Non-linear identification of aqueous ammonia binary distillation column based on simple Hammerstein model

Ammonia is an important fluid to produce urea, NPK, ammonium sulfate and other fertilizer products. So, high quality of ammonia at low operating cost is an importance factor. Presently, due to the oversized valve and other dynamic factors, the ammonia stripper as a subsystem of ammonia plant is difficult to be controlled especially during start-up operation. For control redesign purposes, the ammonia stripper which is basically an aqueous ammonia binary distillation column will be identified by a simple quadratic Hammerstein model due to its non-linear characteristics. The experiment was conducted on real-time plant operation of a fertilizer plant in Gresik, East Java, Indonesia. Validation method was also performed to verify the results of identification. The results show how the models represent the dynamics characteristics of the ammonia stripper quite satisfactorily.