Desalting method with phase change for indirectly freeze seawater by using of liquefied natural gas refrigeration capacity

The invention relates to a desalting method with phase change for indirectly freeze seawater by using liquefied natural gas refrigeration capacity, belonging to the technical field of refrigeration and low-temperature engineering. The liquefied natural gas exchanges heat with a secondary refrigerant in a heat exchanger firstly, the liquefied natural gas absorbs the heat to lead the temperature of the secondary refrigerant to reduce and generate gas-liquid phase change, then the secondary refrigerant enters a crystallizer and indirectly exchanges heat with seawater so as to lead seawater to be frozen to ice on a heat exchanging surface, and simultaneously the secondary refrigerant absorbs heat to be gasified. The prepared ice enters a water tank and melts into fresh water. The recovered liquefied natural gas contains large amount of refrigeration capacity, does not need a high-energy consumption refrigerating unit, and can effectively reduce the energy consumption of a desalting device for indirectly freezing seawater.