The Simulation and Control of Ammonia Unit of Shiraz Petrochemical Complex, Iran

The aim of this paper is the steady state and dynamic simulations of the ammonia unit of Shiraz petrochemical complex and system behavior study versus the feed flow rate change for producing a good quality product. The ammonia unit consists of the reformer units, shift converter units, carbon dioxide absorption unit, methanation unit, and ammonia synthesis unit. For this purpose, in the first step, the ammonia unit is simulated at a steady state using the Aspen Plus 2006.5 simulator. In the following stage, the required parameters are entered into the software for the dynamic simulation. The Aspen Plus was exported to Aspen dynamic. In this study, PI and PID controllers, as basic controllers, were automatically added and tuned by the Tyreus–Luyben tuning method. Finally, in order to ensure the accuracy of the proposed control structure, the feed flow rate increased by 5%. The results show that, first of all, the simulation accuracy at steady and dynamic states are optimal so that the mean errors are -0.01% and -0.02% for steady and dynamic states, respectively. The controlling structure can well control the 5% feed increase.