基于氧气高炉工艺条件的熔融滴落带炉料冶金行为研究

发布时间：2018-07-03 11:52

本文选题：氧气高炉 + 熔融滴落带　；参考：《北京科技大学》2017年博士论文

【摘要】：随着空气中雾霾的加剧,钢铁企业环保压力也在不断增加。高炉炼铁是钢铁企业能源消耗和CO_2及其它污染物排放最高的生产环节,要实现减排,炉顶煤气循环-氧气鼓风高炉炼铁技术(简称氧气高炉)是节碳减排潜力最大且最可能工业化的炼铁技术之一。该工艺含铁炉料间接还原度高、低焦比、大喷煤等特点,导致炉料在熔融滴落带的冶金行为发生变化。本文基于焦炭和炉渣,进行两方面的研究。第一部分是熔融滴落带炉渣对焦炭的溶蚀研究;第二部分是炉渣在焦炭床的流动行为研究。本研究结果将为氧气高炉工艺下熔融滴落带的焦炭劣化和高炉下部透气透液性提供理论基础。首先,采用自行设计的动态溶蚀装置,进行了炉渣对焦炭的动态溶蚀实验研究。根据炉料在块状带还原度、冶炼强度、反应温度,研究了渣中FeO含量、温度、反应时间对焦炭动态溶蚀的影响,进行了三因素三水平的正交实验,通过失重率和直径变化确定焦炭劣化程度,实验发现溶蚀时间影响最大,FeO含量次之,最后为温度;根据焦炭在块状带的气化,开展了炉渣对水蒸气和CO_2气氛下气化后焦炭的溶蚀研究,通过失重率、孔隙率、孔径分布和微观形貌表征焦炭的变化,在此基础上进行了模拟高炉气氛下的气化和溶蚀,采用I型转鼓法和纳米力学探针法对其强度进行检测;通过动力学分析,对炉渣对焦炭的溶蚀步骤和机理进行分析,得出FeO含量为10%时的溶蚀反应活化能为177.34 KJ/mol,并确定了控速环节。结合氧气高炉的实际条件,说明焦炭在熔融滴落带的溶蚀减弱,有利于保持其高温性能。然后,对炉渣在熔融滴落带焦炭床的滞留行为进行了热态实验研究。根据高炉下部炉料变化,研究了温度、炉渣碱度、炉渣Al/Si比、焦炭床粒度和种类对滞留行为的影响;在此基础上,进行了燃料对高炉下部炉渣滞留行为的研究,包括炉渣吸收燃料灰分和未燃煤粉及焦炭加入兰炭对滞留的影响,结果表明,炉渣吸收灰分和未燃煤粉后,滞留量明显增大。结合"液泛"极限条件和高炉参数,确定了最大滞留量为11.52%,传统高炉和氧气高炉煤粉的燃尽率应大于78.56%和83.92%,兰炭在氧气高炉-煤化工工艺中应控制加入量在30%以内;结合小型解剖高炉软熔带和滴落带压降以及最大滞留量,提出了氧气高炉"骨架焦比"的计算方法和数值。最后,基于上述热态实验,分别进行了冷态模拟和数值模拟研究。通过自行设计的液体穿行狭缝的冷态实验装置,采用硅油-水系统模拟高炉滴落带炉渣-铁水在焦炭床狭缝中的穿行行为,获得液体的流动状态、速度和压差等参数,根据数据可得液体粘度和流动速度的关系为v =-29.1η + 17.72,液滴流动速度和气体流量的关系为v =-1.72Q + 0.823Q~2-0.147Q~3+5.316,由此得到硅油-水溶液中,气体流速为0.395 m/s产生"液泛";通过VOF二维模型系统的模拟了不同物性的渣相、铁相和渣-铁两相以及在不同气体流速下,液体穿行焦炭空隙的流动行为。确定了液滴受力为:2πσ[(17-Rsinφ_1)sin(φ_1-θ)+(17-Rsinφ_2)5in(φ_2+π + θ]-4/3πr~3ρg + f。根据模拟结果发现:渣滴越小、接触角越小、粘度越大以及表面张力越大都会抑制炉渣的顺利滴落;对于渣铁两相的流动,由于两相接触面上界面张力方向相反,使得铁水流动受阻,而炉渣流动更加顺畅;结合氧气高炉参数和模拟结果,说明渣铁在穿行焦炭空隙时更易滴落。
[Abstract]:With the intensification of fog and haze in the air, the environmental pressure of iron and steel enterprises is increasing. Blast furnace ironmaking is the highest production link of energy consumption and CO_2 and other pollutants in iron and steel enterprises. To achieve emission reduction, the top gas cycle of the furnace top gas cycle - oxygen blast furnace ironmaking Technology (abbreviated oxygen high furnace) is the most potential and most likely industrialization One of the technology of iron smelting. This process contains the characteristics of high indirect reduction degree, low coke ratio and large coal injection, which leads to the change of metallurgical behavior of furnace material in molten drop zone. Based on coke and slag, two aspects are studied in this paper. The first part is the study on the dissolution of coke in molten drop zone; the second part is the slag in coke bed. The results of this study will provide a theoretical basis for the deterioration of the coke and the permeability of the bottom of the blast furnace under the process of oxygen blast furnace. First, the dynamic dissolution test of the coke is carried out by the dynamic dissolution device designed by ourselves. The effect of FeO content, temperature and reaction time on the dynamic corrosion of coke was studied. The orthogonal experiment of three factors and three levels was carried out. The degree of coke deterioration was determined by the weight loss rate and the change of diameter. The experiment found that the dissolution time had the greatest influence, the content of FeO was the second, and the temperature was last. The slag to water was carried out according to the gasification of coke in the lump zone. The corrosion of coke after vaporization in vapor and CO_2 atmosphere was studied. The change of coke was characterized by weight loss rate, porosity, pore size distribution and Micromorphology. On this basis, gasification and corrosion were simulated under the atmosphere of the blast furnace. I type drum method and nanomechanical probe method were used to detect the strength of the coke. The process and mechanism of the dissolution of carbon were analyzed, and the activation energy of the dissolution reaction was 177.34 KJ/mol when the content of FeO was 10%, and the speed control link was determined. The effects of temperature, slag basicity, slag Al/Si ratio, particle size and type of coke bed on the retention behavior are studied according to the change of the lower furnace burden. On this basis, the study on the retention behavior of the lower furnace slag in the blast furnace is carried out, including the ash and unburned pulverized coal and the coke added to the char. The result shows that the retention of the slag and unburned pulverized coal is obviously increased after the slag absorption and unburned pulverized coal. The maximum retention amount is 11.52%, the burning rate of the traditional blast furnace and the oxygen blast furnace pulverized coal should be greater than 78.56% and 83.92%, and the carbon in the oxygen blast furnace and coal chemical process should be controlled by 30% in the combination of the "liquid flooding" limit conditions and the blast furnace parameters. In addition, the calculation method and numerical value of the "skeleton coke ratio" of the oxygen blast furnace were put forward by combining with the pressure drop of the small dissection blast furnace and the drop zone and the maximum retention amount. Finally, the cold state simulation and numerical simulation were carried out on the basis of the above hot state experiments. The relationship between the flow state of liquid, velocity and pressure difference is obtained by simulating the behavior of slag and molten iron in the slit of the coke bed. The relationship between the viscosity and flow velocity of the liquid is v =-29.1 ETA + 17.72 according to the data. The relationship between the flow velocity of the droplet and the flow rate of the liquid is v =-1.72Q + 0.823Q~2-0.147Q~3+5.316, thus the silicon is obtained. In the oil and water solution, the gas flow velocity is 0.395 m/s and produces "liquid flooding". Through the VOF two-dimensional model system, the slag phase of different physical properties, the iron phase and the slag iron two phase and the flow behavior of the liquid through the coke air gap at different gas flow velocities are used to determine the droplet force as: 2 pi sigma [(17-Rsin [[[[[[[[sin]) + (17-Rsin [[[[[[[[[Phi] _2) 5in ([Phi] _2+ PI + theta]-4 According to the simulation results, /3 PI r~3 P G + F. shows that the smaller the droplet, the smaller the contact angle, the greater the viscosity and the more the surface tension will restrain the smooth dripping of the slag; for the flow of the slag and iron, the flow of the molten iron is obstructed by the opposite direction of the interfacial tension on the two phase contact surface, and the flow of the slag is smoother; and the parameters and modes of the oxygen blast furnace are combined. The results show that slag iron drips more easily when passing through the coke gap.
【学位授予单位】：北京科技大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TF53

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