Nattawin Chawaloesphonsiya

Study of Cutting-Oil Emulsion Separation by Coalescer Process in Terms of Medium Characteristics and Bed Packing

This work aimed to consider the effects of media shape, size, and packing on the coalescer efficiency. Different shaped polypropylene was applied as media for separating the cutting-oil emulsion. The results exhibited that polypropylene media can separate the emulsion with the highest efficiency of 43% at the optimal condition. The dissimilar shape provided the difference in the equivalent size and the packing by means of porosity, permeability, and pore uniformity. Furthermore, the approach for determining application possibility of materials as coalescer media was proposed. Wetting properties and bed permeability were suggested as key factors for media selection and coalescer process design.

Study of Hydrophobic VOCs Absorption Mechanism in a Bubble Column: Bubble Hydrodynamic Parameters and Mass Transfer Coefficients

The absorption mechanism of hydrophobic Volatile Organic Compounds (benzene) was investigated in a small bubble column. Effects of gas spargers (orifice size), gas flow rates, and absorbents (tap water, aqueous solution with non-ionic surfactant, and lubricant oily-emulsion) were analyzed in terms of absorption efficiency, bubble hydrodynamic, and mass transfer parameters. The results showed that the presence of non-ionic surfactant and lubricant oil affected the bubble hydrodynamic phenomena and the interfacial area (a) and the mass transfer parameters (volumetric mass transfer coefficient, kLa, and liquid-side mass transfer coefficient, kL). Absorption efficiencies of aqueous solutions with the previous substances as absorbents were significantly greater than those of tap water. These experimental results relate to the augmentation of benzene solubility in the liquid phase (absorbents) due to the presence of oily-particles and surfactant molecules. Moreover, high gas flow rates can decrease the VOCs absorption efficiency due to desorption mechanisms, associated with the mixing power in the liquid phase. Finally, it has been suggested that gas spargers with an orifice size smaller than 0.65 mm, 1 cm/s gas superficial velocity, and 50 mg/l lubricant oily-emulsion or 5 CMC non-ionic surfactant aqueous solutions are of optimal design and operation for hydrophobic VOCs absorption in the bubble column used in this study.

Analysis of cutting-oil emulsion destabilization by aluminum sulfate

ABSTRACT The destabilization mechanism of the high stable cutting-oil emulsion by aluminum sulfate (Al2(SO4)3) was investigated since it can affect properties of aggregates and following separation units. Al2(SO4)3 dosage and pH were key factors in the destabilization. The effective separation occurred when precipitated Al(OH)3 is dominated at the neutral pH of 6.5–7.0. The best separation can be achieved when solid flocs were formed at 1.0 mM, which exceeded the dosage from the critical coagulation concentration (CCC) of 0.75 mM. Two different mechanisms were proved for the emulsion destabilization depending upon the Al3+ concentration under this pH range. The first mechanism was the adsorption of Al(OH)3 on surface of oil droplets, which led to the droplet coalescence. By increasing the Al3+ dosage, the sweep flocculation by Al(OH)3 precipitates occurred. Al3+ dosage for effective destabilization was increased in accordance with oil concentration. The formation of aluminum hydroxide precipitates in bayerite structure was affirmed by analyzing elemental composition and crystalline structure of flocs from the destablization.

Comparison of cutting-oil emulsion treatment by electrocoagulation-flotation in bubble column and airlift reactors.

ABSTRACT Separation of nanoscale oil droplets in the cutting-oil emulsion by electrocoagulation–flotation (ECF) was carried out in a bubble column reactor (BCR) and an external-loop airlift reactor (ALR). Under the batch operation, aluminium electrode provided the highest efficiency of 99% and required the shortest separating time compared to iron and graphite electrodes. The separation performance was also affected by the electrode gap and current density due to the amount of produced aluminium ions and turbulence by bubble motions. Additionally, the ECF efficiency obtained from the ALR was similar to that of the BCR. However, the ALR was preferable owing to its lower energy consumption, less electrode sacrifice, and less sludge production. Similar results were acquired under the continuous mode; nevertheless, the highest efficiency of only 85% was achieved from both reactors. It was found that the efficiency declined with increasing flow rates. According to the results suggested by the residence time distribution (RTD), the ALR was more effective at higher flow rates since the plug flow condition can be retained. On the other hand, an increase in flow rate also provoked the bypass flow to the down-comer of the ALR, resulting in the presence of a dead zone and reduction in the treatment efficiency.