Modelagem matemática e estudo de sensibilidade paramétrica de um reator de síntese de ureia

Abstract

One of the main challenges of the chemical industry is the search for strategies saving mass and energy for various processes, either in the design of new projects and in the improvement of existing technologies. In a manufacturing process this paradigm corresponds to reduce as much as possible the formation of undesirable products and energy consumption in the steps involved in the process. In this dissertation is developed a phenomenological model for urea synthesis reactor and, from this, a computational modulus for the synthesis process simulation. A mixing cell model was proposed for the representation of the real system in the transient regime, considering the conservation equations of mass and energy. A fourth order Runge-Kutta method was implemented in the programming language Matlab (Matrix Laboratory) to solve systems of ordinary differential equations representing the mathematical model. Besides the model of the reactor, a thermodynamic modulus has been developed in order to analyze the influence of pressure on the fugacity coefficients of the species from the gas phase and the influence of temperature on the activity coefficient of the species from the liquid phase. From computer simulations became a parametric sensitivity study of the main operating variables that determine the performance of the urea reactor. The parameters examined in the sensitivity tests were: the molar ratio between water and carbon dioxide, the molar ratio between ammonia and carbon dioxide and the feed temperature. A study of the dynamic behavior of the reactor was also done for disturbances in the inlet temperature of reactants.