A thermo-hydraulic approach to conceptual design of an internally heat-integrated distillation column (i-HIDiC)

This paper introduces an effective method for the conceptual design of internally heat-integrated distillation columns (i-HIDiC). In i-HIDiC, the two column sections are operated at different pressures. The column configuration uses internal heat transfer on column trays between the different sections for heat integration, i.e. they are heat-integrated pressure swing distillation. The new method is based on stage temperature profiles and hydraulic calculations. The paper proposes a tool to assess the feasibility of design and operation of columns combining both the thermodynamic and hydraulic (physical space) capacities. An algorithm is suggested by which the stage temperature profiles are obtained and the pinched stages are identified. Thus, various feasible alternatives for i-HIDiC can be achieved. The work also introduces new terms which are useful for i-HIDiC designs and evaluation of column configurations. Finally, a model, based on hydraulic calculations and geometry analysis, is developed in order to quantify the capability of a column design for heat transfer areas. The model equations can be used in conjunction with commercial software, such as ASPEN+, in order to optimise basic designs for i-HIDiC.