JPH04272030A - Pneumatic transportation method and device for fine powder - Google Patents

Abstract

PURPOSE:To transport fine powder pneumatically in pressurizing system without accumulating it in a container. CONSTITUTION:An aeration device includes a process for charging fine powder 1 in a container 2, a process for enclosing the powder and feeding pressurized gas 4, and a process for transporting the fine powder 1 by feeding the fine powder 1 to a transportation pipe 7 due to difference in pressure of the pressurized gas and dispersing it into the transportation gas 8. The pressurized gas 4 is fed to the container 2 from its wide bottom area of over 70% in level cross-section of the container 2.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to pneumatic transport for transporting fine powder at a pressure higher than atmospheric pressure. Note that, hereinafter, in this specification, pneumatic transport is a customary name for this type of transport, and the carrier gas is not limited to air.

0002

2. Description of the Related Art A general method of pneumatic transportation of powder by a pressure-feeding method in which the pressure inside the transportation piping is higher than atmospheric pressure will be explained with reference to FIG. Powder 1 is charged into the container 2 through the charging port (not shown), and after closing the charging port and sealing the container, the pressurized gas 4 is sent, and the outlet valve 9 is opened and the transport piping 7 is opened due to the pressure difference between the inside and outside. Powder 1 is sent out, dispersed in carrier gas 8, and pumped under pressure in the pipe higher than atmospheric pressure. At this time, the pressurized gas 4 blows up into the container 2 from the bottom of the container 2 through a perforated plate or canvas cloth called an aeration plate 3, and sends the powder 1 into a suspended state from the nozzle pipe 6 to the transportation pipe 7. be.

0003

[Problem to be solved by the invention] By the way, this type of pneumatic transportation of powder using the pressure-feeding method is widely used in many manufacturing industries including the chemical industry. Due to the movement to increase the surface area by pulverization, or to effectively utilize fine powder such as recovered dust as a resource, which has traditionally been difficult to handle, there are cases where fine powder with a particle size of several μm to several tens of μm is handled. is increasing. In conventional equipment, the container 2 has an inverted conical shape with an angle of 60° to 40° at the bottom, and the area of the aeration plate is generally only about 5 to 30% of the top cross section of the container. However, when trying to pump such fine powder, the pressurized gas suspends only the powder layer directly above the aeration plate, and the powder around the container does not become fluidized, resulting in poor ventilation. As a result, the inside of the powder bed that has not been fluidized is compressed from its surroundings and becomes compacted. Although such a phenomenon hardly occurs with ordinary powder, it becomes noticeable when the particle size is a fine powder of several micrometers to several tens of micrometers.

Possible means to prevent this compaction include a method of pre-treating the fine powder to increase the particle size, and a method of mechanically stirring the part that has not been aerated. In the latter case, there are various problems including an increase in maintenance costs due to the complexity of the device. An object of the present invention is to provide a method for pneumatic transportation of fine powder that solves these problems.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the present invention is characterized in that pressurized gas is supplied from a wide bottom area of 70% or more of the cross section of the container to perform aeration.

[0006]

[Function] The function of the present invention will be explained below with reference to FIG. The device in FIG. 1 has the same basic configuration as the device in FIG. 6 shown earlier, but differs only in the shape of the container 2, with the aeration plate 3 at the bottom having a size close to the top of the container. The horizontal projected area of the entire aeration plate 3 is S1
, the area of the maximum cross section of container 2 is S2, and the ratio is x=
S1 /S2 ×100 (%) was defined, and a pressure-feeding experiment was conducted in which powder was sent out from two containers with maximum dimensions (diameter) of 1150 mm and 2300 mm, with various dimensions of the aeration plate at the bottom. The components of the fine powder used were NaCO3: 61%, CaO
: 5%, SiO2: 1%, total carbon 8%, iron oxide 25
%, water content is 0.22%, the shape is a mixture of aggregates of fine particles of about 0.5 μm and needle-shaped crystals of several tens of μm, and the bulk specific gravity is 0.22 t/m3.

[0007] The experimental conditions are shown in Table 1, and the experimental results are shown in FIG.

[0008]

[Table 1]

As can be seen from FIG. 2, when x<70%, 80 to 90% of the charged fine powder remained in the container. This situation will be considered using the schematic diagram of FIG. The pressurized gas 4 discharged from the aeration plate 3 passes through the powder layer directly above the region a as upward bubbles, interstitial flow, or fluidized bed. Since the powder is stirred at this time, the pressure in this area is relatively uniform and high. Next, in region b near the outside, ventilation is maintained by the gas that diffuses laterally from region a, and the state is similar to region a. On the other hand, in the further outer region c, there is no passage of pressurized gas, and because the powder is fine and has poor air permeability, the pressure inside the powder tends to be lower than the surrounding region when pressurized. be. Therefore, the powder in region c is compressed by the surrounding pressure and consolidated into a lump. When such fine powder is pumped, the powder in areas a and b easily comes out, but almost all of the powder in area c remains.

On the other hand, in the range of x≧70%, most of the powder in the container falls into areas a and b, so there are no lumpy residues, and only a small amount of soft residue that does not pose a problem in actual operation. I was able to cut out almost the entire amount except for.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a perspective view of a preferred embodiment of the present invention. The one in this figure is shown in Figure 2 of the dimensions listed in Table 1.
This method performs aeration by supplying pressurized gas from a wide bottom area that covers more than 70% of the cross section of the container, which has shown good results. FIG. 3 shows another embodiment in which the shapes of the container and the aeration plate are changed. first (
In a), the dimensions of the aeration plate are larger than the top of the container, and in (b), the dimensions of the aeration plate are 2 times above and below.
(c) is one in which a plurality of aeration devices are combined to increase the effective area.

[0012] Regarding these, we have compared various types of aeration equipment such as perforated plates, canvas cloth, and perforated nozzles regarding the materials and structures of the aeration equipment. It was found that this effect can be obtained. Incidentally, a similar problem occurred in the case of fine powder in the case of a type in which cutting is performed by a rotary feeder that performs pressure feeding without using an aeration device, but as shown in Fig. 4, based on the idea of the present invention, a container When an aeration pipe 11 of a predetermined area was attached to the front surface of the bottom, complete discharge was possible. 14 is a rotary feeder, and 15 is a pressure equalizing pipe.

[0013]

[Effects of the Invention] As explained above, according to the present invention,
It has become possible to pneumatically transport fine powder, which was previously considered impossible, and it can bring many benefits to various manufacturing industries, including the chemical industry, such as cost reduction and effective use of waste.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the configuration of an embodiment of the present invention.

FIG. 2 is a graph of experimental results showing the effective range of the present invention.

FIG. 3 is a side view showing another embodiment of the present invention.

FIG. 4 is a sectional view showing still another embodiment of the present invention.

FIG. 5 is a schematic cross-sectional view of a conventional container.

FIG. 6 is a sectional view showing a conventional technique.

[Explanation of symbols]

1 Powder 2 Container 3 Aeration plate 4 Pressurized gas 6 Nozzle pipe 7 Transport piping 8 Carrier gas

Claims (2)

[Claims] [Claim 1] After charging fine powder into a container and sealing the container, pressurized gas is sent and the fine powder is sent into a transportation pipe by a pressure difference, and dispersed in the carrier gas so that the inside of the pipe is at a pressure higher than atmospheric pressure. 1. A pneumatic transportation method for fine powder, which is characterized in that a pressurized gas is supplied from a bottom region having an area of 70% or more of the horizontal cross section of the container. [Claim 2] After charging fine powder into a container and sealing the container, pressurized gas is sent and the fine powder is sent into a transportation pipe due to a pressure difference, and dispersed in the carrier gas so that the inside of the pipe is at a pressure higher than atmospheric pressure. A device used for a pneumatic transportation method in which fine powder is pumped under pressure, characterized by being equipped with an aeration device that supplies pressurized gas over a bottom area that is 70% or more of the horizontal cross section of the container. A pneumatic transport device for fine powder.