US1900531A - Multistage centrifugal pump - Google Patents

Description

March 7, 1933. J, E. vlTU 1,900,531

MULTISTAGE CENTRIFUGAL PUMP l Filed sept. 19, 1929 4 sheets-sheet 1 Lgg l I l l l if March 7, 1933. J. E. vlTU 1,900,531

MULTISTAGE CENTRIFUGAL PUMP Filed Sept. 19, 1929 4 Sheets-Sheet 2 March 7, 1933. J, E V|TU 1,900,531

MULTISTAGE CENTRIFUGAL PUMP Filed Sept. 19, 1929' 4 SheetS-SheelI 3 March 7, 1933. 1 E V|TU 1,900,531

MULTISTAGE CENTRIFUGAL PUMP Filed Sept. 19, 1929 4 Sheets-Sheet 4 zg/Z556. MMM a M m i@ Eefeered Meer, 1933 UNITED sTATEs l PATENT -oFF'lcE TABS Ee VITU, OF GHIOAGO, ILLINOIS, ABBIGNO TO WEIL Pm OOD CHICAGO, ILLINOIS, .A CORPORATION OI' ILLINOIS IULTIBTAGE CENTBIIUGAI Pm vappueeanm meg september 1s, ma 'semi n. :$3,003.

This invention relates to improvements in multi-stage centrifugal um s.

In the art of centri ga pumps, great diiiiculty has always heretofore been experiencedv on account'of unbalanced pressures resulting in heavy end thrusts which 1n turn cause excessive wear and loss of eiciency in operation and the main object of my invention, therefore, is to so construct and arrange the parts of a multi-stage centrifugal ump as to obtain balance pressures an thereby eliminate or substantially eliminate an endwise thrust. Another o ject of my invention is to p rovide a multi-stage centrifugal pump having the parts thereof so arranged that the unequal pressures develo ed by one of the 1mpellers are neutralize by reversely arran ing another similar impeller secured to t e same shaft.

Another object of my invention is to provide, in a four-stagxe centrifugal pum an arrangement such t at two of the impe lers each develop substantially balanced pressures and the remaining'two impellers, although each developing unbalanced pressures, are so arranged that the unbalanced pressures are neutralized.

More general objects of my invention are to provide a multi-stage centrifugal pump of compact arrangement, com rised of a minimum number of parts, an eiiicient in operation.

0ther objects of my invention will more clearly appear from the description y and claims hereinafter following.

- In the drawings formin a part of this specification, Fi re 1 is a longitudinal vertical sectional vlew of a four-stage centrifugal pump showing my improvements incorporated therein, the section being a diametrical section and portions of the casin being left in elevation. Figure 2 is a vertical broken sectional view taken lengthwise of the casing and corresponding substantially to the line 2-2 of Fi ure 7. Figures 8, 4, 5, 6 and 7 are vertica transverse sectional views corresponding respectively to the section lines 3-3, 4 4, 5 5, 6-6 and 7-7 and looking in the direction of the arrows, said section lines being indicated on Finlre 1.

e improved pump, as shown comprises, broadly, a casing a shaft B first second l third and fourth stage impellers D, and F, respectively, together with bearin s, pressure rings, sealing rin s and the li e, more particularly describe hereinafter.

The casing A is preferably of the horizon tally split type, having a lower member 10 60 and an upper member 11, each of approximately semi-cylindric form and diametrically anged as indicated at \.12-12, the latter bein secured together by suitable bolts or ot er fastening devices 13. The lower member 10 of the casing is formed with suitable depending pedestals 14-14 to provide a su port and means of attachment to a base or t e like, and, at 'each end is provided with wells 15--15 and journal bearing 10 supports ,16-16.

The casing proper, which provides the chambers for the impellers, is constituted by an end wall 17 at the left, as viewed in Figure 1, an end wall 18 at the right, and I5 vertically disposed partitions 19, 20`and 21, to there y provide a casing havin four chambers, as will be clear from an inspection of Figure 1. At one end, (the lefthand end as viewed in Fi re 1 and the righthand end as viewed in Figure 2) the lower member of the casing is formed with a tubular section 22 extending horizontally and laterally outward, whlch tubular section is flan ed at its outer end as indicated at 23 in igure 3, and provides the intake opening 24 and lnt-ake passage 25 leadin to the first impeller. From the second c amber, containing the impeller D, a passage is formed in the lower member of the casing which extending first vertically downwardr1y, as indicated at 125 in F1 re 2 and thence horizontally as indicate at 26, and then upwardly as indicated at 27, the latter portion of the passageway being ada ted to conduct the fluid to the third or rig thand end chamber, as viewed in Figure 1. The horizontal portion of said passageway between the second and third chambers of the pump has a partition 28 disposed therewith- 1U chamber of the casing is extended horizontally `and laterally another tubular section 29 shown in Figure 6, which tubular section is flanged at its outer end as indicated at30 and provides the discharge passage 31.

Theshaft B is rotatably supported at its ends by meansyof suitable ball bearings 32- 33, supported in bearing housings 34-34, carried by the bearing support sections 16 of the casing. Each of the housings 34 is y provided with aremovable cover plate 36 and is adapted to contain oil, grease or other suitable lubricant, the supply for which may be .maintained through the lubricating cup 37. Each bearing housing is provided with a drain 38 normally'closed by a screw plug 39.

To seal the shaft and casing against leakage, each of the end walls 17 and 18 of the casing is formed with a hub 40 and 41, respectively, the hubs being outwardly offset from the upper portions 17 of the end walls, as best shown in Figure 1. Within the hubs is secured a bearing ring 41, nearest the corresponding impeller, and outwardly of each ring 4l is a series of packing rin s 42-42 and cooperable with each serles o packing rings is an adjustable packing gland 43-' 43. In the case of the packing arrangement adjacent the first impeller, a duct 44 leads from the first chamber to the shaft at a point approximately midway of the packing rings 42. Through this duct the water or other fluid being handled will be forced to the packing rings under pressure so that, should a partial vacuum exist in the admission chamber, air will not be drawn through the packing. ln the case of the other set of packing rings at the opposite end of the shaft, it is obviousl that the packing will alj ways-be under` pressure.

- Referring now more particularly to Figures 1, 3 and 4, the water or fiuid being handled by the pulnp enters through the passageway 25 and is deflected upwardly and preferably divided by a fixed partition 45 and enters what may be termed the end admission chamber 46, whence it is delivered or passes to the impeller C through the annular intake opening 47 of the latter. Said impeller C is provided outwardly of the hub 48 thereof with two spaced webs 49-49 between which and integral therewith, are a plurality of curved radiating impelling blades 50--50 so that, as the water is acted upon b the im ller C, it will be thrown outwar 1y into t e first chamber, as will be understood. Within said first chamber is a fixed partition -51 of slightly greater dialneter tian the diameter of the impellerl C, said partition 51 being preferably inclined away from the fixed partition 19 and be-. tween which and integral therewith are fixed ribs 52-52 of arcuate form and which serve to break up or mingle the water as it passes inwardly toward the shaft 011 its passage to the second impeller D.

The hub 48 of the impeller C is keyed to the shaft B by a suitable key 53. Between the e'nd wall 17 and the hub of the impeller C are two water sealing rings 54 and 55, one of said rings preferably being provided with a serles of annular grooves to thereby provide a better seal. Secured to the fixed partition 51 adjacent the impeller C is a combined' wear and thrust ring 56 of generally right angular formation and between the perlpheral flange thereof and the hub 48 is another sealing ring 57 similar to the'ring 55. Secured to the shaft and interposed between the hubs of the mpellers C and D is a sealing bushing 58 also preferably having water sealing grooves therein opposite the ,ring 56.

As well understood .in the art, as water is passed through and acted upon by an impeller in a centrifugal pump, the pressure is built up by the action of the impeller so that the pressure around the impeller and beyond it, with the passage of the water, will be greater than the pressure at the intake opening of the impeller. Hence the pressure in the first chamber will be greater on that ortion of the back or far side of the impe ler C directly opposite the intake area,tha't is, the side farthest from the intake opening thereof, and to relieve this pressure and substantially eliminate endwise pressure. onv the impeller C, the latter is provided with an annular recess 59 on its back side and opposite the ring 56. A plurality of spaced openings or apertures 60 are formed in-the web of the impeller so as to establish communication between the annular recess 59 andthe intake side or opening of the impeller. Hence, if any water seeps through the seals provided by the ring 56, to get on the back side of the hub of the impeller C, the pressure will not be built up but will be constantly relieved so as to equalize the pressure on` the impeller C in'the opposite direction which is Iimpressed thereon from the intake side, thus obtaining a balanced pressure on the impeller C. As understood by those skilled in the art, inasmuch as the impeller C is the first or initial impeller of the pump, the pressure on the intake side thereof may be either positive or negative, dependent upon conditions, but the balancing arrangement for said impeller C will nevertheless be effective under all variable conditions.

As the water is delivered from the first chamber near the shaft, it then enters the intake opening 61 of the second impeller D, which, 1n general construction, except for the annular recess 59 and apertures 60 is quite similar to the impeller C. The 1mpeller D is keyed to the shaft by a ky 62 and sealing rings 63, 64, are em loye between the hub of the impeller and the artition 19. On the opposite sideof the impeller D, a more or less Z-shaped 65 is secured to the partition 20 o the casing and with said rmg 65 cooperates a T- section loose floating ring 66 and, as will be evident the'floatling ring 66 will always normalfy be pressed toward the left due to the fact that the pressure in the fourth chamber containing the impeller F will always be greater than the pressure delivered to the ring from the second chamber.

The water, after being acted upon by the second impeller D, is then delivered through the passageway 125, 26, 27 to the third or righthand end impeller E. As the water leaves the section 27 of said passage it 1s delivered into a chamber 67 which communicates with the intake 0 ening 68 of the im ller E. The latter 1s of substantially t e same form as the impeller C except that it does not have any annular recess or openings 59-60. The water, after being acted u on by the impleller is delivered from t e periphery t ereof into the third casing chamber 69, which is divided by a artition 70 similar to the partition 51. fter passin around the outer edge of the partition and thence inwardly, during which travel the water is broken up by the longitudinally extending partitions 71, it is then delivered to the intake o ening 72 of the fourth impeller F, as s own in Figures 1 and 6. After being acted upon by the impeller F, the water is delivered through the discharge passage 31,

as shown in Figure 6.

The impeller F is similar to the impeller D, but is oppositely disposed, as is clear from Figure 1. Each of the impellers D and F is unbalanced no provision being made for balancing the pressures with res ect to these impellers individually, but,

ue to the fact that they are oppositely disposed and by the use of the floating ring 66, it is evident that the unbalanced pressure of one of these impellers will be neutralized by the unbalanced pressure of the other.

Referring now to the third impeller E, balance of the pressures with respect thereto is effected inthe following manner. As will be evident, the pressure on the hub from the chamber 67 side will be less than the pressure on the opposite side of the impeller within the angular shaped sealing ring 73. The diameter or area of the surface of the impeller, which is exposed to the pressure in the chamber 67, is greater than the area of the exposed surface of the impeller on the other side within the recess 74, the exposed area on the said other or back side of the impeller being less by the amount of the thickness of the hub section 180. These different exposed areas" on the opposite sides of the impeller E will be so proportioned that. the pressure 'times the exposed area on the intake side will equal the greater pressure times the lesser exposed area on the other or back side of the imeller. Hence, it will be seen that the two impellers YD and F neutralize each other, so far as endwise pressure or thrust is concerned, and the two end or first and third impellers C and E are each individually balanced so that the entire arrangement is left in balance and end thrust thereby eliminated or minimized to such extent as to be practically negligible. ln the case of the third stage impeller E, it is obvious that there will always be a positive pressure on the intake side thereof and it is because of this reason'that I am able to employ the much cheaper and simpler balancing arrangement for this impeller, above described, than the balancing means heretofore descCribed in connection with the impeller All of the ilnpellers are assembled on the' shaft and keyed thereto in the manner previously described and are held pro erly as selnbled by threading the sha-ft as lndicated at 75-75 and then applying lock nuts 76-76. For riming the pump, each of the impeller cliambers is provided with a pet"cock 77 at the top and to facilitate handling of the pump when putting it in place, heavy screw eyes 7 8-78 may be used, as indicated. The several impeller chambers are provided with removable drain plugs 79-79, as shown in Figures 4, 5, 6 and 7. l

I have herein shown and described what l now consider the preferred manner of carrying out the invention, but the same is merely illustrative and all changes and modiications are contemplated that come within the scope of the claims appended hereto.

lring loosely surrounding said shaft and lll having an outstanding annular flange with a plane surface overlapping the plane surface of said flange of the fixed sealing ring and disposed on that side of the sealing ring facing the chamber having the higher pressure, whereby the flange of the floating ring is pressed against the flange of the fixed ring by the pressure developed in said chamber having. the higher pressure and the floating ring may shift relatively to the fixed ring in a plane perpendicular to the axis of the shaft.

2. In a four-stage centrifugal pump, the combination with a casing having four chambers and passageways leading from the first to the second chamber, from the second to the fourth chamber and from the fourth to the third chamber in the order of the arrangement of the chambers lengthwise of the casing; of an impeller mounted in each of said chambers, said impellers being mounted on a, common shaft and the fluid handled by the pump being acted upon successively by the first, second, fourth and third impellers in the order of their arrangement lengthwise of the shaft, the second and third impellers being each unbalanced but of like construction and oppositely disposed 011 the shaft whereby the unbalanced pressures developed thereby are neutralized; means associated with the first impeller including openings through the impeller, for balancing the thrusts thereon and effective with plus or minus pressures on the intake side of said impeller; and thrust pressure balancing means associated with said third impeller.

3. In a multi-stage centrifugal pump, the combination with a casing having a plurality of chambers and communicating passageways between the chambers; of an impeller mounted in each of said chambers, said impellers being carried by a common shaft; and means for balancing the thrust pressures on one of said impellers other than the impeller first to act upon the fluid, said means including a hub arrangement on said impeller having its opposite ends subject to the respective pressures on the intake and discharge sides of the impeller, the area of the hub end on the intake side subject to the intake pressure being greater than the area of the hub end on the outlet side subject to the discharge pressure, said areas being so proportioned that the total pressures on the opposite sides of the impeller are substantially equal.

4. In a multi-stage centrifugal pump, the combination with a` casing having an even number of chambers in excess of two and communicating passages therebetween; of

balanced end thrusts under either plus or minus intake pressure on the first-acting'

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