COMPLEX METHOD FOR EXTRACTION OF GAS-CONDENSATE LIQUIDS AND LIQUEFACTION OF NATURAL GAS Russian patent published in 2018 - IPC F25J1/00 

FIELD: oil and gas industry.

SUBSTANCE: cooling and partially condensing an incoming stream containing light hydrocarbons in one or more heat exchangers. Partially condensed stream is introduced into cold gas/liquid separator producing a gaseous stream extracted from the top and the bottom streams, which are introduced into a fractionating system containing (a) fractionating column of light fractions and fractionating column of heavy fractions or (b) methane-stripping column. The gaseous stream extracted from the top is expanded and introduced into (a) the lower zone of the fractionating column of light fractions or (b) the upper zone of the methane-stripping column. A stream of bottom liquid (b) is introduced in the (a) fractionating column of heavy fractions at its intermediate point or (b) to the methane-stripping column at its intermediate point. The stream of liquid products is removed from the bottom portion of the fractionating column of heavy fractions or (b) the bottom portion of the methane-stripping column. The top gaseous stream(a) from of the fractionating column of light fraction s or methane-stripping column (b) is removed. The stream of the bottom liquid is removed from the bottom zone of the fractionating column of light fractions and introduced into the upper zone of the fractionating column of heavy fractions. If the system contains a fractionating column of light fractions and a fractionating column of heavy fractions, by indirect heat exchange with the first portion of the gaseous stream taken from above the fractionating column of light fractions is cooled and partially condensed from the top of gaseous stream of the fractionating column of heavy fractions and introduced into the fractionating column of light fractions. A second portion of the gas stream extracted from above the gas stream from the fractionating column of light fractions is removed, cooled and partially condensed by indirect heat exchange. Partially liquefied side-cut distillate is introduced into an additional separation device, the liquid product is recovered and introduced into the fractionating column of light fractions and/or to the fractionating column of heavy fractions as liquid reflux stream. The upper steam flow is extracted from the additional separation device, cooled and condensed by indirect heat exchange and the produced steam and condensate are supplied to LNG separator where the final LNG product is produced. The upper steam flow is extracted from the additional separation device, compressed to form the residual gas. A method and a device wherein a methane stripping column is used instead of column of heavy fractions is also provided.

EFFECT: reduced energy consumption by installing of liquefied natural gas.

18 cl, 27 dwg