Water removal and heavy-hydrocarbon removal process in liquefied natural gas production from mixed gas rich in methane

Abstract

A process for dehydrating and removing heavy hydrocarbons in the production of liquefied natural gas from a methane-rich gas mixture is disclosed, wherein the methane-rich gas mixture subjected to deacidification treatment is divided into two streams, i.e. the first stream and the second stream, wherein the first stream used as a system process gas is introduced into a drying procedure, and the second stream used as regenerating gas is introduced into a regenerating procedure; the first stream is subjected to a drying treatment, and the moisture and the heavy hydrocarbons are simultaneously removed from the first stream in a composite adsorbent bed(s) of a drying tower, wherein the moisture is removed such that the dew point at normal pressure is ≦−76° C. and the heavy hydrocarbon components of C6 and higher are removed such that the content of these components is ≦217 ppm; and the second stream is used as a regenerating gas in the regenerating procedure of the above-mentioned drying tower, subjected to a regenerating process, and then returned as a part of the system process gas. Comparing to those conventional processes, the present invention can achieve good purifying effect, lower equipment investment and late-stage energy consumption of the system, increase utilization ratio of feed gas, and the operation target of each unit becomes more clear and easy to control. The present invention further relates to an apparatus for carrying out the process.