Raffinate, defined

P ) Qpp- The specification of P and the solid flow rate (or, alternatively, one of the liquid flow rates) defines all the flow rates throughout the TMB system. The P parameter has a higher limit, since the feed flow rate must be higher than zero, 1 < /3 < v t. The case of /3 = 1 corresponds to the situation where dilution of species is minimal, and the extract and raffinate product concentrations approach the feed concentrations. In fact, for /3 = 1, we obtain = Qf = = ( - 1) = (Kg... 

Figure 9-13 shows the Ynryn P ° obtained for the first case where four regions are defined a region of complete separation, two regions where only one outlet stream is 100 % pure and a last region where neither of them is 100 % pure. The closed circles are numerical results based on the equivalence between the TMB and the SMB the thick lines connect those results. The thin line in Fig. 9-13 has two branches. The diagonal 7 -7 corresponds to zero feed flow rate therefore, 7 must be higher than Yn- The horizontal branch Ym corresponds to zero raffinate flow rate in this case, the extract flow rate is 25.09 mL min k... 

In 1950 the Fischer-Tropsch synthesis was banned in Germany by the allied forces. Sinarol, a high paraffinic kerosene fraction sold by Shell, was used as a substitute. This ban coincided with the rapid development of the European petrochemical industry, and in due time Fischer-Tropsch synthesis applied to the production of paraffins became uneconomic anyway. After the war there was a steady worldwide increase in the demand for surfactants. In order to continually meet the demand for synthetic detergents, the industry was compelled to find a substitute for /z-paraffin. This was achieved by the oligomerization of the propene part of raffinate gases with phosphoric acid catalyst at 200°C and about 20 bars pressure to produce tetrapropene. Tetrapropene was inexpensive, comprising a defined C cut and an olefinic double bond. Instead of the Lewis acid, aluminum chloride, hydrofluoric acid could now be used as a considerably milder, more economical, and easier-to-handle alkylation catalyst [4],... 

The nomenclature used in solvent extraction has been defined in Chapter 1 and is illustrated in Fig. 8.1. Not all of the steps shown in this figure will be found in every extraction process, but equally there may be occasions where it is necessary to add additional steps for example, to recover the extractant from the scrub raffinate. So while Fig. 8.1 is not a completely general flow diagram it covers most of the processes likely to be found in practice. Variations of this flow sheet will become apparent during the remaining chapters. 

The Murphree stage efficiencies are also in common use. In terms of the extract the Murphree extract stage efficiency Eme is defined as the ratio of the number of moles of solute actually transferred to the number which would be transferred if the final extract were in equilibrium with the actual final raffinate. Preservation of a material balance does not permit such final equilibrium concentrations actually to develop, but in terms of the concentrations shown in Fig. 2 this becomes... 

Similarly the Murphree raffinate stage efficiency EMr is defined as... 

The effectiveness of the separation can be quantified by an efficiency, q, which is defined as the actual increase in raffinate concentration divided by the increase expected from the altered solution volume. For example, if half of the feed solution is absorbed by the gel and the raffinate has twice the feed concentration, then the efficiency would be 100%. The efficiency is primarily a measure of how well the solute is excluded from the polymer network of the geL The efficiency can be reduced, however, by physical entrainment of raffinate solution around the gel particles. The entrained solute can be recovered by washing the swollen gel and adding the wash liquor to new feed. 

The relative volatility, or selectivity factor, for each component in the presence of carbon dioxide is also given in Table I. Relative volatility is defined as the ratio of K-value for component i to K-value for limonene. The K-value for component i is defined as mole fraction i in the vapor (extract) phase to mole fraction i in the liquid (raffinate) phase. 

In the recent years Simulated Moving Bed (SMB) technology has become more and more attractive for complex separation tasks. To ensure the compliance with product specifications, a robust control is required. In this work a new optimization bas adaptive control strategy for the SMB is proposed A linearized reduced order model, which accounts for the periodic nature of the SMB process is used for online optimization and control purposes. Concentration measurements at the raffinate and extract outlets are used as the feedback information together with a periodic Kalman filter to remove model errors and to handle disturbances. The state estimate from the periodic Kalman filter is then used for the prediction of the outlet concentrations over a pre-defined time horizon. Predicted outlet concentrations constitute the basis for the calculation of the optimal input adjustments, which maximize the productivity and minimize the desorbent consumption subject to constraints on product purities. 

Note that the recovery column is still a liquid/liquid extractor however, the toluene s role is now the raffinate and the caustic water is the solvent. In addition, the distribution coefficient needs to be defined as or the inverse of the definition for the... 

Even though the degree of the actinide removal still needs to be more precisely defined, actinide decontamination factors (DF) of 103 for Pu, Am and Cm are taken as target values to be attained (12) by a specific partitioning process on HAW raffinates. A DF of about 10 for Np appears to be sufficient higher values would indeed yield only an insignificant advantage (12). 

An equilibrium or theoretical stage in liquid-liquid extraction, as defined earlier, is routinely utilized in laboratory procedures. A feed solution is contacted with a solvent to remove one or more of the solutes from the feed. This can be carried out in a separating funnel or, preferably, in an agitated vessel that can produce droplets about 1 mm in diameter. After agitation has stopped and the phases separate, the two clear liquid layers are isolated by decantation. The partition ratio can then be determined directly by measuring the concentration of solute in the extract and raffinate layers. (Additional discussion is given in Liquid-Liquid Equilibrium Experimental Meth-... 

The selectivity of an extraction is defined as the concentration ratio of the solute and carrier components in the extract phase divided by the same ratio in the raffinate phase ... 

The distribution coefficient, k, is defined as the ratio of the weight fraction of solute in the extract phase, y, to the weight fraction of solute in the raffinate phase, x, i.e.. 

The positions of the four discontinuities that define the widths of the bands of the raffinate and the extract in the system can be calculated from the following sums [24]... 

This system of inequalities defines a region in the four dimensional space spanned by the four flow rate ratios. In the framework of the equilibrium theory, the points belonging to this region correspond to the experimental conditions that allow the achievement of a complete separation of solutes A and B, one in the extract and the other in the raffinate. The boimdaries of this region depend on the composition of the two streams pmnped into the SMB unit, the desorbent, Xp, and the feed, Xf, and on the retention times of the solutes, which is described by Eq. 17.77. 

The two rectilinear coordinates define the component fractions of two of the three main components in an extraction process. The third component is determined as the difference from unity. For example, the raffinate component fraction, may be defined on the horizontal coordinate and the extract component fraction, Xg on the vertical coordinate. The solvent component fraction is then determined as X = 1 - X - X. The resulting diagram for a given R II S system is shown schematically in Figure 11.7. 

The extraction model is shown in Figure 11.3. The equation variables Lq and are the solvent and extract component flows, and are the feed and raffinate component flows, and N is the number of equilibrium stages. Flow rates are on a mass or mole basis. The extraction factors E are defined as... 

Any point on Fignre 10.1 defines one ternary composition. Points interior to the mntnal solnbility diagram form two phases as shown in Figure 10.2, where a mixture with composition M in this diagram is shown to separate into two phases with extract composition E and raffinate composition R. The inverse lever rule defines the relative amounts of the two phases. So, given the line segment EM and MR, relative amounts are... 

The point M is also known as the mix point, and it defines the overall stoichiometric composition of the mixture (i.e., the composition if only a single phase was formed by mixing), while the extract and raffinate compositions E and R are found from constructing a line parallel to the nearest tie lies that also intersects the mix points and the mutual solubility curve. 

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