Comparison of Capacity Expansion Strategies for Chemical Production Plants

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.