US2951165A - Heat exchanger for submergible pumping assembly - Google Patents

Description

Aug. 30, 1960 A. ARUTUNOFF HEAT EXCHANGER FOR SUBMERGIBLE PUMPING ASSEMBLY Filed Aug. 8, 1957 FIG? WELI FLIII D ,7

INVENTOR ARMA/S ARUTUNOFF MOTOR HEAT EXGHANGER ATTORNEY WILL LUID United States Fatent fice 2,951,165 Patented Aug. 30, 1960 HEAT EXCHANGER FOR SUBMERGIBLE PUMPING ASSEMBLY Armais Arutunotf, Bartlesville, kla., assignor to Reda Pump Company, Bartlesville, Okla, a corporation of Delaware Filed Aug. 8, 1957, Ser. No. 677,099

8 Claims. (Cl. 310-54) This invention relates to a heat exchanger for a submergible electric motor driven pump assembly and consists more particularly in new and useful improvements in a heat exchange unit adapted to be coaxially connected to a submergible electric motor unit, whereby the heated lubricating and protecting fluid from the motor unit may be circulated in heat exchange relation to a flowing body of the surrounding well fluid.

In the operation of pumps driven by submergible electric motors, it is important to maintain the motor, bearings and other working parts at the lowest practicable operating temperature. The temperatures to be contended with are normally the sum of the temperature developed by the motor itself and that of the fluid to be pumped and in which the motor is submerged. Thus, if the operating temperature normally developed by the motor is 100 F. and that of the fluid to be pumped is 100 F., the hot spo temperature inside of the motor becomes 200 F.

In very deep oil Wells, the bottom hole temperature is often as. high as 240 F. With a motor having a temperature rise to 100 F. and employing no additional cooling means, the pumping of oil from such a well would result in the development of a motor temperature of 340 F. Obviously, the life of the electrical of the working parts. means to minimize the temperature rise in the motor. For example, if the cooling surface coursed by the fluid pumped, is increased five times, then the temperature rise would be of the order of 20 F. and the hot spot temperature in the motor would be 260 F.-whicl1 the normal materials of the motor and parts can stand indefinitely.

insulation as well as that of all If the increase in cooling surface is obtained by in- Y creasing the height of the motor housing, the motor length would become impracticable. For example, a motor with 15 feet of active iron would have to be increased to 75 feet of housing length to accomplish this result. Obviously, with deep well pumps, where the length of the equipment is already great, it is important to concentrate the available cooling surfaces within a minimum of longitudinal extent and with the present invention, the required effective cooling surface may be obtained within a fraction of the length that would otherwise be required.

To this end, it is the object of this invention to provide a heat exchange arrangement in the base of a submergible motor driven pump assembly which utilizes the well fluid as the cooling medium and distributes the same in heat exchange relation with the heated oil fromthe motor, over a plurality of contact surfaces confined Within limited longitudinal boundaries.

Another object of theinvention is to provide a heat exchange base unit for deep Well pump assemblies, comprising a series of concentric, annular passageways alternately arranged to accommodate the reverse flow of the well fluid and the heated oil from the motor, respectively.

such temperatures would shorten It is desirable to provide some A further object of the invention is to provide in a heat exchange system of this character, centrifugal means associated with this motor shaft, to facilitate the circulation of the motor lubricating and protecting fluid through a series of concentric annular passageways in heat exchange relation to a body of well fluid flowing through alternate passageways.

With the above and other objects in view which will appear as the description proceeds, the invention consists in the novel features herein set forth, illustrated in the accompanying drawings and more particularly pointed out in the appended claims.

Referring to the drawings in which numerals of like character designate similar parts throughout both views,

Figure l is a side elevational view of a motor and pump assembly including the heat exchange unit of the present invention, and

Figure 2 is an enlarged view, partly in section, illustrating the heat exchange unit.

In Figure l of the drawings, where the entire assembly is shown, 3 represents a conventional centrifugal pump unit, the casing of which is threaded at its upper end as at 4, for connection to a conventional well tubing. An oil filled motor unit 5 is concentrically connected by any suitable means to the lower end of the pump unit 3 with the motor shaft coupled to the pump shaft in the usual manner. A heat exchange unit 6 is concentrically connected to the lower end of the motor unit 5 and forms the lowermost or bottom unit of the assembly.

As best seen in Figure 2, the heat exchange unit 6 comprises a cylindrical housing 7 which is concentrically connected to the housing of the motor unit 5 by a coupling head 8 provided with annular recesses 9 and 10 for receiving the adjacent ends of the housing of the: motor unit 5 and the heat exchange unit 6, respectively. The coupling head 8 is provided with annular recesses: 9 and 10 for receiving the adjacent ends of the housing of the motor unit 5 and the heat exchange unit 6, respectively. The coupling head 8 is preferably formed of an integral casting which is centrally recessed as at 11 to receive a thrust bearing assembly 12 supporting the lower end of the motor shaft 13. The motor shaft 13 is provided with a longitudinally extending central bore 14, communicating with one or more radial ports 15 for causing a centrifugal circulation of the oil with which the motor unit and reservoir are initially charged, the lower end of said bore opening into the housing 7 of unit 6 through the coupling head 8, as will later appear.

The bottom of the housing 7 is closed by a base member 16, retained in place in the housing by a closure ring 17, the latter being annularly grooved as at 18 to receive the housing 7 and at 19 to provide a shoulder for supporting the bottom of the base 16.

Extending longitudinally between the head 8 and the base 16, are a plurality of concentric tubular sleeves 20 to 23 inclusive, nested in the housing 7 and preferably of progressively increasing length from the central sleeve or tube 20, outwardly. In the form of the invention shown in the drawings, these sleeves are respectively supported at opposite ends by step-shaped shoulders 20a to 23a formed on the opposed faces. of the head 8 and the base 16.

The outermost sleeve 23 together with the housing 7, forms an annular passageway A, the upper end of which communicates with the interior of the housing of the motor unit 5 through a port 24 in the head 8 and its lower end is connected by a transverse port 25, to a central well 26, formed in the base 16. The well 26 in turn,

opens into a vertical passageway E formed solely by the central sleeve 20 which, through an opening 27 in the Outer sleeve 23 just referred to, define the walls of a second annular passageway B, the lower end of which communicates with the exterior of the housing 7 through a port or ports 28 drilled in the base member 16, its upper end being connected by a port or ports 29 with a discharge passageway 30 in head 8, leading to the area surrounding the housing 7 at the upper end of the latter. The next inwardly spaced sleeve 21, together with the sleeve 22, forms a third annular passageway C which, as in the case of passageway A communicates with the interior of the motor housing through a port 31 provided in the head 8 and at its lower end it is connected by a transverse port 32 in the base 16, with the central well 26 and passageway E. The central tube 20 together with the sleeve 21, forms a fourth annular passageway D connected by a port 33 in base 16, with the exterior of the housing 7 and through a port 34 at its upper end, with the discharge opening 30 leading to the exterior at the upper end of the housing 7.

The entire assembly is submerged in an oil well or the like and the centrifugal pump 3 draws the surrounding well fluid upwardly as shown by the arrows in Figure 1,

into the inlet ports 35 of the pump unit from whence it flows through the tubing (not shown) attached to the upper end of the pump unit 3. This upward flow of well fluid in'the well, causes a corresponding flow of some of such fluid through'the passageways B and D from their respective inlet openings 28 and 33, returning it to the well through the discharge opening 30. Simultaneously, the rotation of the motor shaft 13, through the centrifugal action of the radial port or ports 15, causes a circulation of the oil in the motor housing, down through the ports 24 and 31 and the alternate passageways A and C for return to the motor housing through ports 25 and 32 and the common return passageway E. Thus, there is effected a counter current flow and heat exchange between the upwardly traveling well fluid and the circulating motor protecting and lubricating fluid passing through the alternate passageways.

It will be apparent that by thus increasing the cooling surface over which the pumped fluid travels, the operating temperature of the motor is proportionately reduced.

Furthermore, the increase of the cooling surface through the use of the series of concentric annuli as described, is of especial advantage not only in minimizing the overall longitudinal extent of the apparatus, but in greatly facilitating the cleaning and assembly of the various parts. Furthermore, this arrangement of concentric annuli affords a marked increase in mechanical strength.

From the foregoing it is believed that the invention may be readily understood by those skilled in the art without further description, it being borne in mind that numerous changes may be made in the details disclosed, without,

departing from the spirit of the invention as set forthin the following claims. 1

I claim: 1 p

1. In an oil filled submergible electric motor driven pump assembly, including a motor unit; a heat exchange reservoir unit forming the base of said motor unit and comprising an elongated cylindrical housing closed at its lower end, a central vertical tube in said housing, closed at its lower end and communicating at its upperend with the in-terior'of said motor unit, at least two concentric elongated annular conduits having common dividing walls, coaxially surrounding said central tube, one of said-conduits having an oil inlet from said motor unit at its upper end and an oil outlet to said central tube at its lower end, the other of said conduits defining an uninterrupted, unidirectional path and having a fluid inlet for the surrounding well fluid at its lower end and a fluid outlet to said well at its upper end, and means in saidmotorunit 2. In an oil filled submergible electric motor driven pump assembly, including a motor unit having a vertical motor shaft, with a longitudinally extending oil conducting bore therein; a heat exchange reservoir unit forming the base of said motor unit and comprising an elongated cylindrical housing closed at its lower end, a central vertical tube in said housing closed at its lower end and communicating at its upper end with said shaft bore, at least two concentric annular conduits having common dividing walls, coaxially surrounding said central tube, one of said conduits having an oil inlet from said motor unit at its upper end and an oil outlet to said central tube at its lower end, the other of said conduits defining an uninterrupted, uni-directional path and having a fluid inlet for the surrounding well fluid at its lower end and a fluid outlet to said well at its upper end, and means associated with said motor shaft for circulating oil from said motor unit through said one conduit and central tube and back to said motor unit, in heat exchange relation to the well fluid coursing through said other conduit.

3; In an oil filled submergible motor driven pump assembly, including a motor unit having a vertical motor shaft with a longitudinally extending oil conducting bore therein; a heat exchange reservoir unit forming the base of said motor unit and comprising an elongated cylindrical housing, a manifold head connecting the upper end of said housing to the lower end of said motor unit,

I a manifold base closing the lower end of said housing,

'head and an outlet to said central tube through said base,

the other of said passageways having a fluid inlet through said base for'the surrounding well fluid and a fluid outlet to said well through said head, and means associated with said motor shaft for circulating oil from said motor unit through said one passageway and central tube and back to said motor unit, in heat exchange relation to the well fluid coursing through said other passageway.

4. An oil filled submergible electric motor driven pump assembly as claimed in claim 3, wherein said manifold head forms a base support for said motor shaft.

5, An assembly as claimed in claim 3, including a thrust bearing for the lower end of said motor shaft, said manifold head forming a base support for said thrust bearing.

6. An assembly as claimed in claim 5, wherein said manifold head and manifold base are multistepshaped in cross section to provide annular mounting shoulders for the respective upper and lower ends of said tube and sleeves.

7. An assembly as claimed in claim 5, wherein said manifold head and manifold base are multi-step-shaped in cross section to provide annular mounting shoulders for the respective upper and lower ends of said sleeves, said base being removably secured in said housing to facilitate the assembly and removal of said sleeves and tube.

8. In an oil filled submergible motor driven pump assembly, including a motor unit having a vertical motor shaft with a longitudinally extending oil conducting bore therein; a heat exchange reservoir unit forming the base of said motor unit and comprising an elongated cylindrical housing closed at its lower end, a central vertical tube in said housing closed at its lower end and communioating at its upper end with said shaft bore, at least ,two concentric annular sleeves coaxially surrounding said central tube to form uninterrupted, uni-directional. annular passageways, one of said passageways having an 5 6 oil inlet from said motor unit at its upper end and an References Cited in the file of this patent oil outlet to said central tube at its lower end, the other of said passageways having a fluid inlet for the surround- UNITED STATES PATENTS ing well fluid at its lower end and a fluid outlet to said 1,657,900 Richter I an. 31, 1928 well at its upper end, and at least one radial port in 5 2,283,118 Arutunoff May 12, 1942 said shaft communicating with said central bore for 2,735,026 Moerk Feb. 14, 1956 aifecting a centrifugal action to circulate oil from said motor unit, through said one passageway and central tube and back to said motor unit, in heat exchange rela- FOREIGN PATENTS tion to well fluid coursing through said other passageway. 10 1,059,539 France N 10, 1953

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