JP3604496B2 - Particle catcher of photoelectric particle concentration measuring device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention is a method for measuring the concentration of airborne particles such as dust, dust floating in a duct, and dust, and combustion gas for pulverized coal for turbine power generation, which is transported through an optical fiber to a base attached to the duct wall. The light emitting cylinder that emits the emitted light from the tip into the duct and the light receiving cylinder that is connected to the optical fiber that carries the scattered light of airborne particles that have entered the tip are ducted with each other's optical axis. The present invention relates to a particle catcher of a photoelectric particle concentration measuring device which is mounted so as to intersect with each other.
[0002]
[Prior art]
This type of particle catcher is attached to an opening of a duct wall surface, and scatters light proportional to the particle concentration into the main body of the photoelectric particle concentration measuring device to measure the particle concentration photoelectrically. In this case, by mounting the light emitting and receiving parts on both sides of the duct so as to face each other, there is no need to adjust the positional relationship between each other as compared with a known method of measuring the particle concentration based on the attenuation of light transmission. In recent years, the application has been expanded to not only dust and the like in a flue to be discarded but also measurement of a dust concentration in a high-temperature and high-pressure combustion gas for driving a turbine.
[0003]
[Problems to be solved by the invention]
However, when targeting such recent high-temperature and high-pressure particles, the optical fiber of the cylindrical body is deformed at a high temperature, or the adhesive for joining the fiber elements in a bundle is deteriorated, or the high-pressure particles are generated. There is a problem that the tip of the optical fiber in the exposed state is easily penetrated. Further, as another problem, when harmful substances are present in the duct, it is necessary to consider safety when entering the duct to remove the particle catcher during maintenance.
[0004]
In view of the above, an object of the present invention is to provide a particle catcher for a photoelectric particle concentration measuring device that can withstand use at high temperatures and high pressures and that can be easily maintained.
[0005]
[Means for Solving the Problems]
In order to achieve this object, according to the present invention, according to the present invention, the light emitted from the main body of the photoelectric particle concentration measuring device for measuring the particle concentration based on the scattered light by the particles in the duct is introduced into the duct. In order to project light and transport the scattered light reflected by the particles in the duct to the main unit, an optical fiber that transports light is connected to the base attached to the opening on the duct wall. A photoelectric particle concentration measuring device in which a light-projecting cylinder that projects light to a light source and a light-receiving cylinder that is connected to an optical fiber that conveys scattered light that has entered the tip end are mounted so that their optical axes intersect. In the particle catcher of (1), the light projecting and light receiving cylinders are composed of an outer cylinder attached to the base, and an inner cylinder screwed into the outer cylinder from behind and into which an optical fiber is inserted. The part has a central opening A light-transmitting window is provided in an airtight state, and a cap formed with a plurality of pairs of nozzles for discharging along the surface of the light-transmitting window is screwed, and one nozzle of each pair is connected to the other nozzle by a light-transmitting window. A ring-shaped air supply passage is formed between the outer peripheral surface of the cap and the inner peripheral surface of the outer cylinder, which is opposed to each other toward the center of the nozzle and offset from each other in the optical axis direction, and communicates with the base end of the nozzle. At the same time, a disk-shaped radiating fin having a diameter corresponding to the inner diameter of the outer cylinder is provided in the optical axis direction on the outer peripheral surface of the inner cylinder between the ring-shaped air supply passage and the gas intake port provided on the side of the outer cylinder. A plurality of air supply paths for guiding the gas taken in from the gas inlet to a part of the ring-shaped air supply path are formed by notching the ends of the disk-shaped heat radiation fins.
[0006]
During the measurement, the gas passing through the air supply passage between the inner cylinder and the outer cylinder partially passes through the notch along the radiation fin that cools the inner cylinder, into the ring-shaped air supply passage on the outer peripheral surface of the cap. From the plurality of nozzles, the gap and turbulence are suppressed along the surface of the light-transmitting window by the two-layer gas curtain and discharged at a pressure higher than the pressure in the duct. When it is desired to inspect the optical fiber, the nozzle or the light-transmitting window, the inner cylinder having the optical fiber attached thereto is removed behind while the outer cylinder is left. The optical fiber can be pulled out of the inner cylinder. The cap provided with the light-transmitting window and the nozzle can be removed from the inner cylinder with a screw.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
A particle catcher of a photoelectric particle concentration measuring apparatus according to an embodiment of the present invention will be described with reference to FIGS. In FIG. 3, reference numeral 9 denotes a particle catcher formed by penetrating the light projecting cylinder 7 and the light receiving cylinder 8 through the base 11 at 45 ° and welding the optical axes A and B to be orthogonal to each other. is there. The base portion 11 is provided with a screw through hole through a heat-resistant asbestos packing 12 in a frame-shaped seat portion 2 protruding around an opening 1a on a wall surface of a duct 1 for conveying pulverized coal combustion gas or the like. It is screwed at 11a. Reference numeral 15 denotes a deflector that blocks light so that light emitted from the light projecting cylinder 7 does not interfere with the light receiving cylinder 8.
[0008]
These cylinders 7 and 8 have the same structure, and as shown in FIG. 1, an outer cylinder 10 having a gas inlet 13 through which dustproof gas is supplied through a filter and an opening 14 at the front. And an inner tube 20 into which the optical fibers 4 joined in a bundle with an adhesive are inserted and screwed into the outer tube 10 via a silicon-based O-ring 29 with a screw portion 20a. The optical fiber 4 is formed by screwing a ring-shaped screw 23 with a screw portion 23a via a silicon-based O-ring 27 exhibiting heat resistance in a state where the sleeve 4a is in contact with the step portion 21. 20.
[0009]
A cap 30 is screwed into the distal end of the inner cylinder 20 with a screw portion 30a. A transparent window 31 made of quartz is fitted into the center opening 32 so as to withstand a high temperature by sealing the front surface with a ring-shaped Teflon packing 37 and the back surface with a silicon-based O-ring 39, The cap 30 discharges a dustproof gas from the periphery of the light transmitting window 31 along the surface thereof.
[0010]
For this gas discharge, a ring-shaped air supply passage 38 is formed between the stepped outer peripheral surface of the cap 30 and the inner peripheral surface of the outer cylinder 10, and a base end portion communicates with this air supply passage. Nozzles 33 are formed at equal intervals in the radial direction toward the center of the light transmitting window 31. A plurality of these nozzles are arranged in pairs facing each other toward the center of the light-transmitting window 31, and one nozzle 33 of each pair has an optical axis with respect to the other nozzle 33. It is offset slightly smaller than its inner diameter in the directions of A and B. That is, in FIG. 2C, for example, the four lower sides are slightly larger than the upper side with respect to the light transmitting window 31 to form a two-layer gas curtain in which mutual interference is suppressed.
[0011]
On the outer peripheral surface of the inner cylinder 20, two disk-shaped radiating fins 25 and 26 having a diameter separated from the optical axes A and B and having a diameter corresponding to the inner diameter of the outer cylinder 10 are formed. As shown in FIGS. 2A and 2B, cutouts 25 a and 26 a are formed on both sides and a lower part when viewed from the gas inlet 13, so that gas can be supplied between the inner peripheral surface of the outer cylinder 10 and a ring-shaped air supply passage. An air supply passage 38a is formed at a lower portion of the air supply 38. Each part of the outer cylinder 10 and the inner cylinder 20 described above is made of stainless steel.
[0012]
FIG. 4 shows the configuration of the light emitting unit 40 and the received light signal processing device 50 as a device main body constituting the particle concentration measuring device together with the particle catcher 9 thus configured. The light emitting section 40 includes a halogen lamp 41, a power supply 42 that receives the light emission by the Cds 43, and drives the halogen lamp 41 to automatically control the halogen lamp 41 to a predetermined light emission amount by feeding back the light reception signal, and a motor. It is provided with a chopper 44 that is driven and converts the light emitted from the halogen lamp 41 into an intermittent lightwave, and a light receiving element 45 that sends out the intermittent lightwave for a synchronization signal. This intermittent light wave is simultaneously conveyed to the light projecting cylinder 7 through the optical fiber 4.
[0013]
The light receiving signal processing unit 50 includes a light receiving element 53 for photoelectrically converting the light receiving signal carried in by the optical fiber 4 of the light receiving cylinder 8, and a phase shift adjusting circuit for aligning the amplified signal by the amplifier 53a with the synchronization signal in phase. 54, a shaping circuit 51 for generating a synchronization signal by slicing a transmission signal of the light receiving element 45 at a minute level and shaping the waveform, a synchronization detection circuit 52 for detecting a light reception signal synchronized with an input synchronization signal, A low-pass filter 52b for high-cutting the amplified output of the synchronously-detected signal amplified by the amplifier 52a; an integrating circuit 55 for integrating the high-cut signal; , An alarm means 57 for giving an alarm by sound or light when the output signal level exceeds a predetermined level, and a synchronizing circuit 51. No. is the Shitamawaru a reference level, and a warning means 58 to alert the abnormality of the light emitting portion 40.
[0014]
The operation of the photoelectric particle concentration measuring device having the particle catcher 9 configured as described above is as follows. The particle catcher 9 is attached to the opening 1a of the duct 1 for feeding the pulverized coal combustion gas at about 200 ° C. to the turbine via the packing 12 at the base 11 thereof. In this state, the light transmitting window 31 together with the packing 37 and the O-ring 39 keeps the inner cylinder 20 airtight against the pressure in the duct 1.
[0015]
Normal-temperature gas, such as air, supplied from the gas inlet 13 enters from both sides of the radiating fin 25, flows into the lower part of the ring-shaped air supply passage 38 through the lower end of the radiating fin 26, and is divided into two sides to be upward. In the process of flowing into the duct 1, the liquid is sequentially discharged from the nozzle 33 at a pressure higher than the pressure in the duct 1. The gas flow in the air supply passage 38a of the cylinders 7 and 8 is guided upward from both sides from the lower part of the ring-shaped air supply passage 38 when viewed from the gas intake 13 by the position setting of the notches 25a and 26a. Discharged. At that time, air rectification occurs on the inner peripheral surface of the inner cylinder 20 and the surfaces of the radiating fins 25 and 26, so that the air is efficiently cooled to room temperature and the heating of the optical fiber 4 is avoided. A plurality of pairs of opposed nozzles 33 are arranged in a radially offset manner so as to form a dust-free curtain with no gaps in two opposite layers along the surface of the light-transmitting window 31 with little turbulence. Intrusion of the dust contained in the light transmitting window 31 is prevented, and the adhesion is reliably cleaned.
[0016]
In such a state, the intermittent light wave of the chopper 44 is guided to the light projecting cylinder 7 through the optical fiber 4 and irradiates a light beam along the optical axis A through the light transmitting window 31. The scattered light reflected by the particles in the duct 1 in a substantially orthogonal direction enters the optical fiber 4 through the light transmitting window 31 of the light receiving cylinder 8 and is converted into an electric signal by the light receiving element 53 of the light receiving signal processing unit 50. You. The pulse-shaped light receiving signal is synchronously detected by the synchronous signal supplied from the light receiving element 45 by the synchronous detecting circuit 52 and subjected to waveform shaping, and noise having no synchronous relation is removed. Further, the signal is converted into a DC signal having a level proportional to the concentration of the particles in the duct by the low-pass filter 52b and the integrating circuit 55, and the concentration of the particles in the duct is indicated by the output means 56.
[0017]
When the output level exceeds the preset density, the alarm means 57 notifies the abnormality of the density. The alarm unit 58 notifies the abnormality of the apparatus when the chopper 44 does not generate the intermittent light or its level is lowered due to the abnormality of the light emitting unit 40. The inner cylinder 20 can be removed while leaving the outer cylinder 10 in the duct 1. The optical fiber 4 can be pulled out by removing the ring-shaped screw 23 while the duct 1 is being pumped, leaving the inner cylinder 20 hermetically sealed by the translucent window 31.
[0018]
In addition, such a particle catcher 9 can be attached to a side wall of a duct for feeding a blast furnace B gas at a pressure of, for example, about 2.6 kg / cm 2 to measure the particle concentration. At that time, the gas to be discharged is set to about 4 kg / cm 2 accordingly. Further, instead of the above-described embodiment, it is conceivable that the inner peripheral surface of the inner cylinder 20 is formed in a screw shape so as to more smoothly guide the gas. Further, the particle catcher 9 can naturally be used not only for high-temperature and high-pressure particles but also for measuring the concentration of particles under ordinary temperature and pressure.
[0019]
【The invention's effect】
According to the present invention, a ring-shaped air supply path is formed on the outer peripheral surface of the cap, and the gas is guided in a rectified state while cooling the radiation fins in the air supply path, and a plurality of nozzles forming a two-layer gas curtain are formed. Smooth ejection is performed without generating turbulent flow, and adhesion of particles to the light-transmitting window is reliably and efficiently prevented or removed, and the measurement accuracy is not impaired. By effectively cooling the inner cylinder with a plurality of radiation fins to which the optical fibers are mounted, the optical fibers are not damaged even if the inside of the duct is at a high temperature. The fact that the inner cylinder can be removed while leaving the outer cylinder allows the main part of the particle catcher to be removed without the need for work in the duct. For example, even when the fine powder end combustion gas or the like is pressure-fed in the duct, since the airtightness is maintained by the light-transmitting window at the tip of the inner cylinder, it is possible to electrically calibrate the apparatus body by removing only the optical fiber. Since the cap provided with the light-transmitting window and the nozzle can be attached to and detached from the distal end portion of the inner cylinder, not only is it advantageous in manufacturing but also maintenance thereof is facilitated.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a catcher according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view of each part of the catcher.
3A and 3B show an appearance of the catcher, wherein FIG. 3A is a plan view and FIG. 3B is a side view.
FIG. 4 is a diagram showing a circuit configuration of an apparatus main body connected to the catcher.
[Explanation of symbols]
1 Duct 4 Optical Fiber 9 Particle Catcher 10 Outer Cylinder 11 Base 13 Gas Inlet 20 Inner Cylinder 25, 26 Radiation Fin 30 Cap 31 Transparent Window 33 Nozzle

Claims (1)

Light emitted from the main body of the photoelectric particle concentration measurement device that measures the particle concentration based on the scattered light from the particles in the duct is projected into the duct, and the scattered light reflected by the particles in the duct is used as the main body of the device. An optical fiber for transmitting light is connected to the base attached to the opening of the duct wall to convey the light into the duct, and the light projecting cylinder that projects light from the tip into the duct, and the scattering incident on the tip In the particle catcher of the photoelectric particle concentration measurement device, which is attached so that the light receiving cylinder to which the optical fiber carrying the light is connected and the respective optical axes cross each other,
Light-emitting and light-receiving cylinders are composed of an outer cylinder attached to the base, and an inner cylinder into which an optical fiber is inserted while being screwed into the outer cylinder from behind,
At the tip of the inner cylinder, a light-transmitting window is provided in an airtight state at the center opening, and a cap formed with a plurality of pairs of nozzles for discharging along the surface of the light-transmitting window is screwed in. One of the nozzles of the pair faces the other of the nozzles toward the center of the light-transmitting window, and is offset from each other in the optical axis direction;
Between the outer peripheral surface of the cap and the inner peripheral surface of the outer cylinder, a ring-shaped air supply passage through which the base end of the nozzle communicates is formed, and a side of the ring-shaped air supply passage and the outer cylinder is formed. A plurality of disk-shaped radiating fins having a diameter corresponding to the inner diameter of the outer cylinder are formed in the optical axis direction on the outer peripheral surface of the inner cylinder between the gas intake ports provided in the portion,
An air supply path for guiding gas taken in from the gas inlet to a part of the ring-shaped air supply path is formed by notching an end of the disk-shaped heat radiation fin, wherein the photoelectric particle concentration is Measurement device particle catcher.

Images