JPS63262545A - Method for measuring bulk density of coal - Google Patents

Abstract

PURPOSE:To rapidly and accurately calculate the bulk density of the coal being filled in chamber and the distribution thereof, by irradiating a coal bed with the radioactive rays from the radiation source arranged to the outer wall of the chamber and detecting the radioactive rays transmitted through the coal bed. CONSTITUTION:The radioactive rays emitted from the radiation source 3 arranged in the vicinity of one outer wall of a chamber 1 are allowed to irradiate a coal bed 2 while the transmitted radioactive rays are caught by a detector 4. The scintillator in the detector 4 emits light in a visible region when a ionizing radiation passes therethrough and an electric pulse is inputted to a measuring device 5 through a photomultiplier tube. The intensity I of the radioactive rays after the transmission through the coal bed 2 becomes weak as the bulk density of coal becomes larger and becomes strong as the bulk density of coal becomes smaller. Therefore, when a calibration curve showing the relation between the index showing the intensity or attenuation ratio of the transmitted radioactive rays and the bulk density of coal is preliminarily prepared, the bulk density of coal can be easily calculated on the basis of the measures value by the measuring device 5.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for non-contactly determining the bulk density and distribution of coal packed in a room using radiation.

[Prior art] - It has been pointed out that the quality of coke in a coke oven is affected not only by the coking coal blending conditions and carbonization conditions, but also by the bulk density of the coal charged into the carbonization chamber of the coke oven. Therefore, knowing the bulk density of the coal packed in the carbonization chamber or storage chamber is important for quality control of coke.

For information on how to measure coal bulk density (and its distribution),
There is a report in "Tosha Toyojo 1, Vol. 45, No. 472, pp. 551-552 (1966)".

The method for measuring the bulk density of coal described in this document relates to a method in which coal is charged into a chamber provided with a large number of sampling holes on the side, and the coal is sampled from the sampling holes using a sampler.

That is, first, a cylinder as a sampler is tightly attached to one lid of the sampling hole, the lid is opened, the cylinder is inserted into the chamber, and the cylinder is advanced until it hits the wall on the opposite side.
Next, the lid on the opposite side of the sampling hole is opened, and the piston pushes out the coal sample stuck in the cylinder. The extruded sample is weighed, and the coal bulk density is determined from its weight and sampler volume.

By performing this operation for each sampling hole, it is possible to determine the positional change in bulk density in each part of the room, that is, the coal bulk density distribution in the room.

Problems to be Solved by the Invention However, the method for measuring coal bulk density described in the above-mentioned document had the following problems.

■ Not applicable to low moisture content below 5%.

Low moisture content tends to flow easily, so if the cylinder is tightly attached to the lid of the sampling hole and the lid is removed, a gap may be created and the coal sample may flow out. Furthermore, when pushing out the sample in the cylinder with the piston, the sample rice may get into the gap between the inner wall of the cylinder and the piston, making piston movement impossible.

■ Powdered coal is sampled in a compressed state.

Since the cylinder is pushed into the coal seam filling the chamber, there is a risk that the tip of the cylinder may compress the coal. Compression of coal leads to bulk density measurement errors.

■ Cannot be applied when molten coal is mixed with powdered coal.

If the coal contains briquettes, the advance of the cylinder may be blocked by the briquettes with large particle sizes, or the briquettes may compress the powdered coal as in case (2).

■ There are restrictions on multi-point measurements.

Naturally, with this method, the bulk density can only be measured at locations where there are sampling holes. In order to increase the reliability of bulk density distribution measurement, it is necessary to increase the number of sampling holes as much as possible.
There are limits to the reliability of measurements, both in terms of the strength of the chamber and the amount of time required for sampling.

■ Measurement requires a lot of man-hours and time.

Since a cylinder is inserted into each of a large number of sampling holes to perform sampling and measure the weight of the sample, the measurement requires a large amount of man-hours and time. Furthermore, it is difficult to automate the measurement.

■ Equipment costs are high.

Since a sampling hole is provided in the chamber and a special sampling device is required, the equipment cost for bulk density measurement increases.

The present invention aims to provide an advantageous method capable of quickly and accurately determining the bulk density of coal packed in a chamber and its distribution without using the sampling method which has various disadvantages as described above. It is.

Means for Solving the Problems The coal bulk density measuring method of the present invention involves arranging a radiation source for radiation irradiation on the outer wall of a chamber filled with coal, and arranging a radiation source on the outer wall on the opposite side. The method is characterized in that a detector is placed at a location where the coal is exposed, and the one-coal density is determined based on the information obtained when the detector captures the radiation emitted from the radiation source and transmitted through the coal seam.

Measurement methods using radiation are applied to inspect or measure plate thickness, internal defects, internal stress, material composition and structure, etc., but it is still unknown to use radiation to determine the bulk density of coal. I believe that this is a technology that has not been developed yet.

The present invention will be explained in detail below.

In the present invention, coal is filled in a chamber and subjected to measurement. Examples of the chamber include a carbonization chamber, a model carbonization chamber, a storage room, a hopper, a container, and other rooms of arbitrary size.

The material of the chamber is not particularly limited as long as it transmits radiation, such as metal (such as iron), wood, or refractory material.

Radiation sources include those using radioactive isotopes and electrical generators. In particular, 1. Those that emit gamma rays,
For example, it is preferable to use Ra, Co, 137Cs, etc. as a radiation source.

The source is handled in a source storage container made of lead, for example.

The radiation source is placed on the outer wall of the chamber filled with coal, while the detector is placed at a corresponding location on the opposite outer wall.

The radiation emitted from the radiation source and transmitted through the coal seam is captured by a detector, and by measuring the information at this time, such as the intensity or attenuation ratio of the radiation after passing through, the target coal bulk density can be determined. Desired.

By sequentially moving the radiation source and detector along the outer wall of the chamber and making measurements using appropriate means, the coal bulk density distribution within the chamber can be easily determined.

FIG. 1 is an explanatory diagram schematically showing an example of a measuring device used in the method of the present invention.

(1) is a chamber filled with coal (2). (1
a) is one outer wall of the chamber (1), and (1b) is the other outer wall.

(3) is a radiation source placed near one outer wall of the chamber (1), and (4) is a detector placed on the other outer wall (lb) of the chamber (1).

(5) is a measuring instrument, and (6) is a microcomputer.

The moving mechanisms for the radiation source (3) and the detector (4) are not shown.

The measurement accuracy and measurement time can be appropriately set by selecting the intensity of the radiation source.

When acting radiation passes through a substance, it is attenuated at a fixed rate determined by the energy of the radiation and the atomic number and density of the substance. When this constant ratio is expressed in terms of mass absorption coefficient, the following formula generally holds true.

I=Io B*exp (-p-psy ・p
・ t) ■ = Intensity of radiation after passing through the material IO: Intensity of radiation before passing through the material B: Reproduction coefficient R: Mass absorption coefficient (cm/g) ρ: Density of the material (g/Cm') t : Radiation transmission distance (cm) t becomes constant once the measurement position is determined. JL and B are determined by creating a calibration curve using known densities and counts during measurement.

Therefore, the intensity of the radiation after transmission or its attenuation ratio (Io
By measuring -I)/IO, the density ρ of the substance can be determined.

In the measuring device shown in FIG. 1, the radiation emitted from the radiation source (3) is detected by the detector (4) after the radiation passes through the radiation source. When ionizing radiation passes through the scintillator inside the detector (3), a part of the energy given by ionization or excitation is not turned into energy of thermal motion, but is converted into emission of light in the visible region. Since the light is weak, a photomultiplier tube equipped with a photocathode converts the light into photoelectrons, which is then amplified in multiple stages between electrodes to turn it into a large electrical pulse, which is then measured by a measuring instrument (5). be done.

The intensity of radiation after passing through the coal (2) layer is weaker as the bulk density of the coal increases, and stronger as the bulk density of the coal is lower. The damping ratio (Io-I)/Io increases as the coal bulk density increases, and decreases as the coal bulk density decreases.

Therefore, if a calibration curve showing the relationship between the intensity or attenuation ratio of the transmitted radiation (for example, the transmission count value) and the coal bulk density is created in advance, it is easy to calculate the The bulk density of the coal can be determined.

Furthermore, by changing the position of the radiation source (3) and the position of the detector (4), the bulk density of coal in the room at that position can be determined, making it easy to understand the distribution of bulk density of coal in the entire room. Can be done.

Example Next, the present invention will be further explained with reference to Examples.

Example 1 Coal with a moisture content of 8.4% and an average particle size of 1.8 mm was charged from a hopper to a height of about 4000 mm into a model carbonization chamber made of iron with a height of 400 mm in the mountains between the walls, and then the top surface of the charged coal was Evened out.

Using the apparatus shown in FIG. 1, coal bulk density was measured under the following conditions.

Radiation source: '37C3, loogCi measurement time: 3
m1n Bulk density accuracy: 5X 10 g/cm3 A calibration curve was created by plotting the γ-ray transmission count value at this time and the coal bulk density determined in advance by the sampling method. FIG. 2 shows this calibration curve (curve A).

From FIG. 2, it is clear that the bulk density can be determined immediately by measuring the gamma ray transmission count value.

Example 2 A calibration curve was created by carrying out the same experiment as in Example 1, except that coal with a moisture content of 3.8% and an average particle size of 1.8 mm was used.

FIG. 2 shows this calibration curve (curve 1NIB).

From the $2 diagram, it can be seen that the bulk density can be immediately determined by measuring the γ-ray transmission count value.

Example 3 Moisture content in the model carbonization chamber: 8.4%, average particle size: 1.8 mm
Molded coal (diameter 35
mm) was increased sequentially from 1 piece → 2 pieces → 3 pieces, and the gamma ray transmission count value was measured.

As shown in FIG. 3, the bulk density determined from the γ-ray transmission count value (indicated by white circles) and the calculated value (indicated by black circles) were in good agreement.

The results shown in FIG. 3 show that measurement according to the present invention is possible even when briquette coal is present.

Example 4 The same experiment as in Example 1 was conducted except that coal with a moisture content of 8.4% and an average particle size of 1.8 mm was blended with 10%, 15%, and 30% briquette coal, respectively. However, since the briquettes are not uniformly distributed, the measured values differed depending on whether or not the briquettes were on the measurement gamma ray. By increasing the number of measurement points,
The distribution of briquette coal was clarified.

Effects of the Invention According to the present invention, the following excellent effects can be achieved.

Technique 2 The bulk density of coal and its distribution can be known accurately and quickly. The reliability of the measured values is also high. Therefore, coke quality management becomes easy and contributes to improvement of coke quality.

Since it is a non-contact measurement method, the troubles associated with mechanical sampling in conventional sampling methods are completely eliminated.

Even if the water content is as low as 5% or less, the bulk density can be measured without any problems.

If briquette coal is mixed in, its distribution will be known.

The bulk density of the coal filled in the chamber can be measured at any location.

By automating the movement of the radiation source and detector and processing the measured values with a microcomputer, the indoor coal bulk density distribution can be automatically output.

The number of man-hours and costs required for measurement are reduced, which is advantageous in terms of labor savings and measurement costs.

The cost of the equipment is also rather low because there is no need to provide a special chamber or sampling means unlike in conventional sampling methods.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram schematically showing an example of a measuring device used in the method of the present invention. FIG. 2 is a calibration curve created by plotting the γ-ray transmission count value and the coal bulk density determined in advance by a sampling method. FIG. 3 is a graph showing the relationship between the number of briquettes and bulk density when briquettes are mixed. (1) ...room, (la)--outer wall, (lb)...
Outer wall, (2)...coal, (3)...ray source, (4)...
...Detector, (5)...Measuring instrument, (6)...Microcomputer - Patent applicant Kansai Thermal Chemical Co., Ltd. Patent applicant Nondestructive Testing Co., Ltd. Figure 1 Figure 2

Claims (1)

[Claims] 1. A radiation source for radiation irradiation is placed on the outer wall of the chamber filled with coal, and a detector is placed on the corresponding part of the outer wall on the opposite side. A coal bulk density measuring method characterized by determining the coal bulk density based on information obtained when radiation emitted from the coal seam and transmitted through the coal seam is captured by a detector. 2. The measuring method according to claim 1, wherein the information is the intensity or attenuation ratio of the radiation after passing through it. 3. The measuring method according to claim 1, characterized in that the bulk density at various positions is determined by sequentially moving the radiation source and the detector, thereby determining the coal bulk density distribution in the room.