Modelagem e simulação de um reator de pré-reforma de nafta

Abstract

The adiabatic prereforming of naphtha is a catalytic process that presents both economical and operational benefits. A model of this process is an important tool to be used for optimizing the operational conditions and for design purposes.Adiabatic prereforming of naphtha design with the commercial catalyst CRG, a nickel catalyst supported by alumina, was studied in an fixed bed industrial reactor. The temperatures were measured by thirty-two thermocouples placed in an axial thermowell in the bed of the reactor. Temperature and pressure in the entrance and exit of the prereformer were obtained directly from data already recorded existing in the Industrial Unit. The reactor operated during 42 months in the temperature range 440ºC-480ºC, with total pressure varying from 15 to 20 bar and steam-to-carbon ratio at the inlet equal to 3. One-dimensional pseudo-homogeneous mathematical model, steady state was developed. In this model, the kinetic expressions of the Reforming, Methanation and Shift reactions were included. Measured and calculated temperature profiles were obtained for several operation periods of the reactor. The simulated temperature profiles reproduced qualitatively the original tendency of the industrial data. A comparison between the calculated and measured values showed that the model formulated mispredictions the process gas temperature and molar flow rates at the pre-reformer outlet. The models studied showed the main trends of the process, but have proved uncapable of representing them quantitatively. This is believed to be due to inadequate when considering the kinetic characteristics of the pre-reform reactor from PERÓXIDOS DO BRASIL.