Innovative mapping method for screening reactive distillation designs

Reactive distillation (RD) technology offers key benefits in many chemical processes, including energy savings and costs reduction. Prior to its application in industry, screening, addressing technical feasibility and economic viability, must be performed at the conceptual design level. But these tasks can be challenging and time-consuming since detailed models are usually needed. To overcome this complexity, we provide a mapping method to quickly assess the applicability of RD. The mapping method overlays key parameters of a real system, i.e. relative volatilities (α) and chemical equilibrium constant (K_eq), onto pre-calculated graphs indicating the RD performance, i.e. the reflux ratio (RR) vs number of theoretical stages (NTS) based on generic cases. The mapping method focuses on quaternary systems (A + B ⇌ C + D). A case study (methyl lactate hydrolysis) is used to demonstrate the approach. Three scenarios are presented, applying different characteristic volatility values; each scenario gives rise to a different RD applicability map for equilibrium constants in the range 0.01 to 10. The findings are validated against results of rigorous process simulation and optimisation. The most accurate scenario is that in which α sets are calculated for mixtures with molar compositions 99% C / 1% A, 50% A / 50% B, 1% B / 99% D, respectively. The results show that the mapping approach allows the prediction of number of theoretical stages and reflux ratio to be estimated within 10% of the optimum values.