Method for liquefying natural gas and nitrogen

Provided is a method for producing liquefied natural gas and a stream of liquid nitrogen comprising at least the following steps: step a): production of gaseous nitrogen by an air separation unit (ASU); step b): liquefaction of a stream of natural gas in a natural gas liquefaction unit comprising a main heat exchanger and a frigorie production system; and step c): liquefaction of the stream of nitrogen originating from step a) in the said main exchanger of the natural gas liquefaction unit in parallel with the natural gas liquefied in step b). The method is characterized in that all the cold required for liquefying the stream of nitrogen and for liquefying the natural gas is supplied by the said frigorie production system of the natural gas liquefaction unit. 种用于产生液化天然气和液氮流的方法，该方法包括至少以下步骤：步骤a)：通过空气分离单元(ASU)产生气态氮气；步骤b)：在天然气液化单元中液化天然气流，该天然气液化单元包括主热交换器和用于产生低温的系统；步骤c)：在天然气液化单元的所述主交换器中将由步骤a)产生的氮气流与步骤b)中的液化天然气并行液化；其特征在于，用于液化氮气流和用于液化天然气所需的所有低温由天然气液化单元的所述用于产生低温的系统供应。