JPH10221274A - Measuring device for powder quantity in container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure an accurate powder quantity by determining the powder quantity in a container based on the powder density and powder height obtained by a γ-ray detector for measuring the powder density and powder height. SOLUTION: A γ-ray radiating device 2 is provided outside of a container 1, the intensity of the γ-rays transmitting the powder 3 in the container 1 is measured with a density measuring detector 4 constituted of a scintillation detector, and the powder density is calculated. The powder height is measured with a height detector 5 provided at a position facing the γ-ray radiating device 2 across the upper end face 6 of the powder 3. Since the height measurement is affected by the density change of the powder 3, the density data obtained by the density measuring detector 4 are used, and the accurate powder height is obtained even if the apparent density of the powder 3 is changed according to the stirring level of the powder 3. The powder quantity in the container 1 is obtained by an arithmetic unit 7 based on the powder height and powder density data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an apparatus for measuring the amount of powder in a container. More specifically, the present invention relates to a device for measuring the amount of powder in a container such as a reactor or a reaction tank.

[0002]

2. Description of the Related Art In a chemical plant or the like, the amount of powder in a container such as a reactor or a reaction tank is adjusted.
For example, in the gas phase polymerization method of olefin, olefin polymerization is continuously performed while maintaining the fluidized bed height of a gas phase polymerization reactor (fluidized bed reactor) almost constant. Specifically, the solid catalyst and the generated solid polymer are kept in a fluidized state by a gas flow of a gaseous olefin or the like as a raw material while supplying the raw material into an apparatus having a dispersion plate at the bottom of the reactor. Thus, a fluidized bed of the powder is formed, and the polymerization reaction is performed.

When a polymerization reaction is carried out using such a fluidized bed, particularly, in order to stably produce a homogeneous olefin polymer by continuously performing the olefin polymerization reaction, it is necessary to form the olefin polymer in the fluidized bed. It is necessary to keep the residence time of the polymer particles constant, and to keep the height of the fluidized bed of the produced polymer as constant as possible while extracting the powder from the fluidized bed and simultaneously supplying the raw materials and conducting the polymerization. There is.

By the way, the height of the fluidized bed of powder, that is, the upper end surface (fluidized bed powder surface) of the fluidized bed is usually in a wave state (a state where the surface is flowing in a wavy shape) and is outside the polymerization apparatus. As a method of accurately grasping the height of the fluidized bed, a method of measuring the pressure difference between a point in the fluidized bed and the space above the fluidized bed, and based on this pressure difference, It is known to know the height. (Tokuhei 3-32562
No.)

[0005]

However, in this method, when the polymerization is carried out in a stable state, the height of the fluidized bed can be accurately grasped. There is a problem that it is difficult to accurately grasp the height of the fluidized bed under conditions where the change occurs. In addition, in the case of this differential pressure measuring method, the polymer powder is easily clogged with the polymer powder in the differential pressure measuring nozzle, and it is necessary to frequently purge the inside of the nozzle, and the operation is complicated. Further, according to this method, the density of the produced polymer powder cannot be measured, and the amount of the polymer powder in the reactor cannot be accurately grasped.

An object of the present invention is to provide an apparatus capable of accurately measuring the height of the powder surface in a container such as a reactor or a tank as described above, and also accurately measuring the amount of powder in the container. It is intended to do so. The gist of the present invention is a container containing powder, a γ-ray irradiator provided outside the container, and a powder density measurement provided at a position opposed to the γ-ray irradiator with the powder in the container interposed therebetween. γ-ray detector, γ-ray irradiator and γ-ray detector for powder height measurement provided at a position facing the upper end surface of the powder in the container, powder density obtained from both detectors The present invention resides in an apparatus for measuring the amount of powder in a container, comprising a means for calculating the amount of powder in the container from the height of the powder. Hereinafter, the present invention will be described in detail. The apparatus for measuring the amount of powder in a container according to the present invention comprises a powder density measuring means using γ-rays and a powder height measuring means using γ-rays.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an example of the apparatus of the present invention will be described with reference to the drawings. FIG. 1 is a schematic explanatory view of an example of the device of the present invention. As shown in FIG.
A line irradiation device 2 is provided, the intensity of γ-rays transmitted through the powder 3 in the container is measured by a density measuring detector 4 including a scintillation detector, and the powder density is calculated by the following equation [1]. That is, when γ-rays irradiated from the outside of the container 1 pass through the powder having the density ρ, the mass attenuation coefficient μm, and the thickness L, the transmitted γ-ray intensity is represented by the following equation [1].

[0008]

(Equation 1)

Here, I ₀ is the γ-ray intensity without powder (measured in advance without powder). Powder thickness L
(The distance that the line connecting the γ-ray irradiator and the γ-ray detector for measuring powder density crosses the powder. If both devices are provided across the maximum diameter portion of the container, it is equal to the inner diameter of the container.) Is constant, the transmitted γ-ray intensity is a function of the density ρ if the mass attenuation coefficient μm is constant. That is, ρ (density) is obtained by measuring I.

As shown in FIG. 1, the powder height is measured by γ-ray irradiation from the outside of the container 1 using a γ-ray irradiator 2, and the upper surface of the powder is measured by the γ-ray irradiator 2. The height of the powder is measured by a height detector 5 provided at a position opposed to across the powder 6. Since the height measurement is affected by a change in the density of the content (powder), if the density data obtained by the above-described detector 4 is used as the density data, the powder can be checked according to the degree to which the powder is agitated. Even if the hanging density changes, an accurate powder height can be obtained.

The powder height and the powder density are obtained, and the amount of the powder in the container is obtained by the arithmetic processing means 7 from the data. As the container 1, a columnar reactor or tank having an inner surface having a diameter substantially equal between the upper part and the lower part is preferably used, and it is desirable that a stirring device capable of stirring the powder 3 contained therein is provided. When applied to the above-mentioned olefin polymerization tank or the like, a dispersion plate for dispersing and flowing gas may be provided at the lower part of the vessel. Further, the powder density in the container can be made substantially uniform by stirring the powder in the container at a constant stirring speed, for example, in the range of 100 to 1000 rpm with a stirring device.

As a γ-ray irradiation device (ray source), 137C
One using s or 60Co is preferably used, and one γ-ray source may be shared for density measurement and height measurement, or two γ-ray sources may be provided for each measurement. As the detector, a scintillation counter detector for measuring γ-rays is preferably used, and used for measuring powder height and powder density.

As the control unit, an appropriate device that performs signal processing from the detector and outputs a signal corresponding to, for example, a predetermined time, powder height and powder density can be used. As the calculation unit, an appropriate device that performs calculation processing of the amount of powder in the container based on the powder height signal and the powder density signal from the control unit can be used. Using the apparatus of the present invention, the bulk density is 0, 33 and 04
5 were put into a container after the weight measurement, and the mixture was stirred by a stirrer while changing the stirring rotation speed to 100 to 1000 rpm, and the powder height and the powder density were changed while changing the rotation speed to several stages. The measurement was performed, and the amount of the polymer powder was obtained from each signal by arithmetic processing. The result that the charged amount of the polymer powder (the value measured in advance) and the calculated amount are almost the same is obtained.

[0014]

According to the apparatus of the present invention, since the powder height is obtained by directly measuring the density and the powder amount is obtained, even if the powder density changes due to the number of revolutions of the stirrer, etc., the accurate powder can be obtained. Body weight can be measured.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of an example of the apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Container 2 γ-ray irradiation device 3 Powder 4 Detector 5 Detector 6 Powder upper surface

Claims (1)

[Claims] 1. A container for accommodating powder, a γ-ray irradiator provided outside the container, and a γ-ray irradiator for powder density measurement provided at a position facing the γ-ray irradiator with the powder inside the container interposed therebetween. Γ-ray detector, γ-ray irradiator, γ-ray detector for powder height measurement provided at a position facing the top end of the powder in the container, powder density and powder obtained from both detectors A powder amount measuring device in a container, comprising: a powder amount calculating means for calculating a powder amount in the container from a body height.