KR20100107218A - Balasting system and floating marine structure having the system - Google Patents

Abstract

PURPOSE: A ballasting system and a floating marine structure therewith are provided to secure safety even if there is an oil leak by forming a void space outside an oil tank. CONSTITUTION: A ballasting system comprises a ballast tank, a ballast pump(4), a ballast pipe(5), and a void space(6). The ballast tank is installed around a storage tank(30) with a double wall structure. The ballast pump supplies ballast water to the ballast tank. The ballast pipe connects the ballast pump and the ballast tank. The void space is installed around a storage tank with a single wall structure. The ballast pipe penetrates through the void space.

Description

Ballasting system and floating offshore structure with the ballasting system {BALASTING SYSTEM AND FLOATING MARINE STRUCTURE HAVING THE SYSTEM}

The present invention relates to a ballasting system provided in a floating offshore structure that can be used suspended in the sea, wherein both the liquefied gas tank for storing liquefied gas, such as LNG or LPG and the oil tank for storing oil The present invention relates to a ballasting system provided in a floating offshore structure installed therein.

Natural gas is transported in gaseous form through onshore or offshore gas piping, or liquefied in the form of liquefied natural gas (LNG) or liquefied petroleum gas (LPG), followed by LNG carriers or LPG. It is transported to a remote consumer while stored in a transport. Liquefied natural gas is obtained by cooling natural gas to cryogenic temperature (approximately -163 ℃), and its volume is reduced to about 1/600 than natural gas in gas state, so it is very suitable for long distance transportation through sea.

LNG transporter for loading and unloading LNG to land requirements by operating the sea with LNG, or LNG RV (Regasification) that reloads LNG after unloading the sea with LNG for recharging the stored LNG The vessel includes a storage tank (commonly referred to as a cargo hold) that can withstand the cryogenic temperatures of liquefied natural gas.

Recently, there is a growing demand for floating offshore structures such as LNG Floating, Production, Storage and Offloading (FPSO) or LNG Floating Storage and Regasification Units (FSRUs). Includes a storage tank installed.

LNG FPSOs are floating offshore structures that are used to liquefy the produced natural gas directly from the sea and store it in storage tanks and, if necessary, to transport LNG stored in the storage tanks to LNG carriers. In addition, LNG FSRU is a floating offshore structure that stores LNG unloaded from LNG carriers in a storage tank at sea far from the land, and then vaporizes LNG as needed to supply land demand.

As described above, a storage tank for storing LNG in a cryogenic state is installed in an offshore structure such as an LNG carrier, an LNG RV, an LNG FPSO, or an LNG FSRU that transports or stores a liquid cargo such as LNG.

These storage tanks can be classified into Independent Type and Membrane Type, depending on whether the load directly affects the insulation. Membrane type storage tanks are generally divided into GT NO 96 type and TGZ Mark III type, and standalone storage tanks are divided into MOSS type and IHI-SPB type.

The GT and TGZ tank structures described above are described in U.S. Patent Nos. 6,035,795, 6,378,722, 5,586,513 and U.S. Patent Publication Nos. 2003-0000949 and the like, and Korean Patent Publication Nos. 10-2000-0011347 and 10-2000. -0011346 and the like. In addition, the structure of the stand-alone storage tank is described in Korean Patent Nos. 10-15063 and 10-305513.

Figure 1 shows an example of a conventional membrane type LNG storage tank used for storing LNG. As shown in FIG. 1, the conventional membrane type LNG storage tank 10 storing LNG includes a secondary heat insulation wall 13 and a secondary sealing wall 14 on the inner wall surface 2 of the hull 1. ), The primary heat insulating wall 15 and the primary sealing wall 16 are sequentially stacked. A ballast tank 3 is provided inside the hull 1 to stably maintain the draft of the floating offshore structure.

2 shows an example of a conventional LPG storage tank used for storing LPG and having a structure similar to the stand-alone LNG storage tank described above. As shown in FIG. 2, the conventional LPG storage tank 20 storing LPG has a structure supported by the supporting structure 24 at the bottom in a state spaced apart from the inner wall surface 2 of the hull 1. Have Similarly, a ballast tank 3 is provided inside the hull 1 to stably maintain the draft of the floating offshore structure.

Thus, the LNG storage tank 10 and LPG storage tank 20 for storing liquefied gas, such as LNG and LPG, have a barrier or empty space between the ballast tanks 3. That is, in the case of the LNG storage tank 10 and the LPG storage tank 20, the first barrier in contact with the liquefied gas (that is, the primary sealing wall 16 and the LPG storage tank 20 of the LNG storage tank 10) ) And a second barrier located outside of this first barrier (i.e., the secondary sealing wall 14 of the LNG storage tank 10 and the hull inner wall surface 2 outside the LPG storage tank 20). Has As a result, the LNG storage tank 10 and the LPG storage tank 20 have a double barrier structure by these first and second barriers.

Therefore, even if leakage of LNG or LPG occurs in the LNG storage tank 10 or the LPG storage tank 20, since LNG or LPG, which is a flammable material, does not have to be introduced into the ballast tank 3, the LNG storage tank ( 10) or the ballast tank 3 and the ballast pump (not shown) located around the LPG storage tank 20 is divided into a safety zone.

3 shows an example of a conventional oil storage tank 30 used for storing oil. As shown in FIG. 3, the conventional oil storage tank 30 for storing oil is constituted by the inner wall surface 2 of the hull 1 itself. That is, the oil storage tank 30 has a single barrier structure.

Therefore, when oil leaks from the oil storage tank 30, since oil, which is a flammable substance, flows into the ballast tank 3 as it is, a ballast pump (not shown) through a ballast pipe (not shown) in the ballast tank. Oil may be introduced). In this case, since the ballast pump may cause an explosion or fire, the ballast pump should be installed inside the pump chamber after preparing a separate pump room in a floating offshore structure such as an oil tanker handling oil or an oil FPSO. The pump room should be compartmentalized from other safety zones as a hazard zone.

As such, ballast tanks around storage tanks storing LNG or LPG and ballast tanks around oil storage tanks must be handled differently, but for this purpose it is costly and time consuming to install two different ballasting systems independently. And it takes a matter of effort. Therefore, when installing the LNG or LPG storage tank and oil storage tank together in one floating offshore structure, there is a need for a ballasting system that can secure the safety while reducing costs.

The present invention for solving these conventional problems, in the case where both the liquefied gas tank for storing the liquefied gas, such as LNG or LPG and the oil tank for storing the oil is installed in the floating offshore structure, It is intended to provide a ballasting system that can ensure safety even if a leak occurs from an oil tank by forming a void space outside.

According to an aspect of the present invention for achieving the above object, a ballasting system for supplying and discharging ballast water to the ballast tank, the ballast tank is installed around the storage tank having a double barrier structure; A ballast pump for supplying and discharging ballast water to the ballast tank; A ballast pipe connecting between the ballast pump and the ballast tank; A void space installed around a storage tank having a single barrier structure; Provided is a ballasting system comprising a.

The ballast pipe is passed through the inside of the void space, it is preferable that the void space and the ballast pipe to maintain a state independent from each other.

It is preferable that a reinforcing member for supporting the storage tank is provided inside the void space.

It is preferable that at least one measuring device is installed in the void space to detect leakage of ignitable gas or liquid from the storage tank.

The size of the void space is preferably determined so that an operator can enter the interior of the void space and perform maintenance work.

It is preferable that another ballast tank connected to the ballast pipe is installed outside the void space.

According to another aspect of the present invention, a ballasting system for supplying and discharging ballast water, comprising: at least one first tank installed around a liquefied gas storage tank and capable of receiving ballast water; At least one second tank installed around the oil storage tank and not receiving ballast water; It includes, The first tank and the second tank is provided with a ballasting system, characterized in that independent from each other.

It is preferable that another first tank is installed outside the second tank to accommodate the ballast water.

According to still another aspect of the present invention, there is provided a floating offshore structure having a liquefied gas storage tank capable of storing liquefied gas and an oil storage tank capable of storing oil therein, including a ballasting system as described above. A floating offshore structure is provided, which is characterized by the above-mentioned.

The floating offshore structure may be an LNG FPSO having a plurality of storage tanks for storing different kinds of cargo.

According to the present invention as described above, in the case where both a liquefied gas tank for storing liquefied gas such as LNG or LPG and an oil tank for storing oil are installed in the floating offshore structure, the outside of the oil tank is voided. By creating a space, a ballasting system can be provided in which safety can be ensured even if a leak occurs from the oil tank.

Thus, according to the ballasting system of the present invention, even if the ignition fluid leaks from the oil tank, there is no fear of fire or explosion in the ballast pump.

In addition, forming a void space outside the oil tank is cheaper than using a stand-alone tank as an oil tank and can secure sufficient structural rigidity.

Hereinafter, a ballasting system according to a preferred embodiment of the present invention will be described in detail with reference to the drawings.

4 is a conceptual diagram of a ballasting system of a typical liquefied gas carrier. 5 is a conceptual diagram of a floating offshore structure to which a ballasting system according to a first embodiment of the present invention is applied, and FIG. 6 is a view of a floating offshore structure to which a ballasting system according to a first embodiment of the present invention is applied. A cross section is shown. 7 is a conceptual diagram of a floating offshore structure to which a ballasting system according to a second preferred embodiment of the present invention is applied, and FIG. 8 is a floating type to which a ballasting system according to a second preferred embodiment of the present invention is applied. A cross sectional view of the offshore structure is shown.

As shown in FIG. 4, in the case of a carrier for transporting liquefied gas such as LNG and LPG, a plurality of ballast tanks 3 are provided in the hull, and the plurality of ballast tanks 3 includes one or more ballast pumps. Is connected to (4). The ballast pump 4 supplies and discharges ballast water to each ballast tank 3. In FIG. 4, a liquefied gas storage tank 10 for storing liquefied gas is positioned at the center of the hull and a ballast tank 3 is positioned at the left and right sides of the hull, but the ballast tank is a liquefied gas storage tank 10. Of course it can also be located below the bottom of the hull.

However, in a floating offshore structure, such as LNG FPSO (Floating, Production, Storage and Offloading), which floats around a gas well and performs LNG production and storage process at sea, LNG is stored in a storage tank provided in the hull. In addition, LPG or oil (ie condensate oil) needs to be stored as cargo.

As described in the background art, a liquefied gas storage tank for storing liquefied gas such as LNG or LPG has a barrier or empty space between the ballast tanks in the hull. Therefore, even if leakage of LNG or LPG occurs in the liquefied gas tank, there is no risk that LNG or LPG, which is a ignitable substance, will flow into the ballast tank. Are distinguished.

In addition, since the oil storage tank storing oil is composed of the inner wall surface of the hull itself, when oil leaks from the oil storage tank, the oil, which is a flammable material, flows into the ballast tank as it is, and thus the ballast in the ballast tank. The oil can enter the ballast pump through the pipe. In this case, because the ballast pump is a risk of explosion or fire, the pump room in which the ballast pump is located is to be separated from other safety zones as a danger zone.

In the present specification, like the LNG storage tank 10 and the LPG storage tank 20, the first barrier in contact with the liquefied gas (that is, the primary sealing wall 16 and the LPG storage tank of the LNG storage tank 10 ( 20) itself, and a second barrier located outside of this first barrier (i.e., secondary sealing wall 14 of LNG storage tank 10 and hull inner wall surface 2 outside of LPG storage tank 20). ), There is no risk that liquefied gas, which is flammable, is directly leaked into the ballast tank, is referred to as a "double barrier structure" (see FIGS. 1 and 2).

In addition, in the present specification, like the oil storage tank 30, it is composed of only one barrier, a structure in which the liquefied gas, which is a flammable material, may directly leak inside the ballast tank (or a space adjacent to the outside of the oil storage tank). Is referred to as the "single barrier structure" (see FIG. 3).

Referring to FIG. 5, the LNG storage tank 10 for storing LNG and LPG storage for storing LPG are stored in the hull 1 of a floating offshore structure such as LNG FPSO, which needs to store various cargoes. Tank 20, and the oil storage tank 30 for storing the oil may be installed together. As such, when installing the LNG or LPG storage tanks 10 and 20 and the oil storage tank 30 together in one floating offshore structure, a different ballasting system is required.

In the present specification, the floating offshore structure includes both a vessel and various structures that are used floating in the sea while having a storage tank for storing liquefied gas such as LNG or LPG and an oil storage tank for storing oil. In addition to the above mentioned LNG FPSO (Floating, Production, Storage and Offloading), OIL FPSO, LNG Floating Storage and Regasification Unit (FSRU), LNG Carrier, Oil Tanker or LNG Regasification Vessel (RV RV) It includes all the structures.

According to the present invention, the first ballast tank 3a, which is a ballast tank around the LNG storage tank 10 having a double barrier structure, and the second ballast, which is a ballast tank around the LPG storage tank 20 having a double barrier structure, similarly. The tank 3b can be set as a safety zone, so that one or more ballast pumps 4 are used to supply and discharge the ballast water of each tank.

On the other hand, since the area around the oil storage tank 30 having a single barrier structure should be set as a dangerous area, when installing a ballast tank around the oil storage tank 30, the number of ballasts contained in the ballast tank is changed to another ballast tank, That is, a separate ballasting system should be configured so as not to mix with the ballast water of the first and second ballast tanks 3a and 3b.

However, according to the present invention, the first and second ballast tanks, which are set as safety zones, are formed by forming a void space around the oil storage tank 30 which should be set as a dangerous zone because of having a single barrier structure. Do not mix ignitable materials with ballast water in 3a, 3b). Accordingly, even if only one ballasting system is installed in the floating offshore structure in which the liquefied gas storage tanks 10 and 20, such as LNG and LPG, and the oil storage tank 30 are disposed together, the flammable material is mixed in the ballast water. Can be prevented.

As shown in Figs. 5 and 6, the ballasting system according to the first preferred embodiment of the present invention comprises first and second ballast tanks 3a and 3b around a liquefied gas storage tank set as a safety zone. And a ballast pump 4 for supplying and discharging ballast water to the first and second ballast tanks 3a and 3b, and between the ballast pump 4 and the first and second ballast tanks 3a and 3b. It includes a ballast pipe (5) for connecting.

According to the first embodiment, an empty space, that is, a void space 6, is formed around the oil storage tank 30 set as the danger zone. In other words, the void space 6 is formed between the outside of the hull 1 of the floating offshore structure and the oil storage tank 30.

As shown in FIG. 6, the ballast pipe 5 and the various equipments (eg, utility lines, etc.) may be configured to pass through the void space 6, but the void space 6 and the ballast pipe 5 may be configured to pass through. Are not connected to each other and remain independent from each other.

In the void space 6, a reinforcing member 6a may be installed to support the oil storage tank 30 in the hull 1. That is, the oil storage tank 30 is structurally connected to the hull 1 via the reinforcing member 6a.

At least one measuring device such as a sensor may be installed in the void space 6 so as to detect the leakage of the ignitable gas or the liquid from the oil storage tank 30. In addition, the size of the void space 6 is preferably determined at the time of design so that an operator can enter the interior of the void space 6 to perform maintenance work such as inspection and repair.

5 shows that two LNG storage tanks 10, one LPG storage tank 20 and one oil storage tank 30 are installed in a floating offshore structure, but this is only an example, and the present invention It may be applied in any case of a floating offshore structure having at least one liquefied gas storage tank and at least one oil storage tank.

In addition, although storage tanks for storing liquefied gas and oil are shown in FIG. 5, the ballast tanks are located at the center of the hull, and ballast tanks are positioned at the left and right sides of the hull, but the ballast tank is located at the bottom of the storage tank, that is, the lower part of the hull. Of course it can.

Hereinafter, a ballasting system according to a second preferred embodiment of the present invention will be described with reference to FIGS. 7 and 8. As shown in FIG. 7 and FIG. 8, the ballasting system according to the second preferred embodiment of the present invention, as in the first embodiment described above, has the first and second ballast tanks 3a set as safety zones. 3b), ballast pump 4 and ballast pipe 5; In addition, an empty space, that is, a void space 6 is formed around the oil storage tank 30 which is set as the danger zone.

In the second embodiment, however, a third ballast tank 3c is provided outside the void space 6, that is, between the hull 1 outside of the floating marine structure and the void space 6.

Thus, in the ballasting system which concerns on 2nd Embodiment, the 3rd ballast tank 3c is provided in the outer side of the void space 6, and this 3rd ballast tank 3c has the ballast pipe 5 as mentioned above. The first embodiment differs from the first embodiment in that the ballast pump 4 is connected to the ballast pump 4 through. The same matters as that of the first embodiment will not be described in detail any further.

As described above, the present invention has been described with reference to the illustrated drawings, but the present invention is not limited to the above-described embodiments and drawings, and has a general knowledge in the technical field to which the present invention belongs within the claims. Of course, various modifications and variations can be made by them.

1 is a view showing an example of a conventional membrane type LNG storage tank,

2 is a view showing an example of a conventional LPG storage tank having a structure similar to a standalone LNG storage tank,

3 is a view showing an example of a conventional oil storage tank,

4 is a conceptual diagram of a ballasting system of a general LNG carrier;

5 is a conceptual diagram of a floating offshore structure to which a ballasting system according to a first embodiment of the present invention is applied;

6 is a cross-sectional view of a floating offshore structure to which a ballasting system according to a first embodiment of the present invention is applied;

7 is a conceptual diagram of a floating offshore structure to which a ballasting system according to a second embodiment of the present invention is applied;

8 is a cross-sectional view of a floating offshore structure to which a ballasting system according to a second embodiment of the present invention is applied.

Description of the Related Art

1: hull 3a: first ballast tank

3b: second ballast tank 3c: third ballast tank

4: ballast pump 5: ballast pipe

6: void space 10: LNG storage tank

20: LPG storage tank 30: oil storage tank

Claims (10)

A ballasting system for supplying and discharging ballast water to a ballast tank, A ballast tank installed around a storage tank having a double barrier structure; A ballast pump for supplying and discharging ballast water to the ballast tank; A ballast pipe connecting between the ballast pump and the ballast tank; A void space installed around a storage tank having a single barrier structure; Ballasting system comprising a. The method according to claim 1, The ballast pipe is passed through the interior of the void space, the ballast space and the ballast pipe, characterized in that the ballast pipe maintains an independent state from each other. The method according to claim 1, Ballasting system, characterized in that the reinforcing member for supporting the storage tank is installed inside the void space. The method according to claim 1, Ballasting system, characterized in that the inside of the void space is installed at least one measuring device for detecting the leakage of the ignitable gas or liquid from the storage tank. The method according to claim 1, The size of the void space, the ballasting system, characterized in that the operator can enter the interior of the void space to perform maintenance work. The method according to claim 1, Ballasting system, characterized in that another ballast tank is connected to the ballast pipe on the outside of the void space. Ballasting system for supplying and discharging ballast water, At least one first tank installed around the liquefied gas storage tank and capable of receiving ballast water; At least one second tank installed around the oil storage tank and not receiving ballast water; Including; And said first tank and said second tank are independent of each other. The method of claim 7, Ballasting system, characterized in that another first tank is installed outside the second tank that can accommodate the ballast water. A floating offshore structure having a liquefied gas storage tank for storing liquefied gas and an oil storage tank for storing oil therein, A floating offshore structure comprising the ballasting system according to any one of claims 1 to 8. The method according to claim 9, The floating offshore structure is a floating offshore structure, characterized in that the LNG FPSO having a plurality of storage tanks for storing different kinds of cargo.

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