Method for desalting seawater by utilizing cold energy of liquefied natural gas through direct contact refrigeration

The invention relates to a method for desalting seawater by utilizing the cold energy of liquefied natural gas through direct contact refrigeration, belonging to the technical field of refrigeration and cryogenic engineering. Firstly, heat exchange is carried out between the liquefied natural gas and secondary coolant in a heat exchanger, the liquefied natural gas is gasified to absorb heat so as to condense the water-insoluble secondary coolant by reducing the temperature thereof, the condensed secondary coolant is sprayed into a crystallizer to exchange heat with seawater through direct contact, liquid drops of the secondary coolant is evaporated to absorb heat, and therefore seawater around the liquid drops releases heat and is refrigerated into ice crystals. 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 a melting device to be melted into fresh water. The process 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, the loss of the heat exchange process is low, and the size of the device is small.