Ammonia is the most important basic chemical for fertiliser production. Modern ammonia plants essentially consist of a hydrogen plant, a nitrogen plant and an ammonia synthesis plant. During ammonia synthesis, ammonia (NH3) is made from hydrogen (H2) and nitrogen (N2) molecules in a ratio of 3:1 at extremely high pressures of 250 to 300 bar and temperatures of 450 °C to 500 °C.
The nitrogen can be taken either from the air, or it is made available in a highly pure form by nitrogen production plants.
The advantage of providing pure nitrogen over air as a nitrogen source is the lack of argon. Argon accumulates during operation of the cyclical process and must be eliminated by means of a continuously discharged exhaust gas stream. This leads to the loss of valuable raw materials and energy. Substantial improvements can also be achieved in the case of air-driven systems by the addition of pure industrial gases.