Combustion and energy balance of aluminum holding furnace with bottom porous brick purging system

For acquiring the details in aluminum holding furnace with bottom porous brick purging system, efforts were performed to try to find out the potential optimal operation schemes. By adopting transient analysis scheme and constant boundary temperature, combustion in the furnace was investigated numerically using computational fluid dynamics (CFD). The predicted gas temperature shows good agreement with the measured results, and the predicted energy distribution of the furnace is consistent with that obtained from energy balance experiment, which confirms the reliability of the numerical solution. The results show that as the fuel-air mixture temperature rises up from 300 K to 500 K, the energy utilization of the furnace could increase from 34.55% to 37.14%. However, as the excess air coefficient increases from 1.0 to 1.4, energy utilization drops from 34.55% to 29.56%. Increasing the combustion temperature is the most effective way to improve the energy efficiency of the furnace. High reactant temperature and medium excess air coefficient are recommended for high operation performance, and keeping the furnace jamb sealed well for avoiding leakage has to be emphasized.     

中国炭素工业生产节能减排主要技术浅析

重点分析了炭素生产过程中的主要节能和减排技术,包括生产设备、生产工艺、余热利用技术以及生产过程中的烟尘处理技术;并指出了我国炭素生产节能减排技术的研究重点和发展趋势。     

敞开式阳极焙烧炉运行状况分析及优化

重点阐述了焙烧炉主要性能指标及其影响因素,从产品质量、能耗、焙烧曲线及生产操作方面分析了某厂焙烧炉运行状况,得到产品质量中等水平、炭块氧化严重、焙烧曲线升温速率设置不合理等结论,并找到了阳极炭块严重氧化的根本原因。通过优化曲线及生产操作工艺,产品质量指标略有提升,解决了炭块氧化问题;系统转弯时间段采用7室运转方式,移炉操作中停火时间由原来的15 min缩短至5 min,系统天然气单耗降低了3 m~3/t。     

生阳极干料配方优化研究与应用

为了获得干料最大振实密度,在分析干料中各成分的颗粒筛分纯度的基础上,开展不同干料配方下的振实密度试验。通过优化粗焦、中焦和细焦的配料比例,使干料振实密度由原来的1.1845 g/cm~3提高到1.2336 g/cm~3,再通过优化球磨料的比例,确定最佳配入量在25%～35%之间,两次优化后振实密度比现有配方提高了0.065 g/cm~3左右。生阳极干料配方优化结果表明,生坯体积密度平均值由原来的1.5516 g/cm~3提高到1.6113 g/cm~3,优化效果明显。     

罐式炉低温煅烧理论的研究与应用

通过实验室研究,分析罐式炉煅后焦晶粒尺寸和煅后焦质量指标与最高煅烧温度的关系,得到如下结论:煅后焦最高煅烧温度控制在1200～1250℃,较传统的罐式炉工艺低50～100℃,更加适合预焙阳极的生产。鉴于此提出罐式炉低温煅烧理论,并通过现场应用,实际应用结果表明:同尺寸的炉型,低温煅烧产量较传统的高16%;煅烧焦真密度基本控制在2. 05～2. 07g/cm3之间;煅烧焦粉末电阻率控制在448～540μΩ·m范围内;而煅烧焦CO2反应率基本保持在6%～10. 5%。罐式炉低温煅烧理论不仅能满足煅后焦质量要求,更能减少预焙阳极在电解槽上的掉渣。     

Numerical simulation of aluminum holding furnace with fluid-solid coupled heat transfer

To predict three-dimensional temperature distribution of molten aluminum and its influencing factors inside an industrial aluminum holding furnace, a fluid-solid coupled method was presented. The fluid-solid coupled mathematics models of aluminum holding furnace in the premixed combustion processing were established based on mass conservation, moment conservation, momentum conservation, energy conservation and chemistry species conservation. Computational results agree well with the test data of the typical condition. The maximum combustion temperature is 1 850 K. The average temperature of the molten aluminum is 1 158 K, and the maximum temperature difference is about 240 K. The average temperature increases 0.3 °C while the temperature of combustion air increases 1 °C. The optimal excess air ratio is 1.25–1.30.     

提高罐式煅烧炉产品质量的方法浅析

结合罐式煅烧炉生产实践,对生产操作中提高罐式煅烧炉产品质量的方法进行了分析,主要通过原料混配、正确处理罐壁结焦、合理设置测温点及正确选用热电偶以及采用改进的空炉操作等方法,使罐式煅烧炉生产运行稳定,产品质量和产量均得以提高.     

铝用阳极中杂质的分析与措施对策

铝电解槽的大型化,对预焙炭阳极质量提出了越来越高的要求。随着生产实践以及科学研究的不断深入,阳极中杂质的作用与影响也越来越引起人们的重视。阳极中的杂质与铝电解过程中阳极过度氧化、掉渣有直接联系,某些杂质影响到电解槽电流效率和铝的纯度等经济技术指标。所以在阳极生产过程中,对其杂质成分进行有效的监测与控制是十分有必要的。本文就铝用阳极中杂质的种类与来源,杂质对阳极的影响以及在电解过程中的作用分别进行了阐述,并对如何降低杂质含量做了探讨。     

经股动脉行介入诊疗术后股动脉止血贴的应用

目的观察经股动脉行介入诊疗术后股动脉穿刺点应用股动脉止血贴（V＋PAD）的临床效果。方法应用随机排列表随机入选８０例行冠状动脉介入诊疗的患者,其中偶数应用止血贴共４０例作为试验组,奇数应用徒手压迫不使用止血贴共４０例作为对照组。所有患者均签订知情同意书。观察两组的按压时间、止血后穿刺点的处理、患者卧床姿势、下床活动时间、患者的舒适度、出院前穿刺点并发症情况。结果两组患者年龄、性别构成比、激活凝血时间和血压差异均无统计学意义（P＜０．０５）,但试验组和对照组的压迫时间分别为（７．９±０．５）min和（１９．８±５．１）min,卧床时间分别为（６．１±５．０）h和（２３．９±０．２）h,两组间差异均有统计学意义（P值均＜０．０１）。试验组所有患者在拔管后即刻均采用床头抬高３０°卧位,１h后将床头抬高９０°,常压包扎,不制动,所有患者舒适度明显提高。试验组有１例比较肥胖的女性发生假性动脉瘤,其余入选患者在住院期间均未出现穿刺处并发症。结论股动脉止血贴止血迅速,效果确切,患者舒适度明显提高,减轻了医护人员的工作量,可以在临床大规模推广应用。     

Numerical simulation on melt flow with bubble stirring and temperature field in aluminum holding furnace

The numerical model for predicting the flow and temperature fields of the melt in holding furnace with porous brick purging system were set up using Euler-Lagrange approach.In this model,bubbles coalescence and disintegration were ignored based on the dimensionless analysis,and the bubble size was assumed to be obedient to Rosin-Rammler distribution with a mean size of 0.6 mm.The results show that on reference operating condition,during the heating and agitation process,melt mixes well in the furnace,and th...