Analysis of the fluid-dynamic behavior of fluidized and vibrofluidized bed containing glycerol

Daleffe, R. V.; Freire, José Teixeira

doi:10.1590/s0104-66322004000100005

Cited by 19 publications

(8 citation statements)

References 4 publications

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“…The product properties and the conditions of stable operation that result in the removal of solids without agglomeration of the inert particles are dependent on the system configuration and several operating parameters such as the flow rates of the liquid material and of the drying gas and the physical and chemical properties of the solid and liquid materials (Spitzner-Neto et al, 2002;Maialle et al, 2002;Souza andOliveira, 2002, 2005;Medeiros et al, 2002;Kudra, 2003;Daleffe and Freire, 2004).…”

Section: Introductionmentioning

confidence: 99%

The Role of Colloidal Silicon Dioxide in the Enhancement of the Drying of Herbal Preparations in Suspended State

Souza

Donida

Rocha

et al. 2008

Chemical Engineering Communications

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Recently, some research groups have been developing studies aiming to apply spouted beds of inert particles for production of dried herbal extracts. However, mainly due to their complex composition, several problems arise during the spouted bed drying of herbal extracts such as bed instability, product accumulation, particle agglomeration, and bed collapse. The addition of drying carriers, like colloidal silicon dioxide, to the extractive solution can minimize these unwanted effects. The aim of this work was to study the influence of the addition of colloidal silicon dioxide on enhancement of the performance of the drying of hydroalcoholic extract of Bauhinia forficata Link on a spouted bed of inert particles. The physical properties of the herbal extract and of its mixture with colloidal silicon dioxide at several concentrations (20% to 80% related to solids content) were quantified by determination of the surface tension, rheological properties, density, pH, and contact angles with the inert surfaces. Drying performance was evaluated through determination of the elutriation ratio, product recovery ratio, and product accumulation. The product was characterized through determination of the thermal degradation of bioactive compounds and product moisture content. The results indicated that the rheological properties of the extracts and their preparations, the contact angle with inert material, and the work of adhesion play important roles in the spouted bed drying of herbal extracts. Higher concentration of the drying carrier significantly improved the spouted bed drying performance.

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Section: Introductionmentioning

confidence: 99%

The Role of Colloidal Silicon Dioxide in the Enhancement of the Drying of Herbal Preparations in Suspended State

Souza

Donida

Rocha

et al. 2008

Chemical Engineering Communications

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“…There is a lot of research in the literature that reports fluid dynamic behavior in gas-solid vibrofluidized beds with particles of uniform size (Bratu and Jinescu, 1971;Gupta and Mujumdar, 1980;Daleffe and Freire, 2004). However, little work has been focused on the effects of particle size distribution on fluid dynamic behavior and on the occurrence of segregation.…”

Section: Introductionmentioning

confidence: 99%

Effects of binary particle size distribution on the fluid dynamic behavior of fluidized, vibrated and vibrofluidized beds

Daleffe

Ferreira

Freire

2008

Braz. J. Chem. Eng.

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-In this work the effects of particle size distribution on the dynamics and segregation patterns in fluidized, vibrated and vibrofluidized beds were investigated. A binary particle size distribution and a reference one composed of glass spheres with a mean Sauter diameter of 2.18×10 -3 m were tested. The experimental setup consisted basically of a circular glass chamber with a height of 0.50 m and a diameter of 0.114 m, operated in the fluidized bed mode ( = 0.00), in either vibrated or vibrofluidized bed modes ( = 2.00). The pressure drops in the fluidized and vibrofluidized beds were not significantly affected by the binary particle size distribution. Well-defined segregation patterns occurred in fluidized and vibrated beds with small particles concentrating at the top and large particles at the bottom in the first situation and the reverse in the second one. Segregation patterns in vibrofluidized beds depended on the values of vibration parameters. Segregation in vibrofluidized and vibrated beds was minimized by operating at a high amplitude of vibration.

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“…In small-scale production, the conical spouted bed dryer is pointed to as a more promising technique for processing viscous and thermal sensitive suspensions (Spitzner Neto et al, 2002;Trindade et al, 2004;Bacelos et al, , 2007 than other techniques, such as fluidization (Daleffe and Freire, 2004) or spray-drying (Birchal et. al., 2005(Birchal et.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of flow in wet conical spouted beds of unequal-sized spherical Particles

Bacelos

Passos

Freire

2008

Braz. J. Chem. Eng.

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Interparticle forces, developed in wet spouted beds composed of a mixture of spherical particles with different size distributions, intensify particle segregation mechanisms interfering in gas distribution inside the bed and, consequently, in the spouting flow characteristics. Therefore, this paper is aimed at describing the effect of interparticle forces on the air-solid flow distribution in conical spouted beds of unequal-sized particles coated by a thin glycerol film. Experimental results show that both the minimum spouting airflow rate and the minimum spouting pressure drop decrease as the amount of glycerol added to the bed increases. In addition, simulated results of the annular air velocity along the bed height showed that, at the base of the column, the radial component of the inertial force is high enough to break liquid bridges between particles and carry these particles out along the spout. Moreover, as the glycerol concentration increases, the spout diameter increases along the bed height. Such changes in the air-solid flow can maintain the spouting regime for higher glycerol concentrations as shown by experimental data

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Analysis of the fluid-dynamic behavior of fluidized and vibrofluidized bed containing glycerol

Cited by 19 publications

References 4 publications

The Role of Colloidal Silicon Dioxide in the Enhancement of the Drying of Herbal Preparations in Suspended State

The Role of Colloidal Silicon Dioxide in the Enhancement of the Drying of Herbal Preparations in Suspended State

Effects of binary particle size distribution on the fluid dynamic behavior of fluidized, vibrated and vibrofluidized beds

Characteristics of flow in wet conical spouted beds of unequal-sized spherical Particles

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