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.

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.

scholarly journals Decagram Synthesis of Dimethyl 1,4-Cubanedicarboxylate Using Continuous-Flow Photochemistry

Synthesis ◽  
2020 ◽  
Author(s):  
Bruno Linclau ◽  
Diego E. Collin ◽  
Edward H. Jackman ◽  
Nicolas Jouandon ◽  
Wei Sun ◽  
...  
Keyword(s):  
Residence Time ◽  
Continuous Flow ◽  
Scale Up ◽  
Process Time ◽  
Materials Chemistry ◽  
Highly Strained ◽  
Straightforward Approach

AbstractThe highly strained cubane system is of great interest as a scaffold and rigid linker in both pharmaceutical and materials chemistry. A straightforward approach is reported for the scale-up of a [2+2] photocycloaddition step using convenient home-made flow photoreactors to access dimethyl 1,4-cubanedicarboxylate on decagram-scale in 33–40% yield over 8 steps. The process is demonstrated on 3.4 g·h–1 input with 30 minutes residence time, enabling to reduce the process time and to avoid the use of batch photoreactors. Completion of the characterisation of the photocycloadduct and its hydrates is reported.

Continuous leaching of uranium from an Indian ore: Residence time scale up and heat effects

2014 ◽  
Vol 146 ◽  
pp. 119-127 ◽  
Author(s):  
K. Anand Rao ◽  
T. Sreenivas ◽  
Madhu Vinjamur ◽  
A.K. Suri
Keyword(s):  
Residence Time ◽  
Time Scale ◽  
Scale Up ◽  
Heat Effects

Scale-up of Nanoparticle Synthesis by Flame Spray Pyrolysis: The High-Temperature Particle Residence Time

2014 ◽  
Vol 53 (26) ◽  
pp. 10734-10742 ◽  
Author(s):  
Arto J. Gröhn ◽  
Sotiris E. Pratsinis ◽  
Antoni Sánchez-Ferrer ◽  
Raffaele Mezzenga ◽  
Karsten Wegner
Keyword(s):  
High Temperature ◽  
Spray Pyrolysis ◽  
Residence Time ◽  
Scale Up ◽  
Nanoparticle Synthesis ◽  
Flame Spray Pyrolysis ◽  
Flame Spray ◽  
Particle Residence Time

Scale-Up of Oscillatory Helical Baffled Reactors Based on Residence Time Distribution

2017 ◽  
Vol 40 (5) ◽  
pp. 907-914 ◽  
Author(s):  
Safaa M. R. Ahmed ◽  
Anh N. Phan ◽  
Adam P. Harvey
Keyword(s):  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Scale Up

Ultrafast and continuous-flow synthesis of AFX zeolite via interzeolite conversion of FAU zeolite

2021 ◽  
Vol 6 (1) ◽  
pp. 74-81
Author(s):  
Tatsushi Yoshioka ◽  
Zhendong Liu ◽  
Kenta Iyoki ◽  
Anand Chokkalingam ◽  
Yasuo Yonezawa ◽  
...  
Keyword(s):  
Residence Time ◽  
Continuous Flow ◽  
Secondary Nucleation ◽  
Flow Synthesis ◽  
Fau Zeolite ◽  
Zeolite P

Continuous-flow synthesis of AFX zeolite is achieved with the residence time of 10 min, using FAU zeolite as the silica and alumina source, and acid-leached seeds which promote secondary nucleation of AFX.

Studies on nucleation and crystal growth kinetics of plutonium(IV) oxalatex

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Chuanbo Li ◽  
Bo Wang ◽  
Xiang Li ◽  
Taihong Yan ◽  
Weifang Zheng
Keyword(s):  
Growth Rate ◽  
Crystal Growth ◽  
Nucleation Rate ◽  
Crystal Growth Rate ◽  
Acid Solutions ◽  
Dilution Ratio ◽  
Secondary Nucleation ◽  
Supersaturation Ratio ◽  
Crystal Growth Kinetics ◽  
Kinetics Of

Abstract A new method is developed to calculate the dilution ratio N of the two reactant solutions during nucleation rate determination. When the initial apparent supersaturation ratio S N  = f(N) in the dilution tank is controlled between 1.66 and 1.67, the counted nuclei is the most, both nuclei dissolving and secondary nucleation avoided satisfactorily. Based on this methoed, Plutonium(IV) oxalate is precipitated by mixing equal volumes of tetravalent plutonium nitrate and oxalic acid solutions. Experiments are carried out by varying the supersaturation ratio from 8.37 to 22.47 and temperature from 25 to 50 °C. The experimental results show that the nucleation rate of plutonium(IV) oxalate in the supersaturation range cited above can be expressed by the equation R N  = A N exp(−E a /RT)exp[−B/(ln S)2], where A N  = 4.8 × 1023 m−3 s−1 , and E a  = 36.2 kJ mol−1, and B = 20.2. The crystal growth rate of plutonium(IV) oxalate is determined by adding seed crystals into a batch crystallizer. The crystal growth rate can be expressed by equation G(t) = k g exp(−E’ a /RT) (c − c eq) g , where k g  = 7.3 × 10−7 (mol/L)−1.1(m/s), E’ a  = 25.7 kJ mol−1, and g = 1.1.

Continuous thermal hydrolysis and anaerobic digestion of sludge. Energy integration study

2012 ◽  
Vol 65 (10) ◽  
pp. 1839-1846 ◽  
Author(s):  
S. I. Pérez-Elvira ◽  
F. Fdz-Polanco
Keyword(s):  
Anaerobic Digestion ◽  
Residence Time ◽  
Pilot Plant ◽  
Scale Up ◽  
Green Energy ◽  
Point Of View ◽  
Thermal Hydrolysis ◽  
Economic Point ◽  
Gas Engine ◽  
Secondary Sludge

Experimental data obtained from the operation in a pilot plant are used to perform mass and energy balances to a global process combining units of thermal hydrolysis (TH) of secondary sludge, anaerobic digestion (AD) of hydrolysed secondary sludge together with fresh primary sludge, and cogeneration from biogas by using a gas engine in which the biogas produces electricity and heat from the exhaust gases. Three scenarios were compared, corresponding to the three digesters operated: C (conventional AD, 17 days residence time), B (combined TH + AD, same time), and A (TH + AD at half residence time). The biogas production of digesters B and A was 33 and 24% better, respectively when compared with C. In the case of the combined TH + AD process (scenarios A and B), the key factors in the energy balance were the recovery of heat from hot streams, and the concentration of sludge. The results of the balances showed that for 8% DS concentration of the secondary sludge tested in the pilot plant, the process can be energetically self-sufficient, but a fraction of the biogas must by-pass the gas engine to be directly burned. From an economic point of view, scenario B is more profitable in terms of green energy and higher waste removal, while scenario A reduces the digester volume required by a half. Considering a population of 100,000 inhabitants, the economic benefit is 87,600 €/yr for scenario A and 132,373 €/yr for B. This value can be increased to 223,867 €/yr by increasing the sludge concentration of the feeding to the TH unit to a minimum value that allows use of all the biogas to produce green energy. This concentration is 13% DS, which is still possible from a practical point of view. Additional benefits gained with the combined TH + AD process are the enhancement of the digesters rheology and the possibility of getting Class A biosolids. The integration study presented here set the basis for the scale-up to a demonstration plant.

Secondary nucleation rate of sodium chloride under different stirring conditions

1986 ◽  
Vol 78 (3) ◽  
pp. 528-532 ◽  
Author(s):  
Mohsen M. Akal ◽  
M. Zakaria ◽  
A. Ebrahim ◽  
Mamdouh M. Nassar
Keyword(s):  
Sodium Chloride ◽  
Nucleation Rate ◽  
Secondary Nucleation
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