Synthesis of Operable Process Intensification Systems—Steady-State Design with Safety and Operability Considerations

Abstract

In this work, we present an integrated approach to synthesize process intensification systems with guaranteed flexibility and safety performances. The synthesis of intensified equipment/flowsheets is addressed through the Generalized Modular Representation Framework (GMF), which utilizes an aggregation of multifunctional mass/heat exchange modules to represent chemical processes. Thus, the optimal design options are investigated as mass- and heat-transfer opportunities using superstructure-based optimization techniques without a prepostulation of plausible configurations. To ensure that the designs can be operated under a specified range of uncertain parameters, a multiperiod GMF representation is developed based on the critical operating conditions identified by flexibility test. Risk assessment, accounting for equipment failure frequency and consequence severity, is incorporated as a constraint into this synthesis model to derive inherently safer designs. The resulting safely operable intensified systems, which are represented via phenomenological modules, are then identified as corresponding equipment-based flowsheets and validated with steady-state simulation. We demonstrate the proposed approach through a case study for the production of methyl tert-butyl ether. The results indicate that safety and operability considerations can result in significant changes in the structural and operating parameters of the optimal intensified design configuration.

Operability and control in process intensification and modular design: Challenges and opportunities

“…Two key questions result from the above framework which also open up more opportunities toward a holistic framework for process intensification and operation: Definition of driving forces to define the optimal operation trajectory — Various driving forces have been defined pertaining to specific types of processes. For example, the previously mentioned elementary process function for reactors, 69 attainable region theory to determine ultimate performance bounds in reaction/separation systems, 70,71 reactive driving force for (reactive) distillation systems, 72,73 Gibbs free energy‐based driving force constraints for reaction/separation systems, 74 and so on. Given the large scope of PI and modular designs, a well‐defined driving force formulation is clearly needed, which may not suggest directly the type of equipment but can rapidly screen the design space and provide preliminary design and operation information (including temporal and spatial profiles). Mathematical formulations — While dynamic modeling and optimization provide accurate descriptions of process systems in both temporal and spatial domains, it is highly demanding (and currently limited) in solution algorithms, problem scales, and computational complexity.…”

“…However, modular design options have not yet been considered in these approaches to evaluate if and how modularization can bring in economic and/or operational benefits in tandem with intensification. In light of this, we take the GMF 35,74 as an example and briefly discuss how it can be extended to represent modular design flowsheet.…”

“…Operability analysis for the phenomena‐based synthesis intensification is kind of challenging since the synthesis is done using abstract phenomena building blocks (e.g., reaction, separation) with no available equipment information (e.g., reactor, membrane). As an attempt for this purpose, Tian and Pistikopoulos 74 applied flexibility analysis with multiperiod design to a methyl tert‐butyl ether reactive separation case study using the phenomena‐based GMF. The flexibility analysis was performed by analogizing each modular building block as a real mass or heat exchanger and then utilizing the flowsheet information on structural layout, stream flowrate, temperature/pressure, pseudo‐sizing estimation, and so on.…”

Towards the Grand Unification of Process Design, Scheduling, and Control—Utopia or Reality?

“…These techniques postulate "superstructures" that systematically simulate and compare every combination of flowsheet possibility to determine the optimal process. More recently, superstructures have been formulated at the phenomena level to capture the fundamental relations between the mass and energy, which in turn yields intensified processes [116][117][118][119][120][121][122]. Such intensified processes are expected to deliver significantly increased operational efficiency and decreased unit volumes, making them very attractive options both in academia and industry [123].…”

Computer‐aided process intensification: Challenges, trends and opportunities

“…Also, as advances are made in tailor‐made material design, new phenomena‐based hybrid operations could be synthesized, for example, improving reactions and separations . However, can new membrane materials totally replace a distillation operation or should hybrid operations be targeted, at least for the short‐term? Wider application: For faster implementation of PI solutions, topics such as process dynamics, control, operability, and safety need to be incorporated. To make a greater impact, it would be beneficial to prepare a list of energy intensive processes where CAPI could be realized with current techniques in the short‐term and where more work would be necessary to achieve the desired improvements in the long‐term.…”