FIELD: separation.
SUBSTANCE: invention can be used in gas-processing and gas-chemical industries. Method for low-temperature separation of hydrocarbon gas includes obtaining fuel gas and fractions C3 and higher of high degree of purity. Stream of hydrocarbon feed gas is pre-cooled with partial condensation and separated to obtain separated gas and a liquid hydrocarbon phase which is fed to an absorption column. Separated hydrocarbon gas is expanded in expander and separated in absorption column to produce methane-ethane fraction and gas condensate. Methane-ethane fraction is divided into two streams while feeding the first stream for cooling the reflux stream of the absorption column and feeding the second stream for partial cooling of the crude hydrocarbon gas. First and second flows are combined, compressed and cooled in an air and/or water cooler with output as a commercial product. Gas condensate is supplied by a pump to the upper part of the deethanization rectification column so that deethanization gas and fraction C3 and higher are obtained. Deethanization gas is separated into two flows with supply of the first flow for full condensation in recuperative heat exchanger with methane-ethane fraction with further supply of condensate to upper part of absorption column as reflux and with supply of the second flow of deethanization gas to lower part of absorption column. Fraction C3 and higher is supplied from still part of deethanization column for further processing. Heat is supplied to the still of the absorption column and the still of the rectification column for deethanization by supplying a heat carrier to the boilers of the columns.
EFFECT: guaranteeing the required clear separation on impurities of fraction C3 and higher in the fuel gas and ethane impurities in the fraction C3 and higher, which is determined by the requirements of consumers.
8 cl, 1 dwg
