In natural gas liquefaction technology, has a new nitrogen expansion refrigeration technology, liquefied natural gas liquefaction process, expansion refrigeration refrigeration, refrigeration cascade mixed liquefaction liquefaction process as examples. Especially the new self-developed mixed refrigerant liquefaction process, due to the distribution of technology uses a unique liquid flow, to avoid the bottom effusion cold box, the device is energy-saving and stable; drying refrigeration system design unique, greatly shorten the driving time and driving cost; design of refrigeration system unique supplement, save the driving time.