KR102803475B1 - Circle sequence osmosis deionization device performing adaptive cycle control and method of addaptive cycle control using the same - Google Patents

Abstract

The present invention relates to a sequential circulation process osmotic desalination device and an adaptive cycle control method capable of fundamentally ensuring a high recovery rate by adopting a closed-loop osmotic technology, sequentially applying a reverse osmotic technology to reduce fouling, and dynamically controlling the number of cycles until the direction of an osmotic module is changed based on existing operating data (pressure of a pipeline) to increase operating efficiency and stably produce high-quality fresh water.

Description

{CIRCLE SEQUENCE OSMOSIS DEIONIZATION DEVICE PERFORMING ADAPTIVE CYCLE CONTROL AND METHOD OF ADDAPTIVE CYCLE CONTROL USING THE SAME}

The present invention relates to a sequential circulating process osmotic desalination device with adaptive cycle control and a control method thereof, and more particularly, to a sequential circulating process osmotic desalination device with adaptive cycle control and an adaptive cycle control method, which adopts a closed-loop osmotic technology to basically ensure a high recovery rate, sequentially applies a reverse osmotic technology to reduce fouling, and dynamically adjusts the number of cycles for desalination based on changes in operating conditions, that is, the amount of pressure change in a pipe, so as to increase operating efficiency and stably produce high-quality fresh water.

Water shortage refers to the difficulty in obtaining available fresh water sources due to resource depletion, and water shortage is becoming more severe worldwide due to industrialization and abnormal climate phenomena.

However, water is an essential element in human life and various industrial fields, and its demand continues to increase. As one effective method to meet this demand, the so-called seawater desalination method, which involves desalinating large amounts of seawater, has been proposed.

Seawater 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, and industrial water.

Current seawater desalination facilities employ either the multiple-stage flash distillation (MSF) process or the reverse osmosis process. Of these, the reverse osmosis process is a process that produces fresh water by applying pressure higher than the osmotic pressure to raw water or brine to remove solutes such as ions and organic molecules and moving pure water through a semipermeable membrane.

Meanwhile, unlike the general reverse osmosis process, there is a closed-circuit reverse osmosis (CCRO) seawater desalination method that mixes the concentrated water discharged from the reverse osmosis facility with raw water or brine and re-injects it into the reverse osmosis facility to achieve the target recovery rate, and discharges the concentrated water when the target concentration is reached.

In this regard, Korean Patent No. 10-1052662 discloses a feature in which multiple closed-circuit desalination units (CCROs) are connected in parallel as a device for continuous batch sequential desalination of brine in a closed circuit by reverse osmosis.

However, the existing closed-circuit desalination device (CCRO) using reverse osmosis has a problem in that the time for which the pressure of the concentrated water discharged through the reverse osmosis facility increases decreases as the process progresses, shortening the cleaning or replacement cycle of the reverse osmosis facility. In addition, if the concentrated water is continuously circulated, the concentration of the concentrated water gradually increases, which increases the amount of scale generated. Therefore, a technology is needed that can reduce the amount of chemicals used to suppress scale by optimizing the time for circulating the concentrated water and minimizing the amount of scale generated.

Republic of Korea Patent Publication No. 10-1052662 (2011.07.22)

The problem to be solved by the present invention is to provide a sequential circulation process osmotic desalination device and an adaptive cycle control method capable of basically ensuring a high recovery rate by adopting a closed-loop reverse osmosis technology, reducing fouling by sequentially applying reverse osmosis technology, and dynamically controlling the number of cycles until the direction of the reverse osmosis module is changed based on existing operating data regarding the pressure of the pipeline, thereby increasing operating efficiency and stably producing high-quality fresh water.

The present invention is one of the means for solving the problem, and is a sequential circulating process osmotic desalination device with adaptive cycle control, comprising: an osmotic unit in which a plurality of forward osmotic modules and at least one reverse osmotic module into which brine output from the forward osmotic modules is input are connected in parallel; And the present invention proposes a sequential circulation process osmotic desalination device with an adaptive cycle control, which includes a controller that controls the desalination device in a circulation mode in which the concentrated water output from the reverse osmosis module is mixed with raw water and inputted into the forward osmosis module, or a discharge mode in which the concentrated water output from the reverse osmosis module is discharged to the outside, and a reset mode in which at least one of the forward osmosis modules included in the osmosis unit is sequentially switched to the reverse direction and operated in a preset order and the rest are operated in the forward direction when N cycles (N is a natural number greater than or equal to 1) of the circulation mode and the discharge mode are completed, and compares the inflow pressure and differential pressure gradient of the circulation mode of the first cycle among the N cycles with the inflow pressure and differential pressure gradient of the circulation mode of the last cycle among the N cycles to reset the number of cycles until operation in the next reset mode.

In one embodiment, in the circulation mode, the controller may control the desalination device so that raw water is supplied to the forward osmosis module, concentrated water output from the reverse osmosis module is input again to the forward osmosis units, and when the quality of the fresh water (permeate) filtered in the osmosis unit satisfies a standard value, it is discharged to the outside.

In one embodiment, in the circulation mode, the controller may control the desalination device so that when the quality of the permeate filtered from the osmosis unit exceeds a reference value, the permeate is transferred to a filtered water tank, and the permeate in the filtered water tank is mixed with the raw water and then fed back into the forward osmosis modules.

In one embodiment, the present invention further includes a pressure sensor provided at each point of a pipe through which raw water is supplied to the osmosis unit and a pipe through which concentrated water is discharged, for measuring the pressure and differential pressure of the pipe, and the controller may calculate the slope of the pipe supply pressure and differential pressure using the measured values of the pressure sensor.

In one embodiment, the controller may decrement the number of cycles until operation in the next reset mode if the slope of the inlet pressure and the differential pressure of the circulation mode of the last cycle among the N cycles increases by a reference value or more than the slope of the inlet pressure and the differential pressure of the circulation mode of the first cycle among the N cycles, and may increase the number of cycles until operation in the next reset mode if the slope of the inlet pressure and the differential pressure of the circulation mode of the last cycle among the N cycles decreases by a reference value or less than the slope of the inlet pressure and the differential pressure of the circulation mode of the first cycle among the N cycles.

In one embodiment, the osmotic pressure module may use either a reverse osmosis membrane or a nanofiltration membrane.

The present invention relates to an adaptive cycle control method for an osmotic desalination device having a sequential circulation process and an osmotic unit, which comprises a plurality of forward osmotic modules and at least one reverse osmotic module connected in parallel to input brine output from the forward osmotic modules, as another means for solving the problem, comprising: a circulation mode operation step including a step of supplying raw water to the osmotic unit, a step of inputting the brine output from the reverse osmotic unit back into the forward osmotic units, and a step of recovering fresh water (permeate) filtered in the osmotic unit to the outside; a discharge mode operation step in which the concentrated water output from the reverse osmotic module is discharged to the outside; a reset mode operation step in which, when N cycles (N is a natural number greater than or equal to 1) of the circulation mode and the discharge mode are completed, at least one of the osmotic modules included in the osmotic unit is sequentially operated in the reverse direction according to a preset order and the rest are operated in the forward direction; And the present invention proposes an adaptive cycle control method of a sequential circulating process osmotic desalination device, which includes a step of resetting the number of cycles until operation in the next reset mode by comparing the slopes of the inlet pressure and differential pressure of the circulation mode of the first cycle among the N cycles with the slopes of the inlet pressure and differential pressure of the circulation mode of the last cycle among the N cycles.

In one embodiment, the circulation mode operation step may further include a step of discharging the permeate filtered from the osmosis unit to the outside when the quality of the permeate satisfies a standard value, and transferring the permeate to a filtered water tank when the quality of the permeate exceeds the standard value.

In one embodiment, the cycle number resetting step may include a step of deducting the number of cycles until operation in a next reset mode if the slope of the inlet pressure and the differential pressure of the circulation mode of the last cycle among the N cycles increases by a reference value or more than the slope of the inlet pressure and the differential pressure of the circulation mode of the first cycle among the N cycles, and a step of increasing the number of cycles until operation in a next reset mode if the slope of the inlet pressure and the differential pressure of the circulation mode of the last cycle among the N cycles decreases by a reference value or less than the slope of the inlet pressure and the differential pressure of the circulation mode of the first cycle among the N cycles.

In one embodiment, the osmotic pressure module may use either a reverse osmosis membrane or a nanofiltration membrane.

According to an embodiment of the present invention, a closed-loop osmotic technology is adopted to basically ensure a high recovery rate, and reverse osmotic technology is sequentially applied to reduce fouling, while the number of cycles until the direction of the osmotic module is changed based on existing operating data (pressure of the pipeline) is flexibly controlled to increase operating efficiency and stably produce high-quality fresh water.

According to an embodiment of the present invention, by periodically reversing the direction of injection of raw water, a portion of the scale can be removed by the injection pressure of raw water (R), while slowing down the bio-fouling and scale generation rate within the osmotic pressure module.

Figure 1 is a schematic diagram showing the circulation mode of a sequential osmotic pressure desalination device of adaptive cycle control according to Example 1 of the present invention.
FIG. 2 is a schematic diagram showing the discharge mode of a sequential circulating process osmotic desalination device of adaptive cycle control according to Example 1 of the present invention.
Figure 3 is a block diagram showing the mode conversion process of the desalination device of this embodiment.
FIG. 4 is a schematic diagram showing the reset mode of a sequential circulating process osmotic desalination device of adaptive cycle control according to Example 1 of the present invention.
Figure 5 is a flow chart showing the raw water and concentrated water supply process in a sequential circulation process osmotic pressure desalination device of adaptive cycle control according to Example 2.
Figure 6 is a flow chart showing the process of determining the circulation of fresh water and switching the discharge mode in a sequential circulation process osmotic desalination device of adaptive cycle control according to Example 2.
Figure 7 is a flow chart showing the process of controlling the number of operations in the circulation mode through the change in pressure gradient in a sequential circulation process osmotic desalination device of adaptive cycle control according to Example 2.

Hereinafter, several embodiments of the present invention will be described in detail using drawings. However, this is not intended to limit the present invention to any specific embodiment, and it should be understood that all transformations, equivalents, and substitutions that include the technical idea of the present invention are included in the scope of the present invention.

In this specification, singular expressions include plural expressions unless the context clearly indicates otherwise.

When it is stated in this specification that a component "has" or "comprises" a sub-component, it is intended that the other component may be included, rather than excluding the other component, unless otherwise specifically stated.

The terms “Unit,” “Module,” and “Component” in this specification mean a unit that processes at least one function or operation, and may be implemented by hardware, software, or a combination of hardware and software.

The term “connected” in this specification may mean, but is not necessarily limited to, that two components are directly connected, and may also mean that the components are connected via one or more other components positioned between the components.

<Example 1>

The osmotic pressure device of this embodiment can use a reverse osmosis membrane or a nanofiltration membrane.

A reverse osmosis membrane is a semi-permeable membrane with the smallest pores used to purify water, and it uses the principle of applying high pressure from the outside to force water to pass in the opposite direction (reverse osmosis).

Nanofiltration membranes are semi-permeable membranes that can selectively remove particles and ions of a specific size at low pressure.

The osmotic pressure device of the present embodiment below will be described using an example of a reverse osmosis membrane, and for the convenience of explanation, the name of the osmotic pressure module will be defined as a reverse osmosis module.

FIG. 1 is a schematic diagram showing the circulation mode of a sequential circulating process osmotic desalination device of adaptive cycle control according to Example 1 of the present invention, and FIG. 2 is a schematic diagram showing the discharge mode of a sequential circulating process osmotic desalination device of adaptive cycle control according to Example 1 of the present invention.

As shown in FIGS. 1 and 2, the device of the present embodiment includes a reverse osmosis unit (10, 20, 30), a plurality of first three-way valves (XV11, XV12, XV21, XV22, XV31, V33), a second three-way valve (XV4), and a controller (200). In addition, the device further includes a feed pump (FP), a primary pump (P1), a secondary pump (P2), a tertiary pump (P3), a water quality sensor (AT), a first two-way valve (XV51), a second two-way valve (XV52), a pressure sensor (PT), and a controller (200).

The reverse osmosis unit (10, 20, 30) includes a plurality of forward reverse osmosis modules (10, 20) and one backward reverse osmosis module (30).

Reverse osmosis modules (10, 20, 30) are devices that filter seawater or saline water through a semi-permeable membrane to remove salt and other impurities, thereby converting it into fresh water (permeate). The concentrated water discharged from the reverse osmosis module of this embodiment is recycled in a predetermined cycle to increase the recovery rate of fresh water, and after the predetermined cycle is repeated, it is discharged to the outside.

The forward reverse osmosis module (10, 20) means that fluid is input to the front end (left side in the drawing) and output to the rear end, and the reverse reverse osmosis module (30) means that fluid is input to the rear end (right side in the drawing) and output to the front end. In this embodiment, the left side in the drawing of the reverse osmosis modules (10, 20, 30) is defined as the front end, and the right side in the drawing of the reverse osmosis modules (10, 20, 30) is defined as the rear end. That is, the front end of the forward reverse osmosis module (10, 20) becomes the input end and the rear end becomes the output end, and the front end of the reverse reverse osmosis module (30) becomes the output end and the rear end becomes the input end.

In this embodiment, an embodiment is shown consisting of two forward reverse osmosis modules (10, 20) and one reverse reverse osmosis module (30), but it is not necessarily limited thereto, and depending on the capacity of the brine to be treated, the reverse osmosis modules may be composed of two or four or more.

As a specific example, it may be composed of one forward reverse osmosis module (10, 20) and one reverse reverse osmosis module (30), or it may be composed of three forward reverse osmosis modules and one reverse reverse osmosis module, or it may be composed of three forward reverse osmosis modules and two reverse reverse osmosis modules.

In addition, the forward reverse osmosis module (10, 20) of the present embodiment may operate as a reverse reverse osmosis module or the reverse reverse osmosis module (30) may operate as a forward reverse osmosis module depending on the direction of inflow of the fluid (i.e., raw water or concentrated water).

Hereinafter, for convenience of explanation, among the reverse osmosis modules (10, 20, 30) (Ro modules) initially arranged in the arrangement of Fig. 1, the forward reverse osmosis modules (10, 20) are defined as the first reverse osmosis module (10) and the second reverse osmosis module (20), and the reverse reverse osmosis module (30) arranged in the reverse direction is defined as the third reverse osmosis module (30). However, the forward reverse osmosis modules (10, 20) and the reverse reverse osmosis modules (30) can be interchanged in the reset mode described below.

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, and the concentrated water (B, Brine) output from the first reverse osmosis module (10) and the second reverse osmosis module (20) in the forward direction is input to the third reverse osmosis module (30) in the reverse direction, and the concentrated water (B2) output from the third reverse osmosis module (30) in the reverse direction is input again to the first reverse osmosis module (10) and the second reverse osmosis module (20), respectively, forming a circulatory circuit.

In this embodiment, the first reverse osmosis module (10), the second reverse osmosis module (20), and the third reverse osmosis module (30) can be switched from forward to reverse, or from reverse to forward, by a plurality of first three-way valves (XV11, XV12, XV21, XV22, XV31, V33) (3-way control valves) described below.

The first 3-way control valve (XV11, XV12, XV21, XV22, XV31, XV32) is respectively positioned in front and behind the first reverse osmosis module (10), the second reverse osmosis module (20), and the third reverse osmosis module (30), and is opened and closed in the horizontal flow direction or the vertical flow direction under the control of the controller (200).

For example, when the three-way valves arranged in the front and rear of one reverse osmosis module are opened in the horizontal flow direction, it becomes a forward reverse osmosis module like the first reverse osmosis module (10), and when the three-way valves arranged in the front and rear of one reverse osmosis module are opened in the vertical flow direction, it becomes a reverse osmosis module like the third reverse osmosis module (30).

The second three-way valve (XV4) (3-way control valve) is positioned at a point in the conduit (L1) where the input terminals of the first reverse osmosis module (10), the second reverse osmosis module (20), and the third reverse osmosis module (30) are connected, and depending on the opening and closing direction, the concentrated water (B2) of the third reverse osmosis module (30) may be discharged to the outside or may be mixed with raw water and then input to the first reverse osmosis module (10) and the second reverse osmosis module (20). That is, the conduit (L1) through which each of the first reverse osmosis module (10), the second reverse osmosis module (20), and the third reverse osmosis module (30) is connected is a conduit through which the concentrated water of the third reverse osmosis module (30) in the reverse direction is output, and when the first reverse osmosis module (10) and the second reverse osmosis module (20) are reset in the reverse direction, the concentrated water of the first reverse osmosis module (10) and the second reverse osmosis module (20) is output through the conduit (L1).

For example, the second three-way valve (XV4) is opened and closed (left open in the drawing) so that the concentrated water (B2) of the third reverse osmosis module (30) is mixed with the raw water and then supplied to the first reverse osmosis module (10) and the second reverse osmosis module (20) in the circulation mode of the device, and is opened and closed (right open in the drawing) so that the concentrated water (B2) of the third reverse osmosis module (30) is discharged to the outside in the discharge mode (see Drawing 2).

The feed pump (FP) is installed to supply raw water (R) to the reverse osmosis modules (10, 20, 30), and can transport raw water (R) at a pressure of, for example, about 3 bar (g).

The primary pump (P1) is connected to the output terminal of the feed pump (FP), and starts operating when the flow rate of the raw water (R) supplied from the feed pump (FP) exceeds a preset standard. A high pressure pump can be used as the primary pump (P1).

The secondary pump (P2) is placed at the output terminal of the primary pump (P1) and transfers the combined water, which is a mixture of the concentrated water (B2) discharged from the third reverse osmosis module (30) and the pressurized raw water (R) supplied through the primary pump (P1), to the input terminals of the first reverse osmosis module (10) and the second reverse osmosis module (20) in the forward direction.

The secondary pump (P2) can be a jet pump of the principle that accelerates the flow of raw water (R) by utilizing the flow of concentrated water.

That is, since the pressure of the concentrated water (B2) is higher than that of the raw water (R), a pressure drop must be applied to ensure smooth joining and transport of the raw water (R) and the concentrated water (B2), but this requires the acceptance of an equivalent amount of energy loss. Therefore, by using a jet pump as the secondary pump (P2), the raw water (R) can be accelerated by utilizing the flow of the concentrated water (B) without a separate pressure drop.

The tertiary pump (P3) is connected to the output terminals of the first reverse osmosis module (10) and the second reverse osmosis module (20), and moves the concentrated water (B) discharged from the first reverse osmosis module (10) and the second reverse osmosis module (20) to the input terminal of the third reverse osmosis module (30). A booster pump can be used as the tertiary pump (P3).

The first two-way valve (XV51) is positioned at a point in a conduit (L2) where the output terminals of the first reverse osmosis module (10), the second reverse osmosis module (20), and the third reverse osmosis module (30) are connected, and depending on the opening and closing direction of the first two-way valve (XV51), the filtered fresh water (permeate) passing through the first reverse osmosis module (10), the second reverse osmosis module (20), and the third reverse osmosis module (30) may be discharged to the outside and recovered, or some of the fresh water may be supplied to a feed pump (FP), mixed with raw water, and then recirculated and supplied to the first reverse osmosis module (10) and the second reverse osmosis module (20) in the forward direction.

The reason for mixing the filtered fresh water with the raw water and recycling it to the first reverse osmosis module (10) and the second reverse osmosis module (20) in the forward direction is to improve the recovery rate of the fresh water and to lower the concentration of the raw water. In other words, when the concentration of the raw water is higher than the design concentration, the produced water (fresh water) that exceeds some water quality standards is not discarded, but rather mixed with the raw water to lower the concentration of the raw water, thereby preventing the pressure required to filter water in the reverse osmosis desalination device from increasing and recovering the discarded produced water to increase the recovery rate.

A water quality sensor (AT) is placed at a point in a pipe (L2) connected to the output terminals through which fresh water is discharged from the first reverse osmosis module (10), the second reverse osmosis module (20), and the third reverse osmosis module (30) to analyze the water quality of the fresh water.

For example, a water quality sensor (AT) analyzes the electrical conductivity of fresh water to measure the concentration of ions dissolved in the water, and if the concentration of ions is higher than the standard, it can be determined that salinity exceeding the water quality standard remains.

That is, fresh water having a salinity higher than the standard salinity is mixed with the raw water and circulated to each of the forward reverse osmosis modules (10, 20). At this time, the first two-way valve (XV51) is closed so that the fresh water is recirculated to the first reverse osmosis module (10) and the second reverse osmosis module (20), and the second two-way valve (XV52) arranged in the conduit (L2) through which the recirculated fresh water is connected to the feed pump (FP) is opened, so that the fresh water is mixed with the raw water and then recirculated to the first reverse osmosis module (10) and the second reverse osmosis module (20) in the forward direction, thereby increasing the fresh water recovery rate.

When fresh water is recycled to the first reverse osmosis module (10) and the second reverse osmosis module (20) in the forward direction, it may also be recycled through a filtered water tank (FWT).

Additionally, recycled fresh water also serves to lower the concentration of raw water that comes in higher than the design raw water concentration.

A pressure sensor (PT) is installed at a point in the pipeline through which raw water is supplied from the feed pump (FT) to the reverse osmosis modules (10, 20, 30) and measures the pressure in the pipeline.

Specifically, pressure sensors (PT) are installed at each point in the pipes through which raw water is supplied to the reverse osmosis modules (10, 20, 30) and the pipes through which concentrated water is output, to measure the pressure and differential pressure of the pipes.

The pressure sensor (PT) may be a hydraulic pressure sensor (PT), but the type of sensor is not limited to this.

The controller (200) controls the desalination device so that at least one of the reverse osmosis modules (10, 20, 30) operates in the reverse direction (e.g., 30) and the rest operate in the forward direction (e.g., 10, 20), but sequentially designates the reverse osmosis modules in a preset order (e.g., in the order of 30, 20, 10).

When the direction of the reverse osmosis modules (10, 20, 30) is designated, the controller (200) operates the desalination device in a circulation mode in which the concentrated water output from the reverse reverse osmosis module (30) is mixed with raw water and input into the forward reverse osmosis module (10, 20), a discharge mode in which the concentrated water output from the reverse reverse osmosis module is discharged to the outside, and a reset mode in which at least one of the reverse osmosis modules included in the reverse osmosis unit is sequentially operated in the reverse direction according to a preset order and the rest are operated in the forward direction when N cycles (N is a natural number greater than or equal to 1) of the circulation mode and the discharge mode are completed, and the inlet pressure and differential pressure gradient of the circulation mode of the first cycle among the N cycles are compared with the inlet pressure and differential pressure gradient of the circulation mode of the last cycle among the N cycles to reset the number of cycles until operation in the next reset mode.

The controller (200) controls the opening and closing directions of the first three-way valve (XV11, XV12, XV21, XV22, XV31, V33) and the second three-way valve (XV4) to operate in circulation mode and discharge mode.

The circulation mode is a mode in which the concentrated water discharged from the reverse osmosis module (30) is mixed with raw water and fed into each forward reverse osmosis module (10, 20), as shown in Fig. 1.

The circulation mode operates for an initially set time based on the pre-calculated concentration, pressure, flow rate, and scale of the concentrated water (B).

The discharge mode is a mode for discharging concentrated water to the outside, as shown in Fig. 2, and is performed after the circulation mode has been operated for the initially set time.

In reset mode, the controller (200) resets the operating direction of the reverse osmosis modules (10, 20, 30) after the cycles of the circulation mode and discharge mode are repeated a preset number of times.

Specifically, the controller (200) controls the first three-way valves (XV11, XV12, XV21, XV22, XV31, V33) to convert at least one of the forward reverse osmosis modules (10, 20) into a reverse reverse osmosis module and converts an existing reverse reverse osmosis module (30) into a forward reverse osmosis module after the circulation mode and the discharge mode are repeated a preset number of times.

For example, when raw water (R) is supplied into a reverse osmosis module, the concentration increases toward the rear end, so the probability of scale occurrence increases, and as the scale increases, the overall flux decreases, which deteriorates performance. Therefore, by periodically reversing the supply direction of the raw water (R), some of the scale can be removed by the supply pressure of the raw water (R), while slowing down bio-fouling and scale occurrence within the reverse osmosis module.

In other words, in a general closed circuit reverse osmosis (CCRO) process, the time for which the pressure of the concentrated water (B) discharged while continuously circulating through the reverse osmosis module in the initial batch state decreases for each batch, but in the present embodiment, before the closed circuit reverse osmosis (CCRO) process in which the concentrated water (B) and the raw water (R) are mixed, the concentrated water (B) discharged from the forward reverse osmosis module (10, 20) (forward RO module) is fed into the reverse reverse osmosis module (30) (backward RO module) with a preset cycle, thereby periodically reversing the supply direction of the raw water, thereby slowing down the rate of bio-fouling and scale generation in the reverse osmosis module and removing some of the scale, so that the decrease in the time for which the pressure of the concentrated water increases is shortened, thereby resulting in a longer CIP (clean in place) cycle.

Figure 3 is a block diagram showing the mode conversion process of the desalination device of this embodiment.

As shown in FIGS. 1 and 3, the controller (200) operates the desalination device in a circulation mode in which the concentrated water output from the reverse reverse osmosis module (30) is mixed with raw water and input into the forward reverse osmosis module, in a discharge mode in which the concentrated water output from the reverse reverse osmosis module (10, 20, 30) is discharged to the outside, and in a reset mode in which at least one of the reverse osmosis modules included in the reverse osmosis unit is sequentially operated in the reverse direction according to a preset order and the rest are operated in the forward direction when N cycles of the circulation mode and the discharge mode are completed, and compares the inlet pressure and differential pressure gradient of the circulation mode of the first cycle among the N cycles with the inlet pressure and differential pressure gradient of the circulation mode of the last cycle among the N cycles to reset the number of cycles until operation in the next reset mode.

The circulation mode is a mode in which the concentrated water discharged from the reverse osmosis module (30) is mixed with raw water and fed into each forward reverse osmosis module (10, 20). The circulation mode is operated for an initially set time based on the pre-calculated concentration, pressure, flow rate, and scale amount of the concentrated water (B).

The controller (200) sets the first three-way valves (XV11, XV12, XV21, XV22) arranged in front and behind the first reverse osmosis module (10) and the second reverse osmosis module (20) in the circulation mode in the forward direction by controlling them in the horizontal flow direction. In addition, the controller (200) sets the first three-way valves (XV31, XV32) arranged in front and behind the third reverse osmosis module (30) in the reverse direction by controlling them in the vertical flow direction.

The discharge mode is a mode that discharges the concentrated water to the outside, and is performed after the circulation mode has been operated for the initially set time (see Figure 2).

The controller (200) opens the second three-way valve (XV4) in the discharge mode in the vertical direction with the right side open in the drawing to stop the circulation of the concentrated water and discharge the concentrated water to the outside.

Additionally, the controller (200) converts at least one of the forward reverse osmosis modules (10, 20) into a reverse reverse osmosis module in the reset mode and converts the existing reverse reverse osmosis module (30) into a forward reverse osmosis module.

For example, in the reset mode, the controller (200) reverses the opening and closing direction of the first three-way valve (XV21, XV22) positioned in front and behind the second reverse osmosis module (20) from the horizontal flow direction to the vertical flow direction.

And the controller (200) switches the opening/closing direction of the first three-way valve (XV21, XV22) positioned in front and rear of the third reverse osmosis module (30) from the vertical flow direction to the horizontal flow direction, thereby setting it in the forward direction.

The reset mode operates at least one of the reverse osmosis modules (10, 20, 30) sequentially in reverse according to a preset order when N cycles of the circulation mode and discharge mode are completed, and the rest are operated in forward direction. This will be described in detail in Fig. 4.

The controller (200) compares the inlet pressure and differential pressure gradient of the circulation mode of the first cycle among N cycles of the circulation mode and the discharge mode with the inlet pressure and differential pressure gradient of the circulation mode of the last cycle among the N cycles, and resets the number of cycles until operation in the next reset mode.

Specifically, the controller (200) decrements the number of cycles until operation in the next reset mode when the inlet pressure and differential pressure gradients of the circulation mode of the last cycle among N cycles increase by a reference value or more than the inlet pressure gradient of the circulation mode of the first cycle among N cycles, and increases the number of cycles until operation in the next reset mode when the inlet pressure gradient of the circulation mode of the last cycle among N cycles decreases by a reference value or less than the inlet pressure gradient of the circulation mode of the first cycle among N cycles.

For example, if one cycle is performed when the circulation mode is performed and the discharge mode is completed, and if this cycle is repeated 20 times and a reset mode is performed to change the direction of the reverse osmosis module, the controller (200) calculates the pressure gradient of the first cycle using the pressure value when the circulation mode of the first cycle starts and the pressure value when the purification mode of the first cycle ends, and calculates the pressure gradient of the 20th cycle using the pressure value when the circulation mode of the 20th cycle starts and the pressure value when the purification mode of the 20th cycle ends.

For reference, the pressure gradient is calculated as (pressure value when circulation mode is turned on - pressure value 30 seconds after circulation mode starts) / (circulation mode setting time - 30 seconds).

And, if the pressure gradient of the 20th cycle increases by 20% or more compared to the pressure gradient of the 1st cycle, the controller (200) reduces the number of cycles (i.e., 20 times) to 19 times before the next reset mode starts.

On the other hand, the controller (200) increases the number of cycles (i.e., 20) to 21 before the next reset mode starts if the pressure gradient of the 20th cycle decreases to 20% or less than the pressure gradient of the 1st cycle.

FIG. 4 is a schematic diagram showing the reset mode of a sequential circulating process osmotic desalination device of adaptive cycle control according to Example 1 of the present invention.

As shown in Fig. 4, the controller (200) controls the first three-way valves to designate at least one of the forward reverse osmosis modules (10, 20) as a reverse reverse osmosis module after the circulation mode and the discharge mode are repeated a preset number of times (e.g., 20 times), and converts the existing reverse reverse osmosis module (30) into a forward reverse osmosis module.

When the first reverse osmosis module (10) and the second reverse osmosis module (20) are set in the forward direction and the third reverse osmosis module (30) is placed in the reverse direction during the initial arrangement of the reverse osmosis modules (10, 20, 30), in the reset mode, the third reverse osmosis module (30) can be reset in the forward direction, and one of the first reverse osmosis module (10) and the second reverse osmosis module (20) can be reset in the reverse direction. In FIG. 4, resetting the second reverse osmosis module (20) in the reverse direction is described as an example.

Specifically, the controller (200) reverses the opening and closing direction of the first three-way valve (XV21, XV22) positioned in front and behind the second reverse osmosis module (20) from a horizontal flow direction to a vertical flow direction.

And the controller (200) switches the opening/closing direction of the first three-way valve (XV21, XV22) positioned in front and rear of the third reverse osmosis module (30) from the vertical flow direction to the horizontal flow direction, thereby setting it in the forward direction.

<Example 2>

Example 2 relates to a control method of a sequential circulation process reverse osmosis desalination device of Example 1.

The method of the present embodiment includes a circulation mode operation step, a discharge mode operation step, a reset mode operation step, and a step of resetting the number of cycles. And the method of the present embodiment may further include a step of transporting fresh water to a filtered water tank.

For convenience of explanation, the circulation mode operation step is described in Fig. 5, the discharge mode operation step is described in Fig. 6, and the reset mode operation step and the step of resetting the number of cycles are described in Fig. 7.

Figure 5 is a flow chart showing the raw water supply and concentrated water supply processes in a sequential circulation process osmotic desalination device of adaptive cycle control according to Example 2.

As shown in FIG. 1 and FIG. 5, the circulation mode operation step selects a module among the reverse osmosis modules (10, 20, 30) to be set in the reverse direction. In the present embodiment, the third reverse osmosis module (30) is set in the reverse direction (S11).

The first three-way valves arranged in front and behind the third reverse osmosis module (30) are set in the reverse direction by adjusting in the vertical flow direction, and the first three-way valves arranged in front and behind the first reverse osmosis module (10) and the second reverse osmosis module (20) are set in the forward direction by adjusting in the horizontal flow direction (S11).

Then, the first two-way valve (XV51) is opened (S11) so that the filtered fresh water from the reverse osmosis modules (10, 20, 30) can be discharged to the outside.

When the settings of the reverse osmosis module (10, 20, 30) and the first three-way valve are completed, the operation phase of the circulation mode starts and the feed pump (FP) is driven to supply raw water at a pressure of approximately 3 bar(g) (S12).

When raw water is supplied from the feed pump (FP), the timer of the initially set circulation mode starts (S13).

And at this point, the number of cycles in the cyclic mode can be counted (S14).

When raw water is supplied from the feed pump (FP), the primary pump (P1) starts operating (S15) after 10 seconds, and the speed of the primary pump (P1) gradually increases through the VFD (Variable Frequency Drive) up to the set flow rate value of the circulation mode, and when the set value is reached, PID (Proportional Integral-Derivative) control starts.

At this time, the VFD is controlled according to the signal of the flow meter (not shown) installed at the output terminal of the feed pump (FP).

After the primary pump (P1) is driven, 10 seconds later, the tertiary pump (P3) is driven (S16), and at this time, the concentrated water produced in the first reverse osmosis module (10) and the second reverse osmosis module (20) in the forward direction is supplied to the third reverse osmosis module (30) in the reverse direction with the pressure increased by approximately 1.5 bar.

In order to mix the concentrated water discharged from the third reverse osmosis module (30) in the reverse direction with the raw water and then circulate it to the first reverse osmosis module (10) and the second reverse osmosis module (20) in the forward direction, the second three-way valve (XV4) is adjusted in the vertical flow direction with the left side open in the drawing (S17).

Figure 6 is a flow chart showing the process of determining fresh water production and discharge in a circulation mode in a reverse osmosis desalination device with adaptive control according to Example 2.

As shown in Fig. 1 and Fig. 6, in the step of transporting fresh water to a filtered water tank, the fresh water filtered in the reverse osmosis modules (10, 20, 30) is monitored by a water quality sensor (AT) (S11).

If the water quality of the fresh water is measured by a water quality sensor (AT) (e.g., an electrical conductivity value) of less than 40 μS/cm, the first two-way valve (XV51) is opened (S2) and the second two-way valve (XV52) is closed (S3) to discharge the fresh water to the outside. If the measured value is 40 μS/cm or higher, the second two-way valve (XV52) is opened (S4) and the first two-way valve (XV51) is closed (S5) to mix the fresh water with the raw water and recirculate it.

Then, it is checked whether the circulation mode operation time has reached the set time (S6) and, depending on whether it has reached the set time, it switches to the discharge mode.

Figure 7 is a flow chart showing the process of switching from circulation mode to discharge mode in a circulating process reverse osmosis desalination device of adaptive control according to Example 2.

When the circulation mode is operated for a preset period of time and then switched to the discharge mode, the discharge mode operation phase starts, and in the discharge mode operation phase, the second three-way valve (XV4) is opened in the vertical direction with the right side open in the drawing to stop the circulation of the concentrated water and discharge the concentrated water to the outside (S21, S24). As a reference, at this time, the timer of the circulation mode ends (S22) and the timer of the discharge mode starts (S23).

At this time, the 3rd pump (P3) is set to the minimum operating point of 15 Hz (S25), and the 1st pump (P1) gradually reduces the pump speed (S26) through the VFD to the set flow rate value of the discharge mode, and when the set value is reached, PID control starts. At this time, the VFD is controlled according to the signal of the 2nd flow meter (FT1).

The above process is repeated until the count of the circulation/discharge mode reaches a predetermined number of times.

Figure 8 is a flow chart showing the process of controlling the number of operations in the circulation mode through the change in pressure gradient in a circulating process reverse osmosis desalination device with adaptive cycle control according to Example 2.

The reset mode operation step is a mode that resets the operating direction of the reverse osmosis modules (10, 20, 30) after the cycle in which the circulation mode and discharge mode are operated is repeated a preset number of times.

In one embodiment, assuming that one cycle is one in which the circulation mode is performed and the discharge mode is completed, and that this cycle is repeated 20 times, a reset mode operation step for switching the direction of the reverse osmosis module is performed, the step of resetting the number of cycles is a step of controlling the number of times each cycle in which the circulation mode and the discharge mode are completed is repeated.

As shown in FIG. 1 and FIG. 8, the controller switches the flow direction of the reverse osmosis modules (10, 20, 30) when the discharge mode is terminated a predetermined number of times (e.g., 20 times).

At this time, in order to change the flow direction of the reverse osmosis modules (10, 20, 30), first check whether the first three-way valves are open (S31).

That is, at least one of the forward reverse osmosis modules is converted into a reverse reverse osmosis module, and the existing reverse reverse osmosis module is converted into a forward reverse osmosis module (reset mode).

For example, when the first reverse osmosis module (10) and the second reverse osmosis module (20) are set in the forward direction and the third reverse osmosis module (30) is set in the reverse direction during the initial arrangement of the reverse osmosis modules (10, 20, 30), the controller checks the first three-way valves (XV11, XV12, XV21, XV22, XV31, V33) to sequentially check whether all reverse osmosis modules, including the first reverse osmosis module (30), the second reverse osmosis module (20), and the first reverse osmosis module (20), are set in the reverse direction (S31).

For example, if the third reverse osmosis module (30) is first designated in the reverse direction during the reset mode operation phase, when the cycle is repeated 20 times, the second reverse osmosis module (20) is designated in the reverse direction through the reset mode, and the first reverse osmosis module (10) and the third reverse osmosis module (30) are designated in the forward direction.

And again, when the cycle is repeated 20 times, the next first reverse osmosis module (20) is designated in the reverse direction through the reset mode, and the second reverse osmosis module (10) and the third reverse osmosis module (30) are designated in the forward direction.

If the first reverse osmosis module (30) to the third reverse osmosis module (30) are not sequentially designated in reverse direction once each, they are designated in reverse direction in a pre-designated order (S32).

If the first reverse osmosis module (30) to the third reverse osmosis module (30) are sequentially designated in reverse direction once each, the count for operation in reset mode is initialized to 0 (S34). If the count is initialized to 0, in the next reset mode, the third reverse osmosis module (30), the second reverse osmosis module (20), and the first reverse osmosis module (10) are designated in reverse direction again in sequence.

The controller (200) compares the inlet pressure gradient of the circulation mode of the first cycle of N cycles with the inlet pressure gradient of the circulation mode of the last cycle of N cycles in the step of resetting the number of cycles, and resets the number of cycles until operation in the next reset mode.

The controller (200) calculates the pressure gradient of the first cycle using the pressure value when the circulation mode of the first cycle starts and the pressure value when the purification mode of the first cycle ends, and calculates the pressure gradient of the 20th cycle using the pressure value when the circulation mode of the 20th cycle starts and the pressure value when the circulation mode of the 20th cycle ends (S35).

On the other hand, if the pressure gradient of the 20th cycle increases by 20% or more compared to the pressure gradient of the 1st cycle, the controller (200) increases the number of cycles (i.e., 20 times) before the next reset mode starts to 21 times (S36).

And, if the pressure gradient of the 20th cycle decreases by 20% or less than the pressure gradient of the 1st cycle, the controller (200) reduces the number of cycles (i.e., 20 times) to 19 times before the next reset mode starts (S37).

Although the present invention has been described above with reference to several embodiments thereof, it will be understood by those skilled in the art that various modifications and changes may be made to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below.

10: 1st reverse osmosis module
20: Second reverse osmosis module
30: Third reverse osmosis module
FP: Feed pump
P1: Primary pump
P2: Secondary pump
P3: 3rd pump

Claims (10)

In a sequential osmotic desalination device with adaptive cycle control,
An osmotic unit having a plurality of forward osmotic modules and at least one reverse osmotic module connected in parallel to which brine output from the forward osmotic modules is input; and
A desalination device is operated in a circulation mode in which the concentrated water output from the reverse osmosis module is mixed with raw water and input into the forward osmosis module, or in a discharge mode in which the concentrated water output from the reverse osmosis module is discharged to the outside, and in a reset mode in which at least one of the forward osmosis modules included in the osmosis unit is sequentially switched to the reverse direction in a preset order and the rest are operated in the forward direction when N cycles (N is a natural number greater than or equal to 1) of the circulation mode and the discharge mode are completed, and a controller is included to reset the number of cycles until operation in the next reset mode by comparing the inflow pressure and differential pressure gradient of the circulation mode of the first cycle among the N cycles with the inflow pressure and differential pressure gradient of the circulation mode of the last cycle among the N cycles.
The above controller,
If the slope of the inflow pressure and differential pressure of the circulation mode of the last cycle among the N cycles increases by a reference value or more than the slope of the inflow pressure and differential pressure of the circulation mode of the first cycle among the N cycles, the number of cycles until operation in the next reset mode is deducted, and if the slope of the inflow pressure and differential pressure of the circulation mode of the last cycle among the N cycles decreases by a reference value or less than the slope of the inflow pressure and differential pressure of the circulation mode of the first cycle among the N cycles, the number of cycles until operation in the next reset mode is increased.
Sequential cyclic process osmotic desalination device with adaptive cycle control. In the first paragraph,
In the circulating mode, the above controller,
A sequential circulating process osmotic desalination device with an adaptive cycle control characterized in that raw water is supplied to the forward osmosis module, the concentrated water output from the reverse osmosis module is input again to the forward osmosis modules, and the desalination device is controlled so that the permeate filtered in the osmosis unit is discharged to the outside when the water quality satisfies a standard value. In the first paragraph,
In the circulating mode, the above controller,
A sequential circulating process osmotic desalination device with an adaptive cycle control characterized in that when the quality of the permeate filtered in the osmotic unit exceeds a standard, the permeate is transferred to a filtered water tank, and the permeate in the filtered water tank is mixed with raw water and then fed back into the forward osmotic desalination modules. In the first paragraph,
It further includes a pressure sensor that is installed at each point of the pipe through which raw water is supplied to the above osmotic pressure unit and the pipe through which concentrated water is output, and measures the pressure and differential pressure of the pipe.
A sequential circulating process osmotic desalination device with adaptive cycle control, characterized in that the controller calculates the slope of the pipe supply pressure and differential pressure using the measured values of the pressure sensor. delete In the first paragraph,
The above osmotic pressure module is,
A sequential osmotic desalination device characterized by using either a reverse osmosis membrane or a nanofiltration membrane. A method for adaptive cycle control of a sequential circulating process osmotic desalination device, comprising an osmotic unit connected in parallel with a plurality of forward osmotic modules and at least one reverse osmotic module into which brine output from the forward osmotic modules is input,
A circulation mode operation step including a step of supplying raw water to the osmosis unit, a step of re-inputting concentrated water output from the reverse osmosis module into the forward osmosis modules, and a step of recovering fresh water (permeate) filtered from the osmosis unit to the outside;
A discharge mode operation step in which the concentrated water output from the above reverse osmosis module is discharged to the outside;
When N cycles (N is a natural number greater than or equal to 1) of the above circulation mode and the above discharge mode are completed, a reset mode operation step in which at least one of the osmotic pressure modules included in the above osmotic pressure unit is sequentially operated in reverse according to a preset order and the rest are operated in forward direction; and
It includes a step of resetting the number of cycles until operation in the next reset mode by comparing the slope of the inlet pressure and differential pressure of the circulation mode of the first cycle among the N cycles with the slope of the inlet pressure and differential pressure of the circulation mode of the last cycle among the N cycles.
The above cycle count reset step is:
A step of deducting the number of cycles until operation in the next reset mode if the slope of the inflow pressure and differential pressure of the circulation mode of the last cycle among the N cycles increases by a reference value or more than the slope of the inflow pressure and differential pressure of the circulation mode of the first cycle among the N cycles, and a step of increasing the number of cycles until operation in the next reset mode if the slope of the inflow pressure and differential pressure of the circulation mode of the last cycle among the N cycles decreases by a reference value or less than the slope of the inflow pressure and differential pressure of the circulation mode of the first cycle among the N cycles.
Adaptive cycle control method for a sequential osmotic desalination device using adaptive cycle control. In Article 7,
The above circulation mode operation step is:
A step of discharging the fresh water (permeate) filtered in the above osmotic pressure unit to the outside when the water quality satisfies the standard, and transferring the fresh water to a filtered water tank when the water quality exceeds the standard.
A method for adaptive cycle control of a sequential osmotic desalination device including an adaptive cycle control further comprising: delete In Article 7,
The above osmotic pressure module is,
An adaptive cycle control method for a sequential circulating process osmotic desalination device characterized by using either a reverse osmosis membrane or a nanofiltration membrane.