Precipitation systems

Dahmen U 1982 Orientation relationships in precipitation systems Acfa Metall. 30 63... 

FIG. 17-66 Electrostatic-precipitator-system model. (Nichols and Ogleshy, Electrostatic Precipitator Systems Analysis, AIChE annual meeting, 1970.)... 

FIG. 25-47 Schematic diagram of a chemical precipitation system for rectangular sedimentation tanks. 

It is easy to see that, under normal circumstances, the characteristic distance is much shorter than the effective length of the precipitation system. 

Thus in a mixed system, as e.g. in a stirred tank, the rate of agglomeration additionally depends on the shear field and therefore on the energy dissipation e in the vessel. Furthermore, in precipitation systems solution supersaturation plays an important role, as the higher the supersaturation, the stickier the particles and the easier they agglomerate (Mullin, 2001). This leads to a general formulation of the agglomeration rate... 

There is an increasing number of industrially important gas-liquid reaction precipitation systems (see Kirk-Othmer, 1993), including the following ... 

For liquid-liquid crystal precipitation systems where the particle formation processes are fast, mixing becomes an important determiner of performance with a subtle interplay of micro- and mesomixing, which changes as scale of... 

Al-Rashed, M.H. and Jones, A.G., 1999a. Validation of a CFD model of a gas-liquid precipitation system. In Industrial Crystallization 99. (Rugby Institution of Chemical Engineers). Cambridge, 13-15 September 1999. Paper 157, p. 160. 

Sohnel, O., Chianese, A. and Jones, A.G., 1991. Theoretical approaches to the design of precipitation systems The present state of the art. Chemical Engineering Communications, 106, 151-175. 

Wachi, S. and Jones, A.G., 1995. Aspects of gas-liquid precipitation systems for precipitate particle formation. Reviews in Chemical Engineering, 11, 1-51. 

A modified reduction-flotation system (Figure 6.5) is very similar to the existing conventional reduction-precipitation system (Figure 6.4), except that a DAF clarifier [T-101F] is used for clarification15-57 instead of using a conventional sedimentation clarifier (Tank T-101, Figure 6.4). 

It should be noted that the chemical reactions of the conventional reduction-precipitation system (Figure 6.4) and the modified reduction-flotation system are identical. 

It is seen from Figure 6.7 that this system is much simpler, more cost-effective, and easier to operate in comparison with all other process systems discussed earlier. The treatment efficiency of the new flotation-filtration system is expected to be higher than that of the conventional reduction-precipitation system. The new flotation-filtration system also requires much less land space.15... 

Table 6.3 shows the characteristics of a typical effluent discharge from a conventional reduction-precipitation system. The effluent quality meets industrial pretreatment requirements. 

The treatment efficiencies of the two innovative flotation-filtration wastewater treatment systems (Figures 6.6 and 6.7) are expected to be higher than those of the conventional reduction-precipitation system. 

Feinn, D., Ortoleva, P., Scalf, W., Schmidt, S. Wolff, M. (1978). Spontaneous pattern formation in precipitating systems. J. Chem. Phys., 69, 27-39. 

Metastable crystalline phases frequently crystallise to a more stable phase in accordance with Ostwald s rule of stages, and the more common types of phase transformation that occur in crystallising and precipitating systems include those between polymorphs and solvates. Transformations can occur in the solid state, particularly at temperatures near the melting point of the crystalline solid, and because of the intervention of a solvent. A stable phase has a lower solubility than a metastable phase, as indicated by the solubility curves in Figures 15.7a and 15.7/ for enantiotropic and monotropic systems respectively and,... 

There is no general rule for the prevention or avoidance of occlusion. In some cases, a change of solvent/precipitant system may help to achieve this goal. Raising the drying temperature is also beneficial. 

The kind of analyses just exemplified must be carried out for each precipitating system, because in every case the composition of the solution will differ depending on the hydrolyzability of the cation, complexation with anions, concentration of reactants, temperature, etc. Such projects are exceedingly time-consuming, which explains the paucity of well-documented published cases. 

Fig. 4.1.1 Scheme of a double-jet precipitation system of AgBr particles. 

In addition, at very low water contents, ampicillin accumulation curves do not exhibit a clear-cut maximum, inherent in the enzymatic acyl transfer reactions in aqueous medium (including quite concentrated heterogeneous aqueous solution-precipitate systems), because of the secondary hydrolysis of the target product by penicillin acylase (Figure 12.6) [84]. 

SAVINGS IN NEW PLANT PRECIPITATOR SYSTEMS (Based on 500 Mw Unit) ... 

An extensive formulation of classical and nonclassical models for homogeneous nucleation, as well as experimental tests of their validity, have been carried out for the Co-Cu precipitation system in which coherent Co-rich nuclei form [15]. 

The Cu-Co system is a particularly simple precipitation system in which a Corich /3 phase precipitates in a Cu-rich terminal a phase. The f.c.c. lattices of both phases are well matched in three dimensions, so that the precipitate interfaces are coherent with respect to either lattice as a reference structure and the interfacial energy is sufficiently isotropic so that they are almost spherical, as in Fig. 19.2. Both the interfacial energy and strain energy are therefore relatively low and the nucleation of the f3 phase is therefore relatively easy and occurs homogeneously. This system has been used to test the applicability of the classical nucleation theory (Section 19.1.1) [11, 12]. In this work, the experimental conditions under which... 

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