In‐line Control and Automatic Management of Industrial Crystallizations using NIR Technique

Vaccari, G.; Tamburini, Elena; Tosi, S.; Sgualdino, G.; Bernardi, Tatiana

doi:10.1002/ceat.200390040

Cited by 4 publications

(2 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Parallel trend lines were drawn based on a reference trend line, which is estimated from the performed experiments at different initial relative supersaturations using seed crystals of size of (251±10) μm. (Online color at www.crtjournal.org) Surface free energy and the role of the enthalpy of immersion The width of the metastable zone for sucrose homogeneous nucleation from its aqueous solutions at various temperatures was found to be S ≈ 1.35 [20,33,34]. The mentioned value of S results when expressing the supersaturation by S = c/c * , where c is the concentration of sucrose in solution in grams per 100 g of water, and c * is the concentration of sucrose saturated solution at the same temperature, and it corresponds to a relative supersaturation in terms of activity σ = 0.613 at T = 313.15 K. The width of the metastable zone for a secondary nucleation case in this work is found to be S ≈1.14, that when the characteristic size of the used seed crystals is (251.1 ± 10) μm.…”

Section: Discussionmentioning

confidence: 98%

Metastable zone width for secondary nucleation and secondary nucleation inside the metastable zone

Khaddour¹,

Rocha²

2011

Cryst. Res. Technol.

View full text Add to dashboard Cite

Key words metastable zone width, interfacial free energy, nucleation, growth from solution.This study presents an evaluation of a new method, called zero growth activation free energy, used to determine the metastable zone width for the secondary nucleation case. It predicts the metastable zone width with a maximum error of 5-10%. Estimation of the metastable zone width for different isothermal crystallization conditions can be modeled according to a chosen reference set of growth experiments carried out in the volume diffusion regime at different initial supersaturations, using seed crystals of a certain characteristic size. Moreover, the activation free energy of the secondary nucleation was estimated. The role of the enthalpy of immersion in the formation of secondary nucleation events inside the metastable zone was pointed out, as well as its effect in causing extra-fast growth rate. Furthermore, sucrose crystal surface free energy was estimated.

show abstract

Section: Discussionmentioning

confidence: 98%

Metastable zone width for secondary nucleation and secondary nucleation inside the metastable zone

Khaddour¹,

Rocha²

2011

Cryst. Res. Technol.

View full text Add to dashboard Cite

show abstract

“…Attempts have been made to employ more sophisticated technology. For example, Vaccari et al 6 utilized an NIR (near infrared) technique in the cooling crystallization of pure sugar, as a first approach to automatic crystallization management. Schultz and Edye 7 continuously measured the crystal content in a pilot vacuum pan using low resolution NMR (nuclear magnetic resonance) instrumentation.…”

Section: Introductionmentioning

confidence: 99%

Modeling Sucrose Evaporative Crystallization. Part 1. Vacuum Pan Monitoring by Mass Balance and Image Analysis Methods

Martins

Rocha

Rein

2005

Ind. Eng. Chem. Res.

View full text Add to dashboard Cite

Sugar boiling experiments were carried out in a pilot vacuum pan with the aim of developing new methods for monitoring and estimation of important variables in industrial crystallization. A mathematical model based on mass balances was applied, using typical on-line data recorded during the boiling runs, to determine the evolution of parameters related to the crystal content and liquor purity. In a subsequent paper (Part II), the conclusions resulting from the application of the mass balance method will be used in a study of crystal growth kinetics of sucrose in industrial and synthetic syrups. In a different approach, in situ images were captured and processed for the purpose of estimating the mean crystals size progress at the early stages of the strikesimage analysis method. A strategy is proposed to solve the problems associated with the identification of crystals in images taken directly from the suspension. The results obtained by the two methods were compared, showing good agreement both in the range of the crystal sizes and in the way crystal size changes.

show abstract

Monitoring Batch Cooling Crystallization Using NIR: Development of Calibration Models Using Genetic Algorithm and PLS

Wang

Abebe

2008

Part & Part Syst Charact

View full text Add to dashboard Cite

Near infrared spectroscopy (NIR) uses fiber‐optics for rapid data transmission, is robust, simple, and sensitive at both low and high solution concentrations. Therefore, it is particularly suitable for monitoring industrial processes. This study investigates the use of NIR for monitoring batch cooling crystallization processes, and emphasis is placed on applying genetic algorithm (GA) for wavelength selection in partial least squares calibration model development. The calibration data was collected for under‐saturated and saturated solutions, as well as for α‐ and β‐form crystal slurries of L‐glutamic acid at a variety of solution concentrations, temperatures, and solid concentrations and sizes. The GA method proves to be capable of effectively selecting a small number of wavelengths and the models thus developed give improved prediction performance in terms of generalization capability compared to models derived using the full spectrum. The developed models are successfully applied to monitoring batch cooling crystallization of L‐glutamic acid under seeded and unseeded conditions and with varied cooling rates.

show abstract

In‐line Control and Automatic Management of Industrial Crystallizations using NIR Technique

Cited by 4 publications

References 3 publications

Metastable zone width for secondary nucleation and secondary nucleation inside the metastable zone

Metastable zone width for secondary nucleation and secondary nucleation inside the metastable zone

Modeling Sucrose Evaporative Crystallization. Part 1. Vacuum Pan Monitoring by Mass Balance and Image Analysis Methods

Monitoring Batch Cooling Crystallization Using NIR: Development of Calibration Models Using Genetic Algorithm and PLS

Contact Info

Product

Resources

About