Reverse osmosis desalting device for sequential circulation engineering

Abstract

The present invention relates to a sequential cycle engineering reverse osmosis desalination apparatus, and more particularly, to a sequential cycle engineering reverse osmosis desalination apparatus which substantially ensures high recovery by using a closed-loop reverse osmosis technique and which sequentially applies a reverse osmosis technique to reduce fouling, high-efficiency water treatment can be performed without a separate energy recovery device.

Description

Technical Field

[0001] The present invention relates to a sequential cycle reverse osmosis desalination device, and more specifically, to a sequential cycle reverse osmosis desalination device, which adopts closed-loop reverse osmosis technology to basically ensure a high recovery rate, and sequentially applies reverse reverse osmosis technology to reduce fouling, while being able to perform high-efficiency water treatment without a separate energy recovery device. Background Art

[0002] Water shortage means that it is difficult to obtain fresh water due to resource depletion, and due to the advanced industrial development and abnormal climate phenomena, water shortage is becoming increasingly serious worldwide.

[0003] However, as water is an indispensable element in human life and various industrial fields, the demand for it continues to increase. As one of the effective methods to meet this demand, a so-called seawater desalination method of desalinating a large amount of seawater has been proposed.

[0004] Desalination refers to a series of water treatment processes that remove dissolved substances including salt from seawater that is difficult to use directly as domestic or industrial water to obtain high-purity drinking water, domestic water, industrial water, etc.

[0005] Currently, seawater desalination equipment uses a multiple-stage flash distillation process (MSF) or a reverse osmosis process. The reverse osmosis process is a process for preparing fresh water by applying a pressure higher than the osmotic pressure to raw water or salt water to allow pure water without solutes such as ions or organic molecules to move through a semipermeable membrane.

[0006] On the other hand, unlike the general reverse osmosis process, in order to achieve the target recovery rate, there is also a closed-circuit reverse osmosis (CCRO) seawater desalination method, which operates by mixing the concentrated water discharged from the reverse osmosis equipment with raw water or brine and injecting it into the reverse osmosis equipment again, and discharging the concentrated water after reaching the target concentration.

[0007] In this regard, Korean Patent No. 10-1052662 discloses an apparatus for continuous batch sequential desalination treatment in a closed circuit of a brine solution by reverse osmosis, which is composed of a plurality of closed circuit desalination apparatuses (closed circuit reverse osmosis, CCRO) connected in parallel.

[0008] However, a closed circuit desalination unit (CCRO) using conventional reverse osmosis has a problem in that the time during which the pressure of concentrated water discharged through the reverse osmosis device increases shortens as the process proceeds, thereby shortening the cleaning or replacement cycle of the reverse osmosis device. Summary of the invention

[0009] Technical Problems to be Solved by the Invention

[0010] The present invention is proposed to solve the above-mentioned problems, and its purpose is to provide a sequential cycle reverse osmosis (CIRCLE-SEQUENCE REVERSE OSMOSIS, Circle-SEQ RO) desalination device, which adopts closed-loop reverse osmosis technology to basically ensure high recovery rate, and sequentially applies reverse reverse osmosis technology to reduce dirt. On the other hand, it can also perform high-efficiency water treatment without a separate energy recovery device.

[0011] Other objects of the present invention will become more apparent from the following embodiments.

[0012] Technical Solution

[0013] In order to solve the above-mentioned problem, the present invention proposes, as an embodiment, a sequential cycle engineering reverse osmosis desalination device, which connects each of a plurality of forward reverse osmosis modules (forward RO modules) and at least one reverse reverse osmosis module (backward RO module) in parallel, and the concentrated water discharged from the forward reverse osmosis module flows into the reverse reverse osmosis module, and the concentrated water discharged from the reverse reverse osmosis module flows into each of the forward reverse osmosis modules.

[0014] In a reverse osmosis desalination device according to an embodiment of the present invention, the device comprises: a feed pump for supplying raw water; a first pump (1 st pump), connected to the output end of the feed pump; a second pump (2 nd pump), connected to the output end of the forward reverse osmosis module; a third pump (3 rd pump), connected to the output end of the first pump; and a controller, in the first operation step (1 st step), controlling the feed pump and the first pump to allow the raw water to enter the plurality of forward and reverse osmosis modules, and in the second operation step (2 nd step), controlling the second pump so that the concentrated water discharged from the forward reverse osmosis module enters the reverse reverse osmosis module. rdstep), the concentrated water discharged from the reverse osmosis module by the third pump merges with the raw water and then enters the forward reverse osmosis module.

[0015] High pressure pumps may be used as the first pump and the second pump, and a jet pump that accelerates the raw water of the third operation step by using the flow of concentrated water may be used as the third pump.

[0016] In addition, a three-way control valve is respectively configured at the input end and the output end of the plurality of forward reverse osmosis modules and the reverse reverse osmosis modules, and the controller can be configured to: in the fourth operation step (4 th step), controlling the three-way control valve so that when a preset first condition is met, the reverse osmosis module is converted into a forward reverse osmosis module, and raw water is continuously supplied to the input ends of all reverse osmosis modules and concentrated water at the output ends of all reverse osmosis modules is discharged to the outside until a preset second condition is met.

[0017] In addition, the following can be used as the first condition: the measurement value of at least one of the concentration sensor, flow sensor, and pressure sensor arranged on the movement path of the concentrated water reaches a preset reference value, or a preset time has passed after the third operation step.

[0018] In addition, the following may be set as the second condition: the concentration of the concentrated water reaches a preset initial concentration.

[0019] The controller may be configured to: after completing one batch process from the first operation step to the fourth operation step, perform a fifth operation step (5 th step), in the fifth operation step, controlling the three-way control valve so as to convert at least one of the plurality of forward reverse osmosis modules into a reverse reverse osmosis module and converting the existing reverse reverse osmosis module into a forward reverse osmosis module.

[0020] In addition, the controller may perform the fifth operation step after performing a plurality of the batch processes.

[0021] Beneficial Effects

[0022] According to an embodiment of the present invention, before a closed circuit reverse osmosis (CCRO) process of mixing concentrated water with raw water, concentrated water discharged from a forward RO module flows into a backward RO module to circulate in a concentrated state one more time, thereby significantly reducing energy consumption and chemical usage compared to a conventional multi-stage reverse osmosis process.

[0023] In addition, according to an embodiment of the present invention, by periodically applying the injection direction of raw water in the opposite direction, the generation rate of biofouling and scale in the reverse osmosis module can be slowed down, and a portion of the scale can be removed, thereby shortening the reduction range of the pressure increase time of the concentrated water, and thus the Clean in place (CIP) cycle can be extended.

[0024] The effects of the present invention are not limited to the above-mentioned effects, and other effects not mentioned can be clearly understood by those skilled in the art from the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of a sequential cycle engineering reverse osmosis desalination device according to an embodiment of the present invention.

[0026] Figure 2 is a block diagram showing a configuration of a sequential cycle engineering reverse osmosis desalination apparatus according to an embodiment of the present invention.

[0027] Figure 3 is a flow chart showing the operation steps of a sequential cycle engineering reverse osmosis desalination device according to an embodiment of the present invention.

[0028] Figure 4 Schematic diagram showing a fourth operation step of a sequential cycle engineering reverse osmosis desalination device according to an embodiment of the present invention.

[0029] Figure 5 2 is a schematic diagram showing a fifth operation step of a sequential cycle engineering reverse osmosis desalination device according to an embodiment of the present invention.

[0030] Figure 6 1 is a graph showing a time reduction range of a pressure increase each time a batch process from a first operation step to a fourth operation step of a sequential cycle process reverse osmosis desalination device according to an embodiment of the present invention is repeated. DETAILED DESCRIPTION

[0031] The present invention can be varied and has a variety of embodiments. Specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, it should be understood that the present invention is not limited to specific embodiments, but includes all changes, equivalents or substitutes contained in the concept and technical scope of the present invention.

[0032] When describing the present invention, if it is determined that a detailed description of a related known technology obscures the gist of the present invention, the detailed description will be omitted.

[0033] The terms used in this application are only used to illustrate specific embodiments and are not intended to limit the present invention. Unless the context clearly stipulates otherwise, singular expressions include plural expressions. The terms "including" or "having" in this application are used to specify the existence of features, numbers, steps, actions, constituent elements, parts or combinations thereof recorded in the specification, and do not preclude the existence or additional possibility of one or more other features, numbers, steps, actions, constituent elements, parts or combinations thereof.

[0034] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meanings as those generally understood by those of ordinary skill in the art. Terms defined in commonly used dictionaries should be interpreted as having meanings consistent with the context of the relevant technology and should not be interpreted as ideal or overly formal meanings unless explicitly defined in this application.

[0035] The term module described in this specification may refer to a unit for processing a specific function or action, and may refer to hardware or software or a combination of hardware and software.

[0036] Although the terms "first", "second" and the like may be used to describe various components, the components are not limited to the terms. The terms are only used to distinguish one component from other components.

[0037] Hereinafter, embodiments according to the present invention will be described in detail with reference to the accompanying drawings. In the description with reference to the accompanying drawings, the same or corresponding components are given the same reference numerals regardless of the reference numerals, and repeated description thereof will be omitted.

[0038] Hereinafter, a sequential cycle reverse osmosis desalination device 1 according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[0039] Hereinafter, when describing the sequential cycle reverse osmosis desalination device 1 according to an embodiment of the present invention, the meaning of "connection" should be interpreted as including all modes of connection directly to the reverse osmosis module or via pumps, valves, controllers, etc.

[0040] Figure 1 is a schematic diagram of a sequential cycle engineering reverse osmosis desalination device according to an embodiment of the present invention, Figure 2 is a block diagram showing the configuration of a sequential cycle engineering reverse osmosis desalination device according to an embodiment of the present invention, Figure 3 is a flow chart showing the operation steps of a sequential cycle engineering reverse osmosis desalination device according to an embodiment of the present invention.

[0041] like Figure 1 and Figure 2 As shown, a sequential cycle reverse osmosis desalination device 1 according to an embodiment includes a plurality of reverse osmosis modules 10, 20, 30 (RO modules), a feed pump FP (feed pump), a first pump P1 (1 st pump), the second pump P2(2 nd pump)、third pump P3(3 rd pump), multiple three-way control valves (3-way valves), concentrate discharge valve DV (Brain valve) and controller C (controller).

[0042] The reverse osmosis modules 10 , 20 , 30 include a plurality of forward reverse osmosis modules 10 , 20 (forward RO modules) and at least one reverse reverse osmosis module 30 (backward RO module).

[0043] In this specification, an embodiment consisting of two forward reverse osmosis modules and one reverse reverse osmosis module is shown, but it is not limited thereto. Depending on the amount of salt water to be treated, the reverse osmosis module may consist of two or more than four. As a specific example, it may consist of one forward reverse osmosis module and one reverse reverse osmosis module, or it may consist of three forward reverse osmosis modules and one reverse reverse osmosis module, or it may consist of three forward reverse osmosis modules and two reverse reverse osmosis modules.

[0044] Hereinafter, for convenience of description, the plurality of reverse osmosis modules 10 , 20 , and 30 (Ro modules) are referred to as a first reverse osmosis module 10 , a second reverse osmosis module 20 , and a third reverse osmosis module 30 , respectively.

[0045] The first reverse osmosis module 10, the second reverse osmosis module 20 and the third reverse osmosis module 30 are connected in parallel with each other, the concentrated water B (Brine) discharged from the first reverse osmosis module 10 and the second reverse osmosis module 20 flows into the third reverse osmosis module 30, and the concentrated water B discharged from the third reverse osmosis module 30 flows into the first reverse osmosis module 10 and the second reverse osmosis module 20 again, respectively, thereby forming a circulation circuit.

[0046] The feed pump FP is provided to supply raw water R to the reverse osmosis module, and can deliver the raw water R at a pressure of about 3 bar(g), for example.

[0047] The first pump P1 is connected to the output terminal of the feed pump FP, and starts driving when the flow rate of the raw water R supplied from the feed pump FP exceeds a preset reference.

[0048] The second pump P2 is connected to output ends of the first and second reverse osmosis modules 10 and 20 , and moves the concentrated water B discharged from the first and second reverse osmosis modules 10 and 20 to an input end of the third reverse osmosis module 30 .

[0049] A high pressure pump may be used as the first pump P1 and the second pump P2.

[0050] The concentrated water B2 discharged from the third reverse osmosis module 30 merges with the raw water R supplied by the feed pump FP and flows into the third pump P3. The third pump P3 transfers the merged water to the input ends of the first and second reverse osmosis modules 10 and 20.

[0051] A jet pump using the principle of accelerating the flow of raw water R by the flow of concentrated water B may be used as the third pump P3 .

[0052] That is, since the pressure of the concentrated water B is higher than that of the raw water R, a pressure drop is required for the smooth confluence and transfer of the raw water R and the concentrated water B, but a corresponding energy loss is also required. Therefore, a jet pump is used as the third pump P3, and the flow of the concentrated water B can be used to accelerate the raw water R without a separate pressure drop.

[0053] Three-way control valves V11, V12, V21, V22, V31, and V32 (collectively referred to as V) are respectively configured at the input end and the output end of the first reverse osmosis module 10, the second reverse osmosis module 20, and the third reverse osmosis module 30, and are opened and closed along the horizontal flow direction or the vertical flow direction according to the control of the controller C.

[0054] The concentrated water discharge valve DV (Drain Valve) is arranged on the pipeline where the output ends of the first reverse osmosis module 10, the second reverse osmosis module 20 and the third reverse osmosis module 30 meet, and when the discharged water B meets the specified conditions, the drain valve DV is opened and closed under the control of the controller C.

[0055] The controller C will control the activation and operation level of each pump FP, P1, P2 for each operation step (S10 to S50) described later, and control the opening and closing of the three-way control valve V and the concentrate discharge valve DV.

[0056] The operation steps controlled by the controller C include: a first operation step (1 st step): supply raw water R (S10); second operation step (2 nd step): supply concentrated water B (S20); the third operation step (3 rd step): circulate the concentrated water B (S30); the fourth operation step (4 th step): discharge the concentrated water B (S40); and the fifth operation step (5 th step), changing the running direction of each reverse osmosis module (S50).

[0057] Here, assuming that the first reverse osmosis module 10 and the second reverse osmosis module 20 are set to forward operation, and the third reverse osmosis module 30 is set to reverse operation, each operation step is described in detail.

[0058] In the first operation step (S10), the controller C controls the three-way control valves V11, V12, V21, and V22 respectively configured at the input and output ends of the first reverse osmosis module 10 and the second reverse osmosis module 20 to open in the horizontal flow direction, and controls the three-way control valves V31 and V32 configured at the input and output ends of the third reverse osmosis module 30 to open in the vertical flow direction.

[0059] In addition, in the first operation step (S10), the controller C controls the feed pump FP and the first pump P1 so that the raw water R enters the first reverse osmosis module 10 and the second reverse osmosis module 20. Specifically, the controller C supplies the raw water by driving the feed pump FP, and when the flow rate of the raw water R supplied from the feed pump FP exceeds a preset reference value, the first pump P1 is started to be driven. At this time, the controller C controls the operation Hz of the first pump P1 based on a signal of a flow sensor (not shown) configured on the supply line of the raw water R.

[0060] In the second operation step (S20), the controller C controls the second pump P2 so that the concentrated water B discharged from the first reverse osmosis module 10 and the second reverse osmosis module 20 flows into the third reverse osmosis module 30. Specifically, when the flow rate of the concentrated water B exceeds a preset reference, the controller C starts to start the second pump P2, and controls the operation Hz of the second pump P2 based on a signal of a flow sensor (not shown) configured on the supply line of the concentrated water B. On the other hand, the fresh water filtered (permeated) while flowing through the first reverse osmosis module 10 and the second reverse osmosis module 20 is discharged through the pipeline.

[0061] In the third operation step (S30), the concentrated water B discharged from the third reverse osmosis module 30 flows into the third pump P3 through the three-way control valve V31 disposed at the output end of the third reverse osmosis module 30. In addition, the raw water R supplied by the feed pump FP and the first pump P1 also flows into the third pump P3 and merges with the inflowing concentrated water B. On the other hand, the fresh water filtered (permeated) when flowing through the third reverse osmosis module 10 is also discharged through the pipeline.

[0062] The first operation step (S10) to the third operation step (S30) are repeatedly performed until any one of the concentration, pressure, flow rate, and scale amount of the concentrated water B detected by the specified sensor S exceeds a preset threshold. Therefore, the specified sensor S can be any one of a concentration sensor, a flow sensor, a pressure sensor, and a scale sensor, and at least one of these sensors is arranged on the moving path of the concentrated water B.

[0063] When any one of the concentration, pressure, flow rate, and scale amount of the concentrated water B exceeds a preset threshold, the fourth operation step (S40) is performed. Figure 4 is a schematic diagram showing a fourth operation step of a sequential cycle engineering reverse osmosis desalination device according to one embodiment.

[0064] In the fourth operation step (S40), when the preset first condition is met, the controller C controls the three-way control valves V31 and V32 to convert the third reverse osmosis module 30 into a forward reverse osmosis module, and continuously supplies raw water R to the input ends of all reverse osmosis modules 10, 20, and 30 and discharges concentrated water B at the output ends of all reverse osmosis modules 10, 20, and 30 to the outside until the preset second condition is met.

[0065] Specifically, when the measured value of the sensor S reaches a preset threshold, the controller C opens all three-way control valves (V11 to V32) configured at the input and output ends of all reverse osmosis modules 10, 20, 30 in the horizontal flow direction, and opens the closed concentrated water discharge valve DV. At this time, the operation of the second pump P2 can be stopped, or operated at the minimum Hz or reversely switched and operated.

[0066] In the fourth operation step (S40), the first condition means that the measurement value of the sensor S arranged on the movement path of the concentrated water B reaches a preset reference (for example, a threshold value of at least one of concentration, salinity, flow rate, pressure, and scale amount) or a preset time has passed after the third operation step (S30).

[0067] Furthermore, in the fourth operation step (S40), the second condition refers to that the concentration of the concentrated water B reaches a preset initial concentration.

[0068] The concentrated water discharge valve DV is in a shielding state in the first operation step (S10) to the third operation step (S30), and then opens to discharge the concentrated water B when the first condition is met in the fourth operation step (S40), and then switches to the shielding state again when the second condition is met.

[0069] The first operation step (S10) to the fourth operation step (S40) described above may be defined as one batch process and will be simply referred to as "one batch".

[0070] In a sequential cycle reverse osmosis desalination device of one embodiment, the operation direction of the reverse osmosis module is reset every time a batch is finished.

[0071] For example, in the first batch, if the first reverse osmosis module 10, the second reverse osmosis module 20 and the third reverse osmosis module 30 are respectively operated in forward, forward and reverse directions, then in the second batch, the first reverse osmosis module 10, the second reverse osmosis module 20 and the third reverse osmosis module 30 are respectively operated in forward, reverse and forward directions, in the third batch, the first reverse osmosis module 10, the second reverse osmosis module 20 and the third reverse osmosis module 30 are respectively operated in reverse, forward and forward directions, and in the fourth batch, the first reverse osmosis module 10, the second reverse osmosis module 20 and the third reverse osmosis module 30 can be respectively operated in forward, forward and reverse directions in the same way as the first batch.

[0072] However, this is only an example, and the number of forward and reverse directions may vary according to the number of reverse osmosis modules, and the resetting order of the operating directions may also be modified in various ways.

[0073] That is, the controller C can determine the object of reverse operation in real time based on the measurement value of the sensor S of each reverse osmosis module, and determine the operation direction of each reverse osmosis module according to its determination result.

[0074] For example, as a result of measuring the pressure of the concentrate water B of each reverse osmosis module, if it is found that the pressure of a specific reverse osmosis module is higher due to an unpredictable reason, the specific reverse osmosis module needs to be reversely operated in order to intentionally remove dirt or scale. Therefore, even if it is time to reversely operate other reverse osmosis modules according to the preset schedule, the schedule can be changed to reversely operate the specific reverse osmosis module.

[0075] The fifth operation step (5 thstep) is a process of resetting the running direction of the reverse osmosis module after a batch from the first operation step (S10) to the fourth operation step (S40) is completed, Figure 5 Schematic diagram of a sequential cycle engineering reverse osmosis desalination device performing the fifth operation step.

[0076] In the fifth operation step (S50), the controller C controls the relevant three-way control valves (at least four of V11 to V32) to convert any one of the first reverse osmosis module 10 and the second reverse osmosis module 20 operating in the forward direction into a reverse reverse osmosis module, and converts the third reverse osmosis module 30 previously operating in the reverse direction into a forward reverse osmosis module.

[0077] When raw water R is injected into the reverse osmosis module, the concentration of raw water R increases toward the rear end of the reverse osmosis module, so the probability of scale generation increases, and as the scale increases, the total flux decreases, causing performance to deteriorate. Therefore, the injection direction of raw water R is periodically reversed, so that part of the scale is eliminated by the injection pressure of raw water R, and at the same time, the generation rate of biofouling and scale in the reverse osmosis module can be reduced.

[0078] On the other hand, the controller C may perform the fifth operation step (S50) immediately after completing a batch process, or may perform the fifth operation step (S50) only when a preset condition is satisfied after repeating a plurality of batch processes.

[0079] Figure 6 1 is a graph showing a time reduction range of a pressure increase each time a batch process from a first operation step to a fourth operation step of a sequential cycle process reverse osmosis desalination device according to an embodiment of the present invention is repeated.

[0080] refer to Figure 6In a general closed circuit reverse osmosis (CCRO), when the reverse osmosis module is continuously circulated through a batch process, the time for the pressure increase of the discharged concentrated water B decreases with the repetition of each batch. However, in the present invention, before the closed circuit reverse osmosis (CCRO) process of mixing the concentrated water B and the raw water R, the concentrated water B discharged from the forward RO module flows into the backward RO module so as to periodically reverse the injection direction of the raw water, thereby slowing down the generation rate of bio fouling and scale in the reverse osmosis module, and removing a part of the scale, thereby shortening the reduction range of the pressure increase time of the concentrated water, which has the effect of extending the clean in place (CIP) cycle.

[0081] The present invention has been described above with reference to several embodiments, but those skilled in the art will appreciate that various modifications and changes may be made to the present invention without departing from the scope of the idea and field of the present invention as described in the appended claims.

Claims

1. A sequential cycle reverse osmosis desalination device, characterized in that: Each of the plurality of forward reverse osmosis modules and at least one reverse reverse osmosis module are connected in parallel, and concentrated water discharged from the forward reverse osmosis module flows into the reverse reverse osmosis module, and concentrated water discharged from the reverse reverse osmosis module flows into each of the forward reverse osmosis modules.

2. The sequential cycle reverse osmosis desalination device according to claim 1 is characterized in that: include: Feed pump, supplying raw water, A first pump, connected to the output end of the feed pump, A second pump is connected to the output end of the forward reverse osmosis module, a third pump connected to the output of the first pump, and A controller, in a first operation step, controls the feed pump and the first pump to allow raw water to enter the plurality of forward reverse osmosis modules, and in a second operation step, controls the second pump to allow concentrated water discharged from the forward reverse osmosis module to enter the reverse reverse osmosis module; When the concentrated water discharged from the reverse osmosis module merges with the raw water and enters the forward reverse osmosis module in the third operation step, the third pump is driven without additional control.

3. The sequential cycle engineering reverse osmosis desalination device according to claim 2 is characterized in that: The first pump and the second pump are high-pressure pumps, and the third pump is a jet pump that accelerates the raw water of the third operation step by using the flow of concentrated water.

4. The sequential cycle reverse osmosis desalination device according to claim 3 is characterized in that: A three-way control valve is respectively configured at the input end and the output end of the plurality of forward reverse osmosis modules and the reverse reverse osmosis modules. The controller is configured to: In the fourth operation step, when the preset first condition is met, the three-way control valve is controlled so that the reverse reverse osmosis module is converted into a forward reverse osmosis module, and raw water is continuously supplied to the input ends of all reverse osmosis modules and concentrated water at the output ends of all reverse osmosis modules is discharged to the outside until the preset second condition is met.

5. The sequential cycle reverse osmosis desalination device according to claim 4, characterized in that: The following condition is taken as the first condition: The measurement value of at least one of the concentration sensor, the flow sensor, and the pressure sensor arranged on the moving path of the concentrated water reaches a preset reference value, or a preset time has passed after the third operation step.

6. The sequential cycle reverse osmosis desalination device according to claim 5, characterized in that: The following condition is taken as the second condition: The concentration of the concentrated water reaches the preset initial concentration.

7. The sequential cycle reverse osmosis desalination device according to claim 5, characterized in that: The controller is configured to: After completing a batch process from the first operation step to the fourth operation step, a fifth operation step is performed, in which the three-way control valve is controlled to convert at least one of the plurality of forward reverse osmosis modules into a reverse reverse osmosis module and the existing reverse reverse osmosis module is converted into a forward reverse osmosis module.

8. The sequential cycle reverse osmosis desalination device according to claim 7, characterized in that: The controller performs the fifth operation step after executing a plurality of the batch processes.

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