scholarly journals Dynamic modeling of the heat transfer process in rotary kilns with indirect oil heating: Parametric analysis of gypsum calcination case

2021 ◽  
pp. 245-245
Author(s):  
José Urbano ◽  
Jorge Henriquez ◽  
Alvaro Ochoa ◽  
Ana Primo ◽  
Breno Souza
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Rotary Kiln ◽  
Parametric Analysis ◽  
Energy Performance ◽  
Transient Regime ◽  
Three Dimensions ◽  
Constitutive Relationship ◽  
Realistic Condition ◽  
Rotary Kilns

This work proposes a mathematical modeling and numerical simulation of a gypsum rotary kiln with indirect oil heating in a three-dimensional transient regime. The mathematical model was based on Fourier's Law as a constitutive relationship and the principle of energy conservation, applied to a control volume in cylindrical coordinates. Furthermore, a bed homogenization model was used to represent the most realistic condition of the physical phenomenon since some rotary kilns have internal fins that aim at homogenizing the gypsum temperature during calcination. This work intends to fill the gap found in heat transfer processes on rotary kilns in transient regime considering three dimensions positions, to have an accurate projection of the temperature profile of the kiln and also, given by the numerical model, the possibility of a tool that can be used to the optimization of the control system of rotary kilns considering the actual demand of the material in production, leading to the best energy performance of the equipment's activation source, as well as reaching the temperatures and processing time of the product. The numerical simulation results revealed reasonable agreement with the experimentally determined calcination process in rotary kilns. Furthermore, a parametric analysis of the influence of the mixture on the temperature fields and the calcination time was carried out to verify the energetic balance of the rotary kiln.

Empirical Determination of the Design Influence of Large Industrial Rotary Kilns for Ferronickel Production on Heat Transfer and Energy Performance

2021 ◽  
Author(s):  
Janneth Ruiz ◽  
Antonio Ardila ◽  
Bernardo Rueda ◽  
Andy Castillo ◽  
Yuleisy Pardo ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Conceptual Design ◽  
Design Process ◽  
Rotary Kiln ◽  
Steel Production ◽  
Industrial Process ◽  
Energy Performance ◽  
Rotary Kilns ◽  
Counter Current ◽  
Early Phases

Abstract In the industrial process of ferronickel production from lateritic minerals, the influence of design factors, constructive and dimensional aspects on the heat transfer and energy performance of the equipment have been little addressed. The literature focuses on cement kilns or iron and steel production applications. This work compares the influence of the approaches considered in the early phases of the design process on heat transfer and energy performance for two ferronickel rotary kilns. For this purpose, a retrospective analysis was realized identifying requirements, operating principles, and approaches applied in the definition of specification and conceptual design. This analysis was carried out, taking into account one operation year data of two rotary calcining kilns of 185 meters and 135 meters in length, both of 6 meters in diameter and similar feeding rate between 170,000 and 180000 kilograms per hour. The analysis showed that kiln 1 had a functional approach in the early phases of the design process, while kiln 2 additionally has an environmental and energy approach, which allowed to improve the heat transfer and energy performance. This was verified with software based on the AHP method. The software results showed that counter-current and cross-flow rotary kiln 2 is a better conceptual design alternative for environmental and energy requirements than counter-current rotary kiln 1.

Computer Simulation of Heat Transfer in Alumina and Cement Rotary Kilns

2021 ◽  
pp. 1-57
Author(s):  
Atinder Pal Singh ◽  
P.S. Ghoshdastidar
Keyword(s):  
Heat Transfer ◽  
Computer Simulation ◽  
Rotary Kiln ◽  
Cement Kiln ◽  
Gas Temperature ◽  
Contact Heat ◽  
Dry Process ◽  
Radiation Exchange ◽  
Covered Wall ◽  
Rotary Kilns

Abstract The paper presents computer simulation of heat transfer in alumina and cement rotary kilns. The model incorporates radiation exchange among solids, wall and gas, convective heat transfer from the gas to the wall and the solids, contact heat transfer between the covered wall and the solids, and heat loss to the surroundings as well as chemical reactions. The mass and energy balances of gas and solids have been performed in each axial segment of the kilns. The energy equation for the wall is solved numerically by the finite-difference method. The dust entrainment in the gas is also accounted for. The solution marches from the solids inlet to the solids outlet. The kiln length predicted by the present model of the alumina kiln is 77.5 m as compared to 80 m of the actual kiln of Manitius et al. (1974, Manitius, A., Kurcyusz, E., and Kawecki, W., “Mathematical Model of an Aluminium Oxide Rotary Kiln,” Ind. Eng. Chem. Process Des. Dev., 13 (2), pp. 132-142). In the second part, heat transfer in a dry process cement rotary kiln is modelled. The melting of the solids and coating formation on the inner wall of the kiln are also taken into account. A detailed parametric study lent a good physical insight into axial solids and gas temperature distributions, and axial variation of chemical composition of the products in both the kilns. The effect of kiln rotational speed on the cement kiln wall temperature distribution is also reported.

Parametric Analysis of Floor Cooling

2016 ◽  
Vol 861 ◽  
pp. 401-408
Author(s):  
Lucie Horká ◽  
Jan Weyr
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Numerical Simulation ◽  
Parametric Analysis ◽  
Cooling Water ◽  
Total Heat ◽  
Design Parameters ◽  
Total Heat Transfer ◽  
2D Numerical Simulation ◽  
Cooling Pipes

This study is aimed at parametric analysis of floor cooling. Impact of several design parameters such as air temperature, temperature of cooling water, distance of cooling pipes, thickness and thermal conductivity of top layer on total heat transfer of cooling floor is studied. The issue is solved by steady-state 2D numerical simulation of heat transfer to the floor construction. These parametric simulations are performed in software CalA. Impact of variable input parameters on total heat transfer is observed. Results of parametric analysis are displayed in a nomogram. This nomogram is useful for faster designing of floor cooling.

Particle Scale Heat Transfer Analysis in Rotary Kiln

2012 ◽  
Author(s):  
Amit Ravindra Amritkar ◽  
Danesh Tafti ◽  
Surya Deb
Keyword(s):  
Heat Transfer ◽  
Rotary Kiln ◽  
Granular Media ◽  
Particle Surface ◽  
Convection Heat Transfer ◽  
Heat Transfer Analysis ◽  
Convection Heat ◽  
Bed Temperature ◽  
Rotary Kilns ◽  
Pass Through

Rotary furnaces have multiple applications including calcination, pyrolysis, carburization, drying, etc. Heat transfer through granular media in rotary kilns is a complex phenomenon and plays an important role in the thermal efficiency of rotary furnaces. Thorough mixing of particles in a rotary kiln determines the bed temperature uniformity. Hence it is essential to understand the particle scale heat transfer modes through which the granular media temperature changes. In this study, numerical simulations are performed using coupled Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD) to analyze heat transfer in a non-reacting rotary kiln. The microscopic models of particle-particle, particle-fluid, particle-surface and fluid-surface heat transfer are used in the analysis. The heat transfer simulations are validated against experimental data. The effect of particle cascading on the bed temperature is measured and contributions from various modes of particle scale heat transfer mechanisms are reported. Particles are heated near the rotary kiln walls by convection heat transfer as they pass through the thermal boundary layer of the heated fluid. These particles are transported to the center of the kiln where they transfer heat to the cooler particles in the core of the kiln and back to the cooler fluid at the center of the kiln. It is found that 90% of the heat transferred to particles from the kiln walls is a result of convection heat transfer, whereas only 10% of the total heat transfer is due to conduction from the kiln walls.

Analysis of Local Heat Transfer in Direct Fired Rotary Kilns

2010 ◽  
Author(s):  
Fabian Herz ◽  
Yogesh Sonavane ◽  
Eckehard Specht
Keyword(s):  
Heat Transfer ◽  
Rotary Kiln ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Internal Diameter ◽  
Transfer Coefficients ◽  
Contact Heat ◽  
Contact Heat Transfer ◽  
Bed Temperature ◽  
Rotary Kilns

Heat transfer in the rotary kiln is a complex phenomenon due to the different modes of heat transfer. In the first part of this study, the local heat transfer coefficients are analysed theoretically, to describe the heat transfer mechanisms in the cross section of the rotary kiln. Furthermore, the axial solid motion along the length of the kiln is considered in the local surfaces which exchanges the heat. A pilot plant drum of length 0.45 m and internal diameter of 0.6 m has been designed and fabricated to measure the contact heat transfer coefficient from the kiln wall to the covered solid bed. The cylinder is heated continuously by means of three electrical heaters fixed externally around the cylinder at various positions. K-type thermocouples have been used to measure the wall and solid bed temperature along the circumferential and the radial direction. Experiments are performed with various materials such as Quartz sand and Copper pellets of different size, shape and thermal conductivity. The effect of the material properties, the rotational speed (1–6 rpm) and the filling degree (10–20%) on the contact heat transfer have been studied thoroughly.

Numerical simulation of particle motion and heat transfer in a rotary kiln

2016 ◽  
Vol 287 ◽  
pp. 239-247 ◽  
Author(s):  
Hong Liu ◽  
Hongchao Yin ◽  
Ming Zhang ◽  
Maozhao Xie ◽  
Xi Xi
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Rotary Kiln ◽  
Particle Motion

scholarly journals Discrete-Ordinates Modelling of the Radiative Heat Transfer in a Pilot-Scale Rotary Kiln

Energies ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2192
Author(s):  
Adrian Gunnarsson ◽  
Klas Andersson ◽  
Bradley R. Adams ◽  
Christian Fredriksson
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Rotary Kiln ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Pilot Scale ◽  
Discrete Ordinates ◽  
Conductive Heat ◽  
Rotary Kilns ◽  
Development Evaluation

This paper presents work focused on the development, evaluation and use of a 3D model for investigation of the radiative heat transfer in rotary kilns. The model applies a discrete-ordinates method to solve the radiative transfer equation considering emission, absorption and scattering of radiation by gas species and particles for cylindrical and semi-cylindrical enclosures. Modelling input data on temperature, particle distribution and gas composition in the radial, axial and angular directions are experimentally gathered in a down-scaled version of a rotary kiln. The model is tested in its capability to predict the radiative intensity and heat flux to the inner wall of the furnace and good agreement was found when compared to measurements. Including the conductive heat transfer through the furnace wall, the model also satisfactorily predicts the intermediate wall temperature. The work also includes a first study on the effect of the incident radiative heat flux to the different surfaces while adding a cold bed material. With further development of the model, it can be used to study the heat transfer in full-scale rotary kilns.

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