JP2006118890A - Particle metering system, particle metering method, plant deterioration detecting system and plant deterioration detecting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize the arrangement position of a sensor capable of ensuring a time sufficient to perform the accurate calibration of a particle sensor without lessening the concentration increasing effect of particles captured by a particle capturing means and to obtain an output value not relying on a flow velocity. <P>SOLUTION: A first particle capturing means 11 is provided in the vicinity of or in piping 15 through which a fluid flows, and the particle sensor 12 and a second particle capturing means 28 are arranged in the vicinity of or in the piping 15 on the downstream side of a flow direction 16. The particles 17 present in the fluid is captured for a predetermined time by the first particle capturing means 11 and released to start the capturing of the particles 17 due to the second particle capturing means 28. Thereafter, the calibration of the particle sensor 12 is performed and the number of the particles 17 reaching an observation region 18 is metered by the particle sensor 12. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a technique for measuring the number of particles present in a fluid (gas or liquid). In particular, it is suitable for application to particle measurement in an ultra-low concentration state where the particle concentration in the fluid is extremely low. The present invention also relates to a monitoring technique for monitoring the deterioration state of piping and reaction tanks in a plant or the like by applying these particle measuring techniques.

  There are various demands for measuring the amount of particles in a liquid. For example, metal powder generated by friction between a piston and a piston ring is mixed in engine oil in an internal combustion engine. The amount of the metal powder can be used as an index indicating the deterioration state of the engine, and can also serve as an index indicating the replacement time of the engine oil. If the amount of the metal powder in the engine oil can be measured, it is possible to prevent the engine from being excessively deteriorated and know the proper oil replacement time.

  For example, in a plant such as a nuclear reactor, it is extremely important to know the deterioration state. There are many degradation modes in the plant, and it is not possible to discuss the degree of degradation in general. For example, in the case of degradation in which the wall thickness of the piping decreases due to long-term use, the shaved piping material is cooled water, etc. It should be mixed in the fluid flowing in the pipe, and if the amount of ground material in the fluid can be monitored, the deterioration state of the plant can be known.

  However, it is not easy to monitor the amount of particles in these fluids. This is because the particles in these fluids are foreign substances that ideally do not exist in a normal operating state, and even if they exist, they are extremely minute. Further, even if particles (foreign matter) are detected after an abnormality has occurred in an internal combustion engine, plant, etc., the purpose cannot be achieved, so it is necessary to detect that the amount of foreign matter in a normal operating state has increased only slightly. . Since it is necessary to detect a very small increase in foreign matter, which is inherently a trace amount, it can be easily assumed that the difficulty is extremely high.

Whether or not a small amount of foreign matter can be detected depends on the sensitivity of the detection device (sensor). Sensors are required to have high sensitivity due to the demand for trace detection. However, when the sensor sensitivity is improved, sensor drift generally becomes a problem, and noise immunity decreases. For example, as disclosed in Patent Document 1, a detection coil head that is electromagnetized by an excitation current and an oscillation tuning circuit that supplies the detection coil head with an excitation current are provided, and the detection coil head is made of metal in engine oil. In an oil check sensor that is configured to adsorb powder and measures the inductance value of the detection coil head according to the amount of adsorbed metal powder using an oscillation tuning circuit, fluctuation (drift) of the sensor baseline is also a problem. It is difficult to detect the foreign substance (particle) concentration with high accuracy.
JP 2000-32248 A

  In view of the above problems, the present inventors made an invention of a foreign matter detection system capable of detecting low-concentration foreign matter (metal powder) (hereinafter referred to as “prior invention”), and the same application as the present application. A patent application identified as Japanese Patent Application No. 2004-41766 (hereinafter referred to as “prior application”) has been filed. The above-described prior invention is intended to detect low-concentration foreign matter by capturing foreign matter for a certain period of time, increasing the concentration of foreign matter in that region, and measuring the foreign matter concentration at the time when the catching is released. Here, in the prior invention, the foreign matter capturing means and the sensor are separated in position so that no foreign matter is present in the observation region of the sensor when the foreign matter is captured by the foreign matter capturing means. Therefore, the sensor can be calibrated immediately before the observation, and the influence of the fluctuation (drift) of the baseline can be removed. Such a prior invention makes it possible to increase the concentration by the foreign matter capturing means even if the foreign matter is originally a low concentration, and it is possible to eliminate the influence of the baseline fluctuation by the calibration immediately before the measurement. It becomes possible to measure a foreign object with high accuracy.

  However, the present inventors have recognized that there is room for further improvement in the prior invention. That is, in the prior invention, the foreign matter concentration is increased by the foreign matter catching means and the sensor is calibrated before the foreign matter is detected by the sensor, so that the foreign matter can be detected with high accuracy. It should be noted here that the sensor calibration needs to be executed after the foreign matter is released by the foreign matter capturing means. That is, if a foreign matter release operation is interposed between calibration and measurement, noise due to the release operation is generated, and the influence of the noise is mixed into the sensor output. Therefore, if calibration is to be performed after the release of foreign matter, the foreign matter capture means must be sufficiently separated from the sensor observation region because at the time of calibration there should be no foreign matter or very little foreign matter in the sensor observation region. Must be placed in position.

  However, if the foreign matter capturing means is set apart from the sensor observation area by a sufficient distance to secure the time required for calibration, the collected foreign matter will diffuse until it moves to the sensor observation area, The effect of increasing the concentration will be diminished. In other words, in order to obtain the effect of increasing the concentration of foreign matter, it is necessary to make the sensor observation area as close as possible to the foreign matter capture region, but this will reduce the accuracy of calibration (some foreign matter reaches the observation region). Resulting in). That is, there is a problem in that there is a trade-off between increasing the concentration of foreign matter and the accuracy of calibration.

  Of course, even if there is a problem as described above, the prior invention according to the prior application can be used for particle measurement within the accuracy of the calibration. However, in the configuration of the prior invention, the measurement of the particles concentrated by capture reflects the particle concentration when it reaches the observation region, so the measured value is released from the release of the captured particles to the observation region. It greatly reflects the degree of diffusion until it reaches. That is, the degree of diffusion depends on the time from the particle release to the observation region, and the time until the particle (group) reaches the observation region depends on the flow velocity of the fluid in which the particles exist. That is, in the prior invention, there is a problem that the output value greatly fluctuates when the flow velocity of the fluid in which particles are present changes.

  It is an object of the present invention to provide a particle measurement similar to that of the previous invention that can realize a sensor arrangement position capable of securing sufficient time for accurate calibration without diminishing the effect of increasing the concentration of foreign matter captured by the foreign matter capturing means. To provide a method. It is another object of the present invention to provide a particle metering technique similar to the prior invention that can obtain an output value that does not depend on the flow velocity of a fluid in which particles exist. Another object of the present invention is to provide a technology that makes it possible to apply this to particles made of any material, assuming that a magnetic substance is assumed as a foreign substance in the prior invention. Still another object of the present invention is to provide a system and method capable of detecting deterioration at a very early stage with high accuracy by applying the particle metering technique presented in this specification to deterioration detection of a plant or the like. .

  The invention disclosed in this specification is as follows. That is, the particle metering system of the present invention is a particle metering system that measures the number or amount of particles present in a liquid or gas having a flow in a predetermined direction in a non-contact manner, and resists the particles against the flow. A first particle capturing means for capturing the particles for a certain period of time and releasing the capturing of the particles at a predetermined timing; and a position downstream of the flow from the position where the first particle capturing means is disposed; And a particle sensor that obtains an output value corresponding to the number or amount of the particles in the observation region. According to such a particle measuring system, the particle concentration can be increased by the first particle capturing means, and the number of particles can be measured by the particle sensor located downstream of the flow. In other words, increasing the particle concentration by the first particle capturing means can be realized by capturing particles for a certain period of time, so that the measurement time is increased and the sensitivity of the measurement is increased. It corresponds to. In other words, it can be said that the measurement technique based on the present invention uses the concept of dimensional transformation that transforms the dimension of time into the dimension of the number of particles (particle density). . Therefore, according to the present invention, it is possible to accurately measure the concentration of particles having a very low concentration.

  Here, the particle sensor may further include second particle capturing means for capturing the particles in a region including the observation region. By providing the second particle trapping means, the concentration of the particles in the observation region is increased again even if the particles having a high concentration by the first particle trapping means diffuse before reaching the observation region of the particle sensor. Can do. As a result, it becomes possible to dispose the particle sensor sufficiently away from the first particle capturing means, and the calibration of the particle sensor can be performed stably and accurately. That is, when the present invention is viewed from another viewpoint, the time until the released particles reach the observation region after the first particle capturing unit releases the particles is calibrated. It is possible to provide a particle metering system in which the particle sensor is arranged away from the first particle capturing means so as to be more than the time required for the above. In this specification, “calibration” means that output correction (zero point calibration) is performed with an output when the sensor output can be estimated to be 0 (no particles are present in the observation region of the sensor) as “0”. Means. There are various zero point calibration methods. For example, a bias is applied to the output circuit so that the sensor output at the time of calibration is “0”, or the sensor output at the time of calibration is recorded. In addition, a method of adding the output value at the time of calibration previously recorded as a correction value to the sensor output at the time of subsequent measurement can be adopted. In the calibration and output measurement of particle sensors, measurement through an appropriate integration circuit (low-pass filter) and the acquisition of multiple samples and the use of an average value to eliminate high-frequency noise and increase the accuracy of the measurement value Needless to say, it can be increased.

  In the above invention, the following can be applied as the particle capturing means. That is, when the particles include a magnetic material, a magnetic force such as a permanent magnet or an electromagnet can be used. Alternatively, when the particle is a dielectric, a conductor, or a semiconductor, and the fluid in which the particle is present is an insulator, an appropriate charge imparting means is provided to impart a charge to the particle and the electrostatic force can be used. Alternatively, a filtering means that permeates a substance (fluid) constituting the flow and inhibits the permeation of particles can be used as the capturing means. In this case, the trapped particles can be released by reversing the direction of the filtering means relative to the flow. Alternatively, when the particle is a gas such as a gas, an adsorbent that selectively adsorbs the particle can be used as the capturing means, and the captured particle can be released by heating the adsorbent.

  In the above invention, the following can be applied as the particle sensor. That is, when the particle is a conductor or a semiconductor, an induction element is applied to the particle sensor, and the induction caused by the eddy current in the conductor or the semiconductor due to the external AC magnetic field generated by the induction element or the excitation induction element. The number or amount of particles can be measured by changing the inductance of the element. Alternatively, when the particle is a magnetic substance, the particle sensor is provided with a magnetic field generating means for generating a magnetic field, a Hall element is applied as the sensor, and the number or amount of particles is measured by fluctuation of the magnetic field detected by the Hall element. it can. Alternatively, when the particle is a dielectric, a capacitive element is applied as the particle sensor, and the number or amount of particles can be measured by changing the capacitance of the capacitive element. Alternatively, the particle sensor can be provided with laser light generation means and scattered light measurement means, and the number or amount of particles can be measured based on the intensity of scattered light obtained by scattering the laser light by the particles. Alternatively, when the particles are gaseous molecules, a gas sensor that measures the number or concentration of the gaseous molecules can be applied as the particle sensor.

  As described above, various particle capturing means and particle sensors can be applied to the particle weighing system of the present invention. However, the effectiveness and applicability of these capture means and sensors differ depending on the type of particles and the material of the fluid container / pipe. For example, particle capture means using magnetic action cannot be applied to paramagnetic material particles or magnetic material containers / pipes, and electrostatic capture is applied to conductive material containers / pipes. Means are not applicable. In addition, a sensor using an inductive element utilizing eddy current cannot be applied to the particles of the insulator material. In addition, it will be easily understood by those skilled in the art that due to the physical phenomenon underlying particle capture and sensing, the capture and sensing may or may not be used with specific particles or container / pipe materials. However, as long as the above-described particle capturing means and particle sensor can be used in a specific particle material and a container / pipe material in accordance with the underlying physical phenomenon, any combination of these capturing means and sensor may be used. Needless to say, it is applicable to a weighing system. The particle capturing means or particle sensor described above can be used alone or in combination as a plurality of particle capturing means or a plurality of particle sensors. In addition, when applying a magnetic, electrostatic, or optical capture / sensing technique, particles can be measured without contact with the fluid in which the particles are present.

  In the above-described particle measurement system, the following particle measurement method can be applied. That is, the particle metering method, which is another invention of the present application, measures the number or amount of particles present in a liquid or gas having a flow in a predetermined direction, and captures the particles against the flow for a certain period of time. And a first particle capturing means for releasing the capture of the particles at a predetermined timing, and the particles located in the observation region disposed at a position downstream of the flow from a position where the first particle capturing means is disposed. A particle metering method using a particle metering system having an output value according to the number or amount of the particles, wherein the particles are captured by the first particle capturing means for a predetermined capturing time. Starting the step of releasing the trapped particles, performing the calibration of the particle sensor after the release of the particles, and starting the measurement by the particle sensor Has a step, a. According to such a particle metering method, particles are captured for a predetermined capture time, so that it is possible to increase the particle concentration, and the particle sensor is calibrated after the particles are released and the metering of the particles is started. In addition, the generation of noise associated with particle release can be avoided and the influence of sensor baseline fluctuations can be eliminated. In the configuration of the present invention, the concept of dimension conversion that converts the dimension of time described above into the dimension of the number of particles (particle density) appears briefly. That is, by increasing the measurement time (capture time) in the time dimension, the number of observed particles (the dimension of the spatial distance called particle density) is increased, leading to the effect of improving the sensitivity of the entire particle measurement system.

  Here, the particle metering system includes second particle capturing means for capturing the particles in a region including the observation region of the particle sensor, and the particles are being captured or captured by the first particle capturing unit. After the release of the particles, and before the calibration of the particle sensor, may start capturing the particles by the second particle capturing means. In order to capture the particles in the observation region of the particle sensor by the second particle capturing means, the particle sensor is observed even if the particles concentrated by the first particle capturing means start to diffuse. Since it is concentrated again in the region, the output of the particle sensor can be increased. In the present invention, since the capture of the second particle capturing means is started before the calibration of the particle sensor, it is not affected by noise accompanying the capturing operation of the second particle capturing means.

  In the particle capturing method, when the output value of the particle sensor is equal to or greater than a predetermined threshold value, the step of displaying the output value or a value calculated from the output value; and the output value of the particle sensor is the predetermined value. The capture time is changed longer and the series of steps from capturing the particles by the first particle capturing means is repeated. By having such a configuration, if the sensitivity of the particle metering system is insufficient, it is possible to increase the sensitivity of the particle metering system by increasing the capture time in the time dimension. In addition, when the capture time is equal to or greater than a predetermined threshold, it can be determined that the particles cannot be detected. If the measurement cannot be performed within a realistic measurement time, it is determined that the measurement limit of the particle weighing system has been exceeded.

  The particle metering system and the particle metering method described above can be applied to plant deterioration detection. In the piping or reaction tank constituting the plant, for example, a reaction liquid or a cooling liquid circulates in the inside. It is generally known that these reaction liquids and cooling liquids may cause the piping and the inner walls of the reaction tank to be scraped and deteriorated. The grinding rod ground with such a circulating fluid is diffused into the circulating fluid and circulates in the piping together with the circulating fluid unless it is positively removed. The plant deterioration detection system and method of the present application recognizes that the grinding rod circulating in the pipe is regarded as particles, and that the increase in the number of grinding rods (particles) reflects the deterioration degree of the plant. As a basis, the particle metering system and particle metering method described above are applied and applied to the detection of plant deterioration.

  The specific configuration is as follows. That is, the plant deterioration detection system of the present invention is a plant deterioration detection system that detects deterioration of the pipe or a reaction tank of the plant in a plant having a pipe through which a fluid flows, and is disposed outside the pipe. First particles for capturing the particles constituting the pipe or the plant reaction vessel or the compound of the material against the fluid flow for a certain period of time and releasing the particles at a predetermined timing According to the number or amount of the particles in the observation region, which is arranged at a position downstream of the flow and outside the pipe with respect to the position where the first particle capturing means is disposed. A particle sensor for obtaining an output value. The particle sensor may further include second particle capturing means for capturing the particles in a region including the observation region.

  The particle capturing means and the particle sensor that can be applied in the plant deterioration detection system are the same as those in the above-described particle weighing system. Further, the plant deterioration detection method applicable to the plant deterioration detection system is the same as the above-described particle measurement method. However, in the plant deterioration detection method, it is sufficient to determine whether the particle concentration is equal to or higher than a predetermined threshold value.

  Since the particle detection method used in the present invention can accurately detect particles having a very low concentration, it is possible to detect deterioration of the plant at an early stage. In addition, if the particle capturing means and the particle sensor are appropriately selected, particle detection can be performed in a non-contact manner, and this can be applied to a plant that has already been installed without significant modification. In addition, the degradation detection method of the present invention can be applied without imposing a heavy burden in plant design.

  According to the present invention, it is possible to realize a sensor arrangement position that can secure a sufficient time for performing accurate calibration of a particle sensor without diminishing the effect of increasing the concentration of particles captured by the particle capturing means. In addition, an output value that does not depend on the flow velocity can be obtained. Further, it is possible to provide a particle weighing method applicable to particles made of any material. Furthermore, it is possible to provide a plant deterioration detection system and method that can detect plant deterioration with high accuracy at an extremely early stage.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, two basic configurations of the particle metering system according to the embodiment of the present invention are illustrated, and specific elements applicable to each component in the two basic configurations are illustrated. Thereafter, the applicability of each specific element to the basic configuration will be described, and the actual operation result of the particle metering system in a specific configuration will be described. Finally, the application of this particle measurement system to a plant deterioration detection system will be described, and various modifications will be mentioned. In the drawings described below, members having the same function are denoted by the same reference numerals, and redundant description is omitted.

1. 1. Basic Configuration of Particle Metering System 1.1 First Configuration Example FIG. 1 is a block diagram showing a first configuration example which is an example of the basic configuration of a particle metering system according to an embodiment of the present invention. The first configuration example is an example in which one particle capturing unit is provided in the particle metering system. The particle measurement system 10 of the first configuration example includes a first particle capturing unit 11, a particle sensor 12, a control unit 13, and a display device 14.

  The first particle capturing unit 11 is disposed in the vicinity of or inside the pipe 15, and has a function of capturing particles 17 existing in the fluid flowing in the direction of the arrow 16 in the pipe 15 under the control of the control unit 13. Further, it has a function of releasing the captured particles 17 under the control of the control means 13. There are various methods for realizing these functions. For example, when the particle 17 is a magnetic material, an external magnetic field can be applied to the particle 17 to capture the particle 17 by a magnetic action. Alternatively, when the particles 17 can be charged, electrostatic adsorption can be performed using Coulomb force. Alternatively, the particles 17 can be captured or adsorbed by a mechanical or physical action. A specific configuration of the first particle capturing unit 11 will be described later. In FIG. 1, the first particle capturing unit 11 is illustrated as being disposed outside the pipe 15, but depending on the specific configuration of the first particle capturing unit 11, the first particle capturing unit 11 may be disposed inside the pipe 15. Some or all of them may be arranged.

  The particle sensor 12 is disposed in the vicinity of or inside the pipe 15 and has a function of detecting the number of particles 17 in the observation region 18. The particle sensor 12 is controlled by the control unit 13 and executes calibration and particle detection under the control of the control unit 13. There are various methods for detecting the particles 17. For example, when the particle 17 is a conductor or a semiconductor, the particle 17 can be detected by generating an eddy current in the particle 17 by the action of an external AC magnetic field and measuring a change in inductance of the detection coil caused by the eddy current. . Or when the particle | grains 17 are high permeability materials, the fluctuation | variation of an external magnetic field can be measured and the particle | grains 17 can be detected. Alternatively, when the particle 17 is a high dielectric constant material, the particle 17 can be detected by measuring the capacitance change of the detection capacitor. Alternatively, when the particle 17 is a material that reflects or absorbs light, the particle 17 can be detected by measuring scattered light or transmitted light. Alternatively, when the particle 17 is a gas, the particle 17 can be detected using a gas sensor using a physical phenomenon in which the resistivity or the like changes due to gas adsorption. A specific configuration of the particle sensor 12 will be described later. In FIG. 1, the particle sensor 12 is illustrated as being disposed outside the pipe 15, but a part or all of the particle sensor 12 is disposed inside the pipe 15 depending on the specific configuration of the particle sensor 12. There is also a case.

  The control means 13 controls the first particle capturing means 11, the particle sensor 12 and the display device 14. Although the specific function and configuration of the control unit 13 differ depending on the specific configuration of the first particle capturing unit 11, the particle sensor 12, and the display device 14, basically, a control signal is sent to the first particle capturing unit 11. The generated output signal is received from the particle sensor 12, and the received output signal is transmitted to the display device 14 as it is or after a necessary calculation for concentration conversion is executed. Further, the control means 13 executes calibration of the particle sensor 12 at a necessary timing. Further, the control means 13 supplies power to the first particle capturing means 11 and the particle sensor 12 as necessary. Therefore, the control unit 13 includes a signal generation unit that generates a control signal to the first particle capturing unit 11, a sensor signal reception unit that receives an output signal from the particle sensor 12, and a display that generates a signal to the display device 14. It has a signal generation unit, a control logic unit that controls these, a calculation unit that performs calculations such as concentration calculation, and a power supply control unit that supplies power as necessary. Specific examples of the control means 13 include an information processing device having a program operation function such as an electronic circuit or a logic circuit that can execute a weighing sequence described later, and a computer.

  The display device 14 is a means for receiving a display signal from the control means 13 and displaying the measurement result. Specifically, image display devices such as a CRT monitor and a liquid crystal display device can be exemplified. However, as long as the measurement result can be displayed, the display is not limited to images, characters, and the like. For example, the measurement result can be read out by voice, and it can be notified by a beep sound that the measurement result exceeds a certain threshold value.

  Although the pipe 15 does not constitute the present particle measurement system itself, depending on the material properties, the physical phenomenon on which the first particle capturing unit 11 or the particle sensor 12 depends may not be generated effectively. is there. Therefore, the material selection of the piping 15 is important for the necessity of operating the present particle metering system as intended. However, the particle metering system 10 can be applied to the pipe 15 of any material by appropriately selecting the specific configurations of the first particle capturing unit 11 and the particle sensor 12. Which piping material is effective or ineffective in which specific configuration of the first particle capturing means 11 or the particle sensor 12 will be described later. The material and shape of the pipe 15 are not particularly limited as long as the physical aspects that affect the measurement of the pipe 15 are excluded. For example, stainless steel piping, iron (steel) piping, vinyl chloride and other various plastic piping can be exemplified.

  The particle 17 is an object to be measured by the particle measuring system 10, and as described above, its physical properties are limited by the physical phenomenon on which the first particle capturing unit 11 and the particle sensor 12 depend. However, by appropriately selecting the specific configurations of the first particle capturing means 11 and the particle sensor 12, the present particle metering system 10 can cope with the measurement of particles 17 of any material as in the case of the pipe 15. It is the same. Which particle material is effective or ineffective in which specific configuration of the first particle capturing means 11 or the particle sensor 12 will be described later. In this particle measurement system, powder or particles such as metal powder generated by mechanical wear or friction with fluid flowing in the pipe 15 itself or an internal combustion engine or a plant to which the pipe 15 is connected are assumed. To do. However, the particles 17 in the present invention are not limited to powders and granules, but are a single molecular state such as a general gas, an atomic state such as a rare gas, and a cluster state material in which a plurality of molecules are aggregated. It is a concept that includes As long as the substance can be dispersed or homogenized in the fluid, it is included in the concept of the particle 17 of the present invention.

  The fluid flowing through the pipe 15 is a fluid substance in a liquid or gaseous state in the operating state. However, there are some restrictions on the fluid. For example, when the particles 17 are captured or detected using a magnetic action, the fluid needs to be non-magnetic (paramagnetic material). Further, when the particles 17 are captured by electrostatic action by applying an electric charge to the particles 17, the fluid needs to be an insulator and has a larger ionization energy than the substance constituting the particles 17. . However, by appropriately selecting the specific configurations of the first particle capturing means 11 and the particle sensor 12, the present particle metering system 10 can be adapted to fluids of any material as in the case of the pipe 15 and the particles 17. It is the same. Specific examples of the fluid include insulators (dielectrics) such as water, oil, and air and nonmagnetic materials (paramagnetic materials). In practice, magnetic fluids (magnetic materials) and electrolyte solutions (conductors) are rarely used, so it is assumed that the fluid applied to this particle metering system is an insulator and non-magnetic material such as water or oil. Is considered sufficient. However, when ionic substances (impurities) such as salt are mixed in the water, there is a possibility that problems may occur in capturing particles by an electrostatic method.

  FIG. 2 is a schematic diagram for explaining the operation of the particle weighing system 10 of the configuration example 1. FIG. 2A shows a state in which the particles 17 are captured by the first particle capturing unit 11, and FIG. The trapped particles 17 are released and moved to the observation region 18 of the particle sensor 12. In FIG. 2, a part of the particle measuring system 10 is omitted.

  In FIG. 4A, the first particle capturing means 11 is in an ON state, that is, a state where particles 17 are captured. Particles 17 are present in the fluid flowing in the direction of the arrow 16 in the pipe 15, and when the particles 17 reach the vicinity of the first particle trapping unit 11, as shown in the drawing, around the first particle trapping unit 11. Be captured. When the particles 17 are in the trapped state, the particles 17 do not reach or reach the observation region 18 of the particle sensor 12 arranged on the downstream side of the flow.

  After a certain amount of particles 17 are trapped by the first particle trapping means 11, the first particle trapping means 11 is turned off, that is, the particles 17 are released. As shown in FIG. 5B, the particles 17 leave the restraint from the first particle capturing means 11 and reach the observation region 18 of the particle sensor 12 while diffusing in the fluid according to the flow. The particles 17 existing in the observation region 18 cause the particle sensor 12 to output an output signal corresponding to the quantity. Here, since the concentration of the particles 17 is increased to some extent by the first particle capturing means 11 as shown in FIG. 5A, the particles 17 reach the observation region 18 at a concentration higher than the concentration existing in the normal fluid. To do. Therefore, the particle detection sensitivity of the entire system can be increased without increasing the detection sensitivity of the particle sensor 12.

  FIG. 3 is a flowchart showing an example of a measurement method of the particle weighing system 10 of the configuration example 1. The capturing state of the first particle capturing means 11 is turned on (step 19), and it is determined whether a predetermined time has elapsed (step 20). An example of the predetermined time is 10 minutes. Step 20 is repeated until the predetermined time has elapsed. If it is determined that the predetermined time has elapsed, the trapping state of the first particle trapping means 11 is turned off, that is, released (step 21). Thereafter, the particle sensor 12 is calibrated (step 22). Since calibration is performed after the OFF operation of the first particle capturing unit 11, calibration and measurement can be performed without being affected by noise associated with the operation. Next, measurement by the particle sensor 12 is executed (step 23). The measurement result is subjected to concentration conversion calculation in the control means 13 and displayed on the display device 14 (step 24). Thereafter, it is determined whether or not the measurement is finished (step 25). When the measurement is performed again, the control from step 19 is repeated, and when the measurement is finished, the measurement is finished (step 26).

  According to the particle metering system 10 of the configuration example 1 described above, the concentration of the particles 17 is concentrated in advance by the first particle capturing unit 11 and the quantity of the particles 17 is measured by the particle sensor 12 arranged downstream. Sensitivity can be increased. In the state where the particles 17 are captured by the first particle capturing means 11 and the state immediately after the release, the particles 17 are hardly present in the observation region 18 of the particle sensor 12. For this reason, calibration of the particle sensor 12 is executed, and even the highly sensitive particle sensor 12 can remove the influence of the drift (baseline fluctuation) and realize high-accuracy measurement.

1.2 Second Configuration Example FIG. 4 is a block diagram showing a second configuration example which is another example of the basic configuration of the particle weighing system according to the embodiment of the present invention. The second configuration example is an example in which two particle capturing means are provided in the particle metering system. The particle measurement system 27 of the second configuration example includes a first particle capturing unit 11, a particle sensor 12, a control unit 13, a display device 14, and a second particle capturing unit 28. Since the first particle capturing unit 11, the particle sensor 12, the control unit 13, and the display device 14 are the same as those in the first configuration example, the description thereof is omitted. Further, the piping 15, the particles 17, and the fluid flowing in the piping 15 are the same as in the configuration example 1.

  The functions and necessary conditions of the second particle capturing means 28 are the same as those of the first particle capturing means 11. However, the second particle capturing means 28 is arranged so that the particles 17 are captured in the observation region 18 of the particle sensor 12. Since the particle metering system 27 of the configuration example 2 includes the second particle capturing unit 28, the particles 17 captured and concentrated by the first particle capturing unit 11 can be concentrated again in the observation region 18, and thus more precise than the configuration example 1. In addition, stable measurement can be performed.

  FIG. 5 is a schematic diagram for explaining the operation of the particle weighing system 27 of the configuration example 2. FIG. 5A shows a state in which the particles 17 are captured by the first particle capturing unit 11, and FIG. (C) shows a state in which the particles 17 have moved to the observation region 18 of the particle sensor 12 and are captured by the second particle capturing means 28. In FIG. 5, a part of the particle metering system 27 is omitted.

  In FIG. 4A, the first particle capturing means 11 is in an ON state, that is, a state where particles 17 are captured. Particles 17 are present in the fluid flowing in the direction of the arrow 16 in the pipe 15, and when the particles 17 reach the vicinity of the first particle trapping unit 11, as shown in the drawing, around the first particle trapping unit 11. Be captured. When the particles 17 are in the trapped state, the particles 17 do not reach or reach the observation region 18 of the particle sensor 12 arranged on the downstream side of the flow.

  After a certain amount of particles 17 are trapped by the first particle trapping means 11, the first particle trapping means 11 is turned off, that is, the particles 17 are released. As shown in FIG. 5B, the particles 17 leave the restraint from the first particle capturing means 11 and diffuse in the fluid according to the flow.

  The particles 17 that have reached the observation region 18 of the particle sensor 12 are captured in the observation region 18 by the second particle capturing means 28. The particles 17 existing in the observation region 18 cause the particle sensor 12 to output an output signal corresponding to the quantity thereof, but the density of the particles 17 is very high as shown in FIG. A very high output of the particle sensor 12 can be expected.

  That is, in the case of the configuration example 1, even if the particle concentration is increased by the first particle capturing unit 11, the concentration is lowered by diffusion to some extent when the particles 17 reach the observation region 18. In Example 2, since the concentration is increased again in the observation region 18, a high output signal from the particle sensor 12 is obtained. In other words, in the case of the configuration example 1, in order to obtain a sufficiently high output level of the particle sensor 12, it is necessary to perform observation before the concentration of the particles 17 decreases due to diffusion. For this reason, the particle sensor 12 cannot be disposed sufficiently away from the first particle capturing means 11. For this reason, the case where it is difficult to ensure the time for calibrating the particle sensor 12 occurs. However, in the second configuration example, even if the particles 17 concentrated by the first particle capturing unit 11 diffuse, the second particle capturing unit 28 performs concentration again, so that the observation is performed even if the concentration of the particles 17 decreases due to diffusion. It does not matter as long as the particles 17 are captured in the region 18. As a result, it is possible to dispose the particle sensor 12 sufficiently away from the first particle capturing unit 11, and it is possible to ensure a sufficient time for performing calibration of the particle sensor 12.

  FIG. 6 is a flowchart showing an example of a measurement method of the particle weighing system 27 of the configuration example 2. The capturing state of the first particle capturing means 11 is turned on (step 19), and it is determined whether a predetermined time has elapsed (step 20). An example of the predetermined time is 10 minutes. Step 20 is repeated until the predetermined time has elapsed. If it is determined that the predetermined time has elapsed, the trapping state of the first particle trapping means 11 is turned off, that is, released (step 21). Thereafter, the second particle capturing means 28 is turned on, that is, in the capturing state (step 29). Thereafter, the particle sensor 12 is calibrated (step 22). Since the calibration is performed after the ON / OFF operation of the first particle capturing unit 11 and the second particle capturing unit, the calibration and measurement can be executed without being affected by noise associated with the operation. Next, measurement by the particle sensor 12 is executed (step 23). The measurement result is subjected to concentration conversion calculation in the control means 13 and displayed on the display device 14 (step 24). After that, the capturing means is reset all the time (step 30), and then it is determined whether the measurement is completed (step 25). When measurement is performed again, the control from step 19 is repeated, and when measurement is completed, the measurement is terminated. (Step 26).

  According to the particle measuring system 27 of the configuration example 2 described above, the concentration of the particles 17 is concentrated in advance by the first particle capturing unit 11, and the number of particles 17 is measured by the particle sensor 12 disposed downstream. In this measurement, the particles 17 in the observation region 18 are re-concentrated by the second particle capturing means 28. For this reason, the detection sensitivity of the system can be increased regardless of the diffusion state of the particles 17. In the state where the particles 17 are captured by the first particle capturing means 11 and the state immediately after the release, the particles 17 are hardly present in the observation region 18 of the particle sensor 12. For this reason, calibration of the particle sensor 12 is executed, and even the highly sensitive particle sensor 12 can remove the influence of the drift (baseline fluctuation) and realize high-accuracy measurement. Furthermore, since the first particle capturing means 11 and the particle sensor 12 can be arranged sufficiently apart from each other, the calibration can be performed sufficiently accurately.

2. Specific Configuration 2.1 Particle Capture Unit A specific configuration of the particle capture unit is illustrated below. The specific configuration described below exemplifies a configuration (corresponding to the second configuration example) in which two particle trapping means are mainly arranged. However, needless to say, one that can be applied as one particle trapping means by omitting one of the two particle trapping means can be applied to the first configuration example. In addition, when a single particle trapping unit is illustrated as the particle trapping unit, it can be applied to the first configuration example as well as two particle trapping units as much as possible in the second configuration example. Needless to say, it can be applied.

A. Electromagnet FIG. 7 is a block diagram showing an example in which the specific configuration of the particle capturing means is configured as an electromagnet. (A) shows a state where the particles 17 are captured by the first particle capturing means 11, and (b) shows a state where the particles 17 are captured by the second particle capturing means 28. The electromagnet of this example has a configuration in which a coil 32 is wound around a magnetic core 31 of a ferromagnetic material such as steel, and energization of the coil 32 is controlled by a power supply control circuit 33. The power control circuit 33 is a part of the control means 13.

  In the electromagnet of this example, the coil 32 of the first particle capturing unit 11 is energized, and the particles 17 are captured in the pipe 15 adjacent to the magnetic core 31 of the first particle capturing unit 11. Further, the coil 32 of the second particle capturing unit 28 is energized, and the particles 17 are captured in the pipe 15 adjacent to the magnetic core 31 of the second particle capturing unit 28. Switching of energization to these coils 32 can be performed by the power supply control circuit 33, and the control of the configuration examples 1 and 2 can be executed.

  In the case where the particle capturing means is constituted by the electromagnet of this example, the particles 17 need to be magnetic as well. In addition, it is necessary for the pipe 15 to be a paramagnetic material (nonmagnetic material). If the particle capturing means is configured by the electromagnet of this example, there is an advantage that the concentration operation of the particles 17 can be performed from the outside of the pipe 15 without contact.

B. Solenoid Magnet FIG. 8 is a block diagram showing an example in which the specific configuration of the particle capturing means is configured as a solenoid magnet. (A) shows a state where the particles 17 are captured by the first particle capturing means 11, and (b) shows a state where the particles 17 are captured by the second particle capturing means 28. The solenoid type magnet of this example includes a solenoid 41, a driving iron core 42, and a permanent magnet 43 provided on one side of the driving iron core 42, and the driving iron core 42 is disposed inside the solenoid 41. The drive iron core 42 is driven by energizing the solenoid 41, and the capture or release of the particles 17 is controlled by bringing the permanent magnet 43 into or out of contact with the pipe wall of the pipe 15. Energization of the solenoid 41 is controlled by a power supply control circuit 44. The power supply control circuit 44 is a part of the control means 13.

  In the solenoid type magnet of this example, the solenoid 41 of the first particle capturing unit 11 is energized, and the particles 17 are captured in the pipe 15 adjacent to the permanent magnet 43 of the first particle capturing unit 11. Further, the solenoid 41 of the second particle capturing unit 28 is energized, and the particles 17 are captured in the pipe 15 adjacent to the permanent magnet 43 of the second particle capturing unit 28. Switching of energization to these solenoids 41 can be performed by the power supply control circuit 44, and the control of the configuration examples 1 and 2 described above can be executed.

  In addition, when the particle | grain capture | acquisition means is comprised with the solenoid type magnet of this example, it is necessary for the particle | grains 17 to be a magnetic body. In addition, it is necessary for the pipe 15 to be a paramagnetic material (nonmagnetic material). If the particle capturing means is constituted by the solenoid type magnet of this example, there is an advantage that the concentration operation of the particles 17 can be performed from the outside of the pipe 15 without contact.

C. Motor-Driven Magnet FIG. 9 is a block diagram showing an example where the specific configuration of the particle trapping means is configured as a motor-driven magnet. (A) shows a state where the particles 17 are captured by the first particle capturing means 11, and (b) shows a state where the particles 17 are captured by the second particle capturing means 28. The motor-driven magnet of this example has a motor 50, a crank 51, and a permanent magnet 52 provided at the tip of the crank 51. By rotating the motor 50, the position of the permanent magnet 52 is moved, and the particles 17 Control the capture position. The rotational drive of the motor 50 is controlled by a motor control circuit 53. The motor control circuit 53 is a part of the control means 13.

  In the motor-driven magnet of this example, the motor 50 is rotationally driven, the permanent magnet 52 is stopped at the position shown in FIG. 1A, and the particles 17 are captured at the particle capturing position of the first particle capturing means 11. Further, the motor 50 is driven to rotate, and the permanent magnet 52 is stopped at the position shown in FIG. 4B to capture the particles 17 at the particle capturing position of the second particle capturing means 28. The rotation control of the motor 50 can be performed by the motor control circuit 53, and the control of the configuration examples 1 and 2 can be executed.

  In addition, when the particle | grain capture | acquisition means is comprised with the motor drive type magnet of this example, it is necessary for the particle | grains 17 to be a magnetic body. In addition, it is necessary for the pipe 15 to be a paramagnetic material (nonmagnetic material). If the particle capturing means is constituted by the motor-driven magnet of this example, there is an advantage that the concentration operation of the particles 17 can be performed from the outside of the pipe 15 without contact.

D. Charge Dust Collection System FIG. 10 is a block diagram showing an example where the specific configuration of the particle trapping means is configured as a charge dust collection system means. (A) shows a state where the particles 17 ′ are captured by the first particle capturing means 11, and (b) shows a state where the particles 17 ′ are captured by the second particle capturing means 28. The charged dust collection means of this example includes a probe 61, a first electrode 62, a second electrode 63, a high voltage power supply 64, a control power supply 65, and a control circuit 66. In the charged dust collection method means of this example, the probe 61 is introduced into the pipe 15 through the current introduction terminal 67, and the high voltage (for example, -1 kV) applied to the probe 61 from the high voltage power supply 64 is negatively applied to the particle 17, for example. Give charge. The charged particles 17 ′ are captured or released by a voltage applied from the control power supply 65 to the first electrode 62 or the second electrode 63. The control circuit 66 controls the high voltage power supply 64 and the control power supply 65, and the high voltage power supply 64, the control power supply 65 and the control circuit 66 are a part of the control means 13.

  In the charged dust collection means of this example, for example, a negative charge is applied to the particles 17 from the high-voltage power supply 64 via the probe 61, and a positive voltage is applied to the first electrode 62 by the control power supply 65, for example. The particles 17 ′ are captured at 11 particle capturing positions. Release of the particles 17 ′ in the first particle capturing means 11 is performed by applying a negative voltage to the first electrode 62, for example. Further, for example, a positive voltage is applied to the second electrode 63 by the control power source 65 to capture the particles 17 ′ at the particle capturing position of the second particle capturing means 28. Release of the particles 17 ′ in the second particle capturing means 28 is performed by applying, for example, a negative voltage to the second electrode 63. The control of the configuration examples 1 and 2 described above can be executed by the polarity of the voltage applied to the first electrode 62 and the second electrode 63 by the control power source 65. Needless to say, the polarity of the charge can be changed to a positive charge. In this case, of course, the polarity of the control voltage in the capture or release operation is reversed.

  When the particle trapping means is constituted by the charged dust collecting means of this example, the particle 17 may be a conductor, a semiconductor, or an insulator, but needs to be smaller than the ionization degree or ionization energy of the fluid flowing in the pipe 15. It is. Further, the fluid needs to be an insulator, and the pipe 15 needs to be an insulator at least in a region where the respective members are arranged.

E. Mesh FIG. 11 is a block diagram showing an example where the specific configuration of the particle capturing means is configured as a mesh (network). (A) shows a state where the particles 17 are captured by the first particle capturing means 11, and (b) shows a state where the particles 17 are captured by the second particle capturing means 28. The mesh 70 is fixed to the rotation introduction terminal 71, and rotates the rotation introduction terminal 71 from the outside of the pipe 15 to control the angle of the mesh 70 with respect to the fluid flow 16.

  In this example, the surface of the mesh 70 of the first particle capturing unit 11 is disposed so as to face the flow of the fluid flowing through the pipe 15 to capture the particles 17. Release of the particles 17 can be achieved by rotating the surface of the mesh 70 so that its normal is perpendicular to the flow direction (flow and surface are parallel), or until the surface of the mesh 70 is reversed. Do. The same can be done for the second particle capturing means 28. In the case of this example, the mesh 70 needs a sufficiently fine eye to capture the particles 17, but there is an advantage that the mesh 70 is not affected by the electrical and magnetic properties of the particles 17, the pipe 15 and the fluid.

F. Adsorbent FIG. 12 is a block diagram showing an example in which the specific configuration of the particle capturing means is configured as an adsorbent. (A) shows a state where the particles 17 are captured by the first particle capturing means 11, and (b) shows a state where the particles 17 are released from the first particle capturing means 11. In this example, a configuration having an adsorbent 80 and a heater 81 is exemplified as the particle capturing means. The adsorbent 80 has a property of adsorbing the particles 17 that are gases, and the particles 17 are released by energizing the heater 81 to heat the adsorbent 80. The heater 81 is energized by a heater power source 82, and the heater power source 82 is controlled by a control circuit 83. The heater power supply 82 and the control circuit 83 are part of the control means 13.

  In this example, the particles 17 are adsorbed by holding the adsorbent 80 at about room temperature (utilizing the adsorption performance inherent in the adsorbent), and the particles 17 are released by heating the adsorbent 80 with the heater 81. (Apply thermal energy to the adsorbed material to release it from the adsorption surface). Examples of the adsorbent include activated carbon, and examples of particles include molecular gas such as carbon monoxide, formaldehyde, toluene, and xylene, and particulate matter in exhaust gas. In this example, the particles 17 are required to be molecular particles or particles as fine as similar to them, but there is a merit that does not depend on the electrical and magnetic properties of the particles 17, the piping 15, and the fluid.

2.2 Particle Sensor The specific configuration of the particle sensor is illustrated below. Note that the particle sensors exemplified here can be used alone or in combination.

A. Eddy current utilization method (1)
FIG. 13 is a block diagram illustrating an example of the particle sensor 12. The particle sensor 12 of this example includes a coil 90 wound around a pipe 15, an oscillation circuit 91, and a frequency counter 92. The coil 90 receives an AC voltage (current) from the oscillation circuit 91 and generates an AC magnetic field. If the particle 17 exists in the observation region 18, an eddy current is generated in the particle 17 by the AC magnetic field from the coil 90. When an eddy current is generated, an alternating magnetic field due to the eddy current is generated and affects the coil 90. This influence on the coil 90 is observed as a change in the inductance of the coil 90 and fluctuates the resonance frequency (oscillation frequency) of the oscillation circuit 91. This frequency fluctuation is observed by the frequency counter 92, and the particles 17 can be detected. Since the magnitude of the frequency fluctuation has a positive correlation with the amount of particles 17, the number of particles 17 can be measured by observing the frequency fluctuation amount.

  In the particle sensor 12 of this example, since it is a requirement to generate an eddy current in the particle 17, the particle 17 needs to include a conductor or a semiconductor. Further, since it is necessary for the pipe 15 and the fluid to transmit an amount of magnetic flux necessary for observation, a ferromagnetic material is not preferable. According to the particle sensor 12 of this example, the number of particles 17 can be measured from the outside of the pipe 15 in a non-contact manner without performing any work on the pipe 15.

B. Eddy current utilization method (2)
FIG. 14 is a block diagram showing another example of the particle sensor 12. The particle sensor 12 of this example uses eddy current generated in the particles 17 as in the case of FIG. The particle sensor 12 of this example has three coils, an excitation coil 100 and sensor coils 101 and 102, as coils wound around the pipe 15, and includes an oscillator 103, a bridge 104, a phase shifter 105, an amplifier 106, and a synchronous detector 107. Is provided. The exciting coil 100 is driven by the oscillator 103 to generate an alternating current magnetic field for excitation. The exciting AC magnetic field generates eddy currents in the particles 17 in the observation region 18. The generated eddy current generates a magnetic field, and the magnetic field due to the eddy current is detected by the sensor coils 101 and 102. In this example, since the exciting coil 100 is provided independently, a large eddy current can be generated by increasing the exciting current, and the sensitivity of the sensor can be improved. The sensor coils 101 and 102 constitute a bridge circuit by the bridge 104, and can detect a change in impedance (inductance) with high sensitivity. Further, the signal from the oscillator is transmitted to the synchronous detector 107 via the phase shifter 105, and the synchronous detector 107 synchronously detects the output of the bridge circuit amplified by the amplifier 106, so that a minute output can be detected with high sensitivity. Is possible.

  In the particle sensor 12 of this example, as in the case of FIG. 13, it is necessary to generate an eddy current in the particle 17. Therefore, the particle 17 needs to contain a conductor or a semiconductor. Further, since it is necessary for the pipe 15 and the fluid to transmit an amount of magnetic flux necessary for observation, a ferromagnetic material is not preferable. According to the particle sensor 12 of this example, the number of particles 17 can be measured from the outside of the pipe 15 in a non-contact manner without performing any work on the pipe 15.

C. Hall Element FIG. 15 is a block diagram showing still another example of the particle sensor 12. The particle sensor 12 of this example has a Hall element 110 and detects the fluctuation of the external magnetic field 114 generated by the magnets 112 and 113 by the Hall element 110. The Hall element 110 is controlled by the amplification / control device 111 and its output is amplified.

  In the case of this example, if the magnetic permeability of the particles 17 is different from the magnetic permeability of the fluid flowing in the pipe 15, the presence of the particles 17 affects the external magnetic field 114 and can be detected. However, in order to increase the influence on the external magnetic field 114, it is preferable that the magnetic permeability of the particles 17 is large. In order for the external magnetic field 114 to pass through the observation region 18, the pipe 15 is preferably a paramagnetic material. According to the particle sensor 12 of this example, the number of particles 17 can be measured from the outside of the pipe 15 in a non-contact manner without performing any work on the pipe 15. When the fluctuation of the external magnetic field 114 is sufficiently large and its detection sensitivity does not become a problem, an appropriate magnetic field fluctuation detection element (for example, an inductance element) can be used instead of the Hall element 110.

D. Capacitor Method FIG. 16 is a block diagram showing still another example of the particle sensor 12. The particle sensor 12 of the present example includes a capacitor including a pair of electrodes 120 and 121 sandwiching the pipe 15, and includes an oscillation circuit 122 and a frequency counter 123 that apply a voltage that resonates to the capacitor. If the dielectric constant of the particles 17 existing in the observation region 18 is different from the dielectric constant of the fluid in the pipe 15, the presence of the particles 17 causes the capacitance of the capacitor to fluctuate, and the capacitance fluctuation is caused by the oscillation frequency applied from the oscillation circuit 122. Affect. Therefore, if the fluctuation of the oscillation frequency is detected by the frequency counter 123, the presence of the particles 17 can be detected. In addition, since the magnitude of the frequency fluctuation has a correlation with the quantity of the particles 17, the quantity of the particles 17 can be measured by the magnitude of the frequency fluctuation.

  In the case of this example, the requirement required for the particles 17 is a difference from the dielectric constant of the fluid in the pipe 15. In order to greatly change the capacitance of the capacitor, it is preferable that the difference in dielectric constant is large. Further, since the electric flux needs to pass through the observation region 18, the pipe 15 and the fluid need to be insulators. According to the particle sensor 12 of this example, the number of particles 17 can be measured from the outside of the pipe 15 in a non-contact manner without performing any work on the pipe 15. Of course, it is possible to detect the variation in capacitance with higher sensitivity by applying the bridge circuit shown in FIG. 14 to the capacitor of this example.

E. Optical Method FIG. 17 is a block diagram showing still another example of the particle sensor 12. The particle sensor 12 of this example includes a laser oscillator 130, a light receiving element 131, and an amplifier 132, and irradiates the observation region 18 with an optical window 134 provided in the pipe 15 with the laser beam 133 generated by the laser oscillator 130. . If the particles 17 are present in the observation region 18, scattered light 135 is generated. The scattered light 135 passes through the optical window 134 and is taken out of the pipe 15 and can be detected by the light receiving element 131 through the optical system 136. Since the scattered light intensity is positively correlated with the amount of the particles 17, the number of the particles 17 can be measured by the output of the light receiving element 131 (the output of the amplifier 132).

  In the case of this example, the requirement required for the particles 17 is a difference in refractive index from the fluid in the pipe 15. Further, the fluid needs to transmit the laser beam 133. According to the particle sensor 12 of the present example, there is an advantage that the physical properties excluding the refractive index of the particles 17 do not cause a problem. Moreover, since the optical window 134 is provided in the piping 15, there is no restriction | limiting in the material. Note that the optical window 134 is not necessary if the pipe 15 itself transmits the laser beam 133.

  Although an example in which the scattered light 135 of the laser beam 133 is measured is shown here, the transmittance of the laser beam 133 can also be measured. In this case, the particles 17 need to be a substance that absorbs light having the wavelength of the laser beam 133. Even if the particle 17 does not have an absorption band of the wavelength, it may be possible to perform light transmittance measurement using two-photon absorption if laser light is used. In the case of measurement using light absorption, the light source need not be a laser. It is also possible to measure the light absorption of the particles 17 using incoherent light. Needless to say, when performing light absorption measurement, the light receiving element is disposed at a position facing the light source.

F. Gas Sensor FIG. 18 is a block diagram showing still another example of the particle sensor 12. The particle sensor 12 of this example has a configuration in which the gas sensor 140 is disposed inside the pipe 15. The gas sensor 140 is connected to the sensor detection drive circuit 141 via the current introduction terminal 142. In the case of this example, when gas exists as the particle 17 in the pipe 15, the particle 17 can be appropriately measured. The gas sensor 140 is appropriately selected depending on the gas to be measured. For example, when the particle 17 is an unsaturated hydrocarbon gas such as formaldehyde, toluene, xylene, etc., a hot wire semiconductor gas sensor can be exemplified. When the particles 17 are, for example, carbon monoxide, a constant potential electrolytic gas sensor can be used.

3. Application of Specific Configuration Example to Basic Configuration The specific configurations of the particle capturing unit and the particle sensor described above can be appropriately selected and applied to the particle measurement system of Configuration Example 1 or Configuration Example 2 described above. However, there are specific configurations that cannot be applied depending on the physical properties of the particles 17, the pipes 15 and the fluid. Hereinafter, the applicability of the application will be described.

  The particle sensor 12 described above can be classified into five types depending on the physical phenomenon underlying the particle sensor 12. That is, a method of measuring using eddy current generated in the particles 17 (hereinafter referred to as “Iw method”) and a method of measuring fluctuations in the external magnetic field affected by the presence of the particles 17 (hereinafter referred to as “Mg method”). ), A method of measuring capacitance variation affected by the presence of the particles 17 (hereinafter referred to as “Cap method”), an optical method (hereinafter referred to as “Pho method”), a method using a gas sensor (hereinafter referred to as “Gas method”). ).

  The Iw method requires that an alternating magnetic field reach the observation region 18 and that a current flow through the particle 17, so the particle 17 must not be an insulator, and the pipe 15 and the fluid are paramagnetic. It is necessary to be.

  The Mg system requires that the external magnetic field reaches the observation region 18 and that the external magnetic field is affected by the presence of the particles 17. Therefore, in the Mg system, the particle 17 and the fluid need to have different magnetic permeability, and the pipe 15 needs to be a paramagnetic material. When the fluid is a paramagnetic material, the particle 17 may be a paramagnetic material as long as the magnetic permeability is different. However, since the influence (signal) on the external magnetic field is stronger, the particle 17 is ferromagnetic. It is preferably a body (ferrimagnetic or ferromagnetic).

  The Cap method requires that the electric flux reaches the observation region 18 and that the capacitance changes due to the presence of the particles 17. Therefore, in the Cap method, the pipe 15 and the fluid need to be insulators. The particle 17 and the fluid must have different dielectric constants, but the particle 17 must not be a conductor because of the definition of the dielectric constant.

  The Pho method requires light to reach the observation region 18 and be scattered (reflected) or absorbed by the presence of the particles 17. Therefore, in the Pho system, the pipe 15 and the fluid must be light transmissive, and the refractive index of the particle 17 and the fluid must be different or the particle 17 needs to have a light absorption rate. In addition, when providing an optical window in the piping 15, the material of the piping 15 does not become a problem. Further, since there is an interface between the particle 17 and the fluid, the refractive index of the particle 17 does not become a problem unless the refractive indexes match with extremely high accuracy. Therefore, in the Pho system, there are no major restrictions on the particles 17 and the pipes 15 except that the fluid is required to have optical transparency.

  The Gas method requires that the sensitivity of the sensor be in the observation target particle 17 (gas). As long as a gas sensor suitable for the gas to be observed is selected, there are no restrictions on the particles 17, the pipe 15, and the fluid.

  The particle capturing means described above can also be classified into four types depending on the physics based on the particle capturing means. That is, a system for capturing particles by a magnetic action (hereinafter referred to as “Mg system”), a system for capturing by electrostatic action (hereinafter referred to as “Ele system”), a system for capturing particles by a physical action (hereinafter referred to as “Me”). System ”) and a method of capturing by an adsorption method (hereinafter referred to as“ Ads method ”).

  In the Mg system, since the magnetic field needs to reach the particles 17 and the particles 17 need to be attracted by the magnetic action, the particles 17 are ferromagnetic and the pipe 15 and the fluid need to be paramagnetic. There is.

  In the Ele system, since the electric field reaches the particles 17 and it is necessary to be able to impart electric charges to the particles 17, the electrical properties of the particles 17 are not questioned, but the pipe 15 and the fluid need to be insulators.

  In the Me system, it is sufficient if the particles 17 are mechanically captured. Therefore, there are no restrictions on the electrical and magnetic properties of the particles 17, the pipe 15 and the fluid. On the other hand, there are no restrictions on the electrical and magnetic properties of the particles 17, the pipes 15, and the fluid in the Ads system. However, it is necessary that the particles 17 be a gas or a fine granular material equivalent to this.

  The table shown in FIG. 19 summarizes whether or not the particle sensor and the particle capturing means in each of the systems described above can be applied depending on the physical properties of the particle 17 and the pipe 15. FIG. 19 is a table summarizing whether or not each specific means of the particle sensor and the particle capturing means in the present embodiment is applicable depending on the physical properties of the particles 17 and the pipe 15. In the table, the fluid is an insulator and a paramagnetic material. Of course, even when the fluid is a magnetic fluid or a conductor (electrolyte), the specific configurations of the particle sensor and the particle capturing means described above may be applicable. However, in many cases, an insulator and a paramagnetic material such as water or oil will be applied as a fluid, and the table is created assuming these cases.

  In the figure, “◯” indicates that it is applicable, “×” indicates that it is not applicable, and “Δ” indicates that it is applicable but it is preferable to select other means. As shown in the figure, in any combination of the particle 17 and the pipe 15, by selecting a specific configuration of any one of the methods described above as the particle sensor and the particle capturing unit, the configuration example 1 or the configuration example 2 A particle weighing system can be realized.

  According to the particle metering system of the present embodiment, it is possible to measure particles 17 with extremely small density with high accuracy. This is realized by capturing the particles 17 by the first particle capturing means 11 and increasing the density in advance, and then measuring with the particle sensor 12. Here, even if a high-sensitivity sensor whose baseline fluctuation cannot be ignored is used as the particle sensor 12, as long as the particle 17 is captured by the particle capturing means 11, the particle 17 does not exist in the observation region 18 of the sensor. Or, even if it exists, the amount is very small, so that the calibration of the particle sensor 12 can be performed.

  According to the particle weighing system of the configuration example 2 of the present embodiment, in addition to the above-described effects, there is an effect that the particle sensor 12 can be calibrated reliably. That is, at the time of calibration of the sensor, it is necessary to perform calibration after performing the particle releasing operation in the first particle capturing unit 11 in order to avoid the mixing of noise accompanying the operation of capturing and releasing the particle 17. There is. Here, it suffices if calibration can be completed before the particles 17 reach the observation region 18; otherwise, the accuracy of the calibration may decrease (some particles in the course of calibration reach the observation region). Resulting in). In order to increase the accuracy of calibration, it is necessary to dispose the first particle capturing unit 11 and the particle sensor 12 sufficiently apart from each other. However, if the separation is too far, the particles 17 concentrated by the first particle capturing unit 11 are observed in the observation region 18. The effect of particle concentration is reduced by diffusing by the time it reaches. Therefore, in the configuration example 2, even if the second particle capturing means 28 is provided and the particles 17 diffuse, a means for concentrating the particles 17 again is provided. As a result, the distance between the first particle capturing means 11 and the particle sensor 12 can be made sufficiently long to ensure time for calibration.

  In the particle metering system of Configuration Example 2, even if the particles 17 are diffused, the particles 17 are collected again in the observation region 18 by the second particle capturing means 28, so that the influence of diffusion can be eliminated. This means that the observation result is not affected by the flow velocity of the fluid and that stable measurement is possible.

  FIG. 20 is a graph showing the result of actual particle weighing performed by the particle weighing system according to the present embodiment. In FIG. 20, the vertical axis represents sensor output (arbitrary scale), and the horizontal axis represents time (arbitrary scale). Line 150 is an experimental result by the particle weighing system of Configuration Example 2, and line 151 is an experimental result by the particle weighing system of Configuration Example 1. As the particle sensor 12, the above-described B.I. A specific configuration of the eddy current utilization method (2) is applied, and the above-described B. The specific configuration of solenoid type magnet was applied. The piping 15 was vinyl piping, engine oil was used as fluid, and iron powder was used as particles 17. The iron powder concentration in the engine oil was 50 ppm. Further, the capturing time in the first particle capturing means 11 is 10 minutes. At time t1, the first particle capturing unit 11 performs a particle releasing operation (in the case of the configuration example 2, the capturing of the second particle capturing unit 28 is started simultaneously). Line 152 shows the baseline variation.

  As shown in the figure, the signal level (width indicated by the arrow 153) of the line 150 (in the case of the configuration example 2) is significantly larger than the signal level (width indicated by the arrow 154) of the line 151 (in the case of the configuration example 1). That is, in the configuration example 2, a large signal level can be obtained. Of course, measurement is possible even with the line 151, but if the baseline fluctuation increases, the signal may be buried in the baseline fluctuation. It can be seen that the configuration example 2 having a large signal level is preferable for more stable measurement.

  Although the present invention has been specifically described above, it is needless to say that the present invention is not limited to the above-described embodiment and can be variously modified without departing from the gist thereof. For example, it is possible to change the measurement method of the particle weighing system in the embodiment as shown in FIG. That is, after measurement by the particle sensor (step 23), it is determined whether or not the measured value is equal to or greater than a threshold value (measurement threshold value) (step 160). If it is determined that the measured value is greater than or equal to the measurement threshold, the concentration is calculated in the same manner as in FIG. 6 (FIG. 3), and the result is further displayed (step 24). However, if it is determined that the measured value is not equal to or greater than the measurement threshold, it is determined whether the capture time is equal to or greater than the threshold (capture time threshold) (step 161), and the capture time is determined not to exceed the capture time threshold. The acquisition time is increased (step 162) and the measurement is repeated. On the other hand, if the capture time is equal to or greater than the capture time threshold, it is determined that particles cannot be detected, and the detection concentration is set to 0 (step 163). Such a method makes it possible to optimize the acquisition time.

  Moreover, the particle | grain measuring system of above-described embodiment is applicable to the deterioration test | inspection of the plant 170 as shown in FIG. That is, the particle measuring system described above is arranged in the pipe 172 connected to the plant 170 by the flange 171. In addition, although the case of the structural example 2 is illustrated in the figure, it cannot be overemphasized that the particle | grain measuring system of the structural example 1 may be sufficient.

  Usually, the fluid is always recirculated to the reaction tank or piping in the plant 170, and the inside of the reaction tank or piping is ground by the reaction in the plant or by the recirculating fluid itself. These abrasives are present as particles in the reflux liquid. By monitoring the ground particle concentration, the deterioration state of the plant can be monitored. In plants such as nuclear power generation, cooling water is recirculated for a long time at high temperature and high pressure, and its use is severe, and safety must be emphasized even though the load on piping and other members is large. I must. If this particle metering system is applied as a deterioration monitor of these plants, a very small amount of grinding particles can be detected with high sensitivity, so that deterioration can be detected at an early stage. Further, if the particle trapping means and the particle sensor are appropriately selected, the particle density can be measured from the outside of the pipe in a non-contact manner, so that it is not necessary to modify the plant for deterioration monitoring. Since it can be applied as a deterioration monitor regardless of the operation status of the plant, it can be applied to a plant that assumes continuous operation, and a great effect can be obtained.

  The present invention relates to a system and method for detecting low-concentration particles present in a fluid, and is applicable to the fields of general industrial measurement and deterioration monitoring of plants and engines.

It is a block diagram showing the 1st example of composition which is an example of the fundamental composition about the particle measurement system which is one embodiment of the present invention. It is a schematic diagram for demonstrating operation | movement of the particle | grain measuring system 10 of the structural example 1, (a) is the state where the particle | grains 17 are capture | acquired by the 1st particle | grain capture means 11, (b) is captured. The particle 17 is released and moved to the observation area 18 of the particle sensor 12. 5 is a flowchart illustrating an example of a measurement method of the particle weighing system 10 of the configuration example 1; It is the block diagram which showed the 2nd structural example which is another example of the fundamental structure about the particle | grain measuring system which is one embodiment of this invention. It is a schematic diagram for demonstrating operation | movement of the particle | grain measuring system 27 of the structural example 2, (a) is the state where the particle | grains 17 are capture | acquired by the 1st particle | grain capture | acquisition means 11, (b) is captured. The particle 17 is released and moved to the observation area 18 of the particle sensor 12. 5 is a flowchart showing an example of a measurement method of the particle weighing system 27 of Configuration Example 2. It is the block diagram which showed an example at the time of comprising the specific structure of a particle | grain capture | acquisition means as an electromagnet. It is the block diagram which showed an example at the time of comprising the specific structure of a particle | grain capture | acquisition means as a solenoid type magnet. It is the block diagram which showed an example at the time of comprising the specific structure of a particle | grain capture means as a motor drive magnet. It is the block diagram which showed an example at the time of comprising the specific structure of a particle | grain capture means as a charged dust collection system means. It is the block diagram which showed an example at the time of comprising the specific structure of a particle | grain capture | acquisition means as a mesh (network). It is the block diagram which showed an example at the time of comprising the specific structure of a particle | grain capture means as an adsorbent. 3 is a block diagram illustrating an example of a particle sensor 12. FIG. It is the block diagram which showed the other example of the particle sensor 12. FIG. FIG. 6 is a block diagram showing still another example of the particle sensor 12. FIG. 6 is a block diagram showing still another example of the particle sensor 12. FIG. 6 is a block diagram showing still another example of the particle sensor 12. FIG. 6 is a block diagram showing still another example of the particle sensor 12. It is a table | surface which put together whether each concrete means of the particle | grain sensor in this Embodiment and a particle | grain capture | acquisition means is applicable by the physical property of the particle | grains 17 and the piping 15. FIG. It is a graph which shows the result of having actually performed particle measurement by the particle measurement system which is one embodiment of the present invention. It is the flowchart which showed the other example of the measuring method of a particle | grain measuring system. It is a block diagram which shows an example at the time of applying a particle | grain measuring system to a plant.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Particle measuring system, 11 ... 1st particle capture means, 12 ... Particle sensor, 13 ... Control means, 14 ... Display apparatus, 15 ... Piping, 17 ... Particle, 18 ... Observation area, 27 ... Particle measuring system, 28 ... Second particle capturing means, 31 ... magnetic core, 32 ... coil, 33 ... power supply control circuit, 41 ... solenoid, 42 ... driving iron core, 43 ... permanent magnet, 44 ... power supply control circuit, 50 ... motor, 51 ... crank, 52 ... permanent magnet, 53 ... motor control circuit, 61 ... probe, 62 ... first electrode, 63 ... second electrode, 64 ... high voltage power supply, 65 ... control power supply, 66 ... control circuit, 67 ... current introduction terminal, 70 ... mesh , 71 ... Rotation introducing terminal, 80 ... Adsorbent, 81 ... Heater, 82 ... Heater power supply, 83 ... Control circuit, 90 ... Coil, 91 ... Oscillation circuit, 92 ... Frequency counter, 100 ... Excitation coil, 101 DESCRIPTION OF SYMBOLS 102 ... Sensor coil, 103 ... Oscillator, 104 ... Bridge, 105 ... Phaser, 106 ... Amplifier, 107 ... Synchronous detector, 110 ... Hall element, 111 ... Amplification / control device, 112, 113 ... Magnet, 114 ... External magnetic field , 120, 121 ... electrodes, 122 ... oscillation circuit, 123 ... frequency counter, 130 ... laser oscillator, 131 ... light receiving element, 132 ... amplifier, 133 ... laser light, 134 ... optical window, 135 ... scattered light, 136 ... optical system , 140 ... gas sensor, 141 ... sensor detection drive circuit, 142 ... current introduction terminal, 170 ... plant, 171 ... flange, 172 ... piping.

Claims (32)

A particle metering system for measuring the number or amount of particles present in a liquid or gas having a flow in a predetermined direction,
First particle capturing means for capturing the particles against the flow for a certain period of time and releasing the capturing of the particles at a predetermined timing;
A particle sensor disposed at a position downstream of the flow from the position where the first particle capturing means is disposed, and obtaining an output value corresponding to the number or amount of the particles in the observation region;
A particle metering system. The particle metering system according to claim 1, further comprising second particle capturing means for capturing the particles in a region including the observation region of the particle sensor. After the first particle capturing means releases the particles, the time until the released particles reach the observation region is longer than the time necessary for calibrating the particle sensor. 3. A particle metering system according to claim 2, wherein is disposed apart from the first particle capturing means. The particle measurement system according to any one of claims 1 to 3, wherein the particles include a magnetic material, and the particles are captured by using magnetic force. The particle metering system according to any one of claims 1 to 3, further comprising a charge imparting unit that imparts a charge to the particles, and capturing the particles using an electrostatic force. 2. The trapping of the particles is performed by a filtering unit that permeates a substance constituting the flow and inhibits the permeation of the particles, and the release of the trapping is performed by reversing the direction of the filtering unit with respect to the flow. The particle | grain measuring system as described in any one of -3. The particle metering system according to any one of claims 1 to 3, wherein the particles are captured by an adsorbent that selectively adsorbs the particles, and the capture is released by heating the adsorbent. . The particle includes a conductor or a semiconductor, the particle sensor includes an inductive element, and the particle or the semiconductor is caused by an eddy current in the conductor or the semiconductor due to an external AC magnetic field generated by the inductive element or the exciting inductive element. The particle measuring system according to any one of claims 1 to 7, wherein the number or amount of the particles is measured by an inductance change of the induction element. The particle includes a magnetic material, the particle sensor includes a magnetic field generation unit that generates a magnetic field, and a Hall element, and measures the number or amount of the particles based on a change in the magnetic field detected by the Hall element. Item 8. The particle weighing system according to any one of Items 1 to 7. The said particle | grain contains a dielectric material, The said particle | grain sensor contains a capacitive element, The number or quantity of the said particle | grains is measured by the change of the capacitance of the said capacitive element. Particle weighing system. The particle sensor has a laser light generating means and a means for measuring scattered light intensity of the laser light scattered by the particles, and measures the number or amount of the particles based on the scattered light intensity. Item 8. The particle weighing system according to any one of Items 1 to 7. The particle measuring system according to any one of claims 1 to 7, wherein the particles are gaseous molecules, and the particle sensor is a gas sensor that measures the number or concentration of the gaseous molecules. Measuring the number or amount of particles present in a liquid or gas having a flow in a predetermined direction, capturing the particles against the flow for a certain period of time, and releasing the capture of the particles at a predetermined timing; A particle sensor for obtaining an output value corresponding to the number or amount of the particles in the observation region disposed at a position downstream of the flow with respect to the position at which the first particle capturing unit is disposed. A particle weighing method using a particle weighing system comprising:
Capturing the particles for a predetermined capture time by the first particle capture means;
Releasing the trapped particles;
Performing calibration of the particle sensor after release of the particles;
Starting measurement by the particle sensor;
A particle weighing method. The particle metering system includes second particle capturing means for capturing the particles in a region including the observation region of the particle sensor,
Initiating capture of the particles by the second particle capture means during capture of the particles by the first particle capture means or after release of the captured particles and prior to calibration of the particle sensor. The particle weighing method according to claim 13. When the output value of the particle sensor is equal to or greater than a predetermined threshold, displaying the output value or a value calculated from the output value;
If the output value of the particle sensor is less than the predetermined threshold, changing the capture time longer and repeating the series of steps from capturing the particles by the first particle capturing means;
The particle weighing method according to claim 13 or 14, wherein: The particle weighing method according to claim 15, wherein when the capturing time is equal to or greater than a predetermined threshold, it is determined that the particles cannot be detected. A plant deterioration detection system for detecting deterioration of the pipe or a reaction tank of the plant in a plant having a pipe through which a fluid flows.
The particles that are arranged outside the piping and capture the particles constituting the piping or the reaction tank of the plant against the fluid flow or the particles made of the compound of the materials for a certain time and capture the particles at a predetermined timing. First particle trapping means for releasing
An output value corresponding to the number or amount of the particles in the observation region, which is disposed outside the pipe and at a position downstream of the flow from the position where the first particle capturing unit is disposed, is obtained. A particle sensor;
A plant deterioration detection system. The plant deterioration detection system according to claim 17, further comprising second particle capturing means for capturing the particles in a region including the observation region of the particle sensor. After the first particle capturing means releases the particles, the time until the released particles reach the observation region is longer than the time necessary for calibrating the particle sensor. The plant deterioration detection system according to claim 18, wherein the plant deterioration detection system is disposed apart from the first particle capturing means. The plant deterioration detection system according to any one of claims 17 to 19, wherein the particles are a magnetic body, and the particles are captured using magnetic force. The plant deterioration detection system according to any one of claims 17 to 19, further comprising a charge imparting unit configured to impart a charge to the particles, and capturing the particles using an electrostatic force. 18. The trapping of the particles is performed by a filtering unit that permeates a substance constituting the flow and inhibits the permeation of the particles, and the release of the trapping is performed by reversing the direction of the filtering unit with respect to the flow. The plant deterioration detection system as described in any one of -19. The plant deterioration detection according to any one of claims 17 to 19, wherein the particles are captured by an adsorbent that selectively adsorbs the particles, and the capture is released by heating the adsorbent. system. The particle is a conductor or a semiconductor, the particle sensor includes an induction element, and the inductance of the induction element due to an eddy current inside the particle due to an external AC magnetic field generated by the induction element or the excitation induction element The plant deterioration detection system according to any one of claims 17 to 23, wherein an output value of the particle sensor is obtained by a change. The particle is a magnetic substance, and the particle sensor includes a magnetic field generating means for generating a magnetic field and a Hall element, and an output value of the particle sensor is obtained by fluctuation of a magnetic field detected by the Hall element. The plant deterioration detection system as described in any one of -23. The particles are made of a material having a dielectric constant different from the dielectric constant of the material constituting the fluid, the particle sensor includes a capacitive element, and the output value of the particle sensor is determined by a change in capacitance of the capacitive element. The plant degradation detection system as described in any one of Claims 17-23 obtained. The particle sensor has a laser light generating means and a means for measuring a scattered light intensity of the laser light scattered by the particles, and an output value of the particle sensor is obtained by the scattered light intensity. The plant deterioration detection system according to any one of 17 to 23. The plant deterioration detection system according to any one of claims 17 to 23, wherein the particles are gaseous molecules, and the particle sensor is a gas sensor that measures the number or concentration of the gaseous molecules. Deterioration of the pipe or the reaction tank of the plant in a plant having a pipe through which a fluid flows is detected, and the pipe or the reaction tank of the plant is disposed outside the pipe and resists the flow of the fluid. From the position where the first particle capturing means for capturing the particles made of the constituent material or the compound of the material for a certain period of time and releasing the capturing of the particles at a predetermined timing, and the position where the first particle capturing means is disposed And a particle sensor that is located downstream of the flow and outside the pipe and obtains an output value corresponding to the number or amount of the particles in the observation region. A degradation detection method,
Capturing the particles for a predetermined capture time by the first particle capture means;
Releasing the trapped particles;
Performing calibration of the particle sensor after release of the particles;
Starting measurement by the particle sensor;
A method for detecting plant deterioration. The plant deterioration detection system includes second particle capturing means for capturing the particles in a region including the observation region of the particle sensor,
Initiating capture of the particles by the second particle capture means during capture of the particles by the first particle capture means or after release of the captured particles and prior to calibration of the particle sensor. The plant degradation detection method of Claim 29 which has these. When the output value of the particle sensor is equal to or greater than a predetermined threshold, displaying the output value or a value calculated from the output value;
If the output value of the particle sensor is less than the predetermined threshold, changing the capture time longer and repeating the series of steps from capturing the particles by the first particle capturing means;
The plant deterioration detection method according to claim 29 or 30, wherein: 31. The plant deterioration detection method according to claim 29 or 30, further comprising a step of issuing an alarm when an output value of the particle sensor is equal to or greater than a predetermined second threshold value.

Images