WO2023219469A1

WO2023219469A1 - Dust measuring apparatus

Info

Publication number: WO2023219469A1
Application number: PCT/KR2023/006501
Authority: WO
Inventors: 연규철; 김기범
Original assignee: 동우옵트론 주식회사
Priority date: 2022-05-13
Filing date: 2023-05-12
Publication date: 2023-11-16
Also published as: KR102509923B1

Abstract

The present invention relates to a light transmission in-situ type dust measuring apparatus in which laser light is transmitted into a stack duct, and the amount of incident light is measured and converted into dust concentration. More specifically, the present invention relates to a dust measuring apparatus in which the optical path-air passage length of a reflector part is set to be longer than the diameter so that the flow of ejected purge air is laminar by the time the air reaches a measurement area, thus preventing dust (particles) from entering and accumulating in the optical path to preclude measurement interference factors in the optical path and increase the measurement efficiency and reliability of the apparatus. To this end, in the present invention, the ratio of the length to the diameter of the optical path-air passage is 1.0 or more, and a plurality of purge holes are formed in two or more rows.

Description

dust meter

The present invention relates to an in-situ type dust meter of the light transmission type that transmits laser light inside the chimney, measures the amount of incident light, and converts it into dust concentration. More specifically, it relates to an optical path of the reflector - air tank. By setting the length of the furnace to be longer than the diameter, the flow of ejected purge air forms a laminar flow when it reaches the measurement area, preventing dust (particulates) from entering and accumulating in the optical path passage and preventing interference with measurement on the optical path. It is about a dust measuring device designed to increase the measurement efficiency and reliability of the device.

In general, an in-situ type dust detector is inserted and installed by drilling a hole in an industrial stack duct (chimney, hereinafter referred to as a 'chimney'). During combustion, combustion including dust emitted through the chimney is carried out. This is a device that measures and analyzes the dust concentration in the exhaust gas discharged to the outside through the chimney in real time on site by installing a part of the dust meter exposed to the exhaust gas flow.

Referring to FIGS. 1 to 2(a)(b), the most accurate conventional in-situ type dust meter is to measure the combustion exhaust gas (G) inside the chimney (4) where the flow is formed. Among the elements that make up the in-situ dust detector, a probe (20) in the form of a circular pipe with an optical path is installed to penetrate the wall of the chimney (4) and be directly inserted into the interior.

In addition, the dust concentration is measured using a light transmission method. A high-efficiency laser diode with a red visible light range wavelength of 645nm - 660nm is used as a light source, and the laser light is transmitted through the measurement area (R) to the measurement detector. The amount of light incident on the (Measuring detector) is measured and converted into dust concentration.

Inside the main body of the measuring instrument (10), a monitor detector that does not pass through the chimney, or measurement section, is installed to check the light source's own light amount in real time and apply the variation of the light source to the received light amount to reduce measurement error.

As a specific example for this, a conventional dust detector is equipped with various optical device parts including a light source and a sensing means in the main body 10, and is connected to one side of the main body 10 to measure the wall of the chimney 4. It is provided with a probe (20) in the form of a circular pipe that is installed penetratingly.

At this time, the probe 20 reflects the entry pipe portion 21 inserted through the wall inside the chimney, the reflector portion 22 including a reflector 22a that reflects light, and the entry pipe portion 21. It has a structure including an air pipe portion (23) that supports the neck portion (22) and divides the measurement area (R) for measuring dust in the chimney.

This air pipe portion 23 opens the optical path between the entry pipe portion 21 and the reflector portion 22 so that combustion exhaust gas (including particulate dust) (G) can pass through, and this portion is opened in the measurement area (R). ) applies the open path method.

Accordingly, the measurement area (R) corresponds to the length (H3) of the air pipe portion (23), which is the length from the end (a) of the entry pipe portion (21) to the end (b) of the reflector portion (22). It applies.

Meanwhile, the combustion exhaust gas including dust within the measurement area must not come into direct contact with the optical path formed at the end (a) of the entry tube portion (21) and the end (b) of the reflector portion (22). Combustion exhaust gas may be in direct contact with the inside of the optical path passage of the end (a) of the entry pipe portion (21) and the end (b) of the reflector portion (22), which does not have a separate glass window to prevent dust intrusion. In this case, particulate dust contained in the combustion exhaust gas invades the optical path, and such dust eventually accumulates on the optical path and acts as a factor that interferes with the measurement of the device. This becomes a factor that reduces the measurement efficiency and reliability of the dust detector.

Meanwhile, Reynolds number is a dimensionless number used to predict fluid flow as the ratio of the force due to inertia and the force due to viscosity.

When the Reynolds number is low, the fluid shows a laminar flow, and when the Reynolds number is high, it shows a turbulent flow phenomenon. In the case of water pipe flow, such as the flow in a normal circular pipe, the critical Reynolds number is about 2,100, which is laminar flow. If the Reynolds number is between about 2,900 and 4,000, it is considered a transition region where the nature of the flow cannot be accurately stated, and if it is over about 4,000, it is called turbulent flow. . A high Reynolds number means that the inertial force of the fluid is higher than the viscous force.

For example, referring to FIG. 3(a), when fluid (e.g., air) passing through a conduit in a circular pipe passes through a hole and is ejected into the conduit due to the injected pressure, it flows in. At the entrance of the hole, a turbulent flow is formed, and as it flows along the length of the pipe, it passes through the transition area and forms a stable laminar flow.

Therefore, in order to form a laminar flow with a stable fluid flow, it must have a certain length from the hole depending on the pressure.

On the other hand, the fluid that passes through the hole and flows into the pipe hits a blockage in the direction of the ejected flow, creating a whirlpool-like flow when the pressure is maintained.

With reference to this, referring again to FIGS. 1 to 2 and FIG. 3(b), a conventional dust measuring device is as follows.

The conventional dust meter prevents dust from entering the interior through the open optical path formed at the end (a) of the entry pipe portion 21 and the end (b) of the reflector portion 22 and from accumulating on the end side. To this end, purge air supplied from the air pump device 3 is forced into the probe 20 at a set pressure, and the end (a) of the entry pipe portion 21 and the end of the reflector portion 22 ( As the purge air is ejected according to the flow on the optical path formed at b), it prevents the particulate dust contained in the combustion exhaust gas from accumulating or flowing into the optical path formed at the ends (a, b) (Figure 2b).

Specifically, the purge air forcibly supplied from the air pump device 3 travels through the optical path passage formed inside the entry pipe unit 21 as an air passage to open the optical path at the end (a). It is ejected into the chimney (4) through the passage, and the reflector portion (22) forces the purge air supplied from the air pump device (3) to move through the entry pipe portion (21) and the air pipe portion (23) connected thereto. It enters the inside of the reflector unit 22 and has a structure in which purge air is ejected by pressure on the optical path where the reflector 22a is located through the purge hole 22b formed inside the reflector unit 22.

At this time, the entry pipe part 21 installed while penetrating the wall inside the chimney is manufactured to have a certain length depending on the size of the chimney. Since the length (H1) must penetrate the wall of the chimney and extend to a point where measurement is possible. It is bound to have a length (H1) much longer than the diameter of the optical path formed at the end (a).

That is, since there is a sufficient length from the point connected to the air pump device 3 to its end (a), the purge air is incident vertically on the optical path, which is an air passage, at the inlet side, forming turbulent flow, but the length in the longitudinal direction is much longer than the optical path diameter of the ejected end (a), making it a sufficient length (Figure 1, H1) to form a laminar flow according to the flow. Accordingly, the purge air discharged from the open optical path passage at the end (a) of the entry pipe portion 21 to the measurement area (R) forms a laminar flow without being caught, and dust comes into contact with the optical path passage at the end (a). Inflow can be blocked.

In other words, the purge air stably forms a laminar flow as it passes through the optical path passage of the entry pipe part 21, and as it passes over the end of the optical path passage and flows into the measurement area (R), dust flows into the optical path passage side. It can be completely blocked. As long as the pressure of the purge air discharged through the optical path passage at the end (a) is equal to or greater than the pressure of the combustion exhaust gas (G) discharged within the chimney, particulate dust is transmitted to the optical path at the end (a) of the entry pipe portion (21). There is no possibility of it flowing into the passage (air passage).

However, referring again to FIG. 3(b), the reflector unit 22 constituting the dust measuring device allows the purge air forced in through the air pipe unit 23 to pass perpendicularly to the optical path through the purge hole 22b. It flows in and is ejected, and at the entrance to the purge hole 22b, a turbulent flow is formed due to the inertial and viscous forces of the purge air. In addition, the ejected purge air collides with the reflector 22a, which is installed in the longitudinal direction and cannot help but block the air flow to one side, and if the pressure is stable, a vortex-like effect occurs near the reflector 22a where the collision occurs with the purge air. flow may occur.

At this time, the purge air sweeps the surface of the reflector 22a to prevent the inflow of dust to some extent, but since the length of the optical path is very short, it flows directly on the open optical path to the measurement area (R). is discharged.

In other words, the reflector portion 22 of the conventional dust measuring instrument is the path length (L) for the purge air to go out to the measurement area (R) for the diameter (D) of the optical path that is the air path - the end from the extreme end of the purge hole. As the length-to-length ratio (b) is short, less than 1.0, and the purge hole 22b forms a single hole, the ejected purge air does not have room to form a laminar flow and forms turbulent and vortex flows.

Such turbulent flow according to the short passage length (L) meets the flow of combustion exhaust gas (G) passing through the measurement area (R) in the chimney, forming irregular turbulence and vortices, and these turbulences, vortices, and vortices A problem was discovered where dust (Ch) was accumulated at points “A” and “B” on the optical path passage of the short reflector portion 22 due to the same flow.

It is possible to prevent dust (Ch) accumulation by simply increasing the pressure of the purge air that is forcefully introduced and increasing the amount of purge air that is ejected, but this ultimately affects the flow of combustion exhaust gas (G) within the measurement area (R). Not only does it have an impact, but it only results in lowering measurement efficiency and reliability.

In addition, since the turbulent flow due to the short passage length (L) is not uniform even if the pressure of the purge air is increased, there was a risk that the reference point of the optical path, which is the reference path for measurement, may be deformed.

In the end, the dust (Ch) accumulated on the optical path and the continuous turbulent flow on the optical path ultimately act as a factor in interfering with the measurement of the dust measuring instrument, causing problems that inevitably raise questions about the measurement efficiency and reliability of the dust measuring instrument. did.

Accordingly, in developing a dust measuring device, a structure that can block particulate dust from entering through the open optical path formed at the end of the probe while efficiently utilizing the pressure of purge air (minimizing pump capacity), especially including a reflector, The development of a dust measuring device that can completely block dust from entering the reflector is becoming an urgent topic.

The present invention was developed to solve the above-mentioned problems. By setting the optical path-air path length of the reflector unit to be longer than the diameter, the flow of ejected purge air forms a laminar flow when it reaches the measurement area, thereby preventing dust (dust) in the optical path path. The purpose is to provide a dust measuring device that prevents interference with measurement in the optical path by blocking the inflow and accumulation of particles and increases the measurement efficiency and reliability of the device.

In order to achieve the above object, a dust measuring device according to the present invention includes a main body including a light source; It is connected to the main body and receives purge air internally through an air pump device, and has an entry pipe portion having an optical path-air passage, a reflector inside, and an optical path-air passage on a concentric axis with the entry pipe portion. A probe consisting of a reflector portion and an air pipe portion that connects and supports the end of the entry pipe portion and the end of the reflector portion to form an air passage and opens the optical path into the chimney to form a measurement area. Includes.

At this time, the reflector portion of the present invention has a diameter equal to the end side diameter of the optical path-air passage of the entry pipe portion, a reflector is placed inside, and a barrel body is formed through a plurality of purge holes at a position close to the reflector. ; It surrounds the barrel body while forming an internal space, and includes an outer cylinder body formed to communicate with the air passage of the air pipe part and the internal space.

At this time, in the barrel body, the ratio of the passage length from the end of the purge hole closest to the measurement area to the light path-air passage diameter is 1.0 or more, and the purge holes are plural at intervals and are identical along the outer peripheral surface of the barrel body. It is arranged in a line at intervals and is characterized by being formed in two or more rows.

Preferably, the reflector unit is characterized in that the pressure of purge air ejected into the optical path-air passage through the purge hole is equal to or greater than the pressure of the combustion exhaust gas flow discharged through the chimney.

Meanwhile, the purge holes are preferably arranged so that the purge holes forming one row are staggered from the purge holes forming an adjacent row.

And, the purge holes are characterized in that the sum of the cross-sectional areas of the total number is equal to the cross-sectional area of the optical path-air passage diameter.

Meanwhile, in the air pipe part, four pipes are arranged in a circle at equal intervals.

Additionally, the entry pipe portion has a long double pipe shape. For example, the entry pipe part includes an outer cylinder connected to the main body and having a flange supported on the chimney wall while forming an air inlet connected to an air pump device on one side; It is disposed on the inside while forming an outer cylinder and an air passage, and includes an inner cylinder that forms a light path-air passage at the inner center while forming a plurality of purge holes in communication with the air inlet through the outer circumference.

In this way, the dust measuring device according to the present invention sets the optical path-air path length of the reflector part to be longer than the diameter, so that the flow of ejected purge air forms a laminar flow when it reaches the measurement area, thereby preventing dust (particles) from forming in the optical path path. By blocking inflow and accumulation, it has the effect of preventing measurement interference in the optical path and increasing the measurement efficiency and reliability of the device.

In addition, accurate measurements can be made without interfering with the flow of combustion exhaust gases within the measurement area, which has the effect of maximizing the reliability of the device.

Figure 1 is a schematic diagram showing the installed state of an in-situ type dust meter.

Figure 2(a)(b) is a schematic diagram showing the state of measurement using the light transmission method of the dust measuring device according to Figure 1 and the state of preventing dust intrusion using purge air.

Figure 3(a) is a schematic diagram showing the state of fluid (air) passing through a conduit in a circular pipe.

FIG. 3(b) is a schematic diagram showing a state in which dust infiltrates and accumulates on the optical path in the reflector portion of the dust measuring device according to FIG. 1.

Figure 4 is a schematic perspective view showing a dust meter according to the present invention.

Figure 5 is a schematic diagram showing the dust meter according to Figure 4 cut in the longitudinal direction.

Figure 6 is a schematic diagram showing an enlarged reflector portion of the dust meter according to Figure 5.

Figure 7 is a schematic diagram for explaining the flow of purge air appearing in the reflector portion of the dust meter according to Figure 5.

Hereinafter, a preferred embodiment of the dust meter according to the present invention will be described in detail with reference to the attached drawings.

In explaining the present invention, the longitudinal direction is assumed to indicate the horizontal direction when the dust meter is installed in the chimney.

Meanwhile, in describing the present invention, detailed descriptions of related known functions or configurations will be omitted in order to not obscure the gist of the present invention.

Additionally, when a part "includes" a certain component, this means that it may further include other components, rather than excluding other components, unless specifically stated to the contrary.

It should be noted that the same components among the drawings are indicated with the same reference numbers and symbols as much as possible, even if they are shown in different drawings.

Referring to Figures 4 to 7, as shown, the dust meter 1 according to the present invention is an in-situ type light transmission type that measures the amount of incident light and converts it into dust concentration. The biggest feature is that it blocks dust (particles) from entering and accumulating in the furnace passage. For this purpose, the dust measuring instrument (1) of the present invention sets the optical path-air path length (L1) of the reflector unit (220) to be longer than the diameter (D1), so that the flow of ejected purge air is measured in the measurement area (R). At this point, it has a structure that forms a laminar flow.

More specifically, the dust measuring instrument 1 of the present invention is largely composed of a main body 100 and a probe 200.

First, the main body 100 includes a light source, which is the same structure as that applied to a conventional in-situ type dust meter, and a detailed description of its structure and function does not obscure the gist of the present invention. In order not to do this, we will omit it.

And, the probe 200 has a structure largely including an entry tube portion 210, a reflector portion 220, and an air tube portion 230.

The entry pipe portion 210 is connected to the main body portion 100, receives purge air (air) internally through the air pump device 3, and has an optical path-air passage LP1.

Specifically, the entry pipe portion 210 has a double pipe structure in the form of a circular pipe having a length, and is connected to one side of the main body portion 100, forming an air inlet portion 214 connected to the air pump device 3 on one side. An outer cylinder (212) having a flange (213) supported on the chimney (4) wall; It is disposed inside while forming the outer cylinder 212 and the air passage 212a, and forms a plurality of purge holes 211a communicating with the air inlet 214, forming an optical path-air passage LP1 at the inner center. It has a structure including an inner cylinder (211).

At this time, it is preferable that a plurality of purge holes 211a of the entry pipe part 210 are formed along the outer peripheral surface of the inner cylinder 211 with the same size and shape. The number and size of the purge holes 211a can be determined using a dust meter. It can be determined based on the size of the chimney or the pressure and flow rate of combustion exhaust gas (G) discharged through the chimney.

Of course, the shape of the purge hole (211a) can have various shapes such as circular, oval, and polygon. However, each purge hole (211a) can blow out purge air uniformly toward the optical path-air path (LP1). It is desirable to have it.

In addition, preferably, when the purge air forced through the purge hole 211a is discharged from the end (a) to the measurement area (R) along the optical path-air passage (LP1), the combustion exhaust gas having a flow in the chimney Ensure that the pressure is equal to or higher than the pressure in (G).

In addition, the reflector unit 220 is provided with a reflector 223 for measurement inside and has an optical path-air passage LP2 on a concentric axis with the entry tube unit 210.

Referring to Figures 6 and 7, the reflector unit 220 constituting the dust measuring instrument 1 of the present invention, in one embodiment, includes an optical barrel body 221 having an optical path-air passage LP2, and an air It has a structure of an external cylinder 222 in communication with the air passage 231 of the pipe portion 230.

First, the barrel body 221 has a diameter (D1) that is the same as the diameter (D11 in FIG. 5) at the end (a) side of the optical path-air passage (LP1) of the entry pipe portion 210, and the measurement is performed therein. The reflector 223 is disposed to be supported by a fixture 224 - a spring or an elastic supporter - and a plurality of purge holes P are formed through it at a position close to the reflector 223.

At this time, preferably, a plurality of the above-mentioned purge holes (P) are spaced apart and are arranged at intervals along the same line along the outer peripheral surface of the barrel body 221, and are formed in two or more rows in the longitudinal direction of the barrel body 221. do.

Of course, the shape of the purge hole (P) can have various shapes such as circular, oval, and polygon. However, each purge hole (P) can blow out purge air uniformly toward the optical path-air path (LP2). It is desirable to have it.

In the illustration, the purge holes (P) are formed in three rows, and are shown in rows P1, P2, and P3 starting from positions close to the measurement area (see Figure 6).

In addition, the purge holes P are preferably arranged in a position where the purge holes forming one row are staggered from the purge holes forming an adjacent row.

In addition, preferably, when the purge air forced through the purge hole (P: P1, P2, P3) is discharged from the end (b) to the measurement area (R) along the light path-air passage (LP2), it is inside the chimney. Ensure that the pressure is equal to or higher than that of the combustion exhaust gas (G) having a flow.

The purge air forcefully introduced through the purge holes (P: P1, P2, P3) formed in this way is ejected into the optical path-air passage (LP2) inside the barrel body 221, from the purge holes in each neighboring row. As the ejected purge air pushes and interacts with each other, it is possible to completely prevent dust from accumulating near the reflector 223 - "A" (see Figure 3b).

Meanwhile, in the dust measuring device of the present invention, the barrel body 221 of the reflector unit 220 is located at the end (the end) of the purge hole (P) closest to the measurement area (R) for the optical path-air passage diameter (D1). The biggest characteristic is that the ratio of the optical path-air path length (L1) formed from ) to the end (b) is 1.0 or more (L1/D1 ≥ 1.0).

The ratio of the optical path-air path length (L1) formed from the end (most end) of the purge hole (P) closest to the measurement area (R) to the end (b) to the optical path-air path diameter (D1) is 1.0. If it is less than that, as found in the dust measuring device according to the prior art, the light path-air path length (L1) is too short and the purge air is discharged to the measurement area (R) in a turbulent state without forming a laminar flow.

Accordingly, when the ratio is a short passage length (L1) less than 1.0, the turbulent flow of purge air meets the flow of combustion exhaust gas (G) passing through the measurement area (R) in the chimney, forming irregular turbulence and vortices. There is a risk that dust (Ch) may accumulate at points “A” and “B” on the optical path of the short reflector portion 22 due to such turbulent, eddy, and whirlpool-like flows (see FIG. 3B).

Therefore, in order for the purge air exiting the optical path-air passage (LP2) to exit while forming a laminar flow at the end (b), the purge hole (P) is closest to the measurement area (R) for the optical path-air passage diameter (D1). It is most desirable that the ratio of the optical path to the air path length (L1) formed from the end (most end) to the end (b) is always 1.0 or more.

Of course, the final optical path-air path length (L1) can be changed depending on the pressure and flow rate of the combustion exhaust gas flow in the chimney and the pressure of the purge air flowing into the optical path-air path.

In addition, the outer cylinder 222 of the reflector portion 220 is shaped to surround the barrel body 221 while forming an interior space (S), and forms the air passage 231 of the air pipe portion 230 and the interior space (S). is formed in a continuous manner. The purge air forced into the internal space (S) is ejected into the optical path-air passage (LP2) through the purge holes (P: P1, P2, P3) described above.

Meanwhile, as described above, the dust measuring device 1 according to the present invention has a purge hole P closest to the measurement area R for the optical path-air path diameter D1 in the reflector unit 220. The ratio of the optical path to the air path length (L1) from the end (most end) to the end (b) must be 1.0 or more, and the amount of purge air forced in through the purge holes (P: P1, P2, P3) must be evenly distributed. You have to let it out.

In this way, in order to evenly distribute the amount of purge air forced through the purge holes (P: P1, P2, P3), it is preferable that the sum of the cross-sectional areas of the total number of purge holes (P: P1, P2, P3) is the optical path - It is characterized by being equal to the cross-sectional area of the air passage diameter (D1).

By equalizing the area of the inlet where air enters and the area of the outlet where air is discharged, the purge air ejected from each purge hole is evenly dispersed and ejected, and changes from turbulent flow to laminar flow through the transition area on the optical path-air passage (LP2). Stable laminar flow can be formed by minimizing flow changes in length.

As the flow of purge air discharged through the light path-air path at the end (b) side achieves a stable discharge in a laminar flow, the combustion exhaust gas (G) comes into direct contact with the light path-air path at the end (b) side. This is blocked, and particulate dust is also blocked from entering the optical path-air path (blocking dust accumulation as shown in "B" in Figure 3b).

On the other hand, as described above, the air tube portion 230 of the probe 200 constituting the dust measuring instrument 1 according to the present invention has an end (a) of the entry tube portion 210 and an end (b) of the reflector portion 220. ) is connected and supported to form an optical path in the form of a pipe forming an air passage 231, thereby forming a measurement area (R) by opening the optical path within the chimney (4).

At this time, in a preferred embodiment, referring again to FIG. 4, the air pipe portion 230 consists of four pipes arranged in a circle at equal intervals.

The air pipe section 230, in which four pipes are arranged in a circle with spacing from each other, can not only stably support the entry pipe section 210 and the reflector section 220, but also has an open shape on all sides between the pipes in the longitudinal direction. In addition to the simple exhaust flow from the bottom to the top of the combustion exhaust gas (G) in the chimney, dust in the optical path can be exposed regardless of the direction of the exhaust flow due to turbulent flow due to changes in pressure and flow rate within the chimney. .

The conventional dust meter, which only formed an open section at the top and bottom, was bound to have an error in measurement if the combustion exhaust gas (G) flowed left or right instead of up and down, but the dust meter according to the present invention ( 1) Measures without being affected by the flow direction of combustion exhaust gas (G) in the chimney as the four pipe-shaped air pipe parts 230 that make up the probe 200 form a measurement area (R) on the optical path. This can increase the measurement efficiency and reliability of the device.

Meanwhile, referring again to FIGS. 4 to 7, the purge air flow and usage state of the dust meter 1 according to the present invention are as follows. The process and flow of measuring dust concentration using a light transmission method are already known, and description thereof will be omitted below in order to not obscure the gist of the present invention.

As described above, the dust meter 1 according to the present invention is an in-situ type of light transmission type that measures the amount of incident light and converts it into dust concentration, so that dust (particles) flows into the optical path. Its main characteristic is to block accumulation of water, and it has a composition and structure for this purpose.

In other words, it blocks dust from flowing in and accumulating on the optical path and air path (LP1, LP2) in the dust meter (1).

To prevent dust from entering and accumulating, air from the air pump device (3) is used, and purge air of a set pressure delivered from the air pump device (3) is forced into the air inlet 214 of the probe 200. do.

A portion of the introduced purge air has a flow that moves toward the end (a) through the purge hole (211a) of the entry pipe portion (210) and along the optical path-air passage (LP1). At this time, the length of the optical path-air passage (LP1) of the entry pipe portion 210 is sufficiently longer than the diameter (D11 in FIG. 5) of the end (a) side of the optical path-air passage (LP1). As the purge air passes through the air passage (LP1), it is discharged to the end (a) while stably forming a laminar flow.

In other words, the purge air flowing in through the purge hole (211a) forms turbulence near the purge hole (211a) as it is incident perpendicular to the longitudinal direction, but the length of the light path-air path (LP1) is long, so the transition area is When it is finally discharged, a stable laminar flow is formed.

In addition, the purge air that forms a laminar flow flows over the optical path-air path (LP1) at the end (a) and flows into the measurement area (R), completely blocking the inflow of dust into the optical path-air path (LP1). You can.

As long as the pressure of the purge air discharged through the light path-air passage (LP1) at the end (a) is greater than the pressure of the combustion exhaust gas (G) discharged within the chimney, particulate dust is transferred to the end (a) of the entry pipe portion (210). There is no possibility of it flowing into the side optical path (air passage).

Meanwhile, another part of the purge air forced into the air inlet 214 moves along the air passage 212a formed between the outer peripheral surface of the inner cylinder 211 and the inner peripheral surface of the outer cylinder 212, and enters the air pipe portion 230. It flows into the internal space (S) of the reflector unit (220) through the air passage (231).

At this time, the internal space (S) can be divided into a passage internal space (S1) formed on the optical path-air passage (LP2) side and a compressed internal space (S2) formed on the reflector 223 side. The internal space ( The purge air flowing into S) passes through the passage inner space (S1), some of it is ejected onto the light path-air passage (LP2) through the purge hole (P), and the other part passes through the passage inner space (S1). Enters the compressed internal space (S2). Since the compressed internal space (S2) is blocked, the purge air stays in the compressed internal space (S2) for a while and is compressed, then moves strongly toward the purge hole (P) again and is ejected onto the optical path-air path (LP2).

And, in the light path-air path (LP2) on the purge hole (P) side, the purge air inertially forms turbulence. At this time, as the purge holes (P) are composed of two or more rows, the purge air emitted from each purge hole (P1, P2, and P3) interacts with each other to sweep and clean the reflector 223.

Meanwhile, the ratio of the passage length (L1) formed from the end of the purge hole (P) closest to the measurement area (R) to the end (b) to the optical path-air passage diameter (D1) is 1.0 or more, and the optical path-air passage diameter (D1) is 1.0 or more. As it passes through the air passage (LP2), it crosses the purge air transition area and forms a stable laminar flow when it is finally discharged.

In addition, the purge air that forms a laminar flow flows over the optical path-air path (LP2) at the end (b) and flows into the measurement area (R), completely blocking the inflow of dust into the optical path-air path (LP2). You can.

As long as the pressure of the purge air discharged through the light path-air passage (LP2) at the end (b) is greater than the pressure of the combustion exhaust gas (G) discharged within the chimney, particulate dust is transferred to the end (b) of the entry pipe portion (210). There is no possibility of it flowing into the side.

As described above, the dust measuring instrument (1) according to the present invention sets the optical path-air path length to be longer than the diameter, so that the flow of ejected purge air forms a laminar flow when it reaches the measurement area (R), thereby maintaining the optical path. By preventing dust (particles) from entering and accumulating in the passage, interference with measurement in the optical path can be prevented in advance and the measurement efficiency and reliability of the device can be improved.

The present invention described above is limited to the above-described embodiments and attached drawings, as various substitutions, modifications and changes can be made by those skilled in the art without departing from the technical spirit of the present invention. It doesn't work.

Claims

A main body 100 including a light source; An entry pipe part 210 that is connected to the main body part 100 and receives purge air (air) internally through an air pump device 3 and has an optical path-air passage LP1, and a reflector 223 therein. A reflector portion 220 having a light path-air passage LP2 on a concentric axis with the entry pipe portion 210, an end (a) of the entry pipe portion 210, and an end (a) of the reflector portion 220 ( A probe 200 consisting of an air pipe portion 230 that connects and supports b) and opens an optical path in the chimney 4 in the form of a pipe forming an air passage 231 to form a measurement area (R); In the in-situ type dust meter using a light transmission method including,

The reflector unit 220,

It has a diameter (D1) equal to the diameter (D11) of the end (a) side of the optical path-air passage (LP1) of the entry tube part (210), and the reflector (223) is disposed inside, and the reflector (223) A barrel body (221) formed through a plurality of purge holes (P) at a position close to and through;

It includes an outer cylinder 222 that surrounds the barrel body 221 while forming an interior space (S) and communicates with the air passage 231 of the air pipe portion 230 and the interior space (S);

The barrel body 221 is,

The ratio of the passage length (L1) from the end of the purge hole (P) closest to the measurement area (R) to the end (b) to the optical path-air passage diameter (D1) is 1.0 or more,

A dust measuring instrument characterized in that the plurality of purge holes (P) are spaced apart and are arranged along the same line at intervals along the outer peripheral surface of the barrel body 221, and are formed in two or more rows.
According to clause 1,

The reflector unit 220,

The pressure of purge air (air) ejected into the light path-air passage (LP2) through the purge hole (P) is equal to or greater than the pressure of the flow of combustion exhaust gas (G) discharged through the chimney (4). Features a dust measuring instrument.
According to clause 1,

The purge holes (P) are a dust meter, characterized in that the purge holes forming one row are arranged in a position where the purge holes forming an adjacent row are staggered.
According to clause 1,

A dust measuring instrument characterized in that the sum of the cross-sectional areas of all purge holes (P) is equal to the cross-sectional area of the optical path-air path diameter (D1).
According to clause 1,

The air pipe part 230 is a dust measuring instrument characterized in that four pipes are arranged in a circle at equal intervals.
According to clause 1,

The entry pipe portion 210 is in the form of a long double pipe pipe,

An outer cylinder 212 connected to the main body 100 and having a flange 213 supported on the wall of the chimney 4 while forming an air inlet 214 connected to the air pump device 3 on one side,

It is disposed inside while forming the outer cylinder 212 and the air passage 212a, and a plurality of purge holes 211a in communication with the air inlet 214 are formed penetrating on the outer circumferential surface and the optical path - A dust measuring instrument comprising an inner cylinder (211) forming an air passage (LP1).