(705b) A Novel Model Predictive Control Scheme for Sustainability: Application to Biomass/Coal Co-Gasification System
To fill this gap, a novel model predictive control (MPC) scheme is proposed to drive the system to a sustainable operating point that is defined using a multi-objective optimization algorithm. In particular, the sustainable MPC is formulated based on dimensionless sustainability performance indicators from the U.S. EPAâs GREENSCOPE (Gauging Reaction Effectiveness for the ENvironmental Sustainability of Chemistries with a Multi-Objective Process Evaluator) tool . These established indicators are associated with the process state variables, releases, resource consumption, and products and can capture the sustainability information of the current process condition, including economic, environmental and social aspects. Such sustainability indicators are employed as hard/soft constraints in the implemented controller in order to maintain the process operation within a pre-defined sustainable zone, where the performance indicator values are higher than desired thresholds. To explicitly visualize the multidimensional sustainability indicators during transient, a multivariate plotting method is developed using dynamic radar diagrams.
The developed method is illustrated via a biomass/coal co-gasification process for syngas production with the end goal of methanol manufacturing. For this application, the whole process model is developed in Aspen Hysys based on existing literature information [4-5]. With the established models in Aspen and a link for data communication between Aspen and MATLAB, a multi-objective optimization problem is solved to maximize profit and optimize the process sustainability performance (e.g., environmental release and resource use minimization), by employing a genetic algorithm-based approach developed in MATLAB. In this presentation, the details on the application results of this novel framework for improving sustainability performance are discussed, focusing on the tradeoffs between using coal and biomass for the sustainable production of chemicals. The results show that the proposed sustainable MPC scheme can effectively drive the process to the optimal operating point, while maintaining the process within sustainable zones during transients.
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