Downstream Process Synthesis for Biochemical Production of Butanol, Ethanol, and Acetone from Grains: Generation of Optimal and Near-Optimal Flowsheets with Conventional Operating Units

Abstract

Manufacturing butanol, ethanol, and acetone through grain fermentation has been attracting increasing research interest. In the production of these chemicals from fermentation, the cost of product recovery constitutes the major portion of the total production cost. Developing cost-effective flowsheets for the downstream processing is, therefore, crucial to enhancing the economic viability of this manufacturing method. The present work is concerned with the synthesis of such a process that minimizes the cost of the downstream processing. At the outset, a wide variety of processing equipment and unit operations, i.e., operating units, is selected for possible inclusion in the process. Subsequently, the exactly defined superstructure with minimal complexity, termed maximal structure, is constructed from these operating units with the rigorous and highly efficient graph-theoretic method for process synthesis based on process graphs (P-graphs). Finally, the optimal and near-optimal flowsheets in terms of cost are identified.

Life-cycle assessment of corn-based butanol as a potential transportation fuel.

“…For the second half of the process, including ABE fermentation and downstream processing, the ASPEN simulation was completed on the basis of the research results from a pilot-scale ABE fermentation plant (Ezeji et al 2003 and2004) and from literature (Liu 2003;Liu et al 2004Liu et al , 2006Heckl et al 2006). The production capacity of this plant was set at 150,000 metric tons per year of butanol.…”

“…Data for the simulation of fermentation and gas-stripping unit operations are based on the research results from Qureshi and Blaschek (2000;2001a,b), Ezeji et al (2004), and Ezeji et al (2005). Table 2 summarizes the main parameters for fermentation and gas stripping input to the Aspen Plus The downstream processing flowsheet in the simulation is based on the most costeffective flowsheet rigorously generated from an exhaustive list of plausible processing equipment and unit operations, as described in Liu (2003), Liu et al (2004Liu et al ( , 2006, and Heckl et al (2006). According to their studies, this optimal flowsheet consists of a gas stripper that isolates a liquid product stream from the fermentation broth; an adsorption unit that removes the majority of water; and a set of distillation columns that purifies the butanol, ethanol, and acetone products.…”

“…Solvent production in this process in a fed-batch mode reached 65:35:1 of butanol:acetone:ethanol by weight, which is a significant increase in butanol production from 6:3:1 in conventional ABE process. Liu (2003) presents an exhaustive survey of major research findings on ABE downstream processing. Recent studies have focused on integration of fermentation and product removal through in-situ gas stripping and fermentation gas recirculation (Qureshi and Blaschek 2000;Qureshi and Blaschek 2001a;Qureshi and Blaschek 2001b;Ezeji et al 2004;and Ezeji et al 2005).…”

“…In these studies, simulations were used to evaluate the economics of their processes. More recent studies were published in Liu (2003) and Liu et al (2004 and. In these studies, downstream processing systems were synthesized, simulated, and optimized in terms of cost.…”

A Robust Combinatorial Approach Based on P-Graph for Superstructure Generation in Downstream Bioprocesses

“…In the combined method, the physical insights of analysis, the level-by-level strategy of hierarchical design procedure, and the goal-oriented-analysis were introduced to gather all in-process materials; then the idea of phenomena-driven design was combined with the hierarchical decomposition approach, which could guarantee that all correlative operation-units were found; finally, the MSG (maximal structure generation) algorithm was used to generate the maximal structure. The usefulness and accuracy of the new combined method was verified through the separation of butanol (B) (Liu et al, 2004;Liu et al, 2006;Fan et al, 2008) and the purification of penicillin (Swartz, 1985;Steffens et al, 1999).…”