Hot ultrapure water production system and hot ultrapure water production method

Abstract

To provide a warm ultrapure water production system capable of controlling the production amount of warm ultrapure water in accordance with the use amount of the warm ultrapure water and reducing energy required for producing the warm ultrapure water.SOLUTION: This hot ultrapure water production system has a preheater 10 and a heater 11 for heating ultrapure water in the rear stage of a non-regenerative ion exchange resin tower 9 of a secondary pure water device 1, and a heat source 12 is connected to the heater 11 through a flow rate regulating valve 13. Further, the hot ultrapure water W1 can be supplied to the point of use UP through the UF membrane 14. A return pipe 20 branches off from the water supply pipe 2A at a stage subsequent to the UF membrane 14, and the return pipe 20 returns the water to the sub tank 2 via the preheater 10. The return pipe 20 is provided with a pressure regulating valve 16 and a flowmeter 18, and the amount of the primary pure water W supplied from the water pump 3 and the booster pump 8 can be adjusted based on the flow rate data of the flowmeter 18.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a hot ultrapure water production system that can reduce the energy required for hot ultrapure water production by controlling the amount of hot ultrapure water produced in accordance with the amount of hot ultrapure water used at the point of use, and to a method for producing hot ultrapure water using the same. [Background technology]

[0002] Ultrapure water used for semiconductor cleaning is produced by treating raw water (industrial water, city water, well water, etc.) in an ultrapure water production system that includes a pretreatment system, a primary pure water production unit, and a subsystem (secondary pure water production unit).

[0003] The pretreatment system, consisting of coagulation, pressurized flotation (sedimentation), and filtration (membrane filtration) devices, removes suspended solids and colloidal substances from the raw water. This process also allows for the removal of high-molecular-weight organic compounds and hydrophobic organic compounds.

[0004] The primary pure water system includes a heat exchanger, a reverse osmosis membrane treatment system (RO system), an ion exchange system (mixed bed type or 4-bed 5-column type, etc.), an ion exchange system, and a degasser. The primary pure water production system removes ions and organic components from the raw water. Note that the viscosity of water decreases and the permeability of the RO membrane improves as the temperature of the water increases. For this reason, a heat exchanger is installed before the reverse osmosis membrane treatment system to heat the water so that the temperature of the water supplied to the reverse osmosis membrane treatment system is above a predetermined temperature. The reverse osmosis membrane treatment system removes salts, as well as ionic components and TOC. The ion exchange system removes salts and inorganic carbon (IC), as well as TOC components that are adsorbed or ion-exchanged by ion exchange resin. The degasser removes inorganic carbon (IC) and dissolved oxygen.

[0005] The primary pure water produced by the primary pure water production unit is sent to a subsystem. This subsystem includes a sub-tank (pure water tank), a low-pressure ultraviolet oxidation unit (UV unit), an ion exchange unit, etc. In the low-pressure ultraviolet oxidation unit, 185nm ultraviolet light emitted from a low-pressure ultraviolet lamp decomposes TOC into organic acids and then into CO2. The organic matter and CO2 generated by the decomposition are removed by the subsequent ion exchange unit.

[0006] Ultrapure water produced by such an ultrapure water system may be heated to approximately 65-85°C using a heating device and supplied to the point of use as warm ultrapure water.

[0007] This hot ultrapure water production system has a configuration as shown in Figure 2, for example. In Figure 2, the hot ultrapure water production system includes a secondary pure water unit (subsystem) 51, which includes a sub-tank 52 for storing primary pure water W at approximately 25°C from the primary pure water unit, a water supply pipe 52A as a hot ultrapure water supply pipeline, a water supply pump 53, a heat exchanger 54, an ultraviolet oxidation unit 55, a hydrogen peroxide decomposition unit 56 filled with a platinum catalyst, a membrane degasser 57, a booster pump 58, and a non-regenerative ion exchange resin tower 59, where ultrapure water at approximately 20-30°C is produced. It also has a preheater 60 and a heater 61 for heating this ultrapure water, and a heat source 62 is connected to the heater 61 via a flow control valve 63 as a flow control mechanism. Furthermore, it is equipped with a UF membrane 64 for removing fine particles from the heated ultrapure water, and the hot ultrapure water W1 can be supplied to the use point UP via this UF membrane 64.

[0008] Furthermore, a temperature sensor 65 is provided at the outlet of the heater 61 as a means of measuring the temperature of the ultrapure water. This temperature sensor 65 can transmit information to a control means (not shown), which can control the flow rate of the heat source 62 by adjusting the opening of the flow control valve 63. In addition, a return pipe 70 branches off from the supply pipe 52A downstream of the UF membrane 64, and this return pipe 70 returns the water to the sub-tank 52 via the preheater 60. This return pipe 70 is equipped with a pressure regulating valve 66 and a pressure sensor 67 as a means of measuring pressure. This pressure sensor 67 can transmit information to the control means, which can adjust the opening of the pressure regulating valve 66 based on the pressure data.

[0009] In this secondary pure water system 51, primary pure water W at approximately 25°C is stored in a sub-tank 52 from the primary pure water system, then supplied from the water supply pipe 52A by a water supply pump 53, and sequentially processed in an ultraviolet oxidation device 55, a hydrogen peroxide decomposition device 56, a membrane degasser 57, and a non-regenerative ion exchange resin tower 59 to produce ultrapure water at approximately 20-30°C. The produced ultrapure water is heated to 30-50°C, for example, approximately 42°C, by a preheater 60, and then heated to 65-85°C, for example, approximately 75°C, by a heater 61, and the required amount of warm ultrapure water W1 is supplied from the water supply pipe 52A through the UF membrane 64 to the use point UP.

[0010] The temperature of the warm ultrapure water W1 is controlled by controlling the flow control valve 63 to maintain a predetermined temperature based on the temperature sensor 65 located downstream of the heater 61, thereby controlling the amount of heat transfer medium supplied from the heat source 62. In addition, any excess warm ultrapure water W1 that is not used at the use point UP is returned to the sub-tank 52 after its heat is recovered in the preheater 60 via the return pipe 70. At this time, the water supply pressure to the use point UP is kept constant by adjusting the opening of the pressure control valve 66 so that the pressure measured by the pressure sensor 67 in the water supply pipe 52A to the use point UP and the return pipe 70 remains constant. [Overview of the project] [Problems that the invention aims to solve]

[0011] However, the conventional hot ultrapure water production system described above produces a fixed amount of hot ultrapure water W1, and if the amount of hot ultrapure water used at the use point UP is less than expected, the amount of water supplied to the use point UP is adjusted by increasing the return amount. This presents a challenge in that there is room to reduce the energy required for heating and water supply power.

[0012] The present invention has been made in view of the above problems, and aims to provide a hot ultrapure water production system and a method for producing hot ultrapure water using the same, which can reduce the energy required for hot ultrapure water production by controlling the amount of hot ultrapure water produced in accordance with the amount of hot ultrapure water used at the point of use. [Means for solving the problem]

[0013] In view of the above objectives, the present invention firstly comprises an ultrapure water production unit equipped with a primary pure water production device and a secondary pure water production device; a hot ultrapure water supply pipeline for supplying ultrapure water from the ultrapure water production unit to a point of use; a first heating means provided in the ultrapure water supply pipeline, which supplies excess return water to the heat source fluid flow path as heat source water for use at the point of use; a return pipe for returning the return water that has passed through the heat source fluid flow path of the first heating means back to the ultrapure water production unit; and a second heating means for further heating the ultrapure water heated by the first heating means. A hot ultrapure water production system is provided, in which heated ultrapure water is supplied to a point of use, wherein the return piping is provided with a flow rate measuring means, a pressure measuring means and a pressure regulating valve downstream of the pressure measuring means, and the hot ultrapure water supply pipeline is provided with a temperature measuring means downstream of the second heating means, and the system has a control means that controls the pressure regulating valve based on the measured value of the pressure measuring means, controls the amount of ultrapure water supplied based on the measured value of the flow rate measuring means, and further controls the second heating means based on the measured value of the temperature measuring means (Invention 1).

[0014] According to this invention (Invention 1), the pressure regulating valve is controlled so that the measured value of the pressure measuring means upstream of the pressure regulating valve installed in the return piping becomes substantially constant, and the supply amount of ultrapure water is controlled so that the measured value of the flow rate measuring means becomes substantially constant. Therefore, when the amount of warm ultrapure water used at the point of use decreases, the supply amount of ultrapure water is reduced, thereby reducing the energy required for heating and water supply power, and enabling the warm ultrapure water production system to be operated and warm ultrapure water to be produced.

[0015] In the above invention (Invention 1), it is preferable that the secondary pure water production apparatus has a water supply pump, and the control means adjusts the supply amount of ultrapure water by controlling the output of the water supply pump (Invention 2). Furthermore, in the above invention (Invention 1), it is preferable that the secondary pure water production apparatus has a water supply pump and a booster pump downstream of the water supply pump, and the control means adjusts the supply amount of ultrapure water by controlling the water supply pump and / or the booster pump (Invention 3). Moreover, in the above invention (Invention 3), it is preferable that the water supply pump and the booster pump are equipped with inverters, the control means controls the frequency output from the inverter, and the lower limit of the fluctuation value of the amount of water used at the use point is 50% or more of the maximum value (Invention 4).

[0016] According to these inventions (Inventions 2-4), by adjusting the water flow rate of the water supply pump and / or booster pump installed in the secondary pure water production apparatus using inverter control or the like, ultrapure water can be supplied quickly and in a wide range of water volumes in response to fluctuations in the use of warm ultrapure water at the point of use.

[0017] Secondly, the present invention comprises an ultrapure water production unit equipped with a primary pure water production device and a secondary pure water production device; a hot ultrapure water supply pipeline that supplies ultrapure water from the ultrapure water production unit to a point of use; a first heating means provided in the ultrapure water supply pipeline that supplies excess return water to the heat source fluid flow path as heat source water relative to the amount used at the point of use; a return pipe that returns the return water that has passed through the heat source fluid flow path of the first heating means back to the ultrapure water production unit; and a second heating means that further heats the ultrapure water heated by the first heating means, wherein the ultrapure water heated by the second heating means is supplied to the point of use. A method for producing hot ultrapure water is provided using a hot ultrapure water production system, which includes a flow rate measuring means, a pressure measuring means, and a pressure regulating valve downstream of the pressure measuring means in the return piping, and a temperature measuring means downstream of the second heating means in the hot ultrapure water supply pipeline, wherein the pressure regulating valve is controlled so that the measured value of the pressure measuring means becomes substantially constant, the amount of ultrapure water supplied is controlled so that the measured value of the flow rate measuring means becomes substantially constant, and the second heating means is controlled so that the measured value of the temperature measuring means becomes constant at a temperature higher than the set temperature of the hot ultrapure water (Invention 5).

[0018] According to this invention (Invention 5), the pressure regulating valve installed in the return piping can be controlled so that the measured value of the pressure measuring means remains substantially constant, and the supply amount of ultrapure water can be controlled so that the measured value of the flow rate measuring means remains substantially constant. Therefore, when the amount of warm ultrapure water used at the point of use decreases, the supply amount of ultrapure water can be reduced, thereby reducing the energy required for heating and water supply power, and enabling the warm ultrapure water production system to be operated and warm ultrapure water to be produced.

[0019] In the above invention (Invention 5), it is preferable that the secondary pure water production device has a water supply pump, and the control means adjusts the supply amount of ultrapure water by controlling the output of the water supply pump (Invention 6). Further, in the above invention (Invention 5), it is preferable that the secondary pure water production device has a water supply pump and a booster pump at the subsequent stage of the water supply pump, and the control means adjusts the supply amount of ultrapure water by controlling the water supply pump and / or the booster pump (Invention 7). Furthermore, in the above invention (Invention 7), it is preferable that the water supply pump and the booster pump are provided with inverters, the control means controls the frequency output from the inverters, and the lower limit value of the fluctuation value of the water consumption amount at the use point is 50% or more with respect to the maximum value (Invention 8).

[0020] According to such inventions (Inventions 5 to 8), by adjusting the water supply amount of the water supply pump and / or the booster pump provided in the secondary pure water production device by inverter control or the like, it is possible to quickly supply ultrapure water in a wide range of water amounts according to the fluctuation of the use of warm ultrapure water at the use point.

Effects of the Invention

[0021] According to the warm ultrapure water production system of the present invention, the pressure regulating valve is controlled so that the measured value of the pressure measuring means becomes substantially constant at the previous stage of the pressure regulating valve provided in the return pipe, and the supply amount of ultrapure water is controlled so that the measured value of the flow measuring means becomes substantially constant. Therefore, when the amount of warm ultrapure water used at the use point decreases, the supply amount of ultrapure water will be reduced, so that the energy required for heating and water supply power can be reduced, and the warm ultrapure water production system can be operated to produce warm ultrapure water.

Brief Description of the Drawings

[0022] [Figure 1] It is a flowchart showing a warm ultrapure water production system according to an embodiment of the present invention. [Figure 2] It is a flowchart showing a conventional warm ultrapure water production system.

Modes for Carrying Out the Invention

[0023] The following description of the thermal ultrapure water production system and the method for producing thermal ultrapure water using the present invention will be explained with reference to the attached drawings.

[0024] (Warm ultrapure water production system) The hot ultrapure water production system of this embodiment includes an ultrapure water production unit equipped with a pretreatment device, a primary pure water production device, and a secondary pure water production device; a hot ultrapure water supply pipeline that supplies ultrapure water from the ultrapure water production unit to a point of use; and a heating means for heating the ultrapure water.

[0025] In this embodiment, the primary pure water production apparatus is not particularly limited, and any known primary pure water production apparatus can be applied with normal control, so this will be omitted.

[0026] The warm ultrapure water production system of this embodiment has a configuration as shown in Figure 1, for example. In Figure 1, the warm ultrapure water production system includes, as a secondary pure water device (subsystem) 1, a sub-tank 2 for storing primary pure water W supplied from the primary pure water device, a water supply pipe 2A as a warm ultrapure water supply pipeline, a water supply pump 3 whose output can be controlled by an inverter, a heat exchanger 4, an ultraviolet oxidation device 5, a hydrogen peroxide decomposition device 6 filled with a platinum group metal catalyst, a membrane degasser 7, a booster pump 8 whose output can be controlled by an inverter, and a non-regenerative ion exchange resin tower 9. Furthermore, it has a preheater 10 as a first heating means and a heater 11 as a second heating means for heating the ultrapure water, and a heat source 12 is connected to the heater 11 via a flow control valve 13 as a flow control mechanism so that the flow rate can be adjusted. In addition, it is equipped with a UF membrane 14 for removing fine particles from the heated ultrapure water, and the warm ultrapure water W1 can be supplied to the use point UP via this UF membrane 14.

[0027] Furthermore, a temperature sensor 15 is provided at the outlet of the heater 11 as a means of measuring the temperature of the warm ultrapure water W1. This temperature sensor 15 can transmit information to a control means (not shown), which can adjust the opening degree of the flow control valve 13 of the heat source 12. In addition, a return pipe 20 branches off from the supply pipe 2A downstream of the UF membrane 14. This return pipe 20 returns water to the sub-tank 2 via the preheater 10, which serves as the heat source for the preheater 10. This return pipe 20 is equipped with a pressure regulating valve 16 as a pressure regulating mechanism, a pressure sensor 17 as a pressure measuring means, and a flow meter 18 as a flow rate measuring means. This pressure sensor 17 can transmit information to the control means. This control means can adjust the opening degree of the pressure regulating valve 16 based on the pressure data measured by the pressure sensor 17. Furthermore, the flow meter 18 is capable of transmitting information to a control means, which can adjust the amount of primary pure water W supplied from the water supply pump 3 and / or the booster pump 8 based on the flow rate data measured by the flow meter 18. In this embodiment, the concentrated water (brine water) from the UF membrane 14 is also joined to the return pipe 20.

[0028] (Method for producing warm ultrapure water) Next, the method for producing hot ultrapure water according to this embodiment using such a hot ultrapure water production system will be described below.

[0029] In the pretreatment system, raw water is pretreated by filtration, coagulation and sedimentation, and microfiltration membranes, primarily to remove suspended solids.

[0030] A primary pure water production system is equipped with a reverse osmosis (RO) membrane separator, a degasser, a regenerative ion exchange system (such as a mixed-bed or 4-bed 5-column system), an electrodeionizer, an ultraviolet (UV) irradiation oxidation system, and other oxidation devices to remove most of the electrolytes, particulate matter, and live bacteria from the pre-treated water. For example, a primary pure water production system consists of a heat exchanger, an RO membrane separator, a mixed-bed ion exchange system, and a degasser.

[0031] In this embodiment, the primary pure water W produced by the primary pure water production apparatus is processed in the secondary pure water apparatus 1 as follows. That is, the primary pure water W at approximately 25°C is stored in the sub-tank 2, supplied from the water supply pipe 2A by the water supply pump 3, and processed sequentially in the ultraviolet oxidation apparatus 5, the hydrogen peroxide decomposition apparatus 6, and the membrane degassing apparatus 7. Then, the water supply pressure is increased by the booster pump 8 and processed in the non-regenerative ion exchange resin column 9 to produce ultrapure water at approximately 20-30°C. The produced ultrapure water is heated to 30-50°C, for example, about 42°C, by the preheater 10, and then heated to 65-85°C, for example, about 70°C, by the heater 11, and supplied to the use point UP as warm ultrapure water W1 via the UF membrane 14 from the water supply pipe 2A. At this time, the flow rate is adjusted so that the required amount is supplied to the use point UP by a flow rate control means (not shown).

[0032] The excess warm ultrapure water W1 then flows through the return pipe 20 and is introduced into the preheater 10 as a heat source fluid. There, it exchanges heat with the ultrapure water treated in the non-regenerative ion exchange resin tower 9, cools down to about 40°C, and is then sent to the sub-tank 2.

[0033] A pressure regulating valve 16 is installed between the return pipe 20, immediately after it branches off from the supply pipe 2A, and the preheater 10. This pressure regulating valve 16 maintains a nearly constant water supply pressure to the use point UP by adjusting its opening so that the pressure measured by the pressure sensor 17 remains nearly constant. In this specification, "nearly constant" means within ±5%, and especially within ±1%, of the set value.

[0034] Furthermore, steam or hot water (approximately 5-10°C above the set temperature of the ultrapure water W1) flows through the heat source fluid passage of the heater 11 as a heat source 12 via a flow control valve 13. The flow control valve 13 is controlled so that the temperature of the ultrapure water W1 detected by a temperature sensor 15 installed in the water supply pipe 2A is above the set temperature (e.g., 70°C) and is approximately at the set temperature at the use point UP.

[0035] In this embodiment, a flow meter 18 is provided upstream of the pressure regulating valve 16 in the return piping 20. By controlling the water supply amount of the water supply pump 3 and / or the booster pump 8 with an inverter so that the flow rate measured by this flow meter 18 remains approximately constant, the amount of hot ultrapure water W1 produced is increased or decreased in response to increases or decreases in the amount of hot ultrapure water W1 used at the use point UP. As a result, the amount of hot ultrapure water W1 produced can be increased or decreased in response to increases or decreases in the amount of hot ultrapure water W1 used at the use point UP, thus reducing the energy required to produce hot ultrapure water W1 compared to producing a constant amount of hot ultrapure water W1. Preferably, the lower limit of the fluctuation value of the water usage at the use point is 50% or more of the maximum value.

[0036] Although the present invention has been described above based on the above embodiments, the present invention is not limited to the above embodiments and can be implemented in various modified forms. For example, the inverter control of the flow rate of the water supply pump 3 and the booster pump 8 may be performed by either one or both. Also, the heat source 12 of the heater 11 may be heated steam, hot water, or a combination of both. Furthermore, the secondary pure water system 1 is not limited to the configuration of the above embodiments and can be applied to systems composed of various elements, and depending on the configuration, the booster pump 8 may not be provided. [Examples]

[0037] The present invention will be described in more detail based on the following specific examples, but the present invention is not limited to the following examples.

[0038] [Comparative Example 1] Using the hot ultrapure water production system shown in Figure 1, 5m 3Primary pure water W is fed from the sub-tank 2 capable of holding a certain amount of liquid by a water supply pump 3, cooled to 23 - 25°C in a heat exchanger 4, and then treated by an ultraviolet oxidation device 5, a hydrogen peroxide decomposition catalyst tower 6, and a membrane degassing device 7. Subsequently, the water supply pressure is increased by a booster pump 8 equipped with an inverter at the rear stage of the membrane degassing device 7, and the water is treated by a non-regenerative ion exchange resin tower 9 to obtain ultrapure water. This ultrapure water is treated by a waste heat exchanger 10, a heater 11, and a UF membrane 14 to produce warm ultrapure water W1, which is then fed to the use point UP. Warm water at 85°C is used as the heat source 12 of the heater 11, and the supply amount of the 85°C warm water is controlled so that the water temperature at the temperature sensor 15 becomes 70°C.

[0039] In such a warm ultrapure water production system, the water supply amount by the water supply pump 3 is about 20 m 3 / h, and the water quality at the outlet of the UF membrane 14 in this system was a specific resistance value of 18.2 MΩ or more and a dissolved oxygen concentration of 1 μg / L or less. The pressure regulating valve 16 was controlled so that the pressure in the return pipe 20 became 0.2 MPa. The UF membrane 14 was adjusted with a valve so that the brine amount became about 2 m 3 / h. Also, the maximum water usage amount at the use point UP was 16 m 3 / h, and the water amount in the return pipe 20 at this time was about 2 m 3 / h.

[0040] In the method for producing this warm ultrapure water W1, the frequency output from the inverter that controls the rotational speed of the booster pump 8 was constant at 48 Hz, and the supply amount of warm water at about 85°C supplied to the heater 11 as a heat medium was about 80 m 3 / h.

[0041] And when the water usage amount at the use point UP was reduced from 16 m 3 / h to about 8 m 3 / h, the heat recovery amount in the waste heat exchanger 10 increased, but the usage amount of warm water at 85°C as the heat source was 70 m 3 / h.

[0042] 〔Example 1〕 In the production method of Comparative Example 1, when the use point UP was at the maximum water usage amount of 16 m3 When consuming / h, the flow rate in the return pipe 20 is measured with the flow meter 18, and 2m 3 The booster pump 8 was inverter-controlled to maintain a constant frequency of / h. At maximum water usage, the frequency of the booster pump 8 was 48Hz, and the hot water supply rate was approximately 80m³. 3 There wasn't a significant difference, around / h. Next, we measured the water usage at Use Point UP at 8m³. 3 The flow rate was reduced to / h, and similarly the flow rate in the return pipe 20 was measured with the flow meter 18, 2m 3 When the boost pump 8 was controlled by an inverter to maintain a constant frequency of / h, the frequency of the boost pump 8 was 24-28Hz, and the amount of 85°C hot water used as the heat source was approximately 50m³. 3 This resulted in a reduction in energy required for supplying and heating the warm ultrapure water W1, significantly decreasing the energy needed for heating.

[0043] This method for producing warm ultrapure water increases the water usage of UsePointUP by approximately 8m³ per hour. 3 / h and approximately 16m 3 After repeatedly operating the / h operation, the water quality at the outlet of the UF membrane 14 showed a resistivity of 18.2 MΩ or higher and a dissolved oxygen concentration of 1 μg / L or lower. No impact on water quality was observed, and high-purity water quality could be maintained. [Explanation of symbols]

[0044] 1. Secondary pure water system (subsystem) 2 Sub-tanks 2A Water supply pipe (warm ultrapure water supply pipe) 3. Water supply pump 8. Booster pump 10 Preheater (first heating means) 11 Heater (second heating means) 12 Heat source 13. Flow control valve (flow control means) 14 UF membrane 15. Temperature sensor (temperature measurement means) 16. Pressure regulating valve (pressure regulating means) 17. Pressure sensor (pressure measuring means) 18. Flow meter (means for measuring flow rate) 20 Return piping UP Youth Point W Primary pure water W1 Warm ultrapure water

Claims

1. An ultrapure water production unit equipped with a primary pure water production system and a secondary pure water production system, A hot ultrapure water supply pipeline that supplies ultrapure water from the ultrapure water production unit to the point of use, A first heating means is provided in the aforementioned hot ultrapure water supply pipeline for heating the ultrapure water, A second heating means for further heating the ultrapure water heated by the first heating means, A UF membrane that removes fine particles contained in the ultrapure water heated by the second heating means, A hot ultrapure water production system comprising the UF membrane, wherein the ultrapure water from which the fine particles have been removed is supplied to the use point, The system further includes a return pipe that branches off from the hot ultrapure water supply pipeline downstream of the UF membrane, The ultrapure water exceeding the amount used at the aforementioned use point flows through the return piping, is introduced to the first heating means as a heat source fluid, and is then sent to a sub-tank upstream of the first heating means. The concentrated water from the UF membrane is connected to the return piping. A flow rate measuring means, a pressure measuring means, and a pressure regulating valve are provided in the return piping upstream of the first heating means, and a temperature measuring means is provided downstream of the second heating means in the hot ultrapure water supply pipeline. A thermal ultrapure water production system having a control means that controls the pressure regulating valve based on the measured value of the pressure measuring means, controls the amount of ultrapure water supplied to the first heating means based on the measured value of the flow rate measuring means, and further controls the second heating means based on the measured value of the temperature measuring means.

2. The thermal ultrapure water production system according to claim 1, wherein the secondary pure water production apparatus has a water supply pump, and the control means adjusts the amount of ultrapure water supplied by controlling the output of the water supply pump.

3. The thermal ultrapure water production system according to claim 2, wherein the secondary pure water production apparatus has a booster pump downstream of the water supply pump, and the control means adjusts the amount of ultrapure water supplied by controlling the water supply pump and / or the booster pump.

4. The hot ultrapure water production system according to claim 3, wherein the water supply pump and the boost pump are equipped with inverters, the control means controls the frequency output from the inverter, and the lower limit of the fluctuation value of the amount of water used at the use point is 50% or more of the maximum value.

5. A method for producing hot ultrapure water using a hot ultrapure water production system comprising: an ultrapure water production unit equipped with a primary pure water production unit and a secondary pure water production unit; a hot ultrapure water supply pipeline for supplying ultrapure water from the ultrapure water production unit to a point of use; a first heating means provided in the hot ultrapure water supply pipeline for heating the ultrapure water; a second heating means for further heating the ultrapure water heated by the first heating means; and a UF membrane for removing fine particles contained in the ultrapure water heated by the second heating means, wherein the ultrapure water from which the fine particles have been removed by the UF membrane is supplied to the point of use, The above-mentioned ultrapure water production system further includes a return pipe that branches off from the ultrapure water supply pipeline downstream of the UF membrane, and any excess ultrapure water beyond the amount used at the point of use flows through the return pipe, is introduced to the first heating means as a heat source fluid, is sent to a sub-tank upstream of the first heating means, and the concentrated water from the UF membrane merges with the return pipe, and the return pipe upstream of the first heating means is provided with a flow rate measuring means, a pressure measuring means and a pressure regulating valve downstream of the pressure measuring means, and the ultrapure water supply pipeline is provided with a temperature measuring means downstream of the second heating means. A method for producing warm ultrapure water, comprising: controlling the pressure regulating valve using a control means of the warm ultrapure water production system so that the measured value of the pressure measuring means becomes substantially constant; controlling the amount of ultrapure water supplied to the first heating means so that the measured value of the flow rate measuring means becomes substantially constant; and further controlling the second heating means so that the measured value of the temperature measuring means becomes constant at a temperature higher than the set temperature of the warm ultrapure water.

6. The method for producing warm ultrapure water according to claim 5, wherein the secondary pure water production apparatus has a water supply pump, and the control means adjusts the amount of ultrapure water supplied by controlling the output of the water supply pump.

7. The method for producing warm ultrapure water according to claim 6, wherein the secondary pure water production apparatus has a water supply pump and a booster pump downstream of the water supply pump, and the control means adjusts the amount of ultrapure water supplied by controlling the water supply pump and / or the booster pump.

8. A method for producing hot ultrapure water according to claim 7, wherein the water supply pump and the boost pump are equipped with inverters, the control means controls the frequency output from the inverter, and the lower limit of the fluctuation value of the amount of water used at the use point is 50% or more of the maximum value.

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