System and method for purifying liquid by reverse osmosis

Abstract

A system for purifying a treated liquid, including: a treatment module, for treating the liquid and providing a purified liquid, and a residual liquid; and a means for pressurizing said treated liquid to supply said treatment module, including: a master cylinder, driven by a working fluid, and at least slave cylinder, driven by said master cylinder, receiving said treated liquid and supplying it to said treatment module;
a cross section of said master cylinder is greater than a cross section of said slave cylinder so that, a greater pressure is generated on the treated liquid in the slave cylinder; and a means for pre-pressurizing the treated liquid, upstream of the pressurizing means, including: at least one master cylinder, connected to the treatment module, and driven by the residual liquid, and a slave cylinder, containing the treated liquid, driven by said master cylinder.

Claims

1. A system for purifying a liquid to be treated, comprising: a module, called treatment module, for treating the liquid to be treated and providing a purified liquid, and a residual liquid; and a means for pressurizing the liquid to be treated to supply said treatment module, comprising: a cylinder, called a master cylinder, provided to be driven by a fluid, called a working fluid; and at least one cylinder, called a slave cylinder, driven by said master cylinder, provided to receive the liquid to be treated and supply the liquid to be treated to said treatment module; a cross section of said master cylinder is greater than a cross section of said at least one slave cylinder so that, for a given pressure of said working fluid in the master cylinder, a greater pressure is generated on the liquid to be treated in the slave cylinder; and a means for pre-pressurizing the liquid to be treated, upstream of the pressurizing means; said pre-pressurizing means comprising: at least one cylinder, called a master cylinder, connected to the treatment module, and driven by the residual liquid provided by the treatment module; and a cylinder, called a slave cylinder, containing the liquid to be treated, driven by said at least one master cylinder.

2. The system according to claim 1, wherein the treatment module is a module for treating the liquid to be treated by reverse osmosis.

3. The system according to claim 1, wherein the master cylinder is a double-acting cylinder, and the pressurizing means comprises two slave cylinders, situated symmetrically on both sides of the master cylinder, and driven by said master cylinder.

4. The system according to claim 1, further comprising a reservoir, called intermediate reservoir, arranged to store the liquid to be treated at an intermediate pressure, less than an osmotic pressure, at an outlet of the means for pre-pressurizing the liquid to be treated and to supply the pressurizing means with the liquid to be treated.

5. The system according to claim 1, wherein the working fluid is a thermal fluid, a pressure of which varies as a function of a temperature of the working fluid, said system comprising a thermal device, arranged upstream of the pressurizing means, and carrying out a heat exchange towards said working fluid, so as to increase its pressure.

6. The system according to claim 1, wherein the working fluid is an incompressible fluid, said system comprising: a thermal device, arranged upstream of the pressurizing means, and carrying out a heat exchange towards a thermal fluid, so as to increase the pressure of said thermal fluid; and a pressure transfer means, arranged between said thermal device and the pressurizing means, to transmit the pressure from said thermal fluid to the working fluid.

7. The system according to claim 6, wherein the pressure transfer means comprises: at least one cylinder, called transfer cylinder, connected to the pressurizing means, and provided to receive the working fluid; and at least one deformable volume, arranged in said transfer cylinder, and provided to receive the thermal fluid.

8. The system according to claim 5, wherein the thermal fluid is a fluid selected from: saturated or unsaturated C5- to C10-type hydrocarbons, organic fluids or mixtures of azeotropic or non-azeotropic organic fluids.

9. The system according to claim 5, further comprising a thermal fluid pre-pressurizing means, arranged upstream of the thermal device.

10. The system according to claim 9, wherein the thermal fluid pre-pressurizing means comprises: at least one cylinder, called master cylinder, driven by the residual liquid provided by the treatment module; and a cylinder, called slave cylinder, containing the thermal fluid, driven by said at least one master cylinder.

11. A method for purifying a liquid, called a liquid to be treated, comprising at least one iteration of the following steps: pressurizing the liquid to be treated; supplying said pressurized liquid to be treated to a treatment module providing a first liquid, called a purified liquid, and a second liquid, called a residual liquid; the pressurizing step is carried out by at least one cylinder, called a slave cylinder, firmly connected to a cylinder, called a master cylinder, with a cross section larger than the cross section of said slave cylinder, and receiving a working fluid; and a step of pre-pressurizing the liquid to be treated, before the step of pressurizing the liquid to be treated, carried out by a cylinder, called slave cylinder, containing the liquid to be treated, firmly connected to at least one cylinder, called master cylinder, receiving the residual liquid.

12. The method according to claim 11, wherein the treatment module is a module for treating liquid to be treated by reverse osmosis.

13. The method according to claim 11, wherein the master cylinder is a double-acting cylinder, and drives two slave cylinders so that, when one of the slave cylinders is emptied of liquid to be treated, the other slave cylinder is simultaneously filled with liquid to be treated.

14. The method according to claim 11, wherein the working fluid is a thermal fluid, said method comprising a step of increasing the pressure of said working fluid by heat exchange.

15. The method according to claim 11, wherein the working fluid is an incompressible fluid, said method comprising the following steps: a step of heat exchange towards a thermal fluid in order to increase the pressure of said thermal fluid; and a step of transferring pressure from said thermal fluid to saidworking fluid.

16. The method according to claim 15, wherein the pressure transfer step is carried out by at least one cylinder containing the working fluid and an elastic bladder, arranged in said cylinder, and containing the thermal fluid.

17. The method according to claim 14, further comprising a step of pre-pressurizing the thermal fluid, carried out by a cylinder, called slave cylinder, containing the thermal fluid, firmly connected to at least one cylinder, called master cylinder, receiving the residual liquid.

18. The method according to claim 15, further comprising two half cycles, each half cycle comprising the following phases: a phase I simultaneously comprising: increasing the pressure of the thermal fluid by heat exchange; and transferring pressure from said thermal fluid to said working fluid; a phase II simultaneously comprising: increasing the pressure of the thermal fluid by heat exchange; transferring pressure from said thermal fluid to said working fluid; pressurizing the liquid to be treated; purifying the liquid to be treated by reverse osmosis; and pre-pressurizing the thermal fluid; a phase III simultaneously comprising: increasing the pressure of the thermal fluid by heat exchange; transferring pressure from said thermal fluid to said working fluid; pressurizing the liquid to be treated; purifying the liquid to be treated by reverse osmosis; and pre-pressurizing the liquid to be treated; and a phase IV comprising a step of pre-pressurizing the liquid to be treated.

19. The system according to claim 1, wherein said master cylinder and said slave cylinder each include a piston.

20. The method of claim 11, wherein said master cylinder and said slave cylinder each include a piston.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other advantages and characteristics will become apparent on examining the detailed description of examples which are in no way limitative and the attached drawings, in which:

(2) FIG. 1 is a diagrammatic representation of a first example of the system according to the invention;

(3) FIG. 2 is a diagrammatic representation of a second example of the system according to the invention;

(4) FIG. 3 is a diagrammatic representation of a third example of the system according to the invention;

(5) FIG. 4 is a diagrammatic representation of an example of the method according to the invention; and

(6) FIGS. 5a, 5b, 5c and 5d are diagrammatic representations of the example of the method according to the invention implemented by the third example of the system according to the invention.

DETAILED DESCRIPTION

(7) It is well understood that the embodiments which will be described hereafter are in no way limitative. Variants of the invention can in particular be envisaged, comprising only a selection of the characteristics described hereafter, in isolation from the other characteristics described, if this selection of characteristics is sufficient to confer a technical advantage or to differentiate the invention with respect to the state of the prior art. This selection comprises at least one, preferably functional, characteristic without structural details, or with only a part of the structural details if this part alone is sufficient to confer a technical advantage or to differentiate the invention with respect to the state of the prior art.

(8) In particular, all the variants and all the embodiments described can be combined with each other if there is no objection to this combination from a technical point of view.

(9) In the figures, the elements common to several figures retain the same reference.

(10) FIG. 1 is a diagrammatic representation of a first example of the system according to the invention.

(11) The system 100 of FIG. 1 comprises a means 102 for pressurizing liquid to be treated 104, originating from a source 106.

(12) The pressurizing means 102 comprises a master cylinder 102.sub.M driving a slave cylinder 102.sub.E, containing the liquid to be treated 104. The master cylinder 102.sub.M has a cross section larger than the cross section of the slave cylinder 102.sub.E. When the slave cylinder 102.sub.E is driven by the master cylinder 102.sub.M, the liquid to be treated 104 is pressurized and conveyed towards a reverse osmosis treatment module 112.

(13) The treatment module 112 comprises a membrane 114, making it possible to produce a purified liquid at the outlet 116 and a residual liquid at the outlet 118 of said module 112.

(14) The system 100 also comprises a thermal device 120 connected to the pressurizing means 102. The thermal device comprises an evaporator 122 and a condenser 124. The evaporator 122 is connected to a solar thermal collector 128 inducing the evaporation of a thermal fluid 130 which is a working fluid in this example. The condenser 124 is cooled by the residual liquid at the outlet 118 of the treatment module 112, inducing the condensation of the thermal fluid 130.

(15) The difference in pressure induced by the evaporator 122 and the condenser 124 leads to the movement of the master cylinder 102.sub.M in the direction 132.

(16) FIG. 2 is a diagrammatic representation of a second example of the system according to the invention.

(17) The system 200 comprises the same elements as the system 100 of FIG. 1. Unlike the latter, the means 102 for pressurizing the system 200 comprises two slave cylinders 102.sub.E1-102.sub.E2. Furthermore, the master cylinder 102.sub.M is a double-acting cylinder. Thus, each of the two slave cylinders 102E can be driven by the master cylinder 102.sub.M in two opposite directions 132.sub.1-132.sub.2.

(18) Each of the slave cylinders 102.sub.E1 and 102.sub.E2 is equipped with a suction valve 202.sub.1 and 202.sub.2 respectively and with a delivery valve 204.sub.1 and 204.sub.2 respectively. The suction valves 202 are connected to the source 106 of liquid to be treated 104, in order to supply the slave cylinders 102.sub.E. The delivery valves 204 are connected to the treatment module 112, supplying the latter with pressurized liquid to be treated 104.

(19) The master cylinder 102.sub.M is connected to the thermal device 120 by means of a distributor 206. The distributor 206 in position A makes it possible to connect the evaporator 122 to a chamber called left-hand chamber of the master cylinder 102.sub.M and the condenser 124 is connected to a chamber called right-hand chamber of the master cylinder 102.sub.M, and vice versa when the distributor 206 is in position B.

(20) When the distributor 206 is in position A: the master cylinder 102.sub.M moves in the direction 132.sub.1, the slave cylinder 102.sub.E2 is filled with liquid to be treated 104 through the suction valve 202.sub.2, and the slave cylinder 102.sub.E1 pressurizes the liquid to be treated 104 and sends it to the treatment module 112 through the delivery valve 204.sub.1.

(21) Conversely, when the distributor 206 is in position B: the master cylinder 102.sub.M moves in the direction 132.sub.2, the slave cylinder 102.sub.E1 is filled with liquid to be treated 104 through the suction valve 202.sub.1, and the slave cylinder 102.sub.E2 pressurizes the liquid to be treated 104 and sends it to the treatment module 112 through the delivery valve 204.sub.2.

(22) FIG. 3 is a diagrammatic representation of a third example of the system according to the invention.

(23) The system 300 of FIG. 3 comprises the same elements as the system 200 of FIG. 2.

(24) The system 300 also comprises a means 302 for pre-pressurizing the liquid to be treated 104. The pre-pressurizing means 302 comprises two master cylinders 302.sub.M1-302.sub.M2 driving a slave cylinder 302.sub.E containing the liquid to be treated 104. The master cylinders 302.sub.M are alternately connected to the outlet 118 of the treatment module 112 and to the condenser 124, by means of a distributor 206.sub.2. The master cylinders 302.sub.M are alternately driven by the residual liquid as a function of the position (A or B) of the distributor 206.sub.2. When the slave cylinder 302.sub.E is driven by a master cylinder 302.sub.M, it simultaneously pre-pressurizes the liquid to be treated 104 and is again filled with liquid to be treated 104. The pre-pressurized liquid to be treated 104 is stored in a reservoir 304 at an intermediate pressure greater than the pressure at the source 106 of the liquid to be treated 104.

(25) The reservoir 304 is connected to the pressurizing means 102 and provides the slave cylinders 102.sub.E with pre-pressurized liquid to be treated 104.

(26) The system 300 also comprises a means 306 for pressurizing the thermal fluid 130. The pressurizing means 306 comprises two master cylinders 306.sub.M1-306.sub.M2 driving a slave cylinder 306.sub.E containing the thermal fluid 130. They are alternately connected to the outlet 118 of the treatment module 112 and to the condenser 124, by means of a distributor 206.sub.3. The slave cylinder 306.sub.E is connected to a reservoir 308 containing thermal fluid 130 condensed by the condenser 124.

(27) The master cylinders 306.sub.M are alternately driven by the residual liquid as a function of the position (A or B) of the distributor 206.sub.3. When the slave cylinder 306.sub.E is driven by a master cylinder 306.sub.M, it pre-pressurizes the thermal fluid 130 and is again filled with thermal fluid 130. The pre-pressurized thermal fluid 130 is transferred into the evaporator 122.

(28) The system 300 comprises a pressure transfer means 318 arranged upstream of the pressurizing means 102 and of the thermal device 120. The transfer means 318 comprises two pressure transfer cylinders 310.sub.1-310.sub.2. Each cylinder 310.sub.1-310.sub.2 comprises an elastic bladder, 312.sub.1 and 312.sub.2 respectively. The cylinders 310 are connected to the master cylinder 102.sub.M of the pressurizing means 102. In particular, the cylinder 310.sub.1 is connected to the left-hand chamber of the master cylinder 102.sub.M and the cylinder 310.sub.2 is connected to the right-hand chamber of the master cylinder 102.sub.M. The transfer cylinders 310 contain an incompressible driving liquid 314, that can be transferred into the master cylinder 102.sub.M in order to produce the movement thereof. The bladders 312 are connected to the thermal device 120 by means of a distributor 206.sub.1. The bladders 312 are alternately connected to the evaporator 122 and the condenser 124. Furthermore, valves 316.sub.1-316.sub.2 are arranged downstream of the evaporator 122 and the condenser 124 respectively. The valves 316 make it possible to isolate or to connect the evaporator 122 and the condenser 124 to one of the bladders 312.

(29) The bladders 312 contain the thermal fluid 130. The bladders 310 are deformed as a function of the pressure of the thermal fluid 130. The deformation of one of the bladders 312 induces the movement of the working fluid 314 present in one of the cylinders 310 and thus the movement of the master cylinder 102.sub.M.

(30) Moreover, the system 300 comprises a device for adjusting the flow rate 320 of residual liquid. This adjustment device 320 comprises a valve that can be adjusted upstream of a downstream pressure reducer. The device for adjusting the flow rate 320 makes it possible to control the speed of the movements of the cylinders 302.sub.M and 306.sub.M.

(31) FIG. 4 is a diagrammatic representation of an example of the method according to the invention.

(32) The method 400 can be implemented, for example by the system 300 of FIG. 3.

(33) The method 400 comprises two half cycles, identical in their execution and for which the role of the transfer cylinders 310 is reversed.

(34) Each half cycle simultaneously comprises a phase 402 comprising a step of increasing the pressure of the thermal fluid by heat exchange and a step of transferring pressure from said thermal fluid to said working fluid.

(35) A half cycle of the method 400 then comprises a phase 404 simultaneously comprising the following steps: increasing the pressure of the thermal fluid by heat exchange, transferring pressure from said thermal fluid to said working fluid, pressurizing the liquid to be treated, purifying the liquid to be treated by reverse osmosis, and pre-pressurizing the thermal fluid.

(36) A half cycle of the method 400 then comprises a phase 406 which simultaneously consists of: increasing the pressure of the thermal fluid by heat exchange, transferring pressure from said thermal fluid to said working fluid, pressurizing the liquid to be treated, purifying the liquid to be treated by reverse osmosis, and pre-pressurizing the liquid to be treated.

(37) Each half cycle of the method comprises a phase 408 comprising a step of pre-pressurizing the liquid to be treated.

(38) A half cycle of the method 400 ends with a step 410 of reversing the connections in order to carry out a second half cycle reversing the roles of the transfer cylinders.

(39) FIGS. 5a, 5b, 5c and 5d are diagrammatic representations of the example of the method according to the invention implemented by the third example of the system according to the invention.

(40) FIGS. 5a, 5b, 5c and 5d respectively represent the phases 402, 404, 406 and 408 of the method 400 of FIG. 4.

(41) In the phase 402 represented in FIG. 5a, the distributor 206.sub.1 is in position A, while the distributors 206.sub.2 and 206.sub.3 are in position B. The valves 316 are open. The bladders 312.sub.1 et 312.sub.2 are connected to the condenser 124 and to the evaporator 122 respectively. Due to the evaporation of the thermal fluid 130 in the evaporator, the pressure and thus the volume of the bladder 312.sub.2 increase. Conversely, the pressure and the volume of the bladder 312.sub.1 are reduced by condensation of the thermal fluid 130 in the condenser 124. The pressurizing of the bladders 312 induces the movement of the driving liquid 314 and thus the pressurizing of the master cylinder 102.sub.M of the pressurizing means 102.

(42) In the phase 404 represented in FIG. 5b, the distributor 206.sub.3 is placed in position A. This arrangement allows the flow of the liquid to be treated 104 in the system 300, in particular the movement of the master cylinder 102.sub.M in the direction 132.sub.2 and thus the pressurizing of the liquid to be treated 104 by the pressurizing means 102.

(43) The liquid to be treated 104 at the outlet of the pressurizing means 102 has a pressure greater than its osmotic pressure. The treatment module 112 thus produces fresh water. The residual liquid at the outlet 118 of the treatment module 112 drives the master cylinder 306.sub.M1. The master cylinder 306.sub.M1 drives with it the slave cylinder 306.sub.E and the other master cylinder 306.sub.M2. The slave cylinder 306.sub.E pre-pressurizes the thermal fluid 130 and transfers it into the evaporator 122 and again sucks in a quantity of the thermal fluid 130 from the reservoir 308. The other master cylinder 306.sub.M2 drives the residual liquid that it contained towards the condenser 124 in order to cool it. This phase 404 ends when the master cylinder 306.sub.M1 is in its end position.

(44) In the phase 406 represented in FIG. 5c, the distributor 206.sub.2 is placed in position A. This arrangement allows the flow of the liquid to be treated 104 in the system 300; in particular the movement of the master cylinder 102.sub.M and thus the pressurizing of the liquid to be treated 104 by the pressurizing means 102.

(45) The liquid to be treated 104 at the outlet of the pressurizing means 102 has a pressure greater than its osmotic pressure. The treatment module 112 continues to produce fresh water. The residual liquid at the outlet 118 of the treatment module 112 drives the master cylinder 306.sub.M1 of the pre-pressurizing means 302. The master cylinder 306.sub.M1 drives with it the slave cylinder 306.sub.E and the other master cylinder 306.sub.M2. The slave cylinder 306.sub.E pre-pressurizes the liquid to be treated 104 that it contained and transfers it into the reservoir 304 at a pressure slightly less than its osmotic pressure, and again sucks in a quantity of liquid to be treated 104. Simultaneously, the master cylinder 306.sub.M1 drives the residual liquid that it contained towards the condenser 124 in order to cool it. This phase 406 ends when the volume of the bladder 312.sub.2 reaches a volume allowing an adiabatic expansion.

(46) Finally, in the phase 408 represented in FIG. 5d, the valve 316.sub.1 is closed, thus isolating the bladder 312.sub.2 from the evaporator 122. The bladder 312.sub.2 containing a constant volume of thermal fluid 130 undergoes an adiabatic expansion so as to occupy the entire volume of the cylinder 310.sub.2. This expansion allows the continuity of the movement of the master cylinder 102.sub.M and thus the pressurizing of the liquid to be treated 104 and the production of fresh water. Moreover, the master cylinder 302.sub.M1 continues to be driven by the residual liquid in order to pre-pressurize the liquid to be treated 104. This phase 408 ends when the master cylinders 102.sub.M and 302.sub.M1 arrive in their end position.

(47) Of course, the invention is not limited to the examples which have just been described and numerous adjustments can be made to these examples without exceeding the scope of the invention.