Gas return type water sealing apparatus, gas return type water sealing system and gas returning method of water sealing system

Abstract

A gas recovery type water seal device, a gas recovery type water seal system, and a method for recovering gas in a water seal system are disclosed. The water seal device may include: a water seal portion formed to be bent downward between the supply side and the use side of a gas pipeline to block the gas flow by means of a water seal; a gas recovery pipe provided with a gas recovery valve that controls the gas flow and communicates between the supply side and the use side of the gas pipeline by bypassing the water seal portion; and a nitrogen supply pipe provided with a nitrogen supply valve that supplies nitrogen gas to the supply side of the gas pipeline and controls the supply of nitrogen gas.

Description

Technology Field

[0001] The disclosed invention relates to a gas recovery type water seal device, a gas recovery type water seal system, and a gas recovery method for a water seal system. More specifically, it relates to a gas recovery type water seal device, a gas recovery type water seal system, and a gas recovery method for a water seal system that can recover residual gas from a pipe with both ends sealed by providing a gas recovery pipe and a nitrogen supply pipe in the event of an abnormal situation such as repair or replacement of a gas supply pipe. Background Technology

[0002] By-product gases generated at steel mills, such as blast furnace gas, converter gas, and coke oven gas, are transported through pipes. For example, in the case of coke oven gas (COG), it is transported through a large gas pipe with a diameter of approximately 2500 mm.

[0003] In the case of large-scale gas pipelines, it is practically impossible to shut off the flow of gas along the pipeline using conventional mechanical valves. Therefore, water sealing equipment is used to block the gas flow within the pipeline.

[0004] A water seal system blocks the movement of gas transported along a gas pipeline by utilizing the hydrostatic pressure of the water seal. Specifically, a specific section of the gas pipeline is formed into a 'V' or 'U' shaped water seal valve (hereinafter referred to as the water seal section), and water that blocks the gas flow is supplied through a supply pipe connected above the boundary between the water seal section and the gas pipeline. The water seal section is filled with water to have a hydrostatic pressure of approximately 1.5 times or more relative to the pressure of the gas flowing along the gas pipeline. The flow of gas flowing through the gas pipeline is blocked by the hydrostatic pressure of the water filled in the water seal section.

[0005] Meanwhile, when such byproduct gas pipelines are used for a long period, if pinholes or perforations occur due to corrosion or if the thickness of the steel sheath thins out and falls below the pipeline management standard, gas can no longer be supplied, and the pipeline must be replaced or reinforced. However, reinforcement or replacement work cannot be performed while gas is present inside the gas pipeline, and since welding or cutting for reinforcement or replacement increases the risk of gas explosion or fire, it is necessary to completely purge the gas inside the pipeline to the outside or replace it with nitrogen gas, an inert gas.

[0006] Until now, gas has been purged using the N2 Injection method, which supplies inert nitrogen gas into the gas pipeline to purge the gas, and the Steam Ejecting method, which injects steam to discharge the gas. However, since both methods discharge gas into the atmosphere, they not only cause environmental pollution but also result in the loss of gas that can be used as fuel. Furthermore, there is a risk of fire and explosion due to the massive release of gas, and if workers are present near the gas discharge area, there is a risk of serious industrial accidents, such as gas poisoning accidents. The problem to be solved

[0007] One aspect of the disclosed invention provides a gas recovery type water seal device, a gas recovery type water seal system, and a gas recovery method of the water seal system, wherein a gas recovery pipe and a nitrogen supply pipe are provided to recover residual gas from a pipe with both ends sealed in the event of an abnormal situation such as repair or replacement of the gas supply pipe. means of solving the problem

[0008] A water seal device according to one embodiment of the disclosed invention may include: a water seal portion formed to be bent downward between the supply side and the use side of a gas pipe to block the gas flow by the water seal; a gas recovery pipe provided with a gas recovery valve that controls the gas flow and communicates between the supply side and the use side of the gas pipe by bypassing the water seal portion; and a nitrogen supply pipe provided with a nitrogen supply valve that supplies nitrogen gas to the supply side of the gas pipe and controls the supply of nitrogen gas.

[0009] The water seal device may further include a pressure sensing unit provided on the supply side of the gas pipe to detect the pressure of the gas pipe.

[0010] The water seal device may further include a gas detection unit provided on the use side of the gas pipe to detect the carbon monoxide concentration of the gas pipe.

[0011] The above gas recovery pipe may have a smaller cross-sectional area than the above gas pipe.

[0012] The above gas recovery valve and the above nitrogen supply valve can be shut off when gas is supplied or when blocked by a water seal.

[0013] A water seal system according to one embodiment of the disclosed invention comprises: a gas pipe connecting a supply source and a use source; and two or more water seal devices provided in the gas pipe; wherein the water seal device may include: a water seal portion formed to be bent downward between the supply side and the use side of the gas pipe to block the gas flow by the water seal; a gas recovery pipe provided with a gas recovery valve that controls the gas flow by bypassing the water seal portion and communicating between the supply side and the use side of the gas pipe; and a nitrogen supply pipe provided with a nitrogen supply valve that supplies nitrogen gas to the supply side of the gas pipe and controls the supply of nitrogen gas.

[0014] The above water seal device may further include a pressure sensing unit provided on the supply side of the gas pipe to detect the pressure of the gas pipe; and a gas sensing unit provided on the use side of the gas pipe to detect the carbon monoxide concentration of the gas pipe.

[0015] The water seal system may further include a control unit that receives information from the pressure sensing unit and the gas sensing unit of the water seal device above and controls the opening and closing of the gas recovery valve and the nitrogen supply valve of two or more water seal devices to recover gas in the gas piping between two or more water seal devices.

[0016] When recovering gas from a gas pipe between two water seal devices provided in the gas pipe, the control unit can recover gas by opening the nitrogen supply valve of the second water seal device closer to the point of use among the two water seal devices blocked by the water seal, and opening the gas recovery valve of the first water seal device closer to the point of supply among the two water seal devices.

[0017] The control unit can open the gas recovery valve of the first water seal device when the pressure in the supply-side gas pipe of the second water seal device becomes higher than the pressure in the supply-side gas pipe of the first water seal device by more than a first threshold.

[0018] The above first threshold value can be determined in proportion to the pressure in the supply-side gas pipe of the above first water seal device.

[0019] The control unit can shut off the gas recovery valve of the first water seal device and the nitrogen supply valve of the second water seal device when the carbon monoxide concentration in the gas pipe on the user side of the first water seal device is below the second threshold.

[0020] A gas recovery method for a water seal system according to one embodiment of the disclosed invention may include: a step of blocking by water sealing a first water seal device near a supply source and a second water seal device near a use source, provided in a gas pipeline connecting a supply source and a use source; a step of opening a nitrogen supply valve of the second water seal device to supply nitrogen gas to the supply-side gas pipeline of the second water seal device; and a step of recovering gas by opening a gas recovery valve of a gas recovery pipe that communicates by bypassing the water seal section between the supply-side and use-side of the gas pipeline of the first water seal device when the pressure in the supply-side gas pipeline of the second water seal device becomes higher than or equal to a first threshold value than the pressure in the supply-side gas pipeline of the first water seal device.

[0021] The above first threshold value can be determined in proportion to the pressure in the supply-side gas pipe of the first water seal device.

[0022] A gas recovery method for a water seal system may further include: a step of detecting a carbon monoxide concentration in the gas pipe on the user side of the first water seal device; and a step of shutting off the gas recovery valve of the first water seal device and the nitrogen supply valve of the second water seal device when the carbon monoxide concentration in the gas pipe on the user side of the first water seal device is below a second threshold. Effects of the invention

[0023] Costs can be reduced by recovering gas within a gas pipeline without releasing it during maintenance work using a gas recovery type water seal device, a gas recovery type water seal system, and a gas recovery method of the water seal system according to one embodiment of the disclosed invention.

[0024] A gas recovery type water seal device, a gas recovery type water seal system, and a gas recovery method of a water seal system according to one embodiment of the disclosed invention can prevent air pollution by not releasing gas into the atmosphere.

[0025] A gas recovery type water seal device, a gas recovery type water seal system, and a gas recovery method of the water seal system according to one embodiment of the disclosed invention can prevent serious industrial accidents such as gas poisoning accidents or explosions and fires. Brief explanation of the drawing

[0026] FIG. 1 is a schematic diagram illustrating the appearance of a water seal system according to one embodiment of the disclosed invention. FIG. 2 is a schematic diagram illustrating the appearance of a water sealing device according to one embodiment of the disclosed invention. FIG. 3 is a schematic diagram illustrating the state of a water seal system during gas supply according to one embodiment of the disclosed invention. FIG. 4 is a schematic diagram illustrating a state in which the gas supply of a water seal system according to one embodiment of the disclosed invention is blocked by a water seal. FIG. 5 is a schematic diagram illustrating a control unit according to one embodiment of the disclosed invention. FIG. 6 is a diagram schematically illustrating a gas recovery method of a water seal system according to one embodiment of the disclosed invention. FIGS. 7 and 8 are schematic drawings illustrating the state of a water seal system during gas recovery according to one embodiment of the disclosed invention. Specific details for implementing the invention

[0027] Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The embodiments introduced below are provided as examples to ensure that the concept of the present invention is sufficiently conveyed to those skilled in the art to which the present invention pertains. The present invention is not limited to the embodiments described below and may be embodied in other forms. To clearly explain the present invention, parts unrelated to the description have been omitted from the drawings, and in the drawings, the width, length, thickness, etc., of components may be exaggerated for convenience. Throughout the specification, the same reference numerals indicate the same components.

[0028] FIG. 1 is a schematic diagram illustrating the appearance of a water seal system according to one embodiment of the disclosed invention.

[0029] A water seal system according to one embodiment of the invention disclosed as illustrated in FIG. 1 may include a gas pipe (10) that transports gas by connecting a supply source (1) and a use source (2) of byproduct gas, a water seal device (1000) that blocks gas by water sealing and is provided in two or more places in the gas pipe (10), and a plurality of gas seal ports (2000) that separate impurities of byproduct gas provided in the gas pipe (10).

[0030] The supply source (1) may be a facility that generates byproduct gas, such as a blast furnace or an electric furnace, or a storage tank that stores the generated byproduct gas and supplies the stored byproduct gas.

[0031] The place of use (2) may be a storage tank where the generated byproduct gas is transported and stored, or a facility or power plant that uses the byproduct gas as process fuel.

[0032] Meanwhile, as shown in FIG. 1, the gas pipe (10) can be connected to multiple places of use (2a) (2b) to transport gas.

[0033] A water seal device (1000) is provided in a gas pipe (10) to block gas by water sealing. In large pipes such as gas pipes (10) through which byproduct gas is transported, it is impossible to block the flow of gas in the gas pipe (10) using a general mechanical valve, so the water seal device (1000) is used to block the flow of gas in the gas pipe (10). The water seal device (1000) can block the flow of gas by making a specific part of the gas pipe (10) into a V-shaped water seal section and supplying water to fill the water seal section.

[0034] By using such a water seal device (1000), the gas flow can be blocked when performing maintenance or replacement work on the gas pipe (10). For example, when maintaining the gas pipe (10) that supplies gas to the first use location (2a), the gas flow can be blocked using the first water seal device (1000a) and the second water seal device (1000b), and after removing the internal byproduct gas, the maintenance or replacement work can be safely performed.

[0035] Conventionally, the gas flow was blocked using a water seal device (1000) and the byproduct gas inside the gas pipe (10) was discharged into the atmosphere, but in an embodiment of the disclosed invention, the byproduct gas inside the gas pipe (10) can be recovered to the supply side. To this end, a water seal device (1000) according to one embodiment of the disclosed invention may include a configuration as shown in FIG. 2.

[0036] FIG. 2 is a schematic diagram illustrating the appearance of a water sealing device according to one embodiment of the disclosed invention.

[0037] Referring to FIG. 2, the specific configuration of such a water sealing device (1000) can be confirmed.

[0038] A water seal device (1000) according to an embodiment of the disclosed invention may include: a water seal portion (20) formed to be bent downward between the supply side and the use side of a gas pipe (10) to block the gas flow by the water seal; a gas recovery pipe (60) provided with a gas recovery valve (130) that controls the gas flow by bypassing the water seal portion (20) and communicating between the supply side and the use side of the gas pipe (10); a nitrogen supply pipe (70) provided with a nitrogen supply valve (140) that supplies nitrogen gas to the supply side of the gas pipe (10) and controls the supply of nitrogen gas; a pressure sensing portion (200) provided on the supply side of the gas pipe (10) to detect the pressure of the gas pipe (10); and a gas sensing portion (300) provided on the use side of the gas pipe (10) to detect the carbon monoxide concentration of the gas pipe (10).

[0039] The water seal device (1000) may be provided with a plurality of discharge pipes (80) for controlling the pressure inside the pipe and a plurality of discharge valves (150) for controlling the opening and closing of the discharge pipes.

[0040] In the supply side and the use side of the water seal (20), a discharge pipe (81)(82) and a discharge valve (151)(152) for controlling the pressure of the gas pipe (10) may be provided, respectively. In addition, in the supply side and the use side of the gas recovery pipe (60), a discharge pipe (83)(84) and a discharge valve (153)(154) for controlling the pressure of the gas recovery pipe (60) may be provided, respectively.

[0041] The water seal (20) is formed to be bent downward between the supply side and the use side of the gas pipe (10). Water can be supplied to the water seal (20) bent downward in this way through a water supply pipe (not shown) to block the flow of gas.

[0042] Meanwhile, the water seal device (1000) needs to ensure that water is always filled within the water seal section (20) so that a water level with a desired hydrostatic pressure can be maintained to block the flow of gas. To this end, water is continuously supplied through a supply pipe to fill the seal, and is controlled to drain water through an overflow pipe (30) and an overflow discharge pipe (50) connected to the water seal section (20) to discharge water.

[0043] In order to restart the flow of gas, water can be discharged through a drain pipe (40) connected to the water seal (20) to discharge water.

[0044] The supply pipe, overflow pipe (30), and drain pipe (40) are each opened and closed through a water supply valve (not shown), an overflow valve (120), and a drain valve (110), respectively, so that the water seal device (1000) blocks or opens the gas pipe (10) through the water seal.

[0045] The gas recovery pipe (60) bypasses the water seal (20) and connects the supply side and the use side of the gas pipe (10). Through this gas recovery pipe (60), even when the water seal (20) is blocked by the water seal, the byproduct gas inside the gas pipe (10) can be recovered to the supply source (1). The gas recovery pipe (60) may have a smaller cross-sectional area than the gas pipe (10).

[0046] A gas recovery valve (130) is provided in the gas recovery pipe (60) to control the gas flow of the gas recovery pipe (60). The gas recovery valve (130) is normally closed to block the flow of gas through the gas recovery pipe (60), and can be opened or closed by a control unit (3000) to be described later when recovering byproduct gas from the gas pipeline (10).

[0047] The nitrogen supply pipe (70) can supply nitrogen gas to the supply side of the gas pipe (10). In the disclosed invention, nitrogen gas can be supplied to the gas pipe (10) to recover byproduct gas inside the gas pipe (10) to the supply side. FIG. 2 shows an embodiment in which the nitrogen supply pipe (70) is connected to one side of the gas recovery pipe (60), but is not limited thereto, and the nitrogen supply pipe (70) may be directly connected to the gas pipe (10) to supply nitrogen gas.

[0048] A nitrogen supply valve (140) is provided in the nitrogen supply pipe (70) to control the supply of nitrogen gas. The nitrogen supply valve (140) is normally closed to block the supply of nitrogen gas, and can be opened or closed by a control unit (3000) to be described later when recovering byproduct gas from the gas pipe (10).

[0049] The pressure sensing unit (200) is provided on the supply side of the gas pipe (10) of the water seal device (1000) to sense the pressure of the gas pipe (10). The pressure of the gas pipe (10) sensed by the pressure sensing unit (200) is input to the control unit (3000) to be described later, and can be used to control the opening and closing of the gas recovery valve (130) and the nitrogen supply valve (140).

[0050] A gas detection unit (300) is provided on the side of use of the gas pipe (10) of the water seal device (1000) to detect the carbon monoxide concentration of the gas pipe (10). The carbon monoxide concentration of the gas pipe (10) detected by the gas detection unit (300) is input to a control unit (3000) to be described later, which can control the opening and closing of the gas recovery valve (130) and the nitrogen supply valve (140).

[0051] FIG. 3 is a schematic diagram illustrating the state of a water seal system when gas is supplied according to one embodiment of the disclosed invention, and FIG. 4 is a schematic diagram illustrating the state in which the gas supply of a water seal system according to one embodiment of the disclosed invention is blocked by the water seal.

[0052] Below, gas control in a water seal system including two water seal devices (1000a) and (1000b) will be described.

[0053] FIGS. 3 and 4 illustrate a water sealing system comprising a first water sealing device (1000a) near a supply source (1) and a second water sealing device (1000b) near a use source (2). These may be the first water sealing device (1000a) and the second water sealing device (1000b) provided in a gas pipe (10) connecting the supply source (1) and the use source (2) in a water sealing system as shown in FIG. 1. However, they are not limited thereto and may be the third water sealing device (1000c) and the fourth water sealing device (1000d) as shown in FIG. 1. At this time, since the third sealing device (1000c) of FIG. 1 is closer to the supply source (1) than the fourth sealing device (1000d), it is described as the first sealing device (1000a) in FIG. 3 and FIG. 4, and since the fourth sealing device (1000c) of FIG. 1 is closer to the use source (1) than the third sealing device (1000d), it is described as the second sealing device (1000b) in FIG. 3 and FIG. 4.

[0054] Referring to FIGS. 3 and 4, the water seal system includes a gas pipe (10) that transports gas by connecting a supply source (1) and a use source (2), and a first water seal device (1000a) and a second water seal device (1000b) provided in the gas pipe (10) to block the gas by a water seal.

[0055] In a general situation, as illustrated in FIG. 3, the supplier (1) supplies byproduct gas to the user (2) through the gas pipe (10). At this time, the water sealing parts (20a) (20b) of the first water sealing device (1000a) and the second water sealing device (1000b) are open, and the gas recovery valve (130a) (130b) and the nitrogen supply valve (140a) (140b) are closed (indicated in black).

[0056] At this time, the byproduct gas passes sequentially through the supply side gas pipe (10a), water seal section (20a), and usage side gas pipe (10b) of the first water seal device (1000a), the supply side gas pipe (10c), water seal section (20b), and usage side gas pipe (10d) of the second water seal device (1000b), and is transported to the place of use (2).

[0057] Meanwhile, as illustrated in FIG. 4, when performing maintenance or replacement of the gas pipe (10), the first water seal device (1000a) and the second water seal device (1000b) block the flow of gas by water sealing. When water is supplied to the water seal portions (20a) and (20b) of the first water seal device (1000a) and the second water seal device (1000b) through a supply pipe (not shown), water fills the downwardly bent water seal portions (20a) and (20b). That is, the flow of gas between the supply-side gas pipe (10a) and the use-side gas pipe (10b) of the first water seal device (1000a) is blocked by water supplied to the water seal section (20a) of the first water seal device (1000a), and the flow of gas between the supply-side gas pipe (10c) and the use-side gas pipe (10d) of the second water seal device (1000b) is blocked by water supplied to the water seal section (20b) of the second water seal device (1000b). At this time, the gas recovery valves (130a) (130b) and nitrogen supply valves (140a) (140b) of the first water seal device (1000a) and the second water seal device (1000b) are blocked (indicated in black).

[0058] Even after the first water seal device (1000a) and the second water seal device (1000b) are blocked by the water seal, the byproduct gas already supplied remains in the gas pipe (10b) (10c) between the first water seal device (1000a) and the second water seal device (1000b).

[0059] In the disclosed invention, by controlling the opening and closing of the gas recovery valve (130a)(130b) and the nitrogen supply valve (140a)(140b) through the control unit (6000), the byproduct gas remaining in the gas pipe (10b)(10c) between the first water seal device (1000a) and the second water seal device (1000b) can be recovered to the supply side.

[0060] FIG. 5 is a schematic diagram illustrating a control unit according to one embodiment of the disclosed invention.

[0061] A water seal system according to one embodiment of the disclosed invention may further include a control unit (3000) that receives information from a pressure sensing unit (200a) (200b) and a gas sensing unit (300a) (300b) of two or more water seal devices (1000a) (1000b) and controls the opening and closing of a gas recovery valve (130a) (130b) and a nitrogen supply valve (140a) (140b) of two or more water seal devices (1000a) (1000b) to recover gas in a gas pipe between two or more water seal devices (1000a) (1000b).

[0062] As illustrated in FIG. 5, the control unit (3000) receives information from the pressure sensing unit (200a) (200b) and the gas sensing unit (300a) (300b) of the first water seal device (1000a) and the second water seal device (1000b), respectively. Additionally, the control unit (3000) can control the opening and closing of the gas recovery valve (130a) (130b) and the nitrogen supply valve (140a) (140b) of the first water seal device (1000a) and the second water seal device (1000b) based on the received information.

[0063] Meanwhile, the control unit (3000) can open and close the water seal unit (200) by directly controlling the opening and closing of the water supply valve (not shown), overflow valve (120), and drain valve (110) of the first water seal device (1000a) and the second water seal device (1000b), or it can open and close the water seal unit (200) by communicating with a water seal control unit (not shown) that controls the opening and closing of the water supply valve, overflow valve (120), and drain valve (110).

[0064] When recovering gas from the gas pipe (10) between two water seal devices (1000a) (1000b) provided in the gas pipe (10), the control unit (3000) can recover gas by opening the nitrogen supply valve (140b) of the second water seal device (1000b) that is closer to the place of use (2) among the two water seal devices (1000a) (1000b) that are blocked by water seals, and opening the gas recovery valve (130a) of the first water seal device (1000a) that is closer to the place of supply (1).

[0065] At this time, the control unit (3000) can open the gas recovery valve (130a) of the first water seal device (1000a) when the pressure in the supply-side gas pipe (10c) of the second water seal device (1000b) becomes higher than the pressure in the supply-side gas pipe (10a) of the first water seal device (1000a) by more than the first threshold value (a1).

[0066] Meanwhile, the control unit (3000) can block the gas recovery valve (130a) of the first water seal device (1000a) and the nitrogen supply valve (140b) of the second water seal device (1000b) when the carbon monoxide concentration in the gas pipe (10b) on the user side of the first water seal device (1000b) is below the second threshold (a2).

[0067] Below, the gas recovery method performed by the control unit (3000) as described above will be described in more detail.

[0068] FIG. 6 is a schematic diagram illustrating a gas recovery method of a water seal system according to one embodiment of the disclosed invention, and FIG. 7 and FIG. 8 are schematic diagrams illustrating the state of gas recovery of a water seal system according to one embodiment of the disclosed invention.

[0069] Referring to FIG. 6, a gas recovery method of a water seal system according to one embodiment of the disclosed invention comprises the steps of: blocking by water sealing a first water seal device (1000a) near the supply source (1) and a second water seal device (1000b) near the use source (2), which are provided in a gas pipe (10) connecting a supply source (1) and a use source (2); and opening a nitrogen supply valve (140b) of the second water seal device (1000b) to supply nitrogen gas to the supply-side gas pipe (10c) of the second water seal device (1000b) (520). The method may include: a step (540) of opening the gas recovery valve (130a) of the first water seal device (1000a) to recover gas when the pressure in the supply-side gas pipe (10c) of the second water seal device (1000b) becomes higher than the pressure in the supply-side gas pipe (10a) of the first water seal device (1000a) by more than a first threshold (a1) (530); a step (550) of detecting the carbon monoxide concentration in the use-side gas pipe (10b) of the first water seal device (1000a); and a step (560) of shutting off the gas recovery valve (130a) of the first water seal device (1000a) and the nitrogen supply valve (140b) of the second water seal device (1000b) when the carbon monoxide concentration in the use-side gas pipe (10b) of the first water seal device (1000a) is less than or equal to a second threshold (a2).

[0070] In the gas recovery method of the water seal system, the first water seal device (1000a) and the second water seal device (1000b) are first sealed by water sealing (510). As described above, by controlling the opening and closing of the water supply valve, overflow valve (120), and drain valve (110) of the water seal device (1000), water can be filled into the water seal section (20a) (20b) as shown in FIG. 4 to block the flow of gas.

[0071] After the first water seal device (1000a) and the second water seal device (1000b) are sealed by the water seal, the control unit (3000) opens the nitrogen supply valve (140b) of the second water seal device (1000b) to supply nitrogen gas to the supply side gas pipe (10c) of the second water seal device (1000b) (520). The nitrogen supply pipe (70) is connected to the supply side gas pipe (10c) of the second water seal device (1000b) to supply nitrogen gas. Meanwhile, because the first water seal device (1000a) and the second water seal device (1000b) are sealed by the water seal, the pressure in the gas pipe (10b) (10c) between the first water seal device (1000a) and the second water seal device (1000b) increases as nitrogen gas is supplied.

[0072] Subsequently, the control unit (3000) receives the pressure (first pressure) in the supply side gas pipe (10a) of the first water sealing device (1000a) and the pressure (second pressure) in the supply side gas pipe (10c) of the second water sealing device (1000b) from the first pressure sensing unit (200a) of the first water sealing device (1000a) and the second pressure sensing unit (200b) of the second water sealing device (1000b), respectively.

[0073] At this time, the control unit (3000) determines whether the second pressure is higher than the first pressure by more than the first threshold (a1) (530). As nitrogen gas is supplied, the second pressure gradually increases. When the second pressure is higher than the first pressure by more than the first threshold (a1), the control unit (3000) opens the gas recovery valve (130a) of the first water seal device (1000a). When the gas recovery valve (130a) of the first water seal device (1000a) is opened while the second pressure is higher than the first pressure, the byproduct gas remaining in the gas pipe (10b) (10c) between the first water seal device (1000a) and the second water seal device (1000b) due to the second pressure is recovered to the supply side gas pipe (10a) through the gas recovery pipe (60a) of the first water seal device (1000a). FIG. 7 illustrates the appearance of byproduct gas being recovered (solid arrow) when the gas recovery valve (130a) of the first water seal device (1000a) is opened (indicated in white). At this time, the byproduct gas can be continuously recovered because nitrogen gas is continuously supplied (dotted arrow) through the nitrogen supply pipe (70b) of the second water seal device (1000b).

[0074] Meanwhile, the first threshold (a1) may be determined as a preset fixed value, or it may be determined in proportion to the pressure in the supply-side gas pipe (10c) of the first water seal device (1000b). For example, the first threshold (a1) may be determined as a preset fixed value (e.g., 0.1 MPa), or it may be determined in proportion to the first pressure (e.g., 10% of the first pressure).

[0075] When recovering by-product gas by continuously supplying nitrogen gas in this manner, the control unit (3000) can detect the concentration of carbon monoxide in the gas pipe (10b) on the user side of the first water seal device (1000a) (550). Since the by-product gas contains carbon monoxide, the concentration of carbon monoxide can be detected to check whether the by-product gas remains.

[0076] The control unit (3000) blocks the gas recovery valve (130a) of the first water seal device (1000a) and the nitrogen supply valve (140b) of the second water seal device (1000b) when the carbon monoxide concentration in the gas pipe (10b) on the user side of the first water seal device (1000a) is below the second threshold (a2) (560).

[0077] As illustrated in FIG. 8, when the recovery of byproduct gas is completed and the gas pipe (10b) (10c) between the first water seal device (1000a) and the second water seal device (1000b) is filled with nitrogen gas (dotted arrow), the carbon monoxide concentration detected by the first gas detection unit (300a) provided in the gas pipe (10b) on the usage side of the first water seal device (1000a) becomes very low. That is, when the carbon monoxide concentration in the gas pipe (10b) on the usage side of the first water seal device (1000a) is below the second threshold (a2), it can be determined that the recovery of byproduct gas inside the gas pipe (10b) (10c) between the first water seal device (1000a) and the second water seal device (1000b) is completed. After the recovery of byproduct gas is completed in this manner, the control unit (3000) can stop the supply of nitrogen gas by blocking the gas recovery valve (130a) of the first water seal device (1000a) and the nitrogen supply valve (140b) of the second water seal device (1000b), thereby preventing the recovered byproduct gas from flowing back through the gas recovery pipe (60) of the first water seal device (1000a).

[0078] In this way, after the recovery of byproduct gas is completed, only nitrogen gas, which is an inert gas, remains in the gas pipe (10b) (10c) between the first water seal device (1000a) and the second water seal device (1000b), so maintenance or replacement work on the gas pipe (10) can be safely performed. Explanation of the symbols

[0079] 1: Supplier 2: User 10: Gas piping 20: Water seal 30: Overflow pipe 40: Drain pipe 50: Overflow discharge pipe 60: Gas recovery pipe 70: Nitrogen supply pipe 80: Radiation pipe 1000: Water seal device 2000: Gas seal port 3000: Control unit 110: Drain valve 120: Overflow valve 130: Gas recovery valve 140: Nitrogen supply valve 150: Diffusion valve 200: Pressure sensor 300: Gas sensor

Claims

Claim 1 delete Claim 2 delete Claim 3 delete Claim 4 delete Claim 5 delete Claim 6 A gas pipeline connecting a supply source and a use source; two or more water seal devices provided in the gas pipeline; and a control unit for controlling the two or more water seal devices; wherein the water seal devices include: a water seal section formed to be bent downward between the supply side and the use side of the gas pipeline to block gas flow by the water seal; a gas recovery pipe provided with a gas recovery valve that communicates between the supply side and the use side of the gas pipeline by bypassing the water seal section and controls gas flow; and a nitrogen supply pipe provided with a nitrogen supply valve that supplies nitrogen gas to the supply side of the gas pipeline and controls the supply of nitrogen gas. A water seal system comprising: a pressure sensing unit provided on the supply side of the gas pipe to detect the pressure of the gas pipe; wherein, when recovering gas from a gas pipe between two water seal devices provided in the gas pipe, the control unit opens the nitrogen supply valve of the second water seal device closer to the point of use among the two water seal devices blocked by the water seal, and opens the gas recovery valve of the first water seal device closer to the supply point among the two water seal devices to recover the gas, wherein when the pressure in the supply side gas pipe of the second water seal device becomes higher than the pressure in the supply side gas pipe of the first water seal device by more than a first threshold, the gas recovery valve of the first water seal device is opened, and the first threshold is determined in proportion to the pressure in the supply side gas pipe of the first water seal device. Claim 7 In claim 6, the water sealing device further comprises a gas detection unit provided on the use side of the gas pipe to detect the carbon monoxide concentration of the gas pipe; a water sealing system. Claim 8 In claim 7, the control unit receives information from the pressure sensing unit and the gas sensing unit of two or more water seal devices and controls the opening and closing of the gas recovery valve and the nitrogen supply valve of two or more water seal devices to recover gas in the gas piping between the two water seal devices. Claim 9 delete Claim 10 delete Claim 11 delete Claim 12 In claim 8, the control unit is a water seal system that blocks the gas recovery valve of the first water seal device and the nitrogen supply valve of the second water seal device when the carbon monoxide concentration in the gas pipe on the user side of the first water seal device is below a second threshold. Claim 13 A method for recovering gas in a sealing system, comprising: a step of blocking a first sealing device near a supply source and a second sealing device near a use source by means of a sealing device provided in a gas pipeline connecting a supply source and a use source; a step of opening a nitrogen supply valve of the second sealing device to supply nitrogen gas to the supply-side gas pipeline of the second sealing device; and a step of recovering gas by opening a gas recovery valve of a gas recovery pipe that communicates by bypassing the sealing section between the supply-side and use-side of the gas pipeline of the first sealing device when the pressure in the supply-side gas pipeline of the second sealing device becomes higher than the pressure in the supply-side gas pipeline of the first sealing device by a first threshold value; wherein the first threshold value is determined in proportion to the pressure in the supply-side gas pipeline of the first sealing device. Claim 14 delete Claim 15 A gas recovery method of a water seal system according to claim 13, further comprising: a step of detecting a carbon monoxide concentration in the gas pipe on the user side of the first water seal device; and a step of shutting off the gas recovery valve of the first water seal device and the nitrogen supply valve of the second water seal device when the carbon monoxide concentration in the gas pipe on the user side of the first water seal device is below a second threshold.

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