Design membrane reactors

Figure 16.15 Examples of the rotating-disc membrane reactor design.

Catalytic membrane reactors represent the most compact and yet challenging membrane reactor design. The membrane material may be inherently catalytic or rendered catalytic by impregnating a catalyst on the surface of the membrane itself or the pores inside the membrane/support matrix. When the inner tube of a shell-and-tul reactor is a permselective and also catalytic membrane, the reactor is called catalytic membrane tubular reactor. Under this special circumstance, ibj = 0 = kf for Equations (10-36) to (10-37) and (10-44) to (10-45), assuming plug flows on both the tube and shell sides. The transport equations for the membrane zone. Equations (10-5) to (10-6), hold. 

In addition to the Navier-Stokes equations, the convective diffusion or mass balance equations need to be considered. Filtration is included in the simulation by preventing convection or diffusion of the retained species. The porosity of the membrane is assumed to decrease exponentially with time as a result of fouling. Wai and Fumeaux [1990] modeled the filtration of a 0.2 pm membrane with a central transverse filtrate outlet across the membrane support. They performed transient calculations to predict the flux reduction as a function of time due to fouling. Different membrane or membrane reactor designs can be evaluated by CFD with an ever decreasing amount of computational time. 

Finally, possible causes for deactivation of catalytic membranes are described and severad aspects of regenerating catalytic membrane reactors are discussed. A variety of membrane reactor configurations are mentioned and some unique membrane reactor designs such as double spiral-plate or spiral-tube reactor, fuel cell unit, crossflow dualcompartment reactor, hollow-fiber reactor and fluidized-bed membrane reactor are reviewed. 

In recent years, various groups have focused their attention on optimizing membrane reactor design aiming to compensate for the relatively low membrane permeability. 

In the early stages of MRs, the two functions were coupled by connecting two distinct units - the reactor and the membrane separator - in series (Figure 2a). The membrane reactor design, shown in Figure 2 (b), which combines both process units into a single one, was the result of the development of the first process design into the second. 

Lopez-Zamora, S. M., Fontalvo, J., Gomez-Garcia, M. A. (2013). Pervaporation membrane reactor design guidelines for the production of methyl acetate. Desalination and Water Treatment. 51, 2387—2393. 

In addition to the membrane performance, the optimal membrane reactor design will have to address the practical aspects of the chosen industrial applications. One important consideration will be the impact of thermal... 

Membrane reactor design with integrated heat management systems and optimal feed flow/catalyst contact with the catalyst placed inside the membranes (Diniz da Costa eta ., 2009). 

To develop a membrane reactor design tool, designers need ... 

Figure 13.19 shows a comparison between the experimental (plots) and simulated (lines) results for Cases 21-23 in Table 13.5, where both conversion and hydrogen permeation rate can be found to be in good agreement. This indicates that the CFD model developed here is valid for analysing the multi-tubular membrane reactor designed in this text. 

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