Predicting Conversion and Catalyst Performance of a De-hydrogen Catalytic Reactor in Urea Plant

Explosion risk is one of the main reason a de-hydrogen catalytic reactor is installed in most urea fertilizer plants. The reactor removes hydrogen impurities from carbon dioxide by reacting hydrogen and oxygen to form water, with the help of platinum (Pt) catalysts. The de-hydrogen catalytic reactor must be monitored to keep the hydrogen outlet at less than 100 ppm. However, important parameters such as reactor conversion cannot be directly seen in the operator’s panel. To address this challenge, a process simulation approach was employed to analyze and predict the conversion of the de-hydrogen catalytic reactor. The objectives of this study were to identify correlations between the de-hydrogen reactor conversion and various operating conditions, including temperature, hydrogen gas flow rate, and oxygen excess. Utilizing these correlations, a model was developed to predict de-hydrogen reactor conversion and estimate catalyst deactivation in a real-time monitoring system. Correlation analysis revealed a negative correlation between hydrogen inlet molar flow rate and conversion, particularly when flow rates exceeded 4600 Nm³/day. A similar negative correlation was observed for the oxygen concentration at the outlet of the reactor, particularly at values above 7700 ppm. Conversely, a positive correlation was established between the temperature difference between the inlet and outlet of the reactor and hydrogen conversion. When this temperature difference was less than 5 °C for 0.1%-vol of hydrogen concentration, it was indicative of an impending deactivation of the platinum catalysts. The utilization of this prediction model, combined with its integration into a real-time monitoring system equipped with an early detection mechanism in the actual plant, would yield substantial advantages in terms of cost reduction for maintenance and extension of the catalyst’s lifespan.