Downstream process synthesis for biochemical production of butanol, ethanol, and acetone from grains

Manufacturing butanol, acetone, and ethanol from the fermentation of grains has been attracting increasing interest. In a production process for these chemicals by fermentation, the cost of product recovery constitutes the major portion of the total cost of the process. Developing cost-effective flowsheets for the downstream processing through synthesis is, therefore, crucial to the enhancement of the economic viability of such a production process, which is the concern of this dissertation.; At the outset, a variety of processing equipment and unit operations, i.e., operating units, is identified for possible inclusion in the process through rigorous analysis or an extensive survey of industrial practices and a meticulous review of technical literature. Subsequently, a set of technically feasible process networks (flowsheets) is generated from such operating units. Eventually, the optimal and near optimal flowsheets are identified among these feasible flowsheets. The rigorous and highly efficient graph-theoretic method for process synthesis adopted in the present work is based on process graphs (P-graphs) devised for process flowsheeting. First, this method constructs algorithmically the maximal structure of the process of interest; the maximal structure is the rigorously defined super-structure with minimal complexity. This is followed by an exhaustive, algorithmic generation of the solution structures corresponding to the combinatorially feasible flowsheets. Finally, the optimal and near-optimal flowsheets are identified among these combinatorially feasible flowsheets in terms of the cost.; This dissertation presents the first successful attempt for the algorithmic synthesis of globally optimal as well as near-optimal flowsheets for downstream processing in the biochemical production of organics. The results obtained have given rise to a highly efficient approach for process retrofitting; a systematic methodology for planning or scheduling process development; and a novel paradigm for process development through process synthesis.