A Validated Flowsheeting Tool for the Study of an Industrial Granulation Process

Abstract

This work evaluates the capabilities of a complete dynamic simulator developed for a urea granulation circuit (based on fluidized-bed technology) to analyze the process sensitivity against different disturbances and to study common operating problems. First, the circuit model is validated by comparing simulation results with plant data from a high capacity industry. Based on a sensitivity analysis of the process variables, diverse strategies are explored aiming to solve typical operational challenges (i.e., too high granulation temperatures, undesired dust formation, low fluidized-bed heights, etc.) by considering different control variables or alternative flowsheets configurations. It is demonstrated that an appropriate fluidization air distribution between the different granulator chambers allows to control, within certain limits, the often too high fluidized-bed temperatures. Furthermore, it is shown that by adjusting the total granulator pressure drop, the fluidized-bed levels can be kept within the desired ranges. Finally, the developed flowsheeting tool suggest that the partial bypass of the fines generated in the crusher can be an efficient strategy for improving product on specification, while the circuit variables remain within the desired operating range.