MODELING AND SIMULATION OF DIVIDED WALL DISTILLATION COLUMN

Abstract

In distillation columns pressure drop calculations Pressure drop calculations are negligible due to insignificant effect on the vapour liquid-equilibrium (VLE). extensively used for finding tray spacing at the time of designing a column, but these'are rarely performed for the simulation purposes since the minor change in pressure (from condenser to reboiler) has insignificant effect on the VLE. However, pressure difference plays an important role in deciding vapour and liquid flow rate across a tray (or trays) particularly in. case of interconnected or divided wall distillation column (DWC). In case of DWC, the feasible vapour split ratio below the divided wall section is naturally adjusted in such a way that pressure drop in two parallel branches of the DWC are equal. For liquid splitting it is not difficult to control because we have so many control valves to control liquid flow. New model was developed for simulation of DWC by introducing connecting streams in MultiFrac model in Aspen plus soft ware In the present work, for simulation of DWC using commercial software was done to study the feasible vapour split as a function of reflux ratio and liquid -spilt ratio:" Plottirig`Feasible- values of vapour split at different reflux ratios and liquid split ratios. Results revealed, some interesting facts like no effect of liquid split ratio on the feasible vapour_ split ratio and significantly different pressure profiles in two sides of the DWC. Also, it was- observed that variation in vapour flow rate leads to drastic change in concentration profile. These indicate that consideration of pressure drop should be the central theme for optimal design and control of a DWC. Also studied two different feed conditions i.e. super heated feed and saturated liquid: feed for DWC; results revealed that there is effect on profiles for_Variation of pressure drop in two column segments with inlet vapour flow rate.