Experimental Studies of the Impact of Anode Pre‐Heating

Fortini, Otavio; Garimella, Srinivas; Kuhn, Edwin; Ruan, Yimin; Yacob, Benyam; Sorensen, Jack

doi:10.1002/9781118359259.ch101

Cited by 5 publications

(6 citation statements)

References 3 publications

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Section: Anode Preheatingmentioning

confidence: 99%

“…During the changing of the anodes, a layer of frozen electrolyte bath is immediately quenched on the bottom surface of the new, cold anodes [52]. Energy is required to melt the layer of frozen electrolyte, and productivity is reduced during the time it takes to melt it [52]. A disrupted bath motion around the new anodes and an uneven anode current distribution occurs until the layer is melted and is thought to increase the noise and reduce the current efficiency [52].…”

Section: Anode Preheatingmentioning

confidence: 99%

“…Preheating the bottom surface of the anodes to 480-510 °C before lowering them into the electrolyte bath can increase the current efficiency by 0.5-1% and can double the electrical current pick-up rate [52]. There is a potential energy saving of about 0.04 kWh/kg Al, which does not take the energy for preheating the anodes into account [52]. This is due to the fact that the anodes either can be delivered directly from the bake furnaces or can be heated by the excess heat from the electrolysis [52].…”

Section: Anode Preheatingmentioning

confidence: 99%

“…There is a potential energy saving of about 0.04 kWh/kg Al, which does not take the energy for preheating the anodes into account [52]. This is due to the fact that the anodes either can be delivered directly from the bake furnaces or can be heated by the excess heat from the electrolysis [52].…”

Section: Anode Preheatingmentioning

confidence: 99%

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Review of measures for improved energy efficiency in production-related processes in the aluminium industry – From electrolysis to recycling

Haraldsson

Johansson

2018

Renewable and Sustainable Energy Reviews

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The aluminium industry is facing a challenge in meeting the goal of halved greenhouse gas emissions by 2050, while the demand for aluminium is estimated to increase 2-3 times by the same year. Energy efficiency will play an important part in achieving the goal. The paper's aim was to investigate possible production-related energy efficiency measures in the aluminium industry. Mining of bauxite and production of alumina from bauxite are not included in the study. In total, 52 measures were identified through a literature review. Electrolysis in primary aluminium production, recycling and general measures constituted the majority of the 52 measures. This can be explained by the high energy intensity of electrolysis, the relatively wide applicability of the general measures and the fact that all aluminium passes through either electrolysis or recycling. Electrolysis shows a higher number of emerging/novel measures compared to the other processes, which can also be explained by its high energy intensity. Processing aluminium with extrusion, rolling, casting (shape-casting and casting of ingots, slabs and billets), heat treatment and anodising will also benefit from energy efficiency. However, these processes showed relatively fewer measures, which might be explained by the fact that to some extent, these processes are not as energy demanding compared, for example, to electrolysis. In many cases, the presented measures can be combined, which implies that the best practice should be to combine the measures. There may also be a future prospect of achieving carbon-neutral and coal-independent electrolysis. Secondary aluminium production will be increasingly important for meeting the increasing demand for aluminium with respect to environmental and economic concerns and strengthened competitiveness. Focusing on increased production capacity, recovery yields and energy efficiency in secondary production will be pivotal. Further research and development will be required for those measures designated as novel or emerging.

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Section: Anode Preheatingmentioning

confidence: 99%

Section: Anode Preheatingmentioning

confidence: 99%

Section: Anode Preheatingmentioning

confidence: 99%

Section: Anode Preheatingmentioning

confidence: 99%

See 2 more Smart Citations

Review of measures for improved energy efficiency in production-related processes in the aluminium industry – From electrolysis to recycling

Haraldsson

Johansson

2018

Renewable and Sustainable Energy Reviews

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“…The thermal issues related to anode change can be mitigated by pre-heating the anodes prior to insertion. Fortini et al [5] heated anodes to surface temperatures of about 500 • C using 30 kW heaters and found an increase in current efficiency of 0.5-1 % over 60 days. Correspondingly, Jassim et al [6] found that preheating anodes up to 300 • C resulted in a 42% faster evolution in current during the initial 6 hours of operation -in theory improving cell stability and current efficiency, as well as improving the local heat deficit.…”

Section: Introductionmentioning

confidence: 99%

Utilization of Waste Heat for Pre-heating of Anodes

Grimstad

Elstad

Solheim

et al. 2020

The Minerals, Metals &Amp; Materials Series

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Carbon anodes are replaced on a regular basis in Hall-Héroult cells as they are consumed by electrochemical reactions. Upon insertion of new anodes, bath will freeze locally as a result of low bath superheat and comparatively low anode temperature, creating an insulating layer on the anode surface, thereby delaying further production. In the current work the potential for pre-heating anodes directly utilizing waste heat from off-gas and spent anode butts is investigated using a numerical model realized in COMSOL and industrial measurements at the Alcoa Mosjøen smelter. Anode core temperatures over 150 • C and surface temperatures over 250 • C were found when using butts as a direct heat source. Frozen bath samples from both pre-heated and regular anodes were collected and analysed using computer tomography (CT) in order to assess how various heating strategies influences frozen bath morphology.

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Heating New Anodes Using the Waste Heat of Anode Butts Establishing the Interface Thermal Contact Resistance

Dupuis¹,

Gudbrandsen

Einarsrud

2021

The Minerals, Metals &Amp; Materials Series

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In order to be able to assess the rate of heat transfer between a new anode and an anode butt, it is critical to measure the interface thermal contact resistance between them. For that purpose, a lab experiment has been setup and tests have been carried out to record the thermal response of the system after a cold anode block is put in contact with a hot anode block. Finally, a model of the same system has been developed in order to identify the value of the thermal contact resistance that permit to reproduce the thermal experimental thermal response.

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Experimental Studies of the Impact of Anode Pre‐Heating

Cited by 5 publications

References 3 publications

Review of measures for improved energy efficiency in production-related processes in the aluminium industry – From electrolysis to recycling

Review of measures for improved energy efficiency in production-related processes in the aluminium industry – From electrolysis to recycling

Utilization of Waste Heat for Pre-heating of Anodes

Heating New Anodes Using the Waste Heat of Anode Butts Establishing the Interface Thermal Contact Resistance

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