Cold Model Study on Mg Desulfurization of Hot Metal Under Mechanical Stirring

The new method of in-situ desulfurization with mechanical stirring of new type impellers was introduced,in which the bubble′s dispersion and disintegration of magnesium vapor were the key to boosting the desulfurization efficiency and increasing the utilization rate of magnesium.Effects of different new type of impellers on bubble dispersion and disintegration were studied through bubble image analysis,gas-liquid mass transfer,and power consumption levels of different impeller structures.The results showed that the sloped swept-back blade impeller-2produces optimal bubble′s dispersion and disintegration,as well as higher volumetric mass transfer coefficient and CO2gas utilization while consuming the least power.Numerical simulation result with Fluent software also showed that the sloped swept-back blade impeller-2has higher turbulent kinetic energy and better velocity distribution than the other two impellers.     

Improvement of Impeller Blade Structure for Gas Injection Refining under Mechanical Stirring简

Abstract： The impeller blade structure for gas injection refining under mechanical stirring has been explored by water model experiments. A sloped swept-back blade impeller is＇proposed for the purpose. The central part of the impeller is disk- or plate-shaped, and the blades are fitted to the side of the disk or plate. In addition, a disk is put on the top side of the impeller blades. The impeller can strengthen the radial and downward flow between the blades and weaken the swirl flow in the zone above the impeller. These effects on flow phenomena are favorable for disintegration and wide dispersion of bubbles which are injected from a nozzle attached to the center of the underside of the impeller. In addition, the sloped swept-back impeller requires less power consumption. The impeller shaft should be placed away from the vessel center so as to disperse the injected bubbles widely in the bath under mechanical stirring even with unidi- rectional impeller rotation and without installing baffles. The number of gas holes in the nozzle and the direction of gas injection have a little effect on the bubble disintegration and dispersion in the bath. Highly efficient gas injection refining can be established under the conditions of proper impeller size, larger nozzle immersion depth, larger eccen- tricity and rotation speed of the impeller. The sloped swept back blade impeller can decrease the power consumption and vet improve the bubble disintegration and wide dist~ersion in the bath.     

CO2吸收模型中容积传质系数的确定

气泡微细化是“原位机械搅拌法铁水炉外脱硫技术”的关键.气液传质系数是研究气液吸收过程的基本参数.本文根据相似性原理建立水模型实验装置,并通过测定NaOH吸收CO2的速率来研究气泡微细化过程,同时根据吸收原理定量计算出容积传质系数Ak及CO2气体利用率η.当溶液pH值从12降低到9的过程中,容积传质系数为2.938×10 4m3/s,本实验所用CO2的利用率的公式可简化为:η=18.98/Qt.本论文的研究结果可为进一步研究吸收速率提供理论依据.     

Effect of Elliptical Snorkel on the Decarburization Rate in Single Snorkel Refining Furnace

In the present work, physical model experiments were performed to investigate the effect of elliptical snorkel on the decarburization in single snorkel refining furnace. A round snorkel with the same cross‐section area as the elliptical snorkel was also made for comparison. Bubble behavior was recorded by a high speed video camera in this study. A volumetric mass transfer coefficient kA/V was used to evaluate the decarburization rate. Measurement of the volumetric mass transfer coefficient kA/V was made by means of the carbon dioxide desorption from a NaOH solution. It is found when the plug location is close to the center of the ladle bottom, almost all the bubbles get into the snorkels. However, when the plug location is too far away from the center of ladle bottom, bubbles will escape from the outside of the snorkel. kA/V generally rises with increasing gas flow rate. Moreover, kA/V is increased when the plug is moved from the center to the half radius of the ladle bottom. However, kA/V is decreased when the plug is moved from the half radius of ladle bottom to the ladle sidewall. It is indicated that kA/V for the elliptical snorkel is larger than that for the round one when the plug is located between the center and half radius of ladle bottom. Nevertheless, when the plug is located between the half radius and the ladle sidewall, the kA/V for the elliptical snorkel is smaller than that for the round one.     

Numerical and Experimental Study on Fluid Dynamic Features of Combined Gas and Electromagnetic Stirring in Ladle Furnace

Basic fluid dynamic features of combined electromagnetic stirring, EMS, and gas stirring (EMGAS) have been studied in the present work. A transient and turbulent multiphase numerical flow model was built. Simulations of a real size ladle furnace were conducted for 7 cases, operating with and without combined stirring and varying the argon gas inlet plug position. The results of these simulations are compared considering melt velocity, melt turbulence, melt/slag‐interface turbulence and dispersion of gas bubbles. An experimental water model was also built to simulate the effects of combined stirring. The water model was numerically simulated and visual comparison of the gas plume shape and flow pattern in the numerical and in the experimental model was also done for 3 flow situations. The results show that EMGAS has a strong flexibility regarding the flow velocity, gas plume, stirring energy, mixing time, slag layer, etc.     

转炉冶炼N80顶吹N_2后搅拌技术研究

通过对转炉冶炼N80顶吹N2进行后搅拌的工业试验研究,探讨了顶吹N2对熔池温度及成分的影响。结果认为,顶吹强度4.0~4.5 m3/(t·min)的N2,喷吹时间≤1.5 min时,熔池平均增氮量仅为0.000 033%,平均增氮速率为0.000 01%/min;对碳含量有一定的影响,平均脱碳速率为0.005%/min;对磷含量影响明显,平均脱磷速率为0.002 2%/min;温降较大,平均温降速率为15.4℃/min;顶吹N2前后炉渣中铁的氧化物含量未出现明显的规律性变化。     

利用NaOH水溶液-CO2系模型研究中间罐钢液的吸气速率

建立了盛钢桶到中间罐钢液吸气的物理模型，利用NaOH水溶液－CO2系模型来研究注流及中间罐液面的吸气（CO2）速率，从而考察操作参数对中间罐钢液吸气速率的影响。结果表明：氧分压、注流半径增加时，熔池内钢液的吸气速率提高；注流速度增加时，中间罐液面的吸气速率提高；另外，中间罐结构对中间罐液面吸气速率也有影响。     

钢铁联合企业CO2排放研究综述

摘 要：回顾了近年来国内外研究钢铁联合企业CO₂排放的文献,建立了钢铁生产过程碳素流模型;总结和分析了钢铁联合工业影响CO₂排放因素;介绍了国外利用reMIND和CLPEX建立的过程集成优化分析生产成本和CO₂排放量的模型;总结了钢铁联合企业CO₂排放量的估算方法和注意事项;提出我国钢铁联合企业目前应该加快建立适合本国钢铁联合企业温室气体排放计算标准和方法;展望了钢铁联合企业研究CO₂排放的研究方向。     

吸收烟气中低浓度CO2的操作条件分析

Mg(OH)2浆液是一种具备低再生能耗潜力的CO2吸收剂,为了推进其在CO2捕集领域的应用而展开研究。在填料塔中,使用真实烟气研究了各种操作条件下Mg(OH)2浆液对CO2的捕集效率。研究发现,填料种类、气体名义停留时间、液气比均对CO2捕集效率有影响。结果表明,增加气体名义停留时间无法有效改善液相传质,而提高液气比能够有效改善液相传质;在试验条件下,拉西环、鲍尔环和IMTP的总体积传质系数分别为8.5×10-7～5.0×10-6、1.8×10-6～4.0×10-6和1.9×10-7～2.9×10-6 mol/(m3·s·Pa)。