scholarly journals Secondary Nucleation Kinetics of AIBN Crystallisation in Methanol: Online Imaging-Based Measurement and Modelling

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 506
Author(s):  
Yang Li ◽  
Yang Zhang ◽  
Xue Zhong Wang
Keyword(s):  
Nucleation Rate ◽  
Induction Time ◽  
Nucleation Process ◽  
Stirrer Speed ◽  
Seed Number ◽  
Nucleation Kinetics ◽  
Secondary Nucleation ◽  
On Line ◽  
Small Change ◽  
Crystal Seed

The secondary nucleation process of 2,2-azobisisobutyronitrile (AIBN) seeded crystallisation in methanol in a stirred tank reactor was studied at varying initial supersaturation levels, temperatures, crystal seed numbers, and stirrer speeds. The average secondary nucleation rate, induction time, and agglomeration ratio were measured using on-line microscopic imaging. The initial supersaturation level, temperature, and stirrer speed were found to be positively correlated with the secondary nucleation rate. A small change in the crystal seed number, i.e., 1-20, did not substantially affect the secondary nucleation rate throughout the secondary nucleation process. An increase in the initial supersaturation level and crystal seed number decreased the induction time, and an increase in the strength of agitation promoted the initiation of secondary nucleation at a stirring rate greater than 250 revolutions per minute (rpm). Temperature exerted a complex effect on the induction time. Regarding the agglomeration ratio, the initial supersaturation level positively correlated with the agglomeration ratio, while the stirrer speed negatively correlated with this parameter. Finally, based on the measured data, the average secondary nucleation rate, induction time, and final crystal suspension density were correlated. This study provides guidance for the control of supersaturation, induction time, stirring, and other factors in the crystal seed addition process in AIBN crystallisation.

Nucleation Kinetics for Boiling in Microstructures

2005 ◽  
Author(s):  
J. F. Lu ◽  
X. F. Peng ◽  
B. Bourouga
Keyword(s):  
Kinetic Equation ◽  
Dynamic Characteristics ◽  
Nucleation Rate ◽  
Critical Radius ◽  
Momentum Conservation ◽  
Bubble Nucleation ◽  
Nucleation Process ◽  
Nucleation Kinetics ◽  
Bubble Evolution ◽  
Two Stages

Theoretical investigation is conducted to understand the bubble nucleation process in microstructures. The bubble evolution in microstructures is investigated for momentum conservation, and the evolution rate is deeply dependent on the structure. According to different dynamic characteristics in the region close to the critical radius, the nucleation process is divided into two stages. Based on the characteristics of these two stages, a nucleation kinetic equation is modified from classical theory and then is conducted to understand the special bubble nucleation process. The result concludes that the nucleation rate will be deduced if bubble evolution is restrained in microstructures.

scholarly journals Effect of Propane and NaCl-SDS Solution on Nucleation Process of Mine Gas Hydrate

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Qiang Zhang ◽  
Qiang Wu ◽  
Hui Zhang
Keyword(s):  
Gas Hydrate ◽  
Induction Time ◽  
Equilibrium Points ◽  
Sodium Dodecyl ◽  
Hydrate Formation ◽  
Nucleation Process ◽  
Nucleation Kinetics ◽  
Gas Hydrate Formation ◽  
Experimental Apparatus ◽  
Mine Gas

In order to explore the method of accelerating hydration separation process to recover methane from mine gas, propane hydrate phase equilibrium was used to measure the equilibrium points of three kinds of mine gas in NaCl solution. Driving force was set as 1 MPa on this basis and high-pressure experimental apparatus of mine gas hydrate was used to carry out the nucleation kinetics experiments of mine gas hydrate for three gas samples in different concentrations of sodium chloride (NaCl) and sodium dodecyl sulfate (SDS) compound systems, which was to study the effect of propane and NaCl-SDS solution on nucleation process of mine gas hydrate. The results showed that induction time of multicomponent mine gas hydrate formation was shortened with the decrease of methane concentration and increase of propane concentration. The induction time of mine gas hydrate formation was shortened with the reduction of NaCl concentration and the increase of SDS concentration. It was found that methane and propane in multicomponent mine gas nucleated collaboratively, which simplified its nucleation process compared with the single component. NaCl has two kinds of functions.

scholarly journals Monitoramento da cristalização da lactose em soro concentrado

2017 ◽  
Vol 72 (4) ◽  
pp. 215-226
Author(s):  
Ítalo Tuler Perrone ◽  
João Pablo Fortes Pereira ◽  
Isis Rodrigues Toledo Renhe ◽  
Júlia D’Almeida Francisquini ◽  
Rodrigo Stephani ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Soluble Solids ◽  
Nucleation Process ◽  
Secondary Nucleation ◽  
Primary Nucleation ◽  
Industrial Setting ◽  
Mathematical Equations ◽  
Average Size ◽  
Two Stages ◽  
Kinetics Of

The kinetics of lactose crystal growth in concentrated whey were studied in two stages. The first took place in a bench-top crystallizer and the second in an industrial crystallizer using concentrated whey obtained by vacuum evaporation, consisting of 3 treatments: crystallization by primary nucleation, by secondary nucleation with the addition of 0.05% and with the addition of 0.1% microcrystalline lactose. The average size of the crystals remained between 60.7 mm and 63.8 mm. The percentage of crystallization was greater in the secondary nucleation process than in the primary nucleation, where crystallization stabilized first. Mathematical equations which independently related crystallization times of the concentrated whey to the concentrations of soluble solids, crystallization percentage and mass of lactose in water were established, that can be used in the industrial setting to process whey. The kinetics of lactose crystal growth was not well described by models of first or second order reactions.

scholarly journals Ultrasound in Continuous Tubular Crystallizers: Parameters Affecting the Nucleation Rate

Crystals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1054
Author(s):  
Arne Vancleef ◽  
Tom Van Gerven ◽  
Leen C. J. Thomassen ◽  
Leen Braeken
Keyword(s):  
Residence Time ◽  
Nucleation Rate ◽  
Static Pressure ◽  
Scale Up ◽  
Ultrasonic Power ◽  
Secondary Nucleation ◽  
Process Understanding ◽  
Ultrasonic Process ◽  
Good Scale ◽  
Equal Power

Ultrasound has proven to be an important tool for controlling nucleation in continuous tubular crystallizers. However, insufficient information is available about the parameters controlling the nucleation rate in a continuous ultrasonic process. Previous research has studied parameters related to the nucleation rate, but has not measured the nucleation rate directly or continuously. In this work, the nucleation rate is measured continuously and inline to solve this problem and achieve a better process understanding. The results indicate that the ultrasound-assisted nucleation process is presumably dominated by secondary nucleation. Additionally, the supersaturation, residence time and flow rate have a strong influence on the nucleation rate. On the other hand, the influence of the ultrasonic power is crucial but levels off once a certain amount of power is reached. The static pressure in the system determines the effective ultrasonic power and is therefore also important for the nucleation rate. Finally, maintaining an equal power per unit of volume and an equal residence time by increasing the tubing diameter seems to be a good scale-up method. These results will improve understanding of ultrasonic tubular crystallizers and how to control them.

Measurement of nucleation rate of ibuprofen in ionic liquid using induction time method

2019 ◽  
Vol 521 ◽  
pp. 55-59 ◽  
Author(s):  
S. Karthika ◽  
T.K. Radhakrishnan ◽  
P. Kalaichelvi
Keyword(s):  
Ionic Liquid ◽  
Nucleation Rate ◽  
Induction Time
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