A long-standing misconception in articles and books on ammonia synthesis must be corrected.

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For example, one textbook states that in production, it is appropriate to maintain a hydrogen-to-nitrogen ratio of 2.5 to 2.9 for the gas circulating within the tower. Since the hydrogen-to-nitrogen ratio used in synthesis is 3:1, the hydrogen-to-nitrogen ratio of the fresh gas added should also be 3; otherwise, excess hydrogen or nitrogen will accumulate in the circulation system, leading to an imbalance in the hydrogen-to-nitrogen ratio of the circulating gas. ——This statement is incorrect! When venting gas, nitrogen usually makes up a little over one-third of hydrogen; in liquid ammonia, even less hydrogen is dissolved, with it being only slightly more abundant than nitrogen at best. Therefore, proportionally, the loss of nitrogen is always higher than that of hydrogen. Therefore, if the gas fed into the reactor – whether it is fresh gas added or a mixture of recycled gas and fresh gas – is mixed in a 3:1 ratio, then the amount of nitrogen in the reactor will gradually decrease, while the hydrogen-to-nitrogen ratio will increase. Even if the synthesis tower is determined from the start to produce at a 3:1 ratio, the dissolution of liquid ammonia will cause nitrogen to decrease much more rapidly than hydrogen, resulting in production at a hydrogen-to-nitrogen ratio of over 3, which is unfavorable for the production process. The hydrogen-to-nitrogen ratio of the fresh gas should be less than 3; the excess nitrogen supplied should be sufficient to compensate for the losses of nitrogen in the exhaust gases and through ammonia dissolution. But it’s not just this textbook; almost all documents state this, or with slight variations – some say that the fresh gas ratio must be 3:1, while others say that the combined ratio of fresh gas and recycled gas should be 3:1 – and all of these are incorrect. If this error did not lead to any consequences, then it should be the case that people control the process strictly based on practical experience: when there is too much nitrogen, hydrogen is added to regulate it, and when there is too much hydrogen, nitrogen is added to regulate it. They didn’t bother at all to consider what the book said. The so-called “ammonia balance” is also a vague concept. There is more gas entering the tower than exiting it; how can simple subtraction be used? To measure the synthesis amount in the synthesis tower, it should be the total volume of ammonia in the gas exiting the tower, minus the total volume in the gas entering the tower; the proportion this represents in the exit gas is slightly lower than that obtained through simple subtraction. It can be used approximately as well.