JPH039031B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a novel in-tank working chamber, particularly
This invention relates to an in-tank work room that can improve the safety of the work area as much as possible when entering into tanks storing flammable gases such as LNG and LPG for maintenance and inspection work.

[Prior Art] Generally, when performing maintenance and inspection work on the inside of a tank that stores flammable gas such as LNG or LPG, after draining out the liquid stored in the tank, the internal atmosphere is replaced with an inert gas such as _N2 gas. It is being replaced with .

Recently, a method has been developed in which workers directly enter a tank that has been replaced with an inert gas.

[Problem to be solved by the invention] By the way, in the case of low-temperature tanks for storing low-temperature combustible gases such as LNG and LPG, a multi-shell tank as shown in Fig. 3 is used, and the diameter is
The size has now been increased to 60m.

As shown in the figure, an outer tank 6 and a bottom cold insulation layer 2 are provided on a foundation 1 provided on the ground, and an inner tank 3 that substantially stores the low-temperature liquid W is formed on the bottom cold insulation layer 2. ing. An outer tank 6 is provided to cover the inner tank 3 so as to form a predetermined side cold insulating layer 4 and an upper cold insulating layer 5 on the outer periphery thereof. In this illustrated example, the upper part of the inner tank 3 is open, and a suspended ceiling 8 is placed over the opening 7 to cover it.
is provided. A cold insulating material is placed on this suspended ceiling 8 to form an upper cold insulating layer 5.

Further, a cold insulating space 9 formed between the outer circumference of the inner tank 3 and the outer tank 6 is filled with a cold insulating material such as pearlite particles to form a side cold insulating layer 4.

When performing maintenance and inspection on the inside of each cold storage layer or the inside of the inner tank 3 in such a low-temperature tank, it has been developed to replace the internal atmosphere with an inert gas and enter directly, as described above. However, as tanks become larger, for example, when performing maintenance and inspection on the inside of the bottom cold insulation layer 2, it is necessary to remove the liquid W stored in the inner tank 3.
Moreover, it is extremely uneconomical to replace the inner tank 3 with inert gas.

In addition, Utility Model Application Publication No. 49-83331 proposes a ``booth for repair work in large towers and tanks,'' and this proposal is based on the idea that the inert gas filled between diaphragms 1 and 2 can be used to expand the work booth. It merely holds the shape, and since a positive pressure is set between the diaphragms 1 and 2, there is a risk that flammable gas may enter the work area of the work booth.

Therefore, the present invention was devised to effectively solve the problems that occur when performing maintenance and inspection work on low-temperature tanks and the like that store flammable gas.

An object of the present invention is to limit the area to be replaced with inert gas to the maintenance and inspection work area, and to prevent the intrusion of flammable gas, etc., thereby improving work safety as much as possible. It provides a working room inside the tank.

[Means and Effects for Solving the Problems] In order to achieve the above object, the present invention provides a working area forming device used when entering a storage tank for flammable gas or the like to carry out maintenance and inspection work. A work chamber formed in an inner work area by surrounding it with a double partition wall, and a pressure reducing means for reducing the pressure inside the double partition wall of the work chamber and exhausting gas entering the inside of the partition wall to the outside. , is formed on the inner wall of the double partition wall that partitions the work room so as to be openable and closable, and is equipped with an exhaust hole to exhaust the atmosphere in the work room, so that only the work area surrounded by the double partition wall is closed. This makes it possible to set an atmosphere suitable for work such as replacing with active gas, and also reduces the pressure inside the double partition wall to constantly exhaust the internal atmosphere to prevent flammable gases from entering the work area. It is designed to prevent this.

[Example] As shown in FIGS. 1 and 2, a low temperature tank 1
0, the bottom plate 12 of this inner tank 11 and the outer tank 13
A bottom cold insulating layer 15 partitioned by a bottom plate 14 of
When carrying out maintenance and inspection work inside the area, the work area A
is surrounded by a double partition wall 16 to form a working room. The double bulkhead 16 will be assembled inside the tank. In the illustrated example, a tank entry/exit device 18 is provided on a side plate 17 of an outer tank 13 forming the outer shell of the tank 10 . This tank entry/exit device 1
8 is mainly composed of a tank communication room 19 and an atmosphere communication room 20, and the tank communication room 19 is connected to the outer tank 13.
The atmosphere communication chamber 20 is connected to the manhole 21 provided in the tank or the side plate 17 of the outer tank 13, and the atmosphere communication chamber 20 is provided with an atmosphere opening/closing door 22 for entering and exiting from the atmosphere side connected in series with the tank communication chamber 19. There is.

Further, the atmosphere communication chamber 20 and the tank communication chamber 19 are provided with an opening/closing door 23 for entering and exiting from each other.

The tank communication chamber 19 is provided with a first atmosphere replacement means 24 for adjusting the atmosphere or pressure to be equal to that inside the tank. Atmospheric communication room 2
0 is similarly provided with a second atmosphere replacing means 25, and is also provided with a regulating valve 26 for adjusting the atmosphere to be the same as that of the tank communication chamber 19.

In this way, the tank entry/exit device 18 is provided in advance on the side plate 17 of the tank, and the side plate 17 is opened from the tank communication chamber 19, or the working area A inside the tank is entered from the manhole 21. The tank will be entered through the tank entry/exit device 18, but first a part of the tank is replaced with an inert gas, and the tank communication chamber 19 is heated to the same atmosphere as the tank.
The atmosphere is replaced by the atmosphere replacement means 24. after that,
Open the atmosphere opening/closing door 22, enter the atmosphere communication room 20 wearing an air breathing apparatus, and after closing the atmosphere opening/closing door 22, replace the atmosphere with an inert gas by the second atmosphere replacement means 25 and adjust the atmosphere. Open the valve 26 to equalize the pressure in the tank communication chambers 19 and 20, open the opening/closing door 23, enter the tank communication chamber 19, and after fully getting used to the atmosphere inside the tank, open the manhole 21 or the side plate 17.
The tank is opened and the inside of the tank is accessed from the tank communication room 19.

On the other hand, when exiting from inside the tank, after entering the tank communication chamber 19 from inside the tank,
The operator opens the opening/closing door 23, enters the atmosphere communication room 20, closes the opening/closing door 23, and then opens the atmosphere opening/closing door 22, so that the atmosphere inside the tank, which has been replaced by the inert gas, is released to the outside. This will prevent this from happening.

As described above, the working area A inside the tank is replaced with an inert gas before entering the tank, and the double partition wall 16 is erected to surround the working area A to form a working chamber.

As shown in FIG. 2, this double partition wall 16 is composed of an outer wall 27 and an inner partition wall 28, and a predetermined distance 29 is formed between each of the outer partition wall 27 and the inner partition wall 28. During this time, the area 29 surrounds the work area A. During this time, a pressure reducing device 30, which is a means for reducing the pressure in order to constantly eliminate the internal atmosphere, is provided in the space 29.

This pressure reducing device 30 is composed of a blower or vacuum pump 31 and an intake pipe 32, and in the illustrated example, the intake pipe 32 is connected to the double partition wall 16 through the tank communication chamber 19 of the tank inlet/output device 18.

That is, after forming the double partition wall 16, the intake pipe 32 of the pressure reducing device 30 is connected to the double partition wall 16, and the inside of the pressure reducing device 29 between the double partition wall 16 is depressurized and the internal atmosphere is constantly exhausted to the outside. Prevents flammable gas etc. from entering the work chamber of work area A.

When the pressure inside the work chamber is higher than atmospheric pressure, the pressure inside the chamber 29 is reduced and exhausted according to the law of nature by opening the shutoff valve 37 even without the blower 31.

In this case, as shown in the figure, the inner partition wall 28 is provided with an exhaust hole 33 that can be opened and closed, and this exhaust hole 33 is provided with an exhaust opening/closing valve or a cap 34. , the atmosphere within the working chamber formed in the working area A is exhausted to the outside through the space 29.

As described above, the work area A in the tank is surrounded by the double partition wall 16 to form a work chamber, and the pressure inside the double partition wall 16 that partitions the work chamber is reduced to reduce the pressure inside the work area A. Inspection work will be carried out by entering the work chamber while preventing flammable gas etc. from entering the work chamber. Especially work area A
It is only necessary to sufficiently replace the inside of the tank with inert gas, and in the case of partial work, it is not necessary to completely replace the entire inside of the tank with inert gas, which is economical.

Further, by opening the exhaust hole 33 for exhausting the atmosphere in the work room, the work atmosphere containing dust, dirt, etc. can be exhausted to the outside, and an optimal work atmosphere can be maintained.

Furthermore, when necessary, all exhaust valves or caps 34 are closed, and as shown in FIG. By doing so, by filling the space between 29 and 29 with inert gas, in the unlikely event that flammable gas leaks from the low temperature tank 10 to 29,
9, no flammable gas will enter the work chamber, so the atmosphere can be introduced into the work chamber by using, for example, the air inlet pipe 24 in Figure 1, thereby increasing work safety as much as possible. can.

Further, the double partition wall 16 is reliably supported within the tank by a support frame 36, etc., as shown in FIG.

[Effects of the Invention] According to the present invention, the following excellent effects are achieved.

(1) Since the working area inside the tank is surrounded by a double partition wall, the area to be replaced with inert gas can be limited to that working area, and the inside of the tank in larger tanks can be Replacement with inert gas can be done economically.

(2) Since the interior between the double partition walls is depressurized by a decompression means to prevent intrusion of flammable gas, etc., safety during maintenance and inspection work can be increased as much as possible.

(3) The exhaust hole is opened and the atmosphere in the work room is exhausted, so an optimal work atmosphere can be maintained.

[Brief explanation of drawings]

FIG. 1 is a schematic side sectional view showing the working chamber in the tank of the present invention, FIG. 2 is a partial enlarged sectional view of FIG. 1,
FIG. 3 is a schematic diagram showing an example of a low temperature tank. In the figure, A is a working area, 16 is a double partition wall, and 30 is a pressure reducing device.

Claims (1)

[Claims] 1. A work area forming device used when entering a tank storing flammable gas, etc. for maintenance and inspection work, including a work chamber formed in the tank work area by surrounding it with a double partition; A pressure reducing means is provided for reducing the pressure inside the space between the double partition walls of the working chamber and exhausting gas entering the space between the partition walls to the outside; A work chamber inside the tank is equipped with an exhaust hole to exhaust the indoor atmosphere.