Dynamic Simulation and Optimization of a Urea Granulation Circuit Including Mass, Energy, and Population Balances

COTABARREN IVANA; BERTIN, DIEGO; PIÑA, JULIANA; BUCALÁ, VERÓNICA

Nüremeberg

Congreso; World Congress on Particle Technology 6; 2010

A dynamic model for a complete urea granulation circuit is presented in this work. The flowsheet includes a fluidized bed granulator, a cooling unit, a vibrating double-deck screen, and a double-roll crusher. This contribution is based on previous validated models against industrial data for the crusher and screen and on new models proposed for the multichamber granulator and fluidized bed cooler. All the units are modeled by means of the population balance equation (PBE). In addition, the granulator energy and mass balances for urea and air (used as a cooling medium and fluidization agent) are solved simultaneously with the PBE to properly represent the unit dynamics. Furthermore, mass and energy balances are developed for the cooler. The individual units are successfully integrated under the gPROMS Molder Builder Environment, which allows having a powerful tool for the circuit simulation and optimization. A sensitivity analysis is performed in order to evaluate the influence of different operating variables on the particle size distributions and mass flowrates of the circuit streams, as well as the mass holdup and thermal conditions in the granulator and cooler. An optimization is carried out to determine the values of the selected manipulated variables that maximize production under specification.