Ultra-pure water production device

Abstract

To ensure an ultrapure water quality while suppressing energy use efficiency.SOLUTION: A ultrapure water system 1A has a primary system S1 and a secondary system S2 located downstream of the primary system S1 and upstream of a use point 2. The ultrapure water system 1A has at least one electrically regenerative deionizer 18, a cooler 17 for cooling the supply water to the electrically regenerative deionizer 18, and a first thermometer 28 which measures the water temperature of water treated in the electric regenerative deionizer 18 and circulating downstream of the electric regenerative deionizer 18. The cooler 17 is activated when the water temperature measured by the first thermometer 28 exceeds a value corresponding to the required water temperature of the use point 2 at the location of the first thermometer 28.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an ultrapure water production apparatus.

Background Art

[0002] In an ultrapure water production apparatus, several water treatment apparatuses such as an electrically regenerative deionization apparatus are arranged in series. Each water treatment apparatus has suitable water temperature conditions, and the temperature of the supply water to each water treatment apparatus is adjusted to an appropriate temperature by a heater or a cooler. For example, Patent Document 1 discloses a water treatment system that adjusts the temperature of the supply water to the electrically regenerative deionization apparatus within a predetermined range based on the temperature of the treated water of the electrically regenerative deionization apparatus.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In an ultrapure water production apparatus, not only the water temperature of the supply water to each water treatment apparatus is kept within a predetermined range, but also the water temperature at the use point, which is the final supply destination of the ultrapure water, is kept within a predetermined required water temperature. However, in order to keep the temperature of the supply water to each water treatment apparatus and the required water temperature at the use point within a predetermined range, it is necessary to repeat heating and cooling of water, and the energy use efficiency in the ultrapure water production apparatus decreases. The decrease in energy use efficiency affects the operating cost.

[0005] An object of the present invention is to provide an ultrapure water production apparatus that can suppress a decrease in energy use efficiency while ensuring the quality of ultrapure water.

Means for Solving the Problems

[0006] The ultrapure water production apparatus of the present invention has a primary system and a secondary system located downstream of the primary system and upstream of the use point. The ultrapure water production apparatus has at least one electrically regenerative deionization device, a cooler for cooling the water supplied to the electrically regenerative deionization device, and a first thermometer for measuring the water temperature of the water treated by the electrically regenerative deionization device and flowing downstream of the electrically regenerative deionization device. When the water temperature measured by the first thermometer exceeds a value corresponding to the required water temperature at the use point at the installation position of the first thermometer, the cooler operates.

Advantages of the Invention

[0007] According to the present invention, it is possible to provide an ultrapure water production apparatus capable of suppressing a decrease in energy use efficiency while ensuring the water quality of ultrapure water.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Modes for Carrying Out the Invention

[0009] Hereinafter, some embodiments of the present invention will be described with reference to the drawings. The ultrapure water production apparatuses 1A to 1F of each embodiment have a primary system S1 and a secondary system S2. The secondary system S2 is located downstream of the primary system S1 and upstream of the use point 2. The primary system S1 produces pure water from raw water, and the secondary system S2 produces ultrapure water from pure water. The ultrapure water produced by the secondary system S2 is sent to the use point 2. Among the ultrapure water produced by the secondary system S2, the ultrapure water not used at the use point 2 is returned upstream by a recirculation line L3 connected to the main pipe L2 of the secondary system S2. In the secondary system S2, pure water or ultrapure water is constantly circulating. The secondary system S2 is the range in which pure water or ultrapure water circulates, and includes the main pipe L2 and the recirculation line L3, and all the facilities installed on the main pipe L2 and the recirculation line L3. The use point 2 is connected to the ultrapure water production apparatus 1 by a line L4 branched from the main pipe L2.

[0010] (First Embodiment) Fig. 1 shows a schematic configuration of the ultrapure water production apparatus 1A according to the first embodiment of the present invention. As described above, since the ultrapure water production apparatus 1A is divided into a primary system S1 and a secondary system S2, first, the primary system S1 will be described, and then the secondary system S2 will be described. Each apparatus of the primary system S1 and the secondary system S2 is monitored and controlled by the control apparatus 3 of the ultrapure water production apparatus 1A. Note that the apparatuses constituting the primary system S1 and the secondary system S2 are not limited to those described below, and other tanks, pumps, etc. may be installed as necessary.

[0011] In the primary system S1, along the main pipe L1 through which the water to be treated flows, in the direction of flow of the water to be treated, from upstream to downstream, there are arranged in series a raw water tank 11, a raw water pump 12, a temperature adjusting device 13, at least one reverse osmosis membrane device 14, a filtered water tank 15, a filtered water pump 16, a cooler 17, and at least one electrically regenerable deionization device 18 (EDI). At least one reverse osmosis membrane device 14 includes both a single-stage reverse osmosis membrane device and a multi-stage reverse osmosis membrane device connected in series, and in the following description, it is simply referred to as the reverse osmosis membrane device 14. At least one electrically regenerable deionization device 18 includes both a single-stage electrically regenerable deionization device and a multi-stage electrically regenerable deionization device connected in series, and in the following description, it is simply referred to as the electrically regenerable deionization device 18. By arranging in series a plurality of at least one of the reverse osmosis membrane device 14 and the electrically regenerable deionization device 18, further improvement in water quality can be achieved. Although not shown in the figure, between the reverse osmosis membrane device 14 and the electrically regenerable deionization device 18, at least one of a membrane degassing device, an ion exchange resin device, an ultraviolet irradiation device, and a boron-selective resin device for removing carbonic acid and dissolved oxygen may be provided.

[0012] The raw water tank 11 stores raw water produced by a pretreatment system (not shown) provided upstream of the primary system S1, and water recovered after being generated in the subsequent equipment (pure water, ultrapure water, concentrated water of the electro-regenerative deionizer 18, electrode water, etc.). The raw water contains boron. The raw water pump 12 sends out the raw water stored in the raw water tank 11 and supplies it to the temperature adjustment device 13. The temperature adjustment device 13 heats or cools the water supplied to the reverse osmosis membrane device 14 to a predetermined temperature. If the water temperature of the water supplied to the reverse osmosis membrane device 14 is too low, the viscosity of the supplied water increases, and it becomes difficult for the supplied water to permeate through the reverse osmosis membrane device 14. As a result, the pressure loss of the reverse osmosis membrane device 14 increases, and there is a possibility that the power consumption and pump capacity of the raw water pump 12 increase. Also, if the flow rate per element of the reverse osmosis membrane device 14 is reduced to reduce the pressure loss, the number of elements increases. On the other hand, if the water temperature of the water supplied to the reverse osmosis membrane device 14 is too high, problems such as elution of the membrane material, precipitation of dissolved components in the supplied water, and generation of bio-derived slime are likely to occur. The temperature adjustment device 13 adjusts the water temperature of the water supplied to the reverse osmosis membrane device 14 to 15°C or higher and 40°C or lower, preferably about 20 to 30°C. In this embodiment, since the water temperature of the water supplied to the reverse osmosis membrane device 14 is lower than the predetermined temperature range (for example, the above-mentioned 15 to 40°C or 20 to 30°C), the temperature adjustment device 13 operates as a heater. However, when the water temperature of the water supplied to the reverse osmosis membrane device 14 fluctuates within the above-mentioned predetermined temperature range, or when it fluctuates inside and outside the above-mentioned predetermined temperature, a temperature controller having a heating and cooling function may be used. When the water temperature of the water supplied to the reverse osmosis membrane device 14 fluctuates within the above-mentioned predetermined temperature range, the temperature adjustment device 13 can also be omitted. Conversely, when the water temperature of the water supplied to the reverse osmosis membrane device 14 is higher than the above-mentioned predetermined temperature range, the temperature adjustment device 13 can be a cooler.

[0013] The treated water of the reverse osmosis membrane device 14 is stored in the filtered water tank 15. The filtered water pump 16 sends out the filtered water stored in the filtered water tank 15 and supplies it to the cooler 17. The cooler 17 provided upstream of the electrically regenerable deionizer 18 cools the feed water to the electrically regenerable deionizer 18 to a predetermined temperature. As will be described later, when the temperature of the feed water to the electrically regenerable deionizer 18 is low, the boron removal rate is improved. The predetermined temperature is about 10 to 30°C, preferably about 15 to 24°C. The electrically regenerable deionizer 18 removes ionic components contained in the water to be treated. The electrically regenerable deionizer 18 also removes boron contained in the water to be treated. The treated water of the electrically regenerable deionizer 18 is stored in the sub-tank 19 of the secondary system S2. A boron concentration measuring device 27 for measuring the boron concentration of the treated water of the electrically regenerable deionizer 18 is provided downstream of the electrically regenerable deionizer 18, specifically, between the electrically regenerable deionizer 18 and the sub-tank 19.

[0014] In the secondary system S2, along the main pipe L2 through which the water to be treated flows, in the direction of flow of the water to be treated, from upstream to downstream, a sub-tank (pure water tank) 19, a pure water pump 20, a heat exchanger 21, an ultraviolet irradiation device 22, an ion exchange device 23, a membrane degassing device 24, and an ultrafiltration membrane device 25 are arranged in series. The pure water pump 20 sends out the pure water stored in the sub-tank 19 and supplies it to the heat exchanger 21. Generally, the required water temperature (for example, about 24 to 26 °C) is determined for the ultrapure water supplied to the use point 2. The heat exchanger 21 is provided to adjust the temperature of the ultrapure water supplied to the use point 2. When the water supplied to the electrically regenerated deionizer 18 is cooled by the cooler 17, since the heat exchanger 21 generally heats the water to be treated, it can be used as a heater. However, when the water temperature of the water to be treated rises due to the heat input from the electrically regenerated deionizer 18, the waste heat from the pure water pump 20, or the increase in the amount of circulating water flowing through the recirculation line L3, the heat exchanger 21 may also cool the water to be treated. Therefore, when there is a possibility of cooling the water to be treated (especially when T1 - T2 described later becomes negative), it is preferable that the heat exchanger 21 is capable of both cooling and heating. The ultraviolet irradiation device 22 irradiates the water to be treated with ultraviolet rays to decompose the organic substances contained in the water to be treated. The ion exchange device 23 removes the decomposition products generated by the ultraviolet irradiation device 22. The membrane degassing device 24 removes the dissolved oxygen contained in the water to be treated. The ultrafiltration membrane device 25 removes the fine particles contained in the water to be treated. The ultrapure water thus produced is sent to the use point 2, and the water not used at the use point 2 is returned to the sub-tank 19 through the recirculation line L3.

[0015] The ultrapure water production apparatus 1A has a first thermometer 28 and a second thermometer 26. The first thermometer 28 is provided on the outlet side of the ultrafiltration membrane device 25 in the secondary system S2. The first thermometer 28 measures the water temperature of the treated water (ultrapure water) of the secondary system S2 that is sent from the secondary system S2 to the use point 2. The second thermometer 26 is provided between the cooler 17 and the electrically regenerative deionizer 18, and measures the temperature of the water supplied to the electrically regenerative deionizer 18. The electrically regenerative deionizer 18 has a desalination chamber through which the water to be treated flows, a concentration chamber through which the concentrated water in which the ion components are concentrated flows, and an electrode chamber that houses electrodes and through which the electrode water flows. There is no significant difference in the temperature of the water flowing through these chambers. Therefore, in the present embodiment, the second thermometer 26 measures the temperature of the inlet water of the desalination chamber. However, the second thermometer 26 may measure the temperature of the outlet water of the desalination chamber, the inlet water or outlet water of the concentration chamber, or the inlet water or outlet water of the electrode chamber. That is, the second thermometer 26 may measure the temperature of any water flowing in and out of the electrically regenerative deionizer 18.

[0016] In this embodiment, the measured value of the first thermometer 28 is used to control the cooler 17 that cools the water supplied to the electrically regenerative deionizer 18. The first thermometer 28 is originally installed for the purpose of water temperature management at the use point 2. Therefore, conventionally, when the measured value of the first thermometer 28 deviated from the required water temperature at the use point 2, the heat exchanger 21 in the secondary system S2 was operated to adjust the water temperature (hereinafter referred to as the conventional example). On the other hand, the temperature adjustment of the water supplied to the electrically regenerative deionizer 18 was generally performed based on a thermometer provided at the inlet of the electrically regenerative deionizer 18. That is, the water temperature management of the water supplied to the electrically regenerative deionizer 18 is generally performed by the cooler 17 provided upstream of the electrically regenerative deionizer 18 based on the water temperature measured at the inlet of the electrically regenerative deionizer 18. In contrast, in this embodiment, the cooler 17 is controlled based on the measured value of the first thermometer 28 that is separated from the electrically regenerative deionizer 18. When the measured value of the first thermometer 28 rises above the required water temperature at the use point 2 due to some reason, instead of cooling the water flowing through the secondary system S2 with the heat exchanger 21, the water supplied to the electrically regenerative deionizer 18 is cooled with the cooler 17. By this, it is possible to keep the water temperature at the use point 2 within the required water temperature, and since only the position where the water to be treated is cooled changes from the conventional example, the thermal efficiency of the entire ultrapure water production apparatus 1A does not change. Moreover, the boron removal efficiency of the electrically regenerative deionizer 18 is improved.

[0017] The first thermometer 28 is installed downstream of the secondary system S2, that is, downstream of the ultrafiltration membrane device 25 on the main pipe L2, but the position on the main pipe L2 is not limited to this. The first thermometer 28 may measure the temperature of the treated water of any water treatment device constituting the secondary system S2. Alternatively, the first thermometer 28 may be provided in the recirculation line L3. That is, the first thermometer 28 measures the water temperature of the water flowing through any position downstream of the primary system S1, more generally, the water temperature of the water treated by the electro-regenerative deionizer 18 and flowing through any position downstream of the electro-regenerative deionizer 18. Generally, the water temperature in the secondary system S2 is not constant, and the water to be treated is heated, for example, by ultraviolet irradiation in the ultraviolet irradiation device 22 or waste heat from the pure water pump 20, so the water temperature varies depending on the location in the secondary system S2. The water temperature may also change due to waste heat from the piping or heat input to the piping. In the present embodiment, the first thermometer 28 is installed downstream of the ultrafiltration membrane device 25. Therefore, the water temperature measured by the first thermometer 28 substantially coincides with the water temperature at the use point 2, but there may be cases where the distance from the first thermometer 28 to the use point 2 is long and the temperature difference between the two cannot be ignored. However, such temperature changes and temperature differences can be predicted or measured in advance, and there is a predetermined correspondence between the water temperature at the installation position of the first thermometer 28 and the water temperature at the use point 2. Therefore, it is possible to control the cooler 17 using the measured value of the first thermometer 28. Specifically, when the measured value of the first thermometer 28 exceeds the value corresponding to the required water temperature at the use point 2 at the installation position of the first thermometer 28, the cooler 17 operates. For example, when the upper limit value of the required water temperature at the use point 2 is 25.5 °C and it is found by measurement that the water temperature measured by the first thermometer 28 is 0.5 °C lower than the water temperature at the use point 2, the water temperature corresponding to 25.5 °C at the use point 2 at the measurement position of the first thermometer 28 is 25 °C. Therefore, the cooler 17 operates when the measured value of the first thermometer 28 exceeds 25 °C. When the first thermometer 28 is installed upstream of the heat exchanger 21 (for example, between the pure water pump 20 and the heat exchanger 21), it is desirable to fix the temperature rise value or temperature drop value in the heat exchanger 21 in order to establish the correspondence between the measured value of the first thermometer 28 and the water temperature at the use point 2.

[0018] The operating temperature of the cooler 17 is not limited to the temperature corresponding to the upper limit of the required water temperature at the use point 2. The required water temperature at the use point 2 is any temperature within the range of the required water temperature, and may be the lower limit value or the median value of the required water temperature at the use point 2. For example, when the lower limit value of the required water temperature at the use point 2 is 24.5 °C, the water temperature corresponding to 24.5 °C at the use point 2 at the measurement position of the first thermometer 28 is 24 °C. Therefore, by operating the cooler 17 when the measured value of the first thermometer 28 exceeds 24 °C, the supply water to the electric regeneration type deionizer 18 can be pre-cooled before the water temperature at the use point 2 reaches the upper limit value of the required water temperature at the use point 2.

[0019] As described above, when the water temperature of the supply water to the electric regeneration type deionizer 18 is low, the boron removal rate improves. However, when the boron concentration has sufficiently decreased, it is not necessary to extremely lower the water temperature, and when the water temperature decreases too much from the required water temperature at the use point 2, the heating load in the heat exchanger 21 increases. Therefore, depending on the required value of the boron concentration, it is generally not preferable to excessively lower the temperature in the front stage of the electric regeneration type deionizer 18, and the cooler 17 preferably operates so that the difference T1−T2 between the temperature T1 measured by the first thermometer 28 and the temperature T2 measured by the second thermometer 26 is −1 degree or more and 5 degrees or less. If the measured value of the first thermometer 28 is controlled within a predetermined range and the boron concentration has sufficiently decreased, T1−T2 may be negative.

[0020] As measures for reducing the boron concentration, in addition to lowering the water temperature of the water supplied to the electro-regenerative deionizer 18, there is also increasing the current density of the current applied to the electro-regenerative deionizer 18. In this embodiment, these two methods can be selectively executed. Hereinafter, the operation in which the cooler 17 cools the water supplied to the electro-regenerative deionizer 18 is referred to as the first operation, and the operation in which the current applied by the electro-regenerative deionizer 18 is increased is referred to as the second operation. When the boron concentration measured by the boron concentration measuring device 27 is higher than a predetermined value, the control device 3 controls the cooler 17 and the electro-regenerative deionizer 18 so as to execute only one of the first operation and the second operation. When the boron concentration does not become equal to or lower than the predetermined value by only one of the first operation and the second operation, the control device 3 controls the cooler 17 and the electro-regenerative deionizer 18 so as to execute the other of the first operation and the second operation. Which operation to prioritize can be appropriately determined in consideration of the operation cost and the like. If the current density of the current applied to the electro-regenerative deionizer 18 is too large, problems such as electrode seizure, electrical damage and deterioration of the ion exchange membrane and the ion exchanger are likely to occur. Therefore, when adopting the second method, it is preferable to adjust the current density within the range of 2 0.3 A / dm 2 or more and 1 A / dm 2 or less.

[0021] FIG. 2 shows a measurement example of the relationship between the temperature of the water supplied to the electro-regenerative deionizer 18 and the boron removal rate. Since electro-regenerative deionizers different depending on the water temperature range are used, for convenience, the results are shown separately in FIGS. 2(a) and 2(b). The supplied water contains boron (5 to 20 ppb), silica (5 to 10 ppb), and carbonic acid (1 ppm). Here, the carbonic acid concentration is H2CO3, HCO3 - , CO3 2-The concentration of the total amount of carbonate components such as is expressed as the concentration in terms of CO2. When the temperature of the feed water is low, the boron removal rate improves. For example, assuming that the boron concentration of the feed water is 10 ppb, the boron concentration of the treated water of the electrically regenerated deionizer 18 is 60 ppt (removal rate 99.4%), and the target value is 50 ppt. In this case, since it is expected that the removal rate will improve by about 0.05% by lowering the water temperature by about 1°C, the target value of 50 ppt (removal rate 99.5%) will be reached by lowering the water temperature by about 2°C.

[0022] Figure 3 shows an example of the relationship between the current magnification of the electrically regenerated deionizer 18 and the boron removal efficiency. The current magnification is the set current magnification / set flow magnification, the set current magnification is the set current / standard current, and the set flow magnification is the treated water flow / standard flow. That is, the current magnification is the ratio of the normalized current to the normalized flow rate, and by using the current magnification, the influence of the flow rate on the boron removal efficiency can be eliminated. The boron removal efficiency improves as the current magnification increases. For example, when the boron concentration of the feed water is 10 ppb, the boron concentration is reduced to 50 ppt or less (removal rate 99.5% or more) by raising the current magnification to about 1.2 times. However, as the current magnification increases, it becomes difficult for the boron removal efficiency to improve, and in order to reduce the boron concentration to 20 ppt or less (removal rate 99.8%), it is necessary to increase the number of stages or improve the performance of the electrically regenerated deionizer 18. As can be understood from the above, it is necessary to consider the operating cost and equipment cost required for the boron removal efficiency when prioritizing either the first operation or the second operation.

[0023] (Second Embodiment) Figure 4 shows the schematic configuration of the ultrapure water production apparatus 1B according to the second embodiment of the present invention. This embodiment is the same as the first embodiment except that the secondary system S2 is not provided with the heat exchanger 21 and other water temperature adjustment means. As described above, the temperature adjustment of the water supplied to the electrically regenerative deionizer 18 and the temperature adjustment of the use point 2 are performed by the cooler 17. The water temperature adjustment means means a device for the purpose of water temperature adjustment such as a heat exchanger or a heater, and does not include a device that may cause a change in the water temperature during operation, such as a pump. Since the secondary system S2 is not provided with the water temperature adjustment means, the difference T1 - T2 is only affected by the exhaust heat of the constituent devices, the circulation flow rate, and the room temperature, and is kept within the range of -1.0 degree or more and 1.0 degree or less. Therefore, this embodiment is preferably applied when the temperature of the water supplied to the electrically regenerative deionizer 18 is close to the required water temperature of the use point 2. Since the required water temperature of the use point 2 is often around 24 to 26 °C, the temperature of the water supplied to the electrically regenerative deionizer 18 is also in the vicinity thereof. This embodiment can be preferably applied when sufficient boron removal performance can be obtained at a water temperature near the required water temperature of the use point 2, when boron removal is mainly performed in the above-described second operation, or when an operation combined with the second operation is performed.

[0024] (Third Embodiment) Figure 5 shows the schematic configuration of the ultrapure water production apparatus 1C according to the third embodiment of the present invention. In this embodiment, the electrically regenerative deionizer 18 is provided in the secondary system S2. Also in this embodiment, the temperature adjustment of the water supplied to the electrically regenerative deionizer 18 and the temperature adjustment of the use point 2 are performed by the cooler 17. The pure water tank 19 and the pure water pump 20 are omitted, and the recirculation line L3 is connected to the filtered water tank 15. Therefore, in this embodiment, when the water to be treated circulates through the secondary system S2, it always undergoes the treatment of the electrically regenerative deionizer 18. Since the secondary system S2 is not provided with the heat exchanger 21 and other water temperature adjustment means, the difference T1 - T2 is kept within the range of -1.0 degree or more and 1.0 degree or less. This embodiment can also be preferably applied under the same conditions as the second embodiment.

[0025] (Fourth Embodiment) As described above, the preferred temperature of the feed water to the reverse osmosis membrane device 14 is generally higher than the preferred temperature of the feed water to the electrically regenerable deionization device 18. The water temperature at the use point 2 is required to be maintained within a certain range, but is usually higher than the preferred temperature of the feed water to the electrically regenerable deionization device 18. Therefore, the water to be treated is generally heated at the inlet of the reverse osmosis membrane device 14, cooled at the inlet of the electrically regenerable deionization device 18, and reheated within the secondary system S2. However, conventionally, the water to be treated has been heated, cooled, and reheated by mutually independent heat exchangers, consuming energy in each of these respective processes. In the fourth to sixth embodiments, the waste heat of the treated water of the reverse osmosis membrane device 14 is utilized for heating the feed water to the reverse osmosis membrane device 14 and / or heating the treated water of the electrically regenerable deionization device 18, thereby improving the overall energy use efficiency of the ultrapure water production devices 1D to 1F.

[0026] Fig. 6 shows a schematic configuration of an ultrapure water production apparatus 1D according to a fourth embodiment of the present invention. In this embodiment, as in the first to third embodiments, the reverse osmosis membrane device 14 is provided upstream of the electrically regenerable deionizer 18, and the temperature adjusting device 13 is provided upstream of the reverse osmosis membrane device 14. Also in this embodiment, the temperature adjusting device 13 adjusts the water temperature of the water supplied to the reverse osmosis membrane device 14 to 15°C or higher and 40°C or lower, preferably about 20 to 30°C. When the water temperature measured by the first thermometer 28 exceeds a value corresponding to the required water temperature at the use point 2 at the installation position of the first thermometer 28, the cooler 17 operates. In this embodiment, in addition to this, a first heat exchanger 29 is provided that recovers heat from the treated water of the reverse osmosis membrane device 14 and warms the water supplied to the reverse osmosis membrane device 14. The arrow indicates the direction of heat transfer. The water supplied to the reverse osmosis membrane device 14 is warmed by the first heat exchanger 29 before being warmed by the temperature adjusting device 13. Therefore, the heat energy required by the temperature adjusting device 13 is saved. On the other hand, the treated water of the reverse osmosis membrane device 14 is cooled by the cooler 17 after transferring heat energy to the water supplied to the reverse osmosis membrane device 14. Therefore, the temperature of the treated water supplied to the cooler 17 decreases, and the cooling load of the cooler 17 decreases. In this embodiment, since heat energy is transferred by heat exchange from a part where heat energy is not required to a part where heat energy is required, the energy use efficiency of the ultrapure water production apparatus 1D is improved.

[0027] (Fifth Embodiment) Fig. 7 shows a schematic configuration of an ultrapure water production apparatus 1E according to a fifth embodiment of the present invention. In the present embodiment, as in the first to third embodiments, the reverse osmosis membrane device 14 is provided upstream of the electrically regenerative deionization device 18, and the temperature adjustment device 13 is provided upstream of the reverse osmosis membrane device 14. Also in the present embodiment, the temperature adjustment device 13 adjusts the water temperature of the water supplied to the reverse osmosis membrane device 14 to 15°C or higher and 40°C or lower, preferably about 20 to 30°C. When the water temperature measured by the first thermometer 28 exceeds a value corresponding to the required water temperature at the use point 2 at the installation position of the first thermometer 28, the cooler 17 operates. In the present embodiment, in addition to this, it has a second heat exchanger 30 that recovers heat from the treated water of the reverse osmosis membrane device 14 and warms the treated water of the electrically regenerative deionization device 18. The treated water of the electrically regenerative deionization device 18 is further warmed by the heat exchanger 21 after being warmed by the second heat exchanger 30. Therefore, the heat energy required by the heat exchanger 21 is saved. In a modified example, the heat exchanger 21 can also be deleted. Similar to the fourth embodiment, the treated water of the reverse osmosis membrane device 14 is cooled by the cooler 17 after transferring heat energy to the water supplied to the reverse osmosis membrane device 14. Therefore, the temperature of the treated water supplied to the cooler 17 decreases, and the cooling load of the cooler 17 decreases. Also in the present embodiment, since heat energy is transferred by heat exchange from a part where heat energy is not required to a part where heat energy is required, the energy use efficiency of the ultrapure water production apparatus 1E is improved. Also, as described above, the temperature adjustment device 13 can be any one of a heater, a cooler, and a temperature controller according to the water temperature of the water supplied to the reverse osmosis membrane device 14, or can also be omitted.

[0028] (Eighth Embodiment) Fig. 8 shows a schematic configuration of an ultrapure water production apparatus 1F according to a sixth embodiment of the present invention. This embodiment combines the fourth and fifth embodiments. The ultrapure water production apparatus 1F of this embodiment includes a first heat exchanger 29 that recovers heat from the treated water of the reverse osmosis membrane apparatus 14 and warms the feed water to the reverse osmosis membrane apparatus 14, and a second heat exchanger 30 that recovers heat from the treated water of the reverse osmosis membrane apparatus 14 and warms the treated water of the electrically regenerable deionizer 18. The first heat exchanger 29 may be a heater that recovers heat from the feed water (raw water) and warms the permeate water of the reverse osmosis membrane apparatus 14. The treated water of the reverse osmosis membrane apparatus 14 has heat recovered by the first heat exchanger 29 and then further has heat recovered by the heat exchanger 30. This embodiment can achieve the effects of the fourth and fifth embodiments simultaneously. That is, the thermal energy required by the temperature adjustment device 13 and the heat exchanger 21 is saved, and the cooling load of the cooler 17 is reduced, so the energy utilization efficiency of the ultrapure water production apparatus 1F is further improved.

Explanation of Signs

[0029] 1A~1F Ultrapure water production apparatus 2 Use point 3 Control device 13 Temperature adjustment device 14 Reverse osmosis membrane apparatus 17 Cooler 18 Electrically regenerable deionizer 26 Second thermometer 27 Boron concentration measuring device 28 First thermometer 29 First heat exchanger 30 Second heat exchanger S1 Primary system S2 Secondary system

Claims

1. An ultrapure water production apparatus having a primary system and a secondary system located downstream of the primary system and upstream of a use point, at least one electrically regenerative deionization device, a cooler for cooling the water supplied to the electrically regenerative deionization device, and a first thermometer for measuring the water temperature of the water treated by the electrically regenerative deionization device and flowing downstream of the electrically regenerative deionization device. The ultrapure water production apparatus, wherein the cooler operates when the water temperature measured by the first thermometer exceeds a value corresponding to the required water temperature of the use point at the installation position of the first thermometer.

2. The ultrapure water production apparatus according to claim 1, wherein the first thermometer measures the water temperature of the treated water of any one of the water treatment devices constituting the secondary system.

3. It has a second thermometer for measuring the temperature of any water entering and leaving the electrically regenerative deionization device, The cooler of the ultrapure water production apparatus according to claim 2 operates so that the difference T1 - T2 between the temperature T1 measured by the first thermometer and the temperature T2 measured by the second thermometer is -1 degree or more and 5 degrees or less.

4. The electrically regenerative deionization device is provided in the primary system, the difference T1 - T2 is -1.0 degree or more and 1.0 degree or less, and the secondary system is not provided with a water temperature adjustment means. The ultrapure water production apparatus according to claim 3.

5. The electrically regenerative deionization device is provided in the secondary system, the difference T1 - T2 is -1.0 degree or more and 1.0 degree or less, and the secondary system is not provided with a water temperature adjustment means other than the cooler. The ultrapure water production apparatus according to claim 3.

6. at least one reverse osmosis membrane device provided upstream of the electrically regenerative deionization device, and a temperature adjustment device provided upstream of the at least one reverse osmosis membrane device. The temperature adjustment device adjusts the water temperature of the water supplied to the reverse osmosis membrane device to 15°C or more and 40°C or less. The ultrapure water production apparatus according to any one of claims 1 to 5.

7. The ultrapure water production apparatus according to claim 6, having a first heat exchanger that recovers heat from the treated water of the at least one reverse osmosis membrane device and warms or cools the water supplied to the reverse osmosis membrane device.

8. The ultrapure water production apparatus according to claim 6, having a second heat exchanger that recovers heat from the treated water of the at least one reverse osmosis membrane device and warms the treated water of the electrically regenerative deionization device.

9. It has a boron concentration measuring device for measuring the boron concentration of the treated water of the electric regeneration type deionization device and a control device, The cooler is capable of a first operation of cooling the water supplied to the electric regeneration type deionization device, The electric regeneration type deionization device is capable of a second operation of increasing the applied current, When the boron concentration measured by the boron concentration measuring device is higher than a predetermined value, the control device controls the cooler and the electric regeneration type deionization device so as to execute only one of the first operation and the second operation. The ultrapure water production device according to any one of claims 1 to 8.

10. When the boron concentration does not become equal to or lower than the predetermined value by only one of the first operation and the second operation, the control device controls the cooler and the electric regeneration type deionization device so as to execute the other of the first operation and the second operation. The ultrapure water production device according to claim 9.

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