US2291138A

US2291138A - Centrifugal pump

Info

Publication number: US2291138A
Application number: US249481A
Authority: US
Inventors: Blom Carl
Original assignee: BINGHAM PUMP Co Inc
Current assignee: BINGHAM PUMP Co Inc; BINGHAM PUMP COMPANY Inc
Priority date: 1939-01-05
Filing date: 1939-01-05
Publication date: 1942-07-28
Anticipated expiration: 1959-07-28

Description

-July 2s, 1942. c. BLOM 2,291,135

GENTRIFUGAL PULP 1 Y Filed YJam. 5'. 1959 2 sheets-sheet 1 Patented July 284, 1942 d CENTRIFUGAL PUMP Carl Blom, Portland, Oreg., assigner to Bingham Pumpl Company, Inc., Portland, Oreg., a corporation of Oregon appueauonsanuary 5, 1939, serm1No.249,4s1

claims. (01.103-113) This invention rentes to liquid pumps of' the centrifugal type, and has particular reference to an improved construction for relieving such pumps of air or other gases which may be entrained with the liquid during pumping operations, or for exhausting air or other gases from the intake pipe to lift liquid to the pump.

It is' an object of the invention to provide a liquid pump of the centrifugal type which will continuously and eiiiciently pump pulp and other liquids which contain entrained air or free gases. It is a further object of the invention to provide a liquid pump of the centrifugal type having means for exhausting from said pump the air and gases entrained with the liquid being pumped.V

It is a further object of the invention to provide a liquid pump of the centrifugal type which will expel air and gases from the pump whenever the air and gases entrained in the liquid being pumped are of sufficient quantity to accumulate in or adjacent the eye of the impeller.

It is a further object of the invention to provide a centrifugal pump which, when partially filled with liquid, will exhaust air and gases from the intake pipe to lift liquid to the pump.

With these and other objects in view, the invention resides in the novel construction and combination of parts hereinafter described, illustrated in'the accompanying drawings, and set forth in the appended claims; itbeing understood that various changes in form, proportion, size and details of construction within the scope of the claims may be resorted to without departing from the spirit or sacrificing any of the advantages of the invention.

In the drawings:

Figure 1 is a side elevation, partly in section, of a vertically positioned pump embodying the presi ent invention.

Figure 2 is a horizontal section taken on the line 2-2 of Figure 1 and illustrating the sectors of the pump casing and their relation to the other parts of the pump.

- Figure 3 illustrates a modified construction of the pump casing illustrated inFigure 2.

Figure 4 is a side elevation, partly in section, of a horizontally positioned pump which is a modification of the pump shown in Figure 1.

Figure 5 is a fragmentary side elevation of the Dump shown in Figure 1, excepting that the construction illustrated does not embody an air vent or air vent port shields.

Figure 6 is a horizontal section taken on the line 6-6 ofFigure 5.

of the casing shown in Figure 3 as the same would appear if taken on the line 6--6 of Figure 5.

' Referring to the drawings, an embodiment of v the improved pump may be either as illustrated in Figure l or in Figure 4. Figure l illustrates a vertical type pump, while Figure 4 illustrates a horizontal type pump. The structural differences between the pumps illustrated in the two figures are only as affect-the operability vof the pump in the respective positions. The principle of the invention is the same in both types.

The pump illustrated in Figure 1 comprises a vertical shaft I which is Journalled in a lower bearing 2 and an upper bearing 3. The lower bearing 2 is housed in a bearing housing 4 which is supported upon a bracket or pedestal 5. Power to drive the shaft l is supplied by a motor 6 disposed 'above and in vertical alignment therewith, the pump shaft and motor being connected by a coupling l.

An impeller 8 is affixed to the shaft I as by a key 9 so as to rotate therewith, and is held in axial position by a shaft sleeve I0 and impeller nut Il threaded on the shaft. The impeller 8 is housed in a pump casing comprising side plates whence it passes through the eye of the impeller` and through passages defined by the impeller vanes i6 and intothe area defined by the volute '|4. The liquid is discharged from the pump .volute through the discharge port Il.

It is well known that pulp and other liquids have air and free gases contained therein, and that when acted upon by a centrifugal pump impellerthe air and gases entrained with the liquid often accumulates within the pump near the center of the rotating body of liquid in quantities sufiicient to interfere materially with the flow of liquid therethrough. In a centrifugal pump of ordinary construction, air and gases which accumulate in the impeller passages during operation of the pump are not acted upon by the ow of liquid through the volute casing. In such a Ipump the area of the volute casing-increases in the direction of iiow and, under normal operating conditions, the liquid' velocity and pressure are approximately constant throughout the area of the volute; there being a continuous outow of liquid through the impeller passages excepting at such times as air and gases accumulate therein in Figure 7 illustrates the modified construction 55 suilicient quantities to interfere with the normal operation of the pump. To overcome this difficulty, applicant has provided a centrifugal pump having an air vent port I9 positioned in or adjacent the eye of the impeller, and a pump casing having its inside periphery divided into sectors, lthe arrangement of said sectors causing a reversal of flow of liquid contained in the passages between adjacent impeller vanes at a point adjacent the air vent forcibly discharging accumulated air and gases from the pump through said port.

Referring to Figures 2 and 3 of the drawings, the casing of a pump embodying the invention is disclosed as having three sectors, which are defined as being from A to B, from B to C, and from C to D. The sector C to D of the pump casing functions normally as in a conventional centrifugal pump, in which there is a continuous outflow of liquid through the impeller passages into the volute casing. Consequently, air and gases which accumulate in the impeller passages during that part of the rotative cycle where they are in registry with the sector C to D of applicants pump are not acted upon by the ow of liquid through the volute casing. y

Referring to Figure'2, the sector of the pump casing defined as from A to B the area ofthe pressure chamber or volute is progressively decreased by the convergence of the casing wall with respect to the periphery of the impeller 8. As the liquid follows the impeller, a portion of the liquid in the pump casing is forced to reenter the impeller passages on account of the convergence of the casing wall, causing a momentary reversal of ilow in the impeller passages while they are in that part of the cycle of rotation adjacent the sector A to B. An air vent port Il is positioned to register with the inner ends of the impeller passages at the moment oi' maximum compression of the accumulated air and gases caused by the reversal of ow of liquid therewithin, and to provide egress from the pump for such accumulated air and gases, there is provided an air vent pipe I8. It will be noted that the air vent pipe I8 is equipped with

shield portions

20 and 2| extending laterally from each side thereof, the pipe I8 and

shield portions

20 and 2| serving to close of! the ,inner ends of the impeller passages during rotation of the impeller through the sectors A to B and B to C from the impeller eye. Section 20 of the shield extends from the air vent port in a direction opposed to the rotation of the impeller, and `section 2| of the shield extends from the air vent port in the direction of rotation of the impeller. The width of the section 2l of the shield may be modified according to conditions under which t'ne pump is required to operate. It will be noted that the air vent pipe Il and shield 2li-2l form a continuous closure for the inner ends of the impeller passages during rotation. thereof through the sectors A to B and B to C, which closure serves to cut o1! the outflow of liquid from the impeller :ge through the impeller passages in these sec- As the flow of liquid is reversed in the impeller passages in the sector A to B, the air and gases therewithin are trapped in the impeller passages by the section 20 of the shield, and prevented from escaping back into the eye of the impeller. As rotation of the impeller brings` the respective inner ends of the passages into registry with the air vent port Il, the air and gases are permitted to escape therefrom through the air vent Il and through the air vent pipe 22, the latter terminating within the area of the suction li as illustrated in Figure 1, or at a point remote from the pump, as may be desired.

The sector defined as from B t0 C is that p0rltion of the'inside periphery of the pump casing are out of registry with the air vent port, to prevent air being drawn into the passages through the air vent port when the liquid in the passages again begins its normal outward flow.

Referring now to Figure 3, there is illustrated a modiiled construction of the pump casing, the construction differing from that illustrated in Figure 2 only in the contour of the peripheral wall of the casing. In the modified construction the point A of the wall which forms the inward end of the liquid discharge port I1 is extended and curved inwardly toward the impeller 8. 'Ihis construction forms a lobe 22 in the pump casing, and during rotation of the impeller the liquid is momentarily drawn outwardly from the impeller passages before being forced into the passages by the convergence of the casing wall and the impeller, as hereinabove described.

The outward movement of the liquid from the impeller passages, under the influence of the divergence of the casing wall from the impeller, causes a displacing effect at the inner end of the impeller passages which positively draws air into the passages from the eye of the impeller. Thus any air which has accumulated in the eye of the -impeller is positively'drawn into the passages prior to the compressing and discharging action of the liquid under iniluence of the converging wall of the pump casing. The inner ends of the impeller passages are closed by the air vent shield 20 as the liquid is forced into the passages by the convergence of the casing wall, whereupon the air is first compressed and then exhausted from the pump through the air vent port I9 in the same manner as hereinbefore described.

In Figures 5, 6 and 'I is illustrated a pump and a modification thereof similar to the construction illustrated in Figures 1, 2 and 3,-excepting that the pump does not embody an air vent pipe or air vent port shields. Under certain operating conditions the presence of the air vent and air vent port lshields is necessary. 'I'hese elements form a valve which is first closed to c'ause the air and gases to be compressed, then opened to premit the air and gases to escape, and thereupon closed to prevent air being drawn into the pump therethrough. The pump illustrated in Figures 1 and 5 is a vertical pump of the type devised for handling pulp and foamy liquids. In such pumps the liquid enters the suction chamber I5 A the valve structure is unnecessary. Under such ing gland 28.

impeller into the atmosphere in the upper portion of the suction chamber.

The pump illustrated in Figure 4 comprises a motor 23 having a shaft 24 which drives an impeller 25. The shaftis journalled in a bearing 26 which includes the usual packing 21 and pack- The impeller is secured to the shaft by means of a machine screw 29 and key 3B. The pump casing is formed by a volute 3i and a suction plate 32, the latteralso defining the walls of the intake port 33. The pump casing embodies sectors A to B, B to C, and C to D, as shown in Figure 2, and is equipped with an air vent port 34 and air vent port shield 35 as hereinbefore described in connection with the pump illustrated in Figure 1. The operation of the pump is identical with the operation of the pump shown in Figure 1; and the functions of. the respective sectors .of the pump casing and their relation to the impeller passages, air vent and air vent shield are also as hereinbefore described. The horizontal type 4pump may also be designed for operation under low suction head, and whenever thiscondition prevails the pump may be constructed and successfully operated without the use of an air vent port or air vent port shield.

This application is a continuation in part of my application Serial No. 117,165, filed December 22, 1936, for Centrifugal pump. f A

Having now described my invention and in' what manner the same may be used, what I claim as new and desire to protect by Letters Patent is:

1. A centrifugal pump designed to exhaust the air and gases entrained with the liquid being pumped, comprising a casing having a discharge opening, an impeller rotatively mounted within said casing, said impeller having passages defined by a plurality of vanes extending outwardly from the eye ofthe impeller, said casing closely approaching said impeller at a point adjacent one side of said discharge opening, said casing in a sector beyond said'point first diverging from said impeller to draw air and gases from the eye of the impeller into said impeller passages and then converging on said impeller for momentarily reversing the flow of liquid inthe impeller passages to exhaust entrained air and gases,r then, beyond said sector, again diverging from said impeller in a volute Aextending to the other side of said discharge opening, a shield for closing the inner ends of said impeller passages during their travel past a portion of said sector for entrapping air and gases in said impeller passages. and an air vent port adjacent the convergent portion of the casing and communicating with the inner ends of the impeller passages for venting said impeller passages during said period of momentary reversal of i'low of liquid therein. l

2.l A centrifugal pump of the type comprising a generally volute casing. an impeller rotatively mounted within said casing, an inlet for said pump communicating with the leye of the impeller, said impeller having passages defined by a plurality of vanes extending outwardly from theliquid from said impeller passages and then to forceL liquid into the impeller passages from the pump lcasing, and an air vent port adjacent the convergent portion of the casing and communieating with the inner ends of the impeller passages for venting the impeller 'passages at the time liquid is caused to enter said passages from the casing, said casing beyond said convergence continuing in a diverging volute extending around to the opposite side of said discharge port.

3. A centrifugal pump of the type comprising a generally volute casing, a discharge port in said casing, an impeller rotatively mounted within said casing, saidimpeller having vpassages dened by a plurality of vanes extending outwardly from the eye of the impeller, means for exhausts ing from said pump the air and gases entrained with the liquid being pumped, said means com- 1 prising a sector of said casing adjacent one side of the`inner end of the discharge port which first diverges from the impeller to positivelydraw air and gases from the eye of the impeller into said impeller passages and then converges with respect to the periphery of the impeller formomentarily reversing the flow of liquid in the ixnpeller passages during rotation of the impeller through vsaid sector for ejecting air and gases from said passages, and an air vent port adjacent the convergent portion of the casing and communicating with the inner ends of the impeller passages to receive air exhausted from 'said passages, during said momentary reversal of iiow of liquid in said passages.

4. A centrifugal pump of the type comprising a generally volute casing, a discharge port in said casing, an impeller rotatively mountedwithin saidfcasing, said impeller having passages dened by a plurality of vanes extending outwardly from the eye of the impeller, means for exhausteye of the impeller, a discharge port for said cassector, said sector operating nrstto withdraw ing from said pump the air and gases entrained with the liquid being pumped, said means comprising a sector of said casing adjacent one side 4 of the inner end of the discharge port which first diverges from the impeller to positively draw air and gases from the eye of the impeller into said impeller passages and then converges with respect to the periphery of the impeller' for momentarily reversing the ow of liquid in the impeller, passages during rotation of the impeller through said sector for ejecting air and'gases.

from said passages.

5. A centrifugal pump of the type comprising a' generally volute casing, an impeller rotatively mounted within saidcaSing, said impeller having passages defined by a plurality .of vanes extending outwardly from the eye of the impeller, an

inlet chamber for receiving material to be pumped and for introducing said material into the eye of the impeller under gravity head, means for exhausting from said pumpthe air and gases entrained with the liquid being pumped, said means consisting of a sector of said casing which converges with respect to the periphery of the impeller for momentarily reversing the now of liquidin the impeller passages'during rotation of the impeller through said sector for ejecting air and gases from said passages, the inner ends' of substantially all of said impeller passages being open for the intake of liquid to be pumped. the ejected air and gases being caused to escape to the atmosphere above the surface of the inowing liquid approaching the eye of the impeller.

CARL BLOM.