Temperature control system, temperature control method, sterilization method for pharmaceutical water production apparatus, and secondary pure water production method

Abstract

The present invention provides a temperature control system and a temperature control method that can suppress overshoot during temperature increases or decreases of water to be treated. [Solution] A temperature control system for a pure water system comprising: a temperature controller; a water supply pipe for supplying water to be treated from the temperature controller to a downstream stage; a heat transfer medium pipe for supplying a heat transfer medium to the temperature controller; a first control valve and a second control valve provided in order from the upstream side in the heat transfer medium pipe; a thermometer for detecting the temperature of the water to be treated in the water supply pipe; a pressure gauge for detecting the pressure of the heat transfer medium; a temperature control unit for controlling the opening degree of the second control valve according to the value detected by the thermometer; and a pressure control unit for controlling the opening degree of the first control valve according to the value detected by the pressure gauge, wherein the pressure control unit controls the opening degree of the first control valve based on the deviation between a preset pressure change pattern and the value detected by the pressure gauge.

Description

Technical Field

[0001] The present invention relates to a temperature control system and a temperature control method for producing primary pure water or secondary pure water with suppressed overshoot at the start of temperature rise or fall, a sterilization method and a secondary pure water production method for a pharmaceutical water production apparatus using these.

Background Art

[0002] Conventionally, primary pure water has been used in the production of ultrapure water used in semiconductor manufacturing processes and as pharmaceutical water (purified water). The primary pure water used for semiconductor manufacturing water is produced by treating raw water with a primary pure water apparatus that combines a reverse osmosis membrane apparatus, an ion exchange apparatus, an activated carbon adsorption apparatus, a microfiltration apparatus, an ultraviolet irradiation apparatus, etc. The primary pure water apparatus, for example, removes the color components in the raw water, and further removes or decomposes the alkaline earth metals, dissolved carbon dioxide, and urea in the raw water in order by a cation exchange apparatus, a decarbonation apparatus, and a urea decomposition apparatus (see, for example, Patent Document 1). In the urea decomposition apparatus, for example, the water to be treated is stored in a treatment tank, and hypobromous acid or hypochlorous acid is added to the water to be treated in a state where the pH of the water to be treated is appropriately adjusted, whereby the urea in the water to be treated is oxidatively decomposed. At this time, in order to increase the decomposition efficiency of urea, the water to be treated supplied to the treatment tank may be heated. Also, in the secondary pure water production apparatus in the semiconductor manufacturing process, the temperature of the water to be treated may be raised or lowered (see, for example, Patent Document 2).

[0003] Also, pharmaceutical water such as purified water and water for injection is produced by a pharmaceutical water production apparatus that combines a reverse osmosis membrane apparatus, an electrodeionization apparatus, an activated carbon adsorption apparatus, a microfiltration apparatus, an ultraviolet irradiation apparatus, and a mixed bed ion exchange apparatus. The quality of pharmaceutical water is strictly defined in the pharmacopoeias of each country. For example, in order to prevent the generation or contamination of viable bacteria and endotoxins (hereinafter referred to as "viable bacteria") in the manufacturing apparatus system, hot water is circulated in the manufacturing apparatus for a predetermined time (see, for example, Patent Document 3).

Prior Art Documents

Patent Documents

[0004] [Patent Document 1] Japanese Patent Publication No. 2015-100733 [Patent Document 2] Japanese Patent Publication No. 2017-172932 [Patent Document 3] Japanese Patent Publication No. 2021-178297 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] In the production of primary and secondary pure water as described above, heat exchangers are used to heat the water to be treated, which exchange heat between the water and a heat transfer medium such as steam via plates. In heating methods that use feedback control of the supply amount of the heat transfer medium based on the temperature of the heated water to be treated, it has been found that, for example, in the initial stages after heating starts, an excessive amount of heat transfer medium is supplied, which can easily cause the water temperature of the treated water to exceed the set value (overshoot). In particular, in the urea decomposition treatment described above, a predetermined amount of water to be treated is stored in a treatment tank, urea decomposition is performed, and the treated water after urea decomposition is sent to the next stage, and this operation is repeated. For example, the water to be treated is heated while the water to be treated is being replenished in the treatment tank, the heating is stopped while the treated water is sent to the next stage, and the heating is resumed when the water to be treated is replenished again. If overshoot occurs each time heating starts, the amount of steam used as a heat source increases unnecessarily, which increases operating costs, and the repeated rapid heating load may accelerate deterioration or failure of piping, etc. For example, conventionally, a rapid increase in steam usage required increasing the number of boilers to cope with the increase, but such measures become unnecessary. Furthermore, even when continuous operation is performed instead of batch operation, it may be necessary to change the supply rate of treated water to the downstream stage to match the operating conditions there. In such cases, continuous operation is not possible, and the system must repeatedly start and stop. In this scenario, overshoot may occur each time the system restarts and stops. Also, in the production of pharmaceutical water, sterilization with heated water is performed periodically, after which the production equipment system is cooled to a temperature suitable for pharmaceutical water production. Therefore, if overshoot occurs each time sterilization is performed, it could similarly accelerate deterioration and failure of piping and other components. Similarly, in the production of ultrapure water (secondary pure water), heating and cooling of the water to be treated may also be necessary.

[0006] The present invention has been made to solve the above-mentioned problems, and aims to provide a temperature control system and a temperature control method that can suppress overshoot at the start of heating of the water to be treated. [Means for solving the problem]

[0007] Embodiments of the present invention have the following configurations. [1] A water purification system for producing primary or secondary pure water by removing impurities from water to be treated, wherein the temperature control system is for adjusting the temperature of the water to be treated, A temperature controller is provided inside which the water to be treated and the heat transfer medium are supplied, and which adjusts the temperature of the water to be treated by heat exchange with the heat transfer medium. A water supply pipe for supplying the temperature-controlled water to be treated from the temperature controller to the downstream stage, A heat transfer medium pipe that supplies the heat transfer medium to the temperature controller, The heat transfer tube is provided with a first control valve and a second control valve, which are arranged in order from the upstream side along the flow of the heat transfer medium. A thermometer is installed in the water supply pipe to detect the temperature of the water to be treated inside the water supply pipe and output the detected value. A pressure gauge is provided on the downstream side of the first control valve and the upstream side of the second control valve of the heat transfer tube, which detects the pressure of the heat transfer medium in the heat transfer tube and outputs the detected value. A temperature control unit that controls the opening degree of the second control valve according to the value detected by the thermometer, The system includes a pressure control unit that controls the opening degree of the first control valve according to the value detected by the pressure gauge, The pressure control unit is characterized by controlling the opening degree of the first control valve based on the deviation between a preset pressure change pattern and the detected value of the pressure gauge. Temperature control system. [2] The temperature control system according to [1], wherein the temperature control unit provides feedback control of the opening degree of the second control valve according to the value detected by the thermometer. [3] The temperature control system according to [1], wherein the temperature control unit controls the opening of the second control valve based on the deviation between a preset temperature change pattern and the value detected by the thermometer. [4] The pure water apparatus is equipped with a decomposition apparatus or an ion exchange apparatus, The temperature control system is the temperature control system according to [1] or [2], which adjusts the temperature of the water to be treated in the decomposition apparatus or ion exchange apparatus. [5] The pure water apparatus is a medical water production apparatus equipped with a reverse osmosis membrane apparatus and an electrodeionizer, The raw water of the aforementioned medical water production apparatus is used as the water to be treated. The temperature control system adjusts the temperature of the water to be treated. The temperature control system according to claim [1] or [2].

[0008] [6] A method for producing pure water by removing impurities from water to be treated to produce primary or secondary pure water, wherein the temperature of the water to be treated is adjusted by heat exchange with a heat transfer medium, A first step involves measuring the temperature of the water to be treated, whose temperature has been adjusted, and, based on the obtained temperature measurement, feedback-controlling the amount of the heat transfer medium supplied to maintain the temperature of the water to be treated within a predetermined range. A temperature control method comprising a second step of measuring the supply pressure of the heat exchange medium and controlling the supply pressure of the heat exchange medium based on the obtained pressure measurement value, based on the deviation from a predetermined pressure change pattern set in advance. [7] The method for producing pure water includes decomposition treatment or ion exchange treatment, A temperature control method according to [6] for adjusting the temperature of the water to be treated in the decomposition treatment or ion exchange treatment. [8] The method for producing pure water is a medical water production apparatus that performs reverse osmosis membrane treatment and electrolytic deionization treatment, and in the sterilization step of the medical water production apparatus, [6] The temperature control method described above generates heated water, and the heated water is circulated within the pharmaceutical water production apparatus system to sterilize the pharmaceutical water production apparatus system. A method for sterilizing a medical water production device. [9] A method for producing secondary pure water, wherein the temperature of the water to be treated is adjusted using the temperature control system described in [1]. Note that the symbol "~" indicates a numerical range including the numerical values before and after it. The pure water treatment device includes a primary pure water treatment device and secondary pure water. The primary pure water includes primary pure water for semiconductor manufacturing and purified water for pharmaceuticals. The secondary pure water includes secondary pure water for semiconductor manufacturing and water for injection for pharmaceuticals, but is not limited thereto. Heating means applying heat to an object, raising temperature means gradually increasing the temperature of the object, and lowering temperature means gradually decreasing the temperature of the object. That is, even if heating is being performed, if the temperature of the heating target does not rise, it is not called raising temperature, and if the temperature of the heating target decreases while heating, it is called lowering temperature.

Advantages of the Invention

[0009] According to the temperature control system and temperature control method of the present invention, overshoot during heating or cooling of the water to be treated can be suppressed.

Brief Description of the Drawings

[0010] [Figure 1] It is a diagram schematically showing the temperature control system of the present embodiment. [Figure 2] It is a graph schematically showing the change over time of the temperature of the heated water to be treated when using the temperature control system of the present embodiment and the conventional heating method. [Figure 3] It is a diagram schematically showing the primary pure water treatment device of the present embodiment. [Figure 4] It is a diagram schematically showing the secondary pure water treatment device of the present embodiment. [Figure 5] It is a diagram schematically showing the primary pure water treatment device of another embodiment. [Figure 6] It is a diagram schematically showing the secondary pure water treatment device of another embodiment. [Figure 7] It is a graph showing the relationship between the elapsed time from the start of heating and the temperature of the treated water in Example 1. [Figure 8] It is a graph showing the relationship between the elapsed time from the start of heating and the temperature of the treated water in Example 2. [Figure 9] It is a graph showing the relationship between the elapsed time from the start of cooling and the temperature of the treated water in Example 3. [Figure 10] This graph shows the relationship between the elapsed time from the start of heating and the temperature of the treated water in the comparative example. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described below. Figure 1 is a schematic diagram of the temperature control system 1 of this embodiment. The temperature control system 1 of this embodiment heats or cools the water to be treated in the pure water system to raise or lower the temperature of the water to be treated. An example of raising the temperature of the water to be treated will be described below, but the same applies to lowering or cooling the temperature.

[0012] The temperature control system 1 includes a heat exchanger 10. The heat exchanger 10 heats the water to be treated by heat exchange between the water and a heat transfer medium supplied inside. The heat exchanger 10 is connected to a supply pipe 11a that supplies the water to be treated to the heat exchanger 10 and a supply pipe 11b that sends the heated water to the downstream stage. The supply pipe 11b is equipped with a thermometer 15 that detects the temperature of the heated water to be treated. The thermometer 15 detects the temperature of the heated water to be treated and outputs the detected value.

[0013] Furthermore, the heat exchanger 10 is connected to a supply pipe 12a that supplies a heat transfer medium to the heat exchanger 10, and a discharge pipe 12b that discharges the heat transfer medium, which has been heat-exchanged with the water to be treated, from the heat exchanger 10. A first control valve 13 and a second control valve 14 are provided in the path of the heat transfer medium supply pipe 12a. The first control valve 13 is located upstream along the flow of the heat transfer medium, and the second control valve 14 is located downstream thereof. A pressure gauge 16 for detecting the supply pressure of the heat transfer medium is provided between the first control valve 13 and the second control valve 14. The pressure gauge 16 detects the supply pressure of the heat transfer medium in the supply pipe 12a and outputs the detected value. When heating, the heat transfer medium is a high-temperature medium such as steam or hot water. When cooling, the heat transfer medium is a low-temperature medium such as cold water. When steam is used, the temperature is raised by gradually increasing the amount of heat transfer medium such as steam supplied to the heat exchanger 10, and the temperature is lowered by gradually decreasing the amount of heat transfer medium such as steam.

[0014] The temperature control system 1 includes a pressure control unit 18a and a temperature control unit 18b. The temperature control unit 18b adjusts the opening degree of the second control valve 14 based on the value detected by the thermometer 15. The pressure control unit 18a adjusts the opening degree of the first control valve 13 based on the value detected by the pressure gauge 16. These controls regulate the supply pressure of the heat transfer medium supplied to the heat exchanger 10 and the water temperature of the treated water in the heat exchanger 10. Although the temperature control system 1 shown in Figure 1 uses two independent control units, the pressure control unit 18a and the temperature control unit 18b, a single control unit integrating the pressure control unit 18a and the temperature control unit 18b may also be used. In this case, the integrated control unit may be, for example, a PLC (Programmable Logic Controller).

[0015] Next, a temperature control method using the temperature control system 1 will be described. First, in the first step, the temperature control unit 18b provides feedback control of the temperature of the water to be treated in the water supply pipe 11b. The temperature control unit 18b has a program stored in advance for controlling the rate of temperature increase (rate of change of temperature) of the water to be treated within a predetermined range. By setting a temperature increase pattern (a graph representing the relationship between elapsed time and temperature) in advance in the program, the deviation between the value detected by the thermometer 15 and the water temperature (set value) of the set temperature increase pattern is calculated. Based on this deviation, the temperature control unit 18b sends a command signal to the second control valve 14 to change the opening degree. This controls the opening degree of the second control valve 14, and the amount of heat transfer medium supplied is adjusted. The temperature increase pattern is, for example, a step-like pattern that changes (increases) the temperature at each minute time interval. The temperature increase pattern may be a pattern in which the temperature increases continuously, or a pattern that repeats the increase and maintenance of the temperature. The minute time interval is, for example, in units of 0.1 seconds to several seconds. Alternatively, instead of a heating pattern, a predetermined heating rate may be set in the program, and the program may calculate the set value to create a heating pattern. Alternatively, instead of setting a heating pattern, in the first step, the temperature of the water to be treated after heating (target temperature) can be set in advance in a program, and feedback control can be performed based on the deviation between the set value of the target temperature and the value detected by the thermometer 15.

[0016] Furthermore, when cooling the water to be treated, the cooling pattern and rate can be set in advance, or the temperature after cooling (target temperature) can be set as a value and controlled in the same manner as above. The cooling pattern is, for example, a step-like pattern that changes (decreases) the temperature at minute time intervals. The cooling pattern may be a pattern in which the temperature decreases continuously, or a pattern that repeats the decrease and maintenance of the temperature. The minute time interval is, for example, in units of 0.1 seconds to several seconds. Note that patterns that set desired temperature changes, such as heating patterns and cooling patterns, are collectively called temperature change patterns.

[0017] Furthermore, in the second step, the pressure control unit 18a provides feedback control of the pressure of the heat transfer medium supplied from the first control valve 13 to the second control valve 14. The program pre-stored in the pressure control unit 18a calculates the deviation between the detected value of the pressure gauge 16 and the set value. By pre-setting a pressure boost pattern (a graph shape representing the relationship between elapsed time and pressure) in the program, the deviation between the detected value of the pressure gauge 16 and the pressure (set value) shown by the set pressure boost pattern is calculated. The pressure boost pattern is, for example, a step-like pattern that changes (increases) the pressure at each minute time interval. The pressure pattern may be a pattern in which the pressure increases continuously, or a pattern that repeats increasing and maintaining the pressure. The minute time is, for example, in units of 0.1 seconds to several seconds. Alternatively, instead of a pressure boost pattern, a predetermined pressure boost speed may be set in the program, and the set value may be calculated to create a pressure boost pattern. Based on this deviation, the pressure control unit 18a transmits a command signal to change the opening degree to the first control valve 13. This controls the opening of the first control valve 13, thereby regulating the supply pressure of the heat transfer medium. The second step maintains the rate of change of the heat transfer medium supply pressure within a predetermined range. By using the first and second steps in combination and performing them simultaneously, the rate of change of the temperature of the water to be treated is maintained within a predetermined range.

[0018] Furthermore, when lowering the temperature of the water to be treated, the pressure setting should be gradually reduced from the initial value by setting a pressure reduction pattern. The pressure reduction pattern is, for example, a step-like pattern that changes (decreases) the temperature at intervals of minute time intervals. The pressure reduction pattern may be a pattern in which the pressure decreases continuously, or a pattern in which the pressure decreases and then stays constant. The minute time interval is, for example, in units of 0.1 seconds to several seconds. Note that patterns that set the desired pressure change, such as pressure increase patterns and pressure decrease patterns, are collectively called pressure change patterns.

[0019] Specifically, for example, at the initial stage of heating, the second control valve 14 is gradually opened to begin supplying the heat transfer medium to the heat exchanger 10. At the beginning of opening of the second control valve 14, the amount of heat transfer medium supplied through the second control valve 14 tends to increase rapidly. Therefore, the first control valve 13 reduces the pressure of the heat transfer medium supplied from the first control valve 13 to the second control valve 14 to an appropriate pressure before sending it to the second control valve 14. This suppresses the rapid rise in the temperature of the treated water (overshoot) at the start of heat transfer medium supply and the start of an increase in the supply amount.

[0020] Figure 2 is a schematic diagram showing the change over time from the start of heating in the temperature control system 1 and temperature control method of this embodiment, and in a conventional example where only feedback control by the second control valve 14 and thermometer 15 is performed without using the first control valve 13. The case of the temperature control system 1 of this embodiment is represented by a solid line, and the case of the conventional example is represented by a dashed line. As shown in the graph of Figure 2, with the temperature control system 1 and temperature control method of this embodiment, the rapid temperature rise (overshoot) at the start of heating is suppressed, and the heating rate (rate of change of temperature) during the heating period is kept approximately constant.

[0021] The conventional example used in Figure 2 is the same device as the embodiment described above, except that, for example, a pressure reducing valve is used as the first control valve 13 and the pressure gauge 16 is omitted. Generally, a pressure reducing valve can control (reduce) the pressure to a constant value, but it cannot perform feedback control. For example, a steam pressure of 0.7 MPa is reduced to a constant pressure of 0.2 MPa and kept approximately constant. In this case, the result of temperature control will be as illustrated in the conventional example in Figure 2, and the temperature gradient will become particularly steep in the initial stages of operation. Therefore, concerns arise regarding increased steam consumption and its impact on the equipment.

[0022] Next, the various components of the temperature control system 1 of this embodiment will be described. The heat exchanger 10 receives the water to be treated and the heat transfer medium, and heats the water to be treated by heat exchange between the water to be treated and the heat transfer medium. The heat exchanger 10 can be any type of heat exchanger, such as a plate type, a multi-tube heat exchanger (shell and tube type heat exchanger), a spiral type heat exchanger, or a double-tube type heat exchanger, but a plate type heat exchanger is preferred. In a plate type heat exchanger, a plurality of heat transfer plates, each having a flow path for the water to be treated or the heat transfer medium formed inside, are arranged alternately on top of each other, with heat transfer plates through which the water to be treated flows and heat transfer plates through which the heat transfer medium flows, thereby performing heat exchange between the water to be treated and the heat transfer medium. As plate type heat exchangers, there are opposing type plate type heat exchangers in which the water to be treated and the heat transfer medium flow in opposite directions, and parallel type plate type heat exchangers in which both flow in the same direction, and an opposing type plate type heat exchanger is preferred. Furthermore, in a plate-type heat exchanger, the inlet and outlet of the water to be treated may be on the same side or opposite side with respect to the overlapping direction of the alternately stacked heat transfer plates. In addition, the material of the heat transfer plates is preferably metal in order to achieve high heat exchange efficiency, and is preferably steel, or stainless steel or titanium, which have high heat resistance and corrosion resistance.

[0023] The supply pipe 11a and water supply pipe 11b for supplying the water to be treated, and the heat transfer medium supply pipe 12a and discharge pipe 12b for supplying the heat transfer medium, are all made of materials that have heat resistance and corrosion resistance. The materials of the supply pipe 11a, water supply pipe 11b, supply pipe 12a and discharge pipe 12b are, for example, steel and stainless steel, with SUS304 and SUS316 being preferred.

[0024] The first control valve 13 is, for example, a pressure control valve that feedback-controls the pressure of the heat transfer medium flowing through the first control valve 13 based on the detected value of the pressure gauge 16. The first control valve 13 has a positioner that receives a control signal from the pressure control unit 18a and outputs a current signal or an air signal so that the control signal and the opening degree of the first control valve 13 match, and a drive unit that operates the valve body in accordance with the current signal or air signal from the positioner.

[0025] The second control valve 14 is a temperature control valve that, for example, adjusts the temperature of the water to be treated in the water supply pipe 11b by feedback-controlling the flow rate of the heat transfer medium flowing through the second control valve 14 based on the detected value of the thermometer 15. The opening degree of the second control valve 14 is adjusted based on a control signal from the temperature control unit 18b, thereby controlling the flow rate of the heat transfer medium and adjusting the temperature of the water to be treated in the water supply pipe 11b. The second control valve 14 has a positioner that receives a control signal based on the temperature detected value from the temperature control unit 18b and outputs a current signal or an air signal so that the control signal and the opening degree of the second control valve 14 match, and a drive unit that operates the valve body in accordance with the current signal or air signal from the positioner.

[0026] Next, a primary pure water system using the temperature control system 1 of this embodiment will be described. The following description will focus on an example where the water to be treated is heated to raise its temperature, but the same applies to cases where the temperature is lowered or cooled. Figure 3 is a schematic diagram of the primary pure water system 20 of this embodiment. The primary pure water system 20 is equipped with an activated carbon unit 21, a cation exchange unit (SC) 22, a decarbonation tower (DG) 23, a temperature control system 1, a decomposition treatment unit 24, a reverse osmosis membrane unit (RO) 25, an ultraviolet irradiation unit (TOC-UV) 26, a mixed-bed ion exchange unit (MB) 27, and a degassing membrane unit (MDG) 28 in this order, and produces primary pure water by treating raw water.

[0027] The raw water sources include city water, well water, groundwater, river water, industrial water, and spent ultrapure water (recovered water) from semiconductor manufacturing processes. The raw water may contain 0.01 to 0.2 mg / L of urea.

[0028] In the primary pure water system 20, the activated carbon system 21 is equipped with activated carbon, which removes chromatic components such as humic substances and / or dissolved organic carbon (DOC) components derived from humic substances, suspended solids, etc., from the raw water. Humic substances refer to humic substances produced when plants and other materials are decomposed by microorganisms, and include humic acid, fulvic acid, etc. As the activated carbon, coconut shell-based or coal-based activated carbon can be used, molded into powder, granular, fibrous, plate-shaped, or honeycomb shape. The chromaticity of the treated water from the activated carbon system 21 is preferably reduced to 5 degrees or less, more preferably to 2 degrees or less.

[0029] The cation exchange device 22 has a cation exchange resin, which exchanges and removes cation components from the raw water. Either a strongly acidic cation exchange resin or a weakly acidic cation exchange resin, or both, can be used as the cation exchange resin. To prevent scaling in the downstream reverse osmosis membrane device 25, it is preferable to use a strongly acidic cation exchange resin because it has excellent performance in removing alkaline earth metals.

[0030] The decarboxylation device 23 performs decarboxylation treatment on cation exchange treated water. In the decarboxylation treatment, dissolved carbon dioxide is removed from the water to be treated, producing decarboxylated water with a reduced carbon dioxide concentration. This prevents scale formation in the downstream reverse osmosis membrane device 25.

[0031] The decomposition treatment device 24 has, for example, one or more airtight treatment tanks, and the water to be treated is retained in the treatment tanks for a certain period of time to decompose and remove urea and other organic substances from the water to be treated. In the treatment tanks, chemicals are added to the water to be treated while the pH is adjusted to an appropriate value according to the substance to be decomposed. Oxidizing agents such as ozone, hydrogen peroxide, hypobromous acid, hypochlorous acid, and persulfuric acid are used as chemicals. Alternatively, the decomposition treatment device may also use biodecomposition treatment using a biological treatment tank or the like. When the decomposition treatment device 24 decomposes urea, for example, hypobromous acid can be added to the water to be treated while the pH of the water to be treated in the treatment tanks is adjusted to 9 or higher to decompose the urea in the water to be treated.

[0032] Alternatively, an ion exchange device can be used instead of the decomposition treatment device 24. The ion exchange device has an ion exchange resin, which removes ionic components from the water. The ion exchange resin can be a cationic resin, anionic resin, boron-selective ion exchange resin, catalyst resin, etc. In this case as well, since the water being treated by the ion exchange device can always be kept at an optimal temperature, it is possible to maintain good treated water quality.

[0033] The temperature control system 1 heats the water to be treated supplied to the decomposition treatment apparatus 24. The configuration of the temperature control system 1 is the same as that of the temperature control system 1 in Figure 1 described above. In order to improve the urea decomposition efficiency in the decomposition treatment apparatus 24, the temperature of the water to be treated heated by the temperature control system 1 is preferably, for example, 20°C to 40°C, and the heating rate (rate of change of the temperature of the water to be treated) is preferably 1°C / min to 10°C / min. The residence time of the water to be treated in the decomposition treatment apparatus 24 is, for example, 10 minutes to 30 minutes, and in the case of batch operation, the interval from the end of heating of the water to be treated by the temperature control system 1 to the start of heating of the next water to be treated is 5 minutes to 20 minutes.

[0034] In the primary pure water apparatus 20 of this embodiment, a thermometer 15 of the temperature control system 1 is provided on the inlet side of the decomposition treatment apparatus 24. Steam, for example, is supplied to the first control valve 13 as a heat transfer medium. The pressure of the heat transfer medium (above) supplied to the first control valve 13 is, for example, 0.5 to 2 MPa. The rate of heating of the water to be treated (rate of temperature change) during the process of passing through the heat exchanger 10 is predetermined to a value in the range of 1°C / min to 10°C / min, and this value of the heating rate is set in the temperature control unit 18b. Based on the value detected by the thermometer 15, the temperature control unit 18b adjusts the opening of the second control valve 14 so that the heating rate is set as above. At the same time, the rate of pressure increase of the heat transfer medium that has passed through the first control valve 13 (rate of pressure change) is predetermined to a value in the range of 0.02 MPa / min to 0.2 MPa / min, and is set in the pressure control unit 18a. The pressure control unit 18a adjusts the opening of the first control valve 13 based on the value detected by the pressure gauge 16, so that the rate at which the pressure of the heat transfer medium passing through the first control valve 13 rises to the value set above. By simultaneously controlling the rate of heating and the rate of pressure rise, a rapid rise in temperature at the start of heating can be suppressed, thereby reducing the heat load on the piping and equipment in the primary pure water system 20 and preventing a decrease in the function of the system. In particular, the water to be treated in the decomposition treatment device has an appropriate temperature range. If the temperature is lower than this appropriate temperature range, the desired reaction will not proceed, and if it exceeds the appropriate temperature range, side reactions will proceed, and sufficient water quality cannot be obtained. Therefore, in the primary pure water system 20 of this embodiment, since the temperature control system 1 is used, the water to be treated in the decomposition treatment device can be maintained at a temperature within the preferred temperature range, so that treated water of good quality can be obtained.

[0035] Furthermore, as the first control valve 13, any control valve capable of feedback control of pressure can be used without particular limitation. Specifically, examples of the first control valve 13 include needle valves, gate valves, ball valves, globe valves, etc. Also, as the second control valve 14, any control valve capable of feedback control of temperature can be used without particular limitation. Specifically, examples of the second control valve 14 include needle valves, gate valves, ball valves, globe valves, etc.

[0036] The reverse osmosis membrane apparatus 25 removes salts and impurities such as ionic and colloidal organic matter from the urea decomposition water to produce concentrated water and permeate. As the reverse osmosis membrane apparatus 25, a cellulose triacetate asymmetric membrane or a polyamide composite membrane can be used, and membrane modules such as sheet flat membranes, spiral membranes, tubular membranes, and hollow fiber membranes can be used. Among these, a polyamide composite membrane is preferred in order to increase the rate of impurity removal, and a spiral membrane shape is preferred. The rate of impurity removal may be improved by connecting two reverse osmosis membrane apparatuses 25 in series to form a two-stage reverse osmosis membrane apparatus.

[0037] The ultraviolet irradiation device 26 decomposes trace amounts of organic matter remaining in the treated water of the reverse osmosis membrane device 25 by irradiating it with ultraviolet light. The mixed-bed ion exchange device 27 adsorbs and removes organic acids and other substances produced by the decomposition of organic matter. The degassing membrane device 28 removes gases, especially dissolved oxygen, from the treated water of the mixed-bed ion exchange device using a gas separation membrane that does not allow water to pass through but allows gases to pass through. In the primary pure water device 20 shown in Figure 3, the degassing membrane device 28 processes the treated water of the mixed-bed ion exchange device 27, but the order of the degassing membrane device 28 and the mixed-bed ion exchange device 27 may be reversed, with the mixed-bed ion exchange device 27 being installed later so that it processes the treated water of the degassing membrane device 28.

[0038] The piping of the secondary pure water system 50 can be made of resins such as polyvinyl chloride, PEEK (polyetheretherketone), PVDF (polyvinylidene fluoride), PTFE (polytetrafluoroethylene), or titanium, as these materials produce fewer leaches from the piping and are less susceptible to deterioration due to temperature changes. While the piping itself may be made of these materials, piping made of other materials may also be used, with a coating or lining made of the aforementioned resins or metals applied to the surface.

[0039] Figure 4 is a schematic diagram of the secondary pure water system 50 of this embodiment. Primary pure water produced by the primary pure water system 20 shown in Figure 3 is supplied to the pure water tank 51 shown in Figure 4 and then supplied to the secondary pure water system 50 by a pump 52. The secondary pure water system 50 has water treatment piping 50a, and the path of the water treatment piping 50a is equipped with the temperature control system 1, degassing membrane device 53, ultraviolet irradiation device 54, non-regenerative ion exchange device (polisher) 55, and ultrafiltration membrane device 56 of the above embodiment. In the secondary pure water system 50, a thermometer 15 of the temperature control system 1 is provided on the inlet side of the degassing membrane device 53. A portion of the secondary pure water (ultrapure water) produced by the secondary pure water system 50 is supplied to the point of use (POU) 500 for use, and the unused secondary pure water is returned to the pure water tank 51 via the circulation piping 50b.

[0040] During steady-state operation, the water to be treated in the secondary pure water system 50 is controlled by the temperature control system 1 to maintain a constant temperature, for example, within the range of room temperature to 80°C. The water to be treated is continuously supplied to the secondary pure water system 50 at a constant flow rate for treatment. However, when the secondary pure water system 50 is started or stopped, the water to be treated is cooled using the temperature control system 1. In addition, the secondary pure water system 50 may also circulate heated hot water within the system as needed to perform thermal sterilization. The circulation path of the secondary pure water system 50, consisting of water treatment piping 50a, circulation piping 50b, and water treatment equipment within the secondary pure water system 50, extends for example from 0.2 km to 3 km. When the water in the system is heated or cooled, expansion and contraction of the piping materials occur, which may lead to deterioration of the ultrapure water quality due to piping deterioration or damage to the piping. In particular, rapid temperature changes during overshoot can significantly accelerate piping deterioration and damage. Since the secondary pure water system 50 of this embodiment has the temperature control system 1 described above, these problems can be avoided.

[0041] Figure 5 schematically shows a medical water production apparatus 30 as a primary pure water apparatus in another embodiment. The following describes an example of raising the temperature of the water to be treated, but the same procedure applies when lowering the temperature. The pharmaceutical water production apparatus 30 is used for the production of pharmaceutical water, particularly purified water. The pharmaceutical water production apparatus 30 is equipped with a raw water tank (TK) 31, a temperature control system 1 of the above embodiment, a reverse osmosis membrane device (RO) 32, and an electrodeionizer (EDI) 33 in this order, and produces pharmaceutical water by treating raw water. The pharmaceutical water production apparatus 30 is equipped with a water supply pipe L1 that sequentially sends the raw water stored in the raw water tank (TK) 31 to each water treatment device installed in the pharmaceutical water production apparatus 30, and a circulation pipe L2 that circulates all or part of the produced pharmaceutical water back to the raw water tank (TK) 31. An ultrafiltration membrane for producing water for injection from purified water may be installed downstream of the branching point of the circulation pipe L2 in the water supply pipe L1.

[0042] Furthermore, in the pharmaceutical water production apparatus 30, when the water to be treated is cooled using the temperature control system 1, both the first control valve 13 and the second control valve 14 are at a predetermined opening degree. The pressure control unit 18a and the temperature control unit 18b control the opening degrees of the first control valve 13 and the second control valve 14 to gradually decrease, thereby enabling cooling at a constant rate.

[0043] The reverse osmosis membrane apparatus 32 has the same configuration as the reverse osmosis membrane apparatus 25 shown in Figure 3. The electrodeionizer 33 has, for example, an anion exchange membrane and a cation exchange membrane alternately arranged between the anode and the cathode, and alternately has a desalination chamber separated by the anion exchange membrane and the cation exchange membrane, and a concentration chamber into which concentrated water containing the removed ionic components flows. The electrodeionizer 33 has a mixture of anion exchange resin and cation exchange resin filled in the desalination chamber, and electrodes for applying a DC voltage. The electrodeionizer 33 can continuously remove ions and other substances from the water to be treated, and can produce high-quality treated water. The ultraviolet irradiation device 34 has the same configuration as the ultraviolet irradiation device 26 shown in Figure 3.

[0044] In the pharmaceutical water production apparatus 30 shown in Figure 5, after producing pharmaceutical water for a predetermined time, the production of pharmaceutical water is interrupted and sterilization is performed inside the production apparatus. The period during which pharmaceutical water production is continued is usually from 1 day to 6 months, meaning that sterilization is performed once every 1 day to 6 months. To effectively prevent contamination by bacteria, etc., it is more preferable to sterilize once every 1 day to 2 months, and even more preferable to sterilize once a week. If the interval between sterilization treatments is too long, it becomes difficult to effectively prevent contamination by bacteria, etc. Conversely, if the interval between sterilization treatments is too short, the production time for pharmaceutical water will be insufficient, and the production efficiency will decrease.

[0045] Sterilization of the pharmaceutical water production apparatus 30 is carried out as follows. First, valves and the like (not shown) inside the pharmaceutical water production apparatus 30 are closed to create a closed circulation system within the pharmaceutical water production apparatus 30 using a water supply pipe L1 and circulation piping L2. Specifically, the supply of raw water to the raw water tank (TK) 31 and the supply of treated water from the electric deionizer 33 to the downstream stage are stopped. Next, the raw water in the raw water tank (TK) 31 is heated to the temperature of the sterilization heating water by the temperature control system 1. The heating water is gradually heated to the desired temperature while circulating inside the pharmaceutical water production apparatus 30. The heating rate at this time is, for example, 1°C / min to 10°C / min. When the raw water reaches the temperature of the sterilization heating water, the heating water is circulated inside the pharmaceutical water production apparatus 30 to sterilize the system. Here, the temperature of the sterilization heating water is 60°C or higher, preferably between 60°C and 90°C. Furthermore, the sterilization time (heated water circulation time) is the time required for sufficient sterilization, depending on the configuration of the manufacturing equipment. For example, it is 30 to 120 minutes at 60°C and 30 to 120 minutes at 80°C.

[0046] In the pharmaceutical water production apparatus 30 of this embodiment, a thermometer 15 of the temperature control system 1 is provided on the inlet side of the reverse osmosis membrane device (RO) 32. The temperature control unit 18b adjusts the opening of the second control valve 14 based on the value detected by the thermometer 15 so that the rate of heating of the raw water (rate of temperature change) is a predetermined value in the range of 1°C / min to 10°C / min. The pressure control unit 18a adjusts the opening of the first control valve 13 based on the value detected by the pressure gauge 16. By doing so, a rapid rise in temperature at the start of heating can be suppressed, thereby reducing the heat load on the piping and water treatment equipment within the pharmaceutical water production apparatus 30 and preventing a decrease in the functionality of the apparatus.

[0047] Figure 6 is a schematic diagram of the water for injection production apparatus 70. The water for injection production apparatus 70 produces water for injection by processing purified water produced by the pharmaceutical water production apparatus 30. The water for injection production apparatus 70 has a water for injection production section 71 and a circulation section 72. The water for injection production section 71 is an ultrafiltration membrane apparatus or a distillation apparatus that produces water for injection from purified water. The circulation section 72 has a water treatment pipe 70a and, along the path of the water treatment pipe 70a, a water for injection tank 73 and the temperature control system 1 of the above embodiment. A portion of the produced water for injection is supplied to the place of use (POU) 75, and the unused water for injection is returned to the water for injection tank via the circulation pipe 70b. In the water for injection production apparatus 70, a thermometer 15 of the temperature control system 1 is provided upstream of the place of use (POU) 75.

[0048] In this case, while the water for injection is being produced on a steady basis, the water temperature in the water for injection production apparatus 70 is maintained at, for example, 80°C. However, when the water for injection production apparatus 70 is started and stopped, the water in the system may cool down to room temperature. During this cooling down, the temperature difference between the steady-state operating temperature of the water for injection production apparatus 70 and room temperature is large, which can cause deterioration or damage to the apparatus. The water for injection production apparatus 70 of this embodiment has the temperature control system 1 described above, so these problems can be avoided. [Examples]

[0049] Next, examples will be described. The present invention is not limited to the following examples.

[0050] (Example 1) Using the same apparatus as shown in Figure 1, the raw water was heated using a heat exchanger. The conditions at that time were as follows: Raw water temperature: 15℃ Set water temperature after heating: 40℃ Heating time (time from the start of heating until the set water temperature is reached after heating is complete): 6 minutes Heating medium (pressure to the first control valve): Steam (0.7 MPa)

[0051] Figure 7 shows the elapsed time from the start of heating, the raw water temperature after heating (treated water temperature), the set pressure of the first control valve controlled by the pressure control unit, and the set temperature of the second control valve controlled by the temperature control unit in the embodiment. From Figure 7, it can be seen that the set temperature and the treated water temperature are in close agreement, indicating that the heating was accurately controlled. In this embodiment, the set pressure adjusted by the first control valve is set to remain constant (the rate of increase in the set pressure is zero) at the same time as the time it takes to reach the water temperature after heating. However, even if the timing at which the set pressure adjusted by the first control valve becomes constant differs from the time it takes to reach the water temperature after heating, it is still possible to heat the water with minimal overshoot.

[0052] (Example 2) In Example 1, the raw water was heated by a heat exchanger in the same manner as in Example 1, except that the set temperature of the temperature control unit was fixed to the temperature of the raw water after heating, thus employing so-called feedback control. The results are shown in Figure 8. From Figure 8, it can be seen that in Example 2 as well, the set temperature and the treated water temperature were in close agreement, indicating that the heating was accurately controlled.

[0053] (Example 3) Using the same apparatus and control as in Example 1, the temperature was reduced from 40°C to 15°C in 6 minutes. The results are shown in Figure 9. It was confirmed that temperature reduction with minimal overshoot is possible even in this case.

[0054] (Comparative example) The raw water was heated in the same manner as in the example, except that the first control valve in the example was replaced with a pressure reducing valve and the pressure on the outlet side of the pressure reducing valve was set to 0.2 MPa. Figure 10 shows the elapsed time from the start of heating, the raw water temperature after heating (treated water temperature), and the set temperature of the second control valve in the comparative example. In Figure 10, the parts where the treated water temperature is higher and lower than the set temperature are overshoots. In the comparative example, it can be seen that multiple severe overshoots occurred in the initial stages of heating. [Explanation of Symbols]

[0055] 1: Temperature control system, 10: Heat exchanger, 10a: Supply pipe, 11a: Supply pipe, 11b: Water supply pipe, 12a: Supply pipe, 12a: Supply pipe, 12b: Discharge pipe, 13: First control valve, 14: Second control valve, 15: Thermometer, 16: Pressure gauge, 18a: Pressure control unit, 18b: Temperature control unit, 20: Primary pure water system, 21: Activated carbon system, 22: Cation exchange system, 23: Decarbonation system, 24: Decomposition treatment system, 25: Reverse osmosis membrane system (RO), 26: Ultraviolet irradiation system (TOC-UV), 27: Mixed bed ion exchange system (MB), 28: Degassing membrane system (MDG) ), 30: Pharmaceutical water production equipment, 31: Raw water tank (TK), 32: Reverse osmosis membrane system (RO), 33: Electrodeionizer (EDI), L1: Water supply pipe, L2: Circulation piping, 50: Secondary pure water system, 50a: Water treatment piping, 50b: Circulation piping, 51: Pure water tank, 52: Pump, 53: Degassing membrane system, 54: Ultraviolet irradiation device, 55: Non-regenerative ion exchange system (polisher) 55, 56: Ultrafiltration membrane system, 70: Water for injection production equipment, 70a: Water treatment piping, 70b: Circulation piping, 71: Water for injection production section, 72: Circulation section, 73: Water for injection tank

Claims

1. In a water purification system that removes impurities from water to be treated to produce primary or secondary pure water, a temperature control system for adjusting the temperature of the water to be treated is provided. A temperature controller is provided inside which the water to be treated and the heat transfer medium are supplied, and which adjusts the temperature of the water to be treated by heat exchange with the heat transfer medium. A water supply pipe for supplying the temperature-controlled water to be treated from the temperature controller to the downstream stage, A heat transfer medium pipe that supplies the heat transfer medium to the temperature controller, The heat transfer tube is provided with a first control valve and a second control valve, which are arranged in order from the upstream side along the flow of the heat transfer medium. A thermometer is installed in the water supply pipe to detect the temperature of the water to be treated inside the water supply pipe and output the detected value. A pressure gauge is provided on the downstream side of the first control valve and the upstream side of the second control valve of the heat transfer tube, which detects the pressure of the heat transfer medium in the heat transfer tube and outputs the detected value. A temperature control unit that controls the opening degree of the second control valve according to the value detected by the thermometer, The system includes a pressure control unit that controls the opening degree of the first control valve according to the value detected by the pressure gauge, The pressure control unit is characterized by controlling the opening degree of the first control valve based on the deviation between a preset pressure change pattern and the detected value of the pressure gauge. Temperature control system.

2. The temperature control system according to claim 1, wherein the temperature control unit provides feedback control of the opening degree of the second control valve according to the value detected by the thermometer.

3. The temperature control system according to claim 1, wherein the temperature control unit controls the opening degree of the second control valve based on the deviation between a preset temperature change pattern and the value detected by the thermometer.

4. The aforementioned pure water apparatus is equipped with a decomposition treatment device or an ion exchange device. The temperature control system adjusts the temperature of the water to be treated in the decomposition apparatus or ion exchange apparatus. The temperature control system according to claim 1 or 2.

5. The aforementioned pure water system is a medical water production system equipped with a reverse osmosis membrane system and an electro-deionizer. The raw water of the aforementioned medical water production apparatus is used as the water to be treated. The temperature control system adjusts the temperature of the water to be treated. The temperature control system according to claim 1 or 2.

6. In a method for producing pure water by removing impurities from water to be treated to produce primary or secondary pure water, a temperature control method is provided for adjusting the temperature of the water to be treated by heat exchange with a heat transfer medium, A first step involves measuring the temperature of the water to be treated, whose temperature has been adjusted, and, based on the obtained temperature measurement, feedback-controlling the amount of the heat transfer medium supplied to maintain the temperature of the water to be treated within a predetermined range. A temperature control method comprising a second step of measuring the supply pressure of the heat exchange medium and controlling the supply pressure of the heat exchange medium based on the obtained pressure measurement value, based on the deviation from a predetermined pressure change pattern set in advance.

7. The above-mentioned method for producing pure water includes decomposition treatment or ion exchange treatment, The temperature control method according to claim 6, for adjusting the temperature of the water to be treated in the decomposition treatment or ion exchange treatment.

8. The aforementioned pure water production method is a medical water production apparatus that performs reverse osmosis membrane treatment and electrolytic deionization treatment, and in the sterilization process of the medical water production apparatus, The temperature control method described in claim 6 generates heated water, and the heated water is circulated within the pharmaceutical water production apparatus system to sterilize the pharmaceutical water production apparatus system. A method for sterilizing a medical water production device.

9. A method for producing secondary pure water, comprising adjusting the temperature of the water to be treated using the temperature control system described in claim 1.

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