【作者】 刘坤；

【导师】 朱苗勇；

【作者基本信息】 东北大学 ， 钢铁冶金， 2008， 博士

【摘要】 氧枪是现代氧气炼钢的关键设备,其性能直接影响到炼钢生产的产量、质量、原材料消耗、生产作业率和环境等重要指标。氧枪性能的优劣取决于由氧枪出口喷射出的氧气射流特性。如将超音速聚合射流技术应用于转炉炼钢生产,,将大大提高炼钢的生产效率和节能效率。本文分别采用实验室射流测试实验、水模型实验、热态模拟实验及数值模拟等研究方法,系统地研究了聚合射流氧枪及传统超音速射流氧枪氧气射流行为特征及与炼钢熔池相互作用规律,其目的是为此技术的应用提供理论基础。主要的研究内容和结果如下：氧枪射流特性的物理模拟研究。利用微机控制液压伺服的多点压力快速扫描的氧枪检测系统,对常温下以空气模拟的射流进行了较为系统的研究。重点考察了单股射流中心线速度在不同驱动压力下的衰减规律；多股射流中心线相对于喷孔几何轴线的偏移规律；多股射流轴线速度的衰减规律；操作枪位对射流冲击面积的影响；以及由低密度氦气伴随的聚合射流流场的速度分布规律等。热态聚合射流物理模拟实验结果表明聚合射流比传统超音速射流具有减缓其轴向衰减及径向扩散,更加具有刚性、聚合性和对熔池更大的冲击性,使其在一定程度上保持中心氧气射流相对聚合的特征。氧枪射流特性的数值模拟研究。首先根据射流物理模拟测试实验结果对标准的k-ε双方程模型进行了修正；并运用FLUENT软件模拟了不同滞止压力下Laval喷管内的流动、传统超音速射流在不同的滞止压力和环境温度时的流动特征以及带有氦气低密度伴随流情况下,不同结构参数与工艺参数下聚合射流流场的流动特征。数值模拟结果表明超音速聚合射流氧枪在有低密度氦气伴随的情况下,能更大程度地减缓轴线上速度的衰减,核心区长度明显增加,使中心射流在距喷嘴更长距离内保持其初始速度及冲击动量。氧枪射流与炼钢熔池相互作用规律的物理模拟。水模型实验模拟鞍钢180t顶底复吹转炉冶炼过程,实验的相似准数为修正的Froude准数,几何相似比取为10：1。考察了不同的底枪布置,不同的顶、底吹流量、不同吹炼枪位下熔池的搅拌混合特征。确定了顶底复吹转炉最佳搅拌效果所对应的结构参数与工艺参数。实验结果表明聚合射流氧枪可以达到顶底复吹的搅拌效果,如能在转炉冶炼工艺中应用,可取消底吹系统,简化转炉设备,提高转炉炉龄,可引领转炉炼钢技术的变革。目前,聚合射流氧枪技术仅在国内宝钢等几家电炉上得到初步应用,其技术尚未公开。该项技术在转炉炼钢上的应用,国外仍处于工业试验阶段,而国内尚属空白。为此针对超音速聚合射流氧枪射流行为特征的数学物理模拟研究将为研制聚合射流氧枪和其在电炉及转炉中的应用起到一定的借鉴和指导作用,对于我国炼钢生产的进一步发展具有重要的理论价值和现实意义。更多还原

【Abstract】 The oxygen lance is the essential equipment for modern oxygen steelmaking process whose performance directly affects the steel-making production output, quality, raw material consumption, production work rate and environment and such kind of important targets and so on. The oxygen lance performance quality is decided by characteristic of the oxygen jet flow which sprays from the oxygen lance outlet. Steel-making production efficiency and the energy saving efficiency will be greatly improved if supersonic coherent jet flow technology is applied into converter steel-making. The laboratory jet flow test experiment, water model experiment, thermal state simulation model test and numerical simulation research methods were adopted respectively in this article which comprehensively and systematically gave the oxygen jet flow characteristics of the coherent jet flow oxygen lance and traditional supersonic jet flow oxygen lance as well as the rule of interaction in the steel-making molten bath, aiming at providing theory basis for this technology application. Main research content and result as follows:Physical modeling research on oxygen lance jet flow characteristic. Relatively systematic research on jet flow simulated by the normal temperature air was carried out by using rapid scanning oxygen lance examination system with the microcomputer control hydraulic servo’multi- spots pressure. The main research content includes:weakening rule of single- nozzle jet flow axis speed under different driving pressure; displacement rule of the muti-nozzle jet flow axis compared to nozzle geometry axis; weakening rule of multi- nozzle jet flow axis speed; influence on jet flow impact area due to different operation lance positions; coherent jet flow field velocity distribution rule with the low density helium and so on. The thermal state coherent jet flow physical modeling experiment result indicated that compared to the traditional supersonic jet flow, the coherent jet flow has characteristics such as slowing down its axial weakening and radial direction proliferation, more rigid, more coherent and bigger impact to a molten bath, maintaining the central oxygen jet flow relatively coherent to a certain degree.Numerical simulation research on oxygen lance jet flow characteristic. First the standard k-s double equation model was rectified according to the jet flow physical modeling experiment result. By FLUENT software, several kinds of jet flow were simulated, such as the jet flow in the Laval nozzle under different stagnation pressure, the traditional jet flow without helium accompanying under different stagnation pressure and surrounding temperature,or with the low density helium accompanying flow or under different design parameters and process parameters. The numerical simulation result indicated the supersonic coherent jet flow oxygen lance with low density helium can greatly slow down the weakening of axis speed,increase core area length, make central jet flow maintain its initial velocity and the impact momentum within longer distance apart from the nozzle.Physical modeling research on interaction rule of oxygen lance jet flow and molten bath. Water model experiment was simulated according to Anshan Iron and Steel Company’s 180t top-bottom converter process and the experiment similarity number was the revision Freud number with geometry analogue ratio 10:1. The water mold experiment was carried on under the condition of different bottom lance arrangement, different top-bottom blowing current capacity, different blowing lance position. The experiment not only gave the design parameters and the structure parameters for best stirring top-bottom converter, but also showed that the coherent jet flow oxygen lance may achieve the result of top-bottom converter stirring effect. If the coherent jet flow oxygen lance can be applied in the converter, bottom blowing system of converter can be canceled. In that case, not only the converter equipment can be simplified, but also the converter lining life can be improved, as well as the steel-making technology transformation.At present, the coherent jet flow oxygen lance technology only obtains the preliminary application in several electric furnaces like domestic Baoshan Steel Corporation’s due to its technology security. This technology application in the overseas converter steel-making is still at the test stage, while blank domestically. So mathematical and physical analogue research on supersonic coherent jet flow oxygen lance characteristics can play certain model and instruction role in researching coherent jet flow oxygen lance and its application in electric furnace and converter, providing important theory value and practical significance for steel-making development of our country.更多还原