# US 9,347,611 B2 · Semi-submersible offshore structure having storage tanks for liquefied gas

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- Number: US 9,347,611 B2
- Document ID: US9347611B2
- Status: Granted
- Kind: B2
- Application number: 13/932,858
- Filed: 2013-07-01
- Published: 2013-11-07
- Granted: 2016-05-24
- Earliest claimed: 2008-05-30
- Assignees: Daewoo Shipbuilding & Marine Engineering Co., Ltd.
- Applicants: Daewoo Shipbuilding & Marine Engineering Co., Ltd.
- Inventors: Min Cheol Ryu; Jun Hyung Jung; Deok Su Kim; Yoon Sik Hwang; Yong Soo Kim; Chuel Hyun Kim
- Web page: https://patentgrep.com/patent/US9347611B2

## CPC

- F17C 3/027: {Wallpanels for so-called membrane tanks}
- F17C 3/005: {Underground or underwater containers or vessels (storing in natural or artificial cavities in the earth in general B65G5/00)}
- F17C 3/025: {Bulk storage in barges or on ships (constructive aspects B63B25/16)}
- B63B 2035/448: {Floating hydrocarbon production vessels, e.g. Floating Production Storage and Offloading vessels [FPSO]}
- F17C 2201/0104: cylindrical
- F17C 2201/0119: with flat end-piece
- F17C 2201/0128: spherical or elliptical
- F17C 2201/0157: Polygonal
- F17C 2201/0166: divided in several chambers
- F17C 2201/032: with substantially vertical main axis
- F17C 2201/035: with substantially horizontal main axis
- F17C 2201/052: large (>1000 m3)
- F17C 2203/03: Thermal insulations
- F17C 2203/0617: with one layer
- F17C 2205/0119: Vessel walls form part of another structure
- F17C 2205/013: Two or more vessels
- F17C 2205/0142: bundled in parallel
- F17C 2205/0184: Attachments to the ground, e.g. mooring or anchoring
- F17C 2221/033: Methane, e.g. natural gas, CNG, LNG, GNL, GNC, PLNG
- F17C 2223/0161: cryogenic, e.g. LNG, GNL, PLNG
- F17C 2223/033: Small pressure, e.g. for liquefied gas
- F17C 2260/016: Preventing slosh
- F17C 2270/011: Barges
- F17C 2270/0113: floating
- F17C 2270/0115: immerged
- F17C 2270/0118: Offshore
- F17C 2270/0121: Platforms
- F17C 2270/0123: Terminals
- F17C 2270/0128: Storage in depth
- F17C: VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES (storing fluids in natural or artificial cavities or chambers in the earth B65G5/00; construction or assembling of bulk storage containers employing civil-engineering techniques E04H7/00; variable-capacity gas-holders F17B; liquefaction or refrigeration machines, plants, or systems F25)
- B63B: SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING (arrangements of vessel ventilation, heating, cooling, or air-conditioning B63J2/00; floating substructures as supports of dredgers or soil-shifting machines E02F9/06)

## Abstract

Disclosed herein is a semi-submersible offshore structure having storage tanks for liquefied gas, which is constructed so as to improve workability in marine offloading of the liquefied gas stored in the storage tanks while reducing an influence of sloshing. The offshore structure is anchored at sea and has liquefied gas. The offshore structure includes a storage tank storing liquefied gas, a plurality of columns partially submerged under the sea level and each having the storage tank therein, and an upper deck located on the plurality of columns to connect the columns to each other.

## Claims

### Claim 1

A semi-submersible offshore structure configured to be anchored at sea and for storing liquefied gas, comprising:
a plurality of liquefied gas storage tanks configured to store liquefied natural gas, wherein each of said liquefied gas storage tanks is a membrane type storage tank and has a shape selected from a cylindrical shape and a rectangular parallelepiped shape;
a plurality of columns configured to be partially submerged below sea level and standing perpendicular to sea level, wherein each of said plurality of columns is provided therein with at least one of said liquefied gas storage tanks;
pontoons configured to adjust ballast and each pontoon connecting lower sides of the columns to each other;
an upper deck located on the plurality of columns and configured to connect the columns to each other; and
a column bridge provided to the columns to bridge a liquefied natural gas (LNG) carrier to the semi-submersible offshore structure, wherein said column bridge is provided in parallel to the pontoons to connect upper portions of the columns to each other under the upper deck, wherein said column bridge connects columns which are connected by each of the pontoons, and wherein each pontoon is configured to reduce fluctuation of the semi-submersible offshore structure and to adjust ballast.

### Claim 2 (depends on 1)

The semi-submersible offshore structure according to claim 1, wherein each of the pontoons connects two or more columns to each other.

### Claim 3 (depends on 1)

The semi-submersible offshore structure according to claim 1, wherein the column bridge connects adjacent columns to each other, and comprises a mooring rope securing the LNG carrier and an offloading arm transferring liquefied gas between the LNG carrier and the semi-submersible offshore structure.

### Claim 4 (depends on 1)

The semi-submersible offshore structure according to claim 1, wherein the column bridge is positioned at an installation height corresponding to a deck height of the LNG carrier.

### Claim 5 (depends on 1)

The semi-submersible offshore structure according to claim 1, further comprising:
a fender disposed on an outer surface of the column to prevent direct contact between the semi-submersible offshore structure and the LNG carrier for buffering operation therebetween.

### Claim 6 (depends on 1)

The semi-submersible offshore structure according to claim 1, wherein each storage tank is divided into two or more chambers by a partition.

### Claim 7 (depends on 1)

The semi-submersible offshore structure according to claim 1, wherein each of the columns has a shape selected from a cylindrical shape and a square pillar shape.

### Claim 8 (depends on 1)

The semi-submersible offshore structure according to claim 1, wherein the plurality of columns comprise four columns disposed in an oblong arrangement, and the pontoons comprise a pair of pontoons on each of which two adjacent columns are positioned.

### Claim 9 (depends on 1)

The semi-submersible offshore structure according to claim 1, wherein the semi-submersible offshore structure is one selected from LNG FPSO and LNG FSRU.