JP2003315268A - Dust detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dust detector capable of performing real-time monitoring, reliably monitoring even a low concentration of dust without relying on workmen's experiences, and preventing the danger of dust explosion. <P>SOLUTION: The dust detector has a piping 1 for transferring a body to be transferred such as powder, particulates, or the like; a transferring device for transferring the body to be transferred in one direction through the piping 1; a pair of transparent windows 4 and 4 provided for opposite surfaces of the piping 1; a light projecting part 2 provided outside the transparent window 4 on one side for projecting detecting light into the piping 1 via the transparent window 4; a light receiving part 3 provided outside the transparent window 4 on the other side for receiving the detecting light transmitted through the piping 1 and converting the quantity of light into an electric signal; and a sensor controller for receiving the input of the electric signal outputted from the light receiving part 3 and outputting an anomaly signal when the electric signal exceeds a predetermined threshold. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dust in a work process including a risk of dust explosion in a production / treatment facility that generates dust such as electronic / electrical equipment, automobiles, industrial machines, packaging containers, building materials, and foods. The present invention relates to a device for detecting an amount, and more particularly to a dust detection device connected to the device for detecting the amount of dust in a pipe through which the dust as a transported object flows.

[0002]

2. Description of the Related Art In order for a dust explosion to occur, it is necessary that the energy for igniting a substance, the elementary concentration for continuing the explosion, and the dust concentration for the explosion are satisfied. When the humidity is high, the dust explosion limit concentration rises. In order to prevent a dust explosion that causes a major accident, it is necessary to monitor the dust concentration in real time and reduce the concentration before the explosion concentration is reached.

[0003]

In the conventional dust detection device, a certain amount of air in the space in which dust is present is sucked in,
This structure measures the amount of dust contained in the air. Since such a dust detection device sucks dust and performs analysis, it takes some time to obtain a result. Therefore, there is a difference between the output dust amount and the dust amount actually present in the target space at that time. Therefore, in reality, monitoring is performed by relying on the experience of the worker.

In other words, although there was a monitoring technique for monitoring the amount of dust, it was not real-time monitoring, and it was inevitable to rely on the experience of the operator, and it was not for efficiently monitoring low-concentration dust.

The present invention has been made in order to solve the above-mentioned problems, and enables real-time monitoring, and reliably monitors even low-concentration dust without relying on the experience of the operator. An object of the present invention is to obtain a dust detection device that can prevent dust explosion and prevent the danger of dust explosion.

[0006]

A dust detecting apparatus according to the present invention includes a pipe for conveying a conveyed object such as powder or granules,
A transport device that transports the transported object in one direction in the pipe, a pair of transparent windows provided on the opposite surfaces of the pipe, and a transparent window provided outside the transparent window on one side to detect in the pipe. Input a light projecting unit that projects light, a light receiving unit that is provided outside the transparent window on the other side and that receives the detection light that has passed through the pipe and converts the amount of light into an electrical signal, and the electrical signal that the light receiving unit outputs And a sensor controller that outputs an abnormal signal when a predetermined threshold value is exceeded.

Further, the sensor controller outputs an analog electric signal based on the amount of received light which increases or decreases depending on the transported object to the data logger device.

Further, it has a control unit for inputting an abnormal signal from the sensor controller and stopping the carrying device.

Further, the inner surface of the transparent window is subjected to static electricity removal processing.

Further, it has a purging device for blowing off the deposits adhering to the inner surface of the transparent window.

Further, a plurality of sets of a pair of transparent windows, a light projecting section, a light receiving section, and a sensor controller are provided, and the control section calculates a logical sum of a plurality of abnormal signals output from the plurality of sensor controllers. Stop the transport device.

Further, the straight lines connecting the plurality of sets of light emitters and light receivers make mutually different angles with respect to the central axis of the pipe.

Further, it has a straightening plate which is provided in the pipe and straightens the flow of the transported object.

Further, it has a flow rate sensor for detecting that the flow rate in the pipe has decreased.

Further, it has a differential pressure sensor for detecting that the pressure in the pipe has increased.

Further, the edge of the current plate in the flow direction of the transported object has an acute cross section.

The current plate can be attached at any angle around the axis of the pipe.

Further, it has a U-shaped support which is provided in a generally U-shape and bypasses the pipe and is attached to the pipe so as to be rotatable around the axis, and the light projecting portion and the light receiving portion are U-shaped. It is fixed to both ends of the support.

Furthermore, the distance between the transparent window and the light projecting portion and the distance between the transparent window and the light receiving portion can be made variable.
The U-shaped support is capable of expanding and contracting with respect to the pipe.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. 1 is a perspective view of essential parts of a first embodiment of a dust detection device of the present invention. Figure 2
FIG. 2 is a sectional view of the dust detection device of the dust detection device of FIG. 1.
In FIG. 1 and FIG. 2, reference numeral 1 denotes a dust collecting pipe for collecting dust which may cause dust explosion generated by crushing waste home electric appliances and the like in the crusher. In the dust collecting pipe 1, dust as a transported object is transferred by a transfer device (not shown) to
It is distributed as indicated by the solid arrow inside.

Reference numeral 2 denotes a light projecting portion of an optical sensor which emits laser light as detection light for measuring dust. On the other hand, 3 is a light receiving part of an optical sensor for receiving the laser light emitted from the light projecting part 2. The white arrow in FIG. 1 indicates the traveling direction of the laser light. The light receiving section 3 is provided so as to face the light projecting section 2 and constantly receives laser light.

Reference numeral 4 is for transmitting the laser light between the light projecting portion 2 and the light receiving portion 3 of the optical sensor in order to measure the amount of dust in the dust collecting pipe 1 by the laser light of the optical sensor. And a pair of transparent windows provided on the pipe 1. The transparent windows 4 and 4 are provided so as to face the pipe 1, and are made of, for example, tempered glass or the like.

The laser light emitted from the light projecting section 2 passes through the transparent window 4 on one side, enters the pipe 1, passes through the transparent window 4 on the other side, and reaches the light receiving section 3. Then, if dust as the transported object exists in the pipe 1, the amount of light reaching the light receiving unit 3 decreases. The pair of transparent windows 4 and 4 have the same curved surface as the inner surface of the pipe 1 so as to prevent dust from accumulating on the inner surface thereof, and are provided so as not to project from the inner surface of the pipe 1. That is, the surfaces of the transparent windows 4 and 4 are flush with the inner surface of the pipe 1.

Reference numeral 5 denotes a purge nozzle (purge device) that blows air or the like on the inner surface of the transparent window 4 to remove dust and the like adhering to the transparent window 4. Purging nozzle 5
Is controlled by a purge control unit (not shown) and blows air or the like periodically at preset time intervals. Reference numeral 6 denotes an electrostatic removal treatment provided on the inner surface of the transparent window 4 for the purpose of preventing dust from adhering to the transparent window 4 due to static electricity. The static electricity removing process 6 is an antistatic agent applied to the inner surface of the transparent window 4, for example. Alternatively, it is a conductive paint applied to the inner surface of the transparent window 4. In the case of a conductive paint, it is electrically grounded to the outside to release static electricity.

FIG. 3 is a block diagram showing the signal flow of the dust detection device of this embodiment. FIG. 3 shows an example in which there are two sets of the light projecting section and the light receiving section. First and second light projecting section 2
The laser beams emitted from a and 2b are sent out in parallel by a light projecting lens unit (not shown). When this parallel laser light is shielded by the transported object such as dust, the first and second
The amount of received light that reaches the light receiving portions 3a and 3b of is reduced according to the amount of dust and the like.

The first and second light receiving portions 3a and 3b convert the change in the light amount into a change in voltage and send it as a voltage signal to the first and second sensor controllers 11a and 11b. The sensor controllers 11a and 11b include the light receiving units 3a and
The voltage signal received from 3b is amplified and output to the control unit 13 and the recorder 14.

As can be understood from the above description, the first
The output from the second sensor controller 11a, 11b is a function of the amount of dust present in the pipe 1. In the present embodiment, based on the outputs from the first and second sensor controllers 11a and 11b, the increase / decrease in the amount of dust in the pipe 1 is constantly monitored and recorded in real time using a data logger. be able to. The data logger in this case is the first and second sensor controller 1
"Personal computer for recording data and CR for displaying data, not shown, connected to 1a and 11b
T monitor device ”and a“ data logger control unit for controlling them ”(not shown).

When the data logger control section receives a voltage signal corresponding to the amount of dust output from the sensor controllers 11a and 11b, the data logger control section displays the data on the CRT monitor device in time series, and the personal logger Data is recorded on a computer at regular intervals.
The recorded data can be printed out later as time series data.

Further, a plurality of threshold values are set in the first and second sensor controllers 11a and 11b.
That is, the first sensor controller 11a outputs the first sensor threshold output lightness 21a and the first sensor threshold output lightness 22a. On the other hand, the second sensor controller 11b outputs the second sensor threshold output lightness 2
1b and the second sensor threshold output severity 22b are output. First and second sensor controllers 11a, 11
b is output as a digital signal according to each threshold when the amount of received light reaches the set threshold. These threshold outputs are input to the control unit 13.

The first sensor threshold output lightness 21a and the second
The sensor threshold output lightness 21b of is output as indicating a slight dust concentration abnormality. The first sensor threshold output severity 22a and the second sensor threshold output severity 22b are output as indicating a severe dust concentration abnormality. The control unit 13 operates in accordance with the mild and severe abnormal signals. For example, the first one that indicates the occurrence of a severe dust concentration abnormality
When the sensor threshold output severity 22a of is received, it sends a signal to stop the equipment that generates dust, and automatically sprays water inside the equipment to suppress dust scattering, and controls the entire equipment to operate safely. To do.

Next, as a specific example using the dust detection device of the present embodiment, an example in which plastic crushed into small pieces is conveyed in the pipe 1 by compressed air will be described. When the plastic is being conveyed, unevenness in the conveyance may occur, and the plastic may lump and block the pipe 1. In that case, the air stagnates there and does not flow downstream. In such a case, the flow rate sensor 17 detects a decrease in flow rate. Further, when the pipe is blocked downstream, the pressure inside the pipe increases. In such a case, the differential pressure sensor 16 detects this. Both the flow rate sensor 17 and the differential pressure sensor 16 detect an abnormality in the flow of the transported object.

Further, the differential pressure sensor 16 and the flow rate sensor 1
When combined with 7 to control, when an object is clogged upstream of the pipe 1, it detects a decrease in flow rate and takes a signal into the control system to detect an increase in the amount of dust in the facility where dust is generated. It is possible to automatically stop the equipment safely.

The purging nozzle (purge device) 5 of the present embodiment blows air or the like on the inner surface of the transparent window 4 to remove dust or the like, but the purging device is not limited to air but blows water or the like. But it's okay.

The first and second light receiving portions 3a and 3b and the first and second sensor controllers 1 of this embodiment are also provided.
Although 1a and 11b use a voltage signal as an output signal, the output signal is not limited to a voltage signal and may be, for example, a current signal.

Embodiment 2. FIG. 4 is a perspective view of essential parts of a second embodiment of the dust detection device of the present invention. In FIG. 4, the dust detection device according to the present embodiment is provided with the first light projecting unit 2
a, a first light receiving section 3a, and a second light projecting section 2b and a second light receiving section 3b. The structure and operation principle of each of the light projecting section and the light receiving section are the same as those in the first embodiment. In the dust collecting pipe 1, downstream of a bent part of the pipe [hereinafter referred to as a bend part],
The air flow is not uniform, and in such a portion, the dust concentration is high and the dust concentration is low. Therefore, if an attempt is made to constantly monitor a place where the dust concentration is high with one set of the light projecting unit and the light receiving unit, an erroneous abnormal threshold output signal may be output due to the non-uniformity of the air flow.
Therefore, in the present embodiment, as shown in FIG. 4, a plurality of transparent windows 4 are provided in the pipe 1 and two sets of the light projecting portion and the light receiving portion are arranged side by side in the flow direction of the transported object.

In the first embodiment, the control unit 13 executes equipment stoppage or sprinkling operation by receiving the first sensor threshold output severity 22a and the second sensor threshold output severity 22b. , The first sensor threshold output severity 22a and the second sensor threshold output severity 2a
When either one of 2b (including both) is received, the facility is stopped or water is sprinkled. With this, it is possible to reduce the detection error of the dust abnormality which is erroneously caused by the non-uniformity of the air flow.

Embodiment 3. FIG. 5 is a perspective view of essential parts of a third embodiment of the dust detecting device of the present invention. Embodiment 2
In the above, since the air flow in the same direction is measured, there is a concern that the concentration may be erroneously measured. In the dust detection device of the present embodiment, a first light projecting section 2a and a first light receiving section 3a, and two sets of light projecting sections including a second light projecting section 2b and a second light receiving section 3b. The straight lines connecting the light receiving portions form different angles with respect to the central axis of the pipe 1.

The structure and operation principle of each of the light projecting section and the light receiving section are the same as in the first embodiment. In the dust collecting pipe 1, the flow of the air flow is not uniform in the downstream of the bend part and the like, and a dense dust concentration and a thin dust concentration change into vortices every moment. Therefore, as in the present embodiment, a plurality of sets of light projecting portions 2a and 2b, light receiving portions 3a and 3b, and
And the transparent windows 4 and 4 are installed while changing the angle with respect to the central axis of the pipe 1.

By changing the angle and attaching the light emitting unit and the light receiving unit, it is possible to change the detection site in the portion close to the outside in the pipe 1, so that it is possible to measure different points in the flow of the transported object. it can. Therefore, it is possible to avoid malfunction due to detection of a portion having a high dust concentration due to the non-uniformity of the air flow by the plurality of light projecting sections and the light receiving sections.

Fourth Embodiment FIG. 6 is a perspective view of essential parts of a fourth embodiment of the dust detection device of the present invention. In FIG. 6, the structure and operation principle of the light projecting section and the light receiving section are the same as those in the first embodiment. In the present embodiment, the pipe 1
A rectifying plate 15 is provided for changing the flow of the transported object inside from turbulent flow to rectification. In the dust collecting pipe 1, the flow of the air flow is not uniform, for example, in the downstream of the bend portion, and the dust concentration is high and the dust concentration is changing every second. That is, there is a possibility that an incorrect abnormal threshold output signal is output due to the non-uniformity of the air flow. Therefore, in the present embodiment, the flow distribution plate 15 is used to make the air flow distribution in the pipe 1 uniform. The current plate 15 is
First light projecting section 2a, first light receiving section 3a, and second light projecting section 2
It is effective to provide two sets of the light projecting section and the light receiving section composed of b and the second light receiving section 3b. The airflow flowing from the upstream is rectified by the straightening plate 15, and the airflow uniformly flows at the positions of the light projecting portion and the light receiving portion on the downstream side. The control operation is the same as in the second embodiment.

Embodiment 5. FIG. 7 is a perspective view of the essential parts of a fifth embodiment of the dust detection device of the present invention. Embodiment 4
On the contrary, the provision of the straightening plate 15 may cause clogging of the transported object. The present embodiment is intended to solve the case where the pipe 1 is clogged due to the provision of the flow straightening plate 15. Monitoring of clogging in the pipe 1 will be described with reference to FIG. In FIG. 7, when collecting dust from a facility that generates dust, for example, strip-shaped thin paper is sucked into the dust collecting pipe 1 and is caught by the rectifying plate 15 provided in the pipe 1 to cause clogging here. The flow rate in the pipe 1 decreases. In the present embodiment, the flow rate sensor 17 or the differential pressure sensor 16 provided downstream of the flow regulating plate 15 in the pipe 1 is used to detect a flow rate abnormality such as a decrease in flow rate or an increase in differential pressure, and an abnormality signal is sent to the control unit 13. Output. Based on this, the control unit 13 executes the equipment stoppage or the water sprinkling operation. With such a configuration, it is possible to detect in advance that foreign matter has accumulated in front of the current plate 15 and the amount of dust has increased, and the facility can be automatically stopped safely.

Sixth Embodiment FIG. 8 is a perspective view of a current plate according to a sixth embodiment of the dust detection device of the present invention. The present embodiment is also intended to solve the case where the pipe 1 is clogged due to the provision of the straightening plate 15. When collecting dust from equipment that generates dust, strip-shaped thin paper, etc.
It has already been described above that the air may be sucked into the pipe 1 and caught in the straightening plate 15 or the like provided in the pipe 1 to cause clogging.
In the present embodiment, the straightening plate 15 provided in the pipe 1
Edges 15a at both ends of the straightening plate 15 are sharply sharpened like a blade edge of a knife so that the thin paper sucked in is easily cut when foreign matter is caught on the sheet.

Embodiment 7. 9 is a perspective view of a current plate of Embodiment 7 of the dust detection device of the present invention. If the density of dust is constant in the air flow in the pipe throughout the year,
The current plate 15 remains fixed as in the fourth embodiment, and there is no problem. However, in reality, due to changes in humidity and temperature,
Airflow changes occur. Therefore, in the present embodiment, the mounting angle of the straightening vane 15 in the pipe 1 can be changed. Dust collection pipe 1 that collects dust from equipment that generates dust
The inside is downstream of the bend part, etc., and the flow of the air flow is not uniform, and the dust concentration is high and the dust concentration is constantly changing. In the present embodiment, in order to rectify the deviation of the air flow in the pipe 1, the rectifying plate 15 is attached in the pipe 1 at an optimum angle.

Flange portions 8 are provided at both ends of the pipe 1a in the portion where the flow regulating plate 15 of the present embodiment is provided. Bolt holes are formed in each of the flange portions 8 at an interval of 45 degrees. For this reason, the pipe 1a can be connected by changing the angle with respect to the cross section of the pipe in units of 45 degrees depending on the way of fastening the mounting bolt (not shown). The current plate 1 is arranged so that the position of the light emitting unit and the position of the light receiving unit installed downstream are stable in the dust airflow.
The pipe 1a to which 5 is attached is rotated by a predetermined angle, and both flanges 8 and 8 are attached to the corresponding continuous pipes (not shown). As a result, stable data can be obtained regarding dust detection.

In the present embodiment, the mounting bolt holes are shown every 45 degrees, but needless to say, the angle is not limited to 45 degrees if the angle is changed roughly or finely. .

Embodiment 8. FIG. 10 is a perspective view of a main part of an eighth embodiment of the dust detection device of the present invention. FIG. 11 is a sectional view of FIG. The dust detection device of the present embodiment,
A U-shaped support body 9 having a substantially U-shape and provided so as to bypass the pipe 1 and attached to the pipe 1 so as to be rotatable around the axis.
have. The light projecting section 2 and the light receiving section 3 are fixed to both ends of the U-shaped support 9.

The pipe 1 for collecting dust from the equipment may be shaken or vibrated by the vibration of the blower sucking or blowing air or the vibration of the air flow. As a measure against this, in the present embodiment, a U-shaped support 9 is provided, and the light projecting unit 2 and the light receiving unit 3 are fixed to both ends of the U-shaped support 9. The U-shaped support 9 is integrally fixed to the pipe 1. Therefore, the transparent window 4, the light projecting unit 2, and the light receiving unit 3 provided in the pipe 1 are provided.
Vibrate in the same vibration mode, and measurement errors are less likely to occur during measurement.

On the other hand, in the dust collecting pipe 1, there are a part where the air flow is uniform and a part where the air flow is not uniform, such as in the downstream of the bend part, so that the sensor ability of the light projecting part 2 and the light receiving part 3 is maximized. It is ideal that the light projecting unit 2 and the light receiving unit 3 can be installed at positions where the air flow in the pipe 1 is uniform with the angle freely changed in order to pull out. The U-shaped support body 9 of the present embodiment is attached to the pipe 1 so as to be rotatable around the axis line as shown by the white arrow in FIGS. Therefore, the straight line connecting the light projecting unit 2 and the light receiving unit 3 can be adjusted in angle with respect to the central axis of the pipe 1, and the light projecting unit 2 and the light receiving unit can be adjusted at an appropriate angle according to the flow of the transported object. 3 can be installed to maximize the sensor capability.

Ninth Embodiment FIG. 12 is a perspective view of the essential parts of Embodiment 9 of the dust detection device of the present invention. FIG. 13 is a sectional view of the dust detection device of FIG. The U-shaped support 9 of the present embodiment is divided at the central portion. Each of the divided U-shaped supports 9a and 9b is fixed to the pipe 1 through the sensor position adjusting slot 10. The sensor position adjusting slot 10 is an slot extending in the direction of a straight line connecting the light projecting section 2 and the light receiving section 3.

With this structure, the U-shaped supports 9a and 9b can be expanded and contracted with respect to the pipe 1 in the direction of the straight line connecting the light projecting section 2 and the light receiving section 3. Thereby, in the present embodiment, as shown by the white arrow in FIG. 13, the distance between the transparent window 4 and the light projecting portion 2 and the distance between the transparent window 4 and the light receiving portion 3 are set. It has an adjustable structure.

The laser light emitted from the light projecting section 2 reaches the light receiving section 3 through the transparent window 4, but the amount of light reaching the light receiving section 3 may decrease due to refraction depending on the incident angle to the transparent window 4. In this embodiment, in order to maximize the amount of light between the light projecting unit 2 and the light receiving unit 3, the position adjustment with the transparent window 4 is made possible, and the influence of the light refraction phenomenon on the transparent window 4 is made possible. Can be minimized.

[0052]

In the dust detecting apparatus according to the present invention, the pipe for conveying the conveyed body such as powder or granules, the conveying apparatus for conveying the conveyed body in one direction in the pipe, and the piping are opposed to each other. A pair of transparent windows provided on the surface, a light projecting portion provided on the outside of the transparent window on one side to project detection light into the pipe through the transparent window, and provided on the outside of the transparent window on the other side. Since it has a light-receiving unit that receives the detection light that has passed through the pipe and converts the amount of light into an electrical signal, and a sensor controller that inputs the electrical signal output from the light-receiving unit and outputs an abnormal signal when a predetermined threshold value is exceeded. Thus, it is possible to quantitatively detect in real time the pulsation of the amount of dust in the pipe, which could not be measured online, and obtain the data necessary to prevent the dust explosion. Further, when the amount of dust exceeds a predetermined value, it is possible to stop the process of generating dust or sprinkle water to suppress the generation of dust to prevent dust explosion. Further, it is possible to obtain a dust detection device that can reliably monitor even low-concentration dust without relying on the experience of the operator and can prevent the danger of dust explosion.

Further, since the sensor controller outputs an analog electric signal based on the amount of received light, which increases or decreases depending on the transported object, to the data logger device, stable data necessary for preventing dust explosion is recorded in time series. be able to.

Further, since a control unit for inputting an abnormal signal from the sensor controller to stop the carrying device is provided, when an abnormality such as clogging occurs in the pipe through which the dust flows, the facility for producing the dust is stopped. It is possible to prevent dust explosion.

Further, since the inner surface of the transparent window is subjected to static electricity removal processing, it is possible to prevent dust from adhering to the transparent window due to static electricity.

Further, since the apparatus has a purging device for blowing off the adhered matter adhering to the inner surface of the transparent window, it is possible to remove dust and the like adhering to the transparent window.

Further, a plurality of pairs of the transparent window, the light projecting section, the light receiving section, and the sensor controller are provided, and the control section calculates the logical sum of a plurality of abnormal signals output from the plurality of sensor controllers. Since the transport device is stopped, it is possible to reduce the detection error of the dust abnormality that is erroneously caused by the non-uniformity of the air flow.

Further, since the straight lines connecting a plurality of sets of the light-transmitting part and the light-receiving part form mutually different angles with respect to the central axis of the pipe, a portion having a high dust concentration due to the non-uniformity of the air flow is defined as the plurality of light-emitting parts. It is possible to avoid malfunction due to detection by the light receiving unit.

Further, since the straightening plate provided in the pipe for rectifying the flow of the transported object is provided, the air flow distribution in the pipe can be made uniform, and the malfunction due to the non-uniformity of the air flow can be avoided.

Further, since the apparatus has a flow rate sensor for detecting a decrease in the flow rate in the pipe, a facility for generating dust by using the data obtained by the flow rate sensor when an abnormality such as clogging occurs in the pipe. It is possible to prevent dust explosion by stopping.

Since a differential pressure sensor for detecting an increase in pressure in the pipe is provided, when an abnormality such as clogging occurs in the pipe, dust is generated using the data obtained from the differential pressure sensor. It is possible to prevent dust explosion by stopping the equipment that operates.

Further, since the edge of the flow straightening plate in the flow direction of the transported object has an acute cross-section, by sharpening the tip of the flow straightening plate, foreign matter flowing from upstream in the dust collecting pipe is prevented. Even if it gets caught, it will not break and will not get stuck in the current plate.

Further, since the current plate can be attached at an arbitrary angle around the axis of the pipe, the relationship between the positions of the light emitting section and the light receiving section installed downstream is such that the dust airflow is stable. As described above, a rectifying plate can be attached, it is possible to cope with a change in the turbulent flow generation situation accompanying a change in the environment, and stable data can be obtained regarding the detection of dust.

Further, there is provided a U-shaped support member which is provided in a substantially U-shape and bypasses the pipe and is attached to the pipe so as to be rotatable around the axis, and the light projecting portion and the light receiving portion are U-shaped. Since it is fixed to both ends of the support, the piping and the light emitting part and the light receiving part vibrate together to eliminate the measurement error due to the vibration between the light emitting part and the light receiving part. By being attached so as to be rotatable around, the mounting angle of the sensor with respect to the pipe can be determined at an appropriate position according to the flow of the measured portion in the pipe.

Furthermore, the distance between the transparent window and the light projecting portion and the distance between the transparent window and the light receiving portion can be made variable.
Since the U-shaped support is capable of expanding and contracting with respect to the pipe, it can be adjusted to a position where the optical axis of the sensor passing through the transparent window has the least refraction.

[Brief description of drawings]

FIG. 1 is a perspective view of essential parts of a first embodiment of a dust detection device of the present invention.

2 is a cross-sectional view of the dust detection device of FIG.

FIG. 3 is a block diagram showing a signal flow of the dust detection device.

FIG. 4 is a perspective view of essential parts of a second embodiment of the dust detection device of the present invention.

FIG. 5 is a perspective view of essential parts of a third embodiment of the dust detection device of the present invention.

FIG. 6 is a perspective view of essential parts of a fourth embodiment of the dust detection device of the present invention.

FIG. 7 is a perspective view of essential parts of a fifth embodiment of the dust detection device of the present invention.

FIG. 8 is a perspective view of a current plate of Embodiment 6 of the dust detection device of the present invention.

FIG. 9 is a perspective view of a current plate of Embodiment 7 of the dust detection device of the present invention.

FIG. 10 is a perspective view of essential parts of an eighth embodiment of the dust detection device of the present invention.

11 is a cross-sectional view of FIG.

FIG. 12 is a perspective view of essential parts of a ninth embodiment of the dust detection device of the present invention.

13 is a cross-sectional view of the dust detection device of FIG.

[Explanation of symbols]

1 piping (dust collection piping), 2, 2a, 2b light projecting section, 3,
3a, 3b Light receiving part, 4 Transparent window, 5 Purge nozzle (purge device), 6 Electrostatic removal treatment, 8 Flange part,
9,9a, 9b U-shaped support, 10 elongated holes for sensor position adjustment, 11a, 11b sensor controller, 1
3 control part, 14 recorder, 15 straightening plate, 15a edge part, 16 differential pressure sensor, 17 flow sensor.

Continued front page    F term (reference) 2G057 AA01 AB04 AB06 AC06 AD15                       BA05 BB01 DA11 DA15 DB08                       DC07 GA01 GA02 JA03 JA20                 2G059 AA01 BB01 CC19 EE01 FF04                       GG01 GG03 KK03 LL10 MM01                       MM05 MM09 NN07                 3F047 AA03 AA16 AB02 AB03 AB06                       BA06

Claims (14)

[Claims] 1. A pipe that conveys an object to be conveyed such as powder or granules, a conveying device that conveys the object to be conveyed in one direction in the pipe, and a pair provided on opposite surfaces of the pipe. Transparent window, a light projecting portion that is provided outside the transparent window on one side and projects detection light into the pipe through the transparent window, and the pipe provided outside the transparent window on the other side. A light receiving unit that receives the detection light that has passed through and converts the amount of light into an electric signal, and a sensor controller that inputs the electric signal output from the light receiving unit and outputs an abnormal signal when a predetermined threshold is exceeded. A dust detection device characterized by having. 2. The dust detection device according to claim 1, wherein the sensor controller outputs an analog electric signal based on an amount of received light which is increased or decreased by the transported object to a data logger device. 3. The dust detection device according to claim 1, further comprising a control unit that receives the abnormality signal of the sensor controller and stops the transport device. 4. The dust detection device according to claim 1, wherein the inner surface of the transparent window is subjected to static electricity removal processing. 5. A purging device for blowing away adhered substances adhering to the inner surface of the transparent window.
5. The dust detection device according to any one of 4 to 4. 6. A plurality of sets of the pair of transparent windows, the light projecting unit, the light receiving unit, and the sensor controller are provided, and the control unit outputs a plurality of the abnormal signals output from the plurality of sensor controllers. Depending on the result of OR operation,
The dust detection device according to claim 3, wherein the transport device is stopped. 7. The dust detection device according to claim 6, wherein straight lines connecting the plurality of sets of the light projecting portion and the light receiving portion make mutually different angles with respect to a central axis of the pipe. 8. The dust detection device according to claim 1, further comprising a rectifying plate provided in the pipe for rectifying a flow of the transported object. 9. The dust detection device according to claim 1, further comprising a flow rate sensor that detects that the flow rate in the pipe has decreased. 10. A differential pressure sensor for detecting that the pressure in the pipe has increased.
10. The dust detection device according to any one of 9 to 9. 11. The dust detecting apparatus according to claim 8, wherein an edge portion of the rectifying plate in a flow direction of the transported object has an acute cross section. 12. The dust detection device according to claim 8, wherein the current plate can be attached at an arbitrary angle around the axis of the pipe. 13. A U-shaped support member having a substantially U-shape, which is provided so as to bypass the pipe and is rotatably attached to the pipe around an axis, and the light-projecting unit and the light-receiving unit are provided. The dust detection device according to any one of claims 1 to 12, wherein the dust detection device is fixed to both ends of the U-shaped support. 14. The U-shaped support is connected to the pipe so that a distance between the transparent window and the light projecting portion and a distance between the transparent window and the light receiving portion can be varied. The dust detection device according to claim 13, wherein the dust detection device is expandable and contractable.