Modelagem e simulação de um reator de oxicloração em leito fluidizado para produção do 1,2-Dicloroetano

Abstract

Taking 1,2-dichloroethane from the Oxychlorination reaction is a commercially very important process due to large application of the 1,2-dichloroethane in the chemical industry for the PVC production. PVC is one of the commodities more used in the world chemical chain because of its wide application strip as plastic. The purpose of this study is to develop a mathematical model to describe the ethylene Oxychlorination reaction in a bubbling fluidized bed reactor. Of the many models proposed in the past, the two-phase model which considers the fluidized-bed reactor to consist of a bubble phase and a surrounding dense phase has proved to be the most suitable model, for incorporating recent findings on the hydrodynamics of fluidization. In the proposed study, the rigorous theory of the two-phase flow was used to model the fluidized-bed reactor, and the theory proposed by Kunii-Levenspiel (1991), based in phenomenological equations. It was considered one-dimensional flow in stationary state. The effect of operating and design parameters was studied. The parameters includes the pressure operation, bubble diameter, particle diameter, feed temperature, cooling médium temperature, height at minimum fluidization, height of expanded bed, cupper concentration in the catalyst ,and the diameter of the reactor. The mass transfer of the species presents in the gas mixture between the bubble phase and the emulsion phase were also studied to investigate their influence in the reactor performance. The freeboard region was also studied to investigated it’s importance in the overall conversion of ethylene. We used the kinetic model proposed by Wachi & Asai (1994) for the formation of 1,2-dichloroethane from ethylene and cupric chloride. The ordinary differential equations system that represents the mathematical model of the bed was solved through the application of the numeric method of Gauss-Newton. The ordinary differential equations system that represents the mathematical model of the freeboard was solved through the application of the numerical differentiation formulas (NDFs) . The solutions are developed using the software Matlab®. The fluidized-bed model is tested against a real plant date, operating by Braskem S.A in the city of Marechal Deodoro, Alagoas State, Brazil.