JPS60192217A - Acoustic mass flowmeter for measuring of gravitationally descending flow - Google Patents

Abstract

PURPOSE:To immediately recognize the occurrence of a non-steady flow, by firmly adhering an acoustic microphone to the outer wall of a transportation pipe for the gravitationally descending flow of a moving layer and obtaining an output passed through a band-pass filter, and then, finding a mass flow rate at a steady flow by calculation. CONSTITUTION:A piezoelectric element microphone 3 is firmly adhered and fixed to the outer wall of a transportation pipe 1 for gravitational descending flow. The output of the microphone 3 is amplified by means of an amplifier 7. Then the amplified output is passed through a band-pass filter 8 for 10-20kHz, band- pass filter in the vicinity of 1kHz and level detector 9, and band-pass filter which passes the peak of non-steady flow spectra and level detector 10. A multiplier 11 inputs signal outputs of the band-pass filters 8 and 9, namely, values proportional to a particle velocity VS and high density rho and outputs rho.VS after operation. An indicator 12 which indicates a mass flow rate G indicates a signal from the filter 10 as a detect signal when a slip phenomenon appears. A mass flow rate regulator 13 compares a measured mass flow rate value with a set value and supplies a valve operating section 6 with its operating output.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention utilizes the fact that the acoustic frequency spectrum emitted by the moving bed powder has a special property when transporting the powder by gravity in a moving bed state. The present invention relates to a device for at all or adjusting the quality and strength of a descending flow.

The emission acoustic characteristics of moving bed powder in gravity downward flow are the first
As shown in the figure, I KHz, 10-20KHz
(1) Peak confession near 1(f).

Among these, the peak (A) in the 10-20 KHz section is caused by collisions between particles, and the generated 7"7 t, t
The 5+ frequency is inversely proportional to the particle diameter, and the frequency sound pressure level P is proportional to the flow 1JVs to the m power (m-1 to 1.2).

Further, the peak (B) near lKH2 is proportional to the number of collisions between the ladles of the powder and granules, and the size of the peak is proportional to the distance ρ between the powder and granules.

The following -1- is the peak value in the case of steady flow, but if sling occurs in the pipe] 00 Hz If (J
A peak with a frequency component as shown by the broken line S (C
) appears, indicating that an unsteady flow is occurring.

The present invention provides an apparatus that can measure and control mass flow rate using six or more generated acoustic characteristics.

FIG. 2 shows the main parts of an apparatus according to an embodiment of the present invention.

High-temperature inorganic adhesive (2) is applied to the outer wall of the gravity descending transport pipe (1).
) to secure the piezoelectric element microphone (3), and secure it with the supplementary presser foot (4). (5) is a control valve provided at the end of the pipe, and (6) is an operating device. (7) is a microphone output intensifier [1], and (8) is a bandpass filter from 10 to 20K) that is used to measure the sound pressure level at the peak (A). <9) detects the sound pressure level of the peak (B) using a bandpass filter near IKH2 and a peak level detector, and measures the height of the peak as a sound pressure level difference. (10) is a bandpass filter that passes the peak (C) of the unsteady flow spectrum and a level detector.

(11) is a multiplier, and the bandpass filter (8) (
8), that is, the particle velocities Vs and Qf, and values proportional to the degree ρ are input to calculate and output ρ·Vs.

When the tube cross-sectional area is A [m'], the mass flow rate is G [kg/
s] can be calculated by 1 as G=-ρ・vS−A.

(12) is an indicator that indicates the mass flow rate G, and when a slip phenomenon occurs, the signal from the filter (10) is displayed as a detection signal.

(+3) A 1-year-old mass intake controller, which compares the measured mass/flow) value with a set value and supplies its operating output to the valve operator (6).

As described above, the present invention realizes a mass flow rate control IB1 device by measuring the mass flow rate in a steady flow using the filters (8) and (9) and by providing a regulator (13) and a control 1'fi valve operator (6). In addition, the condition of the descending moving layer can be constantly monitored using the filter (10), and when an unsteady flow occurs, it can be immediately displayed and an alarm can be issued.

[Brief explanation of drawings]

FIG. 1 is a frequency spectrum diagram of a group of particles moving in a tube, and FIG. 2 is a schematic diagram of the apparatus of the present invention. ('3)...Acoustic microphone (7)...Increase + lJ device

Claims (2)

[Claims] (1) An acoustic microphone is fixed to the outer wall of the moving bed gravity downflow transport pipe, and the microphone output is passed through a bandpass filter with lθ~20KHz and IK)Iz opening to obtain an output proportional to the flow velocity and bulk density. Acoustic gravity downflow mass flow rate with the characteristic 'II+ to calculate the mass flow rate in steady flow by multiplying, 1° (2) An acoustic microphone is fixed to the outer wall of the moving bed gravity downflow transport pipe, and the microphone output is set at 10 to 20K)lz
and IKHz 1 (by passing through a bandpass filter near 41 to obtain an output proportional to the flow velocity and tea + degree of harm and multiplying both, the mass flow 1- in a steady stream is further increased to 100) 1
An acoustic ball force descending flow quality h) flowmeter characterized by detecting the occurrence of an unsteady flow by outputting a peak value signal near z.