JP7306074B2 - Ultrapure water production device and ultrapure water production method - Google Patents

Description

The present invention relates to an ultrapure water producing apparatus for producing ultrapure water used in the electronic industry such as semiconductors and liquid crystals, and a method for producing ultrapure water using this ultrapure water producing apparatus.

Conventionally, ultrapure water used in the electronic industry field such as semiconductors has a pretreatment system 2, a primary pure water production device 3, and a secondary pure water production device (sub) for processing the primary pure water, as shown in FIG. system) 4 by treating raw water (industrial water, city water, well water, etc.) W in an ultrapure water production apparatus 1.

Suspended solids and colloidal substances in the raw water W are removed in the pretreatment system 2 comprising coagulation, pressure flotation (sedimentation), filtration (membrane filtration) devices, and the like. In this process, it is also possible to remove polymeric organic substances, hydrophobic organic substances, and the like.

The primary pure water production device 3 includes a tank 11 for pretreated water W0, a preheater 15, a heat exchanger 16, a reverse osmosis membrane device (RO device) 12, an ion exchange device (mixed bed type or 4 bed 5 tower type etc.) 13 and a deaerator 14 . This primary pure water manufacturing apparatus 3 removes ions and organic components from the raw water. It should be noted that the higher the temperature of water, the lower the viscosity and the higher the permeability of a membrane device. For this reason, as shown in FIG. 2, a preheater 15 and a heat exchanger 16 are installed upstream of the reverse osmosis membrane device 12, and by controlling the outlet water of the heat exchanger 16 to a predetermined temperature, The viscosity of the water is reduced, the temperature of the water supplied to the reverse osmosis membrane device 12, the ion exchange device 13 and the degassing device 14 is heated to a predetermined temperature or higher, and the water is supplied to the secondary pure water production device 4. Primary pure water W1, which is supplied water, is controlled to a predetermined temperature. Steam is supplied to the primary side of the heat exchanger 16 as a heat source fluid. In the reverse osmosis membrane device 12, the water to be treated is treated at a predetermined recovery rate to remove salts and ionic and colloidal TOC, while discharging concentrated water W3. The ion exchange device 13 removes salts and TOC components adsorbed or ion-exchanged by the ion exchange resin. Then, the deaerator 14 removes inorganic carbon (IC) and dissolved oxygen.

Primary pure water W<b>1 produced by the primary pure water production system is sent to the secondary pure water production system 4 via pipe 17 . This secondary pure water production device 4 includes a primary pure water tank 21, a pump 22, a heat exchanger 23, a low-pressure ultraviolet oxidation device (UV oxidation device) 24, a non-regenerative ion exchange device 25 and an ultrafiltration membrane (UF membrane) 26. In the low-pressure ultraviolet oxidizer 24, TOC is decomposed into organic acids and CO ₂ by ultraviolet rays of 185 nm emitted from a low-pressure ultraviolet lamp. Organic matter and CO ₂ generated by the decomposition are removed in the subsequent ion exchange device 25 . The ultrafiltration membrane device 26 removes fine particles and also removes effluent particles from the ion exchange resin.

The ultrapure water W2 produced by the secondary pure water production device 4 is sent to the point of use 5 via a pipe 27, and unused ultrapure water is returned to the primary pure water tank 21 via a pipe 28. . If the pressure of the pump 22 is insufficient, a booster pump may be installed upstream of the ion exchange device 25 (for example, between the UV oxidation device 24 and the ion exchange device 25).

The heat exchanger 23 is for setting the water temperature of the ultrapure water W2 sent from the secondary pure water production device 4 to the point of use 5 to a predetermined temperature (for example, about 25°C). In general, the ultrapure water W2 produced by the secondary pure water production device 4 is supplied to the point of use 5, and surplus ultrapure water W2 (unused) is returned from the point of use 5 to the secondary pure water production device 4. , is processed again in the secondary pure water production device 4 and circulated while maintaining a constant ultrapure water quality. The constant circulation prevents the water from stagnation and suppresses the propagation of microorganisms. During this circulation, the temperature of the circulating ultrapure water rises due to the heat of the ultraviolet irradiation lamp of the pump 22 and the low-pressure ultraviolet oxidation device 24, and the heat is removed by the heat exchanger 23, and the water temperature of the circulating ultrapure water is set to a predetermined value. Maintain at temperature.

The ultrapure water W2 from the secondary pure water production system 4 may be further treated in a tertiary pure water production system to further reduce the impurity concentration. As the tertiary pure water production device, one having the same configuration as the secondary pure water production device can be used.

As an ultrapure water production apparatus that heats the pretreated water W0 as described above with a preheater 15 and a heat exchanger 16 at the front stage of the reverse osmosis membrane device (RO device) 12, for example, the one shown in Patent Document 1 is proposed. It is

JP 2013-119060 A

However, in recent years, there has been a demand for energy saving in a primary pure water production apparatus (ultra-pure water production apparatus) that heats pretreated water W0 with a conventional heat exchanger. It is desirable to be able to reduce consumption.

The present invention has been made in view of the above problems, and provides an ultrapure water production apparatus and an ultrapure water production method using the same that can reduce the energy consumption of heat exchangers compared to conventional ones. for the purpose.

In view of the above object, the present invention firstly provides a primary pure water production system equipped with a heat exchanger and reverse osmosis membrane separation means, and a secondary water purification system for treating the primary pure water obtained from the primary pure water production system. and a water production device, wherein the heat exchanger is provided downstream of the reverse osmosis membrane separation means (Invention 1).

According to this invention (Invention 1), it is possible to heat the treated water of the reverse osmosis membrane separation means with a heat exchanger, and compared with the case of heating the feed water of the reverse osmosis membrane separation means, the reverse The amount of heat source fluid used in the heat exchanger can be reduced according to the recovery rate of the permeable membrane separation means.

In the above invention (Invention 1), the flow rate detection means and the temperature detection means of the treated water of the reverse osmosis membrane separation means, the means for setting the target temperature of the outlet water of the heat exchanger, the flow rate detection means and the temperature detection means and means for controlling the supply amount of the heat source fluid to the heat exchanger so as to achieve the target temperature based on the flow rate and temperature detected by the detection means (Invention 2).

According to this invention (Invention 2), the amount of heat source fluid supplied to the heat exchanger can be controlled based on the flow rate and temperature of the treated water of the reverse osmosis membrane separation means, so the amount of heat source fluid used can be further reduced. can be optimized.

Secondly, according to the present invention, primary pure water is produced by passing raw water through a primary pure water producing apparatus equipped with a heat exchanger and reverse osmosis membrane separation means, and secondary pure water is produced from the primary pure water. Provided is a method for producing ultrapure water in which water is passed through a device to produce ultrapure water, in which treated water from a reverse osmosis membrane separation means is heated by a heat exchanger (Invention 3).

According to this invention (Invention 3), by heating the treated water of the reverse osmosis membrane separation means with a heat exchanger, compared with the case of heating the feed water of the reverse osmosis membrane separation means, the reverse osmosis membrane The amount of steam used can be reduced according to the recovery rate of the separation means.

In the invention (invention 3), the flow rate and temperature of the treated water of the reverse osmosis membrane separation means are measured, and the water passing through the heat exchanger reaches the target temperature based on the measured flow rate and temperature. It is preferable to control the amount of heat source fluid supplied to the heat exchanger as follows (Invention 4).

According to this invention (invention 4), by controlling the amount of heat source fluid supplied to the heat exchanger based on the flow rate and temperature of the treated water of the reverse osmosis membrane separation means, the amount of heat source fluid used is further optimized. can be improved.

According to the present invention, the heat exchanger is provided after the reverse osmosis membrane, and the treated water of the reverse osmosis membrane is heated by the heat exchanger, compared with the case of heating the feed water of the reverse osmosis membrane. Therefore, the amount of heat source fluid used can be reduced according to the recovery rate of the reverse osmosis membrane, and the energy consumption of the heat exchanger can be reduced.

1 is a flow diagram showing an ultrapure water production apparatus according to one embodiment of the present invention; FIG. FIG. 3 is a flow diagram showing a conventional ultrapure water production apparatus;

Hereinafter, an ultrapure water production apparatus according to one embodiment of the present invention will be described with reference to the accompanying drawings.

[Ultrapure water production equipment]
FIG. 1 is a flow diagram showing an ultrapure water production system according to one embodiment of the present invention. The same reference numerals are given to the configurations, and detailed descriptions thereof are omitted.

As shown in FIG. 1, the ultrapure water production system 1 of this embodiment is composed of a pretreatment system 2, a primary pure water production system 3, and a secondary pure water production system (subsystem) 4 for processing the primary pure water. be. The pretreatment system 2 includes flocculation, pressure flotation (sedimentation), and filtration (membrane filtration) devices.

The primary pure water production device 3 includes a tank 11 for pretreated water W0, a preheater 15, a reverse osmosis membrane device (RO device) 12 as reverse osmosis membrane separation means, and an ion exchange device (mixed bed type, 4-bed 5 tower type, electrically regenerative ion exchange device (EDI or CDI, etc.) 13 and degassing device 14, and in this embodiment, a heat exchanger 16 is installed after the reverse osmosis membrane device (RO device) 12 are placed. The reverse osmosis membrane used in the reverse osmosis membrane device (RO device) 12 is not particularly limited, but it is desirable to have a wide membrane area and a high flux.

The primary pure water production apparatus 3 includes a flow meter as flow rate detection means for the permeate water W4 of the reverse osmosis membrane apparatus (RO apparatus) 12, a temperature sensor as temperature detection means, and an outlet water W5 of the heat exchanger. A temperature sensor is installed. These flow meter and temperature sensor, the temperature sensor of the outlet water W5 of the heat exchanger 16 and the heat exchanger 16 are connected to control means, and the target temperature of the outlet water W5 of the heat exchanger 16 is controlled by the control means. is set, based on the flow rate and temperature of the permeated water W4 of the reverse osmosis membrane device (RO device) 12 detected by these flow meters and temperature sensors, the heat source fluid to the heat exchanger 16 is adjusted to the target temperature. It is possible to control the supply amount of For convenience, the illustration of the flow meter and temperature sensor for the permeated water W4 and the temperature sensor and control means for the outlet water W5 of the heat exchanger 16 is omitted.

The secondary pure water production device 4 includes a tank 21 for primary pure water W1, a pump 22, a heat exchanger 23, a low-pressure ultraviolet oxidation device (UV oxidation device) 24, and a non-regenerative ion exchange device 25. and an ultrafiltration membrane (UF membrane) 26 .

[Ultrapure water production method]
A method for producing ultrapure water using the ultrapure water production apparatus having the configuration described above will be described.

First, raw water W is supplied to the pretreatment system 2 and treated by coagulation, pressure flotation (sedimentation), filtration (membrane filtration), and the like. Suspended solids and colloidal substances in the raw water W are thereby removed. In addition, the pretreatment system 2 can also remove macromolecular organic substances, hydrophobic organic substances, and the like. In the pretreated water W0 treated here, the number of fine particles in water is usually 10 ³ particles/mL or less.

Next, the pretreated water W0 is temporarily stored in the tank 11 of the primary pure water producing apparatus 3 and then supplied. This reduces the viscosity of the pretreated water W0 and improves the permeability in the reverse osmosis membrane device (RO membrane device) 12 . The heating temperature depends on the temperature of the pretreated water W0, but if the temperature of the water supplied to the reverse osmosis membrane device 12 is less than 18° C., not only does the viscosity of the pretreated water W0 not sufficiently decrease, While a large amount of heat source fluid is required to be supplied in the heat exchanger 16, which will be described later, if the temperature exceeds 22°C, the required amount of energy for heating in the preheater 15 becomes excessive. Just do it.

The pretreated water W0 thus preheated is treated with a reverse osmosis membrane device (RO membrane device) 12 at a predetermined recovery rate to remove salts and to remove ionic and colloidal TOC, while concentrating Water W3 is discharged. The recovery rate of the reverse osmosis membrane device (RO membrane device) 12 depends on the pretreated water W0 and the primary pure water W1, but is about 60 to 90% by volume, particularly about 70 to 80% by volume. Therefore, the amount of the permeated water W4 of the reverse osmosis membrane device (RO membrane device) 12 is smaller than that of the pretreated water W0 by an amount corresponding to the integrated recovery rate. At this time, it is preferable to add a slime control agent or an anti-scaling agent in order to prevent slime and scale troubles in the reverse osmosis membrane.

Subsequently, the RO membrane permeated water W4 is heated again by the heat exchanger 16 to produce outlet water W5 at a predetermined temperature. The temperature at which the RO membrane permeated water W4 is heated depends on the required water temperature of the ultrapure water W2. If it exceeds, a large amount of heat source fluid is required to be supplied to the heat exchanger 16, so the temperature should be about 23 to 27°C, for example, about 25°C.

Specifically, the target temperature of the outlet water W5 of the heat exchanger 16 is input to the control means, and the flow rate and temperature of the permeated water W4 of the reverse osmosis membrane device (RO device) 12 are measured by a flow meter and a temperature sensor, respectively. Based on this measured value, the supply amount of the heat source fluid to the heat exchanger 16 is determined so as to achieve the target temperature, and the supply amount of the heat source fluid is controlled based on the measured value of the temperature sensor of the outlet water W5. Just do it.

By heating the RO membrane permeated water W4 in the heat exchanger 16 in this way, the permeated water W4 of the reverse osmosis membrane device 12 has a higher recovery rate than the pretreated water W0 (supply water of the reverse osmosis membrane device 12). Since the amount is smaller by the integrated amount, the amount of heat source fluid supplied to the heat exchanger 16 can be reduced compared to the case where the water supplied to the reverse osmosis membrane device 12 is heated by the heat exchanger 16. , the energy consumption in the heat exchanger can be reduced. Moreover, since the heat exchanger 16 heats the primary pure water W1 at a position closer to the discharge side, the supply temperature of the primary pure water W1 can be controlled more accurately.

After that, the ion exchange device 13 removes salts and the TOC components adsorbed or ion-exchanged by the ion exchange resin, and the degassing device 14 removes inorganic carbon (IC) and dissolved oxygen. A primary pure water W1 is produced.

The produced primary pure water W1 is then sent to the secondary pure water producing device 4 through the pipe 17 and temporarily stored in the primary pure water tank 21 . Then, in the low-pressure ultraviolet oxidizer 24, a trace amount of remaining TOC is decomposed into organic acids and further CO ₂ by ultraviolet rays of 185 nm emitted from a low-pressure ultraviolet lamp. Organic matter and CO ₂ generated by the decomposition are removed in the subsequent ion exchange device 25 . The ultrafiltration membrane device 26 removes fine particles and also removes effluent particles from the ion exchange resin. Thus, ultrapure water W2 can be produced.

The ultrapure water W2 produced by the secondary pure water production device 4 is sent to the point of use 5 via a pipe 27, and unused ultrapure water is returned to the primary pure water tank 21 via a pipe 28. . In the heat exchanger 23, the water temperature of the ultrapure water W2 may rise due to the heat of the UV irradiation lamp of the pump 22 and the low-pressure UV oxidation device 24 as the ultrapure water W2 is circulated as described above. Therefore, in such a case, heat is taken by the heat exchanger 23 to maintain the water temperature of the circulating ultrapure water W2 at a predetermined temperature.

Although the present invention has been described above based on the above-described embodiments, the present invention is not limited to the above-described embodiments, and various modifications are possible. Various configurations are possible without being limited to the configuration of the embodiment. For example, in the primary pure water production system 3 , reverse osmosis (RO) membranes 12 may be arranged in series in two stages, and one of the permeated water may be heated by the heat exchanger 16 . Furthermore, a tertiary pure water device may be further provided after the secondary pure water production device 4 .

EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[Comparative Example 1]
Using the ultrapure water production apparatus 1 shown in FIG. 2, raw water W was treated by a pretreatment apparatus 2, a primary pure water production apparatus 3 and a secondary pure water production apparatus 4 to produce ultrapure water W2.

At this time, 10 m ³ /h of pretreated water W0 as feed water for the primary pure water production apparatus 3 is heated to 20° C. in the preheater 15, and further heated to 25° C. in the heat exchanger 16. The water was treated with an apparatus (RO apparatus) 12 at a recovery rate of 70% by volume to obtain RO membrane permeated water W4. The required amount of heat in the heat exchanger 16 at this time was 210 [MJ/h].

[Example 1]
Using the ultrapure water production apparatus 1 shown in FIG. 1, raw water W was treated with a pretreatment apparatus 2, a primary pure water production apparatus 3 and a secondary pure water production apparatus 4 to produce ultrapure water W2.

At this time, after heating 10 m ³ /h of pretreated water W0 to 20° C. in the preheater 15 as the feed water for the primary pure water production device 3, the reverse osmosis membrane device (RO device) 12 was used with a recovery rate of 70% by volume. processed. This RO membrane permeated water W4 was further heated to 25° C. by the heat exchanger 16 . The required amount of heat in the heat exchanger 16 at this time was 147 [MJ/h].

On the other hand, the increase in power consumption of the reverse osmosis membrane device 12 due to lowering the treated water of the reverse osmosis membrane device 12 from 25 ° C. to 20 ° C. is 0.8 m / d (at 0.74 MPa ), the temperature correction factors at 20° C. and 25° C. are 0.144 and 1, respectively, which gives inlet pressures of 0.85 MPa and 0.74 MPa, respectively. Therefore, Δ0.09 MPa affects the total head (Δ9 m) due to temperature change.

The power consumption W is obtained by shaft power W/motor efficiency. Assuming that the gravitational acceleration of 9.8 m/S, the pump efficiency of 80%, and the motor efficiency of 80% are constant, the difference in power consumption between Comparative Example 1 and Example 1 is calculated as follows.
Power consumption (W) = 1000 [kg/ ^m3 ] x 9.8 [m/ ^S2 ] x 10 [ ^m3 /h]
× Δ9 [m] ÷ 0.8 ÷ 0.8
= 1.38MJ/h

Therefore, an energy reduction of 61.6 MJ/h can be expected from the increase in power consumption of the reverse osmosis membrane device 12 of 1.38 MJ/h and the amount of heat that can be reduced by the heat exchanger 16 of 63 (210-147) MJ/h. was confirmed.

1 ultrapure water production device 2 pretreatment system 3 primary pure water production device 11 tank 12 reverse osmosis membrane device (RO device)
13 Ion exchange device 14 Deaerator 15 Preheater 16 Heat exchanger 17 Piping 4 Secondary pure water production device (subsystem)
21 primary pure water tank 22 pump 23 heat exchanger 24 low pressure ultraviolet oxidizer (UV oxidizer)
25 Ion exchange device 26 Ultrafiltration membrane (UF membrane)
27 Piping 28 Piping 5 Point of Use W Raw Water W0 Pretreated Water W1 Primary Pure Water W2 Ultrapure Water W3 Concentrated Water W4 RO Membrane Permeated Water W5 Outlet Water

Claims (4)

An ultrapure water production apparatus comprising a primary pure water production apparatus and a secondary pure water production apparatus for processing the primary pure water obtained from the primary pure water production apparatus,
The primary pure water production apparatus comprises a preheater, a reverse osmosis membrane separation means, a first heat exchanger, a mixed-bed or 4-bed 5-tower ion exchanger, and a deaerator in this order,
The secondary pure water production device comprises a second heat exchanger, an ultraviolet oxidation device, an ion exchange device, and an ultrafiltration membrane in this order,
The first heat exchanger heats the treated water of the reverse osmosis membrane separation means to a range of 23 to 27° C. in the ultrapure water production process. Flow rate detection means and temperature detection means of the treated water of the reverse osmosis membrane separation means, means for setting the target temperature of the outlet water of the first heat exchanger, and flow rates detected by these flow rate detection means and temperature detection means and means for controlling the supply amount of the heat source fluid to the first heat exchanger so as to achieve the target temperature based on the temperature. In an ultrapure water production method, raw water is passed through a primary pure water production device to produce primary pure water, and the primary pure water is passed through a secondary pure water production device to produce ultrapure water,
The primary pure water production apparatus comprises a preheater, a reverse osmosis membrane separation means, a first heat exchanger, a mixed-bed or 4-bed 5-tower ion exchanger, and a deaerator in this order,
The secondary pure water production device comprises a second heat exchanger, an ultraviolet oxidation device, an ion exchange device, and an ultrafiltration membrane in this order,
A method for producing ultrapure water, wherein in the ultrapure water production process, the treated water of the reverse osmosis membrane device separation means is heated to a range of 23 to 27° C. by the first heat exchanger. The flow rate and temperature of the treated water of the reverse osmosis membrane separation means are measured, and based on the measured flow rate and temperature, the first heat exchange is performed so that the water passing through the first heat exchanger reaches a target temperature. 4. The method for producing ultrapure water according to claim 3, wherein the amount of heat source fluid supplied to the vessel is controlled.

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