Semicontinuous reactive distillation for specialty chemicals production: Economic comparison with batch and continuous processing

Semicontinuous reactive distillation was introduced as a novel means of integrating reaction and separation operations using a forced-cyclic strategy. Rigorous simulations of equivalent batch, continuous, and semicontinuous designs were analyzed and compared over a range of production capacities. The continuous process used an external CSTR for 2,4-dimethyl-1,3-dioxolane (24DMD) production. Fresh acetaldehyde and propylene glycol were fed to the CSTR in equimolar amounts. The batch process used a fed-batch reactor in parallel with a batch distillation column. For the batch and SRD processes, other parameters affected the production rate, such as the size of each batch and the feed rate to the column. The batch process had the lowest total capital costs for production rates below about 1 million kg/yr of 24DMD, with the SRD process having the lowest capital costs for rates above that value. The batch process is the best choice for production rates below 1 million kg/yr, the continuous process is best at rates above about 4.5 million kg/yr, and the SRD process is the optimal choice for production rates in between. This is an abstract of a paper presented at the AIChE Annual Meeting and Fall Showcase (Cincinnati, OH 10/30/2005-11/4/2005).