Reverse-osmosis Pump

Abstract

A multiple stage pump comprising a main chamber, a booster chamber and a driving chamber each having a piston therein with the pistons interconnected by a common piston rod for reciprocating the pistons in unison. Main conduit means connects the main chamber with a fluid supply and the inlet of a reverse-osmosis device. Second conduit means connects the fluid reject discharge port of the reverse-osmosis device with the booster chamber. Hydraulic pump means including a pressure compensated pump and hydraulic conduits connected with a hydraulic fluid reservoir is connected with the driving chamber. Control means actuated by the reciprocating action of the piston rod operates valve devices in the hydraulic conduits and second conduits to maintain a continuous flow of fluid, under a predetermined pressure, from the main chamber to the reverse-osmosis device.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention.

The present invention relates to fluid pumps and more particularly to a hydraulically driven multi-stage pump for a hollow-fiber-reverse-osmosis device which utilizes the kinetic energy of a pressurized stream of reject fluid as a booster in driving the pump.

The principle of reverse-osmosis is used to separate components of fluid, such as fractionating a salts solution, brackish water, for example, into a relatively saltfree effluent and a saltsconcentrated effluent. This is accomplished by subjecting the fluid feed to a pressure higher than its osmotic pressure and bringing it into contact with a semipermeable membrane in a container so that the pressure drives water ions through the membrane. The reject salts-concentrated water, under proportionate pressure, is discharged from the container.

This invention provides a pumping system for generating the required feed pressure and utilizes the pressurized stream of reject fluid in driving the pump.

2. Description of the Prior Art.

The prior art patents disclosing hydraulic driven pumps have generally comprised a pair of piston equipped cylinders with the cylinders and piston rods arranged in parallel and connected with a hydraulically operated pumping means, such as is disclosed by U.S. Pat. No. 2,528,131. Another type of hydraulically operated pump is disclosed by U.S. Pat. No. 2,500,624 which utilizes a spring at one end of the main cylinder for returning the piston therein to the downwardly disposed end thereof.

This invention is distinctive over hydraulically operated pumps presently in use by providing a plurality of axially aligned cylinders, each having a piston therein connected with a piston rod common to all cylinders and forming a main pumping chamber and a booster pumping chamber with the booster pumping force supplemented by a hydraulic pumping means connected with a third cylinder.

SUMMARY OF THE INVENTION

A plurality of axially aligned cylinders form a main pumping chamber, a booster chamber, and a hydraulic chamber, each having a piston therein reciprocated in unison by a piston rod common to all pistons and cylinders. Main conduit means, connect the main chamber with a source of fluid supply with the output of the main chamber connected to a reverse-osmosis load device. Secondary conduit means connects the booster chamber with a pressurized stream of reject fluid from the load device through a first two-position valve device. Hydraulic conduit means connects the hydraulic cylinder with a pressure compensated hydraulic pump, connected with a hydraulic reservoir, through a second two-position valve device. Valve control means, operated by the reciprocating piston rod, at the respective end of its travel, shifts the first and second two-position valve devices so that a stream of reject fluid under pressure from the load device cooperates with the hydraulic pump means, as a pump booster force, for maintaining a predetermined pressure of fluid supplied to the load device.

The principle object of this invention is to provide a hydraulic pumping system maintaining a constant flow or stream of fluid under a predetermined pressure for a reverse-osmosis load device wherein a pressurized stream of reject fluid, from the load device, is utilized in driving a piston in a booster cylinder which is supplemented by hydraulic pumping means for driving the piston of a main pump.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the pump connected with a reverse-osmosis device; and,

FIG. 2 is a fragmentary longitudinal cross-sectional and diagrammatic view of the pump and its control means.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Like characters of reference designate like parts in those figures of the drawings in which they occur.

In the drawings:

The reference numeral 10 indicates a reverse-osmosis device which fractionates a salts solution, for example brackish water, into a relatively saltfree effluent and a salts-concentrated effluent. The device 10 includes a container 12 having end walls 14 and containing membranes consisting of very fine hollow fibers (85 microns outside diameter), not shown. The general chemical description of these fibers is disclosed in U.S. Pat. No. 3,567,632. The fibers are assembled within the container 12 in a manner similar to a shell-and-tube heat exchanger with the fibers representing the tubes and the container 12 forming the shell. The fractionating action is accomplished by subjecting the feed supply to a pressure higher than its osmotic pressure and forcing it into the container 12 through an inlet opening 16 for contact with the semipermeable membrane walls of the fibers wherein the applied pressure drives water, but relatively few salt ions, inwardly through the individual fiber walls leaving a concentrated salts solution. The concentrated salts solution, hereinafter called reject fluid, is discharged from the container discharge opening 18 under pressure proportionate to the input pressure. Fresh water, from the bore of the individual fibers, emerges from the opposite end of the container 12 through a pipe 20 connected with a storage tank 22.

The above described device 10 is conventional and forms no part of the present invention but is included to illustrate the manner in which the feed solution passing through the device 10 cooperates with the below described pumping system.

The reference numeral 25 indicates the pumping system, as a whole, comprising a plurality of axially aligned cylinders 26, 28, 30 and 32, respectively, provided with end plates 34-36, 38-40, 42-44 and 46 with the end plate 44 common to the cylinders 30 and 32. Diametrically the cylinders 28 and 30 are smaller than the cylinders 26 and 32. The cylinders 26, 28, 30 and 32, respectively, form a master or main pumping chamber 48, a booster chamber 50, a hydraulic pumping chamber 52 and a hydraulic fluid reservoir 54. The reservoir 54 contains a supply of hydraulic fluid 56 which may be replenished through a filler opening 57. The cylinders 26, 28, 30 and 32 are connected in axially aligned relation by elongated bolts 58, or the like, extending through the respective cylinder end plates. Pistons 60, 62 and 64 are disposed within the respective cylinders 26, 28 and 30. A piston rod 66 extends coaxially through the cylinders 26, 28 and 30 and through the respective end plates 34-36, 38-40 and 42-44 and is coaxially secured to the respective piston 60, 62 and 64. One end portion 68 of the piston rod projects into the reservoir 54 while the other end portion 70 of the piston rod projects beyond the cylinder end plate 34 and has a stop 72 secured thereto. The piston rod is sealed, with the respective end plate through which it projects, as by O-rings, as shown, and similarly the respective piston is provided with O-rings or seals, not shown, for forming a seal with the inner wall surface of the respective cylinders. Each of the cylinder end plates 34-36, 38-40 and 42-44 are provided with combination inlet-outlet ports 74-76, 78-80 and 82-84 communicating with the respective ends of the chambers 48, 50 and 52.

Main conduit means 86 forms a conduit header having conduit end portions 88 and 90 connected with the main chamber inlet-outlet ports 74 and 76, respectively. A pair of double check valves 92 and 94 are respectively interposed in cross conduits connected with the conduits 88 and 90. A supply conduit 95 connects a source of fluid supply, not shown, with the double check valve 92 through a filter F. Another conduit 96 connects the output of the double check valve 94 with a pressurized fluid receiving header 98 connected to the reverse-osmosis container 12 inlet 16 by a tube 100.

Secondary conduit means 102 comprises one conduit 104 connected at one end with the booster chamber inlet-outlet port 80 and connected at its other end with a reject fluid header 106 in turn connected with the reverse-osmosis container 12 outlet or fluid reject discharge port 18. The other conduit 108 of the secondary conduit means is connected at one end with the booster chamber inlet-outlet port 78 with the other end of the conduit 108 discharging reject fluid as waste. A first two-position valve means 110 is interposed in the secondary conduits 104 and 108 for controlling the direction of flow of reject fluid to the respective ends of the booster chamber 50.

Hydraulic pump means 112, comprising a pressure compensated pump P, driven by a motor M, is connected, by hydraulic conduit means 114, with the reservoir 54 and hydraulic pumping chamber 52. The hydraulic conduit means 114 comprises a supply conduit 116 connecting the reservoir 54 outlet 117 to the intake side of the pump P. The hydraulic output side of the pump P is connected by a conduit 118 to the inlet-outlet port 84 of the chamber 52. Another tube 120 is connected at one end with the chamber 52 inlet-outlet port 82 and to the fluid reservoir 54 inlet 124 at its other end. A second two-position valve device 122 is interposed in the conduits 118 and 120 to control the direction of flow from the pump P and from the inlet-outlet ports of the chamber 52 and return the hydraulic fluid to the reservoir return port 124. An adjustable pressure release or relief valve R is interposed in a bypass conduit 126 connected at its respective ends with the conduits 118 and 120 between the pump P and the two-position valve 122 for the purposes readily apparent.

Solenoids 128-130 and 132-134 are connected respectively with the two-position valves 110 and 122 with one terminal of each solenoid grounded. A pair of normally open limit switches 136 and 138 are disposed in spaced-apart relation in the path of and at the respective end limits of travel of the piston rod 66 to be contacted and closed by the stop 72 when the piston rod approaches its limit of travel in respective directions. A wire 140 connects a source of electrical energy, not shown, with one terminal of each of the limit switches 136 and 138. A second wire 142 is connected at one end portion with the solenoids 130 and 134 and is connected at its other end in series with the wire 140 through the limit switch 136. Another wire 144 is similarly connected at one end portion with the solenoids 128 and 132 and at its other end in series with the source wire 140 through the limit switch 138.

OPERATION

Assuming the pump 25 is operating and the piston rod 66 is moving toward the right, as viewed in FIG. 2, fluid, under pressure in the main cylinder 48 at its end portion between the piston 60 and end plate 34, flows out of the inlet-outlet port 74 through the conduit 88, check valve 94 to the feed header 98 and into the container 12. Reject fluid under proportionate pressure from the reject fluid header 106 flows through the conduit 104, in the direction of the arrows, into the booster chamber 50 through its inlet-outlet port 80 forcing the piston 62 toward the right, as viewed in the drawings, and supplementing the force applied to the main chamber piston 60. The reject fluid in the chamber 50, to the right of the piston 62, is exhausted to waste through the secondary conduit 108 in the direction of the arrows. During this time the pump P is forcing hydraulic fluid 56 at constant pressure through the hydraulic conduit 118 into the hydraulic chamber 52 through its inlet-outlet port 84 while hydraulic fluid in the other end of the chamber 52 is returned to the reservoir 54 through the hydraulic conduit 120. The hydraulic pump P pressure output control 145 is either manually set, for a predetermined pressure output of the pump P or is connected, as by tubing, not shown, with the main conduit 96 according to the type of hydraulic pressure compensated pump used. When the piston rod approaches the end of its travel to the right, as viewed in the drawings, the stop 72 closes the limit switch 138 energizing the solenoids 128 and 132 thus simultaneously shifting the two-position valves 110 and 122 so that the direction of flow of fluid to and from the respective chambers 48, 50 and 52 is reversed and continues, thus moving the respective piston toward the left, until the stop 72 contacts and closes the limit switch 136 by movement of the piston rod 66 toward the left, as viewed in FIG. 2. When the limit switch 136 is closed it energizes the solenoids 130 and 134 thus shifting the two-position valves 110 and 122 to their position at the beginning of this cycle of operation. Obviously the two-position valve devices may be controlled by mechanical means, such as linkage, not shown, actuated by the piston rod 66 for shifting the two-position valves, if desired. Similarly other type valve control means may be used, such as piston equipped pneumatic or hydraulic valves replacing the limit switches and solenoids, respectively.

Obviously the invention is susceptible to changes or alterations without defeating its practicability, therefore, I do not wish to be confined to the preferred embodiment shown in the drawings and described herein.

Claims

I claim:

1. A hydraulic pumping system, comprising:

a plurality of axially aligned cylinders forming a like plurality of pumping chambers each having inlet-outlet ports and each having a piston therein;

a piston rod common to all said cylinders and connected with each said piston for reciprocating said pistons in unison;

main conduit means connected for directly receiving the fluid pumped from one of said chambers;

a varying load device having an inlet connected to the main conduit means whereby a constant fluid pressure is established in the main conduit means,

said load device having an outlet discharging a fluid stream under pressure proportionate to the fluid pressure established in said main conduit means;

second conduit means having a first valve device therein connecting the pressurized fluid stream with a second one of said chambers and for discharging said latter fluid after passing into and out of said second chamber;

hydraulic pump means;

hydraulic conduit means having a second valve device therein connecting said hydraulic pump means with a third one of said chambers; and,

valve control means connected with said valve devices and actuated by said piston rod as it approaches the end of its movement in respective directions for driving the pistons in said second and said third chambers in a reciprocating action.

2. The pumping system according to claim 1 in which said hydraulic pump means includes:

a pressure compensated hydraulic pump for driving the piston in said third chamber and maintaining the fluid pressure in said main conduit means constant.

3. The pumping system according to claim 2 in which the first and second valve device each comprises:

a two-position valve.

4. The pumping system according to claim 3 in which one end portion of said piston rod projects beyond one end of said axially aligned cylinders and said valve control means includes:

a stop secured to said one end portion of said piston rod; and,

valve shifting means connected with each said two-position valve and actuated by said stop in response to longitudinal reciprocating movement of said piston rod for shifting said two-position valves in unison with each other.

5. The pumping system according to claim 2 in which said pressure compensated hydraulic pump is provided with a pressure output control responsive to the fluid pressure in said main conduit means.

6. The pumping system according to claim 2 in which said pressure compensated hydraulic pump is provided with a manually adjustable pressure output control.

7. In combination with a reverse-osmosis device including a container having an inlet opening for receiving a constant pressurized flow of supply fluid and having an outlet opening discharging a constant flow of reject fluid under pressure proportionate to the supply fluid pressure, the improvement comprising:

a plurality of axially aligned cylinders forming a like plurality of pumping chambers each having inlet-outlet ports and each having a piston therein;

a piston rod common to all of said cylinders and connected with each said piston for reciprocating said pistons in unison;

main conduit means connected for directly receiving the fluid pumped from one of said chambers;

second conduit means having a first valve device therein connecting the outlet opening of said container with a second one of said chambers and for discharging the reject fluid after passing into and out of said second chamber;

hydraulic pump means;

hydraulic conduit means having a second valve device therein connecting said hydraulic pump means with a third one of said chambers; and,

valve control means connected with said valve devices and actuated by said piston rod as it approaches the end of its movement in respective directions for driving the pistons in said second and third chambers in a reciprocating action.

8. The combination according to claim 7 in which said hydraulic pump means includes:

a pressure compensated pump responsive to the fluid pressure in said main conduit means for driving the piston in said third chamber and maintaining the fluid pressure in said main conduit means constant.

9. The combination according to claim 8 in which the first and second valve devices each comprises:

a two-position valve.

10. The combination according to claim 9 in which one end portion of said piston rod projects beyond one end of said axially aligned cylinders and said valve control means includes:

a stop secured to said one end portion of said piston rod; and,

valve shifting means connected with each said two-position valve and actuated by said stop in response to longitudinal reciprocating movement of said piston rod for shifting said two-position valves in unison with each other.