System for reverse osmosis and pressure retarded osmosis

Abstract

The invention relates to a system for reverse osmosis (RO) and pressure retarded osmosis (PRO), the system comprising: a RO subsystem having a high pressure RO compartment and a low pressure RO compartment separated by a RO membrane, the high pressure RO compartment having a RO feed inlet and a brine outlet, and the low pressure RO compartment having a permeate outlet; a PRO subsystem having a high pressure PRO compartment and a low pressure PRO compartment separated by a PRO membrane, the high pressure PRO compartment having a draw inlet and a draw outlet, and the low pressure PRO compartment having a PRO feed inlet and a PRO feed outlet; an induction motor having a stator and a rotor, wherein the rotor is mechanically connected to an input shaft of a hydraulic pump and to an output shaft of a hydraulic motor, the hydraulic pump being configured for providing a feed solution to the RO feed inlet, the hydraulic motor being configured for receiving a draw solution from the draw outlet. The invention also relates to a method for operating such a RO / PRO system and to a use of such a system.

Description

Technical Field

[0001] This invention relates to a system for reverse osmosis and pressure-delayed osmosis, and more particularly to a system for combined operation of the two processes. The invention also relates to a method for operating (e.g., operating independently) such a system, and to using such a system for producing freshwater adjacent to salt and / or other minerals. Background Technology

[0002] Osmosis is the process by which a solvent moves through a semipermeable membrane from the side of the membrane facing a lower solute concentration towards the side facing a higher solute concentration. The movement of solvent particles is driven by diffusion, and overall, more solvent particles diffuse toward the higher solute concentration (i.e., lower water potential), resulting in a net movement of solvent. This naturally occurring process forms the basis of both reverse osmosis and pressure-delayed osmosis.

[0003] In reverse osmosis, pressure exceeding the osmotic pressure is applied to the side with the higher solute concentration, thereby restoring the energy balance of the osmosis system and causing a net diffusion motion across the membrane from high to low solute concentration, thus increasing the solvent concentration at the pressurized membrane side. A reverse osmosis system includes at least two chambers separated by a semi-permeable membrane, wherein the inflow and outflow of the chambers can be controlled to set volumetric flow conditions and a pressure gradient across the membrane.

[0004] Reverse osmosis (RO) is frequently used in water purification or desalination applications. In these applications, RO produces a high concentration of brine next to the purified and / or desalinated water. The brine is retained on the pressurized side of the membrane, while the purified and / or desalinated water (permeate) is removed from the other membrane side under low pressure. Removing the pressurized brine from the RO chamber prevents excessive osmotic pressure buildup and allows fresh feed solution to flow into the chamber. Energy recovery devices, such as the Danfoss iSave unit, are known to be used to transfer hydraulic energy from the pressurized brine to the feed solution, thereby improving the overall energy efficiency of the reverse osmosis process.

[0005] Pressure delayed osmosis (PRO) is a process that builds upon forward osmosis by applying net flow toward a higher solute concentration while external pressure is applied again via a reverse osmosis pressure gradient. In PRO, energy can be generated based on the concentration (e.g., salinity), the gradient between the feed solution and the drive solution, and the upper limit of recoverable energy is defined by the Gibbs free energy associated with mixing these solutions. In practice, the concentrated drive solution (e.g., seawater) and the feed solution (e.g., brackish water or fresh water (e.g., river water)) are separated by a semi-permeable membrane, and water diffuses from the feed side to the pressurized drive solution side. To recover the generated hydraulic energy, the resulting pressurized and diluted drive solution can be supplied to a turbine to generate electricity.

[0006] It is evident that the RO and PRO processes are well-suited for combination, as the RO process produces concentrated brine solutions, while the PRO process extracts energy from the concentration gradient. Therefore, various studies have analyzed the thermodynamic potential of these process combinations. Among these, it has been found that the combination of PRO and RO allows, for example, reducing the cost of the RO process for seawater desalination, and allows for the dilution of RO brine solutions to reduce their environmental impact. Furthermore, a prototype RO-PRO hybrid unit has been developed in Japan's national development project, the "Mega-ton Water System," which utilizes RO brine in the PRO process.

[0007] However, known research on RO-PRO hybrid systems focuses more on thermodynamic models for improving the energy efficiency of the combined process than on practical methods for achieving such hybrid systems. For example, although the use and effects of so-called energy recovery devices (ERDs) are frequently considered in previous publications (e.g., see Altaee et al., Integration and optimization of pressure retarded osmosis with reverse osmosis for power generation and high efficiency desalination, Energy 103 (2016), pp. 110-118), details regarding the construction and operation of such ERD devices are often neglected.

[0008] Therefore, the object of the present invention is to overcome or at least reduce the disadvantages of the prior art and to provide a combined system of reverse osmosis and pressure delayed osmosis that has improved efficiency and allows for a variety of operating conditions. Summary of the Invention

[0009] The present invention achieves its objectives and overcomes or at least reduces the disadvantages of the prior art through the system for reverse osmosis (RO) and pressure delayed osmosis (PRO) of the present invention, and through the method for operating such a system for RO and PRO.

[0010] One aspect of the present invention relates to a system for reverse osmosis (RO) and pressure delayed osmosis (PRO), comprising an RO subsystem and a PRO subsystem.

[0011] The RO subsystem includes a high-pressure RO chamber and a low-pressure RO chamber separated by an RO membrane. The high-pressure and low-pressure RO chambers preferably form an RO tank configured to accommodate the RO process and withstand the pressures generated. The high-pressure RO chamber has an RO feed inlet and a brine outlet, and is configured to receive the RO feed solution via the RO feed inlet. The low-pressure RO chamber has a permeate outlet and is configured to receive permeate, i.e., a drive solution with a reduced solute concentration, via the RO membrane. The permeate is removed from the low-pressure RO chamber via the permeate outlet at a first RO pressure, while the upwardly concentrated drive solution (brine) is removed from the high-pressure RO chamber via the brine outlet at a second RO pressure. The first RO pressure is lower than the second RO pressure.

[0012] The RO membrane is configured to allow the solvent of the feed solution to diffuse under external pressure applied to the high-pressure RO chamber. In a preferred embodiment, the feed solution is brine, such as seawater, and the RO membrane is configured to allow water to diffuse through the membrane while preventing salt ions (e.g., Na+) from diffusing through it. + and Cl - The RO membrane allows organic matter, bacteria, and pyrogens to pass through. Preferably, the RO membrane is also configured to prevent the passage of organic matter, bacteria, and pyrogens. The RO membrane is preferably a cellulose acetate (CA) membrane or a polysulfone membrane, which may be further coated with an aromatic polyamide. Also preferred are nanostructured RO membranes, zeolite membranes, and / or spiral-wound RO membranes.

[0013] The PRO subsystem includes a high-pressure PRO chamber and a low-pressure PRO chamber separated by a PRO membrane. These two chambers preferably form a PRO tank configured to contain the PRO process and withstand the pressures generated. The low-pressure PRO chamber has a PRO feed inlet and a PRO feed outlet, and is configured to receive a PRO feed solution via the PRO feed inlet and to supply (output) a PRO feed solution via the PRO feed outlet. The PRO feed solution output via the PRO feed outlet is preferably concentrated compared to the PRO feed solution received via the PRO feed inlet. The PRO feed solution is received at the PRO feed inlet at a first PRO pressure, and output at the PRO feed outlet at a second PRO pressure lower than the first PRO pressure.

[0014] The high-pressure PRO chamber has a drive inlet configured to receive a drive solution and is further configured to receive the solvent of the PRO feed solution via a PRO membrane. The high-pressure PRO chamber also has a drive outlet configured to provide (output) a diluted drive solution. The drive solution has a higher solute concentration than the PRO feed solution. Exemplarily, the drive solution is brine and the PRO feed solution is fresh water. However, the drive solution can also be a solution of another (mineral) solute, wherein the PRO feed solution includes a lower concentration of said (mineral) solute. Preferably, the drive solution is a brine or mineral solution output from the high-pressure RO chamber. The drive solution is received at a third PRO pressure and volumetric flow rate, while a diluted drive solution is output at a fourth PRO pressure and volumetric flow rate, wherein the fourth pressure is at least the same as the third PRO pressure, and the volumetric flow rate of the diluted drive solution is increased relative to the volumetric flow rate of the drive solution.

[0015] The PRO membrane is configured to allow the solvent of the PRO feed solution to diffuse under pressure applied to the high-pressure PRO chamber. In a preferred embodiment, the PRO feed solution is brine, such as seawater or fresh water, and the PRO membrane is configured to allow water to diffuse through the membrane while preventing salt ions (e.g., Na+) from diffusing through it. + and Cl - The PRO membrane is preferably configured to prevent organic matter, bacteria, and pyrogens from passing through it. The PRO membrane is preferably one of a cellulose acetate (CA) membrane, a film composite membrane (TFC) (e.g., a composite sheet comprising polysulfone (PSF) and polyamide, or a composite sheet comprising polyacrylonitrile (PAN) and polyamide), and a hollow fiber PRO membrane (e.g., made of polyethersulfone (PES), polyetherimide, etc.).

[0016] In the system of the present invention, a hydraulic pump configured to supply feed solution to the RO feed inlet is mechanically connected to a hydraulic motor configured to receive drive solution from the drive outlet of the PRO chamber. In other words, the hydraulic pump driving the RO subsystem is mechanically connected to the hydraulic motor that generates power in the PRO subsystem. Therefore, in the RO and PRO system according to the present invention, the RO subsystem and the PRO subsystem are mechanically connected. This allows for advantageous operating modes, as described in more detail below. In short, this configuration allows energy to be transferred directly from the PRO subsystem to the RO subsystem without conversion losses, particularly without any losses due to the conversion of mechanical energy to electrical energy in the PRO side, and without losses due to the conversion of electrical energy to mechanical energy in the RO side.

[0017] The mechanical connection between the hydraulic motor and the hydraulic pump is preferably a direct mechanical connection, for example, via a common drive shaft of the hydraulic motor and the hydraulic pump, via a pinion, drive belt, and / or drive shaft. A portion of the common drive shaft can serve as the output shaft of the hydraulic motor, and another portion can serve as the input shaft of the hydraulic pump. In this case, energy can be transferred between the RO subsystem and the PRO subsystem via the direct mechanical connection, for example, in the form of torque and / or speed. More specifically, the hydraulic energy (volume flow rate, pressure) in the PRO subsystem is converted into mechanical energy (torque, speed) by the hydraulic motor and transferred to the RO subsystem via the direct mechanical connection, where the hydraulic energy is converted back into hydraulic energy (volume flow rate, pressure) by the hydraulic pump.

[0018] In such an embodiment, the hydraulic energy used in the PRO subsystem and / or consumed in the RO subsystem can be adapted to match each other, thereby allowing for trouble-free direct mechanical connection. Exemplarily, the pressure drop at the hydraulic motor can be adjusted (e.g., reduced) to accommodate (e.g., reduce) the hydraulic energy converted into mechanical energy there. Similarly, the pressure rise at the hydraulic pump can be adjusted (e.g., increased) to match the mechanical energy supplied via a common shaft. This adaptation can be performed using an adjustable valve.

[0019] More preferably, the mechanical connection is an indirect mechanical connection, such as via a gearbox, transmission, and / or clutch. In such an embodiment, preferably, the output shaft of the hydraulic motor is mechanically connected to the input shaft of the hydraulic pump via a gearbox, transmission, and / or clutch. An indirect mechanical connection advantageously allows for more efficient matching of the power output of the PRO subsystem and the energy input of the RO subsystem, and eliminates the need to control the flow processes in said subsystems. Exemplarily, the speed and / or torque provided via the output shaft of the hydraulic motor, via a gearbox, can be adapted to the speed and / or torque required by the input shaft of the hydraulic pump. Simultaneously, the hydraulic processes in the RO and PRO subsystems can remain identical. In this way, an indirect mechanical connection allows for trouble-free operation of the system, for example, by avoiding overload of mechanical components and power distribution.

[0020] In a preferred embodiment, the system of the present invention further includes an induction motor, particularly an asynchronous AC motor, having a stator and a rotor. Preferably, the induction motor is a three-phase squirrel-cage motor configured to operate at a substantially constant (rotational) speed assuming a given AC input frequency and winding configuration (pole adjustment). Particularly preferred is that the induction motor is a doubly-fed induction generator (DFIM), such as a doubly-fed induction generator (DFIG) or a doubly-fed wound-rotor asynchronous motor (DASM), configured to operate at a variable (rotational) speed assuming a given winding configuration (pole adjustment). In a DFIM, DFIG, or DASM, the stator is preferably directly connected to an AC power source (e.g., an energy storage device or a power grid), while the rotor is connected to the AC power source via a frequency converter. In other words, the induction motor is configured as a fixed-speed generator (FSG) or an adjustable-speed generator (ASG), wherein the latter can be configured as a direct-online ASG system or a DFIG ASG system, preferably including an IGBT converter.

[0021] Technicians are familiar with various designs of this induction motor, which are commonly used in a variety of industrial applications, such as wind turbines. Exemplary designs, schematics, and circuit diagrams are disclosed, for example, in S. MÜLLER; S. et al. (2002), “Doubly Fed Induction Generator Systems for Wind Turbines” (PDF); IEEE Journal of Industrial Applications; IEEE.8(3):26-33; doi:10.1109 / 2943.9996 10, and in Roberts, Paul C. (2004), “Study of Brushless Doubly-Fed (Induction) Machines; Contributions in Machine Analysis, Design and Control” (PDF); Emmanuel College, University of Cambridge. The entire contents of the above documents are incorporated herein by reference.

[0022] According to this preferred embodiment, the rotor of the induction motor is mechanically connected to the input shaft of a hydraulic pump configured to supply feed solution to the RO feed inlet. The rotor of the induction motor is also mechanically connected to the output shaft of a hydraulic motor configured to receive drive solution from the drive outlet of the PRO chamber. In other words, the rotor of the induction motor is mechanically connected to both the hydraulic pump driving the RO subsystem and the hydraulic motor generating electricity in the PRO subsystem. In other words, in this embodiment, there is also an indirect mechanical connection between the RO subsystem and the PRO subsystem. In the context of this application, input / output shaft refers to any mechanical component (e.g., a pinion gear) configured to transmit mechanical energy input / output by a given device. The mechanical connection between the rotor and the hydraulic motor and / or hydraulic pump is a direct mechanical connection (e.g., via the common shaft of the induction motor) or an indirect mechanical connection (e.g., via a gearbox). Particularly preferably, the induction motor is a dual-shaft induction motor or a double-shaft induction motor, wherein the rotor is connected to two shafts, one of which is then preferably connected to the hydraulic motor and the other to the hydraulic pump.

[0023] In the RO and PRO system according to this preferred embodiment, the RO subsystem and the PRO subsystem—that is, the hydraulic pump in the RO subsystem configured to supply feed solution to the RO feed inlet and the hydraulic motor in the PRO subsystem configured to receive drive solution from the drive outlet—are mechanically connected via the rotor of an induction motor. This again allows energy to be transferred directly from the PRO subsystem to the RO subsystem without conversion losses, particularly without losses due to electrical power conversion in power converters (e.g., AC / DC, AC / AC, or DC / DC converters or frequency converters).

[0024] Furthermore, the combination of the hydraulic motor, induction motor, and hydraulic pump can be operated (configured for operation) at net positive power production, wherein the generated power can be advantageously allocated and / or used for other electrical equipment in the operating system, such as feed pumps, etc. Additionally, the system configuration allows for easy compensation of energy differences between the PRO and RO subsystems by adding or drawing power from the system. Preferably, the induction motor is capable of operating with variable slip, wherein a positive slip corresponds to an operating mode in which energy is consumed by the induction motor, and wherein a negative slip corresponds to an operating mode in which electrical energy is generated by the induction motor (i.e., where the induction motor acts as a generator).

[0025] In yet another preferred embodiment, the system of the present invention further includes a feed solution reservoir connected to the RO feed inlet via a hydraulic pump. Additionally or alternatively, the feed solution reservoir is also connected to the drive outlet via a hydraulic motor. Exemplarily, the feed solution reservoir is a seawater reservoir that supplies the RO feed solution to the RO subsystem and receives diluted PRO drive solution, preferably diluted RO brine, from the PRO drive outlet. More preferably, the feed solution reservoir is also connected to the PRO feed inlet. In such a configuration, the brine output of the RO subsystem is preferably connected to the drive inlet, thus advantageously ensuring a concentration gradient for operating the PRO subsystem. This setup with only a single feed solution reservoir is advantageously a simple configuration.

[0026] In another preferred embodiment, the system further includes a drive solution reservoir, distinct from the feed solution reservoir and connected to the brine outlet, drive inlet, drive outlet, and ultimately to the PRO feed outlet. Such a drive solution reservoir preferably allows for the separate collection of higher concentration solutions from the feed solution reservoir. This has no positive ecological impact and allows for further advantageous operating modes of the system, such as for upward concentration and mineral harvesting. The drive solution reservoir can be constructed as a tank, such as a closed tank, or as an open reservoir, such as an artificial lake. The drive solution reservoir further preferably includes a concentrate outlet for supplying the upwardly concentrated solution to subsequent processes, such as an evaporator, another PRO stage, etc. Further details of the operating modes of a system with such a drive solution reservoir are described below.

[0027] In the system of the present invention, the hydraulic pump is preferably an axial piston pump. Such an axial piston pump includes a mechanical shaft (input shaft) connected to a rotating swashplate that carries a plurality of pistons arranged inside a cylinder. The pistons can be axially oriented (i.e., parallel to the axis of the shaft). A cam angle between the normal vector of the rotating swashplate and the axis of the shaft determines the pump displacement, and the extension and reciprocating motion of the pistons is achieved based on the relative rotation of the rotating swashplate and the cylinder. This movement of the pistons is used to transfer (pump) fluid from the pump inlet to the pump outlet, both of which can be located in ports and valve plates. The use of an axial piston pump in this system advantageously allows for positive displacement pumping with minimal moving parts and seals, as well as oil-free lubrication. Exemplarily, the hydraulic pump used in the system of the present invention is a Danfoss APP high-pressure pump.

[0028] More preferably, (additionally or alternatively) the hydraulic motor is an axial piston motor. The axial piston motor also includes a mechanical shaft (output shaft) connected to a swashplate that carries multiple pistons arranged inside the cylinder. Similarly, the pistons can be axially oriented (i.e., parallel to the axis of the shaft). The cam angle between the normal vector of the swashplate and the axis of the shaft determines the motor's displacement. Applying pressurized fluid to the pistons via the motor inlet (generator inlet) enables the piston's extension and reciprocating motion, as well as the relative rotation of the swashplate and the cylinder. The output (rotational) speed of the axial piston motor is proportional to the input flow rate, and its drive torque is proportional to the pressure difference between the motor inlet and outlet. Using an axial piston motor in this system advantageously allows for the generation of rotational energy from pressurized fluid with minimal moving parts and seals, and without oil lubrication. Another important advantage is that the axial piston pump / motor allows for a wide operating window in terms of both pressure and flow rate while still maintaining relatively high energy efficiency. Exemplarily, the hydraulic pump is one of the Danfoss high-pressure PAH pump, the Danfoss MP1 axial piston motor, and the H1 bent-axis variable motor. The use of axial piston motors and axial piston pumps further allows for systems with high symmetry (and therefore ease of maintenance) and low vibration.

[0029] In a preferred embodiment, at least one of the hydraulic pump and the hydraulic motor has an adjustable displacement. Particularly preferably, the hydraulic pump is an adjustable displacement axial piston pump and / or the hydraulic motor is an adjustable displacement axial piston motor. In other words, preferably, one of the axial piston pump and the axial piston motor has an adjustable stroke displacement. By utilizing a variable displacement pump and a variable displacement motor connected to the same induction motor, the operating conditions of the system can be advantageously and precisely controlled. Exemplarily, during system startup, the displacement of the axial piston motor can be set to a minimum (cam / swashplate angle almost zero), while the displacement of the axial piston pump can be set to a permissible maximum (cam / swashplate angle increases). Once the system is running, i.e., fluid output from the brine outlet is supplied to the drive input, the displacement of the axial piston pump (cam / swashplate angle) can decrease, while the displacement of the axial piston motor (cam / swashplate angle) increases to the permissible maximum.

[0030] More preferably, the axial piston pump and / or hydraulic piston motor can have direct displacement control via mechanical, electromechanical, or hydraulic mechanical means. The control circuits of the axial piston pump and / or hydraulic piston are preferably connected, for example, to allow combined control of the pump and motor. Also preferably, the axial piston pump and / or hydraulic piston motor can each be pressure-compensated. The pressure compensation can be configured to regulate the pump's output flow to maintain a predetermined pressure at the pump outlet and / or regulate the motor's input flow to maintain a predetermined pressure at the motor inlet. More preferably, the pressure compensation is configured to control the motor's input flow to maintain a predetermined pressure at the pump outlet and / or regulate the pump's output flow to maintain a predetermined pressure at the motor inlet. Such a configuration advantageously prevents overpressure at the pump (RO) side, which could be caused by increased inflow to the motor (PRO) side, and this pressure compensation can even be used with fixed connections between the pump input shaft and the motor output shaft to the rotor of an induction motor.

[0031] According to a preferred embodiment, the induction motor is connected to the power grid and / or an energy storage device. The connection to the energy storage device advantageously allows for independent operation of the system, where the energy storage device is used to compensate for the difference in hydraulic energy between the PRO and RO subsystems by adding or drawing power from the system. The energy storage device is preferably a battery, such as a lithium-ion battery, but can also be another form of energy storage device, such as a hydrostatic reservoir. Connecting the induction motor to the power grid further increases the system's versatility and also allows for operation under cold-start conditions using energy from the grid. The induction motor can be directly connected to the power grid or connected to the AC output of the energy storage device. The synchronous speed of the induction motor is preferably defined by the AC frequency and can be adjusted using a gearbox or highly adjustable windings. The induction motor can also be connected to the power grid or energy storage device via a power converter, preferably via a (IGBT-based) frequency converter, etc.

[0032] In a particularly preferred embodiment of the disclosed system, the displacement of the hydraulic pump is lower than that of the hydraulic motor. In other words, the stroke displacement of the axial piston pump is lower than that of the axial piston motor. The displacement of the hydraulic pump can be set or configured to be lower than that of the hydraulic motor. In such a configuration, the pressure and / or volumetric flow rate at the inlet of the hydraulic motor in the PRO subsystem exceeds the pressure and / or volumetric flow rate at the outlet of the hydraulic pump in the RO subsystem; that is, the hydraulic energy at the motor exceeds the hydraulic energy at the pump. Since both the motor and the pump are connected to the rotor of an induction motor, the induction motor will operate with a negative slip rate, i.e., the motor operates above the synchronous speed of the stator, and thus supplies power to the energy storage device and / or the power grid.

[0033] In another preferred embodiment, at least one of the hydraulic pump and hydraulic motor is configured to operate at a variable delta pressure (Δp). This delta pressure refers to the pressure difference between the pump / motor inlet and outlet. Particularly preferably, the pressure drop at the hydraulic motor and / or the pressure rise at the hydraulic pump can be regulated. This regulation can be made via an inlet or outlet valve of the pump and / or motor. Preferably, the hydraulic motor is configured to operate at a higher delta pressure than the hydraulic pump (operating at a higher delta pressure). In other words, the pressure difference at the hydraulic motor exceeds the pressure difference at the hydraulic pump. Exemplarily, the hydraulic motor in the PRO subsystem receives working fluid at a pressure of approximately 200 bar and outputs working fluid at a reduced pressure of approximately 2 bar, while the hydraulic pump in the RO subsystem receives a corresponding working fluid at a pressure of approximately 2 bar and outputs it at a pressure of approximately 60 bar. In such a setup, the displacement of the hydraulic pump can be greater than that of the hydraulic motor (e.g., up to 3 times), while still achieving net positive energy production.

[0034] In other words, by setting the fluid flow rate and / or delta pressure of the hydraulic motor to exceed the fluid flow rate or delta pressure of the hydraulic pump through default settings or by setting variable displacement and / or by adjusting the valves of the hydraulic motor and / or hydraulic pump, the system of the present invention advantageously allows for RO-PRO combined operation and the generation of excess electrical energy in a simple, compact, and robust setup. The excess energy generated in the system can be supplied to an energy storage device and / or the power grid, and can also be used within the system itself. Exemplarily, the system preferably further includes at least one feed pump in the RO subsystem and / or the PRO subsystem. The at least one feed pump is preferably supplied directly or via the power grid and / or energy storage device by the excess energy generated in the induction motor.

[0035] In a preferred embodiment, the system of the present invention further includes at least one energy recovery device (ERD) configured to transfer hydraulic energy from the input flow to the output flow. Exemplarily, such an ERD is interconnected between the brine outlet and the RO feed inlet. Additionally or alternatively, such an ERD is interconnected between the drive outlet and the drive inlet. More preferably, such an ERD is interconnected between the PRO subsystem and the RO subsystem. Particularly preferred is that the ERD is a Danfoss iSave device. However, other ERDs may also be used in the disclosed system. The use of such an ERD advantageously further improves the overall energy efficiency of the system.

[0036] Another aspect of the invention relates to a method for operating a system according to the invention for reverse osmosis (RO) and pressure delayed osmosis (PRO) as described above. The method of the invention includes at least the steps of supplying a feed solution to the RO feed inlet via a hydraulic pump at a first pressure and a first volumetric flow rate, receiving a drive solution from the drive outlet via a hydraulic motor at a second pressure and a second volumetric flow rate, and transferring energy from the hydraulic pump configured to supply the feed solution to the RO feed inlet to the hydraulic motor configured to receive the drive solution from the drive outlet via a mechanical connection. Therefore, the method of the invention advantageously allows energy transfer between the RO and PRO subsystems without electrical conversion losses. Details of the (direct or indirect) mechanical connections and related operating modes have been discussed above, and for the sake of brevity, repeated descriptions are omitted.

[0037] Preferably, the method further includes the steps of operating the system in a first operating mode with net energy consumption and operating the system in a second operating mode with net energy production. In the first operating mode, the energy transferred from the PRO subsystem to the RO subsystem is not entirely sufficient to operate the entire system, while in the second operating mode, the transferred energy is sufficient. Furthermore, in the second operating mode, energy transfer can be regulated by manipulating flow and / or pressure conditions in the RO and / or PRO subsystems (e.g., via adjustable valves), by manipulating indirect mechanical connections (e.g., gearboxes), or by manipulating induction motors.

[0038] In another preferred embodiment, the system of the present invention includes an induction motor having a stator and a rotor as described above, wherein the rotor is mechanically connected to the input shaft of a hydraulic pump and the output shaft of a hydraulic motor. In this embodiment, the method further includes the step of operating the induction motor with a slip rate based on a first pressure and a ratio of a first volumetric flow rate to a second pressure and a second volumetric flow rate. In other words, in the method of the present invention, the ratio of hydraulic energy in the RO subsystem and the PRO subsystem is advantageously connected to the slip rate of the induction motor mechanically connecting the RO subsystem and the PRO subsystem. Therefore, the method of this preferred embodiment advantageously allows for simple control via the slip rate of the induction motor.

[0039] In a preferred embodiment of the method of the present invention, the induction motor is connected to an energy storage device as part of the RO and PRO systems and / or connected to the power grid (electricity grid). According to this embodiment, the method further includes the step of operating the system in a first operating mode, wherein the induction motor operates with positive slip and consumes electrical energy from the energy storage device and / or the power grid. In other words, in the first operating mode, the hydraulic energy required by the RO subsystem exceeds the hydraulic energy provided by the PRO subsystem, and the difference in hydraulic energy is compensated via the induction motor. The method further includes the step of operating the system in a second operating mode, wherein the induction motor operates with negative slip and supplies electrical energy to the energy storage device and / or the power grid. In other words, in the second operating mode, the hydraulic energy provided by the PRO subsystem exceeds the hydraulic energy required by the RO subsystem, and the excess hydraulic energy is converted by the induction motor.

[0040] The first and second operating modes described above can be implemented in the disclosed system by design, for example, by using a hydraulic pump with a stroke displacement (significantly) smaller than that of the hydraulic motor, thereby allowing excess energy conversion via an induction motor whose rotor is connected to the shafts of both the motor and the pump. In another example, the hydraulic motor is configured to operate at a higher delta pressure than the hydraulic pump (operating at a higher delta pressure), and / or other components of the PRO and / or RO subsystems (e.g., valves) can be adjusted to set the desired delta pressure.

[0041] However, in a further preferred embodiment, at least one of the hydraulic pump and hydraulic motor of the disclosed system has an adjustable displacement and / or an adjustable delta pressure. In such a preferred embodiment, the method further includes the step of adjusting the displacement ratio of the hydraulic pump and hydraulic motor to be greater than 1 in a first operating mode. Such a displacement ratio is preferably related to the pressure at the motor inlet of the PRO subsystem (which exceeds the pressure at the pump outlet in the RO subsystem). Alternatively or additionally, the method further includes the step of adjusting the delta pressure of the hydraulic motor to be less than the delta pressure of the hydraulic pump, for example, by using an adjustable valve, in the first operating mode.

[0042] In the second operating mode, the displacement ratio of the hydraulic pump and the hydraulic motor is preferably adjusted to be less than 1. This displacement ratio is preferably related to the pressure at the inlet of the PRO motor (which is less than the pressure at the outlet of the RO pump). Alternatively or additionally, the method may also include, in the second operating mode, adjusting the delta pressure of the hydraulic motor to be greater than the delta pressure of the hydraulic pump, for example, by using an adjustable valve.

[0043] According to this preferred embodiment of the disclosed method, the first operating mode can be dynamically changed to a second operating mode and then back by adjusting the displacement and / or delta pressure of the hydraulic pump and / or hydraulic motor. This embodiment advantageously provides the system with the ability to freely set the operating mode, which advantageously allows for the setting of optimal operating conditions, for example, during startup, or when the flow and / or pressure in the PRO subsystem changes, or when it is necessary to increase the RO water production.

[0044] In another preferred embodiment, the system of the present invention includes at least one feed pump located in the RO subsystem and / or the PRO subsystem, and the method of the present invention further includes the step of operating at least one feed pump with electrical energy from an energy storage device. This electric feed pump, supplementing the hydraulic pump, preferably operates at least during a portion of the system's operating time. Exemplarily, during system startup, the PRO subsystem may not generate sufficient energy to power the system (e.g., due to a lack of RO brine as the feed solution), while the RO subsystem requires energy input to operate. In this case, the induction motor can operate with positive slip and drive the hydraulic pump. Furthermore, in this case, at least one feed pump in the RO subsystem and ultimately the PRO subsystem can be driven with energy from the energy storage device. Operating at least one feed pump allows the use of a combination of hydraulic pump, induction motor, and hydraulic motor, which is optimized for stable system operation and particularly effective during stable system operation. However, the at least one feed pump can also operate during stable system operation to maintain a longer flow distance and to reduce the load on the hydraulic pump. The at least one feed pump can be powered by the energy storage device via the mains or directly by the induction motor via appropriate control and connection.

[0045] In another preferred embodiment, the system of the present invention further includes a seawater reservoir connected via a hydraulic pump to the RO feed inlet and also to the PRO feed inlet. The system also includes a drive solution reservoir connected via a hydraulic motor to the drive outlet and further connected to the drive inlet and brine outlet. In this configuration, the system can not only provide demineralized water as RO permeate but also provide power using the concentrated feed solution (brine) from the PRO process and RO. The system can also be used to collect minerals, such as salts. In such a preferred embodiment, the method of the present invention further includes collecting brine from the brine outlet in the drive solution reservoir and providing drive solution from the drive solution reservoir to the PRO drive inlet, and receiving diluted drive solution from the PRO drive outlet in the drive solution reservoir. In other words, the stock solution reservoir acts as a buffer between the RO and PRO processes and further receives diluted PRO stock solution generated during the PRO process. Therefore, the net inflow to the stock solution is determined by the volumetric flow rate at the brine outlet and the volumetric flow rate through the PRO membrane, where the latter corresponds to the difference between the volumetric flow rate at the PRO drive outlet and the volumetric flow rate at the PRO drive inlet.

[0046] The brine concentration corresponds to the baseline concentration of the stock solution reservoir, while the volumetric flow rate through the PRO membrane has a lower solute concentration (almost zero) than that of the stock solution reservoir, resulting in dilution of the stock solution reservoir. The method of this embodiment also includes the step of evaporating solvent from the drive solution reservoir, wherein the solvent evaporation rate exceeds the difference between the volumetric flow rate at the PRO drive outlet and the volumetric flow rate at the PRO drive inlet, i.e., it exceeds the volumetric flow rate through the PRO membrane. By controlling the inflow to the stock solution reservoir and maintaining such an evaporation rate, the solute concentration in the stock solution reservoir will continuously increase, allowing the stock solution reservoir to be used directly or by driving the upward-concentrated stock solution for mineral (salt) harvesting. With further inflows and / or outflows into the stock solution reservoir, the evaporation rate must be set at least high enough to maintain a constant concentration in the stock solution reservoir. The evaporation rate can be adjusted, for example, by setting the dimensions of the stock solution reservoir, particularly the surface dimensions, to be in thermal equilibrium with the surrounding environment. Additionally and / or alternatively, an additional heat source may be used. The concentrated stock solution can also be removed from the drive solution reservoir and supplied to another subsequent PRO process to generate electricity.

[0047] Another aspect of the invention relates to the use of a system for reverse osmosis (RO) and pressure delayed osmosis (PRO) according to the invention as described above. The system includes a seawater reservoir connected via a hydraulic pump to both the RO feed inlet and the PRO feed inlet. The system also includes a drive solution reservoir connected via a hydraulic motor to the PRO drive outlet and further connected to a brine outlet. According to this aspect of the invention, the system is used to concentrate salts and / or other minerals in the drive solution reservoir, to extract salts and / or other minerals from the drive solution reservoir, and to provide fresh water from the permeate outlet. To achieve this use, the system can be operated according to the method of the invention as described above. It is also preferred that the system further utilizes an induction motor to generate electrical energy.

[0048] Other aspects and preferred embodiments of the invention derive from the dependent claims, the drawings, and the following description of the drawings. Unless otherwise expressly stated, the different embodiments disclosed are advantageously combined with each other. Attached Figure Description

[0049] The features of the present invention will become apparent to those skilled in the art from the detailed description of exemplary embodiments with reference to the accompanying drawings, wherein:

[0050] Figure 1 The RO and PRO systems according to the first embodiment are shown;

[0051] Figure 2 The RO and PRO systems according to the second embodiment are shown;

[0052] Figure 3 The RO and PRO systems according to the third embodiment are shown;

[0053] Figure 4 The RO and PRO systems according to the fourth embodiment are shown;

[0054] Figure 5 The RO and PRO systems according to the fifth embodiment are shown;

[0055] Figure 6 The RO and PRO systems according to the sixth embodiment are shown;

[0056] Figure 7 The RO and PRO systems according to the seventh embodiment are shown;

[0057] Figure 8 The RO and PRO systems according to the eighth embodiment are shown;

[0058] Figure 9 The RO and PRO systems according to the eighth embodiment are shown;

[0059] Figure 10 A method for RO and PRO according to one embodiment is shown; and

[0060] Figure 11 A method for RO and PRO according to another embodiment is shown. Detailed Implementation

[0061] Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings. The effects and features of exemplary embodiments and their implementation methods will be described with reference to the drawings. In the drawings, the same reference numerals denote the same elements, and redundant descriptions are omitted. The invention can be embodied in various different forms and should not be construed as being limited to the embodiments shown herein. These embodiments are provided as examples so that the invention will be complete and will fully convey aspects and features of the invention to those skilled in the art.

[0062] Therefore, elements that are deemed unnecessary by those skilled in the art for a full understanding of the features of the invention may not be described.

[0063] As used herein, the term “and / or” includes any and all combinations of one or more of the related listed items. Furthermore, in describing embodiments of the invention, the use of “may” refers to “one or more embodiments of the invention.” In the following description of embodiments of the invention, singular terms may include plural terms unless the context clearly indicates otherwise.

[0064] It should be understood that although the terms "first" and "second" are used to describe various different elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element may be named a second element without departing from the scope of the invention, and similarly, a second element may be named a first element. As used herein, the terms "basically," "about," and similar terms are used as approximate terms rather than terms of degree and are intended to describe the inherent deviations of measured or calculated values ​​that will be recognized by those skilled in the art. Furthermore, if the term "basically" is used in conjunction with a feature that can be expressed numerically, the term "basically" indicates a range of + / -5% of the value centered on that value.

[0065] Figure 1 A system for reverse osmosis (RO) and pressure delayed osmosis (PRO) according to a first embodiment is schematically illustrated. The system includes an RO subsystem 10 and a PRO subsystem 20, which... Figure 1 The dashed box indicates the area.

[0066] The RO subsystem 10 includes a high-pressure RO chamber 11 and a low-pressure RO chamber 12, which are separated by an RO membrane 13 and together form an RO tank. The high-pressure RO chamber 11 has an RO feed inlet 14 and a brine outlet 15, while the low-pressure RO chamber 12 has a permeate outlet 16. Preferably, each inlet and outlet is valve-controlled, wherein an active valve or a passive valve (e.g., a check valve) can be used.

[0067] The PRO subsystem 20 includes a high-pressure PRO chamber 21 and a low-pressure PRO chamber 22, which are separated by a PRO membrane 23 and together form a PRO tank. The high-pressure PRO chamber 21 has a drive inlet 24 and a drive outlet 25, and the low-pressure PRO chamber 22 has a PRO feed inlet 26 and a PRO feed outlet 27. Each inlet and outlet can be valve-controlled by an active valve and / or a passive valve.

[0068] The system also includes a feed solution reservoir 40, which contains the feed solution. The feed solution reservoir 40 can be, for example, a pool, stream, or ocean. The feed solution reservoir 40 is connected to the RO subsystem 10 and the PRO subsystem 20 via piping, particularly via fluid-sealed piping. Figures 1 to 8 In the diagram, such pipes are indicated by arrows. The feed solution reservoir 40 can be considered as part of the RO subsystem 10 and / or the PRO subsystem 20, or it can be considered as separate from these subsystems, which is irrelevant.

[0069] The system of the present invention also includes an induction motor 30, particularly an asynchronous motor, having a stator and a rotor. The system also includes an axial piston pump 31, which functions as a hydraulic pump and is configured to supply a feed solution from a feed solution reservoir 40 to the RO feed inlet 14. The system further includes an axial piston motor 32, which functions as a hydraulic motor and is configured to receive a drive solution from a drive outlet 25 and supply it to the feed solution reservoir 40. The rotor of the induction motor 30 is mechanically connected to the input shaft of the axial piston pump 31 and the output shaft of the axial piston motor 32. Specifically, the rotor of the induction motor 30 is connected to a motor shaft of the induction motor 30, which is connected to both the input and output shafts, and wherein the motor shaft may be a single, continuous motor shaft or may be formed by a pair of two (double) motor shafts.

[0070] Feed solution reservoir 40 is fluidly connected to the feed inlet 14 of high-pressure RO chamber 11 via axial piston pump 31, which pumps liquid from feed solution reservoir 40 to high-pressure RO chamber 11 at a certain volumetric flow rate and pressure. The solvent of the feed solution enters low-pressure RO chamber 12 through RO membrane 13, leaving an upwardly concentrated feed solution (brine) in high-pressure RO chamber 11. The solvent, as permeate, is discharged from low-pressure RO chamber 12 at low pressure via permeate outlet 16. The permeate can be fresh water. Brine is discharged from high-pressure RO chamber 11 at high pressure via brine outlet 15.

[0071] Brine discharged from the high-pressure RO chamber 11 is supplied to the drive solution inlet 24 of the high-pressure PRO chamber 21 via a pipe connecting the brine outlet 15 and the PRO drive solution inlet 24. Simultaneously, feed solution from the feed solution reservoir 40 is supplied to the PRO feed solution inlet 26 via a suitable pipe. The solvent of the feed solution is driven by osmotic pressure through the PRO membrane 23 into the high-pressure PRO chamber 21, diluting the drive solution received via the drive solution inlet 24.

[0072] The diluted drive solution is discharged from the high-pressure PRO chamber 21 via drive solution outlet 25, with a volumetric flow rate exceeding that at the PRO drive solution inlet 24. The extracted diluted drive solution is supplied to the motor inlet of the axial piston motor 32, where its hydraulic energy is converted into rotation and then into electricity via the induction motor 30. The depressurized diluted drive solution exiting the axial piston motor 32 via the motor outlet is guided back to the drive solution reservoir 40. The feed solution retained in the low-pressure PRO chamber 22 is discharged from it and supplied to the drive solution reservoir via the PRO feed outlet 27.

[0073] Figure 2 The RO and PRO systems according to the second embodiment are schematically illustrated. The same reference numerals as in the first embodiment denote the same components, and for the sake of brevity, repeated descriptions of these components are omitted.

[0074] Figure 2 The system and Figure 1The difference between the systems is that energy recovery devices 63 and 64 are located in the RO subsystem 10 and the PRO subsystem 20. Specifically, in the RO subsystem 10, the RO energy recovery device ERD 63 is interconnected between the brine outlet 15 and the RO feed inlet 14. More specifically, the RO ERD 63 receives the feed solution from the feed solution reservoir 40 at low pressure and receives the brine from the high-pressure RO chamber 11 at high pressure. In the RO ERD 63, hydraulic energy is transferred from the high-pressure brine to the low-pressure feed solution, and thus, the feed solution is supplied to the RO feed inlet 14 by the RO ERD 63 at an increased pressure, and the brine is supplied to the feed reservoir 40 by the RO ERD 63 at a decreased pressure.

[0075] In the PRO subsystem 20, the PRO energy recovery unit ERD 64 is interconnected between the drive outlet 25 and drive inlet 24 of the high-pressure PRO chamber 21. More specifically, the piping connected to the drive outlet 25 is separate, providing one flow path to the motor inlet of the axial piston motor 32 and another flow path to the PRO ERD 64. A portion of the diluted drive solution discharged from the high-pressure PRO chamber 21 is supplied to the PRO ERD 64 via the other flow path, while another portion of the solution is supplied to the axial piston motor 32. Thus, the PRO ERD 64 receives the diluted PRO drive solution at high pressure. The PRO ERD 64 also receives brine discharged from the brine outlet 15 of the high-pressure RO chamber 11 at low pressure. In the PRO ERD 64, hydraulic energy is transferred from the high-pressure diluted drive solution to the low-pressure brine; therefore, the brine is supplied to the drive inlet 24 at increased pressure as the PRO drive solution, and the diluted drive solution is supplied to the feed solution reservoir 40 at decreased pressure.

[0076] Figure 3 The RO and PRO systems according to a third embodiment are schematically illustrated. Identical components are indicated by the same reference numerals as in the previous embodiments, and repeated descriptions of these components are omitted for brevity.

[0077] Figure 3 The system and Figure 2 The difference in the system is that feed pumps 61 and 62 are located in the RO subsystem 10 and the PRO subsystem 20. Specifically, the RO feed pump 61 is interconnected between the feed solution reservoir 40 and the axial piston pump 31. The RO feed pump 61 reduces the load on the axial piston pump 31. Furthermore, the PRO feed pump 62 is interconnected between the feed reservoir 40 and the PRO ERD 64, and further increases the pressure of the PRO drive solution upstream of the drive inlet 24.

[0078] Figure 4The RO and PRO systems according to the fourth embodiment are schematically illustrated. Identical components are indicated by the same reference numerals as in the previous embodiments, and for the sake of brevity, repeated descriptions of these components are omitted.

[0079] Figure 4 The system and Figure 3 The difference in this system is that the energy storage device 50 is connected to the induction motor 30 and the power grid 51. The electrical connections are as follows: Figures 4 to 6 As shown by the dashed lines in the diagram. The energy storage device 50 is preferably a battery, such as a lithium-ion battery, configured to receive electrical energy from and supply electrical energy to the induction motor 30. The energy storage device 50 is also preferably configured to receive electrical energy from and supply electrical energy to the power grid 51. When the energy storage device 50 supplies power to the induction motor 30, the induction motor 30 can operate with a positive slip rate, and when the energy storage device 50 receives power from the induction motor 30, the induction motor 30 can operate with a negative slip rate. However, the conversion between power supply and consumption can also be independent of the slip rate of the induction motor 30, for example, if a doubly-fed motor is used as the induction motor 30 and an inverter is used for control. The energy storage device 50 may include one or more frequency converters, for example, for connecting to the power grid 51 and / or the induction motor 50. Similarly, as... Figure 4 As shown, the energy storage device 50 provides power to the RO feed pump 61 and the PRO feed pump 62.

[0080] Figure 5 The schematic illustration shows the RO and PRO systems according to the fifth embodiment. Identical components are indicated by the same reference numerals as in the previous embodiments, and for the sake of brevity, repeated descriptions of these components are omitted.

[0081] Figure 5 The system and the previous Figures 1 to 4 The difference in this system lies in that it includes a drive solution reservoir 41 located adjacent to the seawater reservoir 42, serving as a feed solution reservoir. The seawater reservoir 42 supplies the feed solution to the RO subsystem 10 via a hydraulic motor 31, specifically to the RO feed inlet 14. However, the seawater reservoir 42 does not receive brine solutions, thus reducing the system's ecological impact. Furthermore, Figure 5 The system is designed to be "off-grid" while simultaneously producing clean (fresh) water and (electric) energy.

[0082] Drive solution reservoir 41 (via RO ERD 63) receives brine solution from brine outlet 15, receives diluted drive solution from drive outlet 25 via axial piston motor 32 and via PRO ERD 64, receives RO feed solution from seawater reservoir 42 and from PRO feed outlet 27, and (via PRO ERD 64) supplies drive solution to drive inlet 24. Drive solution reservoir 41 further supplies upward concentrated brine / drive solution to another process stage, such as an evaporator (not shown).

[0083] In a specific example, the seawater storage tank 42 supplies 186 m³ of seawater via the RO feed pump 61 at a pressure of 2 bar. 3 The feed solution is supplied at a rate of / h. A portion of the volumetric feed solution flow rate, specifically 53 m³ / h. 3 / h, is supplied to RO ERD 63, while the remaining portion of the volumetric feed solution flow rate, i.e., 133 m, is... 3 The feed solution is supplied at a pressure of 66 bar to the axial piston pump 31 and from there to the RO feed inlet 14. The solvent in the feed solution is supplied at a pressure of 2 bar and 133 m... 3 A volumetric flow rate of [value] / h passes through RO membrane 13 and exits low-pressure RO chamber 12 via permeate outlet 16. The upwardly concentrated feed solution, as brine, exits through brine outlet 15 at a flow rate of 53m³ / h. 3 A volumetric flow rate of / h and a pressure of 62 bar are discharged from the high-pressure RO chamber 11. In RO ERD 63, hydraulic energy is transferred from the brine to a portion of the feed solution received from the seawater reservoir 42, such that this portion of the feed solution is also at a pressure of 66 bar and 53 m 3 A volumetric flow rate of / h is supplied from RO ERD 63 to feed inlet 14.

[0084] Salt water at 53 m 3 A volumetric flow rate of / h and a pressure of 2 bar are supplied from RO ERD 63 to drive solution reservoir 41. From drive solution reservoir 41, the solution is fed from PRO feed pump 62 at a rate of 100 m³ / h. 3 A volumetric flow rate of / h and a pressure of 2 bar supply brine as the driving solution to PRO ERD 64. PRO ERD 64 is fed into the drive inlet 24 of the high-pressure PRO chamber 21, while the feed inlet 26 of the low-pressure PRO chamber 22 is supplied with a portion of the volumetric flow rate driven by the RO feed pump, specifically 100 m³ at a pressure of 2 bar. 3 The feed solution is supplied at a rate of / h. In the PRO unit, the solvent of the feed solution passes through PRO membrane 23 and is supplied at an increased pressure of 200 bar and 150 m. 3A volumetric flow rate of / h is used to dilute the drive solution exiting the high-pressure PRO chamber via drive outlet 25. A portion of the volumetric flow rate of the diluted drive solution, specifically 50 m³ / h, is used. 3 At a pressure of 200 bar, hydraulic energy is supplied to the motor inlet of the axial piston motor at a rate of / h. After the hydraulic energy is converted into electrical energy via the axial piston motor 32 and the induction motor 30, 50 m 3 A portion of the volumetric flow rate of the drive solution, at a pressure of 2 bar, is supplied back to the drive solution reservoir 41. Another portion of the volumetric flow rate of the diluted drive solution, specifically 100 m³ / h... 3 The fluid is supplied to the PRO ERD 64 at a pressure of 200 bar per hour. There, hydraulic energy is transferred from a portion of the diluted drive solution to the drive solution supplied by the PRO feed pump 62, such that the drive solution is supplied to the drive inlet 24 at an increased pressure, while the depressurized diluted drive solution is supplied to the drive solution reservoir at a pressure of 2 bar. In the example above, all membranes are considered ideal entities with no pressure loss, and the ERD is idealized to have no pressure drop or other internal losses. The feed pump and booster pump are modeled with an energy efficiency of 80%, and the axial piston pump 31 and motor 32 are modeled with an energy efficiency of 93%.

[0085] exist Figure 5 In one embodiment, the drive solution reservoir 41 further supplies the upwardly concentrated brine / drive solution to another process stage, such as an evaporator (not shown), and may further receive additional feed solution from the seawater reservoir 42 for upward concentration. Similar implementations include... Figure 6 As shown, the RO and PRO systems according to the sixth embodiment are schematically illustrated, wherein the same components are indicated by the same reference numerals as in the previous embodiments, and repeated descriptions of these components are omitted for brevity.

[0086] Figure 6 and Figure 5 The difference is that the feed solution from the PRO feed outlet 27 is supplied to the feed solution reservoir 40, instead of driving the solution reservoir 41. Furthermore, in Figure 6In this configuration, the drive solution reservoir 41 does not receive additional feed solution from the feed solution reservoir 40 for upward concentration. Furthermore, in this configuration, the ecological impact on the system is minimized, and the net inflow into the drive solution reservoir 41 is determined solely by the volumetric flow rate at the brine outlet 15 and the volumetric flow rate through the PRO membrane 23, where the latter corresponds to the difference between the volumetric flow rate at the PRO drive outlet 25 and the volumetric flow rate at the PRO drive inlet 24. Therefore, if the solvent evaporates from the drive solution reservoir 41 (indicated by the bottom arrow from the drive solution reservoir 41 on the left) at an evaporation rate exceeding the difference between the volumetric flow rate at the PRO drive outlet 25 and the volumetric flow rate at the PRO drive inlet 24 (i.e., exceeding the volumetric flow rate through the PRO membrane 23), the concentration in the drive solution reservoir 41 is always at least the brine concentration. Therefore, in Figure 6 In this system, the production / harvesting of minerals (such as salts) can be controlled by adjusting only the evaporation rate and / or the flow rate through the PRO membrane 23.

[0087] Figure 7 The RO and PRO systems according to the seventh embodiment are schematically illustrated. Identical components are indicated by the same reference numerals as in the previous embodiments, and for the sake of brevity, repeated descriptions of these components are omitted.

[0088] Figure 7 The system is different from the previous one. Figures 1 to 6 The difference in this system is that the feed solution for the PRO subsystem 20 is not provided from the feed solution reservoir 40, but rather the permeate from the RO process is provided as the feed solution to the PRO process. Therefore, Figure 7 The system includes a pipe between the permeate outlet 16 and the PRO feed inlet 26. Figure 7 Other components of the previous system, such as the ERD, feed pump, energy storage device, or power grid, are omitted from this embodiment. However, these components can also be included in a similar manner to those previously described.

[0089] Figure 8 The RO and PRO systems according to the eighth embodiment are illustrated schematically. Identical components are indicated by the same reference numerals as in the previous embodiments, and for the sake of brevity, repeated descriptions of these components are omitted.

[0090] Figure 8 The system is different from the previous one. Figures 1 to 7The difference in this system is that the brine from the RO process is not used as the driving solution for the PRO process. Instead, when the permeate from the RO process is used as the feed solution for the PRO process, the driving solution for the PRO process is obtained by utilizing a mineral reservoir 43 (e.g., underground salt resources), specifically by pumping a solvent (e.g., water) through such a reservoir 43, in order to achieve a high solute concentration. This setup is advantageously used when the mineral content of the feed solution is not of interest for harvesting and / or when an existing mineral reservoir 43 provides the opportunity to obtain a high concentration gradient for driving the PRO process. Figure 8 The system also includes RO ERD 63 and PRO ERD 64, the RO ERD being interconnected between the brine outlet 15 and the feed inlet 14 of the high-pressure RO chamber 11, and the PRO ERD being interconnected between the drive outlet 25 and the drive inlet 24 of the PRO high-pressure chamber 21, as described with respect to the preceding embodiments. Figure 8 Other components of the previous system, such as the feed pump, energy storage device, or power grid, are omitted from this embodiment. However, these components can also be included in a similar manner as described above.

[0091] Figure 9 The RO and PRO systems according to the ninth embodiment are schematically illustrated. Identical components are indicated by the same reference numerals as in the previous embodiments, and for the sake of brevity, repeated descriptions of these components are omitted.

[0092] Figure 9 The system is different from the previous one. Figures 1 to 8 The difference in this system is that the energy recovery unit (specifically the isobaric pressure exchanger 65) is interconnected between the PRO subsystem 20 and the RO subsystem 10. (Compared to the reference...) Figure 5 Compared to the specific embodiment explained, in the isobaric pressure exchanger 65, only a portion of the hydraulic energy of the PRO subsystem 20 is transmitted to the RO subsystem 10 via an indirect mechanical connection of the induction motor 30, while another portion of the hydraulic energy is transmitted from the PRO to the RO side via the isobaric pressure exchanger 65.

[0093] In particular, Figure 9 In this embodiment, the delta pressure of the hydraulic motor 32 is adjusted so that the 50m at the motor inlet... 3 The hydraulic energy at a flow rate of 200 bar / h is converted into mechanical energy, enabling the 50 m at the motor outlet. 3A flow rate of 65 bar / h exits the hydraulic motor and is input to the isobaric pressure exchanger 65. There, the remaining hydraulic energy of the flow rate is transferred to a low-pressure inflow from the feed solution reservoir 40, entering the isobaric pressure exchanger 65 at a pressure of 2 bar and exiting at approximately 65 bar. Thus, in the RO subsystem, the hydraulic pump 31 only pressurizes a portion of the inflow to the high-pressure RO chamber 11 to up to 65 bar, while the outflow from the isobaric pressure exchanger 65 provides the remaining inflow. By regulating the delta pressure of the hydraulic motor in this way, the transmission efficiency of the isobaric pressure exchanger 65 is advantageously improved. Further advantageously, the delta pressure of the hydraulic motor 32 follows the pressure at the high-pressure inlet of the isobaric pressure exchanger 65, and the pressure at the high-pressure inlet of the isobaric pressure exchanger 65 again follows the pressure at the RO feed inlet 14, thus providing a self-regulating system.

[0094] Figure 10 A block diagram schematically illustrates a method for operating a reverse osmosis (RO) and pressure delayed osmosis (PRO) system according to one embodiment, as previously described. Figures 1 to 9 The method, as described, includes step S100 of supplying a feed solution to the RO feed inlet 14 via a hydraulic pump 31 at a first pressure and a first volumetric flow rate. The method further includes step S200 of receiving a drive solution from the drive outlet 25 via a hydraulic motor 32 at a second pressure and a second volumetric flow rate. The method also includes step S300 of transferring energy from the hydraulic pump 31, configured to supply the feed solution to the RO feed inlet 14, to the hydraulic motor 32, configured to receive the drive solution from the drive outlet 25. In a preferred embodiment of the system including an induction motor 30, step S300 may further include operating the induction motor 30 with a slip rate based on the ratio of the first pressure and the first volumetric flow rate to the second pressure and the second volumetric flow rate. Steps S100, S200, and S300 should not be construed as referring to a series of steps, but rather as steps performed simultaneously during stable operation of the system.

[0095] Figure 11 The illustration schematically depicts an operation as previously described in another embodiment. Figures 1 to 9 A block diagram of the methods for the described reverse osmosis (RO) and pressure delayed osmosis (PRO) systems. Figure 11 In the previous section, steps S100, S200, and S300 were executed, describing the stable operation of the system. The remaining steps of the method are executed according to the operating mode. In the first operating mode, Figures 1 to 8 The induction motor 30 operates with positive slip in step S401a, and therefore consumes energy from the energy storage device 50 and / or the power grid 51 in step S402a (e.g., Figures 4 to 6The first operating mode also involves: the displacement ratio of the hydraulic pump 31 and the hydraulic motor 32 being adjusted to be greater than 1 in step S403a and / or the delta pressure of the hydraulic motor being less than the delta pressure of the hydraulic pump. In contrast, in the second operating mode, the induction motor 30 operates with a negative slip rate in step S401b and further supplies energy to the energy storage device 50 and / or the power grid 51 (e.g., ...) in step S402b. Figures 4 to 6 The system supplies electrical energy. According to the illustrated embodiment, the second operating mode also involves: the displacement ratio of the hydraulic pump 31 and the hydraulic motor 32 being adjusted to be less than 1 and / or the delta pressure of the hydraulic motor being greater than the delta pressure of the hydraulic pump. Similarly, these steps S401, S402, and S403 should not be construed as referring to a series of steps, but rather that these steps can be performed simultaneously during stable operation of the system.

[0096] Figure 11 The method also includes steps that are independent of the system's operating mode, which is one of the first and second operating modes. While the steps described above serve to produce desalinated and / or purified water, these steps serve the additional purpose of harvesting minerals. To achieve this purpose, in step S501, brine is collected from brine outlet 15 and stored in drive solution reservoir 41 (e.g., Figure 5 and Figure 6 In step S502, the driving solution is supplied from the driving solution reservoir 41 to the driving inlet 24, while the diluted driving solution from the driving outlet 25 is received in the driving solution reservoir 41. In step S503, the solvent from the driving solution reservoir 41 is evaporated at a solvent evaporation rate at least as high as the difference between the volumetric flow rate at the PRO driving outlet 25 and the volumetric flow rate at the PRO driving inlet 24, i.e., exceeding the net flow rate of the solvent through the PRO membrane 23. Similarly, these steps S501, S502, and S503 should not be construed as necessarily referring to a series of steps, but rather that these steps can be performed simultaneously during stable operation of the system.

[0097] Figure Labels

[0098] 10 Reverse Osmosis (RO) Subsystem

[0099] 11 High-pressure RO chamber

[0100] 12 Low-pressure RO chamber

[0101] 13 RO membrane

[0102] 14 RO feed inlet

[0103] 15. Brine Export

[0104] 16 Permeate outlet

[0105] 20 Pressure Delayed Permeation PRO Subsystem

[0106] 21 High-voltage PRO chamber

[0107] 22 Low-pressure PRO chamber

[0108] 23 PRO film

[0109] 24 Driver Entry Point

[0110] 25 Drive Outlet

[0111] 26 PRO feed inlet

[0112] 27 PRO Inlet / Outlet

[0113] 30 Induction Motor

[0114] 31 Axial piston (hydraulic) pump

[0115] 32 Axial Piston (Hydraulic) Motor

[0116] 40 Feed solution storage tank

[0117] 41 Drive solution reservoir

[0118] 42 Seawater storage tank

[0119] 43 Mineral storage container

[0120] 50 Energy storage devices

[0121] 51 Power Grid

[0122] 61 RO feed pump

[0123] 62 PRO feed pump

[0124] 63 RO Energy Recovery Unit

[0125] 64 PRO Energy Recovery Device

[0126] 65 Isobaric pressure exchanger.

Claims

1. A system for reverse osmosis (RO) and pressure delayed osmosis (PRO), comprising: The RO subsystem (10) has a high-pressure RO chamber (11) and a low-pressure RO chamber (12) separated by an RO membrane (13), wherein the high-pressure RO chamber (11) has an RO feed inlet (14) and a brine outlet (15), and the low-pressure RO chamber (12) has a permeate outlet (16). The PRO subsystem (20) has a high-pressure PRO chamber (21) and a low-pressure PRO chamber (22) separated by a PRO membrane (23). The high-pressure PRO chamber (21) has a drive inlet (24) and a drive outlet (25), and the low-pressure PRO chamber (22) has a PRO feed inlet (26) and a PRO feed outlet (27). The hydraulic pump (31) configured to supply feed solution to the RO feed inlet (14) is mechanically connected to the hydraulic motor (32) configured to receive drive solution from the drive outlet (25) to allow energy to be transferred directly from the PRO subsystem (20) to the RO subsystem (10) without conversion loss.

2. The system according to claim 1 further includes an induction motor (30) having a stator and a rotor, wherein, The rotor is mechanically connected to the input shaft of the hydraulic pump (31) and the output shaft of the hydraulic motor (32).

3. The system according to claim 1 or 2 further includes a feed solution reservoir (40) connected via the hydraulic pump (31) to the RO feed inlet (14) and / or via the hydraulic motor (32) to the drive outlet (25), and connected to the PRO feed inlet (26), and / or The system also includes a drive solution reservoir (41) connected to the brine outlet (15), the drive inlet (24), and the drive outlet (25).

4. The system according to claim 1 or 2, wherein, The hydraulic pump (31) is an axial piston pump, and the hydraulic motor (32) is an axial piston motor.

5. The system according to claim 1 or 2, wherein, At least one of the hydraulic pump (31) and the hydraulic motor (32) has an adjustable displacement.

6. The system according to claim 2, wherein, The induction motor (30) is connected to the energy storage device (50) and / or the power grid (51).

7. The system according to claim 6, wherein, The displacement of the hydraulic pump (31) is lower than that of the hydraulic motor (32), and the induction motor (30) is configured to operate with a negative slip rate and supply power to the energy storage device (50) and / or to the power grid (51).

8. The system according to claim 6 or 7 further includes at least one feed pump (61, 62) in the RO subsystem (10) and / or the PRO subsystem (20), the at least one feed pump (61, 62) being connected to the energy storage device (50) and / or the power grid (51).

9. The system according to claim 1 or 2 further includes an RO energy recovery device (63) interconnected between the brine outlet (15) and the RO feed inlet (14) and / or a PRO energy recovery device (64) interconnected between the drive outlet (25) and the drive inlet (24).

10. A method for operating a system for reverse osmosis (RO) and pressure delayed osmosis (PRO) according to claim 1, the method comprising the steps of: The feed solution is supplied (S100) to the RO feed inlet (14) via the hydraulic pump (31) at a first pressure and a first volumetric flow rate; The hydraulic motor (32) receives (S200) the driving solution from the drive outlet (25) at a second pressure and a second volume flow rate; and Energy (S300) is transferred via a mechanical connection from the hydraulic pump (31) configured to supply feed solution to the RO feed inlet (14) to the hydraulic motor (32) configured to receive drive solution from the drive outlet (25).

11. The method according to claim 10, wherein, The system also includes an induction motor (30) having a stator and a rotor, wherein the rotor is mechanically connected to the input shaft of the hydraulic pump (31) and the output shaft of the hydraulic motor (32), and the method further includes the following steps: The induction motor (30) is operated with a slip ratio based on the ratio of the first pressure and the first volumetric flow rate to the second pressure and the second volumetric flow rate.

12. The method according to claim 11, wherein, The induction motor (30) is connected to the energy storage device (50) and / or the power grid (51) of the system, and the method further includes the following steps: In the first operating mode, the induction motor (30) operates with positive slip (S401a) and consumes (S402a) electrical energy from the energy storage device (50) and / or the power grid (51); and / or In the second operating mode, the induction motor (30) operates with a negative slip rate (S401b) and supplies (S402b) electrical energy to the energy storage device (50) and / or the power grid (51).

13. The method according to claim 12, wherein, The system further includes at least one feed pump (61, 62) in the RO subsystem (10) and / or the PRO subsystem (20), and the method further includes the following steps: The at least one feed pump (61, 62) is operated with electrical energy from the energy storage device (50).

14. The method according to any one of claims 10 to 13, wherein, The system further includes: a seawater reservoir (42) connected to the RO feed inlet (14) and the PRO feed inlet (26) via the hydraulic pump (31); and a drive solution reservoir (41) connected to the drive outlet (25), the drive inlet (24), and the brine outlet (15) via the hydraulic motor (32); and the method further includes the following steps: (S501) Brine is collected from the brine outlet (15) in the drive solution reservoir (41); (S502) Drive solution is supplied from the drive solution reservoir (41) to the drive inlet (24), and a diluted drive solution from the drive outlet (25) is received in the drive solution reservoir (41); and The solvent is evaporated (S503) from the drive solution reservoir (41), wherein the evaporation rate of the solvent exceeds the difference between the volumetric flow rate at the drive outlet (25) and the volumetric flow rate at the drive inlet (24).

15. Use of a system for reverse osmosis (RO) and pressure delayed osmosis (PRO) according to claim 1, said system comprising: A seawater reservoir (42) connected to the RO feed inlet (14) and the PRO feed inlet (26) via the hydraulic pump (31), and a drive solution reservoir (41) connected to the brine outlet (15) and the drive outlet (25) via the hydraulic motor (32) are used to concentrate salt and / or other minerals in the drive solution reservoir (41), to extract salt and / or other minerals from the drive solution reservoir (41), and to provide fresh water from the permeate outlet (16).

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