JP2861742B2 - Flow measurement method for high concentration powder conveyed in pipe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring a flow rate of a high-concentration powder conveyed by a conveying medium in a pipe.

[0002]

2. Description of the Related Art Conventionally, as a method for measuring the flow rate of powder, a method using a light transmission type powder densitometer is known. FIG.
To show an example. As shown in FIG. 9, set up two opposite viewing window 2 to the powder transfer pipe 1, incident parallel light beam 4 emitted from one of the observation window 2 from light source 3, the powder transfer pipe 1
Incident inside. The incident light attenuated by the powder 7, taken out the rest of the transmitted light from the other observation window 2, the light amount detection end 5
To detect the amount of transmitted light. 6 is for sealing
O-ring.

[0003] That is, the light amount of the light source body (incident light intensity) is set to a constant value, for measuring the powder density by detecting the change in transmitted light amount due to the powder density. Further, assuming that the moving speed of the powder is equal to the flow velocity of the carrier medium (gas) , the powder flow rate value is calculated from the product of the powder concentration value and the carrier medium flow rate value.

[0004]

However, in the measurement using the powder densitometer based on the light transmission method described above, the maximum measurable powder concentration is restricted. Transfer medium (gas) from powder transfer tube
Or it sucked constant speed, or by or provided a branch pipe, it is necessary to measure by sampling a portion of the particles. Even with such an improved system, the maximum powder concentration of a practically used dust concentration meter is about 200 g / m ³ ,
Light is decays for more concentration particles
Because, by applying the light transmission type powder concentration meter measuring the high density powder flow rate is difficult.

The present applicant has attempted to solve the above-mentioned problems, and has disclosed in Japanese Patent Application Nos. 4-234721 and 4-233.
794. Generally, the powder is continuously conveyed to measure the powder concentration in the high-concentration region, but the conveyance of the powder is often stopped.

[0006] In this case, the in powder flow rate measuring device for high concentration of optical employed is a potent light source is, if the powder does not flow does not have the amount of transmitted light and little attenuation,
Light quantity detecting end is destroyed by the amount of transmitted light, the detection ability is reduced. Furthermore, in order to prevent destruction of the light amount detecting end, as if the powder is not flowing not receiving a strong projection light of the light source to the light amount <br/> detecting end, the light emission of the light source It has been found that there is a problem in that when the flow is stopped or the incident light is cut off , continuous measurement cannot be performed when the flow of the powder is restarted.

The present invention is based on the invention disclosed in the above-mentioned Japanese Patent Application No. 4-234721, and aims to solve the problem. It is an object of the present invention to provide a method that enables continuous automatic measurement of powder concentration in a high concentration region and that can measure a powder flow rate online.

[0008]

[MEANS FOR SOLVING THE PROBLEMS] To achieve the above object
The flow rate of the high-concentration powder conveyed through the tube according to the first invention of the
The measuring method is to install two opposing observation windows on the pipe wall of the pipe on which the powder is transported by the transport medium, and to obtain the predetermined amount of received light.
As described above, light is transmitted through the observation window, the transmitted light is received, and the powder flow rate is calculated from the powder average concentration measured using the transmittance of the transmitted light amount and the flow velocity value of the transport medium.
A method for measuring the flow rate of a high concentration powder, when conveying of the powder is stopped compares the received light level at the time of powder conveying
The light quantity changing means for providing the received light levels of weakened Te using,
The transmittance is measured under conditions that provide a weakened light receiving amount level, and when the powder is started to be conveyed, the transmission is started with the start of the powder conveyance.
Detecting the attenuation Urn amount of transmitted light based on the detection signal, where
So that a constant amount of received light, the transmittance under conditions giving receiving light level at the time to <br/> powder transfer release the light quantity changing means
It was measured, by measuring the powder average density from the measured transmittance,
It is characterized in that the powder average concentration of this and the velocity values of the transfer medium and calculates the powder flow rate.

[0009] The high concentration conveyed in the tube according to the second invention
In the method of measuring the flow rate of powder, two measuring tubes for light transmission that protrude opposite each other at a fixed tip interval are installed in a tube in which the powder is conveyed by a conveying medium, and the light is measured so that a predetermined amount of light is received. Transparent
By transmitting light through the over-measurement tube, high that the transmitted and received light, calculates the powder flow rate from the powder average density was measured using a transmittance of the transmission light amount and the flow rate value of the transport medium Dark
A flow rate measuring method in degrees powder, prior to when the transport of Kikotai is stopped, the amount of light changes giving compared to weak <br/> meth received light levels to receive light level when the powder conveying by using the means, weakening
Measuring the transmittance under conditions that give the received light level
When the transfer of the powder is started, the attenuation of the transmitted light amount due to the start of the transfer of the powder is detected, and a predetermined value is determined based on the detection signal.
Such that the amount of received light, wherein to release the light quantity changing means and <br/> measure the transmittance under conditions giving receiving light level during powder transfer, the powder average density from the measured transmittance measured, it is characterized in that to calculate the powder flow rate from the powder the average concentration of this and the flow rate value of the carrier medium.

[0010] The high concentration conveyed in the tube according to the third invention
The method for measuring the flow rate of powder is described in the first invention or the second invention.
The light amount changing means is performed by a light source additional current operation of the light source body .

A high concentration transported in a pipe according to a fourth aspect of the present invention.
The method for measuring the flow rate of powder is described in the first invention or the second invention.
And the light amount changing means is operated by operating the light attenuation shutter.
It is characterized by performing .

A high concentration transported in a pipe according to the fifth invention.
The method for measuring the flow rate of powder is described in the first invention or the second invention.
And the light amount changing means is operated by the collimating lens device.
It is characterized by performing by work.

[0013]

According to the present invention , the light intensity of a continuous light
Uses a strong light source that can easily realize a large parallel light beam
Relative to the pipe wall that transports the powder by the transport medium
Through the two observation windows
For measuring the body concentration, or via a light transmission measuring tube protrudingly arranged at a constant tip interval L in a tube in which the powder is conveyed , Let the light pass through the powder
It measures body concentration. In particular, a constant tip interval L
When the measuring tube for light transmission is made to protrude in opposition, the optical path length of the measuring part (equal to the distance L between the tips of the measuring tube for light transmission) is made smaller than the actual diameter of the powder transfer tube, and the attenuation of the light transmission amount is reduced. Can be suppressed as much as possible, making it possible to measure high-concentration powder.
You.

[0014] In actual powder flow rate measurement, different particle <br/> child size of the powder, the type of powder in different so-called mixed grain state, in the present invention, as shown in FIG. 3 transmission A powder average density value is determined based on an output signal from the light amount detection end using a relationship between the ratio and a parameter including a powder average density and a measurement condition .

[0015] Figure 3 is a diagram showing FIG. 1 will be described later, the transmittance in the case of using the powder flow rate measuring apparatus of FIG. 2 and (I / Io), the relationship between the parameters consisting of the powder average density and measurement conditions , it is obtained by tests using the silica sand two iron ore as a powder.

As is apparent from FIG. 3, even when the powder particle diameters are different, by taking into account the true specific gravity (ρ) of the powder ,
The transmittance (I / Io) could be measured in agreement with one calibration line. From this, in the present invention, powder particle size,
It was found that measurement was possible even if the powder types were mixed.

That is, the optical path length L of the measuring section as the measuring device is specified, and the true specific gravity (ρ) and the harmonic mean diameter (dp32) of the powder of the object to be measured are obvious as the characteristic values of the handling process. By measuring the ratio (I / Io)
Thus , the average powder concentration value (kg / m ³ ) can be uniquely obtained from the relationship shown in FIG.

Meanwhile, out flow rate detection to measure the flow rate of the carrier medium
An average flow velocity value of the transport medium is calculated based on the output signal at the end . That is, the average flow velocity of the existing detection signal of the pressure by Pitot tube, or by using a general relationship between the flat <br/> average flow rate of the temperature detection signal to the transport medium by a hot-wire flow rate detecting end, the transport medium Value can be calculated.

Furthermore by calculated multiplication and a transport medium average flow velocity value and the powder average density value, it can be calculated powder flow rate value. Furthermore, in the present invention, with the front end distance L of the two opposite light transmitting measuring tube to be constant, more possible to traverse the powder transport tube <br/> radially radially of the powder transfer pipe Of the powder concentration can be measured.

[0020] FIG. 4 is an explanatory diagram for estimating a powder distribution in the diameter direction of the powder transfer tube. The tip distance L for light transmission measurement pipe in the range of the inner diameter of keeping with the tube at regular intervals, toward one of the tube wall from at least the tube center, the radius of the step to the tube the-edge interval length as a unit By continuously moving along, the powder concentration distribution in the diameter direction in the tube is measured from the attenuation distribution of the transmitted light amount corresponding to the moving position in the tube,
Obtaining a powder average density simultaneously have use a weighted average formula of the following equation (1).

[0021]

(Equation 1)

The above average powder concentration value and average transport medium flow velocity value
Can be calculated by multiplying by.

[0023] In the present invention uses a light source having a large output for measuring high density powder, when the powder density, and the like when the conveyance of the powder is stopped small becomes large transmission light amount, transmitted light excessive light intensity received light quantity detection end, the light amount detection end there is a risk of burning.

In the present invention, when the conveyance of the powder is stopped,
Amount of light, to give in order to reduce the amount of light received increasing, the receiving light amount level weakened compared to receive <br/> light levels during powder transfer
Under the condition of giving the weak received light level by the changing means,
In other words, the amount of transmitted light that irradiates the light amount detection end is
Rates were measured, and, when the conveying of the powder is started,
Detects the attenuation of the transmitted light amount due to the start of the powder conveyance, and based on the detection signal, sets the light amount to a predetermined amount.
It gives the received light level at the time of the powder transfer to release the changing means
The transmittance was measured by measuring the powder average concentration conditions, the
The powder flow rate is calculated from the powder average concentration measured as described above and the average flow velocity value of the transport medium, so that even if the powder transport is interrupted during continuous measurement, excessive light it is possible to prevent the burning of the light amount detecting end by transmitted light intensity.

[0025] The predetermined amount of received light in this invention, the amount of light detected edge during powder transfer <br/> is a light intensity of received light. At the time of the powder transfer
Maintains the transmitted light intensity so as to reach the above-mentioned received light level.
And, by the powder is present in the measurement interval, receiving the attenuated light, with the transmission rate (attenuation ratio) powder Rights
Measure the average concentration. As this, for the powder concentration measurement during powder transfer, by projection with a constant intensity of the light quantity detection end receiving
The amount of received light is referred to as a predetermined amount of received light.

[0026] Therefore, the most weakened was received amount of light used for measurement when the powder transfer is stopped, the received light amount level at the powder transfer
Under the conditions that give, 1/10 to 1/10000 of the received light amount when no powder is present in the measurement section ,
It is of the permissible amount of received light and a constant value selected to a value below that calculated from the ratio between the maximum output light intensity of the light source of the light receiving element used in the light amount detection end.

In order to satisfy the above, the present invention has taken three measures. For the first strategy that the light receiving amount of the above reporting, by changing the additional current to the light source is incident light, and the intensity level for the determination of when the powder transfer, the powder transfer is stopped The light intensity of the light source is switched and changed to a weak level for measurement at the time.

The light intensity of the light source, for example, the laser output value ,
The means for switching from the low level to the high level or vice versa is achieved by switching the output setting signal of the output level setting circuit of the laser power supply to the high level signal or the low level signal in response to the light intensity level switching signal from the light amount detection terminal. You. Usually, switching of the output level of the laser output value is possible within the 100 to 10% range of the rated total output.

The second strategy is to set up a shutter for optical attenuation in front of the converging lens of the light transmittance in the detection unit attenuates the light, which has a structure to prevent damage to the light quantity detecting end is there. Movement in the optical axis of the shutter is performed by the shutter driving unit, an instruction to the driving device to perform with reference to transmitted light quantity value detected by the light amount detection end.

[0030] For example, to set the amount of received light light amount detection end is not damaged as the most weakened amount of received light, the powder transfer measurement
A predetermined receiving light amount of the received light amount of the strong level of use, the shutter for optical attenuation for attenuating the weak meta received light amount was charged to the measuring optical path,
In this state, the measurement is continued to monitor the start of powder transport.

When the powder concentration increases in this state, the amount of transmitted light further decreases or the amount of transmitted light is no longer detected. Therefore, the shutter for light attenuation is moved away from the optical path for measurement, and the total amount of light from the light source is used. to start the measurement of powder flow rate.

[0032] In optical attenuating shutter used in the present invention,
The amount of transmitted light is attenuated to about 1/100 to 1 / 10,000. Furthermore, if the light attenuating shutter is inserted into the optical axis of the measuring system and the transmitted light amount is attenuated, and if the transmitted light amount is constantly measured in the measurement standby state, the change over time of the entire system of the powder flow measuring device is monitored. I can do it.

The third measure is light attenuation which attenuates the amount of transmitted light.
Instead of use shutter coli Mate queuing lens device for attenuating the incident light intensity, a structure that is placed between the <br/> the light source and the light-transmission measurement pipe.

The portion this coli Mate viewing lens device, which is the strength level coli Mate viewing lens system for converting all parallel light beam for measuring an output light beam of the light source, the output light flux cross-section of the light source to the optical axis and center only are those arranged in parallel in parallel to a plurality of different attenuating coli Mate queuing lens device and the optical axis of the light attenuation factor to a parallel light beam of the parallel light beam of the same diameter for the measurement, waiting for the powder flow measurement In this state, the collimating lens device with the highest light decay rate is inserted into the output optical axis of the light source body to attenuate the incident light amount, and as a result
The receiving light amount of the amount detected edge to a weak level.

The light attenuating collimating lens device used in the present invention attenuates the incident light amount to about 1/10 to 1/100. Replacement replacement of coli Mate queuing lens apparatus performs the coli Mate queuing lens unit switching device, an instruction to the switching device is performed by referring to the transmitted light quantity value detected by the light amount detection end.

[0036] For example, previously set amount of transmitted light that the light amount detection end is not damaged, if the actual amount of transmitted light is greater than this set value, moves the optical attenuating coli Mate queuing lens unit in the optical axis, transmission The light quantity is attenuated, and the apparatus enters a measurement standby state.

If the powder concentration increases in this state, the amount of transmitted light will be further reduced or the amount of transmitted light will not be detected. Therefore, another collimating lens device which uses the total amount of light of the light source as the amount of incident light will be used. The powder flow rate measurement is started by replacing the collimating lens device and using the total light amount of the light source body .

[0038]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are diagrams showing an embodiment of the present invention. FIG. 1 shows a light transmittance detecting section, a flow rate detecting end, and an arithmetic unit.
FIG. 2 is a diagram showing a state in which the powder flow measuring device is installed in a powder transfer tube , and FIG. 2 is a diagram showing a main part of a light transmittance detector shown in FIG. In these figures, 10 is a light transmittance detector, 11a and 11b are light transmission measurement tubes, 12 is a tip interval adjusting device, 13 is a flow velocity detecting end , 14 is a computing device,
O-ring for the observation window ,, 6 seal 7 powder, 19
It is a cover .

The powder flow Ryohaka constant apparatus used in the present invention, the powder
7 is provided in a piping system 9 transported by the transport medium ,
Adjacent upper and lower pipe concentric like cross section perpendicular powder transfer pipe 1 of the opening 8a which is located on the line E which is orthogonal to the axial center C are opposed, are inserted into 8b, at a distal spacing L Light transmission measurement tubes 11a, 11 protrudingly arranged to face each other.
b, a tip distance adjusting device 12 attached to the light transmission measurement tubes 11a and 11b, a parallel light beam incident light source 3 disposed at the rear end of one of the light transmission measurement tubes 11a, and a light source 3 a light source power supply 21, the light transmittance detector 10 determined by the light intensity detection end 5 which is arranged at the rear end portion of the other light-transmission measurement pipe 11b
A flow velocity detecting end 13 for measuring the flow velocity of the transport medium ;
It was from the output signal of the detection end 5 and the flow rate detecting end 13 and a powder mean density value and conveyance medium average flow velocity value of each calculated, combining the operation unit 14 by multiplying them calculates the powder flow rate value
As hereinbefore, further, when the conveyance of the powder 7 is stopped, the light quantity changing means for providing a received light quantity level weakened compared to receive light levels at the time of powder <br/> member transport, weakened level received Under quantity
In continuing the measurement of the transmittance, when the conveyance start of the powder 7, as to detect the attenuation of transmission light due to the conveyance start of the powder 7, based on the detection signal, the Jo Tokoro amount of received light the transmittance was measured constructively received light levels during powder transfer, these transmission
The powder concentration was determined from the rate of the detection signal, immediately the function of calculating the powder flow rate from the flow rate value of the powder density and the transport medium
Ru Bei to Monodea. Weakening the received light level, as the light amount changing means or intensified, the light transmittance detection unit 10,
6 to be described later, FIG. 7, as shown in FIG. 8, the light source power supply 21 switches the output light amount by changing the light source additional current, or input
Collimating lens device with switchable light intensity
Or a shutter that attenuates the amount of transmitted light .

The arithmetic unit 14 receives the transmission signal obtained by converting the measured value into a signal from each of the light amount detecting end 5 and the flow velocity detecting end 13 in the light transmittance detecting unit 10, and calculates by the calculating unit 15. The flow rate of the powder 7 is displayed. 17 is a storage unit, 1
8 is a command unit.

FIG. 6 is a control circuit of the light source current 21 to control the light intensity of the light source 3 used in the present invention, an embodiment of a light source power supply 21 in which a light amount level setting circuit for providing a switching command light level setpoint It is a figure which shows an example, and is a figure which specifically shows the example using the continuous emission laser light source.

The laser output (light intensity) of the laser oscillator 22 as the light source body 3 is monitored by monitoring the laser output, and the discharge current control circuit 23 adjusts the discharge current amount of the discharge current output circuit 24. , And the laser output value is stabilized.

Therefore, the means for switching the laser output value of the laser oscillator 22 from the low level to the high level or vice versa is a command signal from the means for receiving the detection signal of the light quantity detection terminal 5 and comparing the signal level with the threshold value. Output based on 25
The output setting signal to the discharge current control circuit 23 of the level setting circuit 26, Ru done by switching to the weak level signal from the strong level signal.

Normally, the output level of the laser output value can be switched within a range of 100 to 10% of the rated total output. The means for comparing can be either a software means using an arithmetic unit 14 for receiving a detection signal of the light amount detection end 5 or a means for comparing low frequency components of the detection signal with an analog circuit.

FIGS. 7A and 7B show an embodiment of the collimating lens device used in the present invention.
(A) is a diagram using a concave lens as the light diffusion lens, and (b) is a diagram using a convex lens as the light diffusion lens.

[0046] When measuring the powder density, light source 3 der
A narrow collimated beam of light output from the laser oscillator 22 as an output light beam 27 is diffused by the concave lens 28a or convex lens 28b for light diffusion that, the light flux diameter is provided at a location that is enlarged to the diameter of the measurement portion parallel light beam 29 The light is transmitted through the collimating convex lens 30 to form a measuring unit parallel light beam 29 having a predetermined diameter. 33 is a diffused light beam.

[0047] To weaken the light intensity of the measuring section parallel light beam 29 (energy / unit projection area), concave lens 2 for light diffusion
8a and using a lens with different focal length in a convex lens 28b, the light diffusion degree is greater than the light diffusing degree of the case for measuring the time of powder transfer, for example <br/> measured during powder transfer the spread diameter After that, a part of the light flux centered on the optical axis (the same area as the area of the parallel light beam 29 of the measuring unit) is divided into the parallel light beam 29 of the measuring unit by the convex lens 30 for the collimating lens. I do. Concave lens 28a of the light diffusion, Totsure
In the example in which the degree of light diffusion in the lens 28b is three times that in the case of measurement during powder conveyance , the light intensity of the measuring unit parallel light flux 29 is set to 1
/ 9.

FIG. 7 shows two examples of the optical method.
Other optical methods, eg for collimating lenses
The light intensity of the measuring unit parallel light beam 29 can also be reduced by disposing the convex lens 30 at a position farther from the light diffusing concave lens 28a and the convex lens 28b.

[0049] In the present invention, by switching the arrangement of the light source output optical axis of the plurality of stiffness Mate Ing lens system designed by an optical method such as described above, by changing the light intensity of the measuring section parallel light beam 29 Can be done .

FIGS. 8A and 8B are views showing one embodiment of the light attenuation shutter used in the present invention, wherein FIG. 8A is a side sectional view, and FIG. 8B is a view after passing through the light attenuation shutter. FIG. 3 is a diagram illustrating a light attenuation state. Here laser onset as the light source 3
A shaker is used, and a perforated plate shutter 31 is used as a shutter for light attenuation .

The perforated plate shutter 31 has an outer diameter of φ20.
This is a perforated plate in which a large number of small holes made by a processing method such as etching are arranged at equal intervals on a stainless steel thin plate having a thickness of 0.1 mm and a thickness of 0.1 mm, and thermal deformation due to light is minimized.

The transmitted light incident on the first perforated plate 31a
34 , the light applied to the thin plate other than the hole is blocked, but the transmitted light passing through the hole goes straight and the next perforated plate 31b
To the next perforated plate 31c as a result,
The total amount of light passing through the perforated plate shutter 31 is attenuated. As described above, the perforated plates 3 1 a, 3 1 b, 3
Irradiated with 1 c, attenuated state after passing through the perforated plate shutter 31 is distribution of light as shown in Figure 8 (b).

The attenuation rate is basically determined by the perforated plate 31
a, 31b, and 31c , the total area (opening ratio) of the holes with respect to the area of one sheet, and the perforated plates 31a, 31b, and 31c.
Is the determined by the weight relative arrangement, a plurality of perforated plates 3
By finely adjusting the relative positions of 1a, 31b and 31c , the transmittance (attenuation) can be finely adjusted.

[0054] In the present invention, the light receiving element of a silicon photodiode type using the light quantity detection end 5, measurable maximum amount of this type is 50 mW, is the measurement accuracy more large amount of light of the light irradiated descend.

[0055] In order to measure the concentration of the high concentration of powder 7,
In the example using a laser light source output 5W to light source 3, a porous
The target value of the light attenuation ratio by the plate shutter 31 is 1/1.
00 = 0.05 / 5, but the perforated plates 31a, 31b,
Due to the reliability of the performance of 31c and the change with time, the attenuation ratio is set to 1
/ 100 to 1/10000.

In order to realize this attenuation ratio, the perforated plate 3
Various prototypes were manufactured by changing the hole diameter, the number of holes, and the number of holes of 1a, 31b, and 31c , and the attenuation ratio was actually examined. The light having a structure of four perforated plates having holes of 0.15 mmφ arranged at a pitch of 0.25 mm was obtained. The damping perforated plate shutter 31 was determined. If a hole having a smaller hole diameter can be formed, the attenuation ratio per one perforated plate can be increased, so that the number of perforated plates can be reduced.

[0057] porous plate shutter 31 of the four structures,
As shown in an example in FIG. 2, it is installed in front of the light converging lens 20 in the light transmittance detector 10. Movement in the optical axis of the perforated plate shutter <br/> over 31 performs the shutter driving unit 32, an instruction to the shutter driving device 32, the amount of transmitted light detected by the light amount detection <br/> Extension end 5 Perform by referring to the value.

Next, a description will be given of a case of performing the invention using apparatus above mentioned. The powder transfer pipe powder 7 in 1 provided in the piping system 9 for conveying the powder 7 is passed by the conveying medium. Here, since the powder transfer tube 1 is piping concentric like cross-sectional area of the pipe system 9, for uniformity of flow in the measuring portion is maintained, the concentration of the powder 7 to pass through its piping system 9
The same as the concentration of the powder 7 inside.

[0059] For the light transmission measurements pipe 11a, 11b is KonataiUtsuri
Flue first axis C located on the line E which is perpendicular to the opposed be allowed openings 8a, since disposed is inserted into 8b, for light transmission measurements tube 11a, 11b are the same size, The axes match. Thereby, the light flux incident from the light source 3 of the light beam for incidence connected to the ends of the light transmission over a measurement pipe 11a traverse becomes a parallel beam 4 the powder transfer tube 1 at right angles, opposite
The light passes through the light transmission measurement tube 11 b and is detected at the light amount detection end 5.

[0060] or, located inside the powder transfer tube 1, opposite the light transmittance measurement tube 11a, keeping the tip distance L 11b at predetermined intervals in the range of the inner diameter of the powder transfer tube 1, whereas Powder transfer tube at a specified speed from one tube wall to the other
1 , the distribution of the amount of transmitted light (transmittance) in the diameter direction in the powder transfer tube 1 is detected.

Here, when the conveyance of the powder 7 is stopped, the light intensity of the light source body 3 is changed so that the transmitted light intensity detected by the light amount detection end 5 becomes a light receiving amount of a weak level. The measurement is continued while preventing the light quantity detection end 5 from being destroyed.

[0062] When the powder 7 is started again transported detects the attenuation of the transmitted light intensity by the detection signal, strengthen amount of received light on the light receiving amount of the predetermined intensity level, a distal spacing L
In pairs toward light-transmitting measuring tube 11a, one to transmit light to the other from 11b, a transmittance of the vertical axis shown in FIG. 3 from the transmittance of light by measuring the amount of transmitted light, the horizontal axis Average powder concentration
Using the relationship between the parameters comprising the measured condition, flour
The average powder concentration in the body transfer tube 1 is calculated.

[0063] From this, since the smaller than the diameter of the measuring portion the optical path length L of the actual powder transfer <br/> flue 1, and the transmittance of the Figure 3, a powder average density measurement conditions By selecting the tip interval L from the relationship with the following parameters, the attenuation of the light transmission amount can be suppressed. As a result, the powder average density value of the high-concentration particles of the powder 7 can be accurately measured.

In the present invention, in actual powder flow rate measurement,
Since the powder 7 is in a so-called mixed particle state having different particle diameters and different types of particles, a relational expression between the light transmittance shown in FIG. 3 and the parameter consisting of the powder average concentration and the measurement conditions is calculated. previously stored in the storage unit 17 of the device 14, from the output signal of the light amount detection end 5 measured by the arithmetic unit 15 (transmitted light intensity) in terms of transmittance of light to calculate the powder average density value.

On the other hand, the arithmetic unit 15 calculates an average flow velocity value of the transport medium from the output signal of the flow velocity detecting end 13. Further, the arithmetic unit 15 multiplies the average powder concentration value by the average flow velocity value of the conveying medium to calculate a powder flow value. These values are displayed by the display unit 16.

[0066] According to the present onset Akira, the pipe length as a condition 2.0
m, a powder transfer pipe 1 having a pipe diameter of 0.2 m is arranged in a piping system 9 ,
Opening 8 provided at a position 75% from the entrance side of powder transfer tube 1
The measuring tubes 11a and 11b for light transmission are inserted and protruded from the a and 8b, and are disposed so that the interval L between the tips is 0.1 m. As the powder 7 , silica sand No. 5 (dp32 = 0.34m)
m, ρ = 2.58) using air as a carrier medium and a flow velocity of 20 m
5 / second, the result as shown in FIG. 5 could be obtained. FIG. 5 is a diagram showing the relationship between the powder flow rate value and the elapsed measurement time. Here, the sampling interval of the powder concentration is set to 0.6 seconds, and the powder flow value is calculated and plotted from the multiplication of the average powder concentration value and the air flow velocity value.

In FIG. 5, the curve indicating the powder flow rate value shows a value of approximately 0 between the point A and the point B where the conveyance of the powder 7 is stopped, but the conveyance of the powder 7 is restarted. Immediately, the flow curve shows a flow rate of approximately 4.5 ton / hour. At this time , A
At the point, the perforated plate shutter 31 is inserted into the optical path for measurement.
The amount of powder conveyed from the strong level received during powder conveyance
The measurement was continued by attenuating the received light amount to a weak level at the time when the powder 7 did not move, and the start of transport of the powder 7 was monitored.

[0068] by the monitoring, detecting a decrease in the amount of transmitted light when the powder transfer began, multi by the detection signal
The perforated plate shutter 31 is retracted from the optical path for measurement, and a high level of transparency is again obtained so as to obtain a predetermined light receiving amount for powder flow rate measurement.
Over light intensity was automatically allowed to continue the powder flow rate is introduced into the measuring optical path.

[0069] As apparent from the above measurement, the present invention automatically continues with can powder flow rate measuring high density region, even when stopping the powder transfer occurs in the course of continuous measurement, after the powder transfer resumption It is a technique suitable for use in industrial online powder flow measurement because it can measure powder flow.

[0070]

According to the present invention, the following effects can be obtained. Measurement of high concentrations up to a powder concentration of 3 kg / m ³ is possible. It is possible to measure a large amount of transported high-concentration powder. The distribution of the powder concentration in the radial direction of the powder transfer tube can be measured by keeping the tip interval L of the light transmission measurement tube constant and traversing the inside of the tube in the radial direction. Even if the powder transfer is stopped, since the amount of transmitted light moderately adjusted can, without light amount detecting end it is broken, and, after the powder transfer restart automatically continuously measure the powder flow rate I can do it.

[Brief description of the drawings]

FIG. 1 is a view showing a state where a powder flow rate measuring device used in the present invention is installed.

FIG. 2 is a diagram showing a main part of a light transmittance detection unit used in the present invention.

FIG. 3 is a graph showing the relationship between the transmittance used in the present invention, and the parameters consisting of the average powder concentration and measurement conditions.

FIG. 4 is an explanatory diagram for measuring a powder concentration distribution in a diameter direction in a pipe according to the present invention.

FIG. 5 is a diagram illustrating a relationship between a powder flow rate value and a measurement elapsed time according to an embodiment of the present invention.

Is a diagram showing an example in which a light amount level setting circuit in the light source power used in the present invention; FIG.

Ri FIG der showing a <br/> an embodiment of coli Mate Ing lens apparatus used in the present invention; FIG,凹Re to (a) the light diffusing lens
(B) using a convex lens for the light diffusion lens
FIG.

[8] Ri FIG der showing an embodiment of the optical attenuating perforated plate shutter used in the present invention, (a) is a side sectional view, (b) is
FIG. 3 is a diagram illustrating a light attenuation state.

FIG. 9 is a diagram showing an example of a conventional light transmission type powder densitometer.

[Description of Signs ] 1 Powder transfer tube 2 Observation window 3 Light source 4 Parallel light beam 5 Light amount detection end 6 O-ring 7 Powder 8a, 8b Opening 9 Piping system 10 Light transmittance detector 11a, 11b Light transmission measurement tube 12 distal spacing adjustment device 13 flow rate detecting end 14 arithmetic device 15 calculating unit 16 display unit 17 storage unit 18 instruction portion 19 cover 20 converging lens 21 light source power 22 laser oscillator 23 discharge current control circuit 24 discharge current output circuit 25 a command signal 26 output level setting circuit 27 output light beam 28a concave lens 28b convex lens 29 measuring section parallel beam 30 convex lens 31 a perforated plate shutter 31a perforated plate 31b perforated plate 31c perforated plate 32 shutter driving device 33 diffuse light beam 34 transmitted light 35 Passing light

Claims (5)

(57) [Claims] 1. A method according to claim 1 , wherein two opposing observation windows are provided on a wall of the tube on which the powder is conveyed by the conveyance medium, and a predetermined amount of received light is provided.
The light is transmitted through the observation window so that the transmitted light is received, and the powder flow rate is calculated from the powder average concentration measured using the transmittance of the transmitted light amount and the flow velocity value of the transport medium. a method for measuring the flow rate of a high concentration powder, when conveying of the powder is stopped, comparing the received light levels when the powder conveying
Using a light amount changing means for providing the received light levels which weakened by, the transmittance under conditions that provide the received light amount level weakened by <br/> measurement, when the powder is initiated conveyed powder Start of transfer
The attenuation of the transmitted light quantity detected with the, group Dzu of the detection signal
The light amount changing means is released so that a predetermined amount of light is received.
Wherein under conditions divided to give received light level at the time of the powder transfer
Measure the transmittance and determine the average powder concentration from the measured transmittance.
Constant, and is conveyed in the tube, characterized in that to calculate the powder flow rate from the powder the average concentration of this and the flow rate value of the transport medium
Flow measurement method for high concentration powder. 2. A light transmission measurement tube is provided in a tube in which powder is conveyed by a conveyance medium, and two light transmission measurement tubes protruding from each other at a predetermined interval are provided so as to have a predetermined amount of received light.
Transmit the light through the constant tube, receive the transmitted light,
High-concentration powder for calculating the powder flow rate from the powder average density measured using the transmittance of the transmitted light amount and the flow velocity value of the transport medium
Of a flow rate measuring method, sometimes <br/> conveying of the powder is stopped, the light amount changing means for providing the receiving <br/> light levels which weakened compared to receive light levels at the time of powder conveying using, weakened light receiving
The transmittance is measured under a condition that gives an amount level, and when the powder is started to be conveyed , the attenuation of the amount of transmitted light accompanying the start of the conveyance of the powder is detected, and based on the detection signal, a predetermined amount of received light is detected.
As will be, the transmittance was measured under the condition of giving the received light level at the time to the powder transfer canceling the light quantity changing means,
The powder average concentration was determined from the measured transmittance, high density powder flow conveyed through the tube and calculates the powder flow rate from the powder the average concentration of this and the flow rate value of the transport medium Measuring method. 3. A method for measuring the flow rate of a high-concentration powder conveyed through the tube according to claim 1 or claim 2, characterized in that said light quantity changing means performs the light source additional current operation of the light source body. 4. A method for measuring the flow rate of a high-concentration powder conveyed through the tube according to claim 1 or claim 2, characterized in that the optical attenuating shutter operating said light quantity changing means. 5. A method according to claim 1, which comprises carrying out the operations of said light quantity changing means co Li Mate Ing lens device
Or flow measurement method of the high density powder is transported in the tube according to claim 2.