KR102423512B1 - Underwater plasma discharge ultrafilation apparatus and seawater desalination system comprising the same - Google Patents

Abstract

The underwater plasma discharge ultrafiltration device of the present invention includes a plasma reactor in which the upper surface is opened and seawater is stored; a seawater supply pump for supplying seawater to the reaction tank; a plurality of discharge electrodes mounted on one surface of the reaction tank and for discharging plasma to the seawater of the reaction tank; a ground electrode installed on the other surface of the reactor; a high voltage power supply supplying high voltage power to the plurality of discharge electrodes; and an ultrafiltration membrane unit immersed in the seawater of the reaction tank to filter foreign substances in the seawater.

Description

Underwater plasma discharge ultrafiltration apparatus and seawater desalination system including the same

The present invention relates to an underwater plasma discharge ultrafiltration device and a seawater desalination system comprising the same.

Seawater desalination technology is a representative technology field that can solve domestic water demand and provide technology for securing alternative water resources, while also pioneering overseas markets and creating high value.

According to "Water Reuse Markets 2005-2015: A Global Assessment & Forecast" of Global Water Intelligence (GWI), the world's most authoritative magazine in the field of water, the seawater desalination market is currently at a size of 3 million tons/day. and is expected to grow to 6.2 million tons/day in 2015.

In addition, seawater desalination technology is becoming a solution to providing alternative water resources to water-stressed areas in Korea. In particular, it is possible to reduce costs and improve environmental problems by replacing the method of securing water resources through dam construction, which is causing controversy over environmental issues. Therefore, domestic demand is expected to increase continuously in the future.

As the seawater desalination method, there are evaporation and reverse osmosis methods. Since reverse osmosis requires relatively less energy to produce a unit volume of water compared to evaporation, reverse osmosis is widely used in recent years.

The reverse osmosis method uses a polymer separation membrane (reverse osmosis membrane) to separate the components contained in seawater or brackish water into production water and concentrated water. do.

In the seawater desalination pretreatment process, various processes are applied depending on the characteristics and treatment purpose of the seawater, and the most commonly applied processes are Dissolved Air Flotation (DAF), Dual Media Filtration (DMF), and membrane filtration processes. have.

In the existing seawater desalination process, the DMF process has been widely applied for reasons such as initial facility cost, but considering the effect on the reverse osmosis process and the water quality aspect, the introduction of the membrane filtration process is gradually increasing.

The membrane filtration process has shown many strengths in terms of initial facility cost and maintenance due to the stable maintenance of treated water quality and the steady efforts of membrane manufacturers, so the trend of increase is steadily increasing. However, the membrane filtration process also has problems as the backwash cycle is shortened and the membrane life is shortened due to contamination formed on the membrane surface due to continuous operation. There is a problem that causes bio fouling. Therefore, in order to solve these problems, the introduction of the dissolved air flotation device is expanding.

The dissolved air flotation type pretreatment device for seawater desalination according to the prior art immerses a plurality of ultrafiltration membranes (UF) in seawater of a membrane separation tank and supplies aeration into the seawater to remove foreign substances adhering to the ultrafiltration membrane. Periodic backwashing is required.

However, in the case of the immersion-type UF pretreatment process of the prior art, there was a problem in that a lot of energy required for aeration (supply air, diffuser air, underwater aeration) is required. In addition, there was a problem in that biofouling occurs in the ultrafiltration membrane, which causes concentration polarization, and thus causes a pressure increase.

Republic of Korea Patent Publication No. 10-1277199

The present invention provides a large-capacity underwater plasma discharge ultrafiltration device capable of discharging plasma in water with low energy to reduce organic matter and biofouling in seawater, thereby extending the lifespan of a filtration membrane and reducing chemical costs, and seawater desalination including the same The purpose is to provide a system.

Underwater plasma discharge ultrafiltration device of the present invention for achieving the above object, the upper surface is open plasma reactor in which seawater is stored; a seawater supply pump for supplying seawater to the reaction tank; a plurality of discharge electrodes mounted on one surface of the reaction tank and for discharging plasma to the seawater of the reaction tank; a ground electrode installed on the other surface of the reactor; a high voltage power supply supplying high voltage power to the plurality of discharge electrodes; and an ultrafiltration membrane unit immersed in the seawater of the reaction tank to filter foreign substances in the seawater.

The reactor may further include a cover member coupled to selectively open and close the open upper surface of the reactor, the plurality of discharge electrodes may be mounted on a bottom surface of the reactor, and the ground electrode may be installed on the cover member.

The plurality of discharge electrodes may be arranged to form a plurality of rows and columns on the bottom surface of the reaction tank.

The ultrafiltration membrane unit may be formed in a rectangular parallelepiped shape by vertically stacking a plurality of ultrafiltration membranes.

The ultrafiltration membrane unit may include a plurality of vertically stacked ultrafiltration membranes, and a pair of support plates respectively coupled to upper ends and lower ends of the plurality of ultrafiltration membranes.

It may further include a sludge pump connected to the lower surface of the reaction tank for discharging the sludge generated in the reaction tank.

The seawater desalination system of the present invention includes: a water intake device for water intake; a pre-treatment device for filtering impurities contained in seawater; a high-pressure pump for supplying pretreated seawater at high pressure; and a reverse osmosis device for producing fresh water by reverse osmosis from high-pressure seawater, wherein the pretreatment device includes an underwater plasma discharge ultrafiltration device, wherein the underwater plasma discharge ultrafiltration device has an open top surface to store seawater being a plasma reactor; a seawater supply pump for supplying seawater to the reaction tank; a plurality of discharge electrodes mounted on one surface of the reaction tank and for discharging plasma to the seawater of the reaction tank; a ground electrode installed on the other surface of the reactor; a high voltage power supply supplying high voltage power to the plurality of discharge electrodes; and an ultrafiltration membrane unit immersed in the seawater of the reaction tank to filter foreign substances in the seawater.

The underwater plasma discharge ultrafiltration device further includes a cover member coupled to selectively open and close the open upper surface of the reaction tank, the plurality of discharge electrodes are mounted on the bottom surface of the reaction tank, and the ground electrode is the cover member can be installed on

The plurality of discharge electrodes may be arranged to form a plurality of rows and columns on the bottom surface of the reaction tank.

The ultrafiltration membrane unit may be formed in a rectangular parallelepiped shape by vertically stacking a plurality of ultrafiltration membranes.

The ultrafiltration membrane unit may include a plurality of vertically stacked ultrafiltration membranes, and a pair of support plates respectively coupled to upper ends and lower ends of the plurality of ultrafiltration membranes.

The underwater plasma discharge ultrafiltration device may further include a sludge pump connected to the lower surface of the reaction tank to discharge sludge generated in the reaction tank.

According to the underwater plasma discharge ultrafiltration device of the present invention and the seawater desalination system including the same, there is no need for a separate backwashing system by washing the filtration membrane with microbubbles generated by discharging plasma in water with low energy, and OH radicals are generated By reducing organic matter and biofouling in seawater by ozone and the like, it is possible to extend the life of the filtration membrane and reduce the cost of chemicals.

1 is a schematic diagram showing a seawater desalination system according to an embodiment of the present invention.
Figure 2 is a schematic diagram showing an underwater plasma discharge ultrafiltration device according to an embodiment of the present invention.

Since the present invention can apply various transformations and can have various embodiments, specific embodiments are illustrated and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

The terms used in the present invention are only used to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present invention, terms such as 'comprise' or 'have' are intended to designate that the features, numbers, steps, operations, components, parts, or combinations thereof described in the specification exist, and one or more other features It is to be understood that this does not preclude the possibility of the presence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. At this time, it should be noted that in the accompanying drawings, the same components are denoted by the same reference numerals as much as possible. In addition, detailed descriptions of well-known functions and configurations that may obscure the gist of the present invention will be omitted. For the same reason, some components are exaggerated, omitted, or schematically illustrated in the accompanying drawings.

1 is a schematic diagram showing a seawater desalination system according to an embodiment of the present invention.

The seawater desalination system of the present invention may include a water intake device 10 , a pre-treatment device 20 , a high-pressure pump 30 , a reverse osmosis device 40 , and a post-treatment device 50 .

The water intake device 10 is an intake device that takes in seawater, and draws seawater from the sea to a predetermined flow rate and pressure.

The pretreatment device 20 takes in seawater and filters impurities contained in the introduced water.

The pretreatment of the pretreatment device 20 includes precipitation treatment, filtration treatment, and chemical treatment. Sedimentation treatment and filtration treatment are carried out to prevent contamination of the membrane by removing suspended substances contained in the raw water. Chemical treatment is performed to maintain the performance of the reverse osmosis membrane to the maximum by controlling the quality of the feed water. In addition, such pretreatment is absolutely necessary in order to prevent contamination of the reverse osmosis membrane and to exhibit high performance.

In particular, an underwater plasma discharge ultrafiltration device 100 that discharges underwater plasma in a state in which the ultrafiltration membrane unit is immersed in seawater of a reaction tank as a pretreatment may be used. According to the underwater plasma discharge ultrafiltration device 100, glass management costs can be reduced compared to the existing DAF and DMF pretreatment facilities, and oxidizing substances such as microbubbles and ozone generated by plasma discharge suppress biofouling Thus, it is possible to reduce the chemical cost and extend the life of the filtration membrane. The specific configuration of the underwater plasma discharge ultrafiltration device 100 will be described later.

The high-pressure pump 30 introduces the pretreated seawater into the reverse osmosis device 40 at a high pressure.

The reverse osmosis device 40 supplies the water filtered by the cartridge filter 30 by the high-pressure pump 30 to produce fresh water by reverse osmosis. Reverse osmosis (RO) is a phenomenon in which a pure solvent escapes from a solution through a semipermeable membrane when a pressure higher than the osmotic pressure is applied. Reverse osmosis can be used to desalinate seawater. In order to cause reverse osmosis to occur, a high-pressure pump 30 for supplying filtered water at a pressure higher than the osmotic pressure of seawater before the reverse osmosis device 40 is disposed.

When passing through the reverse osmosis device 40, the supplied seawater becomes high salt water (concentrated water), and the water that has passed through the reverse osmosis membrane becomes treated water.

A post-treatment device 50 for re-treating the filtered treated water may be disposed behind the reverse osmosis device 40 . The post-treatment device 50 may perform pH adjustment, mineral injection, chlorine disinfection, and the like.

In addition, a device (not shown) for treating the high salt water generated in the reverse osmosis device 40 to waste water may be further provided.

Figure 2 is a schematic diagram showing an underwater plasma discharge ultrafiltration device according to an embodiment of the present invention.

The underwater plasma discharge ultrafiltration device 100 of the present invention includes a plasma reactor 120, a seawater supply pump 110, a plurality of discharge electrodes 130, a ground electrode 140, a high voltage power supply unit 160, and an ultrafiltration membrane. unit 180 .

The plasma reactor 120 may be formed in the form of a rectangular parallelepiped water tank with an open upper surface. An inlet is formed at one side of the plasma reactor 120 and an inlet pipe is connected to the inlet, so that seawater can be introduced. An outlet is formed at the other side of the plasma reactor 120 , and an outlet pipe is connected to the outlet, so that treated water can flow out. The inlet and outlet may be formed on the upper side of the plasma reactor 120 , but the inlet pipe and the outlet pipe may be connected to the open upper surface of the plasma reactor 120 .

The seawater supply pump 110 is connected to the inlet pipe to supply seawater to the plasma reactor 120 . The seawater supply pump 110 may supply seawater at an appropriate speed so that the seawater sufficiently passes through the ultrafiltration membrane in the plasma reactor 120 .

The plurality of discharge electrodes 130 are mounted on one surface of the plasma reactor 120 and discharge plasma with seawater of the reactor.

The ground electrode 140 is installed on the other surface of the plasma reactor 120 so that the plasma is discharged in water from the plurality of discharge electrodes 130 toward the ground electrode 140 .

The high voltage power supply 160 may be connected to each of the plurality of discharge electrodes 130 to supply high voltage pulse power. The high voltage power supply 160 may include a power meter to control power supply while sensing power supplied from the power supply.

The ultrafiltration membrane unit 180 is immersed in the seawater of the plasma reactor 120 to filter foreign substances in the seawater. Ultrafiltration membrane (UF membrane: UltraFiltration Membrane) is a filtration membrane that can separate extremely fine particles or dissolved molecules from a fluid. In general, the asymmetric structure is composed of a surface active layer having a selective separation function and a porous support layer. It is possible to remove bacteria, colloids, proteins, polymers, organic matter, etc. with a molecular weight of 50 to 300,000 through the filtration action of 0.01~0.001㎛ which is difficult to observe even with a microscope. Ultrafiltration membranes can be used multiple times by washing. In the seawater pretreatment process, it is common to use a plurality of ultrafiltration membranes stacked. That is, a plurality of stacked ultrafiltration membranes constitute the ultrafiltration membrane unit 180 .

In the present invention, the ultrafiltration membrane unit 180 may be immersed in the seawater of the plasma reactor 120 to filter foreign substances including organic matter from the seawater. While the seawater flows from the inlet to the outlet of the plasma reactor 120 , most of the seawater may pass through the ultrafiltration membrane unit 180 . The ultrafiltration membrane unit 180 may be configured by coupling the upper and lower ends of a plurality of vertically stacked ultrafiltration membranes to a support plate. 2, two or more ultrafiltration membrane units 180 may be arranged in series. Although not shown, the support plate of the ultrafiltration membrane unit 180 may be fixed at a position submerged in seawater inside the plasma reactor 120 by a wire or a bar or frame.

The underwater plasma discharge ultrafiltration device 100 may further include a cover member 150 coupled to selectively open and close the open upper surface of the plasma reactor 120 . That is, the plasma reactor 120 is formed in the form of a rectangular parallelepiped box with an open upper surface, and the cover member 150 in the form of a rectangular plate may be rotated or selectively coupled to the upper edge of the plasma reactor 120 .

The plurality of discharge electrodes 130 may be mounted on the bottom surface of the plasma reactor 120 , and the ground electrode 140 may be installed on the cover member 150 . Electrode holes in which a plurality of discharge electrodes 130 are installed are formed on the bottom surface of the plasma reactor 120 , and wires from the high voltage power supply unit 160 may be connected in parallel to each discharge electrode 130 . The plurality of discharge electrodes 130 may be arranged to form a plurality of rows and columns on the bottom surface of the plasma reactor 120 .

The ground electrode 140 may be attached to or coupled to the lower surface of the cover member 150 . When high voltage pulse power is supplied to the plurality of discharge electrodes 130 , plasma is discharged in water from the plurality of discharge electrodes 130 toward the ground electrode 140 , and accordingly, micro bubbles and OH radicals and Ozone oxide and the like are generated. The generated microbubbles have an effect of cleaning the ultrafiltration membrane, and the generated OH radicals and ozone oxides have an effect of inhibiting the formation of biofouling. Therefore, the ultrafiltration membrane unit 180 does not need to be periodically backwashed by a separate backwashing system.

The ultrafiltration membrane unit 180 may be formed in a rectangular parallelepiped shape by vertically stacking a plurality of ultrafiltration membranes in the form of a rectangular sheet. Although the size of the ultrafiltration membrane unit 180 is shown to be much smaller than that of the plasma reactor 120 in FIG. 2 , in reality, the area or volume of the ultrafiltration membrane unit 180 is close to the area or volume of the plasma reactor 120 . It is preferably formed so that most of the seawater passes through the ultrafiltration membrane unit 180 .

Meanwhile, the underwater plasma discharge ultrafiltration device 100 may further include a sludge pump 170 connected to the lower surface of the plasma reactor 120 to discharge sludge generated in the reactor. When an underwater plasma discharge is applied to the seawater in the plasma reactor 120, the microbubbles are cleaned of the ultrafiltration membrane to remove foreign substances and float in the seawater, or heavy ones of them can sink. In addition, OH radicals and ozone oxides may sink into seawater as organic matter is generated in the process of suppressing biofouling and become sludge together with foreign substances. The sludge pump 170 may be connected to the bottom surface of the plasma reactor 120 to pump and discharge sludge containing about 2% of moisture.

According to the present invention, there is no need for a separate backwashing system by washing the filtration membrane with microbubbles generated by discharging plasma in water with low energy. It can extend the life of the drug and reduce drug costs.

In the above, an embodiment of the present invention has been described, but those of ordinary skill in the art can add, change, delete or add components within the scope that does not depart from the spirit of the present invention described in the claims. Various modifications and changes of the present invention will be possible by this, and this will also be included within the scope of the present invention.

10: water intake device 20: pretreatment device
25: filtration device 30: high pressure pump
40: reverse osmosis device 50: post-processing device
100: underwater plasma discharge ultrafiltration device
110: seawater supply pump 120: plasma reactor
130: discharge electrode 140: ground electrode
150: cover member 160: high voltage power supply device
170: sludge pump 180: ultrafiltration membrane unit

Claims (12)

Plasma reactor in which the upper surface is opened to store seawater;
a cover member coupled to selectively open and close the open upper surface of the reactor;
a seawater supply pump for supplying seawater to the reaction tank;
a plurality of discharge electrodes mounted on the bottom surface of the reaction tank and discharging plasma to the seawater of the reaction tank;
a ground electrode installed on the cover member;
a high voltage power supply supplying high voltage power to the plurality of discharge electrodes; and
An ultrafiltration membrane unit immersed in the seawater of the reaction tank to filter foreign substances in the seawater,
The ultrafiltration membrane unit is an underwater plasma discharge ultrafiltration device, characterized in that it comprises a plurality of ultrafiltration membranes vertically stacked and formed in a rectangular parallelepiped shape, and a pair of support plates respectively coupled to upper and lower ends of the plurality of ultrafiltration membranes. delete The method of claim 1,
The plurality of discharge electrodes is an underwater plasma discharge ultrafiltration device, characterized in that arranged to form a plurality of rows and columns on the bottom surface of the reaction tank. delete delete 4. The method of claim 1 or 3,
Underwater plasma discharge ultrafiltration device, characterized in that it further comprises a sludge pump connected to the lower surface of the reaction tank for discharging the sludge generated in the reaction tank. water intake device for water intake;
a pretreatment device for filtering impurities contained in seawater;
a high-pressure pump for supplying pretreated seawater at high pressure; and
A reverse osmosis device for producing fresh water by reverse osmosis from high-pressure seawater,
The pretreatment device includes an underwater plasma discharge ultrafiltration device,
The underwater plasma discharge ultrafiltration device,
Plasma reactor in which the upper surface is opened to store seawater;
a cover member coupled to selectively open and close the open upper surface of the reactor;
a seawater supply pump for supplying seawater to the reaction tank;
a plurality of discharge electrodes mounted on the bottom surface of the reaction tank and for discharging plasma to the seawater of the reaction tank;
a ground electrode installed on the cover member;
a high voltage power supply supplying high voltage power to the plurality of discharge electrodes; and
An ultrafiltration membrane unit immersed in the seawater of the reaction tank to filter foreign substances in the seawater,
The ultrafiltration membrane unit is a seawater desalination system, characterized in that it comprises a plurality of ultrafiltration membranes in the form of a rectangular parallelepiped stacked vertically, and a pair of support plates respectively coupled to the top and bottom of the plurality of ultrafiltration membranes. delete 8. The method of claim 7,
The plurality of discharge electrodes are seawater desalination system, characterized in that arranged to form a plurality of rows and columns on the bottom surface of the reaction tank. delete delete 10. The method of claim 7 or 9,
The underwater plasma discharge ultrafiltration device is a seawater desalination system, characterized in that it further comprises a sludge pump connected to the lower surface of the reaction tank for discharging the sludge generated in the reaction tank.

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