FIELD: gas industry.
SUBSTANCE: invention relates to cryogenic installations and can be used in gas industry. Disclosed are two versions of a main gas deethanization unit, including a drying unit, an intermediate separator, a dephlegmator, a separator, low- and high-pressure demethanizers, deethanizer, first and second recuperative heat exchangers, refrigerator, compressor and reducing devices. In operation of first version of main gas is drained, then one part is compressed, cooled in refrigerator, first recuperative heat exchanger, reduced and supplied to demethanizer, and other part is cooled in second recuperative heat exchanger, reduced and separated in intermediate separator to obtain residue withdrawn after reduction, and gas, directed to the dephlegmator, from which, after reduction, reflux and dephlegmation gas are withdrawn, which is separated in the separator together with methane-containing gas into a residue and gas, which is heated in a heat and mass exchange unit of a dephlegmator, a first recuperative heat exchanger and, after mixing with a regeneration gas supplied from the drying unit, is removed. Remaining separation residues and reflux and offgas are fed into the low-pressure demethanizer, and methane-containing gas is removed from the top, and a stream of circulating reflux is fed from the middle part, which is heated in the second recuperative heat exchanger and returned, and from the bottom is a demethanised condensate, which is fed into a high-pressure demethanizer for separation into off-gas and a hydrocarbon fraction, supplied to deethanizer for separation into ethane and propane-butane fraction. Second version is characterized by supply of the reduced first flow of the dried main gas to the intermediate separator.
EFFECT: invention increases output of hydrocarbons C2+.
8 cl, 2 dwg
