Gas Supply Structure

Abstract

To provide a technology capable of reducing erosion of a gas supply device by slag. A main gas flow path has a gas inlet 31 for receiving a supply of gas during refining of molten steel contained in a ladle 9, and is connected to a gas injection plug 91 attached to the ladle 9 to supply the gas; a sub-gas flow passage having a pressure accumulator cylinder 55 for accumulating the gas supplied to the main gas flow passage through the gas inlet 31, and for supplying the gas from the pressure accumulator cylinder 55 to the gas blowing plug 91; A gas supply device 3 having A housing 8 is attached to the outer surface of the ladle 9 and houses at least a part of the gas supply device 3. The housing 8 comprises a box-shaped storage section 80 having an opening 83 on a side thereof, a door body 81 attached to the storage section 80 and covering the opening 83 in an openable and closable manner, and a eave section 82 provided above the opening 83 and protruding outward, forming a gas supply structure 1.

Description

[Technical field]

[0001] The present invention relates to a gas supply structure including a gas supply device for blowing gas into a molten metal contained in a ladle. [Background technology]

[0002] 2. Description of the Related Art There is known a technique for handling molten metal, i.e., molten metal, using a vessel called a ladle. The ladle generally has a gas injection plug for injecting gas into the molten metal in the ladle. In this specification, when the word "plug" is used without any special explanation, it means the gas injection plug.

[0003] In the ladle having the above-mentioned gas injection plug, the gas injection plug is directly or indirectly connected to a gas supply source installed in a plant, and gas such as argon or nitrogen supplied from the gas supply source is injected through the gas injection plug into the molten metal contained in the ladle, thereby making it possible to stir the molten metal contained in the ladle, adjust the temperature, and promote the reaction of removing non-metallic components.

[0004] Gas injection plugs for ladles generally include a porous plug having a porous shaped refractory layer, a slit-type plug having slit-like pores formed in a dense unshaped refractory layer, etc. In these gas injection plugs, gas flows through the pores in the porous shaped refractory layer or the slit-like pores formed in the shaped refractory layer.

[0005] However, when the ladle is moved after the gas injection process into the molten metal, it is necessary to disconnect the gas injection plug from the gas supply source, which is in a connected state. In such a case, the supply of gas to the gas injection plug is stopped, and the molten metal may enter the gas flow path, i.e., the pores, of the gas injection plug.

[0006] When the molten metal solidifies in the pores, the pores become clogged with metal and become unable to function as gas passages. When a ladle having such a gas injection plug is to be reused, it is necessary to remove the metal that has entered the pores of the gas injection plug.

[0007] In order to remove the metal that has entered the pores of the gas injection plug, a method called oxygen cleaning is generally adopted during maintenance after the molten metal is discharged from the ladle. In this method, air is supplied to the gas injection plug toward the inside of the ladle while oxygen is blown onto the gas injection plug from inside the ladle through a pipe to heat it. By this oxygen cleaning, the temperature of the working surface of the gas blowing plug that was in contact with the molten metal becomes high enough to melt the metal, and the refractory material that constitutes the working surface melts. This makes it possible to remove the permeation layer of the working surface of the gas blowing plug that has been permeated by the molten metal. This restores the gas blowing function of the gas blowing plug, and the gas blowing plug blows air.

[0008] Apart from the oxygen cleaning described above, a gas supply device has been proposed for supplying gas to the gas injection plug. The gas supply device has a pressure accumulator cylinder that stores gas under pressure, and the pressure accumulator cylinder is connected to a gas blowing plug. According to the gas supply device, when the gas injection plug and the gas supply source in a connected state are disconnected, gas is supplied from the pressure accumulator cylinder to the gas injection plug, thereby avoiding or suppressing the above-mentioned clogging of the pores. In this specification, when the term "cylinder" is used without special explanation, it means the pressure accumulator cylinder. Summary of the Invention [Problem to be solved by the invention]

[0009] As described above, when the gas injection plug and the gas supply source are disconnected from each other, the gas injection plug can be supplied with gas from the pressure storage cylinder of the gas supply device, which can prevent or suppress clogging of the pores with metal, and the above-mentioned oxygen cleaning does not need to be performed for a long time, but can be performed for a very short time. Therefore, the gas injection plug can be prevented from deteriorating by the gas injection device.

[0010] The gas supply device is located very close to the ladle in order to supply gas to the gas injection plug attached to the ladle, and is therefore exposed to fine solids (so-called slag) resulting from splashes of the molten metal contained in the ladle and additives to the molten metal.

[0011] If the gas supply device is corroded by the slag, the gas flow path of the gas supply device may be damaged, which may cause a problem in supplying gas to the gas injection plug, and may also make it difficult to smoothly supply gas to the ladle via the injection plug.

[0012] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a technique capable of reducing erosion of a gas supply device by slag. [Means for solving the problem]

[0013] The gas supply structure of the present invention that solves the above problems is as follows: a main gas flow passage having a gas inlet for receiving a supply of gas during refining of molten steel contained in the ladle, the main gas flow passage being connected to a gas injection plug attached to the ladle to supply the gas; an auxiliary gas flow passage including a pressure accumulator cylinder for accumulating the gas supplied to the main gas flow passage through the gas inlet, and for supplying the gas from the pressure accumulator cylinder to the gas injection plug; A gas supply device having a housing attached to an outer surface of the ladle and housing at least a portion of the gas supply device; The housing is a gas supply structure having a box-shaped storage section with an opening on the side, a door body attached to the storage section and covering the opening in an openable and closable manner, and a eave section provided above the opening and protruding outward. Effect of the Invention

[0014] According to the present invention, it is possible to reduce erosion of the gas supply device by slag. [Brief description of the drawings]

[0015] [Figure 1] 1 is an explanatory diagram illustrating a gas supply structure according to an embodiment and a ladle to which the gas supply structure is attached; FIG. [Diagram 2] FIG. 2 is an explanatory diagram illustrating a housing in the gas supply structure according to the embodiment; [Diagram 3] FIG. 2 is an explanatory diagram for explaining a gas supply device in the gas supply structure according to the embodiment; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The gas supply structure of the present invention comprises a gas supply device and a housing. The gas supply device supplies gas to a gas injection plug attached to the ladle, while the housing is attached to the outer surface of the ladle and houses at least a part of the gas supply device.

[0017] In the gas supply structure of the present invention, at least a part of the gas supply device is housed in a housing, so that slag generated in the ladle is blocked by the housing and does not easily reach the gas supply device.

[0018] Here, the housing has an opening on a side surface, and the opening is covered by a door body so as to be able to be opened and closed. Slag generated in the ladle is scattered downward from the upper opening of the ladle to the outside of the ladle. Therefore, if slag enters the housing from the outside through the gap between the opening and the door, the gas supply device housed in the housing is exposed to the slag. Depending on the period of use and the conditions of use of the ladle, it is expected that the amount of slag that enters the housing will increase. If the amount of slag that enters the housing is excessive, the gas supply device housed in the housing may be eroded by the slag.

[0019] The housing of the gas supply structure of the present invention has a eaves portion protruding outward above the opening. Therefore, the gap between the opening and the door body is covered from above by the eaves portion. In other words, in the gas supply structure of the present invention, the eaves portion interferes with the entry path of the slag from the ladle through the gap between the opening and the door body to the inside of the housing. Therefore, the gas supply structure of the present invention can reduce erosion of the gas supply device by slag.

[0020] The gas supply structure of the present invention will be described below with respect to each of its components.

[0021] Hereinafter, unless otherwise specified, the numerical range "x to y" described in this specification includes the lower limit x and the upper limit y in the range. The numerical range can be formed by arbitrarily combining these upper and lower limit values, as well as the numerical values ​​listed in the embodiment. Furthermore, the numerical values ​​arbitrarily selected from within the numerical range can be the upper and lower limit numerical values.

[0022] The gas supply structure of the present invention comprises a gas supply device and a housing. The gas supply device includes a main gas flow path, an auxiliary gas flow path, and a gas control unit.

[0023] The main gas flow path includes a gas inlet that is directly or indirectly attached to a gas supply source, and may be referred to as a gas flow path that is connected from the upstream side of the gas flow to a gas injection plug that is attached to the ladle.

[0024] The main gas flow passage is literally a gas flow passage, and may be formed, for example, inside a pipe or a cylinder, and its material, length, cross-sectional shape, flow passage cross-sectional area, etc. are not particularly limited. As described above, the gas flowing through the main gas passage is a gas supplied to the molten metal contained in the ladle, and may be an appropriate gas depending on the application, the type of molten metal, etc. Hereinafter, this gas may be referred to as a supply gas as necessary.

[0025] The auxiliary gas flow passage has a pressure accumulator cylinder that accumulates the supply gas supplied to the main gas flow passage through the gas inlet, and supplies the supply gas from the pressure accumulator cylinder to the gas injection plug. The auxiliary gas flow passage can be called a branch passage that branches off from the main gas flow passage downstream of the gas inlet and rejoins the main gas flow passage upstream of the gas injection plug.

[0026] Any pressure accumulator cylinder may be used as long as it is capable of storing the above-mentioned supply gas, and an appropriate one may be selected depending on the type of supply gas, the pressure of the supply gas in the cylinder, the amount of supply gas to be stored, and the like.

[0027] The auxiliary gas flow passage may further include a gas regulating element for supplying a given amount of supply gas from the accumulator cylinder to the gas injection plug. For example, the gas regulating element may be directly connected to the gas injection plug and supply the supply gas directly to the gas injection plug. Alternatively, the gas regulating element may be connected to a gas flow passage communicating with the gas injection plug and supply the supply gas indirectly to the gas injection plug via the gas flow passage. There is also no particular limitation on the amount of gas supplied by the gas regulating element to the gas injection plug, and the amount of gas supplied may be constant or may vary appropriately depending on the situation.

[0028] The gas supply structure of the present invention may further include a gas control section that switches between supplying the supply gas from the main gas flow passage to the gas injection plug and supplying the supply gas from the secondary gas flow passage to the gas injection plug. In the gas supply structure of the present invention having a gas control section, when it is necessary to supply the supply gas from the main gas flow path to the gas injection plug, the gas control section closes or throttles the gas flow path from the sub gas flow path to the gas injection plug to supply the supply gas preferentially from the main gas flow path to the gas injection plug. Hereinafter, this gas supply mode may be referred to as a first supply mode, as necessary.

[0029] In the gas supply structure of the present invention, when it is necessary to supply the supply gas from the sub-gas passage to the gas injection plug, the gas control unit closes or throttles the gas passage from the main gas passage to the gas injection plug to supply the supply gas preferentially from the sub-gas passage to the gas injection plug. Hereinafter, this gas supply mode may be referred to as a second supply mode, as necessary.

[0030] The gas control unit may be any unit capable of switching between the first and second supply modes described above. An example of the gas control unit may include a valve that opens and closes the main gas flow path and / or the sub-gas flow path, and a control element that controls the switching of the valve. In the gas supply structure of the present invention, the gas control section may be separate from the main gas passage and the sub gas passage, or may be a part of the main gas passage and / or the sub gas passage.

[0031] When the gas control unit switches between the gas supply in the first supply mode and the gas supply in the second supply mode as described above, the trigger for switching between the gas supply in the first supply mode and the gas supply in the second supply mode is not particularly limited.

[0032] For example, when the pressure of the supply gas flowing into the pressure accumulator cylinder is equal to or higher than a predetermined value, the gas supply may be switched from the second supply mode to the first supply mode.

[0033] The housing is attached to the outer surface of the ladle and houses at least a part of the gas supply device. Hereinafter, the part of the gas supply device housed in the housing may be referred to as a protected part, as necessary.

[0034] In the gas supply structure of the present invention, the entire gas supply device may be the protected part, or a part of the gas supply device may be the protected part. However, for example, since the pressure accumulator cylinder is relatively large, if the pressure accumulator cylinder is included in the protected part, the housing will become large. Therefore, it is preferable that the protected part of the gas supply device is a part of the gas supply device that does not include the pressure accumulator cylinder and the gas flow path part connected thereto. In addition, since the gas inlet, gas adjustment element, and gas control part of the gas supply device have a relatively precise structure, it is preferable that they are not exposed to slag. Therefore, it is preferable that the protected part of the gas supply device includes at least one selected from the gas inlet, gas adjustment element, and gas control part, and it is particularly preferable that the protected part of the gas supply device includes all of these.

[0035] The housing may be any housing capable of separating the part to be protected of the gas supply device from the outside world, and the inside of the housing may be connected to the outside world or may be air-tightly and / or liquid-tightly sealed from the outside world.

[0036] In the gas supply structure of the present invention, the housing has a container portion, a door body, and a canopy portion. The container may be in the shape of a box having an opening on a side surface. The side surface means a surface other than the top and bottom surfaces of the container, and may be a main wall surface facing the peripheral wall of the ladle, or a side wall surface perpendicular to the main wall surface.

[0037] The door body is only required to be able to cover the opening in an openable and closable manner, and its shape and opening / closing mechanism are not particularly limited. For example, the door body may be of a rotating type that is pivotally supported by the storage unit and rotates between a closed position that closes the opening and an open position that opens the opening, or the door body may be of a detachable type that is detachably attached to the storage unit and closes the opening in the closed position attached to the storage unit and opens the opening in the open position removed from the storage unit.

[0038] In the case of the above-mentioned pivotable door, the pivot axis of the door may extend in the up-down direction, in other words, in the vertical direction, or may extend in the horizontal direction. In order to smoothly open and close the door, it is preferable that the pivot axis of the door extends in the up-down direction. Note that the up-down direction here can be any direction that crosses the vertical direction at an angle of 5° or less.

[0039] In either case, the gas supply structure of the present invention has a visor portion provided above the opening. The visor portion protrudes outward above the opening. Therefore, it can be said that the opening is covered from above by the visor portion. The outside here means the outside in the inside-outside direction of the housing with the opening as the boundary.

[0040] There are no particular limitations on the size of the eaves portion relative to the opening, its positional relationship, etc. For example, the eaves portion may cover only a portion of the opening from above in the horizontal direction, or may cover the entire opening from above in the horizontal direction. In order to more reliably avoid or reduce exposure of the protected portion of the gas supply device to slag, it is preferable that the eaves portion covers the entire opening from above in the horizontal direction.

[0041] The vertical distance between the opening and the eaves is also not particularly limited, and the eaves may cover the opening from above at a position close to the opening, or may cover the opening from above at a position distant from the opening. In order to avoid an increase in size of the housing, it is preferable that the vertical distance between the lower end of the eaves and the upper end of the opening is short, and the distance is preferably, for example, 100 mm or less, 50 mm or less, 30 mm or less, or 10 mm or less.

[0042] In the gas supply structure of the present invention, the length of the outward protrusion of the eaves portion is not particularly limited, and as long as the eaves portion protrudes outward even slightly, it has the effect of reducing exposure of the protected part of the gas supply device to slag. However, in order to more reliably avoid or reduce exposure of the protected part of the gas supply apparatus to slag, it is more preferable that the eaves portion protrudes significantly outward from the outer end of the opening, and specifically, it is preferable that the distance from the outer end of the opening to the protruding end of the eaves portion be 20 mm or more, 30 mm or more, or 50 mm or more. In addition, it is more preferable that the distance from the outer surface of the door body to the protruding end of the eaves portion is 10 mm or more, 20 mm or more, 30 mm or more, or 50 mm or more. There is no particular upper limit to the distance from the outer edge of the opening to the protruding end of the eaves, and the distance from the outer surface of the door body to the protruding end of the eaves, but it is particularly preferable that these be 80 mm or less to avoid increasing the size of the housing.

[0043] The gas supply structure of this proposal will be described below by giving a specific example. [Embodiment] Fig. 1 is an explanatory diagram that typically illustrates a gas supply structure according to an embodiment and a ladle to which the gas supply structure is attached. Fig. 2 is an explanatory diagram that typically illustrates a housing in the gas supply structure according to an embodiment. Fig. 3 is an explanatory diagram that typically illustrates a gas supply device in the gas supply structure according to an embodiment.

[0044] 1, a gas supply structure 1 of the embodiment includes a gas supply device 3 and a housing 8. The gas supply device 3 and the housing 8 are attached to a ladle 9.

[0045] As shown in FIGS. 1 to 3, the ladle 9 has a ladle body 90 and a gas injection plug 91 attached to the ladle body 90. The ladle body 90 is capable of containing molten metal 95, and a gas injection plug 91 is provided at the bottom of the ladle body 90 for injecting a supply gas into the molten metal 95 contained in the ladle body 90.

[0046] More specifically, the ladle body 90 has a layered structure having a tank-shaped outer shell made of a heat-resistant metal and a heat-resistant refractory layer disposed inside the outer shell. The gas injection plug 91 connects the inside and outside of the ladle body 90.

[0047] The gas blowing plug 91 blows the supply gas flowing through the gas supply device 3 into the molten metal 95. In the gas supply structure 1 of the embodiment, the supply gas is a so-called inert gas, typically argon or nitrogen.

[0048] As the gas injection plug 91 of the ladle 9, a porous plug having a gas permeable porous molded refractory layer, or a slit plug having slit-shaped pores formed in a dense unformed refractory layer can be suitably used. The supply gas supplied from the gas supply device 3 to the gas injection plug 91 passes through the porous pores or slit-like pores described above, and is injected into the molten metal 95 contained in the ladle body 90.

[0049] 3, the gas supply device 3 includes a first pipe 4, a second pipe 5, a third pipe 6, a pressure regulating valve 61, a flow rate regulating valve 62, a filter 7, and a pressure accumulator cylinder 55. As shown in FIG. 1, the gas supply device 3 is disposed on the outer surface of the ladle 9, more specifically, on the outer peripheral surface of the outer shell of the ladle body 90.

[0050] The first pipe 4, the second pipe 5, and the third pipe 6 are essentially pipes through which the supply gas flows.

[0051] Of these, the first piping 4 connects a gas inlet 31 and a gas outlet 32. The gas inlet 31 is disposed on the upstream side of the gas flow in the first piping 4, and is connected to a gas supply source (not shown). The gas outlet 32 ​​is disposed on the downstream side of the gas flow in the first piping 4, and is connected to a gas inlet plug 91 of the ladle 9.

[0052] A first check valve 41 is provided in the first pipe 4. The first check valve 41 allows only the direction from the gas inlet 31 to the gas outlet 32, that is, the upstream - downstream direction of the gas flow, as the flow direction of the supply gas. A normal check valve is used as the first check valve 41.

[0053] Furthermore, a filter 7 is disposed between the gas inlet 31 and the first check valve 41 in the first pipe 4, more specifically, between the connection portion of the second pipe 5 and the first pipe 4, which will be described later, and the gas inlet 31. The filter 7 is for removing foreign matters contained in the supply gas. The gas inlet 31, the first pipe 4, the first check valve 41, and the filter 7 form the main gas flow path in the gas supply structure 1 of the present invention.

[0054] The second pipe 5 branches off from the first pipe 4 and connects the gas inlet 31 and the accumulator cylinder 55. More specifically, the upstream - side end of the second pipe 5 in the gas flow direction is connected to the first pipe 4 on the downstream side of the filter 7. And the downstream - side end of the second pipe 5 in the gas flow direction is connected to the accumulator cylinder 55. A second check valve 51 is provided in the second pipe 5. The second check valve 51 also allows only the upstream - downstream direction of the gas flow as the flow direction of the supply gas. A normal check valve is also used as the second check valve 51.

[0055] The third pipe 6 connects the first pipe 4 and the second pipe 5. More specifically, one end of the third pipe 6 is connected between the first check valve 41 in the first pipe 4 and the joint 43 of the gas outlet 32. The other end of the third pipe 6 is connected between the second check valve 51 in the second pipe 5 and the joint 52 of the accumulator cylinder 55. The third pipe 6 is a flow path for the supply gas from the accumulator cylinder 55 toward the gas outlet 32. A pressure regulating valve 61 and a flow rate regulating valve 62 are provided in the third pipe 6. In the flow of the supply gas through the third pipe 6 from the pressure accumulator cylinder 55 toward the gas outlet 32, a pressure regulating valve 61 is disposed on the upstream side and a flow rate regulating valve 62 is disposed on the downstream side.

[0056] The second pipe 5, the second check valve 51, the third pipe 6, the pressure regulating valve 61, the flow rate regulating valve 62 and the pressure accumulator cylinder 55 form a secondary gas flow path in the gas supply structure 1 of the present invention.

[0057] Among these, the third pipe 6, the pressure regulating valve 61 and the flow rate regulating valve 62 are parts for switching between the supply of supply gas from the main gas flow path to the gas injection plug 91 and the supply of supply gas from the auxiliary gas flow path to the gas injection plug 91, and can be referred to as a gas control unit in the gas supply structure 1 of the present invention.

[0058] In the gas supply structure 1 of the embodiment, the gas supply device 3, i.e., the main gas flow path, the auxiliary gas flow path, and the gas control units contained therein, are disposed on the outer peripheral surface of the outer shell of the ladle body 90. Among these, the pressure accumulator cylinder 55 and a part of the second piping 5 connected thereto, the gas injection plug 91 and a part of the first piping 4 connected thereto, and the gas inlet 31 and a part of the first piping 4 connected thereto are contained inside the housing 8.

[0059] Incidentally, the portion of the second piping 5 connected to the accumulator cylinder 55 and the other portion are detachably connected by a joint 52. The portion of the first piping 4 connected to the gas blowing plug 91 and the other portion are detachably connected by a joint 43. Furthermore, the portion of the first piping 4 connected to the gas inlet 31 and the other portion are detachably connected by a joint 42.

[0060] As shown in FIGS. 1 and 2, the housing 8 has a storage section 80, a door body 81, and a canopy section .

[0061] The accommodation unit 80 has a generally rectangular box shape having a front wall surface facing the peripheral wall of the ladle 9, two side wall surfaces perpendicular to the front wall surface, and upper and lower wall surfaces perpendicular to the front wall surface and the side wall surfaces. The accommodation unit 80 is attached to the outer surface of the ladle 9.

[0062] An opening 83 that communicates between the inside and the outside of the storage section 80 is provided on the front wall surface of the storage section 80 . The door body 81 is in the form of a substantially rectangular plate. A rotation shaft 84 of the door body 81 extends in the vertical direction and is attached to one horizontal end of the storage section 80. The door body 81 is supported by the rotation shaft 84 in the storage section 80 and rotates about the rotation shaft 84 between a closed position where the opening 83 is closed and an open position where the opening 83 is opened.

[0063] The eaves portion 82 is provided above the opening 83 . 2, eaves portion 82 has a generally plate-like shape. One end of eaves portion 82 is fixed to the upper wall surface of storage portion 80, and the other end protrudes outward. Eaves portion 82 is located adjacent to opening 83. In gas supply structure 1 of the embodiment, the distance in the vertical direction between the lower end of eaves portion 82 and the upper end of opening 83 is approximately 10 mm. Eaves portion 82 horizontally covers the entire opening 83 from above. Distance L1 from the outer edge of opening 83 to the protruding end of eaves portion 82 is about 50 mm, and distance L2 from the outer surface of door body 81 to the protruding end of eaves portion 82 is about 40 mm.

[0064] The operation of the gas supply structure 1 of the embodiment will be described below.

[0065] [First supply mode] When the molten metal 95 is poured into the ladle body 90 of the ladle 9 and the ladle body 90 contains the molten metal 95, the gas supply structure 1 of the embodiment supplies gas in the first supply mode. At this time, the supply gas introduced into the gas inlet 31 from a gas supply source (not shown) first flows into the first piping 4, passes through the filter 7, and flows through the first piping 4 toward the gas outlet 32. The supply gas that reaches the gas outlet 32 ​​is supplied to the gas injection plug 91 of the ladle body 90 through the gas outlet 32. The supply gas supplied to the gas injection plug 91 is then injected into the molten metal 95 in the ladle 9, thereby stirring the molten metal 95, etc.

[0066] At the same time, the supply gas introduced into the gas inlet 31 flows into the second piping 5. A part of the supply gas that has flowed into the second piping 5 merges with the downstream side of the first piping 4 through the third piping 6 and flows toward the gas outlet 32. The other part of the supply gas that has flowed into the second piping 5 flows into the pressure accumulator cylinder 55 and is accumulated in the pressure accumulator cylinder 55.

[0067] [Second supply mode] When the ladle body 90 containing the molten metal 95 is to be transferred, the gas inlet 31 is detached from the gas supply source (not shown). Therefore, at this time, the supply gas is no longer supplied to the gas inlet 31 of the gas supply device 3. At this time, the gas supply structure 1 of the embodiment supplies gas in the second supply mode.

[0068] At this time, the pressure regulating valve 61 and the flow rate regulating valve 62 close or throttle the gas flow path from the main gas flow path to the gas blowing plug 91, and the supply gas is preferentially supplied from the sub-gas flow path to the gas blowing plug 91. Therefore, the supply gas stored in the pressure accumulating cylinder 55 is released from the pressure accumulating cylinder 55 and supplied to the third pipe 6. The supply gas passes through the third pipe 6, merges with the downstream side of the first pipe 4, passes through the gas blowing port 32, and is supplied to the gas blowing plug 91. The supply gas supplied to the gas blowing plug 91 is blown out toward the molten metal 95. By blowing the supply gas from the gas blowing plug 91 toward the molten metal 95 in this way, it is possible to suppress the intrusion of the molten metal 95 into the gas blowing plug 91.

[0069] Since the first check valve 41 is provided in the first piping 4, the supply gas released from the pressure accumulator cylinder 55 does not flow back through the first piping 4 from the gas outlet 32 ​​side to the gas inlet 31 side. Since the second check valve 51 is provided in the second piping 5, the supply gas released from the pressure accumulator cylinder 55 does not flow back through the second piping 5 from the pressure accumulator cylinder 55 side to the gas inlet 31 side.

[0070] In the gas supply structure 1 of the embodiment, most of the gas supply device 3 is accommodated in a housing 8. An opening 83 in the housing 8 is covered by a door body 81 so as to be able to open and close, and an outwardly protruding eaves portion 82 is provided above the opening 83. The eaves portion 82 covers the gap between the opening 83 and the door body 81 from above, so that the eaves portion 82 blocks the path of entry of slag, which is generated in the ladle 9 and scattered downward from the upper opening 93 of the ladle 9, into the housing 8. This prevents slag from entering the housing 8, and thus the portion of the gas supply device 3 accommodated in the housing 8, i.e., the protected portion, is less likely to be exposed to slag. As a result, according to the gas supply structure 1 of the embodiment, erosion of the gas supply device 3 by slag is reduced.

[0071] Although the present invention has been described above, the present invention is not limited to the above-mentioned embodiments, and it is possible to implement the present invention by appropriately extracting and combining elements described in the embodiments, and to make various modifications within the scope that does not deviate from the spirit of the present invention. In addition, the specification of the present invention discloses not only the citation relationships of each claim at the time of the initial application, but also a technical idea that appropriately combines the matters described in each claim. [Explanation of symbols]

[0072] 1: Gas supply structure 3: Gas supply equipment 31: Gas inlet 55: Pressure cylinder 8: Housing 80: Storage unit 81: Door body 82: Eaves 83:Aperture 84: Pivot shaft of door body 9: Ladle 91: Gas inlet plug

Claims

1. a main gas flow passage having a gas inlet for receiving a supply of gas during refining of molten steel contained in the ladle, the main gas flow passage being connected to a gas injection plug attached to the ladle to supply the gas; an auxiliary gas flow passage including a pressure accumulator cylinder for accumulating the gas supplied to the main gas flow passage through the gas inlet, and for supplying the gas from the pressure accumulator cylinder to the gas injection plug; A gas supply device having a housing attached to an outer surface of the ladle and housing at least a portion of the gas supply device; The gas supply structure includes a box-shaped storage section having an opening on the side, a door body attached to the storage section and covering the opening in an openable and closable manner, and a eave section provided above the opening and protruding outward.

2. The gas supply structure according to claim 1 , wherein the door is pivotally supported by the container and rotates between a closed position at which the opening is closed and an open position at which the opening is opened.

3. The gas supply structure according to claim 2 , wherein the pivot axis of the door body extends in a vertical direction.

4. 4. The gas supply structure according to claim 1, wherein a distance from an outer end of the opening to the protruding end of the eave portion is 30 mm or more.

5. The gas supply structure according to claim 4 , wherein a distance from an outer end of the opening to the protruding end of the overhanging portion is 50 mm or more.

6. The gas supply structure according to claim 4 , wherein a distance from an outer surface of the door body to the protruding end of the eave portion is 10 mm or more.

7. The gas supply structure according to claim 6 , wherein a distance from an outer surface of the door body to the protruding end of the eave portion is 30 mm or more.

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