JPH06286874A - Powder transport method by gas - Google Patents

Abstract

PURPOSE:To suppress clogging at a bent pipe part and enable highconcentration transportation to be carried out while preventing the wear of a transport pipe by performing gas transportation while supplying inert gas toward the axial center part of a bent pipe from the outer peripheral side in relation to the center-of-curvature of the bent pipe in the bent pipe on the way of a powder transportation line by gas. CONSTITUTION:The length part including a horizontal pipe 131.132 part or a vertical pipe 13,3 part of specific times as long as piping on the inlet-outlet sides of bent pipes 134.135, within a range of 1/2 of the circumference on the outer peripheral side in relation to the centerof-curvature of the bent pipes 134.135 is formed of a perforated plate 16 made of ductile iron, for instance, (35-50 blow holes of 0.15-0.3 in inner diameter are opened per 1cm<2>), and it is so formed that make-up inert gas can be supplied to this perforated plate 16 from make-up feed pipelines 181.182 fitted to a header 17 covering the perforated plate 16. As a result, pipeline clogging is not generated at the bent pipe 134.135 part, and stable transportation can be performed. In addition, high- concentation transportation can be performed by supplying make-up gas also to the horizontal pipe parts 131.132 and the vertical pipe 133 part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for pneumatically transporting powder.

[0002]

2. Description of the Related Art Conventionally, a belt conveyor, a screw feeder or the like has been used as a method for transporting powder, but when a belt conveyor is used, there is a problem that the powder is scattered during transportation. Therefore, it is necessary to take environmental measures, and when a screw feeder is used, there is a problem that powder is crushed during transportation. Therefore, recently, when the powder is transported, the gas transportation method is often adopted.

By the way, when the powder is transported by gas, if the internal pressure of the pneumatic tank becomes higher than the internal pressure of the transportation pipe, the carrier gas flows out of the tank due to the pressure difference. Runs out with powder. At this time, if the powder amount (solid-gas ratio) with respect to the carrier gas flow rate is large, it cannot be transported over a long distance, and although it depends on the transported powder, if the carrier gas flow rate is not more than 8 m / sec, the powder will not be transported. The body will not float and the piping will be blocked.

Therefore, the above problem is to be solved by adding a large amount of carrier gas in the vicinity of the outlet of the pneumatic tank. That is, keeping a constant solid-gas ratio,
If the powder is transported by gas at a flow rate above a certain level, the carrier gas flow in the transport piping stabilizes, and if the pressure in the pneumatic tank is maintained above the pressure loss in the piping that occurs at this time, stable transport is always achieved. It will be possible.

[0005]

However, the transportation pipe includes not only the straight pipe portion but also the curved pipe portion and the vertically rising pipe portion. In such a curved pipe portion, the powder collides with the inside of the pipe wall, so that the powder locally congests. However, if the congestion lasts for a long period of time, the congested portion becomes longer due to the powder that has been gas-transported from the upstream. As a result, the carrier gas is no longer vented, and eventually the piping becomes clogged. Therefore, in the curved pipe portion, it is important to reduce the frictional resistance between the powder and the pipe so that the powder does not become congested.

[0006] It is an object of the present invention to provide a method capable of suppressing the clogging of the pipe, particularly in the curved pipe portion, which occurs when the powder is transported by gas.

[0007]

[Means for Solving the Problems] Not all powders transported by gas are suspended in the pipe, and in the straight pipe 1a in the horizontal portion, as shown in FIG. A density distribution is generated in which the upper part (indicated by 2a in FIG. 3) is in a floating state (indicated by 2b in FIG. 3). On the other hand, in the curved pipe 1b, as shown in FIG. 4, the congestion portion 2 is located at a position downstream of the split position of the curved portion.
c is generated. Mainly the curved pipe section in the transportation pipe, as shown in FIG.
As shown in, the powder 2 is locally congested because the powder 2
Is caused by the frictional resistance generated when colliding with the inner wall of the pipe.

Therefore, as a method for alleviating this traffic congestion, it is sufficient to reduce the frictional resistance. For this purpose, additional gas is supplied at the inlet of the curved pipe portion where traffic congestion is likely to occur, and the powder collides. It is effective to form a film of an inert gas on the inner wall of the curved pipe portion to reduce the collision speed of the powder with the inner wall of the pipe, and further, as shown in FIG. That is, by transporting the gas (indicated by an arrow in FIG. 5) uniformly from the outer peripheral side to the axial center of the curved tube 1b with respect to the center of curvature of the curved tube 1b, the transportation powder is transported as much as possible. Can be prevented, that is, the contact resistance can be reduced. When the contact resistance decreases, there is no difference in the flow of powder between the curved pipe portion and the straight pipe portion, the congestion portion disappears, and high-concentration powder can be smoothly transported by gas.

Further, in the curved pipe portion, a turbulence of the flow is generated, and the turbulence also causes collision of the transport powder with the inner wall surface of the pipe. Since this gas turbulence is affected by the diameter of the pipe, it is effective to supply the gas from the inlet and outlet portions where the turbulence of the pipe begins to occur, and the length is determined by the inventor's experiments to find that the pipe diameter It is necessary to be about 5 times.

The present inventor has established the following invention based on the above findings. That is, the first aspect of the present invention is that, in the curved pipe portion in the middle of the powder gas transportation line,
A gas transport method for powders, characterized in that the powder is transported while supplying an inert gas from the outer peripheral side toward the axial center of the curved tube with respect to the center of curvature of the curved tube. Two
In the first gas transportation method, the powder gas transportation is characterized in that the inert gas is supplied to a length portion including a straight pipe portion having a pipe diameter of 5 times, on the inlet / outlet side of the curved pipe portion. Is the way.

[0011]

EXAMPLES Hereinafter, examples carried out to confirm the effects of the method of the present invention will be described. As shown in FIG. 2, the tank 12 receives an air feed tank 11, the vertical length 15m that connects the horizontal pipe 13 _1, 13 ₂ each length 50m These horizontal pipe 13 ₁ and 13 ₂ the pipe 13 ₃ and this vertical tube 13
Curved tube 13 ₄ connecting ₃ and the respective horizontal tubes 13 ₁ and 13 ₂
・ Using a transportation route connected by a transportation pipe 13 composed of 13 ₅ and a pressure gauge 14 _{1 at} the inlet of each curved pipe 13 ₄ 13 ₅
14 ₂ and carrier gas supply pipes 15 ₁ and 15 ₂ were provided, and a transportation test was conducted using coal having a water content of <3% and a grain size of <3 mm.

The structure of the curved tubes 13 ₄ and 13 ₅ at this time is shown in FIG.
As shown in Figure 1, the radius of curvature of the curved pipes 13 ₄ and 13 ₅ is 1/2 of the circumference on the outer peripheral side, and the curved pipes 13 ₄ and 1
At the entrance / exit side of 3 ₅ times the pipe diameter (test E),
Horizontal tube 13 _{1 with} 5 times (test F) and 10 times (test G)
13 ₂ parts, or the length part including the vertical tube 13 ₃ part, for example, the multi-pore plate 16 (inner diameter 0.
15 to 0.3 pores are formed by 35 to 50 pores per 1 cm ² ), and the multi-pore plate 16 is provided with a supply pipe from the supply pipes 18 ₁ and 18 ₂ attached to the header 17 that covers the multi-pore plate 16. It has a configuration capable of supplying active gas.

The transport pipe 13 used had a nominal diameter of 50 A and the carrier gas used was N ₂ gas. Further, 19 in FIG. 2 indicates a bag filter. Table 1 below shows various conditions of the transportation test and the results in that case.

[0014]

[Table 1]

Under the conditions shown in the test results A and B,
Eventually in unstable transport but pipeline clogging has occurred, the test result C~G of applying the present invention method the bent tube 13 ₄ - 1
Pipe clogging does not occur in ₃₅ parts, was possible stable transport. In addition, as shown in the test results F and G, the supply pipe 1
High-concentration transport is possible by supplying the supplementary gas to the horizontal pipe parts 13 ₁ 13 ₂ and the vertical pipes 13 ₃ before and after the inlet and the outlet of the curved pipes 13 ₄ 13 ₅ by using 8 ₁ 18 _2. But
Even if the length of these straight pipe portions is set to 5 times or more the pipe diameter, the effect is small.

Further, as a result of carrying out a transportation test of coal of 200 TON, the abrasion amount is 4.2 mm in the test result B, 4.1 mm in the test result D, 2.3 mm in the test result E, and 1.8 mm in the test result F. Result G is 1.8m
It was m. From this result, it can be seen that the present invention is effective.

[0017]

As described above, in the present invention, in the curved pipe portion in the middle of the powder gas transportation line, the inert gas is inactivated from the outer peripheral side with respect to the curvature center of the curved pipe toward the axial center portion of the curved pipe. Since gas is transported while supplying gas, when powder is transported by gas,
It is possible to effectively suppress clogging in the curved pipe section and enable high-concentration transportation. Furthermore, the method of the present invention is also effective against wear of transportation pipes.

[Brief description of drawings]

FIG. 1 is a view of a configuration of a curved pipe section for carrying out the method of the present invention.
It is a figure which shows an example, (a) is a figure which shows the front cross section,
(B) is a bb sectional view of (a).

FIG. 2 is a diagram showing an example of test pipes for carrying out the method of the present invention.

FIG. 3 is an explanatory diagram of a concentration distribution state of powder that is gas-transported in a straight pipe.

FIG. 4 is an explanatory diagram of a traffic jam condition of powder that is transported by gas in a curved pipe.

FIG. 5 is an explanatory diagram of a method of alleviating congestion of powder in a curved pipe.

[Explanation of symbols]

13 ₄・ 13 ₅ Curved pipe 16 Multi-hole plate 17 Header 18 ₁・ 18 ₂ Supply pipe

Claims (2)

[Claims] 1. In a curved pipe portion in the middle of a powder gas transportation line, gas is transported while supplying an inert gas from the outer peripheral side to the axial center portion of the curved pipe with respect to the center of curvature of the curved pipe. Characteristic powder gas transportation method. 2. The gas transportation method according to claim 1, wherein
A powder gas transportation method, characterized in that an inert gas is supplied to a length portion including a straight pipe portion having a diameter five times as large as a pipe diameter on the inlet / outlet side of the curved pipe portion.