Volker Herdegen

A Model Approach for the Montan Wax Extraction: Model Development and Experimental Analysis

A model is developed based on experimental and theoretical analysis for the description of the Montan wax extraction process. This paper focuses on Graefe extraction, a standard methodology in brown coal industry, which is used to estimate the maximum yield of available wax. Using the results of Graefe extraction, the equilibrium curve and transfer coefficient can be identified by means of a global optimization algorithm Molecular-Inspired Parallel Tempering (MIPT). Another aim of the work is to predict the yields of Montan wax extracted by a percolation-column extraction, which contains 100 times the amount of brown coal as it is used in Graefe extraction.

Identification and analysis of mass transfer coefficients and effective diffusion coefficients for models of solvent extraction of Montan wax

ABSTRACT Montan wax extraction which is considered to be an application of solid–liquid extraction (leaching) was systematically studied. Different mass transfer models for Montan wax extraction of brown coal–toluene system are established to simulate and analyse the extraction process with fixed-bed extractors and stirred extractors. Empirical correlations are applied to determine the mass transfer coefficients and the axial diffusion coefficient . A method (denoted as Opt-empirical method) to estimate the effective diffusion coefficient is proposed for the Montan wax extraction, which is validated by using sets of experimental data in percolation columns and stirred extractors.