Separated region

In design of separating chambers, static vessels or continuous-flow tanks may be used. Care must be taken to protect the flow from turbulence, which coiild cause back mixing of partially separated fluids or which could cany unseparated hquids rapidly to the separated-hquid outlet. Vertical baffles to protect rising biibbles from flow currents are sometimes employed. Unseparated fluids should be distributed to the separating region as uniformly and with as little velocity as possible. When the bubble rise velocity is quite low, shallow tanks or flow channels should be used to minimize the residence time required. 

Separation regions are also encountered in the centrifugal impeller as shown previously. Applying the same concept (separation causes a loss in efficiency and power) reduces and delays their formation. Diverting the slow-moving fluid away lets the separation regions be occupied by a faster stream of fluid, which reduces boundary-layer build-up and thus decreases separation. 

The obvious application of microfocus Raman spectroscopy is the measurement of individual grains, inclusions, and grain boundary regions in polycrystalline materials. No special surface preparation is needed. Data can be obtained from fresh fracture surfeces, cut and polished surfaces, or natural surfeces. It is also possible to investigate growth zones and phase separated regions if these occur at a scale larger than the 1-2 pm optical focus limitation. 

Separate regions in Figure 6.33 account for scatter of velocities of cylinders and spheres separating into 2, 10, or 100 fragments. The assumptions used in deriving the figure are from Baker et al. (1983), namely,... 

Separate regions in the figure account for the scatter of velocities for spheres and cylinders separating into 2, 10 or 100 fragments. The number of fragments must first be chosen, usually on the basis of scaled energy. 

Proline is the only amino acid in Table 27.1 that is a secondary amine, and its presence in a peptide chain introduces an amide nitrogen that has no hydrogen available for hydrogen bonding. This disrupts the network of hydrogen bonds and divides the peptide into two separate regions of a helix. The presence of proline is often associated with a bend in the peptide chain. 

The Ynryn provide possible operating conditions that allow the separation of a binary mixture. The separation regions are built imposing that the constraints concerning sections I and IV are fulfilled. Since Yj is a linear function of Yu and Yup we must ensure that the region of complete separation of both species is not affected by the value of Yp In fact, in section I (between the eluent and extract nodes) the objective is to ensure that the more retained species B move upwards, in the same... 

The vertex of the complete separation region, evaluated for k = 0.5 s is characterized by Yu - -86 and Ym 4 -75. The corresponding minimum value of Yi is Yi -7.135 -H 3.86 - 4.75 = 6.245, which is still higher than the critical value 7 = 6.045. We conclude that, considering negligible mass transfer, within the whole separation region built under these conditions, the Yi value does not affect the SMB performance. It should be pointed out that the presence of mass transfer resistance can influence the critical value for 7 and the form of the separation region [32]. 

Fig. 9-14. Influence of the mass transfer resistance on the separation region Ynryii ...

The vertex of a separation region points out the better operating conditions, since it is the point where the purity criteria are fulfilled with a higher feed flow rate (and so lower eluent flow rate). Hence, in the operating conditions specified by the vertex point, both solvent consumption and adsorbent productivity are optimized. Comparing the vertex points obtained for the two values of mass transfer coefficient, we conclude that the mass transfer resistance influences the better SMB operating conditions. Moreover, this influence is emphasized when a higher purity requirement is desired [28]. 

The case with k = 0.4 s (open squares) is close to the situation where mass transfer resistance is negligible. These differences are due to mass transfer resistances as we can easily conclude by comparing the separation regions obtained for the cases with k = 0.4 and k = 1 s k If mass transfer resistance is important, the region of complete separation can be significantly reduced from the one obtained by the Equilibrium Theory. For example, for a mass transfer coefficient of k = 0.1 s there is no separation region where extract and raffinate are 99.5 % pure. 

Fig. 9-18. Separation regions in a Yuryu Equilibrium Theory (100 %, line), mass transfer eoeffieient = 1 s (99.5 %, elosed squares), k = 0.4 s (99.5 %, open squares).

The optimum of the complete triangular separation region (maximizing productivity and minimizing eluent consumption) is the point w corresponding to ... 

Higher overall heat transfer coefficients are obtained with the plate heat exchanger compared with a tubular for a similar loss of pressure because the shell side of a tubular exchanger is basically a poor design from a thermal point of view. Considerable pressure drop is used without much benefit in heat transfer efficiency. This is due to the turbulence in the separated region at the rear of the tube. Additionally, large areas of tubes even in a well-designed tubular unit are partially bypassed by liquid and low heat transfer areas are thus created. 

In polyatomic molecules there are separate regions of essentially nonoverlapping electron clouds whose interaction may be treated by London s methods. This was recognized by many authors, but relatively few calculations have emphasized this factor. Indeed sometimes it may have been erroneously dismissed as of negligible magnitude. Bom and Mayer6 Considered London forces in their... 

Metals are insoluble in common liquid solvents but can dissolve in each other (like dissolves like). A mixture of substances with metallic properties is called an alloy. Some alloys are true solutions, but microscopic views show that others are heterogeneous mixtures. Brass, for instance, is a homogeneous solution of copper (20 to 97%) and zinc (80 to 3%), but common plumber s solder is a heterogeneous alloy of lead (67%) and tin (33%). When solder is examined under a microscope, separate regions of solid lead and solid tin can be seen. When brass is examined, no such regions can be detected. 

This might be done, by considering the metal wall and perhaps also the jacket as consisting of a series of separate regions of uniform temperature, as shown in Fig. 3.9. The balances for each region of metal wall and cooling water volume, then become for any region, n. 

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