JP5453607B2 - Light scattering dust concentration meter - Google Patents

Description

The present invention relates to a dust concentration meter. More specifically, the dust concentration in the cloudy exhaust gas in which the inside of the flue is below the dew point and the mist (droplet particles) and dust (solid particles) are adsorbed and coexist and clouded. The present invention relates to a light scattering dust densitometer capable of continuous, accurate, and long-term measurement in a flue.

Exhaust gas discharged from various factory flues contains a large amount of harmful substances such as sulfur oxides and nitrogen oxides. Therefore, it is obliged to install an exhaust gas treatment device such as a desulfurization device or a denitration device in the exhaust gas path.

On the other hand, predetermined emission concentration regulations are also provided for dust. For example, in a paper mill or the like, mist used in the above-described exhaust gas processing apparatus is turned into white smoke and discharged from a chimney. Complaints and anxieties are often sent to factories that the surrounding residents who have seen the white smoke are discharging more dust than the regulation value.

Therefore, it is necessary for various factories to accurately grasp whether white smoke is caused by dust emission exceeding the regulatory standard or by mist, and always confirm that the regulations regarding dust emission are observed.

Conventionally, a light scattering dust concentration meter is known as a dust concentration meter. Conventional light scattering dust concentration meters can continuously measure the dust concentration in exhaust gas in real time, but the exhaust gas becomes cloudy exhaust gas below the dew point downstream of the exhaust gas desulfurization device using mist. Since a large amount of mist is contained together with dust, it is theoretically difficult to accurately measure the dust concentration due to the influence of mist.

On the other hand, a sampling tube (suction passage) that collects part of the cloudy exhaust gas in the flue is provided, and a mist particle size measurement device that introduces exhaust gas into the detection chamber outside the flue and measures the particle size distribution of the mist has been released. (Patent Document 1).

  The mist particle size distribution measuring device described in Patent Document 1 continuously measures the particle size distribution of dust and mist at the upstream end of the detection chamber 4 with an optical sensor (light source 6, condensing lens 7 and light receiver 10). Further, downstream of the optical sensor, the cloudy exhaust gas passing through the detection chamber 4 is irradiated with heating light (heating device 15 and condensing lens 16) to vaporize the mist, and further, the dust after the mist vaporization is downstream of the irradiation unit. The particle size distribution is measured with an optical sensor (light source 8, condensing lens 9, light receiver 11). Then, the particle size distributions before and after the vaporization of the measured mist are compared by the computing units 12 and 13 and the comparison analyzer 14, and the particle size distribution of the mist is continuously measured.

JP-A 64-15634

However, according to the mist particle size distribution measuring device of Patent Document 1, the particle size distribution of mist can be measured, but the dust concentration cannot be measured. In addition, since the device uses a sampling tube with a fixed length and a small diameter, dust and mist are deposited and adhered to the sampling tube, which causes clogging of the sampling tube, and cloudy exhaust exhausted from the flue It was difficult to collect the gas continuously and accurately into the examination room 4 through the sampling tube.

Therefore, the dust concentration in the cloudy exhaust gas discharged from the flue cannot be accurately measured, and measurement over a long period of time is impossible.

  Accordingly, the present invention provides a continuous, accurate, and long-term cloudy exhaust gas directly in the flue without using a sampling tube for collecting a part of the cloudy exhaust gas in the flue in a laboratory outside the flue. A light scattering dust concentration meter capable of measuring a duct concentration in a gas is provided.

  In order to solve the above problems, the present invention is a dust concentration meter for measuring the dust concentration in cloudy exhaust gas in which mist and dust are adsorbed and coexisted in the flue, and the mist in the cloudy exhaust gas in the flue is measured. A vaporization device for vaporization, a light irradiator that irradiates light to an area where mist is vaporized in the flue, and a scattered light detector that detects scattered light reflected from dust from which the mist has been removed. The light scattering dust concentration meter is characterized in that the dust concentration in the cloudy exhaust gas is obtained based on the scattered light intensity detected by the scattered light detector.

  The dust concentration meter measures the dust concentration in the cloudy exhaust gas where mist and dust are adsorbed and coexisted in the flue, and the moment when the mist in the cloudy exhaust gas is evaporated by converging the heating light in the flue An instantaneous heater that forms a heating region; a light irradiator that irradiates measurement light having a wavelength different from that of the heating light immediately downstream in the flow direction of the cloudy exhaust gas in the instantaneous heating region; and the measurement light is the instantaneous heating region A scattered light detector that detects scattered light scattered by being reflected by the dust that has passed through, and an arithmetic device that determines the dust concentration in the cloudy exhaust gas based on the scattered light intensity detected by the scattered light detector It was set as the structure of the light-scattering type dust concentration meter characterized by becoming.

  Also, a dust densitometer that measures the dust concentration in the cloudy exhaust gas where mist and dust are adsorbed and coexisted in the flue, and the instantaneous heating that causes the heating light to converge in the flue and vaporize the mist in the exhaust gas An instantaneous heater that forms a region, a light irradiator that irradiates the instantaneous heating region with measurement light having a wavelength different from that of the heating light, and scattered light that is scattered when the measurement light is reflected by dust in the instantaneous heating region A light scattering type dust concentration meter, comprising: a scattered light detector that detects a dust concentration; and an arithmetic unit that obtains a dust concentration in the cloudy exhaust gas based on a scattered light intensity detected by the scattered light detector. The configuration was as follows. Then, the instantaneous heater is disposed between the light irradiator and the scattered light detector, and then stored in the box, and the box is connected to a flange of a connection pipe connected to the flue. It was set as the structure of the said light-scattering type dust densitometer characterized by the above-mentioned.

  Further, it is a method for measuring the dust concentration in the cloudy exhaust gas in which mist and dust are adsorbed and coexisted in the flue, and heating a part of the cloudy exhaust gas in the flue above the dew point to vaporize the mist. A region is formed, light is irradiated to the heating region or a region where the mist is vaporized through the heating region, the scattered light is detected by scattered light scattered in the dust from which the mist has been removed, and the detected scattered light intensity Thus, the dust concentration measurement method is characterized in that the dust concentration in the cloudy exhaust gas is obtained.

  Further, it is a method for measuring the dust concentration in the cloudy exhaust gas in which mist and dust are adsorbed and coexisted in the flue, and the heating light is focused in the flue to instantaneously vaporize the mist in the cloudy exhaust gas. A heating step for forming the instantaneous heating region, an irradiation step for irradiating the measurement light having a wavelength different from that of the heating light to the instantaneous heating region or a region where the mist is vaporized through the instantaneous heating region, and the measurement light. The method comprises: a detection step for detecting scattered light scattered in the dust from which mist has been removed; and a calculation step for calculating the dust concentration in the cloudy exhaust gas based on the detected scattered light intensity. The measurement method was configured.

  Here, the flue is a passage for exhausting the exhaust gas, and the cloudy exhaust gas is a cloudy exhaust gas in which the inside of the flue is below the dew point as at the outlet of the wet scrubber and dust and mist coexist and adsorb. It is the exhaust gas that is used.

  The vaporization device is a device that evaporates mist by irradiating heating light such as a heater or light, or vaporizes mist in the flue by excitation, decompression or other methods, and examples thereof include a heating device. A region where mist is vaporized is called a heating region.

  The heating light is a heating source such as radiant heat of an infrared heater or a laser generated by a laser generator, and directly converges on a partial area in the flue to form an instantaneous heating area in the flue. In the instantaneous heating zone, the mist in the cloudy exhaust gas is instantly vaporized, separated from the dust, diffused, and removed from the instantaneous heating zone. In addition, a microwave etc. can be illustrated as a heating source.

  As a means for converging the heating light, for example, by using a lens or a concave mirror for the radiant heat of the infrared heater, and using a plurality of small outputs of the laser heating light to collect at the focal point, it is directly focused on a partial area in the flue. A method can be exemplified.

  As a heater which is an example of a heat source generating device, for example, a spot heater HSH made by FinTech, which can be heated up to 1400 ° C., can be exemplified. With such an apparatus, the convergence position of the heating light, the volume of the heating area, and the heating temperature can also be controlled. The heating temperature is desirably a temperature range in which mist is surely vaporized and dust does not burn, for example, about 100 ° C. to 500 ° C. Within this range, it is possible to measure the dust concentration more accurately. As a result, an instantaneous heating zone having a very small volume can be formed in the flue.

  The measurement light is irradiated from the light irradiator in the (instant) heating zone or immediately after passing through the (instant) heating zone (a region where the mist vaporization state is maintained immediately downstream of the cloudy exhaust gas flow direction). Light. As the measurement light, the detection accuracy of the scattered light is increased by setting the wavelength different from that of the heating light. Furthermore, it is preferable to use only light in a predetermined wavelength range as scattered light, since scattered light can also be detected as light of a specific wavelength, and scattered light can be detected with high accuracy. For example, it can be obtained by using light that has been synchronously detected at a constant wavelength, and more specifically by irradiating it through an optical filter that passes only light of a specific wavelength.

  The scattered light is light that is scattered by the dust from which mist is removed from the measurement light emitted from the light irradiator to the (instant) heating region. In the area immediately after the (instantaneous) heating area or the (instantaneous) heating area, the mist contained in the cloudy exhaust gas in the non-instantaneous heating area is not mixed, and the (instant) heating area is maintained, so the scattered light. The amount of light (light intensity) is proportional to the dust concentration.

  The scattered light detector is a device that detects the amount of scattered light scattered by dust from which mist has been removed. For example, if a calibration curve having a proportional relationship between the dust concentration and the light intensity of the scattered light is prepared in advance, the dust concentration with respect to the detected scattered light intensity can be obtained from the calibration curve. When the measurement light is not synchronously detected by the optical filter, the scattered light intensity may be detected by receiving only the light having the wavelength of the scattered light through the optical filter by the scattered light detector.

  For example, as a light irradiator and scattered light detector, DDM-HAL 2 infrared LED (light emitting diode) and photodetector (photodiode) manufactured by Tanaka Electric Laboratory Co., Ltd., described in JP-A No. 09-236545 Or a photoelectric particle concentration measuring device can be used.

The computing device is a device that computes the dust concentration in the cloudy exhaust gas based on the light intensity detected by the scattered light detector, and is a computer or the like. As a calculation method, for example, a proportional expression (primary expression or the like) between the dust concentration and the light intensity of scattered light is created in advance and stored in the storage unit of the calculation device, and the detected scattered light is substituted into the proportional expression. Thus, the dust concentration can be obtained and directly displayed on the monitor in units of mg / m ³ _N.

  Since this invention is the said structure, the mist in cloudy exhaust gas can be vaporized in a flue, and a dust density | concentration can be measured with a light-scattering type dust densitometer without the influence of mist.

In addition, an instantaneous heater that forms an instantaneous heating area with a small volume in the flue, a light irradiator and a scattered light detector for measuring the dust concentration in the instantaneous heating area, and a part of the cloudy exhaust gas are provided. The dust concentration can be continuously and accurately measured based on the amount of scattered light without installing a sampling tube for sampling. In addition, since the light scattering type duct densitometer according to the present invention only includes an instantaneous heater, a light irradiator, and a scattered light detector, the cost of the dust densitometer can be reduced.

Furthermore, since the sampling pipe with a small inner diameter is not used, there is no problem such as clogging of the sampling pipe, and it is possible to measure the dust concentration in the cloudy exhaust gas flowing in the flue accurately for an extremely long time compared to the past. is there.

FIG. 1 is a schematic cross-sectional view of an embodiment of a light scattering dust densitometer according to the present invention. FIG. 2 is a schematic cross-sectional view of another embodiment of the light scattering dust densitometer according to the present invention.

  Hereinafter, the light scattering dust concentration meter according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic cross-sectional view of an embodiment of a light scattering dust densitometer according to the present invention. The measurement principle is that the heating light 3a is converged on a part of the flue 6 (focal point 3b), and the mist 10 around the focal point 3b (instantaneous heating region 7) is vaporized by instantaneous heating to the measurement light 4a. This is a method of irradiating. Note that the right arrow in FIG. 1 is the direction of the cloudy exhaust gas flow, the left in FIG. 1 is the upstream of the cloudy exhaust gas, and the right is the downstream.

The light scattering dust concentration meter 1 includes an instantaneous heater 3, a light irradiator 4, a scattered light detector 5, and an arithmetic device 12. Then, the instantaneous heater 3, the light irradiator 4, and the scattered light detector 5 are arranged in this order with respect to the flow from the upstream to the downstream of the cloudy exhaust gas, and stored in the box 1a.

  And the flange 1b of the box 1a is connected to the flange 6b of the connecting pipe 6c connected to the flue 6. In the figure, the double-headed arrow L1 is the opening diameter (inner diameter) of the opening 6a of the connecting pipe 6c.

  Thereby, without providing a sampling pipe in the flue 6, the inside of the flue 6 becomes the dew point or less, and the dust 11 (●), the mist 10 (◯), and the mist adsorbing dust 10a (● in ●) coexist. The concentration of the dust 11 in the exhaust gas can be measured.

  The instantaneous heater 3 converges the heating light 3a in the flue 6 to form an instantaneous heating region 7 (circle in the figure). In the instantaneous heating zone 7, the mist 10 in the cloudy exhaust gas is instantly vaporized and separated from the dust 11. And the re-adsorption of the mist 10 to the dust 11 does not occur for a while.

  Immediately downstream of the cloudy exhaust gas flow in the instantaneous heating zone 7, there is no re-adsorption to the dust 11 due to mixing of the mist 10 contained in the cloudy exhaust gas in the non-instantaneous heating zone and liquefaction of the vaporized mist, and the mist 10 is vaporized. Thus, the region where only the dust 11 in the separated state exists is maintained.

  The light irradiator 4 measures the dust concentration in a part of the area where only the dust 11 exists immediately downstream of the cloudy exhaust gas flow in the instantaneous heating area 7 (scattered light detection area 8 (colored area in the figure)). The measurement light 4a for detecting the scattered light 4b which is the basis of the above is irradiated as diffused light. At that time, the measurement light 4a synchronously detected with a constant wavelength is irradiated.

  The scattered light detector 5 detects the scattered light 4b scattered by the measurement light 4a being reflected by the dust 11 from which the mist 10 has been removed through the instantaneous heating region 7.

  In the flue 6 between the scattered light detector 5 and the scattered light detection region 8, there is a cloudy exhaust gas region that does not pass through the instantaneous heating region 7, but the measurement light 4a that is synchronously detected at a constant wavelength is used. When irradiated, the scattered light 4b scattered by the dust 11 in the scattered light detection area 8 is different from the scattered light scattered by the mist 10 and the mist adsorbing dust 10a in the cloudy exhaust gas area not passing through the instantaneous heating area 7. Since it becomes scattered light of a wavelength, it can be identified by the scattered light detector 5.

  Further, even if the scattered light having the same wavelength as the scattered light 4b generated from the scattered light detection region 8 is generated in the cloudy exhaust gas region that has not passed through the instantaneous heating region 7, the amount of scattered light is extremely low. Since the light intensity in the region 8 is extremely strong, the amount of scattered light from the cloudy exhaust gas region can be ignored.

  In addition, if the wavelength bands of the heating light 3a and the measuring light 4a are different from each other, the wavelength of the scattered light 4b is also different from those wavelengths, and the lights do not interfere with each other, and do not affect the detection value of the scattered light 4b. Will not be given.

  The computing device 12 is a device that computes the dust concentration from the light intensity of the scattered light 4b based on the fact that the scattered light 4b is proportional to the dust concentration. For example, if a calibration curve proportional to the dust concentration and the light amount is created in advance, the dust concentration with respect to the detected light amount of the scattered light 4b can be obtained from the calibration curve. The arithmetic device 12 and the scattered light detector 5 may be integrated.

FIG. 2 is a schematic cross-sectional view of another embodiment of the light scattering dust densitometer according to the present invention. The measurement principle is a method in which the scattered light detection area 8 is formed inside the instantaneous heating area 7.

  The light scattering dust concentration meter 2 includes a light irradiator 4, an instantaneous heater 3, a scattered light detector 5, and an arithmetic device 12, and the light irradiator 4 against the upstream to downstream flow of the cloudy exhaust gas. The instantaneous heater 3 and the scattered light detector 5 are arranged in this order and are accommodated in the box 1a.

  And the flange 1b of the box 1a is connected to the flange 6b of the connecting pipe 6c connected to the flue 6. In the figure, the double-headed arrow L2 is the opening diameter (inner diameter) of the opening 6a of the connecting pipe 6c. Thereby, the density | concentration of the dust 11 in cloudy exhaust gas can be measured like Example 1. FIG.

  In addition, about each structure of Example 2, since it is the same as the function and effect of Example 1 except being demonstrated below, the description is abbreviate | omitted.

  In the second embodiment, the arrangement order of the light irradiator 4, the instantaneous heater 3, and the scattered light detector 5 is different, and the order of the measurement light 4a and the heating light 3a is essentially different.

  Thereby, the scattered light detection area 8 can be positioned in the instantaneous heating area 7. As a result, the influence of the mist 10 can be suppressed lower than in the first embodiment. In particular, in Example 1, when the flow rate of the cloudy exhaust gas is slow and when the mist 10 coexists excessively, the mist 10 is transferred from other than the instantaneous heating region 7 and the mist vaporized in the instantaneous heating region 7. However, if the instantaneous heating area 7 and the scattered light detection area 8 are made the same as in the second embodiment, there is no influence from the mist 10 at all. The dust concentration in cloudy exhaust gas can be measured with extremely high accuracy.

  Furthermore, by arranging the light irradiator 4, the instantaneous heater 3, and the scattered light detector 5 in this order, the light can be accommodated in the box 1a in a compact manner, and the diameter of the opening 6a (L2) is the opening 6a of the first embodiment. It can be made smaller than the diameter (L1). Therefore, the existing connecting pipe 6c of the commercial standard can be used, and the installation of the light scattering dust concentration meter 2 becomes easy.

The light scattering dust concentration meter of the present invention can be easily and inexpensively attached to an existing flue. Also, since only dust in cloudy exhaust gas below the dew point, which was difficult until now, can be measured continuously and accurately in the flue, there is concern that the standard value may be exceeded for cloudy exhaust gas. Can provide explanatory evidence to local residents. Furthermore, it can be used for white smoke prevention measures. Therefore, it can be expected to greatly contribute to the technical field and industry of exhaust gas measurement.

1 Light Scattering Dust Densitometer 1a Box 1b Flange 2 Light Scattering Dust Densitometer 3 Instantaneous Heater 3a Heating Light 3b Focus 4 Light Irradiator 4a Measurement Light 4b Scattered Light 5 Scattered Light Detector 6 Flue 6a Opening 6b Flange 7 Instant heating zone 8 Scattered light detection zone 10 Mist 10a Mist adsorption dust 11 Dust 12 Arithmetic unit

Claims (4)

A dust concentration meter that directly measures the dust concentration in the cloudy exhaust gas inside the flue without sucking and sampling the cloudy exhaust gas that adsorbs and coexists with mist and dust inside the flue,
An instantaneous heater that forms an instantaneous heating zone in which heating light is converged in the flue and mist in the cloudy exhaust gas is vaporized;
A light irradiator that irradiates measurement light having a wavelength different from that of the heating light immediately downstream in the flow direction of the cloudy exhaust gas in the instantaneous heating region;
A scattered light detector for detecting scattered light scattered by reflecting the measurement light to the dust that has passed through the instantaneous heating region;
The instantaneous heater, the light irradiator, the light irradiator, and the scattered light arranged in the order of the instantaneous heater, the light irradiator, and the scattered light detector on the same side surface of the flue along the flow direction of the cloudy exhaust gas A box that houses the detector;
An arithmetic device for obtaining the dust concentration in the cloudy exhaust gas based on the scattered light intensity detected by the scattered light detector;
Consists of
A light scattering dust concentration meter, wherein the box is connected to one flange of a connecting pipe connecting to the flue. A dust concentration meter that directly measures the dust concentration in the cloudy exhaust gas inside the flue without sucking and sampling the cloudy exhaust gas that adsorbs and coexists with mist and dust inside the flue,
An instantaneous heater that forms an instantaneous heating zone in which heating light is focused in the flue and mist in exhaust gas is vaporized;
A light irradiator that irradiates the instantaneous heating region with measurement light having a wavelength different from that of the heating light;
A scattered light detector for detecting scattered light scattered by reflecting the measurement light to dust in the instantaneous heating region;
The light irradiator arranged in the order of the light irradiator, the instantaneous heater, and the scattered light detector on the same side surface of the flue along the flow direction of the cloudy exhaust gas, the instantaneous heater, the scattered light A box that houses the detector;
An arithmetic device for obtaining the dust concentration in the cloudy exhaust gas based on the scattered light intensity detected by the scattered light detector;
Consists of
A light scattering dust concentration meter, wherein the box is connected to one flange of a connecting pipe connecting to the flue. A method for directly measuring the dust concentration in the cloudy exhaust gas in the flue without sucking and sampling the cloudy exhaust gas in which the mist and dust are adsorbed and coexist in the flue,
Forming a heating zone in which a part of the cloudy exhaust gas in the flue is heated above the dew point by a vaporizer installed in a space continuously provided in the flue to vaporize mist,
Irradiate light from the same side as the vaporizer to the area where the mist is vaporized through the heating area or the heating area,
The scattered light scattered in the dust from which the mist has been removed is detected in the space on the same side as the vaporizer connected in the flue,
A dust concentration measuring method, wherein the dust concentration in the cloudy exhaust gas is obtained from the detected scattered light intensity. A method for directly measuring the dust concentration in the cloudy exhaust gas in the flue without sucking and sampling the cloudy exhaust gas in which the mist and dust are adsorbed and coexist in the flue,
A heating step of forming an instantaneous heating region in which heating light irradiated from an instantaneous heater installed in a space continuously provided in the flue is converged and mist in the cloudy exhaust gas is instantaneously vaporized, and
Irradiation step of irradiating measurement light having a wavelength different from that of the heating light from the same side as the vaporizing device to the instantaneous heating region or the region where the mist is vaporized through the instantaneous heating region, and
A detection step of detecting the scattered light scattered in the dust from which the measurement light has been removed from the mist on the same side as the vaporizer in the flue;
A calculation process for calculating the dust concentration in the cloudy exhaust gas based on the detected scattered light intensity;
A method for measuring dust concentration, comprising:

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