Multistage processes, application

In general, high selectivities can be obtained in liquid membrane systems. However, one disadvantage of this technique is that the enantiomer ratio in the permeate decreases rapidly when the feed stream is depleted in one enantiomer. Racemization of the feed would be an approach to tackle this problem or, alternatively, using a system containing the two opposite selectors, so that the feed stream remains virtually racemic [21]. Another potential drawback of supported enantioselective liquid membranes is the application on an industrial scale. Often a complex multistage process is required in order to achieve the desired purity of the product. This leads to a relatively complicated flow scheme and expensive process equipment for large-scale separations. 

Davis discusses the evaluation of multistage compressors for conversion to new or different process applications. 

The production of the nylon precursor e-caprolactam via the Beckmann rearrangement is one of the largest industrial processes worldwide. There are a large number of synthetic routes to e-caprolactam, most of which need to be improved because, without exception, all are multistage processes that produce large amounts of by-products, primarily ammonium sulfate. Due to its industrial application, the improvement of the Beckmann rearrangement of e-caprolactam was the aim of several smdies and a lot of scientific papers, patents and book chapters have been published on this topic during the last century. 

In considering these complex multistage processes, the ideas discussed early in this chapter are still applicable. We need to consider each reactor using the principles described in this chapter, but we need also to consider the separation and recycle components of the... 

Section 7 describes the application of numerical techniques (cellular automata and Monte-Carlo (MQ) for dynamical investigation of surface processes. These techniques are alternative approaches for simulations of various multistage processes. 

In the majority of multistage separation processes, the phases in question are vapor and liquid. Vapor-liquid-liquid equilibrium (VLLE) can exist when two partially immiscible liquids are at equilibrium with each other, as well as with a vapor phase. This is a phenomenon that can occur under certain conditions in phase separation processes. Applications in this book cover vapor-liquid, liquid-liquid, and vapor-liquid-liquid separation processes. Chapter 18 discusses membrane separation processes, where the separation is not brought about as a result of different phase compositions, but by the action of membrane barriers. 

In other applications, chemicals are produced by contacting gases and liquids in multistage processes where reaction products are concentrated in the same operation. Examples of such processes include the production of nitric acid (Koukolik and Marek, 1968) and chlorination. 

A chemical intermediate which has no inherent useful properties other than as a starting material for a useful end-product claimed in the same application may depend on the useful end-product for its inventive step because it is part of the same invention. On the other hand, according to a decision of EPO s Technical Board of Appeal, a new chemical intermediate may be inventive if it is prepared in the course of a multistage process, providing that the intermediate itself makes a contribution to the quantitative effect of the process. ... 

Seawater or brackish water is used for process applications or as potable water when fresh water is scarce. Six techniques are used for desalination. Five are evaporation processes multiple-effect thermocompression mechanical vapor compression once-through multistage flash and multistage flash with brine recirculation. The sixth process, reverse osmosis, uses membrane technology for desalination. 

Very recently" an application of the tree approximation to multistage processes during network formation has been reported. The first stage is the reaction of the monomers 1 giving a product 1, the second stage is the reaction of the monomers 2 with the product 1, and so on. This procedure can be applied to the reaction of preformed polymers as well. 

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