Experimental Apparatus for Studying Heat Transfer in Externally Heated Rotary Kilns
TL;DR: In this paper, a rotary kiln equipped with an external electrical heating system enables the study of the influence of various parameters such as the solid flow rate, the kiln inclination angle, the rotational speed, or the presence of lifters on heat exchange and in particular on the heat exchange coefficient between the solid and the wall.
Abstract: Rotary kilns are widely used in several branches of the chemical industry. In order to control the temperature of the solid and the gas flowing through the kiln, it is important to understand the heat exchange phenomena that occur. The design and construction of a novel experimental device to study heat exchange in rotary kilns is described. The device, which comprises a rotary kiln equipped with an external electrical heating system, enables the study of the influence of various parameters such as the solid flow rate, the kiln inclination angle, the rotational speed, or the presence of lifters on heat exchange and in particular on the heat exchange coefficient between the solid and the wall. Preliminary experimental results concerning the influence of the solid flow rate and the rotational speed on the solid-to-wall heat exchange coefficient are presented.
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TL;DR: In this article, the axial dispersion coefficient of the solid particles within a rotary kiln at room temperature and equipped with lifters has been analyzed for the continuous flow of sand and broken rice.
51 citations
TL;DR: In this article, the authors modeled conductive heat transfer from rotary drum walls to a particle bed via discrete element method simulations, and three time scales were determined: 1) the characteristic heating time of the bed, τ; 2) the particle thermal time constant, τp; and 3) the contact time between a particle and the wall, τc.
41 citations
TL;DR: In this paper, the influence of operational variables and material properties on the mean residence time (MRT), hold up, and axial dispersion was investigated in a pilot plant rotary calciner.
Abstract: Rotary calcination is widely used in catalyst manufacturing and many other industrial processes. In this article, the influence of operational variables and material properties on the mean residence time (MRT), hold up, and axial dispersion was investigated in a pilot plant rotary calciner. Residence time distributions (RTD) of spherical, cylindrical, and quadrilobe catalyst particles were measured and contrasted. The Saeman's model was successfully applied to predict the experimental bed depth and the MRT as particles flowed through the calciner. It was observed that increasing the feed rate did not significantly affect the MRT. Results for the different particles indicated that cylinders and quadrulobes exhibited less axial dispersion than spheres due to the decreased flowability. A reliable method was developed to provide a reasonable RTD prediction in rotary calcination systems. © 2013 American Institute of Chemical Engineers AIChE J, 59: 4068–4076, 2013
34 citations
TL;DR: In this article, the authors deal with the heat transfer analysis from experimental apparatus installed in a large-scale rotary drum reactor applied to the asphalt materials production and compare the results with major results of the literature.
32 citations
Cites background from "Experimental Apparatus for Studying..."
...[4] described the many experimental results existing in the literature dedicated to the evaluation of the gas/wall transfer coefficient, hgw, and the solid/wall transfer, hsw....
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TL;DR: In this article, a coupled thermal-granular model is applied to a flights rotary kiln for hot-mix asphalt materials manufacture, where the exchange surfaces estimation governing the heat transfer phenomena is calculated in the kiln cross-section.
31 citations
Cites methods from "Experimental Apparatus for Studying..."
...This correlation is widely used in the literature, for several mathematical models describing heat transfer by contact between the covered inner wall surface and the solid bed in rotating kiln [4,6,17,19,20]....
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References
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Book•
01 Oct 2007
TL;DR: In this paper, conversion factors and mathematical symbols are used to describe conversion factors in physical and chemical data and Mathematical Symbols are used for converting, converting, and utilising conversion factors.
Abstract: Section 1: Conversion Factors and Mathematical Symbols Section 2: Physical and Chemical Data Section 3: Mathematics Section 4: Thermodynamics Section 5: Heat and Mass Transfer Section 6: Fluid and Plastic Dynamics Section 7: Reaction Kinetics Section 8: Process Control Section 9: Process Economics Section 10: Transport and Storage of Fluids Section 11: Heat-Transfer Equipment Section 12: Psychrometry, Evaporative Cooling, and Solids Drying Section 13: Distillation Section 14: Equipment for Distillation, Gas Absorption, Phase Dispersion, and Phase Separation Section 15: Liquid-Liquid Extraction and Other Liquid-Liquid Operations and Equipment Section 16: Adsorption and Ion Exchange Section 17: Gas-Solid Operations and Equipment Section 18: Liquid-Solid Operations and Equipment Section 19: Reactors Section 20: Alternative Separation Processes Section 21: Solid-Solid Operations and Processing Section 22: Waste Management Section 23: Process Safety Section 24: Energy Resources, Conversion, and Utilization Section 25: Materials of Construction Index
10,028 citations
01 Jan 1984
TL;DR: Perry's Chemical Engineers' Handbook as mentioned in this paper is a free download pdf for chemical engineering applications, from the fundamentals to details on computer applications and control, and it can be found in any computer science course.
Abstract: Perry chemical engineers handbook free download pdf. Customers at an SAP AG event in Boston today expressed strong commitment to the vendors platform. Perry's Chemical Engineers' Handbook. All aspects of chemical engineering, from the fundamentals to details on computer applications and control. Definitive. Garner, G. O., “Careers in Engineering,” 2nd ed., VGM Career Books, in "Perry's Chemical Engineers' Handbook," 6th ed., McGraw-Hill, New York (1984).
7,890 citations
"Experimental Apparatus for Studying..." refers methods in this paper
...The solid/gas heat transfer coefficient hsg was estimated to be 3 W m K using a correlation that is applicable to natural convection above a horizontal solid plane for air in the temperature range measured by our pilot-kiln [27]; the solid/wall heat transfer coefficient hsw is the magnitude to be determined....
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Book•
01 Jan 1969
TL;DR: In this article, a unified treatment of momentum transfer (fluid mechanics), heat transfer and mass transfer is presented, with a focus on modern applications of the basic material, and many new homework exercises at the end of each chapter.
Abstract: Providing a unified treatment of momentum transfer (fluid mechanics), heat transfer and mass transfer. This new edition includes more modern applications of the basic material, and to provide many new homework exercises at the end of each chapter.
1,973 citations
TL;DR: In this paper, a mathematical model was developed to predict the transitions between different forms of transverse motion of free-flowing bed materials in rotating cylinders: sliding, surging, slumping and cascading.
522 citations
TL;DR: In this article, an experimental study of convective heat transfer from hot air to the solid charge and walls in a non-fired rotary kiln is reported, where axial temperature profiles of gas, wall and solids were measured.
Abstract: An experimental study of convective heat transfer from hot air to the solid charge and walls in a non-fired rotary kiln is reported. Ottawa sand was heated by passing it counter-current to a flow of preheated air in a 2.5 m × 0.19 m I.D. rotary kiln. Axial temperature profiles of gas, wall and solids were measured. Local and average convective heat transfer coefficients from gas to solids and from gas to wall were determined assuming plug flow of gas and solids. Solid feed rates to 1750 kg/m2 h and air rates to 3300 kg/m2 h were investigated at rotational speeds to 6 r/min, holdup ratios to 17% and gas temperatures from 350–590 K. The gas/solids convective coefficient was found to depend on the gas through-put and to a lesser extent on solids holdup and rotational speed. Over the range tested, the angle of kiln inclination, solids throughput and particle size showed no significant effect on heat transfer. Gas/wall coefficients were about a factor of ten below gas/solid coefficients. Heat transfer results are compared to the limited data available in the literature, and to commonly used equations. Correlations of the experimental data on gas/solids, and gas/wall coefficients are presented; data from the literature on the wall/solids heat transfer coefficient are summarized.
On presente une etude experimentale sur le transfert thermique convectif de l'air chaud a la charge solide et aux parois dans un four rotatif sans brǔlures. On a chauffe du sable Ottawa en le faisant passer a contre-courant dans un flux d'air pre-chauffe, dans un four rotatif de 2.5 metres par 0.19 metre de diametre interieur. On a mesure les profils des temperatures axiales du gaz, des parois et de la charge solide. On a determine, en supposant l'existence d'un ecoulement piston du gaz et des solides, les coefficients de transfert thermique convectif local et moyen du gaz a la charge solide et du gaz aux parois. On a etudie des vitesses d'alimentation en solides allant jusqu'a 1750 kg/m2 h et des vitesses de l'air atteignant 3300 kg/m2 h et ce, a des vitesses de rotation allant jusqu'a 6 tours a la minute, pour des rapports de retention de 17% et des temperatures comprises entre 350 et 590 K. On a trouve que le coefficient de transfert thermique convectif du gaz a la charge solide dependait du debit du gaz et, a un degre moindre, de la retention des solides et de la vitesse de rotation. On a constate qu'a l'echelle des experiences faites, l'angle d'inclinaison du four, le debit et les dimensions des particules solides n'avaient aucun effet important sur la transfert de chaleur. Les coefficients de transfert thermique convectif du gaz aux parois avaient une valeur dix fois moindre que celle des coefficients de transfert du gaz aux matieres solides. On a compare les resultats relatifs aux transfert de chaleur avec les renseignements restreints qu'on trouve dans la litterature technique et avec les equations usuellement employees. On presente des correlations entre les resultats experimentaux obtenus, pour les transferts de chaleur entre gaz et solides et gaz et parois; on resume aussi les donnees parues dans la litterature technique relativement au coefficient de transfert de chaleur des parois aux solides.
159 citations