System and method for ammonia synthesis by using renewable energy sources

The invention discloses a system and a method for synthesizing ammonia by utilizing renewable energy sources. The system comprises an ammonia synthesis tower, a waste heat recoverer, a heat exchanger, cooling equipment and an ammonia separator, a gas inlet pipeline and a gas outlet pipeline are connected to the ammonia synthesis tower, and a thermal circulation gas pipeline is arranged on the gas outlet pipeline between the heat exchanger and the ammonia separator and connected to the gas inlet pipeline on the heat exchanger through a circulation gas compressor. A secondary return pipeline is arranged at the joint of the heat circulating gas pipeline and the gas inlet pipeline and is connected with the gas inlet end of the circulating return pipeline; aiming at the instability of energy supply of renewable energy sources such as wind and light, when a difference value is generated between the total flow of hydrogen and nitrogen input into the system and the total flow of full-load hydrogen and nitrogen, the a