JP2007197190A - Powder transport device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a powder transport device capable of smoothly extracting powder to an external part from a silo, while sufficiently exhibiting storage capacity of the silo and transport capacity of a powder transport device, by preventing progress of compaction and sedimentation of the powder in the silo, in the powder transport device for extracting the powder from the silo storing the powder such as a cement raw material and a cement product. <P>SOLUTION: This powder transport device is provided for extracting the powder from a bottom part 14 of the silo. A gas injection means 5 having an injection port for injecting gas upward, is arranged in an upper part of the transport device. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a powder transport apparatus for stably extracting powder from a silo in which powder such as cement raw material or cement product is stored.

In recent years, large silos have been installed to store powder, and as a device for extracting powder from this large silo, air sliders are often used as long transport devices that can be easily extracted from the bottom. ing. For example, Patent Document 1 describes an air slide conveyor used when carrying out a powder such as cement stored in a silo.
JP-A-6-48567

Examples of use of commonly used air sliders are shown in FIGS. When extracting powder from a large silo, many air sliders 1 such as comb-shaped teeth are installed in parallel near the bottom 14 of the silo, which is often a bowl-shaped cylinder. The The air slider 1 has a gentle inclination angle (4 to 8 degrees) that allows the powder to flow, and is arranged so as to cover the entire cross section near the bottom 14 of the silo. In general, a cylindrical silo has a group of air sliders arranged in a half-moon-like comb shape on the left and right sides, and finally passes through the collective transporter 12 after the air slider is pulled out in the middle of the bottom 14 of the silo. The powder is pulled out from the silo. This collective transport 12 passes through a tunnel 13 for collective transport provided in the lower part of the silo. Each air slider 1 is inclined toward the collective transporter 12 so that powder flows.

Next, the structure of the conventional air slider 1 is shown in FIG. About the length in the silo of the air slider 1, it has the length of about 80 to 100 dimension% of the linear distance from the silo inner surface of the tunnel wall 16 for collective transport aircraft to the outer wall 10 of the silo. Further, the air chamber 2 is provided at the lower part of the air slider, the cloth canvas 3a or the porous plate 3c installed on the air chamber 2, the punching plate 3b, the lid 3d and the like. The lid 3d does not exist inside the silo, but exists inside the tunnel 13 for the collective transport from the tunnel wall 16 for the collective transport. A punching plate 3b is placed over the upper surface of the cloth canvas 3a or the porous plate 3c. The punching plate 3b is for preventing the cloth canvas 3a from being damaged by the powder pressure in the silo. Air, which is a transportation power source of the air slider, is introduced into the lower air chamber 2 by blower air blown from outside the silo, and passes upward through the gap between the cloth canvas 3a or the porous plate 3c and the punching plate 3b. Are released into the silo. The air blown upward from the air chamber 2 in the air slider causes the powder in the silo to flow on the top surface of the air slider, and the cohesive force and frictional force between the powder particles are greatly reduced, so that the powder is in the air. Float. As a result, the powder is fluidized and circulates on the air slider like a liquid and is extracted from the silo.

Since the powder is discharged in a bowl shape as shown in FIG. 11, the powder remains in the silo (shaded portion 9). Thereafter, when a new powder is introduced into the silo, the height of the powder stack increases, so that the residual powder is consolidated and hardened. In particular, in a large silo having a powder stacking height of 20 to 50 meters, hardening due to powder compaction occurs remarkably.

Since the hardened powder stays inside the silo, it cannot be pulled out. It also significantly reduces silo storage capacity. Therefore, the transportation device must be periodically stopped, and the hardened powder must be manually crushed and removed with a tool such as a pick. For this reason, the transport efficiency of the powder has been reduced. Moreover, the removal work by human power has a risk of dust scattering and collapse of the accumulated powder, and requires a huge cost. For this reason, there were problems in workability and economy.

In addition, in the conventional air slider, a large number of air sliders are arranged at the bottom of the silo so as to ensure as wide an area as possible. However, hardening by powder compaction also occurs on the air slider at the bottom of the silo. For this reason, the air slider may be blocked and the powder may not be extracted at all. As a result, 30 to 60% of the air sliders installed at the bottom of the silo are operating in a closed state, and it cannot be said that the air slider's transport capacity is fully demonstrated. It was.

This invention solves the said subject, and makes it a subject to provide the powder transport apparatus for extracting powder stably from the silo in which powder, such as a cement raw material and cement products, was stored.

According to the present invention, in a powder transportation apparatus for extracting powder from the bottom of a silo, gas injection means having an injection port for injecting gas upward is provided at the top of the transportation apparatus. Is a powder transport device characterized by

According to the present invention, it is possible to prevent the progress of powder compaction and deposition in a silo. Further, the fluidized powder can be guided to the inlet 4 of the air slider. As a result, the powder can be smoothly extracted from the silo to the outside. In addition, it is possible to dramatically improve the transportation efficiency related to the reception and discharge of the powder while making full use of the transportation capability of the air slider.
In addition, the silo storage capacity can be effectively utilized. Furthermore, it is possible to reduce the frequency of the powder removal operation, which is very advantageous from an economic viewpoint.

The present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic side view of a silo equipped with a powder transport device according to the present invention. FIG. 2 is a plan view of a silo provided with a large number of semicircular comb-shaped powder transport device groups according to the present invention.
The silo referred to in the present invention refers to a storage tank for storing powder or the like, and includes, for example, a tank, a hopper and other storage tanks. The powder that can be transported in the powder transport device of the present invention includes, in addition to cement raw materials mainly composed of limestone powder, related products such as cement, coal ash (fly ash), calcium carbonate powder, Examples include slag powder, silica powder, and other dusts.

Examples of the powder transport apparatus used in the present invention include air sliders, screw conveyors, vertical table conveyors and other positive displacement conveyors. Hereinafter, an air slider will be described as an example. Note that the structure of the air slider 1 is the same as that shown in FIGS.

  On the upper part of the air slider 1, there is provided gas injection means 5 provided with an injection port for injecting gas upward of the silo. An example of the gas injection means 5 is a metal tube. The metal tube may have any shape such as a circle or a square. The inner diameter of the metal tube is preferably 25 to 50 millimeters. The injection port has an opening at the top of the metal tube as shown in FIG. The tip of the metal tube is preferably conical. As a result, the metal tube can be smoothly inserted into the powder. Examples of the gas include air and nitrogen. The metal pipe fixing method, which is the gas jetting means 5, is fixed by providing a flange pipe on the wall of the tunnel 13 for the collective transport machine, and the support by gravity or the like is fixed to the mechanical end of the air slider. May be. By using the gas slider together with the air slider, it is possible to facilitate fluidization of the powder inside the silo and to smoothly extract the powder to the outside of the silo. Further, the number of expensive air sliders can be reduced and the length can be shortened. For example, when the length of the air slider 1 is L, the length L is 40 to the linear distance from the silo inner surface of the tunnel wall 16 to the outer wall 10 of the silo by using the gas injection means together. The length can be 60% by dimension.

As shown in FIG. 5, a plurality of gas injection means 5 can be installed in parallel in the vertical direction. The number of jetting means per transport device can be appropriately changed depending on the length and width of the transport device, but is preferably 1 to 4. When the width of the air slider 1 is large, the fluidity of the powder is made uniform by increasing the number of ejecting means.

For example, in the present invention, when the width of the air slider 1 is 25 centimeters or less, the number of ejection means is preferably 2. However, when using powder having adhesion or cohesion, the number of injection means can be increased to four.
Here, FIG. 6 and FIG. 7 show the case where three jetting means are installed per transport device. As shown in FIG. 7, two metal pipes of the jetting means 5 are installed in parallel in the longitudinal direction so as to be mounted in contact with both ends of the punching plate 3b which is the upper surface of the air slider 1, and the air pipe is placed above the transport device. One is installed at a position away from the slider 1. It is also possible to change the length of the gas injection means installed above and below. The gas injection means close to the air slider can be made longer by using the mechanical support around the air slider as compared with the gas injection means installed at a distant position.

It is preferable that the gas injection means is installed at a position 0.1 to 4 times higher than the width of the transport device. Here, the width (D) of the transport device refers to the length of the air slider in the short direction. When the gas injection means 5 is installed at a position having a length exceeding four times the width of the transport device, it is not preferable because the powder clogging may proceed between the air slider 1 and the injection means 5.

The length of the gas injection means 5 should be 0.8 to 2 times the longitudinal length (L) of the air slider 1 in consideration of powder fluidization, economy, construction and maintenance. preferable. Also, as shown in FIG. 2, the length of the air slider and the gas injection means can be the same from the center of the tunnel 13 for the collective transport to the outer wall 10 of the silo. . The lengths of the air slider and the gas injection means near the both ends of the tunnel 13 for the collective transport aircraft are relatively shorter than the central portion. Thus, while the length of the conventional air slider is along the arc of the silo as shown in FIG. 9, it can be made into a short comb shape by the present invention, and maintenance is also performed. It is also advantageous in terms of economy.

Next, the injection port 6 provided in the gas injection means 5 will be described in more detail with reference to FIG. 3 taking a metal tube as an example.
The injection port 6 for injecting gas toward the upper part of the silo is provided in the upper part of the metal pipe installed in the silo. The cross-sectional shape of the injection port 6 is preferably circular, but may be elliptical or polygonal. Further, an injection nozzle may be installed at the injection port 6. The injection port 6 is provided at the top of the metal tube or at a 45 degree position, preferably at a 45 degree position.

For example, when the length of the metal tube is 3 meters, the number of the injection ports 6 arranged in one metal tube is preferably 3 to 10. The inner diameter of the injection port is preferably 5 to 15 millimeters. When a plurality of injection ports are provided at a place other than the top of the injection means, they can be provided symmetrically or alternately. Thereby, it becomes possible to inject gas evenly on the upper part of the silo, and the powder can be smoothly introduced into the air slider 1 without causing hardening due to compaction of the powder. The interval between the injection ports 6 is 70 to 400 millimeters.

The direction of the injection port is not particularly limited, but preferably has an angle of 20 to 90 degrees from horizontal to upward.

Further, the injection port 6 preferably has a backflow prevention structure as shown in FIGS. 3-5b and 3-5c. The backflow prevention structure refers to a structure that prevents the powder in the silo from entering the gas injection means from the injection port 6 of the gas injection means. Specifically, a backflow prevention element 7 is provided at the injection port 6. The backflow prevention element 7 has a structure in which the tip of the injection port 6 is covered in FIGS. 3-5b. 3-5c has a structure in which an injection port 6 is provided at the tip of the injection port in an oblique direction with respect to the gas injection means 5, and a plug is attached to the tip of the injection port 6. As shown in FIG. 4, the thickness of the backflow prevention element 7 through which the gas passes is 1 to 5 millimeters, and the backflow prevention element 7 is fitted into the injection port 6 like the injection pipe 5b and welded. Alternatively, it may be a pressing type with an external screw. The material of the backflow prevention element 7 is a material in which metal, ceramics, cloth, etc. are knitted and has a stitch that allows gas to pass through. If the powder does not flow back in large quantities, a fine porous plate or the like can pass through the gas. Any material is acceptable. Alternatively, a structure in which the backflow prevention element 7 is screwed into the injection port 6 as in the injection pipe 5c may be used. Thereby, it is possible to prevent the powder from being mixed into the metal tube and blocked.

The pressure of the gas to be injected is about 20 to 120 kilopascals at the gauge pressure at the base of the gas pipe in the tunnel 13 for the collective transport machine. Further, it is necessary to secure the tip flow velocity of the gas at the injection port of 5 to 45 meters / second. The gas supply source is a compressor or a blower. When the atmosphere is used as a gas, it is desirable to perform dehumidification in advance. As a result, the powder particles adhere and aggregate due to moisture in the atmosphere to form a lump, which is blocked in the inlet 4 of the air slider or the air slider 1 and stably removes the powder from the silo. Can be prevented from becoming impossible.

As described above, the powder group near the inlet 4 of the air slider is fluidized by the gas ejected from the ejection port 6. As a result, in the powder group, the gas is interposed between the particles, whereby the frictional resistance between particles and the cohesiveness between the particles are reduced, and the fluidity as the powder group is improved. In this way, the powder group can flow smoothly and stably.

By this method, when the powder is extracted from the silo, a stable extraction amount of 50 to 300 tons / hour can be ensured per one air slider.

  The present invention can be used when powder is stably extracted from silos, tanks, hoppers and other storage tanks.

It is a schematic side view of the silo provided with the powder transportation apparatus in the present invention. It is a top view of the silo provided with many semicircular comb-tooth type powder transport apparatus groups in the present invention. It is detail drawing of the injection means of the gas in this invention. It is detail drawing of two types of backflow prevention elements by the gas injection means in this invention. It is another schematic diagram of the silo provided with the powder transport apparatus in the present invention. It is a top view of the powder transport apparatus provided with the injection means of the gas in this invention. Sectional drawing of the powder transport apparatus provided with the injection means of the gas in this invention is shown. It is a side view of the silo provided with the conventional powder transportation apparatus. It is a top view of the silo provided with many powder transportation device groups of the conventional half moon-like comb-tooth type. It is detail drawing of the conventional air slider type transport apparatus. It is a state figure which extracts powder from the conventional air slider type transportation device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Air slider 2 Air chamber 3a Cloth canvas 3b Punching plate 3c Porous board 3d Lid 4 Air slider entrance
DESCRIPTION OF SYMBOLS 5 Gas injection means 6 Injection port 7 Backflow prevention element 8 Powder flow locus 9 Powder compaction dead 10 Silo outer wall 11 Silo powder layer 12 Aggregate transport machine 13 Aggregate transport tunnel 14 Silo bottom 15 Welding 16 Tunnel wall for collective transport aircraft

Claims (7)

In the powder transport apparatus for extracting powder from the bottom of the silo, a gas injection means having an injection port for injecting gas upward is provided at the top of the transport apparatus. Powder transport device. 2. The powder transport apparatus according to claim 1, wherein one to four gas injection means are provided for each transport apparatus. 3. The powder transport apparatus according to claim 1, wherein the gas injection means is installed 0.1 to 4 times the width of the transport apparatus. 4. The powder transport device according to claim 1, wherein a length of the gas injection unit is 0.8 to 2 times a length of the transport device in a longitudinal direction. 5. The powder transportation apparatus according to any one of claims 1 to 4, wherein the number of the injection ports is three to ten. The powder transport device according to any one of claims 1 to 5, wherein the injection port has an angle of 20 to 90 degrees from the horizontal to the upper side. The powder transport apparatus according to claim 1, wherein the injection port has a backflow prevention structure.

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