Foam Separation Tests

Gas bubble in oil phase. Little research here has been accomplished, and very little has been published about gas bubble or foam separation from liquid. Herein I offer a good contribution to this technology, along with a plea for more field-proven data. As in the case for liquid droplet fall in the gas phase, I propose that the same equations, Eqs. (4.5), (4.6), and (4.7), be used in the oil media. This is done in these three equations, Eq. (4.7) deriving the gas bubble terminal velocity. We must, however, input a feasible and proven gas particle size Du, pm. Having accomplished several field-proven foam separation tests, the following Dm determination equation is offered. 

Foam Separation by Dispersed Air Flotation Cell Chemical Reagents for Adsorptive Bubble Separation Laboratory Foam Separation Tests Engineering Applications... 

AGAIN, POUR 10 ml OF EACH SOLUTION INTO SEPARATE TEST TUBES. ADD 5 ml LIME-WATER TO EACH. SHAKE AND NOTICE THE DIFFERENCE IN THE AMOUNT OF FOAM MADE BY EACH SOLUTION IN THIS HARD" WATER. 

The test methods developed for testing flexible cellular plastics are quite different from those developed for rigid foams. For rigid cellular plastics, separate test methods were developed for specific properties. No such separate test methods relating to specific properties are developed for flexible cellular plastics. Instead, a series of test procedures that describe a variety of physical properties of a particular type of material are commonly used to test flexible cellular plastics. 

The foams were tested in a cylindrical calorimeter similar to the one shown in Fig. 2. The unit consists basically of two concentric stainless steel cans separated by a 2)4-in. thickness of the test foam. To minimize the end effects of a calorimeter of this type, the upper end was insulated with a high-vacuum space, while the lower end was insulated with an extra-thick section of the test foam itself. Fill and vent lines, as well as suitable vacuum taps were provided in the... 

The numerous separations reported in the literature include surfactants, inorganic ions, enzymes, other proteins, other organics, biological cells, and various other particles and substances. The scale of the systems ranges from the simple Grits test for the presence of surfactants in water, which has been shown to operate by virtue of transient foam fractionation [Lemlich, J. Colloid Interface Sci., 37, 497 (1971)], to the natural adsubble processes that occur on a grand scale in the ocean [Wallace and Duce, Deep Sea Res., 25, 827 (1978)]. For further information see the reviews cited earlier. 

Table 2 presents the results of tests to measure the calorific power, ash content, and chlorides concentration of some of the materials obtained from the separation process, such as polystyrene, aluminum foil, plastic foam, and other plastics (general, clear, colored, black, and vinyl). Polystyrene and clear plastic have very high calorific power and low levels of chlorides, but polystyrene has very high ash content. Figures 10-17 present the samples of waste components from the separation and composting plant of Cantagalo. 

The mechanical response of polypropylene foam was studied over a wide range of strain rates and the linear and non-linear viscoelastic behaviour was analysed. The material was tested in creep and dynamic mechanical experiments and a correlation between strain rate effects and viscoelastic properties of the foam was obtained using viscoelasticity theory and separating strain and time effects. A scheme for the prediction of the stress-strain curve at any strain rate was developed in which a strain rate-dependent scaling factor was introduced. An energy absorption diagram was constructed. 14 refs. 

The common gangue material quartz (silica) is naturally hydrophilic and can be easily separated in this way from hydrophobic materials such as talc, molybdenite, metal sulphides and some types of coal. Minerals which are hydrophilic can usually be made hydrophobic by adding surfactant (referred to as an activator ) to the solution which selectively adsorbs on the required grains. For example, cationic surfactants (e.g. CTAB) will adsorb onto most negatively charged surfaces whereas anionic surfactants (e.g. SDS) will not. Optimum flotation conditions are usually obtained by experiment using a model test cell called a Hallimond tube . In addition to activator compounds, frothers which are also surfactants are added to stabilize the foam produced at the top of the flotation chamber. Mixtures of non-ionic and ionic surfactant molecules make the best frothers. As examples of the remarkable efficiency of the process, only 45 g of collector and 35 g of frother are required to float 1 ton of quartz and only 30 g of collector will separate 3 tons of sulphide ore. 

Although severe foaming of Troll crude was not indicated in the laboratory tests, provision to inject defoamer upstream of the separators is provided. 

Hexanoic acid. Into a 2-litre three-necked flask, fitted with a separatory funnel, a mechanical stirrer and a reflux condenser, place a hot solution of 200 g of potassium hydroxide in 200 ml of water. Stir the solution and add slowly 200 g (0.925 mol) of diethyl butylmalonate. A vigorous reaction occurs and the solution refluxes. When all the ester has been added, boil the solution gently for 2-3 hours, i.e. until hydrolysis is complete a test portion should dissolve completely in water. Dilute with 200 ml of water and distil off 200 ml of liquid in order to ensure the complete removal of the alcohol formed in the hydrolysis (2). To the cold residue in the flask add a cold solution of 320 g (174 ml) of concentrated sulphuric acid in 450 ml of water add the acid slowly with stirring in order to prevent excessive foaming. The solution becomes hot. Reflux the mixture for 3-4 hours and allow to cool. Separate the upper layer of the organic acid and extract the aqueous portion with four 150 ml portions of ether (3). Combine the acid layer with the ether extracts, wash it with 25 ml of water and dry with anhydrous sodium sulphate. Distil off the ether (rotary evaporator), transfer the residue to a flask fitted with a short fractionating column (the latter should be well lagged and, preferably, electrically heated) and distil the product from an air bath. Collect the hexanoic acid at 200-206 °C. The yield is 80 g (75%). Record the i.r. spectrum and compare it with that shown in Fig. 3.31. 

Uses of Oldershaw columns to less conventional systems and applications were described by Fair, Reeves, and Seibert [Topical Conference on Distillation, AIChE Spring Meeting, New Orleans, p. 27 (March 10-14, 2002)]. The applications described include scale-up in the absence of good VLE, steam stripping efficiencies, individual component efficiencies in multicomponent distillation, determining component behavior in azeotropic separation, and foam testing. 

Disclaimer As in all theoretical variable determinations, these equations presented for Du calculation are subject to field-test verification. Equations (4.14) and (4.16) are not presented as being infallible or able to predict accurately every case of particle size with a given medium viscosity. For example, a crude with a high asphaltene content should be field tested before a final design for construction is issued on the basis of these equations. Small asphaltene crude contents (less than 2%) were used in deriving Eq. (4.16). More tests are needed for foam-liquid separations. Readers and users of this criterion, can perhaps contribute more data, and I indeed solicit such contributions of better methods and data as you may discover. 

A relative drainage rate test in which a foam is formed in a vessel and thereafter the remaining foam volume is determined as a function of time. The foam number is the volume of bulk liquid that has separated after a specified interval, expressed as a percentage of the original volume of liquid foamed. 

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