FIELD: oil and gas industry.
SUBSTANCE: invention relates to low-temperature dephlegmation units with rectification and can be used in gas industry for natural gas preparation. Proposed plant comprises inlet separator, cooling assembly with recuperative heat exchanger and compressor connected with expanders via kinematic or electrical connection, recuperative heat exchanger, reducing devices including at least one expander, dephlegmator, demethanizer and fractionation unit. Raw gas is separated in inlet separator into condensate and gas, which is cooled in recuperative heat exchangers, separated in first intermediate separator into condensate and gas, which is reduced and separated in the second intermediate separator into condensate and gas, directed to the dephlegmator, from which the condensate and dephlegmation gas are removed. Reduced condensates are supplied to demethanizer, and demethanizer is removed: from top is prepared gas, which is mixed with reduced dephlegmation gas, is heated in a dephlegmator heat exchange section and a first recuperative heat exchanger, from the middle part is a stream of circulating reflux, which is heated in the second recuperative heat exchanger and returned to the demethanizer, from the bottom—demetanized condensate, which is fed into a fractionation unit for separation into products and off gas, which is returned to the demethanizer. Invention also relates to a version of the plant, which is characterized by supply of reduced dephlegmation gas to the demethanizer.
EFFECT: technical result is higher output of C3+ hydrocarbons.
2 cl, 2 dwg
