VERY LARGE LATTICE MODEL OF LIQUID MIXING IN TRICKLE-BEDS (PERCOLATION)

A three-dimensional very large lattice model (VLLM) based on percolation theory concepts is used to predict the performance of isothermal and non-isothermal trickle-bed reactors. The packed-bed is simulated by a three-dimensional network of randomly connected transport cells (sites) representing the liquid flow paths. The liquid flow through the cells is mathematically determined using percolation theory. Simulation of a transport cell by a micro continuous stirred tank reactor ((mu)-CSTR), in which a single, first order, irreversible reaction proceeds isothermally and non-isothermally, is considered. This enabled the VLLM to predict the effects of liquid flow maldistributions on the conversion and temperature profiles. The possible occurrence of multiple steady states and the existence of local hot spots in non isothermal trickle-bed reactors are also predicted.; Experimental data on the liquid flow distribution are found to be in excellent agreement with the VLLM theory. A theoretical formula expressing the mean film thickness as a function of the film Reynolds number and a theoretical correlation of the dynamic liquid hold-up are proposed based on the VLLM. Both of these correlations are in very good agreement with experimental data from the literature. Since the gas phase is implicit in the model results, the extension to packed-beds may be carried out without introducing any new parameters.