Dynamic Operation of a Haber-Bosch Loop with Quench-Cooled Converter for Power-to-Ammonia Systems

This work presents a preliminary application of a developing methodology for assessing the operational flexibility of ammonia synthesis loops. Part of this methodology involves systematic dynamic testing in the synthesis loop. In the present case, a synthesis loop equipped with a two-bed, quench-cooled converter operating under variable feed conditions was considered. A high-fidelity model of the converter was developed in gPROMS Process using two-dimensional reactor models from its fixed-bed catalytic reactor library, and a synthesis loop configuration was modeled and designed in the same environment. A series of dynamic tests varied the make-up flow rate across four disturbance amplitudes (±25% and ±50%) and four disturbance durations (10 s, 600 s, 1800 s, 3600 s). The results showed that disturbances of ±50% magnitude led to the violation of one process operational constraint. These findings enable the construction of a preliminary operational map of this system, providing an initial determination of its process boundaries, and therefore its current degree of flexibility. Such knowledge is fundamental to understand how the synthesis loop can be made more flexible so that it suits Power-to-Ammonia applications. Overall, this study constitutes an initial step toward the development of a framework for enhancing the flexibility of ammonia synthesis loops.