Froth-Emulsion

Froth-Emulsion Froth-emulsion transition occurs [Hofliuis and Zuiderweg, I. Cherrt. E. Symp. Ser. 56, p. 2, 2/1 (1979)] when the aerated mass begins to obey the Francis weir formula. Using this criterion, the latest version of this transition correlation is... 

Liquid enters the column and flows across the top tray, where it contacts the rising gas to form a froth, emulsion, or spray-type dispersion (Fig. 18). It then overflows the weir into the downcomer, which separates gas from the liquid, and carries liquid by gravity to the tray below. The liquid then flows across the next tray, and the process is repeated. Liquid is thus contacted with gas in a stagewise manner. 

Flow regime. Since the trays are unlikely to operate in the spray regime (Sec. 6.4.2), it is best to first examine the froth-emulsion transition. This check requires using the Hofhuis correlation for clear liquid height (Sec. 6.3.5). 

The transition from the spray regime to mixed froth-emulsion flow is described by FP > 3.0/ /z ... 

After they are deaerated, the primary and secondary froths are combined into a single stream for further treatment. The deaerated froth contains about 65% oil, 25% water, and 10% solids. It also contains emulsions. The microscopic studies of Swanson (67) showed that emulsified water droplets in froth persist through the deaeration process and were also found in naphtha-diluted deaerated froth. Emulsions of water in bitumen and of bitumen in water, both thought to be stabilized by asphaltenes and fine biwetted solids, have indeed been found in interface layer emulsions in enhanced gravity separators (68). 

In production the quantities of water in emulsions vary from 30% W/0 formed in oil sands extraetion proeesses to 80 or 90% in the form of choeolate mousse during an oil spill at sea (97, 98). Real systems are more eomplex and heterogeneous than the ideal systems. The W/0 droplets are fine, well dispersed, and very stable. Asphaltene content is around 17% in bitumenous emulsions and around 2% for North Sea erudes. Figure 7 shows a eonfoeal photomicrograph of a bitumen froth emulsion fi eshly extracted at CANMET. The solids present are shown as white specks the dark spots are emulsion droplets in a bitumen eontinuous phase. The eomposition is 41% bitumen, 44% water, and 15% solids. 

Emulsion drilUng fluids emulsion fracturing, stimulation, acidizing fluids enhanced oil recovery (EOR) in situ emulsions produced (well-head) emulsions bituminous oil sand process and froth emulsions heavy oil pipeUne emulsions fuel oil and tanker emulsions... 

The value of the critical micelle concentration (CMC) is an important parameter in a wide variety of industrial applications involving adsorption of surfactant molecules at interfaces, such as foams, froths, emulsions, suspensions, and surface coatings. It is probably the simplest means of characterizing the colloid and surface behaviour of a surfactant solute, which in turn determines its industrial usefulness. Many industrial processes are also dynamic processes in that they involve a rapid increase in interfacial area, such as foaming, wetting, emulsification and solubilization. First, the available monomers adsorb on to the freshly created interface. Then, additional monomers must be provided by the breakup of micelles. Especially when the free monomer concentration (i.e. CMC) is low, the micellar breakup time or diffusion of monomers to the newly created interface can be rate-limiting steps in the supply of monomers, which is the case for many nonionic surfactant solutions (3). 

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