Resistance due to gas bubbles in aluminum reduction cells

Cooksey, Mark; Taylor, Marilyn; Chen, John J. J.

doi:10.1007/s11837-008-0019-x

Cited by 46 publications

(30 citation statements)

References 18 publications

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“…13 Although bubble nucleation and, in consequence, their associated potential variation are dependent on the operating current density, cell design (electrode geometry, interelectrode spacing) and electrolyte formulation, several studies have estimated these losses under specific conditions. In an aluminum production industrial cell, potential drops in the range of 0.09-0.35 V were reported for 10 kA cell with a bubble layer of ~ 2.1 cm, 14 while laboratory scale studies reported potential drops of 0.15-0.35 V for current densities of 300-900 mA/cm 2 . 15,16 In chloro-alkali processes at industrially relevant current densities (>600 mA/cm 2 ), bubbles attached to the electrodes accounted for potential drops in the range of 0.6 to 0.9 V, ~20% of the total cell voltage.…”

Section: Introductionmentioning

confidence: 99%

Influence of Bubbles on the Energy Conversion Efficiency of Electrochemical Reactors

Angulo

Linde

Gardeniers

et al. 2020

Joule

533

374

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Bubbles are known to influence energy and mass transfer in gas evolving electrodes. However, we lack a detailed understanding on the intricate dependencies between bubble evolution processes and electrochemical phenomena.This review discusses our current knowledge on the effects of bubbles on electrochemical systems with the aim to identify opportunities and motivate future research in this area. We first provide a base background on the physics of bubble evolution as it relates to electrochemical processes. Then we outline how bubbles affect energy efficiency of electrode processes, detailing the bubble-induced impacts on activation, ohmic and concentration overpotentials.Lastly, we describe different strategies to mitigate losses and how to exploit bubbles to enhance electrochemical reactions. Context & ScaleElectrochemical reactors will play a key role in the electrification of the chemical industry and can enable the integration of renewable electricity sources with chemical manufacturing. Most large-scale industrial electrochemical processes, including chloro-alkali and aluminum production, involve gas evolving electrodes. The evolution of bubbles at the surface of redox reaction sites often lead to the reduction of the active electrode area, the increase of ohmic resistance in the electrolyte and the formation of undesirable concentration gradients. All of these effects result in energy losses which reduce the efficiency of electrochemical systems. This review synthesizes our current understanding on the relationship between bubble evolution and energy losses in electrochemical reactors. By presenting a thorough account on the state of the research in this area, we aim to provide a common ground for the research community to improve our understanding on the complex processes involved in multiphase electrochemical systems. Increasing our knowledge on the relationship between bubbles and electrochemistry will lead to new strategies to mitigate and exploit bubble-induced phenomena leading to design guidelines for high-performing electrochemical reactors.

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Section: Introductionmentioning

confidence: 99%

Influence of Bubbles on the Energy Conversion Efficiency of Electrochemical Reactors

Angulo

Linde

Gardeniers

et al. 2020

Joule

533

374

View full text Add to dashboard Cite

show abstract

“…The use of input material parameter values, their temperature dependence, the cell aging process and the complexity of the operational practice makes the precise inputs difficult and requires creative mind to find the right solutions suit practical demand of industry. For instance, the electric current distribution is considerably affected by the influence of the initial shape and position of an anode and the curvature of the aluminium [10], effects of the gas bubble concentration at the anode bottom [13], and the various contact resistances in the cathode assembly [14] and anode connectors. These features are available as the initial setup parameters within the software.…”

Section: Introductionmentioning

confidence: 99%

Anode Bottom Burnout Shape and Velocity Field Investigation in a High Amperage Electrolysis Cell

Bojarevics

Radionov

Tretiyakov

2018

The Minerals, Metals &Amp; Materials Series

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Long term burnout shape of the anode bottom is believed to reflect the quasi-stationary liquid metal interface dome-shaped deformation. The shape profiles and their interplay affect the MHD stability, the velocity fields, set up of new anodes and electrical efficiency of the cell. Spent prebake anode bottom profiles were systematically measured at Rusal 309 kA cell to obtain the overall view of the liquid metal deformation. The magnetic field distribution and velocities of liquid metal flow were measured in order to obtain a more complete characterization of the cell. The results are compared to the modelling results using the specialised MHD-VALDIS software giving the insight to the cell dynamics.

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“…According to Haupin and Kvande [1], the presence of gas bubbles in an industrial cell increases the cell voltage by 0.25 V which gives about 6 % contribution to the total cell voltage. In the literature it is very common to denote this component of the cell voltage as bubbles overpotential, which is slightly confusing, because, in fact, bubbles increase cell voltage by two main mechanisms: increase of ohmic resistance of the electrolyte and increase of activation polarization [2]. An increase of ohmic resistance of electrolyte may be described by Bruggemann's equation for dispersed bubble phase fraction in an electrolyte [3,4].…”

Section: Introductionmentioning

confidence: 99%

Effect of Coke Properties on the Bubble Formation at the Anodes During Aluminium Electrolysis in Laboratory Scale

et al. 2017

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The anodic reaction of aluminium electrolysis cells leads to the formation of CO 2 bubbles, which partly screen the anode surface and leads to an increase in the cell voltage. An advantage of these bubbles is that the formation and release contribute to the stirring of the electrolyte, however, the screening of the surface increase the irreversible energy losses. In this work the voltage and current oscillation due to bubbles evolution during electrolysis in laboratory cell were presented. A comparison of different carbon anode materials in terms of coke impurities (mainly sulphur content) and grain sizes were investigated. Anodes with finer coke fraction showed lower oscillations than coarser fraction equivalents. Additionally, influence of current density on amplitude of anode potentials was measured. A 64 % increase of current density caused an increase of anode potential oscillations from 79 to 179 %.

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Resistance due to gas bubbles in aluminum reduction cells

Cited by 46 publications

References 18 publications

Influence of Bubbles on the Energy Conversion Efficiency of Electrochemical Reactors

Influence of Bubbles on the Energy Conversion Efficiency of Electrochemical Reactors

Anode Bottom Burnout Shape and Velocity Field Investigation in a High Amperage Electrolysis Cell

Effect of Coke Properties on the Bubble Formation at the Anodes During Aluminium Electrolysis in Laboratory Scale

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