THEORETICAL & EXPERIMENTAL STUDIES ON A HIGH PRESSURE COLUMN FOR THE SEPARATION OF AN AZEOTROPIC MIXTURE

Abstract

related to the separation of azeotropic mixture. For the separation of homogeneous azeotropic mixtures pressure swing distillation columns are widely being used. But until now, only a limited number of experimentally validated studies have been published. The study used a distillation column with total 28 trays with multiple feeding facilities at different trays. We did total 6 experiments and total number of measured variables was 150, which contains measurement of different flows, temperatures and pressures. The experimental work comprised of the investigation of feasible operating conditions of high pressure distillation column and collection of various steady states data for further investigation. In the theoretical work, we estimated the parameters, which are generally changed from column to column or depend upon the operating condition of the column. This estimation was based upon our steady state experimental results and simulation results from a rigorous model of the column. For the estimation of parameter, we used maximum likelihood method and kept the objective function as minimization of the difference between simulated results and experimental results. The column model is based upon the mass balance, energy balance, equilibrium relations etc. for each stage of the column. We also considered the affect of uncertainty and disturbances in that estimation. Column's Piping and Instrumentation Diagram (P & ID) and standard operation procedure of working is also discussed in detail. To found out the mixture composition with out the use of gas chromatography, a relation between mixture density and mixture composition based upon excess volume of mixing is also established. Pressure at the top of the column was controlled by cooling water flow in the condense' For this control, a MATLAB program based upon nonlinear model predictive control was used which changed the cooling water requirement in the condenser according to column's top pressure.