Comparison of capacity expansion strategies for chemical production plants

[Display omitted] •Framework to determine the best strategy for an equipment-wise capacity expansion.•Comparison of equipment- and line-wise capacity expansions to conventional design.•Case study reveals TCIinitial reduction and absolute profit increase by step-wise capacity expansion.•Numbering-up often leads to gaps in operating window.•Large operating window enables numbering-up without gap in operating window. Changing market conditions and production requirements in chemical and biochemical industry force engineers to depart from conventional plant design. Adaptability to the market demand, a reduced investment risk and a shorter time-to-market are gaining importance besides technical excellence. A reduced investment risk and an increased adaptability can be achieved by designing smaller plants and use step-wise capacity expansions. The use of modules offers the possibility to reduce the time-to-market. This work introduces an approach to determine the best expansion strategies for modular equipment-wise capacity expansions and compares its results to line-wise capacity expansion strategies and to a conventionally designed plant for a given market demand development using a detailed process simulation. In a case study, the modular equipment-wise expansion strategy offers a 30% lower initial investment risk while increasing the absolute profit up to 40%, although the overall investment increased up to 40% compared to the conventional design. Additionally, an approach to design reactor modules with a larger operating window is proposed and compared in light of an equipment-wise capacity expansion strategy. Two final key statements to exploit the full potential of an equipment-wise capacity expansion are: (a) the determination of operating windows based on process-technological and mechanical operating constraints is a necessity and (b) equipment modules need to be designed for a large operating window to offer a capacity expansion by numbering-up without a gap in the operating window.