US2764943A - Pump system - Google Patents

Description

A. W. PETERS Oct. 2, 1956 PUMP SYSTEM Filed Oct. 13, 1951 bustion Corporation, Toledo, Ohio Application October 13, 1951, Serial No. 251,185 Claims. (Cl. 103-87) Ohio, a corporation of This invention relates to an improved pump system for transmitting liquids.

When it is desired to move special liquids which are sensitive chemically to components of the atmosphere, or which are labile, chemically unstable, and the like and hence are deleteriously alfected by loss of a vapor constituent or decomposition product therefrom, the problem of providing means for pumping such a liquid has been so difficult of solution as to discourage use of such liquids. Typical examples of the character of liquids referred to are heat transfer liquids such as tetra-arylsilicate, liquid metals and low melting alloys or liquified gases most of which are extremely sensitive to oxygen containing gases such as air, water vapor and carbon dioxide, especially when in contact with the liquid at elevated temperatures. Some liquids are adversely affected by such gases only at elevated temperatures; some liquids such as petroleum products are deleteriously affected by loss of a component in equilibrium at elevated temperatures, which loss upsets or shifts such equilibrium; and some liquids contain phenol which, if lost from the system, is toxic to humans, thus must be contained for that reason. The present invention provides a relatively simple solution to the problem of pumping such liquids, utilizing a hermetically sealed motor and pump having no turning shaft seals exposed to the atmosphere.

For a consideration of what I believe to be novel and my invention, attention is directed to the following specification and the drawing and concluding claims thereof.

In the drawing:

Fig. l is a partially sectional view of a motor and pump according to this invention.

Fig. 2 is a sectional view of Fig. 1 taken on line 2-2 thereof.

Fig. 3 illustrates a modified form of the motor of Pi 1.

lig. 4 is a substantially schematic diagram of a complete pump system.

A motor is totally enclosed in a gas tight, hermetically sealed, casing having sealed wire leads 13 to the motor. The drive shaft 15 of the motor is enclosed at its upper end, and its lower or drive end is surrounded by a cylindrical casing 16 which is hermetically sealed to the casing of the motor proper, and secured thereto by bolts 14. The casing 16 is hermetically sealed and secured by bolts 17 to a plate 20 which forms the upper flange of a partially water cooled, hermetically sealed, shaft housing 21. The plate 20 is welded to a bearing support member 22 having a labrynth type seal 23 bolted to the top thereof. An extension shaft 25 is secured to drive shaft 15 by coupling 24 and is supported in the shaft housing by upper bearing 26 of the anti-friction type. The housing 21 comprises concentric upper cylinders 27 and 28 forming with the upper bearing support member 22 and a lower endwall 30 a water chamber which closely surrounds the extension shaft 25 and has water inlet and outlet pipes 18 and 19 supplying cooling water thereto. A cylindrical shell 31 forms the lower portion of the shaft housing 21 which shell is welded to an end plate 32 which in turn supports upper and lower portions 33 and 34 of a pump impeller housing. The extension shaft 25 is supported at its lower end in a sleeve type bearing 35 which is adapted to be lubricated by the liquid being pumped, the bearing 35 being supported in the upper portion 33 of the impeller housing. The pump further comprises an impeller 36 disposed in the housing and secured to the shaft extension 25 by a retaining nut 37. The upper and lower portions 34 and 35, respectively, form outlet and inlet ports 40 and 41 for said impeller housing.

When it is desirable to utilize an ordinary motor 9, instead of one comprising a hermetically sealed motor caslng, to drive the impeller of the pump, a watercooled casing 42 is disposed about the motor and hermetically sealed to the cylindrical casing 16 as in Fig. 3 thus providing means for dissipating the heat generated by the motor 9 as well as hermetically sealing the motor to the liquid-vapor system prevailing about the extension shaft 25. The water outlet pipe 19 from the shaft housing leads to the water cooled casing 42 for the motor 9, from which cooling water is exhausted through pipe 43.

In operation, the liquid is maintained at a level in the shaft housing 21 intermediate the impeller 36 and the water cooled portion of the flow of vapor past the inner portion of the housing the shaft 25. It is thus possible to maintain the motor 10 in a relatively cool environment where even phenol or other vapors from the attack the parts of the motor 10. A liquid drain 45 and a vapor line 46 are connected to a liquid circulation system in a way to maintain a liquid level therebetween, thus assuring submerged operation of the impeller 36 and its wet sleeve type bearing 35 for lubrication thereof, and also assuring the maintenance of a dry vapor space between the shaft 25 and the inner shell 27 of the water cooled portion, often called a water wall, of the shaft housing.

The pump outlet 40 is connected by a pipe 50 to a liquid heater wherein the liquid is brought to the desired temperature, and the liquid passes from the heater to a heat exchanger by pipe 51 where useful heat is extracted from the liquid. Liquid from the heat exchanger passes through a pipe 52 to the intake 41 of the pump housing. The drain pipe 45 is connected between the shell 31 below the liquid level therein and the pipe 52 to return to said pipe the small amount of liquid which flows past the bearing 35. The vapor line 46 connects the vapor space within the shell 31 to a vapor space in the surge tank, thus the liquid level is maintained below the vapor line 46 and above the bearing 35, which bearing is kept lubricated by the small fiow of liquid there through. The length of the shell 31 between the vapor line 46 and the liquid line 45, and the capacity of the surge tank, are chosen to maintain the desired liquid level during all cycles of operation of the system.

To initially fill the pump system with liquid, the system is first purged with a dry inert gas by circulating such gas through the system before adding liquid. This may be done in the usual way by connecting a gas supply pipe to the system at one point, such as the surge tank, and venting gas from another point, such as the motor housing, until substantially uncontaminated purge gas is vented. Then the liquid is added, usually cold, to the system until it is filled, usually being added initially at the surge tank and passing into the system by operating the pump at the lowest possible liquid temperatures until the system is properly full and the pump is full of liquid to a level between vapor line 46 and liquid line 45 as above discussed. The system is then sealed and put into operation.

shell 27 of the water cooled housing so that only a small could carry heat upwards along liquid below will not seriously- When tetra-arysilicate, for example, is utilized as a heat transfer liquid in the system herein disclosed it may safely be operated for extended periods of time at 600 to 650 F. without oxidation and chemical deterioration of the liquid, formation of gum deposits and the like, due to the influx of atmospheric air, and no loss of phenol due to outward leaks from the system with the usual deterioration of the liquid therefrom. This liquid has been operated at 600 F. for over 2800 hours constant operation Without noticeable deterioration of any kind, and this pump system was thereby instrumental in determining more accurately the safe upper operating temperature of said liquid, and at a temperature well above that indicated as the top safe operating temperature by known experience.

It is an important feature of this invention that the impeller of the pump is driven by shaft and motor which are totally enclosed in and hermetically sealed in the liquid-vapor system of the liquid being pumped, thus utilizing no packing glands or shaft seals to seal the liquid in the system, and providing a trouble free system that is well suited to its intended purpose.

What I claim is:

1. Apparatus for pumping a hot liquid which is chemically sensitive to components of the atmosphere, comprising: a motor having a hermetically sealed motor housing except for an elongated shaft driven at one end by said motor; an impeller attached to the other end of said shaft, said impeller being located below said motor; an impeller housing enclosing said impeller and having an inlet and an outlet; a casing surrounding said shaft and hermetically sealed to said motor housing and said impeller housing; a tube adjacent an upper portion of said shaft and connected to said casing by upper and lower partitions to form about said portion a water cooled chamber; a coolant inlet and outlet for said chamber; a liquid chamber between said impeller housing and said lower partition and defined by the lower portion of said casing; a sleeve bearing for said shaft through which a portion of said lqiuid flows, for lubrication,- from said impeller housing to said liquid chamber; and means for maintaining the level of liquid in said liquid chamber.

2. The apparatus according to claim 1 wherein said means for maintaining the level of liquid in said chamber comprises a surge tank containing liquid whose level is equal to the level desired in said liquid chamber; said surge tank being connected to said impeller housing inlet; and a pipe connnecting said casing below the level of liquid therein to the inlet of said impeller housing.

3. Apparatus according to claim 2 and comprising a vapor vent above the liquid level in said liquid chamber connected to said surge tank above the level of liquid therein.

4. Apparatus for pumping a hot liquid which is chemically sensitive to components of the atmophere, which apparatus comprises, in combination: an impeller; an impeller housing for said impeller and having an inlet and an outlet for the liquid to be pumped; a generally vertical drive shaft above the impeller and connected thereto to turn the same; a motor above the impeller and connected to said drive shaft to turn the same; a hermetically sealed casing encompassing said motor and said shaft, extending and hermetically sealed to said housing; wall means forming an internally cooled chamber which closely surrounds and cools at least a portion of said shaft between said motor and said impeller; a gas substantially inert to said motor and said hot liquid, located in the volume defined by said casing and above said housing; coolant conduit means for delivering coolant to and from said chamber; liquid conduit means for conducting liquid to and from said housing in a liquid flow system; a surge tank for liquid in said flow system and having a liquid level therein between the levels of said internally cooled chamber and said impeller; and a vapor conduit connecting said surge tank above said liquid level therein to said casing between said internally cooled chamber and said impeller.

5. Apparatus according to claim 4 and comprising: a submerged sleeve bearing below said chamber and an anti-friction bearing above said chamber for supporting the shaft concentrically within the chamber walls, said surge tank being disposed relative to said casing to maintain the liquid level therein between said sleeve bearing and said chamber whereby hot liquid is prevented from passing between said shaft and the walls of said cooling chamber.

References Cited in the file of this patent UNITED STATES PATENTS 1,428,238 Keating Sept. 5, 1922 1,472,560 Griffiths et al. Oct. 30, 1923 1,877,762 Griswold Sept. 10, 1932 2,075,895 Harmon Apr. 6, 1937 2,130,583 Fosnot Sept. 20, 1938 2,277,333 Leopold Mar. 24, 1942 2,667,127 Rimann Jan. 26, 1954 FOREIGN PATENTS 57,567 Denmark May 6, 1940 628,346 Great Britain Aug. 26, 1949 813,006 France May 25, 1937

Images