KR200287609Y1 - A formed equipment of uniform dust cloud for a dust explosion test - Google Patents

Abstract

The present invention relates to a device for forming a highly reproducible dispersion of uniform dust clouds required for the explosion limit of dust clouds and flame propagation studies, It is characterized by the generation of one dust cloud.

The present invention solves the problem of the conventional methods of preventing the generation of uniform dust cloud due to the inability to prevent the upward movement of the dust cloud at the ignition timing and the problem of the uniform dispersion of the dust cloud to the high reproducibility And an object of the present invention is to provide a device. In order to realize this purpose, The sample is sent to a rising air stream formed from air supplied from the outside and passed through the combustion tube. The control of the opening and closing of the upper and lower ends of the combustion tube is controlled by a control timer together with the inflow of air to pause the rising dust, Is uniformly dispersed, it is possible to perform an experiment with high reproducibility by ignition.

The homogeneous dispersion of the dust cloud using the experimental apparatus of this invention was confirmed by the vertical propagation of the flame shape forming the hemisphere shape through the slide type quartz glass window installed on the side of the combustor during the ignition, And to an experimental apparatus for uniformly dispersing the dust cloud with high reproducibility.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a uniform dust cloud forming apparatus for dust explosion test,

The present invention relates to a device for forming a highly reproducible dispersion of the uniform dust cloud required for the explosion limit of the dust cloud and the flame propagation study.

With the development of undoping technology, pulverulent powder technology has been extensively used for the production of functional materials and electronic materials as a new material, including raw materials and solid fuels. Thus, even in powders which have not recognized explosion hazards in the past, The danger is increasing. Despite its importance, the research on dust explosion has many problems in the fabrication of experimental and experimental apparatus on the dispersion method of dust cloud, so there is almost no reliable data. The reason for this is that it is difficult for the dust to stay in the space due to its own weight, and since it has a wide particle size and particle size distribution, there is a difference in the falling speed of the particles, and it is difficult to make a uniform dust cloud. Since these factors influence the measurement of dust explosion characteristics, it is very important to produce a reproducible, uniform dust cloud in order to measure reliable data.

Various devices have been developed for the method of forming the dust cloud required in the study of the conventional dust explosion. Experimental apparatuses for generating dust clouds were classified into two types according to the supply method of the dust: the upward type (Hartmann type) and the falling type (Falling type). Recently, the 1 m ³ explosion test apparatus adopted by the International Standard Organization (ISO), an international standard organization, has been used in spherical containers as a combination of an upward injection type and a drop type.

The device using the upward injection type is used to blow the compressed air from the lower part of the explosion container to form a dust cloud, and is used for the explosion limit concentration of the combustible dust, the oxygen concentration affecting the explosion, and the influence of the carbon dioxide gas. A typical device employing the upward injection method is the Hartmann type explosion test apparatus of the US mine. Many experimental data have been measured using this device and are widely used up to now. The Japan Powder Industries Association also employs a Hartmann type dust explosion tester which makes it a little more convenient to use. It injects the dust sample filled in the lower part of the explosion vessel with compressed air, . The method of generating dust by this apparatus is simple, however, the dispersed dust before ignition is difficult to obtain a steady state, and dispersion in a turbulent state can not be avoided, so that the dust cloud is unevenly formed. It is too large to be used for preliminary testing, but it is not suitable for research and experimental use.

On the other hand, in the dropping type apparatus, a sieve is provided on the upper part of the explosion vessel, and a mechanical strike or a vibration by a vibrator is given to drop the sample dust to generate dust clouds. This device has been used in studies employing vertical vessels because it can measure the state of the vessel and is simple to operate. The falling type dust cloud generating device is better in dispersion uniformity than the upward injection type, but it is necessary to pay attention to the aggregation of the dust particles by the sieve. In fact, according to the result of observation of dust cloud using blow or vibration, there is a problem that dust particles do not fall simultaneously through the sieve, or particles fall through only a part of the sieve, so that uniform dust cloud can not be formed.

In addition, the upward injection mode and the falling mode can not avoid the movement of the dust cloud until the ignition of the dust cloud occurs, and the movement of the particles can not be temporarily stopped or suppressed. It is a very difficult problem to disperse solid particles which are solid as long as the earth's gravity acts, completely uniformly in the space. It is an optimal experimental condition to carry out dust explosion research in the space-free space of the universe, but it is not economically feasible. Therefore, dust particles are ignited in a state of having a falling velocity of a certain size, and the flame is propagated, so that there is a high possibility that the movement of the particles affects the explosion characteristic value. Therefore, the dust explosion characteristic values obtained in the experimental apparatus employing the dispersion method employing the Hartmann type and the falling type are considerably deteriorated in reproducibility even when the same apparatus is used, .

The object of the present invention is to solve the above problems and to provide a device for forming a uniform dispersion of dust clouds with high reproducibility.

In order to achieve the above object, the inner space of the combustion chamber of about 1 ~ 2 m which is small in the movement of the dust particles and the good dispersion state is set as the experimental object, the air supply of the dusty fluidized bed which is rising at a slow rate is stopped, So that the rising dust cloud is temporarily stopped so that the dust is uniformly distributed and ignited.

Fig. 1 is a cross-

Fig. 2 is a schematic view showing an experimental apparatus using a dust-

Fig. 3 is a cross-sectional view of the upper part of the combustion tube with the electronic shutter

Fig. 4 is an explanatory view showing the generation process of dust cloud by the dust generator of the present invention

5 shows an example of a control circuit operation using an electronic timer by generating a dust cloud and automating experimental manipulations

FIG. 6 is a view of a flame observed when the dust lighter is ignited by the present inventive apparatus, and is a photograph showing the uniformity of the dust cloud

Description of the Related Art

1. Air supply pipes 2a, 2b, 2c. air

3. Sintered metal filter (Porous plate) 4. Soft rubber

5. Moving system 6. Steel wire

7. Rotation shaft (Winch) 8. Solenoid valve

9. Spark ignition 10. Flame

11. Combination duct 12. Shutter

13. Slide quartz glass

14. Control timer (Time controller) 15. Dust sample (dust)

16. Sensor insertion hole 100. Dust supply device

200. A dust cloud generator

The present invention will be described in detail with reference to the drawings.

The dust cloud generator 200 of the present invention comprises a vertical combustion tube 11, a dust supply device 100, and a control timer 14.

The vertical combustion tube 11 is provided with a shutter 12, an ignition device 9, a quartz glass window 13 and a sensor insertion hole 16. As shown in FIG. 2, the vertical combustion tube 11 has a square cross- The ignition device 9 is located at about 150 mm from the lower end of the vertical combustion tube 11 and the ignition device 9 is provided at 1,800 mm. The shutter 12 may be opened and closed as shown in FIG. 3 so as to be closed when the dust cloud is ignited, and the ignition device 9 stops the dust cloud and is uniformly distributed And the quartz glass window 13 is for observing the flame. The quartz glass window 13 is provided on the side surface of the vertical combustion tube 11 to reflect light as observed in A and A ' And it is possible to observe the flame by using the laser sheet and the optical measuring device from the side by installing it in a slide manner. The sensor insertion hole 16 is formed in the rear of the vertical combustion tube 11 as shown in C of FIG. 2, and it is possible to insert a sensor for measuring the flame temperature and the ion distribution near the flame, The holes 16 other than the holes 16 inserted with the bolts are sealed by bolts.

2, the dust supply device 100 is provided with a sintered metal filter 3, an air supply pipe 1, a carrier 5 and a soft rubber 4, As a filter filter capable of dispersing dust particles uniformly by the upward flow of the sample 16, the metal powder is compressed and molded and sintered at a temperature not higher than the melting point, 140 x 2 mm, The air supply pipe 1 is attached to the outside of the lower part of the dust supply device 100 so that the air 2a flows from the outside to the vertical combustion pipe and the carrier 5 supports the dust supply device 100, The carrier 5 connected to the wire 6 by the rotation of the rotary shaft 7 moves the dust supply device 100 to open the lower portion of the vertical combustion tube 11, ).

The soft rubber 4 is attached to the upper end of the dust supply device 100 so that the soft rubber 4 adheres closely to the lower end of the vertical combustion pipe 11 while the soft rubber 4 of the dust supply device 100 is ignited, (11).

The control timer 14 is provided outside the vertical combustion tube 11 and controls the shutter 12, the ignition device 9, the solenoid valve 8 and the rotary shaft 7 to open and close the shutter 12, Air supply, and movement of the carrier to separate the dust supply device 100 from the vertical supply pipe 11.

The operation of this device will be described as follows.

The generation of the dust cloud causes the compressed air 24 to flow into the air supply pipe 1 in a state in which the shutter 12 at the top of the vertical combustion pipe 11 is opened. The air 2a supplied from the outside via the air supply pipe 1 located outside the lower part of the dust supply device 100 has the effect of dispersing the air flow through the sintered metal filter 3, The air 2b is loaded on the sintered metal filter 3 by loading the dust sample 15 in a rising air stream to form a fluidized bed of the dust sample 15 and the fluidized bed is mixed with the air 2c in the combustion tube, And flows out toward the outlet of the upper part which is open. The vertical movement of the dust-air mixer at this time becomes a comparatively gentle upward flow of about 0.051 m / sec (a little fluctuated by the air supply speed). Air mixture of the dust sample 15 and the air 2c in the combustion tube is generated by the flow of the air and flows along the vertical combustion tube 11 at a constant speed and the dust- The air supply from the air supply pipe 1 is stopped when it is dispersed throughout the combustion tube.

The dust supply device 100 is moved to the carrier 5 at the same time as stopping the supply of the air 2a supplied from the outside for igniting the dust cloud to open the lower portion of the vertical combustion tube 11, Close the shutter 12 at the top. After these processes are completed, the ignition is made to have a slight delay time by using the control timer 14 and then ignited by the ignition device 9.

The advantage of using a fluidized bed is that the control timer 14 can control the dust concentration by adjusting the amount of air 2a supplied from the outside and the time supplied, It is possible to temporarily minimize the movement of dust particles in the space to produce a homogeneous laminar flow gas mixture.

The generation process of the dust cloud by the dust generator of the present invention is as follows.

4, air (2a) supplied from the outside in the state (I) in which dust is placed on the sintered metal filter (3) passes through the sintered metal filter (3) (D-2) (Ⅱ), the dust cloud moved upward spreads over the entire vertical combustion tube 11 to generate a uniformly dispersed dust cloud d-3 (III), the upper part of the vertical combustion tube 11 is closed and the rising dust cloud is stopped, and the dust supply device 100 is moved to open the lower part of the vertical combustion tube (III).

Such a series of operations, including the generation of dust clouds, can be automated by creating and using control timers 14 using electronic circuits. 5, the supply of the dust sample is stopped for a time t _A (13 to 318 sec), followed by the disconnection of the dust feeder 100 (A), and the time t _B (0.3 to 0.5 (B), wait for t _C , and then ignite (C). The reason for setting the delay time of t _B is to obtain the effect of temporarily stopping the space in the vertical combustion tube 11 due to the action of gravity acting on the dust particles which have moved to the upper part by leaving the air for a certain time after stopping the supply of air , And it is possible to select the delay time t _B (0.3 to 0.5 sec) according to the flow rate by observing the movement of the dust cloud by the flow rate of the air 2a supplied from the outside, Can be known by the amount of decrease of the dust sample 15 in the apparatus 100. [

6 is a graph showing the relationship between the dust cloud of a dust-air mixer (concentration 47 g / m 3) formed in a vertical combustion tube 11 of a dust cloud generating apparatus 200 of the present invention at a relatively low speed (0.38 m / sec) (Exposure time; 1 / 1500sec) of the flame propagating in the air, Mushrooms are pine pollen, and the shape of the pollen particles is close to spherical shape and the particle size is almost constant. Therefore, it is used as the standard powder in powder engineering. Therefore, it is used as the dust sample (15) do. In this ignition experiment, as shown in FIG. 6, the flame formed in the vertical combustion tube has a constant flame surface and vertical propagation while forming an oval shape of the hemisphere. If the dust cloud is not uniform or is in the form of turbulence, A uniform flame shape such as an elliptical shape is not obtained and the shape of the flame surface becomes irregular. In addition, the dust cloud obtained from the dust generator of the present invention, which is seen from the state of the flame in which the flame is moved upward almost constantly with time, can be said to be very uniform.

Table 1 compares the characteristics of the present invention with those of the conventional dust cloud generator. As shown in Table 1, the dust cloud generator can generate more uniform dust clouds than the conventional dust cloud generator have.

<Table 1>

Hartmann type Falling type Present invention Dispersion method Compressed air Mechanical tapping or vibrating with mesh The fluidized bed and the sintered metal filter (Fluidized bed and Porous plate) The mechanical structure of apparatus Complicated Comparatively less complicated Simple and low cost Direction of initial dispersed dust cloud. Upwards Downwards Upwards Flow type Turbulent Laminar Laminar Dust concentration 1. Depends on the amount of dust used 2. Dust is dispersed and varies with time 3. Time-dependent 1. Depends on the number of mechanical strikes 2. The distribution can be adjusted by the frequency of impact 1. Independent of the amount of dust used 2. Can be changed manually 3. Maintain good quality schedule 4. Instantaneous stop of dust particles for a certain period of time The efficiency in terms of the amount of time consumed per experiment Inefficient (Low efficient); Time consuming for next experimental setup. Efficient Efficient Distribution of dispersed dust cloud Unsatisfactory. Measured value is very large due to very uneven dust cloud. However, in the experiment, the experimenter's judgment on the optimum concentration of dust cloud was required, and the results varied according to the experimenter. Satisfactory. The reason is that it is hardly dependent on the judgment of the experimenter in determining the optimum dust cloud.

This design makes it possible to generate uniform dust clouds without turbulence, freely set the dust concentration, and little influence of dispersibility due to the amount of dust used. In addition, it is easy to control the concentration by the fluidized bed, minimizing the movement of the particles, making it possible to generate laminar dust clouds, and there are few processes requiring the judgment of the experimenter in the experiment operation for producing uniform dust cloud, It is possible to automate the experiment operation and to generalize the experiment operation since the measurement error according to the experimenter can be prevented in advance.

In addition, the experimental apparatus of the present invention has a simple structure, so that it can be easily manufactured because it has little trouble. By using the present invention, it is possible to make the dust cloud generator low in value and applied to a scale apparatus of all scales from small scale to large scale This is possible.

Claims (1)

An apparatus for producing a uniform dust cloud, comprising: a vertical combustion tube (11) for detonating uniformly distributed dust; a dust supply device (100) for uniformly supplying dust below the vertical combustion tube; And a control timer 14 for controlling the dust explosion test. The vertical combustion tube 11 has a shutter 12 at an upper portion thereof, an ignition device 9 at an intermediate portion thereof, a quartz glass window 13 for observing a flame at a side surface thereof, And a sensor insertion hole 16 for inserting a sensor in the rear of the vertical combustion tube 11. The dust supply device 100 is provided with a soft rubber 4 and dust 15 mounted thereon so as to be in close contact with the vertical combustion tube 11, An air supply pipe 1 connected to the solenoid valve 8 for introducing the air 2a from the outside to the outside of the lower portion and a carrier 5 at the lower end thereof are provided, The timer 14 includes a shutter 12, an ignition device 9, (8) and the rotary shaft (7), wherein the valve (8) and the rotary shaft (7) are connected to each other to control the valve (8) and the rotary shaft (7).