Development Of A Foam Breaker With Porous Medium Cylinder And Study On Its Defoaming Performance

At present,the common defoaming methods are divided into two types:chemical and physical.Physical method is concerned for its clean characteristic by researchers.These new foam breakers with disadvantages of high energy consumption and low defoaming efficiency were reported.For decreasing further energy consumption and improving the defoaming efficiency of physical defoaming method,a new foam breaker with porous medium cylinders was developed.Sodium dodecyl sulfate(SDS),and cetyl trimethyl ammonium bromide(CTAB)and whey soy protein(WSP)were used as the model system for evaluating the performances and explaining the mechanism of the foam breaker.Based on the above researches,a defoaming model was established to predict the defoaming efficiency and was verified by the experimental data.The results show that no SDS molecules were adsorbed at the synthetic sponge and the capillary pressure of porous medium is lower than foam.So,the adhesion and shear on the interstitial liquid and furrow on the liquid film caused by capillarity and roughness were the main reason.The defoaming percentage increased with the decrease of pore size of porous medium,and increased with the increase of the number of porous medium cylinder,solution concentration and volumetric gas velocity.The defoaming efficiency of foam formed by CTAB is lower than SDS and WSP,because the liquid holdup and the half-time of CTAB foam is respectively lower and higher than SDS and WSP.Meanwhile,the result of model prediction shows that the relative error of between predicted values and experimental was less than 10.0%when the defoaming efficiency was more than 90.0%,and adversely the relative error was less than 30%.The defoaming percentage of the new foam breaker was 100.0%(SDS),65.3%(CTAB)and 100.0%(WSP)under the conditions of the pore size 0.23±0.05 mm and mean density55.0±0.2 kg/m~3 of porous medium,the number of porous medium cylinders 4,WSP concentration 2.0 g/L,SDS and CTAB concentration 0.6 g/L,volumetric gas velocity 200mL/min and volumetric liquid fraction 3.0±0.1%.Furthermore,the new foam breaker with the porous medium cylinders had much higher defoaming efficiency and lower energy consumption than that with the paddle agitators at 300 rad/min.Therefore,the foam breaker with the porous medium cylinders is promising.