Model membrane reactor configuration

In a generalized case, both the tube and the shell sides are packed with catalyst beds (e.g., in a reaction coupling situation explained in Chapter 8) and the membrane layer is catalytic either inherently or through impregnation on the pore surfaces. Two commonly occurring membrane reactor configurations will be treated as special cases of this generalized model. 

Then Ramasubramanian et al. [42] reported spiral wound C02-selective membrane reactor for GS reaction by using Cu0/Zn0/Al203. Figure 6.19 shows the configuration of spiral wound model membrane reactor. 

Two 50-kW fuel processors concepts were compared by Lattner and Harold [405]. Both systems had autothermal reformers combined with either catalytic carbon monoxide dean-up or membrane reactor configurations. Tetradecane was used as the model substance for diesel fuel. 

Membrane reactor models of various configurations, complexity, and ranges of applicability have been previously reported [Sun and Khang, 1988 Itoh and Govind, 1989 Liu et al., 1990], Several previous investigators have presented water-gas shift membrane reactor models. A model of the iron-chromium oxide catalyzed water-gas shift reaction at 673 K in a cylindrical, palladium membrane reactor was developed to demonstrate... 

When implemented in the field, inorganic membrane reactors invariably will be large in scale and complex in configuration. Their reliable design and operation rest on the foundation of good understanding and design of laboratory and pilot reactors. An important tool that helps build that foundation is validated mathematical models. 

For ease of fabrication and modular construction, tubular reactors are widely used in continuous processes in the chemical processing industry. Therefore, shell-and-tube membrane reactors will be adopted as the basic model geometry in this chapter. In real production situations, however, more complex geometries and flow configurations are encountered which may require three-dimensional numerical simulation of the complicated physicochemical hydrodynamics. With the advent of more powerful computers and more efficient computational fluid dynamics (CFD) codes, the solution to these complicated problems starts to become feasible. This is particularly true in view of the ongoing intensified interest in parallel computing as applied to CFD. 

Furthermore, various membrane reactor parameters and configurations result in different performance levels. All the above factors and other engineering aspects will be reviewed in this chapter with both modeling predictions and experimental data. 

The permeate is continuously withdrawn through the membrane from the feed sueam. The fluid velocity, pressure and species concentrations on both sides of the membrane and permeate flux are made complex by the reaction and the suction of the permeate stream and all of them depend on the position, design configurations and operating conditions in the membrane reactor. In other words, the Navier-Stokes equations, the convective diffusion equations of species and the reaction kinetics equations are coupled. The transport equations are usually coupled through the concentration-dependent membrane flux and species concentration gradients at the membrane wall. As shown in Chapter 10, for all the available membrane reactor models, the hydrodynamics is assumed to follow prescribed velocity and sometimes pressure drop equations. This makes the species transport and kinetics equations decoupled and renders the solution of... 

They have also modeled a perfectly mixed membrane reactor for the same reaction. For this membrane configuration, the C2 selectivity is essentially 1(X)% for a jo value of less than 0.2 and drops off rapidly with increasing The yield becomes greater as the relative oxygen permeation rate increases. The yield reaches a maximum and then decreases with the permeation rate. There is only a limited range of Jo in which the yield can reach beyond 20%. 

As one of the two common types of membrane modules, the hollow-fiber membrane module has shown excellent mass transfer performance due to its large surface area per unit volume (about 1000-3000ft2/ft3 for gas separation). In the modeling work, the WGS membrane reactor was configured to be a hollow-fiber membrane module with catalyst particles packed inside the fibers. 

In this study the feasibility of implementing ceramic membranes on an industrial scale in the styrene production process is treated. Therefore, a model has been set up in the flowsheeting package ASPEN PLUS , which describes a styrene process production plant. Some modelling has been done with different types of membrane reactors in different reactor section configurations to investigate the influence on the performance of the production of styrene. 

There are a number of membrane reactor systems, which have been studied experimentally, that fall outside the scope of this model, however, including reactors utilizing macroporous non-permselective membranes, multi-layer asymmetric membranes, etc. Models that have been developed to describe such reactors will be discussed throughout this chapter. In the membrane bioreactor literature, in particular, but also for some of the proposed large-scale catalytic membrane reactor systems (e.g., synthesis gas production) the experimental systems utilized are often very complex, in terms of their configuration, geometry, and, of course, reaction and transport characteristics. Completely effective models to describe these reactors have yet to be published, and the development of such models still remains an important technical challenge. 

Figures 7.21 and 7.22 show typical results for the two cases-with enzymatic gel layer formation and when soluble enzymes are confined only near the membrane surface. Comprehensive models for an immobilized enzyme batch membrane reactor (IEMR) and for a soluble enzyme batch membrane reactor (SEMR) are proposed in References 33 and 30, respectively, for a flat slab membrane configuration.

Developed a one-dimensional non-isothermal model for the novel WGS membrane reactor with a C02-selective membrane in the hollow-fiber configuration using air as the sweep gas. 

We have developed a mathematical model for the countercurrent WGS membrane reactor with a CO2-selective membrane in the hollow-fiber configuration using air as the sweep gas. With this model, we have elucidated the effects of system parameters on the novel WGS membrane reactor for synthesis gases from steam reforming and autothermal reforming. The modeling results show that H2 enhancement via CO2 removal and CO reduction to 10 ppm or lower are achievable. For comparison and the completeness of the modeling work, we have also developed a similar model for the cocurrent WGS membrane reactor. 

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