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

COTABARREN, IVANA MARÍA; BERTÍN, DIEGO ESTEBAN; PIÑA, JULIANA; BUCALÁ, VERÓNICA

Nuremberg

Congreso; World Congress on Particle Technology; 2010

PARTEC

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 for the granulator and cooler. All the units are modeled by means of the population balance equation. 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 size enlargement unit dynamics. Furthermore, mass and energy balances are developed for the fluidized bed cooler model. The individual units are successfully integrated under the gPROMS Molder Builder Environment, which allows having a powerful tool for the simulation and the optimization step. Later, a sensitivity analysis is performed in order to evaluate the influence of different operating variables on the particle size distributions (PSDs) and mass flowrates of the circuit different streams, as well as the physical and thermical conditions in the granulator and cooler. Finally, an optimization is carried out to determine the values of the manipulated variables that maximize production under specification.