MLNG Dua

Image Source : PETRONAS – MLNG Plant

Location : Bintulu, Sarawak

Malaysia’s history as a major LNG producer began with the discovery of substantial gas reserves in Sarawak’s Central Luconia basin, 125 km from Bintulu, in the 1960s. On 31st March 1978, PETRONAS signed a joint venture agreement with Shell BV, Mitsubishi Corporation and Sarawak government to initiate the country’s first liquified natural gas projects. The small town of Bintulu in the island of Borneo, Malaysia was selected as an ideal site due to its strategic location and proper geographical condition for developing Sarawak’s first deep sea port, specifically to cater to large LNG ships that will call the port in the future. The Petronas LNG complex is built on an area covering over 276 hectares.

MLNG Satu, Malaysia’s first liquefaction plant, with 3 LNG processing trains of combined capacity 8.1 MMTPA, started its operation on November 1982. The success of the project and growing LNG demand in the world spurred Malaysia to quickly develop expansion plans for their LNG assets. On 1st June 1992, Malaysia LNG Dua Sdn. Bhd. (MLNG Dua) was incorporated to operate the second LNG processing plant. The company was owned by PETRONAS (60%), Shell B.V. (15%), Mitsubishi Corporation (15%) and the state government (10%). The second plant also has three LNG processing ‘trains’ with a combined output of 9.6 MMTPA. MLNG Dua shares several utilities with MLNG Satu, including the 4 existing LNG storage tanks, with one more LNG storage tank of capacity 65,000 cubic meter added. The first shipment of cargo from MLNG Dua was dispatched on 19th May 1995.

The plant uses Air Products & Chemicals Inc.’s (APCI) Propane Pre-cooled Mixed Refrigerant (C3-MR) liquefaction concept and has maintained a 100% success delivery rate to its customers, establishing a reputation as a preferred and reliable LNG supplier in the world. At one point of time the PETRONAS LNG complex became the world’s largest LNG processing facility in a single location, until Qatar established itself as an international LNG giant. The plant exports Liquefied Natural Gas (LNG), Propane and Butane (LPG) and Gasolene. MLNG has long term contracts with several Japanese customers including Tokyo Electric Power Co. Inc. and Tokyo Gas Co. Ltd., who renewed their 20-year sale and purchase agreement on 17 March 2003. Other major clients include KOGAS of South Korea, CPC Corporation Taiwan (CPC) of Taiwan and Shanghai LNG Co Ltd (SHLNG) of China.

MLNG is actively involved with various education, capability-building and outreach programmes. The initiatives cover a wide range of human development needs to improve the lives and well-being of both present and future generations. Dedicated skills development and industrial training programs have been initiated for nurturing its workforce as well as providing valuable exposure to students from the community. The company claims that sustainability is an integral part of how they operate, as they conduct their business in an ethically, socially, and environmentally responsible manner. Biodiversity, Environmental and Conservation (Beacon) Project at Similajau National Park (SNP) is a collaborative venture with Sarawak Forestry for the preservation and conservation of marine biodiversity in Bintulu waters through programs such as Friends of Nature. MLNG deployed approximately 1,500 artificial reef balls at the Similajau National Park, at a cost of RM4.6 million, to improve the livelihood of the local community and biodiversity conservation.

OWNERSHIP (Equity %)

PETRONAS	80.00%
Diamond Gas (80% Mitsubishi Corporation, 20% JAPEX)	10.00%
Sarawak State Government	10.00%

General Data

Estimated Capital Cost (USD)	NA
Plant Type	Onshore Stick-built
Plant Stage	Operating
Final Investment Decision (FID) Year	1992
FEED Contractor	Shell Internationale Petroleum Maatschappij (SIPM)
EPC Contractor	JGC Corporation MW Kellogg Company Sime Engineering Sdn Bhd
No. of Trains / capacity	3 Trains / 3.2 MMTPA each
Production Start Year	1995
Products	Liquefied Natural Gas (LNG), Propane and Butane (LPG) and Gasolene
Gas Type	Non-associated Gas (NAG)

Technical Data

Cooling Media	Seawater + Air (Hybrid)
Liquefaction Technology	APCI AP-C3MR™
Refrigeration Train Details:
Propane String
Driver	GE PG6581B (Frame 6B) Heavy Duty Gas Turbine (Upgraded from GE PG6551B)
Gearbox	Double Helical Speed Reduction Gear box
Propane Compressor	3MCL1004 GE (Nuovo Pignone) Horizontally Split Centrifugal Compressor
Starter/Helper	NG40/32 GE (Nuovo Pignone) Steam Turbine (Upgraded from 8.5MW to 12MW)
Mixed Refrigerant (MR) String
Driver	GE MS7121EA (Frame 7EA) Heavy Duty Gas Turbine (Upgraded from GE MS7111EA)
Low Pressure (LP) MR Compressor	AN200 GE (Nuovo Pignone) Axial Compressor
Medium Pressure (MP) / High Pressure (HP) MR Compressor	2BCL806 GE (Nuovo Pignone) Radially Split Centrifugal Compressor
Starter/Helper	NG40/32 GE (Nuovo Pignone) Steam Turbine (8.5MW)
Power Generation	Power supply from MLNG SATU utilities. No additional power generation added.

Refrigeration Train Configuration

Key Facts

MLNG Dua was incorporated on 1 June 1992 as a joint venture between PETRONAS (60%), Mitsubishi Corporation (15%), Shell Gas (15%) and Sarawak State Government (10%). In 2003, post expiration of the joint venture agreement with Shell and Mitsubishi corporation, Petronas became a 90% shareholder. Mitsubishi reacquired a 10% stake through Diamond Gas an 80:20 partnership with JAPEX.^1,2
On 22^nd March 1995, MLNG signed a sale and purchase agreement with Chinese Petroleum Corporation (CPC) – the first long-term customer from Taiwan.²
MLNG Dua’s major customers include CPC from Taiwan; JERA, JXTG Nippon Oil & Energy, Sendai City Gas, Shizuoka Gas, Kansai Electric, Tohoku Electric, Osaka Gas, Toho Gas, Tokyo Gas from Japan; and KOGAS from South Korea.³
MLNG Dua uses one GE Frame 6 and one Frame 7 gas turbines. It is the first LNG plant in the world to use the GE Frame 7 gas turbine driver, which contributes to lower fuel consumption and smaller footprint compared to the steam-driven MLNG Satu.^4,5,6
MLNG Satu and MLNG Dua share several utilities, however they have two separate gas supply systems, as MLNG Satu is designed for sweet gas with negligible H₂S, while MLNG Dua processes sour gas, containing up to 300 parts per million by volume (ppmv) H₂S.⁷
A hybrid cooling system is deployed at MLNG Dua using both seawater and air. This was done to make optimum use of the surplus capacity of the large utility systems of MLNG Satu, through an integrated design employing significant amount of sea cooling water for the propane cooling cycle of MLNG Dua. No additional power generation facilities were required for MLNG Dua. ⁷
MLNG Satu and Dua both employ one propane compressor and two MR compressors with 3 compression stages. However, MLNG Dua has an axial LP MR compressors for increased MR flows.⁷
A 3-bundle design was used for the cryogenic exchanger at MLNG Satu. However, the design was replaced with a 2-bundle version at MLNG Dua. However, this made the plant susceptible to operational upsets and tube leakages and necessitated stringent adherence to operation guidelines. Eventually, the 3-bundle design was re-employed in MLNG Tiga.⁷
A GE Frame 7 gas turbine drives both MR compressors at MLNG Dua on a single shaft arrangement, with a helper steam turbine driver for start-up assistance. The helper turbine is also capable of delivering up to 10% of the total power required by the MR compressor during normal operation. A Frame 6 gas turbine drives the propane compressor through a gear-box with an identical helper steam turbine on the same shaft as the compressor. The set-up at MLNG Dua is comparatively simpler and more cost effective than MLNG Satu. However, this arrangement exhibits lower reliability, lower availability due to a higher maintenance requirement and longer re-start times after trips (typically 6 hours).⁷
Around the 1997, bush fire induced haze in Indonesia and Sarawak started affecting MLNG Dua’s gas turbine compressor drivers, with fouling on account of dust accumulating in the inlet filter systems. This necessitated daily washing of filters from the once-a-week routine. Intensive care and monitoring of the compressors performance assisted MLNG Dua in mitigating the impact on production.⁷
In 1998, the MLNG Rejuvenation & Revamp Project (MRR Project) was initiated to improve performance and reliability of MLNG Satu and Dua. MLNG Dua revamp commenced in 2001 with threefold objective:⁸
> To prevent capacity reduction on account of anticipated higher concentration of CO2 in the feed gas.
> To maintain historical production capacity of 105% of the nameplate capacity
> Upgradation of plant utilities to support revamped plant requirement.
As a part of the MLNG Rejuvenation & Revamp (MRR) Project, Trains 4-6 were revamped in 2001, 2002 and 2004 respectively, during the routine DOSH shutdowns (Malaysian Department Of Safety and Health).⁸
Higher concentration of CO₂ was anticipated in the feed gas supply to MLNG Satu & Dua, which could result in reduction of capacity. In a proactive and preventive move, the capacity of the acid gas removal and disposal facilities of the plant was increased through several means:⁸
> Replacement of Sulfinol Regenerator Reboilers
> Addition of new Sulfinol Booster Pumps
> Replacement of internals of Sulfinol Knock-Out Vessels
> Increased capacity of Sulfinol Overhead Condensers
> Revamp of existing Acid Gas Incinerators and constructing new Incinerators
> Trimming of Propane Compressors impellers
MLNG Dua is partly seawater cooled and shares the cooling system with MLNG Satu. However, MLNG Dua’s exchangers are fed from the top while Satu’s are fed from the bottom. Multiple tube failures were observed in the propane condensers and sub-coolers, due to erosion-corrosion damage. The primary cause was traced to air ingress in piping causing erosion of the soft Aluminium Brass material, particularity after transition areas where tube diameter changed. The second factor was low pump pressures which reduced seawater velocities and created fouling, causing under deposit corrosion of the tubing. Several measures were deployed to address this issue including: ⁹
> Throttling the main outlet valves of the condensers
> Improving chlorination of the sea cooling water to prevent biofouling
> Re-tubing with equal diameter tubes
> Installation of mesh screen at the tube sheet
> Passivation of aluminium brass tubes
> Installation of soft anode
In 2005, MLNG Dua underwent a major debottlenecking project to add 1.3 MMTPA to its original nameplate capacity of 7.8 MMTPA. The project worth USD 18 million was awarded to GE Oil & Gas to upgrade three propane compressors of Train 4,5 & 6, which were subsequently delivered in 2007, 2008 and 2009, respectively. The project involved:^10,11,12
> The addition of a new (extended) end flash unit
> Uprating main refrigerant compressors and drivers per module
> Debottlenecking existing systems and equipment to support increased production per module
> Additional common power generation to support increased production