Effect on foaming

The limitations of foam are (1) operational complexity, (2) high cost, and (3) the pressure effect on foam consistency, i.e., below about 3,000 ft, foam corn-presses to a near liquid form. 

Bubbles are formed instantaneously. This conclusion made in [33] is based on estimates taken from earlier works [37]. As seen from the above cited works by S. E. Sosin et al., this is not always true viscoelastic liquids under triaxial stretching stress are not destroyed instantly. The existence of an induction period may produce a considerable effect on foam growth kinetics upon free foaming, when pressure is lowered instantaneously from P > Pcr to P < Pcr in a melt with dissolved gas. However, it would appear that microfaults in polymer melts, which are caused by factors... 

NOTE Colloidal clays also can form deposits, and suspended solids have a significantly higher effect on foaming than TDS. 

FIG. 11 Hardness effect on foam stability of LAS homologs in a 24% LAS/6% AES/ 2% amide dishwashing liquid. Conditions 46°C, 0.05% concentration, Keen soil. (From Ref. 19.)... 

Incomplete texturization or partial denaturation at temperatures below 60 °C significantly increased gel strength, but at 75 °C or above, complete loss of the gelling property resulted. Foam volume remained high up to 50 °C but decreased significantly (p < 0.05) above 75 °C. Foam stability followed the same pattern as foam volume, being very stable for an hour below 50 °C. On the contrary, Phillips et al. (1990) reported that WPI heated to 80 °C had little effect on foam stability. 

The system can be operated with fewer emergency responders and foam loss is minimized. Foam chambers cause the foam to flow down the tank shell and onto the liquid surface therefore, thermal updrafts have little effect on foam application. A similar effect is seen with the use of foam chambers to protect the seals on floating roof tanks. 

FIGURE 2.19 The effects on foam active ( ) and HA ( ) protein of treating unstabilized beer with bentonite. Reprinted with permission from Siebert and Lynn (1997b). Copyright 1997 American Society of Brewing Chemists. 

In a later investigation, Kraynik and Hansen [62] demonstrated that the shear rate and liquid film viscosity greatly affect the rheological properties of foams. They studied the effect on foam properties and structure with variation of capillary number, Ca, which is the ratio of viscous to surface tension forces in the liquid films, and is given by -... 

Prins, A. (1999). Stagnant surface behaviour and its effect on foam and film stability. Colloids and Surfaces A Physicochemical and Engineering Aspects, 149, 467 473. 

The studies published by Senee et al. (1999, 2001) show that the endogenous particles (bentonite and yeasts) that can exist in a wine also have an important effect on foam quality, simultaneously having both positive and negative effects, since they have different effects on the various foaming parameters. 

The influence of harvest yield has also been studied and was found to have no effect on foaming qualities (Pozo-Bay6n et al. 2004), in spite of the findings in this work that too large a harvest can significantly affect the sensorial quality of the sparkling wine, producing wines of a poorer quality. 

The wettability of the porous medium was found to have a significant effect on foam flow as early as 1966 (D. C. Bond and G. G. Bernard, AICh 58th Annual Meeting, Dallas, February 7-10, 1966). Later, Kanda and Schechter showed that a foam produced a large reduction of permeability only if the aqueous phase wet the porous medium (64). Thus, various flow studies confirm the importance of wettability. 

A fundamental concern in CO2 foam applications is how far foams can be transported at reservoir temperatures and salinities in the presence of crude oil. Oils that spread at gas/brine interfaces are known to have severe debilitating effects on foam stability. Another concern is that surfactants may retard oil droplet coalescence and therefore reduce tertiary oil reconnection and mobilization efficiency. 

Ritzinger, G.B., "Catalyst Its Effect on Foaming Characteristics and Physical Properties of Rigid Foams," du Pont Co. Brochure A-26302 (June 3, 1960). 

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