JPH0755524A - Method and instrument for measuring flow rate of high-concentration powder carried on carrying medium in pipe - Google Patents

Abstract

PURPOSE:To continuously and automatically measure the concentration of powder when the powder is carried and the flow rate of the powder in an on-line state by calculating the flow rate of the powder by using the light transmissivity of the powder found from the receiving quantity of light transmitted by the powder through an observation port facing the wall of a pipe through which the powder is carried by a carrying medium. CONSTITUTION:A luminous flux made incident from a light source body 3 which is connected to the end section of a measuring tube 11a and emits the luminous flux across powder in a vertical pipe 1 at right angles is detected by means of a light quantity detecting terminal 5 as a parallel luminous flux after passing through another measuring tube 11b. Relational expressions among the light transmissivity and average concentration of the powder and parameter of measuring conditions is stored in advance in the storing section 17 of an arithmetic device 14 and an arithmetic section 15 converts the output signal (intensity of transmitted light) of the detecting terminal 5 and, at the same time, calculates the average concentration of the powder. When the carrying of the powder is restarted, a high-level light quantity for measuring flow rate of the powder is introduced to a measuring optical path and the flow rate of the powder is automatically and continuously measured by detecting 5 a decrease in the quantity of transmitted light and retreating 32 a light attenuating shutter 31 from the optical path.

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 and a measuring apparatus therefor.

[0002]

2. Description of the Related Art Conventionally, as a powder flow rate measuring method and a measuring apparatus therefor, it is known to use a light transmission type powder densitometer. An example is shown in FIG. In FIG. 9, two observation windows 2 facing the powder transfer tube 1 are installed. The parallel light flux 4 emitted from the light source body 3 is made incident from one observation window 2 and is made incident on the inside of the powder transfer tube 1. The incident light is attenuated by the powder 7, and the remaining transmitted light is extracted from the other observation window 2 and introduced into the photodetector 5 to detect the amount of transmitted light.

That is, the particle concentration is measured by setting the light amount (incident light intensity) of the light source to a constant value and detecting the change in the transmitted light amount depending on the particle concentration. Further, assuming that the moving speed of the particles is equal to the flow velocity of the carrier medium (gas), the powder flow rate value is calculated from the product of the particle concentration value and the mean flow velocity value of the carrier medium.

[0004]

However, in the measurement by the powder densitometer by the above-mentioned light transmission method, the maximum measurable powder concentration is restricted. From powder transfer pipe to carrier medium (gas)
It is necessary to sample a part of the particles and measure them by suctioning at a constant velocity or by providing a branch pipe.
Even with such an improved method, the maximum powder concentration of the dust densitometer that has been put into practical use is about 200 gr / m ³ ,
It is difficult to measure the flow rate of the high-concentration powder by applying the light transmission method, because the light is attenuated with respect to the particle group having a higher concentration.

The present applicant has attempted to solve the above-mentioned problems, and is directed to Japanese Patent Application No. 4-234721 and Japanese Patent Application No. 4-233.
Filed under No. 794. Generally, the powder is continuously conveyed to measure the powder concentration in the high concentration region, but in many cases, the conveyance of the powder is stopped.

In this case, the optical high-concentration powder flow rate measuring device used is a powerful light source, and when the powder is not flowing, the transmitted light amount is hardly attenuated. Light emission of the light source so that the detection end is destroyed, the detection ability is reduced, and in order to prevent destruction of the light detection end, when the powder is not flowing, the strong detection light of the light source is not received by the light detection end. It has been found that when the powder flow is restarted by stopping or stopping the incidence of projection light, continuous measurement cannot be performed.

The present invention is based on the invention disclosed in the above-mentioned Japanese Patent Application No. 4-234721, and is intended to solve the problems. In the case of carrying the powder, including the case of stopping the carrying of the powder. An object of the present invention is to provide a method and an apparatus for enabling continuous automatic measurement of powder concentration in a high concentration region and measuring the powder flow rate online.

[0008]

In order to achieve the above-mentioned object, as a method invention, the first invention is to install two observation windows opposed to the tube wall of a tube in which powder is carried by a carrier medium. , Through the observation window, the light is transmitted, the transmitted light is received, and the powder average concentration and the flow velocity value of the carrier medium measured by using the transmittance from the predetermined received light amount of the transmitted light amount. A method for calculating the powder flow rate from the above, wherein when the powder conveyance is stopped, the predetermined light reception amount is measured using a light reception amount that gives a light amount level weakened from the light amount level at the time of powder transfer. Detecting the attenuation of the transmitted light quantity when the powder is started to be conveyed, and using the detection signal, the predetermined light receiving amount is strengthened to the light quantity level at the time of powder conveyance to measure the powder average concentration. It is possible to calculate the powder flow rate from the average concentration and the flow velocity value of the carrier medium. It is an method for measuring the flow rate of a powder that is transported by the transport medium in the tube to symptoms.

In a second aspect of the invention, the powder is transmitted through a light-transmitting measuring tube which is arranged so as to project so that the powder is opposed to the tube conveyed by a carrier medium at a constant tip interval. Is a method of calculating the powder flow rate from the powder average concentration measured using the transmittance from the predetermined received light amount of the transmitted light amount and the flow velocity value of the carrier medium, When the conveyance of the powder is stopped, the predetermined amount of received light is measured by using the amount of received light that gives a light amount level that is weakened from the light amount level when the powder is conveyed, and the attenuation of the transmitted light amount when the powder starts to be conveyed is measured. Detecting the detected signal, the predetermined light receiving amount is strengthened to the light amount level during powder conveyance to measure the powder average concentration, and the powder flow rate is calculated from the powder average concentration and the flow velocity value of the conveying medium. It is carried by the carrier medium in the pipe characterized by calculating It is an method for measuring the flow rate of a density powder.

In this case, as the third invention, the fourth invention, or the fifth invention, the means for weakening or re-strengthening the light amount level of the predetermined light receiving amount as described above is operated by operating the light source additional current of the light source body. This is done by operating the light-attenuating shutter or by operating the collimating lens device of the light source.

As a device invention, a sixth invention is a pipe having observation windows located on a line orthogonal to the axis and opposed to each other,
A light source for incident a light beam disposed in one of the observation windows, a light transmittance detection unit having a light amount detection end disposed in the other observation window, and detection for measuring the flow velocity of the carrier medium. A powder flow rate measuring device comprising an end and a powder average concentration and a medium average flow velocity calculated from the output signals thereof, respectively, and a device for calculating a powder flow rate by combining them.
Optical means of the light transmittance detecting portion for changing the light receiving amount level to the light amount detecting end and light for receiving the detection signal of the light transmittance detecting end and comparing the signal level with the threshold value to change the light receiving amount level. A flow rate measuring device for powder carried by a carrying medium in a pipe, characterized in that the optical means of the transmittance detecting section is provided with a comparing means for issuing a command signal for switching a light quantity level set value.

The seventh invention, the eighth invention, or the ninth invention is a tube having openings facing each other on a line orthogonal to the axis, and a fixed tip inserted into these openings. A light-transmitting measuring tube which is arranged so as to be opposed to each other at an interval, a tip interval adjusting device attached to the light-transmitting measuring tube, and a light source for incident light flux arranged at the rear end of one of the measuring tubes. The body, the light transmittance detecting section having a light quantity detecting end arranged at the rear end of the other measuring tube, the detecting end for measuring the flow velocity of the carrier medium, and the powder average concentration and the medium from the output signals thereof. A flow rate measuring device comprising a device for calculating an average flow velocity and a device for calculating a powder flow amount by multiplying the average flow velocity with each other. The light source additional current control device for the light source body is provided with a light amount level setting circuit and the light transmitting device. The detection signal from the rate detection end is received and the signal level and threshold value are compared to The level setting circuit is provided with a comparison means for issuing a command signal for switching the light amount level set value, and at least one shutter for attenuating the light transmission amount and the shutter are inserted into and retracted from the light source body in the measuring optical path. Comparing means for receiving a detection signal from the moving device and the light transmittance detecting end, comparing the signal level and the threshold value, and issuing a charging / retracting command signal to the moving device,
Alternatively, a plurality of collimating lens devices having different light densities of the parallel light fluxes, a moving device for loading and unloading the collimating lens devices on the optical axis between the light source body and the measuring tube, and the light transmittance detection. The high-concentration powder conveyed by the conveying medium in the pipe is provided by the comparison means for receiving the detection signal at the end and comparing the signal level with the threshold value and issuing the charging / retracting command signal to the moving device. This is a flow rate measuring device.

[0013]

The present invention has the above-described structure, and in the example of measuring the flow rate of a high-concentration powder, the measurement for light transmission is arranged so as to be opposed to each other at a constant tip interval in a pipe for conveying the powder by a conveying medium. Light is transmitted through the tube to the powder,
By inserting the measurement tube for light transmission from the opening oppositely, the measurement section optical path length is made smaller than the actual powder transfer tube diameter, and while suppressing the amount of attenuation of light transmission as much as possible, as a light source,
It uses a strong light source body capable of easily realizing a parallel light flux having a high light intensity, such as a continuous light emitting laser light source.

In the present invention, in the actual powder flow rate measurement,
Since the powders are in a so-called mixed particle state in which the particle diameters are different and the types of particles are different, the output signal from the light amount detection end is calculated using the relationship between the transmittance and the measurement condition of the powder average concentration as shown in FIG. An average density value of the powder is calculated by the calculation device of the present invention.

FIG. 3 is a diagram showing parameters which are related to the transmittance (I / Io), the average concentration of the powder and the measurement conditions when the measuring device of FIGS. 1 and 2 which will be described later is used. It was obtained by a calibration test using seeds and iron ore.

As is apparent from FIG. 3, even if the particle diameters of the powders are different, the transmittance (I / Io) is measured on one calibration line by considering the true specific gravity (ρ) of the particles. I was able to do it. From this, it was found that the present invention enables measurement even if the powder particle size and powder type are mixed.

That is, since L as a measuring device is specified and the true specific gravity (ρ) and the harmonic mean diameter (dp32) of the powder to be measured are obvious as eigenvalues of the handling process, the transmittance (I / Io) is measured and the average powder concentration value (kg / m ³ ) is uniquely determined from the relationship shown in FIG.

On the other hand, the medium average flow velocity value is calculated by the arithmetic unit of the present invention from the detection end for measuring the flow velocity of the conveyed medium and its output signal. That is, the medium average flow velocity value is calculated by using a pressure detection signal from an existing Pitot tube, or a general relational expression of the temperature detection signal from the heat ray type flow velocity detection end and the medium average flow velocity.

Further, the powder flow rate value can be calculated by multiplying the powder average concentration value and the medium average flow velocity value by the arithmetic unit of the present invention. Further, in the present invention, by making the distance (L) between the tips of the two opposed measurement tubes for light transmission constant and traversing the tubes in the radial direction,
It is also possible to measure the distribution of powder concentration in the radial direction of the tube.

FIG. 4 is an explanatory view for estimating the diametrical powder distribution in the vertical pipe. Keeping the tip interval (L) of the measuring tube at a constant interval, the tube is continuous from at least the center of the tube toward one of the tube walls within the range of the inner diameter of the tube, and the tip interval length is set as one unit to make the tube stepwise. By moving along the radius, the powder concentration distribution in the diameter direction in the tube is measured from the attenuation distribution of the amount of transmitted light corresponding to the moving position in the tube, and at the same time, the weighted average expression of the following mathematical formula 1 is used to calculate the present invention. The average powder concentration is calculated by the device.

[0021]

[Equation 1]

The powder flow rate value can be calculated by multiplying the powder average concentration value and the medium average flow velocity value by the arithmetic unit of the present invention.

In the present invention, a high-power light source is used to measure the particle concentration of the high-concentration powder. However, when the particle concentration is low, such as when the powder conveyance is stopped, the transmitted light intensity increases. When the transmitted light having an excessively high light intensity is applied to the light detecting end, the light detecting end may be burned out.

In the present invention, when the powder conveyance is stopped, the predetermined light reception amount is measured by using the light reception amount which gives a light amount level weakened from the light amount level at the time of powder conveyance, and the powder conveyance is started. When the attenuation of the transmitted light amount at the time of the powder is detected, the predetermined light receiving amount is increased to the light amount level at the time of powder conveyance by the detection signal to measure the powder average concentration, and the powder average concentration and the conveyance medium Since the powder flow rate is calculated from the flow velocity value, even if the powder conveyance is interrupted during continuous measurement, there is no burning of the photodetector that detects the transmitted light intensity due to the excessive transmitted light intensity. It is something to do.

The predetermined amount of received light according to the present invention is a light intensity for light transmission measurement during powder conveyance, and is the amount of light received by the photodetector if the powder is not present in the measurement section.
For the measurement during powder conveyance, the light quantity is held and projected, and the powder that is present in the measurement section receives the attenuated light, and the transmittance (attenuation ratio) is used to determine the powder concentration. taking measurement. In this way, the amount of light that is projected or received at a constant intensity for measuring the powder concentration during powder conveyance is referred to as the predetermined amount of received light for measurement during powder conveyance.

Therefore, the weakened predetermined light receiving amount used for the measurement when the powder conveyance is stopped is 1/10 to 1/10000 of the predetermined light receiving amount used for the powder conveyance measurement. Then, it is a constant value selected below a value calculated from the ratio of the allowable light receiving amount of the light receiving element used at the light transmittance detecting end to the maximum output light amount of the light source.

In order to satisfy the above, the present invention has taken three measures. The first measure is to switch between the strong level for measurement when the above-mentioned predetermined amount of received light is conveyed and the weak level for measurement when the powder is stopped by changing the additional current of the light source of incident light. Instead, it changes the light intensity.

The means for switching the light intensity of the light source, for example, the laser output value from the weak level to the strong level or vice versa, is the output level to the discharge current control circuit of the laser power source by the light intensity level switching signal from the powder densitometer. This is done by switching the output setting signal of the setting circuit to a strong level signal or a weak level signal. Normally, switching the output level of this laser output value is 100 to 10 of the rated total output.
It is possible within the range of%.

The second measure is to install a light-attenuating shutter in front of the light-focusing lens in the light-transmittance detecting section so as to attenuate the light and prevent damage to the light-detecting end. The movement of the shutter to the optical axis is performed by the shutter drive device, and the command to the drive device is performed by referring to the transmitted light amount value detected at the light detection end.

For example, a light-attenuating shutter for setting a light receiving amount that does not damage the light detecting end as a weak level of the predetermined light receiving amount and attenuating the high level light amount of the predetermined light receiving amount to the weak level light amount is for measurement. It is charged in the optical path and the measurement is continued to monitor the start of powder conveyance.

If the particle concentration increases in this state, the amount of transmitted light becomes smaller or the amount of transmitted light cannot be detected. Therefore, the optical attenuation shutter is moved away from the measuring optical path and the total light amount of the light source is used to measure the powder flow rate. Is to start.

The light attenuation shutter of the present invention attenuates the amount of transmitted light to about 1/100 to 1/10000. Further, if the amount of transmitted light is constantly measured in a measurement standby state with a shutter entering the optical axis of the measurement system and the amount of transmitted light is attenuated, it is possible to monitor changes over time in the entire particle concentration measuring device system.

The third measure is a structure in which a collimating lens device that attenuates the intensity of incident light is installed between the light source body and the light transmission measuring tube of the light emitting unit, instead of the shutter that attenuates the amount of transmitted light. is there.

This collimating lens device is a high-level collimating lens device for converting all output light beams of the light source body into parallel light beams for measurement, and only a part of the output light beam cross section of the light source body around the optical axis. A plurality of attenuating collimating lens devices having different optical attenuating ratios for making the above-mentioned parallel light flux for measurement and a parallel light flux having the same diameter are arranged in parallel in parallel to the optical axis, and are most suitable in the standby state of powder flow rate measurement. A collimating lens device having a high light attenuation factor is inserted in the output optical axis of the light source body to attenuate the incident light amount, and as a result, the predetermined light receiving amount at the light transmittance detection end is set to a weak level.

The light-attenuating collimating lens device of the present invention attenuates the amount of incident light to about 1/10 to 1/100. Replacement and replacement of the collimating lens device is performed by the collimating lens device switching device, and an instruction to this switching device is performed by referring to the transmitted light amount value detected at the light detection end.

For example, if the amount of transmitted light which does not damage the light detecting end is set and the actual amount of transmitted light is larger than a predetermined set value, the collimating lens device for light attenuation is moved to the optical axis to transmit the amount of transmitted light. Is attenuated, and the measurement standby state is set.

If the particle concentration increases in this state, the amount of transmitted light becomes smaller or the amount of transmitted light cannot be detected. Therefore, another collimating lens device having the total amount of light of the light source as the incident light amount is used. It is arranged to be exchanged with the mating lens device, and the measurement of the powder flow rate is started by using the total light amount of the light source.

[0038]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are views showing an embodiment of the present invention, FIG. 1 is a view showing a state in which the device of the present invention is installed, and FIG. 2 is a main part of a light transmittance detecting portion of the device of the present invention. FIG.
In the figure, 10 is a light transmittance detection unit of the powder flow meter, and 11
Reference numerals a and 11b are light transmission measuring tubes, 12 is a tip interval adjusting device, and 13 is a flow velocity detecting end. 7 is a powder particle.

The powder flow rate measuring device of the present invention is provided with a vertical pipe 1 having an equal cross-sectional area and concentric with an adjacent pipe provided in a pipe system 9 in which powder is conveyed by a conveying medium, and orthogonal to the axis C. Line E
Measuring tube 11a for light transmission, which has openings 8a, 8b located above and opposed to each other, is inserted into these openings 8a, 8b, and is projectingly arranged so as to be opposed to each other at a constant tip interval;
11b, a tip interval adjusting device 12 attached to the light-transmitting measuring tubes 11a, 11b, a light source 3 for light flux incidence arranged at the rear end of one measuring tube 11a, and a light source power source 2 for the light source.
1 and a light transmittance detecting unit 10 including a light amount detecting end 5 arranged at the rear end of the other measuring tube 11b, a flow velocity detecting end 13 for measuring the flow velocity of the carrier medium, and output signals from these detecting ends. A device 14 for calculating the powder average concentration value and the medium average flow velocity value, multiplying them, and calculating the powder flow rate value is combined, and further, when the powder conveyance is stopped, the predetermined light reception is performed. Measurement is continued using the received light amount that gives a light amount level that is weakened from the light amount level during powder transfer, and the start of powder transfer is monitored to detect the attenuation of the transmitted light amount when powder starts to be transferred. By using the detection signal, the predetermined light receiving amount is strengthened to the light amount level during powder conveyance to measure the powder concentration, and the powder flow rate is calculated from the powder concentration and the flow velocity value of the conveying medium. Yes, a device that weakens or strengthens the light level as described above Then, the light source power source 21 for switching the output light amount by changing the light source additional current as shown in FIG. 6, FIG. 7, and FIG. 8 described later to the light transmittance detection unit 10, the shutter for attenuating the transmitted light amount, or the incident light intensity. The collimating lens device which can be switched is provided.

The arithmetic unit 14 receives the transmission signals obtained by converting the measured values into signals from the light amount detecting end 5 and the flow velocity detecting end 13 in the light transmittance detecting unit 10, calculates them in the calculating unit 15, and displays them in the display unit 16. The flow rate of the powder 7 is displayed. 17 is a storage unit, 1
Reference numeral 8 is a command unit, and 19 is a cover.

FIG. 6 shows a light source power source 21 provided with a light quantity level setting circuit for giving a light quantity level setting value switching command to a light source current control circuit for controlling the light intensity of a light source body according to the present invention.
It is a figure which shows one Example, ie, the example using a continuous light emitting laser light source.

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

Therefore, the means for switching the laser output value of the laser oscillator 22 from the weak level to the strong level or vice versa is a command from the means for receiving the detection signal at the light transmittance detecting end and comparing the signal level with the threshold value. The output level setting circuit 2 to the discharge current control circuit 23 of the laser power supply according to the signal
This is done by switching the output setting signal of 6 from a strong level signal to a weak level signal. 21 is a light source (leather)
Power.

Normally, the switching of the output level of the laser output value is possible within the range of 100 to 10% of the rated total output. The means for comparing is a software means using an arithmetic unit of a powder flowmeter that receives a detection signal from the light transmittance detecting end,
Alternatively, either of the means for comparing the low frequency components of the detection signal with an analog circuit can be used.

FIGS. 7A and 7B are views showing an embodiment of the collimating lens device according to the present invention.
(A) is a figure which used the concave lens for the light diffusion lens, (b) is a figure which used the convex lens for the light diffusion lens.

When measuring the powder concentration, the thin parallel light beam output as the output light beam 27 from the light source body 3 is diffused by the convex lens 28a or the concave lens 28b for light diffusion, and the light beam diameter becomes the diameter of the measuring part parallel light beam 29. The convex lens 30 for collimating provided at the enlarged portion is transmitted to form a parallel light beam 29 for measuring portion having a predetermined diameter. Reference numeral 33 is a diffused light flux.

In order to weaken the light intensity (energy / unit projection area) of the measuring portion parallel light beam 29, the light diffusing lens 28a,
A lens having a different focal length of 28b is used, and the light diffusion degree thereof is larger than the light diffusion degree in the case of measurement. For example, after making the spread diameter three times that in the case of measurement, The partial light flux (the area having the same area as the measurement light flux) is made into the measurement light flux 29 by the convex lens 30 for the collimating lens. Light diffusion lenses 28a, 28b
In an example in which the degree of light diffusion in 3 is three times that in the case of measurement, the light intensity of the measuring unit parallel light flux 29 can be set to 1/9.

FIG. 7 shows two examples of optical methods.
The optical intensity of the parallel light flux at the measurement portion can be weakened by other optical methods, for example, by arranging the convex lens for the collimating lens at a position far from the light diffusing lens.

The present invention changes the light intensity of the parallel light flux in the measuring section by switching the arrangement of the plurality of collimating lens devices designed by the above optical method on the output optical axis of the light source body. .

FIGS. 8 (a) and 8 (b) are views showing an embodiment of the light attenuation shutter used in the present invention. FIG. 8 (a) is a side sectional view, and FIG. 8 (b) is the light after passing through the light attenuation shutter. It is a figure which shows the decay state of. Here, a laser light source and a perforated plate shutter 31 are used.

The shutter 31 is a thin plate made of stainless steel having an outer diameter of 20 mm and a thickness of 0.1 mm, and a large number of small holes formed at equal intervals by a processing method such as etching. It is as small as possible.

Of the light incident on the first perforated plate 31a, the light irradiated on the thin plate other than the holes is blocked, but the light passing through the holes travels straight and is irradiated on the next perforated plate 31b. Is
As a result of irradiating the next porous plate 31c, the total amount of light is attenuated. As described above, the attenuated state after passing through the light attenuating shutter irradiated by the perforated plates 3a, 3b, and 3c is the light distribution state as shown in (b).

This damping ratio is basically determined by the total area of the holes (opening ratio) with respect to the area of one perforated plate and the relative weight arrangement of these perforated plates. By finely adjusting the transmittance (attenuation rate)
Can be finely adjusted.

In the present invention, a silicon photodiode type light receiving element is used at the light transmittance detecting end, the maximum measurable light amount of this type is 50 mW, and when a light amount of more than that is irradiated, the measurement accuracy becomes high. descend.

To measure the particle concentration of the high-concentration powder,
In an example in which a laser light source with an output of 5 W is used as the light source, the target value of the light attenuation rate by the light attenuation shutter is 1/100 =
Although it is 0.05 / 5, the attenuation ratio is 1/100 to 1/100 due to the reliability of the shutter perforated plate performance and the change over time.
It was set to 00.

In order to realize this attenuation ratio, various hole diameters, the number of holes and the number of holes of the perforated plate were changed, various trial manufactures were carried out, the attenuation ratio was actually investigated, and the above-mentioned perforated plate (holes of φ0.15 mm with pitch 0 0.25 mm) was adopted as the light attenuating shutter having a four-sheet structure. If it is possible to perform drilling with a smaller hole diameter, the attenuation rate per perforated plate can be increased, so that the number of perforated plates can be reduced.

This light attenuation shutter 31 is used for the light converging lens 2 in the light transmittance detecting section 10 as shown in FIG.
Install in front of 0. The movement of the light attenuation shutter 31 to the optical axis is performed by the shutter drive device 32, and the command to the drive device 32 is performed by referring to the transmitted light amount value detected at the light detection end.

A case of carrying out the method of the present invention using the above-mentioned apparatus of the present invention will be described. The powder is passed through the vertical pipe 1 provided in the piping system 9 for carrying the powder by the carrier medium. Here, since the vertical pipe 1 has a concentric and equal cross-sectional area with the pipe in the pipe system 9, the uniformity of the flow in the measurement part is maintained, and therefore the powder concentration passing through the vertical pipe 1 depends on the particles in the pipe system 9. 7
It is the same as the powder concentration of.

The light transmission measuring tubes 11a and 11b are vertical tubes 1.
Since the measurement tubes 11a and 11b for light transmission have the same diameter, the measurement tubes 11a and 11b for light transmission have the same diameter because the measurement tubes 11a and 11b are inserted from the openings 8a and 8b facing each other and located on the line E orthogonal to the axis C of the. Match. As a result, the luminous flux incident from the light source body 3 for incident luminous flux connected to the end of the measuring tube 11a crosses the powder in the vertical tube 1 at a right angle as a parallel luminous flux 4, passes through the measuring tube 11b, and passes through the quantity of light. It is detected at the detection end 5.

Alternatively, the distance between the tip ends of the opposed measuring tubes located inside the vertical tube is maintained at a predetermined interval, and one tube wall is continuously connected to the other tube wall within a predetermined range within a range of the inner diameter of the vertical tube. By moving along the diameter of the vertical tube at a velocity, the distribution of the amount of transmitted light (transmittance) in the diameter direction inside the vertical tube is detected.

Here, when the conveyance of the powder is stopped, the light intensity of the light source body 3 is changed so that the transmitted light intensity detected by the light amount detecting end 5 becomes a predetermined weak level of the received light amount. The light quantity detecting end 5 is prevented from being destroyed, and the measurement is continued.

When the powder is conveyed again, the attenuation of the transmitted light amount is detected, and the detection signal enhances the received light amount to a predetermined strong level, and one of the measuring tubes for the fixed interval. From the light in the vertical tube using the relationship between the transmittance, the average density of the powder, and the straight line of the measurement conditions shown in FIG. Calculate the average concentration.

In this case, since the optical path length (L) of the measuring section is made smaller than the actual diameter of the powder conveying tube, from the relationship between the transmittance, the average concentration of the powder and the parameter consisting of the measuring conditions in FIG. The attenuation of the light transmission amount can be suppressed by selecting the tip interval. As a result, it is possible to accurately measure the powder average concentration value of the high concentration particle group of the powder.

In the present invention, in the actual powder flow rate measurement,
Since the powders are in a so-called mixed state in which the particle diameters are different and the types of particles are different, the relational expression of the parameters including the light transmittance, the powder average concentration, and the measurement conditions shown in FIG. The calculation unit 15 stores the data in the storage unit 17 in advance.
The output signal (transmitted light intensity) of the light amount detecting end 5 measured in step 1 is converted into the light transmittance, and at the same time, the powder average concentration value is calculated.

On the other hand, the medium average flow velocity value is calculated by the calculating unit 15 from the output signal of the flow velocity detecting end 13. Further, the powder flow rate value is calculated by multiplying the powder average concentration value and the medium average flow velocity value by the calculation unit 15. These values are displayed on the display unit 16.

According to the method of the present invention, the pipe length is 2.0 as a condition.
m vertical pipe with a diameter of 0.2 m is placed in the piping system, and the light transmission measuring pipe is inserted and protruded from the opening provided at a position of 75% from the inlet side of the vertical pipe, and the distance between the tips (L) Is arranged to be 0.1 m, and as a powder, silica sand No. 5 (dp32 = 0.34 mm,
When ρ = 2.58) was conveyed with air as a medium at a flow rate of 20 m / sec, the results 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 powder concentration sampling interval is set to 0.6 seconds, and the powder flow rate value is calculated and plotted from the multiplication of the powder average concentration value and the gas flow velocity value.

In FIG. 5, the curve showing the powder flow rate value shows that the flow rate measurement value between point A and point B is almost 0 when the powder conveyance is stopped.
The flow rate curve shows a flow rate of approximately 4.5 tons / hour immediately after the powder conveyance is restarted. At this time, at point A, an optical attenuation shutter for attenuating the high level light intensity of the predetermined light receiving amount for powder flow rate measurement to the weak level predetermined light receiving amount when the powder is not conveyed is installed in the measurement optical path. Then, the measurement was continued and the start of powder conveyance was monitored.

By the above-mentioned monitoring, a decrease in the amount of transmitted light at the start of powder conveyance is detected, and the detection signal causes the shutter for light attenuation to be withdrawn from the optical path for measurement, and again a predetermined amount of received light for measuring the powder flow rate is detected. The intensity of light at a strong intensity level is introduced into the optical path for measurement, and the powder flow rate is automatically continued.

As is clear from the above measurement, the present invention is capable of measuring the powder flow rate in the high-concentration region, and even if the powder conveyance is stopped during the continuous measurement, it is automatically continued after the powder conveyance is restarted. Since it is possible to measure the powder flow rate by using this method, it is a technology suitable for use in industrial online powder flow rate measurement.

[0070]

According to the present invention, the following effects can be obtained. It is possible to measure high concentration up to 3kg / m ^{3 of} powder concentration. It is possible to measure a large amount of highly concentrated powder. It is possible to measure the powder concentration distribution in the radial direction of the vertical pipe by making the tip interval (L) of the measuring pipe constant and traversing the inside of the pipe in the radial direction. Even if the powder conveyance is stopped, the amount of transmitted light can be adjusted appropriately, so that the light detection end is not destroyed, and the powder flow rate can be automatically measured after the powder conveyance is restarted.

[Brief description of drawings]

FIG. 1 is a diagram showing a state in which the device of the present invention is installed in a piping system.

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

FIG. 3 is a diagram showing the relationship between the transmittance according to the present invention and the parameters consisting of the average powder concentration and the measurement conditions.

FIG. 4 is an explanatory diagram for measuring a diametrical powder concentration distribution in a tube according to the present invention.

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

FIG. 6 is a view showing an embodiment in which a light source power supply is provided with a light intensity control circuit and a light amount level setting circuit according to the present invention.

FIG. 7 is a diagram showing an embodiment of a light attenuation shutter according to the present invention.

FIG. 8 is a diagram showing an embodiment of a collimating lens device according to the present invention.

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

[Explanation of symbols]

 10 Light Transmittance Detecting Part of Powder Flowmeter 11a, 11b Light Transmitting Measuring Tube 12 Tip Spacing Adjuster 13 Flow Rate Detecting End 14 Powder Flowmeter Calculator 15 Calculator 16 Display 17 Memory 18 Commander 19 Cover 20 lens 21 light source (laser) power source 22 laser oscillator 23 discharge current control circuit 24 discharge current output circuit 25 light intensity level switching signal from powder densitometer 26 output level setting circuit 27 laser output luminous flux 28 light diffusing lens 28a convex lens 28b concave lens 29 Measuring part parallel light beam 30 Convex lens for collimating 31 Perforated plate shutter 31a First perforated plate 31b Second perforated plate 31c Third perforated plate 32 Driving device 33 Diffused light beam 34 Transmitted light 35 Light

Claims (9)

[Claims] 1. A two observation window facing a tube wall of a tube in which powder is conveyed by a conveyance medium is provided, light is transmitted through the observation window, and the transmitted light is received, A method for calculating a powder flow rate from a powder average concentration measured using a transmittance from a predetermined received light amount of a transmitted light amount and a flow velocity value of the transfer medium, wherein when the powder transfer is stopped. ,
The predetermined amount of received light is measured by using the amount of received light that gives a light amount level that is weakened from the light amount level at the time of powder conveyance, and the attenuation of the transmitted light amount when the powder is started to be conveyed is detected, and by the detection signal, A pipe characterized by increasing the predetermined amount of received light to a light amount level at the time of powder conveyance to measure the powder average concentration, and calculating the powder flow rate from the powder average concentration and the flow velocity value of the conveying medium. A method for measuring the flow rate of powder carried by a carrying medium. 2. The light is transmitted through a light-transmitting measuring tube which is disposed so as to project so that the powder is opposed to the inside of a tube which is conveyed by a conveying medium at a constant tip interval, and the transmitted light is passed through the tube. A method of calculating a powder flow rate from a powder average concentration measured using the transmittance of a received light amount from a predetermined received light amount and a flow velocity value of the transfer medium, wherein the powder is transferred. When stopped, the predetermined amount of light received is measured using the amount of light received that gives a light amount level that is weakened from the amount of light during powder conveyance, and the attenuation of the amount of transmitted light when powder starts to be conveyed is detected, By using the detection signal, the predetermined amount of received light is increased to a light amount level during powder conveyance to measure the powder average concentration, and the powder flow rate is calculated from the powder average concentration and the flow velocity value of the conveying medium. Of high-concentration powder conveyed by the conveying medium in the pipe characterized by Flow measurement method. 3. The medium according to claim 1 or 2, wherein the means for weakening or once again strengthening the light quantity level of a predetermined received light quantity is carried out by operating the light source additional current of the light source body. High-concentration powder flow rate measurement method. 4. The high-concentration powder carried by a carrier medium in a pipe according to claim 1 or 2, wherein means for weakening or once again strengthening a light quantity level of a predetermined received light quantity is performed by a light attenuation shutter operation. How to measure body flow. 5. The pipe as claimed in claim 1 or 2, wherein means for weakening or strengthening the light amount level of a predetermined amount of received light is carried out by operating the collimating lens device of the light source. Flow measurement method for high concentration powder. 6. A tube having observation windows located on a line orthogonal to the axis and opposed to each other, a light source for light beam incidence arranged in one of the observation windows, and the other observation window. , A light transmittance detection unit having a light amount detection end, a detection end for measuring the flow velocity of the carrier medium, and a powder average concentration and a medium average flow velocity are calculated from their output signals, and these are multiplied. And a powder flow rate measuring device comprising a combination of a device for calculating the powder flow rate, wherein the optical means of the light transmittance detecting section for changing the received light level to the light amount detecting end and the light transmittance detecting end. Receiving means for comparing the signal level with the threshold value and changing the received light amount level, the optical means of the light transmittance detecting portion is provided with a comparing means for issuing a command signal for switching the light amount level set value. Powder that is transported by the transport medium in the pipe Flow measuring device. 7. A tube having openings opposed to each other on a line orthogonal to the axis, and light transmission inserted into the openings and projecting so as to oppose each other at a constant tip interval. Measuring tube, a tip interval adjusting device attached to the light transmitting measuring tube, a light source for light beam incidence arranged at the rear end of one measuring tube, and at the rear end of the other measuring tube. A light transmittance detecting section having a light amount detecting end, a detecting end for measuring the flow velocity of the carrier medium, and a powder average concentration and a medium average flow velocity are respectively calculated from their output signals, and these are multiplied to obtain a powder A flow rate measuring device comprising a device for calculating a body flow rate, wherein the light source additional current control device of the light source body receives a detection signal from the light amount level setting circuit and the light transmittance detecting end, and the signal level and range thereof are received. The light intensity level setting circuit compares the A flow measuring device for high-concentration powder conveyed by a conveying medium in a pipe, characterized in that a comparison means for issuing a replacement command signal is provided. 8. A tube having openings opposed to each other on a line orthogonal to the axis, and a light transmitting member inserted into the openings and protruding so as to oppose each other at a constant tip interval. Measuring tube, a tip interval adjusting device attached to the light transmitting measuring tube, a light source for light beam incidence arranged at the rear end of one measuring tube, and at the rear end of the other measuring tube. A light transmittance detecting section having a light amount detecting end, a detecting end for measuring the flow velocity of the carrier medium, and a powder average concentration and a medium average flow velocity are respectively calculated from their output signals, and these are multiplied to obtain a powder A flow measuring device comprising a device for calculating a body flow rate, comprising: a shutter for attenuating at least one light transmission amount; and a moving device for loading and unloading the shutter in an optical path for measurement from the light source body. The signal level of the detection signal received by the light transmittance detection end And a threshold value for comparing with the threshold value and for issuing a command signal for charging and retracting to the moving device, a flow rate measuring device for high-concentration powder conveyed by a conveying medium in a pipe. 9. A tube having openings opposed to each other on a line orthogonal to the axis, and a light transmission member inserted into those openings and projecting so as to oppose each other at a constant tip interval. Measuring tube, a tip interval adjusting device attached to the light transmitting measuring tube, a light source for light beam incidence arranged at the rear end of one measuring tube, and at the rear end of the other measuring tube. A light transmittance detecting section having a light amount detecting end, a detecting end for measuring the flow velocity of the carrier medium, and a powder average concentration and a medium average flow velocity are respectively calculated from their output signals, and these are multiplied to obtain a powder A flow rate measuring device comprising a combination of devices for calculating body flow rate, wherein a plurality of collimating lens devices having different light densities of parallel light fluxes are provided between the light source body and the measuring tube. Device for loading and retracting on the optical axis of Comparing means for receiving the detection signal from the detection end and comparing the signal level with the threshold value and issuing a command signal for loading and retracting to the moving device is provided with a high-conveyance medium in the pipe. Concentrated powder flow rate measuring device.