Numerical Simulation of the Heat Transfer for a Three-Phase Reactor of Fixed Bed

Abstract

Heat transfer plays an important role in several applications of fixed bed reactors with concurrent down-flow of liquid and gas. Because of the possibility of forming hot spots on the bed of this reactor, which can inhibit the process catalyst and impair the proper functioning of the equipment. Thus, the present paper presents a mathematical model to simulate the process of heat transfer in these reactors. The mathematical modeling was performed by the technique known as Coupled Integral Equation Approach (CIEA). It is a new formulation, based on Hermite integral approximations (H_0,0/H_0,0 and H_0,0/H_1,1), present more accurate results with a shorter CPU time, than the more traditional techniques and transforms the partial differential equations (PDEs) into ordinary differential equations (ODEs). From this formulation, the results of the ODEs were obtained through the Euler method and the variation of the temperature over time with different values of the heat transfer coefficient was perceptible, being clear the influence of this parameter for the good application of the equipment the desired processes, such as steam reforming of hydrocarbons. In addition, the paper contains a comparison of the mathematical techniques of the approximations (H_0,0/H_0,0 and H_0,0/H_1,1), making it clear that H_0,0/H_1,1 is the best technique to be used in the simulation.