Characterization of local flow behaviour in conical spouted beds

Yeniçeri, Ali
Conical spouted beds are used in various physical and chemical applications such as drying, coating, and pyrolysis of waste plastic and biomass owing to their effective feature of gas-solid contact. To design and operate these units in high efficiency, a complete understanding of the phenomena and detailed investigation of local flow structure are of paramount importance. In this study, the effects of bed design parameters (unit size, conical angle, spouting gas-inlet diameter) and operational conditions (particle density, axial position) on bed local flow structure were investigated in detail. Experiments were performed in small and large conical spouted beds by using light and heavy particles with varying density (2460 kg/m3 ≤ ρp ≤ 6050 kg/m3). To observe the effects on local flow structure, an optical probe system was used. Additionally, an empirical correlation was proposed to predict the solids hold-up at the spout center (r = 0) for light and heavy particles. The investigated parameters caused significant changes in spout region while the annulus region was found to be unaffected. The particle velocity decreased and solids hold-up and particle flux increased from the bed bottom to the bed surface. Using larger gas-inlet diameter decreased the particle flux in the spout. An increase in cone angle caused a major decrease in particle flux. Introducing fluidizing gas through the conical section to the system caused minimal effect on particle flux, resulting in only 8% increase in the spout region. Particle velocity and solids hold-up did not significantly change in presence of fluidizing gas.


Gas mixing in conical spouted beds
Doğan, Neslin; Külah, Görkem; Department of Chemical Engineering (2020-12-28)
Conical spouted beds are relatively new generation gas-solid flow reactors used in various applications such as drying, catalytic polymerization, treatment of wastes, particle coating and chemical vapor deposition due to their advantages over cylindrical spouted beds. For complete characterization of conical spouted beds, determination of the local flow structure based on gas velocity and gas mixing is of paramount importance. There are limited studies on local gas behavior in conical spouted beds, especial...
Evaluation of a sand bentonite mixture as a shaft/borehole sealing material
Akgün, Haluk (2018-11-01)
The mechanical and hydrological characteristics of compacted sand bentonite mixtures with bentonite contents ranging from 5 to 40% were investigated in the laboratory in order to assess their use as a waste isolation material and to select an optimum sand bentonite mixture. Laboratory tests included compaction, compaction permeability, unconfined compression and direct shear tests which led to a recommendation to select a mixture with a bentonite content of 30% for the isolation of underground geological wa...
Development of electrically conductive porous silk fibroin/carbon nanofiber scaffolds
Tufan, Yiğithan; Ercan, Batur; Department of Metallurgical and Materials Engineering (2020-8)
Tissue engineering applications typically require porous scaffolds which provide requisite surface area for cellular functions, while allowing nutrient, waste and oxygen transport with the surrounding tissues. Concurrently, scaffolds should ensure sufficient mechanical properties to provide mechanically stable frameworks under physiologically relevant stress levels. Furthermore, electrically conductive platforms are also desired for the regeneration of specific tissues, where electrical impulses are transmi...
Characterization of clay rock samples of a borax ore in relation to their problematical flocculation behavior
ÇIRAK, MUSTAFA; Hoşten, Çetin (2015-11-01)
Beneficiation process in the Kirka Borax Concentrator in Turkey generates a tailings effluent containing 3-10% solids that are composed mainly of colloidal particles of clay-rock-type gangue minerals and some unrecoverable borax fines. These colloidal particles form very stable aqueous suspensions in the tailings, hindering solid/liquid separation and clean water recovery. This leads to difficulties in the sustainable and environmentally acceptable operation of the concentrator. Flocculation studies on thes...
Preparation and characterization of biodegradable composite systems as hard tissue supports: bone fillers, bone regeneration membranes and scaffolds
Sezer, Ümran Aydemir; Hasırcı, Nesrin; Department of Biomedical Engineering (2012)
In tissue engineering applications, use of biodegradable and biocompatible materials are essential. As the tissue regenerate itself on the material surface, the material degrades with enzymatic or hydrolytic reactions. After a certain time, natural tissue takes the place of the artificial support. Poly(ε-caprolactone) (PCL) is one of the preferable polymers used in the restoration of the bone defects due to its desirable mechanical properties and biocompatibility. Addition of inorganic calcium phosphate par...
Citation Formats
A. Yeniçeri, “Characterization of local flow behaviour in conical spouted beds,” Thesis (M.S.) -- Graduate School of Natural and Applied Sciences. Chemical Engineering., Middle East Technical University, 2019.