Closed-architecture

Two primary methods exist for the introduction and removal of reagents from reactors a flow-through system employing inlet and outlet valves or a liquid-handling robot with stand-alone reactors. Although a valving system always has a closed architecture, a robotic system may have an open or closed architecture. 

The optimal configuration of a valve or flow-through system is achieved by mounting the reactors at a stationary location in the instrument, thus dictating a closed architecture... 

The typical and most straightforward configuration for a membrane reactor is composed of two concentric tubes, where the catalyst is packed in the annular zone while the inner tube is the membrane itself (closed architecture) as shown in Fig. 11.2. 

The two configurations both have several benefits and drawbacks. Globally, at the same operating conditions, the closed architecture is more compact, shows ease of scalability and avoids catalyst waste however, its major drawback is in the technological difficulties involved in designing and maintaining the reactor. 

The modeling of the WGS reaction assisted by membranes was carried out using both closed and open architecture. In the case of the closed architecture, the model was developed for the tube in tube configuration. The... 

In the study of an open architecture, two WGSRs with a membrane module separating them were employed. In both cases, the membrane permeation surface was assumed to be the same. However, the temperature profiles were different in the closed architecture, the temperature along the membrane... 

The results of mathematical modeling developed for closed architecture with a catalyst effectiveness factor of 0.6 clearly show the effect of the presence of the membrane on CO conversion profile along the catalyst bed. The most important effect is that the reactor, in this case, can overcome the thermodynamic limitations and the maximum CO conversion is higher than that obtained without the membrane. In addition, it is worth noting that the equilibrium CO conversion can be obtained by using a lower catalyst volume, or in other words at a shorter reactor length. 

The effect of the catalyst effectiveness factor on the membrane assisted WGSR in closed architecture is shown in Fig. 11.4, in terms of CO conversion (Fig. 11.4a) and reactor temperature profile (Fig. 11.4b). 

Effect of catalyst effectiveness factor on WGS membrane reactor performance in closed architecture (a) CO conversion and (b) temperature. 

It should be noted that in the case of closed architecture the catalyst and the membrane tube can be arranged in such a way that the hydrogen flux can be centrifugal (the catalyst in the inner tube) or centripetal (the catalyst in the outer tube). Clearly, such an arrangement (i) would require a specific catalyst support such as an open cell foam, allowing a radial flow and (ii) would influence the temperature profile established in the catalyst bed, thus potentially leading to an improvement in catalyst performance (Palma et al, 2009). 

The catalyst volume was taken to be equal to 33.7 m for the closed architecture, and twice that for open architecture, whereas the membrane surface was the same for both configuration and equal to 38.5 m. ... 

On the basis of these assumptions, the costs obtained in the case of closed architecture were 705 /kmol H2 produced, whereas in the case of open architecture, the costs are sfightly at 680 /kmol/h Hj produced, with a gain of about 5%. 

Open architecture systems are systems that provide a varied combination of interoperability, portability, and open software standards. It can also mean systems configured to allow unrestricted access by people or other computers. Open architecture will most likely apply primarily to system backbones, such as the network structure, computer structure, and operating systems. Application hardware and software will plug into these backbone structures, but will themselves probably not be open. For example, the IBM PC hardware has an open architecture, whereas the Apple home computer has a closed architecture. The open architecture allows third-party vendors to develop hardware for the PC. Linux is software that is an open architecture operating system that allows users to modify it and make their own enhancements, whereas Microsoft Windows is not open architecture. 

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