Supersaturation tracking for the development, optimization and control of crystallization processes

Jiang

Chemical Engineering Research and Design

et al. 2015

Section: ␤-Artemethermentioning

confidence: 99%

Metastable zone width, crystal nucleation and growth kinetics measurement in anti-solvent crystallization of β-artemether in the mixture of ethanol and water

Jiang

Chemical Engineering Research and Design

et al. 2015

“…The development of this model involves the fundamental theories and models in membrane process and crystallization engineering, especially the models described the polarization phenomenon on membrane interface 28,29 and the CSD determined by both nucleation and crystal growth processes. [30][31][32][33][34] Little research had been reported on this combined process model development.…”

Section: Introductionmentioning

confidence: 98%

Membrane assisted cooling crystallization: Process model, nucleation, metastable zone, and crystal size distribution

Jiang

Xiao

et al. 2015

AIChE Journal

The membrane assisted cooling crystallization was proposed and investigated by the simulation and experiments. The developed process model concerned the supersaturation evolution on the membrane interface, the combined nucleation rate in the crystallizer. The impact of different membrane on reducing the nucleation barrier was investigated by introducing the metastable zone width theory. The influence of membrane distillation conditions on the crystal nucleation and growth kinetic was uncovered based on the simulation and experiments results. The experimental results indicated that membrane assisted cooling mode with optimized profiles did improve the crystal size distribution and crystal habit comparing with conventional cooling mode. Terminal coefficient of variation decreased from 55.4 to 33.9 under similar mean crystal growth rate, 2.27 3 10 27 m s 21 (conventional cooling) and 1.98 3 10 27 m s 21 (membrane assisted cooling). Finally, the brief summary on the advantages and key issues of this propose membrane assisted crystallization operation were concluded. V C 2015 American Institute of Chemical Engineers AIChE J, 62: [829][830][831][832][833][834][835][836][837][838][839][840][841] 2016

Journal of Crystal Growth

“…ATR-FTIR [4,31,32) or electrochemical in-situ monitoring (e.g. ionselective electrodes [33][34][35] or conductivity probes).…”

Section: Introductionmentioning

confidence: 99%

The crystal growth kinetics of alpha calcium sulfate hemihydrate in concentrated CaCl2–HCl solutions

Feldmann

Demopoulos²

2012

The crystal growth kinetics of calcium sulfate α-hemihydrate (α-HH) in nearly constant supersaturated HCl-CaCl 2 solutions were investigated. Two types of solutions were used, the first had a low HCl (1.4 mol/L) and high CaCl 2 (2.8 mol/L) concentration and the second had a high HCl (5.6 mol/L) and low CaCl 2 (0.7 mol/L) concentration. These conditions were chosen to represent the first and last stage of a newly developed stage-wise HCl regeneration process. The seeded growth experiments were carried out in a stirred, temperature controlled semi-batch reactor in which supersaturation was kept constant by simultaneous addition of CaCl 2 and Na 2 SO 4 solutions. The influence of the following parameters on α-HH crystal growth was studied: temperature (70-95°C), specific power input of stirring (0.02-1.29 W/kg) and equimolar inflow rate of CaCl 2 and Na 2 SO 4 (0-0.6 mol/h). The crystal growth rate was derived from particle size distribution measurements made with the laser light diffraction technique. It was found that the surface area normalized crystal growth rate increased linearly with the molar inflow rate up to 0.3 mol/h, at higher inflow rates no further increase of the growth rate was observed. Temperature and specific power input, within the investigated ranges, did not show a marked effect on the growth rate, attributable to a diffusion/adsorption controlled growth process. An interesting finding of the present research is the establishment of a positive relationship between the narrowing of the width of the particle size distribution with increasing crystal growth rate. The results show that the resulting particle size distribution is positively related to the reagent inflow rate, a finding that can be applied to the industrial design and scale-up of the α-HH crystallization/HCl regeneration process.