JPS6091213A - Method for measuring flow rate of solid in vertical pipe - Google Patents

Abstract

PURPOSE:To shorten the measuring time of a flowmeter, by providing a plurality of acoustic detectors on the outer wall of a vertical pipe, and statistically smoothing the number of collision times between particles caused by the differences in particle size distribution and in flow speed distribution of high concentration descending bulk material. CONSTITUTION:A solid-state flow-rate measuring apparatus is composed of a pressurizing tank 1 having a fluid bed 2, a pressurizing gas source 3, a distributing discharge pipe 4, a valve 5, a descending transport pipe 6, a horizontal part 8, a tuyere nozzle 9, a carrier-gas blowing and controlling device 11, and the like. Two acoustic detectors 13a and 13b are provided at symmetrical positions on an outer wall 14 of the descending pipe 6 by attaching bodies 15. An octave filter 16, an average measured value computing circuit 17, and a regulator 18 are provided. The central frequency is set at 1kHz-8kHz. Then, the difference in detected output due to the difference in particle size distribution at the cross section of the pipe is averaged. Therefore the measurement for the length twice the conventional length can be performed in the same time period. Thus the measuring time of the flow rate can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for accurately measuring solid ill when transporting powder or granular material to a high-temperature, high-pressure furnace or the like by means of downward gravitational waves.

When stably transporting pulverized coal or the like at a high solid-air ratio to the high-pressure supply end, one-gravity downward flow is more advantageous than horizontal pipe transport in order to increase the mass flow rate ratio.

The device shown in Fig. 1 (Patent No. 117
58-94119) has been proposed.

Although an effective means of measuring the mass flow rate in a vertical transport pipe has not yet been established in such a device, the inventors have developed a method to measure particle noise inside the pipe outside the pipe, as explained below. It has been found that the solid flow rate in a pipe can be measured by detecting with an acoustic or vibration detector and using the signal output of a specific frequency band among the detection outputs.

In other words, when solid particles (powder) flow through a transport pipe, collision and friction sounds are generated (particle sound), and these generated sounds (noise), that is, the noise caused by the statistical number of collisions, are caused by the particle flow velocity. It is already known that the concentration is proportional to the concentration. (Japanese Patent Publication No. 52-20869) However, in the case of a non-porous type where the detector is installed outside the pipe, the detected noise contains various frequency components.
Therefore, it was said that identification was difficult due to the influence of background noise (ambient noise) at the measurement location.

As a result of various experiments, the present inventors have found that by setting the measurement range to a frequency range of 1 kHz or higher, the influence of background noise can be reduced even with a non-porous type, and that it is not affected by the material of the transport pipe. It was confirmed that the solid flow rate could be measured simply by fixing the sound detector to the wall surface instead of penetrating the transport pipe wall as in the conventional method.

The present invention provides a method that allows the above measurement method to be implemented with even higher precision.

The invention will now be described with reference to FIG.

(1) is a pressurized tank for transporting powder and granular materials, and (2) is a fluidized bed, to which gas is supplied from a pressurized gas source (3). (
4) are distribution and discharge pipes opening into the side walls of the tank, each connected to a descending transport pipe (6) via a valve (5). (
7) is a bent part, (8) is a horizontal part or an inclined part, and (8) is a tuyere nozzle, which is opened at the supply end (10) of a high-temperature, high-pressure gasification furnace, high-pressure gold IA reduction furnace, etc. (11) is an intermittent flow generator or other gas blowing control device for axial transport, in which the quality of the granular material λ flow section is adjusted by the transport gas valve (12).

The density of the powder in the downcomer (6) is maintained at a high solid-air ratio comparable to that of the moving bed, and is slowly descending.

(13a) (+3b) is the outer surface of the wall of the downcomer pipe (6) (
14) A plurality of microphones or acoustic or vibration detectors such as vibration pickups are fixed to the mounting body (15) covered with putty or other suitable backing sealing material, the output of which is supplied to an octave filter (16). Ru.

(17) is a measurement average value calculation circuit, which is configured to calculate the weighted average of the number of detections to obtain the average solid flow velocity, and adjust the set value of the controller (1 day) based on this output. .

Next, the present invention will be explained along with an example of ¥5. In the equipment shown in Figure 1, open the bent part (7) and cut the vertical part of the transport pipe with a diameter of 50 mm.
mII+ stainless steel tube, ABS as powder material material
The relationship between the particle sphericity Vs when a resin pellet (2 mm φ x 2 mm L) is dropped and the noise level (microphone output) at each frequency is approximately linear as shown in FIG.

Furthermore, when the particle flow velocity Vs is, for example, 5.8 cm/see, the noise levels of the particle sound and background noise at the center frequency of the octave filter are as shown in FIG.

(Number of detections: 1 time/sec, average value of 10 times).

From the above, it is clear that the center frequency used in the present invention is less than 1 kHz, and that the noise level relative to the flow velocity is not easily affected by the material of the transport pipe at 1 kHz or less, and that the signal-to-noise ratio is A frequency range of about 1 kHz to about 8 kHz is adopted because it can be made at high frequencies.

Therefore, for example, by setting the center frequency to 8 kHz, measuring the relationship between the average particle flow velocity and the noise level in the applicable equipment in advance, and detecting the noise level at the same frequency when the equipment is operating, it is possible to detect hands and crabs in the transport pipe. The mass of the downflow is C
The quantity is measured, and the amount of supply to the supply end at that time is obtained.

Therefore, this output enables the liF and fi controllers to be operated to control the supply amount to a constant value.

In the above measurement method, if the object to be transported, that is, the powder or granular material, is relatively uniform in shape, properties, etc., such as a pellet, the relationship between the flow velocity and the noise level is stable, so the detector 1
However, in the case of fine powder beds and other powder materials containing fine powder, the relationship between flow velocity and noise level fluctuates due to statistical fluctuation phenomena, so if there is only one detector, the actual It was necessary to calculate the moving average of the data for about 10 seconds.

For example, when measuring a descending flow with a maximum speed of 10 cm/s, if the lower limit is 10%, the speed is I cm/s, and the average value of IQ cm/s measured for 10 seconds (10 times) is the descending flow in a pipe of 1 m. means the average noise level. Therefore I
cm/s, it takes 100 seconds to make the average error similar.

By the way, the number of collisions of powder and granular materials, which are noise sources, is a probability distribution function that occurs irregularly with respect to time, and it is mathematically It is possible to statistically smooth out the noise detection level by separating the detection points and measuring them at the same time using ergodicity.

Therefore, the present invention fixes the multiple image detectors in different locations. In this case, if the detectors (13a) and (13b) are installed symmetrically on the cross section of the pipe as shown in Figure 4, or if they are installed several times at regular intervals (L) in the pipe axis direction as shown in Figure 5. There is.

In the case of Figure 4, the difference in detection output due to the difference in particle size distribution in the cross section of the tube is averaged out, and it becomes equivalent to measuring twice the length in the same time, so it is possible to make the measurement time almost the same. be.

In the case of Fig. 5, for example, the downward flow velocity is 10 cm/s ~
At 1 cm/s, the measurement time is 10 seconds, and it is equivalent to measuring a moving range of 10 cm separately, so the average of this is 200 cn + ~ 20 cm.
is equal to the average (11'1), and as a result, the overall result is equivalent to a spatial filter that uses the measurement time as a station.

In the present invention, the number of detectors is not limited to two, and a combination of the configurations shown in FIGS. 4 and 5, that is, four detectors, or a pair of cross-sections, three in the tube axis direction, and a total of six detectors is also possible.

In short, the present invention aims to shorten measurement time by statistically smoothing out interparticle collisions caused by differences in particle size distribution and flow velocity distribution of high-concentration, downward-flowing powder and granular materials. Therefore, it can be easily realized by simply installing multiple detectors with the same characteristics.

[Brief explanation of the drawing]

1st [;? 1 is a schematic configuration diagram of the device of the great invention, FIG. 2 is a graph of particle velocity and noise level, FIG. 3 is a comparison graph of particle sound level and background noise level, and FIGS. 4 and 511 are the detector's (+3a) (13)
b)...Acoustic or vibration detector (16)...; Bar range or octave filter Patent applicant: 1 Figure 22

Claims (1)

[Claims] 8I acoustic or vibration detectors are fixed at different positions on the outer wall surface of the pipe in which the granular solids descend at a mass flow rate similar to that of the moving bed, and the output signals from the detectors are used to calculate the particle flow rate. 9-Measurement method of solid flow in a pipe, characterized in that the spatial deviation of the distribution is reduced and the time average value is calculated.