Partial liquid mixing

As in progressive freezing, many refinements of these models have been developed. Corrections for partial liquid mixing and a variable distribution coefficient have been summarized in detail (Zief and Wilcox, op. cit., p. 47). 

The partial liquid mixing case is of considerable interest in design. Various models for representing partial mixing have been proposed for most instances the eddy diffusion model appears appropriate. This model uses a dimensionless Peclet nuirffien... 

In the more common cases of partial liquid mixing with a boundary layer present near the freezing interface, an effective partition coefficient, 4,eff is defined as... 

Figure 6.3.17. Effect of parameter fSiVfr/Diil/ps/pi) on effective distribution coefficient for partial liquid mixing in molten zone, according to Eq. (6.3.119a) (After Wilcox (1967).)...

In zone melting, if the partial liquid mixing model can be employed, then the impurity mass fraction in the refrozen solid may be obtained from expression (6.3.109h) for the totally mixed case by replacing 4s by 4,eft ... 

From studies in zone melting, it is known that models of partial liquid mixing are more realistic, and the effective partition coefficient approach of equation (6.3.119) is quite useful. In this approach. 

Syngas Homologation of Acetic Acid. To a N2-flushed liquid mix of acetic acid (50.0 gm) and methyl iodide (5.67 gm, 40 mmole), set in a glass liner is added 0.763 gm of ruthenium(IV) oxide, hydrate (4.0 mmole). The mixture is stirred to partially dissolve the ruthenium and the glass liner plus contents charged to a 450 ml rocking autoclave. The reactor is sealed, flushed... 

The monomer ethylene is first led through a series of dryers (not shown), mixed with recycle gas, hydrogen, and butylene, and enters the fluidized bed reactor (Rl) at the bottom. A catalyst is added from numerous locations on the side of the reactor (not shown). The reactor operates at approximately 85°C and 20 bar (the temperature depends on the desired grade). The heat of reaction is removed as sensible heat of the gas stream and by the evaporation of the partially liquid reaction mixture. The reactor gas exits the top of the reactor. 

On the other hand, if sodium and potassium tartrates are mixed with water in the proportions shown on the right side of the equation, the system will remain partially liquid so long as the temperature is maintained above 55 (in a closed vessel to prevent loss of water), but on allowing the temperature to fall below this point, complete solidification will ensue, owing to the formation of the hydrated double salt. Below 55 , therefore, the hydrated double salt is the stablq... 

Unlike in MASRs, where liquid mixing is always considered complete, in this case allowance must be made for partial mixing. Thus it may often be necessary to use the dispersion model given by Equation 17.25. The liquid-phase axial diffusion coefficient for estimating the Peclet number in this equation may be calculated from the correlations of Hikita and Kikukawa (1975) or Mangartz and Pilhofer (1981). 

In Sect. 12.5, we were introduced to a similar situation that leads to lowering of vapor pressure over solutions. However, foreign substance B had low volatility so that the vapor phase was made up of only A (at least approximatively). In the case of two volatile components, reestablishment of equilibrium is caused by lowering of the partial pressure of A to pa in the mixed vapor (above the liquid mixed phase) ... 

Here is a somewhat different formulation of Raoult s law The partial pressure of every component i in a mixed vapor equals the product of the vapor pressure of the pure component and its mole fraction x] in the liquid mixed phase. Ideal mixtures are subject to Raoult s law independent of chemical composition. Conversely, this law also represents a further experimental criterion for the indifferent behavior of the two components relative to each other. 

Interaction is accompanied by formation of the heteromolecular associates. It can be demonstrated by analysis of volumetric equations for the liquid mixed systems, data on volume compression, i.e., positive density deviation from additivity rule, and hence negative deviations of experimental specific molar volume from partial molar volume additivity rule. 

Grosse S, Letzel T (2007) Liquid chromatography/atmospheric pressure ionization mass spectrometry with post-column liquid mixing for the efficient determination of partially oxidized polycyclic aromatic hydrocarbons. J Chromatogr A 1139 75... 

Obviously then, any situation where an alkyl phosphoric add ester-hydrocarbon mixture is liquid or even partially liquid will lead to some measure of selective migration into the powder and therefore antifoam deactivation. Such situations could occur during periods of storage of the powder at elevated temperatures or when the antifoam is sprayed directly onto hot powder immediately after production from a spray-drying tower, as described by Curtis et al. [35]. The antifoam exemplified in this patent consisted of a mixture of a commercial (Cig-Cig) alkyl phosphoric acid monoester and a petroleum jelly, which is a hydrocarbon gel at ambient temperatures with a carbon number >25. Mixing petroleum jelly with the phosphoric acid monoester in the preferred ratio of 1 3 by weight produces an effective antifoam precursor with a drop melting point of 58°C. Curtis et al. [35] describe both full-plant scale... 

Fig. 4.13 Solute (lisu ibutions in a solid bar frozen from liquid of initial concentration Co, for (a)equiUbrium freezing (h). white mixing in the liquid by diffusion only (c) complete solute mixing in the liquid (rf) partial solute mixing in the...

The reactor effluent might require cooling by direct heat transfer because the reaction needs to be stopped quickly, or a conventional exchanger would foul, or the reactor products are too hot or corrosive to pass to a conventional heat exchanger. The reactor product is mixed with a liquid that can be recycled, cooled product, or an inert material such as water. The liquid vaporizes partially or totally and cools the reactor effluent. Here, the reactor Teed is a cold stream, and the vapor and any liquid from the quench are hot streams. 

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