Sugar Extraction via Moving-Bed Diffusers in Ethanol Production Industry: Phenomenological Modeling and Finite-Volumes Simulation

Abstract

This work proposes a steady-state two-dimensional phenomenological model for sugar extraction in industrial moving-bed diffusers. The mathematical formulation of the model is based on the theories of transport phenomena in porous media, which is an original and formal theoretical approach to describe sugar extraction in sugar cane beds. Averaging techniques were applied to convert the model equations into macroscopic mass balances over continuous volumes. The model was discretized by the finite volume method and solved by a supernodal LU factorization routine. In order to make the model and the solution procedure user-friendly, a computer-aided simulation framework was developed in the Python programming language. The outputs of this framework are extraction degree, °Brix curve, and °Brix distribution in the bed. This last output is unprecedented in literature. A real industrial moving-bed diffuser was used as a case study to demonstrate the capabilities of the simulation framework. Solution procedures of the model equations were accomplished accurately in a few seconds. Simulated outputs are in good agreement with the expected behavior of the real equipment. The developed simulation framework arises as a fast and reliable predictive tool, which has the potential to assist design and operation of moving-bed diffusers in the ethanol production industry.