Research On Simulation And Optimization Of Ammonia Synthesis Process

The synthetic ammonia is regarded as the pillar trade of the chemical field, so the simulation and optimizing in ammonia plant are imperative. As the key part of synthetic ammonia process, ammonia synthesis system is one of the key links to increase production and conserve energy. Starting from the practical production, we have used computer modeling technique to simulate and analyze the ammonia synthesis system in a fertilizer plant. Main studies in this paper are as follows:(1) According to the physical Properties of the ammonia synthesis system, the proper unit operation model and thermodynamic property calculation method were chosen to the system simulation and calculation on the steady state process simulation of Aspen Plus software. The data of material balance and energy balance were obtained. The results can reflect the actual situation of ammonia synthesis system, and the model can be applied to the simulation and optimization for ammonia synthesis process.(2) Based on the accurate simulation of ammonia synthesis system, the energy use situation of the main equipment was analyzed. The influences of pressure, heat exchanger temperature, water cooler temperature and ammonia cooler temperature on system energy using were studied. We considered reducing the energy consumption from changing of the operating parameters.(3) Taking all factors into consideration, such as consumption of Utilities and feed gas, Equipment depreciation and ammonia production, the optimization objective function called systematic net income was given. Then using maximum systematic net income as objective function, the optimum values of the main operating parameters were obtained:synthesis pressure 20.4MPa, converter inlet temperature 370℃, the representation of purge gas 0.04, H/N 3.0, recycle compressor isentropic efficiency 0.8, the representation of principal line 0.55.(4) The method of combining the process simulation and orthogonal test was stated. And it was applied to the optimization of ammonia synthesis system. The optimization direction and influence effect of operating factors have been given out. Finally, the optimum working condition of ammonia synthesis process was obtained: synthesis pressure 20.5MPa, converter inlet temperature 370℃, the representation of purge gas 0.035, H/N 3.0, recycle compressor isentropic efficiency 0.8, the representation of principal line 0.575. The systematic net income of the optimum working condition was increased 0.8632 yuan/h than original condition.We studied and explored the potential of ammonia synthesis system optimization, provided the viable calculation model and optimization method. And we successfully established the effective foundation for the further investigation of optimization of ammonia synthesis process through the effective optimization work.