Total Site Integration as a Process Synthesis and Scheduling Tool in Multiple-feedstock Biorefineries
Pyrgakis K., Kokossis A.
Computer Aided Chemical Engineering, 40, pp. 1825-1830, 2017
Total Site Integration; Process Synthesis; Process Scheduling; Lignocellulosic biorefineries; Biomass seasonality
This paper presents new systems representations to assess, integrate and optimize biomass valorization paths in multiple-product biorefineries. Biorefinery portfolios are generated through value chain paths, which include all feasible biorefining routes from biomass to intermediate and end-products. Once the problem requires minimum energy cost to improve sustainability, Total Site integration is called to estimate steam targets in sites of fixed/known processes. Since biorefinery processes are not known beforehand, integration is re-stated as a synthesis tool to address processes as additional degrees of freedom. The biorefinery synthesis and integration problem requires the combination of Total Site thermodynamics with mathematical programming. A Total Site transshipment representation is introduced to simultaneously model direct and indirect integration. A biomass representation is proposed to map synthesis options along value chains and address biomass seasonality with the inclusion of variable biomass varieties and technologies to integrate across biorefinery. Mass and energy balances of representations are constructed as an optimization tool to schedule multiple-feedstock operations and select biorefinery processes that minimize annual energy cost.