Intermediate heat exchange in binary distillation

Doctoral thesis, 2005

Abstract The overall reason for investigating intermediate heat exchange in diabatic distillation is to enable a reduction in external energy demand. This thesis applies computer simulations and experimental measurements to evaluate and analyse the use of intermediate heat exchange in binary distillation. The use of intermediate heat exchange has been studied in a stand-alone distillation unit as a method to improve the energetic performance of distillation. Considerable external energy savings can theoretically be achieved by using different intermediate heat exchange arrangements. The way the intermediate heat exchange is performed in terms of a combination of positions for side stream withdrawal and side stream return has a clear impact on the column performance. In a real column with constant number of trays and constant separation an optimisation of the intermediate heat exchange will generate increased efficiencies locally together with improved separation. Some parts will run closer to reversibility than other parts. A new type of experimental equipment has been constructed to enable pilot plant scale diabatic distillation experiments in both the rectifying section as well as in the stripping section.