| As a novel type of process intensification equipment, high shear mixers (HSMs)have advantages of quickly micro-mixing and intensifying transfer process, so it havegreat potential to be applied to gas-liquid system, gas-liquid-solid system,gas-liquid-liquid system, for example absorption, extraction, mixing, etc. Theperformance of inline high shear mixers for the multi-phase systems was studied inthis thesis.Firstly, single-pass continuous emulsifications were studied in kerosene-andsilicone oil-aqueous systems with the inline high shear mixers (HSMs) adopting twomain commercial configurations, including the dual rows ultrafine teethed and thesingle-row blade-screen units. The effects of the processing parameters on themeasured drop sizes and power consumptions were investigated. Bimodal drop sizedistributions (DSDs) were observed within both in-line HSMs due to theinhomogeneity of the turbulence and shear levels accompanied with the recirculationand re-entrainment flow pattern. The drop sizes increase with the dispersed phasevolume fraction and the continuous phase flowrate while decrease with the rotorspeed and the continuous phase viscosity. Correlations for the Sauter mean diameterswere also obtained.Secondly, the mass transfer characteristics of a gas-liquid continuous flow systemaccompanied by reaction in two commercial in-line high shear mixers (HSMs) wereevaluated by the sulphite oxidation method. The gas-liquid specific interfacial area, a,and the volumetric mass transfer coefficient, kLa were measured under differentoperating conditions involving the rotor speed, the liquid flowrate, the gas flowrate,the liquid viscosity and the surface tension. The results indicate that a and kLaincrease with the rotor speed and liquid flowrate due to an increase of turbulenceintensity, while decrease with the liquid viscosity as a result of the damping ofturbulence and the increase of mass transfer resistance. Both parameters increaseslightly first but then decrease with the gas flowrate. For either the dual rowsultrafine-toothed or the single-row blade-screen configuration of HSMs, a increaseswhile kLa decreases with the surfactant concentration, and both of them tend to bechangeless at the surfactant concentration higher than30mg/L. Lastly, Needle-like aragonite was synthesized from CO2-Ca(OH)2carbonationprocess in the high shear mixer (HSM) with H3PO4as the additive, characterizedusing SEM and XRD. Effects of some key parameters such as the additiveconcentration, the flowrate of CO2, the reaction temperature, and the configuration ofHSM were investigated. It is found that the HSM configuration, the additiveconcentration and reaction temperature are the important parameters affecting thecontent of aragonite in the product. High aragonite yield is obtained in the HSM witha H3PO4concentration of6.4g/L, a reaction temperature of83oC, and a CO2flowrateof8.4L/h. A potential method for the industrial production of aragonite has beenidentified via the HSM, which needs short reaction time while maintaining higharagonite purity (~97.9%) and yield. |
