氯碱工业离子膜电解槽内气液两相流动特性
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摘要
为验证数值模拟结果的正确性,建立了氯碱工业离子膜电解槽冷模实验装置,对电解槽内液体速度和气含率进行了实验测量,实验数据验证了模拟结果。利用实验和数值模拟方法对不同工况下气含率和气体体积分布进行了研究;对循环板上开口处膜侧瞬时压力进行了监测,分析了该处压力波动特性。结果表明,随着气液流量增大,电解槽内气含率增大,顶部气体滞留层增厚。当电流密度为10 k A×m~(-2)时,槽内气含率达到9.08%,为4.5 k A×m~(-2)时的近3倍。气体体积分数沿电解槽竖直方向逐渐增大,在膜与槽板夹角处最大。循环板上开口处膜侧压力信号波动明显,高频脉动主要由液体流动引起,低频脉动主要由气体流动引起。
Experimental setup of an ion-exchange membrane electrolysis cell from chlor-alkali industry was established to validate simulation results. Liquid velocity and gas holdup in the electrolysis cell were measured and the simulation results were verified. Gas holdup and gas volume fraction distribution in the anode chamber of the electrolysis cell under different operation conditions were investigated experimentally and numerically. The instantaneous pressure signals at the top of the circular plate near the membrane were monitored and analyzed. The results show that gas holdup increases and gas retention layer at the top of the electrolysis cell becomes thicker with the increase of gas and liquid flow rates. The value of gas holdup reaches to 9.08% at current density of 10 k A×m~(-2), which is nearly three times higher than that at 4.5 k A×m~(-2). The gas volume fraction increases along the vertical direction of the electrolysis cell and reaches to maximum at membrane corner and channel plate. Pressure signals at the top of the circular plate near the membrane fluctuate obviously. The higher frequency fluctuation of the pressure signals is mainly caused by liquid flow, while the lower ones are caused mainly by gas flow.
Experimental setup of an ion-exchange membrane electrolysis cell from chlor-alkali industry was established to validate simulation results. Liquid velocity and gas holdup in the electrolysis cell were measured and the simulation results were verified. Gas holdup and gas volume fraction distribution in the anode chamber of the electrolysis cell under different operation conditions were investigated experimentally and numerically. The instantaneous pressure signals at the top of the circular plate near the membrane were monitored and analyzed. The results show that gas holdup increases and gas retention layer at the top of the electrolysis cell becomes thicker with the increase of gas and liquid flow rates. The value of gas holdup reaches to 9.08% at current density of 10 k A×m~(-2), which is nearly three times higher than that at 4.5 k A×m~(-2). The gas volume fraction increases along the vertical direction of the electrolysis cell and reaches to maximum at membrane corner and channel plate. Pressure signals at the top of the circular plate near the membrane fluctuate obviously. The higher frequency fluctuation of the pressure signals is mainly caused by liquid flow, while the lower ones are caused mainly by gas flow.
引文
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[17]Farshad A,Hasan R.Applying a modified two-fluid model to numerical simulation of two-phase flow in the membrane chlor-alkali cells[J].Iranian Journal of Chemistry and Chemical Engineering,2008,27(3):51-61.
[18]YUE Wen-ting(岳雯婷),ZHANG Li(张丽),LIU Xiu-ming(刘秀明),et al.Influence of current density on transfer characteristics in electrolysis cell of chlor-alkali industry(电流密度对氯碱工业离子膜电解槽传递特性影响)[J].Journal of Chemical Industry and Engineering(China)(化工学报),2015,66(3):915-923.
[19]Asahi Kasei Corporation.Used for alkali metal chloride aqueous solution of electrolyzer unit slots:Japan,JP 242002/99[P].1999-08-27.
[20]Asahi Kasei Corporation.Bipolar press filter type electrolytic cell(双极压滤器型电解池):China,CN 92102754.0[P].1992-12-09.
[2]LI Su-gai(李素改).Energy consumption status and application progress of energy saving technology of chlor alkali industry(氯碱行业能源消耗现状及节能技术应用进展)[J].China Chlor-Alkali(中国氯碱),2014,5(3):1-3.
[3]ZHOU Qiang(周强),WANG Qi(王奇),JIANG Yong(江泳).Research on operation technologies of Asahi Kasei NCZ zero-polar distance electrolyzers(旭化成NCZ零极距电解槽应用技术研究)[J].Chlor-Alkali Industry(氯碱工业),2012,48(10):13-16.
[4]Janssen L J J,Hoogland J G.The effect of electrolytically evolved gas bubbles on the thickness of the diffusion layer[J].Electrochimica Acta,1970,15(6):1013-1023.
[5]Gijsbers H F M,Janssen L J J.Distribution of mass transfer over a 0.5-m-tall hydrogen-evolving electrode[J].Journal of Applied Electrochemistry,1989,19(5):637-648.
[6]Vogt H.The incremental ohmic resistance caused by bubbles adhering to an electrode[J].Journal of Applied Electrochemistry,1983,13(1):87-88.
[7]Xiong Y,Jialing L,Hong S.Bubble effects on ion exchange membranes-an electrochemical study[J].Journal of Applied Electrochemistry,1992,22(5):486-490.
[8]Bergner D.Membrane cells for chlor-alkali electrolysis[J].Journal of Applied Electrochemistry,1982,12(6):631-644.
[9]Chandran R R,Chin D T.Reactor analysis of a chlor-alkali membrane cell[J].Electrochimica Acta,1986,31(1):39-50.
[10]Jalali A A,Mohannadi F,Ashrafizadeh S N.Effects of process conditions on cell voltage,current efficiency and voltage balance of a chlor-alkali membrane cell[J].Desalination,2009,237(1):126-139.
[11]Dahlkild A A.Modeling the two-phase flow and current distribution along a vertical gas-evolving electrode[J].Journal of Fluid Mechanics,2001,428(2):249-272.
[12]Wedin R,Dahlkild A A.Numerical and analytical hydrodynamic two-phase study of an industrial gas-lift chlorate reactor[J].American Society of Mechanical Engineers,Pressure Vessels and Piping Division,1999,397(1):125-136.
[13]Zuber N,Findlay J A.Average volumetric concentration in two-phase flow systems[J].Journal of Heat Transfer,1965,87(4):453-462.
[14]Hua J S,Wang C H.Numerical simulation of bubble-driven liquid flows[J].Chemical Engineering Science,2000,55(19):4159-4173.
[15]Aldas K.Application of a two-phase flow model for hydrogen evolution in an electrochemical cell[J].Applied Mathematics and Computation,2004,154(2):507-519.
[16]Mat M D,Aldas K.Application of a two-phase flow model for natural convection in an electrochemical cell[J].International Journal of Hydrogen Energy,2005,30(4):411-420.
[17]Farshad A,Hasan R.Applying a modified two-fluid model to numerical simulation of two-phase flow in the membrane chlor-alkali cells[J].Iranian Journal of Chemistry and Chemical Engineering,2008,27(3):51-61.
[18]YUE Wen-ting(岳雯婷),ZHANG Li(张丽),LIU Xiu-ming(刘秀明),et al.Influence of current density on transfer characteristics in electrolysis cell of chlor-alkali industry(电流密度对氯碱工业离子膜电解槽传递特性影响)[J].Journal of Chemical Industry and Engineering(China)(化工学报),2015,66(3):915-923.
[19]Asahi Kasei Corporation.Used for alkali metal chloride aqueous solution of electrolyzer unit slots:Japan,JP 242002/99[P].1999-08-27.
[20]Asahi Kasei Corporation.Bipolar press filter type electrolytic cell(双极压滤器型电解池):China,CN 92102754.0[P].1992-12-09.