JP7609124B2 - Dust removal device and method - Google Patents

Description

The present invention relates to a dust removal device and method that is installed in exhaust gas cooling equipment, such as a gas cooler in a vacuum degassing facility for molten steel.

In the molten steel refining process, degassing processes that utilize a vacuum such as RH, DH, and VOD are carried out. During the vacuum degassing process, high-temperature exhaust gas is discharged from the vacuum degassing tank or processing pit through a duct, and a cooling device called a gas cooler is installed to cool this exhaust gas. In a gas cooler, U-shaped water pipes are arranged in multiple branches from a cooling water header, with the U-shaped part at the bottom and the straight pipe part standing upright, and cooling water is passed through these cooling pipes to exchange heat with the high-temperature exhaust gas and cool the exhaust gas.

During vacuum degassing operation, the evaporation of metal vapor and the bubbling of oxygen and inert gas using a top blowing lance cause the molten steel to scatter, generating dust. This dust is discharged together with the exhaust gas, and some of the dust adheres to the cooling tubes of the gas cooler. There would be no problem if the dust attached to the surface of the cooling tubes fell off naturally, but in reality, the dust adheres firmly to the surface of the cooling tubes. When dust adheres, the heat exchange capacity of the cooling tubes decreases, and the exhaust gas temperature increases. When the exhaust gas temperature increases, various pipe deformations, sealing failures, and reduced exhaust performance occur in the equipment downstream of the gas cooler (exhaust gas outlet side), making it difficult to operate under good conditions. In addition, if a large amount of dust accumulates in the gaps of the cooling tubes of the gas cooler, the pressure loss of the exhaust gas in the gas cooler increases, the degree of vacuum during treatment deteriorates, the degassing treatment performance decreases, the treatment time is extended, and even degassing treatment becomes impossible. Therefore, when a certain amount of dust accumulates on the surface of the gas cooler's cooling pipes, the dust must be removed.

Under these circumstances, technology has been proposed to remove dust that has accumulated in the gaps between the cooling pipes of a gas cooler (Patent Documents 1 and 2).

Patent Document 1 discloses a method for cleaning a gas cooler in which multiple gas spray nozzles are placed in front of the gas cooler (on the exhaust gas inlet side) and an inert gas is sprayed onto the gas cooler.

Patent Document 2 discloses a dust removal device for a gas cooler, in which a lance having a nozzle for spraying a gas toward the surface of the cooling pipe of the gas cooler is provided in the gas cooler of a vacuum degassing facility or in an adjacent duct. The lance is on standby outside the gas cooler when not in use, and is loaded into the gas cooler when in use, so that an inert gas, _CO2 , steam, etc. is sprayed onto the gas cooler from a rotatable nozzle.

Japanese Unexamined Patent Publication No. 55-21554 Japanese Patent Application Publication No. 10-183232

However, in the technology for removing dust by blowing gas as in Patent Documents 1 and 2, the gas does not hit the dust attached to the surface of the cooling tube opposite the nozzle directly, making it difficult to remove, and there is also the problem that the dust removal capability of blowing gas is insufficient for firmly attached dust.

On the other hand, one possible technique for mechanically scraping off dust is to suspend two scrapers (scrapers) equipped with partition members that are placed between each row of cooling pipes from the top of the gas cooler on a pulley so that they can be raised and lowered in opposite directions, and to raise and lower the scrapers by rotating the pulleys alternately forward and backward using a driving means such as a motor, thereby raising and lowering the scrapers and scraping off the dust that has accumulated in the gaps between the cooling pipes.

The above-mentioned technique of mechanically scraping off dust with a scraper is thought to have a higher removal capacity than gas blowing. However, the scraper mainly removes dust by scraping it off as it descends, and the driving force of the driving means only acts in the upward direction of the scraper, while only its own weight acts in the downward direction. Therefore, if there is a spot on the outer surface of the cooling pipe where dust has adhered so firmly that it is unable to resist the scraper's own weight, there is a problem in that it becomes difficult to remove dust from the area below that spot.

The present invention has been made to solve the above problems, and aims to provide a dust removal device and method that can scrape off dust that has accumulated in the gaps between cooling pipes in an exhaust gas cooling device, overcoming the resistance caused by adhesion to the cooling pipe surface.

The inventors conducted extensive research to solve the above problems, and as a result, discovered that by applying the driving force of the driving means to the downward side of the scraper, it is possible to scrape off even dust that is so firmly attached that it can resist the scraper's own weight. After further research, they developed the present invention.

That is, the present invention is as follows.
[1] A dust removal device for scraping off dust accumulated in gaps between cooling pipes in an exhaust gas cooling device having a plurality of cooling pipes, comprising:
An endless annular body;
Two scrapers attached to the endless annular body;
a first rotor that is wound around the endless annular body and drives the endless annular body to rotate;
a second rotor facing the first rotor and wound around the endless annular body to rotate without being driven,
The dust removal device according to claim 1, wherein the scraper is provided with partition members disposed between each of the rows of the cooling pipes.
[2] The dust removing device according to [1], characterized in that the endless ring-shaped body is made of a wire rope, a chain or a combination thereof.
[3] The dust removal device according to [1] or [2], characterized in that the first rotating body is a pulley or a gear.
[4] The dust removing device according to any one of [1] to [3], wherein the partition member is made of a rod, a flat plate, or a combination thereof.
[5] The dust removal device according to any one of [1] to [3], wherein the partition member is made of a flat plate, and the flat plate is inclined with respect to the outer surface of the cooling pipe.
[6] The dust removal device according to any one of [1] to [5], characterized in that the exhaust gas is exhaust gas discharged from a vacuum degassing facility for molten steel.
[7] The dust removal device according to any one of [1] to [6], wherein the second rotating body is a pulley or a gear.
[8] The dust removal device according to any one of [1] to [6], characterized in that the second rotating body is replaced by a curved guide along which the endless annular body slides.
[9] The dust removing device according to [8], characterized in that the guide is made of a half pipe or an angle.
[10] A dust removal method using the dust removal device according to any one of [1] to [7], characterized in that the second rotor applies tension to the endless annular body while driving the first rotor to rotate and rotating the second rotor without being driven, and the two scrapers are moved in opposite directions.
[11] A dust removal method using the dust removal device described in [8] or [9], characterized in that the first rotating body is driven to rotate while applying tension to the endless ring-shaped body with the guide, causing the endless ring-shaped body to slide against the guide, and the two scrapers are moved in opposite directions.

According to the present invention, when applied to a gas cooler (where the straight pipe sections of multiple cooling pipes are vertical) in a vacuum degassing equipment for molten steel, it is possible to generate a driving force in the scraper not only in the upward direction but also in the downward direction, and even dust that is so firmly attached that it cannot be removed by the scraper's own weight can be mechanically removed. This not only enables stable operation of the vacuum degassing equipment, but also has the excellent effect of making it possible to extend the offline repair cycle of the gas cooler.

1 is a side view showing an overview of one example of an embodiment of the present invention; FIG. 2 is a three-dimensional view corresponding to FIG. 1 . FIG. 13 is a side view showing an overview of another example of an embodiment of the present invention. FIG. 4 is a three-dimensional view corresponding to FIG. 3 . FIG. 13 is a schematic three-dimensional diagram of yet another example of an embodiment of the present invention. FIG. 2 is a side view showing an overview of a comparative embodiment to the embodiment of FIG. 1 . FIG. 7 is a three-dimensional view corresponding to FIG. 6 .

The following describes some examples of the embodiments of the present invention. The following examples are examples in which the dust removal device of the present invention is applied to a gas cooler in a vacuum degassing facility for molten steel.

Figure 1 is a side view showing one embodiment of the present invention, and Figure 2 is a three-dimensional view corresponding to Figure 1. In the illustrated example, only the essential parts of the gas cooler (cooling device) are shown.

Among the vacuum degassing equipment for molten steel, the RH and DH are equipment that performs vacuum degassing by circulating the molten steel contained in a ladle or the like in a vacuum tank. The VOD is equipment that performs vacuum degassing by storing the entire ladle containing the molten steel in a chamber and reducing the pressure inside the chamber. The gas cooler is a device for cooling the exhaust gas discharged from these vacuum degassing equipment, and is equipped with a header (not shown) through which cooling water flows and cooling pipes 1, which are multiple U-shaped water pipes branching downward from the header. The cooling pipes 1 have straight pipe sections 1S on both sides of the U-shaped section 1U, one of which is the water supply side and the other is the drainage side, with the water supply side being the upstream side in the direction of the exhaust gas flow (the exhaust gas inlet side) and the drainage side being the downstream side (the exhaust gas outlet side). The number of cooling pipes 1 is usually 15 to 25 per row of multiple cooling pipes 1 lined up in the direction of the exhaust gas flow (called the row direction), and the number of rows is 4 to 6. The distance between the straight pipe sections 1S in one row is 90 to 120 mm. The dimensions of the arrangement area of the cooling pipes 1 are approximately 600 to 900 mm in the row direction, 2000 to 2500 mm in the horizontal direction of the row, and 2600 to 2800 mm in the height direction.

The present invention is a dust removal device that uses an endless ring-shaped body 2 to scrape off dust that has accumulated in the gaps between the cooling tubes 1 in an exhaust gas cooling device having multiple cooling tubes 1.

The dust removal device of the present invention comprises the endless ring body 2, two scrapers 3, a first rotating body 5, and a second rotating body 6.

The endless ring body 2 is a ring-shaped, long-chain member with no ends, and has an endless structure in which both ends of a long object with both ends are connected. The endless ring body 2 is preferably made of a wire rope, a chain, or a combination of these, which are widely used as tension transmission members. In the example of Figure 1, the endless ring body 2 is made of a wire rope.

The two scrapers 3 are dust scrapers and are attached to the endless ring body 2. As shown in the figure, the endless ring body 2 can be cut and the two cut ends can be connected to the scrapers 3 to make it endless, or the endless ring body 2 can be left uncut and connected to the scrapers 3 with a tightening jig or the like (not shown).

The scraper 3 is equipped with partition members 7 arranged between each row of multiple cooling pipes 1. Here, a row refers to a row of multiple cooling pipes 1 arranged in the direction of the exhaust gas flow (row direction) as described above, and a space between rows refers to the gap between adjacent rows.

The partition member 7 is a member that scrapes off dust that has accumulated between the rows. The partition member 7 is fixed to the frame 4, and the frame 4 is attached to the endless ring body 2. The frame 4 also contributes to scraping off the dust.

As the partition member 7, a rod, a flat plate, or a combination of these is preferred from the viewpoints that they are easily available and the scraper 3 is easy to assemble. The same applies to the frame 4. In terms of scraping ability, a flat plate is more preferred, as exemplified in Figure 2.

When the partition member 7 is a flat plate, it is preferable to tilt this plate with respect to the surface of the cooling pipe 1 (see Figure 5), as this allows dust closer to the surface of the cooling pipe 1 to be scraped off, improving dust removal capacity.

The two scrapers 3 are arranged one on the inlet side (meaning the upstream side in the direction of exhaust gas flow; same below) and one on the outlet side (meaning the downstream side in the direction of exhaust gas flow; same below). The number of cooling pipes 1 per row of the multiple rows that each scraper is responsible for is approximately the same, and it is preferable to make the weights of the two scrapers 3 approximately equal from the viewpoint of the stability of the movement of the scrapers 3. For example, if the total number of cooling pipes 1 per row is an even number (2N pipes), the number of pipes (N pipes) on the inlet side and the outlet side is the same, and if the total number of cooling pipes 1 per row is an odd number (2N-1 pipes), the number of pipes (N pipes) on the inlet side and the outlet side is one less than the other (N pipes and N-1 pipes).

When it is difficult to stabilize the scraper 3 by attaching it to only one endless ring body 2, it is attached to two or more endless ring bodies 2. In the example of Figures 1 and 2, there are two endless ring bodies, one of which is connected to one end of the frame 4 of the scraper 3 (one of both ends in the width direction or length direction), and the other end (not shown) is connected to the other.

The first rotating body 5 is a member around which the endless ring body 2 is wound and driven to rotate. A pulley or gear is preferably used for this, from the viewpoint of smoothly moving the wound endless ring body 2 in the direction of rotation. It is difficult to wind a wire rope around a gear, but a pulley is easy to wind both a wire rope and a chain around, so it is more preferable as the first rotating body 5. In the example of Figures 1 and 2, a pulley is used as the first rotating body 5. A motor (not shown) can be used as a driving source for the rotation.

The second rotating body 6 is a member that faces the first rotating body 5 and rotates without being driven by wrapping the endless annular body 2 around it. As in the case of the first rotating body 5, a pulley or gear can be preferably used, but a pulley is more preferable. In the example of Figures 1 and 2, a pulley is used as the second rotating body 6.

In the example of Figures 1 and 2, the first rotating body 5 is located above the cooling pipe 1, and the second rotating body 6 is located below the cooling pipe 1, and the upper and lower positions are fixed to the cooling device so that tension is applied to the endless ring body 2 between the upper and lower positions. Note that the positions of the first and second rotating bodies 5 and 6 may be interchanged.

In addition, in response to the two endless ring bodies 2 as described above, there are two first and two second rotating bodies 5, 6 on the same axis, and one and the other of these two are used to wrap around one and the other of the two endless ring bodies, respectively.

With the above-mentioned configuration, the driving force of the driving rotation of the first rotor 5 is transmitted to the scraper 3 via the endless ring 2 and the second rotor 6, which rotates without being driven by the tension of the endless ring 2. The transmitted driving force causes the scraper 3 to rise or fall, and the partition members 7 arranged between the rows of cooling pipes 1 scrape off the dust, thereby removing it.

Therefore, it is possible to generate a driving force in the scraper 3 not only in the upward direction but also in the downward direction, making it possible to mechanically remove dust that is so firmly attached that it cannot be removed by the scraper 3's own weight.

This dust removal effect is particularly pronounced when the exhaust gas is discharged from a vacuum degassing facility for molten steel, so the present invention is preferably applied to this case.

Figure 3 is a side view showing another example of an embodiment of the present invention, and Figure 4 is a three-dimensional view corresponding to Figure 3. In this example, instead of the second rotating body 6 in the example of Figure 1, a curved guide 9 is used to slide the endless ring body 2.

The guide 9 may be a half pipe or an angle that has been bent. In this bending process, the outer peripheral surface of the half pipe or angle is made to be the inward bending side. The endless ring body 2 is then wrapped around the inner peripheral surface that will be the outward bending side and slid. However, from the viewpoint of reducing the amount of wear on the endless ring body 2, it is more preferable to use a half pipe.

In addition, it is preferable to bend both ends of the guide 9 inward with a curvature greater than the curvature at the center, in order to prevent the ends of the guide from getting caught on the wire or chain.

In addition, it is preferable to use a guide 9 instead of the second rotating body 6, because the dust adhering to the endless ring body 2 can be scraped off and removed by the guide 9.

In addition, in order to accommodate the two endless ring bodies 2 as described above, there are two first rotating bodies 5 on the same axis, and two guides 9 at approximately the same height position, one and the other of these two guides are used to wrap around one and the other of the two endless ring bodies, respectively.

When using the guide 9, it is preferable to use a flat plate as the partition member 7 of the scraper 3, as in the case of the second rotor 6, and to incline this plate with respect to the surface of the cooling pipe 1. An example of this configuration is shown in Figure 5.

The dust removing method using the above-mentioned dust removing device of the present invention is as follows.
One method is to use a second rotating body 6, apply tension to the endless ring-shaped body 2 with the second rotating body 6, drive the first rotating body 5 to rotate, and rotate the second rotating body 6 without being driven, thereby moving the two scrapers 3 in opposite directions.

Another method is to use a guide 9, apply tension to the endless ring-shaped body 2 with the guide 9, drive the first rotor 5 to rotate, and slide the endless ring-shaped body 2 along the guide 9, moving the two scrapers 3 in opposite directions.

This allows the partition member 7 and frame 4 to effectively scrape off dust that has accumulated in the gaps between the cooling pipes 1.

The endless ring body 2 attached to the underside of the scraper 3 is preferably set to a length that is not subject to tension during normal operation in order to minimize friction with the guide 9. However, if it is made so long that it protrudes from the guide 9, there is a risk of abnormal snagging, so the length is set so that the endless ring body 2 fits within the guide 9.

The dust removing apparatus of the present invention can be operated, for example, in the following manner.
(a) The standby positions of the two scrapers 3 are set at the upper and lower end positions in the height direction of the installation area of the cooling pipe 1. (b) After the operation of the vacuum degassing equipment is completed, the pulley is driven to rotate and the two scrapers 3 are raised and lowered in opposite directions. (c) After several lifts and lowers are completed, the scrapers 3 are returned to the standby positions, the drive rotation of the pulley is stopped, and the vacuum degassing equipment is prepared for the next operation.

This allows the vacuum degassing equipment to be operated repeatedly while avoiding abnormal increases in exhaust gas temperature and poor ventilation downstream of the gas cooler due to dust accumulation inside the gas cooler.

In a gas cooler (exhaust gas cooling device) of a vacuum degassing facility for molten steel, the present invention was embodied in the form illustrated in FIG. 3, and used as an example of the present invention. The number of cooling pipes 1 was 5 in the row direction and 20 in the row horizontal direction, and the installation area was 2500 mm from the top to the bottom. The distance between the straight pipe sections 1S in one row was 100 mm. Of the two scrapers 3, the one on the entry side was responsible for 20 cooling pipes per row x 2 rows, and the one on the exit side was responsible for 20 cooling pipes per row x 3 rows. The frame 4 and partition member 7 of the scraper 3 were made of flat plates. The scraper 3 had a weight of 160 to 200 kg. A pulley was used for the first rotating body 5 of the scraper 3, and a half-split pipe was bent and used for the guide 9. A wire rope was used for the endless ring body 2, and the position of the pulley was fixed. The upper limit of the scraper 3's elevation range is 110 mm below the upper end of the area where the cooling pipe 1 is installed, and the lower limit is 300 mm above the lower end of the same area.

When removing dust, the dust removing device was operated according to the above-mentioned operating methods (a) to (c).
On the other hand, as a comparative example, a dust removal device in the form shown in Fig. 6 was used and operated in the same manner as in the example of the present invention. In the dust removal device of the comparative example, the guide 9 and the endless ring body 2 below the scraper 3 were removed from the dust removal device of the present invention, and the endless ring body 2 above the scraper 3 was used as a connecting body 10, but otherwise the dust removal device of the comparative example was the same as in the example of the present invention. In the comparative example, two scrapers 3 are suspended by a connecting body 10 (wire rope) with a first rotating body (pulley) as a fulcrum, and the driving force of the rotation of the pulley is not transmitted to the scraper 3 on the descending side, so that the dust is scraped off by its own weight alone.

The number of times the dust removal device failed to operate in the present invention example and the comparative example was averaged over 300 operating occasions, and the reciprocal of this average was used as the dust removal failure occurrence rate for comparison. As a result, the dust removal failure occurrence rate in the present invention example was significantly reduced to 50 relative to the comparative example, which was set at 100, demonstrating a significant improvement in dust removal ability compared to the comparative example.

1 Cooling pipe (U-shaped water pipe)
1S Straight pipe section 1U U-shaped section 2 Endless annular body 3 Scraper 4 Frame 5 First rotating body 6 Second rotating body 7 Partition member 9 Guide 10 Connecting body

Claims (3)

A dust removal device for scraping off dust accumulated in gaps between cooling pipes in an exhaust gas cooling device having a plurality of water pipes, comprising :
An endless annular body;
Two scrapers attached to the endless annular body;
a first rotor that is wound around the endless annular body and drives the endless annular body to rotate;
a curved guide that faces the first rotor and allows the endless annular body to slide ,
The scraper includes a partition member disposed in each gap between adjacent rows of the cooling pipes arranged in a row direction, which is a flow direction of the exhaust gas , and
3. A dust removing device, comprising: a partition member that is made of a flat plate and that is inclined with respect to an outer surface of the cooling pipe . 2. The dust removing device according to claim 1 , wherein the guide is made of a half pipe or an angle. 3. A dust removal method using the dust removal device according to claim 1 or 2 , characterized in that the first rotating body is driven to rotate while tension is applied to the endless ring-shaped body by the guide, causing the endless ring-shaped body to slide against the guide, and the two scrapers are moved in opposite directions.

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