Dust removal device and method

Abstract

To provide a dust removal device and method capable of scraping off dusts accumulated in a gap between cooling pipes in a cooling device of exhaust gases against resistance by adherence to an outer surface of the cooling pipes.SOLUTION: A dust removal device which scraps off dusts accumulated in a gap between cooling pipes that uses an endless annular body 2 in a cooling device for exhaust gases having a plurality of cooling pipes 1 includes: two scrapers 3 fitted to the endless annular body; a first rotating body 5 around which the endless annular body is wound and which is driven and rotates; and a second rotating body 6 which faces the first rotating body, is wound by the endless annular body 2, and rotates without being driven. The scrapers are provided with partition members arranged in each intra-column of the respective plurality of cooling pipes.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a dust removal device and method to be installed in an exhaust gas cooling device such as a gas cooler in a vacuum degassing facility for molten steel. [Background technology]

[0002] In the molten steel refining process, degassing treatments using vacuum such as RH, DH, and VOD are performed. During the vacuum degassing treatment, high-temperature exhaust gas is discharged from the vacuum degassing tank or treatment pit through a duct, and a cooling device called a gas cooler is installed to cool this exhaust gas. In the gas cooler, U-shaped water pipes are arranged in multiple branches from the 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.

[0003] During vacuum degassing operation, the evaporation of metal vapor and the bubbling of oxygen or 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 naturally fell off, 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 exhaust performance decrease in the equipment downstream of the gas cooler (exhaust gas outlet side), making it difficult to operate in good condition. In addition, when 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 decreases, the degassing treatment performance decreases, the treatment time is extended, and even the degassing treatment becomes impossible. Therefore, when a certain amount of dust accumulates on the surface of the cooling pipe of the gas cooler, the dust must be removed.

[0004] Under these circumstances, techniques have been proposed for removing dust accumulated in the gaps between the cooling pipes of a gas cooler (Patent Documents 1 and 2).

[0005] Patent Document 1 discloses a method for cleaning a gas cooler in which a plurality of gas spray nozzles are arranged in front of the gas cooler (on the exhaust gas inlet side) and an inert gas is sprayed onto the gas cooler.

[0006] 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 tube of the gas cooler is provided in the gas cooler of a vacuum degassing facility or in a duct adjacent thereto. 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. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 55-21554 [Patent Document 2] Japanese Patent Application Publication No. 10-183232 Summary of the Invention [Problem to be solved by the invention]

[0008] However, in the technology for removing dust by blowing gas as in Patent Documents 1 and 2, the gas does not directly hit the dust adhering to the surface of the cooling tube opposite the nozzle, making it difficult to remove, and there is a problem that the dust removal ability of gas blowing is insufficient for firmly attached dust.

[0009] 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.

[0010] The above-mentioned technique of mechanically scraping off dust with a scraper is considered to have a higher removal capacity than gas blowing. However, the scraper mainly removes dust by scraping off the dust as it descends, but the driving force of the driving means acts only in the upward direction of the scraper, and 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 is firmly attached to the extent that it can resist the scraper's own weight, there is a problem that it becomes difficult to remove dust from the area below that spot.

[0011] The present invention has been made to solve the above-mentioned problems, and has an object to provide a dust removal device and method that is capable of scraping 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. [Means for solving the problem]

[0012] The inventors conducted intensive research to solve the above problems, and as a result, they discovered that by applying the driving force of the driving means to the downward side of the scraper as well, it is possible to scrape off even dust that is so firmly attached that it can resist the scraper's own weight. Further research led to the creation of the present invention.

[0013] 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 is driven 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 removal device described in [1], characterized in that the endless ring body is made of a wire rope, a chain or a combination thereof. [3] The dust removal device described in [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 removing device according to any one of [1] to [5], wherein the exhaust gas is exhaust gas discharged from a vacuum degassing facility for molten steel. [7] The dust removing 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] A dust removal device as described in [8], characterized in that the guide comprises a half pipe or an angle.

[10] A dust removal method using a dust removal device described in any one of [1] to [7], characterized in that the second rotor applies tension to the endless ring-shaped 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 rotor 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 moving the two scrapers in opposite directions. Effect of the Invention

[0014] According to the present invention, when applied to a gas cooler of vacuum degassing equipment for molten steel (where the straight pipe sections of multiple cooling pipes are vertical), a driving force can be generated in the scraper not only in the upward direction but also in the downward direction, making it possible to mechanically remove even dust that is so firmly attached that it cannot be removed by the scraper's own weight.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. [Brief description of the drawings]

[0015] [Figure 1] 1 is a side view showing an overview of one example of an embodiment of the present invention. [Diagram 2] FIG. 2 is a three-dimensional view corresponding to FIG. [Diagram 3] FIG. 1 is a side view showing an overview of another example of an embodiment of the present invention. [Figure 4] FIG. 4 is a three-dimensional view corresponding to FIG. [Diagram 5] FIG. 13 is a schematic three-dimensional diagram of yet another example of an embodiment of the present invention. [Figure 6] FIG. 2 is a side view showing an overview of a comparative embodiment to the embodiment of FIG. [Figure 7] FIG. 7 is a three-dimensional view corresponding to FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The following describes the embodiment of the present invention by giving some examples. In the following examples, the dust removing device of the present invention is applied to a gas cooler of a vacuum degassing facility for molten steel.

[0017] Fig. 1 is a side view showing one example of an embodiment of the present invention, and Fig. 2 is a three-dimensional view corresponding to Fig. 1. In the illustrated example, only the main parts of a gas cooler (cooling device) are shown.

[0018] Among the vacuum degassing equipment for molten steel, RH and DH are equipment that performs vacuum degassing by circulating molten steel contained in a ladle or the like in a vacuum tank. VOD is equipment that performs vacuum degassing by storing the entire ladle containing molten steel in a chamber and reducing the pressure in 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 pipe 1 has straight pipe sections 1S on both sides of a U-shaped section 1U, one of which is a water supply side and the other is a drainage side, with the water supply side being the upstream side in the direction of exhaust gas flow (the inlet side of exhaust gas) and the drainage side being the downstream side (the outlet side of exhaust gas). The number of cooling pipes 1 is usually 15 to 25 per row of multiple cooling pipes 1 arranged in the direction of exhaust gas flow (referred to as 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 about 600 to 900 mm in the row direction, 2000 to 2500 mm in the horizontal arrangement direction of the rows, and about 2600 to 2800 mm in the height direction.

[0019] The present invention is a dust removal device that uses an endless annular body 2 to scrape off dust accumulated in the gaps between the cooling pipes 1 in an exhaust gas cooling device having a plurality of cooling pipes 1.

[0020] The dust removing device of the present invention comprises the endless annular body 2, two scrapers 3, a first rotating body 5 and a second rotating body 6.

[0021] 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 Fig. 1, the endless ring body 2 is made of a wire rope.

[0022] 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 is cut and the two cut ends are connected to the scrapers 3 to make it endless, or the endless ring body 2 is not cut and is connected to the scrapers 3 by a fastening jig or the like (not shown).

[0023] The scraper 3 is equipped with partition members 7 arranged between each row of the cooling pipes 1. Here, the row refers to a row of the cooling pipes 1 arranged in the direction of the exhaust gas flow (row direction) as described above, and the space between the rows refers to the gap between adjacent rows.

[0024] 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 annular body 2. The frame 4 also contributes to scraping off the dust.

[0025] As the partition member 7, a rod, a flat plate, or a combination of these is preferable from the viewpoints of being easily available and easy to assemble the scraper 3. The same applies to the frame 4. From the viewpoint of scraping ability, a flat plate as exemplified in FIG. 2 is more preferable.

[0026] When the partition member 7 is a flat plate, it is preferable to incline this plate with respect to the surface of the cooling pipe 1 (see FIG. 5), as this allows dust closer to the surface of the cooling pipe 1 to be scraped off, improving dust removal capability.

[0027] Moreover, 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). It is preferable from the viewpoint of the stability of the movement of the scrapers 3 that the number of cooling pipes 1 per row of the multiple rows that each scraper is responsible for is approximately the same and the weights of the two scrapers 3 are approximately equal. For example, when 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 when 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).

[0028] When it is difficult to stabilize the posture of the scraper 3 when attached to only one endless ring body 2, the scraper 3 is attached to two or more endless ring bodies 2. In the example of Figs. 1 and 2, there are two endless ring bodies, one end (one of both ends in the width direction or length direction) of the frame 4 of the scraper 3 is connected to one of them, and the other end (not shown) is connected to the other one.

[0029] The first rotating body 5 is a member around which the endless ring body 2 is wound to drive it to rotate, and a pulley or gear is preferably used for this from the viewpoint of smoothly moving the wound endless ring body 2 in the rotational direction. Note that 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 for 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 driving the rotation.

[0030] The second rotor 6 is a member that faces the first rotor 5 and rotates without being driven by wrapping the endless annular body 2 around it, and like the first rotor 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 rotor 6.

[0031] 1 and 2, the first rotor 5 is located above the cooling pipe 1, and the second rotor 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 annular body 2 between the upper and lower positions. Note that the positions of the first and second rotors 5 and 6 may be interchanged.

[0032] In addition, in correspondence with the two endless ring bodies 2 as described above, there are two first and two second rotating bodies 5, 6 each on the same axis, and one and the other of these two rotating bodies are used to wind one and the other of the two endless ring bodies, respectively.

[0033] 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 annular body 2 and the second rotor 6 which rotates without being driven by the tension of the endless annular body 2. The transmitted driving force causes the scraper 3 to rise or fall, and the partition members 7 arranged between the rows of the cooling pipes 1 scrape off the dust, thereby removing the dust.

[0034] Therefore, a driving force can be generated in the scraper 3 not only in the upward direction but also in the downward direction, so that even dust that is so firmly attached that it cannot be removed by the scraper 3's own weight can be mechanically removed.

[0035] This dust removal effect is particularly pronounced when the exhaust gas is discharged from a vacuum degassing facility for molten steel, and therefore the present invention is preferably applied to this case.

[0036] Moreover, Fig. 3 is a side view showing another example of the embodiment of the present invention, and Fig. 4 is a three-dimensional view corresponding to Fig. 3. In this example, the second rotating body 6 in the example of Fig. 1 is replaced with a curved guide 9 along which the endless annular body 2 slides.

[0037] 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 of the endless ring body 2, it is more preferable to use a half pipe.

[0038] In particular, it is preferable to bend both longitudinal ends of the guide 9 inward at a greater curvature than the central portion, from the viewpoint of preventing the guide ends from getting caught on the wire or chain.

[0039] Also, it is preferable to use the guide 9 instead of the second rotor 6, since dust adhering to the endless annular body 2 can be scraped off and removed by the guide 9.

[0040] In addition, in correspondence with the two endless ring-shaped bodies 2 as described above, there are two first rotating bodies 5 on the same axis, and there are two guides 9 at approximately the same height position, one of which is used to wrap around one of the two endless ring-shaped bodies and the other is used to wrap around the other of the two endless ring-shaped bodies, respectively.

[0041] Incidentally, when the guide 9 is used, similarly to the case of the second rotor 6, it is preferable that the partition member 7 of the scraper 3 is a flat plate and this flat plate is inclined with respect to the surface of the cooling pipe 1. An example of this configuration is shown in FIG.

[0042] 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 while driving the first rotating body 5 to rotate and rotating the second rotating body 6 without being driven, thereby moving the two scrapers 3 in opposite directions.

[0043] Another method is to use a guide 9, apply tension to the endless ring-shaped body 2 with the guide 9 while driving and rotating the first rotating body 5 to slide the endless ring-shaped body 2 against the guide 9, and move the two scrapers 3 in opposite directions.

[0044] This allows the partition member 7 and the frame 4 to effectively scrape off dust that has accumulated in the gaps between the cooling pipes 1 .

[0045] The endless ring body 2 attached to the underside of the scraper 3 is preferably set to a length that is not subjected 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 possibility that abnormal snagging may occur, so the length is set so that the endless ring body 2 fits within the guide 9.

[0046] 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 finished, 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 their standby positions and the drive rotation of the pulley is stopped to prepare for the next operation of the vacuum degassing equipment.

[0047] This makes it possible to repeatedly operate the vacuum degassing equipment while avoiding abnormal increases in exhaust gas temperature and poor ventilation downstream of the gas cooler due to dust accumulation in the gas cooler. EXAMPLES

[0048] In a gas cooler (cooling device for exhaust gas) of a vacuum degassing facility for molten steel, the present invention was embodied in the form illustrated in FIG. 3, and this was 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 interval 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 rotor 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 lifting range of the scraper 3 was set to a position 110 mm below the upper end of the area where the cooling pipe 1 was installed, and the lower limit was set to a position 300 mm above the lower end of the same area.

[0049] When removing dust, the dust removal 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. The dust removal device of the comparative example was the same as the example of the present invention, except that the guide 9 and the endless ring body 2 below the scraper 3 were removed and the endless ring body 2 above the scraper 3 was used as a connecting body 10. In the comparative example, two scrapers 3 were 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 was not transmitted to the scraper 3 on the descending side, so that the dust was scraped off by its own weight alone.

[0050] The number of times the dust removal device failed to operate was averaged over 300 operating occasions for the inventive example and the comparative example, 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 for the inventive example was significantly reduced to 50, relative to the comparative example being 100, demonstrating a significant improvement in dust removal ability compared to the comparative example. [Explanation of symbols]

[0051] 1 Cooling pipe (U-shaped water pipe) 1S straight pipe section 1U U-shaped part 2 Endless ring 3. Scraper 4 Slots 5 First Rotating Body 6 Second Rotating Body 7 Partitioning material 9 Guide 10 Concatenation

Claims

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 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. 2. The dust removing device according to claim 1, wherein the guide is made of a half pipe or an angle.

3. 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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