Implementation of membranes

The packed bed ceramic membrane reactor configuration (PBMR) has been chosen as the reactor set-up (see Section 14.2.2). In the PBMR configuration three possible sub-configurations can be envisioned for a specific sweep gas in combination with a hydrogen or oxygen selective membrane for the dehydrogenation of ethylbenzene. These sub-configurations are shown in Fig. 14.10. 

In sub-configuration (A) hydrogen will permeate through the hydrogen selective membrane tube under the influence of a pressure difference over the membrane and it will be carried away with an inert sweep gas (steam). The partial pressure of hydrogen in the reaction mixture will decrease cmd the equilibrium will shift to the product side. 

In sub-configuration (B) the permeated hydrogen will be swept away with air. Hydrogen will be burned and the heat generated by this exothermic reaction flows through the membrane to the reaction mixture. In this way the reactor will get an isothermic character and therefore higher conversions. 

The third sub-configuration (C) uses oxygen permeable membranes instead of hydrogen permeable membranes. Again air is used as an oxygen source in 

For modelling the styrene process in ASPEN PLUS , several assumptions have been made  

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F. (2008) Proceedings ICIMIO, Tokyo, Fischer Tropsch Synthesis with In-situ Water Removal Industrial Implementation of Membranes and their Economic Feasibility. 

The impact of parameters such as the ratio of protein mass to the membrane cutoff (A), or the effect of the membrane material during permeation, on their structure/ function, is currently unknown and constitutes an essential requisite for the full development and implementation of membrane processes for the selective fractionation of proteins. 

This work focuses on the reactor section of the styrene production process because it is the most promising part for the implementation of membranes. The reactor section of this process is shown in Fig. 14.9 [50]. 

The simulation results are not cis promising as expected beforehand and not as good as those reported in literature [45-49]. To find an explanation for our results, we first simulated the implementation of membranes having a permselectivity which is thousand times higher than that for microporous membranes, but which has the same hydrogen permeability. To create an even more ideal environment for extremely selective removal of hydrogen from the reactant gas, the permeate pressure has been set to 0.005 bar. 

In addition to the challenges mentioned above, the thermochemical stability of the perovskite membranes in syngas environment is a major hurdle that needs to be overcome for successful implementation of membrane technology for hydrogen separation. Both SrCeOs and BaCe03 based compositions are shown to be unstable in the presence of CO2 and H2O [16-18]. It was shown that replacing a fraction of Ce in the perovskite with Zr also provided improved stability [19]. However this... 

I 9 Economics Associated with implementation of Membrane Reactors... 

Although these types of studies are important for further improving the efficiency of processes and extending the field of applications, the implementation of membrane reactors on a large scale also needs to be addressed. 

Based upon the above considerations, it is concluded that the implementation of membrane reactors at an industrial level will be strongly related to further development, testing and optimization of larger scale membrane reactors under real operating conditions, in order to obtain effective performance and cost data to be directly used for techno-economic evaluations by industrial companies. 

H. Susanto, Towards prachcal implementations of membrane distillation. Chemical Engineering and Processing 2011, 50, 139-150. 

Susanto H. (2011), Towards practical implementations of membrane distillation, Chem. Eng. Proc., 50,139-150. 

Implementation of membrane-less cells, however, faces many inherent problems. Ancillary structures are needed to achieve the laminar flows, including pumps and special channel entrances. The operation is suitable to microfluidic designs with narrow channels and orientation independence... 

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