JPS58216829A - Distributing method of particulate material pneumatically conveyed - Google Patents

Abstract

PURPOSE:To contrive to enhance accuracy in distributing a particulate material and to reduce the abrasion of a distributor or the like, by a method wherein a particulate material being pneumatically conveyed is mixed by agitating in an expanding pipe having a specified shape, the concentration of the material is made to be uniform in a straight pipe having a specified length, and then it is directed into the distributing pipes. CONSTITUTION:The expanding pipe 2-1, the straight pipe 2-2 and the distributing pipes 2-3 are connected to a main pipe 1 for pneumatically conveying a particulate material, through flanges 2-4-2-6, to constitute the distributor 2. The expanding pipe 2-1 has a bend angle theta of 8-180 deg. and an expansion ratio on an inside diameter basis of not lower than 1.3. The length of the straight pipe 2-2 is set to be 3-50 times of the open end diameter on the outlet side of the expanding pipe 2-1. The particulate material pneumatically conveyed through the main pipe 1 is expandingly dispersed in the pip 2-1, is mixed by agitating therein, the concentration thereof is made to be uniform by forming a uniform suspended particle layer in the straight pipe 2-2, and is uniformly distributed into the plurality of distributing pipes 2-3.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for transporting granular materials such as pulverized coal or coke powder by pneumatic flow and evenly distributing them from a transport pipe to a plurality of branch pipes.

In the pneumatic transportation of powder and granular materials such as pulverized coal and coke powder, the conventional method of distributing the pneumatically transported powder and granular materials to multiple locations is to install a Y-shaped fw or T-shaped pipe in the middle of the transportation main pipe. A method for distributing and supplying powder and granular materials by installing them in a cascade.■ A dividing pipe is provided on the top surface of a cylindrical dispersion chamber, and the powder and granules transported by airflow from the bottom collide with the top surface of the dispersion chamber. A method of distributing and supplying radially,
(2) There is a method in which a fluidized bed of granular material is formed and the granular material is flowed out from the upper part of the fluidized bed through a plurality of overflow pipes.

However, methods (■) and (2) both utilize collisions and reflections against the inner surface of the branch W or the inner surface of the dispersion chamber, but they have the disadvantage of low distribution accuracy due to insufficient uniformity of powder dispersion. In addition, there were disadvantages in that the equipment was subject to significant wear and pressure loss due to impinging flows. Furthermore, method (2) has the disadvantage that it requires skill to operate, as the fluidization conditions of the powder vary considerably depending on the type and particle size, as well as differences in surface conditions due to weather, etc. .

This invention was made in order to solve the above-mentioned drawbacks of the conventional method, and provides a distribution method that improves the distribution accuracy of pneumatically transported powder and granules, reduces wear on the distributor, and reduces pressure loss. This is a proposal.

That is, this invention has an expansion angle of 8 to 180 degrees, a ratio of the inner diameters of the entrance side and the exit side (hereinafter referred to as F expansion ratio) of 1.8 or more,
An expanding tube having a cross-sectional area such that the average gas flow velocity is equal to or higher than the transport limit speed of powder and granular material, and a diameter of 8 to 8 mm at the outlet end of this expanding tube.
Using a distributor consisting of a straight y having 50 times the length and a plurality of distribution pipes communicating with the outlet side of the straight pipe, the flow of powder and granular material transported by air current is expanded and dispersed in the expanding pipe part. This method of distributing powder and granules is characterized in that they are stirred and mixed, then rectified in a straight pipe section to make the concentration of the powder and granules uniform in the circumferential direction, and then guided to each distribution pipe opening.

In air flow transportation of powder and granular materials, in order to evenly distribute the flow rate of the powder and granular materials, it is essential to equalize the powder concentration within the distributor. In the transportation main π before reaching the distributor, not only in the case of horizontal pipes, but also in vertical pipes, the powder concentration at the cross section of the pipe is affected by bends in the upstream, and there is considerable deviation. arise. In the conventional distribution method, the unavoidable imbalance in the concentration of powder and granules within the transport pipe is not fully resolved before the powder is sent to the distribution pipe or transport branch pipe, so the distribution accuracy is very high. Only about 80% was obtained.

The main feature of this invention is that the concentration of the powder and granules is made uniform by stirring and mixing the powder and granules by the turbulence of the airflow and the generation of vortices caused by enlarging the flow path.

This invention method will be explained below with reference to the drawings.

FIG. 1 shows an example of a distributor based on the method of the present invention, in which (1) is a main air flow transporting pipe for powder and granules, and (2) is an expansion tube (2- 1), Straight pipe (
2-2) and a distribution pipe (2-8), which is connected to the transportation main pipe (1) via a flange joint (2-4), and also includes a distribution pipe (2-8). is 7 lunges (2-
5), and is connected to the straight pipe (2-2) via a flange (2-6) that is integrally attached to the straight pipe (2-2).

This invention expands the above! As (2-1), the expansion angle θ=8 to 180° and the expansion ratio based on the inner diameter=1.8 or more are used. The reason is as follows.

In other words, when the spreading angle θ is small, the distribution pipe (2-,
Due to the number of pipes taken in l), the pipe dimensions have to be lengthened, which is disadvantageous in terms of space.Furthermore, at the wind speed (5 to 50 m/sec) in normal air transport, the expansion angle θ is 8.
If it is smaller than 0.0°, there will be less airflow turbulence and less vortex formation, which will result in poor agitation and mixing of the powder and granular material.

Furthermore, when the spreading angle θ is larger than 180°, the shape of the distributor becomes complicated, and the stirring and mixing action of the powder remains the same as when θ=180°. In addition, wear due to powder at the inlet of the Shima expansion tube is caused by the expansion angle θ-1
It tends to become larger at 50°.

In addition, the reason why the expansion ratio is set to 1.8 or more is because the pressure loss when air or water is flowed in a commercially available reducer etc. decreases rapidly when the expansion ratio is 1.3F or more, resulting in less turbulence in the airflow. This is because the mixing effect of powder and granules cannot be expected.

The diameter (cross-sectional area) of the expanding tube is such that the average speed of the conveying air flow does not exceed the limit transport speed of the powder by F times.

For the above reasons, in this invention, the expansion angle θ of the expansion tube is
was set to 8 to 180°, and the enlargement ratio was set to 1.3 or more.

Next, the straight tube (2-2) connected to the downstream side of the expansion tube (2-1) is provided to further stir and mix the powder particles dispersed by the expansion tube to achieve a uniform concentration. The length varies depending on conditions such as the particle size, specific gravity, shape of the powder and the flow rate and pressure of the carrier electric material, but the length is between 8 and 8 mm, which is the diameter of the outlet end of the expansion tube (1-1). A length of 50 times is appropriate.

This means that in order to achieve a more uniform concentration of the expanded and dispersed powder in the expansion tube (2-1), the length of the straight tube must be at least 8 times or more, and the length of the straight tube must be at least 50 times the diameter. This is because when the length increases, particularly in the case of fine powder particles, the particles dispersed in the expansion tube may flow in a concentrated manner, resulting in poor distribution accuracy.

As described above, in the case of this distributor, the powder and granules that have been air-transported in the transport main pipe (1) flow into the enlarged 'f (2), and at the same time are expanded and dispersed and stirred and mixed.

Subsequently, after a uniform suspended particle layer is formed in the straight pipe (2-2) and the concentration of the powder is made uniform, a plurality of distribution pipes (2-2) opened in the straight pipe (2-2) are formed. -8
) is evenly distributed.

Figure 2 was obtained by the inventors using a distributor with the structure shown in Figure 1 to experimentally determine the relationship between the spread angle θ of expansion 'If (2-1) and the absolute value of the distribution error. This is the result. The diameter of the transportation main pipe (1) is 41.5ffφ, and the diameter of the expansion pipe (2
-1) Outlet opening end diameter 80φ (constant).

Expansion ratio 2 (constant), spreading angle 3 to 210°, straight "If (2-2) length 1.8 mm (constant), distribution pipes (2-8) with inner diameter of 200 x 6 pieces were used. Powder material is pulverized coal (average particle size 70 μm) Powder material carrier gas is nitrogen Cb
Nd1 min, 2 kL1/cd-G). The distribution error is a value calculated using the following formula.

From Figure 2, when the length of the straight tube is fixed and distribution is made by varying the expansion angle θ of the expanding tube, the distribution error is 10 inches or more when the expansion angle θ is 8 degrees or less, whereas the distribution error is 8 degrees or more. It can be seen that the distribution error decreases to 5 degrees and becomes a substantially constant value above .degree.

Next, under the same experimental equipment and transportation conditions as above, the size of the expansion tube was kept constant and the length of the straight tube was varied to examine the distribution error. The results were as shown in FIG. The expansion tube used had an expansion angle θ=80° and an outlet opening end diameter of 80° (expansion ratio 2).

From FIG. 8, it can be seen that the distribution error is minimized when the length of the straight tube is 8 to 50 times the diameter of the outlet opening end of the expanding tube.

Next, embodiments of the invention will be described.

〔Example〕

FIG. 4 shows the results of flow rate distribution in pneumatic transport of pulverized coal and coke powder using the distributor shown in FIG. 1. The dimensions and transportation conditions of the transport main distributor in this example were as shown below.

CI) Transport wood charge and dimensions of the distributor Transport main pipe: Inner diameter 41.5 ff Expansion pipe: 41.5 so-called XSO, expansion ratio 2. Straight pipe with 80° spread angle: 80 mm inner diameter x 1000 mm long Piping: 20 mm inner diameter x 6 pipes (II) As is clear from Figure 4 of the transport conditions, the distribution error is the same for coal powder (
(O mark) within ±5%, and in the case of coke powder (△ mark) within ±22 inches, which was very small, and almost even distribution was achieved. In addition,
Conventionally, as described above, a distribution accuracy of only about 80% could be obtained at most.

As explained above, according to the method of the present invention, it is possible to make the concentration of powder and granule uniform in the distributor, so it is possible to significantly improve the tolerance accuracy for the flow rate of powder and granule. Since the path is straight and there is no bend in the flow, pressure loss can be reduced and wear on the distributor can be prevented.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an example of a distributor based on the method of the invention, Fig. 2 is a chart showing the relationship between the expansion angle of the expanding tube and the distribution error in the same distributor, and Fig. 8 is a straight tube in the same distributor. Chart showing the relationship between length and distribution error, Part 4
The figure is a chart showing the distribution accuracy in an embodiment of the present invention. 1... Transport main pipe, 2... Distributor, 2-1... Expansion pipe, 2-2... Straight pipe, 2-8... Distribution pipe,
2-4°2-5.2-6...7 lunges. Applicant: Sumitomo Metal Industries, Ltd.

Claims (1)

[Claims] In air flow transportation of powder and granular materials, the cross-sectional area has a spread angle of 8 to 180°, a ratio of the inner diameter of the inlet and outlet sides of 1.8 or more, and an average gas flow velocity that is equal to or higher than the transport limit speed of the powder or granular material. Expansion π
air flow transport using a distributor consisting of a straight tube having a length 8 to 50 times the diameter of the outlet opening end of the expanding tube, and a plurality of distributors communicating with the outlet side of the straight tube. The powder and granules to be mixed are expanded and dispersed in the enlarged π section, stirred and mixed, and then the straight pipe section makes the concentration of the powder and granules uniform in the circumferential direction, and each portion is guided to the tube opening. Method for distributing powder and granular materials by pneumatic transport.