(19)
(11)EP 1 986 766 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
30.03.2011 Bulletin 2011/13

(21)Application number: 07702483.4

(22)Date of filing:  08.02.2007
(51)International Patent Classification (IPC): 
B01D 61/06(2006.01)
B01D 61/12(2006.01)
(86)International application number:
PCT/DK2007/000065
(87)International publication number:
WO 2007/090406 (16.08.2007 Gazette  2007/33)

(54)

A LIQUID TREATMENT APPARATUS

FLÜSSIGKEITSBEHANDLUNGSVORRICHTUNG

APPAREIL DE TRAITEMENT DE LIQUIDES


(84)Designated Contracting States:
AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LI LT LU LV MC NL PL PT RO SE SI SK TR

(30)Priority: 10.02.2006 DK 200600193

(43)Date of publication of application:
05.11.2008 Bulletin 2008/45

(73)Proprietor: Danfoss A/S
DK-6430 Nordborg (DK)

(72)Inventors:
  • LINNIG, Jan
    DK-6440 Augustenborg (DK)
  • LAURSEN, Michael
    DK-6400 Sønderborg (DK)


(56)References cited: : 
EP-A- 1 256 371
WO-A-2004/065308
US-A- 4 772 385
EP-A1- 0 190 741
DE-A1- 2 533 151
US-A1- 2004 178 145
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    INTRODUCTION



    [0001] The present invention relates to a liquid treatment apparatus comprising:
    • a separation structure comprising a membrane, an inlet for receiving an inlet liquid, a first outlet for delivering a first liquid which has not passed through the membrane, and a second outlet for delivering a second liquid which has passed through the membrane,
    • a displacement pump adapted to provide an essentially fixed geometric displacement of an inlet liquid to the separation structure relative to the rotation of a pump element, and
    • a pressure recovery unit adapted to drain an amount of first liquid from the separation structure proportional to the rotation of a recovery element
    • a drive structure adapted to provide a variable and synchronous rotational speed (RPM) of the pump element and the recovery element.

    BACKGROUND OF THE INVENTION



    [0002] Devices in which a liquid substance passes through a membrane are commonly used for separating substances of a liquid composition. In connection with water treatment, such devices are used for desalination purposes by separation of dissolved salts from water, and for water purification in general e.g. by separation of contaminants such as bacteria and virus from water. Similar devices are used for removing liquid from fruit juice to provide a concentrate thereof and in general for removing substances from a liquid or for concentrating substances in a liquid.

    [0003] In general, the separation structure receives a liquid composition comprising various substances, in the following referred to as inlet liquid, and delivers two different liquids each having different contents of one of more substances. Certainly, both of these two different liquids may be valuable. Often, however, one of the two liquids is a desired liquid, and the other one is to be disposed of. To distinguish the two liquids, the following description will be based on the term "the first liquid" for the liquid which has not passed through the membrane, and "the second liquid" for the liquid which has passed through the membrane.

    [0004] In general, it is desired that as much liquid as possible permeates through the membrane. This may be achieved by increasing the pressure difference across the membrane, i.e. by increasing the pressure of the inlet liquid to a point which is close to a maximum limit prescribed for the membrane. In a desalination plant working in accordance with the principles of reverse osmosis, the inlet water (saltwater) is typically pressurised to approximately 60-70 bar depending upon the salt concentration. At this pressure, the saltwater enters a separation structure with a reverse osmosis membrane which is permeable to pure water. Since the utilization rate is typically 25-35%, 65-75% of the saltwater is rejected from the system as a residual product of the process (the first fluid). This rejected water has a higher salt concentration than the received saltwater and will in the following be referred to as brine. During returning of the brine, it undergoes a pressure drop of 60-70 bar and the energy thereby released corresponds to 65-75 percent of the energy which has been consumed by the pump which initially raised the pressure of the saltwater. In order to recover the energy which is released during the returning of the seawater, a pressure recovery unit is often inserted after the separation structure.

    [0005] US 200470178145 describes a reverse osmosis system with energy recovery, in which the pump used in the preferred embodiment is made as a double diaphragm pump and has two diaphragm heads in the preferred version. The document mentions nothing about changes in the efficiency of the described units and nothing about the possibility of changing the synchronous rotational speeds of the pump element and the recovery element.

    [0006] A reverse osmosis system is shown e.g. in US 5,482,441.

    [0007] The pressure recovery unit not only recovers the pressure and thus saves energy; it also provides a sufficient back pressure in the outlet of the first fluid.

    [0008] A general problem with the existing devices is that fouling in the membrane increases the resistance against permeation of the liquid through the membrane. As a consequence, a fixed pressure of the inlet liquid provides a ratio between the first liquid and the second liquid which changes over time. This characteristic of the known devices is undesired. Firstly, the loading and thus the wear of the often very expensive membrane increases over time, and secondly, a specific consumption of the first and/or second liquid requires over-dimensioning of the device when the membrane is new.

    DESCRIPTION OF THE INVENTION



    [0009] It is an object of the present invention to enable a more constant capacity of a liquid treatment apparatus and to enable a reduced wear on the membrane. Accordingly, the invention, in a first aspect, provides an apparatus of the kind mentioned in the introduction wherein the displacement pump and the pressure recovery unit have different changes in efficiency for a change in the synchronised RPM to enable control of a ratio between the first and second liquids by varying the synchronous rotational speeds of the pump element and the recovery element.

    [0010] The inlet fluid must necessarily leave the separation structure either in the form of the first fluid or in the form of the second fluid. Since the supplied amount of inlet liquid is proportional to the rotation of the pump element and the drained amount of first liquid is proportional to the rotation of the recovery element, the amount of liquid which permeates through the membrane, i.e. the second liquid, is determined by the difference between the two amounts. Since the speed of the pump element and the recovery element is variable and synchronous, the invention facilitates an easy way of varying the total flow of liquid through the separation structure without having to consider adjustments of the back pressure, or the invention may be utilised to provide a fixed flow of liquid through the separation structure even though the membrane fouls over time.

    [0011] The separation structure may e.g. be a filtration structure or a reverse osmosis structure of the known kind, i.e. comprising an inlet and an outlet on one side of a membrane and an outlet on an opposite side of the membrane. Depending on the membrane, the separation could provide pure water from saltwater or from contaminated water, or the separation could provide a concentrated product from a less concentrated primary produce, e.g. concentrated juice from less concentrated juice.

    [0012] The pressure recovery unit could be of a similar structure as the displacement pump. In one embodiment at least one, and preferably both the pump and the recovery unit are axial piston units, e.g. of the kind disclosed in EP 0 774 073. The displacement pump and the pressure recovery unit could also be combined into one unit.

    [0013] The drive structure could be a regular electrically or hydraulically driven motor provided with control means for adjusting the rotational speed, e.g. a frequency converter for changing the rotational speed of an AC motor. Alternatively, the motor could be a Frequency controlled motor (FCM). The motor could be connected to one shaft which drives both the pump element and the recovery element. In another embodiment, two separate motors drive the pump element and the recovery element individually. In this embodiment, the synchronisation between rotations of the two elements could be established by a controller which controls the speed of the two motors. In another embodiment, the pump and recovery unit could be integrated into one single unit which is driven by one single motor.

    [0014] The synchronising structure could provide a direct coupling between the rotatable element of the displacement pump and the rotatable element of the pressure recovery unit to make the two elements rotate with identical speeds, or the synchronising structure could provide a fixed ratio between the RPM of one of the rotatable elements and the RPM of the other rotatable element.

    [0015] The displacement pump and the pressure recovery unit may e.g. be of the kind which are lubricated by the operating liquid, i.e. with the liquid which is displaced through the pump or unit. In such a pump or unit, the efficiency depends on the RPM, and typically, the efficiency decreases when the RPM increases. For a low number of RPM, the amount of liquid which passes through the pump or unit for each rotation is relatively large compared with the amount which passes through the pump or unit for each rotation at larger RPM.

    [0016] This effect may be utilised in a particularly advanced way by using a displacement pump and a pressure recovery unit having a different change in efficiency for a change in the synchronised RPM. If, as an example, the efficiency of the pump unit decreases less than the efficiency of the pressure recovery unit for a specific increase in the synchronised RPM, then the amount of the supplied inlet liquid decreases less than the amount of drained first liquid per rotation, and as a result, the amount of liquid which is forced through the membrane, i.e. the amount of the second liquid increases. In other words, this selection of displacement pump and pressure recovery unit enables an increase in the ratio of the second fluid to the first fluid by increasing RPM, and the ratio between the first and second liquids may in general be controlled by varying the synchronous rotational speeds of the pump element and the recovery element.

    [0017] In order to protect the membrane against overloading, the RPM could be adjusted based on a pressure which is measured in the separation structure. As an example, the RPM could be adjusted based on a pressure difference between pressure of the inlet liquid and pressure of the first liquid when it leaves the separation structure, or just on the pressure on the side of the membrane which faces the inlet and the outlet of the first fluid.

    [0018] Starting and stopping of an apparatus, in particular a reverse osmosis structure may be undesirable since it typically reduces the lifetime of the membrane or at least reduces the time between necessary cleanings of the membrane. In order to reduce the number of starts and stops of the apparatus, the RPM could be adjusted based on consumption of one of the first and second liquids. In a desalination apparatus for providing freshwater from saltwater or contaminated water, the RPM may be adjusted based on the consumption of the freshwater, preferably to achieve a production of the freshwater which equals the consumption. Accordingly, the apparatus may comprise means for determining the consumption. This could comprise a flow measuring structure inserted in a pipeline which drains the first and/or the second liquid away from the separation structure, or it may comprise a level measuring structure in a buffer tank which receives one or both of the first and second liquids.

    [0019] To further protect the membrane against overloading and thus to increase the lifetime of the apparatus or membrane or to increase the time between cleanings of the membrane, the apparatus may further comprise a start-up structure by which a maximum acceleration of the drive structure and thus of the pump element and of the recovery element can be specified. Accordingly, when the apparatus is switched on, it may be adjusted to start the rotation from zero RPM and to achieve its desired speed over a selectable interval, e.g. over 1 to 5 minutes, such as to achieve the desired speed after 3 minutes. This facilitates a controllable increase of pressure in the separation structure and thus protects the membrane against overloading.

    [0020] In a second aspect, the invention provides a method of operating a liquid treatment apparatus according to ano of claims 1 - 13, the method comprising driving the displacement pump and the recovery unit synchronously at different speeds depending on consumption of a liquid which is received from the separation structure.

    [0021] In a third aspect, the invention provides a method according to claim 14, the method comprising adjusting a pressure gradient in the separation structure by adjusting an acceleration of a synchronous rotation of the pump element and the recovery element.

    [0022] In a fourth aspect, the invention provides a method according to claims 14 or 15, the method comprising applying freshwater to the inlet and driving the displacement pump and the recovery unit synchronously at a speed which is lower than a speed which is necessary for activating permeation of saltwater through the membrane. As an example, the apparatus may normally be operated at a certain RPM to provide permeation of saltwater through the membrane, and when freshwater is flushed through the structure, the apparatus is operated at a speed in the range of 35-70 pct. of the speed during normal operation. Due to an osmotic pressure, the freshwater may destroy bacteria which are collected in the membrane.

    DETAILED DESCRIPTION



    [0023] In the following, a preferred embodiment of the invention will be described in further details with reference to the drawing in which:

    Fig. 1 illustrates a reverse osmosis apparatus according to the invention,

    Fig. 2 illustrates a ratio between RPM and displaced amounts of fluid by the displacement pump and the pressure recovery unit, and

    Fig. 3 illustrates the reverse osmosis apparatus in Fig. 1 including a tank for collection of produced freshwater.



    [0024] Fig. 1 illustrates schematically a reverse osmosis apparatus 1 for providing freshwater from saltwater. The apparatus comprises two separation structures 2, 3 connected in parallel between an inlet pipe 4, a first outlet pipe 5 for a first liquid, in this case brine, and a second outlet pipe 6 for a second liquid, in this case freshwater. Each separation structure comprises a membrane 7, an inlet 8 for receiving an inlet liquid (in this case saltwater), a first outlet 9 for delivering a first liquid (in this case brine with a relatively high salt concentration), and a second outlet 10 for delivering a second liquid which is freshwater, i.e. water which has passed through the reverse osmosis membranes 7. The apparatus further comprises an axial piston displacement pump 11 which supplies the saltwater at a pressure of 60-70 bar. A pressure recovery unit or pressure converter 12 located on the other side of the separation structures 2, 3 transfers the energy of the high pressure brine to the saltwater which enters the separation structure. The pressure converter 12 and the pump 11 are driven via one common shaft 13 by a frequency controlled motor 14.

    [0025] A first pressure sensor 15 measures the pressure in the inlet, and a second pressure sensor 16 measures the pressure in the first outlet. In one mode of operation, the RPM of the motor 14 and thus of the pump 11 and the recovery unit 12 is controlled based on a pressure difference between the pressures measured by the first and second pressure sensors 15, 16.

    [0026] The pump graph 17 in Fig. 2 illustrates the ratio between the RPM (along the abscissa) of the pump 11 and the amount of liquid in litres per minute (along the ordinate), which is displaced into the inlet 8 by the pump 11. The recovery graph 18 illustrates the ratio between the RPM (along the abscissa) of the pressure converter 12 and the amount of liquid in litres per minute (along the ordinate), which is displaced out of the first outlet 9 by the pressure converter 12. As indicated by the difference in the inclination of the two graphs 17, 18, the efficiency, i.e. the amount of displaced liquid per minute related to the RPM, of the pressure recovery unit 12 and the pump 11 change differently for a change in the RPM. Since the inclination of the pump graph 17 is steeper than the inclination of the recovery graph 18, an increase in RPM results in an increase in the difference between the amount of liquid which enters through inlet 8 and the amount of liquid which drains through the first outlet 9. Since the difference necessarily has to drain out of the separation structure through the second outlet 10, the increase in the difference causes an increase in the amount of liquid per minute which permeates through the membrane 7, and thus an increased production rate of freshwater. In Fig. 2, the recovery rate graph 19 indicates the difference in inclination, and thus the recovery rate of the apparatus.

    [0027] The output of the liquid treatment apparatus 1 may thus be controlled by varying the RPM of the synchronised motion of the pump and of the recovery unit. The RPM can, as mentioned above be measured based on a pressure in the separation structure, e.g. by using the two pressure sensors 15, 16 disclosed in Fig. 1, or as will be discussed relative to Fig. 3, based on consumption of freshwater.

    [0028] Fig. 3 shows the apparatus of Fig. 1 in a more complete configuration including a tank 20 for collecting freshwater. The tank includes an upper level switch 21 and a lower level switch 22. In order to reduce the number of starts and stops of the apparatus, the level switches are located at a distance from the top and bottom, respectively. When the upper level switch is triggered, the tank therefore has additional space for freshwater. When the upper level switch is triggered, the RPM can be reduced until the freshwater level decreases to a lower level. In a corresponding manner, triggering of the lower level switch may cause an increased RPM until the freshwater level gets above the lower limit. In an alternative embodiment, a flow metre is inserted in the delivery pipe 23 to measure a consumption of the freshwater, and the RPM is controlled to compensate for the actual consumption.

    [0029] Fig. 3 further shows a second tank 24 which receives freshwater from the separation structures 2, 3 when the valve k5 connects the conduit 25 to the outlet pipe 6. In a similar manner, the valve k4 may connect or disconnect the flow of freshwater to the tank 20. The outlet 26 of the tank 24 is connectable to the inlet pipe 4 via the switch s1. When freshwater from the tank 24 is guided to the inlet of the reverse osmosis structures, the membrane and the area between the inlet and the first outlet are cleaned by an osmotic pressure which destroys micro organisms which may exist in the salt environment. When freshwater is guided through the reverse osmosis structure, it is not necessary to create permeation of water through the membrane but merely to flush the membrane. Accordingly, the pressure in the reverse osmosis structure during this procedure may be lowered considerably relative to the pressure applied to activate the permeation of water through the membrane. In this respect, the variable and synchronous rotational speed of the pump element and recovery element is further advantageous since it facilitates an improved way of controlling the pressure in the reverse osmosis structure when changing from saltwater to freshwater. Typically, the RPM can be lowered to a range of 35-70 pct. of the RPM which is considered for activating the permeation of water through the membrane.


    Claims

    1. A liquid treatment apparatus (1) comprising:

    - a separation structure (2, 3) comprising a membrane (7), an inlet (8) for receiving an inlet liquid, a first outlet (9) for delivering a first liquid which has not passed through the membrane (7), and a second outlet (10) for delivering a second liquid which has passed through the membrane (7),

    - a displacement pump (11) adapted to provide an essentially fixed geometric displacement of an inlet liquid to the separation structure (2, 3) relative to rotation of a pump element,

    - a pressure recovery unit (12) adapted to drain an amount of first liquid from the separation structure (2, 3) proportional to the rotation of a recovery element, and

    - a drive structure (13, 14) adapted to provide a variable and synchronous rotational speed (RPM) of the pump element and the recovery element,

    characterized in that the displacement pump and the pressure recovery unit have different changes in efficiency for a change in the synchronised RPM to enable control of a ratio between the first and second liquids by varying the synchronous rotational speeds of the pump element and the recovery element.
     
    2. An apparatus according to claim 1, wherein the displacement pump is an axial piston displacement pump.
     
    3. An apparatus according to claims 2, wherein the displacement pump and the pressure recovery unit have an identical structure.
     
    4. An apparatus according to claim 1, wherein a recovery rate increases when the RPM increases.
     
    5. An apparatus according to any of the preceding claims, wherein the RPM is adjusted based on a pressure which is measured in the separation structure (2, 3).
     
    6. An apparatus according to any of the preceding claims, wherein the RPM is adjusted based on the consumption of a liquid which is received from the separation structure (2, 3).
     
    7. An apparatus according to claim 6, wherein the liquid is the first liquid.
     
    8. An apparatus according to claim 6, wherein the liquid is the second liquid.
     
    9. An apparatus according to any of the preceding claims, wherein the separation structure (2, 3) is a reverse osmosis structure.
     
    10. An apparatus according to any of claims 1-8, wherein the separation structure (2, 3) is a filtration structure.
     
    11. An apparatus according to any of the preceding claims, comprising a start-up structure for defining the acceleration of the drive structure (13, 14).
     
    12. An apparatus according to any of the preceding claims, wherein the displacement pump (11) for a fixed RPM provides a fixed ratio between liquid displacement and RPM.
     
    13. An apparatus according to any of the preceding claims, wherein the drive structure (13, 14) comprises an electrically driven motor (14) with variable RPM.
     
    14. A method of operating a liquid treatment apparatus according to any of claims 1-13, the method comprising driving the displacement pump and the recovery unit synchronously at different speeds depending on the consumption of a liquid which is received from the separation structure.
     
    15. A method according to claim 14, comprising adjusting a pressure gradient in the separation structure by adjusting an acceleration of a synchronous rotation of the pump element and the recovery element.
     
    16. A method according to claims 14 or 15, comprising applying freshwater to the inlet and driving the displacement pump and the recovery unit synchronously at a speed which is lower than a speed which is necessary for activating permeation of saltwater through the membrane.
     


    Ansprüche

    1. Eine Flüssigkeitsbehandlungsanordnung (1) mit:

    - einer Trennstruktur (2, 3) mit einer Membran (7), einem Einlass (8) zum Empfang einer Einlassflüssigkeit, einem ersten Auslass (9) zur Ausgabe einer ersten Flüssigkeit, die nicht durch die Membran (7) geflossen ist, und einem zweiten Auslass (10) zur Ausgabe einer zweiten Flüssigkeit, die durch die Membran (7) geflossen ist,

    - einer Verdrängungspumpe zur Lieferung einer im wesentlichen festen geometrischen Verdrängung einer Einlassflüssigkeit zur Trennstruktur (2, 3) im Verhältnis zur Drehung eines Pumpenelementes,

    - einer Druckrückgewinnungseinheit (12) zum Ablassen einer Menge erster Flüssigkeit von der Trennstruktur (2, 3) proportional zur Drehung eines Rückgewinnungselementes, und

    - einer Antriebsstruktur (13, 14) zur Lieferung einer variablen und synchronen Drehgeschwindigkeit des Pumpenelementes und des Rückgewinnungselementes,

    dadurch gekennzeichnet, dass die Verdrängungspumpe und die Druckrückgewinnungseinheit unterschiedliche Änderungen der Leistung für eine Änderung der synchronisierten Drehgeschwindigkeit aufweisen, um eine Regelung des Verhältnisses zwischen der ersten und der zweiten Flüssigkeiten bei variierenden synchronen Drehgeschwindigkeiten von Pumpenelement und Rückgewinnungselement zu ermöglichen.
     
    2. Eine Anordnung nach Anspruch 1, dadurch gekennzeichnet, dass die Verdrängungspumpe eine Axialkolbenverdrängungspumpe ist.
     
    3. Eine Anordnung nach Anspruch 2, dadurch gekennzeichnet, dass die Verdrängungspumpe und die Druckrückgewinnungseinheit eine identische Struktur haben.
     
    4. Eine Anordnung nach Anspruch 1, dadurch gekennzeichnet, dass die Rückgewinnungsmenge ansteigt, wenn die Drehgeschwindigkeit ansteigt.
     
    5. Eine Anordnung nach jedem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass die Drehgeschwindigkeit auf Grund eines Druckes geregelt wird, der in der Trennstruktur (2, 3) gemessen wird.
     
    6. Eine Anordnung nach jedem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass die Drehgeschwindigkeit auf Grund des Verbrauches einer Flüssigkeit geregelt wird, die von der Trennstruktur (2, 3) erhalten wird.
     
    7. Eine Anordnung nach Anspruch 6, dadurch gekennzeichnet, dass die Flüssigkeit die erste Flüssigkeit ist.
     
    8. Eine Anordnung nach Anspruch 6, dadurch gekennzeichnet, dass die Flüssigkeit die zweite Flüssigkeit ist.
     
    9. Eine Anordnung nach jedem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass die Trennstruktur (2, 3) eine Umkehrosmosestruktur ist.
     
    10. Eine Anordnung nach jedem der Ansprüche 1-8, dadurch gekennzeichnet, dass die Trennstruktur (2, 3) eine Filtrierstruktur ist.
     
    11. Eine Anordnung nach jedem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass sie eine Struktur zur Definierung der Beschleunigung der Antriebsstruktur (13, 14) aufweist.
     
    12. Eine Anordnung nach jedem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass die Verdrängungspumpe (11) für eine feste Drehgeschwindigkeit ein festes Verhältnis zwischen der Flüssigkeitsverdrängung und der Drehgeschwindigkeit liefert.
     
    13. Eine Anordnung nach jedem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass die Antriebsstruktur (13, 14) einen elektrisch angetriebenen Motor (14) mit variabler Drehzahl aufweist.
     
    14. Ein Verfahren zum Betreiben einer Flüssigkeitsbehandlungsanordnung nach jedem der Ansprüche 1-13, das den synchronen Betrieb der Verdrängungspumpe und der Rückgewinnungseinheit bei verschiedenen Geschwindigkeiten, abhängig vom Verbrauch einer Flüssigkeit, die von der Trennstruktur erhalten wird, umfasst.
     
    15. Ein Verfahren nach Anspruch 14, das die Justierung eines Druckanstiegs in der Trennstruktur durch eine Justierung einer Beschleunigung der synchronen Drehung von Pumpenelement und Rückgewinnungselement umfasst.
     
    16. Ein Verfahren nach Anspruch 14 oder 15, das die Anwendung von Süßwasser am Einlass und den synchronen Antrieb von Verdrängungspumpe und Rückgewinnungspumpe bei einer Geschwindigkeit, die niedriger ist als die zur Aktivierung des Durchdringens von Salzwasser durch die Membran benötigte Geschwindigkeit, umfasst.
     


    Revendications

    1. Appareil de traitement de liquide (1), comprenant :

    - une structure de séparation (2, 3) comprenant une membrane (7), une entrée (8) pour recevoir un liquide d'entrée, une première sortie (9) pour distribuer un premier liquide qui n'est pas passé à travers la membrane (7), et une seconde sortie (10) pour distribuer un second liquide qui est passé à travers la membrane (7),

    - une pompe volumétrique (11) adaptée pour fournir un déplacement géométrique essentiellement fixe d'un liquide d'entrée à la structure de séparation (2, 3) par rapport à une rotation d'un élément de pompe,

    - une unité de récupération de pression (12) adaptée pour drainer une quantité de premier liquide à partir de la structure de séparation (2, 3) proportionnelle à la rotation d'un élément de récupération, et

    - une structure d'entraînement (13, 14) adaptée pour fournir une vitesse de rotation (TR/MIN) variable et synchrone de l'élément de pompe et de l'élément de récupération,

    caractérisé en ce que la pompe volumétrique et l'unité de récupération de pression possèdent des changements différents de rendement pour un changement de la TR/MIN synchronisée pour permettre la commande d'un rapport entre les premier et second liquides en variant les vitesses de rotation synchrones de l'élément de pompe et de l'élément de récupération.
     
    2. Appareil selon la revendication 1, dans lequel la pompe volumétrique est une pompe volumétrique à pistons axiaux.
     
    3. Appareil selon la revendication 2, dans lequel la pompe volumétrique et l'unité de récupération de pression possèdent une structure identique.
     
    4. Appareil selon la revendication 1, dans lequel un taux de récupération augmente lorsque la TR/MIN augmente.
     
    5. Appareil selon l'une quelconque des revendications précédentes, dans lequel la TR/MIN est réglée sur la base d'une pression qui est mesurée dans la structure de séparation (2, 3).
     
    6. Appareil selon l'une quelconque des revendications précédentes, dans lequel la TR/MIN est réglée sur la base de la consommation d'un liquide qui est reçu à partir de la structure de séparation (2, 3).
     
    7. Appareil selon la revendication 6, dans lequel le liquide est le premier liquide.
     
    8. Appareil selon la revendication 6, dans lequel le liquide est le second liquide.
     
    9. Appareil selon l'une quelconque des revendications précédentes, dans lequel la structure de séparation (2, 3) est une structure d'osmose inverse.
     
    10. Appareil selon l'une quelconque des revendications 1 à 8, dans lequel la structure de séparation (2, 3) est une structure de filtration.
     
    11. Appareil selon l'une quelconque des revendications précédentes, comprenant une structure de démarrage pour définir l'accélération de la structure d'entraînement (13, 14).
     
    12. Appareil selon l'une quelconque des revendications précédentes, dans lequel la pompe volumétrique (11) pour une TR/MIN fixe fournit un rapport fixe entre le déplacement de liquide et la TR/MIN.
     
    13. Appareil selon l'une quelconque des revendications précédentes, dans lequel la structure d'entraînement (13, 14) comprend un moteur entraîné électriquement (14) avec une TR/MIN variable.
     
    14. Procédé de fonctionnement d'un appareil de traitement de liquide selon l'une quelconque des revendications 1 à 13, le procédé comprenant l'étape consistant à entraîner la pompe volumétrique et l'unité de récupération de façon synchrone à des vitesses différentes suivant la consommation d'un liquide qui est reçu à partir de la structure de séparation.
     
    15. Procédé selon la revendication 14, comprenant l'étape consistant à régler un gradient de pression dans la structure de séparation en réglant une accélération d'une rotation synchrone de l'élément de pompe et de l'élément de récupération.
     
    16. Procédé selon la revendication 14 ou 15, comprenant les étapes consistant à appliquer de l'eau douce sur l'entrée et entraîner la pompe volumétrique et l'unité de récupération de façon synchrone à une vitesse qui est inférieure à une vitesse qui est nécessaire pour activer la perméation d'eau salée à travers la membrane.
     




    Drawing














    Cited references

    REFERENCES CITED IN THE DESCRIPTION



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    Patent documents cited in the description