LNG Proccess Overview

Welcome to the PT. Arun NGL system, Arun LNG plant is located at Lhokseumawe the northern coast of Sumatra 275 km from Banda Aceh capital of Nanggroe Aceh Darussalam Province - Indonesia.
PT. Arun LNG plant processes natural gas from ExxonMobil Gas Fields The ExxonMobil fields consists of 2 major fields On-shore and Off-shore fields. The Onshore fields is called Arun field located at Lhoksukon about 30 Km away from LNG Plant. This field was discovered in late 1971 by Mobil Oil Ind. Inc. The Offshore fields named NSO (North Sumatra Offshore) Plat-form discovered in late 1990's located approximately 100 KM from LNG Plant.
PT. Arun NGL operates Arun LNG plant, which includes the Condensate and LNG facilities. The LNG facilities include separation, treating, fractionation and storage and loading. Instead of uses some processes to produce stabilized condensate and Liquefied Natural Gas (LNG), there are also two facilities that used to produce LPG's but no longer in operation.
Natural gas and un-stabilized condensate feed to Arun LNG plant deliver via separate pipelines. The 42 inches natural gas pipeline that carries feed gas from the Arun field and 24 inches treated gas from NSO onshore facilities goes to Inlet separation drum referred as "First Stage Flash Drums" to separate any hydrocarbon liquid from feed gas.
Hydrocarbon liquid in the bottom of separators is sent to condensate recovery unit for further treatment, while the overhead vapor flows to gas Treating Units. The 10 inches pipeline that carries un-stabilized feed condensate from Arun field and the 3 inches pipeline carriers small amount of condensate feed from NSO onshore facilities combined with hydrocarbon liquid from bottom of First Stage Flash drum goes to Condensate Recovery/Stabilization Unit referred as "Second Stage Flash Drums" for RVP (Raid Vapor Pressure) stabilization by heating and cooling. The overhead gas from the second stage separator then sent to low-pressure fuel gas system while the stabilized condensate product is cooled and sent to product storage.
The overhead vapor from First Stage Flash Drums will flow to LNG processing Units that referred as "Train" consists of Gas treating Unit ( Unit-30 ) where the impurities such as mercury (Hg), carbon dioxide (CO2) and hydrogen sulfide (H2S) are removed from the feed gas and then the sweet gas outlet Unit-30 goes to Liquefaction Unit ( Unit-40 ) where it is dehydrated to remove water content, cooled by using propane refrigerant and fractionated in scrub tower to remove heavy hydrocarbon from the feed gas. The lighter ends such as methane, ethane, propane and some butane are sent through the Ethane Extraction Unit ex LPG plant to recover ethane and propane plus to be prepared for MCR refrigerant components.
Residue gas outlet this unit (mostly ethane and lighter component) is boosted by the Residue Gas booster compressor and flow to the Main Cryogenic Exchanger in Unit-40 for liquefaction. The Scrub Tower bottom containing some mostly ethane, propane, butane and heavier hydrocarbon components become the feed to Fractionation/Refrigerant Preparation Unit.
Once the gas is liquefied in Main Cryogenic Exchanger ( spiral wound exchanger type ) using mixed refrigerant system that referred as "Mixed Component Refrigerant (MCR)", then pumped to storage tank and subsequent marine loading. MCR system receives a make up stream from Refrigerant Preparation Unit and Ethane Extraction Unit; the mixed-component refrigerant is pre-cooled by propane refrigerant system before circulated in the Main Heat Exchanger to liquefy the feed gas.
http://www.arunlng.co.id/Operations/LNG.aspx