Mathematical Models for Packed Bed Reactor for Methanation of Carbondioxide<sub>

Abstract

Models for carbondioxide methanation in a packed bed reactor was developed from first principles by the application of the law of conservation of mass and energy. The kinetic expressions of the process where obtained from relevant literatures and incorporated and solved simultaneously with the developed models using Matlab ODE45 solver. Sensitivity analysis was performed to ascertain the optimal conditions gave reasonable results, which were validated with plant data and was found to be accurate with deviations within allowable range. The research study focuses on carbondioxide methanation reaction for production of synthetic natural gas (SNG) and the performance of the process is characterized by carbondioxide conversion under various operating conditions. One dimensional pseudo-homogeneous packed-bed reactor model neglecting all possible mass and heat constraints was used as a reference and the resulting model equations are solved numerically. The reaction rates and exothermicity (ΔH°=-165KJ/Mol) prevent a packed bed reactor to be operated at high conversions and the reactant inlet temperature is used as a primary parameter, while an optimum inlet temperature is determined at which the carbondioxide conversion has maximum value. With inlet temperature higher than the optimum temperature, CO₂ conversion decreases due to the reverse Sabatier reaction.