JPH0447519Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a device for entering and exiting work inside a tank, and is used when entering and exiting a tank whose internal pressure is maintained at positive pressure and which has been replaced with an inert gas. This relates to a device used for.

[Conventional technology] Conventionally, when entering a tank for storing flammable gas such as LPG or LNG for maintenance and inspection, it was necessary to prevent the combustible gas remaining in the tank from exploding. For this purpose, a method was adopted in which the atmosphere inside the tank was replaced with an inert gas such as nitrogen gas, the replaced inert gas was further replaced with air, and then the required work was performed by entering the tank. When finishing the work inside the tank, it was also replaced with inert gas and then filled with liquid as a flammable gas. As described above, it is not economical to repeatedly replace the inside of the tank with inert gas, and there are problems in that the construction period is prolonged.

Therefore, a method is being developed in which the tank is filled with inert gas and work can be carried out by entering and exiting the tank.

Furthermore, for multi-shell tanks, methods have been proposed in which the internal pressure is positive to prevent flammable gas or outside air from flowing into the tank from the outside, such as through a cold insulation layer.

[Problem that the invention aims to solve] However, when performing maintenance and inspection work inside the tank, if the inside of the tank is replaced with an inert gas and the pressure is increased to maintain a positive pressure inside the tank, it is difficult to enter the inside of the tank. At present, no fully satisfactory device has been proposed yet.

Japanese Unexamined Patent Publication No. 57798/1984 proposes a device in which a tank that has been replaced with an inert gas is entered through an atmosphere communication chamber and a tank communication room that are also replaced with an inert gas. However, in this proposal, since inert gas is supplied to both communication chambers from a special inert gas supply means such as a compressor, it is necessary to monitor and control the pressure in each communication chamber, which reduces safety and reliability. This is still not enough.

The present invention has been devised to effectively solve the above problems.

[Means for Solving the Problems] In order to achieve the above object, the present invention allows workers etc. to go in and out of a multi-shell tank whose internal atmosphere is replaced with an inert gas and maintained at positive pressure. A tank access/exit device for in-tank work, comprising: a tank communication chamber installed at an opening formed for entering and exiting the tank; an atmospheric communication chamber connected to the tank communication room; A first opening/closing door for opening and closing between the communication room and the atmosphere communication room, a second opening/closing door for entering and exiting the atmosphere communication room from the atmosphere side, and connected to each of the tank communication room and the atmosphere communication room, An exhaust system that discharges the gas in these rooms, an inert gas supply system that is connected between the inside of the tank and the tank communication room and supplies the inert gas in the tank to the tank communication room, and a communication between the tank communication room and the atmosphere. a communication supply system connected between the rooms and supplying gas in the tank communication chamber to the atmosphere communication chamber;
The control valve is provided on a partition wall between the tank communication chamber and the atmosphere communication chamber to equalize the internal pressures of both chambers.

[Function] According to the above configuration, the inert gas in the tank is supplied to both the tank communication chamber and the atmosphere communication chamber by the inert gas supply system and the communication supply system. At this time, the capacity inside the tank is much larger than the capacity of both communication chambers, and the inside of the tank is maintained at positive pressure, so by simply flowing inert gas from inside the tank to both chambers, The pressure and atmosphere will be almost the same as the pressure and atmosphere inside the tank. Furthermore, since the inert gas is supplied to the atmosphere communication chamber via the tank communication chamber by the communication supply system, the airtightness within the tank is maintained even if the gas within the tank is used.

[Example] An example of the present invention will be described below in detail with reference to the accompanying drawings.

As shown in FIG. 2, a device 2 according to the present invention is installed in a cryogenic tank 1 for storing cryogenic liquids such as LNG and LPG in order to enter inside the tank and carry out maintenance and inspection work.

LNG stored inside the cryogenic tank 1,
The device 2 of the present invention discharges flammable gas such as LPG to the outside, fills the inside with inert gas such as nitrogen gas to replace the internal atmosphere, and boosts the internal pressure to maintain positive pressure. It can be attached to 1.

As shown in FIG. 1, the in-tank work entry/exit device 2 of the present invention is mainly used for a tank that is detachably attached to an opening formed in a tank side plate, a roof plate, etc., or a manhole, etc. in order to enter and exit the tank. a communication room 3; an atmosphere communication room 4 connected to the tank communication room 3; a first opening/closing door 5 for opening and closing between the atmosphere communication room 4 and the tank communication room 3;
A second opening/closing door 6 provided in the atmosphere communication chamber 4 for entering and exiting from the atmosphere side, and a conversion door 6 for converting the tank communication chamber 3 and the atmosphere communication chamber 4 into the internal pressure and internal atmosphere of the tank 1. It consists of means 7.

As shown in the figure, the tank communication chamber 3 and the atmosphere communication chamber 4 are constructed so as to face the atmosphere from the outside of the tank 1 and to be connected in series.

An opening 9 is provided in the tank communication chamber 3 so as to be connected to an opening 29 in the side plate 19 of the tank 1 or a manhole 8 or the like. Also, a partition wall 10 that partitions the tank communication room 3 and the atmosphere communication room 4 is provided.
An entrance/exit 11 is provided for mutual access, and the entrance/exit 11 is provided with a first opening/closing door 5 for sealing each chamber.

On the other hand, the atmosphere communication chamber 4 is provided with an entrance/exit 12 for entering/exiting the atmosphere side, and this entrance/exit 1
2 is provided with a second opening/closing door 6 for opening/closing and sealing it. Of course, the entrances and exits 11 and 12 may face outward.

The atmospheric communication chamber 4 and the tank communication chamber 3 are each provided with a conversion means 7 for making the internal atmosphere or internal pressure equal to that inside the tank 1.
This converting means 7 is connected to an exhaust system 30 that is connected to each of the tank communication chamber 3 and the atmosphere communication chamber 4 and exhausts the gas in these chambers 3 and 4, and is connected to the inside of the tank 1 and the tank communication chamber 3. An inert gas supply system 13 (Fig. 2) that supplies inert gas such as nitrogen gas in the tank 1 to the tank communication chamber 3, and an inert gas supply system 13 (Fig. Communication supply system 14 that supplies gas to the atmosphere communication chamber 4
It is composed of. The inert gas supply system 13 and the communication supply system 14 are connected to the corresponding communication chambers 3 and 4 via flow rate regulating valves 15 and 16. An exhaust valve 1 is provided in the exhaust system 30 connected to each communication chamber 3, 4.
7 is provided. Further, each communication chamber 3, 4 is provided with a safety valve 28.

The partition wall 10 is provided with a regulating valve 18 for equalizing the indoor atmosphere and internal pressure of the tank communication chamber 3 and the atmosphere communication chamber 4.

Further, the opening 9 of the tank communication chamber 3 is connected to the side plate 19 of the tank 1, the manhole 8, etc. in a sealed manner.

In the embodiment shown in FIG. 1, the opening 9 is removably sealed and attached to a side plate 19 and a bottom plate 20 of the tank 1.

As shown in Figure 3, the opening 9 of the tank communication chamber 3
The end edge 21 is joined to the side plate 19 by welding 22 to improve sealing performance.

Furthermore, FIG. 4 shows an edge 21 forming the opening 9.
and a flange 23 extending radially outward.
A gasket 24 is interposed between the flange 23 and the tank side plate 19, and the tank communication chamber 3 is joined to the tank 1 with bolts 25. Furthermore, in order to improve the sealing performance, a sealant 26 is applied inside the gasket 24 as shown in FIG.
The tank communication chamber 3 and the tank 1 may be connected by adding a .

The operation of the present invention will be described based on the above configuration.

Figures 1 and 2 show the inner tank 3 of the double shell tank 1.
1 shows an example when performing maintenance and inspection work under the bottom plate 32 of No. 1. Inner tank 3 as the inside of tank 1
1 and an outer tank 27.
The bottom of the chamber is filled with an inert gas to replace the gas, and the internal pressure is increased to maintain a positive pressure. At the same time, the opening 9 of the tank communication chamber 3 of the device 2 is sealed and joined to the tank side plate 19. Alternatively, if the tank 1 has a manhole 8 in advance, the tank communication chamber 3 may be connected to the manhole 8.

Next, the second opening/closing door 6 is opened and the working tools are brought into the atmosphere communication chamber 4, after which the second opening/closing door 6 is closed. At this time, it goes without saying that workers must carry air breathing equipment with them when entering the facility. After the worker enters the atmosphere communication room 4, the atmosphere communication room 4 and the tank communication room 3 are connected to the inert gas supply system 13 and the communication supply system 14.
And the same atmosphere and pressure as inside the tank 1 is made by the exhaust system 30. In addition, the inert gas supply system 13
After converting the chamber 3 to the same as the inside of the tank, both chambers may be made to have the same atmosphere and pressure by the regulating valve 18. Then, the first opening/closing door 5 is opened and the tank communication chamber 3 is entered into the tank communication chamber 3. Close the opening/closing door 5. After entering the tank communication room 3, the operator creates an opening 29 or opens the manhole 8 if there is one, and enters the work area inside the tank 1 to work.

Next, when exiting from the pressurized tank 1 to the atmosphere, return to the tank communication room 3, and then return to the atmosphere communication room 4.
The second opening/closing door 6 is closed, and the pressure in both chambers is equalized by the regulating valve 18, and the first opening/closing door 5 is opened to move into the atmosphere communication chamber 4. After that, the regulating valve 18 and the door 5 are closed.
is closed, the exhaust valve 17 is opened to reduce the pressure, and the second opening/closing door 6 is opened to exit to the atmosphere. In particular, when the pressure inside the tank 1 is increased, the tank communication chamber 3 and the atmosphere communication chamber 4 function as pressure equalization chambers.

As described above, according to this embodiment, it is possible to directly enter and exit the tank 1 maintained at a positive pressure and replaced with an inert gas while preventing air from entering.
Even if flammable gas remains inside the tank, an explosion accident will not occur, making work inside the tank safer.

In particular, in this device 2, the inert gas in the tank 1 is supplied to the communication chambers 3 and 4 by the inert gas supply system 13 and the communication supply system 14, so that reliability and safety can be improved. . That is, the capacity of tank 1 is much larger than that of communication rooms 3 and 4,
Further, since the tank 1 is always maintained at a constant positive pressure, the pressure in the chambers 3 and 4 can be set to be almost the same as that in the tank 1 by simply supplying the gas in the tank 1 to both chambers 3 and 4. Therefore, the pressure control that is normally performed is unnecessary, and safety and reliability can be improved. Of course, at this time, the internal pressure of the tank 1 hardly changes.

Additionally, by supplying the gas in the tank 1 to the communication chambers 3 and 4, these chambers 3 and 4 can be replaced with inert gas in a short time, reducing the time workers spend in the inert gas. Therefore, safety can be improved in this respect as well.

In addition, in this device 2, the inert gas in the tank 1 is supplied to the atmosphere communication chamber 4 via the tank communication chamber 3 by the communication supply system 14, so the gas flow from the tank side to the communication chamber side is always ensured. , it is possible to prevent the air in the atmosphere communication chamber 4 from flowing back into the tank 1,
This eliminates the risk of an explosive atmosphere inside the tank. Moreover, when the atmosphere communication chamber 4 has the same pressure as the inside of the tank 1, the tank communication chamber 3 is always under the same conditions, so the user can enter the tank communication chamber 3 with peace of mind.

Further, since a regulating valve 18 is provided between the tank communication chamber 3 and the atmosphere communication chamber 4 to equalize the internal pressures of both chambers, the first opening/closing door 5 can be opened and closed manually.

FIG. 5 shows a modified embodiment in which the atmosphere communication room 4 is divided into a worker's room 41 and a work tool loading/unloading room 42.

[Effects of the invention] In summary, the present invention provides the following excellent effects.

(1) Since the inert gas inside the tank is supplied to the tank communication room and the atmosphere communication room, the gas pressure in these communication rooms can be easily and reliably made almost the same as the pressure inside the tank, allowing work to be performed with high reliability and safety. personnel can enter and leave the tank.

(2) In addition, since the inert gas in the tank is supplied to the atmosphere communication room through the tank communication room, it is possible to reliably prevent the atmosphere from the atmosphere communication room from flowing into the tank, and the sealing performance inside the tank can be improved. Can be secured in good condition.

[Brief description of the drawings]

Fig. 1 is a schematic side sectional view showing an embodiment of the present invention, Fig. 2 is a schematic diagram showing an example in which the device of the present invention is applied to a low-temperature tank, and Figs. FIG. 5 is a partial side sectional view showing a connected state, and a schematic view showing a modified embodiment. In the figure, 1 is a tank, 2 is this device, 3 is a tank communication room, 4 is an atmosphere communication room, 5 is a first opening/closing door, 6 is a second opening/closing door, 7 is a conversion means, and 13 is an inert gas. Supply system, 14 is a communication supply system, 18 is a regulating valve, 30
is the exhaust system.

Claims (1)

[Scope of utility model registration request] An in-tank work entry/exit device for allowing workers, etc. to enter/exit the inside of a multi-shell tank whose internal atmosphere is replaced with an inert gas and maintained at positive pressure, and is formed for accessing the tank. A tank communication room located and attached to an opening etc., an atmospheric communication room connected to the tank communication room,
A first opening/closing door that opens and closes between the tank communication room and the atmosphere communication room, a second opening/closing door for entering and exiting the atmosphere communication room from the atmosphere side, and each of the tank communication room and the atmosphere communication room. an exhaust system that is connected to the tank and discharges the gas in these chambers, an inert gas supply system that is connected between the tank and the tank communication room and supplies inert gas in the tank to the tank communication room, and the tank communication room. A communication supply system is connected between the tank communication chamber and the atmosphere communication chamber, and supplies the gas in the tank communication chamber into the atmosphere communication chamber, and the communication supply system is installed on the partition wall between the tank communication chamber and the atmosphere communication chamber, and is installed on the partition wall between the tank communication chamber and the atmosphere communication chamber, and is connected to the communication supply system that supplies the gas in the tank communication chamber to the atmosphere communication chamber. An in-tank work entry/exit device characterized by being equipped with a regulating valve for carrying out work in a tank.