Bubble driven flow in narrow channels between the electrodes of an aluminium electrolysis cell

铝电解槽电极之间狭窄通道中的气泡驱动流

• 批准号: 250454-2011
• 负责人: Kiss, Laszlo
• 金额: $ 2.19万
• 依托单位: Université du Québec à Chicoutimi
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=570922
• 关键词: Bubble; driven; flow; narrow; channels

Today's production technologies consume about twice of the electrical energy needed theoretically to reduce alumina into metallic aluminum. An important part of the excess energy is dissipated in the molten electrolyte during the passage of the electrical current. The gas bubbles that are generated during the electrochemical reduction of alumina occupy a part of the horizontal interelectrode space and increase the electrical resistance provoking a parasite heat generation. One method of reducing that excess heating is by reducing the interelectrode space, the so-called anode-cathode distance, ACD. However, the thickness of the bubble layer under the anode sets a limit to the reduction of the ACD as the bubbles can perturb the electrolyte-metal interface, causing a reduction in the current efficiency of the electrolysis cell. Earlier research has shown that the size of the bubbles under the anode varies over a very wide range from few micrometers up to tens of centimeters. The generation and behavior of the very large bubbles were also studied and it was determined that they have a very strong influence on the movement of the electrolyte and on the overvoltage caused by the bubbles. The efficiency of the efforts of reducing the anode-cathode distance depends essentially on the better understanding and control of the bubble layer. The proposed research project aims at the extension of knowledge about the morphology and dynamic behavior of the gas-liquid flow when the anode-cathode distance is reduced and approaches of the thickness of the bubble laden layer. Both experiments and mathematical modeling methods will be used to discover and describe the morphology and movement of bubbles. The expected results will aid directly the improvement of the energy efficiency of the existing plants as well as the development of innovative, new reduction technologies, which is important to maintain Canada's leadership in aluminum production. The fundamental aspects of the proposed research can represent a contribution to the improvement of other electrolysis methods like fluorine and hydrogen production.

当今的生产技术消耗的电能大约是理论上将氧化铝还原成金属铝所需电能的两倍。在电流通过期间，多余能量的重要部分消散在熔融电解质中。氧化铝电化学还原过程中产生的气泡占据了水平电极间空间的一部分，并增加了电阻，引起寄生热产生。 减少过度加热的一种方法是减少电极间空间，即所谓的阳极-阴极距离 (ACD)。然而，阳极下方气泡层的厚度限制了 ACD 的降低，因为气泡会扰乱电解质-金属界面，导致电解池电流效率降低。 早期研究表明，阳极下方气泡的尺寸变化范围很广，从几微米到几十厘米。还研究了非常大的气泡的产生和行为，并确定它们对电解质的运动和气泡引起的过电压有非常大的影响。 减少阳极-阴极距离的努力的效率本质上取决于对气泡层的更好理解和控制。 拟议的研究项目旨在扩展有关阳极-阴极距离减小时气液流的形态和动态行为以及接近气泡层厚度的知识。实验和数学建模方法将用于发现和描述气泡的形态和运动。 预期结果将直接有助于提高现有工厂的能源效率以及开发创新的新型减排技术，这对于保持加拿大在铝生产方面的领先地位非常重要。拟议研究的基本方面可以代表对改进其他电解方法（如氟和氢生产）的贡献。