MODELLING AND SIMULATION OF A DIASPORE TUBULAR DIGESTION PROCESS

Mohammad Farrokh, Jafar Mahmoudi, and Erik Dahlquist

Keywords

Low alumina/silica ratio, diaspore, tubular digestion, processsimulation

Abstract

A simulation model is developed to predict the performance of a tubular digestion process of a low alumina/silica ratio diaspore bauxite type. The electrolyte – NRTL property method is used to calculate the equilibrium and thermodynamic properties of the slurry. The Aspen Plus simulator has been employed to solve the reaction and thermodynamic submodels. The model was validated with several sets of the industrial experimental data in terms of the flash tanks temperatures and close agreement was found. The simulation model has been utilized by the R&D department to predict the digestion process behaviour at various operation conditions. One practical output of this work is suggestion for a new design to increase the vapour and thermal energy recovery in the digestion process unit. As a result, the exhaust vapour from the last flash tank was directed to a new pre-heater section. The industrial output has been confirmed by the energy department that has decreased 8% in the furnace fuel consumption and leads to an increase of water recovery in the digestion unit.

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