辊底式连续热处理炉钢坯二维传热过程数学模型的研究

以某公司拟建的辊底式连续热处理炉为研究对象,在详细分析其传热机理的基础上,针对其钢坯厚度变化较大的特点,建立了钢坯在炉内连续加热和摆动加热过程数学模型,采用数值计算方法对其进行了仿真计算,并利用设计大纲提供的数据间接验证了所建模型的正确可靠性。所开发的辊底式热处理炉计算机数值仿真系统可以动态模拟不同燃料、不同规格的钢坯在炉内的运行状况及其钢坯各典型点的温度变化规律;可以确定在不同的热处理工艺制度下、不同规格的钢坯所需要的最佳运行方式和最佳工艺制度。     

辊底式热处理炉加热模型的研究与应用

为确保钢板的加热质量,以明火加热的辊底式热处理炉为研究对象,建立了钢板加热过程数学模型,通过研究分析炉内传热机理,开发出辊底式热处理炉加热模型控制系统。此加热模型控制系统投运后,先后通过埋偶实验及生产实践检验,其结果表明模型计算精度较高,在线控制系统运行稳定,满足生产的需求。     

中厚板无氧化低温辊底式热处理炉的脉冲控制策略

针对国内某钢铁企业新建中厚板无氧化辊底式热处理炉工程,对辐射管加热系统在低温下的脉冲控制策略进行组合、优化,使无氧化热处理炉在低温下获得了很好的温度均匀性,扩大了该热处理炉产品种类范围,取得很好的效果.     

直流电弧炉水冷钢棒式底电极传热过程的数值仿真

采用文献[1]建立的“直流电弧炉水冷钢棒式底电极传热过程二维数学模型”,在验证模型正确可信的基础上,对直流电弧炉底电极的传热过程进行了数值仿真计算,所得结论对直流电弧炉的生产有重要的指导意义。     

环形炉内辐射传热的新的物理-数学模型

建立了加热圆钢坯或方钢坯的环形转底炉的物理一数学辐射传热数学模型。计算的复杂性在于各点气体和固体之间的相互辐射、温度的不均匀和角度系数的难以确定。列出辐射能量守恒方程，然后进行求解，并认为所采取的求解方法有一系列优点，精度高，速度快。举例进行实算，列出了计算结果。该模型可以用来对各种形状钢坯在环形加热炉中加热时，计算加热时间和加热质量（热流分布）。     

高速烟气环流技术在辊底式热处理炉上的应用

高速烟气环流技术是指采用燃烧器产生的高速烟气流围绕被加热板坯循环,从而实现快速均匀加热的效果.在数值模拟的基础上,将该技术首次应用于辊底式热处理炉,生产数据实践表明该方案具备良好的节能效果,同时热处理温度均匀性优异.     

步进式加热炉内钢坯水冷黑印的模拟研究

采用全隐式有限差分法,建立了步进式加热炉内钢坯温度场的数值计算模型,编制了钢坯加热过程的模拟软件。分别对不同工况下的钢坯加热过程进行模拟计算,得到了滑轨结构、滑轨高度和滑轨质材等对钢坯出炉温度分布和黑印温差的影响。为消除黑印,提高钢坯加热质量提供了科学依据。     

基于步进式加热炉数学模型的氧化烧损预测模拟

针对钢铁企业的氧化烧损问题,用数值模拟的方法进行预测分析。利用CFD流体计算软件建立了炉内流动、燃烧、辐射、钢坯导热和氧化烧损模型,流动模型采用k—ε湍流模型,燃烧采用PDF燃烧模型,辐射换热模型采用离散坐标（DO）辐射模型,热流密度做为钢坯导热的边界条件,模拟钢坯在实际工况下的结果表明,氧化铁皮的快速增长期是在钢坯入炉50～120min之间,位于加热段;在不同均热时间下,钢坯氧化率随均热时间呈线性增长。据此结论,现场操作人员可通过强化加热段加热能力的手段减少钢坯在加热段的停留时间或热装钢坯调整总的在炉时间来降低钢坯氧化烧损率以提高钢坯加热质量。     

钢锭系统热送热装热过程数学模型的研究

在全面系统分析了某公司钢锭热送热装系统热过程传热机理的基础上,建立了钢锭冷却、加热过程二维传热数学模型。并采用交替隐式TDMA法对所建立的数学模型进行了数值求解。利用现场的实测数据对所建立的数学模型进行了对比分析计算,模型计算值和实测值的最大相对误差仅为2．46％,完全满足工程应用的要求,证明所建模型是正确可信的,可以作为计算机在线控制的理论基础。     

薄板坯连铸连轧CSP工艺缓冲性能的研究--直通式辊底炉传热模型及其数值分析

CSP工艺是薄板坯连铸连轧的主要生产工艺之一,直通式辊底炉在CSP工艺中起到加热、均热薄板坯和缓冲作用,是十分重要的热工设备.建立了描述直通式辊底炉炉内换热的长炉模型,应用预解区域法解算其辐射换热,提出了新的"显式"迭代法,对直通式辊底炉的设计和操作参数的影响进行了数值分析.     

Novel Approach to Estimate the Optimum Zone Fuel Mass Flow Rates for a Walking Beam Type Reheating Furnace

Three-dimensional numerical simulation is performed to predict the heat transfer performance in a walking-beam reheating furnace. The furnace uses a mixture of coke oven gas as a heat source to reheat the slabs. The fuel is injected into the furnace at four zones: preheating zone, first heating zone, second heating zone, and soaking zone. This numerical model considers turbulent reactive flow coupled with radiative heat transfer in the furnace; meanwhile, the conductive heat transfer dominates the energy balance inside the slabs. An initial iterative method is proposed to estimate the fuel mass flow rate at each zone of the reheating furnace, while the required heating curve of the slabs is specified. In addition, a simplified two-dimensional numerical model is performed to estimate the fuel mass flow rate for the consideration of computational time consummation. The results of the two-dimensional numerical simulations are compared with those of three-dimensional numerical simulation and the in situ data. Furthermore, velocity and temperature distributions are examined for two cases under different heating curves of the slabs.     

Efficiency analysis of radiative slab heating in a walking-beam-type reheating furnace

The thermal efficiency of a reheating furnace was predicted by considering radiative heat transfer to the slabs and the furnace wall. The entire furnace was divided into fourteen sub-zones, and each sub-zone was assumed to be homogeneous in temperature distribution with one medium temperature and wall temperature, which were computed on the basis of the overall heat balance for all of the sub-zones. The thermal energy inflow, thermal energy outflow, heat generation by fuel combustion, heat loss by the skid system, and heat loss by radiation through the boundary of each sub-zone were considered to give the two temperatures of each sub-zone. The radiative heat transfer was solved by the FVM radiation method, and a blocked-off procedure was applied to the treatment of the slabs. The temperature field of a slab was calculated by solving the transient heat conduction equation with the boundary condition of impinging radiation heat flux from the hot combustion gas and furnace wall. Additionally, the slab heating characteristics and thermal behavior of the furnace were analyzed for various fuel feed conditions.     

Investigation of the slab heating characteristics in a reheating furnace with the formation and growth of scale on the slab surface

In this work, the development of a mathematical heat transfer model for a walking-beam type reheating furnace is described and preliminary model predictions are presented. The model can predict the heat flux distribution within the furnace and the temperature distribution in the slab throughout the reheating furnace process by considering the heat exchange between the slab and its surroundings, including the radiant heat transfer among the slabs, the skids, the hot combustion gases and the furnace wall as well as the gas convection heat transfer in the furnace. In addition, present model is designed to be able to predict the formation and growth of the scale layer on the slab in order to investigate its effect on the slab heating. A comparison is made between the predictions of the present model and the data from an in situ measurement in the furnace, and a reasonable agreement is found. The results of the present simulation show that the effect of the scale layer on the slab heating is considerable.     

Online simulation model of the slab-reheating process in a pusher-type furnace

This paper presents an online simulation model of the slab-reheating process in a pusher-type furnace in Acroni d.o.o. in Slovenia. The simulation model is connected to the information system of a hot-processing plant that provides online measuring and charging data of the furnace. The simulation model considers the exact geometry of the furnace enclosure, including the geometry of the slabs inside the furnace. A view-factor matrix of the furnace enclosure was determined using the Monte Carlo method. The heat exchange between the furnace gas, the furnace wall and the slab’s surface is calculated using a three-temperature model. The heat conduction in the slabs is calculated using the 3D finite-difference method. The model was validated using measurements from trailing thermocouples positioned in the test slabs during the reheating process in the furnace.A graphical user interface (GUI) was developed to ensure a user-friendly presentation of the simulation-model results.     

圆形铝熔炼炉内非稳态热工过程数值模拟

针对铝熔铸过程中常用的圆形铝熔炼炉,利用FLUENT软件,根据能量守恒方程、动量方程建立铝熔炼炉内热工过程数学模型,采用标准k-ε湍流模型、P-1辐射模型对铝熔炼炉内非稳态传热及流动过程进行数值模拟研究。考虑到铝料熔化过程会消耗一部分能量,采用等效比热法将铝料的熔化潜热转换为相应的比热值进行计算。通过数值模拟得到了炉内流场、炉膛及铝料温度场分布情况。模拟结果与实际情况相符,为铝熔炼炉的设计与优化研究提供了理论依据。     

步进式加热炉内热工过程的数值模拟

建立步进式加热炉内流动、燃烧和传热的数学模型.炉内流场的模拟采用κ-ε双方程模型,辐射换热计算采用P-1辐射模型,气相燃烧采用Species Transport模型,流场计算采用Simpler算法.采用上述模型与算法得到了炉内详细合理的温度、速度和浓度分布,并对其中影响板坯加热的温度场进行了试验验证.     

Study of ice and snow melting process on conductive asphalt solar collector

This paper investigates the snow melting process on asphalt pavements as solar collector by experiments and numerical simulation. A numerical simulation method was used to predict the general design requirements for snow melting system of asphalt pavements, and a type of experimental asphalt snow melting system has been built using the design parameters obtained from the preceding simulation. Graphite powders were used to improve the thermal conductivity of asphalt concrete and thus resulting in an improved efficiency of asphalt collector. A laboratory snow melting test was performed after real snowstorm events. The effects of thermal conductive asphalt concrete (CAC) on snow melting performance and asphalt pavement temperature distribution were evaluated. The heat transfer in the asphalt slabs and the heat requirement for the snow melting were analyzed. The results that are obtained show that asphalt solar collector (ASC) provides us a better alternative method for snow melting. The higher fluid temperature is a positive way to improve the performance of snow melting system. However, it is unnecessary to keep a too high fluid temperature so as to reduce the waste of energy. The non-uniform temperatures in the asphalt slabs are noticeable. Furthermore, the heat-transmission and the snow melting performance can be enhanced using CAC.     

中频无芯感应熔炼炉熔化过程温度特性的数值模拟

进行感应炉熔炼中传热过程的简化，建立数学模型，用数值方法计算出炉内金属炉料在各时刻的温度分布以及在熔化发生时的温度分布和相界面的移动特性。讨论了感应炉的感应加热作为传热方程的内热源以及感应电流的集肤效应对数值计算的影响。结果表明，正是由于集肤效应的存在，才使得钢料首先从炉内表面处发生熔化直至炉圆柱中心。     

THREE-DIMENSIONAL ANALYSIS OF THE WALKING-BEAM-TYPE SLAB REHEATING FURNACE IN HOT STRIP MILLS

Three-dimensional analysis is performed for the turbulent reactive flow and radiative heat transfer in the walking-beam-type slab reheating furnace by FLUENT. A simplified burner is validated against the results of the actual burner with the detailed grid resolution to avoid an excessive number of grids. The predicted temperature distribution in the furnace and global energy flow fractions are in reasonable agreement with available data. Distribution of the heat flux to the slabs, velocity vectors, and all major scalar variables in the furnace also are predicted. This study shows that three-dimensional analysis may be a useful tool to understand quantitatively the complicated combustion and heat transfer characteristics in the furnace.     

炉内辐射换热过程的有限体积法

简要分析了含吸收散射性介质的三维空腔内辐射传递方程的有限体积法求解过程,应用该方法对四角切圆炉膛内的辐射换热过程进行模拟计算,得出了炉膛内温度分布,并将计算结果与实测值进行了比较。通过数值计算表明：有限体积法计算速度快,对不规则边界适应性强,具有很高的工程可用性。