Double-refrigerant circulating natural gas liquefaction system based on wound-tube heat exchanger

The invention provides a double-refrigerant circulating natural gas liquefaction system based on a wound-tube heat exchanger. The double-refrigerant circulating natural gas liquefaction system is characterized by comprising a precooling level compression module, a precooling level heat exchange module, a copious cooling level compression module and a copious cooling level heat exchange module which are connected, wherein the precooling level compression module comprises buffer tanks, compressors and coolers which are connected in sequence; a precooling refrigerant low-pressure outlet of the precooling level heat exchange module is connected with one of the buffer tanks; a natural gas first-level outlet is connected with a gas-liquid separator; the outlet of one of the coolers is connected with another gas-liquid separator; the copious cooling level compression module comprises buffer tanks, compressors and coolers which are connected in sequence; a copious cooling refrigerant low-pressure outlet of the copious cooling level heat exchange module is connected with one of the buffer tanks of the copious cooling level compression module; a natural gas second-level outlet is connected with the exterior; a natural gas second-level inlet is connected with one of the gas-liquid separators; the outlet of one of the coolers of the copious cooling level compression module is connected with a copious cooling refrigerant first-level inlet; and a copious cooling refrigerant first-level outlet is connected with a gas-liquid separator of the copious cooling level heat exchange module. According to the double-refrigerant circulating natural gas liquefaction system, two-level independent mixed refrigerants circulate and are overlaid, the system process is concise, the structure is compact, the production load operational flexibility is high, the integral machine adopts modularized design, and the system is applicable to offshore flotation natural gas production devices.