CN219044891U

CN219044891U - Ultrapure water deep boron removal system

Info

Publication number: CN219044891U
Application number: CN202222054544.9U
Authority: CN
Inventors: 戎宇舟; 高康; 陈炜彧; 张�浩; 陈琳媛; 赵浩竹
Original assignee: China Electronics Innovation Environmental Technology Co ltd
Current assignee: China Electronics Innovation Environmental Technology Co ltd
Priority date: 2022-08-05
Filing date: 2022-08-05
Publication date: 2023-05-19
Anticipated expiration: 2032-08-05

Abstract

The utility model discloses an ultrapure water deep boron removal system which sequentially comprises a raw water tank, a raw water tank heat exchanger, a filtering unit, a pH adjusting water tank, a UV sterilizer, a cartridge filter, a reverse osmosis unit, a TOC-UV device, an EDI device, a primary degassing membrane device and an ultrapure water tank, and further comprises a boron removal device arranged between the pH adjusting water tank and the UV sterilizer; the boron removing device comprises a silicon dioxide layer and a boron removing functional layer, and the boron removing functional layer is positioned on the silicon dioxide layer; the boron removal device of the system is arranged at the front end of the system, and the boron removal efficiency is high and the TOC content in water is effectively controlled through the synergistic effect of the boron removal device, the reverse osmosis unit and the EDI device.

Description

Ultrapure water deep boron removal system

Technical Field

The utility model relates to a water treatment system, in particular to an ultrapure water deep boron removal system.

Background

In the related art, in the field of manufacturing electronic devices such as semiconductors and liquid crystal panels, a large amount of ultrapure water containing a very small amount of impurities, ions and organic substances is required to be used for cleaning products. Among them, in the manufacturing process of semiconductors, there is an increasing demand for ultrapure water to be used with the reduction of the production of semiconductors and the expansion of wafer sizes. With the gradual increase of water quality requirements, the requirement for boron in ultrapure water is gradually increased, and boron is a p-type impurity, and most of the boron can invert n-type silicon and influence carrier concentration, so that the yield of products in the semiconductor manufacturing process is influenced.

Boron (B) is the only nonmetallic element in the third main group of the periodic table, the valence electron structure of B atoms is 2s22p1, and the valence electrons of B atoms are less than the valence orbit number, so that the situation of electron deficiency exists, but boron has the characteristics of small atomic radius, high ionization energy and large electronegativity compared with the metallic element lithium and beryllium in the same period, and covalent bond molecules are formed. In the ultrapure water production system, boron removal mainly depends on a reverse osmosis unit and an ion exchange resin unit, but in the case of low pH, B exists in the form of boric acid, the removal efficiency of reverse osmosis is low (a common reverse osmosis membrane, the removal rate is about 80% at ph=9), and chemical cleaning causes significant degradation of the boron removal efficiency; in the selectivity table of the ion exchange resin, the selectivity of B is low, and hydroxide in the ion exchange resin is difficult to exchange, so that the removal rate of the ion exchange resin to boron is lower than that of common ions, the fluctuation of B can cause the ion exchange resin to be easily penetrated by B, and the removal effect of boron is drastically reduced.

Because the two-stage reverse osmosis membrane and EDI device has poor boron removal effect and cannot meet the requirement of ultrapure water on boron, the boron removal process in the ultrapure water manufacturing system mainly adopts an ion exchange resin mode, adopts a process of a cation exchange resin tower, an anion exchange resin tower, reverse osmosis, a boron removal anion bed and a mixed bed ion exchange resin tower, needs frequent regeneration of the ion exchange resin, discharges a large amount of regenerated waste liquid, and still cannot realize efficient boron removal. When the requirement on boron is extremely high (less than 10 ppt), a set of boron removal resin tower is required to be arranged behind the pure water tank to protect the boron, and the resin structure is extremely easy to damage in the regeneration process, so that a large amount of TOC is dissolved out, and TOC in the terminal water is easy to exceed the standard.

Disclosure of Invention

The utility model aims to: the utility model aims to provide an ultrapure water deep boron removal system, wherein a boron removal device is arranged at the front end of the system, and the boron removal efficiency is high through the cooperation of the boron removal device, a reverse osmosis unit and an EDI device, so that the TOC content in water is effectively controlled; the problem of boron removal efficiency is not high among the prior art, because boron removal resin sets up in pure water tank rear end and causes the TOC exceeds standard in the water is solved.

The technical scheme is as follows: the ultra-pure water deep boron removal system comprises a raw water tank, a raw water tank heat exchanger, a filtering unit, a pH adjusting water tank, a UV sterilizer, a cartridge filter, a reverse osmosis unit, a TOC-UV device, an EDI device, a primary degassing membrane device and an ultra-pure water tank in sequence, and further comprises a boron removal device arranged between the pH adjusting water tank and the UV sterilizer; the boron removing device comprises a silicon dioxide layer and a boron removing functional layer, and the boron removing functional layer is arranged on the silicon dioxide layer.

Preferably, the filter unit comprises a multi-medium filter, a decarbonizing acid tower and an activated carbon filter, wherein the multi-medium filter is filled with anthracite, quartz sand and gravel, and the activated carbon filter is filled with activated carbon and quartz sand. Raw water enters a raw water tank, the water in the raw water tank passes through a raw water heat exchanger through a water pump to adjust the water temperature, and then enters a multi-medium filter, a decarbonizing acid tower and an active carbon filter, and the raw water tank is mainly used for removing impurities, partial organic matters, alkalinity, residual chlorine and the like in the water so as to protect RO membranes in a rear reverse osmosis unit from oxidation and organic matter pollution.

The produced water of the activated carbon filter enters a pH adjusting water tank, and sodium hydroxide is added to adjust the pH of the water to 7.0, so that the neutrality of the water in the subsequent treatment is ensured.

The water from the pH adjusting water tank passes through the boron removing device, boric acid is combined with calcium phosphoramidate on the boron removing functional layer, so that boron is removed, the concentration of boron in the produced water passing through the boron removing device is ensured to be lower continuously and stably, the water speed is in the range of 60-120BV/h, generally 80/h can be selected, and the concentration of boron in the produced water passing through the boron removing device is less than 10ng/L. The mesoporous silica layer on the boron removing device has larger specific surface area, the boron removing functional layer is calcium amino phosphate silane coupling agent, the boron removing functional layer is grafted on the silica layer by a chemical method, and the specific surface area is 50-1500 m ² ·g ^-1 Pore volume of 0.05-1 ml.g ^-1 Pore diameter is 2-20 nm, adsorption capacity is 0.5-4 mmol.g ^-1 Has better stability under the condition of water flushing, lower dissolved TOC and good regeneration performance.

The amino calcium phosphate silane coupling agent is prepared from amino silane coupling agent, phosphoric acid and calcium hydroxide in a mass ratio of 1:0.5 to 2: 2-10, reacting for 1-4 hours at 200-400 ℃, wherein the inert organic solvent is cyclohexane, heptane, toluene, xylene and the like.

The method for grafting the calcium phosphoramidate silane coupling agent on the silicon dioxide layer comprises the following steps: mesoporous silica material and calcium phosphoramidate silane coupling agent are mixed according to the mass ratio of 1: 2-10 in inert solvent, under 200-400 deg. C, under argon atmosphere for 2-10 h, the inert organic solvent is one of cyclohexane, heptane, N-dimethyl amide and toluene.

The regeneration period of the boron removal functional layer in the boron removal device is generally controlled to be 20-40 days, and the regeneration method comprises the following steps: firstly, 1-8% hydrochloric acid with the concentration of 1-5 BV is used for elution operation, and then 1-8% sodium hydroxide with the concentration of 1-5 BV is used for regeneration.

The water produced by the boron removing device is sterilized by a UV sterilizer, and the UV sterilizer adopts 254nm ultraviolet rays for sterilization.

The pore size of the filtration membrane in the preferred cartridge filter is 2 to 10. Mu.m. The effluent of the UV sterilizer passes through a cartridge filter to filter out suspended particulate matters and colloid.

Preferably, the reverse osmosis unit comprises a first-stage reverse osmosis device, a first-stage RO water producing tank, a second-stage reverse osmosis device and a second-stage RO water producing tank which are sequentially connected in series, wherein the first-stage reverse osmosis device adopts a desalination reverse osmosis membrane, and the second-stage reverse osmosis device adopts a low-pressure high-flux reverse osmosis membrane. The reverse osmosis unit is used for removing anions and cations in water and organic matters in water. The water from the cartridge filter enters a two-stage reverse osmosis system, the two-stage reverse osmosis device adopts a reverse osmosis membrane element with high desalination rate and low energy consumption, the water inlet pressure is more than 1.0MPa, the water recovery rate of the first-stage reverse osmosis system can reach 80-85%, the water recovery rate of the second-stage reverse osmosis system can reach 85-95%, the TDS of produced water is 0.2-1mg/L, the TOC is 10-50 mug/L, and the produced water enters an RO pool.

The water in the RO water tank enters a TOC-UV device, the TOC-UV device adopts 185nm ultraviolet light, and 185nm ultraviolet light can effectively decompose TOC in the water; then the water enters an EDI device, the device utilizes the mixed ion exchange resin to adsorb anions and cations in the water, and the adsorbed anions are removed through the anion and cation exchange membranes respectively under the action of direct current voltage.

The water produced by the EDI device passes through the first-stage degassing membrane device, dissolved oxygen in the water is removed, the produced water directly enters the pure water tank, and the pure water tank adopts a nitrogen sealing mode to prevent other gases from being dissolved in the water.

Preferably, the ultrapure water tank is also connected with a pure water heat exchanger, a TOC-UV device, a mixed bed type ion exchange device, a secondary dehydration membrane device and a terminal ultrafiltration device; the terminal ultrafiltration device is connected with the water point, the water discharged from the terminal ultrafiltration device is sent to the water point to be directly used, and the unused water returns to the pure water tank to continue circulating. The water in the ultra-pure water tank is firstly subjected to temperature regulation to the temperature required by a water consumption point through a pure water heat exchanger; the TOC-UV device is used for decomposing TOC in water again by ultraviolet light of 185 nm; trace anions and cations and partial organic matters in water are removed by a mixed bed type ion exchange device, the resin of the mixed bed type ion exchange device does not need to be regenerated, and the resistivity of the yielding water is stabilized to be above 18.2MΩ & cm; the effluent enters a second-stage degassing membrane device, and dissolved oxygen in the water is removed again; finally, directly supplying the ultra-filtered treatment to an ultra-pure water point, and returning the unused ultra-pure water at the point of use to a pure water tank for circulation; wherein the speed of water introduced into the mixed bed type ion exchange device is in the range of 50/h to 100/h, and generally 80/h can be selected.

The beneficial effects are that: compared with the prior art, the utility model has the following advantages: (1) The boron removing device of the system is arranged at the front end of the system, and the boron removing efficiency is high through the synergistic effect of the boron removing device, the reverse osmosis unit and the EDI device, so that the TOC content in water is effectively controlled; (2) The boron removing device in the system has the advantages of high boron removing efficiency of the boron removing functional layer, reproducibility and low TOC dissolution.

Drawings

FIG. 1 is a process flow diagram of the system of the present utility model.

Detailed Description

The technical scheme of the utility model is further described below with reference to the accompanying drawings.

Example 1

The ultra-pure water deep boron removal system comprises a raw water tank, a raw water tank heat exchanger, a multi-medium filter, a decarbonizing acid tower, an active carbon filter, a pH adjusting water tank, a boron removal device, a UV sterilizer, a security filter, a primary reverse osmosis, a primary RO water producing tank, a secondary reverse osmosis, a secondary RO water producing tank, a TOC-UV device, an EDI device, a primary degassing membrane device, an ultra-pure water tank, a pure water heat exchanger, a TOC-UV device, a mixed bed ion exchange device, a secondary degassing membrane device, a terminal ultrafiltration device and a water consumption point.

The boron removing device comprises a mesoporous silicon dioxide layer and a boron removing functional layer calcium phosphoramidate silane coupling agent grafted on the silicon dioxide layer. The amino-calcium phosphate silane coupling agent adopts amino-silane coupling agent, phosphoric acid and calcium hydroxide according to the mass ratio of 1:1.55:5, in cyclohexane, at 300℃for 2.5 hours. Mesoporous silica material and calcium phosphoramidate silane coupling agent are mixed according to the mass ratio of 1:2.5, in cyclohexane, under 300 ℃ and argon atmosphere, for 5 hours.

The first-stage reverse osmosis system adopts a desalination reverse osmosis membrane, and the second-stage reverse osmosis system adopts a low-pressure high-flux reverse osmosis membrane.

Anthracite, quartz sand and gravel are filled in the multi-medium filter, and activated carbon and quartz sand are filled in the activated carbon filter.

Raw water: raw water of a certain 12-inch integrated circuit semiconductor manufacturing factory has pH of 6.5-7.5, conductivity of 320-380 mu S/cm, TOC of 2-2.5mg/L and boron of 50-100 mu g/L.

Raw water enters a raw water tank, the water temperature is adjusted to 23 ℃ through a raw water heat exchanger, hydrochloric acid is added to adjust the pH value to 6.8 through a pipeline mixer before the raw water enters a multi-medium filter, sodium hypochlorite and polyaluminium chloride (PAC) are added simultaneously, and the turbidity of filtered water through the multi-medium filter is less than 0.01NTU.

The pH value of the inlet water of the decarbonizing acid tower is regulated to 3.5 by a pipeline mixer, then the produced water of the decarbonizing acid tower enters an active carbon filter, the residual chlorine of the outlet water of the active carbon filter is less than 0.1mg/L, and the produced water enters a pH regulating water tank.

And the pH value of the water tank is regulated to 7.0, and then the water tank enters a boron removing device, wherein the volume of the mesoporous silica layer and the boron removing functional layer is 3000L, the boron concentration of water entering the boron removing device is 50-100 mu g/L, and the water yield is less than 50ng/L. When the boron removing device regenerates, 2-4 BV of 5% hydrochloric acid is used for eluting, and then 2-4 BV of 5% sodium hydroxide solution is used for regenerating, wherein the regeneration period is 30 days.

The water produced by the boron removing device enters a UV sterilizer, and the UV sterilizer kills bacteria in the water by adopting 254nm ultraviolet rays. The water of the UV sterilizer enters a cartridge filter, and the cartridge filter adopts a filter core of 5 mu m to intercept impurities in the water and protect a reverse osmosis membrane at the rear.

The produced water of the cartridge filter enters a first-stage reverse osmosis device, the water inlet pressure of the first-stage reverse osmosis device is 1.2mPa, the water inlet TDS is 220-250mg/L, the TOC of the water inlet is 1.5-2mg/L, the recovery rate of the reverse osmosis device is 80%, the TDS of the water outlet is 3-5mg/L, the TOC is 100-150 mug/L, and the produced water enters a first-stage RO water tank.

The effluent of the first-stage RO water tank enters a second-stage reverse osmosis device, the water inlet pressure of the second-stage reverse osmosis device is 1.2mPa, the water inlet TDS is 3-5mg/L, the TOC of the water inlet is 100-150 mug/L, the recovery rate of the reverse osmosis system is 90%, the water outlet TDS is 0.5-1.2mg/L, the TOC is 20-40 mug/L, and the boron is less than 15ng/L, and the produced water enters the second-stage RO water tank.

The effluent of the second-stage RO water tank passes through TOC-UV and enters an EDI device, the water yield of the EDI device is 95%, the water resistivity is more than 17.5MΩ & cm, the TOC is 3-5 mug/L, and the boron is less than 8ng/L. EDI produced water enters the pure water tank through the primary degassing membrane device, and the dissolved oxygen concentration of the water discharged from the primary degassing membrane device is less than 10 mug/L.

The temperature of the effluent of the ultrapure water tank is reduced to 23+/-1 ℃ by a heat exchanger, the resistivity of the effluent of the mixed bed type ion exchange device can be stabilized to be above 18.2MΩ & cm, the TOC of the effluent is less than 0.5 mug/L, and the boron is less than 3ng/L. The water produced by the mixed bed type ion exchange device passes through a secondary degassing membrane device and an ultrafiltration system, namely, the water is sent to a water supply point. The concentration of dissolved oxygen in the terminal effluent is less than 0.8 mu g/L, the particles of the ultra-pure water effluent which is more than or equal to 0.05 mu m after terminal ultrafiltration is less than 100pcs/L, TOC is less than 0.5 mu g/L, and boron is less than 35ng/L.

Claims

1. The ultra-pure water deep boron removal system is characterized by sequentially comprising a raw water tank, a raw water tank heat exchanger, a filtering unit, a pH adjusting water tank, a UV sterilizer, a cartridge filter, a reverse osmosis unit, a TOC-UV device, an EDI device, a primary degassing membrane device and an ultra-pure water tank, and further comprising a boron removal device arranged between the pH adjusting water tank and the UV sterilizer; the boron removing device comprises a silicon dioxide layer and a boron removing functional layer, and the boron removing functional layer is positioned on the silicon dioxide layer; the boron-removing functional layer is a calcium amino phosphate silane coupling agent.

2. The boron removal system of claim 1, wherein the reverse osmosis unit comprises a primary reverse osmosis unit, a primary RO water producing tank, a secondary reverse osmosis unit, and a secondary RO water producing tank in series.

3. The boron removal system of claim 1, wherein the filtration unit comprises a multi-media filter, a decarbonation tower, and an activated carbon filter in series.

4. The boron removal system of claim 1, wherein the silicon dioxide layer is a mesoporous silicon dioxide layer.

5. The boron removal system of claim 1, wherein the cartridge filter has a filter membrane pore size of 2-10 μm.

6. The boron removal system of claim 3, wherein said multi-media filter is filled with anthracite, silica sand and gravel.

7. The boron removal system of claim 3, wherein said activated carbon filter is filled with activated carbon and quartz sand.

8. The boron removal system of claim 1, wherein said ultrapure water tank is further connected to a pure water heat exchanger, a TOC-UV device, a mixed bed ion exchange device, a secondary dewatering membrane device, and a terminal ultrafiltration device; the ultrafiltration device is connected with a water point, and unused water returns to the pure water tank for continuous circulation.