(中南大學(xué) 能源科學(xué)與工程學(xué)院，長沙 410083)
摘 要: 在鋁電解下料過程中，氧化鋁顆粒吸熱、結(jié)塊、溶解并受到傳熱與傳質(zhì)溶解機(jī)制的綜合作用。基于OpenFOAM計算平臺，有效區(qū)分主導(dǎo)顆粒溶解的控制機(jī)制，考慮氣泡作用和下料后的電解質(zhì)溫度響應(yīng)，開發(fā)鋁電解槽中氧化鋁顆粒傳熱、傳質(zhì)耦合溶解計算模型；利用Rosin-Rammler分布函數(shù)計算下料后電解質(zhì)中氧化鋁顆粒粒徑分布，對實際300 kA鋁電解槽中氧化鋁溶解過程進(jìn)行數(shù)值模擬。結(jié)果表明：前18 s氧化鋁溶解50%(質(zhì)量分?jǐn)?shù))，屬于快速溶解階段；一個下料周期144 s結(jié)束后，剩余約1.5%(質(zhì)量分?jǐn)?shù))的氧化鋁未溶解，未溶解顆粒聚集，并在電解槽底部形成沉淀；僅考慮氧化鋁溶解吸熱的情況下，下料區(qū)位置電解質(zhì)溫度在前1 s快速下降，隨后，電解質(zhì)溫度快速回升并在60 s之后呈現(xiàn)震蕩趨勢。
關(guān)鍵字: 結(jié)塊；氧化鋁溶解；傳熱；傳質(zhì)；粒徑分布；數(shù)值模擬
（School of Energy Science and Engineering, Central South University, Changsha 410083, China）
Abstract:During the aluminum electrolytic feeding process, alumina particles will dissolve after absorbing heat, aggregation subject under the control of the mass and heat transfer mechanism. Based on the OpenFOAM computing platform, identifying the dominant mechanism controlling dissolution of alumina, considering the bubble effect and temperature response of electrolyte after feeding, the alumina, dissolution model coupled with heat and mass transfer were proposed. Based on the alumina particle size distribution calculated by Rosin-Rammler function, the actual dissolution process in electrolyte after feeding were simulated in 300 kA aluminum reduction cell. The simulation results show that the first 18 s is the quick stage of dissolution, in which about 50% of the quantity is dissolved. At the end of a feeding cycle 144 s, about 1.5% of the alumina is undissolved, the undissolved particle aggregates and forms sludge at the bottom of the cell. Only considering the alumina endothermic process, the electrolyte temperature in the feeding zone rapidly declines within the first 14 s, then, the temperature quickly is recovered and oscillated after 60 s.
Key words: aggregation; alumina dissolution; heat transfer; mass transfer; particle size distribution; numerical simulation
