantages of the invention will become apparent from the following description when taken in conjunction with the FIGURE which is a diagrammatic cross-section of the modified centrifugal pump.

The objects of the invention are attained by modifying the impeller structure of a pump for liquids having solid particles suspended therein so that the particles will be ground up and agitated by the impeller acting against a wear plate thereby preventing the plugging action which norm-ally occurs with a fully shrouded impeller structure.

Referring to the figure, the pump is indicated generally at 10, consisting of the inlet casing section at 11, and the bearing section or stuffing box extension 12, each formed with recesses to define a chamber for the impeller 13. Through the stufing box extension 12, there is mounted the drive shaft 14, which is supported by the shaft sleeve at 15, with the packing stutfing box at 16 and the stuffing box bushing or packing sleeve at 17, and the gasket for the shaft sleeve at 18.

The impeller 13 is fastened to the drive shaft 14 by means of the locking collar at 19, which is fastened in locking position, eg by means of the cotter pin, as disclosed herein, at 20. The impeller includes a shroud at 21 on the inlet side, annular in cross-section and having an upright cylindrical portion at 22 concentric with the axis of the impeller 13. The shroud 21 serves to reinforce and define passages between a plurality of spiral vanes or volutes 23 which are mounted between the shroud and the hub 24 and define the fiow passages of diminishing cross-section in a radial direction, the edge portions of the volutes adjacent the bearing section of the pump being free edge portions as shown at 23a.

At the outer edge of the hub and at the beginning of the free edge portions of the volu-tes, the impeller has wear ring at 25 of annular shape. On the stufing box extension and in immediate position and in contact with the free edge portions 23a of the volutes 23, and the outer cylindrical surface 25a of the wear ring '25, there is an annular wear plate 26, with a flat end surface 26a and which is held in position by appropriate fastening means, shown herein as cap screws 27 together with a plurality of welds at 28. As the liquid containing the suspended solid particles passes through the passage way defined by the volutes between the shroud 21 and the hub 24, there is a wearing action between the free edge portions 23a of the volutes in contact with the flat end surface 26a of the wear plate which will grind the particles to such a size that they will be able to proceed through the pump withotu a packing of the particles, because of the wiping action across the fiat end surface of the wear plate.

The inlet casing section 11 includes the suction eye or inlet portion at 2%, and at the edge of the pump chamber, there is positioned the casing Wear ring at 3%, fastened in position by the Welds at 31 and which extends into the chamber and is of such configuration that it is in contact at 39a with the upstream or inlet edges 23' of the volutes 23 and at 36b with the inner surface 22a of the upstanding cylindrical portion 22. This forms a seal between the low pressure incoming fluid at the inlet end of 29 and the pressurized fluid in the chamber indicated at 32..

Thus there has been shown and described, a modification of a single stage, centrifugal pump, wherein the shroud is maintained on the upstream side of the' impeller which has volutes on the downstream side in contact with a wear plate. While the modification of the pump is such as to allow for construction thereof, it is possible also to modify a conventional double shrouded impeller of a centrifugal pump by removal of the downstream shroud which leaves the hub only to support the vanes on the downstream side of the impeller.

Obviously, other modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore, only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. in combination in a centrifugal pump, a bearing section and an inlet casing section together denfining a pump chamber, an impeller housed in said chamber and comprising a hub, spiral vanes of diminishing radial cross section supported on that portion of said hub facing said inlet casing section, and a shroud fastened to the edges of said vanes facing said inlet casing section starting at the discharge edges thereof and extending inwardly radially partly a ong said vanes facing said inlet casing section thereby defining a single shroud impeller whereby said vanes on the side facing said bearing section have free edge portions, and a replaceable wear plate supported by said bearing section in sliding contact with said free edge portions of said vanes on the side of said impeller facing said bearing section, said wear plate having a cylindrical annular form, said impeller including an annular wear ring supported by the hub thereof adjacent said free edge portions of said vanes and of such dimension as to contact the annular wear plate on the inner cylindrical surface thereof.

2. In a centrifugal pump as defined in claim 1, said shroud after extending inwardly radially partly along said vanes extending upstream coaxially with said hub free of said edges of said vanes and defining a cylindrical portion extending towards the inlet of said casing section, said casing section at the inlet to said chamber having a casing wear ring in sliding contact with said cylindrical portion on the inner surface thereof thereby separating high and low pressure fluids in said pump chamber.

3. In combination, in a single stage centrifugal pump, an inlet casing section and a bearing section formed to define a pump chamber when together in assembled position, and an impeller mounted within said pump chamber, said bearing section including means for supporting said impeller within said chamber, said impeller including a hub and an annular shroud and spiral vanes having axially opposed edges and diminishing in cross section a in outward radial direction in joining relationship with said hub and said shroud and defining spiral passages therebetween, saidshroud being supported by the edges of said vanes adjacent the inlet casing section starting at the peripheral edges thereof and extending partly therealong radially inward and then upstream coaxially with said hub and" free of said vanes, the edge portions of said vanes adjacent the bearing section defining said pump chamber being free edge portions, said bearing section including a cylindrical annular wear plate, said wear plate having a flat end surface in surface to surface contact with said impeller along said free edge portions of said spiral vanes for wiping action thereagainst during impeller rotation, said annular shroud on the upstream coaxially extending portion of said impeller being a cylindrical portion in concentric relationship with the axis of its rotation, said inlet casing section having a wear member in sliding contact with the inner surface of said cylindrical portion of said annular shroud, said impeller including a wear ring mounted on said hub and in contact with the inner cylindrical surface-of said annular wear plate 4; In combination, in a single stage centrifugal pump, an inlet casing section and a bearing section having cornpleinentaryi recesses for defining a pump chamber when in: assembled relationship with each other, an impeller for housing in said chamber formed thereby, a drive shaft supported by said bearing section and mounting said impeller, said impeller including a hub, an annular shroud and spiral vanes of diminishing cross section in outward radialdimension in supporting relationship with each other and defining spiral passages ofdecreasing crosssection relationship in downstream flow, said annular shroud being spaced closer toward said inlet casing section than said spiral vanes starting from the outer radial discharge edges thereof extending inwardly radially partly along the upstream edges thereof and having an inner cylindrical portion in concentric relationship with the axis of rotation of said impeller free of the, upstream edges of a said vanes, said inlet casing section having a wear meme all) ber in contact with said cylindrical portion and forming a seal between the low pressure inlet fluid and the'high pressure fluid discharged by said impeller, said vanes having free edge portions in downstream relationship to said annular shroud, and a cylindrical annular wear plate in said bearing section in surface to surface sliding. cone tact with said free edge portions of said vanes whereby wiping action of said free edge portions of said vanes pref vents clogging by suspended materials in said passages, said impeller including a wear ring. mounted on said hub and in contactwith the inner cylindrical surface of said annular wear plate.

References Cited in the file of this patent UNITED STATES PATENTSv 538,050 Swabel Apr. 23, 1895 721,207 Lockwood Feb. 24, 1903' 772,532 Ray Oct. 18,1904 790,795 Lea et a1. May 23, 1905 914,283 Jackson Mar. 2 1909 1,099,921 Gibson June 16, 1914' 1,743,916 Hargis' Ian'.'14',. 1930 2,852,009" Tur1ay' e Sept; 16, 1958* FOREIGN PATENTS 1,616 Great Britain of 1899 15,895 Great Britain c of 1907 27,740 Great Britain .a of 1912 35,354 Norway July 17, 1922' 267,300 Great Britain e Mar. 17,4927 442,555 Italy Nov. 25, 1948 495,897 Italy Feb. 28, -1953- 730,459 Great Britain May 25, 1955'

Claims

1. IN COMBINATION IN A CENTRIFUGAL PUMP, A BEARING SECTION AND AN INLET CASING SECTION TOGETHER DEFINING A PUMP CHAMBER, AN IMPELLER HOUSED IN SAID CHAMBER AND COMPRISING A HUB, SPIRAL VANES OF DIMINISHING RADIAL CROSS SECTION SUPPORTED ON THAT PORTION OF SAID HUB FACING SAID INLET CASING SECTION, AND A SHROUD FASTENED TO THE EDGES OF SAID VANES FACING SAID INLET CASING SECTION STARTING AT THE DISCHARGE EDGES THEREOF AND EXTENDING INWARDLY RADIALLY PARTLY ALONG SAID VANES FACING SAID INLET CASING SECTION THEREBY DEFINING A SINGLE SHROUD IMPELLER WHEREBY SAID VANES ON THE SIDE FACING SAID BEARING SECTION HAVE FREE EDGE PORTIONS, AND A REPLACEABLE WEAR PLATE SUPPORTED BY SAID BEARING SECTION IN SLIDING CONTACT WITH SAID FREE EDGE PORTIONS OF SAID VANES ON THE SIDE OF SAID IMPELLER FACING SAID BEARING SECTION, SAID WEAR PLATE HAVING A CYLINDRICAL ANNULAR FORM, SAID IMPELLER INCLUDING AN ANNULAR WEAR RING SUPPORTED BY THE HUB THEREOF ADJACENT SAID FREE EDGE PORTIONS OF SAID VANES AND OF SUCH DIMENSION AS TO CONTACT THE ANNULAR WEAR PLATE ON THE INNER CYLINDRICAL SURFACE THEREOF.