FIELD: gas industry.
SUBSTANCE: invention relates to cryogenic units and can be used in the gas industry. The invention relates to a unit for deethanisation of mains natural gas, including a mains gas line divided after the drying unit into two lines, a compressor, a refrigerator, expanders connected with the compressor, a recuperative heat exchanger, a reflux column with a heat and mass exchange unit and a reflux output line connected with a separator equipped with lines for methane-containing gas supply, residue and separation gas output with the heat and mass exchange unit and the recuperative heat exchanger by a reflux gas supply line equipped with a reducing apparatus, and a fractioning unit. The unit is equipped with reducing apparatuses at least one whereof is made in form of an expander, the first recuperative heat exchanger, a reducing apparatus and a low pressure demethaniser are installed on the first mains gas line after the refrigerator, a second recuperative heat exchanger, a reducing apparatus and an intermediate separator equipped with a residue output line equipped with a reducing apparatus, and with a gas output line whereon the reflux column is installed, are installed on the second mains gas line. The low pressure demethaniser is equipped with a demethanised condensate output line, connected to the lines for separation residue supply, reflux and intermediate separation residue supply and methane-containing gas output, and is also connected to the first recuperative heat exchanger by circulating reflux input/output lines. The fractioning unit includes at least a high pressure demethaniser connected with a low pressure demethaniser by demethanised condensate and off-gas output lines, and a deethaniser equipped with ethane and propane-butane fraction output lines. The invention also relates to a variant of a unit for deethanisation of mains natural gas.
EFFECT: technical result is an increased yield of C2+ hydrocarbons.
8 cl, 2 dwg
