Operating conditions separator performance, effects

Equation (9.1) is the preferred method of describing membrane performance because it separates the two contributions to the membrane flux the membrane contribution, P /C and the driving force contribution, (pio — p,r). Normalizing membrane performance to a membrane permeability allows results obtained under different operating conditions to be compared with the effect of the operating condition removed. To calculate the membrane permeabilities using Equation (9.1), it is necessary to know the partial vapor pressure of the components on both sides of the membrane. The partial pressures on the permeate side of the membrane, p,e and pje, are easily obtained from the total permeate pressure and the permeate composition. However, the partial vapor pressures of components i and j in the feed liquid are less accessible. In the past, such data for common, simple mixtures would have to be found in published tables or calculated from an appropriate equation of state. Now, commercial computer process simulation programs calculate partial pressures automatically for even complex mixtures with reasonable reliability. This makes determination of the feed liquid partial pressures a trivial exercise. 

The separation performance of the reaction section is key to realizing the full potential of catalytic distillation as described above. Efficient gas-liquid mass transfer ensures immediate removal of the products from the reaction zone, effectively shifting the equilibrium such that reactants arc completely converted. Poor separation, on the other hand, will result in the reaction s proceeding little beyond the equilibrium value associated with a fixed bed operating under the same conditions. The remaining reactants will then have to be separated from the products downstream. The potential of catalytic distillation to avoid difficulties in separation due to azeotropes with the reactants is then lost. (It should be kept in mind, however, that while this is one of the major attractions of catalytic distillation, the process cannot help avoid all azeotropes that may form.)... 

The effects of operating conditions on separation [119] performance were studied. POMS membrane was more perm-selective to the aroma compound than PDMS. /3 higher for ETH than for ETB... 

Since the characteristics of the linear polyolefin dispersions that are being studied and produced vary over wide limits, the selection of the proper centrifuge for a specific separation becomes an important consideration. The performance of a given centrifuge and the economics of its use can frequently be improved by a factor of 2 or more by a minor change in reactor conditions without detrimental effect on the product itself. The role of the pilot plant in this connection cannot be overemphasized. In many cases, pilot plant-size centrifuges have been used to monitor reactor conditions and other process operating variables with substantial economies in the final process. 

Basic Equations In the following sections, internal mechanisms of water flux in the membrane due to capillary forces will be explored, considering AP = 0. The effect of nonzero A P% is presented separately in Sect. 8.2.2.8.2 Two equations determine the distribution of water in the membrane and its effect on current-voltage performance under operation conditions. 

The manner in which reflux influences an extractor performance and the extent of its effect depend on the equilibrium characteristics of the particular system. Also, the ranges of reflux and other operating conditions must be restricted to the two-phase region where separation is feasible, both thermodynamically and physically. 

FI preconcentration system compared to one without preconcentration. For example, the response of a flame AAS detector may be influenced by a change in the solution introduction rate (cf. Sec, 2.4,2, equation 2.1). These effects should be differentiated from enrichment effects in order to obtain a valid evaluation of the preconcentration performance. This may be realized by separately determining the enhancement factor under similar operational conditions but without preconcentration. In this book the two factors will be differentiated whenever possible, otherwise the total enhancement factor, expressed as will be used instead of EF. Fang ei al.[10] have shown that when sensitivity enhancement factors exist, other than an increase in concentration of the analyte in solution, the enhancement effects will be multiplicative on EF. Provided that different factors have independent enhancement mechanisms, the total enhancement factor Nt, will be the product of the individual enhancement factors, N, and... 

Seawater is a complicated mixture of many components. Hence, it is difficult to predict the manhrane performance under different operating conditions based on transport theories. Most of the theories treating the separation of multicomponent electrolytic systans are based on the Debye-Hiickel theory, Donnan effect, and Nemst-Planck eqnation [52,53]. Although they are applicable to the mixture of any number of ions involved in the feed, there are only few works in which... 

He et al used a binary mixture-based film model to perform a theoretical analysis on the concentration polarization in a generic membrane. They defined a concentration polarization coefficient for both the two species involved in the separation as the ratio of the actual flux to the ideal one (without polarization), quantifying the polarization effect by means of the ratio of the actual fluxes of the components. Although this is a simplified approach that cannot be generalized to multi-component systems, nevertheless, under some operating conditions, the authors predicted a significant influence of the external mass transfer on the process. 

He, Y., Li, G., Wang, H., Zhao, J. and Huang, Q. 2008b. Effects of operating conditions on separation performance of reactive dye solution with membrane process. 

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