KR20210133631A - Complex desalination system using pressure-retarded osmosis for sea water desalination - Google Patents

Abstract

The present invention relates to a complex desalination system using pressure-retarded osmosis for sea water desalination, which performs water treatment for seawater and brackish water reverse osmosis (BWRO) wastewater. According to one embodiment of the present invention, the complex desalination system comprises: a pretreatment facility pre-filtering seawater; a first pressure exchange device increasing pressure by receiving seawater from the pretreatment facility; a second pressure exchange device increasing pressure by receiving at least a part of the seawater supplied from the first pressure exchange device; a first pressure regulating device pressurizing the remaining part of the seawater supplied from the first pressure exchange device; a second pressure regulating device pressurizing the seawater supplied from the second pressure exchange device; an SWRO facility produces salt-filtered water from the seawater supplied from the first pressure regulator and the second pressure regulator through a seawater desalination reverse osmosis membrane and transferring unfiltered SWRO concentrated water to the second pressure exchange device; a BWRO facility receiving and filtering sewage treatment plant effluent through a brackish water desalination reverse osmosis membrane and discharging unfiltered BWRO concentrated water; and a pressure-retarded osmosis (PRO) facility supplying, to the first pressure exchange device, PRO water which is produced by performing a pressure delay osmosis process on the SWRO concentrated water supplied from the second pressure exchange device and the BWRO concentrated water supplied from the BWRO facility.

Description

Complex desalination system using pressure delayed osmosis technology for seawater desalination

The present invention relates to a complex desalination system using seawater desalination pressure delayed osmosis technology.

As the demand for drinking water or industrial water continues to increase, the importance of seawater desalination technology is increasing. In addition, economically feasible and large-scale seawater desalination technology is particularly important for reasons such as continuous population growth and the growth of related industries.

Although the membrane-based desalination process consumes less energy compared to the thermal desalination process, it is still high.

Accordingly, as a desalination method with a low energy consumption, several methods including a technology to which fluid energy generated from forward osmosis and pressure-retarded osmosis (PRO) processes are applied have been developed. Although the forward osmosis technology has a mechanism of low energy consumption in theory, there is no practical application of it to the desalination process.

In applying the forward osmosis technology to the desalination process, a technology for separating water from a draw solution and a technology for recovering the draw solution are important for a continuous and practical process, but these technologies still have many problems.

On the other hand, PRO process technology is spotlighted as a technology that can recover or produce energy (Statkraft Osmotic Power Pilot Plant, Norway). However, for the commercialization of PRO process technology, the development of innovative technology for maximum energy recovery or generation is required.

The driving force of the osmotic process is the difference in osmotic pressure between two aqueous solutions facing the semipermeable membrane. The osmotic pressure of the aqueous solution may be calculated by the Van't Hoff relation.

π = θ.v.c.R.T.

where v is the number of ions generated during desalination of the solute, θ is the osmotic coefficient, c is the concentration of all solutes (moles/l), R is the universal gas constant (0.083145 l.bar/moles.K), and , T is the absolute temperature (K).

The flow rate through the semipermeable membrane due to the osmotic pressure difference is given by the following equation (McCutcheon and Elimelech, 2007).

Jw = A(π _D,b - π _F,b )

Here, J _w is the flow rate passing through the semi-permeable membrane, A is the net permeability coefficient of the semi-permeable membrane, and π _D,b and π _F,b are the bulk osmotic pressures during extraction and supply, respectively.

PRO is used to generate or recover energy (power) using the Gibbs free energy of mixing for the difference in salinity of two aqueous solutions (Sandler, SI, 1999, Chemical Engineering Thermodynamics, 3rd ed) .; Wiley).

-ΔGmix = RT{[Σx _i ln(γ _i x _i )] _M - θ _A [Σx _i ln(γ _i x _i )] _A -θ _B [Σx _i ln(γ _i x _i )] _B }

where x _i is the mole fraction of the reagent i in solution, R is the gas constant, T is the temperature, and γ is the activity coefficient of the reagent.

In the PRO system, a constant fluid pressure is applied to the high salinity aqueous solution, and water continues to permeate from the low salinity aqueous solution, whereas the osmotic pressure difference between the two solutions is higher than the applied fluid pressure. The pressure of the high salinity aqueous solution is conserved by the additional energy generated from the mixing Gibbs free energy while the volume flux of the solution increases.

According to Yip and Elimelch (2012), the highest energy that can be extracted from the constant pressure PRO process is 0.75 kWh/m ³ when seawater and river water are used as extraction and feed solutions, respectively. Therefore, in terms of pressure and volume, the extracted mixed Gibbs free energy could be used to generate energy for a process or to recover pressure.

In the PRO process energy production scheme, a water turbine turbine can be used to generate power using the pressure and volume flux of an aqueous solution. At this time, even if the efficiency of the latest Pelton turbine can reach 92%, the average efficiency is generally around 90%, and the overall efficiency including power generation facilities such as generators will reach about 80%.

Recently, in the reverse osmosis (RO) seawater desalination process, a PRO process technology using a pressure exchanger that can transfer and recover the pressure of the high-salinity reverse osmosis membrane concentrate to seawater raw water has been developed. By recovering the osmotic energy generated from the PRO process as it is and applying it to the existing seawater desalination process, the energy consumption required for seawater desalination can be greatly reduced.

Isobaric pressure exchangers applicable to reverse osmosis seawater desalination and PRO processes have efficiencies of up to 97%. Therefore, the seawater desalination complex process incorporating the PRO process, which can recover and transmit pressure using such a pressure exchange device, has higher energy recovery efficiency than the method of producing the generated osmotic energy as electric power through a water turbine turbine, and also simplifies the process facility. because you can

In addition, the higher the salt concentration of the seawater desalination concentrated water, the greater the PRO process energy recovery, and the effluent from the low-salinity sewage treatment plant and sewage reuse facility can be used to generate high-salinity concentrated water and osmotic energy. Accordingly, there is a demand for a seawater desalination and sewage treatment or sewage reuse complex desalination facility incorporating the PRO process.

An embodiment of the present invention uses wastewater (discharge water) generated in the BWRO (Brackish Water Reverse Osmosis) process for further treatment of sewage treatment plant effluent as raw water for the PRO process together with reverse osmosis seawater desalination concentrated water, seawater and BWRO wastewater It is intended to provide a complex desalination system using PRO technology that enables complex water treatment.

According to an aspect of the present invention, a pre-treatment facility for pre-filtering seawater; a first pressure exchanging device for increasing the pressure by receiving seawater from the pretreatment facility; a second pressure exchanging device that receives at least a portion of the seawater supplied from the first pressure exchanging device to increase the pressure; a first pressure regulating device (high pressure pump) for pressurizing the remaining part of the seawater supplied from the first pressure exchange device; a second pressure regulating device (booster pump) for pressurizing the seawater supplied from the second pressure exchanging device; The seawater supplied from the first pressure control device and the second pressure control device produces salt-filtered product water through a seawater desalination reverse osmosis membrane, and the SWRO concentrated water that is not filtered with salt is delivered to the second pressure exchange device. SWRO equipment; BWRO facility that receives effluent from sewage treatment plant, filters it through brackish water desalination (BWRO) reverse osmosis membrane, and discharges unfiltered BWRO concentrated water; and PRO equipment for supplying the filtered PRO production water to the first pressure exchange device by performing a pressure delay osmosis process on the SWRO concentrated water supplied from the second pressure exchange device and the BWRO concentrated water supplied from the BWRO facility may include.

At this time, in the present invention, the flow rate of the PRO production water supplied to the first pressure exchange device and the flow rate of the seawater supplied to the first pressure exchange device can be controlled so as to remain the same.

In addition, the present invention may further include an RO facility that receives the PRO-produced water from the first pressure exchange device and filters the supplied PRO-produced water with salt through a reverse osmosis membrane to produce product water.

In addition, the present invention may further include a first bypass pipe for guiding at least a portion of the PRO produced water supplied to the inlet side of the first pressure exchange device to the outlet side of the first pressure exchange device.

In addition, the present invention may further include a second bypass pipe for guiding at least a portion of the PRO concentrated water discharged from the PRO facility to the first pressure exchange device.

In addition, the present invention may further include a third bypass pipe for guiding at least a portion of the seawater discharged from the pretreatment facility to the SWRO facility.

In addition, the present invention may further include a fourth bypass pipe for guiding at least a portion of the PRO produced water discharged from the first pressure exchange device to the pretreatment facility.

In addition, the PRO concentrated water discharged from the PRO facility may be supplied to the pre-treatment facility.

According to an embodiment of the present invention, by applying BWRO wastewater generated in the sewage reuse BWRO process that treats sewage treatment plant effluent to an osmotic process such as PRO where desalination of seawater is made, a complex desalination treatment for seawater and sewage treatment plant effluent can be performed. It has the effect that it is possible.

In addition, according to an embodiment of the present invention, by connecting SWRO and BWRO to the PRO facility, there is an effect that it is possible to maximize the recovery efficiency of energy recovered in seawater desalination and brackish water desalination process.

1 is a block diagram illustrating a complex desalination system according to a first embodiment of the present invention.
2 is a block diagram illustrating a complex desalination system according to a second embodiment of the present invention.
3 is a block diagram illustrating a complex desalination system according to a third embodiment of the present invention.
4 is a block diagram illustrating a complex desalination system according to a fourth embodiment of the present invention.
5 is a block diagram illustrating a complex desalination system according to a fifth embodiment of the present invention.
6 is a block diagram illustrating a complex desalination system according to a sixth embodiment of the present invention.
7 is a block diagram illustrating a complex desalination system according to a seventh embodiment of the present invention.
8 is a block diagram illustrating a complex desalination system according to an eighth embodiment of the present invention.

Hereinafter, specific embodiments for implementing the spirit of the present invention will be described in detail with reference to the drawings.

In addition, in the description of the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

In addition, when it is said that a component is 'connected', 'supported', 'connected', 'supplied', 'transferred', or 'contacted' to another component, it is directly connected, supported, connected, It should be understood that supply, delivery, and contact may occur, but other components may exist in between.

The terminology used herein is only used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise.

In addition, in this specification, the expression of the upper side, the lower side, the side, etc. is described with reference to the drawings in the drawings, and it is clarified in advance that if the direction of the object is changed, it may be expressed differently. For the same reason, some components are exaggerated, omitted, or schematically illustrated in the accompanying drawings, and the size of each component does not fully reflect the actual size.

Also, terms including an ordinal number such as 1st, 2nd, etc. may be used to describe various components, but the components are not limited by these terms. These terms are used only for the purpose of distinguishing one component from another.

The meaning of "comprising," as used herein, specifies a particular characteristic, region, integer, step, operation, element and/or component, and other specific characteristic, region, integer, step, operation, element, component, and/or group. It does not exclude the existence or addition of

Hereinafter, a detailed configuration of the complex desalination system using the seawater desalination pressure delayed osmosis technology according to an embodiment of the present invention will be described with reference to FIGS. 1 to 8 .

1 is a block diagram illustrating a complex desalination system according to a first embodiment of the present invention.

Referring to FIG. 1 , the complex desalination system 1 according to the first embodiment of the present invention receives seawater and treated WWTE and converts it to fresh water through desalination treatment. .

To implement this, the seawater desalination system 1 includes a pretreatment facility 100, a first pressure exchange device 200, a second pressure exchange device 300, a SWRO facility 400, a BWRO facility 500, and an RO facility. 600 and PRO facility 900 .

The pretreatment facility 100 may perform pre-filtration treatment (pretreatment) for desalination of seawater through the DAF device 110 and the seawater UF device 120 . The DAF device 110 may be a facility that performs a treatment process for separating and removing algae or particles of light specific gravity in raw water. The seawater UF device 120 may be a facility for performing an ultrafiltration membrane separation process. The seawater UF device 120 performs a process of first removing impurities by filtering raw water by a method of separating according to the size of a substance in a solution using a semi-permeable membrane. Since the DAF process and the UF process correspond to common technical knowledge in the art, detailed process descriptions will be omitted.

Seawater from which impurities such as algae have been removed through pre-treatment may be introduced into the first pressure exchange device 200 to receive pressure and pressurize. The seawater pressurized by the first pressure exchange device 200 is separated by a multi-way valve and flows into the second pressure exchange device 300 or into the first pressure control device 810, for example, a high-pressure pump. can be The seawater pressurized in the second pressure exchange device 300 may be further pressurized by the second pressure control device 820 , for example, a booster pump.

The first pressure exchanging device 200 refers to a device that transfers pressure from a liquid flow of a high pressure side to a liquid flow of a low pressure side while preventing the flows of the two liquids from mixing with each other. Since an example of such a pressure exchange device is disclosed in Korean Patent Publication No. 2014-0092836, a detailed description thereof will be omitted.

Some of the seawater pressurized by the first pressure exchange device 200 may be introduced into the SWRO facility 400 after the pressure is increased through the first pressure control device 810 (high-pressure pump). The remaining part of the seawater pressurized by the first pressure exchange device 200 flows into the SWRO facility 400 after being pressurized through the second pressure exchange device 300 and the second pressure control device (820: booster pump). can be

The SWRO facility 400 may be understood as a facility for desalination of seawater by reverse osmosis. The SWRO facility 400 includes a seawater desalination reverse osmosis membrane capable of permeating only water while hardly permeating solutes such as salt in the introduced seawater by applying a physical pressure equal to or higher than the osmotic pressure. For example, the SWRO facility 400 may produce the product water produced through the seawater desalination reverse osmosis membrane.

Since the produced water desalinated through the SWRO facility 400 is discharged to the outside in a drinkable state of low salt, it can be used for other purposes such as drinking, irrigation, or industrial use through a separately provided post-treatment process.

The SWRO facility 400 may deliver unfiltered SWRO concentrated water through the seawater desalination reverse osmosis membrane to the second pressure exchange device 300 .

The second pressure exchange device 300 may use the pressure of the SWRO concentrated water received from the SWRO facility 400 to reduce the pressure of the SWRO concentrated water while transferring it to the seawater supplied from the first pressure exchange device 200 . . The decompressed SWRO concentrated water may be pressurized to a predetermined pressure in the third pressure control device 830 such as a booster pump. SWRO concentrated water pressurized by the third pressure control device 830 is a draw solution with high salinity, and may be introduced into the PRO facility 900 .

Meanwhile, the Brackish Water Reverse Osmosis (BWRO) facility 500 may receive effluent from a sewage treatment plant from the effluent UF device 510 . In the effluent UF device 510 , pretreatment for desalination of effluent from a sewage treatment plant may be performed. The sewage treatment plant effluent pretreated through the effluent UF device 510 may be pressurized by the fourth pressure control device 840 such as a high-pressure pump and supplied to the BWRO facility 500 .

The BWRO facility 500 may filter the effluent from the sewage treatment plant that has undergone the pretreatment process through the brackish water desalination reverse osmosis membrane. The sewage treatment plant effluent filtered by the BWRO facility 500 may be sterilized through the UV device 520 and then discharged as low-salinity, drinkable water. The unfiltered BWRO concentrate from the BWRO plant 500 may be provided to the PRO plant 900 as a feed solution.

PRO facility 900 performs a pressure delay osmosis process with respect to the SWRO concentrated water (draw solution) supplied from the second pressure exchange device 300 and the BWRO concentrated water (supply solution) supplied from the BWRO facility 500 can do. For example, in the PRO facility 900 , they meet each other with the PRO membrane interposed therebetween, and water flows out from the feed solution to the draw solution due to the salinity difference between the draw solution and the feed solution, so that the volume flow rate of the draw solution can be increased.

Accordingly, the extracted water exiting from the BWRO concentrated water through the PRO membrane in the PRO facility 900 has very low salinity, and mixed Gibbs free energy is generated by the difference in salinity between the two solutions while being mixed with the SWRO concentrated water. The pressure of the SWRO brine is maintained by the resulting mixed Gibbs free energy.

The volume flow rate of the PRO produced water discharged from the PRO facility 900 is increased compared to the SWRO concentrated water, while the pressure is relatively maintained. PRO produced water flows into the first pressure exchange device 200 after being discharged from the PRO facility 900 , and transfers the pressure to the seawater supplied from the pretreatment facility 100 to pressurize the seawater. After transferring the pressure to the seawater, the PRO produced water may have a lower pressure, and may undergo a separate treatment or process after being discharged from the first pressure exchange device 200 .

On the other hand, BWRO concentrated water loses extraction water while going through the pressure delay osmosis process in the PRO facility 900, and the concentrated brackish water is transported to an external storage tank as PRO concentrated water and stored, or a separate post-treatment or It can be used through the process.

On the other hand, in the case of the above-described first embodiment, since the PRO produced water discharged from the first pressure exchange device 200 is discharged to the outside of the system, the recovery rate of the product water recovered from the entire system may be deteriorated. In order to improve the problems of the first embodiment, a second embodiment to be described later may be proposed.

2 is a block diagram illustrating a complex desalination system according to a second embodiment of the present invention.

Referring to FIG. 2 , the combined desalination system 1 according to the second embodiment of the present invention includes a pretreatment facility 100 , a first pressure exchange device 200 , a second pressure exchange device 300 , and a SWRO facility 400 . ), the BWRO facility 500 , the RO facility 600 , and the PRO facility 900 . This second embodiment is different from the first embodiment in that the PRO produced water discharged from the first pressure exchange device 200 is filtered through the RO facility 600, so the difference will be mainly explained. , the same description and reference numerals will be used.

The RO facility 600 may receive PRO production water from the first pressure exchange device 200 . At this time, PRO production water may be pressurized through the third pressure exchange device 610 and the fifth pressure control device 850 . The third pressure exchanging device 610 and the fifth pressure adjusting device 850 may be understood as configurations corresponding to the pressure exchanging device and the pressure adjusting device described in the first embodiment.

The RO facility 600 may produce product water by filtering the supplied PRO production water through a reverse osmosis membrane for salt. The RO facility 600 may deliver unfiltered RO concentrated water through the reverse osmosis membrane to the third pressure exchanger 610 .

As such, in the second embodiment, by filtering the PRO production water discharged from the first pressure exchange device 200 again through the RO facility 600, the recovery rate of the product water recovered from the system can be improved, 1 It is possible to reduce the discharge amount of PRO production water discharged from the pressure exchange device 200 to the outside of the system.

In the case of the first embodiment and the second embodiment described above, as the operating time of the PRO equipment 900 increases, the filtration performance of the PRO equipment 900 may be lowered. Since the flow rate of the PRO produced water is reduced, the flow rate of PRO produced water supplied from the PRO facility 900 to the first pressure exchange device 200 and the pretreatment facility 100 are supplied to the first pressure exchange device 200 . There may be differences in the flow rate of seawater. In other words, a change may be caused in a flow rate ratio between the feed solution and the draw solution supplied to the first pressure exchange device 200 .

In order to improve the problems of the first and second embodiments, the third to eighth embodiments described below may be proposed. The third to eighth embodiments to be described later have an inlet solution ( Feed Solution) and the draw solution (Draw Solution) there is a difference in that the flow ratio can be kept constant, so the difference will be mainly described, and the same description and reference numerals will be used.

3 is a block diagram illustrating a complex desalination system according to a third embodiment of the present invention.

Referring to FIG. 3 , in the combined desalination system 1 according to the third embodiment of the present invention, the inlet pipe 711 of the first pressure exchange device 200 and the outlet of the first pressure exchange device 200 . The side pipe 712 may be connected through the first bypass pipe 710 .

For example, when the flow rate of PRO production water supplied to the first pressure exchange device 200 is greater than the flow rate of seawater flowing into the pretreatment facility 100 , the first bypass pipe 710 is the first pressure exchange device 200 . ), by bypassing at least a part of the PRO produced water supplied to the inlet side of the first pressure exchange device 200 to the outlet side of the first pressure exchange device 200, the flow rate of the PRO production water supplied to the first pressure exchange device 200, and the first pressure exchange The flow rate of seawater supplied to the device 200 may be maintained the same.

As an example, the flow rate of PRO production water supplied from the PRO facility 900 to the first pressure exchange device 200 is 488 m ³ /day, and the pretreatment facility 100 is supplied to the first pressure exchange device 200 . When the flow rate of seawater is 444 m ³ /day, the first bypass pipe 710 converts the PRO production water flow rate of 44 m ³ /day from the PRO production water flow rate ^{of 488 m 3 /day to the first pressure exchange device (} 200) may be guided to the outlet side pipe 712.

In this way, when the flow rate of the PRO production water supplied to the first pressure exchange device 200 is greater than the flow rate of the seawater flowing into the pretreatment facility 100, in the third embodiment, the first bypass pipe 710 The flow rate of PRO production water supplied from the PRO facility 900 to the first pressure exchange device 200 is equal to the flow rate of the seawater supplied from the pretreatment facility 100 to the first pressure exchange device 200 by using By maintaining this to increase the energy change efficiency of the first pressure exchange device 200, it is possible to maximize the energy recovery efficiency of the present invention.

4 is a block diagram illustrating a complex desalination system according to a fourth embodiment of the present invention.

Referring to FIG. 4 , in the combined desalination system 1 according to the fourth embodiment of the present invention, the inlet pipe 711 of the first pressure exchanging device 200 and the outlet pipe of the PRO facility 900 ( 721 may be connected through the second bypass pipe 720 .

For example, in the fourth embodiment, the second bypass pipe 720 bypasses a portion of the PRO concentrated water discharged from the PRO facility 900 to the inlet pipe 711 of the first pressure exchange device 200 . , the flow rate of PRO production water supplied to the first pressure exchange device 200 and the flow rate of seawater supplied to the first pressure exchange device 200 can be kept the same.

For example, the PRO concentrated water discharged from the PRO facility 900 is 73 m ³ /day, and the PRO production water supplied from the PRO facility 900 to the first pressure exchange device 200 is 416 m ³ /day, and the first When the flow rate of seawater supplied to the pressure exchanger 200 is 444 m ³ /day, the second bypass pipe 720 is 73 m ³ /day of PRO concentrated water flow rate, 28 m ³ /day of PRO concentration. The water flow rate may be guided to the outlet side pipe 712 of the first pressure exchange device 200 .

As such, in the fourth embodiment, using the second bypass pipe 720, the flow rate of PRO production water supplied from the PRO facility 900 to the first pressure exchange device 200, and the pretreatment facility 100 It is possible to maintain the same flow rate of seawater supplied to the first pressure exchange device 200 .

5 is a block diagram illustrating a complex desalination system according to a fifth embodiment of the present invention.

Referring to FIG. 5 , in the combined desalination system 1 according to the fifth embodiment of the present invention, the outlet pipe 731 of the pretreatment facility 100 and the inlet pipe 732 of the SWRO facility 400 are It may be connected through a third bypass pipe 730 . The third bypass pipe 730 may be provided with a sixth pressure regulating device 870 , for example, a booster pump.

For example, in the fifth embodiment, the third bypass pipe 730 bypasses some of the seawater treated in the pretreatment facility 100 to the inlet side of the SWRO facility 400, and then the sixth pressure control device 870: booster pump) and the first pressure regulating device (810: high pressure pump) by pressurizing, the flow rate of PRO production water supplied to the first pressure exchange device 200, and the seawater supplied to the first pressure exchange device 200 The flow rates can be kept equal to each other.

For example, the flow rate of PRO production water supplied from the PRO facility 900 to the first pressure exchange device 200 is 416 m ³ /day, and the flow rate of seawater discharged from the pretreatment facility 100 is 444 m ³ /day In the case of , the third bypass pipe 730 may guide a seawater flow rate of 28 m ^{3 /day of the seawater flow rate of 444 m 3} /day to the inlet pipe 732 of the SWRO facility 400 .

As such, in the fifth embodiment, using the third bypass pipe 730 , the flow rate of PRO production water supplied from the PRO facility 900 to the first pressure exchange device 200 , and the pretreatment facility 100 in the It is possible to maintain the same flow rate of seawater supplied to the first pressure exchange device 200 .

6 is a block diagram illustrating a complex desalination system according to a sixth embodiment of the present invention.

Referring to FIG. 6 , in the combined desalination system 1 according to the sixth embodiment of the present invention, the outlet pipe 731 of the pretreatment facility 100 and the inlet pipe 732 of the SWRO facility 400 are It may be connected through the third bypass pipe 730 , and the outlet side pipe 712 of the first pressure exchange device 200 may be connected to the pretreatment facility 100 . A sixth pressure regulating device 870 may be provided in the third bypass pipe 730 .

For example, by supplying all of the PRO produced water discharged from the outlet side of the first pressure exchange device 200 to the pre-treatment facility 100, it is possible to significantly reduce the amount of seawater intake and concentrated water discharge. The third bypass pipe 730 bypasses and pressurizes the mixed water treated in the pretreatment facility 100 to the SWRO facility 400 inlet side, thereby increasing the flow rate of PRO produced water supplied to the first pressure exchange device 200 and , it is possible to maintain the same flow rate of seawater supplied to the first pressure exchange device 200 with each other.

As an example, when the flow rate at the outlet side of the pretreatment facility 100 is 444 m ^{3 /day, all the flow rates (416 m 3} /day) of the PRO produced water discharged from the outlet side of the first pressure exchange device 200 (416 m 3 /day) 100), and due to this, seawater can be ^{withdrawn only by 28 m 3} /day, and the discharged concentrated water can be reduced by ^{416 m 3 /day.} Of the seawater flow rate (444 m ³ /day) ^{discharged from the pretreatment facility 100 , the seawater flow rate of 28 m 3} /day is the inlet pipe 732 of the SWRO facility 400 through the third bypass pipe 730 . ) can be guided.

In this way, by supplying all of the PRO produced water discharged from the outlet side of the first pressure exchange device 200 to the pretreatment facility 100, the amount of seawater intake can be reduced, and the concentrated water discharged can also be reduced.

7 is a block diagram illustrating a complex desalination system according to a seventh embodiment of the present invention.

Referring to FIG. 7 , in the combined desalination system 1 according to the seventh embodiment of the present invention, the outlet pipe 721 of the PRO facility 900 may be connected to the pretreatment facility 100 .

For example, when the flow rate at the outlet side of the pretreatment facility 100 is 444 m ^{3 /day, all the flow rates (73 m 3} /day) of the PRO concentrated water discharged from the outlet side of the PRO facility 900 flows into the pretreatment facility 100 . As a result, seawater can be ^{withdrawn by only 404 m 3} /day and the discharged concentrated water is ^{reduced by 73 m 3} /day. In addition, since the mixed water has a lower TDS than seawater, the energy consumption of the entire process is reduced.

As an example, when the flow rate at the outlet side of the pretreatment facility 100 is 444 m ^{3 /day, all the flow rates (73 m 3} /day) of the PRO concentrated water discharged from the outlet side of the PRO facility 900 are to the pretreatment facility 100 . can enter, and as a result, seawater can be ^{withdrawn by only 404 m 3} /day and the discharged concentrated water is ^{reduced by 416 m 3} /day.

8 is a block diagram illustrating a complex desalination system according to an eighth embodiment of the present invention.

Referring to FIG. 8 , in the combined desalination system 1 according to the eighth embodiment of the present invention, the outlet pipe 721 of the PRO facility 900 may be connected to the pretreatment facility 100 , and the first pressure exchange The outlet pipe 712 of the apparatus 200 and the pretreatment facility 100 may be connected to each other through the fourth bypass pipe 740 , and the outlet pipe 731 of the pretreatment facility 100 and the SWRO facility 400 may be connected to each other. ) of the inlet side pipe 732 may be connected through the third bypass pipe 730 .

For example, in the eighth embodiment, it is possible to guide all the flow rates of the PRO concentrated water discharged from the outlet side of the PRO facility 900 to the pretreatment facility 100, and the fourth bypass pipe 740 is the first pressure exchange device. Some of the PRO production water discharged from the outlet side of 200 may be bypassed to the pretreatment facility 100 .

In addition, the third bypass pipe 730 bypasses some of the seawater discharged from the pretreatment facility 100 to the inlet side of the SWRO facility 400 and pressurizes it, thereby producing PRO supplied to the first pressure exchange device 200 . The flow rate of water and the flow rate of seawater supplied to the first pressure exchanging device 200 may be maintained to be the same.

For example, if the flow rate at the outlet side of the pretreatment facility 100 is 444 m ^{3 /day, all the flow rates (73 m 3} /day) of the PRO concentrated water discharged from the outlet side of the PRO facility 900 are the pretreatment facility 100 ^{A portion of the flow rate (220m 3} /day) of the PRO produced water discharged from the outlet side of the first pressure exchange device 200 through the fourth bypass pipe 740 is guided to the pretreatment facility 100 . As a result, seawater can be ^{withdrawn by only 151 m 3} /day and the discharged concentrated water is ^{reduced by 493 m 3} /day.

^{In addition, among the flow rate (444 m 3} /day) of seawater discharged from the pretreatment facility 100 , ^{the seawater flow rate of 28 m 3} /day is the inlet pipe of the SWRO facility 400 through the third bypass pipe 730 . (732).

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, those of ordinary skill in the art to which the present invention pertains can realize that the present invention can be embodied in other specific forms without changing its technical spirit or essential features. you will be able to understand For example, those skilled in the art may change the material, size, etc. of each component according to the field of application, or combine or substitute the embodiments in a form not clearly disclosed in the embodiment of the present invention, but this is also the present invention that does not exceed the scope of Therefore, the embodiments described above should not be understood as illustrative and limiting in all respects, and it should be said that these modified embodiments are included in the technical spirit described in the claims of the present invention.

100: pretreatment facility 110: DAF device
120: UF device 200: first pressure exchange device
300: second pressure exchange device 400: SWRO equipment
500: BWRO equipment 600: RO equipment
710: first bypass tube 720: second bypass tube
730: third bypass tube 740: fourth bypass tube
810: first pressure regulating device 820: second pressure regulating device
830: third pressure control device

Claims (8)

pre-treatment facility for pre-filtering seawater;
a first pressure exchanging device for increasing the pressure by receiving seawater from the pretreatment facility;
a second pressure exchanging device that receives at least a portion of the seawater supplied from the first pressure exchanging device to increase the pressure;
a first pressure control device for pressurizing the remaining part of the seawater supplied from the first pressure exchange device;
a second pressure regulating device for pressurizing the seawater supplied from the second pressure exchanging device;
The seawater supplied from the first pressure control device and the second pressure control device is used to produce salt-filtered product water through a seawater desalination reverse osmosis membrane, and the unfiltered SWRO concentrated water is delivered to the second pressure exchange device. SWRO equipment;
BWRO facility that receives effluent from sewage treatment plant, filters it through brackish water desalination reverse osmosis membrane, and discharges unfiltered BWRO concentrated water; and
For the SWRO concentrated water supplied from the second pressure exchanging device and the BWRO concentrated water supplied from the BWRO facility, a PRO facility for supplying the filtered PRO production water to the first pressure exchanging device by performing a pressure delay osmosis process containing,
Seawater desalination A complex desalination system using pressure-delayed osmosis technology. The method of claim 1,
The flow rate of the PRO produced water supplied to the first pressure exchange device and the flow rate of the seawater supplied to the first pressure exchange device are controlled to be kept the same with each other,
Seawater desalination A complex desalination system using pressure-delayed osmosis technology. The method of claim 1,
Further comprising an RO facility that receives the PRO-produced water from the first pressure exchange device, and filters the supplied PRO-produced water with salt through a reverse osmosis membrane to produce product water,
Seawater desalination A complex desalination system using pressure-delayed osmosis technology. 2. The method of claim 1
Further comprising a first bypass pipe for guiding at least a portion of the PRO produced water supplied to the inlet side of the first pressure exchange device to the outlet side of the first pressure exchange device,
Seawater desalination A complex desalination system using pressure-delayed osmosis technology. 2. The method of claim 1
Further comprising a second bypass pipe for guiding at least a portion of the PRO concentrated water discharged from the PRO facility to the first pressure exchange device,
Seawater desalination A complex desalination system using pressure-delayed osmosis technology. The method of claim 1,
Further comprising a third bypass pipe for guiding at least a portion of the seawater discharged from the pretreatment facility to the SWRO facility,
Seawater desalination A complex desalination system using pressure-delayed osmosis technology. 7. The method of claim 6,
Further comprising a fourth bypass pipe for guiding at least a portion of the PRO produced water discharged from the first pressure exchange device to the pretreatment facility,
Seawater desalination A complex desalination system using pressure-delayed osmosis technology. 8. The method of claim 1 or 7
The PRO concentrated water discharged from the PRO facility is supplied to the pre-treatment facility,
Seawater desalination A complex desalination system using pressure-delayed osmosis technology.

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