Total Site Analysis as a Synthesis Model to Select, Optimize and Integrate Processes in Multiple-Product Biorefineries

The paper presents a new approach to apply Total Site Analysis (TSA). The incentives of this work originate in biorefineries, where numerous alternative processing routes are possible to get integrated in new plants. The fact that energy targets in Total Sites are exclusively estimated using the graphical tool of Site Sources and Sinks Profiles (SSSPs) as well as that TSA assumes fixed processes in integration procedure causes significant limitations in new applications. The problem requires the re-development of conventional TSA approach into a synthesis tool to systematically evaluate the energy targets of numerous alternative process combinations rather than solely estimate steam savings of given process portfolios. Given a set of candidate processes - possible to get integrated with an existing plant or across a new one - the conventional approach would require the exhaustive use of SSSPs to estimate steam savings of each potential process combination. Instead, the proposed approach introduces a new representation to combine thermodynamics of Total Site integration with mathematical programming and systematically screen the infinite process combinations. As a result, the processes portfolio that improves steam savings and minimizes energy cost can be detected. The proposed model was used for the development of a real-life biorefinery yielding in structures with 9 % and 14 % lower hot and cold utility demands, respectively, compared with the solution obtained by using SSSPs.