Thermodynamics integrated process design

Distillation remains the most used separation method, but is penalised by low thermodynamic efficiency in stand-alone operation. Therefore, energy saving in distillation is a priority topic in integrated process design. In this subchapter we present a number of techniques that can be applied to improve the energetic efficiency of distillation systems by integration with the whole process. 

To tackle these problems successfully, new concepts will be required for developing systematic modeling techniques that can describe parts of the chemical supply chain at different levels of abstraction. A specific example is the integration of molecular thermodynamics in process simulation computations. This would fulfill the objective of predicting the properties of new chemical products when designing a new manufacturing plant. However, such computations remain unachievable at the present time and probably will remain so for the next decade. The challenge is how to abstract the details and description of a complex system into a reduced dimensional space. 

The transport properties of a material determine the rate at which an initially non-uniform thermodynamic state evolves towards a uniform state over time. For this reason, from an industrial point of view, within the context of equipment or process design, the thermodynamic properties of a fluid often determine the feasibility of what is proposed, whereas the transport properties essentially determine how large the equipment or process unit must be or the time scale of the operation. This essential difference is responsible for the fact that the transport properties have, traditionally, been less emphasized in process design activities. However, as the needs for process integration and energy minimization grow, there is a tendency to examine more carefully the effects of the transport properties on the pocess design. 

This book aims is to treat the most important conceptual aspects of Process Design and Simulation in a unified frame of principles, techniques and tools. Accordingly, the material is organised in five sections. Process Simulation, Thermodynamic Methods, Process Synthesis, Process Integration, Design Project, and covered in 17 Chapters. Numerous examples illustrate both theoretical concepts and design issues. The work refers also to the newest scientific developments in the field of Computer Aided Process Engineering. 

Many opportunities conversely are supported by reversible reactions of QM despite the noted complications. One example includes the synthesis and chiral resolution of binaphthol derivatives by two cycles of QM formation and alkylation.77 The reversibility of QM reaction may also be integrated in future design of self-assembling systems to provide covalent strength to the ultimate thermodynamic product. To date, QMs have already demonstrated great success in supporting the opposite process, spontaneous disassembly of dendrimers (Chapter 5). 

The development and application of a rigorous model for a chemically reactive system typically involves four steps (1) development of a thermodynamic model to describe the physical and chemical equilibrium (2) adoption and use of a modeling framework to describe the mass transfer and chemical reactions (3) parameterization of the mass-transfer and kinetic models based upon laboratory, pilot-plant, or commercial-plant data and (4) use of the integrated model to optimize the process and perform equipment design. 

Today, there is an increasing interest in the theoretical study and the practical application of integrated reactive separation processes such as reactive distillation columns [1-3] or membrane-assisted reactors [37]. However, to date there is no general method available for designing such processes. For practical applications, it is important to be able to evaluate quickly whether a certain reactive separation process is a suitable candidate to reach certain targets. Therefore, feasibility analysis tools being based on minimal thermodynamic and kinetic information of the considered system are valuable. 

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