JPH06129980A - Water content measuring device using micro wave for powder and granulate - Google Patents

Abstract

PURPOSE:To precisely measure water content percentage of powder and granulate transported by a belt conveyor. CONSTITUTION:A conveyor line is provided with a moisture meter 3 of a micro wave method, a range finder 4 that measures layer thickness of powder and granulate 1, and a weighing equipment 5. The data obtained by the moisture meter 3 is applied with the correction based on the layer thickness of the powder and granulate 1, and with that based upon the concentration of the powder and granulate 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave granular material for continuously measuring the water content of a granular material such as coal transported by a belt conveyor in a conveyor line using a microwave. The present invention relates to a moisture measuring device.

[0002]

2. Description of the Related Art There is a technique utilizing microwave as a technique for continuously measuring the moisture content of powdery or granular material in a non-contact manner. This is a method of irradiating a microwave on a granular material and measuring the moisture content of the granular material from changes in the propagation characteristics of the microwave in the granular material. Japanese Patent Laid-Open No. 59-203946 and the like, and a method utilizing a phase change of microwaves are known.
No. 102146 is disclosed.

However, in all of these moisture measuring techniques, the moisture content rate is evaluated on the assumption that the volume of the powdery or granular material is constant. Therefore, when a powder or granular material whose layer thickness changes, such as coal transported by a belt conveyor, an error occurs due to the change in the layer thickness, and accurate measurement cannot be performed.

In order to solve this problem, measures have been taken to smooth the surface of the powdery particles on the belt conveyor by using a scraper. In addition, in the moisture absorption method of the infrared absorption method, which is not by microwave, a measure for measuring the distance from the moisture meter to the granular material and correcting the distance is disclosed in JP-A-62-12838. It is disclosed.

[0005]

The countermeasure using the scraper is to eliminate the error due to the change of the layer thickness by keeping the layer thickness of the powder particles on the belt conveyor constant. However, according to the research conducted by the present inventors, it has been found that in the moisture measurement by microwaves, a complete correction cannot be achieved only by keeping the layer thickness constant.

Further, in this measure, since the powder or granules are cut out from the hopper or the like, the layer thickness varies greatly, and the powder or granules may pass under the scraper. In that case, the layer thickness is not constant, and correction becomes completely impossible. Further, the scraper causes the particles to bounce off, which causes a problem that the particles fall from the belt.

On the other hand, in the case of measuring the distance from the moisture meter to the granular material, even if it is applied to the moisture measurement by the microwave, only the change of the layer thickness is required at most, and the correction by the layer thickness is incomplete. It is as described above.

An object of the present invention is to use a microwave capable of highly accurately measuring the water content of a powder or granular material that is transported by a belt conveyor while changing the volume, and that does not cause the powder or granular material to fall off from the belt conveyor. An object of the present invention is to provide a moisture measuring device for powders.

[0009]

SUMMARY OF THE INVENTION A microwave moisture measuring apparatus for powder and granular materials according to the present invention includes a moisture meter for irradiating microwaves on powder and granular materials transported by a belt conveyor to measure the moisture content thereof. A measurement system provided on a conveyor line in proximity to a moisture meter to measure the layer thickness and weight of the powder and granular material, and the layer thickness of the powder and granular material measured by the measurement system,
A correction system that corrects the measured value of the water content based on the bulk density of the powder and granules obtained from the layer thickness and the weight.

[0010]

In the powdery or granular material, water is contained mainly in the form in which water is attached to the surface of each particle. Therefore, even if the water content is the same, the amount of water in the same volume changes due to the increase or decrease of the bulk density, and the water content cannot be measured correctly.

In the moisture measuring apparatus for powdery or granular material according to the present invention, the moisture content is measured with high accuracy because the measurement value of the moisture meter is corrected by the layer thickness and the bulk density.

The bulk density of the powder or granular material is also measured by radiation, but radiation has a problem in handling.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing one configuration of the moisture measuring device of the present invention.

The present moisture measuring apparatus is installed on a conveyor line for continuously or intermittently transporting coal as powdery or granular material 1 by a belt conveyor 2, and a moisture meter 3, a distance meter 4, a weighing machine 5 and a calculator 6 are installed. Is configured.

The moisture meter 3 has a transmitting antenna 3a and a receiving antenna 3b provided above and below the conveyor line.
These are connected to the main body unit 3c by a waveguide cable.

The transmitting antenna 3a irradiates the powdery or granular material 1 on the belt conveyor 2 with microwaves. The microwave radiated to the granular material 1 passes through the granular material 1 and the receiving antenna 3
caught by b. The main body unit 3c measures the water content of the granular material 1 from the phase difference and energy difference between the transmitted wave and the received wave, and supplies the measured data to the computer 6.

The distance meter 4 is provided on the conveyor line near the moisture meter 3 and irradiates the granular material 1 on the belt conveyor 2 with ultrasonic waves or the like to measure the distance from the distance meter 4 to the granular material 1. Is measured without contact. The measurement data is input to the calculator 6 and converted into the layer thickness of the powdery or granular material 1 by the calculator 6.

The weighing machine 5 measures the weight of the powdery or granular material 1 on the belt conveyor 2 just below the distance meter 4. The measurement data is input to the computer 6 together with other measurement data. Note that the tracking information of the granular material 1 obtained by the pulse generator 7 is given to the computer 6 in order to make each measurement data correspond to the measurement location of the granular material 1.

The calculator 6 stores two types of correction tables for the moisture content measured by the moisture meter 3 for each brand of coal (grain size) which is the granular material 1. The first correction table is based on the layer thickness of the granular material 1, and the second correction table is based on the bulk density of the granular material 1.

When the measurement is started, the computer 6 compares the layer thickness of the powdery or granular material 1 with the first correction table to obtain the first correction value, and also calculates the bulk density from the layer thickness and the weight. Then, the second correction value is obtained by collating this with the second correction table. Then, these corrections are added to the water content rate measured by the water content meter 3, and this is output as the water content rate of the granular material 1.

FIG. 2 shows the moisture content (%) and the layer thickness (mm) of coals of the same brand with a constant moisture content measured by a microwave moisture meter. It is a graph which shows a relationship. Even if the actual water content of coal is constant, the output of the water content meter changes when the layer thickness is different. The computer 6 performs this correction using the first correction table.

Further, FIG. 3 shows the moisture output (%) and the bulk density (kg) of coal of the same brand with a constant moisture content, when the moisture content is measured by a microwave moisture meter. It is a graph which shows a relationship. The output of the moisture meter also changes with changes in bulk density. The computer 6 performs this correction using the second correction table.

By these two corrections, the moisture content of the granular material can be accurately measured.

FIG. 4 is a graph showing the relationship between the measured water content (%) of coal and the analyzed water content (%) for each particle size. The moisture content measured by the microwave moisture meter is also influenced by the particle size. The correction table for the measured value of the water content is stored for each brand of coal (by grain size) and used properly in order to eliminate the influence of this grain size.

[0025]

As is apparent from the above description, since the moisture measuring apparatus for powder and granular material of the present invention corrects the measured value of the moisture meter by the layer thickness and bulk density of the powder and granular material, The measurement can be performed with higher accuracy than when the layer thickness is made constant with a scraper. Further, in the case where the layer thickness is made constant with a scraper, measurement becomes impossible when the layer thickness is thin, but the moisture measuring apparatus of the present invention does not have such a concern. Furthermore,
There is no concern that the powder or granules will fall off the belt conveyor, and there is no hindrance to the transportation of the powder or granules. Furthermore, since the bulk density is measured from the layer thickness and the weight, there is no anxiety about the human body or the like, which is a problem in measurement by radiation.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a moisture measuring apparatus showing an embodiment of the present invention.

FIG. 2 is a graph showing the influence of layer thickness on the output of a moisture meter.

FIG. 3 is a graph showing the effect of bulk density on the output of a moisture meter.

FIG. 4 is a graph showing the relationship between measured water content and analyzed water content by particle size.

[Explanation of symbols]

 1 Powder and Granules 2 Belt Conveyor 3 Moisture Meter 4 Distance Meter for Obtaining Layer Thickness 5 Weighing Machine 6 Calculator

Claims (1)

[Claims] 1. A moisture meter for irradiating microwaves on a powder or granular material transported by a belt conveyor to measure the moisture content thereof, and a moisture meter close to the moisture meter for measuring the layer thickness and weight of the powder or granular material. The measurement of the water content based on the measurement system provided on the conveyor line, the layer thickness of the granular material measured by the measurement system, and the bulk density of the granular material obtained from the layer thickness and weight. A moisture measuring device for powdery or granular material by microwave, comprising: a correction system for correcting the value.