Simultaneous Process Network Synthesis and Process Intensification Using Block Superstructure
Jianping Li (1), Salih Emre Demirel (1), M.M. Faruque Hasan (1)
1. Artie McFerrin Department of Chemical Engineering, Texas A&M University,College Station, TX 77843-3122, USA.
Process synthesis is used in obtaining the best processing route among many alternatives by assembling units into a process network with the goal of optimizing either economic, environmental, and/or social objectives. Current optimization-based process synthesis methods are unable to automatically construct and identify novel intensified equipment as they require pre-specified equipment configurations. Furthermore, whenever a new problem is addressed, a different superstructure needs to be postulated. To address these challenges, we propose a new block-based superstructure instead of classical unit-operation based one. Each block represents a unit use of materials with a specific function (reaction, separation, storage). The existence of connecting streams between adjacent blocks and jump flows among all blocks enables the necessary interactions between different blocks via material and energy flows. An assembly of the same blocks results in a classical unit operation, while intensified units are realized with assembly of multiple different blocks. This allows a systematic identification, representation and generation of intensification alternatives at the flowsheet level without a priori postulation of their existence. The proposed approach not only identifies different process equipment, but also automatically generates the corresponding flowsheet. We pose the unified synthesis and intensification problem as a mixed-integer nonlinear optimization (MINLP) problem. 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 also demonstrate that the simultaneous synthesis and intensification approach leads to substantially smaller, cleaner, safer, and more energy-efficient designs.
Keywords: Process Synthesis, Process Intensification, Process Integration