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ABSTRACT
In this study, the effects of emulsion properties on demulsification of the phosphoric acid–tributyl phosphate (W/O) emulsion by hydrocyclone were investigated. The droplet size distributions were measured pre and post demulsification. The demulsification performance was evaluated by calculating the average droplet size difference. The results showed that increasing kerosene addition in the oil phase improved demulsification efficiency. As the maximum amount of kerosene added in the oil phase, average droplet size difference could reach about 43 µm. In each composition, as the stirring rate increased from 3000 to 7000 r/min, the effect of initial droplet size distribution on demulsification by hydrocyclone was not obvious. A model for predicting average droplet size difference was established by dimensional analysis method. By comparing the experimental data with calculated ones, this model is available.
Nomenclature
| a, b, c, d, e, f, g | = | constants |
| dj | = | droplet diameter (μm) |
| d43 | = | average droplet size (μm) |
| d43i | = | average droplet size of the emulsion pre-demulsification (μm) |
| d43u | = | average droplet size of the emulsion post-demulsification (μm) |
| D | = | inner diameter of joint of large cone part and small cone part (mm) |
| DSD | = | droplet size distribution |
| Di | = | inner diameter of inlet (mm) |
| Do | = | inner diameter of overflow pipe (mm) |
| h | = | height of cylindrical part (mm) |
| l | = | length of tail pipe (mm) |
| L | = | length |
| LLHC | = | liquid–liquid hydrocyclone |
| L | = | rotor diameter (m) |
| M | = | mass |
| N | = | stirring rate (s−1) |
| O/W | = | oil-in-water |
| PA | = | phosphoric acid |
| Po | = | power number |
| q3ln(x) | = | density distribution of droplet size |
| Q | = | inlet flow rate (L/min) |
| Q3 | = | function of volume cumulative distribution |
| Re | = | Reynolds number |
| T | = | time |
| TBP | = | tributyl phosphate |
| Vk | = | volume of the kerosene (mL) |
| VP | = | volume of the phosphoric acid (mL) |
| Vswept | = | impeller swept volume (m3) |
| VT | = | volume of TBP (mL) |
| W/O | = | water-in-oil |
| xi | = | lower limit of the divided range of DSD (μm) |
Greek letters
| α | = | angle of large cone part |
| β | = | angle of small cone part |
| ∆d43 | = | average droplet size difference (μm) |
| ∆ρ | = | density difference between two equilibrated phases (g/mL) |
| Δx | = | length of the divided range of DSD (μm) |
| ε | = | energy dissipation rate (W/kg) |
| μe | = | initial viscosity of the emulsion (cP) |
| ρa | = | density of the equilibrated aqueous phase (g/mL) |
| ρo | = | density of the equilibrated oil phase (g/mL) |
Acknowledgements
Project supported by the National Natural Science Foundation of China (No. 21776180, 21306116).