Double Valve Vapor Push Pump

Abstract

Disclosed is a vapor push pump having a housing adapted to be immersed in a liquid to be pumped. Within the housing a chamber is defined; the chamber communicates with the liquid outside the housing via a port provided in the housing. A heater in the chamber vaporizes some of the liquid admitted to the chamber through said port. Vapor pressure in the chamber forces (pushes) the liquid through a liquid delivery conduit, passing through the housing, to a location outside the housing and above the level of the liquid in which the housing is immersed. A buoyant first valve body moves and closes, or opens, said port, as a function of the head of liquid outside the housing, the weight of the first valve body, the level of liquid in the chamber and the vapor pressure in the chamber and surface tension. Also provided is a vapor vent conduit passing through said housing to vent vapor in the chamber to a location outside the housing and above the external liquid level. A buoyant second valve body within the chamber moves to close or open the vapor vent conduit as a function of the weight of the second valve body, the level of liquid in the chamber and the vapor pressure in the chamber and surface tension. Also, the first valve body is caused to open abruptly when the second valve body operates to vent the vapor pressure from the chamber.

Description

CROSS-REFERENCES TO RELATED PATENT APPLICATIONS

A related novel push pump is disclosed in the U.S. Pat. application Ser. No. 310,662, filed Nov. 29, 1972, on even date herewith, in behalf of the inventors H. Jaster and P. G. Kosky and titled SINGLE VALVE VAPOR PUSH PUMP. Also, a novel vaporization cooling system using a condensate recirculation pump employing vapor push pump principles is disclosed in the U.S. Pat. application Ser. No. 310,323, filed November 29, 1972, on even date herewith, in behalf of the inventors F. W. Staub and P. G. Kosky and titled EVAPORATIVE COOLING SYSTEM EMPLOYING LIQUID FILM EVAPORATION FROM GROOVED EVAPORATOR SURFACE AND VAPOR PUSH PUMP FOR CIRCULATING CONDENSATE.

The entire right, title and interest in and to the inventions described in the aforementioned patent applications, as well as in and to the aforementioned applications, and the entire right, title and interest in and to the invention herein described, as well as in and to the patent application of which this specification is a part, are assigned to the same assignee.

BACKGROUND OF THE INVENTION

The invention, hereinafter disclosed in connection with an accompanying drawing, pertains to a novel pump for pumping liquid; and, more particularly, to a pump wherein part of the liquid delivered thereto for pumping is vaporized and the vapor pressure so developed is employed for forcing, or pushing, the remaining liquid through a liquid delivery conduit.

Because it is appropriately descriptive, the subject pump is often referred to hereinafter, in the specification and in the claims, as a "vapor push pump".

Conventional mechanical pump units (e.g., rotary, reciprocating or diaphragm pumps) have, among others, the following limitations respecting their performance: (1) restricted reliability due to the inclusion of many moving parts; and (2) the inability of such conventional units to effectively pump saturated liquids because of cavitation.

Since reliability of mechanical pump units is generally associated with the number of moving parts efforts have been made to reduce the number of moving parts to a minimum. For example, in a conventional pump unit such moving parts include the prime mover (e.g., an electric motor), bearings, mechanical couplings, impeller, etc.

SUMMARY OF THE INVENTION

One object of the invention is to provide a novel pump employing few moving parts in order to enhance the pump's reliability and also to enable less expensive construction and maintenance.

Another object of the invention is to provide a novel pump which is capable of pumping saturated liquids.

Briefly, in accordance with an illustrative embodiment of the invention, there is provided a vapor push pump comprising: a housing adapted to be submerged below the liquid level of a body of liquid to be pumped, said housing including a chamber therein and a port through which liquid from said body of liquid may enter the housing and at least partly fill said chamber therein; a first conduit having inlet and outlet openings, said inlet opening of said first conduit defining a communicating path between said chamber and said first conduit for venting vapor from said chamber through said first conduit, said outlet opening of said first conduit being located above said liquid level of said body of liquid; a second conduit having inlet and outlet openings at opposite ends thereof, said inlet opening of said second conduit being normally submerged in liquid in said chamber and said outlet opening of said second conduit being located above the liquid level of said body of liquid, said second conduit passing in sealed relationship through said housing; means for vaporizing at least part of the liquid in said chamber to enable the vapor pressure produced therein to push the liquid in said chamber into said inlet opening of said second conduit and through said second conduit until the liquid is discharged at said outlet opening of said second conduit; a buoyant first valve body within said chamber, movable in response to the difference between the force exerted by the liquid level of said body of liquid through said port on said first valve body and the algebraic sum of the forces represented by the weight of the first valve body, the buoyant force exerted by the liquid in the chamber on said first valve body and the force on the first valve body due to vapor pressure of vapor in said chamber and to surface tension, for closing or opening said port; and, a buoyant second valve body within said chamber, operable as a function of the weight of said second valve body, the level of liquid in said chamber, the vapor pressure in said chamber and the surface tension for closing and opening the inlet opening of said first conduit.

Other objects, the various features and advantages of the invention, as well as a fuller understanding thereof, will appear by referring to the following detailed description, claims and drawing.

THE DRAWING

In the drawing there is schematically shown a vertical cross section of a vapor push pump in accordance with the invention.

DESCRIPTION OF A PREFERRED EMBODIMENT

In the schematic cross section drawing a vapor push pump is designated, generally, by the reference number 10. The pump 10 includes a housing 12 within which there is defined a chamber 14. The housing 12 is provided with a port 16, or opening, at the top thereof so that liquid from an external body 18 of liquid may enter port 16 and at least partly fill the chamber 14. The housing 12 is submerged in the external body 18 of liquid whose head Hx, or liquid level, is indicated in the drawing with reference to a datum plane passing through the top cover of housing 12. At the top of housing 12 an additional opening 20 is provided. Opening 20 allows a conduit 24 to pass through the housing 12 to provide communication between the chamber 14 and a location above the liquid level, or head Hx, of the body 18 of liquid. The conduit 24 passes through opening 20 but is, nevertheless, in sealed relationship with the housing 12. The conduit 24 has at opposite ends thereof inlet and outlet openings 21 and 22, respectively. The outlet opening 22 of conduit 24 is, as shown, located above the liquid level, or head Hx, of the external body 18 of liquid. The conduit 24 serves as a vapor vent, the action of which is described hereinafter. Another conduit 26 which, as shown, is relatively long passes through another opening 25 provided in the housing 12; the conduit 26 being in sealed relationship with respect to the housing 12 where it passes through the opening 25. The conduit 26 has an inlet opening 28 at the lower end thereof within chamber 14 and an outlet opening 30 at the opposite or upper end thereof. The conduit 26 serves as a liquid delivery tube, or riser, because liquid within the chamber 14 of housing 12 is pushed through the inlet opening 28 by vapor pressure in the space above the liquid within chamber 14 and the liquid, so pushed, flows upwardly in conduit 26 where it is ultimately discharged at the outlet opening 30 thereof. As indicated in the drawing the outlet opening 30 extends beyond the external body 18 of liquid, above its liquid level or head Hx. The inlet opening 28 is submerged in the liquid in chamber 14 within the housing 12.

Situated in chamber 14 is a tube 32 or shroud of low thermal conductivity (i.e., thermal insulation material) and low thermal diffusivity which, as indicated, has an inlet port 34 of small diameter at the bottom thereof and an opening 36 at the top thereof. Situated within the tube 32 is an electric cartridge-type heater 38. A pair of electrical leads 40 having ends thereof electrically connected to the heater 38 extend in sealed relationship through the housing 12 to the outside thereof so that heater 38 may be electrically energized via the leads 40 externally of housing 12. Within tube 32 or shroud near the upper opening 36 thereof is a liquid-vapor separator member 42. The separator member 42 extends across the diameter of the tube 32 within the tube but, nevertheless, permits the passage of vapor upwardly through tube 32 and out of the opening 36. The member 42 intercepts liquid particles entrained with vapor and effectively allows the entrained liquid, after separation from the vapor, to be returned to the inside wall of the tube 32 so that a liquid film formed thereon can flow downwardly toward the liquid level within the tube 32. The separator member 42 is shaped somewhat like a propeller in order that the vapor and entrained liquid on impingement therewith changes direction so that the vapor and entrained liquid are given a radial direction change whereby the entrained liquid can move radially outward from the separator member 42 to form a liquid film on the inside wall surface of the tube 32 while the vapor, now separated from the liquid, can move upwardly and exit into chamber 14 through the outlet opening 36.

Arranged for movement within the chamber 14 are two buoyant valve bodies 44 and 46. As indicated in the drawing the valve bodies 44 and 46 can move upwardly or downwardly as indicated by the direction of the arrows adjacent said valve bodies. The valve body 44 has a relatively thin flexible diaphragm 45 at the upper end thereof as indicated. Likewise, the valve body 46 has a thin flexible diaphragm 47 at its upper part as indicated. One material, among others, suitable for the diaphragms 45 and 47 is silicone rubber. A suitable stop member 48 helps to limit the vertical travel of the valve body 44 as suggested in the drawing as well as limiting horizontal motion. Similarly, the stop members 49 limit the travel of the valve body 46. As suggested in the drawing the stop members 48 and 49 leave openings so that liquid or vapor may contact and exert pressure or force on the valve bodies 44 and 46 as well as the diaphragms 45 and 47.

The inside diameter of the vapor vent conduit 24, including the inlet and outlet openings 21 and 22, is smaller than the inlet port 16 in housing 12. The reasons for this appear hereinafter whereat a discussion of the operation of the subject vapor push pump 10 as set forth.

OPERATION

As indicated the housing 12 is sealed except for the openings 16, 20 and 25. The openings 20 and 25, however, have the conduits 24 and 26 passing therethrough and these conduits are sealed to the housing 12. Within the housing 12 the buoyant first valve body 44 allows the port 16 to open because of the force exerted on diaphragm 45 by the external body of liquid 18 above the top cover of housing 12 plus the weight of valve 44. Thus, liquid from the external body 18 of liquid enters the chamber 14 through port 16. Liquid from the body 18, after it enters the open port 16, rises within chamber 14 until the buoyancy of the valve in the liquid within chamber 14 causes it to float and close the inlet port 16. The liquid within the chamber 14 enters the tube or shroud 32 through the inlet port 34 and surrounds the heater 38. The heater 38 adds heat to the liquid in shroud 32 until the liquid therein is raised to its boiling point. The vapor thus produced within the tube 32, or shroud, moves upwardly and the liquid entrained in the vapor is removed in the manner hereinbefore discussed by the separator 42 so that "dry" vapor exits into the chamber 14 through the outlet opening 36. Vapor accumulates in the chamber 14 above the level of liquid therein. Some fraction of the vapor in the chamber 14 condenses at the vapor-liquid interface in chamber 14 as well as on the surfaces of the various solid elements therein. Providing sufficient energy is supplied by the heater 38 the net vapor produced does useful work in pushing the liquid in chamber 14 through the inlet opening 28 of conduit 26. The liquid pushed through the inlet opening 28 is forced upwardly through conduit 26 and discharged at opening 30, against any back pressure exerted on the inside of conduit 26 through the opening 30. In order to force liquid from chamber 14 through opening 28 into conduit 26 and cause it to rise within conduit 26 the pressure of the vapor within chamber 14 must correspondingly increase. The increase in pressure causes diaphragm 45 to deflect into opening 16 and thus effect a seal. When the level of the liquid within the chamber 14 has fallen to a lower level the internal pressure (vapor pressure) in the chamber 14 is still sufficient to maintain the valve body 44 in a position closing the inlet port 16. However, as more liquid is pushed upwardly through the conduit 26 the level of liquid in chamber 14 falls to a level low enough to cause the buoyant second valve body 46 to move downwardly thereby opening the inlet opening 21 of the vapor vent conduit 24. At this point vapor within the chamber 14 enters the inlet opening 21 and is vented through the conduit 24 where it exits from the outlet opening 22. Thus, vapor pressure within the chamber 14 is relieved and allows the buoyant first valve body 44 to move downwardly thereby reopening the inlet port 16 for the purpose of admitting a fresh charge of liquid from the external body 18 of liquid and allowing vapor and accumulated gases, if any, to escape. Thereafter, the cycle hereinbefore described is repeated. Sometimes gas may be included in the liquid in the chamber 14 from which said gas can evolve.

One feature of the invention is that the second buoyant valve body 46 is designed to fall under its own weight against the force represented by the product of the area of inlet opening 21 of conduit 24 and the difference in pressure between the vapor in chamber 14 and the pressure existing above level Hx. In addition, the diameter of the vapor vent conduit 24 is sized so as to allow rapid venting of vapor from chamber 14.

Although one more or less specific embodiment of the invention has been described and illustrated in the accompanying drawings, it is to be understood that this has been done for the purpose of providing a working example of the invention and that many changes, not departing from the inventive principles involved, will occur to those skilled in the art. The scope of the invention is, however, to be determined from the claims hereinafter set forth.

Claims

What is claimed is:

1. A vapor push pump comprising: a housing having a top cover, at least a portion of said top cover being adapted to be submerged below the liquid level of an external body of liquid to be pumped, said housing including a chamber therein, said portion of said top cover including a port through which liquid from said external body of liquid can enter said housing and at least partly fill said chamber therein; a first conduit having inlet and outlet openings, said inlet opening of said first conduit being within said chamber at a fixed distance below said port and defining a communicating opening between said chamber and said first conduit for venting vapor from said chamber through said first conduit, said first conduit passing in sealed relationship through said housing, said outlet opening of said first conduit being located above said liquid level of said external body of liquid; a second conduit having inlet and outlet openings, said inlet opening of said second conduit being a fixed distance below said inlet opening of said first conduit and submerged in liquid in said chamber, said outlet opening of said second conduit being located above the liquid level of said external body of liquid, said second conduit passing in sealed relationship through said housing; means for vaporizing at least part of the liquid in said chamber to enable the vapor pressure produced therein to push the liquid in said chamber into said inlet opening of said second conduit and through said second conduit until the liquid therein is discharged at said outlet opening of said second conduit; a buoyant first valve body within said chamber, movable in response to the algebraic sum of the force exerted by the liquid head of said external body of liquid through said port on said first valve body, the weight of said first valve body, the buoyant force exerted by the liquid in the chamber on said first valve body, the force on the first valve body due to vapor pressure of vapor in said chamber and surface tension, for closing or opening said port; and, a buoyant second valve body within said chamber, operable as a function of the weight of said second valve body, the level of liquid in said chamber, the vapor pressure in said chamber and surface tension, for closing or opening said inlet opening of said first conduit.

2. The vapor push pump according to claim 1 wherein said means for vaporizing the liquid in said chamber is an electric heater located in said housing but energizable from outside said housing.

3. The vapor push pump according to claim 2 further comprising a shroud of thermal insulation material located within said housing and encompassing said heater, said shroud including a first aperture for admitting liquid from said chamber into contact with said heater so said heater can vaporize at least part of the admitted liquid, said shroud also including a second aperture located a fixed distance above said first aperture for enabling discharge of the vapor into said chamber at a level between said port and said inlet opening of said first conduit.

4. The vapor push pump according to claim 3 further comprising separator means in combination with said shroud, said separator means separating entrained liquid from the vapor produced by said heater in said shroud.