Ethane Extraction for Petrochemical Feedstock

Abstract

Abstract Preliminary studies have shown that a petrochemical project for the manufacture of ethylene and selected ethylene derivatives using an ethane feedstock extracted from natural gas to be produced from the Arun field would be practical. The Arun field, which is near the town of Lho Seumawe in Aceh Province, North Sumatra, is being developed to produce gas to be liquefied for export, and the studies initiated by Pertamina have shown that the ethane required for a one billion pound per year ethylene plant could be extracted from the Arun gas without reducing the quantity or heating value of the LNG product below the levels permitted under existing sales contracts. Agreements for the sale of LNG and for the design and construction of the Arun LNG plant were signed prior to beginning the ethane studies. Therefore it was necessary that the ethane extraction facilities be designed to have a minimal effect on the LNG plant design and on the construction schedule. A simple cryogenic turboexpander process was selected for this purpose. The natural gas will be treated and dehydrated by the LNG plant before its delivery to the turboexpander cycle. Energy developed by the pressure drop across the turboexpander will be utilized to help recompress the gas. Additional compression horsepower will be required to boost the gas back to its original pressure. The major interface between the LNG plant and the ethane extraction facilities will be in the fractionation system which serves both plants. By this recommended method for efficient ethane extraction both technical and business criteria will be satisfied.