Powder storage device and its dust explosion prevention system

Abstract

To prevent an explosion accident in a powder storage device.SOLUTION: A powder storage device 1 comprises: a silo container 100 which stores powder 104; and an injection unit 300 which injects at least one kind selected from a group consisting of inert gas, ion and mist into the silo container 100.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] This invention relates to a powder storage device and its dust explosion prevention system.

Background Art

[0002] Conventionally, a silo is disclosed in, for example, Japanese Patent Application Laid-Open No. 2018-185264 (Patent Document 1). Patent Document 1 discloses a suction hose suspended from the upper part of a silo, and a suction hose length adjustment device that adjusts the length of the suction hose so that the suction port of the suction hose is positioned near the surface of the stored material based on the height information of the stored material stored in the silo, and a gas sensor that detects the concentration of a predetermined component in the gas sucked by the suction hose.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, there has been a problem that explosion accidents can occur in conventional silos.

Means for Solving the Problems

[0005] The powder storage device includes a silo container for storing powder, and an injection unit for injecting at least one selected from the group consisting of inert gas, ions, and mist into the silo container.

[0006] The powder storage device configured in this way can suppress dust explosion in the silo container because it injects an inert gas or the like into the silo container.

[0007] Preferably, it further includes a control unit that adjusts the injection amount of at least one selected from the group consisting of the inert gas, ions, and mist, and a storage unit that stores functions necessary for adjusting the injection amount.

[0008] In this case, since the injection amount is adjusted according to the function stored in the storage unit, the injection amount can be effectively controlled.

[0009] Preferably, the control unit adjusts the injection amount according to the type of powder and the total volume of the powder. In this case, dust explosion can be effectively suppressed.

[0010] Preferably, the control unit adjusts the injection amount according to the type of powder and the moisture content of the powder. In this case, dust explosion can be effectively suppressed.

[0011] Preferably, the control unit adjusts the injection amount according to the type of powder and the particle size of the powder. In this case, dust explosion can be effectively suppressed.

[0012] Preferably, the control unit adjusts the injection amount according to the type of powder and the humidity at the time of input. In this case, dust explosion can be effectively suppressed.

[0013] Preferably, the control unit adjusts the injection amount according to the explosion limit concentration of the powder. Preferably, the control unit adjusts the injection amount according to the statistical minimum ignition energy of the powder to do.

[0014] Preferably, the control unit adjusts the injection amount according to the limiting oxygen concentration of the powder. The dust explosion prevention system according to the present invention is a dust explosion prevention system for a powder storage device that realizes a neural network by an information processing device. The powder storage device includes a silo container for storing powder, and an injection unit for injecting at least one selected from the group consisting of an inert gas, ions, and mist into the silo container. The dust explosion prevention system of the powder storage device includes an input layer and an output layer. The input data of the input layer is set as at least one of a plurality of risk factors related to powder dust explosion when powder is put into the silo container, and the output data of the output layer is set as the probability of dust explosion occurring in the silo container in the future from the powder input time. A neural network, a machine learning unit that trains the neural network using the actual values of the input data and the output data as teacher data, and inputs the input data to the neural network trained by the machine learning unit with the current time as the reference time, and based on the output data when the current time is the reference time, an estimation unit that obtains an estimated value for the future, and a control unit that determines the injection amount from the injection unit according to the estimated value of the estimation unit. The risk factors are the type of powder, the total volume of the powder, the moisture content of the powder, the particle size of the powder, and the humidity at the time of powder input.

[0015] The dust explosion prevention system of the powder storage device configured as described above can determine the injection amount with high accuracy because it obtains an estimated value for the future using a neural network.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

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Embodiments for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described with reference to the drawings. (Configuration of the Device) FIG. 1 is a schematic diagram of a powder storage device according to an embodiment. As shown in FIG. 1, the powder storage device 1 according to the embodiment includes a silo container 100 for storing powder, and an injection unit 300 for injecting at least one selected from the group consisting of inert gas, ions, and mist into the silo container.

[0018] The powder storage device 1 includes a charging unit 200 for charging powder into the silo container 100. The powder storage device 1 includes a control unit 400 for controlling the flow rate, injection timing, etc. of gas or the like injected from the injection unit 300, and a storage unit 500 for storing data used for the calculation of the control unit 400.

[0019] The silo container 100 has a cylindrical shape, a tubular state such as each cylindrical shape. The inner diameter does not necessarily have to be constant, and the inner diameter may change according to the height. The volume of the silo container 100 is not particularly limited.

[0020] Powder is stored in the silo container 100. Examples of the pellets ( powder) stored in the silo container 100 include foods such as wheat, barley, rye, corn, soybeans, adzuki beans, soybean meal, etc., and industrial products such as alumina, coal, tire chips, wood chips, straw, etc.

[0021] The charging section 200 is provided at the upper part of the silo container 100. The charging section 200 drops powder into the silo container 100 by gravity, for example. However, not only by gravity dropping, but powder may be charged from the charging section 200 into the silo container 100 by a screw (thread), for example. When using power such as a screw, the charging section 200 does not necessarily have to be provided at the upper part of the silo container 100 and may be provided at the side part or the lower part of the silo container 100.

[0022] The injection section 300 is a device for injecting gas, ions, mist, etc. into the silo container 100. The injection section 300 may include a nozzle provided inside the silo container 100. The injection section 300 injects an inert gas such as nitrogen or carbon dioxide into the silo container 100 in order to suppress dust explosion inside the silo container 100.

[0023] When plants such as pine cones are in the silo container 100, the pine cones breathe even during storage. Thereby, oxygen is consumed and carbon dioxide is generated. Therefore, the air inside the silo container 100 becomes thin and an oxygen-deficient state occurs. When entering the silo container 100 for inspection or the like, the oxygen concentration is measured with an oxygen concentration measuring device. If it is 18% or more, it is safe, but if it is less than this, it will be oxygen deficiency. In order to prevent this, oxygen may be supplied from the injection section 300 to make the oxygen concentration inside the silo container 100 18% or more. That is, not only an inert gas for preventing dust explosion but also oxygen gas or air for enabling an operator to work inside the silo container 100 may be injected from the injection section 300.

[0024] Ions may be injected from the injection unit 300 into the silo container 100. By injecting ions, each powder can be neutralized to reduce the risk of dust explosion. As a device for generating such ions, for example, the hybrid type ultra-high-speed sensing ionizer SJ-E series manufactured by Keyence Corporation can be used. When injecting ions, since the gas composition in the silo container 100 is not changed compared with the case of injecting the above-described gas, it is optimal for storing powders (such as sawdust) that require management of the gas composition in the silo container 100. Further, both gas and ions may be injected from the injection unit 300.

[0025] Mist may be injected from the injection unit 300. The mist can be produced, for example, by the product names "Meka Suing Nozzle" series or "Water Mist" manufactured by Galyu Co., Ltd. It is preferable to use mist for powders that do not cause problems such as corrosion even when moisture adheres.

[0026] The control unit 400 is a device for controlling the flow rate, flow velocity, injection timing, etc. of gas, ions, mist, etc. injected from the injection unit 300. The control unit 400 includes, for example, a computer.

[0027] The storage unit 500 stores a table used for control in the control unit 400. The storage unit 500 may be a hard disk of a computer constituting the control unit 400. The storage unit 500 may be a recording medium detachable from the computer. Examples of the recording medium include media that fixedly carry programs, such as DVD-RAM, DVD-ROM, CD-ROM, FD, hard disks, magnetic tapes, cassette tapes, optical disks, semiconductor memories such as EEPROM and flash ROM. The recording medium is a non-temporary medium readable by a computer for the program, etc. Here, the program includes not only a program directly executable by the CPU, but also a program in source program form, a compressed program, an encrypted program and the like.

[0028] Figure 2 is a detailed view of the powder storage device according to the embodiment. The powder storage device 1 shown in Figure 2 inertizes the inside of the silo container 100. The silo container 100 has a tapered shape at the inlet 110 and outlet 120 portions. The silo container 100 has a cylindrical shape, and powder 104 is stored therein.

[0029] A plurality of temperature sensors 102 are provided on the outer peripheral surface of the silo container 100. A temperature sensor 105 is also provided at the center of the silo container 100. The temperature sensors 102 and 105 measure the temperature inside the silo container 100, and when the temperature of the silo container 100 becomes equal to or higher than a predetermined value, the inside of the silo container 100 is cooled. Note that the temperature sensor 102 does not necessarily have to be provided.

[0030] A charging section 200 is provided on the silo container 100. Powder is charged from the charging section 200 to the inlet 110. The charging rate of the powder from the charging section 200 to the inlet 110 is adjustable.

[0031] Powder 104 is discharged from the outlet 120 of the silo container 100. An injection section 300 is provided on the peripheral surface of the silo container 100. The injection section 300 has a pipe 107 and a nozzle 103 attached to the pipe 107. The pipe 107 is connected to a control section 400. The flow of gas or the like in the pipe 107 is controlled by the control section 400.

[0032] The control section 400 has, for example, a valve and a computer that controls the valve. At least one of a high-pressure container group 610, a CE (Cold Evaporator) tank device 620, and a PSA (Pressure Swing Adsorption) device 630 is connected to the control section 400 is.

[0033] The high-pressure container group 610 is composed of a plurality of cylinders 611. The plurality of cylinders 611 are filled with, for example, nitrogen gas. When injecting nitrogen gas from the nozzle 103 into the silo container 100, the nitrogen gas is supplied from the cylinders 611. The control unit 400 and the high-pressure container group 610 are connected by a pipe 619.

[0034] The CE tank device 620 has a tank 621 for storing liquid nitrogen and a regulator 622 that receives the supply of liquid nitrogen from the tank and vaporizes the liquid nitrogen. The control unit 400 and the CE tank device 620 are connected by a pipe 629.

[0035] The PSA device 630 is a pressure swing adsorption device. By utilizing the difference in the adsorption characteristics of the adsorbent for gases, while alternately repeating the operations of pressurization and depressurization, the target gas (nitrogen) is continuously separated. As the adsorbent, for example, "Bellfine activated carbon", a high-performance MSC (molecular sieves carbon) manufactured by Air Water Co., Ltd., can be used. The control unit 400 and the PSA device 630 are connected by a pipe 639.

[0036] As a device for sending nitrogen gas to the control unit 400, a high-purity nitrogen gas generator "V1" (trade name) manufactured by Air Water Co., Ltd. may be used. This device stably generates high-purity nitrogen gas by heat exchange using the cold heat of liquefied nitrogen. That is, when liquid nitrogen vaporizes, a large amount of heat is taken away. By using this heat to cool air, oxygen, carbon dioxide, etc. in the air are liquefied, and the nitrogen remaining as a gas is utilized for a predetermined purpose. Thereby, nitrogen gas can be stably supplied at low cost.

[0037] In order to cause a dust explosion, three requirements are necessary: the presence of combustible dust, the presence of an ignition source, the presence of oxygen necessary for explosion. In the present invention, by injecting nitrogen gas or the like, the risk of dust explosion is reduced. This not only reduces oxygen but also contributes to reducing the combustibility of combustible dust and not generating an ignition source (static electricity).

[0038] Figure 3 is a graph showing the relationship between the total volume of the powder and the injection amount of gas or the like. As shown in Figure 3, there is a correlation between the total volume of the powder and the risk of dust explosion. As the total volume of the powder increases, the risk of dust explosion increases. This is presumably because when the total volume of the powder increases, the number of contacts between the powders when the powder is put into the silo container 100 increases, so static electricity is generated between the powders, which triggers the dust explosion. Furthermore, the risk of dust explosion is higher when the powder is wood pellets than when the powder is grains. This is presumably because the moisture content of wood pellets is lower than that of grains. The data regarding the graph of Figure 3 is stored in the storage unit 500.

[0039] The data regarding the total volume of the powder can be measured at the stage when the powder transported by a ship or the like is landed. The data regarding the total volume is input into the storage unit 500, for example. Based on the input data and the graph of Figure 3, the injection amount of gas or the like into the silo container 100 is determined. Then, when the powder is put from the input unit 200 into the inlet 110, gas or the like is injected based on the determined injection amount.

[0040] Figure 4 is a graph showing the relationship between the moisture content of the powder and the injection amount of gas or the like. As shown in Figure 4, there is a correlation between the moisture content of the powder and the risk of dust explosion. As the moisture content of the powder decreases, the energy (activation energy) for burning the powder becomes small, so the risk of dust explosion increases. This is presumably because when the moisture content of the powder decreases, the powder easily burns in the silo container 100. The data regarding the graph of Figure 4 is stored in the storage unit 500.

[0041] The data regarding the moisture content of the powder can be obtained by extracting a part of the powder before it is put into the silo container 100 and measuring its moisture content. The data regarding the moisture content is input into the storage unit 500, for example. Based on the input data and the graph of Figure 4, the injection amount of gas or the like into the silo container 100 is determined. Then, when the powder is put from the input unit 200 into the inlet 110, gas or the like is injected based on the determined injection amount.

[0042] Figure 5 is a graph showing the relationship between the particle size of the powder and the injection amount of gas or the like. As shown in Figure 5, there is a correlation between the particle size of the powder and the risk of dust explosion. When the particle size of the powder becomes smaller, the risk of dust explosion becomes higher. This is presumably because when the particle size of the powder becomes smaller, the area of contact between the powder and oxygen becomes larger, making it easier for the powder to burn inside the silo container 100. The data regarding the graph of Figure 5 is stored in the storage unit 500.

[0043] Data regarding the particle size of the powder can be obtained by extracting a part of the powder before it is put into the silo container 100 and measuring its particle size. The particle size can be measured, for example, based on JIS-Z-8825:2013. Furthermore, by photographing the powder before it is put into the silo container and performing image analysis, the particle size of individual particles can be determined. Data regarding the particle size is input into, for example, the storage unit 500. Based on the input data and the graph of Figure 5, the injection amount of gas or the like into the silo container 100 is determined. Then, when the powder is being put from the input unit 200 into the inlet 110, gas or the like is injected based on the determined injection amount.

[0044] Figure 6 is a graph showing the relationship between the humidity at the time of powder input and the injection amount of gas or the like. As shown in Figure 6, there is a correlation between the humidity at the time of powder input and the risk of dust explosion. When the humidity at the time of powder input is low, the risk of dust explosion becomes higher. This is presumably because when the humidity is low, it is difficult for moisture to adhere to the surface of the powder, so the energy required to burn the powder becomes smaller, making it easier for the powder to burn inside the silo container 100 and presumably easier to burn. The data regarding the graph of Figure 6 is stored in the storage unit 500.

[0045] Data regarding the humidity at the time of powder input is obtained from the humidity announced by the Japan Meteorological Agency at the time before the powder is put into the silo container 100. Furthermore, a hygrometer may be provided inside the silo container 100, and the humidity may be measured using that hygrometer.

[0046] FIG. 7 is a graph showing the relationship between the explosion limit concentration of powder and the injection amount of gas or the like. As shown in FIG. 7, there is a correlation between the explosion limit concentration of powder and the risk of dust explosion, and as the explosion limit concentration of powder decreases, the risk of dust explosion increases. This is because a small explosion limit concentration indicates that the powder is likely to explode at a low concentration. The explosion limit concentration is determined mainly by the type of powder, taking into account factors such as particle size and moisture content. When determining the explosion limit concentration, it may be determined only by the type of powder conveyed to the input unit 200, or it may be determined taking into account the type of powder and the particle size. As shown in FIG. 7, the explosion limit concentration of wood pellets is about 1 / 4 of the explosion limit concentration of grains, indicating that wood pellets are likely to explode. The data related to the graph of FIG. 7 is stored in the storage unit 500.

[0047] FIG. 8 is a graph showing the relationship between the statistical minimum ignition energy of powder and the injection amount of gas or the like. As shown in FIG. 8, there is a correlation between the minimum ignition energy of powder and the risk of dust explosion, and as the minimum ignition energy of powder decreases, the risk of dust explosion increases. This is because a small minimum ignition energy indicates that dust is likely to explode with a small amount of energy. The minimum ignition energy is determined mainly by the type of powder, taking into account factors such as particle size and moisture content. When determining the minimum ignition energy, it may be determined only by the type of powder conveyed to the input unit 200, or it may be determined taking into account the type of powder and the particle size. As shown in FIG. 8, the minimum ignition energy of wood pellets is about 1 / 64 of the minimum ignition energy of grains, indicating that wood pellets are likely to explode. The data related to the graph of FIG. 8 is stored in the storage unit 500.

[0048] Figure 9 is a graph showing the relationship between the limiting oxygen concentration of the powder and the injection amount of gas or the like. As shown in Figure 9, there is a correlation between the limiting oxygen concentration of the powder and the risk of dust explosion. When the limiting oxygen concentration of the powder decreases, the risk of dust explosion increases. This is because a small limiting oxygen concentration indicates that dust explosion can occur at a low oxygen concentration. The limiting oxygen concentration is mainly determined by the type of powder, and is determined considering factors such as particle size and moisture content. When determining the limiting oxygen concentration, it may be determined only by the type of powder transported to the input unit 200, or may be determined considering the type and particle size of the powder. The data regarding the graph of Figure 9 is stored in the storage unit 500.

[0049] The dust explosion prevention system in the powder storage device 1 is a dust explosion prevention system of the powder storage device 1 that realizes a neural network by an information processing device. The powder storage device 1 includes a silo container 100 for storing powder, and an injection unit 300 for injecting at least one selected from the group consisting of inert gas, ions, and mist into the silo container 100. The dust explosion prevention system of the powder storage device 1 includes an input layer and an output layer. The input data of the input layer is taken as at least one of a plurality of risk factors related to powder dust explosion when powder is input into the silo container 100, and the output data of the output layer is taken as the probability of dust explosion occurring in the silo container 100 in the future from the powder input time. A neural network, a machine learning unit for training the neural network using the actual values of the input data and the output data as teacher data, and inputting the input data to the neural network trained by the machine learning unit with the current time as the reference time, and obtaining an estimated value for the future based on the output data with the current time as the reference time. An estimation unit, and a control unit 400 for determining the injection amount from the injection unit according to the estimated value of the estimation unit. The risk factors are the type of powder, the total volume of the powder, the moisture content of the powder, the particle size of the powder, the humidity at the time of powder input, the explosion limit concentration of the powder, the statistically minimum ignition energy of the powder, and the limiting oxygen concentration of the powder.

[0050] Input and output data related to machine learning are obtained by simulation. Values of various risk factors are changed and input into a commercially available simulator, and the values output by the simulation are used as actual results to create teacher data.

[0051] The embodiments disclosed herein should be considered illustrative in all respects and not restrictive. The scope of the present invention is defined not by the above-described embodiments but by the claims, and is intended to include meanings equivalent to the claims and all modifications within the scope.

Explanation of Signs

[0052] 1 Powder storage device, 100 Silo container, 102, 105 Temperature sensor, 103 Nozzle, 104 Powder, 107, 619, 629, 639 Pipe, 110 Inlet, 120 Outlet, 200 Feeding section, 300 Injection section, 400 Control section, 500 Storage section, 610 High-pressure container group, 611 Cylinder, 620 CE tank device, 621 Tank, 622 Regulator, 630 PSA device.

Claims

【Claim 1】 A silo container for storing powder, and an injection unit for injecting at least one selected from the group consisting of an inert gas, ions, and mist into the silo container, further comprising a control unit for adjusting the injection amount of at least one selected from the group consisting of the inert gas, ions, and mist, and a storage unit for storing a function necessary for adjusting the injection amount, wherein the control unit adjusts the injection amount according to the type of powder and the humidity at the time of input, the injection unit is provided on the peripheral surface of the silo container, the injection unit has a pipe and a nozzle attached to the pipe, the pipe is connected to the control unit, a flow of at least one selected from the group consisting of the inert gas, ions, and mist in the pipe is controlled by the control unit, and a plurality of temperature sensors are provided on the outer peripheral surface of the silo container. A powder storage device.

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