GAS-LIQUID REACTOR IN THE SYNTHESIS OF UREA

In spite of the fact that urea has raised to become the most important fertilizer, till now a scant scientific attention has been devoted to the understanding of the detailed behaviour of the reactor wherein the urea synthesis takes place. It is a typical gas-liquid reactor involving not only backmixing fenomena, but also significant aspects of heat and mass transfer between vapor and liquid phases, together with liquid and gas-liquid homogeneous and heterogeneous phases equilibria and kinetics. Fluid dynamic problems are created by the cocurrent gas-liquid flow through the perforated plates which generates intermittent bubbles swarms. Purpose of this paper is to present bases and results obtained through a "complete" modelling (covering thermodynamic, kinetic and fluid dynamic aspects) of gas-liquid stagewise reactor, and comparison with real data of commercial units. Original kinetic equation and some thermodynamic data related to the very complicated equilibria involved are also presented.