Pneumatic ejector

Abstract

A hydraulically controlled pneumatic ejector for handling liquids containing solid material. The ejector includes a vessel having a top cover secured thereto in an air tight manner. A vertical discharge pipe extends through the top cover into the vessel in an air tight manner. A U-tube, positioned within the vessel with an end in fluid communication with the interior of the vessel, serves to control the operation of the ejector. A flapper type-check valve controls the entrance of liquid into the vessel through an inlet opening at the bottom of the vessel. An air inlet pipe extends through the top cover to continuously supply compressed air into the vessel.

Description

BACKGROUND AND SUMMARY OF THE INVENTION

This invention relates to ejector type pumping units and more specifically to a hydraulically controlled pneumatic ejector for handling liquids containing solid material such as raw sewage or the like.

It has been the heretofore practice to use conventional vacuum primed, vertical shaft, centrifugal pumps mounted on a deck plate above a wet well to pump raw sewage. Although such equipment, when properly designed, functions very satisfactorily, the initial cost and periodic maintenance cost of such equipment is relatively high. A good example of this type of installation is disclosed in U.S. Pat. No. 3,558,012, assigned to the same assignee as the present invention.

It is a primary object of the present invention to provide a pneumatic ejector for use in pumping raw sewage from a wet well.

Another object is to provide a hydraulically controlled pneumatic ejector for use in pumping raw sewage having only one moving part.

A further object of the invention is to provide a hydraulically controlled pneumatic ejector which will continue operating when clogged with foreign matter.

A still further object is to provide a hydraulically controlled pneumatic ejector having an inlet check valve which will continue operating when foreign matter holds the check valve open and will clear itself on the succeeding cycle.

Another object is to provide a hydraulically controlled pneumatic ejector in which all internal piping is designed to be self-cleaning.

The foregoing and other objects are realized in accordance with the invention by providing an ejector unit which includes a housing or vessel having a top cover secured thereto in an air tight manner. A vertical discharge pipe extends through the top cover into the vessel in an air tight manner. A U-tube, positioned within the vessel with one end in fluid communication with the discharge pipe and the other end in fluid communication with the interior of the vessel, serves to control the operation of the ejector. A flapper type check valve controls the entrance of raw sewage into the vessel through an inlet opening at the bottom of the vessel. An air inlet pipe extends through the top cover to continuously supply compressed air into the vessel and force sewage out the discharge pipe during the ejecting phase. Liquid entering and exiting the U-tube automatically switches the ejector between its ejecting phase and its filling phase. The positioning of the U-tube and the inlet opening with respect to the discharge pipe prevents solid particles from entering the U-tube and air from exiting from the inlet opening.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and features of the invention will become apparent to those skilled in the art as the disclosure is made in the following description of a preferred embodiment of the invention, as illustrated in the accompanying sheet of drawings, in which:

FIG. 1 is an elevation, partially in section, of a somewhat diagrammatic representation of the pneumatic ejector of the present invention shown positioned within a sewage receiving wet well; and

FIG. 2 is a sectional view of an alternative inlet flapper valve arrangement.

DESCRIPTION OF A PREFERRED EMBODIMENT

Referring to FIG. 1, a pneumatic ejector constructed in accordance with the present invention is designated generally at 10. Ejector 10 is illustrated seated within a standard wet well 12, from which it pumps sewage received therein. Although illustrated and disclosed in the environmental context of a sewage pump station assembly, it will be readily appreciated that the hereinbelow disclosed pneumatic ejector may be utilized in other environments which require the pumping of liquids containing solid material.

Ejector 10 includes a rectangular housing 14 having a top cover 15 releasably secured thereto in an air tight relationship by bolts 16 so as to form an air tight vessel or tank 18. Extending into vessel 18 through cover 15 is a substantially vertical discharge pipe 20. The upper end of discharge pipe 20 is suitably attached to a coupling 22 which in turn is attached to an appropriate distribution pipe 23. The lower end of discharge pipe 20 extends into vessel 18 to a depth approximately equal to three-fourths the height of vessel 18. A U-tube or control tube 24 is formed within vessel 18 by a substantially horizontal pipe section 26, ninety degree connecting elbows 28, 30, and 32, and a pair of substantially vertical pipe sections 34 and 36. Pipe 26 has a first end 38 in fluid communication with discharge pipe 20 at a depth approximately equal to one-eighth the height of vessel 18, and a second end 40 attached to an upper end 42 of pipe 34 through elbow 28. The lower end 44 of pipe 34 is attached to elbow 30 which in turn is attached to elbow 32. The lower end 46 of pipe 36 is attached to elbow 32 and the upper end 48 extends upward to a level a short distance below cover 15.

Communicating with an upper portion of vessel 18 is an air inlet connection 50 passing through an appropriate opening in top cover 15. An air inlet pipe 52, having a control valve 54 associated therewith, is secured at one end to connection 50 and at its other end to a conventional source of compressed air (not shown).

Air inlet opening 60 is provided through the side wall of vessel 18 adjacent the lower edge thereof. Referring to FIG. 1, an inlet flapper type control valve 62 controls the passage of sewage from wet well 12 through inlet opening 60 into vessel 18. Control valve 62 is shown in solid lines in FIG. 1 in its closed position and in phantom lines in its open position. Control valve 62 includes a rubber gasket/hinge 64 which extends beyond the outer periphery of opening 60 in a closing relationship thereto along the inner surface of vessel 18. The upper edge of gasket 64 is secured to vessel 18 by mounting bolts 66 and retaining member 67. Secured to the inner surface of gasket 64 in horizontal alignment with opening 60 is a metallic flapper disk 68 having an outer periphery extending beyond the periphery of opening 60. Secured to the outer surface of gasket 64 in horizontal alignment with opening 60 is a metallic back-up disk 69 having an outer periphery contained within the periphery of opening 60. Mounting bolt 70 sandwiches gasket 64 between disks 68 and 69. Gasket 64, being of a flexible material, acts as a hinge point at the point between retaining member 67 and flapper disk 68 to swing gasket 64 between its closed position in contact with vessel 18 and its open position spaced from vessel 18.

Referring to FIG. 2, alternative inlet control valve is shown generally at 80. Control valve 80 is a wafer type check valve including a body 82 having horizontally aligned openings 83 and 84 formed therethrough. A clapper assembly 85 is pivotally mounted about a horizontal stem 86 for movement between a closed position having a closing relationship to opening 84 and an open position having a spaced relationship to opening 84. A valve seat 87 is formed around the periphery of opening 84 to receive an O-ring 88 to contact clapper assembly 85 when in its closed position. Control valve 80 is sandwiched between a mounting plate 90 and the side wall of vessel 18 by bolts 92 such that opening 83 is in horizontal alignment with opening 60 and an opening 94 in plate 90 is in horizontal alignment with opening 84.

In operation, ejector 10 is immersed in a sewage receiving wet well 12 and the pressure of the sewage within wet well 12 moves control valve 62 to its open position to permit the passage of sewage into vessel 18 through opening 60. As the liquid level within vessel 18 continues to rise past the level indicated at A, the liquid enters discharge pipe 20 and rises therein until it reaches the level indicated at B. At this point the liquid enters control tube 24 and seals the bottom portion of the U-tube 24. Prior to the sealing of U-tube 24, the continuous flow of pressurized air entering vessel 18 is directed through U-tube 24 into discharge pipe 20 and out of vessel 18 through distribution pipe 23. The sealing of U-tube 24 prevents this air from passing through U-tube 24 and thereby increases the pressure within vessel 18. This increase in pressure forces the liquid higher in discharge pipe 20 and U-tube 24 and moves control valve 62 to its closed position. The pressure within vessel 18 continues to force the liquid within vessel 18 up discharge pipe 20 and out distribution pipe 23 until the liquid level within vessel 18 drops to the level indicated at C, at which point air is free to pass through U-tube 24, to be vented out discharge pipe 20. The resulting loss of pressure within vessel 18 causes the sewage from wet well 12 to move control valve 62 to its open position and enter vessel 18 to repeat the hereinabove disclosed cycle. The air flow through pipe 52 is controlled by valve 54 and must be sufficient to overcome the discharge head and losses through the system. The air pressure required can be determined by multiplying the total dynamic discharge head (ft.) by 0.542 p.s.i. The dynamic head should be calculated based on a flow of 1.5 times the maximum average pumping flow rate.

Should control valve 62 get stuck in its open position by a solid particle, the liquid within vessel 18 would be forced back through valve 62 into wet well 12 until the seal in U-tube 24 is broken. Liquid from wet well 12 will then rush in through control valve 62 and flush out the solid particle and thereby permit the return to normal operation. Control valve 62 is positioned low enough in vessel 18 to prevent air from leaking out therethrough and disrupting service. The operation of alternative control valve 80 performs in substantially the identical manner as does control valve 62 and therefore will not be discussed in further detail.

The hereinabove disclosed hydraulically controlled pneumatic ejector is a simple device, capable of handling solids, and tends to be self-cleaning if clogged. The only moving part is the inlet control valve, which is specifically designed to be self-cleaning to increase the reliability of the ejector. Foreign matter holding the inlet control valve in its open position does not prevent operation, and will be cleared on succeeding cycles. Removal of top cover 15 allows complete access to all internal piping.

It should be understood, of course, that the foregoing disclosure relates to only a preferred embodiment of the invention and that numerous modifications or alterations may be made therein without departing from the spirit and the scope of the invention as set forth in the appended claims.

Claims

What is claimed is:

1. A hydraulically controlled pneumatic ejector for handling liquids containing solid material; comprising:

a. a vessel constructed in a substantially air tight manner for receiving liquid thereinto;

b. a gas inlet pipe extending into said vessel through an upper portion thereof for supplying gas thereinto to pressurize said vessel, said inlet pipe being in communication with a continuous source of pressurized gas;

c. a discharge pipe extending into said vessel through the upper portion thereof;

d. a U-tube positioned within said vessel having a first vertical pipe section in fluid communication with said discharge pipe at its upper end and a second vertical pipe section in fluid communication with the upper portion of said vessel at its upper end, said first and second pipe sections being connected at their lower ends so as to define a substantially horizontal passageway therebetween, said U-tube serving to vent gas therethrough into said discharge pipe when not sealed by liquid confined therein and preventing the passage of gas therethrough when sealed by liquid confined therein; and

e. an inlet opening through a lower portion of said vessel, the top of said inlet opening being positioned below at least a portion of said substantially horizontal passageway; and at or below the lowermost portion of said discharge pipe so as to permit the passage of liquid thereinto, said inlet opening having a control valve means associated therewith operable to permit and prevent the passage of liquid therethrough into said vessel dependent upon the pressure differential across said inlet opening.

2. The invention as defined in claim 1 wherein said discharge pipe extends into said vessel to a level below the bottom of said U-tube.

3. The invention as defined in claim 2 wherein said control valve means includes a clapper member pivotally mounted about a substantially horizontal axis to permit movement between an open position permitting the passage of liquid through said inlet opening and a closed position preventing the passage of liquid through said inlet opening.

4. The invention as defined in claim 3 wherein said clapper member is secured to the inner surface of said vessel immediately above said inlet opening.

5. The invention as defined in claim 2 wherein said control valve means includes a wafer type flapper valve which is secured to said vessel adjacent said inlet opening.

6. The invention as defined in claim 2 wherein said first vertical pipe section of said U-tube communicates with said discharge pipe at a level substantially above the level of said bottom end of said discharge pipe so as to prevent solid material from entering said U-tube.

7. The invention as defined in claim 2 wherein said vessel includes a removable top cover to close off an opening in said vessel and said discharge pipe and said air inlet pipe extend through said top cover so as to permit access into said vessel upon removal of said top cover.

8. A hydraulically controlled pneumatic ejector for pumping sewage from a wet well, comprising:

a. a vessel constructed in a substantially air tight manner positioned below the liquid level of said wet well, said vessel including a top cover member closing off an opening through an upper portion thereof;

b. a gas inlet pipe extending into said vessel through said top cover for supplying gas thereinto to pressurize said vessel, said inlet pipe being in communication with a continuous source of pressurized gas;

c. a discharge pipe extending into said vessel through said top cover member;

d. a U-tube positioned within said vessel having a first vent pipe section, the upper end of said first pipe in fluid communication with an upper portion of said discharge pipe and a second vent pipe section in fluid communication with an upper portion of said vessel at its upper end, said first and second pipe sections being connected at their lower ends so as to define a substantially horizontal passageway therebetween, said U-tube serving to vent gas therethrough into said discharge pipe when not sealed by liquid confined therein and preventing the passage of gas therethrough when sealed by liquid confined therein, said discharge pipe extending into said vessel to a level below the bottom of said U-tube; and

e. said inlet opening through a lower portion of said vessel, the top of said inlet opening being positioned below at least a portion of said substantially horizontal passageway and at or below the lowermost portion of said discharge pipe, so as to permit the passage of liquid thereinto, said inlet opening having a flapper type control valve means associated therewith operable to to permit and prevent the passage of liquid into said vessel dependent upon the pressure differential across said inlet opening, said control valve means being positioned a sufficient distance below the bottom of said discharge pipe to prevent gas from escaping through said inlet opening.