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Title:
PRESSURE EXCHANGER UNIT (PE) FOR SAVING ENERGY
Document Type and Number:
WIPO Patent Application WO/2020/192857
Kind Code:
A1
Abstract:
The present invention relatesto a energyrecovery unit in desalination plants or other applications as (oil & gas), wherein the energy of the pressure exchanger PE is provided by the exchange of pressure between the 1st fluid, which can be the high-pressure concentrated water from the desalination plant output, and the 2ndfluid, which can be the low-pressure feeding water to the desalination plants, wherein the 1st fluid entersinto the pressure exchanger through HPI and the pressure is transferred to the 2nd fluid through the pressure exchanger. Thus, the pressure of the 2ndflow is raised and pushed through HPO to RO desalination membrane. The course of this cycle is as follows: (HPI / E / 44 / X45 / 46 / C / 55 / X56 / 57 / A/HPO) and 2nd fluid is entered into pressure exchanger through LPI and 1st fluid is swiped out with low pressure (after exchanging pressure with 2nd fluid) from the pressure exchanger through LPO. The course of this cycleis as follows: (LPI / A / 54 / X52 / Y52 /Z52 / 51 / C / 47 / Z48 / Y48 / X48 / 50 / E / LPO).PE consists of stationary cylinder "C" and rotating discs "A,B,D&E".

Inventors:
SWIDAN MOHAMED (EG)
Application Number:
PCT/EG2019/000008
Publication Date:
October 01, 2020
Filing Date:
March 26, 2019
Export Citation:
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Assignee:
SWIDAN MOHAMED ABDELWAHAB WAHBY (EG)
International Classes:
F04F13/00; B01D61/06; F15B3/00
Foreign References:
CN101440828A2009-05-27
US20130294944A12013-11-07
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Claims:
CLAIMS

1. A fluid pressure exchanger PE includes a stator cylinder part C ,side rotor discs A, B, D and E, side-end manifolds that contain fluid inlets and outlets, and a source of rotory motion.

2. The pressure exchanger according to claim 1, wherein the stator cylinder part is a fixed cylinder C including longitudinal channels 60 in the entire circumference of the circle, wherein the longitudinal channels 60 can be replicatedon the same disc with different diagonal dimensions, and axial channelto pass the rotorshaft 58 , on the edges of the stator cylinder part C there are cavities for housing the rotor discs A, B, D and E.

3. The pressure exchanger according to anyone of claims 1 or 2, wherein the stator cylinder part C has a terminalmanifolds at both ends 61 - 62.

4. The pressure exchanger according to anyone of claims 1 to 3, wherein the manifold61 has an inlet for the entry of high-pressure lstfluid (HPI) and an outlet for discharge of the same fluid after pressure exchange and its exit by low pressure LPO.

5. The pressure exchanger according to anyone of claims 1 to 3, wherein the manifold 62 has an inlet for low-pressure 2nd fluid LPI and an outlet for discharge of the same fluid with high pressure and exiting through the HPOafter pressure exchange between the two fluids.

6. The pressure exchanger according to anyone of claims 1 to 5, wherein the high-pressure fluid is 1st fluid(the brine fluid in one of the embodiments) drained out of the membranes of the desalination unit and low-pressure fluidis the 2nd fluid(feed fluidin one of the embodiments) taken from the source.

7. The pressure exchanger according to claim 4, wherein the high-pressure fluid inlet HPI allows the first fluid to enter at a inclination anglein case thefluid pressure is used to rotate the discs (completely or wih aid of external rotoray device).

8. The pressure exchanger according to claim 4, wherein the high-pressure fluidinlet HPI allows the first fluid to enter without anyanglein case external motion source is used to rotate the discs.

9. The pressure exchanger according to claim 5, wherein the low-pressure fluidinlet LPI allows the first fluid to enter at ainclination anglein case the fluid pressure is used to rotate the discs, reducing the rotation energy consumbtion.

10.The pressure exchanger according to claim 5, wherein the law-pressure fluid inletLPI allows the entry of the first fluid without any angle in case external motion source is used to rotate the discs.

1 l .The pressure exchanger according to anyone of claims 1, 2, 4 or 7, wherein the disc E is added to the pressure exchanger if fluid pressure is used to rotate the set of discs, wherein the high-pressure fluid (1st fluid) flows from the HPI at aninclination/tangential angle to rotate the discE, thus it drives shaft 58 connected to the other discs, ensuring that all discs are rotating at the same rotation speed.

12. The pressure exchanger according to anyone of claims 1 , 2, 5 or 9, wherein the terminal disk A is added to the pressure exchanger if fluid pressure is used to rotate the group discs, wherein the low-pressure fluid (2nd fluid) flows from the LPI at an inclination/tangential angle to rotate the discA, thus assist the disc E in rotating the drive shaft 58 connected to the rest of the discs, ensuring that all discs are rotated at the same rotation speed.

13. The pressure exchanger according to anyone of claims 1, 2, 11 or 12, wherein terminal discs A and E allow the fluid to pass through grooves, regardless the shape of the grooves are.

14.The pressure exchanger according to anyone of claims 1 or 2, wherein disc D is located in one of the terminalcavities of the stator cylinder part C.

15. The pressure exchanger according to anyone of claims 1 or 2, wherein disc D has a front face“D Face” containing complete or semi-fullgroove/s44 and 50 Both grooves 44 and 50 can be replicated on the same disc with different diagonal dimensions.

16.The pressure exchanger according to claim 15, whereinthe first high- pressure fluid passes through channel44.

17. The pressure exchanger according to claim 15, wherein the first fluid passes through channel 50after pressure exchange with low pressure.

18. The pressure exchanger according to anyone of claims 1 or 2, wherein disc D has a rear face“D Back”contains partial grooves 46 and 47, wherein each of the 46 and 47 groovescan be replicated on the same disc with different diagonal dimensions.

19.The pressure exchanger according to claim 18, wherein the second fluid with high pressure passes through the channel 46.

20.Pressure exchanger according to claim 18, wherein the second fluid passes through the channel 47 after pressure exchangewith low pressure.

21. Pressure exchanger according to any of claims 1 , 2, 15 or 1 1, wherein the disc D has two sides and during the manufacturing process each face can be manufactured as a separate disc then assembling the two discs together by any means possible. It can also be manufactured as a single disc with two different groove shaps.

22. Pressure exchanger according to any of claims 1 , 2, 15 or 18, wherein the disc D has a hole X45 (or a set of holes) in the groove 44 to connect the front face of disc“ D Face” with groove 46 in the rear side of disc“D Back”, through which the first fluid passes with high pressure.

23. Pressure exchanger according to any of claims 1, 2, 15 or 18, wherein the disc D has a hole X48 (or a set of holes), channel Y48 (or a set of channels) and a hole Z48 (or a set of holes) to connect groove 47 in the rear side of disc“ D Back” with groove 50 in the front side of the disc“D Face”, through which the first fluid passes with low pressure.

24. The pressure exchanger according to anyone of claims 1 or 2, wherein disc B is located in one of the terminal cavities of the stator cylinder part C.

25. The pressure exchanger according to anyone of claims 1 or 2, wherein disc B has a rear face“B Back”contains full or semi-full groove/s54 and 57, wherein each of the 54 and 57groovescan be replicated on the same disc with different diagonal dimensions.

26.The pressure exchanger according toclaim 25, wherein the low-pressure second fluid coming from LPI passes through groove 54.

27.The pressure exchanger according toclaim 25, wherein the second fluid passes through groove 57, after pressure exchange to come out with high pressure through HPO.

28. The pressure exchanger according to anyone of claims 1 or 2, wherein disc B has rear side“ B Back” contains partial grooves 51 and 55, wherein each of the 51 and 55grooves can be replicated on the same disc with different diagonal dimensions.

29.The pressure exchanger according to claim28, wherein the second fluid with low pressure passes through the groove 51 through LPI.

30.Pressure exchanger according to claim 28, wherein the second fluid passes through the groove 55 after pressure exchange with high pressure then to groove 57 and HPO accordingly.

31. Pressure exchanger according to any of claims 1, 2, 25 or 28, wherein the discB has two sides and during the manufacturing process each face can be manufactured as a separate disc then assembling the two discs together by any means possible. It can also be manufactured as a single disc with two different grooves' shapes.

32.Pressure exchanger according to any of claims 1, 2, 25, 28, 29 or 30, wherein the discB has a hole X52 (or a set of holes), channel Y52(or a set of channels), a hole Z52 (or a set of holes) to connect the groove 54 in the front side of the disc“B Face” to groove 51 in the rear face of disc“B Back”, through which the second fluid passes with low pressure.

33. Pressure exchanger according to any of claims 1, 2, 25, 28, 29 or 30, wherein the discB has a hole X56 (or a set of holes), groove 55 to connect the rear side of disc“B Back” with groove 57 in the front side of the disc“B Face”, through which the second fluid passes with high pressure to HPO.

34.Pressure exchanger according to any of claims 15, 16, 18, 19, 22, 25, 27, 28 or 30, wherein grooves 44, 46 and grooves 55 and 57 in the rotor discs B and D include steady high pressure along operation time, regardless their position; whether in top or in the bottom of the cycle.

35.Pressure exchanger according to any of claimsl5, 18, 20, 23, 25, 26, 27, 28 ,29 , 30 or 31, wherein grooves47, 50, 51 and 54 in the rotor discs B and D include steadylow pressure along operation time, regardless their position; whether in top or in the bottom of the cycle.

36.Pressure exchanger according to any of claimsl to 3, wherein the rotor cylinder C contains central channel, through which drive shaft 58 passes, without rotation of the cylinder part C.

37.Pressure exchanger according to any of claims 1 to 3, wherein the rotor cylinder C includes longitudinal channels 60, through which both fluids pass, as well as pressure exchange process, the longitudinal channels 60 can be replicated on the same disc with different diagonal dimensions.

38.Pressure exchanger according to claim 37, whereinthe internal size of the longitudinal channel 60 is the main parameter affecting the capacitance of the pressure exchanger, thus the total capacity can be increased by increasing the cross section area, lengths and number of the longitudinal channels 60.

39.Pressure exchanger according to claim 37, wherein the longitudinal channels60 can contain a free piston for the purpose of pressure exchange without the direct contact between the fluids.

40.The pressure exchanger according to claim 39, wherein the free piston moves freely within the longitudinal channels 60, and the longitudinal channels 60 contain bumpers that prevent the piston from escaping out of the channels.

41. The pressure exchanger according to anyone of claims 1 or 2, wherein the cylinder part C is fixed nonrotating, which greatly limits the mixing of the two fluids.

42.Pressure exchanger according to anyone of claims 1 or 2, wherein the cylinder part C and discs A, B, D & E are manufactured from any material (metal, non metal) and any other.

43. Pressure exchanger according to anyone of claims 1, 2, 7, 9, 11 , 12 or 13, wherein A, E discs are optional and added to the pressure exchanger in case the first fluid pressure is used to rotate the discs or aid the rotation device.

44.Pressure exchanger according to claim 1, wherein the source of rotational motion is optional in case of dispensing with discs A, E, and is used to rotate discs B, D through the rotation shaft 58.

45.The pressure exchanger according to anyone ofclaims 1 to 35, whereinB and D discs are separated by a fine clearance to reduce the loss of pressure and fluids.

46. The pressure exchanger according to anyone of claims 1 to 45, whereindiscs D, C, B, A can be replicated on both sides of the E disc in a symmetrical manner when double action is needed. In this case disc E will be dublicated. In other words it means to mirror the whole unit

Description:
Pressure Exchanger Unit for Saving Energy

SPECIFICATION

FIELD OF INVENTION

The present invention relates to apressure exchanger unit to save energybytransferring pressure fromfirst fluid to second fluid. More specifically, the present invention relates to an energy-saving unit that transmits energy from one fluid to another via rotary discs and a stator cylinder, both the cylinder and the discs containing channels and grooves.

BACKGROUND OF INVENTION

Desalination plants consume very high energy to generate the necessary pressure for feed water, and to force it to pass through the desalination membranes, thereby overcoming osmotic pressure. During the operation of the plant, there is a loss of much energy consumed, which exceeds 50% of the supply capacity consumed by the plant, and therefore the need for energy recovery to take advantage of wasted energy.

Desalination plants using reverse osmoses process is considered to be an energy intensive process due to high pressure of the membrane inlet stream .the energy in the brine flow is about 50% of the consumed energy by the whole plant that’s why many types of energy recovery devices is used in desalination plants to recover the energy of the brine flow by transferring the pressure from high pressure brine flow to the low pressure feed flow before sweeping the brine flow to the out fall. Different techniques for energy saving in desalination plants have addressed two main types.

First type: Turbine: which works by adding a turbine in one of two ways: a) Puttinga turbine on the same axis as the main pressure pump. As shown in Figure (1) b) Putting the turbochargers, which is is a booster installed on the high pressure pump line. As shown in Figure (2).

Second direction: Isobaric:

In which the pressure of brineflow from the desalination plant is transmitted to the feed flow entering the plant. The energy saving devices used in this technique are called pressure exchangers. This is done by one of the following methods:

• Using one or more hydraulic cylinders, as shown in Figure (3).

• Using rotor, as shown in Figure (4).

Several prior art documents have relates torotor pressure exchanger technique and methods of application, for example:

• US 4887942 (19 DEC. 1989)

• US 6537035B2 (25 MAR. 2003)

• US 2006/0037895 Al(23 FEB. 2006)

• US 2014/0128656 A1 (8 MAY 2014)

• US 2016/0062370 A1 (3 MAR 2016) • US 2017/0130743 A1 (11 MAY 2017)

• US 9976573 B2 (22 MAY 2018)

Rotor pressure exchangers include a rotating cylindrical body (25 cm to 40 cm length) with stator faces at both ends, and 4 holes for feed and discharge:

• HPI - High Pressure fluid Inlet

• LPO - Low pressurefluid outlet

• LPI - Low pressurefluidinlet

• HPO - High pressurefluid outlet

The holes are distributedon both sides, each side contains two holes (LPI,HPO& HPI, LPO)

The water enters the energy saving unit through one of the two sides at An inclined angle and with the pressure of the highly brine water coming out of the ROplant to meet the free cylinder which in turn begins to spin, during the cylinder rotation the pressure is transferred from high pressure brineflow to low pressure feed flow.

The general design of this type of energyrecovery units (pressure exchangers) is shown in figure (4).

Although this type of energy saver is the most efficient in the world, it has many disadvantages, notably:

• The sides are stator and the cylindrical part is freely moving, rotates within a stator(sleeve) with narrow clearance between them.

• Loss of pressure and flow occurs in the clearance between the stator (sleeve) and moving cylindrical parts. • The clearance between the moving cylindrical part and the stator(sleeve) should be as narrow as possible, as it increases the loss of pressure and flow leakage through it.

• As a result of fine clearance, there is a strong friction between the moving cylindrical part and the stator(sleeve), especially in the presence of impurities in the water entering, these impurities enter between the stator(sleeve) and the moving parts and cause erosion of the cylindrical part.

• The rotary cylinder part causes noise during rotation.

• The rotary cylinder part is usually made of ceramic, in order to reduce friction and increase efficiency. However, ceramics are damaged or broken if any small solid body enters with impurities inside the energy saver plant.

• The rotary cylindrical part is difficult to maintain, as it is avoided to completely removedfrom the stator(sleeve) for the difficulty of returning it to the same operating mode.

• The length of the cylindrical part can not be increased to a certain extent because the cylinder is subjected to slight clearance differencesduring manufacturing, which greatly affects performance and increases the amount of loss. Moreover, in the case of increasinglength, operating and friction problems may occur, which means that the energy supply capacity of theenergy saverplant is limited (maximum 68 m 3 / h), and rotates at high speeds, so large plants require a large number to be connected in parallel.

• The limited dimensions of the cylinder are also due to the control of the total weight of the cylinder, which increases the inertia forces, which may adversely affect the regularity of the rotation or increase the need for higher rotation energy. • The limited dimensions of the cylinder to avoid increasing the friction area and ununiformity of clearance along the cylinder and its (sleeve).

• The limited length to avoid increased maintenance difficulty, which sometimes requires the partial release of the cylindrical part out of the sleeve.

• The limited length to avoid the difficult of implementation, either for the cylindrical part or thesleeve casing at various manufacturing stages to adjust the clearance along the cylinder and its sleeve.

• The cylindrical part rotates at high speed to achieve an adequate flow to compensate for the short length of the rotary cylinder.

• pressure exchanger is cosidered tobe noisy during operation.

• Although the speed of rotation of the cylinder part is high, it can not be increased more than a certain limit due to the fine clearance and to avoid the rapid damage to the unit (pressure exchanger).

The above points show that the productivity of the plant is limited, and can not be increased from a certain limit.

INTRODUCTION

The current invention relates to an energy recovery device of isobaric type, exchanging the pressure between 1 st fluid (such as the brine flow) and 2 nd fluid (such as the feed flow). This energy recovery devicevaries from any other system, by making the cylindrical part stationary, and not a rotating cylindrical part as in case of other systems. This stator cylindrical part has longitudinal channels and rotary discs located on both ends, unlike the stator discs in other systems. These discs are rotated by the pressure ofbrine flowcoming out of the membrane or can be supplied by a external source for rotation, as will be explained in different embodiments of the present inventions.

Thissignificant exchange in the moving part through the movement of the discs rather than the rotary cylinder added significant advantages to the pressure exchanger PE, including ease of manufacturing, operation and maintenance, saving consumed energy for rotation of the moving parts and allowing the length of the cylindrical part to be increased. Through the power saver.

Further, the clearances between the discs and the casing are also very short in length compared to the rotating cylinder, which has a great effect in reducing the loss of pressure and flow leakage in the clearance, reducing inertia of rotating parts and also in prolonging the lifetime of the plantas well as increase its efficiency and durability.

DESCRIPTION OF DRAWINGS

Figure (5) shows example of complete system of a desalination plant using the energyrecovery unit from the isobaric type, showing the membrane desalination unit (RO membrane) and extracting the brine flow at 59 bar to enter the pressure exchanger (PX) from the High Pressure brine flow Inlet (HPI), source of feed flow (1), where the flow is pumped by pump (2)with a pressureof 3 bar to enter the pressure exchanger unit (PX) from the Low pressure feed flow Inlet (LPI). The brine flow is sweeped by low pressure from the Low pressure outlet (LPO) and the feeding flow is discharged by high pressure from the High pressure outlet (HPO) to the membrane desalination unit (RO membrane) through the booster pump (8), which compensates the lost pressure throughout the desalination membranes and the pressure exchanger. Figure (6) "Prior art": Reflects the basic idea of pressure exchangers of isobaric rotor type, which shows:

A: High pressure brine ilowenters to the pressure exchanger through (hole 56) and drained out with low pressurethrough (hole 52) of it after exchange the pressur in the feed flow -the manifoledincluding the holes 56& 52 is stator.

B: Low pressure feeding flowentersinto the pressure exchanger through (hole 48) and out of it to the RO membrane with high pressure through (hole 45) - the manifoled including the holes 48& 45 is stator.

C: Cylinder is a rotor part

In which high pressure brine flow enters the PX through HPI to be directed to the cylindrical rotor part C with a inclination angle, to force it to rotate and pass through longitudinal holes filled with feeder water that have been entered into the longitudinal streamsat low pressure throughLPI port.

As a result of the high pressure of the brine flow inside the longitudinal channels, thehigh pressurebrine flow will push the feed flow and transfer the pressure from the brine flow to the feed flow and push it out of the pressure exchanger with high pressure through the HPO to the RO membrane. This occurs during half the cycle of the cylindrical part C. In the second half of the cycle, the brine flow has lost its pressure and the pressure of the feed flow is higher than the pressure of the brine flow, which in turn drives the brine flow out of the system through the LPO.

During successive cycles of the cylindrical part, pressure exchange occurs between brine flow and feed flow. Figure (7) describes a desalination plant using the pressure exchanger PE. The general system of the plant is the same as the general system of the plant in Figure (5) with the replacement of the PX energy recovery described in the prior art with the PE energy recovery subject of thepresent invention.

Figure (8) describes the PE pressure exchanger subject of the present invention which consistes of: statorcy 1 indrical part C, rotor disc B front and rear views, rotor disc D front and rear views, rotor disc A and rotor disc E and fluid inlet and outlet ports (HPI/LPO/LPI/HPO) .

Figure (8 A) shows the rotor disc B front and rearviews, in addition to the facing of the stationary cylinder part C from the back, and the rotor disc A through which the 2 ndt fluid gets out with high pressure from HPO and the 2 nd fluid gets into (PE) through LPI with low pressure, disc A is optional.

Figure (8 B) describes the rotor disc D front and rearviews, and the facing of the stationary cylinder part C from the front and the rotor disc E, through which the 1 st fluid gets into with high pressure HPI and the 1 st fluid with low pressure through LPO, disc E is optional.

Figure (8 C) describes the assembly ofthe pressure exchanger PE, showing the stator cylinder part C, and at its ends there are the housing of the rotary discs, the longitudinal channelsof part Cthrough which the fluid passes and exchanging pressuretakes place, the rotary discs D & B appear on both ends, in addition to the optional discs A & Eand fluid inlet and outlet ports (HPI/LPO/LPI/HPO) .

Taking into consideration that the main job of the optional discs A & E is used as self rotating discs to rotate rotor discs D & B, or at least reducing the energy consumed for rotating discs D&B in case of using an external rotating device. Figure ( 9) shows the PE pressure exchanger without the optional A & E discs, showing the possibility of running the pressure exchanger without them, replacing them with a rotating device to rotatethe discs D & B.

DETAILED DESCRIPTION OF THE INVENTION

The present invention PE relates to pressure exchanger (energy recovery devices) from an isobaric type that includes a stator cylinder part C with longitudinal Channelsor tubes with cavities at both ends (as sleeves) housing the rotor discs. Rotor discs B&Dfor the entry and exit of both 1 st fluid and 2 nd fluid in order to exchange pressure between them inside the stator cylinder part C. In addition to optional discs A &E which designed to utilize the fluids at a inclination (tangential) angleto rotate the disks or at least save the energy consumed to rotate them if external rotating device is needed.

As shown in the figures7,8 and 9, the 1 st fluid gets into the pressure exchanger from port HPI with high pressure from the front side of the rotor disc“D Face” and passes through it to the back side of“D Back”.

Figures (8 B) and (9 B)describe that the front side ofthe disc“D Face” has groove 44 which is“circumferential or complete”, in which the 1 st fluid (such as brine flow) passesthrough it to a small hole X45 (or a set of holes) through which the brineflow transfers from the front side to the rear side, to crescent(or other shape) groove46, for preserving the pressure of the fluid and directing it towards the cylinder“stationery part“ C.Further, there are other crescent shape (or other shape) groove 47in the back side of“D Back”, Where the brine flow is received after it gets out from the stator cylinder part, where pressure exchange between it and the 2 nd fluid (such as feed flow) takes place, as it gets out with low pressure and passes through the crescent (or other shape) Channels 47 to the front side of the disc“D Face” through small hole Z48 (or a set of holes), Channels Y48 (or a set of Channels) and small hole X48 (or a set of holes) to pass into the internal Channels 50 which is (circumferential or complete) and from them to LPO.

It is shown from the figures that the pressure in grooves 46and 47 on the rear side of disc“DBack”is steady. For instance, Channel 46 has steady high pressure along the whole operation, whether at the top or in the bottom of the unit, as well as channel 47has steady low-pressure along the whole operation, regardless the position, whether at the top or in the bottom. Therefore, the pressure between the l st fluid and the 2 nd fluid is exchanged along with steadinesscylinder part C (stationary).

Figures (8 A) and (9 A) shows the front and rear sides of the B disc, where the 2 nd fluid enters by a low pressure into the LPI to the front side of the disc“B Face”, where there is a groove 54 which is“circumferential or complete” for entry of 2 nd fluid (feedflow with low pressure) to pass through a small hole Z52 (or a set of holes) and a channel Y52 (or a set of Channels) and a small hole X52 (or set of holes) for the back of the disc“B Back” for groove 51 to pass through the Channels of stator cylinder C in order to sweep the 1 st flow of low pressure out of the pressure exchanger PE through grooves 47&50 in disc D. groove 55on the back side of the disc“B Back”, whichreceives the 2 nd fluid after pressure exchangingprocess to pass through the X56 hole (or a set of holes) to the groove 57 in the front face of the disc“B Face” to get outside the pressure exchanger PE with high pressure through HPO,thus directed to the booster pump and membrane desalination unit.

It is shown from the Figures 8 & 9that grooves 51 and 55 on the back of the disc “B Back” disk has steady pressure along the whole operation. For instance, groove 51 has steady low pressure whether at the top or in the bottom along the whole operation,, as well as groove 55 hassteadyhigh pressure regardless of its position, whether at the top or in the bottom position. Therefore, the pressure between the 1 st fluid and the 2 nd fluid is exchanged along with steadiness of the cylinder part C (stationary).

Both discs B and D are connected to each other through a rotor shaft 58 to ensure that they are rotating together. It is necessary to connect both discs together to ensure proper exchange of pressure. The rotorshaft 58 passes through the axis of the stator cylinder part C.in addition, in the case of the use of discs A and E they are connected to the same rotor shaft 58.

It is clear from the above that the rotation of the external discs B and D is the control of pressure exchange process inside the unit, thus it is necessary to have a motion source to runs the rotor shaft 58 and therefore rotate both the disc B and disc D. Neither the rotorshaft 58 nor the B and D discs need high rotationenergy, this is due to low friction between the discs and the housing, wherein the thickness of the discs is limited, therefore only a small motor is needed to rotate them or any suitable motion source supply.

The pressure of the water entering the pressure exchanger can be used to rotate the discs by using additional discs A & E. The 1 st fuidenters through discE with high pressure and inclination (tangential) angle causing the rotation of the corresponding disc D, then the rotation of disc B, due to being on the same axis. Other holes are there for discharge of the 1 st fluidcoming out from the unit at low pressure LPO.

On the other side of unit is the disc A, through which 2 nd fluid enters at low pressure, this low pressure generates light motion helps in the rotation of the discs B and D in the same way by entering the 2 nd fluid on the disc with inclination(tangential ) angle that helps the corresponding disc B to rotate. In addition, on the disc A there are holes fordischarging the 2 nd fluidthat comes out from the pressure exchanger at high pressure to direct it to the membrane desalination unit.

According to the designing conditions of each unit, a small engine (or any appropriate motion source) is used to rotate the discs B and D, or to rotate them without external motion source by making use of the hydraulic motion resulting from the discs A & E or by using both methods.

Pressure exchanger as shown above is distinguished from any other isobaric pressure exchanger by several characteristics, the most significant is the easiness of manufacturing, lower losses in the clearance (as the clearance is only located along the discs, not along the cylinder part) .The pressure exchanger can work under any pressure and any conditions due to the ability to control the length and cross section area of the cylinder part, as well as the number of the internal holes (channels) according to available conditions.

The steadiness of the cylinder part C reduces the mix between 1 st fluid and 2 nd fluidas a result of the contact between them. In one embodiments of the present invention, a free piston can be put inside every longitudinal channel in the cylinder part C to prevent the contact between the two fluids and at the same time allows pressure exchange between them. METHOD OF OPERATION OF PRESSURE EXCHANGER ( PE)

The l st fluid (coming out from the membrane desalination unit) enters to the pressure exchanger from HPI, at the same time the 2 nd flow enters from LPI, wherein these portsare located in the manifolds of the pressure exchanger.

In one embodiment of the present invention, the 1 st fluid enters from HPI on the disc D and the 2 nd fluid enters from LPI on the disc B, wherein both discs B and D are on the same rotation axis and with the same rotation shaft 58, which is connected to the source providing rotary motion to the unit.

In another embodiment, the 1 st fluid enters from HPI with a inclination (tangential ) angle on the disc E and the 2 nd fluid enters from LPI with an inclination (tangential ) angle on the disc A , wherein both discs A and E are on the same rotation axisof discs B and D, which is rotary shaft 58. Both pressure and the inclination (tangential ) angle cause the discsto rotate, through which the source or rotatorymotion can be excluded in the previous embodiment, or at least the consumed energy can be reduced.

After ensuring the discs with the same rotatorymotion:

2 nd fluid enters from HPI on the face of the disc D Face to enter inside a full- fledged groove 44 to pass through a hole inside X45 (or a set of holes) to the back face of the disc D Back to enter a partial groove 46.

The 1 st fluid moves with the discs within the space occupied by the partial groove 46 to enter with high pressure into the stator cylinder part C to longitudinal channels in it. At the same time, the 2 nd fluid enters from LPI on the face of disc B face to enter inside a full groove 54 to pass through hole X52 (or a set of holes), channelY52 (or a set of channels) and hole Z52 (or a set of holes) to the back face of the disc B Back to enter into a partial groove 51. The 2 nd fluid movesin turn from the partial groove 51 to the stator cylinder part C to longitudinal Channels in it.

If we assume instantaneous system steadiness, the upper part of the system is subjected to 1st fluid with high pressure and the lower part of the system is filled 2 nd fluid with low pressure.

Once the discs have rotated half the cycle, the situation is reversed as the high pressure transferred to 2 nd fluid filled channel to press it firmly out of the pressure exchanger with high pressure from HPO and on the other side the 1 st fluid lost the pressure (after exchanging the pressure with the 2 nd fluid) to exit the system from LP0.2 nd fluid after supplied with pressure iit passes through groove 55 on the rear side of disc B Back pass through a hole X56 (or a set of holes) to full groove 57 on the face of the disc B Faceto HPO.

After losing a large part of the pressure, the 1 st fluid moves to the partial groove 47 on the rear side of the disc D Back to pass through hole Z48 (or a set of holes), Channel Y48 (or a set of channels), hole X48 (or a set of holes) to full groove 50 on the face of disc D Face to LPO.

In one of the embodiments of the present invention, a free piston can be put inside every longitudinal channel in the stator cylinder part C to ensure that there is no admixture between the two fluids with the possibility to add bumpers at the end of each stage. This means that the system is generally divided into two halves; one with high pressure and the other with low pressure in an exchanging way with the steadiness of the cylinder part C (stationary) . This position saves quality characteristic for the pressure exchanger of the present invention, due to statistic steadiness that reduces the admixture between the two fluids, which is attributed to the cylinder part C and pressure exchange caused by the rotation of discs D and B.

The pressure exchanger according to any embodiment of the present invention is characterized by that the small length of fmeclearances, as the clearanceis located along the length of each disc not on the length of the cylinder part, so that the manufacturing and formation process becomes easy and this rises the efficiency of operation and reduces erosion and noise caused by the motion of parts of pressure exchanger.