Cover and exhaust port closing device

Abstract

To provide a lid body capable of reducing a welding amount during manufacturing and reducing a manufacturing cost, and an exhaust port closing device.SOLUTION: A lid body used to close an exhaust port in a treatment tank, has a spiral pipe conduit in which a fluid pipe having a membrane structure through which fluid flows is formed in a spiral shape. The spiral pipe conduit also has a water supply pipe part through which the fluid flows toward the center of the spiral pipe conduit, and a drain pipe part through which the fluid flows away from the center of the spiral pipe conduit. The water supply pipe part and the drain pipe part are alternately provided from the center of the spiral pipe conduit toward an outer edge.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a lid and an exhaust port closing device used for closing an exhaust port in a treatment tank.

Background Art

[0002] In the refining process of molten steel, a RH-type or DH-type vacuum degassing device (hereinafter also referred to as "treatment tank") is used to adjust the components of molten steel by treatment such as deoxidation. In the refining process of molten steel in the treatment tank, the treatment is performed by connecting an exhaust port provided in the treatment tank to an external exhaust device. Further, during the maintenance of the treatment tank, the connection between the exhaust port and the external exhaust device is released, and a lid is used to close the exhaust port in order to prevent radiant heat, high-temperature gas, etc. from flowing out from the inside of the treatment tank.

[0003] For the lid for closing the exhaust port, a plate-shaped member is used. Further, the lid is required to have heat resistance against heat loads received from radiant heat, high-temperature gas, etc., and conventionally, studies have been made on the application of a refractory lining, an internal cooling structure that enables the flow of cooling water, etc. For example, Patent Document 1 discloses a slide valve for a high-temperature gas pipeline that employs a jacket structure through which a cooling fluid can flow as a lid having heat resistance.

[0004] Further, the lid employs a membrane structure having a pipe for circulating a cooling fluid and a fin member for connecting a plurality of pipes. In this case, the pipes are composed of straight pipes and elbow pipes (bent pipes). Then, the cooling fluid is introduced from one outer edge portion of the lid, flows through all the straight pipes and elbow pipes, and is then led out from the other outer edge portion of the lid.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, lids lined with refractory material to ensure heat resistance will experience flaking over time, exposing the lid's main body (steel shell). This makes it difficult to maintain heat resistance over extended periods.

[0007] The lid described in Patent Document 1 employs a jacket structure, resulting in excellent cooling performance. However, to ensure the mechanical strength of the lid, it is necessary to increase the thickness of the fluid-flowing conduit. If the thickness of the conduit is increased, there is a problem in that the cooling performance decreases. Furthermore, in a configuration employing a jacket structure, while it is easy to repair damage to the surface of the lid when external stress is applied to the lid, it is difficult to repair internal damage due to the complexity of the jacket structure. In addition, the complexity of the structure presents problems in terms of manufacturing cost.

[0008] When employing a membrane structure that includes pipelines through which fluid flows and fin members connecting multiple pipelines, the use of numerous straight pipes and elbow pipes results in a large amount of welding during manufacturing, posing a problem in terms of manufacturing costs. Furthermore, due to the use of numerous elbow pipes, blockages in the pipelines may occasionally occur depending on the cleanliness of the flowing fluid. In addition, the fin members connecting multiple pipelines form recesses (indentations) on the pipeline surface, and dust and other particles accumulate over time. This leads to uneven heating due to the thermal effect of the accumulated dust, resulting in the problem of uneven thermal stress on the surface of the cover. Moreover, fin slits, which are provided to account for the difference in thermal expansion between adjacent straight pipes when the straight pipes are arranged to extend horizontally, also suffer from the problem of dust and other particles accumulating.

[0009] The present invention has been made in view of the above circumstances, and its object is to provide a lid and an exhaust port closing device that enable a reduction in the amount of welding during manufacturing and a reduction in manufacturing costs. [Means for solving the problem]

[0010] [1] A lid used to close an exhaust port in a processing tank, the lid having a spiral conduit formed by spirally shaped fluid tubes with a membrane structure through which fluid flows. [2] The lid according to [1], wherein the spiral pipeline has a water supply section through which the fluid flows toward the center of the spiral pipeline and a drainage section through which the fluid flows away from the center of the spiral pipeline, and the water supply section and the drainage section are alternately provided from the center of the spiral pipeline toward the outer edge. [3] The lid according to [1] or [2], wherein adjacent fluid pipes extending from the center of the spiral conduit toward the outer edge are joined to each other by welding. [4] The central part of the spiral conduit is a fluid tube with a jacket structure, as described in [3]. An exhaust port closing device having the cover described in [5][3]. [6] An exhaust port closing device, wherein the flange portion and the sealing portion are provided on the outer edge of the cover described in [3]. [Effects of the Invention]

[0011] According to the present invention, it is possible to reduce the amount of welding during manufacturing and lower manufacturing costs. [Brief explanation of the drawing]

[0012] [Figure 1] This figure shows a schematic diagram illustrating an example of the general structure of the lid of the present invention. [Figure 2] This figure shows a schematic partial cross-sectional view, which is an example of the general configuration of the fluid tube in the lid of the present invention. [Figure 3] This figure shows a schematic plan view of an example of the general configuration of the jacket tube provided in the center of the lid of the present invention. [Figure 4] This figure shows a schematic plan view of an example of the general structure of a conventional lid. [Figure 5] This figure shows a schematic partial plan view illustrating an example of the general configuration of a conventional straight pipe and elbow pipe with a cover. [Figure 6] This figure shows a schematic partial cross-sectional view, which is an example of the general configuration of the straight tube and fin section of a conventional lid. [Modes for carrying out the invention]

[0013] First, the configuration of the conventional cover 10 will be explained using Figures 4 to 6. Figure 4 shows a schematic plan view, which is an example of the general configuration of the conventional cover 10. Figure 5 shows a partial schematic plan view, which is an example of the general configuration of the straight pipe 12 and elbow pipe 13 of the conventional cover 10. Figure 6 shows a partial schematic cross-section, which is an example of the general configuration of the straight pipe 12 and fin section 14 of the conventional cover 10. Note that Figure 5 is a partially enlarged view of the general configuration of the straight pipe 12 and elbow pipe 13 shown in Figure 4. Figure 6 is a partial schematic cross-section of multiple straight pipes 12 in the general configuration of the cover 10 shown in Figure 4.

[0014] As shown in Figures 4 and 5, the conventional cover 10 has straight pipes 12 and elbow pipes 13 through which fluid can flow. The cover 10 employs a membrane structure that connects multiple adjacent straight pipes 12 to each other by interposing fin sections 14. However, because it uses a large number of straight pipes 12 and elbow pipes 13, the amount of welding required during manufacturing is large, which is problematic in terms of manufacturing costs. Also, because a large number of elbow pipes 13 are used, depending on the cleanliness of the flowing fluid, clogging of the pipeline (straight pipes 12 or elbow pipes 13) may occur from time to time.

[0015] Furthermore, in the lid 10, the cooling fluid is introduced from one outer edge of the lid 10 (the lower side in Figure 4), flows through all the straight pipes 12 and elbow pipes 13, and is then discharged from the other outer edge of the lid 10 (the upper side in Figure 4). As a result, an uneven temperature distribution occurs in the lid 10, which may lead to deformation and other damage as the usage time accumulates. Also, as shown in Figure 6, the fin section 14 that connects the multiple straight pipes 12 becomes a recess (indentation) on the surface of the straight pipes 12. As a result, dust and other particles accumulate on the surface of the fin section 14 as the usage time of the lid 10 accumulates. Therefore, uneven heating occurs due to the thermal effect of the accumulated dust, and there is a problem that non-uniform thermal stress occurs on the surface of the lid 10.

[0016] Next, embodiments of the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 shows a schematic diagram of an example of the schematic configuration of the lid body 1 of the present invention. FIG. 1(a) shows a plan schematic diagram of an example of the schematic configuration of the lid body 1 of the present invention. FIG. 1(b) shows a side schematic diagram of an example of the schematic configuration of the lid body 1 of the present invention. FIG. 2 shows a partial cross-sectional schematic diagram of an example of the schematic configuration of the fluid pipe 2 of the lid body 1 of the present invention. FIG. 3 shows a plan schematic diagram of an example of the schematic configuration of the jacket pipe 4 at the center O of the lid body 1 of the present invention. Note that FIG. 2 is a partial cross-sectional schematic diagram of a plurality of fluid pipes 2 with respect to the schematic configuration of the lid body 1 shown in FIG. 1.

[0017] The lid body 1 according to the present invention is used for closing the exhaust port in a treatment tank such as a vacuum degassing device. As shown in FIG. 1, the lid body 1 has a spiral pipe path 3 formed by spirally winding a fluid pipe 2 having a membrane structure through which fluid flows. That is, by bending the fluid pipe 2, which is a long pipe, a spiral pipe path 3 formed in a spiral shape can be manufactured. Therefore, it is possible to reduce the amount of welding and the manufacturing cost during the manufacture of the lid body 1 compared to the conventional lid body 10. Furthermore, since a bent fluid pipe such as an elbow pipe is not required, regardless of the cleanliness of the fluid flowing through it, the deposition of scale (fluid contents) inside the fluid pipe 2 can be suppressed, and as a result, clogging of the fluid pipe 2 can be prevented.

[0018] Also, as shown in FIG. 1, the spiral pipe path 3 includes a water supply pipe portion 3a in which the fluid swirls as the fluid flows through the fluid pipe 2 and heads toward the center (center O) of the spiral pipe path 3, and a drain pipe portion 3b in which the fluid swirls as the fluid flows through the fluid pipe 2 and moves away from the center (center O) of the spiral pipe path 3. Then, the water supply pipe portion 3a and the drain pipe portion 3b are alternately adjacent to each other from the center (center O) to the outer edge (outer edge portion S) of the spiral pipe path 3. Therefore, in all regions of the lid body 1, heat exchange always occurs between the low-temperature fluid flowing through the water supply pipe portion 3a and the high-temperature fluid flowing through the drain pipe portion 3b, enabling temperature uniformity in the lid body 1. And by suppressing the generation of a thermal stress difference caused by uneven heat, the deformation and cracking of the fluid pipe 2 can be prevented. That is, the heat resistance of the lid body 1 can be improved.

[0019] Furthermore, as shown in FIG. 2, a plurality of adjacent fluid pipes 2 are joined to each other by welding from the center to the outer edge of the spiral pipe 3. That is, compared with the fin portion 14 in the conventional configuration, the area and depth of the recesses (depressions) on the surface of the fluid pipe 2 can be reduced. For this reason, the deposition of dust on the surface of the lid 1 can be suppressed, and the generation of uneven heat caused by the thermal action of the dust can also be suppressed. In addition, since the plurality of adjacent fluid pipes 2 are the water supply pipe portion 3a and the drain pipe portion 3b in the spiral pipe 3, by joining the water supply pipe portion 3a and the drain pipe portion 3b to each other by welding, the effect of temperature uniformity in the lid 1 can be further improved.

[0020] Also, since a plurality of adjacent fluid pipes 2 are joined to each other, even when the thickness of the pipe member of the fluid pipe 2 is reduced, the strength of the lid 1 can be ensured. Specifically, the thickness of the pipe member of the fluid pipe 2 is preferably 4 mm or more and 5 mm or less. When the thickness of the pipe member of the fluid pipe 2 is less than 4 mm, with the increase in thermal stress caused by uneven heat, the occurrence of distortion and cracks in the fluid pipe 2, and damage due to wear and corrosion will be induced. Also, when the thickness of the pipe member of the fluid pipe 2 is greater than 5 mm, the temperature difference between the inner surface and the outer surface of the fluid pipe 2 becomes large, and due to the thermal stress caused by the temperature difference, cracks in the fluid pipe 2 are likely to occur, and the cooling capacity will decrease.

[0021] Next, the jacket pipe 4 in the central part O of the lid 1 will be explained. As shown in Figure 1, the central part O of the spiral pipeline 3 is composed of a jacketed fluid pipe (jacket pipe 4). As shown in Figure 3, the jacket pipe 4 has a partition plate 5, a guide section 6, a water inlet 7, and a drain outlet 8. The partition plate 5 and the guide section 6 define the flow path for the fluid circulating inside. The water inlet 7 is connected to the water supply pipe section 3a of the spiral pipeline 3 and receives the fluid supplied from the water supply pipe section 3a into the jacket pipe 4. The drain outlet 8 is connected to the drain pipe section 3b of the spiral pipeline 3 and allows the fluid that has circulated inside the jacket pipe 4 to flow into the drain pipe section 3b. In other words, the fluid supplied to the lid 1 circulates through the water supply pipe section 3a of the spiral pipeline 3, then through the jacket pipe 4, then through the drain pipe section 3b of the spiral pipeline 3, and is discharged to the outside.

[0022] The lid 1 may be manufactured by first bending a long fluid pipe 2 to produce the water supply pipe section 3a and the drain pipe section 3b in the spiral pipeline 3. Then, the lid 1 may be manufactured by combining the jacket pipe 4 with the spiral pipeline 3 (water supply pipe section 3a and drain pipe section 3b). Here, the fluid pipe 2 that is bent should preferably be about 5.5 m in length, taking into account the size (length of the pipe section) of the water supply pipe section 3a or the drain pipe section 3b. The outer diameter of the fluid pipe 2 should preferably be about 38.1 mm, taking into account the cooling capacity of the fluid flowing inside and the strength of the fluid pipe 2. The fluid pipe 2 should preferably be made of carbon steel boiler pipe, taking into consideration the material.

[0023] The above-described lid 1 may be applied to a vacuum degassing apparatus, which is a processing tank. Specifically, in order to close the exhaust port in the vacuum degassing apparatus, the lid 1 may be used to close the exhaust port by operating the exhaust port closing device in the vacuum degassing apparatus.

[0024] In this case, a flange portion and a sealing portion may be provided on the outer edge S of the lid 1. Specifically, a flange portion may be provided extending from the outer edge S in the direction from the center O of the lid 1 toward the outer edge S, and a sealing portion may be provided on the surface of the flange portion. The flange portion and the sealing portion may be made of heat-resistant rubber material or metal material (metal touch). By providing a flange portion and a sealing portion on the outer edge S of the lid 1, when the exhaust port is closed by the lid 1, the exhaust port can be sealed, and the outflow of radiant heat and high-temperature gases can be reliably prevented. [Examples]

[0025] The results of implementing the cover and exhaust port closing device according to the present invention will now be described. Specifically, first, several fluid pipes with an inner diameter of 38.1 mm were prepared, and the water supply pipe section and the drain pipe section were manufactured by bending these fluid pipes. Then, the cover was manufactured by combining the jacket pipe, the water supply pipe section and the drain pipe section. The diameter of the manufactured cover (fluid pipe panel diameter) was 2170 mm.

[0026] Next, during maintenance of the vacuum degassing unit, the connection between the vacuum degassing unit's exhaust port and the external exhaust device was disconnected, and the exhaust port was closed using a cover. Subsequently, to cool the cover, a fluid at a flow rate of 80 l / min was supplied to the cover. The pressure of the fluid flowing inside the cover was 0.3 MPa. The fluid temperature was 32°C at the inlet side of the cover and 70°C at the outlet side, with a temperature difference of 38°C between the inlet and outlet sides of the fluid. At this time, the temperature inside the chamber of the vacuum degassing unit was approximately 800°C.

[0027] As a result of the above implementation, the manufacturing of the lid achieved a significant reduction in the amount of welding and a reduction in manufacturing costs compared to the manufacturing of lids using the conventional structure (see Figures 4-6). Specifically, by configuring the fluid tube 2 as a spiral conduit 3, the use of short straight pipes and elbow pipes was eliminated, and as a result, the number of butt welds of multiple fluid tubes was reduced to about 1 / 8 of the conventional amount. Manufacturing costs were reduced to about 1 / 4 of the conventional amount. In addition, because of the spiral conduit formed in a spiral shape, scale accumulation inside the fluid tube was suppressed. Specifically, compared to the conventional membrane structure where the fluid tube cleaning frequency was once every 6 months, the cleaning frequency was reduced to once every 3 years.

[0028] Furthermore, by arranging the water supply pipe section and the drainage pipe section alternately adjacent to each other and joining them together by welding, temperature uniformity in the lid can be promoted, suppressing the generation of thermal stress differences caused by uneven heating and preventing deformation and cracking of the fluid pipe. As a result, the replacement cycle of the lid can be increased from once every 5 years in conventional membrane structures to once every 10 years. [Explanation of symbols]

[0029] 1 Lid 2 Fluid tube 3. Spiral pipeline 3a Water supply pipe section 3b Drain pipe section 4 Jacketed tubes 5 Divider Plates 6 Guide section 7 Water inlet 8 Drain O center S outer edge

Claims

1. A cover used to close the exhaust port in a processing tank, It has a spiral conduit through which fluid flows, and another fluid conduit located in the center of the spiral conduit. The vortex pipeline has a water supply section through which the fluid flows toward the center of the vortex pipeline, and a drainage section through which the fluid flows away from the center of the vortex pipeline. The water supply pipe section and the drainage pipe section are arranged alternately from the center of the spiral pipeline toward the outer edge, and The water supply pipe section and the drainage pipe section adjacent to each other, extending from the center of the spiral pipeline toward the outer edge, are joined to each other by welding. The other fluid pipe has a water inlet connected to the water supply pipe section, a drain outlet connected to the drain pipe section, a partition plate that defines a fluid flow path inside the other fluid pipe, and a guide section, and is a lid.

2. An exhaust port closing device having the cover described in claim 1.

3. An exhaust port closing device comprising a flange portion and a sealing portion provided on the outer edge of the cover described in claim 1.

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