(430f) Toward a Unified Method for Process Design, Integration and Intensification

Authors: 
Demirel, S. E., Artie McFerrin Department of Chemical Engineering, Texas A&M University
Hasan, M. M. F., Artie McFerrin Department of Chemical Engineering, Texas A&M University
Li, J., Artie McFerrin Department of Chemical Engineering, Texas A&M University
Until now, process synthesis and integration methods have focused on classical unit operations, where units such as separators, reactors and storage tanks are integrated but they are not merged to perform multiple tasks in situ. Due to the historically standalone development of conversion, separation and storage technologies, excess energy is consumed in isolated units. In this work, we propose an original approach for process design that leverages on the construction of flowsheets using building blocks, where each block performs specific operation (e.g., separation, conversion, storage, etc.) via enabling materials (e.g., membrane, catalyst, adsorbent, etc.). An assembly of blocks of the same type obtains a classical unit, while an assembly of blocks with different types results in a hybrid or intensified unit. Our building block-based flowsheet superstructure not only contains all alternatives typically considered for process synthesis and integration, but it also systematically identifies and incorporates all plausible intensification alternatives at the flowsheet level. To this end, our proposed method can potentially lead to a unified approach for process synthesis, integration and intensification without exhaustive enumeration. The overall problem is formulated as a single mixed-integer nonlinear optimization (MINLP) problem which can be solved using commercial solvers. While the mass and energy flows between the blocks are modeled using continuous variables, the selection of the operations and their enabling materials are discrete decisions. The objective is to synthesize a process with intensified units by minimizing or maximizing a process metric given the feed and product specifications, feed and product prices, material properties and bounds on flow rates. We demonstrate the applicability of the proposed method for the innovative design of several emerging technologies for clean and sustainable energy, such as carbon capture and conversion, natural gas utilization, and multicomponent gas separation. We also demonstrate that the simultaneous synthesis and intensification approach leads to substantially smaller, cleaner, safer, and more energy-efficient designs.