Capital and total cost targets for mass exchange networks - Part 2: Detailed capital cost models

This part of the paper builds on the developments of Part 1. It starts by d eveloping a targeting method for tray columns using detailed capital costin g methods. The number of units, column diameters and tray spacings, and the distribution of units and trays will all be considered. The limitations of stages targeting are also discussed, leading to an;explanation of why stag es targets may be beaten, and showing how continuous contactors are more an alogous to heat exchangers than stagewise contactors. A procedure for deter mining capital cost targets for networks of continuous contactors (usually packed columns) is then developed. Networks featuring different exchanger s pecifications are also dealt with. As before, capital cost targets are comb ined with operating cost targets to give total annual cost targets. The des ign of networks to meet the targets is then discussed. Systems featuring si gnificant differences in exchanger specifications may require some deviatio n from ideal (vertical) driving force use. The examples presented in this p art of the paper demonstrate that the targets are accurate enough for preli minary design as well as pre-design optimisation. The work in both parts of this paper reduces the amount of design work required when evaluating proc esses at the conceptual stage. (C) 2000 Elsevier Science Ltd. All rights re served.