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Twenty eight years after the commissioning of the LNG production facilities by Abu Dhabi Gas Liquefaction Co. Ltd. (ADGAS) on Das Island, located some 160 kilometers northwest of Abu Dhabi city, ADGAS name has become synonymous with “Efficiency, Commitment and Success”. As much as the Company’s beginning was special and unique, its march throughout the years has been full of remarkable achievements. This successful march will undoubtedly be maintained with appropriate planning, continuing development of human resources and use of state-of-the-art technology, all of which have taken ADGAS into the 21st century.

GAS LIQUEFACTION
Natural gas is one of the precious gifts of nature. It is found both onshore and offshore as independent deposits, or mixed with crude oil (i.e. associated gas). This associated gas has to be separated before crude oil is exported and refined. Oil-producing countries have long been wasting this gas by burning it off in the atmosphere. Some of them started utilizing the gas as fuel for their industrial plants and other domestic purposes. The surplus that exceeded their local requirements was exported to neighboring countries, through special pipelines. But what about the countries that are separated from suppliers by cast distances?

The Sixties witnessed a dire and pressing need by both parties to find a solution that would help the producing countries utilize the gas, stop flaring it away and subsequently protect the environment and, at the same time, make it easily available for the importers. Transportation was the major problem. Gas in its gaseous form is too huge in volume and transporting it thus would undoubtedly mean exorbitant expenses.

The solution was found: the liquefaction of gas-by cooling it down to minus 160ºC, thus reducing its volume in the ratio of 600:1. It could then be easily transported-involving much reasonable expenses, to the importers who, in turn, will store it in its liquefied form under the same temperature. It could later be re-gasified, whenever required, to be used as fuel.

A UNIQUE PLANT
The initial plant consisted of two identical process trains arranged in parallel to permit safe overhaul of one train while the other remains in service. The process plant is integrated with a utilities complex which can be shut down in sections for maintenance overhaul while production continues subject to some limitations. The two original liquefaction trains were designed to produce the following total annual yields:
LNG: 2,300,000 tons
PROPANE: 650,,000 tons
BUTANE: 20,000 tons
PENTANE: 220,000 tons

The plant was not only the first of its kind in the Middle East, but it was the only plant in the world capable of processing both natural gas and petroleum gas.

THE THIRD LNG TRAIN
Upon the conclusion in 1990 of a new agreement with Tokyo Electric Power Company (TEPCO), to double ADGAS’ production from 1994, the third LNG train was built adjacent to the original two liquefaction trains and the storage and loading facilities.

The new train, designed to increase LNG production capacity by about 2.5 million tones/year, houses proprietary liquefaction equipment and facilities including three steam turbine-driven refrigeration-compressors (developing some 36 MW each), together with the largest cryogenic column ever constructed. Taking advantage of some over-design to the actual feed gas, being easier to process, the third train currently produces over 3 million tones per year.

In most LNG plants, the heat exchangers are also major items of equipment. For the new facility, ADGAS has utilized the platefintechnology and decided to install this, making major savings on space and size of major heat exchangers. The so-called “cold boxes” of the ADGAS Plant are amongst the largest ever constructed.

ADGAS construction of a new LNG Train was complemented upstream by the development of additional suppliers of nonassociated gas.

THE GAS LIQUEFACTION PROCESS
The LNG plant feed gas is made up of associated gas and natural gas. The associated gas is separated at the oil fields under different pressures. There oil fields include Umm Shaif, Zakum and Bunduq. The natural gas fields include Abu Al Bukoosh Khuff, Uweinat, Umm Shaif Khuff and cap gas fields.

The sweet dry gas passes through a heat exchanger where it is cooled against medium-level Propane down to minus 1ºC. Condensed liquid is separated while uncondensed feed gases are cooled against lowlevel Propane to minus 34ºC.

Again, the condensed hydrocarbons are separated and the gas passes through the first bundle in the main cryogenic exchanger, where the gas is cooled to around minus 45ºC and the remaining LPG that has condensed already is separated out. The condensed hydrocarbons from all the separators pass to the fractionation plant. The remaining uncondensed gas, which is predominantly Methane and Ethane, passes back into the main cryogenic exchanger for liquefaction.

In the de-ethanizer column, the Methane and Ethane in the feed boiloff overhead are sent to the main cryogenic exchanger for liquefaction.

LPG FRACTIONATION
In the de-ethanizer column, the Methane and Ethane in the feed boiloff overhead are sent to the main cryogenic exchanger for liquefaction.

The bottoms from the de-ethainzer pass to the de-propanizer where the Propane is distilled overhead and, after condensation and cooling, is pumped to storage.

The bottoms from the de-propanizer go to the de-butnizer where the Butane is distilled overhead, cooled, condensed and pumped to storage.

The bottoms from the de-ethanizer contain the Pentanes and heavier hydrocarbons.

The Plant’s performance, gas liquefaction, involves a number of utilities and services. The following are the most important of them:-
a) Six forced draft, gas-fired boilers, each having a rated capacity of 360 tonnes per hour of steam at a pressure of 60 bars and a temperature of 440 ºC.
b) Sea water cooling is provided by nine pumps each of a rated capacity of 16,500 cubic meters of water per hour.
c) Three fire-water pumps; each can provide 1200 cubic meters of water per hour into there fire-water system.
d) Compressed air is provided for four Nitrogen production units and then dried and supplied to all pneumatically-operated instrumentation.
e) All the industrial fresh water requirements of the LNG Plant are provided by three sea-water desalination units, each having a proven production capacity of 35 tonnes per hour. Water required for boiler water feed is further treated in six demineralization units. There is an extensive steam condensate recovery system and recovery of condensate exceeds 95%.
f) Electric power generation capacity of 105 megawatts is provided by two steam-turbine generators, each of 17.5 megawatts; and four gas-turbine generators; each of 17.5 megawatts. As well as supplying power to the LNG Plant, the Utilities section provides the power requirements of the whole Das Island.

STORAGE TANKS
The Plant originally had two storage tanks each for LNG, kept at minus 160ºC, Propane plus at minus 45ºC Butane at minus 6ºC and Pentane at ambient temperature.

But with the increase in production that exceeded the Plant’s original capacity, and in order to meet future requirements, they were decommissioned after the construction of seven new storage tanks built in conformity with the most advanced international specifications. This included three tanks each of 80,000 cubic meter capacity for the LNG and four LPG tanks, each of 50,000 cubic meter capacity. The construction of these tanks was completed in 1986. It is from these tanks that the LNG and other products are loaded onto tankers and exported.

LOADING FACILITIES
The liquid products are shipped from a jetty located approximately 700 metres offshore to provide sufficient depth of water for the largest LNG ships to berth and load at the times.

The LNG loading system has pumps which deliver through a 30 inch pipeline. For the LPG, there is a separate pumping and loading system for each product (Propane and Butane) through two pipeline. There is also a line for loading Pentane plus, and vapour-return lines for LNG and LPG.

PRODUCTION CAPACITY
Since the commissioning of the Plant in 1977, ADGAS has witnessed numerous developments and changes that helped it fulfilling its commitments and increasing its production remarkable levels.

Gas supplies were generally restricted until late 1979, when successful modifications were made to the offshore gas supply system. Since then, increased supply reliability has enabled the Plant to run at full capacity. But when the associated gas supplies fell down due to reduction in oil production, this shortfall was largely offset by increasing the cap gas offtake to maintain the production and export of LNG.

The construction of the third LNG train in 1994 was a major leap in the company’s operations and in the size of its production. This train alone has the capacity to produce around 3 million tonnes of liquefied natural gas a year, increasing the total annual production of the Plant to 5.8 million tonnes of LNG, or around 8 million tonnes after adding LPG, Pentane plus and Sulphur.

EXPORTS
ADGAS exports the products of its LNG Plant to the international gas market, always making sure that the clients’ specifications are met, that its sales policies are flexible enough to ensure a fair share of the market, and that its excellent relations with customers are maintained and consolidated.

LNG is exported under long-term contracts, most of which stipulate that the product is to be delivered to the client’s terminal and that shipping charges are to be agreed with the National Gas Shipping Company (NGSCO), and ADNOC Group Company that operates the modern LNG carrier fleet that transports ADGAS products.

The first long-term contract was signed in 1972 with Tokyo electric Power Company (TEPCO), under which TEPCO would receive approximately two million metric tons of liquefied natural gas (LNG) and 800,000 metric tons of liquefied petroleum gas (LPG) each year, over a 20-year period, from the proposed gas liquefaction plant on Das Island.

The second one was signed in 1990 with the same company, TEPCO, under which ADGAS was to double its production by 1994, and TEPCO was to purchase an additional volume of this doubled production for a 25-year period.

A third long-term agreement was signed in 1999 with the American Company “ENRON” under which would export 48 thousand tons of LNG annually to “Dabhol Power Company” of India from 2001 to 2021.

ADGAS also exports LPG, Pentane plus and Sulphur under contracts with some of the world’s major companies. The validity of these contracts ranges from one year to three years. Having increased the production of LNG and LPG to exceed thecontractual volumes agreed with TEPCO, ADGAS has been successfully selling its surplus production, since 1995, to some of the world’s major companies in Europe, Asia and the USA.

SAFETY COMES FIRST
The highly experienced LNG Plant Management was aware from the outset of problems commonly encountered when commissioning a new plant with an untried team. A lack of safety training, for instance, could easily spell disaster. A great effort was therefore made to weld the already experienced staff into cohesive and self-reliant crew, ensuring that the Plant would have the best possible chance of an incident-free start-up.

The skills of control and direction in emergency situations and of fire-fighting and search and rescue are assiduously practiced on large scale “hands on” type exercises which also involve the fire and medical services on Das Island. These exercises continue to be a vital and frequent of the LNG training.

CHRONOLOGY OF EVENTS

07/09/1971	The Gas Liquefaction Project Agreement Signed
14/12/1972	The 20-year Sale Agreement with TEPCO Signed
10/03/1973	The Company Registered in Bermuda with ADNOC Holding 20% of the Shares
04/12/1973	Sheikh Zayed Bin Sultan Al Nahyan, Founder of UAE, Lays the Plants Foundation Stone
25/12/1975	ADNOC’s Shareholding Increased to 51%
28/03/1977	The Company Incorporated in Abu Dhabi
29/04/1977	First LNG Shipment Loaded
04/10/1977	Sheikh Zayed Bin Sultan Al Nahyan, Founder of UAE, officially Inaugurates the Plant
1981	Construction of Seven LNG and LPG Storage Tanks Starts
1988	New Seawater Intake Project Completed
1990	Introduction of the Highly-Sophisticated Computer-Based Digital Control System (DCS) at DAS LNG Plant
15/10/1990	Heads of agreement signed with TEPCO for ADGAS expansion
16/11/1991	Agreement for Execution of the 3rd LNG Train Engineering and Construction works Signed
3/10/1993	New 25 Years Sales and Purchase Agreement Signed
June 1993	First Liquid Sulphur shipment Exported
16/7/94	First LNG from Train III
July 1994	3rd LNG Train Commissioned
August 1994	New LNG tanker “Khaznah” Enters Service. It is the First of Four New Tankers That Joins the Fleet
09/11/1994	3rd LNG Process Train Inaugurated Officially
Jan 1995	ADGAS First LNG Shipment to Third Parties
Jan.1996	The first of Four LNG Tankers to be built in Finland “Mubaraz”, Joins the Fleet
Feb. 1996	ADGAS Launches its New Integrated Systems project
5/10/1996	A New, Remarkable 3-Million Man/Hours Safety Record Established
June 1997	ADGAS Offices shift to New Headquarters
24/06/1997	ADNOC’s Shareholding Increased to 70%
25/02/1999	20 year SPA signed with Dabhol Power Company, India
25/02/2000	100 Million Tonnes of product export from Das Island
20/10/2001	The new administrative building on Das
2003	80 Million ton of LNG sales to TEPCO
December 2003	ADGAS 25th LNG Anniversary
2004	8 Million Man-Hour with LTI
2004	ISO 14001 Award
April 2005	Three Years of LTI Free Environment
November 2005	Finalized Das Master Plan
April 11, 2006	22 Million/Man/Hours of work without lost time Injury

SHAREHOLDERS
ADGAS is owned by four shareholders:
Abu Dhabi National Oil Company (ADNOC) : 70%
Mitsui & Co, Ltd (Japan) : 15%
BP (U.K) : 10%
TOTAL (France) : 5%

COMPANY ADDRESS
Abu Dhabi Gas Liquefaction Company Limited (ADGAS)
P.O.Box 3500, Abu Dhabi,
United Arab Emirates
Tel: +971-2-6061111
Fax: +971-2-6065500
Telex: 22698 ADGAS

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