Patent ID: 6986266
Filing Date: 2006-01-17
Classification: F25J

Abstract:
1. A process for enriching LNG in methane, comprising the steps: a) feeding an initial LNG stream to flow in a first path in a heat exchanger wherein the LNG stream partially vaporizes, b) feeding the partially vaporized initial LNG stream into a middle region of a distillation column that has a concentration section and a stripping section, c) operating the distillation column to separate the partially vaporized initial LNG stream into a methane enriched overhead gas stream and into an ethane enriched liquid product stream, d) warming the methane enriched gas stream while flowing in a second path in the heat exchanger, e) compressing the warmed methane enriched gas stream, and cooling the compressed methane enriched gas stream to a temperature at or near ambient, f) further cooling the compressed and cooled methane enriched gas stream to liquid state while flowing in a third path in the heat exchanger, g) and distributing the compressed and liquefied methane enriched gas stream into two streams, one of which is expanded and then introduced to the top of the distillation column as a reflux, and the other of which is expanded and provided as a methane product.