【作者】 万飞；

【导师】 王勇勤；

【作者基本信息】 重庆大学 ， 机械工程， 2011， 博士

【摘要】 随着现代科学技术的进步,对高质量冷轧带钢的需求量日益增加,对后续深加工处理也提出了更高的要求。带钢连续热处理机组正是把冷轧带钢的脱脂、退火热处理和平整三个工序连结为整体而发展起来的新型设备,提高了处理带钢的速度和质量。立式连续带钢热处理炉是该机组中的关键工艺设备。要获得高质量的带钢机械性能,热处理过程中对带钢的温度控制是关键技术之一。在立式连续热处理炉中,影响带钢温度的因素很多,包括:炉内设备结构参数(喷射集管与带钢的距离、喷射集管的排列方式、喷孔直径、辐射管直径和排列形式、辐射管与带钢的距离等)、带钢参数(材质、厚度和宽度)和工艺参数(带钢速度、混合气喷射温度和速度、辐射管开启数量等)。各种参数相互影响,错综复杂,共同影响带钢的加热和冷却温度。在国外提供的带钢温度生产控制模型中,只包括带钢参数和工艺参数中的带钢速度和辐射管开启数量,而没有包括设备结构参数和混合气喷射温度和速度等参数。因而,在深入分析带钢的热处理机理时,存在着两个问题:只能简单地使用国外的带钢温度生产控制模型,而不了解模型的来源;缺乏对带钢温度变化机理的理论研究数学模型。要达到自主集成连续热处理炉的目的,必须要对带钢热处理过程进行系统科学地研究,建立完整的理论计算数学模型,再由其得到带钢温度生产控制模型。理论数学模型中应包括所有的设备结构参数、带钢参数和工艺参数。在所查文献中,未查到对于包括设备参数在内的研究内容。为此,本文经过系统科学地深入分析,创新性地提出了包括设备结构参数、带钢参数和各种工艺参数的理论研究数学模型,并由理论数学模型推导得到带钢温度生产控制模型。本文针对热处理炉中的预热、辐射加热和快冷三个具有典型代表意义的炉段,进行科学地理论研究。研究的主要内容分为:带钢的传导传热分析、常规强制对流换热带钢温度数学模型研究、建立预热段冲击射流换热带钢温度数学模型、建立快冷段冲击射流换热带钢温度数学模型、加热段辐射换热带钢温度数学模型五个部分。主要研究内容及成果如下:①带钢的传导传热分析分析了炉内预热段、辐射加热段和快冷段的设备结构和换热系统的特点,根据带钢较薄的几何特征及内部传导传热规律,利用牛顿冷却定律,得到了带钢瞬时温度、边界温度、炉内温度和换热系数之间的关系。②常规强制对流换热带钢温度计算数学模型研究根据常规强制对流换热,运动气体外掠平壁的基本原理,分析了带钢运动使气体外掠带钢壁面的特点。按照带钢的运行方式和炉内上下炉辊的位置,分析了混合气体在带钢表面边界层形成的紊流状态。推导了带钢瞬时对流换热系数和带钢瞬时温度理论计算数学模型,进而得到带钢在指定计算段中的平均换热系数和带钢温度数学模型。将带钢的计算温度与生产实测带钢温度数据比较,误差小于5%。③建立预热段冲击射流换热带钢温度理论计算数学模型根据实际生产中预热段的炉内设备结构(气体喷射集管与带钢的位置、集管的排列、喷孔直径等)、带钢参数(材质、厚度和宽度)、工艺参数(带钢速度、喷气速度、炉内温度等),应用高温气体冲击射流换热机理,分析了气体和带钢在预热段中的对流换热。应用数值模拟方法,以计算冲击射流换热系数为目标,建立了带有未知系数和幂指数形式的努塞尔数与普朗特数和雷诺数的关系模型。代入多组生产实测炉内温度和带钢温度数据,得到预热段冲击射流加热带钢瞬时努塞尔数、换热系数、带钢边界温度数学模型,最终获得了基于冲击射流理论的带钢瞬时温度和平均温度理论计算数学模型。由该数学模型得到带钢温度生产控制模型,已用于生产中,计算结果与生产数据比较接近。④建立快冷段冲击射流换热带钢温度理论计算数学模型应用冲击射流方式冷却带钢的换热机理,研究了在不同氢含量的混合气体冷却带钢条件下,冷却系统与带钢在快冷段中的对流换热。根据快冷段冷却带钢的炉内换热系统设备、带钢参数和各工艺参数的特点,预设带有未知系数和幂指数的努塞尔数与普朗特数和雷诺数的关系模型。用数值模拟方法,建立了快冷段瞬时换热系数、带钢瞬时边界温度数学模型,进而得到了基于冲击射流对流换热理论的冷却带钢瞬时温度和平均温度理论计算数学模型,并建立了生产控制模型,生产实测数据与用理论数学模型的计算结果比较符合。⑤建立加热段辐射换热带钢温度理论计算数学模型根据辐射换热的基本原理和传热特性,分析了辐射段设备结构(辐射管与带钢的相互位置、辐射管直径、辐射管配列密度等)、带钢参数(材质、厚度与宽度)、工艺参数(带钢速度、辐射管组开启数量、炉内温度等),应用牛顿冷却定律、辐射换热系统与带钢之间的热流量转换、带钢的传导传热三者之间的关系,推导了瞬时辐射热流量、辐射换热系数、带钢边界温度计算数学模型,并推导得到基于系统辐射换热理论的带钢瞬时温度和带钢平均温度理论计算数学模型。由该模型推导得到生产控制模型,将生产控制模型用于生产中,生产实测数据与用理论数学模型的计算结果符合度较高。本文研究的新型多参数热处理炉预热段、辐射加热段和快冷段带钢温度理论计算数学模型和生产控制模型及其研究方法和研究成果,解决了连续热处理系统中带钢温度变化的理论研究问题,为研究带钢连续热处理工艺、自主集成热处理炉和实际生产提供了重要的参考和理论依据,是立式连续热处理炉中预热、辐射加热和快冷三个区段中带钢温度理论研究的创新性探索,对连续热处理炉的科学集成和生产控制将产生重要的推动作用。更多还原

【Abstract】 With the development and advancement of science and technologies, the requirement progressively increases for higher qualities and better processing of cold strip. A continue heat treatment production line is a new type of heat treatment equipment developed for increasing speed and improving the quality of the strip, which combining cleaning function, annealing heat treatment, and skin pass for strip into a associated production line. Vertical Continue Annealing Furnace (VCAF) is the key process equipment in the line.The key technology is for controlling temperature of strip in heat treatment process if better mechanical characters of strip are obtained. There are many affecting parameters in VCAF. These parameters include in equipment configurations (the distance between jet pipes and strip, the arranging method for jet pipes, the diameter of jet holes, the diameter and arranging method of radiation tubes, the distance between radiation tubes and strip, etc), the strip parameters (thickness and width), and process parameters (the speed of strip, the temperature and speed of gas, the opening number of radiation tubes, etc). The parameters are affected each other, and they affect temperature of strip all together. The model of temperature of strip for production control from foreign company only consists of the strip parameters, strip speed and opening number of radiation tubes, not equipments parameters, temperature and speed of gas. Therefore, there are two problems for analyzing annealing furnace: the model from foreign company is difficult to be understood principle but used; the model of strip temperature for theory research is deficient. We must found the theory research models for attaining ability self-determination theory analyzing and a production control model from the theory research model. The theory research model should include in all equipments configuration parameters, strip parameters, and process parameters. The theory research model is not found in reference papers. The thesis perfectly analyses the characters of heat transfer system in VCAF and brings forward in innovation a set of new theory research model including in equipment, strip and process parameters. The control models for strip temperature for production are obtained from the theory research models.The main contents of the thesis consist of 5 contents: analysis on conduction heat transfer of strip, analysis on normal forced convection heat transfer, proposing the calculating temperature models of strip on jet impinging convection heat transfer in Jet Preheat Furnace (JPF) and Rapid Cooling Section (RCS), and building calculating temperature models of strip on radiation heat transfer in Radiation Tube Furnace (RTF). Main contents of the study are summarized as follows:①Analysis on conduction heat transfer of stripThe relation is founded on strip instantaneous temperature, boundary temperature of strip, inner temperature in furnace, heat transfer coefficient and the Newton’s cooling law according to equipment configuration, conduction characters of strip, and characteristics of transfer system of JPF, RTF and RCS,②Study for calculating temperature models of the strip on normal forced convection heat transferThe characteristics of the moving strip are analyzed according to the basic principle on a fluid flowing over a stationary surface. The boundary layer on the strip surface can be considered as turbulent flow according to the relation between the strip and the rollers in furnace. The calculating models are built by using the differential coefficient method for instantaneous heat transfer coefficient and instantaneous temperature of the strip. Then, they can be integrated to gain models for calculating the average heat transfer coefficient and strip temperature. The data errors are less than 5% by comparisons between the calculation data and production data.③Proposing calculating temperature models of the strip on jet impinging convection heat transfer in JPFThe convection heat transfer between strip and heat transfer system is analyzed in JPF using the jet impinging heat transfer principles according to equipment configuration parameters (the distance between jet pipes and strip, the arranging method for jet pipes, the diameter of jet holes, etc), the strip parameters (thickness and width), and process parameters (the speed of strip, the temperature and speed of gas, etc). The jet impinging convection heat transfer is analyzed between strip and heat transfer system. The relation model among Nusselt number, Prandt number and Reynolds number is proposed with coefficients and powers. The theory research models of instantaneous and average strip temperature are proposed. The model for production controlling temperature of strip is proposed from theory research model. The calculating data are basically accordance with production data.④Proposing calculating temperature models of the strip on jet impinging convection heat transfer in RCS The convection heat transfer between strip and heat transfer system is analyzed in RCS using the jet impinging heat transfer principles according to equipment configuration, the strip parameters, and process parameters. The jet impinging convection heat transfer is analyzed between strip and heat transfer system. Using the numerical value simulation method, the relation model among Nusselt number, Prandt number and Reynolds number is proposed with coefficients and powers. The theory models of instantaneous and average strip temperature are proposed. The model for production controlling strip temperature is proposed from theory model. The calculating data are basically accordance with production data.⑤Proposing calculating temperature models of the strip on radiation heat transfer in RTFBased on the fundamental radiation heat transfer principles, the models of radiating heat transfer rate are proposed for description of the relation between strip and system by analyzing relation among equipment configuration parameters (the diameter and arranging method of radiation tubes, the distance between radiation and strip, etc), strip (thickness and width) and process parameters (the speed of strip, the diameter, arranging method and the opening number of radiation tubes, etc). The calculating models are proposed for instantaneous radiation heat transfer rate, radiation heat transfer coefficient, and boundary temperature of strip applyed the Newton’s cooling law, heat transfer between strip and system, and conduction heat transfer. The theory research models of instantaneous and average strip temperature are proposed. The production controlling model of strip temperature is proposed from theory model. The calculating data are basically accordance with production data.The theory research model and production control models, research methods and results in the thesis can be used in theory analyzing the annealing furnace and production controlling for strip temperature. The models can offer important reference and theory foundation for researching heat treatment process. It is a new exploration on theoretical innovation on calculating strip temperature for 3 furnace sections of JPF, RTF and RCS in VCAF. The models and theories can become important action for theory analyzing continue annealing furnace and production control.更多还原