JPH037327B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a gas circulation type fumigation method for powder and granular materials in a silo. For example, one of the problems when fumigating powder and granules with various particle size distributions, such as alpha-alpha pellets, etc., in a silo using a gas circulation method. There are classification and uneven distribution. Classification is a phenomenon in which when powder and granules with various particle size distributions are simply introduced through the input pipe at the top of the silo, the particle size of the accumulated powder increases toward the outer periphery of the silo and decreases toward the center. In this case, most of the fumigation gas passes through the periphery where the particle size is large and the passage resistance is low, and almost none passes through the central area where the particle size is small and the passage resistance is large. Fumigation becomes impossible. In addition, uneven accumulation is a phenomenon in which the passage resistance of fumigation gas is uneven due to the partial formation of piles, and in this case, complete fumigation is also impossible. As shown in other inventions of the present inventors, the above classification and uneven loading can be achieved by providing an eccentric flow correction section for powder and granules in the input tube and a dispersion input section at the lower part of the input tube. This problem can be solved by properly distributing the bodies in silos. That is, by such a charging method, the fine particles are uniformly mixed so as to fill the gaps between the coarse particles, so that the powder and granules are uniformly filled. However, compared to regular grains such as maize and milo, which have uniform grain sizes, the powder and granules packed in this way have a higher resistance to passage of fumigation gas because of their fine grains and powder content. Because of the large size of the silo, even if the normal gas circulation type fumigation used for general grains is applied, it is not possible to average the fumigation gas concentration throughout the silo, and therefore it is not possible to completely Fumigation cannot be carried out. The present invention uses an extremely rational method to prevent classification and uneven accumulation of particles such as alpha apertures, which have various particle size distributions, and to uniformly fill them in a silo with a relatively large amount of fumigation gas. This makes it possible to average the concentration of fumigation gas throughout the silo, even for powder and granular materials that have a passage resistance of
For example, it is designed to perform cyclic fumigation using methyl bromide gas. A detailed explanation will be given below based on an example. Reference numeral 1 is a silo, 2 is a conveyor provided above the silo 1, 3 is an input pipe, 4 is an eccentric flow corrector for powder and granular material provided in the input pipe 3, and 5 is a conveyor provided at the bottom of the input pipe 3. This is the dispersed feeding section provided. The eccentric flow correction section 4 and the dispersion feeding section 5 correct the powder and granular material fed into the silo 1 from the conveyor 2 via the feeding pipe 3.
This is for filling while preventing classification and uneven accumulation, and for example, the structure shown in Japanese Patent Application Laid-Open No. 59-223631 can be applied. In such a configuration, the eccentric flow correction section 4 moves from the conveyor 2 to the feeder 3.
The powder and granules fed into the hopper-like constrictor 6 are deposited in one layer, and a part of the material is connected to the lower part of the hopper-like constrictor 6 to form a fine inlet coaxial with the feeder 3. At the same time, the other part is connected to the communication pipe 9 connected to the communication hole 8 provided in the constriction part 6, and the other part is connected to the outside of the narrow input tube 7 to form an eccentric flow in a concentric manner. This is to correct the flow. Further, the dispersion feeding section 5 first deposits the powder particles falling concentrically from the feeding tube 3 by the eccentric flow correction section 4 on the hopper section 10,
A part of it is dropped along the slope of the mountain, and
The other part is dropped from the lower part of the hopper part 10,
At this time, the powder and granules dropped along the slope of the pile pile are supported coaxially on the outside of the hopper part 10, and the baffle plate of the cylindrical guide part 13 in which baffle plates 11 and spaces 12 are alternately formed. A part of the powder is caused to collide with the hopper part 11 and fall, and the other part is allowed to fall outward through the space part 12, and the particulate material dropped from the lower part of the hopper part 10 is collected by the mountain-like dispersion part 14 supported below. It disperses and falls. This configuration is just an example, and any method for classifying and filling the powder without uneven distribution is suitable. Therefore, fumigation gas inlet/outlet ports 15, 15' are provided at the bottom and top of the silon 1, respectively.
In between, a fumigation gas forward and reverse circulation system S equipped with a blower 16 is constructed. In the illustrated embodiment, a is a pipe exclusively for forward circulation, b is a pipe exclusively for reverse circulation, c is a common pipe, and d is a valve, but these specific configurations are arbitrary. A fumigation gas supply section 17 is provided at a suitable location in the circulation system S. The fumigation gas supply section 1
7 is composed of, for example, a vaporizer 18, a heating tank 19, and a methyl bromide cylinder 20 in the circulation system S, but the specific structure is arbitrary. In the above configuration, the present invention supplies fumigation gas such as methyl bromide to the circulation system S from the fumigation gas supply section 17 after putting the powder to be fumigated into the silo 1. By operating the blower 16, the fumigation gas is circulated through the bottom outlet/outlet 15 as the inlet for the fumigation gas, and the upper outlet/outlet 1.
Silo 1 by reverse circulation operation with 5' as the introduction part.
Forced supply within. The present invention is characterized in that the circulation operation is performed intermittently with appropriate pause times. If we are currently performing a positive cycle, Silo 1
As shown by the solid line in FIG. 3, the pressure distribution inside the silo 1 is positive pressure at the bottom and negative pressure at the top, and the pressure difference decreases as the operation progresses. On the other hand, when reverse circulation is performed, the lower part becomes negative pressure and the upper part becomes positive pressure, as shown by the broken line in FIG. Even if only forward circulation or only reverse circulation is performed continuously in this way, the gas passage resistance of the powder and granules is relatively large, and a pressure difference is created between the top and bottom of silo 1, so that the fumigation gas is It is difficult to make the concentration uniform. Further, even if such forward circulation and reverse circulation are operated continuously and alternately, it is difficult to equalize the concentration in the center, upper and lower portions of the silo 1 due to the gas passage resistance. However, in the present invention, the circulation operation is performed intermittently with an appropriate pause time, so as the pause time passes, the fumigation gas is gradually transferred to the center of the silo 1 due to the pressure difference between the upper and lower parts of the silo 1. It can be permeated in the low pressure direction through the part. In this way, the present invention not only provides an appropriate pause time between circulation operations, but also performs both forward circulation operations. Even if the concentration at the top and bottom of the silo 1 cannot be made uniform in time, the difference in concentration between the top and bottom of the silo 1 can be very effectively eliminated by the pause time after the circulation operation, which is the reverse of the previous stage. In combination with the above, the present invention can uniformize the fumigation gas concentration at the top, bottom, and center of the silo 1 very effectively. Furthermore, although the present invention performs both forward circulation and reverse circulation operations as described above, the fumigation gas outlet/outlet 15,
15' are provided only at the top and bottom of silo 1, and the fumigation gas forward and reverse circulation systems are provided outside of silo 1, with no pipes, etc. for fumigation gas inlet/outlet provided in the middle part of silo 1. Therefore, inconveniences such as clogging of these pipes etc. due to powder and granules do not occur. As described above, the present invention can uniformize the concentration of fumigation gas throughout the silo even for powdered materials such as alpha apertures having various particle size distributions, and A great advantage is that it can be completely fumigated with methyl bromide gas, which has many advantages compared to, for example, fumigation with aluminum phosphide agents. The following table shows the results of an example of the present invention, and the results are as follows: 60 minutes of normal circulation, 20 minutes of rest time, 30 minutes of normal circulation, 20 minutes of rest time, 30 minutes of normal circulation, and 20 minutes of rest time.
This shows the results of fumigation by cycling and resting in a sequence of 20 minutes and 30 minutes of reverse circulation, followed by 72 hours of standing.

【table】

[Table] As described above, the present invention provides fumigation gas inlets and outlets at the top and bottom of the silo, and configures a forward and reverse circulation system for fumigation gas between the respective inlet and outlet. The structure is configured to circulate and supply the fumigation gas into the silo through forward circulation using the bottom outlet as the inlet and reverse circulation using the top outlet as the inlet. In addition, since the circulation operation is performed intermittently with appropriate downtime, it is possible to effectively equalize the fumigation gas concentration at the top, bottom, and center of the silo. This means that the gas concentration can be made uniform throughout the silo, which has many advantages compared to fumigation using aluminum phosphide agents, even for powders with a diverse particle size distribution, such as alpha apellets. It has the great effect of completely fumigating with methyl bromide gas having . In addition, the number and time of forward circulation and reverse circulation in repeating the circulation operation may be set as appropriate depending on the situation.
In addition, the present invention provides fumigation gas inlets and outlets only at the top and bottom of the silo, and provides forward and reverse circulation systems for the fumigation gas outside the silo, with pipes for fumigation gas inlet and outlet installed in the middle of the silo. Since no pipes are provided, there is an advantage that there is no inconvenience such as clogging of these pipes due to powder or granules.

[Brief explanation of the drawing]

Fig. 1 is a system explanatory diagram showing an example of the overall configuration of the present invention, Fig. 2 is an explanatory sectional view showing a specific example of the configuration of the powder/granular material input section, and Fig. 3 is the pressure inside the silo during circulation operation. It is an explanatory diagram showing distribution. Code 1...Silo, 2...Conveyor, 3...Charging pipe, 4...Eccentric flow correction section, 5...Dispersion charging section,
6...Hopper-like constriction part, 7...Narrow input tube, 8...
...Communication hole, 9...Communication pipe, 10...Hopper part,
11...Baffle plate, 12...Space part, 13...Cylindrical guide part, 14...Mountain-shaped dispersion part, 15, 15'...
Outlet/outlet, 16... Blower, 17... Fumigation gas supply section, 18... Vaporizer, 19... Warming tank, 20
...Methyl bromide cylinder, S...Circulation system, a...
Piping exclusively for forward circulation, b... Piping exclusively for reverse circulation, c...
Common piping, d... valves.

Claims (1)

[Claims] 1. Fumigation gas inlets and outlets are provided at the top and bottom of the silo, and a forward and reverse circulation system for fumigation gas equipped with a blower is constructed between each inlet and outlet on the outside of the silo. A fumigation gas supply section is provided at an appropriate location inside, and the fumigation gas supplied from the supply section into the circulation system is subjected to forward circulation using the bottom outlet as the introduction section and reverse circulation using the top introduction/outlet as the introduction section. 1. A gas circulation type fumigation method for powder and granular material in a silo, characterized in that the material is circulated and supplied into the silo through operation, and the circulation operation is performed intermittently with appropriate pause times.