US2791968A - Self-priming centrifugal pump - Google Patents

Description

May 14, 1957 w. E. RUPP 2,791,968

SELF-PRIMING CENTRIFUGAL. PUMP Filed Sept. 8, 1953 INVENTOR. WARREN E. PUFF A TTOENEYS United States Patent C l SELF-PRIIVIING CENTREFUGAL PUMfP Warren E. Rupp, Mansfield, Ohio, assignor to The Gorrnan-Rupp Company, Mansfield, Ghio, a corporation of Ohio Application September 8, 1953, Serial No. 378,959

6 Claims. (Cl. 103-113) This invention relates generally to the art of centrifugal pumps and is particularly concerned with self-priming centrifugal pumps having a new mode of operation and the new result of much more rapid priming action than is possessed by conventional self-priming centrifugal pumps.

In all self-priming centrifugal pumps with which I am familiar, priming is accomplished by mixing liquid and gas in the impeller chamber and discharging that mixture, thus gradually exhausting the gas from the impeller chamber and the line leading thereinto and filling them with liquid. During such priming action the impeller delivers a stream of such mixture containing much less liquid than is present after priming has been completed, and hence during the priming action the liquid delivered by the pump is less than after priming has been completed. Thus the centrifugal pump is quite efficient while pumping but is relatively inefficient for pumping while priming.

The so-called jet ejectors are more eflicient as priming means but less eflicient as pumping means than centrifugal pumps. Since the function of a jet ejector is primarily that of priming, jet ejectors have been used in conjunction with centrifugal pumps for priming where greater priming speed is desired than can be furnished by a centrifugal pump alone.

There has long existed a demand for a centrifugal pump, which would prime much more rapidly than conventional pumps and at a speed favorably comparable to a pump and jet ejector combination, but none has been proposed heretofore which would meet those demands so far as I am aware. That demand is satisfied by the present invention.

One illustration of a use where a rapid priming action is essential is where high test gasoline is to be pumped out of drums and into the tanks of airplanes. Commercial centrifugal pumps are not satisfactory for this purpose for they require much more time to prime the suction hose and impeller chamber than to pump the 55 gallons of gasoline contained in a drum. The present invention makes it possible to deliver almost a continuous stream of such gasoline as drum after drum is being emptied because of the extremely short time required to do whatever priming is required as the hose is moved from one drum to another.

Another illustration of a use demanding rapid prim? ing action is where condensate is to be pumped, for example in a so-called vacuum heating system. There the pump must continuously handle large volumes of vapor and liquid and very little time is permitted for priming action. The present invention is quite satisfactory for such a use because of its extremely rapid rate of priming.

Still another use where rapid priming is demanded is in connection with drainage operations where the level of an underground water table is to be lowered. For this purpose well points i. e., pipes having perforations at the lower ends, are sunk into the ground approximately to the desired level of the water table and a plurality of such pipes is connected by headers to a centrifugal pump 2,791,968 Patented May 14, 1957 which is to pump out the water to lower the surface of the water table to the predetermined level. Present day self-priming centrifugal pumps do not have sufiicient air handling capacity to remove the air from these pipes rapidly or efiiciently, and as a result special well point pumps have been developed to handle the large volume of air. The present invention makes it unnecessary to use such special well poin pumps for pumps embodying the present invention have the necessary large air handling capacity.

The present invention will be better understood by those skilled in the art from the drawings accompanying and forming a part of this specification and in which:

Fig. 1 is a diagrammatic, vertical, center view through one form of apparatus embodying the present invention.

Fig. 2 is a view similar to Fig. 1 by showing a modified form of the invention, and,

Fig. 3 has a view similar to Fig. 1 by showing still another modified form of invention.

In Fig. 1 the pump housing 1 is adapted to contain fluid indicated at 2, and is provided with a fluid inlet 3. A casing 4 is disposed within housing 1 which has an inlet 5 communicating with inlet 3 of housing 1 so that gas and liquid may flow from that inlet and any pipe or hose connection associated therewith (not shown) into the interior of easing 4. This casing 4 also has an inlet 6 for a liquid within the housing. Casing 4 comprises opposite side walls 7 and 8, the former defining inlet 5 and the latter defining inlet 6, and has a peripheral wall 9 connecting the peripheries of side- walls 7 and 8 and partly defining two chambers Ill and 11 and a Venturi-like outlet 12, communicating with both of said chambers. Within casing 4 a partition Wall 15, extends parallel to and approximately midway between side- walls 7 and 8, and is integrally connected to wall 9. In approximate alignment with Venturi 12, the partition wall 15 is shaped to define a nozzle 16, and is connected to side-wall 8 adjacent to the nozzle as at 17. It will be understood that the two chambers 10 and 11 provided in casing 4 may cornmunicate with each other at the outlet of nozzle 16, and that this nozzle and Venturi 12 are in substantial alignment so that liquid delivered through nozzle 16 will be projected into Venturi 12.. A shaft support 20 is secured to the side of housing which is opposite to the inlet 3 and an impeller shaft 21, is rotatably mounted in bearings 22, carried by support 20. This shaft may be rotated by a belt (not shown) running over pulley 23, attached to shaft 21, or by any other suitable and conventional means. Shaft 21 extends through packing 25, and a packing gland at 26, which surround a hole in the side of housing Which through the shaft extends. The inner end of the shaft may be rotatably supported by bearing 27 in partition wall 15. An impeller 30 is disposed in chamber 1t and is fixed to 'the end of shaft 21, and an impeller 31, is disposed inchamber 11 of easing 4, and is also secured to shaft 21.

The operation of the apparatus shown in Fig. 1 is substantially as follows: assuming that housing 1 contains liquid substantially as illustrated in .Fig. 1, and the pump is to pump liquid, the shaft 21 is rotated. Impeller 31 pumps liquid 2 into chamber 11 and discharges it through nozzle 16 through Venturi 12 into the space above the liquid level in housing 1. The action of the liquid passing under high velocity through Venturi 12 is to draw gas from within chamber 10 and inlet 3 through impeller 30 and discharge it through that Venturi. This gas will separate from the liquid promptly after delivery into the upper part of housing 1, and the gas may escape from the housing through outlet 35 while the liquid may return for recirculation through impeller 31 and Venturi 12. As this action continues the gas is rapidly exhausted from chamber 10, inlet 3, and any pipe connecting therewith on the principal of a jet ejector, and thus the rate of removal of the'gas is much faster than when it is removed by being mixed with the liquid and pumped out of the impeller housing by means of the impeller.

As soon as the gas has been removed from chamber 10 and inlet 3 and any pipe connecting therewith, and replaced with liquid, impeller 30 pumps that liquid and discharges it through Venturi 12 along with the liquid being discharged therethrough from chamber 11. 1 In other words, at that time two impellers are pumping liquid simultaneously.

The apparatus of Fig. 1 may also be considered as follows: A first impeller casing has walls 8 and 15, an inlet 6 and a discharge nozzle 16, with an impeller 31 in the casing to discharge liquid under pressure through the nozzle. A second impeller casing has walls 7 and 15, an inlet and a discharge outlet 12 which surrounds, is aligned with and forms a chamber about the nozzle 16 of the first casing with an impeller 30. The housing 1 forms a chamber which communicates with the discharge outlet 12 from the second casing and with the inlet 6 into the first casing. Liquid and gases discharged from that outlet may separate in that chamber and the liquid is conducted into the inlet and in being discharged through the nozzle 16 induces a flow of fluid into the inlet 5 of the second casing.

It will be understood from the foregoing description that during the priming action one impeller pumps liquid and the other provides a passage for gas and vapor, and the liquid so pumped passes through a jet ejector and induces flow of gas and vapor through said passage; and that after priming has been completed both impellers pump only liquid.

In the modification shown in Fig. 2 the housing 40 is adapted to contain liquid, is provided wth an intake 41 to which a pipe may be connected if desired as at 42. The housing has an outlet 43 for gas and liquid, and is provided with packing 44, and a stuffing box 45 in one side-wall through which an impeller shaft 46 extends into the housing.

A casing 47 is disposed in the housing and communicates with inlet 41 on one side and with the interior of the casing on the other side as at 48. Thus the casing 47 may receive gas or liquid from outside of the housing 40, and may also receive liquid from within the housing.

The opposite side- walls 49 and 50 constituting casing 47 converging toward their peripheries and define a peripheral outlet 51 of Venturi configuration.

Impeller shaft 46 which extends through packing 44 and the side-wall of housing 40 projects into casing 47 and is there connected to an impeller 55. This impeller comprises a central partition plate 56 having impeller blades 57 on opposite sides thereof. Shroud rings 58 are attached to the edges of blades 57 and together with partition plate 56 define peripheral outlets 59 and 60, the latter preferably being restricted and nozzle shaped. Both outlets 59 and 60 are positioned to deliver liquid into Venturi 51.

When the pump of Fig. 2 is to prime, impeller shaft 46 is rotated and the impeller pumps liquid in through inlet 48, out through nozzle 60 at high velocity and thence out through Venturi 51. At the same time the other impeller provides a fluid path through the impeller from inlet 41 to outlet 59. The flow of the high velocity liquid through Venturi 51 acts as a jet ejector to induce the flow of gas and vapor through said fluid path. As soon as the gas in inlet 41 and piping connected thereto has been exhausted and replaced by liquid, both sides of the impeller pump liquid through Venturi 51.

In the modification of the present invention shown in Fig. 3 the housing 70 is provided to contain liquid and has an inlet 71 to be connected to a source of liquid through a pipe which may be attached, as at 72. Liquid and gas may escape from housing through outlet 73. Through one sidewall of housing 70 .an impeller shaft 74 extends and is fitted with packing 75, and the packing gland 76.

A casing disposed within housing 70 comprises sidewalls 77 and 78 the former being connected to the housing for communication with inlet 71, the latter having a central opening 79 through which liquid in the housing may enter the casing. This casing is provided with a. circumferential volute chamber 80 having an outlet 81. An impeller is positioned within the casing on the inner end of shaft 74. This impeller comprises a central wall 82, impeller blades 83 and 83a on opposite sides thereof and shroud rings 84 and 85 connected to blades 83 and 83a. Ring 84 has a central opening communicating with housing inlet 71 and ring 85 has a central opening within opening 79 of the casing and communicating with liquid in housing 7 0. The partition wall 82 and shroud ring 85 converge toward each other and form nozzle 86 through which liquid pumped by blades 83 may be discharged at high velocity. Shroud ring 84 and 82 form peripheral outlets 87 between blades 83a. Rings 84 and 85 extend outwardly beyond the outer periphery of central wall 82 and are shaped to form a Venturi-like outlet 88 into which the nozzle 86 discharges and from which the liquid may pass out thru outlet 81.

When the pump illustrated in Fig. 3 is to prime, shaft 74 is rotated. Impeller blades 83 pump liquid from within the housing through nozzles 86 and Venturi 88 thereby creating a jet ejector effect on gas and vapor between blades 83a in inlet 71 and in any pipe line connected thereto, with resultant flow of gas and vapor thru outlets 87. As soon as the gas has been exhausted and replaced by liquid, blades 83a pump liquid from outside of the housing through inlet 71 and thus all the impeller blades are pumping liquid into housing 70.

It will be understood that the clearance between the walls defining the impeller intakes and the surrounding walls of the casing is small enough to minimize the amount of pumped liquid which is returned to the intake, as is conventional practice.

It will be understood from the foregoing disclosure that gas is exhausted from the pump and the connections to a source of liquid outside of the housing largely by the jet ejector principle of operation. Thus the evacuation of gas or the priming of the pump is very much faster than when it is accomplished by mixing the gas with liquid in the impeller chamber. It will also be understood that once the pump has been primed, both impellers participate in the liquid pumping action and while the effect is not twice as great as that of either impeller alone it is considerably greater than the pumping effect of only one impeller. Thus the present invention combines the rapid evacuating action of the jet ejector with the efficient liquid pumping action of the centrifugal pump. The invention comprises a new combination of parts having this new operation and these new and hitherto unobtainable results.

Having described this invention so that others may be able to understand and practice the same, I state that what I desire to secure by letters patent is defined in what is claimed.

What is claimed is: I l. A self-priming centrifugal pump comprising a first impeller casing having a chamber, a central inlet and an outer peripheral liquid pressure discharge nozzle, an impeller rotatably mounted in said casing for moving pressure liquid from said inlet through said discharge nozzle, a second impeller casing having a central inlet and a peripheral discharge outlet aligned with said discharge nozzle, said second impeller casing enclosing and forming a chamber about said nozzle, a second impeller r0- tatably mounted in said second chamber for moving fluid therethrough, means communicating with the discharge outlet of the second casing and forming a liquid supply chamber for said first impeller about its central inlet, conduit means forming an intake for liquid and vapor to said second casing and means for rotating said first and second impeller, whereby liquid discharged through said nozzle entrains liquid and vapor in said second chamber to discharge therewith through said discharge outlet.

2. The combination of elements set forth in claim 1 in which the two said casings have a common wall.

3. The combination of elements set forth in claim 1 in which the said discharge nozzle of the first casing opens through a Wall which is common to both casings.

4. The combination of elements set forth in claim 1 10 in which the said means includes a housing enclosing and forming a chamber about said casings.

5. The combination of elements set forth in claim 1 in which the said means includes a housing enclosing said casings and having an inlet passage opening into the inlet 15 of said second casing.

6. The combination of elements set forth in claim 1 in which the said impellers are fixed to and are rotatable by a common shaft.

References Cited in the file of this patent UNITED STATES PATENTS

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