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

Abstract

Provided are a temperature control system and a temperature control method capable of suppressing overshoot during temperature rise or temperature fall of treatment-target water. The temperature control system includes, in a pure water apparatus: a temperature regulator; a water transfer pipe for transferring treatment-target water from the temperature regulator to a subsequent part; a heating medium pipe for supplying a heating medium to the temperature regulator; a first regulation valve and a second regulation valve which are provided to the heating medium pipe sequentially from the upstream side; a thermometer for detecting the temperature of the treatment-target water inside the water transfer pipe; a pressure gauge for detecting the pressure of the heating medium; a temperature control unit for controlling the opening degree of the second regulation valve in accordance with the detected value by the thermometer; and a pressure control unit for controlling the opening degree of the first regulation valve in accordance with the detected value by the pressure gauge. The pressure control unit controls the opening degree of the first regulation valve on the basis of the deviation between a preset pressure change pattern and the detected value by the pressure gauge.

Description

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

[0001] An embodiment of the present invention relates to a temperature control system and a temperature control method for producing primary pure water or secondary pure water, which suppress overshoot at the start of temperature increase or decrease, and a sterilization method for a pharmaceutical water production apparatus and a secondary pure water production method using these systems and methods.

[0002] Conventionally, primary pure water has been used in the production of ultrapure water and as pharmaceutical water (purified water). Ultrapure water produced from primary pure water is used in semiconductor manufacturing processes. Primary pure 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, an ultrafiltration apparatus, an ultraviolet irradiation apparatus, etc. For example, the primary pure water apparatus removes color components in raw water, and further removes or decomposes 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 contained 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 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 increased or decreased (see, for example, Patent Document 2).

[0003] 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, an ultrafiltration apparatus, an ultraviolet irradiation apparatus, and a mixed-bed ion exchange apparatus. The water quality of pharmaceutical water is strictly defined by 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).

[0004] JP-A-2015-100733 JP-A-201,7-172932 JP-A-2021-178297

[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 the use of heat exchangers, a heating method is sometimes used in which the amount of heat transfer medium supplied is feedback-controlled based on the temperature of the heated water to be treated. With this method, for example, it has been found that in the initial stages after heating starts, an excessive amount of heat transfer medium is supplied, and a phenomenon called overshoot occurs where the water temperature of the treated water exceeds the set value. 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 and failure of piping, etc. If steam usage increases rapidly, it is necessary to take measures such as increasing the number of operating boilers to cope with the increased usage. Furthermore, even when continuous operation is performed instead of batch operation, it may be necessary to change the amount of treated water supplied to the downstream stage in order to respond to the operating conditions of the downstream stage when sending treated water to the downstream stage. In that case, it is not possible to operate in a completely continuous manner, and operation must be repeated on and off, similar to batch operation. In that case, overshoot may occur each time operation is restarted and stopped. In addition, in the production of pharmaceutical water, after periodic sterilization with heated water, the production equipment system is allowed to cool to a temperature suitable for pharmaceutical water production. Therefore, if overshoot occurs each time sterilization is performed, it may accelerate deterioration and failure of piping, etc., similar to urea decomposition equipment. Similarly, in the production of ultrapure water (secondary pure water), the temperature of the water to be treated may be raised or lowered.

[0006] Embodiments of the present invention have been made to solve the above-mentioned problems, and 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.

[0007] To solve the above problems, this embodiment has the following configuration. [1] A pure water apparatus for producing primary or secondary pure water by removing impurities from water to be treated, comprising a temperature control system for adjusting the temperature of the water to be treated, the system comprising: a temperature controller into which the water to be treated and a 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-adjusted water to be treated from the temperature controller to a downstream stage; a heat transfer medium pipe for supplying the heat transfer medium to the temperature controller; a first control valve and a second control valve provided in the heat transfer medium pipe in order from the upstream side along the flow of the heat transfer medium; a thermometer provided in the water supply pipe for detecting the temperature of the water to be treated in the water supply pipe and outputting a detected value; a pressure gauge provided downstream of the first control valve and upstream of the second control valve in the heat transfer medium pipe for detecting the pressure of the heat transfer medium in the heat transfer medium pipe and outputting a detected value; a temperature control unit for controlling the opening degree of the second control valve according to the detected value of the thermometer; and a pressure control unit for controlling the opening degree of the first control valve according to the detected value of the pressure gauge. A temperature control system characterized in that 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 detected value of the pressure gauge. [2] The temperature control system according to claim [1], wherein the temperature control unit provides feedback control to the opening degree of the second control valve according to the detected value of 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 detected value of the thermometer. [4] The temperature control system according to claim [1] or [2], wherein the pure water apparatus comprises a decomposition apparatus or an ion exchange apparatus, and the temperature control system adjusts the temperature of the water to be treated by the decomposition apparatus or ion exchange apparatus. [5] The temperature control system according to claim [1] or [2], wherein the pure water apparatus is a medical water production apparatus comprising a reverse osmosis membrane apparatus and an electrodeionizer, and the raw water of the medical water production apparatus is used as the water to be treated, and the temperature control system adjusts the temperature of the water to be treated.

[0008] [6] A method for producing pure water to remove impurities from water to be treated to produce primary pure water or secondary pure water, comprising a temperature control method for adjusting the temperature of the water to be treated by heat exchange with a heat transfer medium, the method comprising: a first step of measuring the temperature of the water to be treated after adjusting the temperature, and based on the obtained temperature measurement value, feedback control of the supply amount of the heat transfer medium that is heat-exchanged with the water to be treated so as to maintain the temperature of the water to be treated within a predetermined range; and a second step of measuring the supply pressure of the heat transfer medium that is heat-exchanged, and based on the obtained pressure measurement value, controlling the supply pressure of the heat transfer medium that is heat-exchanged based on the deviation from a predetermined pressure change pattern set in advance. [7] The method for producing pure water comprising a decomposition treatment or an ion exchange treatment, wherein the temperature of the water to be treated in the decomposition treatment or ion exchange treatment is adjusted, the temperature control method according to [6]. [8] The method for producing pure water is a pharmaceutical water production apparatus that performs reverse osmosis membrane treatment and electrolytic deionization treatment, wherein in the sterilization step of the pharmaceutical water production apparatus, heated water is generated by the temperature control method described in [6], and the heated water is circulated within the pharmaceutical water production apparatus system to sterilize the pharmaceutical water production apparatus system, the method for sterilizing the pharmaceutical water production apparatus system. [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]. The symbol "~" indicates a numerical range including the numbers before and after it. Furthermore, the pure water apparatus includes a primary pure water apparatus and a secondary pure water apparatus, the primary pure water includes primary pure water for semiconductor manufacturing and purified water for pharmaceutical use, and the secondary pure water includes, but is not limited to, secondary pure water for semiconductor manufacturing and water for injection for pharmaceutical use. Heating means applying heat to an object, raising the temperature means gradually raising the temperature of an object, and lowering the temperature means gradually lowering the temperature of an object. In other words, even if something is being heated, if the temperature of the object being heated does not rise, it is not called a temperature increase; and if the temperature of the object being heated decreases while it is being heated, it is called a temperature decrease.

[0009] According to the temperature control system and temperature control method of this embodiment, it is possible to suppress overshoot when the temperature of the water to be treated rises or falls.

[0010] This is a schematic diagram of the temperature control system of this embodiment. This is a schematic graph showing the change in the temperature of the heated water to be treated over time when using the temperature control system of this embodiment and a conventional heating method. This is a schematic diagram of the primary pure water system of this embodiment. This is a schematic diagram of the secondary pure water system of this embodiment. This is a schematic diagram of the primary pure water system of another embodiment. This is a schematic diagram of the secondary pure water system of another embodiment. This is a graph showing the relationship between the elapsed time from the start of heating and the treated water temperature in Example 1. This is a graph showing the relationship between the elapsed time from the start of heating and the treated water temperature in Example 2. This is a graph showing the relationship between the elapsed time from the start of cooling and the treated water temperature in Example 3. This is a graph showing the relationship between the elapsed time from the start of heating and the treated water temperature in a comparative example.

[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 heating the water to be treated to raise its temperature will be described below, but the same applies to lowering or cooling the water.

[0012] The temperature control system 1 includes a heat exchanger 10. The heat exchanger 10 functions as a temperature controller. In this embodiment, the heat exchanger 10 heats the water to be treated by heat exchange between the water to be treated 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 water supply pipe 11b that sends the heated water to the downstream stage. The water 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. The supply pipe 12a is a heat transfer medium pipe that supplies the heat transfer medium. A first control valve 13 and a second control valve 14 are provided along 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 using steam, 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 heating of the water to be treated (rate of temperature change) within a predetermined range. By setting a heating pattern (a graph representing the relationship between elapsed time and temperature) in advance in the program, the temperature control unit 18b calculates the deviation between the value detected by the thermometer 15 and the water temperature (set value) of the set heating pattern. Based on this deviation, the temperature control unit 18b sends a command signal to the second control valve 14 to change the opening degree. As a result, the opening degree of the second control valve 14 is controlled, and the amount of heat transfer medium supplied is adjusted to follow the heating pattern. The heating pattern is, for example, a step-like pattern that changes (increases) the temperature at each minute time interval. The heating 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 setting a heating pattern, a predetermined heating rate may be set in the program, and the set value may be calculated 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) may be set in advance in the program, and feedback control may 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 pressure control unit 18a has a program for controlling the supply pressure of the heat transfer medium stored in it. The program calculates the deviation between the detected value of the pressure gauge 16 and the set value. For example, 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 rate may be set in the program, and the set value may be calculated to create a pressure boost pattern. Then, based on the deviation, the pressure control unit 18a transmits a command signal to change the opening degree to the first control valve 13. As a result, the opening degree of the first control valve 13 is controlled so that the supply pressure of the heat medium follows the pressure increase pattern, and the supply pressure of the heat medium is adjusted. In the second step, the rate of change of the supply pressure of the heat medium is maintained 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] For example, at the beginning of the heating process, the second control valve 14 is gradually opened to begin supplying the heat transfer medium to the heat exchanger 10. At the beginning of the 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 pressure reduction can be set by a program such as the pressure boosting pattern described above. This makes it possible to suppress a rapid rise in the temperature of the treated water (overshoot) at the start of heat transfer medium supply and the start of the increase in 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 beginning 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, pressure reducing valves can control (reduce) the pressure to a constant value, but they cannot perform feedback control. For example, a pressure reducing valve reduces a steam pressure of 0.7 MPa to a constant pressure of 0.2 MPa and maintains it at a nearly constant level. 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. Consequently, this raises concerns about increased steam consumption and its impact on the equipment.

[0022] Next, the components of the temperature control system 1 of the 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 a plate type, a multi-tube heat exchanger (shell and tube type heat exchanger), a spiral type heat exchanger, a double-tube type heat exchanger, etc., without any particular limitations, 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. The pressure control valve provides feedback control of the pressure of the heat transfer medium flowing through the first control valve 13 based on the value detected by the pressure gauge 16. When the first control valve 13 is a pressure control valve, it 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 matches the opening degree of the first control valve 13, and a drive unit that operates the valve body in response to the current signal or air signal from the positioner.

[0025] The second control valve 14 is, for example, a temperature control valve. The temperature control valve 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. When the second control valve 14 is a temperature control valve, the opening degree of the temperature control valve is adjusted based on a control signal from the temperature control unit 18b, thereby controlling the flow rate of the heat transfer medium, and as a result, the temperature of the water to be treated in the water supply pipe 11b is adjusted. When the second control valve 14 is a temperature control valve, it 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 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 apparatus using the temperature control system 1 of this embodiment will be described. The following description will mainly 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 apparatus 20 of this embodiment. The primary pure water apparatus 20 is equipped with, in this order, an activated carbon apparatus 21, a cation exchange apparatus (SC) 22, a decarbonation tower (DG) 23, a temperature control system 1, a decomposition apparatus 24, a reverse osmosis membrane apparatus (RO) 25, an ultraviolet irradiation apparatus (TOC-UV) 26, a mixed-bed ion exchange apparatus (MB) 27, and a degassing membrane apparatus (MDG) 28. The primary pure water apparatus 20 processes raw water to produce primary pure 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. The activated carbon system 21 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 using activated carbon. 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. The cation exchange device 22 exchanges and removes cation components from the raw water using the cation exchange resin. 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 tank is adjusted to 9 or higher, thereby decomposing the urea in the water to be treated.

[0032] Alternatively, an ion exchange device can be used instead of the decomposition 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 primary pure water device 20 uses the temperature control system 1 of the above embodiment, it is possible to keep the water being treated by the ion exchange device at the optimal temperature at all times, and therefore 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 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 in the case of batch operation is, for example, 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. For example, steam is supplied to the first control valve 13 as a heat transfer medium. The pressure of the heat transfer medium (steam) 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 described 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 at which the pressure rises, a rapid rise in temperature at the start of heating can be suppressed. As a result, the heat load on the piping and equipment in the primary pure water system 20 can be reduced, and a deterioration in the function of the system can be prevented. In particular, the water to be treated in the decomposition treatment device has an appropriate temperature range. Below this appropriate temperature range, the desired reaction will not proceed. If the temperature exceeds this appropriate temperature range, side reactions will proceed, and sufficient water quality cannot be obtained. 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 a 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 is equipped with a reverse osmosis membrane. The reverse osmosis membrane removes salts and impurities such as ionic and colloidal organic matter from the urea decomposition water to produce concentrated water and permeate. For example, the reverse osmosis membrane apparatus 25 can use a cellulose triacetate asymmetric membrane or a polyamide composite membrane, and membrane modules such as sheet flat membranes, spiral membranes, tubular membranes, and hollow fiber membranes can be used. In particular, from the viewpoint of increasing the impurity removal rate, the reverse osmosis membrane is preferably a polyamide composite membrane, and the membrane shape is preferably a spiral membrane. The impurity removal rate 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 is equipped with a gas separation membrane that does not allow water to pass through but allows gas to pass through. The degassing membrane device 28 removes gas, especially dissolved oxygen, from the treated water of the mixed-bed ion exchange device using the gas separation membrane. 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 after the degassing membrane device 28 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 resin or metal applied to its surface.

[0039] Figure 4 is a schematic diagram of the secondary pure water system 50 of this embodiment. The secondary pure water system 50 processes primary pure water to produce secondary pure water. Primary pure water is produced, for example, by the primary pure water system 20 shown in Figure 3. Primary pure water is supplied to the pure water tank 51 shown in Figure 4 and 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 and used. Unused secondary pure water at the usage location 500 is returned to the pure water tank 51 via the circulation pipe 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, a constant temperature in the range of room temperature to 80°C. The water to be treated is also 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 is a schematic diagram showing a pharmaceutical water production apparatus 30 as a primary pure water apparatus of another embodiment. The following description will focus on an example of raising the temperature of the water to be treated, but the same procedure applies to lowering the temperature. The pharmaceutical water production apparatus 30 is used to produce 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-described embodiment, a reverse osmosis membrane apparatus (RO) 32, and an electrodeionizer (EDI) 33 in this order. The pharmaceutical water production apparatus 30 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 apparatus provided 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 high-quality treated water can be obtained. The ultraviolet irradiation apparatus 34 has the same configuration as the ultraviolet irradiation apparatus 26 shown in Figure 3.

[0044] In the pharmaceutical water production apparatus 30 shown in FIG. 5, after producing pharmaceutical water for a predetermined time, the production of pharmaceutical water is interrupted and sterilization inside the production apparatus is performed. The time for continuously producing pharmaceutical water is usually from 1 day to 6 months, that is, sterilization is performed once every 1 day to 6 months. In order to effectively prevent contamination by bacteria and the like, it is more preferable to perform sterilization once every 1 day to 2 months, and even more preferable to perform sterilization once a week. If the interval between sterilization treatments is too long, it becomes difficult to effectively prevent contamination by bacteria and the like. Also, if the interval between sterilization treatments is too short, the production time of pharmaceutical water becomes insufficient and the production efficiency decreases.

[0045] Sterilization of the pharmaceutical water production apparatus 30 is performed as follows. First, valves and the like (not shown) inside the pharmaceutical water production apparatus 30 are closed to form a closed circulation system by the water supply pipe L1 and the circulation pipe L2 inside the pharmaceutical water production apparatus 30. Specifically, the supply of raw water to the raw water tank (TK) 31 and the supply of treated water from the electro-deionization apparatus 33 to the subsequent stage are stopped. Subsequently, the raw water in the raw water tank (TK) 31 is heated by the temperature control system 1 to the temperature of the heating water for sterilization. The heating water is gradually heated to a 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. In a state where the raw water has reached the temperature of the heating water for sterilization, the heating water is circulated inside the pharmaceutical water production apparatus 30 to sterilize the system. Here, the temperature of the heating water for sterilization is 60 ° C. or higher, and preferably 60 ° C. to 90 ° C. Also, the sterilization time (circulation time of the heating water) is a time sufficient for sterilization according to the configuration of the production apparatus. For example, in the case of 60 ° C., it is 30 minutes to 120 minutes, and in the case of 80 ° C., it is 30 minutes to 120 minutes.

[0046] In the pharmaceutical water production device 30 of the present 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 degree of the second regulating valve 14 based on the detected value of the thermometer 15 so that the heating rate (temperature change rate) of the raw water becomes a predetermined value within the range of 1°C / min to 10°C / min. The pressure control unit 18a adjusts the opening degree of the first regulating valve 13 according to the detected value of the pressure gauge 16. Since these can suppress a rapid temperature rise at the start of heating, the heat load on the pipes and water treatment devices in the pharmaceutical water production device 30 can be reduced, and the degradation of the device's function can be prevented.

[0047] FIG. 6 is a diagram schematically showing an injection water production device 70. The injection water production device 70 processes purified water to produce injection water. The purified water is, for example, produced by the pharmaceutical water production device 30. The injection water production device 70 has an ultrafiltration membrane device or a distillation device as an injection water production unit 71, which produces injection water from purified water. The circulation unit 72 has a water treatment pipe 70a, an injection water tank 73 on the path of the water treatment pipe 70a, and the temperature control system 1 of the above embodiment. A part of the produced injection water is supplied to the point of use (POU) 75, and the unused injection water is refluxed to the injection water tank via the circulation pipe 70b. In the injection water production device 70, a thermometer 15 of the temperature control system 1 is provided upstream of the point of use (POU) 75.

[0048] Here, while the injection water is being produced steadily, in the injection water production device 70, for example, the water temperature is maintained at 80°C. However, when the injection water production device 70 is operating and stopping, the water in the system may be cooled down to room temperature. During this cooling process, since the temperature difference between the steady operating temperature of the injection water production device 70 and room temperature is large, deterioration and damage of the device may occur. Since the injection water production device 70 of the present embodiment has the above-described temperature control system 1, these problems can be avoided.

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

[0050] (Example 1) Raw water was heated using a heat exchanger with the same apparatus as shown in Figure 1. The conditions were as follows: Raw water temperature: 15°C Set water temperature after heating: 40°C Heating time (time from the start of heating until the set water temperature is reached after heating is complete): 6 minutes Heating medium (supply 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 controlled accurately. In this embodiment, the set pressure adjusted by the first control valve is set to be constant (the rate of increase of 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, heating with minimal overshoot is still possible.

[0052] (Example 2) 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 in Example 1 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 the case of cooling.

[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 (treated water temperature) after heating, 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.

[0055] 1: Temperature control system, 10: Heat exchanger, 11a: Supply pipe, 11b: Water 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 system, 55: Non-regenerative ion exchange system (polisher), 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. A temperature controller into which water to be treated and a 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 that sends the temperature-adjusted water to be treated from the temperature controller to a downstream stage; a heat transfer medium pipe that supplies the heat transfer medium to the temperature controller; a first control valve and a second control valve provided in the heat transfer medium pipe in order from the upstream side along the flow of the heat transfer medium; a thermometer provided in the water supply pipe that detects the temperature of the water to be treated in the water supply pipe and outputs the detected value; a pressure gauge provided downstream of the first control valve and upstream of the second control valve in the heat transfer medium pipe that detects the pressure of the heat transfer medium in the heat transfer medium pipe and outputs the detected value; a temperature control unit that controls the opening degree of the second control valve according to the detected value of the thermometer; and a pressure control unit that controls the opening degree of the first control valve according to the detected value of 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 detected value of the pressure gauge. A temperature control system for adjusting the temperature of the water to be treated in a water treatment apparatus that removes impurities from the water to be treated to produce primary or secondary pure water.

2. The temperature control system according to claim 1, wherein the temperature control unit provides feedback control to 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 temperature control system according to claim 1 or 2, wherein the pure water apparatus comprises a decomposition apparatus or an ion exchange apparatus, and the temperature control system adjusts the temperature of the water to be treated by the decomposition apparatus or ion exchange apparatus.

5. The pure water apparatus is a medical water production apparatus comprising a reverse osmosis membrane apparatus and an electrodeionizer, wherein the raw water of the medical water production apparatus is treated water, and the temperature control system adjusts the temperature of the treated water, according to claim 1 or 2.

6. A method for producing pure water to remove impurities from water to be treated and produce primary pure water or secondary pure water, comprising: a first step of measuring the temperature of water to be treated, and based on the obtained temperature measurement, feedback control of the supply amount of a heat transfer medium that exchanges heat with the water to be treated so as to maintain the temperature of the water to be treated within a predetermined range; and a second step of measuring the supply pressure of the heat transfer medium that exchanges heat with the water, and based on the obtained pressure measurement, controlling the supply pressure of the heat transfer medium that exchanges heat with the water based on the deviation from a predetermined pressure change pattern set in advance, wherein the temperature of the water to be treated is adjusted by heat exchange with the heat transfer medium.

7. The method for producing pure water, comprising a decomposition treatment or an ion exchange treatment, wherein the temperature of the water to be treated in the decomposition treatment or ion exchange treatment is adjusted, according to claim 6.

8. The method for producing pure water is a medical water production apparatus that performs reverse osmosis membrane treatment and electrolytic deionization treatment, wherein in the sterilization step of the medical water production apparatus, heated water is generated by the temperature control method described in claim 6, and the heated water is circulated within the medical water production apparatus system to sterilize the medical water production apparatus system.

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 claim 1.

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