Electronic-grade ultrapure water preparation system and process

Abstract

The system comprises a raw water tank, a multi-medium filter, a bag filter, a plate heat exchanger, an ultrafiltration device, an ultrafiltration water tank, a primary reverse osmosis device, a secondary reverse osmosis device, a UV (ultraviolet) sterilization device, an EDI (electrodeionization) device, a TOC (total organic carbon) remover, a polishing mixed bed and a terminal filter which are sequentially connected, the RO concentrated water tank is connected with the reverse osmosis concentrated water outlet ends of the primary reverse osmosis device and the secondary reverse osmosis device, the electric driving membrane device is connected with the RO concentrated water tank, and the drainage concentrated water tank is connected with the electric driving membrane device. The reverse osmosis (RO) and electrodeionization (EDI) combined process adopted in the invention comprehensively solves a series of problems of acid and alkali consumption, environmental pollution, poor automation degree, complex system and the like in ultrapure water production. The process equipment disclosed by the invention is relatively high in automation degree, saves the cost required by acid-base regeneration, and does not cause any pollution to the environment.

Description

Technical Field

[0001] The present invention relates to the technical field of ultrapure water preparation, and in particular to an electronic grade ultrapure water preparation system and process. Background Art

[0002] Monocrystalline silicon cells are one of the most efficient and widely used cells in the silicon series solar cells in the photovoltaic industry. The production process of monocrystalline silicon cells requires a large amount of electronic grade ultrapure water, which is mainly used in processes such as texturing, BSG removal + alkali polishing, PSG removal + RCA, and auxiliary material cleaning. Electronic grade ultrapure water is water with a resistivity greater than 18MΩ·cm, and the purity of water quality directly affects the quality of monocrystalline silicon cells. The traditional ultrapure water production process has always used ion exchange as the core deep desalination method. The ion exchange resin used in this process needs to be periodically regenerated with a large amount of acid and alkali. This chemical regeneration method is not only inconvenient to operate, consumes a large amount of cleaning water, but also produces waste acid and waste alkali, becoming a source of pollution for water and soil environment. The reverse osmosis concentrated water produced in the ultrapure water production process has the characteristics of high salt content, easy scaling, low suspended solids content (lower than the SS content in tap water), high water temperature, and large reuse space. If it is directly discharged, it will cause a great waste of water resources.

[0003] Therefore, it is necessary to improve the existing technology to provide a more reliable solution. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide an electronic grade ultrapure water preparation system and process in view of the deficiencies in the above-mentioned prior art.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: in the first aspect of the present invention, an electronic grade ultrapure water preparation system is provided, comprising a raw water tank, a multi-media filter, a bag filter, a plate heat exchanger, an ultrafiltration device, an ultrafiltration water tank, a primary reverse osmosis device, a secondary reverse osmosis device, a UV ultraviolet sterilization device, an EDI device, a TOC remover, a polishing mixed bed, a terminal filter, and an RO concentrated water tank connected to the reverse osmosis concentrated water outlet ends of the primary reverse osmosis device and the secondary reverse osmosis device, an electrically driven membrane device connected to the RO concentrated water tank, and a drainage concentrated water tank connected to the electrically driven membrane device.

[0006] Preferably, a first water delivery pipe and a first backwash water pipe are connected in parallel between the raw water tank and the multi-media filter, the first water delivery pipe is connected to the water inlet of the multi-media filter, and the first backwash water pipe is connected to the water outlet of the multi-media filter;

[0007] The first water delivery pipe is provided with a raw water pump, and the first backwash water pipe is provided with a multi-media backwash water pump.

[0008] Preferably, a second water pipe and a second backwash water pipe are connected in parallel between the ultrafiltration device and the ultrafiltration water tank, the second water pipe is connected to the water inlet side of the ultrafiltration water tank, and the second backwash water pipe is connected to the water outlet side of the ultrafiltration water tank;

[0009] The second backwash water pipe is provided with an ultrafiltration dosing device and an ultrafiltration backwash water pump.

[0010] Preferably, the primary reverse osmosis device comprises an RO booster pump, a reverse osmosis dosing device, a first security filter, a primary high-pressure pump, a primary reverse osmosis membrane group and a primary RO water tank, which are sequentially connected to the water outlet side of the ultrafiltration water tank, and the purified water outlet end of the primary reverse osmosis membrane group is connected to the primary RO water tank, and the concentrated water outlet end is connected to the RO concentrated water tank;

[0011] The secondary reverse osmosis device includes a secondary high-pressure pump, a primary reverse osmosis membrane group and a secondary RO water tank which are sequentially connected to the water outlet side of the primary RO water tank. The clean water outlet end of the secondary reverse osmosis membrane group is connected to the secondary RO water tank, and the concentrated water outlet end is connected to the RO concentrated water tank.

[0012] Preferably, the water outlet side of the secondary RO water tank is connected to the UV ultraviolet sterilization device, and a lift pump is provided between the secondary RO water tank and the UV ultraviolet sterilization device;

[0013] A second safety filter is arranged between the UV sterilization device and the EDI device.

[0014] Preferably, the EDI device is further provided with an EDI water return pipe, the EDI water return pipe is connected to the water inlet side of the RO concentrated water tank, and the EDI water return pipe is provided with an EDI water return valve.

[0015] Preferably, a concentrate pump, an antiscalant dosing device and a third safety filter are sequentially arranged between the outlet side of the RO concentrate tank and the electrically driven membrane device.

[0016] Preferably, the purified water outlet of the concentrated water reverse osmosis device is connected to the raw water tank, and a concentrated water outlet pipe and a concentrated water return pipe are connected in parallel to the concentrated water outlet of the concentrated water reverse osmosis device;

[0017] The concentrated water return pipe is connected to the RO concentrated water tank, and a concentrated water return valve is provided on the concentrated water return pipe;

[0018] The concentrated water outlet pipe is connected to the concentrated water drainage tank, and a drainage valve is arranged on the concentrated water outlet pipe.

[0019] A second aspect of the present invention provides a process for preparing electronic grade ultrapure water, which uses the system as described above to prepare ultrapure water, and the process comprises the following steps:

[0020] S1. The water in the raw water tank is transported to the multi-media filter through the raw water pump. The filtered water passes through the bag filter and then enters the plate heat exchanger. The water temperature is controlled at 25℃±1 through the plate heat exchanger.

[0021] S2. The outlet water of the plate heat exchanger passes through the primary reverse osmosis device and the secondary reverse osmosis device in turn and then enters the EDI device. The reverse osmosis concentrated water produced by the primary reverse osmosis device and the secondary reverse osmosis device enters the RO concentrated water tank for collection;

[0022] S4. Part of the effluent from the EDI device enters the RO concentrated water tank through the EDI return pipe, and the rest of the effluent enters the TOC remover; the effluent from the TOC remover passes through the polishing mixed bed and the terminal filter in turn to obtain electronic grade ultrapure water;

[0023] S5. The water in the RO concentrated water tank passes through the concentrated water pump and the third safety filter in turn and then enters the concentrated water reverse osmosis device. The clean water produced by the concentrated water reverse osmosis device enters the raw water tank. A part of the concentrated water produced by the concentrated water reverse osmosis device returns to the RO concentrated water tank through the concentrated water return pipe, and the remaining part enters the drainage concentrated water tank through the concentrated water outlet pipe. The water in the drainage concentrated water tank is discharged.

[0024] Preferably, when the multi-media filter needs to be shut down for backwashing, the multi-media filter is backwashed using water in the raw water tank through a multi-media backwashing water pump;

[0025] When the ultrafiltration device needs to be shut down for backwashing, a cleaning agent is added to the ultrafiltration dosing device, and the ultrafiltration device is backwashed using water in the ultrafiltration water tank through an ultrafiltration backwash water pump.

[0026] The beneficial effects of the present invention are:

[0027] The present invention provides an electronic grade ultrapure water preparation system and process. The reverse osmosis (RO) + electric desalination (EDI) combined process adopted in the present invention comprehensively solves a series of problems in the production of ultrapure water, such as acid and alkali consumption, environmental pollution, poor automation, and complex system. The use of the RO and EDI combined process can ensure the best water treatment process performance, and can ensure that the outlet water resistance is greater than 18MΩ·cm for a long time; compared with conventional acid and alkali regeneration, the process equipment of the present invention has a higher degree of automation, and saves the cost required for acid and alkali regeneration, and does not cause any pollution to the environment; the present invention adopts a two-stage reverse osmosis + EDI combined process to produce ultrapure water, and the concentrated water reuse system adopts an electric drive membrane process, which can desalinate the concentrated water produced in the two-stage reverse osmosis system and then re-enter the ultrapure water production system for recycling. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic structural diagram of the electronic grade ultrapure water preparation system of the present invention.

[0029] Description of reference numerals:

[0030] 1-Raw water tank; 2-Raw water pump; 3-Multi-media filter; 31-Multi-media backwash water pump; 4-Bag filter; 5-Plate heat exchanger; 6-Ultrafiltration device; 7-Ultrafiltration water tank; 71-Ultrafiltration backwash water pump; 72-Ultrafiltration dosing device; 8-First-stage reverse osmosis device; 81-RO booster pump; 82-Reverse osmosis dosing device; 83-First security filter; 84-First-stage high-pressure pump; 85-First-stage RO water tank; 9-Second-stage reverse osmosis device; 91-Second-stage high-pressure pump; 92-Second-stage RO water tank; 10-Booster pump; 11-UV ultraviolet sterilization device; 12-Second security filter; 1 3-EDI device; 131-EDI return pipe; 14-TOC remover; 15-polishing mixed bed; 16-terminal filter; 17-electrically driven membrane device; 181-RO concentrate tank; 182-concentrate pump; 183-scaling inhibitor dosing device; 184-third security filter; 185-concentrate reverse osmosis device; 186-drainage concentrate tank; 201-first water pipe; 202-first backwash water pipe; 203-second water pipe; 204-second backwash water pipe; 205-concentrate outlet pipe; 206-concentrate return pipe; 207-concentrate return valve; 208-drain valve. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below in conjunction with embodiments so that those skilled in the art can implement the invention with reference to the description.

[0032] It should be understood that the terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.

[0033] The test methods used in the following examples are conventional methods unless otherwise specified. The materials and reagents used in the following examples are all commercially available unless otherwise specified. In the following examples, if no specific conditions are specified, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used, if the manufacturer is not specified, are all conventional products that can be purchased commercially.

[0034] Example 1

[0035] An electronic grade ultrapure water preparation system comprises a raw water tank 1, a multi-media filter 3, a bag filter 4, a plate heat exchanger 5, an ultrafiltration device 6, an ultrafiltration water tank 7, a primary reverse osmosis device 8, a secondary reverse osmosis device 9, a UV ultraviolet sterilization device 11, an EDI device 13, a TOC remover 14, a polishing mixed bed 15, a terminal filter 16, and an RO concentrated water tank 181 connected to the reverse osmosis concentrated water outlet ends of the primary reverse osmosis device 8 and the secondary reverse osmosis device 9, an electric-driven membrane device 17 connected to the RO concentrated water tank 181, and a drainage concentrated water tank 186 connected to the electric-driven membrane device 17.

[0036] In this embodiment, a first water delivery pipe 201 and a first backwash water pipe 202 are connected in parallel between the raw water tank 1 and the multi-media filter 3. The first water delivery pipe 201 is connected to the water inlet of the multi-media filter 3, and the first backwash water pipe 202 is connected to the water outlet of the multi-media filter 3.

[0037] The first water delivery pipe 201 is provided with a raw water pump 2 , and the first backwash water pipe 202 is provided with a multi-media backwash water pump 31 .

[0038] In this embodiment, a second water pipe 203 and a second backwash water pipe 204 are connected in parallel between the ultrafiltration device 6 and the ultrafiltration water tank 7, the second water pipe 203 is connected to the water inlet side of the ultrafiltration water tank 7, and the second backwash water pipe 204 is connected to the water outlet side of the ultrafiltration water tank 7;

[0039] An ultrafiltration dosing device 72 and an ultrafiltration backwash water pump 71 are provided on the second backwash water pipe 204 .

[0040] In this embodiment, the primary reverse osmosis device 8 includes an RO booster pump 81, a reverse osmosis dosing device 82, a first security filter 83, a primary high-pressure pump 84, a primary reverse osmosis membrane group and a primary RO water tank 85, which are sequentially connected to the outlet side of the ultrafiltration water tank 7. The purified water outlet end of the primary reverse osmosis membrane group is connected to the primary RO water tank 85, and the concentrated water outlet end is connected to the RO concentrated water tank 181.

[0041] The secondary reverse osmosis device 9 includes a secondary high-pressure pump 91, a primary reverse osmosis membrane group and a secondary RO water tank 92 which are connected in sequence to the outlet side of the primary RO water tank 85. The clean water outlet end of the secondary reverse osmosis membrane group is connected to the secondary RO water tank 92, and the concentrated water outlet end is connected to the RO concentrated water tank 181.

[0042] In this embodiment, the water outlet side of the secondary RO water tank 92 is connected to the UV ultraviolet sterilization device 11, and a booster pump 10 is provided between the secondary RO water tank 92 and the UV ultraviolet sterilization device 11;

[0043] A second safety filter 12 is provided between the UV sterilization device 11 and the EDI device 13 .

[0044] In this embodiment, the EDI device 13 is further provided with an EDI water return pipe 131 , which is connected to the water inlet side of the RO concentrated water tank 181 , and an EDI water return valve is provided on the EDI water return pipe 131 .

[0045] In this embodiment, a concentrate pump 182 , an antiscalant dosing device 183 and a third safety filter 184 are sequentially arranged between the outlet side of the RO concentrate tank 181 and the electrically driven membrane device 17 .

[0046] In this embodiment, the purified water outlet of the concentrate reverse osmosis device 185 is connected to the raw water tank 1, and the concentrate outlet of the concentrate reverse osmosis device 185 is connected in parallel with a concentrate outlet pipe 205 and a concentrate return pipe 206;

[0047] The concentrate return pipe 206 is connected to the RO concentrate tank 181, and a concentrate return valve 207 is provided on the concentrate return pipe 206; the concentrate outlet pipe 205 is connected to the drainage concentrate tank 186, and a drainage valve 208 is provided on the concentrate outlet pipe 205. The concentrate outlet ratio is controlled by the concentrate return valve 207 and the drainage valve 208.

[0048] The process for preparing electronic grade ultrapure water by the above system comprises the following steps:

[0049] S1. The water in the raw water tank 1 is transported to the multi-media filter 3 through the raw water pump 2. The filtered water passes through the bag filter 4 and enters the plate heat exchanger 5. The water temperature is controlled to 25℃±1 through the plate heat exchanger 5.

[0050] S2, the outlet water of the plate heat exchanger 5 passes through the primary reverse osmosis device 8 and the secondary reverse osmosis device 9 in sequence and then enters the EDI device 13, and the reverse osmosis concentrated water produced by the primary reverse osmosis device 8 and the secondary reverse osmosis device 9 enters the RO concentrated water tank 181 for collection;

[0051] S4, part of the effluent from the EDI device 13 enters the RO concentrated water tank 181 through the EDI return pipe 131, and the rest of the effluent enters the TOC remover 14; the effluent from the TOC remover 14 passes through the polishing mixed bed 15 and the terminal filter 16 in turn to obtain electronic grade ultrapure water;

[0052] S5. The water in the RO concentrated water tank 181 passes through the concentrated water pump 182 and the third safety filter 184 in sequence and then enters the concentrated water reverse osmosis device 185. The clean water produced by the concentrated water reverse osmosis device 185 enters the raw water tank 1. A part of the concentrated water produced by the concentrated water reverse osmosis device 185 returns to the RO concentrated water tank 181 through the concentrated water return pipe 206, and the remaining part enters the drainage concentrated water tank 186 through the concentrated water outlet pipe 205. The water in the drainage concentrated water tank 186 is discharged.

[0053] When the multi-media filter 3 needs to be shut down for backwashing, the multi-media backwashing water pump 31 uses the water in the raw water tank 1 to backwash the multi-media filter 3;

[0054] When the ultrafiltration device 6 needs to be shut down for backwashing, a cleaning agent is added to the ultrafiltration dosing device 72 , and the ultrafiltration device 6 is backwashed using the water in the ultrafiltration water tank 7 through the ultrafiltration backwash water pump 71 .

[0055] The raw water tank 1 is used to store fresh water to ensure the stability of subsequent water use.

[0056] Among them, the multi-media filter 3 is mainly used to remove particulate impurities larger than 10μm in the raw water, and pass the water with high turbidity through two or more filter media under a certain pressure, so as to effectively remove suspended matter and make the water clear. In this embodiment, quartz sand and coconut shell biochar are selected as double-layer filter media. Quartz sand has a good effect of filtering out particulate impurities and suspended particles in water. Activated carbon is used to remove dissolved organic matter, heavy metals and residual chlorine in water. Multi-media filter 3 has a diameter of 3600mm and a water output of 100m 3 / h, effluent turbidity <1NTU, SDI <4, free residual chlorine <0.1ppm. After a period of operation, the multi-media filter 3 needs to be backwashed.

[0057] When the incoming water passes through the bag filter 4 under pressure, the impurity particles are trapped inside the filter bag. The filter bag is replaced in time according to the inlet and outlet pressure difference or the running time, and there is basically no filter material consumption during the filtration.

[0058] The plate heat exchanger 5 mainly plays the role of increasing the temperature of the raw water, and the temperature is controlled at 25°C ± 1 to reduce the impact of seasonal temperature changes on the water production of the ultrafiltration and RO systems.

[0059] Among them, the ultrafiltration device 6 is used as the pretreatment equipment of the reverse osmosis system, which can reduce the investment in reverse osmosis and extend the service life of the RO membrane. The external pressure hollow fiber ultrafiltration membrane made of PVDF is selected, with a pore size of 0.002-0.005μm and a suspended matter removal rate of 90%. Two backwash pumps are equipped, and the maintenance cleaning and restorative chemical cleaning agents of the ultrafiltration membrane all use NaClO, HCl and NaOH.

[0060] Among them, the two-stage reverse osmosis system (primary reverse osmosis device 8 and secondary reverse osmosis device 9) further desalinates the ultrafiltration water, which can remove most of the inorganic salts, organic matter, microorganisms, etc. in the water. The ultrafiltration water is transported to the primary security filter by the lifting pump 10 through the ultrafiltration water tank 7 for preliminary filtration, and then pressurized by the high-pressure pump to enter the primary reverse osmosis module for desalination treatment. The treated water enters the primary RO water tank 85. The design recovery rate of the primary reverse osmosis is 75%, and the desalination rate of a single membrane is ≥99.5%. The primary reverse osmosis is equipped with shutdown flushing, and the flushing water source is the primary reverse osmosis water; the secondary reverse osmosis does not set the startup or shutdown flushing due to the good water quality of the inlet water, but sets the offline chemical cleaning.

[0061] The ultrafiltration water is transported to the primary security filter by the lifting pump 10 through the ultrafiltration water tank 7 for preliminary filtration, and then pressurized by the high-pressure pump to enter the primary reverse osmosis module for desalination treatment. The treated water enters the primary RO water tank 85. The design recovery rate of the primary reverse osmosis is 75%, and the desalination rate of a single membrane is ≥ 99.5%. The primary reverse osmosis is equipped with shutdown flushing, and the flushing water source is the primary reverse osmosis water; the secondary reverse osmosis does not have startup or shutdown flushing due to the good water quality of the inlet water, but has offline chemical cleaning.

[0062] Sulfate and carbonate enrichment on the membrane surface can easily cause problems such as reverse osmosis membrane blockage, reduced recovery rate, and reduced desalination rate. Inorganic salt crystals can easily scratch the reverse osmosis membrane during the concentration process, shortening the service life of the membrane. Adding scale inhibitors can effectively control salt scale and extend the water production cycle of the reverse osmosis system. Scale inhibitors are composite dispersants with large molecular weights and low dosages. They cannot pass through the reverse osmosis membrane. While effectively controlling membrane scaling pollution, they will not affect the water quality of the produced water. The scale inhibitor (commercially available conventional products) addition point is set before the raw water enters the RO membrane (i.e., through the reverse osmosis dosing device 82). After the reverse osmosis system has been running for a long time, chemical drugs are needed to clean organic matter and inorganic salt scale to restore the performance of the reverse osmosis membrane. When removing inorganic salt scale, the agent is 2.0% citric acid or 0.5% HCl, and when removing polymerized silicon scale, the agent is 0.1% NaOH. The chemical cleaning time interval is 3 to 4 months. The water quality of the effluent from the reverse osmosis system (i.e., the effluent from the secondary reverse osmosis device 9) meets the inlet water requirements of the EDI device 13: conductivity <40μS / cm, total hardness (CaCO3) <0.5mg / L, residual chlorine <0.05mg / L, SiO2≤0.5mg / L.

[0063] Among them, the EDI device 13 scientifically integrates electrodialysis and ion exchange technology, and realizes the directional migration of ions in water under the action of electric field through the selective permeation of cations and anions by cation and anion membranes and the exchange of ions in water by ion exchange resins, thereby achieving deep purification and desalination of water. The indicators of the EDI device 13 are: recovery rate is 90% to 95%, and the resistivity of produced water is ≥18.0MΩ·cm.

[0064] The TOC remover 14 sterilizes the ultrapure water delivered, and the irradiation intensity is >180000μWs / cm 2 , effluent TOC <10μg / L. The main mechanism of action of TOC-UV is that it can emit dual-wavelength ultraviolet lamps of 254nm and 185nm. Among them, 185nm ultraviolet rays have strong energy and play a major role in the degradation of TOC. 185nm ultraviolet rays will induce the homolysis and ionization of water molecules, produce strong oxidizing hydroxyl free radicals and hydrogen peroxide, and oxidize organic matter into charged substances such as CO2 or organic acids. At the same time, 185nm ultraviolet rays can also directly decompose pollutants.

[0065] The polishing mixed bed 15 can further desalinate and remove residual TOC in the water. A filter is arranged at the outlet of the polishing mixed bed 15 to prevent the resin from entering the terminal filter 16 and clogging the membrane assembly.

[0066] Among them, the terminal filter 16 can ensure that the particle content of the outlet water meets the requirements, and the system outlet water resistivity is ≥18.5MΩ·cm.

[0067] Among them, the concentrated water produced by the two-stage reverse osmosis system is introduced into the RO concentrated water tank 181, and the reverse osmosis concentrated water is pumped into the electric drive membrane device 17 by the lifting pump 10 through the third security filter 184 for desalination treatment, and the generated fresh water enters the concentrated water reverse osmosis device 185 for further desalination treatment. At regular intervals, the positive and negative electrodes of the electric drive membrane are reversed, and the produced water is set to enter the electric membrane production water tank when the conductivity reaches 500μS / cm, and the concentrated water is discharged when the conductivity reaches 12000μS / cm; at the same time, the concentrated water compartment and the fresh water compartment are exchanged accordingly, which can automatically clean the dirt formed on the ion exchange membrane and the electrode surface to ensure the long-term stable operation of the system. The electric drive membrane process has the advantages of low power consumption, no environmental pollution, flexible device design, and no need for heating and heating through a heat exchanger. Its desalination rate and water production rate are 30% to 99% and 65% to 90% respectively. The desalination rate can be increased by connecting the membrane groups in series, and the water production rate can be increased by connecting them in parallel. Adding antiscalant through the antiscalant dosing device 183 can prevent the crystallization of insoluble salts such as Mg(OH)2, CaCO3, CaSO4, etc.

[0068] In this embodiment, the inlet water in the raw water tank 1 is tap water, and the ultrapure water finally prepared (the outlet water at the water use point) has a water quality of resistivity ≥18.5MΩ·cm, TOC concentration <5μg / L, bacteria <0.01cfu / mL, soluble SiO2 <5μg / L, sodium <0.1μg / L, copper <0.1μg / L, zinc <0.1μg / L, nickel <0.1μg / L, which meets the ultrapure water quality standards.

[0069] In this embodiment, the RO and EDI devices 13 are used together, which can effectively solve the shortcoming that the RO effluent cannot be completely desalinated, and can also improve the water quality of the EDI inlet, prevent EDI damage, and increase the overall water purification effect. The concentrated water reuse system collects and processes the reverse osmosis concentrated water, improves the utilization efficiency of water resources, and reduces the cost of ultrapure water preparation. It promotes the preparation of electronic grade ultrapure water to develop in the direction of low cost, pollution-free, continuous production, high yield, and easy operation, so that the water treatment industry will eventually become a green and environmentally friendly industry and play a greater role.

[0070] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to specific details.

Claims

1. An electronic grade ultrapure water preparation system, characterized in that: It includes a raw water tank, a multi-media filter, a bag filter, a plate heat exchanger, an ultrafiltration device, an ultrafiltration water tank, a primary reverse osmosis device, a secondary reverse osmosis device, a UV ultraviolet sterilization device, an EDI device, a TOC remover, a polishing mixed bed, a terminal filter, and an RO concentrated water tank connected to the reverse osmosis concentrated water outlet ends of the primary reverse osmosis device and the secondary reverse osmosis device, an electric-driven membrane device connected to the RO concentrated water tank, and a drainage concentrated water tank connected to the electric-driven membrane device.

2. The electronic grade ultrapure water preparation system according to claim 1, characterized in that: A first water delivery pipe and a first backwash water pipe are connected in parallel between the raw water tank and the multi-media filter, the first water delivery pipe is connected to the water inlet end of the multi-media filter, and the first backwash water pipe is connected to the water outlet end of the multi-media filter; The first water delivery pipe is provided with a raw water pump, and the first backwash water pipe is provided with a multi-media backwash water pump.

3. The electronic grade ultrapure water preparation system according to claim 2, characterized in that: A second water pipe and a second backwash water pipe are connected in parallel between the ultrafiltration device and the ultrafiltration water tank, the second water pipe is connected to the water inlet side of the ultrafiltration water tank, and the second backwash water pipe is connected to the water outlet side of the ultrafiltration water tank; The second backwash water pipe is provided with an ultrafiltration dosing device and an ultrafiltration backwash water pump.

4. The electronic grade ultrapure water preparation system according to claim 3, characterized in that: The primary reverse osmosis device comprises an RO booster pump, a reverse osmosis dosing device, a first security filter, a primary high-pressure pump, a primary reverse osmosis membrane group and a primary RO water tank, which are sequentially connected to the water outlet side of the ultrafiltration water tank. The purified water outlet end of the primary reverse osmosis membrane group is connected to the primary RO water tank, and the concentrated water outlet end is connected to the RO concentrated water tank. The secondary reverse osmosis device includes a secondary high-pressure pump, a primary reverse osmosis membrane group and a secondary RO water tank which are sequentially connected to the water outlet side of the primary RO water tank. The clean water outlet end of the secondary reverse osmosis membrane group is connected to the secondary RO water tank, and the concentrated water outlet end is connected to the RO concentrated water tank.

5. The electronic grade ultrapure water preparation system according to claim 4, characterized in that: The water outlet side of the secondary RO water tank is connected to the UV ultraviolet sterilization device, and a lifting pump is provided between the secondary RO water tank and the UV ultraviolet sterilization device; A second safety filter is arranged between the UV sterilization device and the EDI device.

6. The electronic grade ultrapure water preparation system according to claim 5, characterized in that: The EDI device is also provided with an EDI water return pipe, which is connected to the water inlet side of the RO concentrated water tank, and an EDI water return valve is provided on the EDI water return pipe.

7. The electronic grade ultrapure water preparation system according to claim 6, characterized in that: A concentrate pump, an antiscalant dosing device and a third safety filter are sequentially arranged between the outlet side of the RO concentrate tank and the electric drive membrane device.

8. The electronic grade ultrapure water preparation system according to claim 7, characterized in that: The purified water outlet of the concentrated water reverse osmosis device is connected to the raw water tank, and the concentrated water outlet of the concentrated water reverse osmosis device is connected in parallel with a concentrated water outlet pipe and a concentrated water return pipe; The concentrated water return pipe is connected to the RO concentrated water tank, and a concentrated water return valve is provided on the concentrated water return pipe; The concentrated water outlet pipe is connected to the concentrated water drainage tank, and a drainage valve is arranged on the concentrated water outlet pipe.

9. A process for preparing electronic grade ultrapure water, characterized in that: The system according to any one of claims 1 to 8 is used to prepare ultrapure water, and the process comprises the following steps: S1. The water in the raw water tank is transported to the multi-media filter through the raw water pump. The filtered water passes through the bag filter and then enters the plate heat exchanger. The water temperature is controlled at 25℃±1 through the plate heat exchanger. S2. The outlet water of the plate heat exchanger passes through the primary reverse osmosis device and the secondary reverse osmosis device in turn and then enters the EDI device. The reverse osmosis concentrated water produced by the primary reverse osmosis device and the secondary reverse osmosis device enters the RO concentrated water tank for collection; S4. Part of the effluent from the EDI device enters the RO concentrated water tank through the EDI return pipe, and the rest of the effluent enters the TOC remover; the effluent from the TOC remover passes through the polishing mixed bed and the terminal filter in turn to obtain electronic grade ultrapure water; S5. The water in the RO concentrated water tank passes through the concentrated water pump and the third safety filter in turn and then enters the concentrated water reverse osmosis device. The clean water produced by the concentrated water reverse osmosis device enters the raw water tank. A part of the concentrated water produced by the concentrated water reverse osmosis device returns to the RO concentrated water tank through the concentrated water return pipe, and the remaining part enters the drainage concentrated water tank through the concentrated water outlet pipe. The water in the drainage concentrated water tank is discharged.

10. The process for preparing electronic grade ultrapure water according to claim 9, characterized in that: in, When the multi-media filter needs to be shut down for backwashing, the multi-media backwashing water pump uses the water in the raw water tank to backwash the multi-media filter; When the ultrafiltration device needs to be shut down for backwashing, a cleaning agent is added to the ultrafiltration dosing device, and the ultrafiltration device is backwashed using water in the ultrafiltration water tank through an ultrafiltration backwash water pump.

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