SIMULATION OF AN AMMONIA PLANT ACCIDENT USING RIGOROUS HETEROGENEOUS MODELS - EFFECT OF SHIFT CONVERTERS DISTURBANCES ON THE METHANATOR

Disturbance introduced into the shift, converters section of the ammon ia production line may lead to problems in the ammonia production line which manifest themselves in other units of the production line. A re al accident that took place in an ammonia production line some years a go is simulated using rigorous models for the units of the ammonia lin e starting at the high temperature shift converter and ending at the e xit of the methanator. Reliable mathematical models are invaluable too ls for the follow-up of the sequence of events leading to an accident. The effect of various types of disturbances introduced to the shift, converter's section are simulated. The main aim is to find out the eff ect of these disturbances on the methanator, which is an adiabatic fix ed reactor preceding the ammonia converter and acting as a guard for t he ammonia synthesis catalysts against CO and CO2 poisoning. The simul ation results show, in a realistic manner, the sequences of events lea ding to temperature runaway in the methanator due to these disturbance s in the shift converters section. The results are very valuable for u nderstanding this complex interaction between the units and finding ou t the best operator response to avoid a shutdown or an accident.