最大值原理在连续加热炉优化控制中的应用

在钢坯加热过程数学模型的基础上，根据加热炉的生产特点，建立了燃料消耗最低的稳态加热模型。运用最大值原理对加热炉内最优供燃函数及温度场分布进行了数值模拟及优化计算，得出了合理的供热制度，从而实现最佳操作。     

连续加热炉待轧策略研究

建立了步进式加热炉数学模型,用方案比较法研究了待轧阶段5种不同炉温制度下的钢坯温度曲线;采用加热曲线法对待轧进行决策,模拟了待轧阶段和待轧后的全炉钢坯温度场.结果表明,用加热曲线法对加热炉待轧过程进行炉温决策,出炉钢温保持稳定,可取得很好的控制效果.     

加热炉内热滑块对钢坯黑印的影响研究

针对步进梁式加热炉,建立了钢坯和热滑块加热过程中耦合传热的数学模型,运用数值模拟的手段对加热炉内钢坯和热滑块的温度场进行仿真计算。结果表明,随热滑块高度的增加,钢坯黑印温差逐渐减小,热滑块最佳高度为80mm;钢坯和热滑块间存在接触热阻时,增加接触热阻对钢坯最终的黑印温差影响不大;随热滑块长度的增加,钢坯黑印温差呈指数形式增大。     

加热炉轧制反馈控制数学模型的研究

在详细分析了宝钢线材加热炉钢坯出炉后热过程特点的基础上,建立了钢坯出炉后热过程数学模型。在验证数学模型可信的基础上,针对实际生产情况进行了计算机数值模拟。最终建立了加热炉轧制反馈控制数学模型,实现了加热炉轧制反馈计算机在线控制。     

三维段法数学模型在加热炉上的应用

以能量平衡为基础,采用三维段法数学模型建立了炉气段、炉围段、钢坯表面段的能量平衡方程组。在典型工况时,以钢坯表面热流为耦合条件,采用主变量修正法求解了加热炉内炉气及炉围温度场,采用有限差分法求解了钢坯温度场。分析了钢坯表面黑度变化及炉气吸收系数变化对钢坯升温过程及排烟温度的影响规律。     

加热炉内一维、非稳态、变热流钢坯温度场的解析

基于合理的简化假设，建立加热炉内钢坯热传导数学模型，应用分离变量法和变分原理，推导一维、非稳态、变热流钢坯温度场的解析解；定量研究热流为线性分布、正弦分布时，钢坯温度场随加热时间的变化规律,并研究对应不同的傅里叶数,钢坯温度沿厚度方向的分布。结果表明，推导的解析解是正确和可行的，为加热炉在线控制中钢坯温度场的动态实时跟踪计算及总括热吸收率的参数辨识提供了一种理论依据。     

加热炉内一维、非稳态、变热流钢坯温度场的解析

基于合理的简化假设,建立加热炉内钢坯热传导数学模型,应用分离变量法和变分原理,推导一维、非稳态、变热流钢坯温度场的解析解;定量研究热流为线性分布、正弦分布时,钢坯温度场随加热时间的变化规律,并研究对应不同的傅里叶数,钢坯温度沿厚度方向的分布。结果表明,推导的解析解是正确和可行的,为加热炉在线控制中钢坯温度场的动态实时跟踪计算及总括热吸收率的参数辨识提供了一种理论依据。     

钢坯粗轧过程数学模型的应用

为了研究加热炉钢坯出炉温度和粗轧出口温度间的关系,建立了加热炉出口到粗轧机出口之间的数学模型,分析了钢坯在辊道空冷、除鳞、粗轧过程中的传热,获得了钢坯截面二维温度场,并利用现场实测数据对所建立的模型进行了对比分析。     

热轧步进式加热炉内钢坯温度场数值模拟

有用有限差分法，建立了热轧步进式加热炉内钢坯三维温度场的数值计算模型，结合攀钢热轧厂热炉的实际生产条件，对钢坯加热过程的温度场进行了数值模拟。通过现场拖偶实验准确确定了钢坯加热的边界条件，并验证了模型计算结果的准确性，在此基础上，通过模拟计算研究了加热工艺，待轧保温制造对钢坯温度场的影响，为优化轧制加热工艺提供科学依据。     

步进梁式加热炉水梁黑印数值模拟

以某钢厂一座步进梁式加热炉为例,建立钢坯和垫块温度场的数学模型.采用有限差分法模拟计算了不同条件下钢坯和垫块温度场及黑印温差随时间的变化;分析了垫块结构、坯料经过水梁错位点后的时间等因素对黑印温差的影响.模拟结果为确定在线模型估算黑印温差简化算法提供了依据.同时在严格控制黑印温差的基础上,减少钢坯的加热时间和氧化烧损,节能效果十分明显.     

The Influence of Oxide Scale on Heat Transfer during Reheating of Steel

The present work presents methodology and development of a mathematical model for prediction of the influence of oxide scale on heat transfer during reheating of steel in an industrial furnace. In this developed model, temperatures inside the steel billet were measured and with thermocouples at selected places and were collected by a water cooled computer that was traveling inside the slab. CFD is used to calculate the flow field inside of a furnace. The mass‐transfer coefficient of the scale formation is obtained by solving the convection mass‐diffusion equation across a boundary layer to the surface of a flat plate. A model for inverse heat conduction is employed to calculate the local surface temperature and heat flux on top of the growing oxide scale layer on a slab moving through a walking beam reheating furnace. By using the inverse method, the transient temperature and heat flux was firstly determined on the surface of the steel. During subsequent computations, the growth of the scale was calculated and the surface temperature of the oxide scale was extracted by using the Cauchy data from the previous calculations. The sensibility of the model on steel physical parameters is studied, and suitable parameters were obtained for heating a low carbon steel plate in the reheating furnace. Results show that the oxide scale layer should not be neglected in reheating models.     

连续加热炉在线控制系统的仿真研究

以总括热吸收率法为基础,对连续加热炉在线控制过程进行了软件仿真研究.研究内容主要包括控制算法和炉子模型两部分,控制算法研究考虑了DDC和SCC两级控制,炉子仿真模型为离线研究提供了完善的软件平台.模型以能量平衡为基础,综合考虑了炉气、钢坯、炉墙和热电偶之间的传热,实现了炉气黑度随炉气温度的动态补偿.以实际的连续加热炉为研究对象,采用加热曲线法较全面地研究了炉子一般动态和典型大幅度动态操作时的SCC决策,得出了适于在线应用的优化控制策略.     

Estimation of the Transient Surface Temperature,Heat Flux and Effective Heat Transfer Coefficient of a Slab in an Industrial Reheating Furnace by using an Inverse Method

In the steel industry it is of great importance to be able to control the surface temperature and heating or cooling rates during heat treatment processes. In this paper, a steel slab is heated up to 1300°C in an industrial reheating furnace and the temperature data are recorded during the reheating process. The transient local surface temperature, heat flux and effective heat transfer coefficient of the steel slab ares calculated using a model for inverse heat conduction. The calculated surface temperatures are compared with the temperatures achieved by using a model of the heating process with the help of the software STEELTEMP® 2D. The results obtained show very good agreement and suggest that the inverse method can be applied to similar high temperature applications with very good accuracy.     

电弧炉炼钢两种余热回收方式的比较

文章从已有的电弧炉炼钢的能量平衡关系出发，计算了利用废气余热预热废钢的节能率，并从能量数量、能量质量、综合效益等几个方面，对废钢预热和余热锅炉两种余热回收方式进行了比较，肯定了废钢预热技术的优越性。     

Mathematical model of metallurgical thermal processes and application

There are lots of physical changes and chemical reactions in the processes of iron and steel making, these processes are quite complex in the aspect of heat transfer.The processes of iron and steel making can be approximately divided into three kinds.The first kinds are the processes of fusion metallurgy which involve enormous chemical reactions,such as blast furnace,converter,electric furnace and coke oven.The second kinds are the processes of heating and cooling which are mainly the physical changes,such as walking-beam reheating furnace,annular heating furnace and car-type furnace.The third kinds are the processes of heat treatment which mainly adjust metallurgical structure of metal,such as roller hearth heat treatment furnace, strip continuous heat treatment vertical/horizontal furnace and HPH bell-type annealing furnace.Every process can only be finished in particular thermal equipment.And all the physical and chemical processes mentioned above must obey first principles of engineering thermodynamics,heat & mass transfer,hydromechanics, combustion,metallurgy physical chemistry etc,and which can be summarized as principle of heat transfer,mass transfer,momentum transfer and chemistry reaction.In this paper,based on first principle of heat and mass transfer in iron and steel making processes,a series of mathematical models of thermal equipments and processes are presented.Such as the model of hot-blast stoves,coke oven,CDQ-boiler system,sintering, reheating furnace,soaking furnace,annular heating furnace,roller hearth heat treatment furnace,strip continuous heat treatment vertical/horizontal furnace,HPH bell-type annealing furnace,control cooling of medium plate,burner,heat exchanger and regenerative burner etc.The on-line application of the model is based on experimental certification of the mathematical model.And finally the computer optimization system of metallurgical thermal process is obtained.     

A New Simplified Zonal Method for Furnace Thermal Radiation Calculation Based on Imaginary Planes

When solving the complex radiative heat transfer problems in reheating furnaces,there are a number of difficulties with the traditional zonal methods.To circumvent these difficulties,a new simplified method was proposed,which employed imaginary planes,referred to as the imaginary plane model.With the new model,crown wall reduction process was simplified.Therefore,every model zone could be treated as a closed square cavity.It could also solve the problem of radiative blocking in industrial furnaces more effectively.Besides,the new imaginary plane based model may lead to a problem that the denominator was zero.This problem was solved by transforming the expressions of reflex heat flux in the model.The model was capable of dealing with the systems that included black surfaces.The model was validated by considering the heat transfer in a reheating furnace where the temperature fields in the furnace chamber(including the steel,wall and gas)were obtained.A detailed comparison was made between the simulation and the black box experiment.The results show that the new model developed was valid and accurate.     

Heat Transfer and Energy Analysis of a Pusher Type Reheating Furnace Using Oxygen Enhanced Air for Combustion

 Oxy-fuel firing is more energy efficient and environmental friendly than conventional air-fuel firing and its application for reheating furnaces has begun since 90s. In this study, a computational methodology is presented to predict the steady heat transfer to the billets and temperature distribution in a continuous Pusher type reheating furnace which combustion air is enhanced by oxygen. The furnace is modeled as 2D radiating medium and Weighted Sum of Gray Gases model is used for absorption coefficient. The billets are moved in constant speed through zones of furnace. Radiative heat flux calculated from the radiative heat exchange within the furnace is modeled using the FVM considering the effects of furnace walls and billets. Energy consumption per ton of steel, production rate and thermal efficiency of furnace, and trend of NOx emission in various levels of oxygen enrichment is investigated by comparison with baseline furnace (21% O2 in air).     

基于可变容差法的步进梁式加热炉炉温设定优化

通过对钢坯在加热炉内的传热过程进行分析,建立钢坯的二维传热模型,并采用有限差分方法对钢坯温度场进行数值模拟。以钢坯出炉温度、出钢温差、加热过程中钢坯断面温差及表面温度等为约束条件,以能耗为目标函数,利用可变容差法求得加热炉各段的最优炉温设定值。运用该模型可方便地求得加热炉各段最优设定值,从而实现加热炉的最优工艺,提高加热炉效率,降低能源消耗,并提高产品质量。     

CSP辊底加热炉供煤气量随坯厚、坯温变化规律的模拟研究

研究了CSP辊底加热炉内的传热过程及其规律.采用数值模拟的方法,在进行合理简化后,建立总能量平衡基础上的炉内热过程数学模型,其中辐射传递方程的求解采用离散坐标法.自主开发了该炉型的通用热过程模拟软件,采集包钢CSP薄板坯连铸连轧厂的生产数据进行验证计算,计算所得钢坯温度与实际温度的相对误差小于1%,表明该模型假设合理,建模正确;该软件能够应用于该类型加热炉的设计、管理和研究等领域,为确定CSP生产线高拉速(提高入炉坯温)、多钢种的生产工艺参数创造了条件.