Mass transfer during air humidification in spouted beds

Abstract

This article presents the results obtained from analysing the impacts of bed media, static bed height, and the water-to-air mass flow ratios on the mass transfer coefficient and Colburn factor. The experimental data were compared with the correlations for mass transfer and the analogy between heat and mass transfer in conical spouted beds described earlier in literature. Moreover, the aim of the article is to present some new correlations of dimensionless groups for description of mass transfer and analogy of heat and mass transfer in sprayed spouted beds, which were developed by the authors.Cet exposé présente les résultats obtenus suiteà l'analyse de l'impact du médium et de la hauteur statique du lit, des rapports d'écoulement de la masse eau-air sur le coefficient de transfert de masse et le facteur de Colburn. Les données expérimentales ontété comparées aux corrélations pour le transfert de masse età l'analogie entre le transfert de chaleur et de masse dans des lits jaillissants coniques décrits plus tôt dans la documentation. En outre, le but de l'article est de présenter quelques nouvelles corrélations de groupes adimensionnels, développées par les auteurs, en vue de décrire le transfert de masse et l'analogie du transfert de chaleur et de masse dans les lits jaillissants pulvérisés.

Bed-to-surface heat transfer in conical spouted beds of biomass–sand mixtures

“…Spouted beds are typically used for drying, so that studies of heat transfer reported in the literature are mainly centered on that process [22][23][24][25][26]. Several authors have developed mechanistic models for heat transfer in spouted bed drying, requiring sophisticated numerical and mathematical methods for solving systems of differential equations [4,21,[27][28][29][30].…”

Correlation for Calculating Heat Transfer Coefficient in Conical Spouted Beds

“…Although spouted bed technology has already been implemented in many applications, being the subject of numerous studies involving hydrodynamics and gas and solid flow patterns, heat transfer is a point that has been scarcely approached in the literature. Thus, certain authors have studied the influence of temperature on hydrodynamics, − but heat transfer itself has hardly been addressed, with drying being the main subject approached by most papers related to heat transfer. − In fact, drying has so far been the main and more popular application of spouted beds. Nevertheless, conical spouted beds have also performed well in the pyrolysis of biomass, plastics, and tires .…”

Analysis of maximum pressure drop for a flat-base spouted fluid bed

“…Due to this unique hydrodynamic behavior,spouted beds have been used in many applications such as pyrolysis (Arabiourrutia et al, 2007;Makibar et al, 2012), combustion (Rasul,2001), gasification (Bernocco et al, 2013), coating (Martins et al, 2008) and drying (Benelli et al, 2013). The main advantage of the spouted bed is a cyclic pattern of solids movement which enhances the heat and mass transfer between gas and solids as well as the long solids residence time (Makibar et al 2011,Kmiec et al 2009.However, there areimportant limitationssuch aslow annulus aeration which may cause dead zones and particle agglomeration, high pressure drop prior to onset of spouting, and slow solids turnover (Rovero et al, 2012).One of many modifications to the spouted bed is spouted fluidized bed (Zhong et al, 2006(Zhong et al, , 2008 which is achieved by introducing additional gas flow into annular region of a spouted bed. The spouted fluidized bed reduces the particle agglomeration, improves the gassolid contact, and enhances mixing.…”