Liquid treatment unit and operation method of the same

Abstract

To suppress inflow of air bubbles of a liquid treatment device.SOLUTION: A liquid treatment unit 1 has: a liquid treatment device 3 for treating liquid; a liquid storage tank 2 for storing the liquid supplied to the liquid treatment device 3; a connection pipe L1 which connects the liquid storage tank 2 and the liquid treatment device 3, and has an inlet end 12 inside the liquid storage tank 2; liquid sending means 11 for sending the liquid stored in the liquid storage tank 2 to the liquid treatment device 3 through the connection pipe L1; detection means S1 for detecting presence / absence of the liquid of the liquid storage tank 2 at a predetermined position P above the inlet end 12; and a control part 9 which is connected to the detection means S1 and the liquid sending means 11, and stops the liquid sending means 11 when the detection means S1 detects the absence of the liquid at the predetermined position P.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a liquid treatment unit and an operation method thereof.

Background Art

[0002] Liquid treatment apparatuses for purifying, concentrating, etc. aqueous solutions and non-aqueous liquids are used in various fields such as analysis and semiconductor manufacturing. Liquid treatment apparatuses have functional materials such as ion exchange resins. When bubbles are mixed into the liquid, there is a possibility that the bubbles are adsorbed on the surface of the functional material and the treatment of the liquid is inhibited. Patent Document 1 describes an alcohol purification apparatus using an ion exchange resin. This apparatus has a column filled with an ion exchange resin and an orifice provided downstream of the column. The orifice applies a predetermined pressure to the liquid passing through the column. By this pressure, the pressure inside the column rises, and the generation of bubbles inside the column is prevented.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] According to the method described in Patent Document 1, it is possible to suppress the generation of bubbles in the liquid. However, in order to further suppress the generation of bubbles in the liquid treatment apparatus, it is desirable to suppress the inflow of bubbles into the liquid treatment apparatus. An object of the present invention is to provide a liquid treatment unit capable of suppressing the inflow of bubbles into the liquid treatment apparatus.

Means for Solving the Problems

[0005] The liquid processing unit of the present invention includes a liquid processing apparatus for processing a liquid, a liquid storage tank for storing the liquid supplied to the liquid processing apparatus, a connection pipe that connects the liquid storage tank and the liquid processing apparatus and has an inlet end inside the liquid storage tank, a liquid delivery means for delivering the liquid stored in the liquid storage tank to the liquid processing apparatus through the connection pipe, a detection means for detecting the presence or absence of the liquid in the liquid storage tank at a predetermined position above the inlet end, and a control unit that is connected to the detection means and the liquid delivery means and stops the liquid delivery means when the detection means detects the absence of the liquid at the predetermined position.

Advantages of the Invention

[0006] According to the present invention, it is possible to provide a liquid processing unit capable of suppressing the inflow of bubbles into the liquid processing apparatus.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0008] Hereinafter, some embodiments of the liquid treatment unit of the present invention and its operation method will be described with reference to the drawings. The liquid treatment unit of the present invention and its operation method can be applied to any liquid, but are particularly suitable for the purification and concentration of flammable liquids, especially organic solvents. The following embodiments are directed to a relatively small unit for purifying an organic solvent for analysis, but the present invention can also be applied to large-scale plants for purifying or concentrating large amounts of liquid, and the scale of the unit is not limited.

[0009] (First Embodiment) Figs. 1(a) and 2 show the schematic configuration of the liquid treatment unit 1 according to the first embodiment. Fig. 1(b) shows the schematic configuration in the vicinity of the liquid storage tank 2 of the liquid treatment unit 1. In Fig. 1, the flow of the liquid in the purification process is indicated by a thick solid line, and the flow of the pressurized gas is indicated by a thick dashed line. In Fig. 2, the flow of the liquid in the liquid replenishment process is indicated by a thick solid line. The liquid treatment unit 1 includes a liquid treatment device 3 for purifying a flammable liquid, a liquid storage tank 2 for storing the liquid supplied to the liquid treatment device 3, a liquid delivery means 11 for sending the liquid stored in the liquid storage tank 2 to the liquid treatment device 3, a detection means (level switch) S1 for detecting the presence or absence of the liquid at a predetermined position P of the liquid storage tank 2, and a control unit 9. The liquid delivery means 11 employs a pressure feeding method in which the liquid is extruded out of the liquid storage tank 2 by supplying a pressurized gas to the liquid storage tank 2. As the pressurized gas, it is preferable to use a gas that does not react with the liquid.

[0010] The liquid treatment device 3 includes a functional material filling device 4 filled with a granular functional material composed of at least one of an ion exchanger, activated carbon, a synthetic adsorbent, and zeolite, and a filter device 5. The ion exchanger may be in a monolithic form or may be formed by molding powder with a binder. Alternatively, two or more types of ion exchangers may be mixed and used. The filter device 5 includes, for example, a microfiltration membrane or an ultrafiltration membrane. The filter device 5 may have a functional group introduced therein. The functional material filling device 4 and the filter device 5 may be integrated. The functional material filling device 4 and the filter device 5 are arranged in series on the first liquid supply pipe L1. Although not shown, a plurality of functional material filling devices 4 and / or a plurality of filter devices 5 may be arranged in series or in parallel. The configuration of the liquid treatment device 3 can be appropriately determined according to the cleanliness of the liquid to be purified and the required cleanliness.

[0011] The liquid supplied to the functional material filling device 4 and the filter device 5 may be either an upward flow or a downward flow. When the functional material is granular, a downward flow causes the functional material to be pushed by the liquid and filled at a high density, resulting in higher treatment performance. On the other hand, in a downward flow, air bubbles mixed into the functional material filling device 4 may enter the gaps between the functional materials, making it difficult for them to escape from the functional material filling device 4. In this case, since there is a high possibility that the treatment performance will decrease, the downward flow is a configuration in which the effects of the present embodiment are more easily obtained.

[0012] The liquid storage tank 2 and the liquid processing device 3 are arranged in series on the first liquid supply pipe L1. The liquid storage tank 2 is arranged upstream of the liquid processing device 3. The first liquid supply pipe L1 is a connecting pipe L1 that connects the liquid storage tank 2 and the liquid processing device 3, and sends the liquid stored in the liquid storage tank 2 to the liquid processing device 3. The first liquid supply pipe L1 is inserted into the liquid storage tank 2 downward from above the liquid storage tank 2. As shown in FIG. 1(b), the end portion of the first liquid supply pipe L1 in the liquid storage tank 2 (hereinafter referred to as the inlet end portion 12) and the portion in its vicinity are located inside the liquid storage tank 2. Among the first liquid supply pipe L1, the portion inside the liquid storage tank 2 and above the inlet end portion 12 is referred to as an end adjacent portion 13. The end adjacent portion 13 extends linearly in the vertical direction generally. The inlet end portion 12 and the end adjacent portion 13 are spaced apart from the bottom surface of the liquid storage tank 2.

[0013] The liquid storage tank 2 and the liquid processing device 3 are housed in a housing 6. Since the liquid storage tank 2 and the liquid processing device 3 contain an organic solvent which is a flammable liquid, the housing 6 is preferably formed of metal in order to ensure chemical resistance, strength, and explosion-proof properties, but the material of the housing 6 is not limited to metal. An exhaust opening 6A is provided at the top of the housing 6, but the shape and size of the opening 6A are not limited. In addition, the pipes and components described below are also housed in the housing 6 unless otherwise specified.

[0014] The first drain pipe L6 branches off from the first liquid supply pipe L1 and extends outside the housing 6. A three-way valve V6 is installed at the branch where the first drain pipe L6 branches off from the first liquid supply pipe L1. A second vent pipe L7 branches off from between the functional material filling device 4 and the filter device 5 of the first liquid supply pipe L1 and merges into the first drain pipe L6. The second vent pipe L7 is provided to discharge the gas inside the functional material filling device 4 when the functional material filling device 4 is emptied for maintenance or the like and then refilled with liquid. Further, the second vent pipe L7 can also be used to discharge waste liquid generated during the initial cleaning performed to remove gas contained between granular functional materials, gas mixed into the liquid supply pipe L1 connected to the functional material filling device 4, particulate impurities, another liquid purified before refilling the liquid, and the like. A three-way valve V4 for switching between the process of discharging the gas inside the functional material filling device 4 and the purification process is installed at the branch of the second vent pipe L7 of the first liquid supply pipe L1. A purified liquid discharge pipe L5 passing through the housing 6 is connected to the outlet of the filter device 5. The liquid purified by the liquid treatment device 3 is discharged outside the housing 6 through the purified liquid discharge pipe L5.

[0015] A liquid supply section 7 is provided outside the housing 6, and the liquid supply section 7 is connected to the liquid storage tank 2 by a second liquid supply pipe L4 passing through the housing 6. The second liquid supply pipe L4 supplies liquid to the liquid storage tank 2. The liquid treatment in the liquid treatment device 3 is performed as a batch process, and the valve V1 provided in the second liquid supply pipe L4 remains closed until a certain amount of liquid stored in the liquid storage tank 2 is processed by the liquid treatment device 3. Note that the batch process in the present embodiment refers to sending the liquid stored in the liquid storage tank 2 to the liquid treatment device 3 for processing, and does not include adding a functional material (a substance that removes impurities from the liquid) into the liquid storage tank 2, nor does it include a continuous process that simultaneously performs liquid supply into the liquid storage tank 2 and liquid feeding outside the liquid storage tank 2. The valve V1 is a manual valve, and an operation section (not shown) such as a handle is provided outside the housing 6, but it may also be provided inside the housing 6.

[0016] A pressurized gas supply unit 8 is provided outside the housing 6. The pressurized gas supply unit 8 is connected to the liquid storage tank 2 by a pressurized gas supply pipe L3 that penetrates the housing 6 and a first vent pipe L2 (described later). The pressurized gas supply pipe L3 supplies pressurized gas to the liquid storage tank 2. The liquid storage tank 2 is a pressure-resistant sealed container. The pressurized gas is used to pressurize the liquid inside the liquid storage tank 2 and send it to the liquid processing device 3. As the pressurized gas, an inert gas such as compressed air or nitrogen is used. Since this embodiment is applicable to the high-purity purification of chemical liquids used in applications such as semiconductor manufacturing and analysis, the pressurized gas that has undergone the processes of dehumidification, dust removal, and oil removal is used, and the degree of dehumidification is preferably a dew point of -40°C or lower. By using the pressurized gas dehumidified to this extent, when the liquid is a non-aqueous solvent, an increase in the water content of the liquid can be suppressed, and the deterioration of a hydrolyzable organic solvent such as esters can also be suppressed. A valve V2 for controlling the supply of the pressurized gas is provided in the pressurized gas supply pipe L3. The flow rate of the liquid supplied to the liquid processing device 3 can be controlled by adjusting the supply pressure of the pressurized gas with the supply unit 8 or the valve V2. A solenoid valve V5 is provided in the pressurized gas supply pipe L3. The solenoid valve V5 is provided in a non-hazardous area outside the housing 6 and is connected to the control unit 9.

[0017] A first vent pipe L2 is provided which communicates with the interior of the liquid storage tank 2 and extends upward from the liquid storage tank 2. The first vent pipe L2 is connected to a first drain pipe L6 (see A connected to the valve V3 in Fig. 1(a)). The first vent pipe L2 is provided for discharging the gas inside the liquid storage tank 2 in the liquid replenishment process, but is also used for supplying pressurized gas to the liquid storage tank 2 in the purification process. That is, in the purification process, the pressurized gas is supplied to the liquid storage tank 2 through the pressurized gas supply pipe L3 and the first vent pipe L2. Since the pressurized gas supply pipe L3 is connected to the first vent pipe L2, it is possible to reduce the amount of piping. A three-way valve V3 is provided at the confluence of the pressurized gas supply pipe L3 and the first vent pipe L2 in order to switch between the purification process and the liquid replenishment process. The pressurized gas supply section 8, the pressurized gas supply pipe L3, the first vent pipe L2, the solenoid valve V5, the valve V2, and the three-way valve V3 constitute a liquid delivery means 11 for delivering the liquid stored in the liquid storage tank 2 to the liquid processing device 3 through the first liquid supply pipe L1.

[0018] A drain pan 10 is installed at the bottom of the housing 6. A second drain pipe L8 connected to the drain pan 10 penetrates the housing 6 and extends outside the housing 6. The drain pan 10 is provided for collecting and holding the leaked liquid in the event of a liquid leak occurring inside the housing 6.

[0019] It is preferable that the inner surfaces of the first liquid supply pipe L1, the second liquid supply pipe L4, and the purified liquid discharge pipe L5 are each formed of a fluororesin. Similarly, it is preferable that the inner surface of the liquid storage tank 2, the inner surface of the casing of the functional material filling device 4, and the inner surface of the casing of the filter device 5 are also formed of a fluororesin. These pipes, tanks, and casings allow the raw material liquid or the purified liquid to pass through. Therefore, by forming at least the liquid contact portion with a fluororesin that has high resistance to organic solvents and is difficult to be contaminated, high-purity purification capable of reducing the impurity concentration of metals to the ppt level or lower becomes possible. Examples of the fluororesin include perfluoroalkoxy alkane (PFA) and polytetrafluoroethylene (PTFE). Since these fluororesins have a high surface free energy and high water repellency, they have good cleanability. As a result, particularly in the concentration analysis described later, the recovery efficiency of impurities to be analyzed is increased and the analysis accuracy is improved. Since no liquid flows through the pressurized gas supply pipe L3, it is not necessary to form the inner surface with a fluororesin.

[0020] When passing an organic solvent with an impurity concentration at the ppt level through the functional material filling device 4 or the filter device 5, it is necessary to sufficiently remove the air bubbles in the functional material filling device 4 or the filter device 5. If air bubbles enter the functional material filling device 4 or the filter device 5 through the first liquid supply pipe L1, a part of the surface of the functional material or the filter may be covered with air bubbles, and there is a possibility that impurities may not be sufficiently removed. Further, if the operation of the liquid delivery means 11 continues with the liquid storage tank 2 emptied, all the liquid in the system including the functional material filling device 4 and the filter device 5 will be discharged out of the system. In this case, it is necessary to refill the system with liquid again and perform an operation to discharge air bubbles, which is very troublesome. Therefore, it is desirable to always keep the first liquid supply pipe L1 filled with liquid. For this purpose, a level switch S1 for monitoring the liquid level of the liquid storage tank 2 is provided inside the housing 6. The level switch S1 is provided outside the liquid storage tank 2, specifically, on the outer surface of the side wall 21 of the liquid storage tank 2. The level switch S1 is located laterally adjacent to the end adjacent portion 13 of the first liquid supply pipe L1, that is, above the inlet end 12. The level switch S1 is an example of a detection means S1 that detects the presence or absence of liquid at a predetermined position P above the inlet end 12 of the liquid storage tank 2. The level switch S1 and the control unit 9 are connected by a cable C1 passing through the housing 6.

[0021] When passing a liquid such as an organic solvent, it is desirable to avoid using electrical equipment in consideration of safety. However, when electrical equipment is not used, it is difficult to perform online measurement and automatic control. The level switch S1 of this embodiment is an explosion-proof capacitive proximity sensor in which the current-carrying part is sealed with resin or the like, and for example, the capacitive proximity sensor K1505A manufactured by ifm efector Co., Ltd. can be used. Since the capacitive proximity sensor detects the liquid level based on the change in capacitance, it is possible to detect the liquid level simply by attaching it to the side wall 21 of the liquid storage tank 2. However, in order to ensure the measurement accuracy, it is preferable that the end adjacent part 13 of the first liquid supply pipe L1 is arranged as close as possible to the level switch S1. Based on the measurement principle, it is desirable that the liquid storage tank 2 is made of a non-metallic material. PFA is preferable as the material of the liquid storage tank 2 because it is translucent and the liquid level can be visually confirmed, and the adhesion of impurities can be suppressed. The structure of the liquid storage tank 2 itself may be a simple shape such as a cylindrical shape or a rectangular parallelepiped. Since the level switch S1 is a non-contact type installed away from the liquid, contamination of the liquid by the level switch S1 is also suppressed, and high-purity purification is possible.

[0022] The control unit 9 is provided in a non-hazardous area outside the housing 6 and is connected to the detection means S1 and the solenoid valve V5 of the liquid delivery means 11. When the detection means S1 detects that there is no liquid at the predetermined position P, the control unit 9 transmits a signal for stopping the operation of the liquid delivery means 11, specifically, a signal for closing the solenoid valve V5, to the solenoid valve V5.

[0023] The overflow detection sensor S2 is attached to the first vent pipe L2. The overflow detection sensor S2 is preferably an explosion-proof certified product or a non-explosion-proof target product. In this embodiment, an optical type is used. The overflow detection sensor S2 has a light emitting part and a light receiving part (not shown) attached so as to sandwich the first vent pipe L2. Since the refractive index of the light emitted from the light emitting part changes depending on the type of the medium between the light emitting part and the light receiving part, the liquid level can be detected based on the change in the amount of light received by the light receiving part. A circuit (not shown) for operating the overflow detection sensor S2, that is, a circuit for generating light to be emitted by the light emitting part and a circuit for receiving the light returning from the overflow detection sensor S2 require a power supply, but these circuits are provided in a non-dangerous area outside the housing 6. The overflow detection sensor S2 and the control unit 9 are connected by an optical cable C2 passing through the housing 6. The part of the first vent pipe L2 where the overflow detection sensor S2 is attached is formed of a transparent or translucent member. As the overflow detection sensor S2, for example, an optical level switch such as the liquid detection sensor TK-010N2 manufactured by Toho Chemical Co., Ltd. or the pipe-mounted liquid level fiber unit HPF-T034 manufactured by Azbil Corporation can be used.

[0024] The liquid treatment unit 1 configured as described above operates as follows. Referring to FIG. 1(a), in the purification process, pressurized gas is supplied from the pressurized gas supply section 8 to the liquid storage tank 2 through the pressurized gas supply pipe L3 and the first vent pipe L2. The liquid stored in the liquid storage tank 2 is pressurized by the pressurized gas and sent to the liquid treatment device 3 (the functional material filling device 4 and the filter device 5) through the first liquid supply pipe L1. The liquid is purified by removing ionic substances and fine particles in the liquid treatment device 3 and discharged to the outside of the housing 6 through the purified liquid discharge pipe L5. During the operation of the liquid treatment unit 1, since the inlet end 12 is immersed in the liquid of the liquid storage tank 2, the possibility of gas mixing into the liquid treatment device 3 from the first liquid supply pipe L1 is low.

[0025] Since the purification process is performed in batch as described above, the liquid level in the liquid storage tank 2 gradually decreases. When the level switch S1 detects the absence of liquid at the predetermined position P, it sends a signal indicating the same to the control unit 9. The control unit 9 closes the solenoid valve V5 and stops the supply of pressurized gas. Thereby, one purification process is completed. Since the liquid delivery means 11 is stopped before the liquid level in the liquid storage tank 2 reaches the inlet end 12, the possibility of gas being mixed into the liquid processing apparatus 3 is reduced. The predetermined position P, that is, the installation position of the level switch S1 is not particularly limited, but a position slightly above the inlet end 12 is preferable. Thereby, it becomes easy to secure the amount of liquid that can be processed in one batch process.

[0026] Next, a liquid replenishment process of replenishing the liquid storage tank 2 with liquid for the next batch process is performed. Referring to FIG. 2, the valve V2 is closed, the valve V1 is opened, the A side of the valve V3 is opened, and the liquid is supplied from the liquid supply section 7 to the liquid storage tank 2 through the second liquid supply pipe L4. The gas in the liquid storage tank 2 is purged through the first vent pipe L2 and replaced with liquid. When the liquid storage tank 2 is filled with liquid, the liquid flows out of the liquid storage tank 2 and into the first vent pipe L2. When the overflow detection sensor S2 detects the liquid level inside the first vent pipe L2, it sends a signal indicating the same to the control unit 9. The control unit 9 notifies the operator in an appropriate manner that the overflow detection sensor S2 has detected the liquid level. The operator can recognize that the liquid storage tank 2 is filled with liquid based on the notification. Therefore, the operator can operate the operation section outside the housing 6 of the valve V1 of the second liquid supply pipe L4 to stop the supply of liquid.

[0027] After that, close valve V1, open valves V2 and solenoid valve V5, open the L2 side of valve V3 to perform the next purification process, and the liquid replenishment process and the purification process can be repeated the necessary number of times. That is, the liquid treatment unit 1 can send the liquid stored in the liquid storage tank 2 to the liquid treatment device 3 through the connection pipe L1 by the liquid delivery means 11, process the liquid in the liquid treatment device 3, discharge the liquid processed in the liquid treatment device 3, and supply new liquid to the liquid storage tank 2, and can repeat a plurality of treatment cycles including these operations.

[0028] According to the present embodiment, even when the treatment cycle is repeated a plurality of times, the inflow of bubbles into the first liquid supply pipe L1, the functional material filling device 4, and the filter device 5 can be effectively suppressed. FIG. 3 shows a schematic configuration in the vicinity of the liquid storage tank 2 of the liquid treatment unit of the comparative example. The level switch S101 is provided above the liquid storage tank 2 of the first liquid supply pipe L1, and detects the presence or absence of liquid (gas) in the first liquid supply pipe L1 at a predetermined position P1 above the liquid storage tank 2. According to this configuration, when the level switch S101 detects gas, a signal indicating that fact can be notified to the operator. By the operator stopping the liquid delivery means 11 based on this notification, the possibility of gas entering the liquid treatment device 3 can be reduced.

[0029] However, in this configuration, when the level switch S101 detects the gas in the first liquid supply pipe L1, there is a possibility that bubbles have already flowed into the inside of the first liquid supply pipe L1, particularly the region 131 between the inlet end 12 and the level switch S101. Therefore, when the next purification process is performed after the liquid replenishment process, the mixed bubbles may be pushed downstream and reach the functional material filling device 4 and the filter device 5. In the present embodiment, since the first liquid supply pipe L1 is maintained in a state of being filled with liquid both in the liquid replenishment process and in the purification process, even when the treatment cycle is repeated a plurality of times, the possibility of bubbles flowing into the functional material filling device 4 and the filter device 5 is reduced.

[0030] (Second Embodiment) FIG. 4 shows a schematic configuration in the vicinity of the liquid storage tank 2 of the liquid processing unit 1 according to the second embodiment. Here, the description will focus on the points different from the first embodiment. The configurations and effects for which the description is omitted are the same as those of the first embodiment. The liquid storage tank 2 has a main body 22 for storing a liquid, and a bypass pipe 23 that extends vertically outside the side wall 21 of the main body 22 and both ends 24 and 25 of which are connected to the side wall 21 of the main body 22. The level switch S1 is provided in the bypass pipe 23. The lower end 24 of the bypass pipe 23 is preferably below the inlet end 12 to secure the installation position of the level switch S1, and the upper end 25 of the bypass pipe 23 is at an arbitrary position above the lower end 24 of the side wall 21. Since the liquid level of the main body 22 of the liquid storage tank 2 and the liquid level of the bypass pipe 23 are substantially the same, the liquid level of the main body 22 of the liquid storage tank 2 can be detected by detecting the liquid level of the bypass pipe 23 with the level switch S1. For the same reason as in the first embodiment, the level switch S1 is preferably provided at the lowest possible part of the bypass pipe 23.

[0031] Since the liquid is flammable, the level switch S1 of this embodiment is preferably an explosion-proof certified product or a non-explosion-proof target product, and an optical level switch is used as in the overflow detection sensor S2 of the first embodiment. For the configuration and example of the optical level switch, refer to the first embodiment. The level switch S1 and the control unit 9 are connected by an optical cable (not shown) that penetrates the housing 6. The bypass pipe 23 is preferably formed of a light-transmissive material such as PFA. Since the main body 22 of the liquid storage tank 2 may be made of a metal such as stainless steel, it is easy to ensure pressure resistance against pressurization by a pressurized gas. However, when the main body 22 of the liquid storage tank 2 is made of metal, the inner surface of the main body 22 is preferably coated with a fluororesin. Similar to the first embodiment, the main body 22 of the liquid storage tank 2 can also be formed of a fluororesin.

[0032] (Third Embodiment) Figure 5 shows the schematic configuration of the liquid processing unit 1 according to the third embodiment. Here, the description will focus on the differences from the first embodiment. The configurations and effects for which the description is omitted are the same as those in the first embodiment. The detection means S1 includes a weight sensor 26 that measures the total weight of the self-weight of the liquid storage tank 2 and the weight of the liquid stored in the liquid storage tank 2, and a determination means 27 that determines the presence or absence of the liquid at a predetermined position P based on the total weight measured by the weight sensor 26. The determination means 27 is configured as part of the control unit 9, but may be provided separately from the control unit 9. The weight sensor 26 is, for example, one using a load cell, and preferably has an explosion-proof type. As an example of the load cell, an explosion-proof compression type load cell LCS-D manufactured by KYOWA Co., Ltd. can be mentioned. Since the self-weight of the liquid storage tank 2 and the specific gravity of the liquid stored in the liquid storage tank 2 are known in advance, the total weight (hereinafter referred to as the reference weight) when the liquid level coincides with the predetermined position P can be calculated in advance. The determination means 27 (control unit 9) closes the solenoid valve V5 and stops the supply of the pressurized gas when the total weight reaches the reference weight. In this embodiment, the liquid storage tank 2 does not have to be translucent, and the material of the liquid storage tank 2 is not limited, but at least the inner surface of the liquid storage tank 2 is preferably formed of a fluororesin.

[0033] (Fourth Embodiment) Figures 6 and 7 show the schematic configuration of the liquid processing unit 1 according to the fourth embodiment. In Figure 6, the flow of the liquid in the purification process (circulation operation) is indicated by a thick solid line, and the flow of the pressurized gas is indicated by a thick dashed line. In Figure 7, the flow of the liquid in the liquid replenishment process is indicated by a thick solid line, and the flow of the pressurized gas is indicated by a thick dashed line. Here, the description will focus on the differences from the first embodiment. The configurations and effects for which the description is omitted are the same as those in the first embodiment. Also, this embodiment can be combined with any one of the second to third embodiments. The liquid delivery means 11 of this embodiment has a diaphragm pump 14.

[0034] The liquid treatment unit 1 connects the liquid treatment device 3 and the liquid storage tank 2, and has a return pipe L9 for returning the purified liquid generated by the liquid treatment device 3 to the liquid storage tank 2. That is, the liquid treatment unit 1 of the present embodiment purifies the liquid while circulating the liquid along the circulation path composed of the first liquid supply pipe L1 and the return pipe L9. The diaphragm pump 14 is provided between the liquid storage tank 2 and the liquid treatment device 3 of the first liquid supply pipe L1, and sends the liquid to the liquid treatment device 3. The diaphragm pump 14 is a type of positive displacement pump that discharges the liquid while moving the diaphragm using a pressurized gas such as an inert gas like nitrogen or air. The pressurized gas is supplied from the working fluid supply unit 15 outside the housing 6 to the diaphragm pump 14 through the working fluid supply pipe L10. The working fluid supply unit 15 is connected to the control unit 9. When used as the liquid delivery means 11 of a device for handling dangerous substances, it is preferable that the diaphragm pump 14 uses a non-powered air-driven type. When a pressurized gas such as nitrogen or air is supplied, the diaphragm moves so that the pump chamber volume decreases due to the pressure of the pressurized gas, and when the supply of the pressurized gas is stopped, the diaphragm is pulled back so that the pump chamber volume expands. Therefore, there is no need to provide an energized part inside the housing 6. The liquid contact part of the diaphragm pump 14 is preferably made of fluororesin, like the pipes and casings. The control unit 9 controls the supply of the working fluid by controlling the working fluid supply unit 15. The flow rate of the liquid supplied to the liquid treatment device 3 can be controlled by adjusting the supply pressure and supply timing of the working fluid by the control unit 9.

[0035] The liquid treatment unit 1 configured as described above operates as follows. Referring to FIG. 6, in the purification process, the working fluid is supplied to the diaphragm pump 14 through the working fluid supply pipe L10. The liquid circulates along the circulation path, and the purification of the liquid is performed. After a predetermined time has elapsed, a valve (not shown) is operated to switch the return pipe L9 to the purified liquid discharge pipe L5. The purified liquid is discharged to the outside of the housing 6 by the diaphragm pump 14. The liquid level in the liquid storage tank 2 gradually decreases. When the level switch S1 detects that there is no liquid at the predetermined position P of the liquid storage tank 2, it transmits a signal indicating the same to the control unit 9. The control unit 9 stops the operation of the diaphragm pump 14 and stops the supply of the working fluid.

[0036] Thereafter, a liquid replenishment process of replenishing the liquid storage tank 2 with liquid for the next batch process is performed. Referring to FIG. 7, the valve V1 is opened, and the liquid is supplied from the liquid supply unit 7 to the liquid storage tank 2 through the second liquid supply pipe L4. The subsequent operations are the same as those in the first embodiment. Since the first liquid supply pipe L1, the functional material filling device 4, and the filter device 5 are maintained in a state filled with liquid during this period, the possibility of air bubbles flowing into the first liquid supply pipe L1, the functional material filling device 4, and the filter device 5 is reduced even in the liquid replenishment process.

[0037] (Application to concentration treatment) Although the embodiments of the present invention have been described above, the present invention can also be applied to concentration processes such as liquid concentration analysis and concentration recovery of valuable substances. For example, when the present invention is utilized for concentration analysis, the concentration step and the liquid replenishment step may be repeated multiple times in order to make the concentration of the analyte higher than the lower limit of quantification in the concentration analysis. In particular, the method of repeating the circulation of the liquid as in the fourth embodiment is preferably used for concentration analysis because it is easy to increase the contact time between the liquid and the functional material. At this time, if gas flows into the system, there is a possibility that the analyte will not be sufficiently concentrated and the analysis accuracy will decrease. By using the present invention, the mixing of bubbles can be suppressed and the concentration ratio can be increased, so that the analysis accuracy can be improved. Also, when concentrating ionic components on functional materials such as ion exchange resins and monoliths, a driving method in which rapid changes in flow rate and pressure do not occur is preferable, and any of the above-described embodiments enables such driving.

Explanation of Signs

[0038] 1 Liquid treatment unit 2 Liquid storage tank 3 Liquid treatment apparatus 9 Control unit 11 Liquid delivery means 12 Inlet end 21 Side wall 23 Bypass pipe 26 Weight sensor 27 Judgment means L1 First liquid supply pipe (connection pipe) P Predetermined position S1 Detection means S2 Overflow detection sensor

Claims

1. A liquid treatment apparatus for treating a liquid, A liquid storage tank for storing the liquid supplied to the liquid treatment apparatus, A connection pipe connecting the liquid storage tank and the liquid treatment apparatus and having an inlet end inside the liquid storage tank, Liquid delivery means for delivering the liquid stored in the liquid storage tank to the liquid treatment apparatus through the connection pipe, Detection means for detecting the presence or absence of the liquid in the liquid storage tank at a predetermined position above the inlet end, A control unit connected to the detection means and the liquid delivery means, which stops the liquid delivery means when the detection means detects the absence of the liquid at the predetermined position, A liquid treatment unit having the above.

2. The connection pipe has an end adjacent portion adjacent to the inlet end and located above the inlet end, and the end adjacent portion is inside the liquid storage tank, The detection means is a level switch, The level switch is outside the liquid storage tank and on the side of the connection adjacent portion. The liquid treatment unit according to claim 1.

3. The level switch is provided on the side wall of the liquid storage tank. The liquid treatment unit according to claim 2.

4. The liquid storage tank has a main body for storing the liquid and a bypass pipe extending vertically outside the side wall of the main body and having both ends connected to the side wall. The level switch is provided on the bypass pipe. The liquid treatment unit according to claim 2.

5. The detection means includes a weight sensor for measuring the total weight of the self-weight of the liquid storage tank and the weight of the liquid stored in the liquid storage tank, and a determination means for determining the presence or absence of the liquid at the predetermined position based on the total weight measured by the weight sensor. The liquid treatment unit according to claim 1.

6. The inner surface of the liquid storage tank is formed of a fluororesin. The liquid treatment unit according to any one of claims 1 to 5.

7. A method of operating a liquid treatment unit having a liquid treatment apparatus for treating a liquid, a liquid storage tank for storing the liquid supplied to the liquid treatment apparatus, a connection pipe connecting the liquid storage tank and the liquid treatment apparatus and having an inlet end inside the liquid storage tank, and liquid delivery means for delivering the liquid stored in the liquid storage tank to the liquid treatment apparatus through the connection pipe, Sending the liquid stored in the liquid storage tank to the liquid processing device through the connection pipe by the liquid delivery means, processing the liquid in the liquid processing device, discharging the processed liquid, and supplying new liquid to the liquid storage tank, and repeating a plurality of times a processing cycle including these steps. When repeating the processing cycle a plurality of times, detecting the presence or absence of the liquid at a predetermined position above the inlet end of the liquid storage tank by a detection means. When the detection means detects the absence of the liquid at the predetermined position, a control unit connected to the detection means and the liquid delivery means stops the liquid delivery means. An operation method of a liquid processing unit having these steps.

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