高炉冷却壁非稳态传热研究

研究了铸钢、球墨铸铁和纯铜3种不同材质高炉冷却壁的非稳态传热过程。考察当高炉煤气温度分别为指数型和周期型变化时,冷却壁壁体温度场的变化情况。并根据不同材质冷却壁在非稳态工作过程中的表现,讨论这3种冷却壁的性能优劣。结果证明,铜质冷却壁是理想的长寿冷却壁,其性能明显优于铸钢和球墨铸铁冷却壁,并且这种优势在非稳态传热过程中表现的更为突出。同时铸钢冷却壁优于球墨铸铁冷却壁。     

差分算法在宝钢冷轧连退冷却控制中的应用

介绍了目前冷轧连退机组几种主要的冷却工艺、宝钢几条连续退火生产线目前所采用的冷却工艺设备、它们各自所采用的冷却控制模型技术、差分算法在冷却控制模型的建模原理和应用效果.通过实际过程控制趋势图表,展示了过程变量差分控制模型在非稳态生产控制过程中的强大调节能力和良好的控制精度.     

170mm×170mm连铸非稳态铸坯洁净度的研究

连铸过程中,中间包液位低于500 mm、浸入式水口出现裂纹、水口堵塞冲水口等非稳态浇铸情况下,生产出非稳态铸坯。采用气体检测、金相法、扫描电镜及高频水浸C扫描自动探伤等对非稳态铸坯进行研究,结果发现:非稳态连铸坯中大颗粒夹杂物含量较高,铸坯洁净度变差,不能用于正常生产。     

400 mm特厚板坯尾坯表面横裂纹的控制

板坯尾坯浇铸属于非稳态浇铸,随着板坯厚度的增加,尾坯表面横裂纹成为影响铸坯质量的主要因素。通过研究钢种的化学成分、二次冷却制度和尾坯浇铸时拉速的变化等因素对尾坯表面横裂纹的影响,确定了特厚板尾坯表面横裂纹的产生机理,提出了相应的改进措施。低碳微合金钢二次冷却制度采用弱冷,控制尾坯浇铸拉速小于0.5m/min的时间要小于5min,尾坯浇铸阶段二冷水的比水量从0.35 L/min减少到0.25 L/min,控制尾坯矫直温度在933℃以上,能够有效地减少尾坯表面横裂纹,使特厚板尾坯废品率降低到5%以下。     

连续退火炉中保护气氛及结构特性对带钢冷却特性的影响

采用标准kε-紊流模型,对连续退火炉中快冷段局部带钢的二维非稳态温度场进行CFD模拟,模拟与实际结果吻合较好。研究结果表明:从温度均匀性和冷却速度来看,当氢气体积分数为30%时,冷却效果最佳;控制最优的冷却速度可以通过控制带钢初始温度、带钢与风箱间距和冷却气体喷出速度、冷却介质的含量等参数来实现。     

矩形坯连铸机凝固末端位置的模拟计算

根据连铸矩形坯凝固传热特点，运用直接差分法建立了二维非稳态矩形坯凝固传热模型，对首钢矩形坯进行了凝固末端位置的模拟计算，得出了3种断面的液芯长度，找了搅拌器的合适位．置。     

节铬型铁素体不锈钢连铸板坯凝固过程热模拟

连铸板坯凝固传热主要在厚度方向进行,这造成了连铸坯大部分区域由侧面向中心凝固,因此可以近似地用非稳态定向凝固进行热模拟。利用自主研发的水平式连铸坯枝晶生长热模拟装置研究了新型节铬铁素体不锈钢连铸坯凝固组织,以期在工业生产前预测连铸工艺对其凝固组织的影响。热模拟试样热端温度采用连铸坯心部冷却曲线进行控制,并通过调节冷却水流量控制热模拟试样冷端的冷却强度,从而实现由冷端向热端的非稳态定向凝固。实验发现过热度和冷却强度对热模拟试样的等轴晶率及其平均晶粒尺寸影响不显著,但大的冷却强度会导致柱状晶长度增加。     

影响弧形小方坯结晶器温度场的因素分析

根据现场实际工艺条件，建立弧形小方坯结晶器二维非稳态传热的数学模型，采有限单元法求解温度场；并分析、讨论钢水含碳量、冷却水的流带和温度以及铜壁厚度对温度分布的影响。     

结晶器保护渣对超低碳钢连铸坯表面渗碳的影响

通过超低碳钢渗碳的理论解析和实验测定，研究连铸保护渣对超低碳钢铸坯表面渗碳的影响。在稳态浇注条件下，超低碳钢铸坯表面渗碳量和渗碳深度很小；在非稳态浇注时期，超低碳钢铸坯表面渗碳量和渗碳深度很大。保护渣中含石墨的连铸坯表面渗碳量和渗碳深度最大，碳黑次之，活性炭最小。     

高碳钢小方坯凝固过程的数值模拟

结合首钢三炼钢现场条件，利用传热学基本原理建立了小方坯凝固传热的二维非稳态数学模型．采用科学与工程计算语言MATLAB开发，通过现场测温验证了模型的准确性和实用性。该模型模拟了铸坯凝固的整个过程，发现过热度对铸坯的凝固终点以及表面温度的变化影响较小，而拉速、比水量影响较大，对小方坯凝固有了定性、定量的认识，从而寻求合适的工艺参数来控制铸机生产以提高铸坯的质量。     

热轧带钢加速冷却过程中温度计算的对称性冷却建模法

带钢冷却是一个多阶段的过程，各阶段间存在相互影响。热轧带钢在水冷却区冷却单元下的冷却是一种机理很复杂的非对称性冷却，难以用精确的数学模型进行描述。为此提出了对称性冷却假设条件下的建模方法，得到结构相对简单并适合过程控制的数学模型，并给出了在线控制的前馈算法，最后推导出可用集总参数法的最大带钢厚度值，简化了带钢厚度方向温度分布的在线控制。     

中厚板轧后冷却控制模型的研究

在研究中厚板轧后冷却工艺过程的基础上提出了一套适合现场使用的数学模型。对水冷模型这一关键控制环节给出了详细说明及程序流程图，并说明了已用于生产的模型算法及自适应方法。这为中厚板轧后冷却控制模型的研究提供了借鉴。     

Model Algorithm Research on Cooling Path Control of Hot-rolled Dual-phase Steel

With the development of advanced high strength steel,especially for dual-phase steel,the model algorithm for cooling control after hot rolling has to achieve the targeted coiling temperature control at the location of downcoiler whilst maintaining the cooling path control based on strip microstructure along the whole cooling section.A cooling path control algorithm was proposed for the laminar cooling process as a solution to practical difficulties associated with the realization of the thermal cycle during cooling process.The heat conduction equation coupled with the carbon diffusion equation with moving boundary was employed in order to simulate temperature change and phase transformation kinetics,making it possible to observe the temperature field and the phase fraction of the strip in real time.On this basis,an optimization method was utilized for valve settings to ensure the minimum deviations between the predicted and actual cooling path of the strip,taking into account the constraints of the cooling equipment′s specific capacity,cooling line length,etc.Results showed that the model algorithm was able to achieve the online cooling path control for dual-phase steel.     

中厚板中间冷却工艺的研究及应用

 中厚板生产过程中采用中间冷却（IC）工艺可以增加待温过程的冷却速率,提高轧制效率。采用有限元方法分析了中间坯待温过程的温度场变化,结果表明：通过中间冷却结合40～60s的空冷返红时间,冷却效果与完全空冷基本相同;通过热模拟试验的方法研究了中间冷却过程中的晶粒尺寸的变化规律,分析了中厚板冷却过程中晶粒长大的控制方法,将中间冷却工艺应用于国内某中板生产线,有效提高了生产效率,改善了表面质量并能降低合金成分的添加量。     

斯太尔摩冷却速度的智能控制

对所在单位斯太尔摩风冷线的风量控制系统进行改造,实现对不同轧制品种的自动识别,使冷却风机风门开口度的调节与辊道速度的变化具有快速反映能力及跟随性,从而实现了冷却速度的智能控制,达到了高附加值产品的控冷要求。这种方法可以在相关问题上得到广泛推广应用。     

Evolution of Control Models for Secondary Cooling in Continuous Casting Process of Steel

Secondary cooling control is an important factor in the continuous steel casting process. This paper reviews popular control models and analyzes their principles and characteristics. On the basis of the review, this paper proposes a new concept called “effective‐superheat” and a new control model called “synthetical model dynamic control method based on online temperature measurement.” The model, which combines the advantages of the popular models reviewed, not only allows steady, accurate and dynamic control of slab surface temperature, but also provides the temperature profile and the end of the liquid pool. In addition, this paper also discusses the current problems with secondary cooling control and the related development trends, which may be helpful for further development of secondary cooling control technology and informationization of the continuous casting process.     

Roll Subsectional Cooling Adaptive Fuzzy Control Based on Fuzzy Model Inversion

 Flatness is an important equality indicator of strip rolling and roll sub-sectional cooling is an important method for flatness control, especially for high order flatness component control. It is very hard to build the mathematic model of roll sub-sectional cooling because of its characteristics of nonlinearity, hysteresis quality and strong coupling etc. In order to improve the control effect of roll sub-sectional cooling control model, the roll sub-sectional cooling adaptive fuzzy control model based on fuzzy model inversion is built according to the separation principle of fuzzy form on the basis of the conventional fuzzy control model, where the parameters of the fuzzy controller can be dynamically regulated according to the change of rolling conditions. Simulation experiment results of the model indicate that the proposed roll sub-sectional cooling adaptive fuzzy control model based on fuzzy model inversion has high control precision and rapid response speed with strong self-learning and anti-interference capacity and a new method is provided for high-precision flatness control.     

Hot ductility trough elimination through single cycle of intense cooling and reheating for microalloyed steel casting

Surface transverse cracking, especially corner cracking, is prone to generate in continuously cast slabs of microalloyed steels. The method of surface structure control (SSC) was supposed to the best way to avoid the detrimental defects. However, the mechanism of improving hot ductility by SSC and the specific parameters to control the process are still unclear for the reasonable adoption in production. In the present work, the impact of cooling rate, holding temperature and holding time on austenite decomposition, and the austenite grain size before and after intense cooling were investigated by thermal simulation method. With the increase of cooling rate, it is observed that the phase is transformed from austenite?→?grain boundary film-like alltromorph ferrite?→?Widmanstätten ferrite plates (or intragranular ferrite plates)?→?bainite+martensite. Mostly important, the film-like ferrite can be eliminated through intense cooling and the following reheating, but the austenite grain size is not observed to be refined through the single γ?→?α?→?γ cycle. Even though, the reduction of area (RA) is improved drastically to over 70% in the third ductility trough, whereas the RA value is just 相似文献   

矿山地热防控与利用研究进展

从矿山地热致灾形式、热害控制技术、热能利用方法3个方面,对相关文献进行归纳,总结已有研究成果。结果表明,矿山地热的致灾形式有加剧煤岩体性质劣化、诱发支护结构失效和导致高温高湿环境三类,具体包括加剧围岩变形破坏、诱发吸附瓦斯溢出、降低锚杆锚固强度、加剧锚护材料腐蚀、损害工人身心健康、降低工人工作效率和增加机械设备故障率七方面。热害控制技术有非人工降温技术和人工降温技术两种,其中非人工降温技术分为热源控制技术、热湿环境调控技术和个体防护技术3类;根据制冷工质不同,可以将人工制冷降温系统分成气冷式、冰冷式和水冷式3大类,包括压缩空气制冷降温、冰制冷降温、地面集中制冷降温、地面排热井下集中降温、回风排热井下集中降温、地面热电联产制冷降温和热害资源化利用等制冷系统。通过提取矿井水和矿井回风中的余热用于矿区井口防冻、洗浴供暖和建筑物供暖,是目前矿山地热利用的主要方法。而直接提取巷道围岩热能的同时实现矿井降温是近年来的研究热点,也是矿山地热直接利用的关键;将地埋管换热器布置在采空区充填材料或巷道围岩内提取围岩热能、实现矿区多种清洁能源协同利用是未来矿山地热利用的发展方向之一。      

中厚板层流冷却过程控制系统在九钢的应用

以中冶京诚工程技术有限公司为江西九钢3 500 mm轧板厂开发的中厚板层流冷却过程控制系统为例,介绍了该过程控制系统的架构、冷却模型的组成、冷却策略、冷却规程计算方法和均匀性控制策略、系统界面以及实际应用效果。生产应用表明,该系统终冷温度控制精度达到±20℃,纵向温差小于30℃,各项指标达到了国外同类产品的水平,具有进...