Process intensification, definition

Stankiewicz and Moulijn extend the definition of process intensification from size reduction of apparatus to dramatic improvements in key features of chemical processing [25]. Substantial decreases in the following process-engineering properties are listed ... 

Therefore, in this definition process intensification encompasses both novel apparatus and techniques which are designed to bring dramatic improvements in production and processing (Figure 1.8) [25]. As a result, safe, cheaper, compact, sustainable (environmentally friendly), and energy-efficient technologies are obtained. 

Phillips of the BHR Group, UK, provides a compact definition of process intensification, saying it is ... a design philosophy whereby the fluid dynamics in a process are matched to its chemical, biological and/or physical requirements,. .. [27]. In this way, significant benefits are gained, those listed above. 

Hence chemical micro processing may also be applied for purposes other than PI, e.g. screening, which is not related to production and, accordingly, does not fall into the category of process intensification (see the definition given above). 

Although the scope of this chapter is limited to catalyst nanoencapsulation for the purpose of process intensification, we take a broad view of the definition of nanoencapsulation. The capsule or catalyst, or both, may be on the nanoscale. Additionally, the various methods of nanoencapsulation may be of the order of up to a few microns. 

Both in the paper by Ramshaw and in the report from the UMIST conference, first definitions (or rather descriptions) of process intensification can be found. Ramshaw (11) describes PI as devising an exceedingly compact plant which reduces both the main plant item and the installation s costs, while according to Heggs (12) PI is concerned with order-of-magnitude reductions in process plant and equipment. In one of his subsequent papers, Ramshaw writes about typical equipment volume reduction by two or three orders of magnitude (13). 

Process intensification can be considered to be the use of measures to increase the volume-specific rates of reaction, heat transfer, and mass transfer and thus to enable the chemical system or catalyst to realize its full potential (2). Catalysis itself is an example of process intensification in its broadest sense. The use of special reaction media, such as ionic liquids or supercritical fluids, high-density energy sources, such as microwaves or ultrasonics, the exploitation of centrifugal fields, the use of microstructured reactors with very high specific surface areas, and the periodic reactor operation all fall under this definition of process intensification, and the list given is by no means exhaustive. 

Of course, apart from these general features every process is unique and requires an individual investigation and definition of the cost drivers before one can start a process intensification study. This will be discussed in more detail in the next section. 

Education is a key factor to achieving this new vision, and therefore, together with the definition of roadmaps, it is necessary to spread the concepts of sustainable industrial chemistry to students, scientists and managers in the sector. Even though many books have been published on green chemistry, process intensification and other key elements to implement a sustainable industrial chemistry, we believe that a more global vision of this topic is necessary. 

In the past few years a novel approach to chemical engineering has emerged. This new way of treating processes is called Process Intensification (PI). Although many definitions exist for PI, the main goal is to achieve considerable size reductions in chemical plants. Consequently a smaller plant will lead to improvements in the field of HSE, energy consumption and waste reduction. Recently an overview of PI incentives has been given by Stankiewicz et al.1... 

Within this definition, the field of process intensification is very broad, ft can not be the objective of this chapter to provide an exhaustive overview of the area. Whole conferences are dedicated to process intensification technology every year and networks of experts have been formed, see, e.g.. Ref [1]. Disciplines like mechanical engineering, process engineering, materials science and others all bring exciting new angles and ideas. Rather than attempting to condense the... 

The objectives in this chapter are to build upon the earlier definition of process intensification given in the introduction, via examples and to discuss the advantages of and obstacles to PI. The chapter also signposts the principal unit operations, the PI type(s) used to improve them, and the potential applications. 

One of several definitions of process intensification (PI) sets out a selection of these themes, all of which have already been identified in the introduction ... 

Process intensification (PI) may be defined in a number of ways. The chemist or chemical engineer will appreciate the two-part definition used by one of the major manufacturers of PI equipment ... 

Often when examples are given for process intensification, at first there are only examples in which it is possible to combine several unit operations in one piece of equipment The fact that process intensification is more complex than this is clarified by the definition by Stankiewicsz and Moulijn (2(XX)) Process intensification is any chemical ei ineering development that leads to a substantially smaller, cleaner and more energy-efficient technology ... 

In this chapter, the process intensification has been presented from a chemical engineering perspective. It shows the tremendous scope for industrial applications in this area. After examining the reported definitions and classifications of PI, an attempt has been made to suggest a classification methodology based on multifunctionality, novelty in devices, and alternate-configurations. 

The foregoing indicates that the ideal process characteristic for the application of intensification is that the reaction or phase change kinetics should be as fast as possible. If we regard the H2/O2 rocket motor as a chanical reactor, its performance is very definitely limited by heat and mass transfer considerations. Nevertheless the very fast combustion kinetics allows residence times of several milliseconds and... 

---