Multifunctional heat exchanger

Ferrouillat, S., Tochon, P., Della Valle, D., and Peerhossaini, H. (2006a) Open loop thermal control of exothermal chemical reactions in multifunctional heat exchangers. Int.J. Heat Mass Transfer., 49 (15-16), 2479-2490. 

Compact Multifunctional Heat Exchangers A Pathway to Process Intensification... 

In the first part of this paper, the different technologies of compact heat exchangers are presented and their range of application is given. The second part presents the state of the art for heat transfer and fluid flow characteristics for single-phase, evaporation, condensation, and heat and mass transfer. The last part presents applications of compact multifunctional heat exchangers. 

Ferrouillat, S., Tochon, R, Gamier, C. and Peeerhossaini, H. (2006). Intensification of heat transfer and mixing in multifunctional heat exchangers by artificially generated stream-wise vorticity. Applied Thermal Engineering, Vol. 26, pp. 1820-1829. 

Case SP Shell International Chemicals—PDC Bulk Chemical Process Design (37). This new process design consists of a multifunctional reactor, which largely combines reaction, heat exchange, and component separation in one piece of equipment. Data on energy and cost element reductions are provided. 

The above considerations indicate that, independent of implementation details, the space-time yield of endothermic reactions could be significantly enhanced by shifting the reaction site to the heat-exchanging surfaces. This intention has led to the production of a large variety of multifunctional reactor concepts for coupling endothermic and exothermic reactions. In the following section the state of the art in this area will be discussed for selected examples. 

In addition to the well-established fixed-bed reactor configurations mentioned above, new concepts are being discussed where specific features like educt addition and selective product removal are integrated in the fixed bed. From these multifunctional reactors , autothermal reactor concepts where the heat exchange between the cold feed and the hot effluent is integrated in the fixed-bed have already been established in industrial practice. 

The cleaning of flue gases from stationary sources is another field in which the application of monolithic catalysts will certainly rise. There will be no versatile catalyst for cleaning all off-gases. Therefore tailor-made catalysts with zeoliths of various types for specific applications will be developed. Incorporated-type monolithic catalysts are likely to prevail in this field. Since cleaning usually requires a set of equipment items in series (e.g., converter, heat exchangers), multifunctional reactors (reverse-flow reactors, rotating monoliths) will become more common. 

These rules of thumb are organized by prime function, and within each function are listed the usual types of equipment. Some equipment is multifunctional. For example, a fluidized bed is primarily a device for mixing a gas-sohd mixture. However, it is also used as a dryer, a heat exchanger, a reactor, and an agglomerator. 

Several authors have shown the industrial profit in the development of chemical engineering equipment based on the integration of different functions in a single device (Taylor et al., 2000 Stankiewicz et al, 2000). Multifunctional reactors are processes that combine reaction with other operations like heat exchange or separation in order to enhance chemical conversion. Reactive distillation is certainly one of the most significant example. It presents several benefits (such as reduction of energy consumption, overcome of the limitation of the thermodynamic chemical equilibrium, limitation of side reactions, decrease of waste production) and it is applied in various... 

In these multifunctional processes, heat transfer and mass transfer are two combined and simultaneous functions, and the objective is to substantially improve these functions in order to save energy, to increase the process efficiency, and to reduce the size and cost of industrial plants. Corrugated pads are often used in the dehumidification process or in chemical heat pumps, but a higher efficiency could be reached by using diabatic units, where the wall could exchange heat with the liquid film. 

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