TW202317484A - Pure water production device and method for operating same - Google Patents

Abstract

An object of the invention is to provide a lower cost method to suppress increases in temperature caused by the circulation of pure water. A pure water production device 1 has a tank 2 which stores pure water, a circulation line L1 which circulates the pure water inside the tank 2, a pump 3 which is provided in the circulation line L1 and flows the pure water in the tank 2 into the circulation line L1, a water feed line L2 which branches from the circulation line L1 at a position downstream from the pump 3 and connects to a usage point 7, and a control unit 10 which switches the revolutions of the pump 3 based on the results of directly or indirectly detecting the presence or absence of the flow of pure water into the water feed line L2, or changes in the flow rate of the pure water flowing through the water feed line L2.

Description

Pure water manufacturing device and operating method thereof

The present invention relates to a pure water manufacturing device and its operating method.

There is known a pure water production device that produces pure water (refined water) for pharmaceutical use or biochemical analysis and supplies it to the point of use, circulates the pure water along a circulation line, and supplies a part of the pure water as needed to the point of use (for example, refer to Patent Document 1). This kind of device, in the case of stopping the supply of pure water to the point of use for a long time, such as nights or holidays when the point of use does not need pure water, in order to suppress the generation of live bacteria due to retention, the pure water circulation operation is still performed. [Prior Art Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2006-095479

[Problem to be solved by the invention]

When the pure water circulation continues for a long time, sometimes the temperature of the pure water will rise due to the heat generated by the pump or ultraviolet sterilizing device installed on the circulation pipeline, exceeding the appropriate use temperature at the point of use (set temperature ). For example, relatively small pure water production equipment that is often used in research institutions often uses pumps with a relatively large capacity (maximum discharge flow rate) relative to the maximum water storage capacity of the storage tank in order to respond to various purposes. This temperature rise tends to occur significantly. As a countermeasure against such a rise in temperature, as described in Patent Document 1, a cooling mechanism such as a heat exchanger can be installed in the circulation line, but if it is a relatively small pure water production device, it is not appropriate to consider the size of the device or the cost. actual. In addition, even relatively large-scale pure water production equipment installed in various factories may not provide a cooling mechanism in the circulation line from an economical point of view. Therefore, in most pure water manufacturing devices, in order to reduce the temperature of pure water below the set temperature, a certain amount of pure water in the circulation will be sprayed out and replenished again. However, such useless waste of pure water is not preferable because it results in an important cause of cost increase.

Therefore, the object of the present invention is to provide a pure water manufacturing device and its operation method, which can suppress the temperature rise of the pure water due to circulation at a lower cost. [Means to solve the problem]

In order to achieve the above object, the pure water manufacturing device of the present invention has: a storage tank for storing pure water; a circulation pipeline for circulating the pure water in the storage tank; a pump installed in the circulation pipeline for making the pure water in the storage tank The water flows through the circulation pipeline; the water pipeline, on the downstream side of the pump, is branched from the circulation pipeline and connected to the point of use; and the control mechanism is based on whether pure water flows through the water pipeline, or flows through the The result of direct or indirect detection of the pure water flow change in the water delivery pipeline is to switch the pump speed.

Also, the operation method of the pure water production device of the present invention includes the following steps: using a pump installed in the circulation pipeline to circulate the pure water stored in the storage tank along the circulation pipeline; The water delivery pipeline branched from the circulation pipeline on the downstream side transports the pure water circulating in the circulation pipeline to the point of use; it depends on whether there is pure water flowing in the water delivery pipeline or the flow rate of pure water flowing through the water delivery pipeline As a result of direct or indirect detection of changes, the pump speed is switched.

According to this pure water manufacturing device and its operation method, by switching the rotation speed of the pump, the temperature rise of the pure water due to circulation can be suppressed, so that the pure water will not be wasted uselessly. In addition, compared with the situation where the pump is operated at the same speed for a long time, the power consumption of the pump can also be suppressed and the operating cost can be reduced. [Effect of Invention]

As mentioned above, according to the present invention, the temperature rise of pure water due to circulation can be suppressed at a lower cost.

Embodiments of the present invention will be described below with reference to the drawings. In this specification, as the pure water production device of the present invention, a cabinet-type pure water production device is exemplified, which is suitably used together with analytical instruments such as automatic blood analyzers in research institutions or medical institutions, but the present invention is not limited thereto. As the pure water production device of the present invention, as long as there is no mechanism (such as a heat exchanger, etc.) that dynamically adjusts the temperature of the pure water in circulation, it can also be a large-scale pure water production device installed in various factories, for example. .

(first embodiment) Fig. 1 is a schematic diagram showing the configuration of a pure water production apparatus according to an embodiment of the present invention. Moreover, the structure of the pure water manufacturing apparatus shown in figure is just an example, and does not limit the structure of this invention.

The pure water production device 1 has a storage tank 2 , a pump 3 , an ultraviolet oxidizing device 4 , an ion exchange device 5 , and a separation membrane device 6 . These components are stored in the cabinet to form a secondary pure water system (sub-system) that "processes the primary pure water produced by the primary pure water system (not shown) in order to produce pure water", and transfers the pure water Supply to use point 7.

The pump 3 , the ultraviolet ray oxidation device 4 , the ion exchange device 5 , and the separation membrane device 6 are arranged on the circulation pipeline L1 , and both ends of the circulation pipeline L1 are connected to the storage tank 2 . At the use point 7, a water delivery pipeline L2 branched from the circulation pipeline L1 is connected via the solenoid valve V1. The solenoid valve V1 is opened and closed according to the command signal (opening and closing command signal) sent from the point of use 7 . Moreover, the storage tank 2 is connected with a primary pure water supply line L3, for example, supplied from a primary pure water system (not shown) according to the water level in the storage tank 2 detected by a water level sensor (not shown). Primary pure water is in storage tank 2. Specifically, when the water level in the storage tank 2 is below the predetermined water supply start level, the primary pure water is supplied to the storage tank 2 through the primary pure water supply line L3, and when the water level in the storage tank 2 reaches the predetermined upper limit water level, The supply of primary pure water to the storage tank 2 was stopped.

When the primary pure water (water to be treated) stored in the storage tank 2 is transported by the pump 3 and supplied to the ultraviolet oxidation device 4, it is irradiated by ultraviolet rays with a wavelength of 185nm, and the total organic carbon (TOC) in the water to be treated is decomposed . Then, the water to be treated is subjected to ion exchange treatment in the ion exchange device 5 to remove metals and the like, and in the separation membrane device 6 to remove fine particles and the like. The pure water obtained in this way flows back to the storage tank 2 through the circulation pipeline L1, but when the solenoid valve V1 is opened due to receiving a water collection request from the point of use 7, part or all of the pure water is transferred to the storage tank 2 through the water delivery pipeline L2. Supply to use point 7. In addition, on the downstream side of the branch point B between the circulation pipeline L1 and the water delivery pipeline L2, a back pressure valve V2 is provided as a back pressure generating mechanism, which is used to make pure water flow from the circulation pipeline L1 when the solenoid valve V1 is opened. It is sure to flow through the water pipeline L2.

As the storage tank 2, the pump 3, the ultraviolet oxidizing device 4, the ion exchange device 5, and the separation membrane device 6, those generally used in the sub-system of the pure water production device can be used. For example, as the ion exchange device 5, a non-regenerative mixed bed ion exchange device (cartridge type high-purifier) in which cation exchange resins and anion exchange resins are filled in a mixed bed form can be used. In addition, the separation membrane device 6 may include either a microfiltration membrane (MF membrane) or an ultrafiltration membrane (UF membrane). In addition, instead of the ultraviolet oxidizing device 4, an ultraviolet sterilizing device for sterilizing water to be treated by irradiating ultraviolet rays with a wavelength of 254 nm may be installed, or both may be installed.

Even if the pure water production device 1 stops the water collection operation (pure water is supplied to the point of use 7) for a long time, for example, at night or on holidays when the point of use 7 does not need pure water, in order to suppress the generation of live bacteria due to stagnation, it is still A circulation operation in which the produced pure water is returned to the storage tank 2 is performed. If the circulating operation of this pure water is carried out for a long time, sometimes the temperature of the pure water will rise due to the heat generated by the pump 3 or the ultraviolet oxidizing device 4, and the temperature of the pure water will be above the proper use temperature (set temperature) of the use point 7. In particular, if it is a cabinet-type pure water manufacturing device like this embodiment, in order to cope with various uses, it is often used to have a relatively large capacity (maximum discharge flow rate) relative to the maximum storage capacity of the storage tank. Considering the size and cost of the pump, there is no cooling mechanism such as a heat exchanger. Therefore, in the case where such a temperature rise is likely to occur significantly, for example, when the manufactured pure water is used in an analysis instrument such as an automatic blood analyzer, the temperature of the pure water will exceed 35°C.

Therefore, in this embodiment, in order to suppress the temperature rise of the pure water due to the circulation, the pump 3 operates at a lower rotational speed during the circulation operation than that during the water collection operation. That is, during circulation operation, the pump 3 operates at a first rotational speed, and during water extraction operation, the pump 3 operates at a second rotational speed higher than the first rotational speed. Therefore, the pure water production apparatus 1 has a control unit (control mechanism) 10 including an inverter (not shown) that controls the rotation speed of the pump 3 . The control unit 10 switches the rotation speed of the pump 3 according to whether pure water flows into the water delivery pipeline L2.

When the control unit 10 obtains the opening instruction signal sent to the solenoid valve V1 from the point of use 7, it indirectly detects that the solenoid valve V1 is opened, and pure water begins to flow in the water delivery pipeline L2 (that is, the water harvesting operation starts), When the closing instruction signal sent to the solenoid valve V1 is obtained from the point of use 7, it is indirectly detected that the solenoid valve V1 is closed, and pure water stops flowing in the water delivery pipeline L2 (that is, the water harvesting operation stops). In addition, the control unit 10 switches the rotation speed of the pump 3 from the first rotation speed to the second rotation speed when detecting that the water extraction operation starts, and switches the rotation speed of the pump 3 from the first rotation speed to the second rotation speed when detecting that the water extraction operation is stopped. The second speed is switched to the first speed. Also, the rotational speed of the pump 3 can be adjusted by controlling the drive output (motor output) of the pump 3 .

Here, the first rotation speed during circulation operation is appropriately set according to the actual device configuration, and is not particularly limited. However, the range in which the temperature of the pure water in the circulation does not rise is verified experimentally in advance to set the first rotation speed. The first rotational speed is better. The results of the actual verification are described later, but in order to minimize the temperature rise of the pure water due to circulation, the drive output of the pump 3 corresponding to the first rotation speed is set at 1L per minimum storage water volume converted into the storage tank 2 It is better if it is less than 5W, and it is better if it is less than 2W. The so-called minimum water storage volume here is the storage water volume when the water level in the storage tank 2 is the lowest, that is, the storage water volume when it is at the predetermined water supply start water level. Also, since the overall volume of the piping constituting the circulation line L1 is not considered to be negligibly smaller than the volume of the storage tank 2, this should be considered when setting the drive output of the pump 3 corresponding to the first rotational speed. The overall volume of the piping is also acceptable. That is, the minimum storage water volume of the storage tank 2 may be set by adding the volume equivalent to the minimum storage water volume of the storage tank 2 to the overall volume of the piping. On the other hand, the second rotational speed during water harvesting operation is appropriately set according to the flow rate of pure water required at the point of use 7, and is not particularly limited.

In this way, according to this embodiment, the rotation speed of the pump 3 is switched by supplying pure water to the point of use 7 through the water delivery pipeline L2 according to the presence or absence of pure water, so that the pump 3 can be operated at a relatively low rotation speed during circulation. action. Thereby, it is possible to suppress the temperature rise of the pure water during the circulation operation without wasting the pure water uselessly. In addition, compared to the case where the pump 3 is operated at the same rotational speed during the circulation operation and the water extraction operation, that is, the pure water is circulated at the same flow rate, the power consumption of the pump 3 and the ion exchange device 5 can be reduced. The loss of the ion exchange resin inside is suppressed, and as a result, the running cost can also be reduced. Also, assuming that it is a cabinet-type pure water manufacturing device used in a research institution or a medical institution, since pure water is often used for a short time and at a high frequency, if it is not necessary to perform a spraying step due to an increase in the temperature of the pure water, there will be There are also benefits in terms of having pure water available whenever you need it.

As mentioned above, the configuration of the pure water production device 1 shown in the figure is still an example, and it goes without saying that it can be appropriately changed according to the purpose, purpose, and required performance of the device. In particular, as long as the following components are provided: the storage tank 2 stores pure water (primary pure water); the circulation line L1 circulates the pure water in the storage tank 2; the pump 3 circulates the pure water in the storage tank 2 In the circulation pipeline L1; and the water pipeline L2, on the downstream side of the pump 3, branched from the circulation pipeline L1 and connected to the point of use 7; the ultraviolet oxidation device 4, the ion exchange device 5 and the separation membrane device can be omitted One or more of the six, or all three may be omitted. Regarding the back pressure valve V2, in order to adjust the flow rate of the pure water flowing through the water delivery pipeline L2 during the water harvesting operation, two or more back pressure valves may be provided, or may be omitted depending on the situation.

Here, the test results obtained by verifying how much the temperature of the pure water circulating in the circulation line rises due to the heat generated by the pump will be described.

(test 1-1) Using a test device that simulates the pure water manufacturing device shown in Figure 1, the pure water circulation is continuously performed, and the temperature (water temperature) of the pure water changes with time. Then, determine the period during which the water temperature rises the most after the operation period, and calculate the water temperature rise rate (water temperature rise per unit time) from this period (time) and the water temperature rise amount at this time. In addition, this testing device has the same configuration as the pure water production device shown in Fig. 1, except that the ion exchange device and the separation membrane device are not provided (and the water delivery pipeline is not provided). The storage tank uses the one with a maximum water storage capacity of 60L, and the pump uses a magnetic drive gear pump (model: MDG-M4S6A100) manufactured by IWAKI Co., Ltd. For pure water circulation, the motor output of the pump is set at 200W, and the storage tank is full of water, that is, the storage tank is filled with 60L of pure water.

(Test 1-2) Measurement was performed under the same conditions as Test 1-1 except that the circulation operation was performed in a state where the storage tank was filled with 40 L of pure water.

(Test 1-3) If the storage tank uses a maximum water storage capacity of 20L, the storage tank is full of water, that is, the storage tank is filled with 20L of pure water, and the cycle operation is performed. Other than that, measurement was performed under the same conditions as in Test 1-1.

(Test 2-1) Measurement was performed under the same conditions as Test 1-1 except for the following points. The pump uses a turbo pump made by Nikuni Co., Ltd. (Model: 15DNL03ZM-V), and the inverter for driving the motor of the pump uses an inverter made by Mitsubishi Electric Co., Ltd. (Model: FR-D710W-0.75K) . For pure water circulation, the motor output of the pump is set at 110W, and the storage tank is full of water, that is, the storage tank is filled with 60L of pure water.

(test 2-2) The measurement was carried out under the same conditions as Test 2-1, except that the motor output was set at 165W for cycle operation.

(Test 2-3) The measurement was carried out under the same conditions as Test 2-1, except that the motor output was set at 235W for cycle operation.

(test 2-4) Measurement was performed under the same conditions as Test 2-1, except that the storage tank was filled with 40 L of pure water and circulated.

(Test 2-5) Measurement was performed under the same conditions as Test 2-2 except that the circulation operation was performed in a state where the storage tank was filled with 40 L of pure water.

Table 1 shows the calculation results of the water temperature rise rate in each test. In addition, in Table 1, for convenience of reference, the stored water volume of the storage tank, the motor output of the pump, and the motor output of the pump per 1 L of stored water volume of the storage tank are also shown.

[Table 1] Test 1-1 Test 1-2 Test 1-3 Test 2-1 Test 2-2 Test 2-3 Test 2-4 Test 2-5 Water temperature rise rate [℃/h] 1.2 1.3 5.5 0.2 1.4 1.3 1.6 1.4 Storage tank water volume [L] 60 40 20 60 40 Pump motor output [W] 200 110 165 235 110 165 Motor output per 1L of stored water [W] 3.3 5.0 10.0 1.8 2.8 3.9 2.8 4.1

Except for Test 1-3, in any test, the rate of rise in water temperature was suppressed below 1.6°C/h, and among them, Test 2-1, in which the motor output of the pump was the smallest relative to the water stored in the storage tank, could be obtained Very good results. It can be seen from this that, from the viewpoint of suppressing the temperature rise of pure water due to circulation, it is better for the motor output of the pump to be 5W or less per 1L of water stored in the storage tank, and more preferably 2W or less.

(Second Embodiment) Fig. 2 is a schematic diagram showing the configuration of a pure water production apparatus according to a second embodiment of the present invention. Hereinafter, the same components as those of the first embodiment will be assigned the same symbols in the drawings, and their descriptions will be omitted, and only the components different from those of the first embodiment will be described.

As mentioned above, when the solenoid valve V1 is opened due to receiving a water collection request from the point of use 7, part or all of the pure water flowing through the circulation line L1 is supplied to the point of use 7 through the water delivery line L2. At this time, on the downstream side of the branch point B in the circulation pipeline L1, the pressure decreases due to the decrease in the flow rate of pure water. By detecting the decrease in pressure, it can also be indirectly detected that the pure water begins to flow through the water delivery pipe. Road L2. In this embodiment, in order to detect such a drop in pressure, a pressure switch 11 is provided on the downstream side of the branch point B in the circulation line L1 and on the upstream side of the back pressure valve V2. The pressure switch 11 outputs a detection signal when the pressure of the pure water flowing downstream of the branch point B in the circulation line L1 is below a set pressure (predetermined value). Then, when the control unit 10 receives the detection signal, it considers that the water harvesting operation starts and the pure water starts to flow in the water delivery pipeline L2, and then switches the rotation speed of the pump 3 from the first rotation speed to the second rotation speed. Thereby, in this embodiment, it is also possible to suppress the temperature rise of the pure water during the circulation operation without wasting the pure water uselessly, and also to reduce the operating cost.

The detection mechanism for indirectly detecting that the pure water begins to flow through the water delivery pipeline L2 is not limited to the pressure switch 11, and may be a pressure sensor. In other words, as long as it can be detected that the pressure of the pure water flowing downstream of the branch point B in the circulation line L1 is below a predetermined value, a pressure sensor may be used instead of the pressure switch 11 . Also, in order to reliably detect that the pure water starts to flow through the water delivery line L2, it is preferable to generate a sufficient pressure drop on the downstream side of the branch point B in the circulation line L1. Therefore, in the first embodiment, it is not necessary to provide the back pressure valve V2 as mentioned above, but it is preferable to provide the back pressure valve V2 in this embodiment. In addition, other back pressure generating mechanisms such as orifices may be provided instead of the back pressure valve V2.

(third embodiment) Fig. 3 is a schematic diagram showing the configuration of a pure water production apparatus according to a third embodiment of the present invention. Hereinafter, for the same configuration as the above-mentioned embodiment, the same symbols are attached to the drawings, and the description thereof is omitted, and only the configuration that is different from the above-mentioned embodiment will be described.

This embodiment is a modified example of the second embodiment, and the method of detecting whether the pure water flows to the water delivery pipeline L2 is different from the second embodiment. Specifically, in the second embodiment, in order to indirectly detect that pure water begins to flow through the water delivery pipeline L2, a pressure switch 11 is provided in the circulation pipeline L1. In contrast, in this embodiment, in order to directly It is detected that the pure water begins to flow in the water delivery pipeline L2, and a flow switch 12 is provided in the water delivery pipeline L2. The flow switch 12 outputs a detection signal when the flow rate of the pure water flowing through the water delivery pipeline L2 is above the set flow rate (predetermined value). The control unit 10 switches the rotation speed of the pump 3 from the first rotation speed to the second rotation speed when receiving the detection signal. Thereby, in this embodiment, it is also possible to suppress the temperature rise of the pure water during the circulation operation without wasting the pure water uselessly, and also to reduce the operating cost.

Also, in the second embodiment, if the pressure loss of the water delivery pipeline L2 changes, when pure water starts to flow through the water delivery pipeline L2, the pressure on the downstream side of the branch point B in the circulation pipeline L1 may not drop. Below the set pressure of pressure switch 11. Therefore, in the second embodiment, it is necessary to consider the change of the pressure loss of the water delivery pipeline L2, and adjust the set pressure of the pressure switch 11 according to this change, but this embodiment does not need to consider the change of the pressure loss. has its benefits.

As the detection mechanism that directly detects that the pure water begins to flow in the water delivery pipeline L2, it is not limited to the flow switch 12, and a flow sensor may also be used. In other words, as long as it can be detected that the flow rate of the pure water flowing through the water delivery pipeline L2 is above a predetermined value, a flow sensor can be used instead of the flow switch 12 .

(Fourth Embodiment) Fig. 4 is a schematic diagram showing the configuration of a pure water production apparatus according to a fourth embodiment of the present invention. Hereinafter, for the same configuration as the above-mentioned embodiment, the same symbols are attached to the drawings, and the description thereof is omitted, and only the configuration that is different from the above-mentioned embodiment will be described.

In the second embodiment, the rotation speed of the pump 3 is switched when it is detected that the pressure drop of the pure water on the downstream side of the branch point B in the circulation line L1 is detected. However, this pressure drop of pure water not only occurs when the pure water starts to flow through the water delivery pipeline L2 when switching from the circulation operation to the water extraction operation, but also when the flow rate of pure water flowing through the water delivery pipeline L2 increases during the water extraction operation. will also generate. Therefore, the switching of the rotation speed of the pump 3 may be performed according to the change of the flow rate of the pure water flowing through the water delivery pipeline L2 during the water harvesting operation as in the present embodiment.

In this embodiment, the water delivery pipeline L2 is branched into plural lines (three in the illustrated example), and each is connected to a plurality of use points 71-73 via solenoid valves V11-V13. In this case, water collection requests from plural usage points 71 to 73 are performed independently. Therefore, even during water mining operation, the flow rate of pure water flowing through the water delivery pipeline L2 also varies greatly. 71~73 In some cases where there is a requirement for water harvesting, it will increase significantly. In order to indirectly detect the increase in the pure water flow rate, a pressure sensor 13 is provided on the downstream side of the branch point B in the circulation pipeline L1 in this embodiment. The pressure sensor 13 outputs a detection signal when the pressure of the pure water flowing downstream of the branch point B in the circulation line L1 is lower than a predetermined set value. Then, when receiving the detection signal, the control unit 10 considers that the flow rate of the pure water flowing through the water delivery pipeline L2 has increased, and switches the rotation speed of the pump 3 from the first rotation speed to the second rotation speed. In this way, the rotation speed of the pump 3 can be switched according to the flow rate of pure water required by the use points 71-73. The temperature of pure water rises during circulation operation, which can also reduce operating costs.

The setting value (threshold value) of the pressure sensor 13 can be appropriately changed according to the flow rate of pure water required by each use point 71-73. For example, the rotation speed of the pump 3 is switched from the first rotation speed to the second rotation speed only when some of the usage points from the plurality of usage points 71-73 have water extraction requirements at the same time. In some cases where there is a requirement for water extraction, the rotation speed of the pump 3 is not switched, but the first rotation speed can be maintained. In addition, when the required pure water flow rates of the usage points 71-73 are different, the rotation speed of the pump 3 is switched from the first rotation speed to the second rotation speed only when there is a demand for water collection from the usage points with a larger required flow rate. also can.

Also, in this embodiment, like the third embodiment, it is also possible to directly detect the increase in the flow rate of the pure water flowing through the water delivery pipeline L2. As a detection mechanism for this purpose, it can be used to switch From the viewpoint of arbitrarily setting the threshold value of the rotational speed of the pump 3, it is preferable to use a flow sensor.

1: Pure water manufacturing device 2: storage tank 3: pump 4: UV oxidation device 5: Ion exchange device 6: Separation membrane device 7,71~73: Use point 10: Control Department (Control Mechanism) 11: Pressure switch 12: Flow switch 13: Pressure sensor B: branch point L1: circulation line L2: water pipeline L3: primary pure water supply line V1, V11~V13: Solenoid valve V2: Back pressure valve (back pressure generating mechanism)

[ Fig. 1 ] is a schematic diagram showing the configuration of a pure water production apparatus according to a first embodiment of the present invention. [ Fig. 2 ] is a schematic diagram showing the configuration of a pure water production apparatus according to a second embodiment of the present invention. [ Fig. 3 ] is a schematic diagram showing the configuration of a pure water production apparatus according to a third embodiment of the present invention. [ Fig. 4 ] is a schematic diagram showing the configuration of a pure water production apparatus according to a fourth embodiment of the present invention.

1: Pure water manufacturing device

2: storage tank

3: pump

4: UV oxidation device

5: Ion exchange device

6: Separation membrane device

7: point of use

10: Control Department (Control Mechanism)

11: Pressure switch

B: branch point

L1: circulation line

L2: water pipeline

L3: primary pure water supply line

V1: solenoid valve

V2: Back pressure valve (back pressure generating mechanism)

Claims (10)

A pure water manufacturing device has: Storage tanks for storing pure water; Circulation pipeline to circulate the pure water in the storage tank; The pump is installed in the circulation pipeline to make the pure water in the storage tank flow through the circulation pipeline; the water delivery line, on the downstream side of the pump, branches off from the circulation line and connects to the point of use; and The control mechanism switches the rotation speed of the pump according to the result of direct or indirect detection of whether there is pure water flowing in the water delivery pipeline or the change of the flow rate of pure water flowing through the water delivery pipeline. Such as the pure water production device of claim 1, wherein, The control mechanism switches the rotation speed of the pump from the first rotation speed to a value higher than the first rotation speed when pure water starts to flow through the water delivery pipeline or when the flow rate of pure water flowing through the water delivery pipeline increases. second speed. For example, the pure water manufacturing device of claim 2 further has: The detection mechanism directly or indirectly detects that pure water begins to flow through the water delivery pipeline, or the flow of pure water flowing through the water delivery pipeline increases, and outputs a detection signal; The control mechanism, when receiving the detection signal, switches the rotation speed of the pump from the first rotation speed to the second rotation speed. For example, the pure water manufacturing device of claim 3 further has: The back pressure generating mechanism is arranged on the downstream side of the branch point of the circulation pipeline and the water delivery pipeline; The detection mechanism outputs the detection signal when the pressure of the pure water flowing downstream of the branch point in the circulation pipeline is below a predetermined value. Such as the pure water production device of claim 4, wherein, The detection mechanism, which is a pressure switch or a pressure sensor, is arranged on the downstream side of the branch point in the circulation pipeline and on the upstream side of the back pressure generating mechanism. Such as the pure water production device of claim 3, wherein, The detection mechanism outputs the detection signal when the flow rate of the pure water flowing through the water pipeline is above a predetermined value. Such as the pure water production device of claim 6, wherein, The detecting mechanism is a flow switch or a flow sensor arranged on the water delivery pipeline. Such as the pure water production device of claim 2, wherein, The control mechanism switches the rotation speed of the pump from the first rotation speed to the second rotation speed when opening the electromagnetic valve connecting the water delivery pipeline and the use point. The pure water production device according to any one of claims 2 to 8, wherein, The control mechanism adjusts the rotation speed of the pump to the first rotation speed by setting the driving output of the pump to be less than 5W per 1L of the minimum storage water volume converted into the storage tank. A method for operating a pure water manufacturing device, comprising the following steps: Use the pump installed in the circulation pipeline to circulate the pure water stored in the storage tank along the circulation pipeline; The pure water circulating in the circulation pipeline is delivered to the point of use through the water delivery pipeline branched from the circulation pipeline on the downstream side of the pump; and According to the result obtained by directly or indirectly detecting whether there is pure water flowing in the water delivery pipeline or the flow change of the pure water flowing through the water delivery pipeline, the rotation speed of the pump is switched.

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