US3010402A - Open-case pump - Google Patents

Description

Nov. 28, 1961 Filed March 9, 1959 J. L. KING OPEN-CASE PUMP 2 Sheets-Sheet l INVENTOR JOHN L. Kl 6 Nov. 28, 1961 Filed March 9, 1959 J. L. KING OPEN-CASE PUMP 2 Sheets-Sheet 2 INVENTQRt A TTOR/VE United States Patent Oilice 3,610,402 Patented Nov. 2 8, 196.14

This invention relates to an improved centrifugal pump having special utility in the transfer of liquids or molten materials at extremely high temperatures.

Many important industrial processes, such as those involving reduction, purication, and separation of certain metals and chemicals, require large amounts of heat at high temperature levels. Molten substances of high heat content can fulfill this heat requirement, but their transfer from a high-temperature reservoir or melting furnace has led to difficulties in the pumping operation.

For example, molten salt is used to melt the waste aluminum chips obtained during the machining of aluminum parts. Solid salt in a large cauldron is melted and heated to about 1500" F. by the direct application of heat to the cauldron. Then the molten salt is pumped at a suitable rate of flow to the desired location and used to melt the aluminum chips. The molten-salt method of melting aluminum chips has proved highly successful and, in fact, is the onlymethod now known which can do the job economically.

However, the pumping of the molten salt gave rise to serious problems, and so did other operations where it became necessary to transfer liquids at extremely high temperatures. The diculty arose from the fact that the vital elements of the pump operate in contact with the high-temperature molten material. It soon became apparent that a pump immersed in such molten material could not have the immersed pump housing constructed from more than one part. In the high-temperature environment, conventional connections such as rivets, nuts and bolts, became distorted and lost strength, and were not able to maintain the structural integrity of the pump case. Therefore, it was foundnecessary to use a welded or integrally cast case. But, before the present invention, this meant that when repair, replacement, or adjustment of the bearings or impeller was required, the entire pump unit had to be replaced, or the pump case had to be torn apart to gain access to the worn or damaged parts. 'Ihe problem was all the more serious because the pumping of thick, molten material at extremely high temperatures tended to increase the wear of the internal operating components and more frequent repair and servicing were required.

My invention has solved the problem by providing a pump with its case open at the lower end and its impeller mounted in this open end in a way enabling its removal. An important feature of my invention is that the impeller is mounted on a shaft that extends up inside the case and is rotatably secured to the case at a point not exposed to high temperature; this feature makes it possible to adjust the impeller relative to the case during operation, when the impeller is actually in molten salt. It also provides for ready removal of the shaft and impeller from the case, when repair or replacement is needed. v

It is, therefore, an object of my invention to provide a centrifugal pump especially adaptable for transferring very high-temperature molten materials, wherein the pump impellr" is mounted externally to the pump case and can be disconnected from the case without rst removing a portion of the case.

Another object of the present invention is to provide an open-case centrifugal pump Ihaving an externally mounted impeller which is adjustable with relation to the case to compensate for wear of the impellerpoccurring after sustained operation.

Other objects and advantages of the invention will appear from the following description of' a preferredv embodiment thereof.

In the drawings: FIG. l is a view in elevation and in section of a Y pump embodying the principles of my invention. Some parts have been broken in the middle and other parts broken off, to conserve space.

FIG. 2 is an enlarged view in horizontal section taken along the line 2 2 in FIG. l, showing the impeller and diffuser blades of the pump and the path of the molten material therethrough. A

FIG. 3 is a View in horizontal section taken along the line 3 3 in FIG. l, showing the take-up adjustment of the impeller shaft, in detail.

My invention, in broad terms, comprises an improved centrifugal pump 4 whose lower end 5 may be immersed in a pool of a liquid 6 to be pumped. The liquid 6 may be molten material at an extremely high temperature. In contrast to pumps of the prior art, where the moving pump components are enclosed in the case, my novel pump has a case or housing 7 with an open lower end 8 lying centrally of the axis of an annular diffuser section 9 and defining an upwardly extending tapered recess 10. An impeller y11 is adapted to rotate within the recess 10 with its peripheral outlet passages 12 adjacent diuser inlet passages y13 of the section 9. Between the impeller 11 and an inner surface 14 of the recess 10 is a clearance gap 15.

The impeller 11 is mounted on the lower end of a shaft 16 driven by a power source 17 that may be mounted on the upper end of the case'7. Near the upper end of the impeller shaft 16 I have provided an adjustable take-up connection 20 to control the vertical position of the shaft 16 relative to the case 7. By moving the shaft 16 up and down within the `case 7 I can vary the width of the gap 15 between the rotating 'impeller 11 and the diiuser inlets 13. Note that the impeller adjustment is made at a point on theV shaft 16 far above the level of the molten material 6, and that it may be made when the lower end 5 of the lpump 4 is immersed and the pump 4 is in running position. rI'lhe connection 20 is the only connection between the shaft y16 and the case 7; so when the pump 4 is .taken out of the liquid 6, the shaft 16 may be disconnected from the power source 17 and it and the impeller 11 dropped down and out of the case 7, for repair or replacement of worn-out parts. Thus, the utility and life of the centrifugal pump 4 is greatly increased since, with my invention, repairs, adjustments, and replacement of vital parts may fbe made easily and without destruction or even damage to the case 7.

Considering the pump 4 in more detail, the case 7 has an upper housing 21 and a Ilower housing 22. Mounted atop a removable plate 23 on the open upper end of housing 21 is the power source 17, which may comprise a constant-speed electrical motor of suitable size mounted conveniently with its driving-shaft 24 substantially vertical. The shaft 24 may be connected to a exible coupling l25 within the upper housing 21, to eliminate alignment problems. Connected to the lower portion of the flexible coupling 25 is a short connecting` shaft 26 which is adjustably connected with the impeller-shaft 16, in a manner explained below. 'Ihe impeller-shaft 16 extends `downwardly through thelower housing 22 to connect at its lower end with the impeller 11.

On an inner flange or spider 28 of the upper housing 21 is mounted, as by bolts 29, a self-aligning thrust-bearing 30, through which passes the impeller-shaft 16. The

take-up adjustment 20 for the impeller-shaft 16 is provided `prevent relative movement thereof. The impeller-shaft V16 has a threaded upper end 35 that engages the interior threads of the sleeve 31. Y

Y The short connecting-shaft 26 attached to the flexible coupling 25. tits within a hollow end-section 36 of the shaft 16. The section 36 is of slightly larger diameter than the shaft 25, and a driving connection between the shafts 16'and 26 is established by a key 37 which may be fixed integrally to the shaft 26 or may be fitted in a groove 38 therein. The key 37 also extends through a slot 39 `(FIG. 3) in the upper threaded portion 35 ofthe impeller-shaft 16 and is attached to the upper flange 33 of the sleeve 31 by a screwr40 that goes into any one of a plurality of tap-holes 41 in the llange 33. Therefore, relative movement between the impeller-shaft 16 and the sleeve member 31. may be `obtained by removing the screw 40, threading the shaft 16 in the sleeve 31, and

putting the screw 40 back into a hole 41. This relative movement provides longitudinal adjustment of the impeller-shaft 16-and of the impeller 11 relative to the pump case 7 and the recess 10.

It is apparent, Vof course, that many types of take-up adjustment structures, which are common to interconnecting shaft members, can be used. Thus, while I have v shown one mechanism for adjusting the vertical position `of the impeller-shaft 16, I wish it to be understood that my invention is not limited to this specific mechanism -of shaft adjustment.

In the installation shown in FIG. l, the upper housing 21 is Welded to a'basemounting-plate 42, which is connected to an integral ange 43 vof the lower housing 22 by a suitable attaching means 44, such as bolts or rivets. The mounting-plate 42 may then be removably connected to a floor-plate 45 by bolts 46. The lower housing 20 'extends down through an opening 47 in the licor-plate 45 ntothe molten material 6, which may be in a heated cauldron (not shown).

At the bottom portion of the lower housing 22 and integral with it is the diffuser section 9. The diffuser 9 may be of a standard type used in centrifugal pumps, with directional -vanes50 spaced vcircumfe'rentially (see FIG. 2) to direct the flow of the liquid 6 received from the impeller 11.V The vanes `50 define passages 51 and operate in the conventional manner to transfonnthe velocity imparted to the liquid 6 by the impeller 11 into a pressurefhead. Leaving the passages 51, the liquid 6 enters a circular collecting chamber 52 at an increasedL pressure and leaves the chamber 52 by an exit 53 which leads into a pump outlet-conduit 54.

The diffuser inlets 13 are located along the periphery 4sides 58 which include the impeller-outlets V12 from the passages 57. An important feature of my invention is Vthat the angle of taper of the impeller sides 58 is substantially the same as the taper of the wall 14 of the conical recess in the diffuser section 9. The impeller- .shaft 16 is mounted along the axis of the case 7, which is also the axis of the conically tapered recess 10. In mounting the impeller 11, I prefer to weld it to the shaft 4 aligned with the inlets 13 to the dtuser 9, leaving only a small clearance gap 15 between the impeller 11 andthe diffuser inlet 13.

Within the lower housing 22, a stainless steel sleeve member 60, providing bearing protection, is press-fitted to the impeller-shaft 16 directly above the impeller 11. Between the sleeve member 60 and the lower housing 22 is mounted a rst shaft-bearing 61 made of carbon, preferably in the form of solid graphite.-VV The bearing 61 may be held in place by pins 62 extendingothrough the sidewall of the lower housing 22 into the carbon-bearing 61 and retained by lock-wires 63 attached therethrough. A washer 64, resting on the sleeve member 60,- retains a second carbon-beating 65 .similarly held in place by pins 66 with lock-wires 67. Y

. A strainer 7@ may be attached to the lower end of the lower housing 22. For. this purpose, integral brackets 71 may extend from the housing 22 with holes 72 which align with similar holes 73 on the strainer 70.V Locking-wires 74 maybe passed through the holes 72 and 73 to secure the strainer 70 in place. The strainer 70 is perforated with apertures 75 of any desired shape, which permit ow of the molten material 6 while preventing the influx of lumps or foreign material into the impellerll.

- In operation, the lower end 5 ofthe pump 4 is immersed in the molten material 6, such as molten salt at 1500 F. Power is supplied to the electrical motor 17 which turns the impeller-shaft 16 and the impeller 11 at the desired speed. The rotating impeller 11 draws the molten material 6 up through the strainer 70 into its inlet-eye 56 and into the impeller passages 57. The impellerV 11 `is positioned within the recess 10v so that its outlet passages 12 pass adjacent the diffuser-inlets 13 in the 'conical recess 10. The molten material 6 thus passes from. the impeller 11 across the clearance-gap 15 into the diffuser section 9 where pressure is built up before the liquid 6 enters the collecting-chamber 52 and leaves the housing 20 through the chambers exit 53.

Duringoperation of the pump, slight leakage occurs through the clearance gap 15, but the adjustable feature of my pump permits this clearance 15 to be kept at the Y `optimum amount,rthereby.reducing leakage. to a mini- Y16 to make a secure connection. The impeller 11 is thus 1 positioned so that the impeller outlet passages 12 are vmum. The adjustment is Vmade at the take-up connection 20 on the thrust-bearing 3i)y by merely loosening the screw 40 and rotating the impellerashaft 16 relative to the threaded sleeve 31 by the desired amount and tightening the screw 40. This rotation causes the shaft 16 to move up or down in the case 7 to vary the clearance-gap 15 be- .tween the beveled impeller 11 and the conical recess 10.

For completeV removal of the mipeller-shat 16, the strainer 70 is removed and the shaft 16 is then disengaged from the sleeve 31 by rotating it until it drops free from the case 7. It is thus a simple matter to render any necessary repairs to the internal pump parts, such as the diluser 9 orrthe bearings 61 yand 65. f The :impeller 11 itself can be repaired =by adding metal to its peripheral surfaces so that its life can be extended substantially.

The present invention thus provides a pump for molten material which canbe easily serviced and adjusted in running position to provide efficient operation and lon-g life under extreme conditions. My pump thereby enables the use of molten materials wherever theymay be needed for heat and power transmission. e

'While I have described myY novel pump structure in conjunction with high tempenature molten materials, citing the aforementioned example of molten salt, it is obvious that the principles of my invention are applicable wherever materials with severe temperature properties yare encountered and where high perfomance, and ease of maintenance of Ithe pump output, become moreV important considerations than absolute maximum eiciency. For example, the open-case pump of the present invention may also be used to good advantage rin pumping materials at extremely low temperatures such as liquid oxygen lwhere again the material being pumped imposes severe limitations on the endurance vand accesibility of the pump structure. lIt is obvious of course that my invention will also nd applications in the pumping of molten metals such `as sodium or lead in Various heat transfer cycles or smelting processes.

To those skilled in the art to which this invention relates, many changes in construction and widely diiering embodiments and applications of the invention will suggest themselves without departing from the spirit and scope of the invention. The disdlosures and the description herein are purely illustrative and are not intended to be in any sense limiting.

I claim:

1. In a centrifugal pump for transferring molten material of extremely high temperature, such as molten salt, comprising a housing; a shaft extending through and mounted in said housing, having a beveled mixed-now impeller mounted on its lower end; a source of power mounted on the upper portion of said housing, having a drive-shaft extending therefrom; a flexible coupling attached to said `drive-shaft; a connecting-shaft attached to the other side of said coupling; a self-aligning thrustbearing mounted in the upper portion of said housing, said impeller-shat having a hollow sleeve portion at its upper end adapted to tit Within said thrust-bearing and around a lower portion of said connecting-shaft; locking means on said thrust-bearing to adjustably attach said impeller-shaft Ito said connecting-shaft; `an integral diffuser section on the lower portion of said housing and a discharge pipe leading therefrom; an inwardly tapered conical recess in the outer surface of the lower portion of said housing adjacent said ditfuser section; inlets to said diifuser -section located within said recess; said impeller-shaft being mounted through the center of said recess, on an axis coincident with the axis yof said recess, said beveled impeller being attached to said shaft and having a central inlet and a plurality of peripheral outlets; said impeller being positioned on said impeller-shaft so that its outlets are substantially adjacent and aligned with said diffuser inlets.

2. A centrifugal pump for transferring molten material, comprising a case having -a diffuser section integral therewith; an inlet to said diuser section, said inlet being formed in a wall of a truste-conical recess in said case; a detachable impeller-shaft mounted in said case on an axis substantially through the center of said recess; means to `adjust the length of said impeller-shaft to vary the clear-ance between said impeller and the diffuser inlet including means =to completely disconnect said impellershaft for removal Vfrom said pump case; Iau impeller mounted on the end of said shaft, having a centrally located inlet and outlets aflong a beveled periphery; and means to rotate said shaft Within said recess so that the impeller outlets pass directly adjacent to a diiusefr inlet; land material-outlet means mounted on said case.

References Cited in the le of this patent UNITED STATES PATENTS 1,370,451 Johnston Mar. 1, 1921 2,273,420 Schott Feb. 17, 1942 2,434,018 Stepanoi lan. 6, 1948 2,706,622 Steaaf Apr. 19, 1955 2,854,926 Haight et al. Oct. 7, 1958 2,865,299 Hornschuch et al. Dec. 23, 1958 2,874,642 Forrest Feb. 24, 1959 FOREIGN PATENTS 12,886 Great Britain of 1885 257,111 Great Britain Aug. 26, 1926 774,692 Great Britain May l5, 1957 808,796 Germany July 19, 1951 904,849 France Mar. 19, 1945 954,669 Germany Dec. 20, 1956 1,175,345 France Nov. l0, 1958

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