Process intensification Operating plant

Globalization creates a need to source complex products with a high degree of consistency across the world [291], This, in turn, demands a well-defined and transferable process technology. A massive, local customization requires product availability in great variety close to the customer, demanding process intensification, modular operations, transportable plant, and fast response and product changeover. Multifunctionality demands a wider space in formulations and a chemistry set to deliver dial-in fimctionality , which needs assembly from a consistent set of basic materials. 

Heat transfer has been identified by Rlay 13 as an important area in which process intensification is expected to offer major benefits in terms of energy efficiency, pollution control and plant operating costs. So-called passive techniques including modifying the walls of a plant unit, for example, are routinely used to improve heat transfer coefficients in... 

There is no doubt that the ultimate development of process intensification leads to the novel field of microreaction technology (Figure 1) (7-9). Because of the small characteristic dimensions of microreaction devices, mass and heat transfer processes can be strongly enhanced, and, consequently, initial and boundary conditions as well as residence times can be precisely adjusted for optimizing yield and selectivity. Microreaction devices are evidently superior, due to their short response time, which simplifies the control of operation. In connection with the extremely small material holdup, nearly inherently safe plant concepts can be realized. Moreover, microreaction technology offers access to advanced approaches in plant design, like the concept of numbering-up instead of scale-up and, in particular, the possibility to utilize novel process routes not accessible with macroscopic devices. 

Innovation is the key issue in today s chemical process industries. The main directions are sustainability and process intensification. Sustainability means in the first place the efficient use of raw materials and energy close to the theoretical yields. By process intensification the size of process plants is considerably reduced. The integration of several tasks in the same unit, as in reactive separations, can considerably simplify the flowsheet and decrease both capital and operation costs. 

However, the integration of PIM also creates synergy in the development of intensified processes, novel product forms, and size dependent phenomena, which in turn provides novel intensified processes. Process intensification-miniaturization is seen as an important element of sustainable development because it can deliver 1) at least a 10-fold decrease in process equipment volume 2) elimination of parasitic steps and unwanted by-products, thus eliminating some downstream processing operations 3) inherent safety because of reduced reactor volume 4) novel product forms 5) energy, capital, and operating cost reduction, and an environment friendly process 6) plant mobility, responsiveness, and security and 7) a platform for other technologies. 

Process intensification (PI) offers several opportunities to improve energy efficiency and reduce environmental impact [92]. Many chemical reactions currently carried out as batch processes in stirred tanks could be carried out in continuously operated, intensified reactors such as spinning disc or oscillatory baffle types. The plant used for separations can be made highly compact, and even for large-scale plants (nitric acid production) the concept of pocket-sized plant has been introduced to reduce energy needs in the process [93]. PI is thus a key element... 

Undoubtedly, this new kind of integrated approach is well representative of what should be membrane engineering, with final objectives clearly defined, the right hypothesis and choice of simple equations for modeling, a realistic representation of real complex solutions and the set-up of efficient simulation tools involving successive intra- and extrapolation steps. It appears to be easily extended to other membrane operations, in other fields of applications. It should provide stakeholders with information needed to make their decision costs, safety, product quality, environment impact, and so on of new process. Coupled with the need to check the robustness of the new plant and the quality of final output, it should constitute the right way to develop the use of membranes as essential instruments for process intensification with industrial units at work. 

The small reactor volumes and the flexible arrangement of microstructured devices can be applied to design multipurpose plants, and traditional batch and semibatch reactors can be replaced. A considerable process intensification and enhanced product selectivity and yield have been shown [20]. Furthermore, continuous reactor operation may help in providing consistent product quality. 

Fractionation of liquid mixtures with supercritical carbon dioxide in counter-cur-rent columns can be operated continuously, because liquids can be easily pumped into and out of a column. This represents a big advantage over extrachon from solid materials, as it allows real process intensification - large quantities of feed can be processed with only a small volume under high pressure at any given time. Frac-tionahon, mostly of natural products or extracts, has been extensively studied at the laboratory and pilot-plant scale. The design principles of this type of column have been established, and scale-up procedures devised [1,6]. They can be operated with reflux, as in distillation, and frachonahon can therefore become an extremely se-lechve process. Difficult separahons can be effechvely carried out. 

The last chapter gives a more comprehensive approach and discusses the role of membrane gas separation and membrane engineering in the re-designing of industrial applications in terms of new, recently introduced metrics. It provides an analysis of some processes for hydrogen production/separation that can be easily extended in other separation processes. This is a useful tool for the evaluation of pros and cons during the design phase of a new plant, where the membrane operations would replace traditional ones to pursue the strategy of process intensification. 

This case study report deals with the production of fine chemicals. This summary of the appUcation is based on a previous publication by Kirschneck and Tekautz [21]. The basic aim of the project was to enhance the capacity of an existing plant by process intensification and by switching to a continuous plant operation. An additional benefit should be gained by less reaction volume in continuous operation mode, as one of the educts is strongly toxic. Microreaction technology was a most promising technology to fulfill these aims. 

The historical aspects of heat and mass transfer enhancement, or intensification, are of interest for many reasons. We can examine some processes that were intensified some decades before the phrase process intensification became common in the process engineering (particularly chemical) literature. Some used electric fields, others employed centrifugal forces. The use of rotation to intensily heat and mass transfer has, as we wiU see, become one of the most spectacular tools in the armoury of the plant engineer in several unit operations, ranging from reactors to separators. However, it was in the area of heat transfer - in particular two-phase operation - that rotation was first exploited in industrial plants. The rotating boiler is an interesting starting point, and rotation forms the essence of PI within this chapter. 

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