Method for desalting seawater by utilizing cold energy of liquefied natural gas through phase transition-free indirect refrigeration

The invention relates to a method for desalting sea water by utilizing the cold energy of liquefied natural gas through phase transition-free indirect refrigeration, belonging to the technical field of refrigeration and cryogenic engineering. Firstly, heat exchange is carried out between the liquefied natural gas and liquefied secondary coolant in a heat exchanger, and the liquefied natural gas is gasified to absorb heat, thereby reducing the temperature of the secondary coolant while maintaining the phase thereof; secondly, the liquid phase secondary coolant enters a crystallizer and indirectly exchanges heat with seawater so as to refrigerate the seawater on the heat exchange surface into ice, and the secondary coolant absorbs heat to raise the temperature and is not gasified. The prepared ice is rinsed in a rinsing tank so as to eliminate salt attached to the surface of the ice and then is led into an ice melting tank to be melted into fresh water. The invention recovers a great amount of cold energy accumulated in the liquefied natural gas, dispenses with a high consumption refrigerating unit, and can effectively reduce the energy consumption of indirect refrigeration seawater desalination device.