Computational modelling of thermophysical processes in the light metals industry

Bui, R. T.

doi:10.1016/s0035-3159(97)89985-0

Cited by 4 publications

(1 citation statement)

References 26 publications

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“…means that there is no cover on the furnace, the anodes are stacked in the pits and just covered with coke for support and protection against oxidation with ambient air. The word "horizontal" refers to the overall direction of the gas flow from section to section in the furnace [9], and "ring" describes the looping pattern of the heat wave in the furnace and the displacement in circle of the equipment ramps on the furnace.…”

Section: Description Of the Anode Baking Furnacementioning

confidence: 99%

Comparison of three combustion models for simulating anode baking furnaces

Grégoire

Gosselin

2018

International Journal of Thermal Sciences

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Carbon anode blocks used in the Hall-Héroult process for primary aluminum production have to be baked up to 1100°C in dedicated furnaces. These furnaces are equipped with burner ramps to heat the air circulating in the flues at 1200°C, so that the anodes reach the required temperature. It is therefore mandatory to include the heat provided by the burners in a numerical model of an anode baking furnace. In this work, we modeled the heat input at the burners in three ways: the Eddy-Dissipation model, the Mixture Fraction/PDF approach and a simplified approach consisting in injecting an equivalent calorific value at the burners' inlets. Results obtained with the first two models are very similar in terms of anode baking prediction but slightly different in terms of flame temperature prediction. Results obtained with the simplified approach show that the model can replace combustion model to predict anode baking, but calibration of boundary conditions is necessary in order to match more elaborate combustion models. The importance of other elements of the model in the flue channel of the furnace has been verified: radiation (cannot be ignored, large influence on the spatial temperature distribution), heat transfer due to species diffusion (negligible influence on the baking, but slight effect on flame shape and temperature), and buoyancy (no significant effect on the results in the furnace firing sections).

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Section: Description Of the Anode Baking Furnacementioning

confidence: 99%

Comparison of three combustion models for simulating anode baking furnaces

Grégoire

Gosselin

2018

International Journal of Thermal Sciences

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Simulating the Heat Transfer Process of Horizontal Anode Baking Furnace

Zhang

Chen

2004

Dev. Chem. Eng. Mineral Process.

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IntroductionLarge amounts of carbon anodes are consumed in the aluminum industry. Anodes are made of petroleum coke held together by a pitch binder. They must be baked to a given temperature of about 1000 to 1200°C at a very low heating rate (10-15"Ch) in order to obtain the appropriate mechanical and electrical properties required for their use in electrolync cells [l, 21. This baking process occurs in a horizontal or vertical ring h a c e , which is built as a chain of sections arranged in a ring shape. The uniformity and stability of the balung temperature in the anodes during baking determines the anodes final qualities, and directly affects aluminum production When baking, air is blown into the flue from the cooling manifold (right hand side of Figure 1) and flows from right to lefl. It picks up heat from cooling the baked anodes and the burner, and gives up part of its heat to the solids in the heating zone before exhausting. During baking, the anodes are stationary in their pits. However, the burner, cooling manifold and exhaust manifold are displaced from one section to the next, moving from right to left at regular time intervals called firing cycle times (range 25-45 hours). The entire process corresponds to a counterflow semi-continuous heat exchanger [l]. The thermal behavior of the baking process in a ring furnace is too complicated to be described completely. Presently, the design of an anode baking furnace strongly depends on the experience of the designers. Thls would inherently induce some defects such as more fuel consumption, asymmetrical heating temperature in the anodes interior, cracking phenomena in anodes, etc. Furthermore, because of the large size and long time constant (in the order of 2 or 3 months) of a bakmg furnace, a real furnace experiment is impractical due to cost and time constraints. It is obvious that new theories and thermal simulation studies on anode baking furnaces are required.The purpose of this paper is to simulate the heat transfer in the horizontal baking furnace, and to identify optimal operating conditions, in order to support the required data for designing a baking furnace. 428Simulating the Heat Transfir Process of Horizontal Anode Baking Furnace Model DescriptionModeling of an anode balung furnaces started about 20 years ago. In an actual furnace, the burners are moved stepwise by one section after each firing cycle. All the burners are then tumed off and the cooling manifold, burners and exhaust manifolds are moved forward by one section. The burners are turned on again and the process is continued. The same process is repeated for another firing cycle time through all the sections from heating to cooling (1P to 1OP in Figure 1). However, it is very difficult to build such a model, which is able to simulate the actual operation of a ring fusnace, since the initial value and boundary conditions at each section are very different. Furthermore, huge amount of CPU time are required to use such models to calculate different firing configurations and to estimate th...

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Simulating the Heat Transfer Process of Horizontal Anode Baking Furnace

Zhang¹,

Chen²,

Xu³

2005

Dev. Chem. Eng. Mineral Process.

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A transient two-dimensional mathematical model of a horizontal baking firnace is presented. The model combines complex thermal phenomena in a baking process such as air infiltration. evolution and combustion of volatile matters, combustion of packing coke, and heat losses. The predicted results are in good agreement with measured data. Furthermore, the process is simulated under diferent operating conditions such as firing cycle time, airjlow and air infiltration. The simulated results indicate that the fuel consumption decreases as the firing cycle time decreases, it is also found that reducing the airjlow and air infiltration will he& to save &el. The model is proved to be a useful tool for the process optimisation of the bakingfirrnace in the aluminum industry.

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Computational modelling of thermophysical processes in the light metals industry

Cited by 4 publications

References 26 publications

Comparison of three combustion models for simulating anode baking furnaces

Comparison of three combustion models for simulating anode baking furnaces

Simulating the Heat Transfer Process of Horizontal Anode Baking Furnace

Simulating the Heat Transfer Process of Horizontal Anode Baking Furnace

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