【作者】 刘增勋；

【导师】 吕庆；

【作者基本信息】 东北大学 ， 钢铁冶金， 2009， 博士

【摘要】 高炉冷却壁是高炉主要冷却设备之一,冷却壁安全工作是高炉长寿的前提。在炉腰和炉腹高负荷区域,冷却壁表面形成稳定渣皮,对冷却壁起到保护作用。渣皮厚度和形貌取决于冷却制度和工艺条件,同时又影响到冷却壁工作状态。本文针对铸铁冷却壁、铜冷却壁和铜钢复合冷却壁,分别建立了稳态和非稳态传热数学模型,分析冷却壁传热、渣皮分布和生长规律。采用热力耦合方法,对铜钢复合冷却壁进行热应力分析。传热和应力模型均选用有限元分析软件ANSYS完成建模、网格划分和模型计算。主要研究工作如下:利用ANSYS的单元生死功能模拟渣皮熔化,建立了新的冷却壁稳态传热分析方法(即渣皮熔化迭代法),解决了目前冷却壁研究中无法确定渣皮厚度的问题,提高了冷却壁传热分析的精度和实用性。根据冷却壁工作环境,选用荷重软化方法测定渣皮承载能力,确定冷却壁表面的挂渣温度为1100℃。利用建立的传热分析模型,对三种材质的冷却壁进行稳态传热分析,研究了工艺因素和冷却制度对壁体温度、渣皮厚度和热负荷的影响。在稳态传热分析的基础上,利用ANSYS的单元生死功能创立了渣皮再生分析法,首次实现了渣皮脱落后再生过程的非稳态传热分析。采用建立的非稳态传热模型分别对铜冷却壁和铜钢复合冷却壁的渣皮恢复过程进行研究,分析了渣皮脱落后的生长规律、冷却壁温度和热负荷变化过程,以及工艺条件对渣皮恢复和铜壁稳定时间的影响。采用渣皮熔化迭代方法,在不同工况下对铸铁冷却壁进行稳态传热分析。结果表明,炉气温度是影响渣皮厚度、热负荷及冷却壁温度的主要因素,提高冷却强度对冷却壁的影响不明显。铸铁冷却壁安全工作温度为1280℃,能够承受的安全热负荷为39.6kW/m~2。增加水管直径和减少气隙宽度可以改善冷却壁承受能力。渣皮脱落致使冷却壁温度急剧升高,严重危害冷却壁寿命。在冷却壁烧毁后,采用炉壳打水将使热损失急剧增加。只有在炉气温度较低时,才能使炉壳与水管之间充满固体渣层。通过铜冷却壁稳态传热分析发现,在高度方向上铜冷却壁渣皮分布不均匀,铜筋部位渣皮较厚,燕尾槽部位较薄。随着炉气温度上升,渣皮不均匀性增加,容易脱落。炉渣性质对铜冷却壁的温度、热负荷和渣皮厚度影响较大。在炉渣粘度较高时,渣皮厚度增加,温度波动会造成结瘤。在渣皮再生过程中,渣皮生长遵循幂函数规律,初期生长较快,随后生长速度逐渐降低。炉气温度对挂渣过程有明显影响。铜壁稳定时间为10.5～32.7min,铜壁最高温度为140℃。分析结果与铜冷却壁运行实践基本一致。在稳态和非稳态传热分析的基础上,对铜钢复合冷却壁进行了热力耦合分析,研究其挂渣能力和工作安全性。结果表明,铜钢复合冷却壁挂渣能力与铜冷却壁基本相当,渣皮稳定时最高温度为120℃,铜壁和界面最大等效应力分别为122MPa和87MPa。在渣皮再生过程中,铜壁稳定时间为17.6～46.4min。最高铜壁温度上升到166℃,铜壁和界面最大等效应力分别达到171MPa和127MPa,在生产中不会产生铜壁塑性变形和铜钢界面分离现象。模型分析结果与生产试验情况基本一致。更多还原

【Abstract】 BF stave is one of main cooling equipments of the blast furnace. To keep the staves in safety is necessary for BF to attain a long life. The steady slag skull that protects the staves is formed on the surface of the staves in the higher heat load areas such as belly and breast of BF. The thickness and shape of slag skull depended on cooling parameters and process conditions. At the same time, they have influence on the stave state. The mathematic models of steady and unsteady thermal transfer of BF staves made of cast iron, copper and compound copper-steel were established respectively, which were used to analyze stave conduction, slag skull distribution and growing process. The thermal stress of copper-steel compound stave was studied with the method of thermal mechanical coupling. Finite element analyzing software ANSYS was taken to build model, mesh and calculate. The main researches are as follows:A new analysis method of steady thermal transfer was established by simulating slag skull melting through ’Element Birth and Death’ of ANSYS, called as ’Slag Skull Melting Iteration’. The problem that the slag skull thickness could not be ascertained presently was solved. The accuracy and practicability of thermal transfer analysis about stave was improved. According to working condition of BF staves, the refractoriness under load was used to describe the adhesion capacity of slag skull. The adhesion temperature was defined as 1100℃. The steady thermal transfer analysis about three kinds of stave with different materials was carried out through the model built in this research. The influence of process condition and cooling parameters on the body temperature, slag skull thickness and heat load was studied.Based on steady thermal transfer analysis, the stimulating method for slag skull recovery was created through ’Element Birth and Death’ of ANSYS. For the first time, the unsteady thermal transfer analysis was actualized during slag recovering after dropping off. On the unsteady thermal transfer model, the slag skull recovering process on the surface of copper and copper-steel staves was studied. The growth rhythm of slag skull, as well as varying of stave temperature and heat load was analyzed. The influences of process conditions on the stabilization time taken by slag skull recovering and copper body steadying were also researched.By means of the slag skull melting iteration, the unsteady thermal transfer analysis about cast iron stave in different process conditions was performed. The results showed that gas temperature was the main factor that affected slag skull thickness, heat load and stave temperature. Increasing intensity of cooling had no obvious effect on stave. The safe temperature for cast iron stave was 1280℃. In addition, the safe heat load was 39.6kW/m~2. The standing capacity of stave was improved by increasing the pipe diameter and decreasing gap width. The slag skull dropping off made the stave temperature rise rapidly, which decreased the life of stave. After the stave had been burned out, spraying water on the shell would increase heat loss enormously. Only when gas temperature was lower, there was solid slag filled among the water pipes and the shell.The results showed that slag skull was not distributed uniformly on the surface of copper stave in height through analysis of the steady thermal transfer about copper stave. There was thicker slag skull on the surfaces of copper ribs. In addition, the slag skull thickness was thinner in the front of the inlayed bricks. As gas temperature went up, no uniformity was ascending and the slag skull was easier to drop off. The slag property had larger influence on copper stave temperature, heat load and slag skull thickness. When slag velocity was higher, slag skull thickness increased. If gas temperature changed, the heel would be formed. During slag skull recovery, slag skull growth followed the power function. In the primary stage, slag skull grew more quickly. Subsequently the growing rate decreased. Gas temperature had obvious influence on slag adhering. The stabilization time was 10.5~32.7min. The maximum temperature of copper body was 140℃. The analysis results were consistent to process experience of copper stave.On the foundation of steady and unsteady thermal transfer analysis, coupled thermo-mechanical analysis about copper-steel compound stave was performed to investigate slag adhering capacity and safety. The results showed that slag adhering capacity of copper-steel stave was the same as copper stave. When slag skull was stable, the maximum temperature in the stave is 120℃. There was the maximum equivalent stress 122MPa in the copper body and 87MPa on the interface of copper plate and steel plate. The stabilization time is 17.6~46.4 minutes during slag skull recovery. The maximum temperature in the copper body went up to 166℃. The maximum The copper body and interface equivalent stress rose respectively to 171MPa and 127MPa. Therefore, there would not be plastic deformation in the copper body and separation between copper plate and steel plate. The results from the model were consistent to process experience in test.更多还原