The invention discloses a rectification-type self-overlaying gas liquefying
system, which comprises a compressor, a condenser, a rectifying device and a
raw material gas liquefying loop. A discharging port of the compressor is connected with a feeding port of the condenser; a discharging port of the condenser is connected with a feeding port in a kettle of the rectifying device; the rectifying device comprises a rectifying
tower and a
tower top
heat exchanger, wherein the
tower top
heat exchanger is communicated with the top of a rectifying section of the rectifying tower; a discharging port at the top of the tower top
heat exchanger is connected with the
raw material gas liquefying loop; and the
raw material gas passes through the raw material gas liquefying loop and a final liquefying product is obtained. In the invention, a multi-stage
separation process of the traditional mixed working medium liquefying
system is replaced by the rectifying device, the high-pressure liquids with different components led out from the bottom and the top of the rectifying device are respectively subject to
pressure reduction to enter the raw material gas liquefying loop, the change of the
water equivalent weight in the temperature-reduction liquefying process is matched in an optimized way so that the raw material gas is cooled section by section. The rectification-type self-overlaying gas liquefying
system has the advantages of simple structure, reliability in operation, high system liquefying efficiency and the like, and is particularly suitable for various mini-type and micro-type gas liquefying systems.