Technical Challenges & Design Features LNG Tank

기고｜ 기고 ｜Technical Challenges & Design Features of the Largest LNG Tank in Korea

Technical Challenges & Design Features of the Largest LNG Tank in Korea Eui-Seung Par｜Managing Director, Plant Division

Biography of Speaker Eui-Seung Park is a Managing Director and a Technical Fellow of Program Committee B(PGC B) of International Gas Union(IGU). Union(IGU). He has been working for Daewoo E&C for around 30 years and has been involved in many natural gas and LNG projects. He attended Seoul National University and received his BS in electrical engineering and also completed Advanced Managerial Program(AMP). He is in charge of plant projects including LNG in Plant Division.

E-mail : [email protected] Hong-Sung Kim

Seung-Rim Lee

General Manger, Plant Division

Senior Researcher, Institute of Gas Safety R&D

Seung-Beom Hong

Korea Gas Safety Corporation, 332-1,

Manager, Plant Division

Deaeya-Dong,, Sihung-Si, Gyunggi-Do, 429Deaeya-Dong

Se-Jin Jeon

712, Korea

Senior Researcher, Institute of Construction Technology

Daewoo E&C Co., Ltd., C.P.O. Box 8269, Seoul, Korea Joseph. H. Cho

AIChE Spring National Meeting, April 2006

Technical Advisor, Ph.D., PE

6th Topical Conference on Natural Gas

Kellogg Brown and Root, 601 Jefferson

Utilization

Avenue, Houston, TX 77002

Orlando, Florida , April 23-27, 2006

market. The importance of LNG storage facilities in

1. Introduction

Korea has recently been highlighted by the country's considerable increase in consumption

Since the first LNG cargo was imported to

and the security of a stable supply against

Korea at the end of 1986, the downstream LNG

seasonal peak loads in winter, which have

industry of Korea has seen remarkable

resulted from sizeable investments to address

development in each sector from receiving

the issue in a timely manner.

terminals to the nationwide trunkline network.

This paper will discuss past major activities

As a result, LNG is positioned to become a

in the various fields of the LNG tank industry

major primary energy source in the domestic

(such as engineering, construction, technology

Journal of The Korea Gas Union

37

기고｜Technical Challenges & Design Features of the Largest LNG Tank in Korea

development, safety study, etc.) starting from

nation-wide natural gas trunk line network

the construction of the first receiving terminal

(about 2,500 km in length), which was

at Pyeongtaek in 1986 to the design of the

constructed and operated by Korea Gas

world's largest above-ground LNG tank which

Corporation (KOGAS). Particularly, the annual

is scheduled to begin construction in early

gas demand growth rate is 9.7% from 1997 to

2006. The design of full containment LNG tank

2004, which was more than 4 times greater

of this 200,000m3 has been developed with an

than of global growth rate of 2.3% in natural

emphasis on the cost saving and land use

gas consumption. Besides, its supply rate of

efficiency under the Korean geopolitical

city gas to the household was 68.8%. However,

specifics. This paper also discusses the

the demand for LNG from the power sector

technical challenges and design features of the

shows a comparatively stable demand pattern

largest full containment.

around 35%. The demand from the city gas sector, which shows a big seasonal fluctuation, takes a considerably large portion of total

2. Increase in LNG Tank Capacity

demand (see Table 1). Korea has executed a long-term supply and

Currently, Korea is the world's 2nd largest

demand program increasing the storage rate

LNG importer after Japan. The Korean LNG

from 9.6% in 2005 to 12.7% in 2015 in order to

industry has been developing correspondingly

make preparations against the annually

with an increase in LNG consumption by

constant increase of demand and seasonal peak

approximately 16% per annum since the first

loads. The Korean government expects that

importation at the end of 1986 to the Pyeongtaek

large storage volumes contribute the stability

terminal from Indonesia.

of supply and demand. This can also meet the

In terms of its development, 22.2 Million Tones per Annum (MTPA) of LNG were

governmental energy-reserving policy in natural gas. .

imported and supplied in 2004 through the

Table-1 shows the increase in LNG demand

Table 1 - Prospect for LNG demand and expansion plan for storage capacity

LNG Demand (103 Ton) Storage Capacity (106m3)

Storage Rate

1997

2000

2003

2005*

2007*

2011*

2014*

2017*

Annual Growth Rate (%, 03~)

City Gas

5,770

9,528

11,979

13,658

15,386

18,852

21,700

24,893

5.36

Power

5,377

4,689

6,468

7,612

8,572

6,992

6,014

6,764

0.32

Total

11,147

14,217

18,447

21,270

23,958

25,844

27,714

31,637

3.93

Newly

-

7.0

14.4

10.2

7.0

20.8

8.4

5.6

Accumulated

1.3

2.0

3.4

4.5

5.2

7.2

8.1

8.6

(%)

5.2

6.3

8.4

9.6

10.2

13.2

13.7

12.7

Note) * is planning data from 'The 7th Long-term Supply and Demand Program, by MOCIE (Ministry of Commerce, Industry and Energy), December, 2004'

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KGU

by around 4% makes the expansion of storage

was preferred from an economic point of view

and supply facilities inevitable, which requires

and dominated the market with over 100 units

sizeable investment and the enlargement of

in the world. However, the geopolitical specifics

LNG tanks considering the economy of scale.

of the armistice as a divided country after the Korean War made Korea select the full containment type of LNG tank even though it

3. Development of LNG Tank

required high capital investment focused on the safety of the tank. By 2000, 10 units of above-

1st Generation : Above-ground membrane LNG tank with dike

ground LNG tanks (#1~10) had been installed at Inchon terminal.

The first LNG tank introduced in Korea was the membrane type at the Pyeongtaek terminal In 1983, the membrane technology developed by

3rd Generation : In-ground membrane LNG tank

Technigaz, France, was adopted for the first

Then came the so-called 3rd Generation LNG

three units (100,000m3 x 3) and the same

tank, in-ground membrane type. These started

technology was applied to the terminal

to be installed for the first time in Korea at the

expansion, resulting in construction of total 10

same terminal from 1997. From 1997 to 2004, a

units of storage tanks. This tank can be called

total of 8 units of in-ground tanks (#11~18)

the 1st Generation LNG tank' for convenience.

were constructed through 4 individual projects using the Japanese membrane technology. Two

2nd Generation : Above-ground 9% Ni full containment LNG tank with dike

tanks (#19~20) that have adopted the KOGAS membrane technology are under construction.

After construction of Pyeongtaek terminal,

These have resulted from a wide range of

the 2nd LNG terminal was built from 1990 to

research and development of membrane and its

1996 at Inchon terminal in order to meet abrupt

components such as insulation material.

increase in LNG demand and supply natural gas

Besides, their individual storage capacity of

to Seoul Metropolitan area. This comprised 9%-

200,000m3 deserves attention as the largest

Ni full containment LNG tanks (100,000m3 x 3)

volume in the world for 8 tanks (#13~20) out of

so-called the 2nd Generation LNG tank. This

10 units.

type of tank was state-of-the-art at the time been built in a few countries in the world.

4th Generation : Above-ground 9% Ni full containment LNG tank with no-dike

Traditionally, the single containment type of

From 1999 to Oct. 2002, the 3rd LNG terminal

double wall LNG tank with 9% Ni inner tank

in Korea was built at Tongyeong and the so-

of construction since only about 15 units1) had

1) In the basis of countries operating import terminals (Source : A study on the containment type of LNG tank, KOGAS, Aug. 1998)


39


Fig. 1 - Development of LNG Tanks in Korea

called 4th Generation LNG tank has been

can be said that this results from devotional

installed, no-dike 9%-Ni full containment LNG

efforts by the Korean government led by

tank (140,000m3 x 3, #1~3) with the largest

KOGAS and some companies involving in LNG

diameter of the LNG tank (86m in O.D.) in the

tank design and construction.

world. This terminal has made a significant contribution to the supply of natural gas in the southern area of Korea. After 2 more tanks

4. Security of Safety for LNG Tank

(#4~5) were installed, a total of 7 tanks (#6~12) with the same capacity have been constructed

Even though the Korean LNG industry has

based on the KOGAS design since Jan. 2002

only about running for 20 years, there are

(#6~10 tanks in operation). In the first half of

considerable efforts to establish a Korean

year 2006, the super-size above-ground LNG

regulatory system for enhancing LNG tank

tank with a 200,000m 3 capacity will be

safety. This was led by Korea Gas Safety

constructed in this terminal, which will be the

Corporation (KGS) and supported by KOGAS

first time in the world.

and government agency. The High Pressure

During two decades of LNG history, Korea

Gas Safety Control Law was enacted in 1996

has been developing with a remarkable increase

and then KGS began to implement verification

of LNG consumption and made a very dynamic

of safety for LNG tanks. In 1998, KGS

market for the LNG tanks. The market

completed 'A Study on Inspection Standards of

contributes development of the large storage

LNG Storage Tanks' and this has presented

tanks, adopted state-of-the-art technology. It

installation standards for LNG tanks at Inchon

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KGU

and Pyeongtaek terminals.

industry were successfully achieved during a

KGS also performed 'A study on Inspection

short period and eliminated unnecessary debate

Technology and International Standards for

over safety issues. As a result, KGS has

LNG Storage Tanks' in 2002, which results in a

contributed greatly to the national plan for

standard for the no-dike LNG tanks (7 tanks in

LNG storage facilities and the development of

operation) at Tongyeong for the first time in

its related industries.

Korea. This detailed study on the functions of dike for LNG tank was the basis of this guideline, which regards the outer wall of a full containment tank as the dike (or impounding

5. Design of the Largest Aboveground LNG Tanks

wall). The guideline does not require the dike since full containment outer wall is considered

The Korean LNG tank industry has developed

having the same function and safety of the

technologically and its market was enlarged along

dike. After this guideline has been enacted, no-

with 9%-Ni LNG tank's installation at Inchon

dike were installed for the full containment

terminal. At the same time, the market

type of LNG tanks. As a result, the client has

competition has been serious as well, which led to

benefited from enhanced land use efficiency.

a reduction in the construction cost per unit

In 2004, KGS implemented the 'Comparative

volume of tank capacity. For example, the LNG

Risk Assessment of LNG Tank Design' with the

tanks at the Tongyeong terminal were constructed

help of the English consulting firm, AEA

at the cost of 70% of the tanks at Inchon 2).

Technology, and the Korea Institute of Gas (KIGAS). They compared and evaluated the safety of the ordinary full containment LNG tank and the KOGAS membrane tank through structural analysis and quantitative risk assessment. The latter KOGAS membrane tank was found to have the same level of safety as the full containment LNG tank installed at Tongyeong. KGS is developing Korean Industrial Standard(KS) codes similar to the international codes and standards such as BS, API and EN code with governmental agency. The efforts of KGS towards the establishment of proper safety standards in time for Korean LNG tank

Fig. 2 - Relative Specific Tank Construction Costs

* Notes) - Specific tank con struction costs were obtained from total construction costs divided by net storage volumes (m3).) - 100,000 m3 tank has dike, while others are no-dike type. - 200,000m3 capacity LNG tank costs is based on Kogas' planned Tongyeong project

2) Estimated by the contract amount and storage capacity taking account of inflation


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Keeping pace with the increase of national

Tongyeong terminals, as a strategy to be a

demand for LNG, the government policy of

market leader at the end of year 2000. The

enlargement of LNG tanks has been aimed at

world's largest tank was 180,000m3 above-

reducing the national budget. It has also been led

ground LNG tank at the Senboku and Himeji

to competitiveness in the market and development

terminals, Japan, in 2000. DWC targeted the

of the technology in the engineering and

following objectives in the development of a

construction areas.

200,000m3 tank.

In terms of above-ground LNG tanks, the

●

Cost reduction per unit volume

result of cost efficiency for the enlargement of

●

Enlargement of land use efficiency

tank capacity was obtained through the

●

Technology development of structural

analysis of many projects in Korea. The data

analysis and materials

was collected from the various projects at

●

Reduction of construction period

Inchon and Tongyeong terminal and analyzed

In February 2005, DWC succeeded to develop

with adjustment for the identical timeframe

the design and structural analysis technology

taking into account for annual inflation by 3%.

for inner and outer tanks on the basis of

Daewoo Engineering and Construction Co.,

various codes and standards, first hand

Ltd. ('DWC') has participated in the LNG tank

experience from previous LNG projects and the

industry since 1995. DWC has independently

design and analysis technology acquired from

started the development of 200,000m3 above-

nuclear containment. The various LNG tanks

ground LNG tank based on design and

have been installed around the world including

construction experiences at Inchon and

Korea principally in accordance with BS7777

Fig. 3 - Sectional View of 200,000m 3 LNG Tank

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KGU

and API 620 codes. However, each code has its

6. Conclusion

own strict and different provisions for the thickness of plate for the inner tank and the

As the second largest LNG importer in the

hydrostatic test level, which in fact limited the

world, the Korean LNG industry has grown

maximum capacity up to 160,000m3 for the

remarkably in a relatively short period of 20

LNG tanks. But now the newly established

years. Along with this, LNG storage facilities

European code prEN14620 replacing BS7777 can

have also been steadily expanding according to

allow the inner tank design with over 50mm

the increase in demand to secure the supply of

thickness and partial hydro-test level up to

LNG against peak loads and introduction of

125% of the maximum liquid loads. Based on

energy-reserving policy for LNG as an

this new regulation, DWC implemented a study

important primary energy source such as

on various sizes of LNG tanks with the

petroleum. Additionally, thanks to the constant

optimum height to diameter(H/D) ratio and

efforts from the government authorities such

finally selected the most economical H/D ratio

as KOGAS and KGS and LNG-related

securing the safety in the seismic loads of

companies, it has been possible to build the

OBE(0.1g) and SSE(0.2g) without anchor strap.

various and state-of-the-art LNG tanks based

Then, DWC designed and verified the tank with

on the governmental policy of the expansion of

structural analysis having the following

LNG supply.

specifications. ●

●

●

●

These efforts gave birth to the Korean

Capacity : 200,000m3 / 90m (ID) X 35.3m

membrane and 9% Ni LNG tanks overcoming

(inner tank height)

many difficulties. Through these efforts, DWC

Internal pressure : 290mmbar / thickness

could secure engineering and analysis

of 1st plate : 31.2mm

technology for the largest 200,000m3 full

Radius of curvature for dome roof : 0.8d

containment LNG tank of 9% Ni type based on

(Safety check with allowable stress &

its own advanced technology as a leading

buckling)

contractor in the Korean market and lay the

Ring beam: designed to reduce thrust

foundation to leap to into the global market

transmitted from the dome roof & internal

where the trend of expansion of LNG

tendon

liquefaction and receiving terminal is very apparent worldwide due to the increase of LNG demand and oil prices.


43


References 1. Se-Jin Jeon, "Design Basis for Large Above-Ground Tank", GASEX2002, May 2002 2. MOCIE (Ministry of Commerce, Industry and Energy), "The 7th Long-term Supply and Demand Program", December, 2004 3. KOGAS (Korea Gas Corporation), "A study on the containment type of LNG tank", August 1998 4. "API 620: Design and construction of large, welded, low-pressure storage tanks", 1996, American Petroleum Institute. 5. "BS 7777: Flat-bottomed, vertical, cylindrical storage tanks for low temperature service", 1993, British Standards Institution. 6. "prEN14620: Design and manufacture of site built, vertical, cylindrical, flat-bottomed steel tanks for the storage of refrigerated, liquefied gases with operating temperatures between 0oC and -165 oC", 2006, European Committee for Standardization. 7. KOGAS R&D Division, "Design Information on the Largest LNG Storage Tank", May 2005

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Technical Challenges & Design Features LNG Tank

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