Ammonia synthesis system and method

Ammonia synthesis system comprising:

• an ammonia synthesis column that synthesizes an ammonia gas from a raw material gas for ammonia synthesis;
• a discharge line that discharges a synthetic gas containing the ammonia gas obtained from the ammonia synthesis column and an unreacted raw material gas;
• a water-cooled or air-cooled cooler that water-cools or air-cools the synthetic gas, disposed in the discharge line;
• an ammonia separator to which the discharge line is connected, into which the synthetic gas after cooling is introduced, and which separates the ammonia gas and a liquid ammonia from each other;
• a raw material return line that returns a raw material gas containing the ammonia gas separated by the ammonia separator to the ammonia synthesis column side as a return raw material gas;
• and
• a compressor that compresses the return raw material gas, disposed in the raw material return line, wherein
• an ammonia concentration in the return raw material gas to be introduced into the ammonia synthesis column is 5 mol % or more, and an ammonia synthesis catalyst that synthesizes the ammonia gas in the ammonia synthesis column is a ruthenium catalyst.