Ammonia synthesis cooling methods

The preparation conditions of each step significantly influence the physical properties and catalytic performance of the catalyst. The key steps for production of ammonia synthesis catalysts by melting method are the purification of raw materials, controlling of Fe +/Fe + ratio, and the cooling speed during the solidification process. 

In the converter, only one of the three cooling methods mentioned above can be used, also two of them can be combined for application. For example, the cold-quench type is used between the first and the second bed, and the indirect heat exchange type is used between the second and the third bed. Some interchangers between beds are placed outside the converter such as Brown converter (Fig. 9.22). It is worth noting that because the ammonia synthesis reaction on the Fe catalyst needs high temperature (400-550°C) and high pressure (over 10 MPa), the... 

The energy consumption figures discussed so far represent a thermodynamic analysis based on the first law of thermodynamics. The combination of the first and second laws of thermodynamics leads to the concept of ideal work, also called exergy. This concept can also be used to evaluate the efficiency of ammonia plants. Excellent studies using this approach are presented in [1061], [1062], Table 39 [1061] compares the two methods. The analysis in Table 39 was based on pure methane, cooling water at 30 °C (both with required pressure at battery limits), steam/carbon ratio 2.5, synthesis at 140 bar in an indirectly cooled radial converter. 

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