中南大学课程设计报告

CENTRALSOUTHUNIVERSITY课程设计说明书现代铝电解槽新型阳极结构设计题目（单槽日产量2.4t,电流密度0.76A·cm-2）学生姓名刘冬专业班级冶金00906班学生学号0503090706指导教师伍上元学院冶金科学与工程学院完成时间2012年9月11日2目录第一章概述1.1现代铝电解槽结构发展趋势····································································31.2所设计电解槽阳极结构的特点···································································4第二章铝电解槽结构简介2.1上部结构····························································································52.1.1阳极炭块组························································································62.1.2阳极升降装置·····················································································62.1.3承重结构···························································································72.1.4加料装置···························································································72.1.5集气装置···························································································82.2阴极结构····························································································92.2.1槽壳与摇篮架·····················································································102.2.2槽内衬······························································································112.3母线结构····························································································132.3.1阳极母线···························································································132.3.2阴极母线···························································································142.4绝缘设施····························································································15第三章铝电解结构计算3.1阳极电流密度························································································153.2阳极炭块尺寸························································································153.3阳极炭块数目························································································173.4槽膛尺寸······························································································173.5槽壳尺寸······························································································173.6阴极碳块尺寸························································································17第四章阳极结构设计4.1阳极炭块组·························································································184.2换极周期与顺序···················································································194.3阳极炭块质量要求与组装·······································································204.3.1阳极炭块质量要求···············································································204.3.2阳极组装···························································································21第五章参考文献····················································································223第一章概述1.1现代铝电解槽结构发展趋势20世纪80年代以前，工业铝电解的发展经历了几个重要阶段，其标志的变化有：电解槽电流由24kA、60kA增加至100-150kA；槽型主要由侧插棒式（及上插棒式）自焙阳极电解槽改变为预焙阳极电解槽；电能消耗由吨铝22000kW·h降低至15000kW·h；电流效率由70%-80%逐步提高到85-90%。1980年开始，电解槽技术突破了175kA的壁垒，采用了磁场补偿技术，配合点式下料及电阻跟踪的过程控制技术，使电解槽能在氧化铝浓度变化范围很窄的条件下工作，为此逐渐改进了电解质，降低了温度，为最终获得高电流效率和低电耗创造了条件。在以后的年份中，吨铝最低电耗曾降低到12900-13200kW·h，阳极效应频率比以前降低了一个数量级。80年代中叶，电解槽更加大型化，点式下料量降低到每次2kg氧化铝，采用了单个或多个废气捕集系统，采用了微机过程控制系统，对电解槽能量参数每5s进行采样，还采用了自动供料系统，减少了灰尘对环境的影响。进入90年代，进一步增大电解槽容量，吨铝投资较以前更节省，然而大型槽（特别是超过300kA）能耗并不低于80年代初期较小的电解槽，这是由于大型槽采取较高的阳极电流密度，槽内由于混合效率不高而存在氧化铝的浓度梯度；槽寿命也有所降低，因为炉帮状况不理想，并且随着电流密度增大，增加了阴极的腐蚀，以及槽底沉淀增多，后者是下料的频率比较高，而电解质的混合程度不足造成的。尽管如此，总的经济状况还是良好的。90年代以来，电解槽的技术发展有如下特点：（1）电流效率达到96%；（2）电解过程的能量效率接近50%，其余的能量成为电解槽的热损而耗散；（3）阳极的消耗方面，炭阳极净耗降低到0.397kg/kg（Al）；（4）尽管设计和材料方面都有很大的进步，然而电解槽侧部仍需要保护性的炉帮存在，否则金属质量和槽寿命都会受负面影响；（5）维护电解槽的热平衡（和能量平衡）更显出重要性，既需要确保极距以产生足够的热能保持生产的稳定，又需要适当增大热损失以形成完好的炉帮，提高槽寿命。我国的电解铝工业可自1954年第一家铝电解厂（抚顺铝厂）投产算起，至2010年已有56年历史，在电解槽设计中，已掌握“三场”仿真技术，在模拟与优化方面采用了ANSYS4和MHD等软件；能较好的处理电解槽的磁场、流场、热-电平衡等问题，为大型和特大型预焙槽的设计和制造奠定了基础。我国近几年开发应用的200kA及其以上容量的大型预焙铝电解槽均取得了较好的技术经济指标，以目前已开发应用的最大容量铝电解槽——350kA预焙槽为例，主要技术经济指标为：电流效率94.43%；直流电耗13310kW·h/t（Al）；阳极净耗397kg/t(Al)。1.2所设计电解槽阳极结构的特点在铝电解生产中，由于所采用的冰晶石—氧化铝熔盐电解体系具有温度高、腐蚀性强等特点，作为阴、阳两极的导电材料，消耗量非常大。迄今为止能够抵御这种强高温熔盐的腐蚀、且价格低廉而又具有良好导电的，唯有炭素制品。因此，铝工业上均采用炭素电极——炭阴极和炭阳极。阳极在电解槽的上部，是铝电解槽的心脏，它承担向电解槽导入直流电和参与电化学反应的任务，阳极质量和工作状况的好坏，直接影响着铝电解生产的主要工艺技术指标，诸如能量效率和电流效率，同时也直接影响着铝电解的生产成本；此外，炭阳极质量优劣与铝电解生产过程的稳定性和工人的劳动强度紧密相关。铝电解生产对炭素阳极的基本要求如下：1.要求阳极具有良好的物理化学性能，减少阳极对空气和二氧化碳反应活性，以求达到降低炭耗、延长阳极更换时间、减少电解槽含炭渣量的目的。2.要求阳极具有良好的电化学性能，以求达到提高阳极电化学反应活性，降低电解过程中电能消耗的目的。3.要求阳极杂质含量要少，以免在电解过程中进入成品而影响产品质量。4.要求阳极质量更均匀、更稳定，以求达到电解槽稳定操作和进一步降低阳极效应系数的目的。阳极的结构尺寸影响到电解槽的电、热场及其分布（即影响电压平衡与热平衡），从而影响到电解槽的能耗指标、电流效率指标以及阳极消耗指标，因此优化阳极结构尺寸具有显著意义。本设计采用的阳极尺寸为1600×700×570，阳极组数为28组，并在底部开两条宽1cm，深300mm的缝隙。阳极底部开沟促进了阳极气体向外界的排放，减少了其在阳极底部的停留时间和阳极底部气泡覆盖率，因此有利于减小阳极气体压降，从而有利于降低槽电压，达到节能目的；阳极底部开沟在促进阳极气体向外界排放的同时，还使电解质流速有所减小，有利于保持电解质流场的均匀与稳定，有利于槽内的传质传热，有利于减少阴极铝液与阳5极气体发生“二次反应”的机会，从而有利于提高电流效率。气泡在阳极底部停留时间的减少和电解质流场的改进有利于降低阳极效应系数。针对排气沟为通沟和非通沟两种情况的计算表明，采用通沟时流体的剧烈程度要小些，这是由于通沟的存在减小了流体在阳极周围流动的阻力，使流体运动更平稳。第二章铝电解槽结构简介现代铝工业已基本淘汰了自焙阳极铝电解槽，并主要采用容量在160kA以上的大型预焙阳极铝电解槽（预焙槽）。因此本章主要以大型预焙槽为例来讨论电解槽的结构。工业铝电解槽通常分为阴极结构、上部结构、母线结构和电气绝缘四大部分。各类槽工艺制