US3150597A

US3150597A - Liquid pump

Info

Publication number: US3150597A
Application number: US175042A
Authority: US
Inventors: Steenhagen Gerrit
Original assignee: Elmwood Liquid Products Inc
Current assignee: Elmwood Liquid Products Inc
Priority date: 1962-02-23
Filing date: 1962-02-23
Publication date: 1964-09-29
Anticipated expiration: 1981-09-29

Description

Sept. 29, 1964 G. STEENHAGEN LIQUIDPUMP N NsR Z mm u N5 6. I Smu F LR %a. E E 1,6 6 K m m, R w R M United States Patent 3,150,597 LIQUID PUMP Gerrit Steenhagen, Montrose, Calif., assignor to Elmwood Liquid Products Inc., a corporation of New York Filed Feb. 23, 1962, Ser. No. 175,042 2 Claims. ((Il. 10399) This invention relates to centrifugal pumps and, more particularly, to pumps of the type adapted to lift liquid from a sump and which employ vertically disposed tubular casings or rotary impellers which revolve at high speeds.

Centrifugal pumps of the foregoing type are especially adapted to the handling of fluids such as liquefied gases, e.g. liquid nitrogen, which are close to their vaporization points without there occurring significant vaporization of the liquid during the pumping operation.

In one conventional centrifugal pump design there is provided a stationary housing, a rotary tubular impeller within the housing, and a shaft for supporting and driving the impeller. The tubular impeller is vertically disposed, with its lower end immersed in liquid contained in a sump. There are provided packing glands around the shaft where it passes through the housing and bearing means for rotatably supporting the shaft. Pumps of this design are subject to leakage about the lower packing gland and to excessive wear and eventual loss of efficiency.

Another form of the centrifugal pump which is designed to overcome the shortcomings of the other conventional design described above, has the rotary tubular impeller rotatably supported only at its upper end, the lower end being free of any support. Such a design elimi hates the necessity for the lower packing gland in the sump area and represents an advancement to this extent. However, it will be appreciated that a rotary impeller which is supported at both its upper and lower ends is more stable and less likely to experience destructive vibrations than an impeller suspended solely from its upper end.

It is an object of the invention to provide an improved centrifugal pump structure requiring no packing glands in the sump area and wherein the rotary tubular impeller or casing is rotatably supported at its opposite ends to provide maximum stability.

A still further object of the invention is to provide a centrifugal pump of the rotary tubular impeller type having an exceptionally rugged construction.

Another object of the invention is to provide a centrifugal pump especially suitable for cryogenic applications.

A still further object is to provide an improved bearing support for the lower end of the rotary tubular impeller of a centrifugal pump.

A still further object is to provide means forestalling any significant vortex spinning of the liquid entering the bottom opening of the rotary tubular impeller during operation of the pump.

Another object of the invention is to utilize the liquid being handled as a lubricant for the lower bearing support of the rotary impeller.

Other objects, features and advantages of the invention will appear from the following description taken in conjunction with the drawing wherein:

FIG. 1 is a side elevational view, partially in section, illustrating a preferred form of the centrifugal pump of the invention;

FIG. 2 is a sectional view taken along line 2-2 of FIG. 1, illustrating specifically a discharge funnel located intermediate the height of the pump;

FIG. 3 is an enlarged cross-sectional view taken along lines 33 of FIGS. 1 and 4, through a lower portion of the centrifugal pump of the invention; and

3,150,597 Patented Sept. 29., 1964 FIG. 4 is an enlarged fragmentary longitudinal sectional view taken along line 4-4 of FIG. 3.

The centrifugal pump of the invention has for its main structural support member a vertically disposed U-channel beam 12 which extends the length of the pump. The beam 12 at its upper end supports a motor 16 on a platform 14. The rotor or movable impeller assembly 18 of the pump of the invention includes an outer hollow casing 20, an inner tubular casing 22, and a vertically disposed rotatably mounted pump shaft 24. The outer hollow casing 20 may be a tube of constant diameter as shown in FIG. 1. The concept of the pump does not require a constant diameter casing 20. There are advan tages in employing a hollow outer casing having differing diameters along its length.

The pump shaft 24 supports the inner tubular casing 22 adjacent its upper end by a top bushing 26 and at its lower end by a lower bushing 28. A key 30 seats in a slot of the pump shaft 24 and a groove of the top bearing 26, locking the two members together. Four equally spaced elongated vane members 34 support the outer tubular casing 20 from the inner tubular casing 22. The elongated vane members 34 are vertically disposed and each lies on a radius of the impeller assembly 18 (see FIG. 3). The four vane members 34 divide the annular space between the two

tubular casings

20 and 22 into equal sized, elongated, quarter circle compartments. With high speed rotation of the impeller assembly 18, liquid climbs up the inner wall of the outer tubular casing 20 of each of the four compartments, and at the upper end of the outer tubular casing 29 is discharged into a pump funnel 36. As best seen in FIG. 1, the vane members 34 extend a short distance above the upper end of the outer tubular casing 20, terminating within the confines of the pump funnel. The lower ends of the four vane members 34 abut against an annular bottom member 40 (see FIG. 4) which provides a restricted central opening into the bottom of the rotor impeller assembly 18, the central bottom opening being of smaller diameter than the upper end of the casing 20 at the pump funnel 36 'rotatably rests on an upper surface of a Tefion thrust bearing 44. The thrust bearing 44 is held within a bronze bushing 46 and'is free to rotate therein. The bronze bushing 46 is secured within a central vertically disposed hole of a three-arm spider member 48. The spider member 48 rests on a lower bearing channel support 50 which is secured, see FIG. 1, by two spaced plate members 52, to the main support U-channel beam 12. The two side plate members 52 are welded to the flanges of the beam 12 and the channel support 50. The upright main U- channel beam 12 is supported in any convenient manner, as for example, by several horizontally disposed U-channel beams 54.-

The structure of the pump funnel 36 is best understood with reference to FIGS. 1 and 2, where it will be seen to comprise an upright collar member 58 which closely encircles the outside wall of the outer tubular casing 20 not far from the top of that member. The pump funnel 36 has a sloping bottom 60 which continues into a chute portion 62 that has for its top a downwardly sloping panel 64. A back panel 66, sides 65 and top panel 68 complete the pump funnel. The top panel 68 has a centrally located hole through which the inner tubular casing 22 extends upwardly. Reference to FIG. 1 will show that the outer tubular casing and the four vane members 34 terminate within the pump funnel 36. Liquid discharge from the upper end of the outer tubular casing 201 leaves the pump via the chute 62 of the pump funne 36.

A special feature of the pump of the invention is the arrangement or bearing assembly for supporting the vertically disposed pump shaft 24. The pump shaft 24 is purposely provided with the reduced diameter spindle 42 to minimize the amount of bearing area. The spindle 42, as has been described, is provided with the Teflon sleeve 43 which is rotatably held within the bronze bushing 46. It will be noted that the upper end of the central vertical hole of the spider member 48 tapers out decidedly, providing a truncated, cone opening 47 above the Teflon sleeve bearing 43. This arrangement facilitates assembly, the cone opening 47 serving to guide the spindle 42 into the bushing 46. The rounded end of the spindle 42 reduces to a minimum the thrust bearing contact between the spindle and the underlying Teflon bearing 44.

The Teflon or Teflon type materials suitable for use in the fabrication of the sleeve 43 and bearing 44 are made of a halogenated polymer which contains preferably a significant amount of low temperature resistant glass fiber in an amount of, for example, or so by weight. A particularly suitable Teflon type material is a fully fluorinated copolymer of ethylene and propylene. Such a material exhibits toughness and strength over a wide range of temperatures, including cryogenic temperatures and possesses antistick and low frictional properties. The material is chemically inert.

Another special feature of the pump of the invention is the structure provided to minimize the swirling of the liquid entering the bottom of the rotor impeller assembly 18 of the centrifugal pump. The object is to bring the fluid into the rotating assembly at a relatively low velocity and with the minimum of spin. This feature of low entrance velocity is most important in obtaining pumping with a minimum of submersion of the lower end of the rotor impeller assembly 18. It has been found that minimum submergence depth is desirable where the pump is used in a refrigerating system as it improves performance of the freezing machine. The low entrance velocity is chosen to give the best compromise between the amount of submergence needed to produce suction inflow and the head producing capabilities of the force vortex of the pump rotor assembly.

The spider member 48 (see FIGS. 3 and 4) is provided with three arms 72. The central portion or the hub 74 of the spider member 48 contains the aforementioned vertical hole which houses the bearing assembly for the support of the rotor impeller assembly 18. The upper end of the hub 74 and the upper surfaces of the inner ends 75 of the three arms 72 lie in the same plane, as best seen in FIG. 4. The three arms 72 intermediate their respective lengths are sharply stepped down and provide (in plan) triangular feet supports 78, see FIG. 3. The supports 78 of the three arms 72 carry on their upper surfaces a ring-shaped baflle plate 80 which at its inner edge has an upwardly turned flange 82 that defines a short tubular enclosure. The outside surface of the upturned flange 82 makes a loose fit with the opening of the annular bottom member 40. Thus, it is seen that with this arrangement the inner ends of the three arms 72 of the spider member 48 provide antivortex plates and are thus situated to direct vertical flow of liquid without interfering lateral flow which is highly undesirable as this leads to vortex spinning of the liquid. The upturned flange 82 in providing a tubular enclosure shields the three passages defined by the three arms 72, forestalling inward lateral fiow between the upper surface of the baffle plate 80 and the lower end of the rotor impeller assembly 18. The baflie plate 80 is aflixed to the underlying channel support member 50 by three rivets which extend through holes provided in the outer supports 78 of the arms 72 of the spider member 48.

The lower end of the centrifugal pump is suspended Within a sump pan 86 that rests on the bottom of a larger outer tank 88. The level of the liquid nitrogen or other fluid within the outer tank 88 is above the top of the sump pan 86.

A special feature of the pump is the provision for directing flow of the fluid being pumped through the bearing means supporting the vertically disposed pump shaft 24. The fluid provides lubrication in passing through the bearing means. Reference to FIG. 4 will show the lower bearing channel support 50 is provided with a hole Sila opening across its thickness to the underside of the thrust bearing 44. The underside or bottom of the thrust bearing 44 carries two horizontally-disposed cross slots 44a which permit liquid to flow from the hole 50a to the annular void defined by the chamfered outer perimeter 44b of the bottom of the thrust bearing 44 and the encircling bronze bushing 45. The thrust bearing 44 on its outer surface is provided with four spaced longitudinally extending grooves 440 which provide paths for the flow of the liquid upward from the annular void to a similar annular void at the upper surface of the thrust bearing 44, the upper annular void being formed by a chamfered top perimeter 44d of the bearing 44 and the encircling bronze bushing 46.

Reference to FIG. 4 will show that the Teflon sleeve 43 does not extend to the thrust bearing 44. The liquid reaching the upper annular void flows upwardly through the three spaced channels earlier described which run the length of the spindle 42 (the channels being between the respective flattened surfaces 42a of the spindle and the sleeve 43). Thus, it is seen there is a passageway running the length of the bearing means to provide lubrication. It is thought that at least a portion of the liquid nitrogen or other liquefied gas flowing through the passage means of the bearing will evaporate. The gas so formed will promote the circulation of the liquid nitrogen by reducing the effective density of the fluid in the zone of the bearing, thus permitting the hydrostatic head of the liquid within the sump to force more liquid into the bearing.

Although an exemplary embodiment of the invention has been disclosed herein for purposes of illustration, it will be understood that various changes, modifications, and substitutions may be incorporated in such embodiment without departing from the spirit of the invention as defined by the claims which follow.

I claim:

1. In a centrifugal pump adapted to lift liquid from a sump, the improvement comprising:

a vertically disposed first tubular casing with an opening at its lower end through which liquid is admitted;

a vertically disposed second tubular casing of a smaller diameter concentrically positioned within said first casing;

elongated spaced vanes disposed between the two tubular casings and fixed respectively thereto, thus providing fluid channels along at least a portion of the length of the first tubular casing;

a rotatably mounted supporting shaft disposed along the common axis of the two concentric tubular casings with the lower end of said shaft extending below said two casings, said rotatable supporting shaft being fixed to the inner one of the tubular casings;

means forestalling substantial vortex spinning of the liquid entering the bottom opening of the outer first tubular casing, said means including a fixed antivortex plate extending from below said casing and terminating at its upper end within the casing above the lower end thereof, and a vertically disposed tubular enclosure for the antivortex plate along at least a portion of its length, said tubular enclosure being located immediately adjoining the lower end of the casing, thus situated to provide a substantially vertical flow of liquid without interfering with 6 enclosure for the antivortex plate along at least a portion of its length, said tubular enclosure being located immediately adjoining the lower end of the casing, thus situated to provide a substantially verthe lateral flow to the bottom opening of the casing; 5 tical flow of liquid without interfering with the and lateral flow to the bottom opening of the casing; bearing means disposed within said sump with the a sleeve press fitted about the lower end of the shaft lower end of the supporting shaft being rotatably with the butt end of said shaft being rounded imcarried by said bearing means, said bearing means mediately below the press fitted sleeve; and

being provided with a passage permitting the flow 10 bearing means disposed within said sump and inof liquid therethrough, said flow of liquid providing lubrication of the bearing means.

cluding a thrust bearing immediately below the shaft with the butt end of the shaft bearing thereon and a bearing surface about the sleeve positioned to slidably engage said sleeve and passage means permitting flow of liquid through the bearing means.

2. In a centrifugal pump adapted to lift liquid from a sump, the improvement comprising:

a vertically disposed second tubular casing of a smaller diameter concentrically positioned within said first References Cited in the file of this patent UNITED STATES PATENTS casing 288,409 Christensen Nov. 13, 1883 elongated spaced vanes disposed between the two tubu- 1 23322: 3; 9 lar casings and fixed respectively thereto, thus pro- 1O94836 De Lava] A 1914 viding fluid channels along at least a portion of the 1294347 Pease s 1919 leng h f the first l r g; 1728277 ha qept' 1929 a rotatably mounted supporting shaft disposed along 1869824 Richter 1932 the common axis of the two concentric tubular cas- 2149921 Lea g 1939 ings with the lower end of said shaft extending be- 2166276 gg f 1939 low said two casings, said rotatable supporting shaft 26145O1 Baker Oct 1952 being fixed to the inner one of the tubular casings; 2851956 Lung qvept' 1958 means forestalling substantial vortex spinning of the 2:935:108 ggfIIiiI: M 1961 liquid entering the bottom opening of the outer first tubular casing, said means including a fixed antivortex plate extending from below said casing and termi- Chicago Gasket New W W to USE nating at its upper end within the casing above the 1011 Products, receivfid June 10, 1952 3 lower end thereof, and a vertically disposed tubular P g OTHER REFERENCES

Claims

1. IN A CENTRIFUGAL PUMP ADAPTED TO LIFT LIQUID FROM A SUMP, THE IMPROVEMENT COMPRISING: A VERTICALLY DISPOSED FIRST TUBULAR CASING WITH AN OPENING AT ITS LOWER END THROUGH WHICH LIQUID IS ADMITTED; A VERTICALLY DISPOSED SECOND TUBULAR CASING OF A SMALLER DIAMETER CONCENTRICALLY POSITIONED WITHIN SAID FIRST CASING; ELONGATED SPACED VANES DISPOSED BETWEEN THE TWO TUBULAR CASINGS AND FIXED RESPECTIVELY THERETO, THUS PROVIDING FLUID CHANNELS ALONG AT LEAST A PORTION OF THE LENGTH OF THE FIRST TUBULAR CASING; A ROTATABLY MOUNTED SUPPORTING SHAFT DISPOSED ALONG THE COMMON AXIS OF THE TWO CONCENTRIC TUBULAR CASINGS WITH THE LOWER END OF SAID SHAFT EXTENDING BELOW SAID TWO CASINGS, SAID ROTATABLE SUPPORTING SHAFT BEING FIXED TO THE INNER ONE OF THE TUBULAR CASINGS; MEANS FORESTALLING SUBSTANTIAL VORTEX SPINNING OF THE LIQUID ENTERING THE BOTTOM OPENING OF THE OUTER FIRST TUBULAR CASING, SAID MEANS INCLUDING A FIXED ANTIVORTEX PLATE EXTENDING FROM BELOW SAID CASING AND TERMINATING AT ITS UPPER END WITHIN THE CASING ABOVE THE LOWER END THEREOF, AND A VERTICALLY DISPOSED TUBULAR ENCLOSURE FOR THE ANTIVORTEX PLATE ALONG AT LEAST A PORTION OF ITS LENGTH, SAID TUBULAR ENCLOSURE BEING LOCATED IMMEDIATELY ADJOINING THE LOWER END OF THE CASING, THUS SITUATED TO PROVIDE A SUBSTANTIALLY VERTICAL FLOW OF LIQUID WITHOUT INTERFERING WITH THE LATERAL FLOW TO THE BOTTOM OPENING OF THE CASING; AND A BEARING MEANS DISPOSED WITHIN SAID SUMP WITH THE LOWER END OF THE SUPPORTING SHAFT BEING ROTATABLY CARRIED BY SAID BEARING MEANS, SAID BEARING MEANS BEING PROVIDED WITH A PASSAGE PERMITTING THE FLOW OF LIQUID THERETHROUGH, SAID FLOW OF LIQUID PROVIDING LUBRICATION OF THE BEARING MEANS.