The study of the effect of gas-phase fluctuation on slag flow and refractory brick corrosion in the slag tapping hole of an entrained-flow gasifier

The service life of refractory brick in the slag tapping hole of the entrained flow gasifier was significantly lower than that in other locations.It was critically important to study the corrosion mechanism of refractory brick in the slag tapping hole for guiding industrial production.Considering the complex flow field in the slag tapping hole,the influence of gas velocity and temperature fluctuation on the service life of refractory brick was investigated in this study.The results showed that the slag flow characteristics periodically changed with the gas temperature and velocity fluctuations.The brick corrosion rate increased with the decrease of fluctuation frequency.Compared with the gas-phase velocity fluctuation,the gasphase temperature fluctuation had a more significant influence on the brick corrosion rate.When the fluctuation frequency was 0.01 Hz and the gas temperature fluctuation amplitude was 200 K,the corrosion rate of refractory bricks increased by 25%.It could be concluded that the fluctuation of gas-phase temperature was the main cause for the low service life of refractory bricks in the tapping hole.

Baosteel's Slag Short Flow process for molten steelmaking slag treatment and its application

Baosteel＇ s Slag Short Flow（BSSF） is an innovative process for steelmaking slag treatment that was developed by Baosteel. The process principles, flow-chart, parameters and component systems of the BSSF for steelmaking slag treatment are presented. Characteristics of the finished BSSF slag are summarized by analyzing the slag＇ s physical and chemical performances. Several Utilization methods for the BSSF slag are given.

钻井法凿井气-液-固耦合排渣流场及刀盘吸渣口优化

针对西部地区侏罗系地层煤矿立井钻井法施工中出现的气举反循环洗井排渣与钻进效率低下问题,以陕西可可盖煤矿中央回风立井ϕ4.2 m超前钻井为工程背景,基于CFD-DEM(计算流体力学和离散单元法耦合)研究方法,建立了气-液-固多相耦合排渣数值模型,揭示了排渣管内、井底流场的速度及压力分布规律,并基于自研的气举反循环排渣试验装置,采用PIV(粒子图像测速法)测试技术对流场分布的正确性进行验证;提出了优化刀盘吸渣口评判指标和方法,对吸渣口的数量、长径比、面积比、总面积占比进行优化,得到了超前钻头刀盘吸渣口布置的最佳方式和相关参数;讨论了钻头转速、注气量、风管没入比和泥浆黏度等主要因素对排渣流场的影响。研究结果表明:(1)排渣管内流体的运移以轴向流动为主,且途经注气端时,流速发生跳跃式剧增;井底流体的运移主要以水平流动为主,流体的垂直上返仅存在于吸渣口附近;井底流体的水平流动以切向流动为主,径向流动仅在吸渣口两侧较为明显,且远离吸渣口处,径流速度较小易产生岩屑沉积;(2)当刀盘吸渣口数量为2,长径比为0.4,面积比为1,总面积占比为1.94%时,吸渣口的布置方式最佳,且清渣率较现行吸渣口布置方式提高66%;(3)增大钻头转速可显著增强吸渣口的吸附作用,注气量、风管没入比与井底和排渣管内流体的轴向速度均呈正相关关系,低黏、低密度的泥浆易获取高流速,但携岩能力较差。研究结果可为破解侏罗系地层深大立井钻井法洗井排渣与钻进效率低下技术难题,提供有益的理论参考。

气化炉内熔渣流动特性预测模型的研究进展

双碳战略目标下,煤气化技术将会是我国未来煤炭领域的重要发展路线。在煤气化技术推广应用中,熔渣的流动行为严重影响气化炉的平稳运行时长,间接影响合成气的质量和炉壁的热量损失,有效求解流动参数的熔渣流动特性预测模型备受关注。本研究论述了现有的气化炉内熔渣流动特性的预测模型,并展望了预测模型的未来研究方向。综述当下,预测模型根据熔渣流动维数可分为一维预测模型和二维预测模型;一维稳态和非稳态预测模型均经历了构建和完善阶段;二维预测模型因无相关的数学公式描述和流动理念假设尚处于构建阶段;通过对液态熔渣的温度分布、附加应力的取舍,临界黏度的选取和熔渣黏度的处理方式等方面可以提高模型的计算精度。展望未来,一维预测模型的应用场景需更完善的规定,针对稳态和非稳态预测模型求解的参数需要更细致的辨析;二维预测模型的构建理论需更详细的突破,明确非稳态工况下熔渣在轴向和周向上流动的优先级;流动预测模型的计算精度需更全面的提升,熔渣性质的非恒定性、熔化的不均匀性、烟气流速的波动性等因素需要侧重考虑。

气流床气化炉中煤气化熔渣的结晶行为研究进展

煤气化是实现煤炭从燃料向原料转变,推进煤炭清洁高效利用的重要途径之一。气流床气化技术是目前的主流气化技术,气化炉的稳定运行要求液态熔渣应具有良好的流动性。排渣过程中的熔渣结晶行为会导致熔渣流动性变差,是造成气化炉非正常停车的主要原因。总结了影响熔渣流动性的主要结晶特征及研究结晶行为的关键——结晶动力学的研究现状。论述根据结晶行为判断结晶机制并选择合适的结晶动力学模型的方法。为获得更准确的结晶行为数据,总结多种结晶检测手段的原理和特点并分析了根据研究重点、仪器特性与熔渣特性选择合适结晶行为的检测手段。最后,论述了化学组成与操作条件对结晶行为的影响。研究发现不同晶体之间结晶机理差异明显,同一化学组成对不同晶体结晶行为的影响不同。当限定熔渣化学组成所处相区时,化学组成与操作条件对第一相结晶矿物质结晶行为的影响更具规律性,可为调控结晶行为提供更准确指导。研究结果与相图结合或建立简单易得的预测模型能更好指导熔渣结晶行为调控。目前,结晶行为研究主要依赖试验手段,后续研究可结合相场模拟与分子动力学模拟等方法,深入挖掘结晶机理,并考察气化炉内温度场、流场等因素对结晶特性的影响。

吹氩模式对钢包内多相流流动行为影响的数值模拟研究

以某钢厂150 t钢包为对象,通过数值模拟手段研究了吹氩模式和吹氩流量对钢包流场、钢渣界面行为和壁面剪应力分布的影响。结果表明:单孔吹氩模式下,钢包内环流远端流速低,钢渣界面流动不活跃,易导致此处渣层冷凝结壳;双孔等流量吹氩模式下,随着吹氩流量增大,钢渣界面流速增加,但其流动活跃性降低;双孔差流量吹氩下,大吹氩流量时钢渣界面能维持一定范围的活跃流动。当吹氩流量在120~240 L/min范围,单孔吹氩所形成的渣眼面积大于两种双孔吹氩模式;当吹氩流量超过240 L/min,双孔等流量吹氩下渣眼面积最大,双孔差流量吹氩对应的渣眼面积最小。另外,单孔吹氩下壁面剪应力最大,应力面积较小,双孔等流量吹氩下剪应力虽然显著降低,但分布区域面积增大。综上所述,双孔差流量吹氩模式可以在提高钢液精炼效率的同时,降低对钢包内衬耐火材料的流动侵蚀。

污泥气化渣骨料回填混凝土的制备与性能

采用污泥气化渣完全替代混凝土中的粗、细骨料,制备了回填混凝土,并在实验室和实际工程中进行了设计和应用.结果表明:由于其吸水特性,污泥气化渣骨料可在混凝土中起到内养护的作用,并优化混凝土界面过渡区,因此具备作为骨料用于回填混凝土的可行性;通过响应面法得到混凝土最优配合比,即砂率为60%,粗骨料中5~10 mm粒径占比为60%,预湿用水量为90%.

磨球钢B2可浇性差的成因分析与控制

针对河北某厂磨球用钢B2在浇注过程,偶发中间包塞棒上涨,可浇性差的现象,采用金相显微镜、扫描电镜及能谱仪对冶炼过程中各工序钢水内的显微夹杂物、大型夹杂物以及精炼渣进行了分析。结果表明,精炼造渣操作不稳定;RH冶炼过程及静吹结束后,夹杂物去除率分别为9.3%、8.1%、8.7%,中间包内显微夹杂物种类主要为Al_(2)O_(3)-MnS夹杂,钙铝酸盐夹杂,硅铝酸盐夹杂和MnS夹杂,来自RH出站时夹杂物的继承,还有少量SiO_(2)-CaO-MgO复合夹杂物,为卷渣产物;大型夹杂物含量分别为23.9 mg/10 kg、32.7 mg/10 kg、22.8 mg/10 kg,平均含量为26.5 mg/10 kg,高于国内同类钢种的先进水平5 mg/10 kg。大型夹杂物种类主要以Al_(2)O_(3)-SiO_(2)-CaO、Al_(2)O_(3)-SiO_(2)-CaO-MnO、Al_(2)O_(3)-SiO_(2)-CaO-MnO-MgO复合脱氧产物为主,约占夹杂物总量的90%以上,大小分布在50~300μm。其中部分脱氧夹杂物含有K、Na等元素,说明夹杂物主要为脱氧产物在上浮过程中粘附钢包渣、中间包渣,反映出钢包渣和中间包渣吸附夹杂物能力不足。明确了可浇性差的主要原因是精炼渣和中间包渣吸附夹杂物效果不理想,LF炉造渣不稳定,且中间包钢水流场易造成卷渣,生成了大型夹杂物。通过优化精炼渣和更换中间包渣,优化中间包钢水流场等措施,基本杜绝了钢水流动性问题,钢水质量得到了有效提高。

内蒙古某铜冶炼炉渣选矿厂流程确定、设计与生产实践

内蒙古赤峰某铜冶炼炉渣主要为侧吹-连续吹炼炉渣,缓冷后铜主要以硫化铜的形式存在,铁主要以磁铁矿和铁橄榄石的形式存在。为了确定选矿厂的流程、设备、产品指标等关键工艺技术及设备信息,通过对比粗碎—半自磨—球磨方案与三段一闭路破碎—球磨方案的优劣,最终确定了包含半自磨的碎磨工艺;通过参考类似选矿厂的实践和技术的先进性、稳定性、可操作性,确定了选矿厂全流程及设备规格型号和数量,并设计了产品指标。生产实践表明,铜冶炼炉渣选矿系统的铜精矿铜品位、回收率及尾矿品位等关键指标均优于设计值,实现了全面达产、达标。

气化熔渣对气流床气化炉操作影响的研究进展

气流床气化技术由于采用液态排渣的方式,煤灰熔渣的性质对气化炉的操作条件和性能具有显著影响。基于煤灰熔渣对气化炉衬里的影响机理分析,从煤灰熔渣的熔融特性和黏温特性的影响因素方面探讨了气流床气化技术对煤灰化学组成的要求及确定气流床气化炉操作窗口的方法和建议,为更好地设计和改进气流床气化技术,拓展煤种适应性提供理论指导。

易流型辅助胶凝材料的制备及其对混凝土性能的影响

基于四川地区的锂渣、钛矿渣、磷渣3种固体废弃物,开展固废基易流型混凝土掺合料的研究。通过与各种掺合料多元体系复配获得了性能优异的易流型掺合料,并系统研究了该辅助胶凝材料对混凝土工作性能、力学性能及耐久性能的影响。结果表明,磷渣粉、钛矿渣粉和石灰石粉复掺替代粉煤灰时,混凝土浆体的屈服应力有小幅下降,扩展度普遍大于550 mm,工作性能得到优化;改性锂渣粉、钛矿渣粉和石灰石粉复掺替代矿粉时,在锂渣粉掺量不高时,混凝土工作性能和力学性能较优,但锂渣粉掺量过大时会增大混凝土塑性黏度,掺量建议不超过胶凝材料的10%。

Status and development of the comprehensive utilization of the steel slag at Baosteel

The steel slag at Baosteel mainly comes from basic oxygen furnaces （BOF）, electric arc furnaces （EAF）, continuous casting and hot metal pretreatment. The output of the steel slag at Baosteel was 4.43 Mt in 2010. The steel slag was utilized both within the company and across the society, and the utilization rate within the company achieved was 16%. This study describes the current status and existing problems in those technologies of treating and using steel slag ,in the aspects of primary treatment, secondary treatment and advanced treatment, and it points out the development＇ s direction.

Numerical Analysis of Slag Carry-Over during Molten Steel Draining

Slag carry-over during the draining of molten steel from a teeming ladle is numerically studied here. Two-phase isothermal transient 3D Computational Fluid Dynamics simulations were employed to simulate the draining process. Two nozzle diameters, two nozzle positions and three slag heights were considered. From mass balances, the slag carry-over in terms of mass flow rate was obtained for each of the above variables. Besides, the draining times of the teeming ladle were estimated from theoretical considerations and CDF simulations, and compared.

Characterization of Size and Density Separated Fractions of a Bituminous Coal as a Feedstock for Entrained Slagging Gasification

Coal is one of the main sources of energy in many parts of the world and has one of the largest reserves/production ratios amongst all the non-renewable energy sources. Gasification of coal is one among the advanced technologies that has potential to be used in a carbon constrained economy. However, gasification availability at several commercial demonstrations had run into problems associated with fouling of syngas coolers due to unpredictable flyash formation and unburnt carbon losses. Computer models of gasifiers are emerging as a powerful tool to predict gasifier performance and reliability, without expensive testing. Most computer models used to simulate gasifiers tend to model coal as a homogenous entity based on bulk properties. However, coal is a heterogeneous material and comminution during feedstock preparation produces particle classes with different physical and chemical properties. It is crucial to characterize the heterogeneity of the feedstocks used by entrained flow gasifiers. To this end, a low ash US bituminous coal that could be used as a gasifier feedstock was segregated into density and size fractions to represent the major mineral matter distributions in the coal. Float and sink method and sieving were employed to partition the ground coal. The organic and inorganic content of all density fractions was characterized for particle size distribution, heating value, ultimate analysis, proximate analysis, mineral matter composition, ash composition, and petrographic components, while size fractions were characterized for heating value, ash composition, ultimate and proximate analysis. The proximate, ultimate and high heating value analysis showed that variation in these values is limited across the range of size fractions, while the heterogeneity is significant over the range of density fractions. With respect to inorganics, the mineral matter in the heavy density fractions contribute significantly to the ash yield in the coal while contributing very little to its heating value. The ash yield across the size fractions exhibits a bimodal distribution. The heterogeneity is also significant with respect to the base-to-acid ratio across the size and density fractions. The results indicate that the variations in organic and inorganic content over a range of density and size classes are significant, even in the low ash, vitrinite rich coal sample characterized here. Incorporating this information appropriately into particle population models used in gasifier simulations will significantly enhance their accuracy of performance predictions.

Application of the BSSF molten steel slag processing technology in POSCO

This study describes an overview of the POSCO＇ s Baosteel＇ s short-flow （BSSF） slag processing project, including process flow, process set-up, equipment composition, auxiliary facilities and relevant parameters, as well as a brief description of its application after commissioning.

矿渣型泥石流形成条件分析及主要物源特征研究:以栾川县康山金矿区为例

栾川县曾多次暴发山洪、泥石流灾害,矿渣型泥石流隐患发育十分典型,矿渣型泥石流与自然泥石流最大的差异在于物源不同。以栾川县康山金矿区为研究对象,通过对地形地貌、气象水文和泥石流物源进行调查研究,总结分析了区内矿渣型泥石流形成条件,泥石流主要物源来自废石弃渣(包括废石渣场和尾矿库),其次是残坡积物、以往泥石流堆积物和沟道内人造耕地。通过实地调查、室内试验和原位试验,对区内废石弃渣、尾矿砂、残坡积土等主要泥石流物源的宏观特征、颗粒级配、渗透特性进行研究,研究结果表明:废石渣场属于砾类土,其不均匀系数C_(u)=35.87,曲率系数C_(c)=1.5,具有明显的颗粒粒径分层规律,级配良好;研究区废石渣场d≥2 mm的颗粒平均含量为76.68%,属于狭义泥石流类型;废石渣场的渗透系数平均值为0.069600 cm/s,是自然泥石流渗透系数(0.021800 cm/s)的3.2倍,是残坡积土渗透系数(0.017320 cm/s)的4倍,是尾矿砂渗透系数(0.001869 cm/s)的37倍;不同泥石流物源的渗透系数与其粗颗粒含量呈正相关关系。

烧嘴偏转角度对气化炉渣层分布特性的影响

气化炉灰渣比(合成气携带走的飞灰与沉积至壁面的熔渣的质量比)是影响后续合成气净化设备寿命的关键因素,优化烧嘴偏转角度是控制气化炉灰渣比的有效方法。采用数值模拟方法,研究了HNCERI(Huaneng Clean Energy Research Institute)气化炉一段四烧嘴偏转角度对气化炉灰渣比、壁面渣层及耐火材料的影响。数值模拟结果表明,烧嘴偏转角度由0°增加至4.5°,灰渣比由2.0降低至0.8,液态渣层平均停留时间减少31.5%。偏转角度增加,渣口位置液/固态渣层厚度均增加;H=4.45~5.07 m位置固态渣层厚度下降,液态渣层厚度则增加。液态渣层流速与黏度呈负相关,与厚度呈正相关,液态渣层厚度主要受流速和颗粒沉积率影响。偏转角度增加,烧嘴平面上方耐火材料表面平均温度升高,烧嘴平面下方耐火材料表面平均温度降低,偏转角度为3.5°时耐火材料需要承受的最高温度取得最低值。在有效降低灰渣比前提下,为减少气化炉堵渣、渣层脱落和耐火材料烧蚀概率,HNCERI气化炉烧嘴偏转角度建议取3.5°。

煤气化渣高值化利用的研究进展及应用展望

我国能源资源禀赋和煤气化产业的发展使煤气化渣排放量已达6 000万t/a。大量的煤气化渣堆存不符合能源清洁低碳高效利用的理念。对煤气化渣进行消纳处理过程中,由于含水量高、含碳量高,限制了规模化利用途径,因此需转换传统思路,向高值化方向进行性能开发是一种趋势。重点综述了煤气化渣在高值化方面的研究进展,概述了煤气化渣的来源及物理化学性质,总结了国内外煤气化渣在催化剂框架、聚合物补强、多孔材料、农业堆肥等高值化方面的研究现状,提出了高值化利用存在的局限性问题,展望了未来的发展方向。煤气化渣高值化利用是固废性能开发的主要形式,可降低生产成本,减少环境污染,并且煤气化渣的特性显示煤气化渣是错位的资源,适度开发其在高值化方面的应用,可实现煤气化渣变废为宝。

顶吹浸没熔炼炉中气-渣-铜锍多相流搅拌特性的数值模拟

采用VOF方法对顶吹浸没熔池中氮气-渣-铜锍的流体动力学特性和搅拌特性进行数值研究。阐明气泡行为和流体速度之间的关系;研究气体入射速度和旋流对流体涡流结构、气体穿透深度和流体速度的影响。结果表明,气泡的形成和上升分别增加和降低流体速度。由于低温气体的注入,流体温度在高度0.43 m和0.52 m处分别呈现V形和W形分布。相比于58 m/s的气体注入速度,气速为98 m/s时气相的时均和最大穿透深度分别增加78.4%和31.9%。由于轴向速度分量的减小,旋流降低气体穿透深度、增加相间动量传递效率、抑制渣相喷溅。