JP6290752B2 - Centrifugal filter, particulate trap using the same, particulate capture method, and particulate detection method - Google Patents

Description

  The present invention relates to a centrifugal filter and a particulate trapping device using the same, and more particularly to a cooling mechanism of the centrifugal filter. The present invention also relates to a particulate capturing method and a particulate detecting method using a centrifugal filter.

  In recent years, with the high integration of semiconductor devices, the line width of the devices has become finer. Therefore, pure water or ultrapure water used in the field of semiconductor manufacturing is increasingly required to have high purity water quality. In particular, for fine particles that are directly affected by yield, strict management is required for both the particle size and concentration. Recently, it may be required to control the concentration of the fine particles below a specified value. The same applies to pure water or ultrapure water used in the field of chemical production.

  A direct spectroscopic method is known as a method for detecting fine particles in pure water or ultrapure water (Non-Patent Document 1). According to this method, pure water or ultrapure water is filtered by the filtration membrane, the fine particles are captured on the filtration membrane, and the fine particles are detected using an optical microscope or a scanning electron microscope. By using a filtration membrane having a pore size smaller than that of the fine particles to be detected, it is possible to detect even fine particles having a small particle size. However, in order to ensure the reliability of detection, it is desirable to capture as many or more fine particles as the number of fine particles contained in the filtration membrane itself, so that a sufficient amount of pure water or ultrapure water is sufficient. Must be passed through the filter membrane. Further, as the particle size of the fine particles to be detected becomes smaller, the pore size of the filtration membrane becomes smaller and the pressure loss of the filtration membrane increases. For these reasons, it is necessary to filter for a long time to detect fine particles having a small particle diameter.

  A method of filtering pure water or ultrapure water using a centrifugal filter when detecting microparticles using a direct spectroscopic method is known (Patent Documents 1 and 2). Pure water or ultrapure water is pressurized by centrifugal force, and the flow rate of pure water or ultrapure water passing through the filtration membrane increases. For this reason, the time required for filtration is shortened.

Japanese Utility Model Publication No. 4-136550 JP 2012-115810 A

Japanese Industrial Standards JIS K 0554-1995 “Measurement Method of Fine Particles in Ultrapure Water”

  Although the time required for filtration is shortened by using a centrifugal filter, it may still require a long time of filtration. For example, in order to detect fine particles having a particle size of the order of nm, a filtration membrane having a pore size smaller than the particle size is used. Therefore, in order to secure a certain amount of water flow, the centrifugal filter may be continuously operated for about one month. . Due to the continuous operation of the centrifugal filter, the temperature inside the centrifugal filter tends to increase with time. Along with this, there is a possibility that the wetted part of the member constituting the centrifugal filter elutes and becomes fine particles and mixed into pure water or ultrapure water. When viable bacteria are contained in pure water or ultrapure water, the viable bacteria may adhere to the filtration membrane and grow on the filtration membrane. These phenomena greatly reduce the detection accuracy of the fine particles.

  An object of this invention is to provide the centrifugal filter which can capture | acquire the microparticles | fine-particles contained in a liquid more correctly, and a microparticle capture | acquisition method.

The centrifugal filter of the present invention has a filter body provided with a rotating part, and a chamber for housing the filter body. The rotating part includes a liquid chamber, a filter membrane detachably provided in the liquid chamber, a drainage part for discharging the filtrate filtered by the filter membrane, and a coaxial axis with the rotation center axis of the rotating part. A surplus liquid drain pipe for draining the surplus liquid . The centrifugal filter further has a cooling mechanism for cooling the liquid in the rotating part before being filtered by the filtration membrane. The cooling mechanism is located above the rotating part and communicates with the outside of the chamber, and is located below the rotating part and outside the first external communicating hole in the radial direction of the rotating part. A second external communication hole communicating with the first external communication hole. The main body of the filter has a first liquid reservoir for recovering the excess liquid drained from the excess liquid drain pipe, and the first liquid reservoir is disposed around the outlet of the excess liquid drain pipe with respect to the excess liquid drain pipe. It is located with a gap. The chamber has a second liquid reservoir for collecting the filtrate inside and discharging it to the second external communication hole, and a filtrate discharge pipe extends from the second external communication hole to the outside of the chamber. Pressure adjusting means for adjusting the pressure of the chamber is provided in the discharge pipe.

  The liquid supplied to the liquid chamber is filtered through a filtration membrane, and flows out into the chamber through a drainage section provided on the outlet side of the filtration membrane. Since the liquid in the rotating part before being filtered by the filtration membrane is cooled by the cooling mechanism, the detection accuracy of the fine particles is prevented from being lowered.

The fine particle capturing method of the present invention includes a filter main body provided with a rotating part, and a chamber for accommodating the filter main body, and the rotating part is provided in a liquid chamber and a filtration membrane detachably provided in the liquid chamber. If, possess a drainage portion for discharging the filtered liquid having passed through the filtration membrane, and excess liquid drain pipe for draining the excess liquid of the rotation center axis is arranged coaxially liquid chamber rotating unit, and is filtered through a filtration membrane A cooling mechanism that cools the liquid in the rotating unit before the cooling unit, the cooling mechanism being positioned above the rotating unit and communicating with the outside of the chamber; A second external communication hole located outside the external communication hole in the radial direction of the rotating portion and communicating with the outside of the chamber, and the filter body collects the excess liquid drained from the excess liquid drain pipe The first liquid reservoir has an excess liquid around the outlet of the excess liquid drain pipe. The chamber is located with a gap with respect to the water pipe, and the chamber has a second liquid reservoir for collecting the filtrate inside and discharging it to the second external communication hole, and from the second external communication hole to the outside of the chamber. filtrate discharge pipe extends to a diesel particulate method using a centrifugal filter pressure adjusting means for adjusting the pressure of the chamber to the filtrate discharge pipe that is provided. The method includes supplying a liquid to the liquid chamber while rotating the rotating unit, filtering the liquid with a filtration membrane, and discharging the filtrate filtered through the filtration membrane from the drainage unit into the chamber. . Chamber by rotating the rotating unit is a negative pressure, gas flows from the first external communication hole, the chamber by gas from the second external communication hole flows out is ventilated chamber by the pressure adjusting means pressure of Ru is adjusted.

  As the rotating part rotates, an air flow is generated in the chamber, particularly in the side of the rotating part. The air flow causes a negative pressure in the chamber, and gas is introduced into the chamber from the first external communication hole. The airflow flows along the side of the rotating part while being drawn toward the side of the rotating part, and is discharged from the second external communication hole. This air flow generated in the chamber cools the inside of the chamber and cools the inside of the centrifugal filter.

  ADVANTAGE OF THE INVENTION According to this invention, the centrifugal filter which can capture | acquire the microparticles | fine-particles contained in a liquid more correctly, and the microparticle capture | acquisition method can be provided.

It is the schematic which shows the whole structure of the microparticles | fine-particles capture apparatus of this invention. It is a schematic sectional drawing of the centrifugal filter of this invention. It is an enlarged view of the A section of FIG.

  The fine particle capturing apparatus of the present invention can be suitably used for capturing fine particles contained in pure water or ultrapure water. The present invention is also applicable to capturing fine particles contained in liquids other than pure water or ultrapure water. In the following description, pure water or ultrapure water or other liquid is referred to as “liquid”.

  FIG. 1 is a schematic view showing the overall configuration of a particulate trap 1 of the present invention. The particulate trap 1 has a centrifugal filter 2. The centrifugal filter 2 receives a liquid containing fine particles, and captures the fine particles contained in the liquid with a filtration membrane provided in the centrifugal filter 2. The fine particle capturing apparatus 1 has a liquid supply pipe 3 for supplying a liquid to the centrifugal filter 2. The liquid supply pipe 3 is connected to a process pipe 4 through which liquid flows. A connection portion between the process pipe 4 and the liquid supply pipe 3 constitutes a sampling point 5. The branch pipe 6 branches from the liquid supply pipe 3 at the branch point 8. A drain port 9 is formed at the tip of the branch pipe 6, and the liquid is discharged from the drain port 9 to the outside of the particulate trap 1. Accordingly, the liquid can continuously flow through the liquid supply pipe 3 and the branch pipe 6. The liquid supply pipe 3 is connected to the centrifugal filter 2 on the downstream side of the branch point 8. The liquid is supplied from the sampling point 5 to the liquid supply pipe 3, and a part of the liquid flows into the centrifugal filter 2, and the fine particles in the liquid are captured. The remaining liquid enters the branch pipe 6 and is discharged from the drain port 9. A section from the sampling point 5 to the branch point 8 of the liquid supply pipe 3 is called an upstream liquid supply pipe 3a, and a section from the branch point 8 of the liquid supply pipe 3 to the inlet of the centrifugal filter 2 is a downstream liquid supply pipe 3b. That's it.

  The upstream liquid supply pipe 3 a has a stop valve 10 on the downstream side of the sampling point 5. In the present embodiment, the liquid is sampled continuously for a certain period of time, and then the filtration membrane 26 mounted inside the centrifugal filter 2 is taken out to detect the fine particles. Accordingly, the stop valve 10 is opened during the sampling of the liquid, and the stop valve 10 is closed when the sampling of the liquid is completed.

  The upstream liquid supply pipe 3 a has a pressure reducing means 11 between the stop valve 10 and the branch point 8. The pressure reducing means 11 has a flow path constricted with respect to the upstream side liquid supply pipe 3a, and depressurizes the liquid by a throttling effect and friction loss. As the decompression means 11, a conduit having no movable part is preferably used. When a valve such as a needle valve is used as the pressure reducing means, fine particles such as metal powder are likely to be generated at the sliding portion. The fine particles generated at the sliding portion are mixed in the liquid, and cannot be distinguished from the fine particles contained in the liquid at the sampling point 5. Accordingly, it is difficult to capture only the fine particles contained in the liquid at the sampling point 5 with the centrifugal filter 2. Since fine particles are unlikely to be generated in the pipe line having no moving part, the centrifugal filter 2 can capture only the fine particles contained in the liquid at the sampling point 5.

  The decompression means 11 preferably uses a pipe having a narrow channel such as an orifice, and a capillary tube (capillary) is particularly preferably used. In order to prevent a rapid pressure drop, the capillary tube may be wound a plurality of times as shown. This makes it easy to secure the channel length, and abrupt changes in the channel cross-sectional area can be avoided. In order to suppress the generation of fine particles, a capillary tube having a wetted part made of PFA (perfluoroalkyl vinyl ether resin) can be particularly preferably used. Such a capillary tube may be coated with PFA on the liquid contact portion.

  A flow rate adjusting mechanism 12 is provided on the branch pipe 6. The flow rate adjusting mechanism 12 is preferably a valve. By adjusting the flow rate of the liquid flowing through the branch pipe 6 with the flow rate adjusting mechanism 12, the flow rate of the liquid flowing through the downstream liquid supply pipe 3b can be adjusted. This is because it is necessary to control the flow rate of the liquid supplied to the centrifugal filter 2 as described later.

  The downstream liquid supply pipe 3 b has an ultrasonic flow meter 13. The ultrasonic flow meter 13 is provided downstream of the branch point 8 of the liquid supply pipe 3. The ultrasonic flow meter 13 has no parts protruding into the flow path, and can suppress the generation of fine particles. In order to further suppress the generation of fine particles, the wetted part is made of PFA.

  Referring to FIG. 2, the centrifugal filter 2 includes a filter body 15 having a rotating unit 14 and a chamber 16 that houses the filter body 15. The rotating unit 14 can rotate around the rotation center axis C. FIG. 3 is an enlarged cross-sectional view of a portion A in FIG. The rotating portion 14 of the filter body 15 includes a casing 18, a casing cover 19 that covers the upper opening of the casing 18, an inner member 23, an outer member 24, a cartridge 25, and a filtration membrane 26. A connecting rod 20 coaxial with the rotation center axis C is connected to the casing 18, and the connecting rod 20 is connected to a motor 21. Accordingly, the rotating unit 14 can rotate at a predetermined number of rotations. The casing 18 and the casing cover 19 define an internal space 22 of the filter body 15.

  An inner member 23, an outer member 24, and a cartridge 25 are provided in the inner space 22. The inner member 23 is fitted in the central protrusion 18 a of the casing 18. A cartridge 25 is provided between the inner member 23 and the outer member 24. A filtration membrane 26 is detachably attached to the cartridge 25. The cartridge 25 defines a liquid chamber 27 into which liquid flows. The liquid chamber 27 constitutes a part of the rotating unit 14. A liquid supply channel 28 extends radially through the cartridge 25 and the inner member 23. An excess liquid drainage channel 29 extends through the cartridge 25 and the inner member 23 in the radial direction above the liquid supply channel 28. Two cartridges 25 are provided at an interval of 180 °, but the number and arrangement thereof are not limited to this.

  An opening 19a is formed at the center of the casing cover 19, and an excess liquid drain pipe 30 extends through the opening 19a. The excess liquid drain pipe 30 extends in the vertical direction along the inner peripheral edge of the inner member 23 coaxially with the rotation center axis C. The surplus liquid drain pipe 30 communicates with the outlet side of the surplus liquid drain flow path 29. A liquid supply pipe 31 extends in the vertical direction coaxially with the rotation center axis C inside the excess liquid drain pipe 30. The liquid supply pipe 31 communicates with the inlet side of the liquid supply flow path 28. The excess liquid drain pipe 30 and the liquid supply pipe 31 form a double pipe coaxial with the rotation center axis C. The lower end 31 a of the liquid supply pipe 31 is located between the outlet of the excess liquid drain passage 29 and the inlet of the liquid supply passage 28, and has a gap between the central protrusion 18 a of the casing 18.

  In the internal space of the chamber 16, a first liquid reservoir 32 that collects excess liquid drained from the excess liquid drain pipe 30 is provided. The first liquid reservoir 32 is an annular member located in the upper part of the chamber 16, specifically, around the outlet of the excess liquid drain pipe 30. The first liquid reservoir 32 is supported by the chamber 16 by a support member (not shown). An annular gap 33 is formed between the first liquid reservoir 32 and the outlet of the excess liquid drain pipe 30. This prevents interference between the excess liquid drain pipe 30 that is a part of the rotating portion 14 and the first liquid reservoir 32 that is a part of the filter main body 15 but does not rotate. . An excess liquid discharge path 34 extends obliquely downward from the radially outer edge of the bottom surface of the first liquid reservoir 32. The surplus liquid discharge path 34 is connected to a surplus liquid discharge pipe 35 that passes through the chamber 16 and extends outside the chamber 16.

  In the internal space of the chamber 16, a second liquid reservoir 36 that collects the filtrate that has passed through the filtration membrane 26 and discharges it to a second external communication hole 40 (described later) is provided. The second liquid reservoir 36 is located on the bottom surface of the chamber 16 and is constituted by the bottom surface of the chamber 16. A filtrate discharge pipe 37 for discharging the filtrate stored in the second liquid reservoir 36 extends obliquely downward from the bottom of the chamber 16. The filtrate discharge pipe 37 extends through the chamber 16 to the outside of the chamber 16. The filtrate discharge pipe 37 is provided with a valve that is a pressure adjusting means 38 and an integrated flow meter 43.

  The chamber 16 is positioned above the rotating unit 14 and communicates with the outside of the chamber 16, and the second external communicating hole 40 is positioned below the rotating unit 14 and communicates with the outside of the chamber 16. And have. These communication holes 39 and 40 constitute a cooling mechanism 44 that cools the liquid in the rotating portion before being filtered by the filtration membrane. The first external communication hole 39 can be provided in the upper lid 16a of the chamber 16, for example. The second external communication hole 40 is provided at the radially outer edge of the bottom surface of the chamber 16. The first external communication hole 39 is located on the inner side in the radial direction with respect to the rotation center axis C with respect to the second external communication hole 40. In other words, the second external communication hole 40 is located on the outer side in the radial direction of the rotating portion 14 than the first external communication hole 39. The number of the first and second external communication holes 39 and 40 is not limited, but it is preferable that the first and second external communication holes 39 and 40 are provided as uniformly and as distributed as possible in order to effectively ventilate the inside of the chamber 16. The first and second external communication holes 39 and 40 can be provided, for example, at four positions every 90 °. The first external communication hole 39 is open to the outside or the atmosphere. The second external communication hole 40 can be opened to the open air or open to the atmosphere by opening the valve 38, and is open to the open air or open to the atmosphere while the centrifugal filter 2 is in operation.

  The centrifugal filter 2 operates as follows. First, the motor 21 is activated to rotate the rotating unit 14. When the stop valve 10 is opened, the liquid flows from the sampling point 5 into the upstream liquid supply pipe 3a, and a part thereof flows into the downstream liquid supply pipe 3b through the branch point 8. The liquid is supplied vertically downward by a liquid supply pipe 31 connected to the downstream liquid supply pipe 3b, and reaches the upper surface of the central projection 18a of the rotating casing 18. The liquid flows into the liquid supply passages 28 on both sides by centrifugal force and is supplied to the liquid chamber 27. The liquid is pressed against the filtration membrane 26 by centrifugal force and filtered through the filtration membrane 26. The liquid becomes a filtrate, reaches the radially outer space 41 of the filtration membrane 26, and is discharged from the drainage portion 42 formed in the outer member 24 and the casing 18. The filtrate falls in the chamber 16 and reaches the second liquid reservoir 36. The filtrate is guided to the filtrate discharge pipe 37 through the second external communication hole 40. The valve 38 of the filtrate discharge pipe 37 is opened during the operation of the centrifugal filter 2, and the filtrate is discharged out of the system through the filtrate discharge pipe 37. The integrated flow rate of the filtrate is measured by the integrated flow meter 43 of the filtrate discharge pipe 37.

  Due to the pressure loss of the filtration membrane 26, most of the liquid flows into the excess liquid drainage channel 29 as an excess liquid. When the surplus liquid reaches the outlet of the surplus liquid drainage channel 29, the surplus liquid rises along the inner wall surface of the rotating surplus liquid drainage pipe 30. When the upper end of the excess liquid drain pipe 30 is reached, the excess liquid is scattered radially outward by centrifugal force and is collected in the first liquid reservoir 32. The recovered surplus liquid is discharged outside the chamber 16 through the surplus liquid discharge path 34 and the surplus liquid discharge pipe 35.

  After operating the centrifugal filter 2 for a predetermined time, the operation of the centrifugal filter 2 is stopped, the stop valve 10 is closed, and the filtration membrane 26 is taken out. Specifically, the upper cover 16 a of the chamber 16, the liquid supply pipe 31, the excess liquid drain pipe 30 and the casing cover 19 are removed, and the outer member 24, the inner member 23 and the cartridge 25 are taken out from the inner space 22 of the casing 18. The filtration membrane 26 is removed from the cartridge 25, and the number of particles captured by the filtration membrane 26, the particle size, and the like are observed with a particle detection device such as an optical microscope or a scanning electron microscope. Based on the amount of the filtrate measured by the integrating flow meter 43, the number of fine particles contained in the liquid per unit volume, the particle size distribution, and the like can be obtained. The fine particle capturing device 1 and the fine particle detecting device for detecting particles captured by the filtration membrane 26 of the centrifugal filter 2 constitute the fine particle detection system of the present invention.

  As described above, the first external communication hole 39 is provided at a position above the rotating portion 14 of the chamber 16, and is located at a position below the rotating portion 14 of the chamber 16 and radially outside the first external communication hole 39. A second external communication hole 40 is provided. The liquid chamber 27 of the centrifugal filter 2 gradually increases in temperature due to factors such as heat generation of the motor 21 and a bearing (not shown), frictional heat between the rotating portion 14 rotating at high speed and the air in the chamber 16. When the temperature rises, the inner wall of the cartridge 25, that is, the liquid contact portion of the member constituting the centrifugal filter such as the wall surface of the liquid chamber 27 is easily eluted. When viable bacteria are contained in the liquid, the viable bacteria may adhere to the filtration membrane 26 and grow. Since these phenomena deteriorate the detection accuracy of the fine particles, it is desirable to keep the temperature of the liquid chamber 27 as constant as possible. In the present embodiment, air is introduced into the chamber 16 from the first external communication hole 39, and air is discharged from the second external communication hole 40, whereby a ventilation flow is formed in the chamber 16. As a result, the chamber 16 is cooled, and an increase in the temperature of the liquid chamber 27 can be suppressed.

  When the rotating unit 14 rotates, an air flow from the radially inner side to the radially outer side with respect to the rotation center axis C is formed near the rotating unit 14 in the chamber 16. Due to this air flow, the inside of the chamber has a higher negative pressure on the inner side in the radial direction with respect to the rotation center axis C and a lower negative pressure on the outer side in the radial direction. Since the first external communication hole 39 is located on the radially inner side of the rotating portion 14 with respect to the second external communication hole 40, the outside air flows in from the first external communication hole 39 having a low pressure, and the pressure is high. It flows out from the second external communication hole 40. By this air flow, the air in the chamber 16 is always replaced with the external air, and the internal space of the chamber 16 is ventilated. Since the air flow is generated by natural ventilation, it is not necessary to use a pump to form the air flow, and it is not necessary to use compressed air. For this reason, a desired cooling effect can be obtained with a simple configuration.

  In other embodiments, a cooling gas other than air, such as nitrogen gas, may be introduced into the chamber 16. Specifically, a nitrogen gas supply pipe is connected to the first external communication hole 39, and nitrogen gas is supplied into the chamber 16 from the nitrogen gas tank through the supply pipe. Also in this case, since the pressure in the chamber 16 is negative, it is not necessary to use a high-pressure gas. When the internal parts of the centrifugal filter 2 are made of metal, corrosion may occur in these parts due to oxygen contained in the air. In particular, the central protrusion 18 a of the casing 18 is likely to be corroded by contact with the air descending in the excess liquid drain pipe 30. By introducing an inert gas such as nitrogen gas into the chamber 16, the chamber 16 can be cooled while preventing corrosion of internal components.

  In the centrifugal filter 2, it is necessary to discharge the excess liquid without mixing it with the filtrate. Most of the liquid supplied to the centrifugal filter 2 is a surplus liquid, and only a small part becomes the filtrate. For this reason, only by mixing a small amount of excess liquid with the filtrate, the flow rate of the filtrate cannot be accurately measured by the integrating flow meter 43, and the calculation accuracy of the fine particle concentration decreases.

  Mixing of the excess liquid and the filtrate occurs when the excess liquid is not discharged normally. The cause is leakage of excess liquid from the excess liquid drain pipe 30. Since the rotating unit 14 rotates in the chamber 16, the pressure in the chamber 16 is not uniform, and a complicated pressure distribution is formed in the chamber 16. In particular, when natural ventilation is performed by the first external communication hole 39 and the second external communication hole 40, a complicated air flow is generated in the chamber 16. Further, in order to measure the amount of the filtrate more accurately, a step is provided at the bottom of the chamber 16 so that the filtrate can easily collect in the second external communication hole 39. The airflow is disturbed. The surplus liquid discharged from the surplus liquid drain pipe 30 does not reach the first liquid reservoir 32 due to centrifugal force depending on the state of the airflow, but from the gap 33 between the first liquid reservoir 32 and the surplus liquid drain pipe 30. It may fall and be collected in the second reservoir 36 at the bottom of the chamber 16.

  In the present embodiment, by adjusting the opening degree of the pressure adjusting means 38, the pressure distribution in the chamber 16 and the state of the airflow can be adjusted, and mixing of excess liquid and filtrate can be prevented. As described above, the air flow in the chamber 16 is disturbed only by modifying the inside of the filter. In order for the excess liquid discharged from the excess liquid drain pipe 30 to reach the first liquid reservoir 32 by centrifugal force, the air flow in the chamber needs to have an appropriate strength. Since the state of the airflow depends on the internal structure of the filter, even if the airflow is too strong or too weak, the airflow falls from the gap 33 between the first liquid reservoir 32 and the excess liquid drain pipe 30, and the chamber 16 May be collected in the second liquid reservoir 36 at the bottom of the tank. When the air flow is too strong, the opening of the pressure adjusting means 38 is narrowed to weaken the air flow toward the filtrate drainage pipe 37, and when the airflow is too weak, the opening of the pressure adjusting means 38 is increased toward the filtrate drainage pipe 37. Increase airflow.

  In order to suppress the mixing of the excess liquid and the filtrate, it is important to control the amount of the excess liquid. For this purpose, it is necessary to limit the flow rate of the liquid passing through the liquid supply pipe 3. Since the flow rate is proportional to the pressure, when the liquid supplied at the sampling point 5 has a high pressure, the flow rate of the liquid supplied to the centrifugal filter 2 increases.

  In the present embodiment, the flow rate of the liquid supplied to the centrifugal filter 2 can be limited by the decompression means 11 (capillary tube) of the liquid supply pipe 3. In facilities that handle pure water or ultrapure water, the pressure of pure water or ultrapure water (the pressure at the sampling point 5) is often 0.2 to 0.3 MPa, but may be about 0.7 MPa. . Therefore, the flow rate of the liquid supplied to the centrifugal filter 2 can be appropriately controlled by adjusting the inner diameter and length of the capillary tube according to the pressure at the sampling point 5. If the pressure at the sampling point 5 is sufficiently low, the decompression means 11 can be omitted.

  In order to ensure the calculation accuracy of the fine particle concentration, it is important not only to control the flow rate of the liquid to be supplied, but also to prevent the generation of excessive fine particles. In order to control the flow rate, the simplest method is to use a valve as the pressure reducing means 11 of the liquid supply pipe 3. However, the valve has a sliding portion, and there is a possibility that fine particles generated by the sliding are mixed into the liquid. In order to accurately detect the fine particle concentration, it is necessary to capture only the fine particles contained in the sampling point 5 with the centrifugal filter 2. In this embodiment, since the decompression means 11 is constituted by a capillary tube, generation of fine particles can be suppressed.

  As described above, for example, a filtration membrane that captures nanometer-order fine particles has fine pores, and there is very little water passing through the filtration membrane, and most of it is an excess liquid. Therefore, the balance between the amount of excess liquid stored in the first liquid reservoir 32 and the amount of excess liquid discharged from the excess liquid discharge path 34 is lost, and the excess liquid overflows from the first liquid reservoir 32. In some cases, the liquid may be collected in the second liquid reservoir 36 at the bottom of the chamber 16. Therefore, it is important to control the flow rate of the liquid flowing through the downstream side liquid supply pipe 3b. In order to control the flow rate of the liquid more accurately, the particulate capturing device 1 of the present embodiment has a branch pipe 6 provided with a flow rate adjusting mechanism 12. The flow rate ratio between the liquid flowing in the downstream liquid supply pipe 3 b and the liquid flowing in the branch pipe 6 can be accurately controlled by the flow rate adjusting mechanism 12. As described above, the flow rate adjusting mechanism 12 is preferably a valve. Since the fine particles that may be generated in the flow rate adjusting mechanism 12 are directed to the discharge port 9 along the flow in the branch pipe 6, the possibility of backflow to the branch point 8 of the liquid supply pipe 3 and the branch pipe 6 is low. Therefore, it is possible to supply a desired flow rate of liquid to the downstream side liquid supply pipe 3b and to suppress the inflow of unnecessary fine particles that may be generated by the flow rate adjusting mechanism 12 into the centrifugal filter 2. Since the flow rate adjustment mechanism 12 can use a general flow rate adjustment valve, the cost can be suppressed.

  The branch pipe 6 provided with the drain port 9 prevents the liquid from staying in the particulate trap 1. Since the water flowing through the branch pipe 6 is continuously discharged from the drain port 9, the liquid in the particulate trap 1 can always be kept close to the sampling point 5.

  The flow rate of the liquid supplied to the centrifugal filter 2 can be controlled more accurately by the combination of the ultrasonic flow meter 13 and the flow rate adjusting mechanism 12. That is, the flow rate of the liquid supplied to the centrifugal filter 2 is measured by the ultrasonic flow meter 13, and the desired flow rate is stably maintained by adjusting the opening of the flow rate adjusting mechanism 12 according to the measured value. be able to. Since the wetted part of the ultrasonic flowmeter 13 is coated with PFA, the generation of extra fine particles is also suppressed.

  In the above embodiment, the cooling mechanism 44 is provided with the first external communication hole 39 and the second external communication hole 40 in the chamber 16 as the cooling mechanism 44, but is not limited to the above embodiment as long as the filtrate can be cooled. For example, a centrifugal filter can be mounted in a cooler capable of controlling the temperature to cool the centrifugal filter itself, and the filtrate can be indirectly cooled. Alternatively, the filtrate can be directly cooled by a heat exchanger in which cold water is circulated. Alternatively, the filtrate can be indirectly cooled by providing a cold water source outside the chamber and providing a pipe connected to the cold water source in the chamber.

DESCRIPTION OF SYMBOLS 1 Fine particle capture device 2 Centrifugal filter 3 Liquid supply piping 5 Sampling point 6 Branch piping 11 Pressure reducing means 12 Flow rate adjustment mechanism 13 Ultrasonic flow meter 14 Rotating part 15 Filter body 16 Chamber 18 Casing 26 Filtration membrane 27 Liquid chamber 28 Liquid supply Flow path 29 Excess liquid drain flow path 30 Surplus liquid drain pipe 31 Liquid supply pipe 32 First liquid reservoir 36 Second liquid reservoir 38 Pressure adjusting means 39 First external communication hole 40 Second external communication hole 44 Cooling mechanism C Rotation center axis

Claims (8)

A filter body having a rotating part, and a chamber for housing the filter body,
The rotating part is arranged coaxially with the rotation center axis of the liquid chamber, a filtration membrane detachably provided in the liquid chamber, a drainage unit for discharging the filtrate filtered by the filtration membrane, and the rotation center axis of the rotating unit. And a surplus liquid drain pipe for draining surplus liquid in the liquid chamber ,
Further have a cooling mechanism for cooling the liquid in the rotating part before being filtered through the filtration membrane,
The cooling mechanism includes a first external communication hole that is located above the rotation unit and communicates with the outside of the chamber, and is located below the rotation unit and outside the first external communication hole in the radial direction of the rotation unit. A second external communication hole located at a position communicating with the outside of the chamber,
The filter body has a first liquid reservoir for recovering the excess liquid drained from the excess liquid drain pipe, and the first liquid reservoir is disposed around the outlet of the excess liquid drain pipe. It is located with a gap to the liquid drain pipe,
The chamber has a second liquid reservoir that collects the filtrate inside and discharges it to the second external communication hole, and a filtrate discharge pipe extends from the second external communication hole to the outside of the chamber. and has, that has a pressure regulating means is provided for adjusting the pressure of the chamber to the filtrate discharge pipe, a centrifugal filter. The centrifugal filter according to claim 1 , wherein the first and second external communication holes are opened to the outside air during operation of the centrifugal filter. The centrifugal filter according to claim 1 or 2 ,
A liquid supply pipe for supplying a liquid to the centrifugal filter;
A branch pipe branched from the liquid supply pipe at a branch point, and the liquid can be continuously circulated;
And a flow rate adjusting mechanism provided on the branch pipe. The fine particle capturing apparatus according to claim 3 , wherein the liquid supply pipe has a pressure reducing unit upstream of the branch point. The particulate trapping device according to claim 3 or 4 , wherein the liquid supply pipe has an ultrasonic flowmeter downstream of the branch point. A filter body having a rotating part; and a chamber for housing the filter body, wherein the rotating part includes a liquid chamber, a filtration membrane detachably provided in the liquid chamber, and the filtration membrane. A drainage part that drains the filtrate that has permeated, and a surplus liquid drainage pipe that is arranged coaxially with the rotation center axis of the rotating part and drains surplus liquid in the liquid chamber, and is filtered by the filtration membrane The cooling mechanism further cools the liquid in the previous rotating part, and the cooling mechanism is located above the rotating part and communicates with the outside of the chamber, and below the rotating part. And a second external communication hole located outside the first external communication hole in the radial direction of the rotating portion and communicating with the outside of the chamber, and the filter body includes the excess liquid drain pipe A first reservoir for collecting the excess liquid drained from the front, The first liquid reservoir is located around the outlet of the surplus liquid drain pipe with a gap with respect to the surplus liquid drain pipe, and the chamber collects the filtrate in the second and communicates with the second external communication pipe. A pressure adjustment for adjusting a pressure of the chamber to the filtrate discharge pipe having a second liquid reservoir for discharging into the hole, a filtrate discharge pipe extending from the second external communication hole to the outside of the chamber; means a diesel particulate method using a centrifugal filter that has been provided with,
While rotating the rotating part, the liquid is supplied to the liquid chamber, the liquid is filtered by the filtration membrane, and the filtrate filtered by the filtration membrane is discharged from the drainage part into the chamber. And
Said chamber is a negative pressure by rotating the rotary part, before SL gas flows from the first outer communication hole, the previous SL said chamber by the gas from the second outer communication hole to flow out ventilated, pressure in the chamber Ru is adjusted by the pressure adjusting means, the diesel particulate methods. A fine particle detection method comprising detecting fine particles captured by the filtration membrane by the fine particle capture method according to claim 6 . The fine particle detection method according to claim 7 , wherein the liquid is pure water or ultrapure water.

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