JPH049617A - Method for measuring flow rate of granular substance - Google Patents

Abstract

PURPOSE:To stably measure the pneumatic transportation rate of granular substance with good accuracy by determining the flow rate of the granular substance in accordance with the detected intensity of acoustic emission and the correlation therewith. CONSTITUTION:The granular substance is pneumatically transported in a piping 1 and a sensor 2 for detecting the acoustic emission is provided in this piping 1. The detection signal of the sensor 2 is inputted to a signal processor 3. The intensity of the acoustic emission detected by the sensor 2 increases with an increase in the flow rate of the granular substance and, therefore, the flow rate of the granular substance is measured in accordance with the detected value of the sensor 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a powder/granular material flow rate measuring device that is suitably employed in detecting a coal flow rate when coal particles are conveyed by air flow.

[Prior Art] For example, when supplying coal particles to a fluidized bed combustion apparatus, the coal particles are often conveyed by air flow. Further, such air flow conveyance of powder and granular materials is employed in various other industrial machinery devices.

Methods for detecting the flow rate of powder and granular material carried by air current include: (1) Measuring the temperature of the wall of the pipe through which powder and granular material is carried by air current. (When flowing high-temperature gas as a gas for airflow conveyance, if a blockage occurs in the pipe, the gas flow rate decreases and the pipe wall temperature decreases.

Therefore, by measuring this tube wall temperature, the flow rate of the granular material can be indirectly measured. ) ■ Measure the pressure difference at two locations separated in the flow direction in a pipe where powder and granules are conveyed by air current.

■ A laser light-emitting element and a light-receiving element are arranged so as to cross the flow direction in a pipe in which powder and granular material is conveyed by air current, and the powder and granular material passes between the light-emitting element and the light-receiving element. The conveyance amount is measured from changes in the amount of received light.

Methods such as these are used.

[Problems to be Solved by the Invention] In the method of estimating the flow rate of powder or granular material by measuring the pipe wall temperature as in (2) above, unless the inside of the pipe is substantially clogged, there is no noticeable temperature in the pipe wall temperature. No changes occur, and it is impossible to accurately determine the flow rate.

(Actually, it can only be used to detect blockages in pipes.) In method (2), the nozzle for pressure measurement is likely to be blocked by powder. Furthermore, if the piping for airflow conveying the powder or granular material is installed horizontally, the pressure difference may be so small that measurement may be virtually impossible.

In the method (2) using a laser, there is a limit to the particle size of the powder that can be used, and measurement accuracy is significantly reduced due to dirt on the light-emitting and light-receiving surfaces of the light-emitting element and light-receiving element.

There were other problems.

[Means for Solving the Problems] The force method for measuring the flow rate of powder or granular material of the present invention is a method for measuring the flow rate of powder or granular material that is air-flow conveyed in a pipe, and includes the steps of: installing an acoustic emission detection sensor in the pipe; The present invention is characterized in that the flow rate of the powder or granular material is detected based on the detected value of acoustic emission.

[Operation] When particles are air-flow conveyed in a pipe, vibrations and sound waves are generated by the particles colliding with the inner surface of the pipe. In the present invention, the intensity of this vibration and acoustic energy is detected by an acoustic emission detection sensor.

Since the vibrations and acoustic energy generated change in response to changes in the flow rate of the powder, the flow rate of the powder flowing through the piping can be measured each time this intensity is measured. In addition, to specifically measure the flow rate, prior to measurement, the intensity of the acoustic emission generated by varying the flow rate of the same powder or granule as the one actually flowing through the pipe is determined. Find the correlation between flow rate and acoustic emission intensity. When actually detecting the flow rate of the powder or granular material, the flow rate of the powder or granular material is determined based on the detected acoustic emission intensity and the correlation.

[Example] Examples will be described below.

FIG. 1 is a schematic diagram showing the state in which the method of the present invention is being carried out. Powder and granular material is conveyed by air flow in a pipe 1, and a sensor 2 for detecting acoustic emission is provided in this pipe 1. The detection signal of this sensor 2 is input to a signal processing device 3. As the flow rate of the granular material increases, the intensity of the acoustic emission detected by the sensor 2 increases, so the flow rate of the granular material is measured based on the detected value of the sensor 2. Specific examples will be described below.

Example 1 Coal crushed to have a particle size of 6 rnrn to 100 μm was air conveyed. The main conditions are as follows.

Inner diameter of pipe 1 4.31cm Air flow range 1.50~5ONrr? /h Coal/Air ratio 1.39kg-Coal/Ntr? - Air Figure 2 is a diagram of changes in the intensity of acoustic emissions when the air flow rate is gradually increased, and from the N2 diagram, there is a relationship between the amount of coal airflow conveyed and the intensity of acoustic emissions as shown in Figure 3. It was recognized that there was a correlation.

The correlation diagram shown in FIG. 3 was inputted into a microcomputer in a signal processing device, and was incorporated into a coal supply line to a fluidized bed boiler to measure the amount of coal air flow conveyed. The coal flow rate calculated from the amount of coal input from the coal bunker and the airflow transport amount calculated from the acoustic emissions agreed with high accuracy.

[Moving Bed] As is clear from the above examples, according to the measuring method of the present invention, the amount of airflow conveyance of powder and granules can be measured accurately and stably. The method of the present invention can be applied regardless of the type or particle size of the powder or granular material. For example, if the amount of air flow conveyed is measured according to the method of the present invention in a large number of air flow conveyance pipes branching from a coal splitter, etc., the amount of powder or granular material transported in each pipe can be accurately detected, and based on this It is also possible to control the flow rate in each pipe individually.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the method of the embodiment, FIG. 2 is a three-signal diagram, and FIG. 3 is a correlation diagram. 1... Piping, 2... Sents for acoustic emission pressure detection, 3... Signal processing device. Patent Applicant Ube Industries Co., Ltd. Agent Patent Attorney Tsuyoshi Shigeno↑ Suspension of Supply 1- Sen 1;〕(,I)”17.N

Claims (1)

[Claims] A method for measuring the flow rate of powder or granular material being carried by airflow in a pipe, characterized in that an acoustic emission detection sensor is provided in the pipe, and the flow rate of the powder or granular material is detected based on the detected value of the acoustic emission. A method for measuring the flow rate of powder and granular materials.