Development Of A Foam Breaker With Perforated Plates And Study On Its Defoaming Performance

There are two essential processes in foam fractionation: interfacial adsorptionand foam drainage and a lot of literature has reported their mechanisms and strategiesfor their enhancement. However, the study on defoaming methods is ignored. Thesuitable stability of foam is the base of foam fractionation therefore, it is necessary todevelop defoaming methods for promoting the application of foam fractionation inindustrial production. Based on the analysis of defoaming principle, a novel low-costfoam breaker with perforated plates was developed. Sodium dodecyl sulfate (SDS)and cetyl trimethyl ammonium bromide (CTAB) were used as the model system forevaluating the performances of the foam breaker and a multistage defoaming modelwas established for predicting the defoaming percentage using the foam breaker.The results showed that both perforated plate and vertical perforated plate couldpromote the defoaming percentage and vertical perforated plate promoted moresignificantly. The results agreed with the analysis of defoaming principle. Thedefoaming percentage increased with the decrease of SDS concentration, liquidholdup, orifice diameter and open area ratio of the plate, when the number ofperforated plates or vertical perforated plates was determined. The foam breaker wasmore effective for defoaming when the bubble diameter was larger than the orificediameter. Vertical perforated plate was less effective for the higher stability of thefoam formed by CTAB. In addition, defoaming was enhanced by decreasing thenumber of bubble caps in the horizontal plate of vertical perforated plate, but it wasnot enhanced by changing the height of bubble cap.The defoaming percentage was80%under the conditions of volumetric gas flow0.20L/min, SDS concentration0.5g/L, liquid holdup3.0%, orifice diameter1.0mm,open area ratio1.0%, height of bubble cap70mm, the number of bubble caps one and the number of vertical perforated plates five. Therefore, the foam breaker withperforated plates or vertical perforated plates could be used for defoaming in foamfractionation. Meanwhile, experiments showed that the multistage defoaming modelpredicted successfully the defoaming percentage using the foam breaker.