US3103177A - Self-priming centrifugal pump - Google Patents

Description

s@PL i0 1963 J. L. GATTO ETAL v3,103,177

SELF-PRIMING CENTRIFUGAL PUMP 2 Sheets-Sheet 1 Filed July 20, 1961 @www @wm/fk @c Sept. 10, 1963 1,L, GATTO ETAL 3,103,177

SELF-PRIMING CENTRIFUGAL PUMP vFiled July 2o. 1961 2 Sheets-Sheet 2 d, l 03,1 7 7 Patented Sept. l0, 1963 3,ltl3,li7 SELF-PRIMING CENTRFUGAL PUMP Joseph L. Gatto, Wyckoff, and Robert Wyckoff, @alrland, NJ., assignors to Bell d: Gossett Company, a corporation of illinois Filed July 20, wol, Ser. No.. 125,436 6 Claims. (Cl. lofi-M3) This invention relates to self-printing centrifugal pumps and more particularly is concerned with diffuser type self-priming centrifugal pumps.

Dilfuser prime pumps such as are shown in Stratton Patent No. 2,281,175 and Marlow Patent No. 2,653,546 are well known and have served Well over the years but at lthe present time numerous applications exist which require faster priming cycles that are not possible with existing pumps. For example, in the petroleum industry present day methods of handling petroleum require pumps having as rapid a priming time as possible. Similar ytrends exist in various .sizes of contractors pumps.

The principal object of the invention is the provision olf a self-priming centritu gal pump that has a faster prin ing cycle and that eliminates recirculatory losses.

Another object of the invention is the provision of an improved diiluser prime centrifuga-l pump that eliminates recirculatory losses and Ithat achieves a faster priming cycle both on static liit and against a positive discharge head.

Still another object `of the invention is the provision of an improved self-priming centrifugal pump that eliminates prime holes and the accompanying problems of coring, machining `and critical positioning `of these holes.

A further object is the provision 'of an improved selfpriming pump that creates increased priming turbulence at the impeller periphery and yet retains a relatively non-turbulent liow during pumping.

Briey the invention contemplates the elimination of inner end portions tot one or more discharge flow passage forming vanes adjacent the lower region of the impeller periphery to permit more direct entrance to the mpeller periphery of only air-free liquid flowing reversely under the optimum pressure differential conditions existing at this location, to permit more ecient air-liquid mixing under the optimum turbulence conditions existing at the lower region of the impeller periphery, and finally to permit peel-ing and discharge of the entrained air into upwardly extending discharge tiow passages in which case the momentum induced by the impeller rotation is reinforced by the inherent buoyancy of 'the air to achieve more rapid and efficient air separation and discharge.

A corollary of this is that long reverse iiow paths may be maintained around the upper region of the impeller periphery and this better maintains the hydraulic seal between the air collecting in the pump ,tank during priming yand :the air at low pressure within the impeller and suction line and thus minimizes the likelihood of creating a vortex of -air through the upper vane passages.

Where the invention is applied to pumps equipped with peeling vancs having a low vane angle, it is usually only necessary .to eliminate the vane portion that is in 'close clearance with the impeller periphery, however, for pumps equipped with peeling vfanes having a high vane angle, the elimination of the inner end of the vane leaves the resultrant vane edge substantially removed from the impeller periphery and this clearance offers an additional advantage in that it accommodates more eicient mixing or air and liquid.

In most pump arrangements lto which the invention has been applied, the amount of vane eliminated is sutlicient to create a direct reverse radial ow path fior the return of air-free liquid though .in some instances some vane overlap can be tolerated. ln both instances, however, the path created for return liquid llow by elimination of the inner end of one or more of the lower vanes is substantially shorter than heretofore. ln general, reverse ow paths range 'from 30 to 50% less than the unshortened paths for the particular pump arrangements that have been devised ito date.

Not only is the location or the eliminated vane portion important but the 'amount ci vane removed varies not only with total vane length and number but also with impeller diameter, impeller radial clearance, impeller speed .and vane height and angle. A delinite Itrend indicates that the amount of vane or vanes cut back increases with increasing flow passage inlet area and with increasing total number of vanes.

On the particular pump arrangements for which dat-a is presently available the amount yof vane cut back, expressed as a percentage of the composite length of the total number of vanes, has ranged fnom 2.8% to 10.7%. The improvement in priming time has been on the order of 35% and in .one situation involving a 20 foot suction lift, the improvement has .been as much as 63%.

It has also been determined that additional important priming advantages can be obtained by matching the pump yarrangement land vane removal configuration to the particular pumping application. Thus, a pump arrangement capable of providing very rapid priming on a l0 foot suction lift may roller no advantage on a v2O foot suction lift.

Other objects and advantages will become :apparent during the course of the 'following description.

ln the accompanying drawings forming a part of this `specilication and in which like numerals are employed to designate like parts throughout the same:

FIG. l is a vertical sectional view along .a center line of a pump having a seven vane diluser;

FIG. 2 is la vertical sectional View taken vsubstantially along the line 2-2 of FIG. l to illustrate the diffuser vane arrangement;

FIG. 3 is a vertical sectional View `corresponding to that of FIG. 2 and illustrating the invention applied to a diffuser prime pump having four diffuser varies;

FIG. 3A is an enlarged detailed sectional view better illustrating the nature of the vane modication of the pump of FIG. 3;

FIG. 4 is .a Vertical sectional view lalso corresponding to that of FIG. 2 and illustrating the invention applied to a diffuser prime pump having live diffuser vanes of low vane angle; and

iFlG. 4A is an enlarged fragmentary View better il-lustrating the particular type of vane modification shown in the pump of FIG. 4.

Referring now to the drawings, one particular construction or a diffuser type self-priming centrifugal pump, as illustrated in FIGS. l and 2 for purposes of disclosure, includes a divided casing l0 having a discharge outlet ll and a suction inlet passage 12 terminating at a suction inlet 13. The pump casing lll comprises a generally hollow main section lo, both sides of which are-open, and the top of which is provided with the discharge outlet 11, a cover plate section 18 forming the suction side of the pump and secured across one of the open sides of the main section lo, and a recessed closure ilange 19 secured across the other open side of the `main casing section 16 Iand sandwiched between a bearing flange 2Q and the [main section 16 to seal the pump. The casing provides an internal chamber 2l for holding a lreserve of liquid.

A ycentrifugal impeller 22, which is here shown as including a plurality of blades 23, is rotatably mounted in the pump casing chamber vfor rotation in a counterclockwise ydirection as viewed in FIG. 2 and is formed at its taxis with a suction eye 24 that communicates .directly il with the suction passage l2. A drive shaft for the impeller projects through a seal well 26 provided by the closure flange 19 and a rotatable seal ring assembly 27 encircles the drive shaft and seals against the closure flange 19.

In the preferred form of the invention illustrated herein for purposes of disclosure a one piece diffuser disc, designated generally as 30 is located and held between oppositely facing annular shoulders and 29, respectively, formed on the cover plate l and closure flange 19. The diffuser disc 3f) is shown as including a tubular inlet stub 30S forming an extension of the inner end of the suction passage l2. The diffuser disc illustrated in FIG. 2 `is equipped with a set of seven vanes, designated 31 through 37, each vane being shown spiraling forwardly and outwardly from adjacent the impeller periphery and in the direction of impeller rotation.

In the preferred arrangement illustrated herein, the ydiffuser vanes are equally spaced, the vane angles are equal and the vane trailing edges terminate at the same outer diameter. These features provide equally diverging discharge flow passages resulting in equal conversion from velocity head to pressure head in all passages and balanced radial pressure during pumping. While this uniformity is preferred, the invention is not limited to such a restricted configuration.

.While some or all of the walls of the diffuser disc 30, as well as other parts of the multiple piece casing illustrated, could `be cast integral, the separate arrangement of the present disclosure permits easy repair or replacement and also simplifies the coring problems involved in casting the various parts.

The principal purpose of the invention is to provide a pump construction capable of rapid priming and free of recirculatory losses. For this purpose, vanes 3l and 32 `are substantially shorter than the remaining vanes in that they terminate well short of the impeller periphery to provide relatively short and direct reverse radial ow paths as indicated by the arrows SEA and 32A in FIG. 2. In the illustrated arrangement, the reverse flow paths 31A and 32A are approximately 50% shorter than the unshortened paths. It is the location and the extent of vane removal of these so-called lcut-back vanes 3l and 32 that determines the speed and eiliciency of priming. It may be observed that the vanes 3l and 32 are located in successive arrangements and have inner edges originating adjacent and alongside the lower downward sweep of the impeller periphery. For convenience of reference it may be explained that vanes 33 and 34?- have inner edges located along the upward sweep of the impeller periphery and vanes 35, 36 and 37 have inner edges adjacent and by the arrows 31A and 32A are located towards the bottom of the chamber 2l for the reserve of liquid and, therefore, substantially a head of liquid acts to establish a near maximum pressure differential at these locations for encouraging a reverse radial flow of air free liquid from the chamber 21 to the impeller periphery. 'Ihis greater pressure differential contributes to the creation of optimum Vturbulence conditions at this 1ocation and this encourages more efficient air and liquid mixing, a requirement for fast priming. Finally, the fact that air `free liquid returns along the paths of the arrows 31A and 32A results in this liquid being carried along a substantial portion of the impeller periphery and becoming mixed with air during such movement with the resultant entrained bubbles then being peeled off, principally at the inner edges of vanes 33 and 34. The vanes 33 and 34 border upwardly extending discharge flow passages in which case the momentum induced by the impeller rotation is reinforced by the buoyancy of the air bubbles beting peeled ofi` to create a rapid and efficient air Iseparation and discharge.

It may also be observed that the reverse liquid ilow passages that exist between the vanes 35, 3d and 37, located across the top sweep of the impeller periphery, are all of substantially greater length and are all associated with inner vane edges that are substantially close to the impeller periphery so that the arrangement maintains a hydraulic seal between the high pressure air within the pump chamber 21 and the low pressure air within the impeller. The ability to maintain this hydraulic seal eliminates the likelihood of creating a vortex of air through the upper diffuser vane passages.

In the particular arrangement of FIGS. l and 2 wherein the diffuser is equipped with seven vanes, the total vane length that is eliminated, expressed as a percentage of the composite length of all of vanes 36 to 36 is about 10.7 percent. Because of this rather substantial figure and because of Vthe relatively'high vane angle, the inner edges of vanes 3l and 52 are substantially removed from the impeller periphery and the resultant clearance accommodates more efiicient mixing of air and liquid.

During the priming cycle, a considerable differential in pressure exists between the liquid reserve in the pump casing chamber and the diffuser vane passages as cornpared with the suction eye of the impeller. This differential pressure causes the reserve of liquid to press against the blade tips of the rotating irnpeller and create an airliquid mixture. Where the vanes along the lower downward sweep of the impeller periphery are foreshortened at their inner ends, substantially shorter reverse flow passages result and liquid is encouraged to return to the impeller periphery by reason of the greater pressure differential at this location. The greater the pressure differential, the more turbulence and the more air entrained in the liquid to be subsequently peeled off by the close tted vanes 33 and 34. This action continues with air free liquid moving along the reverse flow paths 31A and 32A and mechanically mixing with air within the impeller to form a foamy mixture `of air and liquid from which air bubbles are peeled off and discharged yuntil all of the air is exhausted from the suction line and the pump is fully primed.

Not only is this pump arrangement capable of providing faster priming but it also retains a relatively nonturbulent discharge flow during normal pumping and, in general, is more efficient in normal pumping operation since it eliminates recirculatory losses.

In the case of the particular diffuser configuration illustrated in FIG. 2, it should be understood that, while somewhat less efficient, the vane 33 might have a portion of its inner end eliminated since it is rather closely adjacent the bottom of the impeller periphery such that it may be considered as being adjacent the lower downward sweep of the impeller. As the description proceeds in connection with FIGURES 3 and 4, it should become apparent that reasonable variations from the illustrated configurations are possible and are contemplated within the scope of this invention. In the care of vane 33, of

FIG. 2, a vane at this location could more effectively be partially eliminated at its inner edge, if it were on a diffuser disc having substantially more than seven vanes.

In FIG. 3 .there is illustrated a pump equipped with a four vane diffuser du having vanes numbered 41 to d4. Here again the diffuser vanes preferably are equally spaced, have equal vane angles and have vane trailing edges terminating at the same diameter. It will be apparent that vane 4l, which is located adjacent and alongside the lower downward sweep of the impeller periphery has its inner end terminated substantially short of the inner ends of the remaining vanes such that no overlap exists between the inner end of vane il and `the outer end of the adjacent preceding vane ad. Thus, there is provided a direct short reverse radial flow path 4lA for the return of air free liquid from the casing chamber to the impeller periphery. In the illustrated arrangement, the reverse flow path dll-X is approximately 30% shorter than the unshortened paths.

Once :again the location where the vane is eliminated isadjacent the bottom of the tank and is subjected to the greater head pressures existing at that point and once again the air `bubbles that become entrained with the liquids returning along the path of the arrow 41A are peeled o'i at a vane 42 such that they are readily discharged through an upwardly extending discharge flow passage. Since the vanes 41 to -44 are arranged at a low vane angle, 'the resultant inner edge of vane 41 is rather close to the limpeller periphery and this illustrates that `inthe present invention it is not an absolute requirement `that the resultant vane edge be located substantially outwardly from this periphery as this is principally a function o'f the vane angle.

FIG. 3 is an enlarged view of the region from which the inner edge of vane 41 is eliminated, and phantom lines fi-1lD illustrate the approximate amont of lvane that `is omitted;

Finally, there is illustrated in FIG. 4 another `pump equipped with a five vane diffuser 5t) having vanes numbered S1 to 55 wherein the vanes are equally spaced and are arranged at equal angles and have their trailing edges terminating at the same diameter. Once again the lower vane 51 has a portion of its inner end omitted as it is the vane which has its inner end originating along the lower downward sweep of the impeller periphery. FIG. 4A is an enlarged view better illustrating in phantom lines at SIP the approximate amount of vane that is omitted. It may be observed that some amount of vane overlap is tolerated in the arrangement of FIG. 4 such .that the reverse liquid flow path indicated by arrow 51A is only approximately radial. One explanation for this difference between the arrangements of FIGS. 3 and 4 is that in FIG. 4 the impeller diameter is somewhat less than in FIG. 3 and, therefore, somewhat less vane removal is required for achieving the required improvements in priming efficiency. In any case it will be apparent that a sufiicient amount of vane is omitted in lFIG. 4 to shorten substantially the reverse iiow path and also to make it approximately radial. In the illustrated arrangement of FIG. 4 the reverse iiow path 51A is approximately 45% less than the unshortened paths.

It may also be noted that the slight amount of vane overlap illustrated in FIG. 4 can usually only be tolerated in pumps equipped with ditusers having a small number of vanes. For difusers with large numbers of vanes, no vane overlap can ordinarily be tolerated and usually it is preferred that two or more successive vanes have portions eliminated at their inner ends.

It should be understood that the description of the preferred form of .the invention is for the purpose of complying with Section 112, Title 35, of the U.S. Code and that the claims should be construed as broadly as prior art will permit.

What is claimed is:

l. In a self-priming pump of the type having a rotary impeller, means -for supporting said impeller for rotating about a substantially horizontal axis, wall structure defining a chamber for a reserve of liquid in which said impeller is rotatable and defining a suction inlet communicating centrally with said impeller and -a discharge outlet leading trom said chamber, and a plurality of vanes spaced about the periphery of said impeller, beginning at a point in close proximity vwith said impeller periphery and spiraling forwardly and outwardly therefrom to a point providing substantial peripheral overlap of the beginning point of the succeeding vane, the improvement wherein ionly each said vane that has its Ibeginning point originating adjacent to the lower downward sweep of said impeller periphery hassaid beginn-ing point located peripherally forward in relation to the proceding vane to provide therebetween substantially radial passages `from said main ychamber -to said impeller periphery thereby providing short direct reverse flow paths for a substantial quantity of liquid contained in said main 6 chamber to reach said impeller periphery thereby provid* ing optimum conditions for rapid priming of said pump.

2. A self-priming pump capable of producing a priming cycle and a pumping cycle, comprising a ycasing for holdin-g reserve liquid, said casing having a suction inlet, discha-rge outlet, a rotary impeller capable of producing an air-liquid mixture at its periphery, a stationary difiuser, said diffuser having `more than two vanes, liquid passages between said vanes communicating to and from said impeller periphery and said reserve liquid in said oasing, said vanes spaced 360i" about said impeller, each beginning at a point in close proximity to said impeller periphery spirali-ng `forwardly and outwardly therefrom to a point providing substantial peripheral overlap with the beginning point of the succeeding vanes; with each of said vanes that has its beginning point originating adjacent the lower downward and bottom sweep of said impeller periphery, having said -beginning point widely spaced in relation to the preceding vane thereby opening a substantially radial low resistance passage to said impeller periphery from the deepest portion of said reserve liquid to return a susbtantial quanti-ty of air-free reserve liquid for remixing with air at said impeller periphery; other said vanes having their beginning point originating across the upward and top sweep of said impeller periphery defining normal resistance passages concurrently discharging the air liquid mix-ture out off at said va-ne beginning point while returning a limited quantity of said reserve liquid to said impeller periphery to accomplish said priming cycle; all of said passages cooperating to discharge liquid into said reserve liquid in said casing during said pumping cycle.

3. In a selfpriming centrifugal pump, a rota-ry impeller, means for supporting said impeller for rotation about a substantially horizontal axis, wall struct-ure deiining a main chamber for a reserve of liquid in which said impeller is rotatable and defining a suction inlet cornmunicating centrally with said impeller and a discharge outlet lead-ing from said chamber, and a plurality of vanes spaced in distributed rela-tion about the entire periphery of said impeller and spiraling forwardly and outwardly therefrom to deiine a plurality of discharge flow passages spaced about the periphery of said impeller and comniunicating between said main chamber and the periphery o-f said impeller, the improvement wherein each vane of said plurality of vanes has an inner edge originating adjacent the impeller periphery, Iwith each vane of said plurality of vanes that has its inner edge originating adjacent the upward and top sweeps of the imp eller periphery having a substantial inner end portion `disposed in pe- -ripherally overlapping relation -with an outer end portion of the immediately preceding one of said plurality of vanes to provide therebetween a reverse how path leading generally spirally vfrom said main. chamber to said impeller periphery and with at least one of said plurality of vanes having its inner edge originating adjacent the lower downward sweep of the impeller periphery and having a substantial inner end portion disposed in peripherally offset relation with an outer end portion of the immediately preceding vane to provide therebetween ya substantially direct reverse radial flow path leading from said main chamber to said impeller perphery.

4. In a pump arrangement in accordance with claim 3 and -wherein a diffuser disc is iixed in said Wall structure and integrally mounts said plurality of vanes.

5. In a pump arrangement in according with cla-im 3 wherein each of two successive vanes having inner edges originating adjacent the lower downward sweep of the impeller periphery has a substantial inner end portion disposed in peripherally offset relation with an outer end portion of the immediately preceding vane.

6. In a self-priming centrifugal pump, a rotary impeller, means for supporting said impeller Ifor rotation about a substantially horizontal axis, wall structure defining a main chamber ifor a reverse of liquid in which said impeller is 7 rotatalble and delinin-g a suction inlet communicating centrally with said irnpeller and a discharge outlet leading from said chamber, and a plurality of varies spaced in distributed relation about the entire periphery of said impeller and spiraling forwardly and outwandly therefrom to define a plurality of discharge ow passages spaced about the periphery of said impeller and communicating between said-main oharnber and the periphery of said impeller, the improvement wherein each vane of said plurality of vanes has an inner edge originating adjacent the .impeller periphery, with each vane of said plurality ofvanes that has its inner edge originating adjacent the upward and top sweeps of the impeller periphery having a substantial linner end portion disposed )closely adjacent the impeller periphery and in peripherally overlapping relation with ari outer end portion of the .immediately preceding one of said plurality of varies to provide therebetween a reverse Iilow path leading generally spirally from said main chamfber to said inipeller periphery and with at least one of said plurality of v-anes having its inner edge originating adjacent Ithe lower Cil downward sweep of the impeller periphery and having a substantial inner end portion disposed in spaced relation to the impeller periphery and in peripherally offset relation with an outer end portion of the immediately preceding vane to provide therebetween a substantially direct reverse radial flow path lead-ing -from said main chamber to said .impeller periphery.

References Cited in the file of this patent UNTED STATES PATENTS 2,332,875 Stratton Oct. 26,- 1943 2,653,546 Marlow Sept. 29, 1953 2,945,448 Frederick July 19, 1960 2,951,449 Van Blarcorn et al Sept. 6, 1960 FORETGN PATENTS 302,588 Germany Apr. 26, 1924 440,679 Genmany Feb. 11, 1927 469,806 Italy -Ma-r. 17. 1952

Claims (1)

1. IN A SELF-PRIMING PUMP OF THE TYPE HAVING A ROTARY IMPELLER, MEANS FOR SUPPORTING SAID IMPELLER FOR ROTATING ABOUT A SUBSTANTIALLY HORIZONTAL AXIS, WALL STRUCTURE DEFINING A MAIN CHAMBER FOR A RESERVE OF LIQUID IN WHICH SAID IMPELLER IS ROTATABLE AND DEFINING A SUCTION INLET COMMUNICATING CENTRALLY WITH SAID IMPELLER AND A DISCHARGE OUTLET LEADING FROM SAID CHAMBER, AND A PLURALITY OF VANES SPACED ABOUT THE PERIPHERY OF SAID IMPELLER, BEGINNING AT A POINT IN CLOSE PROXIMITY WITH SAID IMPELLER PERIPHERY AND SPIRALING FORWARDLY AND OUTWARDLY THEREFROM TO A POINT PROVIDING SUBSTANTIAL PERIPHERAL OVERLAP OF THE BEGINNING POINT OF THE SUCCEEDING VANE, THE IMPROVEMENT WHEREIN ONLY EACH SAID VANE THAT HAS ITS BEGINNING POINT ORIGINATING ADJACENT TO THE LOWER DOWNWARD SWEEP OF SAID IMPELLER PERIPHERY HAS SAID BEGINNING POINT LOCATED PERIPHERALLY FORWARD IN RELATION TO THE PROCEEDING VANE TO PROVIDE THEREBETWEEN SUBSTANTIALLY RADIAL PASSAGES FROM SAID MAIN CHAMBER TO SAID IMPELLER PERIPHERY THEREBY PROVIDING SHORT DIRECT REVERSE FLOW PATHS FOR A SUBSTANTIAL QUANTITY OF LIQUID CONTAINED IN SAID MAIN CHAMBER TO REACH SAID IMPELLER PERIPHERY THEREBY PROVIDING OPTIMUM CONDITIONS FOR RAPID PRIMING OF SAID PUMP.

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