Chapter 5 - Distillation of Bulk Chemicals

Abstract

This chapter discusses various aspects of the distillation of bulk chemical processes—that is, distillation columns with diameters of 6ft (2m) and larger. These large columns form the basis of all separations in state-of-the-art industrial (petro-) chemical plants. Competitive world-scale plants require hydraulically balanced (high-capacity) column internals that can be reliably scaled over several orders of magnitude in capacity. The design of such industrial columns requires attention to negative performance factors that are less well defined, such as foaming, wetting, polymerization/fouling, scaling, or entrainment. These factors often change over time and relate to catalyst aging or the handling of different feed-stocks. Chemical distillation processes must account for high turndown or complicated chemical interactions stemming from the nonideality of the components to separate, such as the presence of salts. The removal of trace components to produce high-purity products also requires nonstraightforward distillation process configurations. These topics are illustrated by means of distillation column internals layouts in actual industrial process plants. The first part of this chapter describes generic issues related to the design of distillation column internals in chemical process plants. In the second part, it will be shown how these translate to specific design aspects for the column internals of existing industrial processes; issues relating to unit operation lineup, column operation, configuration, integration, and design will be considered.