KR100796561B1 - Deionized water system with membrabe separation technology for power plant - Google Patents

Abstract

A method for preparing deionized water for a power plant is provided to remove an inorganic material and an organic material contained in raw water without chemicals and recycle backwash wastewater, by using backwash microfiltration or ultrafiltration membrane. Raw water supplied from a raw water collection bath(10) is passed through a press type backwash microfiltration or ultrafiltration membrane(30) or an immersion type backwash microfiltration or ultrafiltration membrane(40), and transported to a pretreatment water collection bath(50). If a pressure at a surface of the backwash microfiltration or ultrafiltration membrane is increased due to external particles, a backwash pump(52) separates the external particles precipitated on the surface of the membrane by automatically shutting off the input of raw water and blowing water and compressed air oppositely to the flow of the raw water. Backwash wastewater, which is generated during backwash by the backwash membrane, is passed through a pore control type fibrous filter or a press type filter press to obtain filtered water, and the filter water is transported to the raw water collection bath.

Description

Deionized Water System with Membrabe Separation Technology for Power plant}

1 is a block diagram showing a pure manufacturing system according to the present invention,

Figure 2 (a), (b) is a schematic diagram showing an operating state of the automatic filter according to the present invention.

Explanation of symbols on the main parts of the drawings

10: raw water collection tank 15: raw water pump

20: automatic washing filter

30: backwashing type precision or ultrafiltration membrane

40: backwash fine type or ultrafiltration membrane

50: pretreatment sump 51: microbial inhibitor

52: backwash pump 60: transfer pump

70: antioxidant 80: scale inhibitor

90: pH adjuster 100: precision filter

110: heat exchanger 120: high pressure pump

125: energy recovery device 130: nano filtration membrane separation device

140: primary reverse osmosis membrane separation device 150: primary permeate collection tank

155: alkali injection device 160: boost pump

170: secondary reverse osmosis membrane separation unit 180: secondary permeate collection tank

190: permeate feed pump 200: membrane contactor

210: electrical continuous pure water purification device 220: pure water collection tank

230: pure water transfer pump

The present invention relates to a pure water manufacturing method for a power plant using membrane separation, and more particularly, it is possible to remove inorganic substances and organic substances in water without using chemicals, and to reuse membrane backwashing water when backwashing filtration membranes. It relates to a pure water manufacturing method for power plants used.

Water is the source of life and one of the indispensable resources. However, due to the shortage of water due to the increase in population and rapid industrialization, the global water shortage is getting worse every year, and 40% of the world's population is suffering from drinking water shortage.

Recently, the World Bank (IBRD) warned that if the cause of international conflict in the 20th century was in oil, the cause of the 21st century would be water. This is due to a surge in local and regional ubiquity of water resources.

In other words, the world's population, which was 2.3 billion in 1940, more than doubled to 5.3 billion in 1990, and the population is expected to reach 8.3 billion by 2025. At present, Korea's water resources are 1,283mm with annual average 1.3 times larger than the global average (973mm), but due to the narrow land area and high population density, the per capita water resource precipitation is 2,705㎥ / year, the world average (22,096㎥ / year) Only 12% of the country is internationally classified as a water shortage country.

Excluding the loss due to evaporation from the total amount of annual precipitation, only 26% of the available water is available. In particular, the amount of groundwater available is estimated at 13.3 billion cubic meters per year, but as of 1999, its use is only 4 billion cubic meters per year. In addition, the difference in precipitation by year, region, and season is large and the change is large, which is very disadvantageous for water resource management.

Since the intake of natural river water is 50% out of the total use of water resources of 33.3 billion tons, it is urgent to develop a dam, improve the river safety and develop alternative water resources.

In addition, considering the deteriorating water resources environment, diversification of water sources should be promoted in case of emergencies such as water quality accidents or abnormal weather caused by El Niño.In such water resources development, water re-use aspects such as heavy water, groundwater development, seawater desalination, artificial rainfall It also uses rainwater, but it is also necessary to develop innovative technologies of existing water treatment methods.

The present invention is applied to the purified water (pure: Deionized Water or Pure Water) treatment technology used in the power plant and semiconductor industry, which is a pivotal industry in Korea, which has a lot of water use. This results in excessive facility costs, a large installation area, environmental pollution (wastewater and harmful gas generation) due to the use of a large amount of chemicals, and increased operation and maintenance costs for managing the required water quality. By using it, there is a problem of securing stable water resources and the complaints from neighboring residents.

Next, a pure water treatment facility installed in a conventional power plant will be described. The places where pure water is used include nuclear power generation, combined cycle power generation and cogeneration. The pure water treatment plant configuration of the power plant is as follows.

□ Pretreatment

The raw water (river, dam, groundwater, reservoir and river water) to be treated is collected and subjected to chemical treatment (neutralization, flocculation, sedimentation) or immediately through a pressure filtration system. It is a process to remove turbidity, color, and suspended solids.

□ Demineralization or Make-up process

The pre-treated raw water is filled with pressure vessels by using ion exchange method, and the raw water (river, dam, ground water, reservoir and river water) to be treated is dissolved in water. It is a method of removing ionic substances.

The ion exchange resin system used for power plant is mainly used to treat high alkalinity water and obtain low residual silica with strong acid cationic exchange resin tower-degassing tower-strong basic anion exchange resin tower (2B3T). This device is somewhat higher in facility cost than strong acid positive ion exchange resin tower-strong base anion exchange resin tower (2B2T) method, but it requires less operating cost and degassing method is not blower type but vacuum degassing device is used.

Strong acid positive ion exchange resin tower-Degassing column-In order to improve the purity of water treated with strong basic anion exchange resin tower (2B3T) method, a mixed-phase ion exchange resin tower was then installed.

The application of the ion exchange method may be used in combination of cocurrent, countercurrent and bottle countercurrent. There are several methods for arranging ion exchange resins in consideration of the ionic substances contained in raw water, facility costs, and operation costs.

1) In order to increase alkalinity and increase silica removal rate, it is composed of strong acid ion exchange resin, blower type degassing tower, and strong base ion resin tower.

2) In order to treat water containing high chloride or low alkalinity, it is composed of strong acidic ion exchange resin-weakly basic ion exchange resin-strong base ion exchange resin.

3) It is composed of strong acidic ion exchange resin-deaeration tower-weakly basic ion exchange resin-strong base ion exchange resin to treat high chloride or high alkalinity water.

4) To treat water with high concentration of alkalinity, hardness, chloride and sulfate, it is composed of weak acid ion exchange resin, strong acid ion exchange resin, degassing column, weak base ion exchange resin, and strong base ion exchange resin.

□ Posttreatment

In the desalination process using an ion exchange resin tower, the resistivity value of the treated water without soluble ions is raised to 200,000 to 1,000,000 m-cm (conductivity of 5 to 1 micromhos-cm) at 25 ° C. In order to remove the soluble silica, a mixed-phase ion exchange resin tower comprising a cation and an anion exchange resin is constituted.

In the conventional pure water treatment facility, the pretreatment process requires regular exchange of media in a rapid or slow filtration device, and there is a problem in that backwash waste water is generated while using a filtration device.

In addition, with the recent high industrial development, as the materials contained in raw water are diversified in complexity, there is a limit to the removal by ion exchange resin method, and the ion exchange resin device must be regenerated using hydrochloric acid or sodium hydroxide. There is a problem that secondary regeneration (pollution) waste water occurs.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to provide a pure water production method for power plants using membrane separation that can recycle backwash wastewater generated in a backwash filter.

Another object of the present invention is to provide a pure water production method for power plants using membrane separation that can remove the inorganic substances of raw water without using chemicals by using an electrical continuous pure water purification device.

The pure water manufacturing method for a power plant using the membrane separation of the present invention for achieving the above object, the pre-treatment step for removing turbidity, color, suspended matter contained in the raw water and the ionic substance dissolved in the pretreated raw water In the pure water production method used in the power plant consisting of a desalting step for removing the water and a post-treatment step for raising the specific resistance of the treated water from which the soluble ions are removed in the desalting step, in the pretreatment step, the raw water supplied from the raw water collection tank is After passing through an automatic washing filter, and passed through a backwash type microfiltration membrane or a backwash type ultrafiltration membrane to transfer to a pretreatment collection tank; When the pressure rises due to foreign matters on the surface of the backwash type microfiltration membrane or the backwash type ultrafiltration membrane, the inflow of raw water is automatically blocked, and the backwash that desorbs the foreign substances deposited on the surface of the membrane by blowing water and compressed air in the reverse of the processing flow The pump is operated; The backwash wastewater generated during the backwashing of the backwash type microfiltration membrane or the backwash type ultrafiltration membrane is passed through a pore-controlled fibrous filter or a pressurized filter press to transfer the water to the raw water collection tank for recycling. It consists of;

In this case, the raw water supplied from the raw water collection tank in the pretreatment step, a stainless steel basket is installed in the pressure vessel made of plastic or stainless steel, the cylinder is reciprocated into the basket and 0.1 ~ during the reciprocating motion of the cylinder After 40 mm of foreign matter passes through the automatic washing filter discharged through the flushing valve, it is preferable to pass through the backwash type microfiltration membrane or the backwash type ultrafiltration membrane.

In addition, 0.1 to 10 ppm of inorganic coagulant aluminum sulfate or polyaluminum chromide (PAC) is injected to improve turbidity and cohesion of suspended solids in the backwash wastewater flowing into the pore-controlled fibrous filter or pressurized filter press. In order to increase the cohesiveness and improve the water content, it is preferable to sequentially inject the organic polymer flocculant.

In addition, the desalting step, according to the type of raw water through the nanofiltration membrane separation apparatus or the first reverse osmosis membrane separation apparatus; Injecting sodium hydroxide from the alkali injection device to the permeated water passed through the nanofiltration membrane separation device or the first reverse osmosis membrane separation device to pass through the secondary reverse osmosis membrane separation device so that the pH of the permeate water is 7 or more.

In the post-treatment step, the positive and negative ion exchange membranes intersect between the two electrode bodies (Anode and Cathode) for supplying the DC power, and the layer layers are arranged, and the ion exchange resin is filled therebetween. It is preferable to include; passing through an electric continuous pure water purification device for desalting the ions contained in the trace amount.

Hereinafter, the configuration and operation of the preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram showing a pure water production system according to the present invention, Figure 2 (a), (b) is a schematic diagram showing the operating state of the automatic filter according to the present invention.

In the present invention, the substances contained in the raw water to be treated are as follows.

1) Inorganic matters

Cations: sodium (Na ⁺ ), magnesium (Mg ⁺² ), potassium (K ⁺ ), calcium (Ca ⁺² ), iron (Fe ⁺² ), zinc (Zn ⁺² ), copper (Cu ⁺² ) , Aluminum (Al ⁺³ ), manganese (Mn ⁺² ).

Negative ion current: chlorine ion (Cl ^-), sulfate ion (SO ₄ ^{2 -),} hydrogencarbonate ions (HCO ₃ ^-), nitrate ion (NO ₃ ^-), phosphate ion (PO ₄ ^-3), silica, such as a halogen compound.

2) Organic matters

Humic acid, fulvic acid, phenol, pesticides, trihalomethane and other organic solvents.

3) Microorganism

Fecal Streptococcus, Pseudomonas aeruginosa, Salmonella, Shigella, E. coli. Waterborne infectious bacteria, viruses, fungi, algae (green algae, diatoms, coccyx), protozoa (Geodia, Cryptosporodilop, etc.)

4) Gases

Oxygen (O ₂ ), Nitrogen (N ₂ ), Carbon Dioxide (CO ₂ ), Ammonia (NH ₃ )

5) Others

Suspended solids (SS), turbidity, total soluble solids (TDS), hydrogen ion concentration (pH), chemical oxygen demand (COD), biological oxygen demand (BOD), oil (Oil and Grease), etc.

These substances contained in the raw water vary depending on the type of raw water, especially when the seawater is used as raw water, the salt concentration is very high, and the natural waters (gorges, reservoirs, lakes, rivers, rivers, dams, etc.) change seasonally in water quality. Can be.

Membrane separation technology has been developed in many fields since 1960, focusing on reverse osmosis (RO) for desalting industrial water in the United States. In the early 1980s, Korea introduced ultrapure water production facilities in the semiconductor industry, and has developed into a universal technology, playing a big role in water treatment and wastewater treatment.

This membrane separation technique uses a semipermeable boundary membrane to remove contaminants contained in water by filtration and diffusion. Membrane separations applicable to water treatment or wastewater treatment are Microfiltration (MF), Ultrafiltration (UF), Nanofiltration (NF), Reverse Osmosis (RO) and Electrodialysis (Electro). Dialysis: ED).

In addition, the membrane separation configuration can be roughly divided into spiral wound, hollow fiber, tubular, and plate and frame, and the membrane module is immersed in water. It is classified into Immersible and Pressurized.

The present invention relates to a method for producing pure water using the membrane separation technology as described above.

First, a pretreatment step for removing turbidity, color, and suspended solids contained in raw water will be described.

Raw water through the raw water pump 15 from the raw water collecting tank 10 to remove the suspended solids, turbidity, microorganisms (E. coli, general bacteria, algae and protozoa), colloidal substances, color, odor and the like contained in the raw water After passing through the automatic washing filter (20), back pressure is possible to pass through the pressurized microfiltration membrane or ultrafiltration membrane separator 30, the backwashable submerged microfiltration membrane or ultrafiltration membrane separator (40) to pretreatment collection tank (50) Send to.

When storing water in the pretreatment collection tank 50 for a long time, it is preferable to inject microbial inhibitors 51, such as chlorine, since microbial propagation is concerned.

In this way, raw water is removed using turbid water or natural water using backwash type microfiltration membrane or backwash type ultrafiltration membrane to remove turbidity and suspended solids contained in raw water. The permeability of the membrane is impeded to reduce the flow rate.

Therefore, when the foreign matters are deposited on the automatic filter 20 or the membrane surface regularly according to the nature of the raw water, the pressure rise occurs. It must be removed.

To this end, the first to filter out foreign matter of 0.1 ~ 40mm from the automatic filter 20. 2, the automatic washing filter 20 is a stainless steel basket 23 installed inside a pressure vessel made of inlet port 21, raw material outlet 22, and plastic or stainless steel. The cylinder 25 is configured to reciprocate up and down by compressed air, and the flushing valve 24 is configured to discharge foreign substances inside the basket 23 during the up and down movement of the cylinder 25.

As the raw water passes through the inlet 21 to the outlet 22, foreign substances are caught in the basket 23 of the stainless steel net, thereby increasing the internal pressure. When the pressure rises as described above, the cylinder 25 is lowered, and the flow rate inside the basket 23 is increased according to the lowering of the cylinder 25, while vacuum washing is performed, and the foreign matter attached to the basket 23 is flushed. It is to be discharged through the valve (24). In this case, the flushing valve 24 has a smaller diameter than the inlet 21 and the outlet 22, and opens and closes only for 10 to 30 seconds required when the piston 25 is operated to descend to the bottom. The foreign matter attached to the basket 23 is detached and removed.

The automatic washing filter 20 can be continuously operated without downtime and is very effective for water containing muddy water, algae, and the like in raw water.

Next, when the pressure rises due to foreign substances on the surface of the membrane, it automatically blocks the inflow of natural water and blows water and compressed air on the contrary to the processing flow to desorb the foreign substances deposited on the surface of the membrane.

As such, the backwash type microfiltration membrane separator or the ultrafiltration membrane separators 30 and 40 are backwashed using a backwash pump 52. In this case, it is preferable to recycle the backwash wastewater generated.

To this end, the backwash waste water generated after backwashing the backwash type microfiltration membrane separator or the ultrafiltration membrane separator 30 and 40 is passed through a pore-controlled fibrous filter or a pressurized filter press. After improving the NTU and removing the suspended solids, the passed water is transferred to the raw water collection tank (1) for recycling, and the material that is not passed through and adhered to the surface of the fibrous filter medium is reversely backwashed to finally treat the wastewater. .

The pore-controlled fibrous filter consists of passing the backwashed water to the outside of the fiber bundle after compressing and installing the bundle having a fiber-like shape in order to reduce the voids.

In this case, inorganic coagulant such as aluminum sulfate or polyaluminum chromide (PAC) alone may be used to improve the cohesion of turbidity and suspended solids in the backwashed water flowing into the pore-controlled fibrous filter or pressurized filter press. It is preferable to inject ˜10 ppm or to sequentially inject an organic polymer flocculant.

Next, the demineralization step for removing ionic substances dissolved in pretreated raw water will be described.

Water transferred by the transfer pump 60 is injected with acid or alkali as the pH adjuster 90 in order to minimize the effect of the salt removal rate according to the hydrogen ion concentration (pH) of the pretreated water, and scale of the membrane by the hardness component. Sodium phosphate is injected as an anti-scaling agent (80), and the chlorine disinfectant of the pretreatment sump (50) has a polyamide membrane damage of the nanofiltration membrane separation (130) or the first and second reverse osmosis membrane separation apparatus (140, 170). In order to remove this it is injected with a reducing agent such as sodium bisulfite, which is an antioxidant (70).

In addition, in order to remove the increase in foreign matters due to the storage of the pre-treated water to pass through the safety precision filter 100 for removing the particles of 1 ~ 5㎛ size in sequence, and send the pre-treated water to the desalination process as a secondary process In order to control the water temperature, since the water treatment affects the performance of the nanofiltration membrane separator 130 or the first and second reverse osmosis membrane separators 140 and 170, the heat exchanger 110 is installed to correct the water temperature.

The raw water passing through the heat exchanger 110 is transferred to the nanofiltration membrane separator 130 or the first reverse osmosis membrane separator 140 through the high pressure pump 120.

The high-pressure pump 120 is installed in a vertical (intake inlet bottom, discharge outlet) in the water in the noise-free, vibration-free or on the ground to assemble the pump and the motor horizontally in the pressure housing to generate the water through the motor and the pump sequentially The heat was recovered to increase the permeation efficiency of the membrane.

If the salt concentration in raw water is less than 500mg / ℓ or the hardness component is more than 50ppm pass through the nanofiltration membrane separation device 130 to remove it, the permeated water can be used directly as drinking water, or the first reverse osmosis membrane separation device for raw water Sending the permeated water passed through the 140 to the primary permeate collection tank 150 and then pressurized the permeated water passed through the membrane with a boost pump 160 to the high-quality permeated water treated by the secondary reverse osmosis membrane separation device 170. The concentrated water not sent to the secondary permeate collection tank 180 and not passed through the membrane in the secondary reverse osmosis membrane separator is sent to the raw water collection tank 10 for recycling.

In addition, natural water having high concentration of raw water or total dissolved solids (TDS) is the permeated water that has passed through the primary reverse osmosis membrane separator 140 through the primary permeate collection tank 150 or the primary reverse osmosis membrane separator 140 ) And pressurized by the booster pump 160 directly to the secondary reverse osmosis membrane separator 170 to send the treated permeate to the secondary permeate collection tank (180).

Depending on the type of raw water, permeate water passing only through the nanofiltration membrane separation device 130 or the first reverse osmosis membrane separation device 140 is directly sent to the electrical continuous purifying device 210 which is the next process through the permeate transfer pump 190. It can be treated, the secondary permeate through the nanofiltration membrane separation unit 130 or the first reverse osmosis membrane separation unit 140 directly through the boost pump 160 without the need for the primary permeate collection tank 150 Reverse osmosis membrane separation device 170 can be sent.

Here, the membrane array of the nanofiltration membrane separation device 130 or the first reverse osmosis membrane separation device 140 is a membrane having a diameter of 4 to 40 inches and a length of 1 to 2 m in a pressure vessel of stainless steel or FRP. One to a maximum of seven inserted state in the first stage (Array), the first through the membrane module consisting of the first to third stages (assembly) and the second reverse osmosis membrane separation (170) 1 The permeation water of good quality can be obtained by constructing an arrangement of -3 steps.

On the other hand, if the pH of the pre-treated water is controlled to 5.5 to 6.5, the membrane scale or salt removal rate can be increased, but gas flows such as carbon dioxide do not pass through the nanofiltration membrane or the reverse osmosis membrane. That is, a gas such as carbon dioxide has a pH of bicarbonate ion (HCO ₃ ^-) in the permeate water in the 7 or less in the present in and, pH of 7 or more carbonate ions (CO ₃ ^{2 -)} there is the presence, the bicarbonate ion (HCO ₃ ^- ) Is gaseous, so it permeates the membrane.

As such, the permeated water that has passed through the nanofiltration membrane separation device 130 or the first reverse osmosis membrane separation device 140 contains a gas stream such as carbon dioxide, and thus has an acid pH of 7 or less, and thus, the secondary reverse osmosis membrane separation device 170. Prior to the installation of the alkali injection device 155 to inject sodium hydroxide so that the pH of the influent water flowing into the secondary reverse osmosis membrane separator 170 to 7 or more.

When the pH of the influent water reaches 7 or more by the injection of sodium hydroxide, the carbon dioxide contained in the water is present in the state of carbonate ions (CO ₃ ^2- ), and thus cannot be penetrated by the membrane of the secondary reverse osmosis membrane separation unit 170.

If the alkali injector 155 is not used, gas streams such as dissolved oxygen and carbon dioxide are contained in the permeated water, and these gas streams also affect the quality of pure water, which is the final treatment water. . Therefore, in this case, the permeated water is passed through the membrane contactor (Membrane Contactor, 200) to remove the gas flow, such as carbon dioxide, and then sent to the electrical continuous filtration apparatus 210 for processing.

In addition, by installing the energy recovery device 125, the nanofiltration membrane separation device by recovering the pressure of the concentrated water generated in the nanofiltration membrane separation device 130 or the first reverse osmosis membrane separation device 140, the second reverse osmosis membrane separation device 170 130 or the first reverse osmosis membrane separation unit 140, the second reverse osmosis membrane separation unit 170 to increase the pressure of the incoming water to reduce the energy. The energy recovery device is to exchange the pressure of the concentrated water from the membrane separation with the water supplied to the membrane separation side to transfer the pressure of the concentrated water to the raw water supplied to reduce the energy cost.

The concentrated water that has not passed through the secondary reverse osmosis membrane separator 170 is transferred to the raw water collection tank 10 for reuse.

Next, the electrical continuous purification apparatus 210 used in the post-treatment step for raising the specific resistance of the treated water quality from which the soluble ionic material is removed will be described.

Conventionally, chemical chemicals are used by adopting a mixed phase ion exchange resin method, but in the present invention, an electrical continuous purifying device (EDI) 210 capable of raising a specific resistance without using chemicals is used.

The electrically continuous purifying apparatus 210 refers to a device for desalting ions contained in a small amount in the permeate water using electromotive force by filling an ion exchange resin in the electrodialysis membrane.

That is, the electric continuous purifier 210 is a combination of ion exchange resin technology and an electrodialysis membrane. The positive and negative ion exchange membranes intersect between two electrode bodies (Anode and Cathode) for supplying a DC power supply, and a layer layer is arranged. It consists of a portion (dilution / concentration chamber) in which water flows with inlet and outlet nozzles filled with ion exchange resin.

DC current is supplied as an external power supply from an electrode body disposed at both ends of the combination consisting of an ion exchange membrane and a dilution chamber / concentration chamber. Then, the flowing part of the water is placed under the influence of electricity, and the ions in the water are attracted to the electrode body having the opposite polarity.

In other words, the portion bounded by the anion membrane adjacent to the + electrode body and the cation membrane adjacent to the + electrode body is deprived of the ion factor, and the portion becomes a dilution chamber. On the other hand, the part bounded by the negative electrode membrane adjacent to the electrode body and the positive electrode membrane adjacent to the electrode body attracts ions moving from the dilution chamber, where the ion concentration is increased than the ion concentration of the influent, where the concentration chamber is do. The flow of water through the concentration chamber is called the Reject Stream.

Ion-exchange membranes operate on the same principles and materials as ion-exchange resins to move specific ions away from opposite polar ions. That is, the anion exchange membrane transmits only anions, the cation exchange membrane transmits only cations, and ions of different polarities inhibit permeation. These membranes do not penetrate water.

The water quality conditions of the feed-in water of the electric continuous purifier 210 are as follows: electrical conductivity is 20 ㎲ / cm or less, pH 5.0 to 9.5, water temperature 5 to 35 ° C, hardness component 1 ppm or less, total organic carbon (TOC) 0.5 ppm The quality of raw water should be controlled by reverse osmosis membrane separation or ion exchange resin method, since it is less than 0.01 ppm of iron and manganese and 0.5 ppm of silica.

Water passing through the electrical continuous purifying device 210 is a pure water (Pure water or DeIonized Water) of more than 10,000,000 Ω-cm (conductivity of 0.1 Micromhos-cm or less) can be used as water for power plants.

The pure water in the water passed through the electric continuous purifying device 210 is used as power generation water through the pure water tank 220 and the pure water transfer pump 230. Reference numeral 215 denotes the concentrated water generated in the electrical continuous purification device 210 and sent to the raw water collection tank 10 for reuse.

Experiment Result 1

The table below shows the results of filtration of backwash wastewater using a pore-controlled fibrous filter and a pressurized filter press.

Backwash Wastewater Characteristics Air gap control fiber filter Pressurized Filta Press I Ⅱ Ⅲ I Ⅱ Ⅲ Turbidity, NTU 3.5 3.3 3.6 6.4 6.9 8.7 Suspended matter (SS), mg / ℓ 2.3 2.3 3.5 5.1 4.8 6.2

The backwash waste water is backwashed with foreign matter accumulated on the membrane surface when the pressure difference between the inflow side and the outflow side is 1.5 kg / cm 2 using the same raw water. Ⅰ is the backwash wastewater of backwash type microfiltration membrane with turbidity of 35 NTU, suspended solids is 1,890mg / ℓ, and Ⅱ is the backwash wastewater generated after the treatment of backwash type ultrafiltration membrane by Dead End filtration. 53 NTU, suspended solids was 4232 mg / l, and Ⅲ was the reverse wash water generated after cross-flow ultrafiltration membrane separation using cross flow method. The turbidity was 64 NTU and suspended solids was measured at 4,282 mg / l. .

The materials of the I, II, and III membranes were polyvinyl difluoride (PVDF), and all three methods were mixed with water and air at the time of backwashing.

Experiment Result 2

The table below shows the results of testing the apparatus for producing power generation water using only membrane (Membrane) with raw water as natural water.

Analysis item enemy After passing BMF After passing BUF NF Permeate Primary RO Permeate Secondary RO Permeate EDI Processed Water Calcium (Ca ^{2 +} ) 56 56 <56 3.8 0.7 0.4 0 Magnesium (Mg ^{2 +} ) 18.5 18.5 <18.5 1.2 1.3 0.1 <0.1 Sodium (Na ^{2 +} ) 4.2 4.2 <4.2 3.7 2.5 0.2 0.01 A sulfate ion (SO ₄ ^{2 -)} 31.9 31.9 <31.9 5.1 0.2 0.06 0 Nitrate ion (NO ₃ ^-) 1.8 1.8 <1.8 0.5 0.04 0.01 0 Chloride (Cℓ ^-) 3.5 3.5 <3.5 2.9 0.8 0.6 0.1 Silica (SiO ₂ ) 6.7 6.7 <6.7 0.5 0.036 0 0.01 Turbidity (NTU) 4.3 0.3 0.08 0 0 0 0 pH 6.9 6.9 6.9 6.4 7.1 6.8 6.7 Electrical Conductivity (㎲ / ㎝) 187 187 <187 143 5.4 3.5 <0.067

-BMF is the backwash pressurized reverse filtration membrane, BUF is the backwash pressurized ultrafiltration membrane, NF is the nanofiltration membrane, RO is the reverse osmosis membrane, and EDI is the electric continuous purification device (hereinafter the same).

-Raw water for the experiment is surface water

-Unit is mg / l

-Adjust the pH of the second reverse osmosis membrane separation influent to 7.0-7.8

-Nanofiltration membrane separation permeate is not treated with secondary reverse osmosis membrane separation device

-The membranes of the first and second reverse osmosis membrane separators are made of brackish water.

Experiment Result 3

The table below shows the results of experimenting with raw water using seawater.

Analysis item enemy  After passing BMF After passing BUF  Primary RO Permeate Secondary RO Permeate EDI Processed Water Calcium (Ca ^{2 +} ) 980 980 <980 2.0 0.4 0 Magnesium (Mg ^{2 +} ) 5,300 5,300 <5,300 4.3 0.1 <0.1 Sodium (Na ^{2 +} ) 10,690 10,690 <10,690 71 0.2 0.01 A sulfate ion (SO ₄ ^{2 -)} 2,520 2,520 <2,520 1.5 0.06 0 Silica (SiO ₂ ) 0.6 0.6 <0.6 0.01 0.01 0 Chloride (Cℓ ^-) 19,800 19,800 <19,800 103 0.6 0.1 Fe 0.15 0.15 <0.15 0.01 0 0 Turbidity (NTU) 5.1 5.1 0.08 0 0 0 pH 7.9 7.9 7.9 5.6 6.8 6.7 Electrical Conductivity (㎲ / ㎝) 51,000 51,000 <51,00 370 3.5 0.067

-Unit is mg / l

-Adjust the pH of the second reverse osmosis membrane separation influent to 7.0-7.8

-Sea water is used for the membranes of the first and second reverse osmosis membrane separators.

In Experimental Results 2 and 3, it can be seen that the permeated water passing through the secondary reverse osmosis membrane separation device satisfies all the water quality conditions of the incoming water introduced into the electrical continuous purification device 210.

As described in detail above, according to the pure water manufacturing method used in the power plant according to the present invention, the water passed through the backwash wastewater generated in the backwash filtration device through a pore-controlled fibrous filter or a pressurized filter press can be recycled. In addition, there is an advantage that by using the electrical continuous pure apparatus can remove the inorganic material of the raw water without using chemicals for regeneration.

Claims (5)

Pretreatment step to remove turbidity, color, and suspended solids contained in raw water and desalting step to remove ionic substances dissolved in pretreated raw water In the pure water manufacturing method for power plants using the membrane separation consisting of a post-treatment step, In the pretreatment step, the raw water supplied from the raw water collection tank is passed through a back pressure type microfiltration membrane or a backwash type ultrafiltration membrane of a pressurized or submerged type to be transferred to the pretreatment collection tank; When the pressure rises due to foreign matters on the surface of the backwash type microfiltration membrane or the backwash type ultrafiltration membrane, the inflow of raw water is automatically blocked, and the backwash that desorbs the foreign substances deposited on the surface of the membrane by blowing water and compressed air in the reverse of the processing flow To operate the pump; Passing backwash wastewater generated in the process of backwashing the backwash type microfiltration membrane or the backwash type ultrafiltration membrane through a pore-controlled fibrous filter or a pressurized filter press to transfer the water to a raw water collection tank for recycling; Pure water production method for power plants using the membrane separation characterized in that. The method of claim 1, Raw water supplied from the raw water collection tank in the pretreatment step, a stainless steel basket is installed inside the pressure vessel made of plastic or stainless steel, the cylinder is reciprocated into the basket and 0.1 to 40 mm of reciprocating motion of the cylinder. After the foreign matter passes through the automatic washing filter discharged through the flushing valve, the pure water manufacturing method for a power plant using membrane separation, characterized in that passing through a back-flush microfiltration membrane or a back-flush ultrafiltration membrane. The method of claim 1, In order to improve the cohesiveness of turbidity and suspended solids in the backwash wastewater flowing into the pore-controlled fibrous filter or pressurized filter press, inorganic coagulant aluminum sulfate (Alum) or polyaluminum chromium (PAC) alone is 0.1 to 10. Pure water production method using a membrane separation, characterized in that the injection of ppm or the organic flocculant is sequentially injected. The method of claim 1, The desalting step, Depending on the type of raw water through the nanofiltration membrane separator or the first reverse osmosis membrane separator; Injecting sodium hydroxide from the alkali injection device to the permeated water passed through the nanofiltration membrane separator or the first reverse osmosis membrane separator to pass through the secondary reverse osmosis membrane separator by the pH of the permeated water is 7 or more; Pure water production method for power plants using the membrane separation characterized in that. The method according to claim 1, wherein In the post-processing step, Since the positive / negative ion exchange membranes intersect between the two electrode bodies (Anode and Cathode) supplying DC power, the layers are arranged, and the ion exchange resin is filled therebetween. Passing an electric continuous pure water purifying apparatus; Pure water manufacturing method for a power plant using a membrane separation comprising a.

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