JP7294952B2 - How to dismantle the tank - Google Patents

Description

TECHNICAL FIELD The present invention relates to a tank dismantling method, and more particularly to a cylindrical tank dismantling method.

Conventionally, as a ground tank for storing cryogenic liquid (for example, liquefied natural gas, hereinafter referred to as "LNG"), a dome-shaped roof plate and a cylindrical roof supporting it from below Cylindrical tanks (eg 70 m diameter, 50 m high) are known, with side plates.

Cylindrical tanks are generally configured such that a roof plate and a side plate are connected via a ring-shaped knuckle plate (also called a knuckle ring) (see Patent Documents 1 and 2).

By the way, when dismantling a cylindrical tank with such a knuckle plate, usually
(a) First, dismantle the shingles,
(b) then disassemble the knuckle plate;
(c) then dismantling the side plates;
The work is done by following these steps.

In particular, when the knuckle plate is to be dismantled, it is common to cut the knuckle plate into blocks at intervals in the circumferential direction, and remove the blocks in order from the upper end of the side plate (see FIG. 2 of Patent Document 2). and the reverse procedure of FIG. 3).

JP-A-61-242266 JP 2014-193726 A

By the way, the knuckle plate functions as a member for reinforcing the connecting portion between the roof plate and the side plate where a large amount of stress tends to act. It is formed thicker than the plate thickness (for example, 10 mm to 15 mm).

In this regard, it can be said that the knuckle plate has a higher weight per unit area than the side plate and the roof plate.

That is, in the above cylindrical tank dismantling method, when the block-shaped knuckle plates are sequentially removed from the side plates, the heavy knuckle plates are inevitably removed from the side plates at an intermediate stage (especially the final stage). There is a period of time during which it remains cantilevered on the upper end of the .

During this period, the connecting portion between the remaining knuckle plate (hereinafter referred to as the “remaining knuckle plate”) and the side plate is subjected to a radially inward load (structurally unstable). Depending on the thickness (weight), shape, etc. of the plate, there is a problem that the side plate may fall down with this portion acting as a point of action. This is especially the case when an earthquake or strong wind (for example, a typhoon) occurs during such a period.

In this respect, it can be said that the conventional dismantling method for cylindrical tanks has much room for improvement in terms of safety.

The present invention was made to solve such a problem, and its purpose is to suppress the instability of the tank structure during dismantling of the knuckle plate, so that the dismantling work can be performed more safely. To provide a dismantling method for an efficient tank.

According to the tank dismantling method of the present invention, the above-mentioned problem is a tank dismantling method, wherein the tank includes a roof plate, a cylindrical side plate that supports the roof plate from below, and a side plate. A ring-shaped knuckle plate having a thick plate thickness and connecting the roof plate and the side plate is provided, and the method for dismantling the tank comprises: a roof plate dismantling step of dismantling the roof plate; a knuckle plate dismantling step of dismantling the knuckle plate after performing the step, wherein the knuckle plate dismantling step includes cutting the knuckle plate along the circumferential direction to form a narrow ring shape. It is solved by including a cutting step.

The term "tank" as used herein means not only tanks that store fluid (for example, "LNG") but also tanks that do not store such fluid, and is limited to so-called double-shell tanks. It does not matter if it is a single-hull tank, for example.

In the above configuration, for example,
(a) cutting the knuckle plate in the circumferential direction to narrow the radial width of the knuckle plate;
(b) After that, the remaining narrow knuckle plate is cut into blocks, which are sequentially removed from the upper end of the side plate.
The dismantling work of the knuckle plate can be performed in such a procedure.

That is, in the above configuration, until the width of the knuckle plate is narrowed (until the work in (a) above is completed), the knuckle plate remains ring-shaped, in other words, as a reinforcing member. Since it is attached to the upper end of the side plate while still fully performing its function as a tank, the structure of the tank will not become unstable during dismantling.

On the other hand, in the above configuration, when the remaining knuckle plate is removed from the upper end of the side plate in a block shape, a period in which the knuckle plate is supported in a cantilever manner on the upper end of the side plate inevitably occurs. Since the plate has already been lightened (narrowed) at this time, it is possible to effectively prevent the structure of the tank from becoming unstable during this period as well.

In summary, with the above configuration, it is possible to sufficiently prevent the tank from becoming structurally unstable during dismantling at any stage during dismantling of the knuckle plate. Dismantling work can be performed more safely.

The tank dismantling method according to the present invention includes a radial cutting step of cutting a plurality of pieces along the radial direction between the inner peripheral edge of the knuckle plate and the cutting position where cutting is performed in the circumferential cutting step. preferred.

Further, in the tank dismantling method according to the present invention, a plurality of second radial cuts are made along the radial direction between the cutting position cut in the circumferential cutting step and the outer peripheral edge of the knuckle plate. Preferably, it includes a cutting step.

As described above, according to the tank dismantling method of the present invention, the dismantling work of the knuckle plate can be performed more safely with a relatively simple structure.

1 is a schematic diagram for explaining the outline of a cryogenic tank according to this embodiment; FIG. 2 is a perspective view of the cryogenic tank of FIG. 1; FIG. FIG. 4 is an explanatory diagram for explaining the dismantling order of the knuckle plate; FIG. 4 is a flowchart for explaining the work flow of the tank dismantling method according to the present embodiment; FIG. 5 is a plan view for explaining the contents of work in the first radial direction cutting step of FIG. 4; FIG. 5 is a plan view for explaining the contents of work in the first circumferential cutting step of FIG. 4; FIG. 5 is a plan view for explaining the contents of work in the remaining knuckle plate division removal step of FIG. 4;

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram for explaining the outline of the cryogenic tank according to this embodiment, FIG. 2 is a perspective view of the cryogenic tank of FIG. 1, FIG. is a flow chart for explaining the work flow of the tank dismantling method according to the present embodiment, FIG. FIG. 7 is a plan view for explaining the details of the work in the first circumferential cutting step of FIG. 4, and FIG. 7 is a plan view for explaining the details of the work in the remaining knuckle plate dividing and removing step of FIG.

FIG. 1 shows a cryogenic tank 1 to which the tank dismantling method according to the present embodiment is applied. The tank dismantling method and the low-temperature tank 1 correspond to the "tank dismantling method" and the "tank" described in the claims, respectively.

(Configuration of low temperature tank 1)
Here, the low-temperature tank 1 according to the present embodiment will be described before describing the dismantling method of the tank.
As shown in FIG. 1, the low-temperature tank 1 is an above-ground so-called double-shell tank, and is arranged so as to surround an inner tank 10 that stores "LNG" as a low-temperature liquid and the inner tank 10. An outer tank 20 is provided.

(Inner tank 10)
The inner tank 10 is made of a plate-shaped metal member (for example, nickel steel or stainless steel), and includes a circular inner tank bottom plate 11, a cylindrical inner tank side plate 12, and a dome-shaped inner tank roof plate 13. have. The inner tank side plate 12 and the inner tank roof plate 13 correspond to the "side plate" and the "roof plate" described in the claims.

Although details will be described later, the inner tank bottom plate 11 is placed and fixed on the bottom ring 24 and forms a bottom cooling space SB with the outer tank bottom plate 21 of the outer tank 20 .
In addition, the inner tank side plate 12 is provided so as to stand up from the outer peripheral portion of the inner tank bottom plate 11, while the inner tank roof plate 13 is connected to the upper end portion of the inner tank side plate 12 via a ring-shaped knuckle plate 14. ing. The knuckle plate 14 corresponds to the "knuckle plate" described in the claims.

(Knuckle plate 14)
Here, the knuckle plate 14 will be described with reference to FIGS. 1 and 2. FIG.
As shown in FIGS. 1 and 2, the knuckle plate 14 has a plate thickness (for example, 30 mm to 50 mm) that is thicker than the plate thickness (for example, 10 mm to 15 mm) of the inner tank side plate 12 and the inner tank roof plate 13. It is made of a formed metal member (for example, nickel steel, stainless steel, and aluminum alloy), and has a shape that slopes upward inward in the radial direction.

That is, the knuckle plate 14 is heavier than the inner tank side plate 12 and the inner tank roof plate 13 in weight per unit area.

The reason why the knuckle plate 14 having a large thickness is provided at the connecting portion between the inner tank side plate 12 and the inner tank roof plate 13 is that these connecting portions are:
(a) When the "LNG" stored in the inner tank 10 evaporates and the internal pressure rises, the inner tank roof plate 13 lifts up, and a large load is likely to be applied.
(b) stress tends to concentrate due to the weight of the inner tank roof plate 13;
Therefore, it is necessary to sufficiently reinforce this part, and
(c) When an earthquake occurs, it is necessary to transmit the vibration load of the inner tank roof plate 13 and the like to the foundation B (concrete foundation) satisfactorily;
For other reasons.

(Outer tank 20)
The outer tank 20 is made of a plate-like metal member (for example, carbon steel), and, like the inner tank 10, has a circular outer tank bottom plate 21, a cylindrical outer tank side plate 22, and a dome-shaped outer tank roof. a plate 23;

The outer tank bottom plate 21 is placed and fixed on the foundation B, and forms the bottom cooling space SB with the inner tank bottom plate 11 as described above.

The bottom cold insulation space SB according to the present embodiment includes a ring-shaped bottom ring 24 made of perlite concrete (a mixture of "perlite" with cement, sand, etc.) and a filling arrangement (not shown) inside the bottom ring 24. A cold insulator (for example, a cylindrical block made of perlite concrete and powdered perlite (hereinafter referred to as “powder perlite”) filled in the inside thereof) is provided.

The outer tank side plate 22 is connected to the outer peripheral portion of the outer tank bottom plate 21 with a predetermined gap from the inner tank side plate 12, and forms a side cooling space SS with the inner tank side plate 12.

Similarly, the outer tank roof plate 23 is connected to the upper end of the outer tank side plate 22 at a predetermined distance from the inner tank roof plate 13, and the roof cold insulation space SU is formed between the inner tank roof plate 13 and the outer tank side plate 22. to form

In this embodiment, the side cold insulation space SS and the roof cold insulation space SU are filled with powdered perlite 31 as a cold insulation material, like a known low temperature tank. In the present embodiment, these spaces are filled with only the powdery perlite 31 as a cold insulating material. It is also possible to fill other portions with the powdered perlite 31 while providing them.

Next, a tank dismantling method according to the present embodiment will be described with reference to FIGS. 1 to 7. FIG.
In the following,
(a) After the removal work (extraction work) of the cold insulation material (powder perlite 31, etc.) in the roof cold insulation space SU, the side cold insulation space SS, and the bottom cold insulation space SB is completed,
(b) A state in which the outer tank roof plate 23 and the inner tank roof plate 13 are dismantled by, for example, the same method as in Patent Document 1 (the method of dividing into blocks and removing them), and the knuckle plate 14 is exposed. (See Figure 2),
will be described as a premise. The work of dismantling the inner tank roof plate 13 corresponds to the "roof plate dismantling process" described in the claims.

As shown in FIG. 4, the tank dismantling method according to the present embodiment includes the above-described dismantling step (roof plate dismantling step) of dismantling the outer tank roof plate 23 and the inner tank roof plate 13, as well as the first step S100. A radial cutting step, a first circumferential cutting step in step S200, a knuckle plate width narrowing confirmation step in step S300, a remaining knuckle plate division removal step in step S400, and a knuckle plate dismantling completion confirmation step in step S500. , and the side plate/bottom plate dismantling step of step S600. The first radial cutting step of step S100 to step S knuckle plate dismantling completion confirmation step, the first radial cutting step of step S100, and the first circumferential cutting step of step S200 are each referred to in claims. corresponds to the "knuckle plate dismantling process", the "radial cutting process", and the "circumferential cutting process" described in the scope of .
[0039]
(Step S100)
The work of dismantling the knuckle plate 14 begins with performing the first radial cutting step of step S100.
[0040]
As shown in FIGS. 4 and 5, in the first radial cutting step, the knuckle plate 14 is provided with a plurality of cuts L1 (“16 places” in this embodiment) at predetermined intervals in the circumferential direction. Work to form.

Specifically, in the first radial cutting step, the cut line L1 is formed radially outward from the inner peripheral edge of the knuckle plate 14 at an intermediate position (for example, 1/2 to 3/2) of the ring width (radial width). /4 position) is performed. Note that such a cut line L1 can be formed by using a cutting tool such as a burner.

In this embodiment, after performing the first radial cutting step (the work of forming the plurality of cuts L1) of step S100, the second circumferential cutting step of step S200, which is the next step, is performed. there is

(Step S200)
As shown in FIGS. 4 and 6, in the first circumferential cutting step of step S200, the cut ends of the adjacent cuts L1, L1 are cut in the circumferential direction, and the knuckle plate 14 is sequentially removed in a blocked state. work to be done. Such cutting may be performed using a cutting tool such as a burner in the same manner as when forming the cut line L1.

Here, the work performed in the first circumferential cutting step will be described with reference to FIGS. 3 and 6. FIG. 3 indicate the order of removal of the block-shaped knuckle plate 14. As shown in FIG. In the following, for convenience of explanation, for example, the block-shaped knuckle plate 14 to be removed "first" is referred to as "divided knuckle plate 14a1", and the block-shaped knuckle plate 14 to be removed "seventeenth" is referred to as "divided knuckle plate 14a1". The knuckle plates 14a17" are respectively referred to.

As shown in FIGS. 3 and 6, in this embodiment, in the first circumferential cutting step of step S200,
(a) First, the split knuckle plate 14a1 is removed by cutting in the circumferential direction between the cut ends of the cuts L1, L1 corresponding to the split knuckle plate 14a1 (see FIG. 6(a)),
(b) Next, remove the split knuckle plate 14a2 located point-symmetrically to the split knuckle plate 14a1 in the same manner as when the split knuckle plate 14a1 was removed (see FIG. 6(b)).
(c) then
・Divided knuckle plate 14a3 (see FIG. 6(c)) adjacent to divided knuckle plate 14a1 in the clockwise direction→
・Divided knuckle plate 14a4 (see FIG. 6(d)) adjacent to divided knuckle plate 14a2 in the clockwise direction→
Split knuckle plate 14a5... Split knuckle plate 14a16 (see FIG. 6(e)),
Perform the removal work in the order of . It should be noted that such work can be realized, for example, by lifting and supporting the inner peripheral edge side of the divided knuckle plate with a crawler crane or the like.

In the present embodiment, after performing the first circumferential cutting step (the work of cutting the adjacent cuts L1, L1 in the circumferential direction) in step S200, the width narrowing of the knuckle plate is confirmed in step S300, which is the next step. configured to carry out the process.

In this embodiment, the split knuckle plates are removed in order at point-symmetrical positions so that the load acting on the inner tank side plate 12 is distributed in a well-balanced manner. It may be removed sequentially in a clockwise (counterclockwise) direction, or may be removed randomly.

(Step S300)
As shown in FIGS. 2 to 4 and 6, in the knuckle plate width narrowing confirmation process of step S300, the knuckle plate 14 is narrowed into a ring shape by performing the first circumferential cutting process of step S200. work to confirm whether or not

Specifically, in the knuckle plate width narrowing confirmation process of step S300,
(a) When all of the divided knuckle plates 14a1 to 14a16 are not removed (for example, when the divided knuckle plates 14a15 and 14a16 remain (see FIG. 2, etc.)), the width of the knuckle plate 14 narrows in a ring shape. While judging that it is not
(b) If all of the divided knuckle plates 14a1 to 14a16 have been removed (see FIG. 6(e)), it is determined that the knuckle plate 14 has been narrowed into a ring shape.
do the work.

In this embodiment, the knuckle plate 14 is
(a) When it is determined that the width is not narrowed into a ring shape, the first circumferential cutting step of step S200 is continued,
(b) When it is determined that the width of the knuckle plate is narrowed in a ring shape, the remaining knuckle plate is divided and removed in step S400, which is the next step.

(Step S400)
As shown in FIGS. 2 to 4 and 7, in the step S400 of dividing and removing the remaining knuckle plate, the remaining knuckle plate 14 is removed from the upper end portion of the inner tank side plate 12 while being cut into blocks. (See the divided knuckle plates 14a17 to 14a32 in FIG. 7(f)).

2 and 7 as an example, this point will be explained in detail.
(a) First, in order to remove the split knuckle plate 14a17, a pair of cuts L2, L2 are formed up to the outer peripheral edge of the knuckle plate 14 in the same manner as when the cut L1 was formed (second radial cutting step, See FIG. 7(a)),
(b) Next, the section between the cut ends of the cuts L2, L2 (the outer peripheral end of the knuckle plate 14) is cut in the circumferential direction, and the divided knuckle plate 14a17 is removed in the same manner as when the divided knuckle plates 14a1 to 14a16 are removed. Remove (second circumferential cutting step, see FIG. 7(b)),
(c) Next, remove the split knuckle plate 14a18 located point-symmetrically to the split knuckle plate 14a17 in the same manner as when the split knuckle plate 14a17 was removed (see FIG. 7(c)).
(d) then
・Divided knuckle plate 14a19 (see FIG. 7(d)) adjacent to divided knuckle plate 14a17 in the clockwise direction→
・Divided knuckle plate 14a20 (see FIG. 7(e)) adjacent to divided knuckle plate 14a18 in the clockwise direction→
Split knuckle plate 14a21... Split knuckle plate 14a32 (see Fig. 7(f)),
It is configured to perform the work of removing in the order of The operation of forming the cut line L2 corresponds to the "second radial cutting step" described in the claims.

In this embodiment, after performing the step S400 of dividing and removing the remaining knuckle plate, the step S500, which is the next step, is performed to confirm completion of disassembly of the knuckle plate.

In the present embodiment, the divided knuckle plates are sequentially removed at point-symmetrical positions so that the load acting on the inner tank side plate 12 is distributed in a well-balanced manner. It may be removed in turn (counterclockwise), or it may be removed at random.

In addition, in the present embodiment, the split knuckle plate is configured to be removed by cutting in the circumferential direction. In this case, the cutting operation as described above can be omitted.

(Step S500)
As shown in FIGS. 2, 4 and 7, in the knuckle plate dismantling completion confirmation process of step S500, whether or not the knuckle plate 14 has been completely removed is determined by performing the remaining knuckle plate division removal process of step S400. Work to confirm.

Specifically, in the knuckle plate dismantling completion confirmation step of step S500,
(a) If any of the split knuckle plates 14a17 to 14a32 remains on the upper end of the inner tank side plate 12, it is determined that the knuckle plate 14 has not been completely removed;
(b) If none of the divided knuckle plates 14a17 to 14a32 remain on the upper end of the inner tank side plate 12, it is determined that the knuckle plate 14 has been completely removed.
do the work.

In this embodiment, the knuckle plate 14 is
(a) If it is determined that the remaining knuckle plate has not been completely removed, the remaining knuckle plate division removal step of step S400 is continued,
(b) When it is determined that the parts have been completely removed, the next step, step S600, of dismantling the side plates and bottom plates is performed.

(Step S600)
As shown in FIGS. 1 and 2, in the side plate/bottom plate dismantling process of step S600,
(a) disassembling the inner tank side plate 12 and the outer tank side plate 22;
(b) dismantling the outer tank bottom plate 21 (if the inner tank bottom plate 11 is not dismantled at the time of the cooling material removal work (extraction work), the inner tank bottom plate 11 is also dismantled);
Work according to the procedure.

In this embodiment, after the side plate/bottom plate dismantling step of step S600 is performed, the tank dismantling method according to this embodiment is completed.

As described above, in this embodiment, when dismantling the knuckle plate 14,
(a) First, a plurality of cuts L1 are formed up to a predetermined position of the ring width (first radial cutting step of step S100),
(b) Next, the cut ends of the adjacent cuts L1, L1 are cut in the circumferential direction, and the knuckle plate 14 is sequentially removed in a blocked state (first circumferential cutting step of step S200),
(c) After that, after the knuckle plate 14 is narrowed into a ring shape (knuckle plate width narrowing confirmation step in step S300), the remaining knuckle plate 14 is blocked while forming a pair of cuts L2, L2. state (remaining knuckle plate division removal step of step S400),
is configured as

That is, in the present embodiment, the knuckle plate 14 remains ring-shaped, in other words, it sufficiently functions as a reinforcing member while the operations (a) and (b) are being performed. Since it is attached to the upper end of the inner tank side plate 12 as it is, the structure of the tank does not become unstable at this stage (see FIG. 6).

On the other hand, in this embodiment, while the work (c) is being performed, there is a period in which the remaining knuckle plate 14 is cantilevered on the upper end of the inner tank side plate 12. Since the knuckle plate 14 has already been narrowed (lightened), it is possible to effectively prevent the structure of the tank from becoming unstable even during this period (see FIG. 7).

In summary, in this embodiment, it is possible to sufficiently prevent the structure of the cryogenic tank 1 from becoming unstable during the dismantling work of dismantling the knuckle plate 14, so that the work can be safely performed. can do.

In the present embodiment, the number of times the knuckle plate 14 is narrowed into a ring shape is "one time" (see FIG. 6(e)), but it may be "two times" or more.

Further, in this embodiment, the dismantling of a so-called double-hulled tank has been described as an example. , the invention can be applied to any cylindrical tank (eg, single-hull tank).

Furthermore, in this embodiment, the plate thickness of the inner tank roof plate 13 is formed thinner than that of the knuckle plate 14, but it can be formed to be equal to or thicker than this, if necessary.

Although the embodiments to which the invention made by the present inventor is applied have been described above, the present invention is not limited by the statements and drawings forming a part of the disclosure of the present invention according to the embodiments. That is, it should be added that other embodiments, examples, operation techniques, etc. made by those skilled in the art based on this embodiment are all included in the scope of the present invention.

1 low-temperature tank 10 inner tank 11 inner tank bottom plate 12 inner tank side plate 13 inner tank roof plate 14 knuckle plates 14a1 to 14a32 split knuckle plate 20 outer tank 21 outer tank bottom plate 22 outer tank side plate 23 outer tank roof plate 24 bottom ring 25 manhole 31 Powdered perlite B Foundation SB Bottom cold insulation space SS Side cold insulation space SU Roof cold insulation space L1, L2 Cut

Claims (3)

A tank dismantling method comprising:
The tank is
a roof plate;
a cylindrical side plate that supports the roof plate from below;
a ring-shaped knuckle plate formed thicker than the side plate and connecting the roof plate and the side plate;
with
The method for dismantling the tank is as follows:
a roof plate dismantling step of dismantling the roof plate;
a knuckle plate dismantling step of dismantling the knuckle plate after performing the roof plate dismantling step;
including
The knuckle plate dismantling step includes:
a circumferential cutting step of cutting the knuckle plate along the circumferential direction to form a narrow ring shape;
Before performing the circumferential cutting step, a radial cutting step of cutting a plurality of radially between the inner peripheral edge of the knuckle plate and the cutting position to be cut in the circumferential cutting step,
A tank dismantling method characterized by: A tank dismantling method comprising:
The tank is
a roof plate;
a cylindrical side plate that supports the roof plate from below;
a ring-shaped knuckle plate formed thicker than the side plate and connecting the roof plate and the side plate;
with
The method for dismantling the tank is as follows:
a roof plate dismantling step of dismantling the roof plate;
a knuckle plate dismantling step of dismantling the knuckle plate after performing the roof plate dismantling step;
including
The knuckle plate dismantling step includes:
a circumferential cutting step of cutting the knuckle plate along the circumferential direction to form a narrow ring shape;
A second radial cutting step of cutting a plurality of radially between the cutting position cut by the circumferential cutting step and the outer peripheral edge of the knuckle plate,
A tank dismantling method characterized by: A tank dismantling method comprising:
The tank is
a roof plate;
a cylindrical side plate that supports the roof plate from below;
a ring-shaped knuckle plate formed thicker than the side plate and connecting the roof plate and the side plate;
with
The method for dismantling the tank is as follows:
a roof plate dismantling step of dismantling the roof plate;
a knuckle plate dismantling step of dismantling the knuckle plate after performing the roof plate dismantling step;
including
The knuckle plate dismantling step includes:
a circumferential cutting step of cutting the knuckle plate along the circumferential direction to form a narrow ring shape;
a radial cutting step of cutting a plurality of radially between the inner peripheral edge of the knuckle plate and a cutting position to be cut in the circumferential cutting step, before performing the circumferential cutting step;
A second radial cutting step of cutting a plurality of radially between the cutting position cut by the circumferential cutting step and the outer peripheral edge of the knuckle plate,
A tank dismantling method characterized by:

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