US2216315A - Multiple unit double casing pump - Google Patents

Description

Oct. 1, 1940. A. HOLLANDER MULTIPLE UNIT DOUBLE CASING PUMP Filed Jan. 4, 1938. 2 Sheets-Sheet 1 Azaclar Hoflancier.

ATTORNEY Oct. 1, 1940. A. HOLLANDER MULTIPLE UNIT-DOUBLE CASING PUMP Filed Jan. 4, 1938 2 Sheets-Sheet 2 Azada; yozzanaer nvmwl.

INVENTOR ATTORNEY Egg Patented Oct. 1, 1940 UNITED STATES 2,216,315 MULTIPLE UNIT DOUBLE CASING PUMP Aladar Hollander, Los Angeles, Calif.,

assignor to Byron Jackson Co., Huntington Park, Calif., a corporationof Delaware Application January 4, 1938, Serial No. 183,298 6 Claims. (Cl. 103-108) This invention relates to improvements in multiple stage centrifugal pumps of the so-called double casing type such as are shown in my prior Patents Nos. 1,655,546 and 1,655,547 issued January 10, 1928 and No. 1,997,824 issued April 16, 1935.

Double casing pumps of the type shown in my prior patents are characterized by an axially split, multiple-stage inner or pump casing enclosed in an outer casing, the walls of the inner and outer casings being spaced apart to form a fluid receiving chamber, the inner or pump casing discharging into the space between the casings, and the outer casing being provided with a discharge outlet communicating with the space between the casings. This construction places the inner or pump casing under compression due to the discharge pressure being admitted to the space between the two casings. Consequently such pumps can be designed for high pressure work but do not require the usual thick heavy Walls that are ordinarily required for withstanding such high pressures. In fact, the walls of these pumps are extremely thin (about threeeighths of an inch in thickness) in pumps capable of developing several thousand pounds pressure per square inch.

In order to provide double casing pumps capable of producing higher pressures than those shown in my prior patents it has heretofore been customary merely to increase the number of stages in the inner or pump casing. I have found, however, that there are limits beyond which it is not practical to merely increase the number of stages. For pumps having axially split casings, the practical limit appears to be about twenty-two stages in a single casting because it is extremely difiicult if not impossible to obtain satisfactory castings and to machine the castings with satisfactory alignment when the number of stages exceeds this figure.

It is characteristic of pumps having axially split casings (unlike pumps having radially split casings) that the length of the casing castings increases with the number of stages. It is customary to assemble the two halves of the axially split casing without the use of a gasket. If a gasket were used it would have to be extremely thin and would be likely to blow out. Also, a thin gasket would be destroyed each time the pump were taken apart for inspection or repair. When the two halves of the casingare assembled without a gasket their meeting faces are ground and scraped to insure a fluid-tight fit. With thin walled casings of more than twenty-two stages it is not practical to use the metal to metal seal because of warpage and flexing. Neither is it practical to use a gasket. Nor'is it practical to employ radially split casings, because a multistage pump of this type is too diflicult to assemble and disassemble and is diflicult to balance hy-' draulically.

The object of the present invention is to provide a construction for double casing, multiple stage pumps of the axially split inner casing type whereby the number of stages can be increased to any desired number without requiring pattern equipment for each size of pump and without materially complicating the casting or machining practice such as is used for pumps of a lesser number of stages.

Another object is to provide a multi-stage, double casing pump of the axially split inner casing type wherein the pump is made up of a plurality of separate units comprising a relatively few number of stages in a single outer case.

Another object is to provide a multi-stage, double casing pump of the axially split inner casing type having a plurality of separate pumping units in a single outer case and wherein at least one of the pumping units is a standard unit such as is used in a double casing pump having only one pumping unit.

Another object is to provide a multistage, double casing pump of the axially split inner casing type having a plurality of separate pumping units in a single outer case and wherein a relatively few types of special units can be combined to make a large number of different total pump stages.

Figure 1 illustrates a side view of the invention.

Figures 2 and 2A illustrate an enlarged sectional view through the shaft axis of a double casing, multi-stage centrifugal pump shown in Fig. 1, Figure 2 showing the upper portion of the pump and Figure 2A showing the lower por- Figure 3 is a cross section of the pump shown in Figs. 2 and 2A taken on line 3-3 of Fig. 2A.

The numeral l indicates a tubular seamless steel casing which forms the outer or higher pressure casing of my pump. The inner or pump volute casing is shown at 2 and 3. The view shown in Fig. 2 is taken on the parting face of the inner casings 2 and 3. The outer casing I is closed at its lower end and is spaced from the inner casing to provide a fluid chamber 5 between the inner and outer casings. The outer casing l is provided at its upper end with a flange 1 to which the nozzle head 9 is attached by bolts I II. The nozzle head 9 is provided with a laterally extending suction nozzle l2 whic communicates with the inlet to the first stage impeller at the upper end of the inner casing 2. Nozzle head 9 is also provided with a laterally extending discharge nozzle l3 which communicates with the space 5 between the inner and outer casings. Nozzle head 9 is also provided with a stuffing box I 5 motor support 16 is bolted to the top of the nozzle through which the pump shaft extends. A-

head 8. The motor shaft is indicated at H and is connected to the pump shaft 18 by means of a coupling IS.

The inner or pump casing is made up of a number of sections or pump units bolted together, each unit being a complete multi-stage pump. The drawing shows a pump made up of two units. The lower unit 3 may be either a duplicate of the upper pump unit or it may be a standard type of .pump having an axially split casing which may have any number of stages up to 22, which is the present practical limit for a single pump. These standard pump units are each preferably substantially balanced hydraulically. In the present instance the pump unit 3 is, hydraulically substantially balanced by arranging the impellers in two opposed groups. The upper group of impellers (of which the topmost 20 is the suction entrance to the pump unit 3) have their suction eyes facing upwardly while the lower group face downwardly. A throttle bearing 2| is interposed between the two opposed groups of impellers; and another throttle bearing 4| is placed at the lower end of the pump casing. The fluid passes serially through each group of impellers. The discharge from the lowermost of the upper impellers 22 is conducted through a channel 23 (formed in the meeting faces of the two halves of the casing 3) to the suction eye of the lower-most impeller 24 in the lower group. The fluid discharged from the last impeller 26 of the lower group passes out of the pump casing 3 through the discharge outlet 28 into the fluid chamber 5 between the inner and outer casings and thence out of the casing i through the discharge nozzle H3.

The upper pump unit 2 is of special design and is intended to be used with a standard lower unit similar to unit 3. To this end the upper unit '22 comprises a pair of axially split casings provided at their upper ends with a suction entrance 3d similar to the upper or suction end 32 of pump unit 3. Thus either of the pump units 2 or 3 can be bolted as shown at 33 to the nozzle head d which is of standard design. The pump unit 2 is a substantially balanced multi-stage pump, being balanced similarly to pump unit it by arranging the impellers in two opposed groups separated by a throttle bearing 3i. Fluid from the suction nozzle i2 enters the first stage impeller 31d and proceeds downwardly serially through the upper group of impellers to the center of the pump, thence through channel 35 to the lowermost im peller t5, upwar through the lower group of impellers in series, and thence downwardly through channel ill to the suction inlet 32 to the lower pumping unit 3. The lower end of pump casing 2 is provided with a throttle bearing 3&3. The upper and lower pump units are bolted together as shown at 3%.

In the drawings the pump shaft is is a single shaft extending through both of the pump units 2 and 3. Separate shafts for each pump unit could be used but it would then be necessary to couple the shafts together where the two units are jointed together. The use of a single shaft is much to be preferred. Because each of the pump units is substantially balanced in itself there will be theoretically no hydraulic thrust to be carried by the motor.

If it is desired to have more than forty-four stages in the pump I employ two or more special sections similar to the upper pump unit 2 (although rwo or more special sections may be used with a lesser number of stages.) Because both ends of the special units 2 are identical and because each unit is substantially balanced hydraulically they can be connected together in any order and in any desired number, within practical limits. It would be possible to have each oi the separate pump units unbalanced with unbalance equal but in opposite directions in each unit so that the pump as a whole would be balanced. However, such an arrangement would not have the practical advantages of the arrangement shown in the drawings. Also any of the well known balancing devices could be used but are not necessary with the design shown in thedrawmgs.

I may provide a centering pin 40 for centering, and, if desired, for partly supporting the inner casings while the pump is being shipped. The pin 40 is shown in axial alignment with and supporting the pump end bearing 4 i.

For very high pressure pumps I may also. provide means for relieving the hydraulic thrust against the lower end of the shaft Hi. This is accomplished by venting the throttle bearing ii back to a lower pump stage through the line 43.

By making use of the construction described above I can build special service pumps having any desired number of stages. This is accomplished without the necessity of having diiferent pattern equipment for each pump. The motor support, nozzle head and lowermost pump unit are standard lower pressure equipment. The outer casing is seamless steel casing which is obtainable in any desired length and diameter. Thus the only special parts are the special upper pump units 2 and only a few sizes and numbers of stages of these special units are needed in order to make a large number of combinations with the standard lower units. For example, the standard lower units are regularly made in even numbered groups of four to twenty-two impellers and in sizes of suction inlets of 1 3" and 4". The special units are preferably made in units of sixteen stages in the same three sizes. Thus a pump for delivering 25 gallons per minute against a pressure of approximately 1,000 lbs. may consist of a standard 1 /2" twenty-two stage lower unit and two identical sixteen stage upper units.

The above described construction has the further advantage of requiring no complicated pattern equipment for a pump having a large number of stages. Also, the casting and machining operations are made as simple as for a pump having relatively few stages.

I claim:

1. In a multi-stage centrifugal pump, a supporting means having an inlet and an outlet therein, a substantially hydraulically balanced multi-stage centrifugal pump unit having an axially split casing mounted on said support with an inlet in one end thereof in communication with the inlet in said support and having an outlet in the opposite end thereof, a second substantially hydraulically balanced multi-stage centrifugal pump unit having an axially split casing secured to and supported by the discharge and of said first pump unit with an inlet in one end thereof communicating with the outlet from said first pump unit, an outer casing secured to said supporting means and enclosing said pump units in spaced relation thereto providing a fluid pressure chamber between said pump units and the outer casing in communication with the outlet in said supporting means, and a discharge opening from said second pump unit communicating with said fluid pressure chamber.

2. In a vertical multi-stage centrifugal pump, a supporting means having an inlet through the center-thereof, a substantially hydraulically balanced multi-stage centrifugal pump unit having an axially split inner casing mounted on said supporting means with its inlet in registry with the inlet through said supporting means and having a discharge outlet in the opposite end thereof, said discharge end being symmetrical with the inlet end of said supporting means, a second substantially hydraulically balanced multi-stage centrifugal pump unit having an axially split inner casing mounted on and supported by the discharge end of said first pump unit with its inlet in registry with the outlet therefrom, a single shaft for both pump units extending through the supporting means, a bearing for the other end of said shaft carried by the distal end of said second pump unit, an outer casing mounted on said supporting means in circumferentially spaced relation to said pump units, said outer casing being free from contact with said pump units, a discharge outlet from said second pump unit communicating with the space between the pump units and the outer casing, and a discharge outlet through said supporting means communicating with said space.

3. In a vertical multi-stage centrifugal pump, a supporting member having a suction inlet therein, a substantially hydraulically balanced axially split multi-stage pump having an inlet at one end and a symmetrical outlet at the opposite end mounted on said supportingmember with its pump inlet in registry with the inlet through said supporting member, a second substantially hydraulically balanced, axially split multi-stage pump having a suction inlet at one end adapted to register with the outlet from said first pump and adapted to be mounted thereon and be supported thereby, a single shaft for both pumps having one end extending through said supporting member and provided at its other end with a bearing carried by the distal end of said second pump, an outer casing mounted on said supporting member in circumferentially spaced relation to said pumps, and being free from contact therewith, a discharge outlet from said second pump communicating with the space between the outer casing and said pumps, and a discharge outlet through said supporting member communicating with said space.

4. In a vertical, multi-stage centrifugal pump, a supporting member having a suction inlet therein, a first substantially hydraulically balanced multistage pump having an axially split casing with an inlet at one end and an outlet at its opposite end symmetrical with said inlet, said pump being mounted on said supporting member with its inlet in registry with the inlet through said supporting member, the impellers in said pump being arranged in two opposed groups, the group adjacent the inlet having their suction eyes facing toward said inlet and the opposed group having their suction eyes facing in the opposite direction, a throttle bearing between the two groups of impellers, a second substantially hydraulically balanced multi-stage pump having an axially split casing with an inlet at one end adapted to be mounted on and register with the outlet from said first pump, a throttle bearing between the inlet of the second pump and the adjacent group of impellers of the first pump. said second pump having the impellers therein arranged in two opposed groups, the group adjacent the inlet end having their suction eyes fac- 5 ing toward said inlet and the opposed group having their suction eyes facing in the opposite direction, a single shaft for both pumps having one end extending through said supporting member and having its other end terminating within said 10 second pump casing at the distal end thereof, a throttle bearing about said shaft between the two opposed groups -of impellers, another throttle bearing in the distal end of said second pump casing and defining therewith a substantially l5 closed chamber for the end of said shaft, and means for venting the pressure from said chamber back to a lower pump stage.

5. In a multi-stage centrifugal pump, a supporting means having a substantially centrally 20 disposed suction inlet opening therein, a substantially hydraulically balanced multi-stage centrifugal pump unit having an axially split casing mounted on said support with a suction inlet in one end thereof in communication with the inlet 25 opening in said supporting means and having a discharge outlet at the opposite end substantially coaxial with said suction inlet, a second substantially hydraulically balanced multi-stage centrifugal pump unit having an axially split casing 80 supported by the discharge end of said first pump unit and having a suction inlet registering with the discharge outlet from said first pump unit, impeller shafting extending through said inlet opening in said supporting means in substantially 85 coaxial relation thereto and extending into said pump units, impellers on said shafting, an outer casing secured to said supporting means and enclosing said pump units in spaced relation thereto providing a fluid pressure chamber between said outer casing and said pump units, a discharge opening from said second pump unit to said fluid pressure chamber, and a discharge outlet from said outer casing communicating with said fluid pressure chamber.

6. In a multiple stage centrifugal pump of the double casing type, a supporting means having an inlet opening therein, a plurality of multi-stage pump units having axially split inner pump casings connected end to end and connected at one end to said supporting means with the suction inlet of the first unit in registery with the inlet opening in said supporting means, each pump unit being substantially hydraulically balanced by means of opposed groups of impellers and having a throttle bearing between each of the opposed impeller groups and at the distal end of each pump unit, a fluid cross-over channel formed in the parting faces of each of said casings between the opposed groups of impellers therein, a fluid channel formed in the parting faces of each of said casings leading from the final stage of each of said pump units except the last to the distal end thereof, an outer casing secured to said supporting means and enclosing said units in circumferentially spaced relation thereto, a fluid channel leading from the final stage of said last unit to the space between said outer casing and said units, and a discharge outlet from said outer casing communicating with the space between said outer casing and said units.

ALADAR HOILANDER.

czzn'mmcym or conmzonon. Patent No. 2,216,515. October 1, who.

' ALADAR HOLLANDER- It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, first column, line 18, claim 2, after the word "units" insert --having one end";-

and that the said Letters Patent should be read with this correction therein that the 'same may conform to the record of the case in the Patent Office.

Signed and sealed this 12th day of Novanber, A. D. 1911.0.

Henry Van Arsdele Acting Comnis sioner of Patents.

Images