JP2011220814A - Test apparatus and test method for dust explosion in fluid bed - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dust explosion test apparatus and a dust explosion test method which can evaluate dust explosibility in a fluid bed.SOLUTION: A dust explosion test apparatus 1 comprises: a fluid bed container 10 which is shaped like a vertically-elongated cylinder provided with a gas introduction port 11 at its lower portion and a gas exhaust port 12 at its upper portion; gas supply means 40 which is connected to the gas introduction port 11 with a pipe and which supplies test gas into the fluid bed container 10; an ignition electrode 21 which ignites a fluid bed consisting of test dust and the test gas; a digital camera 22 for checking the occurrence of dust explosion through an observation hole 17 provided on the fluid bed container 10; and a gas dispersion panel Z, installed above the gas introduction port 11 inside the fluid bed container 10, on which the test dust is placed and through which the test gas passes. Using the dust explosion test apparatus 1 enables the evaluation of dust explosibility in a fluid bed.

Description

  The present invention relates to a dust explosion test apparatus and a dust explosion test method in a fluidized bed. More specifically, the present invention relates to a dust explosion test apparatus and a dust explosion test method for testing explosibility of a fluidized bed composed of a test powder and a test gas in a temperature range of room temperature or higher.

As an evaluation method for dust explosibility of powders, JIS standards (see Non-Patent Documents 1 and 2), “Measurement method of explosive pressure and pressure rise rate of combustible dust” and “Explosion lower limit concentration measurement method of combustible dust” Is defined.
In addition, a method is known in which airtightness is ensured by blowing up powder in a closed container and a test is performed under an arbitrary oxygen concentration (see Non-Patent Documents 3 and 4).

JIS Z 8817 (2002) "Measurement method of explosion pressure and pressure rise rate of combustible dust" JIS Z 8818 (2002) “Measurement method for lower explosive concentration of combustible dust” Central Industrial Accident Prevention Association, `` Prevention measures for dust explosions '', page 33 (1989) Yoichi Uehara and Teruo Ogawa techno system "Fire and Explosion Prevention Technology Handbook" 484 pages (1998)

By the way, there is a chemical process using a fluidized bed formed by continuously supplying gas to the powder material in the reaction vessel. In the fluidized bed, the powder flow state is maintained at a high density by the gas flow, but in the chemical process using such a fluidized bed, a combustible or flammable powder material or supply gas is used. In many cases, it is necessary to evaluate the safety of these explosions.
However, the dust explosion test apparatus according to the above known technique cannot evaluate the explosion safety of the fluidized bed.

  Under such circumstances, an object of the present invention is to provide a dust explosion test apparatus and a dust explosion test method capable of evaluating the dust explosibility of a fluidized bed.

  As a result of intensive studies to solve the above problems, the present inventors have applied a fluidized bed reactor that causes a reaction at the same time that the catalyst is fluidized with a raw material gas in a chemical process, thereby having a dust explosive property. The present inventors have found that a dust explosion test is possible by fluidizing the powder to a state where a dust explosion can occur, and providing an ignition source thereto.

That is, the present invention is a dust explosion test apparatus for testing the explosibility of a fluidized bed composed of a test powder and a test gas,
A vertical cylindrical fluidized bed container provided with a gas inlet at the lower part and a gas outlet at the upper part, and connected to the gas inlet and piping to supply a test gas into the fluidized bed container Gas supply means for igniting, ignition means for igniting a fluidized bed consisting of a test powder and a test gas, observation means for observing the presence or absence of a dust explosion,
Have
In the fluidized bed container,
A gas dispersion plate provided at an upper portion of the gas introduction port, and vents a test gas;
This relates to a dust explosion test apparatus having

  According to this configuration, the test gas on the gas distribution plate provided above the gas inlet in the fluidized bed container is ejected from the gas inlet of the fluidized bed container by the gas supply means. The powder rides on the flow of the test gas and is blown up into the fluidized bed container to form a fluidized bed composed of the test powder and the test gas. By igniting the fluidized bed with the igniting means and observing whether the fluidized bed causes a dust explosion with the observing means, the explosibility of the test powder and the test gas can be evaluated.

In the present invention, the test powder refers to a sample powder for inspection that may cause dust explosion when ignited when mixed with a combustion-supporting gas, such as Ishimatsuko or aluminum powder. It is done. Further, the test gas refers to a sample gas for inspection that may cause a dust explosion by ignition when mixed with a test powder. Examples of the test gas include gases that may show flame support properties, such as oxygen-containing gas, nitrous oxide, fluorine, chlorine, and silicon halide.
In addition, the dust explosion test apparatus of this invention is equipped with the gas supply means which supplies test gas in a fluidized bed container. In the case of an oxygen-containing gas, the test gas is usually supplied by adjusting the compressed air to a predetermined concentration with an inert gas such as compressed argon. In addition, when the test gas is liquid at room temperature such as silicon tetrachloride, the liquid test gas component is stored in an appropriate container, and an inert gas such as argon is supplied to the test gas for bubbling. It can be supplied in the form of being accompanied by an inert gas. Note that the gas component to be detected by bubbling is adjusted to a predetermined concentration and supplied by adjusting the container temperature.

The dust explosion test apparatus of the present invention forms a fluidized bed composed of a test powder and a test gas, and a fluidized bed container (hereinafter simply referred to as a “container”) for causing the fluidized bed to generate a dust explosion by ignition. Yes.) This container needs to have a volume sufficient to form a fluidized bed and cause a dust explosion.
As the fluidized bed container, a vertical cylindrical heat-resistant pressure-resistant container is preferably used. The material of the container is not particularly limited as long as it constitutes a heat and pressure resistant container, but a material having corrosion resistance is preferably used in preparation for using a corrosive test powder or test gas. Generally, stainless steel, nickel alloy or the like is used.

The container is provided with a gas inlet at its lower part and a gas outlet at its upper part. A test gas is introduced from the gas inlet, and a test gas, a test powder, and the like are discharged from the gas outlet.
A lower part of the container is provided with a gas dispersion plate that is provided above the gas introduction port and on which the test powder is placed (set) and vents the test gas. The test powder may be placed on a gas dispersion plate in advance during the test, and then the gas dispersion plate may be attached to the container. However, it is preferable to install powder supply means as described below. The gas dispersion plate has a function of placing a test powder and introducing a test gas to form a fluidized bed by blowing up the test powder. For this reason, the gas dispersion plate needs to have air permeability. For example, a plate-like material made of a perforated metal plate, a sintered alloy or a porous ceramic is used.

  Next, as the container, a fluidized bed is formed as described above, and a vertical cylindrical one is used to cause a dust explosion. More preferably, a small diameter portion is used to facilitate the formation of a fluidized bed. And a large diameter portion. The length and diameter of the small diameter portion and the large diameter portion are appropriately determined depending on the amount of the test powder placed, the amount of gas for forming the fluidized bed, and the like.

Furthermore, it is desirable that the container be provided with a rupture plate that ruptures when the inside of the container becomes excessive pressure due to the impact of dust explosion. The rupture disc is provided in the vicinity of the upper end of the container, and can rupture when the allowable pressure of the container is reached, allowing the pressure to escape. The burst setting pressure needs to be lower than the pressure that reaches the position of the rupture disc when any part of the container reaches rupture.
The material of the rupturable plate is not particularly limited, and examples thereof include nickel and a nickel alloy.

The dust explosion test apparatus preferably has a heating means for heating the fluidized bed container to a predetermined temperature. By placing the test powder on a gas dispersion plate that vents the test gas in the fluidized bed container and heating the fluidized bed container by the heating means, the fluidized bed container is maintained at a predetermined temperature. The By evaluating in that state, the explosion safety of the fluidized bed at a high temperature can be evaluated.
Any heating means may be used as long as the container can be heated directly or indirectly, and a known annular furnace such as an electric furnace or a heating furnace using electromagnetic induction is used.

Moreover, it is preferable that the gas supply means includes a preheating means for heating the test gas to a predetermined temperature.
In the case of measurement at a high temperature, if the test gas supplied into the fluidized bed container remains at room temperature, the temperature in the fluidized bed container is lowered, and measurement at an accurate set temperature becomes difficult. By providing this preheating means, the test gas can be heated to a predetermined temperature corresponding to the test temperature in the fluidized bed container, and the measurement accuracy is further improved.
Even when the fluidized bed container is not heated, in the case of a test gas that is liquid at room temperature, such as silicon tetrachloride, the test gas can be prevented from condensing in the pipe. As a result, a test gas having an accurate temperature can be supplied, and an equivalent fluidized bed can be formed for each test, thereby reducing variations in test results.

The dust explosion test apparatus of the present invention includes ignition means for igniting a fluidized bed composed of a test powder and a test gas, and observation means for observing the presence or absence of a dust explosion.
As the ignition means, a known dischargeable electrode that is also used in a conventional dust explosion test apparatus such as a Hartmann apparatus can be used.
In addition, examples of observation means include photographing equipment such as a digital camera. Specifically, the presence or absence of a dust explosion can be indirectly observed by attaching a heat-resistant observation window such as quartz to a fluidized bed container and photographing a moving image with a digital camera or the like.

  Furthermore, the dust explosion test apparatus of the present invention has a powder supply means for supplying the test powder to the gas dispersion plate inside the fluidized bed container without replacing the inner atmosphere with an inert gas and contacting with the outside air. It is preferable. For example, the test powder can be efficiently moved into the container by installing a pot for preparing the test powder, pressurizing the pot with an inert gas, and opening the valve.

In addition, the dust explosion test apparatus of the present invention is preferably provided with solid-gas separation means that is connected to the gas discharge port by piping and collects the test powder discharged from the container along with the test gas.
Examples of the solid-gas separation means include a cyclone, a bag filter, and a chamber, and these can be used alone or in combination of two or more.
In particular, when the solid-gas separation means has a mechanism for returning the collected test powder to the fluidized bed container, the collected unreacted test powder can be subjected to the powder explosion test again.

  Similarly, it is preferable that emergency discharge means for storing the test powder and the test gas to be ejected outside the container when the rupturable plate is ruptured is provided. As this emergency discharge means, a drum sealed with an inert gas such as nitrogen can be used as appropriate.

Next, the dust explosion test method of the present invention will be described.
The dust explosion test method of the present invention is a method for testing explosibility of a fluidized bed comprising a test powder and a test gas, and is in a fluidized bed container maintained at a set temperature of 100 ° C. or higher and 400 ° C. or lower. Whether or not a dust explosion occurs by igniting the fluidized bed by blowing up the test powder previously placed in the container to form a fluidized bed. It relates to the dust explosion test method to be observed.

The dust explosion test method of the present invention can be performed using the above-described dust explosion test apparatus of the present invention. In particular, from the viewpoint of further improving the accuracy of the measurement temperature, it is preferable that the test gas is preheated so as to reach the set temperature when supplied into the container.
Further, in the dust explosion test method of the present invention, the test powder density in the dust cloud is tested at 10 g / m ³ or more and 1000 g / m ³ or less, which is a general density at which dust explosion occurs. Is desirable.
In addition, the density of the test powder in the fluidized bed is obtained by using a visualization container of the same type as the fluidized bed container, which is separately made of a transparent resin or the like. The volume of the part where the fluidized bed is formed can be determined by changing the conditions such as the charged amount of the test powder, the supply amount of the test gas, and the pressure. It is calculated by measuring the height of the test powder that soars.

  According to the present invention, it is possible to evaluate the dust explosibility in a fluidized bed, and ensure the safety in advance in a chemical process using a fluidized bed made of flammable or combustion-supporting powder material or supply gas. Evaluation can be performed.

It is a mimetic diagram of a dust explosion test device concerning an embodiment of the present invention.

  Hereinafter, an embodiment of the present invention using aluminum powder as a test powder and silicon tetrachloride as a test gas will be specifically described with reference to the drawings.

  A dust explosion test apparatus 1 according to an embodiment of the present invention includes a fluidized bed container 10, an electric furnace 20 that heats the fluidized bed container 10 to a predetermined temperature, a powder supply unit 30, a gas supply unit 40, Air separation means 50 and emergency discharge means 60 are provided.

  In FIG. 1, a fluidized bed container 10 is a vertical cylindrical heat-resistant pressure-resistant container made of stainless steel (SUS310), and includes a small-diameter portion 10a and a large-diameter portion 10b.

The small-diameter portion 10a is a fluidized bed portion for testing the explosibility of a fluidized bed composed of a test powder and a test gas. In this embodiment, the inner diameter is 6.2 cm and the height H ₁ is 58 cm.
The end side of the small diameter portion 10a is formed in a weight shape whose cross-sectional area decreases toward the tip, and a gas inlet 11 is provided at the tip. The gas inlet 11 is connected to the gas supply means 40 via a pipe. Further, a powder retransmission port 16 is provided at a side portion of the small diameter portion 10a, and is connected to a cyclone 51 constituting the solid-gas separation means 50 through a pipe.

The large-diameter portion 10b is a portion that makes it easy to drop the powder that has flown from the fluidized bed to the top and also reduces the impact of dust explosion. In the present embodiment, the inner diameter is 9.7 cm and the height H ₂ is 132 cm. .
A gas discharge port 12 and a powder charging port 15 are provided on the upper side surface of the large diameter portion 10b.
The gas discharge port 12 is connected to a cyclone 51 constituting the solid-gas separation means 50 via a pipe, and the powder charge port 15 is a powder charge pot 31 constituting the powder supply means 30 via the pipe. Connected.

Further, a lid is attached to the upper end portion 13 of the large diameter portion 10b by a flange or the like. The upper end portion 13 is connected to an inactive drum 61 constituting the emergency discharge means 60 through a pipe. A rupturable plate 14 is attached to the lower portion near the upper end portion 13, and the fluidized bed container 10 is in a substantially sealed state.
The rupture disc 14 is ruptured when dust explosion exceeds the rupture disc operating pressure set below the allowable pressure of the fluidized bed container 10, and releases the pressure, and the discharged test gas, test particles, and the like are urgently released. 60 can be recovered.

  The electric furnace 20 is a heating means for heating the fluidized bed container 10 and can hold the container at a predetermined temperature. The temperature inside the container, particularly the temperature at which the fluidized bed is formed, is detected by a thermocouple (not shown) or the like, and linked with an electric furnace to control the temperature inside the container.

  As shown in FIG. 1, a gas dispersion plate Z is disposed above the gas inlet 11 in the small diameter portion 10 a in the fluidized bed container 10. The gas dispersion plate Z is made of a gas-permeable porous ceramic having a thickness of about several centimeters, and the test powder is placed on the gas dispersion plate Z in the powder explosion test.

An ignition electrode 21 for igniting dust is disposed at about 28.5 cm above the gas dispersion plate Z in the small diameter portion 10a.
The ignition electrode 21 of the present embodiment makes it possible to insert both poles whose positional relationship between the two poles is fixed from the same direction by carefully insulating the + pole and the -pole. Therefore, the complexity of adjusting the positional relationship between the two electrodes in the container 1 can be eliminated, and the reproducibility of the measurement is improved.
Further, a viewing window 17 (14.3 mmφ) made of quartz is formed on the side opposite to the ignition electrode 21 in the small diameter portion 10a.
Through this viewing window 17, the inside of the small diameter portion 10 a of the fluidized bed container 10 can be observed. Therefore, the inside of the fluidized bed container 10 can be observed over time by disposing a digital camera 22 as observation means and taking a moving image from the viewing window 17 through the through hole 20a provided in the electric furnace. Since a bright explosion occurs when a dust explosion occurs, the presence or absence of a dust explosion can be easily determined from the captured moving image.

Powder supply means 30 includes a powder feed pot 31, a powder feed port 15 and the powder pipe P ₁ connecting the powder feed pot 31, the powder discharge valve provided in powder pipe P ₁ Vp.
The powder charging pot 31 is replaced with argon gas distributed from the gas cylinder 42. The test powder is supplied into the fluidized bed container 10 through the powder pipe P ₁ by opening and closing the powder valve Vp. Therefore, the test powder can be supplied to the inside of the fluidized bed container 10 without coming into contact with outside air (air).

The gas supply means 40 includes a liquid storage tank 41 in which the temperature of silicon tetrachloride can be controlled by a water bath 41a, a gas cylinder 42 for argon, and heaters 43a and 43b as preheating means.
In this embodiment, since silicon tetrachloride, which is a liquid, is used as the test gas, the liquid storage tank 41 is provided and the test gas (silicon tetrachloride) is supplied to the fluidized bed container 10 by bubbling. When a gaseous test gas is used, the gas cylinder of the test gas may be connected in parallel to the argon gas cylinder 42.
Further, since the piping from the gas cylinder 42 is branched and argon can be supplied directly to the fluidized bed container 10 without going through the liquid storage tank 41, the concentration of the test gas (silicon tetrachloride) is predetermined by bubbling. It can also be diluted to a concentration of
Heaters 43a and 43b are installed in a pipe connecting the liquid storage tank 41 and the gas introduction port 11 and a pipe connecting the gas cylinder 42 and the fluidized bed container 10 directly. Can be heated.

The solid-gas separation means 50 includes a cyclone 51 connected to the gas discharge port 12 by piping, a bag filter 52 provided at the subsequent stage of the cyclone 51, and a return powder for connecting the cyclone 51 and the powder retransmission port 16. It consists of use the pipe P _2.
The cyclone 51 is a facility for collecting the test powder discharged from the fluidized bed container 10 with the test gas, and the subsequent bag filter 52 cannot be recovered by the cyclone 51 and cannot be recovered. This is a facility for collecting the test powder having a fine diameter discharged together with the air flow.
Test powder recovered in the cyclone 51, by opening the powder discharge valve Vp provided powder pipe P _2, it is returned to the fluidized bed vessel 10 through the powder pipe P ₂ it can.
Note that constitutes the solid-gas separating means 50, a cyclone 51, bag filter 52 and the powder discharge pipe P _2, in order to prevent the concentration of the gas can be heated to about 220 ° C..

  On the other hand, the emergency discharge means 60 is composed of an inert drum 61 and a pipe connecting the inert drum 61 and the fluidized bed container 10, and the inside thereof is sealed with nitrogen supplied from a nitrogen cylinder 62.

  EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to a following example, unless the summary is exceeded.

In the dust explosion test apparatus 1 shown in FIG. 1, 60 g of spherical aluminum powder having a particle size d ₅₀ = 33 μm was charged into the fluidized bed container 10 from the powder charging pot 31 as a test powder.
As a test gas, air dehumidified to a dew point of −30 ° C. or lower is circulated at a flow rate of 40 l / min (Nor) without diluting to form a fluidized bed composed of aluminum powder and air, The fluidized bed was ignited by discharging with the ignition electrode 21.
The test state was recorded by the moving image shooting function of the digital camera 22, and the experiment was conducted by remote control to ensure the safety of the experimenter. After the experiment, it was determined as an explosion by checking the video.

In the dust explosion test apparatus 1 shown in FIG. 1, 5 g of spherical aluminum powder having a particle size d ₅₀ = 33 μm is charged in advance into the fluidized bed container 10 as a test powder, and divided into two for heating the container. The temperature was raised to 200 ° C. in the electric furnace 20 of the mold.
As the test gas, silicon tetrachloride was bubbled in the liquid storage tank 41 at 53 ° C. with 0.69 l / min (Nor) argon gas, and at the same time, 30 l / min (Nor) argon gas was circulated. The fluidized bed is made of aluminum powder and silicon tetrachloride by being heated to 200 ° C. by the preheating heater 43a and supplied to the container, and the fluidized bed is ignited. The electrode 21 was discharged and ignited. The test state was recorded by the moving image shooting function of the digital camera 22, and the experiment was conducted by remote control to ensure the safety of the experimenter. After the experiment, it was determined that no explosion occurred by checking the video.

  ADVANTAGE OF THE INVENTION According to this invention, the dust explosion test apparatus and dust explosion test method which can evaluate the dust explosive property in high temperature are provided.

DESCRIPTION OF SYMBOLS 1 Dust explosion test apparatus 10 Fluidized bed container 10a Small diameter part 10b Large diameter part 11 Gas introduction port 12 Gas discharge port 13 Upper end part 14 Rupture plate 15 Powder preparation port 16 Powder retransmission port 17 Viewing window 20 Electric furnace 20a Through-hole 21 Ignition electrode 22 Digital camera 30 Powder supply means 31 Powder charging pot 40 Gas supply means 41 Liquid storage tank 41a Water bath 42 Gas cylinder (argon)
43a, 43b Heater 50 Solid-gas separation means 51 Cyclone 52 Bag filter 60 Emergency discharge means 61 Inert drum 62 Gas cylinder (nitrogen)
Z gas distribution plate Vp powder discharge valve Vg gas valve FC gas flow controller P _1, P ₂ powder pipe

Claims (10)

A dust explosion test apparatus for testing the explosibility of a fluidized bed comprising a test powder and a test gas,
A vertical cylindrical fluidized bed container provided with a gas inlet at the lower part and a gas outlet at the upper part, and connected to the gas inlet and piping to supply a test gas into the fluidized bed container Gas igniting means, igniting means for igniting a fluidized bed composed of a test powder and a test gas, and observation means for observing the presence or absence of a dust explosion from a viewing window provided in the fluidized bed container;
Have
In the fluidized bed container,
A gas dispersion plate provided at an upper portion of the gas introduction port, and vents a test gas;
A dust explosion test apparatus characterized by comprising:   The dust explosion test apparatus according to claim 1, further comprising heating means for heating the fluidized bed container to a predetermined temperature.   The dust explosion test apparatus according to claim 1 or 2, wherein the gas supply means includes preheating means for heating the test gas to a predetermined temperature.   The dust explosion test apparatus according to any one of claims 1 to 3, wherein the fluidized bed container includes a small diameter portion and a large diameter portion.   5. The powder supply means according to claim 1, further comprising: a powder supply means for supplying the test powder to a gas dispersion plate inside the fluidized bed container without replacing the inner atmosphere with an inert gas and contacting the outside air. Dust explosion test equipment.   The solid gas separation means according to any one of claims 1 to 5, further comprising solid-gas separation means connected to the gas discharge port by a pipe and collecting the test powder discharged from the fluidized bed container with the test gas. Dust explosion test equipment.   The dust explosion test apparatus according to claim 6, wherein the solid-gas separation means has a mechanism for returning the collected test powder to the fluidized bed container.   The dust explosion test apparatus according to any one of claims 1 to 7, wherein the fluidized bed container is provided with a rupturable plate in the vicinity of an upper end portion thereof.   A method for testing explosibility of a fluidized bed comprising a sample powder and a sample gas, and continuously supplying the sample gas into a fluidized bed container maintained at a set temperature of 100 ° C. or higher and 400 ° C. or lower. The test powder previously placed in the container is blown up to form a fluidized bed, and it is observed whether or not a dust explosion occurs by igniting the fluidized bed. Dust explosion test method.   The dust explosion test method according to claim 9, wherein when the test gas is supplied into the container, the test gas is heated in advance so as to reach the set temperature.

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