FIELD: oil and gas industry.
SUBSTANCE: invention relates to low-temperature separation plants and can be used in gas industry for extraction of hydrocarbons C2+ from natural gas. Proposed is a unit including, in version 1, a drying unit, an external cooling circuit comprising an evaporator, a compressor, a condenser and a reducing device, two recuperative heat exchangers, two expansion devices, a pump, a dephlegmator and a demethanizer. Alternative 2 instead of external cooling circuit includes compressor, refrigerator and third expander. In operation of version 1, high-pressure gas is dried and separated into two streams, first is cooled in first recuperative heat exchanger, and second one – in evaporator and in second recuperative heat exchanger, then flows are combined, reduced in the first expander and sent to a dephlegmator, cooled with low pressure gas, which is then heated in the first recuperative heat exchanger and discharged. During circulation, the external circuit coolant after heating in the evaporator is compressed with a compressor driven by expanders, cooled in a condenser and reduced. Dephlegmation gas is reduced in the second expander and mixed with the methane-containing gas to form a low-pressure gas. Reflux from dephlegmator via second recuperative heat exchanger is supplied by pump to demethanizer, from which hydrocarbons C2+ and methane-containing gas. Operation of version 2 is characterized by that the second high-pressure gas stream is compressed by a compressor driven by expanders, cooled in a cooler, a second recuperative heat exchanger and reduced by means of a third expander.
EFFECT: invention increases output of hydrocarbons C2+.
2 cl, 2 dwg
