Process intensification equipment

Figure 1.28 Illustration of a future plant using process-intensification equipment, aiming at giving the corresponding shape or perception. Compared with today s plants, a reduction in size is predicted [25].

Eurther examples and concepts are discussed in the following sections, but already this introduction evidences the possibilities and opportunities for a sustainable industrial chemistry that derive from the application of process intensification equipment and methodology. 

Static mixers are perhaps the simplest and most versatile of process intensification equipment, with application in reactions where at least one phase is a liquid. They are tube inserts that use the pumping energy/pressure drop to induce mixing and can be roughly divided into three categories ... 

Amalgamated Research is a process research and development company. It specialises in fluid handling and distribution, but an example of the process intensification equipment offered is the patented fractal ion exchange system. 

The term process intensification is used synonymously with minimization. Process intensification is also often used more specifically to describe new technologies which reduce the size of unit operations equipment, particularly reactors. Innovative process intensification techniques are receiving more and more attention. Interesting possibilities for a range of unit operations, including reaction, gas-liq-... 

Elgue, S., Ferrato, M., Momas, M., Chereau, P., Prat, L, Gourdon, C., and Cabassud, M. (2007) Silicon carbide equipments for process intensification first steps of an innovation. 1st Congress on Green Process Engineering, April 24-26, 2007, Toulouse. 

Minimization goes much further than storage, however. For many processes the largest inventory of hazardous materials is in the reactor. If, through radical reactor design, inventories and equipment size can be reduced whilst throughput is maintained, then this presents opportunities for improved safety and possibly reduced capital costs. This is the concept behind Process Intensification which is discussed more fully below. 

Figure 1.8 Branching of process intensification into engineering methods and corresponding equipment [26],...

As examples of micro-channel process intensification and the respective equipment, in particular gas/liquid micro reactors and their application to toluene and various other fluorinations and also to carbon dioxide absorption can be mentioned [5]. Generally, reactions may be amenable to process intensification, when performed via high-temperature, high-pressure, and high-concentration routes and also when using aggressive reactants [5]. 

In practice, the process regime will often be less transparent than suggested by Table 1.4. As an example, a process may neither be diffusion nor reaction-rate limited, rather some intermediate regime may prevail. In addition, solid heat transfer, entrance flow or axial dispersion effects, which were neglected in the present study, may be superposed. In the analysis presented here only the leading-order effects were taken into account. As a result, the dependence of the characteristic quantities listed in Table 1.5 on the channel diameter will be more complex. For a detailed study of such more complex scenarios, computational fluid dynamics, to be discussed in Section 2.3, offers powerful tools and methods. However, the present analysis serves the purpose to differentiate the potential inherent in decreasing the characteristic dimensions of process equipment and to identify some cornerstones to be considered when attempting process intensification via size reduction. 

This class is the simplest of all micro reactors and certainly the most convenient one to purchase, but not necessarily one with compromises or reduced fimction. HPLC or other tubing of small internal dimensions is used for performing reactions. There are many proofs in the literature for process intensification by this simple concept. As a micro mixer is missing, mixing either has to be carried out externally by conventional mini-equipment or may not be needed at all. The latter holds for reactions with one reactant only or with a pre-mixed reactant solution, which does not react before entering the tube. 

Several technological responses to these emerging trends can be gathered under the umbrella of process intensification. This term encompasses a wide range of methods and equipment for performing chemical processing steps more quickly and compactly, thereby increasing the... 

From the very beginning, continuous reactor concepts, an alternative to the truly microfabricated reactors, were used, for example, static meso-scaled mixers or HPLCs and other smart tubing (see Iwasaki et al. 2006 for an example). This completed functionality by filling niches not yet covered by microfabricated reactors or even by replacing the latter as a more robust, more easily accessed or more inexpensive processing tool. Further innovative equipment, coming from related developments in the process intensification field, is another source e.g., structured packings such as fleeces, foams, or monoliths. 

The concept of process intensification does not need to apply to the whole of an API production process. There is merit in looking at hybrid reaction schemes, which retain the benefits of, or capital investment in, batch equipment but use continuous processes for the generation of hazardous intermediates [17] or for certain unit processes. Of these, hydrogenation [18], filtration [19], phase separation [20], crystallisation [21] and drying [22] are good examples. 

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). 

The philosophy of process intensification has been traditionally characterized by four words smaller, cheaper, safer, slicker. And indeed, equipment size, land use costs, and process safety are among the most important PI incentives. But process intensification can (and should) also be placed in a broader context—the context of sustainable technological development. Several years ago DSM published a picture symbolizing its own vision of process intensification (32), in which skyscraping distillation towers of the naphtha-cracking unit are replaced by a compact, clean, and tidy indoor plant (see Figure 3). The importance of PI for sustainable development and its role in the company s responsible business has been further stressed in a recent publication by the company s CEO, Peter Elverding (33). Here,... 

The toolbox for process intensification is schematically shown in Figure 7. It includes process-intensifying equipment (PI hardware) and process-intensifying methods (PI software). Obviously, in many cases overlap between these two domains can be observed as new methods may require novel types of equipment to be developed and, vice versa, novel apparatuses already developed sometimes make use of new, unconventional processing methods. In Figure 7, examples of both PI hardware and PI software are shown. Many of them will be discussed in detail in other chapters of this book. Here, we give only a brief overview of the more important PI items. 

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