Natural gas liquefaction system and process based on coiled tube heat exchanger

The invention provides a natural gas liquefaction system and process based on a coiled tube heat exchanger, and relates to the technical field of natural gas liquefaction. The system comprises a liquefaction device and a heavy hydrocarbon removal device. The liquefying device comprises a pre-cooling plate-fin heat exchanger, a liquefying coiled tube heat exchanger and a supercooling coiled tube heat exchanger. The heavy hydrocarbon removal device comprises a heavy hydrocarbon washing tower. In the natural gas liquefaction system based on the coiled tube heat exchanger, the plate-fin heat exchanger and the coiled tube heat exchanger are simultaneously used, so that the characteristics of the plate-fin heat exchanger and the coiled tube heat exchanger are combined to enhance advantages and avoid disadvantages. The process comprises the following steps: cooling gas-phase purified natural gas to-11 DEG C to-15 DEG C in a pre-cooling plate-fin heat exchanger, and feeding the cooled gas-phase purified natural gas i