Structured reactors advantages

It has also been recognized that micro-structured components, because of their low mass and thermal inertia, are able to offer short response times for unsteady state periodic operations. Micro-reactors have been used successfully for fluorination, oxidations and both heterogeneous [63-65] and homogeneous hydrogenations [66]. A review on gas-liquid micro-structured reactors has been published [67]. The very small material inventory when using micro devices offers another advantage, notably as a laboratory tool for screening applications, kinetics determination and process data acquisition, where the main concern is... 

In a microstructured reactor plant, in contrast, the flow rate will be dominated by the pressure loss. Typical pressure losses in micro devices are of the order of 1 bar at a flow of 11 h 1 (water) [50,93], If sufficient pump capacity is available, the pressure loss in a micro structured device is limited by the mechanical stability of the reactor housing, which is often made of steel and hence a loss of several bar is certainly acceptable. Even the combination of up to 10 different micro devices only amounts to about 10 bar in this example. The main advantage of a micro structured reactor plant is that the flow rate can be adjusted more freely because the flow is pressure driven and not influenced by a single gravity-driven device as in a miniplant. 

New reactor types for three-phase operation are still being developed. An example is the application of structured reactors, which may have certain advantages in three-phase operation, and can be operated with co-, cross- as well as with countercurrent flow. A very recent development is the use of monolith reactors (Fig. 8.9) in three-phase operations. Their advantages are the small pressure drop, the good external mass transfer, the short diffusion distance, and the low adiabatic temperature rise. Disadvantages are the higher catalyst costs, importance of liquid distribution, and moderate catalyst load. 

The use of an already prepared support or catalyst (or perhaps even one that is commercially available) to coat structured reactors or packings has several advantages. A commercial catalyst is optimized for a particular reaction, and the effort of catalyst development can be shortened or even avoided. The only requirement is the development of an adequate coating procedure. 

Monoliths and microchannel reactors (MRs) are two of the different types of structured reactors. A thin layer of catalyst deposited on stiff 3D structures with channels or macro-pores and high lateral surface is characteristic of these catalytic devices. These structures overcome flow maldistribution, high pressure drop, and diffusional limitations in the pores that are frequently associated with the conventional packed-bed reactors (PBRs) commonly used for catalytic reactions. Compared with PBR, structured reactors have unquestionable advantages not only in lowering pressure drop and decreasing flow maldistribution, which... 

Novel reactor configurations are discussed in terms of micro and monolith reactors. Examples of gas and liquid phase reactions and appropriate reactor configmations and process details are presented with a focus on PI. Structured reactors are discussed with their advantages compared to conventional reactors. Process aspects of monolith reactors including their applications in some industrially important reactions are discussed. A brief mention is made about novel devices for heat, mass and momentum transfer. The achievement of PI... 

Structured reactors such as monoliths have several obvious advantages over the traditional reactor randomly filled with catalyst particles [1]. They have lower pressure drop, uniform flow distributions, less hot-spot formation and uniform residence times. However, these catalytic systems have low surface areas, making it necessary to incorporate some phase like alumina or silica, which increases the surface area. 

Ultra-High Vacuum Reactors. CVD reactions at extremely low pressures (i.e., 10 Torr) are being developed for the deposition of semiconductor materials, such as silicon-germanium and some optoelectronic materials. Advantages appear to be better control of the deposit structure and reduction of impurities. 

The vertical reactor simulations reported In this paper typically Involved 14,000 unknowns and took 25 CPU seconds per Newton Iteration on a Cray-2. The tracing of a complete family of solutions for one parameter (e.g. susceptor temperature) cost approximately 25 CPU minutes. The latter number underscores the advantage of using supercomputers to understand the structure of the solution space for physical problems which often Involve many parameters. 

While having some advantages over riser reactors, downer reactors also suffer fixrm some serious shortcomings, such as a low solids holdup in the bed, difficulty in even distribution of injected residual on the catalysts, and a high sensitivity to the structure of the inlet [11,12]. Therefore, the development of a new coupled CFB reactor that can fully utilize the advantages of the riser and the downer is of interest. 

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