US2240176A - Refrigeration - Google Patents

Description

April 29. 1941. 0Ns ETAL 2,240,176

REFRIGERATION Filed Oct. 20, 1937 INVENTOR Curtis 6. Coons- BY Rudolph 5. Nelson Patented Apr. 29, 1941 REFRIGERATION Curtis 0. Coons, North Canton, Ohio, and Rudolph S. Nelson, Larchmont, N. Y., assignors to The Hoover Company, North Canton, Ohio, a corporation of Ohio Application October 20, 1937, Serial No. 169,986

15 Claims.

This invention relates to pumping devices and more particularly to pumping devices of the character in which gas under pressure is introduced into a liquid to raise the same to a higher elevation. More specifically this invention relates to liquid elevating devices of the character in which a stream of liquid is divided into two connecting columns into which gas is introduced alternately for the purpose of elevating the liquid to a higher elevation.

It has been known previously to elevate a liquid by introducing gas thereinto; however, these prior devices have possessed the disadvantage that the liquid discharge was not continuous, the quantityiof'liquid elevated was limited by limitations of pipe size, and prior devices were not designed to utilize certain kinetic properties of the liquid being pumped as is the novel pump of this invention.

We have devised a gas operated pump which is more efiicient than previously known pumps, which provides for a constant liquid discharge if. desired, which will function simultaneously as a liquid elevating and dividing device, which utilizes eflectively an oscillating liquid column induced within the pump to aid in the pumping action, and which will provide for proportional division between the discharge of two connected liquid pumping columns.

The conventional gas lift pump is essentially a pulsating pump, and gas must be supplied under a pressure equivalent to the depth of immersion of the pump. Furthermore, the supply column of existing types of gas lift pumps is depressed into the body of liquid being pumped without performing any useful work. Our twin gas lift pump utilizes the depression of the liquid in one part of the pump to increase the elevating effect in another part of the pump and permits the gas to be supplied at a lower pressure to elevate liquid to a given height. With equal depth of immersion and pumping head the novel pump herein disclosed will elevate a greater quantity of liquid and with lower gas pressure than is pos-. sibie with gas lift pumps heretofore known.

It is known that an increase in the depth of immersion of a gas lift pump will increase its ca: pacity and elevating properties; however, this is accompanied by an increase in the pressure of the pumping gas. We have devised a unique structure in which certain kinetic properties of It is an object of this invention to provide a pumping device operated by a gas which will provide for a substantially constant discharge of the pumped fluid.

Still another object of the invention resides in the provision of a pumping device which will simultaneously elevate a fluid to a higher elevation and divide the same into a plurality of separate bodies.

Still another object of this invention resides in the provision of a pump which is particularly useful when incorporated within closed circuit, fluid systems.

Other objects and advantages of the invention will become apparent as the description proceeds when taken in connection with the accompanying drawing, in which- Figure 1 is a diagrammatic view illustrating our invention as applied to a continuous threefluid absorption refrigerating system.

Figure 2 is a view of our pumping device pe se drawn to an enlarged scale.

Figures 3 and 4 are views of our pumping device in operation and drawn to an intermediate scale.

Referring now to the drawing and first to Figure 1 thereof, it will be seen that we have diagrammatically illustrated our invention as applied to a continuous three-fluid absorption refrigerating system. As shown, the refrigerating system comprises a boiler B, an analyzer A, a condenser C, a pair of evaporators E and E, a pair of absorbers D and D, a gas circulating pump F driven by a motor M, a strong solution reservoir 30, a gas lift pump or impeller P for refrigerant liquid, and a gas lif-t'or pump impeller P for absorption liquid. These elements are connected together by suitable conduits to form various gas and liquidcircui-ts constituting a complete refrigerating system.

The system is suitably charged with a refrigerant, preferably ammonia, an absorbent for the refrigerant, preferably water, and an inert pressure equalizing medium, preferably a dense gas such as nitrogen. I

The boiler B is heated by any suitable device to generate refrigerant vapor from the solution therein contained. Refrigerant vapor and entrained absorption liquid pass upwardly through the analyzer Ain counterflow to strong liquor flowing downwardly therethrough. Substantially pure refrigerant vapor is conducted from the analyzer A byway of a conduit II which includes a rectifier R. into the condenser C. The rectifier R eliminates any vapor of absorption solution which may have passed through the analyzer A. The condenser C, which is preferably of a finned tubular air-cooled type, liquefies the refrigerant vapor which discharges therefrom through a conduit |2 into the elevating pump P.

Liquid supplied to the pump P is elevated through the arms l3 and I4 thereof into the evaporator sections E and E, respectively, through which it flows by gravity in countercurrent to a propelled stream of inert gas whereby refrigeration is produced by diffusion of the refrigerant vapor into the inert gas stream. The evaporator sections E and E are joined at their upper and lower ends by conduits l5 and I6, respectively. The inert gas refrigerant vapor mixture formed in the evaporator sections E and E .exits therefrom through the conduit |5 into the conduit which is connected by means of the conduits l8 and I9 to the lower ends of the absorbers D and D, respectively. The inert gas and refrigerant vapor passes upwardly through the absorbers D and D' counter to downwardly flowing streams of absorption solution whereby the refrigerant vapor is absorbed from the inert gas stream. The inert gas stream exits from the absorber sections D and D through conduits and 2|, respectively, which open into the suction inlet 22 of the inert gas circulating pump F. The inert gas discharges from the pump F under pressure through a conduit 23 which is in heat exchange relationship with the conduit l1 previously described and opens into the conduit I6 connecting the lower ends of the evaporator sections E and E.

The weak solution formed in the boiler B by the generation of refrigerant vapor exits therefrom through a conduit 24 which opens into the liquid circulating pump P. The absorption solution is elevated through the legs 25 and 26 of the pump P into the absorber sections D and D, respectively. The weak solution discharged into the absorber sections flows downwardly therethrough counter to the refrigerant vapor inert gas stream in a manner previously described. Absorption solution collecting in the lower end of the absorber sections D and D' is conveyed therefrom by conduits 21 and 28, respectively into the strong solution reservoir 30 from which it is returned to the analyzer A by way of a conduit 0 opens into an inverted U-shaped conduit 34 which communicates with the elevating conduits 25 and 26 below the liquid level therein whereby to elevate absorption liquid through the conduits 25 and 26.

The condenser C is provided with a suitable vent conduit 31 which conveys non-condensable gases to the rich gas conduit H. The condenser is also provided with an overflow conduit 38 connected to the rich liquor conduit 29 to prevent the pump or impeller P from being subjected to an excessive liquid supply head.

In view of the duplicate nature of certain parts of our pump, we prefer to designate the same a twin gas lift pump. This terminology seems particularly apt and well suited to distinguish the pump from prior types of gas lift pumps.

Our pump possesses particular advantages in systems in which it is desirable to divide the liquid as the elevating and dividing devices are then incorporated in a single simple mechanism. Preferably a relatively dense gas is supplied to the pump in order to reduce the size of the gas compressing mechanism; however, the pump works equally well with a dense gas like nitrogen or a light gas like hydrogen.

Referring now to the Figures 2 to 4 of the drawing, the pump or impeller mechanism will be described in detail. The pump will be described as a distinct unit in order to facilitate description, but it is to be understood that it is substantially identical with the pumps P and P described in connection with Figure 1. The pump comprises a U-shaped liquid conduit comprising right and left hand elevating conduits 4| and 42, respectively, connected at their lower ends by a transverse liquid conduit 43 which receives liquid to be pumped from any suitable source through a supply conduit 44. The elevating legs 4| and 42 are connected together by an inverted U-shaped conduit which opens into the legs 4| and 42 adjacent the lower portions thereof; that is, at a point below the normal liquid level prevailing in the conduits 4| and 42 under static, non-pumping conditions. The conduit 45 is of such extent that the bight portion thereof extends appreciably above the liquid level normally existing in the pipes 4| and 42 under static, non-pumping conditions though this is not essential. A gas supply conduit 45 to which is connected any suitable source of gas under pressure opens into the central bight portion of the conduit 45 whereby the pumping gas is supplied "to the pumping mechanism above the liquid level in the conduit 45. The pump just described may be constructed of any suitable type of tubing which is sufficiently strong to withstand the pressure prevailing in the system in which it is to be used.

Referring now to Figures 3 and 4, the operation of our twin gas lift pumping device will be explained. Assuming the conduits 46 and 44 to be connected to suitable sources of gas under pressure and liquid, respectively, it will be seen that the gas supplied to'the U-shaped conduit 45 will depress the liquid level therein until'such time as the liquid in the conduit 45 is forced therefrom into the conduits 4| and 42. We have ob served in operation of the pumping device here in disclosed that the liquid being pumped does not discharge from the conduit 45 in two streams but, on the contrary, discharges in bubbles or slugs alternately into the conduits 4| and 42. This is believed to be due to the fact that the bubbles formed at the points of connection between the conduit 45 and the pumping conduits 4| and 42 do not form exactly equally and that one or the other of the bubbles will break free of the conduit 45 and begin to rise in the conduits 4| or 42 thereby lightening the fluid in that column and causing the liquid to surge in the direction of the lighter column. Assuming that the conduit 42 first begins to pump, the surge will cause the liquid to be carried beyond the point at which the conduit 45 connects with the conduit 42 and will also cause the liquid to rise into the conduit 45. In addition to the action just noted, the liquid surge will, in effect, reduce the pressure upon the non-pumping conduit 4| against which the pumping gas must be forced produce a continuous liquid flow to the higher into that conduit. Gas will then discharge into the conduit 4| and the liquid will surge from conduit 42 into conduit 4i through the conduit 43. It is apparent from theexplanation above that the conduits 4i and 42 discharge alternately and a liquid piston oscillates through the conduit 43 first into the conduit 4i and then into the conduit 42.

In accordance with the present invention there is provided a twin gas lift pumping apparatus. The expression twin gas lift pump is used to refer to a pumping mechanism in which one or more upstanding bodies of liquid to be pumped are in free and open communication witha source of the liquid to be pumped, with a confined body of liquid which is adapted to oscillate or surge during the pumping process and with a source of pumping gas under pressure. Stated somewhat differently, the present invention comprises a pumping mechanism in which an upstanding or rising body or column of liquid is in free and open communication with a chamber containing an additional body of liquid which liquid to be pumped is made at a point below the free surface of such liquid under static nonpumping conditions and that the gas is applied at a pressure sufiicient to overcome the static pressure of the pumping column under static conditions in order that the gas may force its way into such column for the purpose of elevating the liquid to some desired point of disposal.

It is apparent from the disclosure that the pump comprises one or more upstanding liquid columns which are continuous with an oscillating or liquid piston. Obviously the aforementioned bodies of liquid all constitute a single body of liquid but for purposes of understanding and expressing the nature of the invention it is more convenient. to consider each upstanding column or body of liquid as a separate portion of liquid and to consider theoscillator'y piston or column as a distinct and individual body of liquid. In this way the upstanding elevation.

The apparatus has been disclosed as being symmetrical for convenience of explanation. If

necessary or desirable, the elevating conduits need not be identical. Proportional division of the liquid may be obtained by forming the elevating conduits of different diameters. Also the elevating conduits. may discharge at different elevations if necessary or desirable. The pumping ability of each elevating conduit is a function of the inside cross-sectional area of the conduit, the length of the conduit and the pressure prevailing in the discharge chamber. Thus our pumping and dividing device is adapted to divide liquid from a single source into a plurality of streams of different cross-sectional area, to discharge these streams into different pressure zones, and to discharge the streams at diiferent elevations. Any one or more of these variables may be incorporated in a single pump and di- "vider if necessary or desirable.

While we have illustrated and described a single embodiment of our invention, it is to be understood that it is to be taken as illustrative only and not in a limiting sense. We do not wish to be limited to the precise structure shown but to include all equivalent variations thereof except as limited by the scope of the appended claims.

We claim:

1. Apparatus of the character described comprising a U-shaped conduit, means for supplying liquid to the bight portion of said U-shaped conduit, an inverted U-shaped gas supply conduit having the legs thereof connected to the legs of said u-shaped conduit, and means for sup-' plying gas under pressure to the bight portion of said inverted U-shaped conduit.

2. Apparatus of the character described comprising a plurality of elevating conduits, means providing free communication between the lower ends of said conduits, means for supplying liquid to said means, means providing free communication between said liquid columns above said first mentioned means, and means for supplying readily be distinguished from the body of liquid I which oscillates to and from each pumping column in order to aid in the pumping action.

.Thus, in the present invention each pumping column is in free and open communication with an oscillatory column of liquid which surges in the direction of the pumping column when the same is lightened by admission thereto of pump* ing gas and which then surges away from the pumping column by the usual reaction to admit additional gas for further pumping.

It will be seen from the description above that our pumping device discharges alternately through each pumping leg but that there is, considering the pump as a whole, a continuous liquid discharge therefrom, and that our invention not only functions as a pump but also as an eflicient dividing device. The conduits 4| and 42 may, if desired, discharge into separate chambers in the manner disclosed in connection with the refrigerating system just described, or they may discharge into a single chamber to gas under pressure to said second mentioned communication means.

3. A liquid pumping system comprising an unobstructed U-shaped conduit, a source. of liquid supply, means for supplying liquid from said source of supply to the lower portion of said U-shaped conduit whereby the liquid level in said U-shaped conduit is substantially the same as the liquid level in said source of supply, means interconnecting said columns below the liquid level therein, and means connected to said last mentioned means above the liquid level in said columns and adapted to supply gas under pressure.

4. A liquid divider adapted for use in a continuous absorption refrigerating system, said divider comprising an unobstructed U-tube, means for supplying a stream of liquid to the bottom thereof and means for supplying gas to both legs of said U-tube to lift the liquid alternately in said legs to divide the same into two streams.

5. A liquid pump adapted for use in a continuous absorption refrigerating system, said.

pump comprising an unobstructed U-tube, means for supplying liquid to the bottom of said U-tube and means for causing gas to pass upwardly through the legs thereof to carry the liquidalong with it, the arrangement being such that the liquid is lifted first through one leg and then through the other to be alternately discharged therefrom.

6. A valveless pumping apparatus comprising a plurality of elevating conduits in open communication with each other and a source of liquid supply at their lower ends, means freely communicating all of said elevating conduits above their lower ends, and means for supplying pumping gas to said last-mentioned means.

7. A valveless pump comprising a pair of elevating conduits, a chamber interconnecting said conduits and adapted to contain an oscillating body of liquid, means for supplying liquid to be pumped to said chamber, and a. source of gas under pressure in open communication with each of said conduits, the arrangement being such that a body of liquid is caused to oscillate through said chamber between said conduits and alternately to allow and prevent discharge of gas into said elevating conduits.

8. Liquid pumping apparatus comprising an open U-tube, a liquid supply conduit connected to the bight portion of said U-tube, an inverted open U-tube having the legs thereof connected to the legs of said U-tube, a centrifugal gas fan, and a gas supply conduit connected to divert a portion of the gas discharged by said Ian into the bight portion of said inverted U-tube.

9. In a device of the character described the combination of a liquid impeller, a source of gas under'pressure, a source of liquid, and means connecting said source of liquid to said impeller, said impeller comprising a plurality of pumping conduits, means adapted to contain an oscillatory body of liquid in open communication with each of said pumping conduits, and means providing open communication between said source of gas under pressure and each of said pumping conduits.

10. In a device of the character described the combination of a liquid impeller, a source of gas under pressure, a source of liquid, and means connecting said source of liquid to said impeller, said impeller comprising a pumping conduit, means peller comprising a plurality of pumping conduits,

means adapted to contain an oscillatory body of liquid in open communication with each of said pumping conduits, means for conducting liquid from said source to said first mentioned means, and means providing openv communication between said source of gas under pressure and each of said pumping conduits.

12. The method of, propelling a liquid which comprises the steps of introducing a gas into a body of the liquid moving along a predetermined path, and causing the gas to react against the portion of the body of the liquid extending from the point of introduction of the gas to the point of discharge to move, such portion toward said point and also causing the gas to react against another portion of said body to cause the same to surge from and back into the said predetermined path of the moving body to a point beyond said point of introduction.

13. In a device of the character described the combination of a liquid impeller, a source of gas under pressure, a source of liquid and means connecting said source of liquid to said impeller, said impeller including a pair of liquid elevating conduits, a conduit adapted to retain .an oscillatory body of liquid connected to and in open communication with said elevating conduits, agas feed conduit connected to and in open communication with said elevating conduits, and a conduit for conducting gas from said source of gas under pressure to said gas feed conduit.

14. That method of propelling a liquid which includes the steps of introducing a gas into each of a pair of bodies of liquid having a portion in common and each having a portion extending along a predetermined path from the point at which gas is introduced thereinto toward a point of discharge and causing the gas to react against said portions extending toward said points to move such portions toward said points and causing the gas to react against said portion in common to cause said common portion to surge out 01 and into said predetermined paths to points beyond said points of introduction of the gas.

15. In a device of the character described a source of liquid to be pumped, a source 01 gas under pressure, and a liquid impeller, said impeller comprising a pair of pumping conduits, a connecting conduit in open communication with each of said pumping conduits adapted to retain an oscillatory body of liquid, conduit means in open communication with said connecting conduit, a second connecting conduit in open communication with said pumping conduits, and a gas supply conduit in open communication with said second connecting conduit for conveying pumping gas from said source thereto.

CURTIS C. COONS. RUDOLPH S. NELSON.

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