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

Abstract

Disclosed are a temperature control system and a temperature control method, with which it is possible to suppress overshoot during heating or cooling of water to be treated. In a pure water device, the temperature control system is provided with: a temperature regulator; a water supply pipe for supplying water to be treated from the temperature regulator to a subsequent stage; a heat medium pipe for supplying a heat medium to the temperature regulator; a first regulating valve and a second regulating valve that are provided in the heat medium pipe in this order from the upstream side; 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 medium; a temperature control unit for controlling the opening degree of the second regulating valve by using a detection value of the thermometer; and a pressure control unit for controlling the opening degree of the first regulating valve by using a detection value of the pressure gauge. The pressure control unit calculates a deviation between a set value of pressure obtained from a preset pressure change pattern and the detection value of the pressure gauge for each minute detection time, and controls the opening degree of the first regulating valve by the calculated deviation.

Description

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

[0001] This embodiment 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 increase or decrease, and a sterilization method for a pharmaceutical water production apparatus and a secondary pure water production method using these.

[0002] Conventionally, primary pure water has been used for 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 ultrafiltration apparatus, an ultraviolet irradiation apparatus, etc. The primary pure water apparatus removes, for example, color components in the raw water, and further removes or decomposes, in order, alkaline earth metals, dissolved carbon dioxide, and hardly decomposable substances such as urea in the raw water by a cation exchange apparatus, a decarbonation apparatus, and a hardly decomposable substance decomposition apparatus for urea, etc. (see, for example, Patent Document 1). In the hardly decomposable substance 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 hardly decomposable substances such as urea in the water to be treated are oxidatively decomposed. At this time, in order to increase the decomposition efficiency of hardly decomposable substances such as 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] 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 electrodialysis deionization apparatus, an activated carbon adsorption apparatus, a ultrafiltration apparatus, an ultraviolet irradiation apparatus, and a mixed bed ion exchange apparatus. The water quality of pharmaceutical water is strictly defined by the pharmacopoeias of each country. For example, in order to prevent the generation or mixing 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-2017-172932 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 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 decomposition treatment of recalcitrant substances described above, a predetermined amount of water to be treated is stored in a treatment tank, recalcitrant substances such as urea are decomposed, and the treated water from which the recalcitrant substances such as urea have been decomposed 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. 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. Additionally, 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] This embodiment was 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.

[0007] This embodiment has the following configuration: [1] A temperature control system for adjusting the temperature of water to be treated in a pure water apparatus for producing primary or secondary pure water by removing impurities from water to be treated, 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. The temperature control system of this embodiment has a temperature control unit that controls the opening degree of the second control valve using the detected value of the thermometer, and a pressure control unit that controls the opening degree of the first control valve using the detected value of the pressure gauge, wherein the pressure control unit may calculate the deviation between a set pressure value obtained from a preset pressure change pattern and the detected value of the pressure gauge at minute detection time intervals, and control the opening degree of the first control valve based on the calculated deviation. [2] The temperature control system according to [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 [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. In the temperature control system of this embodiment, the temperature control unit may calculate the deviation between the set temperature value obtained from a preset temperature change pattern and the detected value of the thermometer at each minute detection time interval, and control the opening degree of the second control valve based on the calculated deviation.[4] The pure water apparatus comprises a recalcitrant substance decomposition apparatus or an ion exchange apparatus, and the temperature control system adjusts the temperature of the water to be treated by the recalcitrant substance decomposition apparatus or ion exchange apparatus, the temperature control system according to claim [1] or [2]. [5] The pure water apparatus is a pharmaceutical water production apparatus comprising one or more selected from a reverse osmosis membrane apparatus and an electrodeionizer, and the raw water of the pharmaceutical water production apparatus is treated water, and 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 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 whose temperature has been adjusted and, based on the obtained temperature measurement value, feedback-controlling the amount supplied 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. The temperature control method of this embodiment may include a first step of detecting the temperature of the water to be treated whose temperature has been adjusted, and using the detected temperature values ​​at minute detection intervals to control the supply pressure of the 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 detecting the supply pressure of the heat transfer medium that exchanges heat and controlling the amount of the heat transfer medium that exchanges heat based on the deviation at minute detection intervals between the pressure obtained from a predetermined pressure change pattern set in advance and the detected value of the supply pressure of the heat transfer medium. [7] The pure water production method includes a decomposition treatment or an ion exchange treatment, and the temperature of the water to be treated in the decomposition treatment or ion exchange treatment is adjusted according to the temperature control method of [6]. In this embodiment, the decomposition device is preferably a recalcitrant substance decomposition device, and may be a recalcitrant substance decomposition device that decomposes recalcitrant substances with an oxidizing agent. [8] The method for producing pure water is a pharmaceutical water production apparatus that performs one or more treatments selected from 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, a pure water system includes a primary pure water system and a secondary pure water system. Primary pure water includes primary pure water for semiconductor manufacturing and purified water for pharmaceutical use, while secondary pure water includes secondary pure water for semiconductor manufacturing and water for injection for pharmaceutical use, but is not limited to these. Heating means applying heat to an object, raising the temperature means gradually increasing the temperature of the object, and lowering the temperature means gradually decreasing the temperature of the object. In other words, even if heating is being performed, if the temperature of the object being heated is not rising, it is not called raising the temperature, and if the temperature of the object being heated is decreasing while it is being heated, it is called lowering the temperature.

[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] The following describes this embodiment. 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. The following describes an example of raising the temperature of the water to be treated by heating it, 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 water supply pipe 11b that sends the heated water to the next 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. 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 according to the value detected by the thermometer 15. The pressure control unit 18a adjusts the opening degree of the first control valve 13 according to the value detected by the pressure gauge 16. These controls adjust 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] Furthermore, "controlling according to the detected value" and "controlling based on the detected value" include not only cases where the controlled object is directly controlled using the detected value as input, but also cases where the controlled object is controlled by using the result of calculations performed by one or more predetermined functions using the detected value as input.

[0016] 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 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 the program beforehand, the deviation between the target temperature and the value detected by the thermometer 15 may be calculated at minute detection intervals, and the second control valve 14 may be feedback-controlled based on the calculated deviation.

[0017] The control of the second control valve 14 using the heating pattern will be explained in detail. As described above, the heating pattern is a graph that represents the relationship between elapsed time and temperature. The heating pattern is, for example, a linear function graph represented by Y = At ​​+ B (where A is the heating rate and B is the water temperature at the start of application of the heating pattern), where t is the elapsed time and Y is the temperature. The heating pattern may also be a quadratic function graph of t, a cubic function graph, a higher-order function graph of the third order or higher, or a function graph that combines these for each predetermined time interval. When the heating pattern is a linear function of t, the heating pattern may also be a graph of a combination of linear functions where the heating rate A is different for each predetermined time interval. For example, in time interval 1, there may be a straight line graph that rises to the right where A is greater than 0, in the following time interval 2, there may be a straight line graph that stays flat with A being 0, and in the next time interval 2, there may be a straight line graph that rises to the right where A is greater than 0. In this way, the heating pattern may be a graph that alternates between time intervals in which the temperature rises at a predetermined heating rate and time intervals in which the temperature is kept constant. In this case, the heating rate A may differ for each time interval. Furthermore, the heating pattern may be represented by setting B to 0 in the linear function Y = At ​​+ B, and using a graph that shows the relationship between elapsed time and the temperature increase from the water temperature at the start of heating. Ramp soak control may be used as a control method that includes a temperature change pattern. Also, when adjusting the opening degree of the second control valve, it is not essential to use the heating pattern described above. Instead of a heating pattern, it is possible to set the temperature after heating is complete (target temperature) and adjust the opening degree of the second control valve 14 using simple feedback control. In this case, the temperature of the treated water after heating is complete (target temperature) is set in advance in a program, the deviation between the target temperature and the value detected by the thermometer 15 is calculated at minute detection time intervals, and the temperature control unit 18b performs feedback control of the second control valve 14 based on the calculated deviation. Furthermore, a stepped heating pattern, which alternates between time intervals of heating at a predetermined rate and time intervals of maintaining a constant temperature, is suitable for ramp soak control, and the same applies to the cooling, heating, and cooling patterns described later.

[0018] Next, the deviation between the value detected by the thermometer 15 and the water temperature (set value) of the above-set heating pattern is calculated. With the start of heating set to t=0, the difference (deviation) between the temperature value obtained by the function representing the heating pattern and the value detected by the thermometer 15 is calculated at every minute detection time. Then, the opening degree of the second control valve 14 is controlled according to the calculated deviation. A function that defines the relationship between the calculated deviation and the amount of change in the opening degree of the second control valve 14 is set in advance, and the opening degree of the second control valve 14 can be controlled by changing the opening degree of the second control valve 14 according to the deviation calculated at every minute detection time.

[0019] The minute detection time is a predetermined value between 0.05 seconds and 20 seconds, and is usually between 0.5 seconds and 10 seconds. The minute detection time may always be the same or it may vary. For example, the calculation interval for the deviation using the heating pattern (minute detection time), the calculation interval for the deviation using the pressure boosting pattern (minute detection time), the opening adjustment interval for the first control valve 13 (minute detection time), and the opening adjustment interval for the second control valve 14 (minute detection time) may all be different, or two or more may be the same. The temperature control unit 18b can calculate and output the deviation and adjust the opening of the second control valve 14. The same applies when using the cooling pattern described later.

[0020] 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.

[0021] The cooling pattern is specifically represented by the graph of a linear function Y = Ct + D (where C is the cooling rate and D is the water temperature at the start of the cooling pattern application), where t is the elapsed time and Y is the temperature. The cooling pattern may also be the graph of a quadratic function of t, a cubic function, a higher-order function of degree three or higher, or a combination of these for each predetermined time interval. When the cooling pattern is a linear function of t, it may be the graph of a combination of linear functions where the cooling rate C is different for each predetermined time interval. For example, in time interval 1, it may be a downward-sloping straight line graph where C is less than 0; in the following time interval 2, it may be a flat straight line graph where C is 0; and in the next time interval 2, it may be a downward-sloping straight line graph where C is less than 0. In this case, the cooling pattern may be a graph that alternates between time intervals where the temperature is cooled at a predetermined rate and time intervals where the temperature is kept constant. Alternatively, the cooling pattern may be represented by setting D to 0 in the linear function Y = Ct + D described above, and using a graph that shows the relationship between elapsed time and the decrease in temperature from the water temperature at the start of cooling.

[0022] Next, the deviation between the value detected by the thermometer 15 and the water temperature (set value) of the above-set cooling pattern is calculated. With the start of cooling set to t=0, the difference (deviation) between the temperature value obtained by the function representing the cooling pattern and the value detected by the thermometer 15 is calculated at every minute detection time. Then, the opening degree of the second control valve 14 is controlled according to the calculated deviation. A function that defines the relationship between the calculated deviation and the amount of change in the opening degree of the second control valve 14 is set in advance, and the opening degree of the second control valve 14 can be controlled by changing the opening degree of the second control valve 14 according to the deviation calculated at every minute detection time.

[0023] 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 interval is, for example, 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 adjusting 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.

[0024] The pressure boosting pattern is a graph that represents the relationship between elapsed time and pressure. For example, when elapsed time is t and temperature is Y, the pressure boosting pattern is a graph of a linear function represented by Y = at + b (where a is the pressure boosting rate and b is the supply pressure of the heat transfer medium at the start of the pressure boosting pattern application). The pressure boosting pattern may also be a graph of a quadratic function of t, a cubic function, a higher-order function of the third order or higher, or a function that combines these for each predetermined time interval. When the pressure boosting pattern is a linear function of t, it may also be a graph of a combination of linear functions where the pressure boosting rate a is different for each predetermined time interval. For example, in time interval 1, a may be a straight line graph sloping upwards to the right, in the following time interval 2 a may be a flat straight line graph where a is 0, and in the next time interval 2 a may be a straight line graph sloping upwards to the right where a is greater than 0. In this case, the pressure boosting pattern may be a graph that alternates between time intervals in which the pressure is increased at a predetermined rate and time intervals in which the pressure is kept constant. Furthermore, the pressure boosting pattern may be represented by setting b to 0 in the linear function Y = at + b described above, and using a graph that shows the relationship between elapsed time and the pressure increase from the supply pressure of the heat transfer medium at the start of the boosting process. As a control using a pressure change pattern including a pressure boosting pattern, ramp soak control to increase the pressure may be used. The pressure control unit 18a can calculate and output the deviation and adjust the opening degree of the first control valve 13. The same applies when using the pressure deflation pattern described later.

[0025] Next, the deviation between the detected value of the pressure gauge 16 and the water temperature (set value) of the above-set pressure boosting pattern is calculated. With the start of pressure boosting set to t=0, the difference (deviation) between the pressure value obtained by the function representing the pressure boosting pattern and the detected value of the pressure gauge 1 is calculated at every minute detection time. Then, the opening degree of the first control valve 13 is controlled according to the calculated deviation. A function that defines the relationship between the calculated deviation and the amount of change in the opening degree of the first control valve 13 is set in advance, and the opening degree of the first control valve 13 can be controlled by changing the opening degree of the first control valve 13 according to the deviation calculated at every minute detection time. The pressure control unit 18a can calculate and output the deviation and adjust the opening degree of the first control valve 13. The same applies when using the pressure reduction pattern described later.

[0026] Furthermore, when reducing the pressure of the water to be treated, the pressure reduction pattern should be set so that the pressure setting value is gradually decreased from the initial value. The pressure reduction pattern is, for example, a step-like pattern that changes (decreases) the pressure at 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 is maintained repeatedly. 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.

[0027] Furthermore, the start of heating in the heating pattern and the start of pressure boosting in the pressure boosting pattern do not necessarily have to be the same. The start of cooling in the cooling pattern and the start of pressure drop in the pressure drop pattern do not necessarily have to be the same. Also, the end of heating in the heating pattern and the end of pressure boosting in the pressure boosting pattern do not necessarily have to be the same. It is preferable that the start of heating in the heating pattern and the start of pressure boosting in the pressure boosting pattern are simultaneous. The end of heating may be later than the end of pressure boosting in the pressure boosting pattern. If the end of heating in the heating pattern is later than the end of pressure boosting in the pressure boosting pattern, the control of the opening degree of the second control valve 14 after the end of pressure boosting in the pressure boosting pattern can be performed by normal feedback control using the deviation between the target temperature (set temperature) and the detected value of the thermometer 15. Similarly, pressure control by the first control valve 13 can be performed by setting a target pressure of the heat transfer medium after passing through the first control valve and using feedback control using the deviation between the target pressure and the detected value of the pressure gauge 16. This method is the same for cooling and pressure drop patterns.

[0028] The pressure reduction pattern is specifically represented by the graph of a linear function Y = ct + d (where c is the pressure reduction rate and d is the supply pressure of the heat transfer medium at the start of the pressure reduction pattern application), where t is the elapsed time and Y is the temperature. The pressure reduction pattern may also be the graph of a quadratic function of t, a cubic function, a higher-order function of the third order or higher, or a combination of these for each predetermined time interval. When the pressure reduction pattern is a linear function of t, it may be the graph of a combination of linear functions where the pressure reduction rate c differs for each predetermined time interval. For example, in time interval 1, it may be a downward-sloping straight line graph where c is less than 0; in the following time interval 2, it may be a flat straight line graph where c is 0; and in the next time interval 2, it may be a downward-sloping straight line graph where c is less than 0. In this case, the pressure reduction pattern may be a graph that alternates between time intervals where the pressure is reduced at a predetermined rate and time intervals where the pressure is kept constant. Alternatively, the pressure reduction pattern may be represented by setting d to 0 in the linear function Y = ct + d described above, and using a graph that shows the relationship between elapsed time and the decrease in pressure from the pressure at the start of the pressure reduction.

[0029] Next, the deviation between the value detected by the pressure gauge 16 and the pressure (set value) of the above-set pressure reduction pattern is calculated. With the start of pressure reduction set to t=0, the difference (deviation) between the pressure value obtained by the function representing the pressure reduction pattern and the value detected by the pressure gauge 16 is calculated at every minute detection time. Then, the opening degree of the first control valve 13 is controlled according to the calculated deviation. A function that defines the relationship between the calculated deviation and the amount of change in the opening degree of the first control valve 13 is set in advance, and the opening degree of the first control valve 13 can be controlled by changing the opening degree of the first control valve 13 according to the deviation calculated at every minute detection time.

[0030] 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 the increase in supply amount.

[0031] According to the temperature control system 1 and temperature control method of this embodiment, the first control valve 13 can be used to control the supply pressure of the heat transfer medium so as to suppress a rapid rise in pressure. In particular, it is possible to suppress a rapid rise in the temperature of the treated water (overshoot) when the supply of the heat transfer medium is started or when the supply amount is increased.

[0032] 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.

[0033] 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.

[0034] Next, the configurations 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.

[0035] 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.

[0036] 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 value detected by 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.

[0037] The second control valve 14 is a temperature control valve that adjusts the temperature of the water to be treated in the water supply pipe 11b by, for example, 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.

[0038] 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 showing the primary pure water apparatus 20 of this embodiment. The primary pure water apparatus 20 is equipped with 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 in this order, and produces primary pure water by treating raw water.

[0039] 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.

[0040] 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.

[0041] The cation exchange device 22 has a cation exchange resin, and the cation exchange resin exchanges and removes the cation components in the raw water. As the cation exchange resin, either or both of a strongly acidic cation exchange resin and a weakly acidic cation exchange resin can be used. For scale prevention in the subsequent reverse osmosis membrane device 25, it is preferable to use a strongly acidic cation exchange resin because of its excellent performance in removing alkaline earth metals.

[0042] The decarbonation device 23 performs decarbonation treatment on the cation exchange treated water. In the decarbonation treatment, dissolved carbonic acid in the treated water is removed to generate decarbonated water with a reduced carbonic acid concentration. This can prevent scale in the subsequent reverse osmosis membrane device 25.

[0043] The decomposition treatment device 24 has, for example, one or more treatment tanks configured airtightly, and the treated water is retained in the treatment tank for a certain period of time to decompose and remove hardly decomposable substances such as urea, PFOS (perfluorooctanesulfonic acid), PFOS (perfluorooctanoic acid), and other organic substances in the treated water. In the treatment tank, according to the object to be decomposed, a chemical agent is added to the treated water in a state where the pH is adjusted to an appropriate value. As the chemical agent, oxidizing agents such as ozone, hydrogen peroxide, hypobromous acid, hypochlorous acid, and persulfuric acid are used. Also, the decomposition treatment device may be a biodegradation 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 treated water in a state where the pH of the treated water in the treatment tank is adjusted to 9 or higher to decompose the urea in the treated water.

[0044] It is also possible to use an ion exchange device instead of the decomposition treatment device 24. The ion exchange device has an ion exchange resin, and the ion exchange resin removes the ion components in the water. The ion exchange resin is a cation resin, an anion resin, a boron-selective ion exchange resin, a catalyst resin, or the like. Also in this case, since the treated water of the ion exchange device can always be set to an optimal temperature, it is possible to maintain good treated water quality.

[0045] 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.

[0046] 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 (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 becomes 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 a preferred temperature range, so that treated water of good quality can be obtained.

[0047] 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.

[0048] The reverse osmosis membrane device 25 removes impurities such as salts, ionic and colloidal organic substances in the urea decomposition water to produce concentrated water and permeated water. As the reverse osmosis membrane device 25, a cellulose triacetate-based asymmetric membrane or a polyamide-based composite membrane can be used, and a membrane module in the form of a flat sheet membrane, a spiral membrane, a tubular membrane, or a hollow fiber membrane can be used. Among them, from the viewpoint of enhancing the removal rate of impurities, a polyamide-based composite membrane is preferably used, and the membrane shape is preferably a spiral membrane. The removal rate of impurities may be improved by connecting two reverse osmosis membrane devices 25 in series to form a two-stage reverse osmosis membrane device.

[0049] The ultraviolet irradiation device 26 decomposes organic substances remaining in trace amounts in the treated water of the reverse osmosis membrane device 25 by irradiating ultraviolet rays. The mixed bed ion exchange device 27 adsorbs and removes organic acids and the like generated by the decomposition of organic substances. The degassing membrane device 28 uses a gas separation membrane that allows gas to permeate but does not allow water to permeate to remove gas, particularly dissolved oxygen, in the treated water of the mixed bed ion exchange device. In the primary pure water device 20 shown in FIG. 3, the degassing membrane device 28 treats the treated water of the mixed bed ion exchange device 27. However, the order of the degassing membrane device 28 and the mixed bed ion exchange device 27 may be reversed, and the mixed bed ion exchange device 27 may be provided later so that the mixed bed ion exchange device 27 treats the treated water of the degassing membrane device 28.

[0050] The piping of the secondary pure water device 50 is made of a resin such as polyvinyl chloride, PEEK (polyether ether ketone), PVDF (polyvinylidene fluoride), PTFE (polytetrafluoroethylene), or titanium because it has little elution from the piping and little deterioration due to temperature changes. Although the piping itself may be made of these materials, piping with a coating or lining made of the above-mentioned resin or metal applied to the surface of piping made of other materials may also be used.

[0051] 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 along the path of the water treatment piping 50a are 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.

[0052] 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.

[0053] 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, 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 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. Although Figure 5 shows a medical water production apparatus 30 having both a reverse osmosis membrane apparatus (RO) 32 and an electrodeionizer (EDI) 33, the medical water production apparatus 30 may have only one of the reverse osmosis membrane apparatus (RO) 32 or the electrodeionizer (EDI) 33.

[0054] 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.

[0055] 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 54 has the same configuration as the ultraviolet irradiation apparatus 26 shown in Figure 3.

[0056] 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 one day to six months, meaning that sterilization is performed once every one to six months. To effectively prevent contamination by bacteria, etc., it is more preferable to sterilize once every one to two 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 becomes insufficient, and the production efficiency decreases.

[0057] 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 pipe 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, and preferably 60°C to 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.

[0058] 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 apparatus (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.

[0059] 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.

[0060] 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.

[0061] Next, examples will be described. The present invention is not limited to the following examples.

[0062] (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 Target water temperature after heating: 40°C Heating time (time from the start of heating until the target water temperature is reached after heating is complete): 6 minutes Heating medium (pressure to the first control valve): Steam (0.7 MPa)

[0063] In Example 1, a heating pattern (set temperature of the second control valve) for controlling the second control valve and a pressure boosting pattern (set pressure of the first control valve) for controlling the first control valve were set. The opening degree of the second control valve was controlled by the deviation (temperature difference) between the set temperature obtained from the heating pattern at each minute detection time and the measured value (detected value) of the thermometer. Furthermore, the opening degree of the first control valve was feedback controlled by the deviation (pressure difference) between the set pressure obtained from the pressure boosting pattern and the measured value (detected value) of the pressure gauge at each minute detection time. The minute detection time was 5 seconds.

[0064] 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 less overshoot is still possible. Furthermore, a similar effect was obtained when the heating pattern for controlling the second control valve was changed to a stepped heating pattern in which the temperature is raised at a constant rate (heating rate of 0.14°C / sec) for 10 seconds, and then the temperature is maintained for 10 seconds, without changing the target temperature and heating time, and ramp soak control was used.

[0065] (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.

[0066] In Example 2, the deviation between the target temperature and the thermometer's detected value increases as the time approaches the start of heating. Therefore, if feedback control of the second control valve is performed solely based on the deviation between the target temperature and the thermometer's detected value, the water temperature may rise rapidly and overshoot may occur at the start of heating. However, in Example 2, the opening degree of the first control valve is controlled by the deviation between the pressure set value obtained from the pressure change pattern and the detected value of the front pressure gauge, so the rate of increase in water temperature was kept almost constant.

[0067] (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.

[0068] In Example 3, a temperature reduction pattern and a pressure reduction pattern were set.

[0069] (Comparative Example) The raw water was heated in the same manner as in the embodiment, except that the first control valve in the embodiment 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. From this, it can be seen that when simple feedback control is used for the supply pressure of the heat transfer medium, the opening of the second control valve becomes excessively large at the start of heating, causing a rapid increase in temperature, which results in a wavy heating curve and makes it difficult to heat at a constant rate. Note that this is due to the characteristics of the valve and the shortcomings of the feedback control, and it is difficult to resolve using methods other than those in this embodiment.

[0070] 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 (MD) G) 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), 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 for producing primary or secondary pure water by removing impurities from water to be treated, a temperature control system for adjusting the temperature of the water to be treated comprises: 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 using the detected value of the thermometer; and a pressure control unit for controlling the opening degree of the first control valve using the detected value of the pressure gauge. A temperature control system characterized in that the pressure control unit calculates the deviation between a set pressure value obtained from a preset pressure change pattern and the detected value of the pressure gauge at every minute detection time, and controls the opening degree of the first control valve based on the calculated deviation.

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 unit calculates the deviation between a set temperature value obtained from a preset temperature change pattern and the detected value of the thermometer at every minute detection time, and controls the opening degree of the second control valve based on the calculated deviation, the temperature control system according to claim 1.

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

5. The pure water apparatus is a pharmaceutical water production apparatus comprising one or more selected from a reverse osmosis membrane apparatus and an electrodeionizer, wherein the raw water of the pharmaceutical 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 by removing impurities from water to be treated to produce primary 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 detecting the temperature of the water to be treated after adjusting the temperature, and using the detected temperature values ​​at minute detection intervals to control the amount of the heat transfer medium supplied to maintain the temperature of the water to be treated within a predetermined range; and a second step of detecting the supply pressure of the heat transfer medium to be heated, and controlling the supply pressure of the heat transfer medium to be heated based on the deviation at minute detection intervals between the pressure obtained from a predetermined pressure change pattern set in advance and the detected value of the supply pressure of the heat transfer medium.

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

8. The method for producing pure water is a medical water production apparatus that performs one or more treatments selected from 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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