COMBINED PUMP AND ENERGY RECOVERY TURBINE

Abstract

The combined pump and energy recovery turbine includes at least one fluid flow pressurizing a sliding vane pump and a sliding vane energy recovery turbine that recovers energy from a second fluid flow, such as the brine discharge from an RO seawater desalination system. A cylindrical rotor has two sliding vanes in respective slots, the rotor being concentrically disposed within an oval-shaped enclosure defining two mirror image crescent-shaped chambers, each chamber having inlet and outlet passageways. The first chamber pressurizes the first fluid flow, and the second chamber functions as a second outflow-driven energy recovery turbine, thus enabling the single rotor device to operate as a pressurizing pump on the first fluid flow, and second outflow-driven energy recovery turbine recovering energy from the pressure drop in the second fluid flow.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to fluid pumps and turbines, and particularly to a combined pump and energy recovery turbine that may be used, e.g., in a desalination plant for pumping seawater through a reverse osmosis membrane.

2. Description of the Related Art

Large seawater reverse osmosis (SWRO) systems are prevalent in areas that do not have natural fresh water sources, such as streams and lakes. While the efficiency of an SWRO exceeds many other desalination methods, a substantial amount of energy is still required in SWRO plant operations. The reverse osmosis chamber needs to have a supply pump feeding its chamber for continuous output of permeate (fresh water). Booster pumps are often connected to some sort of work exchanger that captures fluid pressure from high-pressure brine output of the SWRO promise to increase efficiency of the system and lower the cost of operations. A more efficient work exchanger would be desirable.

Thus, a combined pump and energy recovery turbine solving the aforementioned problems is desired.

SUMMARY OF THE INVENTION

The combined pump and energy recovery turbine is a rotary sliding vane unit that can operate as a main system pump pressurizing a system destination, such as an RO (reverse osmosis) chamber, the pumping unit incorporating an energy recovery expander for reducing the operating cost by recovering energy from a second flow that may be an unwanted byproduct from the process, for example, brine discharged at high pressure from an RO seawater desalination system. The apparatus is a hydraulic pump mechanism suitable to serve as the first input pump of an RO system. The unitary device incorporates an energy recovery expander that recovers energy from the brine output flow of the RO system. The device may include a hydrodynamic lubrication means for sliding vanes in physical contact with its pump chamber. The pump chamber walls have rotor slots that reduce frictional losses through the device and, thus, energy recovery efficiency is improved.

These and other features of the present invention will become readily apparent upon further review of the following specification and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a combined pump and energy recovery turbine according to the present invention being used in energy recovery mode for a seawater RO system, the combined pump and turbine having multiple rotors.

FIG. 2 is a perspective view of a combined pump and energy recovery turbine according to the present invention.

FIG. 3 is a perspective view of the combined pump and energy recovery turbine of FIG. 2, shown with a portion of the casing broken away and partially in section to show details thereof.

FIG. 4 is an exploded, perspective view of the combined pump and energy recovery turbine of FIG. 2.

FIG. 5 shows a section view of a combined pump and energy recovery turbine according to the present invention, showing the elliptical cross section of the pump chamber and two sliding vanes disposed therein.

FIG. 6 shows a section view of another embodiment of the combined pump and energy recovery turbine according to the present invention, showing the elliptical cross section of the pump chamber and four sliding vanes disposed therein.

Similar reference characters denote corresponding features consistently throughout the attached drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The combined pump and energy recovery turbine unit 10, as shown in FIGS. 1, 4, 5 and 6, comprises a fluid turbine module that includes at least one central cylindrical rotor 47 having a pair of vanes 24 as depicted in FIG. 5, or two pairs of vanes as another embodiment, as depicted in FIG. 6, mounted therein within diametrically opposed slots 49. As the rotor 47 rotates, the vanes 24 slide outwardly under centrifugal force. As most clearly shown in FIG. 5 and FIG. 6, the rotor(s) 47 is (are) mounted within an elliptical or oval-shaped housing 30 that constrains the amount of outward travel of the vanes 24 within the slots 49 according to the elliptical or oval shape of the inner wall of housing 30. Thus, the vanes 24 slide radially inward and outward. The vanes 24 are at a maximum distance from one another when oriented with the major axis of the elliptical housing 30, and the vanes 24 are closest to one another when oriented with the minor axis of the elliptical housing 30. As shown in FIG. 2, fluid turbine modules 13a, 13b, 13c, and 13d can be stacked in coaxial alignment with each other. The modules 13a, 13b, 13c, and 13d each have the centrifugally operated sliding vanes 24. When coaxially coupled, the rotor assemblies of modules 13a, 13b, 13c, and 13d define equal relative vane phase angle with respect to each other, the phase angle being equal to 180° divided by the number of rotors 47 in the system 10.

Referring to FIGS. 1 and 2, seawater is fed to a reverse osmosis system 40 by a seawater supply pump 34 and feed pump 38. The pressurized brine output is fed to the high-pressure (HP) brine inlet 18 of the first turbine module 13a, which drives rotation of each of the turbine modules 13a through 13d in the stack. Part of the initial seawater flow does not go to the feed pump 38, but is diverted into a low pressure (LP) feed inlet 16 of the combined pump and energy recovery turbine 10, and the rotation of the rotor(s) 47 caused by the high pressure brine driving the turbine portion of the unit causes the seawater to be pumped through the pump portion of the unit 10, and then to the reverse osmosis system with the aid of an additional booster pump 36 (shown in the block diagram of FIG. 1). The combined pump and energy recovery turbine 10 utilizes output brine pressure of the reverse osmosis unit 40 to drive the turbine to aid in the pumping of the seawater. The combined pump and energy recovery turbine 10 therefore converts the pressurized fluid flow of the brine to an additional source of seawater pumping energy.

The multi-rotor, multi-chamber assembly shown in FIGS. 1-4 includes at least one cylindrical rotator drum 47 having diagonal slots 49, which receive respective sliding vanes 24. As most clearly shown in FIG. 5 and FIG. 6, a rotor assembly 47 is coaxially disposed within a corresponding oval-shaped housing 30 that, in combination with the rotor 47, defines two-mirror image crescent-shaped chambers 99a and 99b. Each chamber 99a, 99b is connected to an intake manifold passageway (header), e.g., 51a, 51c and a discharge manifold passageway (header), e.g. 51b, 51d, the intake and discharge passageways being at opposite ends of the crescent-shaped chambers 99a, 99b. The intake and discharge headers 51a through 51d are fluid passageways defined in the oval-shaped housing body 30, the fluid passageways extending into the pump chambers 99a, 99b. The housing modules 13a, 13b, 13c, and 13d stack against each other in a coaxial configuration, the cylindrical rotor assemblies 47 being disposed inside the oval shaped central axial openings defined by the stacked modules 13a, 13b, 13c, and 13d. The last module 13d is sealed by a terminal endplate 45.

A faceplate 12 covers the first module 13a. The faceplate 12 has connecting ports 14, 16, 18, and 20, which extend into the inlet and outlet headers 51a through 51d. A HP feed outlet port 14 is connected to the HP feed outlet header 51d. A LP feed inlet port 16 is connected to the LP feed inlet manifold passageway (header) 51c. An HP brine inlet port 18 is connected to the HP brine inlet manifold passageway (header) 51a. Lastly, an LP brine outlet port 20 is connected to the LP brine outlet manifold passageway (header) 51b.

It should be understood that as a vane 24 in the rotor assembly 47 sweeps through a respective chamber 99a or 99b, the vane 24 divides the chamber into an intake sub-chamber at the trailing side of the vane and a discharge sub-chamber at the leading side of the vane 24. Thus, the combined pump and energy recovery turbine 10 is powered in this manner. HP brine water travels through the HP brine water inlet port 18 and into the connected inlet header 51a to thereby enter into the corresponding crescent-shaped chamber 99a, which may be referred to as the turbine chamber 99a or turbine portion of the unit 10. High pressure of brine water on vane 24 in contact with the inner wall of the crescent-shaped chamber 99a, fed by brine water inlet header 51a, causes rotary action of rotor 47, the vane 24 sweeping through the sub-divided crescent-shaped volume, thereby decreasing the pressure of the HP intake fluid as it travels toward the low pressure brine water outlet header 51b. The high-pressure brine water is expanded and displaced by the sweeping sliding vane 24 through the discharge port 20 in communication with discharge header 51b at lower pressure.

Conversely, LP seawater travels through the LP seawater inlet port 16, through the connected inlet header 51c, and into the corresponding crescent-shaped chamber 99b, which may be referred to as the pump chamber 99b or pump portion of the unit 10. The rotary action of the rotor 47 causes the vane 24, which is in contact with inner wall of the crescent-shaped chamber 99b, to sweep through the sub-divided crescent-shaped volume, thereby increasing the pressure of the intake fluid as it travels toward the high pressure outlet header 51d. The high pressure seawater exits via the outlet header 51d, and then through the HP feed outlet port 14. As shown in FIG. 1, this flow is directed to a booster pump 36, which feeds the SWRO 40.

To help guide rotary motion of the vanes 24, machined cam tracks may be formed along the inner wall of oval shaped housing 30. The vane outer tips may then engage the oval shape cam tracks formed in the chamber inner wall. Inlet manifold passageways 51a, 51c are arranged in the crescent-shaped chamber proximal to a tapered end of the housing 30, and outlet passageways 51b, 51d are arranged proximal to an opposing end of the housing 30. Such an arrangement results in flow from inlet to outlet in a counter current direction within the housing module of the combined pump and energy recovery turbine 10.

As shown in FIG. 3, a power shaft 22 connected to the rotor 47 extends through the faceplate 12 and may be used to either provide auxiliary mechanical power or to receive auxiliary mechanical power. In the case where no auxiliary mechanical power is supplied, the outlet pressure from the HP feed outlet port 14 is less than the supply pressure at the HP brine inlet port 18, the combined pump and energy recovery turbine 10 operates in energy recovery mode. And in this case, an external booster pump 36 is needed to augment the pressure to the level of the discharge pressure of mean feed pump 38.

Optionally, the combined pump and energy recovery turbine 10 can also receive auxiliary mechanical power via power shaft 22. In the case where the supply pressure at the HP brine inlet 18 is less than the HP feed pressure at outlet port 14, the combined pump and energy recovery turbine 10 operates as a combination energy recovery turbine and booster pump mode. And in this case, an external booster pump 36 may not be needed to augment the pressure to the level of the discharge pressure of mean feed pump 38.

Referring to FIG. 3, channels 300a and 300b are longitudinally disposed along the pump modules 13a, 13b, 13c, and 13d, to be used together with tie rods (not shown) for assembly of said modules as one unit. Additionally, a portion of high-pressure fluid can be re-routed to a pressure cavity in the chambers 99a, 99b, the pressure cavity communicating the pressure cavity re-routed stream to an inner portion of the slots 49 of rotor 47. Tips of vanes 24 have openings 303 through which re-routed high pressure fluid can travel and lubricate the vanes 24 for reduced frictional contact with the chamber walls.

Thus, in the exemplary SWRO combined pump and energy recovery turbine 10, a first chamber 99a and corresponding one of the sweeping sliding vanes 24 operate as an energy recovery-expander receiving high pressure brine from an RO vessel and disposing the spent brine to waste, thereby recovering energy used for pressurizing seawater in a second chamber 99b. The second chamber 99b and its corresponding one of sweeping sliding vanes 24 operate as a pump for pressurizing flow, such as seawater feed in the RO plant. The system 10 can be optimized for application in a seawater RO system to provide benefits including simplicity, compact machine size and low capital and operating costs. Long term reliability can be enhanced by employing hydrodynamic lubrication of the sliding vanes 24.

While a single rotor 47 produces a generally sinusoidal fluid flow through the pump portion of the unit, four rotors 47 that are coaxially coupled in such a manner that their vanes 24 are staggered or equally spaced radially produce fluid flow at a generally constant rate through the pump portion of the combined pump and energy recovery turbine unit 10.

Another embodiment of the combined pump and energy recovery turbine is a turbo-compressor where the first fluid flow is low pressure steam introduced through the first inlet port and the second fluid flow is high pressure steam introduced through the second inlet port. Here, the purpose of the device is compress the low pressure steam to a higher pressure using the pressure energy of available high pressure steam.

Another embodiment of the combined pump and energy recovery turbine is a turbocharger for power plants where the first fluid is air introduced at atmospheric pressure through the first inlet port and the second fluid flow is high pressure exhaust gases from the plant introduced through the second inlet port.

Still another embodiment of the combined pump and energy recovery turbine is a turbo-vacuum pump where the first fluid flow is low pressure gas or vapor from a low pressure chamber under vacuum introduced through the first inlet port and the second fluid flow is high pressure steam introduced through the second inlet port. Here, the purpose of the device is maintain vacuum or remove unwanted gases from a process chamber using the pressure energy of available high pressure steam.

It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims.

Claims

1. A combined pump and energy recovery turbine, comprising: at least one cylindrical rotor having an outer axial wall defining a periphery of the cylindrical rotor;substantially radially opposed slots extending from proximate an axial center of the rotor outward through the outer wall of the rotor;a corresponding sliding vane disposed in each of the slots, the sliding vane including an outer tip, the slots constraining each of the sliding vanes to inward and outward sliding displacement guided by the slots, each of the sliding vanes being slidable outward beyond the peripheral outer wall of the rotor;a modular housing having at least one oval-shaped opening formed therethrough, the at least one rotor being rotatably disposed through the at least one oval-shaped opening in axial alignment with the modular housing;an end plate affixed to the housing in coaxial alignment with the rotor, the end plate and the rotor defining first and second crescent-shaped chambers within the at least one oval-shaped opening;a first inlet manifold passageway disposed in the modular housing, the first inlet manifold passageway opening into the first crescent-shaped chamber;at least one first inlet port connected to the first inlet manifold passageway;a first outlet manifold passageway disposed in the modular housing, the first outlet manifold passageway opening into the first crescent-shaped chamber;at least one first outlet port connected to the first outlet manifold passageway, wherein the first inlet and outlet passageways, the at least one first inlet port, the at least one first outlet port, and the first crescent-shaped chamber define a first fluid flow path;a second inlet manifold passageway disposed in the modular housing, the second inlet manifold passageway opening into the second crescent-shaped chamber;at least one second inlet port connected to the second inlet manifold passageway;a second outlet manifold passageway disposed in the modular housing, the second outlet manifold passageway opening into the second crescent-shaped chamber; andat least one second outlet port connected to the second outlet manifold passageway, wherein the second inlet and outlet passageways, the at least one second inlet port, the at least one second outlet port, and the second crescent-shaped chamber define a second fluid flow path counter to the first fluid flow path;wherein a first fluid flow introduced at low pressure through the first inlet port to the first crescent-shaped chamber may be pumped out through the first outlet port at a higher pressure by rotation of the at least one rotor, and a second fluid flow introduced at high pressure through the second inlet port to the second crescent-shaped chamber produces a turbine drive of the vanes and the at least one rotor, thereby recovering energy to continue pumping through the first crescent-shaped chamber.

2. The combined pump and energy recovery turbine according to claim 1, further comprising an oval-shaped cam track formed in said end plate, the outer tip of said sliding vane engaging said oval-shaped cam track.

3. The combined pump and energy recovery turbine according to claim 1, further comprising: a power shaft connected to said rotor for power transmission to and from said rotor.

4. The combined pump and energy recovery turbine according to claim 1, further comprising: for each of said slots, a pressure cavity disposed therein, the pressure cavity accepting lubricating fluid therein;a plurality of lubrication openings disposed in the outer tip of said sliding vane, the openings extending into a hollow portion of said vane, the hollow portion being in operable communication with the pressure cavity to expel the lubricating fluid from the lubrication openings during operation of the turbine.

5. The combined pump and energy recovery turbine according to claim 4, further comprising: an external passageway conveying the lubricating fluid under high pressure to said pressure cavity.

6. The combined pump and energy recovery turbine according to claim 4, further comprising: an internal passageway conveying the lubricating fluid under high pressure to said pressure cavity.

7. The combined pump and energy recovery turbine according to claim 4, further comprising: a central channel disposed in said rotor to form said pressure cavity; andconnecting radial passageways operable with an inner portion of the rotor slots to convey the lubricating fluid.

8. The combined pump and energy recovery turbine according to claim 4, further comprising a circular channel disposed in said end plate to form said pressure cavity, the circular channel being operable with an inner portion of the rotor slots to convey the lubricating fluid.

9. A combined pump and energy recovery turbine assembly, comprising a plurality of combined pump and energy recovery turbine units according to claim 1 coaxially connected together to form the assembly, thereby defining an equal relative vane phase angle with respect to each of the units, the phase angle being equal to 180° divided by the number of rotors in the coaxially connected units.

10. The combined pump and energy recovery turbine assembly according to claim 9, further comprising means for receiving rotational drive from an external motor.

11. The combined pump and energy recovery turbine assembly according to claim 9, wherein the first fluid flow is of seawater, the first outlet port is adapted for feeding a seawater intake of a main seawater chamber of a reverse osmosis desalination system, the second fluid flow is of brine from the chamber of the reverse osmosis desalination system, and the second outlet port is adapted for feeding a brine disposal unit.

12. The combined pump and energy recovery turbine assembly according to claim 9, wherein the first fluid flow is of seawater, the first outlet port is adapted for feeding an intake of a booster seawater pump, the second fluid flow is of brine from a chamber of a reverse osmosis desalination system, and the second outlet port is adapted for feeding a brine disposal unit.

13. The combined pump and energy recovery turbine according to claim 1, wherein the at least one cylindrical rotor comprises one pair of slots engaged by the slots' respective corresponding vanes.

14. The combined pump and energy recovery turbine according to claim 1, wherein the at least one cylindrical rotor comprises two pair of slots engaged by the slots' respective corresponding vanes.