JP2000189917A - Blasting method for inside surface of piping and almost blocking piece used in blasting operation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blasting method by which a collision force of cleaning abrasives against foreign matters is increased, thereby efficiently removing the foreign matters. SOLUTION: In the blasting operation, the pressurized air is fed into one end of this piping 1, into which the cleaning abrasives are to be fed, or the cleaning abrasives are made to pass through the piping 1 by sucking the air 2 inside this piping 1 from the remaining other end, and simultaneously, an almost blocking piece 10 is transferred within the piping 1 by being pressed by the air 2 or the cleaning abrasives passed through the piping 1, thereby causing a local pressure fluctuation in the air 2 passing through a gap formed between the inside surface of the piping 1 and the external size of the almost blocking piece 10, whereby the collision force of the cleaning abrasives against the foreign matters is increased by this pressure fluctuation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for removing foreign matter (scale) adhered to the inner surface of various pipes by sending a polishing material (sand, gravel, ballast, etc.) from one end of the pipe, and polishing the inside of the pipe. The present invention relates to a method of blasting an inner surface of a pipe for scraping off foreign matter while a cleaning material moves, and a substantially closing tool used for blasting operation.

[0002]

2. Description of the Related Art Various foreign substances adhere to the inner surface of a pipe over time in a transport pipe (also referred to as a transport pipe, hereinafter referred to as a transport pipe) for transporting powder or granules using air or flowing a liquid containing solid matter. However, there is a problem in that the pipe diameter is gradually narrowed, and the purpose of the above-mentioned transportation and distribution cannot be sufficiently achieved. This problem is unavoidable due to the usage form of the pipe, and can be easily solved by replacing the pipe portion having a reduced pipe diameter. However, from the viewpoint of reducing the cost of using piping,
It is preferable to temporarily stop transportation and circulation and clean the inner surface of the pipe. Thus, various cleaning methods have been conventionally proposed.

[0003] In general, a cleaning method is used in which an abrasive is fed from one end of a pipe, and the abrasive is moved in the pipe to remove foreign matter (a blast method, a cleaning operation using this method). Blast work, the same applies hereinafter). Many conventional proposals mainly relate to the improvement of the blasting method. For example, in Japanese Patent Application Laid-Open No. 6-270065, an intake blower is connected to a pipe (steel pipe), and the secondary air sucked by the intake blower is swirled by a fan, so that not only the flow direction but also the abrasive material moving according to the air can be swirled. In addition, a blast method for removing foreign matter (scale) by giving a movement in a direction perpendicular to the circulation, that is, a turning direction, is proposed.

[0004]

The removal of foreign matter by the abrasive material flowing through the pipe is performed by causing the abrasive material to collide with the foreign matter and scraping off the foreign matter from the inner surface of the pipe by the action of the impact force of the abrasive material against the foreign matter. It uses the physical phenomenon called.
Therefore, the higher the impact force of the abrasive material on the foreign matter, the more effectively the foreign matter can be removed. However, many of the conventional blasting methods, the abrasive material is sent from one end of the pipe, and air is sent from the same direction, or the air flow in the pipe is realized by means of either suction or suction from the other end, Only the abrasive material was allowed to flow through the pipe with the flow of the air. For this reason, if the piping is too long, the circulation of air is not good, and the collision force of the abrasive material cannot be increased unless either the feeding or suction of air is excessively increased. This has led to an increase in the size and cost of the air feeding or suction device used for the blasting operation.

[0005] Further, it is not possible to simply increase the air supply or suction. This is because increasing the air supply or suction increases the impact force of the abrasive on foreign matter, increases the flow rate of the abrasive, and shortens the passage time of the abrasive, which contributes to the removal of foreign matter, through the pipe. Would. This would require a large amount of abrasive material. JP-A-6-2700 exemplified above
No. 65 extends the time for the abrasive to pass through the pipe by dividing the direction of movement into the direction of circulation and the direction of rotation while increasing the speed of movement of the abrasive. However, only the fan for turning the abrasive material is provided at one end of the pipe, and the turning motion may be weakened before reaching the other end. If so, not only does the effective removal of foreign matter by the swirling motion weaken, but also the problem of speeding up the abrasive material emerges again. Therefore, a method and an auxiliary tool for increasing the impact force against foreign materials without increasing the size of the device, making it possible to efficiently feed or intake air by reducing the size of the device, and increasing the distribution speed of the abrasive material without increasing the size are considered. It was decided to.

[0006]

Means for Solving the Problems The thing developed as a result of the study, in order to remove foreign matters sticking to the inner surface of various pipes, sends an abrasive material from one end of this pipe and distributes the abrasive material through the pipe. At the time of blast work to scrape off foreign substances, pressurized air is sent to one end of this pipe that sends the abrasive material, and the air in this pipe is sucked from the other end to distribute the abrasive material through the pipe. This is a method of blasting the inner surface of a pipe in which the flow speed of the abrasive material is increased by a pressure difference between both ends to increase the collision force of the abrasive material against foreign matter. After all, the flow rate of the abrasive material is proportional to the pressure difference between both ends of the pipe. In the blast method of the present invention, one end is pressurized and the other end is depressurized to create a large pressure difference, thereby increasing the flow speed of the abrasive material, and thereby increasing the collision force of the abrasive material against foreign matter. Although the devices required for pressurization and decompression are small, the obtained pressure difference can be increased.

Next, a blast method for locally increasing the collision force while suppressing the circulation speed was developed. During the blasting operation, pressurized air is sent to one end of this pipe for sending the abrasive material, or the air in this pipe is sucked from the other end to allow the abrasive material to flow through the pipe and substantially block. The tool is moved in the pipe by pushing it with air or abrasive material flowing in the pipe, and air passing through a gap formed by the inner surface of the pipe and the outer shape of the substantially obturator causes local pressure fluctuation, and this pressure fluctuation causes This is a method of blasting the inner surface of the pipe to increase the impact force of the abrasive on foreign matter.

In this blast method, a venturi tube-like flow path is formed in a part of the pipe with a gap having a reduced pipe diameter as a “throat” due to the presence of a substantially obstruction member moving in the pipe. The pressure fluctuation caused locally by air passing through the gap increases the impact force of the abrasive. Since the collision force of the abrasive material is increased in addition to the pressure due to the flow speed, the flow speed itself can be kept low. For this reason, only either air feeding or suction may be used, or both may be used in combination to use a smaller device. In addition, the local increase in the collision force before and after the gap
Compared to the conventional method in which the collision force is substantially constant over the entire area of the pipe, there is a feature that the grinding action of removing foreign substances due to the collision of the abrasive material is more effectively exhibited.

[0009] As an example of the substantially closing device used in the blasting operation, three or more support portions having a concentric circular outer shape slightly smaller than the pipe diameter and in contact with the inner surface of the pipe at substantially the same distance protrude from the circular outer shape. When the abrasive is circulated through the pipe, a structure in which air passing through a gap formed by the inner surface of the pipe and the circular outer shape locally causes a pressure fluctuation can be given. In the present invention, the pipe cannot be deformed,
Also, since the gap corresponding to the "throat" in the flow path of a venturi tube must move sequentially, the "throat" with a circular outer shape close to the inner surface of the pipe, that is, a substantially obstructing device having a structure that forms the gap Used. The simplest configuration of the substantially obstructing device is a disk shape, but the substantially obstructing device has an excessively high resistance to air supply or intake. For this reason, it is preferable to provide front and rear conical portions that are smoothly continuous toward the maximum outer shape. In this case, if the upstream side of the air is long and the slope is gentle, the downstream side is short and the slope is tight,
More desirable air pressure fluctuation can be realized. Further, it is preferable that the wire is slowly pulled out from the upstream side of the movement so that the wire can be slowly moved so that the wire can be moved slowly.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the configuration of an apparatus showing a blasting operation in which foreign matter stuck to the inner surface of the pipe 1 is removed by using the blast method of the present invention (for convenience of explanation, the scale of the pipe 1 and each apparatus is different. FIG. 2 is an enlarged perspective view of a portion A in FIG. 1, and FIG. 3 is a cross-sectional view showing the flow of air 2 in the portion A (for convenience of explanation, the tilting legs 3 and wires 4 which are support portions in the drawing). Is omitted, FIG.
See). In this example, the abrasive material and the pressurized air are sent from the right end of the pipe 1, and the abrasive material that has flowed while being sucked in from the left end of the pipe 1 is collected together with the foreign matter.

As shown in FIG. 1, a tank truck 5 loaded with an abrasive is connected to a right end of a pipe 1 by a flexible hose 6, and a compressor capable of sending compressed air to the flexible hose 6. 7 is connected. If the pipe 1 is too long and air cannot be circulated just by suction from the other end, pressurized air is supplied from the compressor 7 to increase the pressure difference between both ends of the pipe 1 so that the smooth air in the entire area of the pipe 1 can be obtained. To ensure circulation. At the left end of the pipe 1, a tank car 8 for collecting the polishing material that has flowed through the pipe 1 is connected by a flexible hose 6, and a suction device 9 is connected to the tank car 8. Mainly, the circulation of the air and the cleaning material is based on the circulation of the air by the suction device 9.

As shown in FIG. 2, the substantially obturator 10 in this embodiment includes a cylindrical portion 11 having a concentric circular outer shape and a front and rear conical portion.
It has a structure in which 12 and 13 are provided integrally, and is pulled by a wire 4 extending from the right end of the pipe 1. The cylindrical portion 11 is provided with four tilting legs 3 having a roller 14 attached to a tip thereof at equal intervals in a circumferential direction as supporting portions. The tilting leg 3 tilts substantially toward the upstream side in the moving direction of the obturator 10, but is urged in the rising direction so that the roller 14 can always contact the inner surface of the pipe 1. A constant gap S is formed all around. Further, in this example, the cover 15 is disposed on the upstream side in the flow direction of the air 2 so that the air 2 does not collide with the tilting leg 3 and generate unnecessary air resistance.

The traction by the wire 4 is performed by the air 2 and the abrasive material.
(Omitted in FIG. 2, circulates integrally with air).
Move slowly according to the feeding. In the present invention, the impact force of air 2 passing through the gap S formed by the substantially obturator 10 with respect to the inner surface of the pipe 1 locally increases the collision force of the abrasive to grind foreign matter. This is why the position control of the substantially closing device 10 is important. Traction by the wire 4 is a means for simply and sufficiently realizing the position control of the obturator 10.

Air is sucked from the left end of the pipe 1 and pressurized from the right end of the pipe 1 if necessary, so that the air 2 flowing through the pipe 1 causes the abrasive to flow through the pipe 1. The flow of the abrasive material is the same as that of the conventional blasting method, and the abrasive material collides with the foreign matter adhered to the inner surface of the pipe 1 and is ground and removed. As shown in FIG. 3, the air 2 and the cleaning material thus circulated reach the substantially obturator 10 and are gradually compressed along the front conical portion 12 toward the inner surface of the pipe 1. As a result, the flow speed of the air 2 (abrasive material) decreases, but the density of the air 2 increases, and as a result, the pressure of the air 2 locally increases (point P1).

When the pressure of the air 2 has been increased, the air 2 has been passed through the gap S formed by the inner surface of the pipe 1 and the circular outer shape of the cylindrical portion 11, and is then released at a stretch along the rear conical portion 13.
(Point P2), the pressure drops sharply, and the distribution speed sharply increases instead. Then, the abrasive material transported to the air 2 is affected by the pressure fluctuation and the speed change, and collides with a foreign substance (a scale attached to the inner surface of the pipe 1) with a high collision force different from other places. This increase in the local impact force of the abrasive material realizes effective foreign matter removal according to the present invention. In addition, since the effective foreign matter removal according to the present invention occurs substantially along the obstruction 10 as is clear, the entire obstruction 10 is moved slowly in the pipeline 1 by slowly moving the obstruction 10 within the pipeline 1. Therefore, the effect of removing foreign substances can be spread throughout.

[0016]

EXAMPLE A blast operation was actually carried out with the configuration shown in FIG. The pipe is a stainless steel 6-in. Pipe used for the outflow device of about 80 m, and gypsum adheres to the inner surface of the pipe as a foreign substance. A tank truck of abrasive material was connected to the right end of this pipe via a flexible hose of about 40 m. Further, a tank truck of the abrasive was connected to the left end of the pipe via a flexible hose of about 30 m, and a suction device was further connected to the tank truck. The suction amount was 120 m ³ / min., And the static pressure at the left end of the pipe during the blasting operation was 550 mHg. When blasting was performed for about 45 minutes under these conditions, about 40% of the foreign matter was recovered. Further, the use of the substantially obturator shown in FIG. 2 improved the recovery rate to about 60%. In each case, it was proved that the recovery rate of foreign substances was improved as compared with the conventional blasting method.

[0017]

According to the blasting method of the present invention, air and abrasive can be circulated in a pipe at a sufficient circulating speed without increasing the size or cost of the apparatus. This realizes a high impact force of the abrasive material on the foreign matter, removes the foreign matter better, and achieves the desired cleaning of the inner surface of the pipe. In addition, the equipment required to carry out the present invention can be easily procured and can be kept inexpensive, so that there is no cost. Further, from the viewpoint of work, since the arrangement of each device and the tank truck with respect to the pipe is symmetric, there is an advantage that the blast operation can be efficiently and repeatedly performed by appropriately arranging the air compressor and the suction device.

[0018] Furthermore, the use of the substantially obturator makes it possible to grind and remove foreign matters more effectively while keeping the air compressor and the suction device unchanged. Since it is sufficient that the diameter of the substantially closing device can be reduced, it is not always necessary to make the gap formed in relation to the inner surface of the pipe constant. For this reason, the same substantially obturator can be applied to many pipes having different pipe diameters, and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is an apparatus configuration diagram showing an implementation state of a blast operation.

FIG. 2 is an enlarged perspective view of a portion A in FIG.

FIG. 3 is a cross-sectional view illustrating a flow of air in a portion A.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piping 2 Air 3 Tilt leg 4 Wire 5 Tank truck loaded with abrasive material 6 Flexible hose 7 Compressor 8 Tank truck for collecting abrasive material 9 Suction device 10 Substantially closing tool 11 Cylindrical part 12 Front cone part 13 Rear cone part 14 Roller 15 Cover S Clearance P1 Area upstream of cylindrical part P2 Area downstream of cylindrical part

Claims (3)

[Claims] In order to remove foreign matter adhered to the inner surface of various pipes, an abrasive material is sent from one end of the pipe, and the abrasive material is removed during the blasting operation to remove foreign matter while flowing the abrasive material through the pipe. The pressurized air is fed into one end of the pipe, and the air in the pipe is sucked from the other end to flow the abrasive material through the pipe. A method for blasting the inner surface of a pipe, wherein the blasting material has an increased impact force against foreign matter. 2. In order to remove foreign matter adhered to the inner surface of various pipes, an abrasive material is fed from one end of the pipe, and the abrasive material is removed at the time of a blast operation of scraping off foreign matters while flowing the abrasive material through the pipe. And pressurized air is fed into one end of the pipe, or air in the pipe is sucked from the other end to allow the abrasive to flow through the pipe, and the air or air through which the substantially obturator flows through the pipe. Pressing with a cleaning material to move the inside of the pipe, air passing through a gap formed by the inner surface of the pipe and the substantially obturator outer form causes a local pressure fluctuation, and the pressure fluctuation increases the impact force of the abrasive material against foreign matter. A method for blasting the inner surface of a pipe. 3. A blasting operation on an inner surface of a pipe, in which an abrasive material is fed from one end of the pipe to remove foreign matter adhered to the inner surface of the various pipes and scrapes off foreign matter while flowing the abrasive material through the pipe. , Having a concentric circular outer shape slightly smaller than the pipe diameter, and projecting from the circular outer shape three or more supporting portions that are in contact with the inner surface of the pipe at substantially equal distances, when flowing the abrasive material through the pipe. A substantially closing tool used for blasting, characterized in that air passing through a gap formed between the inner surface of the pipe and the circular outer shape causes a local pressure fluctuation.