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 developing a targeting method for tray columns using detailed capital costing 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 stages targets may be beaten, and showing how continuous contactors are more analogous to heat exchangers than stagewise contactors. A procedure for determining capital cost targets for networks of continuous contactors (usually packed columns) is then developed. Networks featuring different exchanger specifications are also dealt with. As before, capital cost targets are combined with operating cost targets to give total annual cost targets. The design of networks to meet the targets is then discussed. Systems featuring significant differences in exchanger specifications may require some deviation from ideal (vertical) driving force use. The examples presented in this part of the paper demonstrate that the targets are accurate enough for preliminary design as well as pre-design optimisation. The work in both parts of this paper reduces the amount of design work required when evaluating processes at the conceptual stage. (C) 2000 Elsevier Science Ltd. All rights reserved.