Deenesh Kavi Babi

Sustainable Process Synthesis-Intensification

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New Vistas in Chemical Product and Process Design

Design of chemicals-based products is broadly classified into those that are process centered and those that are product centered. In this article, the designs of both classes of products are reviewed from a process systems point of view; developments related to the design of the chemical product, its corresponding process, and its integration are highlighted. Although significant advances have been made in the development of systematic model-based techniques for process design (also for optimization, operation, and control), much work is needed to reach the same level for product design. Timeline diagrams illustrating key contributions in product design, process design, and integrated product-process design are presented. The search for novel, innovative, and sustainable solutions must be matched by consideration of issues related to the multidisciplinary nature of problems, the lack of data needed for model development, solution strategies that incorporate multiscale options, and reliability versus predictive power. The need for an integrated model-experiment-based design approach is discussed together with benefits of employing a systematic computer-aided framework with built-in design templates.

A computer-aided software-tool for sustainable process synthesis-intensification

Abstract Currently, the process industry is moving towards the design of innovative, more sustainable processes that show improvements in both economic and environmental factors. The design space of unit operations that can be combined to generate process flowsheet alternatives considering known unit operations as well as reported hybrid/intensified unit operations is large and can be difficult to manually navigate in order to determine the best process flowsheet for the production of a desired chemical product. Therefore, it is beneficial to utilize computer-aided methods and tools to enumerate, analyze and determine within the design space, the more sustainable processes. In this paper, an integrated computer-aided software-tool that searches the design space for hybrid/intensified more sustainable process options is presented. Embedded within the software architecture are process synthesis and intensification methods that operate at multiple scales, namely, unit operation, task and phenomena. First a base case process flowsheet (if it is not already available) is generated through process synthesis considering only known unit operations. The generated or supplied base case is then analyzed in order to identify process bottlenecks/limitations ( hot-spots ) that are translated into design targets. Next, phenomena-based synthesis is performed to identify process flowsheets that match the design targets through the use of hybrid/intensified unit operations. As these process flowsheets satisfy all process constraints while also matching the design targets, they are therefore more sustainable than the base case. The application of the software-tool to the production of biodiesel is presented, highlighting the main features of the computer-aided, multi-stage, multi-scale methods that are able to determine more sustainable designs.

Hybrid Distillation Schemes: Design, Analysis, and Application

Abstract Aspects of design, analysis, and application of hybrid distillation schemes are covered in this chapter. Four types of hybrid distillation schemes are considered: pressure-swing distillation, solvent-based extractive distillation, membrane-assisted operation combined with conventional distillation, and reactive distillation with or without non-reactive stages. These hybrid distillation schemes become necessary when specific separation tasks such as separation of azeotropic or close-boiling mixtures cannot be achieved in a single conventional distillation column. Models, methods, and computer-aided tools that may be employed for design, analysis, and application of hybrid distillation schemes are presented together with illustrative examples.Aspects of design, analysis, and application of hybrid distillation schemes are covered in this chapter. Four types of hybrid distillation schemes are considered: pressure-swing distillation, solvent-based extractive distillation, membrane-assisted operation combined with conventional distillation, and reactive distillation with or without non-reactive stages. These hybrid distillation schemes become necessary when specific separation tasks such as separation of azeotropic or close-boiling mixtures cannot be achieved in a single conventional distillation column. Models, methods, and computer-aided tools that may be employed for design, analysis, and application of hybrid distillation schemes are presented together with illustrative examples.

A computer-aided approach for achieving sustainable process design by process intensification

Abstract Process intensification can be applied to achieve sustainable process design. In this paper, a systematic, 3-stage synthesis-intensification framework is applied to achieve more sustainable design. In stage 1, the synthesis stage, an objective function and design constraints are defined and a base case is synthesized. In stage 2, the design and analysis stage, the base case is analyzed using economic and environmental analyses to identify process hot-spots that are translated into design targets. In stage 3, the innovation design stage, phenomena-based process intensification is performed to generate flowsheet alternatives that satisfy the design targets thereby, minimizing and/or eliminating the process hot-spots. The application of the framework is highlighted through the production of para-xylene via toluene methylation where more sustainable flowsheet alternatives that consist of hybrid/intensified unit operations are generated from the application of phenomena-based process intensification.

Achieving More Sustainable Designs through a Process Synthesis-Intensification Framework

Abstract More sustainable process designs refer to design alternatives that correspond to lower values of a set of targeted performance criteria. In this paper, a multi-level framework for process synthesis-intensification that leads to more sustainable process designs is presented. At the highest level of aggregation, process flowsheets are synthesized in terms of a sequence of unit operations that correspond to acceptable values for a set of targeted performance criteria. This defines the upper-bound of the performance criteria and the design is called the base-case design. At the next lower level, tasks representing unit operations are identified and analysed in terms of means-ends to find more flowsheet alternatives that improve the base-case design and correspond to lower values of the set of targeted performance criteria. At the lowest level, phenomena employed to perform the specific tasks are identified and manipulated to find intensified operations, leading to more flowsheets that further improve the base-case design and correspond to even lower values of the set of target performance criteria. An overview of the framework is presented together with a case study that highlights the key concepts and application work-flow.

Fundamentals of Process Intensification: A Process Systems Engineering View

This chapter gives an overview of the fundamentals of process intensification from a process systems engineering point of view. The concept of process intensification, including process integration, is explained together with the drivers for applying process intensification, which can be achieved at different scales of size, that is, the unit operation scale, the task scale, and the phenomena scale. The roles of process intensification with respect to process improvements and the generation of more sustainable process designs are discussed and questions related to when to apply process intensification and how to apply process intensification are answered through illustrative examples. The main issues and needs for generation of more sustainable process alternatives through process intensification are discussed in terms of the need for a systematic computer-aided framework and the methods and tools that should be employed through it. The process for the production of methyl-acetate is used as an example to highlight the generation of more sustainable process alternatives through this framework. Perspectives, conclusions, and future work are proposed in order to further develop the field of process intensification using a systems approach.

Sustainable Chemical Process Development through an Integrated Framework

Abstract This paper describes the development and the application of a general integrated framework based on systematic model-based methods and computer-aided tools with the objective to achieve more sustainable process designs and to improve the process understanding. The developed framework can be applied to a wide range of problems, including the design of new processes as well as retrofit of existing batch-continuous production systems. The overview of the framework together with results from two case studies is presented to highlight the key aspects and the applicability of the framework. These case studies involve multiphase reaction systems for the synthesis of active pharmaceutical ingredients.

Teaching Sustainable Process Design Using 12 Systematic Computer-Aided Tasks

Abstract In this paper a task-based approach for teaching (sustainable) process design to students pursuing a degree in chemical and biochemical engineering is presented. In tasks 1-3 the student makes design decisions for product and process selection followed by simple and rigorous model simulations (tasks 4-7) and then sizing, costing and economic analysis of the designed process (tasks 8-9). This produces a base case design. In tasks 10-12, the student explores opportunities for heat and/or mass integration, followed by a sustainability analysis, in order to evaluate the base case design and set targets for further improvement. Finally, a process optimization problem is formulated and solved to obtain the more sustainable process design. The 12 tasks are explained in terms of input and output of each task and examples of application of this approach in an MSc-level course are reported.

A Systematic Approach to Green Solvent Selection, Design, and Verification

Abstract This chapter presents the systematic approach to solvent selection for various separation processes. First, the problem is defined in the mathematical manner. The technique of computer-aided molecular design is useful in selection of solvents with desired parameters, not only favorable in the context of given process, but also of low environmental impact and high safety of handling. Few solvent selection case studies show that greenness considerations and technological aspects can be successfully combined during separation process design with application of organic solvents or ionic liquids.