US1941442A - Multistage centrifugal pump - Google Patents

Description

Dec., 26, 1933. D. J. MoRAN ET AL Y MULTISTAGE CENTRIFUGAL PUMP Filed Feb. 9. 1933 Patented Dec. 26, 1933 PATENT ,o1-Flos 1,941,442 l f' MULTISTAGE CENTRIFUGAL PUMP Daniel J. Moran and Edwin 0. Bennett, Ponca l City, kla., assignors to Continental Oil -Company, Ponca City, Okla., a corporation of Dela- Ware Application February 9, 1933. Serial No. 655,926

2 Claims. (Cl. 10S-109) Our invention relates to multi-stage centrifugal pumps and more particularly to a balanced centrifugal pump construction.

The customary design for centrifugal Vpumps is one in which the stages are placed in series along the shaft with the low pressure or intake stage at one end and the high pressure or discharge stage at the other end. The disadvantage inherent in this design is that the axial thrust is in one direction. The hydraulic unbalance of this type of construction requires special balancing disks or cylinders on the shaft. Sometimes specially designed thrust bearings are used in order to hold the rotating elements in their correct spatial relation to the stationary parts. y

Where many stages are used, the outlet or discharge pressure is usually very high. This necessitates the packing of the discharge end against atmospheric pressure. The high pressure within the pump tends to promote leakage. In' order to preclude the escape of the fluid being pumped, it is necessary to keep the discharge end stuiiing box extremely tight especially when volatile liquids are used. This creates friction and entails power losses. The result is that the operating 'emciency is lowered.

Our invention contemplates a multi-stage centrifugal pump design in which the number of stages is odd. While we prefer to use an odd number of stages, it is to be remembered that an even number of stages can be used within thespirit of our invention. We propose with an odd number of stages to split the first stage. The remaining impellers are divided into two groups and placed along the shaft in back to back relationship. Each section of the split stage has one half the volume capacity of one of the remaining stages of the pump.

In the accompanying drawing which forms part of the instant specification and which is t0 be read in conjunction therewith, and in which\ like reference numerals are used to indicate like parts in the various views;

Figure 1 shows a diagrammatic sectional elevation of a pump embodying one mode of carrying out our invention.

Figure 2 is a sectional view taken on the line 2-2 of Figure 1.

Figure 3 is a sectional view taken on the line 3 3 of Figure 1.

More particularly referring now to the draw-a ing, a shaft l is mounted for rotation within a suiti able casing or housing 2. A pair oi centrifugal impellers 3 and 3a are keyed to the shaft l by keys 4 and 5. The impellers 3 and 3a are dis- 13a from impeller 3a. It will be observed that 65 the capacity of impellers 3 and 3a is one half that i of the remaining impellers of the pump. The two stages 3 and 3a will handle a volume of iiuid equivalent to that handled by any one of the remaining stages of the pump. The fluid from the 79 two divided stages 3 and 3c passes from duct 13a to stage 10 of the pump, thence to stages 9 and 8 as can readily be seen by reference to Figure 1.- The fluid from stage 8 passes through duct 14 to stage 5 and thence through stages 6 and 'l as can be seen by reference to Figure l. It is to ybe remembered that stages 5, 6, and 7 are opposed to stages 8, 9, and 10 so that the thrust will be balanced. The iiow of the iiuid through the stages of each group is toward the center of the pump. 'f lIhe final stage 7 communicates with eduction tubing 15. The impellers may be of any suitable design and may be provided with blades 16 as can be seen by reference to Figure 2. The transfer lines 13 and 14 may be external of the pump if desired. Likewise, line 13 may be formed by a bore in the pump casing if it is desired. Y

It will be noted that our arrangement provides for an even number of impellers at all, times and that the ow through the pump is such that the thrust at the opposite ends of the pump equalize. This feature makes for a pump having a long life. The introduction of the iluid to the low pressure impellers and their disposition at the ends of the pump require that the stuing boxes 17 and-18 hold back only such pressure as is occasioned by the differential between the atmospheric pressure and that existing in the first stage. This is a great advantage as obviously this pressure will be much lower than that ex- 190 isting at the high pressure or discharge stage. 'l

If an even number of stages is used, we may introduce the liquid to one outboard stage, transfer it to the second outboard stage, and

then continue as shown. This method has the disadvantage of requiring a packing at one end which will withstand the pressure developed in the second stage which is considerably higher than that developed in the rst stage. This modification ci' our invention is not shown but it il@ The uuid to 6:0,-

is to be understood that it is Within the spirit thereof.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and sub-combinations. This is contemplated by and is within the scope of our claims. t is further obvious that various changes may be made in details Within the scope of our claims Without departing from the spirit of our invention. Xt is, therefore, to be understood that our invention is not to be limited to the specific details shown and described.

Having thus described our invention, what We claim is:

1. A multi-stage centrifugal pump having an odd number of stages and an even number of impellers, two of said impellers having half the capacity of the other impellers and being disposed at opposite ends of said pump, and means for splitting the induction fow of the liquid being pumped to said impellers of half capacity.

2. A multi-stage centrifugal pump comprising `stages on one side in combination a casing, n+1 centrifugal impeling stages, n+2 impellers, two of said impellers having half the capacity of the other impellers, said half capacity impeliers being disposed at the ends of the pump and adapted to form the rst stage, the other stages being distributed in the following manner:

of the center of said pump and NIB

stages opposed to the rst stages, means for dividing the induction iiuid to said first stage and the last stage of the pump being disposed near the central part thereof, wherein n is any even number.

DANIEL J. MORAN. EDWEN O. BENNETT.

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