The objective of this work is to study the reactive crystallization in an airlift-loop reactor （ALR） using the precipitation of Ni（OH）2 as a model reaction. The growth of Ni（OH）2 particles in an ALR and a stirre...The objective of this work is to study the reactive crystallization in an airlift-loop reactor （ALR） using the precipitation of Ni（OH）2 as a model reaction. The growth of Ni（OH）2 particles in an ALR and a stirred tank was quantified by scanning electronic microscope （SEM）, X-ray diffraction （XRD）, laser particle analyzer, tap densitometer and optical microscope, and the growth process of Ni（OH）2 particles is analyzed. It is found that the Ni（OH）2 particles prepared in an ALR have a better sphericity than those in a stirred tank and the growth of Ni（OH）2 particle tap density mainly depends on the size of crystallites： the bigger the size of crystallites, the bigger the tap density is. Based on these, the growth process of Ni（OH）2 particles in ALR is elaborated. Crystallites precipitated from solution aggregate to form large particles with much void. These constituting crystallites continue to grow up, that takes up the void inside particles and makes the tap densitv increase.展开更多
The investigation of hydrodynamic behavior in three-phase external loop airlift reactors is important to their design and scale-up. Pressure difference was used to measure gas holdup and ultrasonic Doppler anemometry ...The investigation of hydrodynamic behavior in three-phase external loop airlift reactors is important to their design and scale-up. Pressure difference was used to measure gas holdup and ultrasonic Doppler anemometry was used to measure liquid velocity. Gas holdup, liquid velocity and expansion rate increased with increasing superficial gas velocity. Under the same superficial gas velocity, gas holdup increased with increasing static solid height, and decreased with increasing solid particle diameter.Adding large particles could increase interfacial area, increase gas residual time and intensify mass transfer. Liquid circulation velocity and expansion rate decreased with increasing solid particle diameter and static solid height.Liquid velocity could be controlled in a suitable range by adding particles to improve the performance in airlift loop reactors.展开更多
基金Supported by the National Key Research and Development Program(2016YFB0301701)the National Natural Science Foundation of China(21406236,91434126)+1 种基金the Major National Scientific Instrument Development Project(21427814)Jiangsu National Synergetic Innovation Center for Advanced Materials
文摘The objective of this work is to study the reactive crystallization in an airlift-loop reactor （ALR） using the precipitation of Ni（OH）2 as a model reaction. The growth of Ni（OH）2 particles in an ALR and a stirred tank was quantified by scanning electronic microscope （SEM）, X-ray diffraction （XRD）, laser particle analyzer, tap densitometer and optical microscope, and the growth process of Ni（OH）2 particles is analyzed. It is found that the Ni（OH）2 particles prepared in an ALR have a better sphericity than those in a stirred tank and the growth of Ni（OH）2 particle tap density mainly depends on the size of crystallites： the bigger the size of crystallites, the bigger the tap density is. Based on these, the growth process of Ni（OH）2 particles in ALR is elaborated. Crystallites precipitated from solution aggregate to form large particles with much void. These constituting crystallites continue to grow up, that takes up the void inside particles and makes the tap densitv increase.
文摘The investigation of hydrodynamic behavior in three-phase external loop airlift reactors is important to their design and scale-up. Pressure difference was used to measure gas holdup and ultrasonic Doppler anemometry was used to measure liquid velocity. Gas holdup, liquid velocity and expansion rate increased with increasing superficial gas velocity. Under the same superficial gas velocity, gas holdup increased with increasing static solid height, and decreased with increasing solid particle diameter.Adding large particles could increase interfacial area, increase gas residual time and intensify mass transfer. Liquid circulation velocity and expansion rate decreased with increasing solid particle diameter and static solid height.Liquid velocity could be controlled in a suitable range by adding particles to improve the performance in airlift loop reactors.
