JP2012026792A - Device and method for detecting particulate in fluid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately and efficiently detect particulates included in a high-pressure fluid.SOLUTION: A device for detecting particulates in a fluid includes: a fluid supply part 13 to which a fluid to be measured is supplied; a flow channel constricted tube 14 which has one end connected to the fluid supply part 13 and has a constricted flow channel relative to the fluid supply part 13; and particulate detection means 15 which is connected to the other end of the flow channel constricted tube 14 and detects particulates flowing in from the flow channel constricted tube 14. A method for detecting particulates in the fluid includes: a step of supplying the fluid to be measured to the fluid supply part 13; a step of reducing pressure of the fluid to be measured, by causing the supplied fluid to be measured to pass the flow channel constricted tube 14 having the constricted flow channel relative to the fluid supply part 13; and a step of detecting particulates included in the fluid to be measured of which the pressure is reduced.

Description

  The present invention relates to an apparatus and a method for detecting particulates in a fluid, and more particularly to an apparatus and a method for detecting particulates contained in high-pressure carbon dioxide in a supercritical state or a liquid phase.

  Various methods for detecting particulates present in a fluid are known. For example, in the direct microscopic method (hereinafter referred to as direct test method), fine particles captured on the filtration membrane when the water to be measured is filtered through the filtration membrane are detected using an optical microscope or a scanning electron microscope ( Non-patent document 1). In the direct test method, the pressure of the fluid to be measured directly acts on the filtration membrane and the container (filter holder) for holding it, so if the fluid to be measured has a high pressure, the filtration membrane and the filter holder will exceed the pressure limit. End up. For this reason, it is difficult to introduce a high-pressure fluid as it is. On the other hand, Patent Document 1 discloses a technique for performing a direct inspection method with a high-pressure fluid. According to this method, two branch pipes are provided in the pipe through which the high-pressure fluid flows, and these branch pipes are connected to both sides of the filter holder. Since the filter receives the pressure of the high-pressure fluid from both sides, the pressure is canceled out and a large pressure is prevented from being applied to the filter and the filter holder.

  As another method, a particle counter method (PC method) that detects fine particles by using scattering of laser light is known (Patent Document 2). The fluid to be measured is passed through a light-transmitting hollow member called a flow cell. Laser light is irradiated from one side of the flow cell, and a photoelectric converter installed on the opposite side across the flow cell detects the scattered light of the laser light and measures the particle size and number of fine particles. Fine particles in an aerosol state may be introduced into the flow cell (dry PC method), or a liquid containing fine particles may be introduced (wet PC method). The PC method can be evaluated online, and quick measurement is easy. However, since the flow cell uses a special material such as quartz or sapphire, it is difficult to increase the pressure resistance.

  As a method similar to the PC method, a method called a condensed particle counter method (CPC method) is also known (Patent Documents 3 and 4). In this method, alcohol vapor and water vapor are condensed and grown around fine particles using fine particles as nuclei. The condensed and grown aerosol is introduced into the flow cell, and the number of aerosols is measured by a condensed particle counter. There is a problem similar to the PC method regarding the pressure resistance performance of the flow cell. Although it is a technique related to the PC method, Patent Document 5 discloses a flow cell in which the cross-sectional shape of the flow path is configured with a curved surface in order to improve the pressure resistance performance of the flow cell.

JP 2009-52981 A Patent No. 3530078 JP 2000-180342 A JP 2007-57532 A JP 2008-224342 A

Japanese Industrial Standard K0554-1995 “Fine particle detection method in ultrapure water”

  If the technique of patent document 1 is used for the direct inspection method, a high-pressure processed fluid can be handled. However, since it is necessary to remove the filtration membrane for each measurement, the direct inspection method is not suitable for continuous measurement, and rapid measurement is difficult. The PC method and the CPC method require high reliability in the pressure resistance of the flow cell, and there is a limit to the applicable pressure.

  On the other hand, if the fluid is depressurized and measured, the above problem can be solved. A known member such as a pressure reducing valve can be used to decompress the fluid. However, since such a member generates fine particles such as metal powder with the operation, high measurement accuracy cannot be realized.

  An object of the present invention is to provide an in-fluid particle detection device and a detection method that can detect particles contained in a high-pressure fluid with high accuracy and efficiency.

  According to one embodiment of the present invention, the particulate detection device in the fluid has a fluid supply unit to which the fluid to be measured is supplied, one end connected to the fluid supply unit, and the flow path is narrowed with respect to the fluid supply unit A flow path reduction pipe, and a fine particle detection means connected to the other end of the flow path reduction pipe for detecting the fine particles flowing from the flow path reduction pipe.

  The flow path reducing tube is narrowed with respect to the fluid supply unit. For this reason, the flow path reducing tube can depressurize the fluid to be measured by the throttling effect, and can gradually reduce the pressure of the fluid to be measured by the friction loss between the inner wall of the flow path reducing tube and the fluid to be measured. Since the reduced pressure fluid is introduced into the particulate detection means, the problem of pressure resistance of the members hardly occurs, and the detection means that has been conventionally applied to the low pressure fluid can be used as it is. Moreover, since the flow path reduction tube has no moving parts and can gradually reduce the pressure, there is no risk of generation of fine particles such as metal powder due to operation, and even a small amount of fine particles can be measured with high accuracy. it can. Since the fluid to be measured supplied from the fluid supply unit can be continuously introduced into the particulate detection means via the flow path reduction tube, efficient measurement is also possible.

  According to another embodiment of the present invention, a method for detecting particulates in a fluid includes a step of supplying a fluid to be measured by a fluid supply unit, and a flow path of the supplied fluid to be measured is narrowed with respect to the fluid supply unit. The method includes a step of reducing the pressure of the fluid to be measured by passing through the flow path reducing tube, and a step of detecting fine particles contained in the pressure-reduced fluid to be measured.

  As described above, according to the present invention, it is possible to provide an in-fluid particle detection device and a detection method that can detect particles contained in a high-pressure fluid with high accuracy and efficiency.

It is a schematic block diagram of a carbon dioxide supply equipment. It is a schematic block diagram of the microparticle detection apparatus of this invention. It is a schematic diagram which shows the ph diagram of a carbon dioxide. It is a flowchart in an Example. It is a graph which shows the detection result of the number of microparticles | fine-particles of an Example and each comparative example. It is a graph which shows the fluctuation | variation of the detection result at the time of changing a sampling location. It is a graph which shows the fluctuation | variation of the detection result at the time of performing the opening / closing operation | movement of a valve.

Hereinafter, embodiments of the fine particle detection apparatus and measurement method of the present invention will be described with reference to the drawings. The pressure and type of fluid to which the present invention is applied are not limited, but the present invention can be particularly suitably applied to the measurement of fine particles contained in high-pressure supercritical, liquid or gaseous carbon dioxide. For this reason, the following description is performed for supercritical, liquid, or gaseous carbon dioxide. This measurement apparatus can be used by connecting to existing carbon dioxide production equipment or supply equipment. First, an outline of carbon dioxide production equipment or supply equipment will be described. FIG. 1 shows a schematic configuration diagram of a carbon dioxide supply facility 1 as an example. Liquid carbon dioxide is stored in the CO ₂ cylinder 2. Liquid carbon dioxide stored in the CO ₂ cylinder 2 is filtered by the metal gas filter 3 a and introduced into the condenser 4. Carbon dioxide is condensed in the condenser 4 and sent to the CO ₂ tank 5. The carbon dioxide in the CO ₂ tank 5 is once supercooled by the precooler 6 to be liquid carbon dioxide. The reason for supercooling by the precooler 6 is to prevent gaseous carbon dioxide from being generated by the subsequent circulation pump 7. Carbon dioxide is boosted by a circulation pump 7, filtered by a metal gas filter 8, and becomes clean high-pressure liquid carbon dioxide, which is sent to a use point (not shown) through a valve 12d. The high-pressure liquid carbon dioxide that has not been used is expanded on the outlet side of the pressure-holding valve 9 and further converted into a gas phase by the evaporator 10. This is to increase the particle removal efficiency in the latter metal gas filter 3b. In this manner, the carbon dioxide supply facility is configured to supply high-pressure liquid carbon dioxide to the use point as necessary while carbon dioxide circulates along the circulation loop. For the supercritical carbon dioxide supply equipment, except for heating the liquid carbon dioxide to a temperature above the critical temperature,
It can be set as the same structure.

The particle detector 11 can be provided at any position on the line of the carbon dioxide supply facility 1. The illustrated take-out points P1 to P3 are an outlet portion of the metal gas filter 8, a bottom portion of the CO ₂ tank 5, and an outlet portion of the metal gas filter 3b. The particle detector 11 is connected to the carbon dioxide supply facility 1 through valves 12a to 12c. The fine particle detector 11 detects fine particles contained in carbon dioxide flowing from the extraction points P1 to P3. Although there is no restriction | limiting in the pressure of the carbon dioxide in the extraction points P1-P3, According to this invention, the high pressure carbon dioxide especially the pressure of 1 Mpa or more can be taken out.

  FIG. 2A shows a schematic configuration diagram of the particle detector 11. The particle detector 11 includes, for example, a fluid supply unit 13 configured by a pipe having a predetermined inner diameter to which a fluid to be measured is supplied, a flow path reducing tube 14 that is a decompression unit, and a particle detector 15. Yes. The broken line in the figure schematically shows the flow of carbon dioxide.

  One end of the fluid supply unit 13 is connected to the carbon dioxide supply facility 1 via the valves 12 a to 12 c, and the other end is connected to the flow path reducing tube 14. Supercritical, liquid or gaseous high-pressure carbon dioxide is continuously supplied to the flow path reduction tube 14 through the fluid supply unit 13. Although the fluid supply unit 13 is illustrated as a pipe in FIG. 2A, a pipe such as a steel pipe, a high-pressure tube, a joint, or the like can be selected depending on the status of the valves 12a to 12c (measurement points). The fluid supply unit 13 shown in FIG. 2A may be eliminated, and the valves 12a to 12c may be disposed adjacent to the flow path reducing tube 14 so that the valves 12a to 12c function as the fluid supply unit. Depending on the situation, the flow path reduction pipe 14 may be directly connected to the circulation loop (mother pipe) of the carbon dioxide supply facility 1 via a joint or the like, and the circulation loop (mother pipe) itself may function as a fluid supply unit. In any case, the flow path reducing tube 14 only needs to be narrowed with respect to the fluid supply unit 13. Further, a pressure holding valve (not shown) may be provided, and a constant flow rate of high pressure carbon dioxide may be supplied to the flow path reducing pipe 14 by adjusting the pressure holding valve.

  One end 14 a of the flow path reducing tube 14 is connected to the fluid supply unit 13, and the other end 14 b of the flow path reducing tube 14 is connected to the particulate detection means 15. The connection method between the flow path reducing tube 14 and the particulate detection means 15 is not particularly limited and can be connected via a pipe, a joint, a valve, or the like, but from the viewpoint of temperature control described later, It is preferable that the distance from the particulate detection means 15 is as short as possible, and that there are few joints, valves, etc. from the viewpoint of preventing unnecessary particulate generation. As will be described in the embodiment, the flow path reducing pipe 14 and the particulate detection means 15 may be connected via a branch pipe for discharging a part of carbon dioxide to the atmosphere.

  The flow path reducing tube 14 has a flow path narrowed with respect to the fluid supply unit 13, and depressurizes supercritical, liquid, or gaseous carbon dioxide by a throttling effect and friction loss. The flow path reducing tube 14 is not particularly limited as long as the fluid to be measured can be depressurized by such a throttling effect and friction loss. For example, a metal tube or a capillary tube can be used. The flow path reduction tube 14 can be made of various types of stainless steel, tungsten, kovar, titanium, brass, phosphor bronze, phosphorous deoxidized copper, etc., but cleanliness in the measurement of fine particles in the fluid (ease of surface treatment in the tube) Stainless steel is preferred from the viewpoint of ease of processing.

  The channel area and length of the channel reduction tube 14 can be set as appropriate according to the supply pressure of high-pressure carbon dioxide, the pressure after decompression, and the required flow rate. In the case where the flow path reducing tube 14 is constituted by a pipe having a circular cross section, the inner diameter is preferably 100 to 1000 μm, more preferably 200 to 500 μm. The length of the flow path reducing tube 14 is preferably 0.1 to 500 m, more preferably 0.5 to 100 m. Since the flow path reducing pipe 14 gradually reduces the pressure of the high-pressure carbon dioxide without causing a rapid pressure drop, the pipe length is very long compared to the inner diameter. In the case where the flow path reducing pipe 14 is constituted by a pipe having a circular cross section, in the above example, the ratio of the pipe length to the inner diameter is 10 or more and 5000000 or less. In the case where the flow path reducing pipe 14 is constituted by a pipe having a circular cross section, a more preferable ratio of the pipe length to the inner diameter is 100 or more and 500,000 or less. For this reason, it may be difficult to provide linearly from a viewpoint of installation space. In that case, the installation space can be reduced by deforming by an appropriate method such as bending in a spiral shape or winding in a circular shape (see FIG. 2B).

  Heaters (heating means) 16 a and 16 b for heating the flow path reducing tube 14 are provided in the vicinity of both ends 14 a and 14 b of the flow path reducing tube 14. The installation positions of the heaters 16a and 16b are not limited to this, and may be provided only in the vicinity of the inlet or the outlet of the flow path reducing pipe 14, or may be provided in other positions. The types of the heaters 16a and 16b are not particularly limited, and may be, for example, a coil-shaped heater around which the flow path reducing tube 14 is wound, a ribbon heater (ribbon-shaped heater), or the like. However, as shown in FIG. 2 (b), when the flow path reducing tube 24 bundled in a circle is used, it is preferable to provide the heaters 16a and 16b at least in the unfolded state with the inlet side and the outlet side unfolded. . Moreover, you may heat the whole channel reduction pipe | tube bundled with a heater.

  Thermometers 17a and 17b for measuring the temperature of carbon dioxide are installed adjacent to the heaters 16a and 16b. The heaters 16a and 16b and the thermometers 17a and 17b are connected to a control device 18 that adjusts the temperature of the fluid. For example, thermocouples can be used as the thermometers 17a and 17b. The temperature measuring units of the thermometers 17a and 17b may be inside the flow path reducing tube 14, but are preferably provided on the outer surface of the flow path reducing tube 14 in order to prevent generation of fine particles. The control device 18 controls the amount of heat generated by the heaters 16a and 16b according to the measurement results of the thermometers 17a and 17b. Specifically, the control device 18 detects the particulate matter in the gas phase containing a very small amount of solid phase or liquid phase so that carbon dioxide does not significantly affect the detection of the particulate matter from the flow path reduction tube 14 or the particulate matter. The carbon dioxide flowing inside the flow path reducing tube 14 is maintained at a predetermined temperature so as to flow into the means 15.

  When carbon dioxide moves inside the flow path reducing tube 14 while reducing the pressure, it can be considered that carbon dioxide approximately changes in isoenthalpy. FIG. 3 schematically shows a ph diagram of carbon dioxide. The horizontal axis represents enthalpy (h), and the vertical axis represents pressure (p). A broken line shows an isotherm, and the temperature is higher on the right side and lower on the left side. For example, when carbon dioxide in a supercritical state is introduced into the flow path reduction tube 14 at point A, the state of carbon dioxide changes from point A to point B and flows out of the flow path reduction tube 14 as gas phase carbon dioxide. To do. Since gas phase carbon dioxide is supplied to the particulate detection means 15, particulates are detected based on the dry PC method or the CPC method, as will be described later.

  Next, a state where the enthalpy is smaller, that is, a case where carbon dioxide having a temperature lower than the point A is supplied (point C) is considered. When low-temperature carbon dioxide undergoes an isoenthalpy change, depending on the decompression condition, there is a possibility of a gas-solid mixed state (point D "). In the case of carbon dioxide, dry gas that is a solid phase in the case of carbon dioxide Since the solid phase continues to exist even when the pressure is reduced, when carbon dioxide exits the flow path reduction tube 14 and flows into the particulate detection means 15 in a gas-solid mixed state. Therefore, it becomes impossible to distinguish between the solid phase of carbon dioxide and the fine particles that should be detected, so that the heaters 16a and 16b are operated to raise the temperature of carbon dioxide in advance (point E). Enthalpy increases, preventing gas-solid mixing even under reduced pressure (point B '), and carbon dioxide is completely vaporized when dry PC or CPC methods are used to detect particulates. thing Desirable, to heat the carbon dioxide heater 16a, 16b, it is also possible to avoid the gas-liquid mixed state (D 'points).

  The heaters 16a and 16b are intended to heat carbon dioxide so that fine particles are detected in a gas phase. Another object is to keep the temperature of carbon dioxide introduced into the detector constant. Therefore, the heaters 16 a and 16 b are not necessarily provided in the flow path reducing tube 14, and can be provided in the vicinity of the inlet of the particulate detection means 15. However, since the flow path reducing pipe 14 is a pipe and has a simple structure, the heater can be easily installed.

  Further, even if a solid phase or a liquid phase of carbon dioxide is temporarily generated, it may be lost when it is introduced into the fine particle detection means 15. That is, even if carbon dioxide temporarily reaches the D ′ point or the D ″ point, it suffices to finally reach the E ′ point or the E ″ state. However, since a certain amount of time is required for the state change, it is desirable to heat the upstream side of the flow path reduction tube 14 as much as possible in order to avoid a gas-solid mixed state or a gas-liquid mixed state. From such a viewpoint, it is desirable to provide the heater 16a in the vicinity of the inlet 14a of the flow path reduction tube 14, and by heating at an early stage, in a high enthalpy region where a gas-solid mixed state or a gas-liquid mixed state does not occur. Enthalpy changes can be made (D → E → B ′). On the other hand, in order to ensure that carbon dioxide is introduced into the particulate detection means 15 in a gas phase, it is desirable to provide a heater 16b near the outlet 14b of the flow path reduction tube 14, and further, near the inlet 14a and the outlet 14b. The heaters 16a and 16b may be provided at both positions. Thus, the installation positions of the heaters 16a and 16b can be appropriately determined according to the purpose.

  If the inner diameter of the flow path reducing tube 14 is increased, the throttling effect is reduced and the degree of decompression is reduced. Similarly, if the pipe length of the flow path reducing pipe 14 is shortened, the degree of decompression is reduced. Needless to say, the adjustment of the pipe length and flow area (inner diameter) of the flow path reduction tube 14 and the temperature control of the flow path reduction tube 14 by the heaters 16a and 16b can be performed together. Even when the flow path area and length of the flow path reducing pipe 14 are optimized, it is more preferable to control the temperature of the flow path reducing pipe 14 in order to avoid a gas-solid mixed state or a gas-liquid mixed state.

  Since the pressure reducing method using the flow path reducing pipe 14 does not require a mechanically operating part like a conventional pressure reducing valve, there is no generation of fine particles such as metal powder in accordance with the operation, and it is contained in carbon dioxide. Fine particles can be detected with high accuracy. Although it is conceivable to use a filter as another decompression method, since the filter repeats adhesion and separation of fine particles during long-time use, precise measurement is difficult. In contrast, the depressurization method using the flow path reduction tube 14 hardly causes generation of fine particles such as metal powder, which becomes a contamination source (or a cause for increasing the number of blank fine particles) for the fine particle detection means 15, and enables highly accurate measurement. It is. In addition, since the flow path area (inner diameter) and the total length of the flow path reduction tube 14 are adjusted and the temperature is controlled by the heaters 16a and 16b, the temperature is not easily affected by the temperature and pressure conditions at the extraction points P1 to P3. This makes it possible to detect fine particles with high accuracy.

  Another advantage of the flow path reduction pipe 14 is that the heat transfer area is very large due to the long pipe length. For this reason, the degree of freedom in setting the heating range is high, and a wide range in which temperature control is possible can be ensured, so fine temperature control is possible. Since it has a large heat transfer area, carbon dioxide can be maintained in a desired temperature range without necessarily providing a heater depending on the external environment temperature. Since the pressure reducing valves and filters are substantially concentrated at one point, it is difficult to control the temperature precisely. Further, the flow path reducing tube 14 has a simple structure, high reliability, low necessity for maintenance, and is advantageous in terms of cost.

  The fine particle detection means 15 detects fine particles flowing from the flow path reducing tube 14. Supercritical, liquid or gaseous carbon dioxide is in the gas phase after being depressurized by the flow path reduction tube 14, and the fine particles originally contained in the carbon dioxide are present in the gas phase. The gas phase carbon dioxide containing the fine particles is introduced into the fine particle detection means 15, and the fine particles contained in the gas phase carbon dioxide are detected. As such a particle detector, a dry PC method or a CPC method can be used.

  The fine particle detection means 15 by the dry PC method has means for irradiating the fine particles with laser light and means for detecting scattered light of the laser light from the fine particles. In the dry PC method, laser light generated by a semiconductor laser is irradiated to fine particles in a gas phase, and direct scattered light from the fine particles is detected.

  FIG. 2 shows a particulate detection means 15 based on the CPC method. The particulate detection means 15 has a condensation chamber 20 provided with a supply port 20a for a vapor such as alcohol. The fine particles are introduced into a condensation chamber 20 in a supersaturated atmosphere such as alcohol, and vapor such as alcohol condenses and grows with the fine particles as a nucleus. A downstream side of the condensing chamber 20 is a flow cell 21 made of a material that can transmit laser light. On the side surface of the flow cell 21, there are disposed a semiconductor laser 22 that irradiates laser light onto vapor-condensed and grown fine particles, and a photoelectric converter 23 that detects scattered light of laser light from the vapor-condensed and grown fine particles. Yes. The fine particles become aerosols (droplets) condensed and grown by vapor deposition, and the droplets are irradiated with laser light. The particle size of the droplet is increased to a level that can be measured by the light scattering method, and the number (concentration) of fine particles is measured by the light scattering method. For this reason, the CPC method can detect fine particles having a smaller particle diameter than the dry PC method. On the other hand, since the dry PC method directly irradiates fine particles with laser light, the particle size distribution of the fine particles can be obtained.

  In addition, since the flow rate of the fluid decompressed by the flow path reducing tube 14 is increased, an unnecessary load may be applied to the particulate detection means 15. Therefore, as shown in the embodiment, a pump is installed on the downstream side of the particulate detection means 15 to introduce a fluid to be measured having an appropriate flow rate and flow rate into the particulate detection means 15, and the atmosphere upstream of the particulate detection means 15. An opening means may be provided to exhaust the fluid that is not introduced into the particulate detection means 15. The pump may be provided between the particulate detection means 15 and the atmospheric release means, but it is preferable to provide the pump downstream of the particulate detection means 15 because particulates generated from the pump may be introduced into the particulate detection means 15. .

  FIG. 4 shows a flowchart in the embodiment. As the high-pressure fluid, high-pressure carbon dioxide filtered with a metal gas filter (filtration accuracy: 0.003 μm) manufactured by Pureron Japan Co., Ltd. was used. The high-pressure carbon dioxide was continuously supplied to the flow path reducing tube 14 serving as a decompression unit through a fluid supply unit having an inner diameter of 4.35 mm. A branch pipe 19 was provided in the fluid supply part of high-pressure carbon dioxide, and a part of the carbon dioxide was exhausted through the pressure holding valve 20. The set pressure of the pressure holding valve 20 was 9 MPa, and high-pressure carbon dioxide at a constant flow rate (3 g / min) was supplied to the flow path reduction tube 14. The flow path reducing tube 14 was made of SUS316 with a tube diameter of φ200 μm and a tube length of 30 m. The flow path reducing tube 14 was wound in a circular shape of φ48 cm and bundled, and both ends were unwound.

  Heaters 16a and 16b were installed at two locations near the inlet and the outlet of the flow path reducing pipe 14, and the temperatures were controlled so that the temperatures of the outer surfaces of the flow path reducing pipe 14 were 60 ° C and 30 ° C, respectively. Specifically, a ribbon heater having a width of 4 cm and a length of 3 m is prepared as the heater 16a, attached along the part where the flow path reducing pipe 14 is unwound from the start end of the flow path reducing pipe 14, and the remaining part is further connected to the flow path. It was attached to the bundled portion of the reduction tube 14. Similarly, a ribbon heater having a width of 4 cm and a length of 3 m is prepared as the heater 16b, and is attached along the portion where the flow path reducing pipe 14 extends from the vicinity of the exhaust pipe branching portion 27 on the downstream side of the flow path reducing pipe 14. Further, the remaining part was attached to a part connected to the unwound part of the bundled parts of the flow path reducing tube 14. In FIG. 4, the range in which the heaters 16a and 16b are attached is indicated by hatching.

  The number (concentration) of fine particles contained in carbon dioxide decompressed by the flow path reducing tube 14 was measured with a fine particle detection device 15 (CPC3772 manufactured by TSI) using the CPC method. A pump 28 is provided on the downstream side of the particulate detection device 15, and only a constant flow rate (1 L / min) of suctioned carbon dioxide is sucked and introduced into the particulate detection device 15, and the rest is released into the atmosphere from the exhaust pipe branching portion 27. did.

  In Comparative Example 1, a flow restrictor manufactured by Sugiyama Shoji Co., Ltd. was used as the pressure reducing means. In Comparative Example 2, a pressure reducing valve (manufactured by Tescom) was used as the pressure reducing means. In Comparative Example 3, a flow path reducing tube 14 (φ200 μm, 30 m) with a heater, which is the same as the Example, was installed at the subsequent stage of the flow restrictor of Comparative Example 1. The flow restrictors of Comparative Examples 1 and 3 are filters that can remove fine particles having a particle diameter of 2 μm or more. The pressure reducing valve of Comparative Example 2 was provided with a ribbon heater having a width of 4 cm and a length of 3 cm on the outer periphery, and the temperature of the thermocouple installed on the pressure reducing valve was controlled to be 100 ° C. The flow restrictor was controlled so that its external temperature was 100 ° C.

  FIG. 5 shows the results of measuring the number (concentration) of fine particles having a particle size in high-pressure carbon dioxide exceeding 10 nm in Examples and Comparative Examples. 5 (a) shows the measurement results of Comparative Examples 1 and 2, FIG. 5 (b) shows the measurement results of Comparative Example 3, and FIG. 5 (c) shows the measurement results of the Examples. The number of particles (number of detected particles per 1 cc of gas). The vertical axes in FIGS. 5B and 5C are the same scale, but the vertical axis in FIG. 5A is 1000 times larger than the scales in FIGS. 5B and 5C.

  In Comparative Example 2, it is considered that fine particles such as metal powder are generated by the operation of the pressure reducing valve, and it is difficult to obtain practical measurement accuracy when a fluid having a low concentration of fine particles is to be measured. In Comparative Example 1, the number of detected particles was smaller than that in Comparative Example 2, but much more fine particles were detected than in Examples described later. Comparative Example 1 is considered to be affected by fine particles that repeatedly adhere and peel off by the filter. Further, in Comparative Examples 1 and 2, since the temperature control was not sufficient, it is presumed that carbon dioxide partially entered the solid phase or the liquid phase and flowed into the measuring apparatus. In Comparative Example 3, it is considered that carbon dioxide is completely in the gas phase because the flow path reducing tube 14 with the heater of the example is installed after the filter of Comparative Example 1. It can be said that the comparative example 3 extracts only the influence of the fine particles that repeatedly adhere and peel by the filter. In Comparative Examples 1 to 3, fine particles other than the fine particles originally included in the measurement target have an influence on the measurement result, the number of detected particles is high, and the measurement value is not stable.

  On the other hand, in the examples, the number of detected particles was smaller than in each comparative example, and was hardly affected by fine particles other than the fine particles originally contained in the measurement target, and a stable measurement value was obtained.

  Next, in the present Example, the result of having measured the number of fine particles (concentration) exceeding the particle size of 10 nm in the sampling location P2, P3, P1 in a high-pressure carbon dioxide supply apparatus is shown in FIG. Sampling locations P1 to P3 are positions as shown in FIG. A phenomenon was observed in which the number of particles increased transiently when the sampling location was changed, but the number of particles almost matched the sampling position was obtained.

  Furthermore, FIG. 7A shows the result of measuring the number (concentration) of fine particles having a particle diameter of more than 10 nm when the valve 24 is opened and closed at the same sampling location. The valve 24 is provided with a configuration as shown in FIG. 7B in order to see the influence of the opening / closing operation of the valve. A line 25 provided with a valve and a line 26 provided with no valve were configured in parallel, and the valve 24 was opened and closed while supplying carbon dioxide, and the number of fine particles was measured. After the opening / closing operation of the valve, the number of fine particles temporarily increases, and then returns to a steady state again.

  Thus, it was confirmed that the change in the number of fine particles (concentration) when the sampling location was changed or the valve was opened / closed could be continuously monitored.

DESCRIPTION OF SYMBOLS 1 Liquid carbon dioxide production equipment 11 Particulate detection apparatus 13 Fluid supply part 14 Flow path reduction pipe 15 Particulate detection means 16a, 16b Heater (heating means)
17a, 17b Thermometer 18 Control device

Claims (12)

A fluid supply unit to which a fluid to be measured is supplied;
One end is connected to the fluid supply unit, and a flow path reduction tube having a flow path restricted with respect to the fluid supply part,
Fine particle detection means connected to the other end of the flow path reduction tube and detecting fine particles flowing from the flow path reduction tube,
A device for detecting particulates in a fluid.   Heating means for heating the fluid to be measured flowing through the flow path reducing pipe; and a control device for controlling the heating means so that the fluid to be measured flows from the flow path reducing pipe into the fine particle detection means in a gas phase; The fine particle detection device according to claim 1, comprising:   The particulate detection apparatus according to claim 2, wherein the heating unit is provided on at least one of the one end side and the other end side of the flow path reducing tube.   The fine particle detecting means includes means for irradiating the fine particles contained in the vaporized fluid to be measured with laser light, and means for detecting scattered light of the laser light from the fine particles. Item 4. The particle detector according to Item 2 or 3.   The fine particle detection means includes a means for condensing and growing vapor around the fine particles contained in the vaporized fluid to be measured, a means for irradiating the fine particles on which the vapor is condensed and grown, and the vapor. And a means for detecting scattered light of the laser beam from the condensed and grown fine particles.   The particulate detection according to any one of claims 1 to 5, wherein the flow path reducing tube has a circular cross section with an inner diameter in a range of 100 to 1000 µm and a pipe length of 0.1 to 500 m. apparatus.   The particulate detection device according to any one of claims 1 to 5, wherein the flow path reducing tube has a circular cross section, and a ratio of a pipe length to an inner diameter is in a range of 10 or more and 5000000 or less. Supplying a fluid to be measured by a fluid supply unit;
Depressurizing the fluid to be measured by passing the supplied fluid to be measured through a flow path reduction tube having a narrow flow path with respect to the fluid supply unit;
Detecting fine particles contained in the pressure-reduced fluid to be measured;
A method for detecting particulates in a fluid.   The step of reducing the pressure of the fluid to be measured includes heating at least one of the inlet side and the outlet side of the flow path reducing pipe so that the fluid to be measured flows out of the flow path reducing pipe in a gas phase. The fine particle detection method according to claim 8.   The step of depressurizing the fluid to be measured includes adjusting at least one of a flow path area and a pipe length of the flow path reducing pipe so that the measured fluid flows out of the flow path reducing pipe in a gas phase. The fine particle detection method of Claim 8 or 9 containing.   The step of measuring the number of fine particles includes irradiating the fine particles contained in the vaporized fluid to be measured with laser light, or applying the laser light to the fine particles contained in the vaporized fluid to be measured. The fine particle detection method according to any one of claims 8 to 10, comprising irradiating a laser beam in a state where vapor is condensed and grown around the surroundings, and detecting scattered light of the irradiated laser beam.   12. The depressurizing step includes depressurizing a carbon dioxide in a supercritical state or a liquid phase or a gas phase at a pressure of 1 MPa or more to form a gas phase of carbon dioxide at a pressure of less than 1 MPa. 2. The fine particle detection method according to item 1.

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