JP2008232741A - Liquid flow sensor, clean water supply system using this, intra-specimen selenium dioxide eliminator, and measuring instrument for mercury in coal combustion exhaust gas using these - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid flow sensor for accurately measuring the flow of a colorless solution such as pure water and a liquid containing weak salts, having a simple structure, and having high operability, a clean water supply system using this, an intra-specimen selenium dioxide eliminator, and a measuring instrument for mercury in coal combustion exhaust gas using these. <P>SOLUTION: This liquid flow sensor 10 comprises a liquid dropping part 1 at its upper part and a measurement part 2 at its intermediate part, and comprises a transmissive photodetector 4 consisting of a light emission part 4a and a light reception part 4b at the measurement part 2. This flow sensor 10 is characterized in that detection light at the detection part 4 passes through an end part 1a of the dropping part 1 and a liquid drop D can be detected just before it parts from the dropping part 1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid flow sensor, a cleaning liquid supply system using the same, a selenium oxide removing device in a sample, and a mercury measuring device in coal combustion exhaust gas using these.

  Conventionally, a droplet detection type flow meter using a liquid dropping device has been reported as many products and researches as a simple optical liquid flow meter. Both are used to monitor or control the flow rate of liquid from a small flow rate pump or head tank. Specifically, several droplet detection type flow meters as exemplified below have been proposed.

  For example, as shown in FIG. 12, a droplet detection type flow meter for use in a liquid feed pump has been proposed as a part of a constant liquid constant supply device. Specifically, it includes a liquid storage tank 61, a liquid feed pump 64a, a liquid storage container 55, a liquid constant speed supply device 40, a liquid receiver 64b, pressure adjusting valves 68 and 69, and a pressurizing device 67. The liquid constant speed supply device 40 includes a main body 41 and a droplet sensor 49, and a light emitting diode 50 and a light receiving diode 51 are installed inside the droplet sensor 49 (see, for example, Patent Document 1). .

  Such a droplet detection type flow meter has a high uniformity of formed droplets and can form droplets with a constant liquid amount when the physical and chemical stability of the measurement target is high. Therefore, a highly accurate liquid flow meter can be configured. Therefore, it is frequently used as a liquid flow meter useful in the medical field and various industrial fields where very strict control management is required as in recent years.

Japanese Patent Laid-Open No. 01-209321

  However, when measuring a colorless solution such as liquid containing pure water or dilute salt using the above-described droplet detection type flow meter, accurate flow rate measurement may not be possible. In particular, when a predetermined time elapses after the droplet formation, and when the detection light is irradiated to a position away from the portion (hereinafter referred to as “droplet portion”) that starts to drop and starts to drop, as described later, The output from the light receiving unit for one droplet sometimes counts 2 or more, and a normal pulse cannot be obtained and accurate flow rate measurement cannot be performed.

  In other words, in the liquid drop detection type flow meter used for the liquid feeding pump as described above, a large amount of pharmaceuticals, nutrients and salts are contained, the refractive index is large, and abnormal pulses due to transmitted light are unlikely to occur. An abnormal value of the transmission signal of the droplet hardly occurs, and detection of the pulse signal is relatively easy. On the other hand, since the detection sensor signal of the transmitted light signal of a liquid droplet containing pure water or dilute salt is likely to generate an abnormal pulse, the conventional droplet detection mechanism has a problem in monitoring the flow rate of various liquids. It was. Depending on the size of the droplet, the abnormal pulse generation mode may be divided into two or more. When an abnormal pulse occurs, the number of droplets by the pulse counter does not match the number of counts, and normal flow rate measurement cannot be performed. The liquid drip sensor of an infusion pump used in hospitals and medical applications is structurally unsuitable for industrial applications.

  Furthermore, liquid flow meters that can accurately measure the flow rate of liquids containing pure water or dilute salts are strongly demanded in various applications such as cleaning solutions for semiconductor manufacturing facilities, processing solutions, or pure water supply devices for chemical reactions. was there. In such applications, the product characteristics are greatly influenced by the control accuracy of the flow rate of the solution, and thus the liquid flow meter requires strict accuracy. Therefore, the above problem cannot be ignored.

On the other hand, in a continuous measurement device such as mercury for coal combustion exhaust gas, in order to prevent the generation of elemental selenium (Se) from selenium oxide (SeO ₂ ) present in exhaust gas that interferes with mercury measurement, There has been a demand for a method and apparatus for removing this stably over a long period of time with a simple operation. Recently, the present inventors have verified that it is possible to quantitatively remove SeO ₂ present in exhaust gas using a liquid containing pure water or dilute salts. Was an issue to be considered.

  In view of this, the present invention responds to such a demand by providing a colorless solution such as a liquid containing pure water or dilute salts (here, “colorless solution” means a solution that does not absorb the wavelength (wavelength range) of the detection light to be irradiated. It is an object of the present invention to provide a liquid flow sensor having a simple structure and high operability, and a clean water supply system using the same. In addition, by applying such a liquid flow sensor or clean water supply system to mercury measurement in coal combustion exhaust gas, etc., a selenium oxide removal device in a sample that removes it stably over a long period of time with a simple operation, and It is an object of the present invention to provide a method and apparatus for measuring mercury in coal combustion exhaust gas that can be continuously measured with high accuracy and high long-term stability without being affected by coexisting components.

  As a result of extensive research, the inventor has conducted the following liquid flow sensor, clean water supply system using the same, selenium oxide removal device in the sample, and mercury measurement device in coal combustion exhaust gas using the same. Thus, the inventors have found that the above object can be achieved, and have completed the present invention.

  The present invention relates to a liquid flow sensor having a liquid droplet part in the upper part and a measuring part in the middle part, and a transmission-type photodetector comprising a light emitting part and a light receiving part in the measuring part. , Detecting a droplet immediately before being separated from the droplet portion.

  When measuring the flow rate of a liquid that has a droplet formation unit and counts the formed droplets to convert the flow rate, it is necessary to perform accurate counting along with the uniformity of the liquid amount of each droplet formed . As described above, when the measurement target is a colorless solution, it has been found that accurate counting is hindered by the position of the photodetector. As a result of verifying such a phenomenon by the present inventor, when the detection light focused on a minute area is irradiated near the center of the falling liquid droplet in the form where the liquid droplet is close to a sphere, most of the detection light is transmitted. As a result, it was estimated that accurate counting would be inhibited. As one of such measures, the present invention applies a method of detecting a droplet before the droplet becomes a shape close to a sphere, and the droplet just before being separated from the droplet portion where the droplet is formed. Is detected. As a result, accurate counting can be performed.

  In other words, the detection light applied to the drop side near the tip of the droplet portion has a large difference in the amount of transmitted light immediately before and after the droplet is separated from the tip regardless of the shape of the droplet. Specifically, immediately before the separation, in addition to the reflection at the boundary surface between the liquid and the air on the droplet surface, a decrease in transmitted light reaching the light receiving part due to an increase in the refracted light occurs, while after separation. In this case, it is estimated that the liquid droplets can be accurately counted by detecting the light amount difference when the decrease in the transmitted light amount can be maintained below the predetermined light amount. This makes it possible to provide a liquid flow rate sensor that can accurately measure the flow rate of a colorless solution such as liquid containing pure water or dilute salts, and has a simple structure and high operability.

  The present invention relates to a liquid flow sensor having a liquid droplet part in the upper part and a measuring part in the middle part, and having a transmission type photodetector comprising a light emitting part and a light receiving part in the measuring part, And a nozzle portion made of a water-repellent material having an inner diameter d1 / outer diameter d2, and the detection light of the light detector is a distance L ≦ d1 × 1.5 from the front end portion of the droplet portion. It is characterized by passing through the measuring part.

  As described above, the present inventor has estimated that the accurate count in the droplet detection type flow rate measurement is hindered. The second aspect of the present invention applies a method for detecting a droplet before the droplet is in a form close to a sphere, as described above, as a second technique for such countermeasures. It is characterized in that the photodetector is disposed at a position at a predetermined distance from the tip of the droplet part. As a result, accurate counting can be performed.

  In other words, by using a water repellent material such as PTFE (fluorine resin) or a water repellent treatment for the nozzle portion, as shown in FIG. In addition, the separation from the nozzle portion 1c becomes smooth, and a droplet without splashing can be formed. In addition, this allows the droplet D to have a shape close to a sphere relatively quickly, and the time (falling distance) can be made substantially constant. On the other hand, the droplet D immediately after being separated from the nozzle portion 1c has a shape resembling a reed shape or a reed shape that is being stretched, and is non-uniform in shape in both the vertical and horizontal directions. Therefore, in addition to the reflection at the boundary surface between the liquid and the air on the droplet surface, the transmitted light that reaches the light receiving portion (not shown) is reduced as the refracted light increases. Therefore, it is possible to set a region where the transmitted light is reduced due to the passage of droplets by removing the region where accurate counting is inhibited as described above, and a colorless solution such as a liquid containing pure water or dilute salts It is possible to provide a liquid flow rate sensor that can accurately measure the flow rate of the liquid and has high operability with a simple structure. As a result of the demonstration, the specific setting region for transmitted light is optimally a region corresponding to a ratio in a predetermined range with respect to the inner diameter of the droplet portion. In addition, when the nozzle part 1c corresponds to the separation part of a droplet as shown in FIG. 1, the “tip part of the liquid droplet part” corresponds to the tip part of the nozzle part 1c, and the nozzle part 1c corresponds to the liquid part. When the entire droplet portion 1 is on the same plane as the tip portion (for example, FIG. 4B) and the entire surface corresponds to the droplet separation portion, the tip portion of the entire droplet portion 1 corresponds.

  The present invention relates to a liquid flow sensor having a liquid droplet part in the upper part and a measuring part in the middle part, and having a transmission type photodetector comprising a light emitting part and a light receiving part in the measuring part, And a nozzle portion made of a hydrophilic material having an inner diameter d1 / an outer diameter d2, and the detection light of the light detector is a distance L ≦ d2 × 2.5 from the tip portion of the droplet portion. It is characterized by passing through the measuring part.

  As described above, the present inventor has estimated that the accurate count in the droplet detection type flow rate measurement is hindered. The third aspect of the present invention applies a method for detecting a droplet before the droplet becomes a shape close to a sphere, as described above, as a third method for such measures, and the nozzle portion is made of a hydrophilic material, It is characterized in that the photodetector is disposed at a position at a predetermined distance from the tip of the droplet part.

  That is, by using a hydrophilic material such as glass or a hydrophilic treatment for the nozzle portion, as shown in FIG. 1B, in forming the droplet D, a larger droplet D is formed with respect to the solution. The surface tension generated when the solution is separated from the solution remaining in the nozzle portion 1c is increased (that is, the contact angle θ is small). As a result, the time (drop distance) until the droplet D becomes a sphere is long. As a result of the demonstration, the specific setting region for transmitted light is optimally a region corresponding to a ratio of a predetermined range to the outer diameter of the droplet portion. Therefore, it is possible to set a wide range in which the transmitted light is reduced due to the passage of the droplet as described above, and it is possible to accurately measure the flow rate of a colorless solution such as a liquid containing pure water or dilute salts, and simple. It has become possible to provide a liquid flow sensor with a structure and high operability.

  The present invention is a liquid flow sensor having a liquid droplet part in the upper part and a measuring part in the middle part, and having a transmission type photodetector comprising a light emitting part and a light receiving part in the measuring part, The central axis of the detection light has an inclination of 20 to 40 ° with respect to the drop trajectory of the droplet of the measurement unit.

  As described above, the present inventor has estimated that the accurate count in the droplet detection type flow rate measurement is hindered. The fourth aspect of the present invention is a method for detecting a droplet under conditions that cause a decrease in transmitted light passing through the droplet, utilizing the fact that the falling droplet does not become a perfect sphere, as a fourth technique for such measures. The detection light is characterized in that the central axis of the detection light has a predetermined inclination angle with respect to the drop trajectory of the droplet of the measurement unit.

  That is, the falling droplet D has a shape close to an elliptical shape elongated in the direction of gravity, as illustrated in FIG. 1C, except for special conditions such as weightlessness. Therefore, since the central axis M of the detection light has a predetermined inclination angle α with respect to the drop trajectory T of the droplet of the measurement unit, the transmitted light reaching the light receiving unit 4b is reduced as the refracted light increases. The resulting conditions can be ensured. As a result of the demonstration, it was found that setting the inclination angle α within a predetermined range does not hinder accurate counting in almost the entire region of the measurement unit. Therefore, it is possible to set a wide range in which transmitted light is reduced due to the passage of the droplet D as described above, and it is possible to accurately measure the flow rate of a colorless solution such as a liquid containing pure water or dilute salts, and simple. It has become possible to provide a liquid flow sensor with a simple structure and high operability.

  The present invention is a cleaning liquid supply system using any one of the liquid flow rate sensors described above, wherein a feeding means, a flow control means, and the liquid are supplied to a flow path for supplying the cleaning liquid or the used cleaning liquid after the regeneration process. The flow rate sensor is arranged in series or in parallel.

  Droplet detection type flowmeters are widely used in various applications including medical use due to their high measurement accuracy, while accurate counts are impeded in clean liquids including pure water and dilute salts as described above. It was essential to take measures against these factors. The present invention uses any one of the above liquid flow rate sensors as one of the components of the cleaning liquid supply system, so that even such cleaning liquid can be accurately measured and operated with a simple structure. It becomes possible to provide a highly purified water supply system.

The present invention includes (1) a heating introduction path for heating a sample,
(2) a primary cooling section having a flow path in which the flow of the heated sample and the flow of cooling water face each other and mixing the sample and the cooling water to rapidly cool the flow;
(3) a secondary cooling unit having a spiral flow path for cooling the mixed gas and having a space for gas-liquid separation at the end of the spiral flow path;
(4) a regenerator for introducing condensed water from the secondary cooling section;
(5) a cooling water supply path connecting the regenerator and the primary cooling unit;
An apparatus for removing selenium oxide in a sample having
One of the liquid flow rate sensors is provided in a cooling water supply flow path to the primary cooling unit.

In recent years, in mercury measurement in exhaust gas, as one of the major causes of remarkably reducing the measurement accuracy, it was found that SeO ₂ present in the sample tends to form mercury and amalgam during the reduction reaction. It was difficult to remove SeO ₂ without affecting the mercury measurement. In the verification by the present inventors, rapid cooling and washing are simultaneously performed by continuously adding clean water to the exhaust gas, and the element Se, which is an interfering substance for mercury measurement in the subsequent sample piping and cooling dehumidifier. It was found that precipitation can be prevented. At this time, if the flow rate of clean water in the clean water supply system decreases or stops, the temperature of the sample gas and the amount of water decrease, selenium oxide in the coexisting gas is reduced, Se is deposited, and hinders mercury measurement. Therefore, continuous monitoring of the flow rate of clean water and control of the flow rate based on it are necessary for continuous continuous addition of clean water.

Specifically, in the primary cooling section, the sample containing SeO ₂ is rapidly cooled from the heating temperature of 100 to 200 ° C. to the ambient atmosphere temperature (usually about 0 to 30 ° C.), thereby removing moisture from the sample. The resulting dissolution in condensed water can be accelerated, and the reaction of the following formula 1 can be promoted. However, at this time, the presence of water droplet-like condensed water induces the precipitation of Se by dissolution of SO ₂ , so that by supplying cooling water, an effect of washing away from the flow path is produced, and Se It is possible to suppress the precipitation of. In addition, the supply of cooling water promotes the dissolution of SeO _{2 into} the cooling water, and can also obtain a dilution effect of dissolved H ₂ SeO ₃ and SO ₂ . Furthermore, it becomes possible to further reduce the formation reaction of amalgam with mercury by lowering the temperature with cooling water. Further, such a technical effect has a flow path in which the flow of the heated sample and the flow of the cooling water are opposed to each other, and the effectiveness can be improved by mixing the sample and the cooling water and rapidly cooling.
SeO ₂ + H ₂ O → H ₂ SeO ₃ .. (Formula 1)

Further, in the secondary cooling section, a sample gas from which SeO ₂ is removed while producing amalgam is produced by performing a gas-liquid separation process while further cooling the mixed gas in a spiral flow path. Made possible. In other words, by cooling the narrow spiral channel, it is provided at the end of the spiral channel while preventing the generation of droplets and splashes in the channel due to the transfer of mixed gas and the generation of condensed water. The gas-liquid separation process can be effectively performed in the space formed.

Furthermore, it is not necessary to continuously supply the cooling water for the primary cooling process from the outside, but to use the condensed water obtained by the gas-liquid separation process as the cooling water supplied to the primary cooling unit. Or it is also preferable from the viewpoint of reducing the burden of wastewater treatment. That is, the amount of water-soluble substances such as SeO ₂ contained in the sample is very small, and selenite etc. can be removed relatively easily by circulating the condensed water through a regenerating means such as an ion exchange resin. . Further, when coal combustion exhaust gas is used as a sample, the sample contains a large amount of water and does not require replenishment of cooling water. Therefore, such circulation recycling is suitable for long-term specifications.

With the configuration described above, it has become possible to provide an apparatus for removing SeO ₂ in a sample stably for a long period of time with a simple operation.

The present invention is a mercury measuring device using the cleaning liquid supply system or the selenium oxide removing device in the sample,
Using a coal combustion exhaust gas as a measurement target sample, a sample collection unit for collecting the sample, a sample introduction path for heating and introducing the sample from the sample collection unit, the removal device, and a mercury analyzer It is characterized by that.

In the measurement of mercury in exhaust gas, it is possible to measure mercury in coal combustion exhaust gas by reducing the mercury compound and measuring it as atomic mercury using an absorptiometric method. Found that it was necessary to overcome several challenges that were not possible before. In particular, SeO ₂ present in the exhaust gas is one of the major causes of remarkably reducing the measurement accuracy because it is easy to produce mercury and amalgam during the reduction reaction. By using a selenium oxide removing device in the sample and eliminating this influence, it is possible to ensure measurement accuracy that was not possible with the conventional method. Therefore, it has become possible to provide a method and an apparatus for measuring mercury in coal combustion exhaust gas that can be continuously measured with high accuracy and high long-term stability without being affected by coexisting components.

As described above, according to the present invention, it is possible to accurately measure the flow rate of a colorless solution such as a liquid containing pure water or dilute salts, which has been difficult to accurately measure conventionally, and has a simple structure and high operability. It has become possible to provide a flow sensor and a clean water supply system using the same. In addition, by applying such a liquid flow sensor or clean water supply system to mercury measurement in coal combustion exhaust gas, generation of element Se from SeO ₂ present in the disturbing exhaust gas is prevented, and simple The selenium oxide removal device in the sample that removes it stably for a long time by operation, and coal combustion that uses these, is not affected by coexisting components, and is highly accurate and has long-term stability and capable of continuous measurement It has become possible to provide a method and apparatus for measuring mercury in exhaust gas.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, regarding a liquid flow rate sensor according to the present invention (hereinafter referred to as “the present flow rate sensor”), a cleaning liquid supply system using them, a selenium oxide removal device in a sample, and a mercury measurement device in coal combustion exhaust gas explain.

<Configuration of this flow sensor>
As shown in FIG. 2, the basic of the present flow sensor has a liquid droplet part 1 at the upper part, a measuring part 2 at the middle part, and a liquid receiving part 3 at the lower part. The liquid flow rate sensor 10 having a transmission type photodetector 4 consisting of 4b and an integrating counter 5 to which the output of the photodetector 4 is connected. The output of the light detector 4 is counted by the integration counter 5, and the flow rate of the solution passing through the liquid flow rate sensor 10 is calculated by multiplying the unit volume per droplet D set in the liquid flow rate sensor 10. be able to. In addition to such a basic configuration, the present invention provides several methods for accurately detecting changes in light transmitted through droplets due to a colorless solution such as liquid containing pure water or dilute salts as a measurement target. This is realized by the configuration example. In addition, this method has a feature that the application range is wide because the measurement system does not affect the measurement even in a reduced pressure or pressurized system.

  Here, the material of the flow sensor 10 is not particularly limited in the case of a non-corrosive solution such as pure water, except for the droplet portion 1 described later, but for confirming the falling state of the droplet D. The measurement unit 2 is preferably made of transparent glass or plastic.

  As shown in FIG. 2, the droplet portion 1 includes a tip portion 1a where the droplet D falls, a solution flow channel 1b therein, and a nozzle portion 1c having an inner diameter d1 / outer diameter d2. . The size of the nozzle portion 1c varies depending on the flow rate of the solution to be measured. For example, the nozzle portion 1c having an inner diameter d1 = 4 mm / outer diameter d2 = 6 mm is normally used at about 1 to several tens ml / min. In addition, the size and shape of the droplet D falling from the tip portion 1a varies depending on the material of the droplet portion 1 or the surface treatment of the droplet portion 1, and the abnormal output of the photodetector 4 is generated by the nozzle portion. It is determined by the material of 1c and the position of the photodetector 4 from the tip 1a (dropping distance of the droplet D), and the optimum conditions can be set in accordance with the arrangement of the photodetector 4. preferable. Details will be described later.

  The light detection unit 4 is not limited to a transmission type or a reflection type as long as it is a sensor capable of measuring the droplet D. However, in the present invention in which the measurement target is a colorless solution, it depends on the presence or absence of the droplet D. In order to reduce the influence of the difference in the detection light, the deviation of the droplet D from the center of the drop trajectory T, the change in the size or shape of the droplet D, and to ensure high detection accuracy, A transmission type photodetector 4 having a light spot (for example, a spot diameter of 1 to 5 mm) is preferable. Specifically, it is preferable to configure the photodetector 4 in which the light emitting unit 4a and the light receiving unit 4b are integrated using a photodiode or a phototransistor in a visible to infrared region (400 to 1000 nm). A commercially available small-sized sensor with high detection sensitivity can be used (for example, OMRON's EE-SPX series).

  In the integration counter 5, as illustrated in FIGS. 3A to 3C, a condition for capturing a transmitted light signal pattern (pulse signal) for one formed droplet D with one droplet to one pulse signal is set. By doing so, it is possible to accurately detect the number of droplets per hour. Accordingly, an output with good linearity can be obtained in a wide flow rate range, so that a wide range of flow rate control is possible. Moreover, it is preferable to set the detection sensitivity of the pulse counter according to the output level from the light detector 4, and the configuration of the droplet portion 1 such as the inner diameter d1 / outer diameter d2 of the nozzle portion 1c and the light detector of the measuring portion 2 4 can be set as a fixed value t (for example, 0.1 msec or 0.05 msec). That is, as shown in FIG. 3B, if the transmitted light amount when there is no droplet D is Io, the transmitted light amount decreases to Ia when the droplet D exists at position a in FIG. At positions b and c, Ib and Ic (≈Ia) respectively. As shown in FIG. 3C, stable and accurate counting can be performed by setting Ia at this time to a count level and setting a time t until Ic at substantially the same level as a fixed value.

  In addition, when the measuring unit 2 is formed of a transparent material such as glass, the flow rate can be easily monitored by observing the liquid drop flow condition in addition to the flow rate monitoring by the pulse counter based on the light detection signal. It can be carried out.

  In measuring the flow rate, it is necessary to consider the temperature effect of the solution. Since the number of droplets D dropped from the nozzle portion 1c and the amount of droplets affect the temperature change in the viscosity and surface tension of the liquid temperature, the relationship between the liquid temperature and the flow rate is obtained in advance, and the liquid temperature is measured simultaneously. Then, by multiplying the correction coefficient and performing flow rate correction, the influence of the flow rate due to temperature can be corrected.

[First configuration example of the flow sensor]
The first configuration example of the present flow sensor is characterized in that the photodetector 4 detects the droplet D immediately before being separated from the droplet portion 1. In other words, in the conventional method, when the detection light focused on a very small area is applied to the vicinity of the center of the droplet D falling in a form close to a sphere, most of the detection light is transmitted. In some cases, accurate counts were inhibited. In the present flow sensor, by arranging the photodetector 4 at a position illustrated in FIG. 4A, the detection light is irradiated to the droplet D immediately before being separated from the droplet portion 1, and the sphere is irradiated. It is possible to detect a droplet D that does not become a close form. This makes it possible to perform accurate counting even when measuring a colorless solution. Specifically, with respect to the distance L along the falling miracle T from the tip 1a of the droplet unit 1, the central axis of the detection light focused on the micro area s connecting the centers of the light emitting unit 4a and the light receiving unit 4b It is preferable to arrange the photodetector 4 at a position of the measurement unit 2 such that M satisfies 0 <L ≦ s.

  That is, as the solution is supplied, droplets D are gradually formed from the tip 1a, but due to the weight of the droplet D and the surface tension between the tip 1a of the droplet 1 and FIG. As illustrated, in the vicinity of the tip 1a, a shape close to a sphere is never formed, and the shape has non-uniformity in the vertical direction. For this reason, immediately before the droplet D is separated, the light emitted from the light emitting portion 4a is reflected on the boundary surface between the liquid and air on the surface of the droplet D, and increases the refracted light on the boundary surface. Accordingly, the detection light that passes through the droplet D and reaches the light receiving portion 4b is greatly reduced. On the other hand, after the liquid droplets are separated, the detection light reaching the light receiving unit 4b does not decrease in the optical path. Therefore, by detecting such a change in the amount of transmitted light caused by the presence or absence of the droplet D, the droplet D can be accurately counted. Specifically, by setting conditions for capturing the transmitted light signal pattern (pulse signal) at the time of droplet formation at the tip portion 1a of the droplet portion 1 with one droplet to one pulse signal, an accurate droplet per time Allows detection of numbers.

[Second configuration example of the flow sensor]
In the second configuration example of the flow rate sensor, the droplet portion 1 has a nozzle portion 1c made of a water repellent material having an inner diameter d1 / outer diameter d2, and the detection light of the photodetector 4 is transmitted to the tip of the droplet portion 1. It passes through the measurement unit 2 up to a distance L satisfying a distance L ≦ d1 × 1.5 from the unit 1a. That is, for example, the nozzle portion 1c is formed by using a water repellent material such as PTFE (fluorine resin) or a water repellent treatment, thereby forming a relatively small droplet D as shown in FIG. In addition, the separation from the nozzle portion 1c can be achieved smoothly. As a result, it is possible to form a droplet D that is not divided into droplets, and to make the time (falling distance) until the droplet D is in a form close to a sphere substantially constant. Therefore, it is possible to set a region where the transmitted light is reduced due to the passage of the droplet D by removing the region where the accurate counting is inhibited as described above, and the droplet D can be accurately counted. it can.

  On the other hand, the droplet Da immediately after being separated from the tip 1a resembles a bowl shape as illustrated in FIG. 5 due to the weight of the droplet Da and the surface tension between the tip 1a of the droplet 1 and the surface. Reflecting at the liquid-air interface at the droplet surface because it has a shape or an eaves-like shape that is being stretched and has a shape non-uniformity in both the vertical and horizontal directions In addition, the transmitted light that reaches the light-receiving portion 4b is reduced as the refracted light increases. Accordingly, it is possible to set a region from the tip 1a until the droplet Dc is in a state where accurate counting is inhibited as a region in which transmitted light decreases due to the passage of the droplet Da or Db. It became possible to count. As a result of the verification, it has been found that a region corresponding to the distance L satisfying the distance L ≦ d1 × 1.5 from the tip portion 1a of the droplet portion 1 is optimal as a specific setting region of transmitted light. For example, as will be described later in [Example], when a nozzle portion 1c having an inner diameter of 4 mm / an outer diameter of 6 mm is used, L ≦ 4 × 1.5 = 6 mm is preferable. More preferably, the condition is L ≦ 4 mm, which corresponds to the distance L satisfying L ≦ d1 × 1.

  Here, the water repellent material or the water repellent treatment of the nozzle portion 1c means that the nozzle portion 1c is made of various fluororesins such as PTFE, plastics such as polypropylene and polyethylene, or the above resin on the surface of a metal nozzle. This refers to the case where the coating process is applied.

[Third configuration example of the flow sensor]
In the third configuration example of the flow sensor, the droplet unit 1 has a nozzle unit 1c made of a hydrophilic material having an inner diameter d1 / outer diameter d2, and the detection light of the photodetector 4 is transmitted to the tip of the droplet unit 1. It passes through the measuring part up to a distance L satisfying the distance L ≦ d2 × 2.5 from the part 1a. That is, for example, by using a hydrophilic material such as glass or a hydrophilic treatment for the nozzle portion 1c, as shown in FIG. 1B, a larger droplet D is formed and the solution is transferred to the nozzle portion. The surface tension generated upon separation from the solution remaining in the substrate increases. That is, the contact angle θ is reduced. As a result, the time (drop distance) until the droplet becomes a shape close to a sphere becomes longer. Therefore, it is possible to set a wide area in which the transmitted light is reduced due to the passage of the droplets as described above, and the droplets D can be accurately counted.

  On the other hand, the droplet Da immediately after being separated from the tip portion 1a is illustrated in FIG. 5 due to the self-weight of the droplet Da and the surface tension between the tip portion 1a of the droplet portion 1 as in the second configuration example. As described above, a region that has a shape similar to the shape of a cocoon or a shape of a cocoon that is being stretched, and that is a droplet Dc in a state where accurate counting is inhibited from the tip portion 1a is defined as a droplet Da. Alternatively, it can be set as a region in which transmitted light decreases due to the passage of Db. In particular, since the droplet D is large and the deformation of the droplet Da immediately after separation due to strong hydrophilicity with the tip portion 1a is large, it is possible to set a wider area and perform accurate counting. It has become possible. As a result of the verification, it has been found that a region corresponding to the distance L satisfying the distance L ≦ d2 × 2.5 from the front end portion 1a of the droplet portion 1 is optimal as a specific set region of transmitted light. For example, as will be described later in [Example], when the nozzle portion 1c having an inner diameter of 4 mm / an outer diameter of 6 mm is used, L ≦ 6 × 2.5 = 15 mm is preferable. More preferably, the condition is L ≦ 10 mm, which corresponds to the distance L satisfying L ≦ d2 × 1.6.

Here, the hydrophilic material or the hydrophilic treatment of the nozzle portion 1c means that the nozzle portion 1c is made of, for example, a metal such as glass or stainless steel, or ceramics, or the surface of the resin nozzle is made of glass or titanium oxide. This refers to the case where a coating process is applied. Further, as shown in FIG. 1B, the droplet D formed on the nozzle portion 1c shows a state where the gravity (F ↓) and the wet tension (F ↑) due to the dynamic angle θ are balanced. That is, m is the mass of the droplet, g is the acceleration of gravity, P is the circumferential length of the nozzle in contact with the droplet, γ is the specific gravity of the droplet, and θ is the contact angle.
F ↓ (mg) = F ↑ Pγcos θ (2)
When the droplet D is separated, m increases and F ↓> F ↑ is established.

[Fourth configuration example of the flow sensor]
The fourth configuration example of the present flow sensor is characterized in that the central axis M of the detection light of the photodetector 4 has an inclination of 20 to 40 ° with respect to the droplet drop locus T of the measurement unit 2. That is, the falling droplet D has a shape close to an elliptical shape elongated in the direction of gravity and does not become a perfect sphere, as shown in FIG. 1C, except for special conditions such as weightlessness. The center axis M of the detection light has a predetermined inclination angle α with respect to the drop trajectory T of the droplet of the measurement unit 2, thereby reducing the transmitted light passing through the droplet as the refracted light increases. The conditions that occur can be set, and the droplets D can be accurately counted.

  Specifically, as a result of the demonstration, it was found that the accurate count is not inhibited in almost the entire region of the measurement unit 2 by setting the inclination angle α to be 20 to 40 °. Therefore, by disposing the photodetector 4 so that the inclination angle α is 20 to 40 °, it is possible to set a wide region in which transmitted light is reduced due to the passage of the droplet D as described above. , The droplet D can be accurately counted.

[Example 1]
The material of the nozzle part 1c of the liquid droplet part 1 was changed, and the position or the optimum range of the photodetector 4 capable of accurate counting in the measurement part 2 was verified.
(1) Experimental conditions (1-1) As shown in FIG. 6 (A), pure water is supplied from the pipe 10a, and an infrared light emitting diode having a beam diameter of 2.2 mm and having a beam diameter of 940 nm is used as the light source as the light detector 4. The output of the photodetector 4 was monitored by the integrating counter 5 and the oscilloscope 6 when the distance L from the tip 1a was changed using the microphotosensor 4 as follows.
(1-2) A nozzle portion 1c having an inner diameter of 4 mm / an outer diameter of 6 mm was used, and the material was glass and PTFE.

(2) Experimental results (2-1) As shown in FIG. 6 (B), the normal pulse waveform observed by the oscilloscope 6 is L ≦ 15 mm and PTFE when the material of the nozzle portion 1c is glass. Sometimes L ≦ 6 mm. More preferably, L ≦ 10 mm when glass was used, and L ≦ 4 mm when PTFE was used.
(2-2) As shown in FIG. 6C, the abnormal pulse waveform observed by the oscilloscope 6 is L> 15 mm when the nozzle portion 1c is made of glass, and L> 6 mm when PTFE is used. It was the condition of.
(2-3) Summary When a glass nozzle is used, a normal pulse signal can be obtained by setting the distance between the tip of the lower nozzle of the droplet and the optical axis of the sensor to 4 to 10 mm. The relationship between the flow rate and the number of pulses at this time was a good linear relationship as shown in FIG. Linearity was obtained in the range of 0-1.5 ml / min and 0-10 ml / min with a glass nozzle having a wide measurement flow rate range.
As for the difference in nozzle material, as described above, in PTFE, there is almost no contact between the tip 1a and the droplet D, and when the transmitted light is measured when the droplet D grows rapidly on the sphere, an abnormal pulse waveform is formed. However, it can be estimated that in glass, the contact angle is large and the size of the droplet D is large and the gravity is superior and the pulse light is not disturbed immediately after falling off the nozzle and dropping.

[Example 2]
When the central axis M of the detection light is provided with an inclination of the angle α with respect to the drop trajectory T of the droplet of the measuring unit 2, the inclination angle of the photodetector 4 capable of accurate counting or the optimum range has been demonstrated.
(1) Experimental condition (1-1) As in [Example 1], pure water is supplied from the pipe 10a, and a 940 nm infrared light emitting diode having a beam diameter of 2.2 mm is used as the light source as the light detector 4. The output of the photodetector 4 when the inclination angle α as shown in FIG. 7A is changed is set at a position of a distance of about 15 mm from the tip end portion 1a using the micro photo sensor to be integrated counter 5 and oscilloscope 6.
(1-2) A nozzle portion 1c having an inner diameter of 4 mm / an outer diameter of 6 mm was used, and the material was glass.

(2) Experimental results (2-1) As shown in FIG. 7B, the normal pulse waveform observed by the oscilloscope 6 was in a condition where the inclination angle α was 20 to 40 °.
(2-2) As shown in FIG. 7C, the abnormal pulse waveform observed by the oscilloscope 6 was in a condition where the inclination angle α was α <20 or α> 40 °.
(2-3) Summary As described above, in [Example 1], even at the position of the photodetector 4 where an abnormal pulse has occurred, it can be detected as a normal pulse at an inclination angle α of 20 to 40 °. did it.

<Clean liquid supply system using this flow sensor>
A cleaning liquid supply system according to the present invention (hereinafter referred to as “main supply system”) uses any of the liquid flow rate sensors described above, and supplies a cleaning liquid or a used cleaning liquid after regeneration processing. Further, the feeding means, the flow rate control means and the liquid flow rate sensor are arranged in series or in parallel.

  That is, as illustrated in FIG. 8A, the cleaning liquid in the cleaning liquid storage tank 11 is pumped by the feed pump 12 (corresponding to the feeding means), and the valve 13 (corresponding to the flow control means) The flow rate is adjusted, confirmed by one of the liquid flow rate sensors 10 described above, and supplied to the processing unit 14. An accurate flow rate can be monitored even in a cleaning liquid containing pure water or dilute salts. Accordingly, the use of the liquid flow sensor 10 dedicated to the cleaning liquid enables a stable cleaning liquid supply system. Here, the cleaning liquid is not only a clean stock solution containing pure water and dilute salts, but also a used solution as shown in FIG. 8B is regenerated and purified via the regenerator 15 and the suction pump 16. The prepared solution is also included. Such a clean water supply system performs continuous flow monitoring and flow control, such as the addition of pure water or chemicals in semiconductor processes, or the clean water supply system in a sample gas processing system in a mercury measuring apparatus described later. Useful when needed. Moreover, the excellent quantitative property can be effectively utilized also for the humidification treatment of the dry gas.

<Selenium oxide removal device in sample using this flow sensor>
The selenium oxide removing apparatus according to the present invention (hereinafter referred to as “the present removing apparatus”)
(1) a heating introduction path for heating the sample;
(2) a primary cooling section having a flow path in which the flow of the heated sample and the flow of cooling water face each other and mixing the sample and the cooling water to rapidly cool the flow;
(3) a secondary cooling unit having a spiral flow path for cooling the mixed gas and having a space for gas-liquid separation at the end of the spiral flow path;
(4) a regenerator for introducing condensed water from the secondary cooling section;
(5) a cooling water supply path connecting the regenerator and the primary cooling unit;
And any one of the liquid flow rate sensors is provided in a cooling water supply channel to the primary cooling unit.

  A specific configuration of the present removal apparatus is illustrated in FIG. Heating conduit 21 (corresponding to a heating introduction path), primary cooling pipe 22 (corresponding to a primary cooling part), secondary cooling pipe 23, an electronic cooler 23a (corresponding to a secondary cooling part) for cooling the same, anion exchange resin , A drain recovery pump 25a, a cooling water tank 25b, a cooling water supply pump 25c, and a flow meter 25d (forming a cooling water supply path). Any of the liquid flow rate sensors 10 is used as the flow meter 25d.

A sample containing moisture, SeO ₂ or the like is transferred while being heated by the heating conduit 1 so as not to condense, and is introduced into the primary cooling pipe 22 and mixed with the cooling water. Here, while being rapidly cooled, the SeO ₂ in the sample is dissolved and then introduced into the secondary cooling pipe 23. Here, the sample is further cooled, separated into gas and liquid, and supplied from the upper part of the secondary cooling pipe 23 as a processed dry sample through the sample supply path 21a.

On the other hand, the cooling water stored in the cooling water tank 25b is supplied to the primary cooling pipe 22 via the flowmeter 25d by the cooling water supply pump 25c. Here, the sample is cooled (cooling water is heated), and SeO ₂ in the sample is dissolved and removed, and then introduced into the secondary cooling pipe 23 together with the sample. Here, it is cooled by the electronic cooler 23a, gas-liquid separated, sucked by the drain recovery pump 25a, and recovered in the cooling water tank 25b through the regenerator 24 filled with anion exchange resin. In the regenerator 24, SeO ₂ and other water-soluble substances dissolved in the cooling water are removed and regenerated as clean cooling water.

[Mechanism of dissolution of SeO ₂ in condensed water and formation of amalgam with mercury]
Here, the mechanism of dissolution of SeO ₂ in condensed water and generation of amalgam with mercury will be described.
(A) SeO ₂ is water-soluble and becomes H ₂ SeO ₃ as shown in the following formula 1. As a result of verification, it was found that this reaction proceeds very rapidly.
SeO ₂ + H ₂ O → H ₂ SeO ₃ .. (Formula 1)
(B) The generated H ₂ SeO ₃ is reduced by SO ₂ coexisting in a large amount in the exhaust gas as shown by the following formula 3 or 3 ′, and becomes metal Se. As a result of the verification, it was found that this reaction proceeds relatively slowly and does not form immediately after SeO ₂ is dissolved in water. In the experiment, when a predetermined concentration of SO ₂ gas was introduced into the H ₂ SeO ₃ aqueous solution, it was verified that yellow to orange color was formed and a deep orange precipitate (elemental selenium Se) was gradually formed. Se is generated quickly in a high temperature dew point atmosphere, and once it is deposited on the tube wall or the like, the cleaning effect by water injection cannot be expected.
H ₂ SeO ₃ + SO ₂ → Se + H ₂ SO ₄ .. (Formula 3)
H ₂ SeO ₃ + 2SO ₂ + H ₂ O → Se + 2H ₂ SO ₄ (Formula 3 ′).
(C) The generated metal Se is insoluble in water, and precipitates as red powder on the inner wall of the pipe and the like, as shown in the following formula 4, and easily forms amalgam with mercury.
Hg + Se → HgSe (Equation 4)

[Configuration of the removal device]
(1) Heating introduction path (heating conduit 21)
Heat the sample to 100-200 ° C. Condensation of moisture in the sample can be prevented, and generation of selenious acid (H ₂ SeO ₃ ) due to the reaction of the above formula 1 can be suppressed. Further, in the presence of solution-like water (including water droplets and droplets), the generation of elemental selenium due to the reaction of SO ₂ in the sample and the above formula 3 is suppressed, and the reaction of the above formula 4 is prevented, thereby The reaction between mercury and Se can be suppressed.

(2) Primary cooling part (primary cooling pipe 22)
The sample heated to 100 to 200 ° C. is rapidly cooled to the temperature of the environmental atmosphere by the primary cooling pipe 22 and simultaneously mixed with the cooling water. According to the above formula 1, SeO ₂ in the sample is dissolved in the cooling water, and washed with the cooling water so that the selenite generated by the above formula 1 does not remain in the flow path such as the cooling pipe. The mixed gas of the cooling water containing the selenious acid generated by dissolution and the sample is supplied to the secondary cooling pipe 23.

(3) Secondary cooling section (secondary cooling pipe 23 and electronic cooler 23a for cooling the secondary cooling pipe 23)
The secondary cooling pipe 23 efficiently cools the cooling water and condensed water (hereinafter referred to as “cooling water”) and the gas-liquid mixed fluid of the sample, and at the same time, increases the outflow speed and contributes to the cleaning effect in the cooling pipe. The structure and material are not limited as long as they can be corrosion-resistant, but the structure shown in FIG. 10 is preferable, for example. The secondary cooling pipe 23 provided in the electronic cooler 23a or the water cooling type cooling device has a double pipe structure using a glass tube, and an outer pipe 23b and an inner pipe 23c that are in contact with the heat exchange part of the electronic cooler 23a. And a space 23f provided at a terminal end 23e thereof, cooling of the sample and outflow of cooling water or the like are accelerated. The sample that has passed through the flow path 23d is separated from the cooling water or the like in the lower space 23f, and then delivered through the internal flow path 23g of the inner tube 23c. During this time, the cooled sample exchanges heat with the sample passing through the flow path 23d. Although a large amount of heat is not expected, the delivered low temperature sample is reheated by exchanging heat with the introduced high temperature sample to prevent condensation. By processing the sample using the secondary cooling pipe 23, it is possible to prevent generation of the element Se that becomes an obstacle. On the other hand, the cooling water or the like is circulated and reused from the space 23f through the condensed water discharge passage 23h, and the rapid cooling of the sample by the primary cooling pipe 2 and the addition of the cooling water to the sample can reduce the drain flow rate. The generated drain flow rate is discharged out of the system while increasing and constantly flowing in the sample processing system. If the drain that has fallen naturally is retained in the pot without being recycled, the element Se may be generated not only in the drain channel but also in the sample channel connected to the drain channel.

(4) Regenerator 24
The cooling water or the like flowing down from the condensed water discharge flow path 26h of the secondary cooling pipe 23 is regenerated by the regenerator 24 and circulated and reused as cooling water. The regenerator 4 is filled with a reagent that removes selenious acid that becomes an obstacle in cooling water or the like. Specifically, an anion exchange resin or an adsorbent of selenious acid such as iron oxide (eg, ferrous oxide (FeO), iron oxyhydroxide (FeO.OH), etc.) can be used. An anion exchange resin that can regenerate itself is preferred. In this apparatus, about 250 g of anion exchange resin is filled, and 1 to 10 ml / min of cooling water or the like always passes. As a result of verifying the maintenance frequency such as replacement and replenishment of cooling water, it was conventionally necessary to replenish every 1 month, but it was found that it was extended to 3 to 6 months by using an anion exchange resin. Further, the regenerator 24 may be installed before or after the cooling water supply pump 25c instead of downstream of the secondary cooling unit 23 as shown in FIG.

(5) Cooling water supply path (drain recovery pump 25a, cooling water tank 25b, cooling water supply pump 25c and flow meter 25d)
The cooling water or the like flowing down from the condensed water discharge flow path 26h of the secondary cooling pipe 23 is supplied to the cooling water via the regenerator 24, the drain recovery pump 25a, the cooling water tank 25b, the cooling water supply pump 25c, and the flow meter 25d. As a result, it is always introduced into the primary cooling pipe 22 at a rate of about 1 to 10 ml / min and recycled. Since the drain recovery pump 25a and the cooling water supply pump 25c recover and supply a substantially constant amount, a tubing pump is generally used. However, since the flow rate decreases due to the elasticity of the tube, as shown in FIG. In addition, it is preferable to install a flow meter 25d at the outlet of the cooling water supply pump 25c to monitor the flow rate and periodically correct the flow rate.

(6) Flow meter 25d
At this time, the flow meter 25d plays an important role not only in normal flow rate monitoring but also in the present removal apparatus. In other words, if water droplets are generated due to a decrease or stoppage in the flow rate of cooling water that is recycled and reused, amalgam is generated, or the selenium oxide in the coexisting gas is reduced by precipitation of the selenium oxide by coexisting gas temperature rise and water content decrease Therefore, in order to continuously add the cooling water stably, it is necessary to continuously monitor the flow rate of the cooling water, and the flow meter 25d for circulating cooling water is preferably installed. Furthermore, as a method for monitoring the flow rate of the cooling water or the like that is circulated and reused, it is possible to detect an increase in the amount of water in the cooling water tank 25b over a certain period of time using a liquid level detector (not shown) such as a float switch. Yes, it is possible to correct the cooling water supply flow rate from the detected flow rate. Further, since the flow rate of the cooling water is monitored in real time, for example, the suction of the sample gas can be stopped at the same time by a flow rate lowering signal, thereby preventing the removal apparatus from deteriorating. Here, the flow meter 25d initially measures pure water or purified water, and measures water regenerated and purified with continuous use. Accordingly, any of the liquid flow rate sensors 10 described above is used as the flow meter 25d, and the flow rate of the clean water supplied to the primary cooling pipe 22 is accurately monitored by accurately counting droplets, so that high-precision control is performed. Can be used.

[Example of the present removal apparatus]
(1) Experimental conditions Air containing 18 ppm of SeO ₂ was introduced at a flow rate of 1.1 L / min from the upstream side of the heating conduit 1 of the removal apparatus illustrated in FIG.
(2) Experimental results The cooling water collected in the cooling water tank 5b was measured by an inductively coupled high-frequency plasma method (ICP, manufactured by HORIBA, Ltd., model: ULTIMA2) to obtain a dissolved Se concentration of 5 ppb. When the total amount of dissolved SeO ₂ was calculated from the amount of 300 g of cooling water in the circulation system and the removal efficiency was calculated, a result of 95% was obtained.

<Configuration example of mercury measuring device in coal combustion exhaust gas using this removal device>
An apparatus for measuring mercury in coal combustion exhaust gas using this removal device (hereinafter referred to as “the present measurement device”) uses a sample of coal combustion exhaust gas as a measurement target sample, and collects the sample, and the sample collection unit A sample introduction path for heating and introducing the sample, the removing device, and a mercury analyzer. For SeO ₂ present in coal combustion exhaust gas, mercury and amalgam can be easily produced under the coexistence conditions such as moisture, SO ₂ and NO ₂ contained in the exhaust gas. This is one of the causes, and this measuring apparatus uses the present removing apparatus and eliminates this influence, thereby making it possible to ensure measurement accuracy that was not possible with the conventional method.

FIG. 11 illustrates one configuration of the measurement apparatus. In this arrangement, the divalent mercury ^{(Hg 2+)} and elemental mercury (Hg ⁰⁾ measured for all mercury plurality of components that can be converted to each other include the same elements ^(Hg 2+ + ^{Hg 0),} such as Suitable for cases. In other words, after the Hg ²⁺ in the sample gas is first converted to the total amount of Hg ⁰ to be measured, the gas treated using the above removal device is analyzed to eliminate the influence of other coexisting components such as SeO _2. It becomes possible to do. Hereinafter, as a specific embodiment, when the present invention is applied to a total mercury measuring device in coal combustion exhaust gas using wet treatment as the removal device and using an ultraviolet absorption analyzer 30 as a measuring means, This will be described as an example.

The sample is sucked and collected from a sample inlet 31 (corresponding to a sample collecting unit) by a suction pump 35 provided on the downstream side of the ultraviolet absorption analyzer 30. After the collected sample is cleaned by the dust filter 32, the total mercury in the sample is converted to Hg ⁰ by the reduction catalyst unit 33, and the heating conduit 21, the primary cooling unit 22, the secondary cooling unit 23, and the filter 34 are changed. And introduced into the ultraviolet absorption analyzer 30. At this time, as the gas contact material, Ti, oxidation treatment SUS can be used as a metal in addition to inexpensive glass, quartz, ceramics and the like.

The reduction catalyst unit 33 is a unit filled with a reduction catalyst, and the reduction catalyst is preferably maintained at an intermediate temperature range of 250 to 500 ° C. by heating means (not shown). That is, normally, mercury in coal combustion exhaust gas exists in the state of HgO, HgCl _2, or Hg ⁰ , but in order to reduce Hg ²⁺ to Hg ⁰ , a thermal decomposition reaction is indispensable, and the reduction temperature is set to 250 By setting the temperature to higher than or equal to ° C., generation of amalgam with mercury caused by reaction of metal oxide such as SeO ₂ contained in the exhaust gas can be prevented. On the other hand, by setting the reduction temperature to 500 ° C. or less, troubles such as corrosion in the sample channel or blockage by the reactants can be prevented.

The reduction catalyst filled in the reduction catalyst part 33 is preferably an inorganic material catalyst having a reducing power and low reactivity with an acidic substance. In the present invention, the reduction catalyst is required to have a function of reducing a divalent mercury (Hg ²⁺ ) compound such as mercury chloride to a metal (Hg ⁰ ), and has an influence on other coexisting components. It is required that it is difficult to be affected and that it does not affect other coexisting components, that is, it has selectivity for divalent mercury. Specific examples of the reduction catalyst include inorganic compounds such as zeolite-based catalysts and alkali metal sulfites. For the reduction action, carbonates and hydrates can also be applied, but functionally limited to such catalysts due to the coexistence of acidic substances such as SO ₂ and NO ₂ contained in large amounts in coal combustion exhaust gas. Will be. The shape of the reduction catalyst is not particularly limited, but a granular material or a honeycomb shape that is easy to fill and replace the reduction catalyst portion 33 and has little pressure loss is preferable. At this time, not only the catalyst itself formed into such a shape but also a catalyst supported on the surface using such a shape as a carrier is applicable.

Although not shown, the ultraviolet absorption analyzer 30 forms an optical system including an ultraviolet light source unit, a sample cell unit, an ultraviolet detector, and an optical filter, and has an ultraviolet region due to Hg ^{0 in} the sample introduced into the sample cell unit. By detecting the amount of absorbed light with an ultraviolet detector, the concentration of Hg ^{0 in} the sample can be measured.

In the above, the application of this flow sensor has been described mainly in the case of applying to a method and apparatus for measuring mercury in coal combustion exhaust gas. The mercury measuring method and measuring apparatus can be applied. Furthermore, it is particularly useful when measuring a sample in which SO ₂ or a metal oxide coexists. Further, the present flow sensor can be widely applied also when supplying a cleaning liquid in various processes including a semiconductor manufacturing process.

Some specific examples are given below.
(1) As a pretreatment of the gas analyzer, it can be applied to a water addition mechanism for humidification.
For example, in a NDIR (non-dispersive infrared analysis) type nitrogen oxide gas analyzer, since there is an interference effect due to moisture, the moisture concentration in the sample gas is kept constant by using a drain separator or an electronic cooler. In some cases, the moisture interference value of the analyzer may be compensated. At this time, in cold regions and in winter, when the environmental temperature decreases and the air is dehumidified to the outside temperature, a sufficient water concentration cannot be obtained. In this case, the required amount of water is dropped into the sample gas while dropping the drainage from the drain separator or electronic cooler while monitoring the flow rate, so that the necessary amount is supplied and stabilized and the humidified state is maintained. Can do.

Such a method is particularly effective in an analyzer that measures a highly water-soluble component such as SO ₂ (sulfur dioxide). That is, these gases, humidification method by water washing apparatus may not be SO ₂ itself measure leads to dissolution loss greater during the measurement. In this water addition mechanism, for example, by injecting condensed water before the drain pot using a tubing pump or into the inlet of the electronic cooler, the saturation solubility and the condensed water addition flow rate of the condensed water can be controlled. Can be minimized. As a result, the influence of moisture interference can be reduced and the dissolution loss of the measurement components such as SO ₂ can be reduced, so that a highly accurate analyzer can be provided.

(2) An example of a measurement flow using a droplet sensor of a UV-TOC analyzer (ultraviolet absorption total organic carbon analyzer) can be given.
This flow sensor is installed in the pressurization line of the TOC analyzer that is easily influenced by the flow rate, and the flow rate measurement data is fed back in real time, and the flow rate control of the pressurization pump is performed to stabilize the flow rate. Realize TOC meter measurement. Even in the measurement of clean water, the characteristics of the present flow sensor with less pressure influence can be used effectively.

Explanatory drawing which shows schematically the formation state of the droplet of the liquid flow sensor which concerns on this invention. Explanatory drawing shown in the basic composition of the liquid flow sensor concerning the present invention. Explanatory drawing which shows schematically the pulse signal generation process in the liquid flow sensor which concerns on this invention. Explanatory drawing which shows roughly the detection state of the droplet in the 1st structural example of the liquid flow sensor which concerns on this invention. Explanatory drawing which shows schematically the formation state of the droplet in the 2nd structural example of the liquid flow sensor which concerns on this invention. Explanatory drawing which shows the experimental condition and experimental result in Example 1. FIG. Explanatory drawing which shows the experimental condition and experimental result in Example 2. FIG. Explanatory drawing which illustrates the structure of the cleaning liquid supply system which concerns on this invention. Explanatory drawing which illustrates the structure of the selenium oxide removal apparatus which concerns on this invention. Explanatory drawing which illustrates the structure of the secondary cooling pipe used for the selenium oxide removal apparatus which concerns on this invention. Explanatory drawing which shows the structural example of the mercury measuring apparatus in the coal combustion exhaust gas which concerns on this invention. Explanatory drawing which shows schematically the structure of the droplet detection system flowmeter concerning a prior art

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Droplet part 1a Tip part 1b Flow path 1c Nozzle part 2 Measuring part 3 Liquid receiving part 4 Photodetector 4a Light emitting part 4b Light receiving part 5 Accumulation counter 10 Liquid flow sensor D Droplet L Distance M Center axis s of detection light Minute Area T Droplet drop locus θ Contact angle α Inclination angle

Claims (7)

  A liquid flow sensor having a droplet part at the upper part and a measuring part at the middle part, and having a transmission type light detector comprising a light emitting part and a light receiving part at the measuring part, the detection light of the light detector A liquid flow rate sensor capable of detecting a droplet that has passed through the tip of the droplet portion and has just been separated from the droplet portion.   A liquid flow sensor having a droplet part at the upper part and a measuring part at the intermediate part, and having a transmission type photodetector comprising a light emitting part and a light receiving part at the measuring part, wherein the droplet part has an inner diameter d1 / A nozzle having an outer diameter d2 made of a water repellent material, and a measuring portion for detecting light from the photodetector up to a distance L where a distance L ≦ d1 × 1.5 from the tip of the liquid droplet portion. A liquid flow rate sensor characterized by passing.   A liquid flow sensor having a droplet part at the upper part and a measuring part at the intermediate part, and having a transmission type photodetector comprising a light emitting part and a light receiving part at the measuring part, wherein the droplet part has an inner diameter d1 / A measuring portion having a nozzle portion made of a hydrophilic material having an outer diameter d2 and having a detection light of the photodetector up to a distance L where a distance L ≦ d2 × 2.5 from a tip portion of the droplet portion; A liquid flow rate sensor characterized by passing.   A liquid flow sensor having a droplet part at the upper part and a measuring part at the middle part, and having a transmission type light detector comprising a light emitting part and a light receiving part at the measuring part, the center of the detection light of the light detector The liquid flow rate sensor, wherein the axis has an inclination of 20 to 40 degrees with respect to a drop trajectory of the droplet of the measurement unit.   A cleaning liquid supply system using the liquid flow rate sensor according to any one of claims 1 to 4, wherein a supply means, a flow control means, and a flow path for supplying the cleaning liquid or the used cleaning liquid after the regeneration treatment, A cleaning liquid supply system, wherein the liquid flow rate sensors are arranged in series or in parallel. (1) a heating introduction path for heating the sample;
(2) a primary cooling unit that has a flow path in which the flow of the heated sample and the flow of cooling water face each other, and mixes and cools the heated sample and cooling water;
(3) a secondary cooling unit having a spiral flow path for cooling the mixed gas and having a space for gas-liquid separation at the end of the spiral flow path;
(4) a regenerator for introducing condensed water from the secondary cooling section;
(5) a cooling water supply path connecting the regenerator and the primary cooling unit;
An apparatus for removing selenium oxide in a sample having
An apparatus for removing selenium oxide in a sample, wherein the liquid flow rate sensor according to any one of claims 1 to 4 is provided in a cooling water supply channel to the primary cooling unit. A mercury measuring device using the cleaning liquid supply system according to claim 5 or the selenium oxide removing device in the sample according to claim 6,
Using a coal combustion exhaust gas as a measurement target sample, a sample collection unit for collecting the sample, a sample introduction path for heating and introducing the sample from the sample collection unit, the removal device, and a mercury analyzer An apparatus for measuring mercury in coal combustion exhaust gas.

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