JP4330115B2 - Piping structure penetrating container outer shell and method for replacing the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for pipe replacement and its structure.
[0002]
[Prior art]
In the LPG (liquefied gas) storage tank, BOG (boil-off gas) may be generated due to natural heat input or the like and the internal pressure may increase. Therefore, it is necessary to suppress the generation of BOG and maintain the internal pressure constant.
[0003]
FIG. 2 shows an example of a BOG suppression device in a conventional LPG storage tank. This suppression device guides a part of LPG pumped out by the pump 52 in the LPG storage tank 51 to the heat exchanger 54, where the LNG is supplied from a LNG (liquefied natural gas) line 57 by the cold heat (−162 ° C.) of LNG. The LPG is supercooled, this supercooled LPG is supplied from the return line 55 to the spray device 56 in the LPG storage tank 51 and sprayed, and the BOG in the LPG storage tank 51 is cooled and condensed to suppress the generation of BOG. ing.
[0004]
In FIG. 2, 58 is a supercooling LPG adjustment valve, 59 is an LNG adjustment valve, and 60 is returned from the return line 55 into the LPG storage tank 51 so that the pressure detected by the pressure detector 60a in the LPG storage tank 51 becomes constant. A control device that feedback-controls the amount of supercooled LPG to be dispersed, 61 is an LNG control device that controls the LNG adjustment valve 59 so that the temperature of the supercooled LPG is constant, and 62 is an LPG receiving line.
[0005]
Moreover, as the spray device 56 in the LPG storage tank 51 as described above, an injection nozzle attached to the upper part in the LPG storage tank 51 for injecting the supercooled LPG in a divergent shape (see, for example, Patent Document 1). In addition, an injection nozzle (see, for example, Patent Document 2) attached to the liquid phase at the bottom of the LPG storage tank 51 for injecting the supercooled LPG in a divergent form has been proposed.
[0006]
[Patent Document 1]
Japanese Patent Laid-Open No. 08-178189 [Patent Document 2]
Japanese Patent Laid-Open No. 08-178191
[Problems to be solved by the invention]
However, if the spray tip at the tip of the supercooled LPG spray nozzle is blocked due to freezing or the like during operation of the LPG storage tank and needs to be replaced, the conventional nozzle structure as described above is very replaceable. There was a problem that it was difficult.
[0008]
The present invention is intended to solve the above-described problems, and provides a method for easily replacing nozzles used for spraying supercooled LPG in an LPG storage tank and a piping structure therefor. It is aimed.
[0009]
[Means for Solving the Problems]
In order to achieve such an object, the present invention has the following configuration.
[1] A piping structure that penetrates the outer shell of the container, comprising an outer pipe provided through the outer shell of the container, an inner pipe that is inserted through the outer pipe and is detachable from the outer pipe, The outer tube and the inner tube are detachable at a position closer to the container outer shell than the detachable portion between the external piping system and the inner tube, and the outer tube is connected to the inner tube from the detachable portion. A gas seal member into which the inner pipe is inserted in order toward the outer shell of the container, a purge gas feeding means, and a shut-off valve that allows the inner pipe to be inserted in an open state. A piping structure penetrating the outer shell of the container, characterized in that it is provided with a closing means for gas-sealing.
[2] closing means in the tube that is a gas bag supplying device for introducing the gas bag and the gas bag closing the inner pipe in said pipe portion by being inserted expanded into said tube portion A piping structure that penetrates the outer shell of the container according to [1] above.
[3] In the piping structure penetrating the container outer shell according to [1] or [2] above, a method for replacing the pipe penetrating the container outer shell, the step of removing the existing inner pipe; And a step of attaching the newly installed inner pipe. The removing process includes a step of closing the existing inner pipe, a step of separating the existing inner pipe and the external piping system, and the existing inner pipe and the outer pipe. And a step of closing the shutoff valve after pulling out the existing inner pipe from the outer pipe while supplying purge gas into the pipe of the outer pipe. Opening the shut-off valve while feeding purge gas into the pipe, inserting the new inner pipe into the outer pipe, joining the new inner pipe and the outer pipe, and the new inner pipe fed and a step of bonding the external piping system, a purge gas into the tube of the outer tube While the pipe passing through the container shell, characterized in that a step of releasing the blockage of the newly inner tube which was closed in the step of inserting into the outer tube the newly inner tube is opened the shut-off valve Exchange method.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0011]
FIG. 1 is an explanatory view showing an embodiment of a piping structure according to the present invention.
[0012]
In FIG. 1, 1 is an outer pipe, 2 is an inner pipe, 3 is an external piping system, and 31 is a container outer shell.
[0013]
In this embodiment, the container is an LPG storage tank, and the supercooled LPG for suppressing BOG is introduced into the LPG storage tank through the external piping system 3 and the inner pipe 2.
[0014]
In this embodiment, a gas bag and its charging means are used as the closing means for the inner tube, and nitrogen gas is used as the purge gas.
[0015]
The outer tube 1 is attached by welding or the like through the end plate of the LPG storage tank forming the container outer shell 31, and communicates the inside and the outside of the LPG storage tank. A joint flange 21 b with the inner tube 2 is provided at the outer end of the outer tube 1. A gas seal 1s made of Teflon (registered trademark) or the like for fitting the outer peripheral surface of the inner tube 2 is provided on the inner peripheral surface of the outer tube 1 in the vicinity of the joining flange 21b. Further, a shutoff valve 16 composed of a gate valve or the like is provided near the container outer shell 31 on the outer side of the outer tube 1. The shutoff valve 16 can be inserted through the inner tube 2 in the open state. A branch pipe 1a is provided between the gas seal 1s and the shutoff valve 16, and a valve 15 made of a ball valve or the like is attached.
[0016]
A part of the inner tube 2 is inserted into the outer tube 1. A nozzle 2n for spraying the supercooled LPG into the LPG storage tank is provided at the inner end of the inner pipe 2. Further, a joining flange 21a with the outer pipe 1 is provided at an intermediate portion of the inner pipe 2, and a joining flange 22a with the outer piping system 3 is provided at an outer end portion. A branch pipe 2a is provided between the joining flange 21a and the joining flange 22a, and a valve 14 such as a gate valve is attached.
[0017]
The external piping system 3 is provided with a joining flange 22b with the inner pipe 2 at one end thereof. A valve 13 made of a gate valve or the like is provided on the upstream side of the joint flange 22b, and a valve 11 made of a gate valve or the like is further provided on the upstream side. A branch pipe 3a is provided between the valve 13 and the valve 11, and a valve 12 such as a ball valve is attached.
[0018]
Next, a procedure for exchanging the inner pipe in the piping structure of the present embodiment configured as described above will be described.
[0019]
First, the procedure for removing the existing inner pipe (denoted as inner pipe 2) will be described in the following [1] to [4].
[1] The valves 11 and 13 are closed in this order to stop the supply of the supercooling LPG from the upstream side, and the valve 12 is opened to drain the drain liquid.
[2] The valve 14 is opened and a gas bag is inserted into the inner pipe 2 via the branch pipe 2a to inflate, thereby preventing the internal gas of the LPG storage tank from leaking outside through the inner pipe 2. .
[3] The joint flanges 22a and 22b of the inner pipe 2 and the outer pipe system 3 and the joint flanges 21a and 21b of the inner pipe 2 and the outer pipe 1 are separated.
[4] The valve 15 is opened and nitrogen gas is fed into the outer pipe 1 via the branch pipe 1a, while the inner pipe 2 is pulled out and the shutoff valve 16 is closed. At this time, the shutoff valve 16 is closed after the nozzle 2n at the tip of the inner tube 2 passes through the shutoff valve 16 and before passing through the gas seal 1s so that the internal gas of the LPG storage tank does not leak to the outside. Thereafter, the valve 15 is closed.
[0020]
Next, the procedure for mounting a new inner pipe (referred to as inner pipe 2 in the same manner as the existing inner pipe) will be described in the following [5] to [10].
[5] Insert the inner tube 2 into the outer tube 1 until the nozzle 2n at the tip of the inner tube 2 reaches just before the shutoff valve 16.
[6] Open the valve 15 and open the shutoff valve 16 while feeding nitrogen gas into the outer pipe 1 via the branch pipe 1a.
[7] Insert the inner tube 2 into the outer tube 1 to a predetermined installation position.
[8] The joining flanges 21a and 21b of the inner pipe 2 and the outer pipe 1 and the joining flanges 22a and 22b of the inner pipe 2 and the outer piping system 3 are joined, respectively. Thereafter, the valve 15 is closed.
[9] The gas bag inserted into the inner pipe 2 via the branch pipe 2a is contracted and pulled out, and the valve 14 is closed.
[10] The valve 12 is closed and the valves 13 and 11 are opened in this order to restart the supply of the supercooling LPG from the upstream side.
[0021]
According to the replacement method described above, it is possible to replace the inner tube without diffusing leak gas around the LPG storage tank even when the LPG storage tank is in operation.
[0022]
In this embodiment, the pipe connected to the spray nozzle of the supercooled LPG used for BOG suppression in the LPG storage tank has been described as an example. However, the pipe structure and the replacement method of the present invention communicate with other container shells. The present invention can also be applied to piping to be used. Needless to say, the presence or absence of the nozzle at the tip of the inner tube has nothing to do with the essence of the present invention.
[0023]
【The invention's effect】
According to the piping structure of the present invention and the replacement method described above, it is easy to replace piping used under severe conditions such as a supercooled LPG spray nozzle for suppressing BOG in an LPG storage tank, which has been extremely difficult in the past. Can be done.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing an embodiment of a piping structure according to the present invention. FIG. 2 is an explanatory view showing a BOG suppressing device in a conventional LPG storage tank.
DESCRIPTION OF SYMBOLS 1 Outer pipe 1a Branch pipe 1s Gas seal 2 Inner pipe 2a Branch pipe 2n Nozzle 3 External piping system 3a Branch pipe 11-16 Valve 21a, 21b Joint flange 22a, 22b Joint flange 31 Outer shell 51 LPG storage tank 52 Pump 53 Pumping line 54 Heat exchanger 55 Supercooled LPG return line 56 Spray device 57 LNG line 58 Supercooled LPG control valve 59 LNG control valve 60 Control device 60a Pressure detector 61 LNG control device 62 LPG receiving line

Claims (3)

  A piping structure that penetrates the outer shell of the container, comprising an outer pipe provided through the outer shell of the container, and an outer pipe system that is inserted into the outer pipe and is detachable from the outer pipe. The inner tube is detachable at a position closer to the container outer shell than the detachable portion between the external piping system and the inner tube, and the outer tube is connected to the container outer shell from the detachable portion with the inner tube. A gas seal member into which the inner pipe is inserted, a purge gas feeding means, and a shut-off valve that allows the inner pipe to be inserted in an open state, and the inner pipe has a gas seal inside the pipe. A piping structure penetrating the outer shell of the container, characterized in that it comprises a closing means. Closing means of the inner tube, and characterized in that the gas bag and the gas bag to close the inner tube by being inserted expanded into said pipe portion is a gas bag dosing means for dosing within said tube portion The piping structure which penetrates the container outer shell according to claim 1. The piping structure that penetrates the container outer shell according to claim 1 or 2, wherein the pipe that penetrates the container outer shell is a method for exchanging the existing inner pipe, and a subsequent new inner pipe. And the removing step includes a step of closing the existing inner pipe, a step of separating the existing inner pipe and the external piping system, and a step of separating the existing inner pipe and the outer pipe. And a step of closing the shut-off valve after pulling out the existing inner pipe from the outer pipe while feeding purge gas into the pipe of the outer pipe, and the mounting step includes supplying the purge gas into the pipe of the outer pipe. Opening the shut-off valve while feeding, inserting the new inner pipe into the outer pipe, joining the new inner pipe and the outer pipe, the new inner pipe and the external piping system; and bonding a fed Shinano purge gas into the tube of the outer tube Pipes penetrating the container shell, characterized in that a step of releasing the blockage of the newly inner tube which has been closing the new inner pipe by opening the al the shutoff valve in the step of inserting into said outer tube Exchange method.

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