(271d) Synthesis, Design and Analysis of Downstream Separation in Chemical and Bio-Processes

In the synthesis of downstream separation of chemical and bio-processes one determines the type of separation operations and their sequence while in the design problems one determines the optimal values for the conditions of operation and other operation/equipment related variables. Different methods (knowledge-based, mathematical programming, hybrid, etc) have been employed in the past to solve these problems. d’ Anterroches (2005) proposed a process-group based approach to solve the synthesis/design problem of chemical processes. The main idea here was to apply the principle of group-contribution approach from chemical property estimation to the synthesis and design of chemical process flowsheets. That is, use process groups representing different unit operations (reactor, distillation, flash, crystallization, etc.), bonds representing streams and/or recycles, rules for chemical feasibility also representing process flowsheet feasibility and sum of group contributions representing the performance of the flowsheet.

In this proposed paper, the new version of the process groups based approach to systematically model, synthesize/design and analyze downstream separation processes of chemical and bio-processes will be presented. In order to represent many process unit operations, an extended set of process groups has been developed. Among the new process groups, the solvent based separation process group to perform the separation of azeotropic mixtures by means of ionic liquids as entrainer together with its corresponding property model and parameters have been included. Other process groups include organic-solvent based separation of azeotropic mixtures, liquid-liquid extraction, bioreactor process groups and many more. Several case studies will highlight the new process group based methodology. As first case study, the downstream separation alternatives for bioethanol production will be highlighted (250 alternatives were generated and analyzed to find the optimal). In the second case study, the bioroute and recovery of succinic acid will highlight the use of the fixed conversion bioeactor and liquid-liquid extraction process groups. Finally, within the biorefinary concept, the integration of the bioethanol and succinic acid production processes will be illustrated through the process-group based approach in order to identify the best process flowsheet in terms of energy consumption as well as economic competitiveness for the production of these chemicals. Also, through the integration of bioethanol and succinic acid production processes, the production of a third chemical namely, diethyl succinate was identified. The downstream separation process for the diethyl succinate production process will also be illustrated through the process-group based approach.

d’ Anterroches, L., 2005, Process Flow Sheet Generation & Design through a Group Contribution Approach. PhD Thesis. Technical University of Denmark.