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Electro-spray of high viscous liquids for producing mono-sized spherical alginate beads

Particuology 2008年第4期6卷 271-275页

作者： Hamid Moghadam Mohsen Samimi Abdolreza Samimi Mohamad Khorram Chemical Engineering Department University of Sistan and Baluchestan

Alginate beads, often used for controlled release of enzymes and drugs, are usually produced by spraying sodium alginate liquid into a gelling agent using mechanical vibration nozzle or air jet. In this work an alternative method of electro-spray was employed to form droplets with desired size from a highly viscous sodium alginate solution using constant DC voltage. The droplets were then cured in a calcium chloride solution. The main objective was to produce mono-sized beads from such a highly viscous and non-Newtonian liquid (1000–5000 mPa s). The effects of nozzle diameter, flow rate and concentration of liquid on the size of the beads were investigated. Among the parameters studied, voltage had a pronounced effect on the size of beads as compared to flow rate, nozzle diameter and concentration of alginate liquid. The size of beads was reduced to a minimum value with increasing the voltage in the range of 0–10 kV. At the early stages of voltage increase (i.e. up to about 4 kV), the rate of size reduction was relatively low, while the dripping mode dominated. However, in the middle part of the range of applied voltage, where the rate of size reduction was high (i.e. about 4–7 kV), an unstable transition occurred between dripping and jetting. At the end part of the range (i.e. 7–10 kV) jet mode of spray was observed. Increasing the height of fall of the droplets was found to improve the sphericity of the beads, because of the increased time of flight for the droplets. This was especially identifiable at higher concentrations of the alginate liquid (i.e. 3 w/v%).

关键词： Electro-spray highly viscous liquid Constant DC electric field Alginate beads

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A Mass Transfer Model for Devolatilization of highly viscous Media in Rotating Packed Bed

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Chinese Journal of Chemical Engineering 2010年第2期18卷 194-201页

作者：李沃源毋伟邹海魁初广文邵磊陈建峰 Research Center of the Ministry of Education for High Gravity Engineering and Technology College of ChemicalEngineering Beijing University of Chemical Technology Beijing 100029 China

A mass transfer model for devolatilization process of highly viscous media in rotating packed bed(RPB) was developed based on penetration theory and mass *** establishing the model,some mass transfer experiments of thin film were conducted in a designed diffusion cell including vacuum and feeding system. In this study,acetone was used as the volatile organic compound(VOC) and syrup as the highly viscous *** thickness of thin film was changed by using different liquid *** was found that bubbling played an important role in the *** correlation of diffusion coefficient of acetone in highly viscous dilute solution was *** relative error between predicted and experimental data was within the range of ± 30% for diffusion coefficient of acetone in syrup.A comparison of experimental data of RPB with model indicated that the relative error was within ± 30% for efficiency of acetone removal.

关键词： mass transfer highly viscous liquid volatile organic compound diffusion coefficient rotating packed bed

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