Designing for Long Campaign Life Blast Furnace (1)──The Mathematical Model of Temperature Field for Blast Furnace Lining and Cooling Apparatus and New Concept of Long Campaignship Blast Furnace Cooler Design

The physical and mathematical model of temperature field for blast furnace stave coolers was established. The computation results show that the heat resistance of 2-6 mm water scale within the cooling pipe is about 7%-20% of the total heat resistance of cooling stave body, as for drilling duct type, the heat resistance of 2-6 mm water scale is about 88%-98% of the total heat resistance. Using drilling duct or full cast pipe can eliminate gas clearance and coating layer between pipes and cast iron body and reduce the heat resistance of the cooler sharply and improve the coefficient of heat transfer to a great extent. The water velocity within coolers can be kept at the 1evel of 0.5- 1 .5 m/s, the higher water velocity can not decrease the hot surface temperature, but can increase energy consumption for cooling water.

Mathematical Modeling of Peat Self-ignition at Ambient Temperature Oscillations

In the classical formulation, the problem of thermal explosion in a finite volume of the reacting material in the presence of harmonic oscillations of the ambient temperature has been solved. It is shown that in the oscillation periods, commensurate with the adiabatic induction period of thermal explosion, implement a kind of resonance which corresponding with average ambient temperature. At both high and very low frequencies oscillations at ambient temperature, their influence on the critical condition and on the induction period of thermal explosion is negligible. However, at low-frequencies influence of ambient temperature oscillations, even a relatively low amplitude, on critical condition and especially on induction period of thermal explosion, can be very strong.

Numerical modeling of multiphase flow,heat transfer and titanium flow behavior in blast furnace hearth

Understanding the complex phenomena in BF hearth is essential to increase furnace productivity and to extend furnace campaign.We have developed several continuum-based mathematical/numerical models to simulate the multi-phase flow,heat transfer and chemical reactions in the BF hearth.These models have generated an improved insight on the mechanisms for liquid drainage efficiency,lining erosion and wall protection in BF hearth under operational conditions.The current paper gives an overview of these studies in three aspects:Gas flow and pressure on the liquid surface,and their effect on the drainage characteristics;The flow and temperature distributions of liquid iron in BF hearth,and the temperature distribution in the refractories;Finally,titanium behaviors due to titania injection to form Ti(C,N) -rich scaffold on the hearth surface,to protect the hearth from erosion.

Influence of furnace temperature and non-uniform heat flux density on direct reduction process of newly designed carbon containing pellet

In this study,innovative ellipsoid pellet with craters on its surface was designed,and the direct reduction process was compared with ellipsoid(without craters)and sphere pellets.In addition,furnace temperature and uneven heat flux density effects on the pellet direct reduction process were also studied.The results show that ellipsoid pellet is better than that of spherical pellet on metallization ratio.However,under the condition of non-uniform heat flow,the ellipsoid pellet final metallization rate and zinc removal rate were lower.Although the heat transfer effect of ellipsoid pellet with craters was not improved significantly,the metallization rate and zinc removal rate were found improved,which will have a cumulative effect on the pellets direct reduction process in rotary hearth furnace.Under varying furnace temperature conditions,the pellet temperature was higher than that of the constant furnace temperature.After 1200 s,pellet Fe concentration increased to 123.6%,metallization rate and zinc removal rate increased to 113.7%and 102.2%,respectively.These results can provide references for the carbon-containing pellet design used in rotary hearth furnace.

Mathematical Modeling of Heat Flux Distribution in Raw Cotton Stored in Bunt

The scientific article examines the physical and mechanical properties of raw cotton stored in buntings in cotton palaces. Because during the storage of raw cotton in bunts, some of its properties deteriorate, some improvements. Therefore, the mathematical modeling of storage conditions of raw cotton in bunts and the physical and mechanical conditions that occur in it is of great importance. In the developed mathematical model, the main factor influencing the physical and mechanical properties of raw cotton is the change in temperature. Due to the temperature, kinetic and biological processes accumulated in the raw cotton in Bunt, it can spread over a large surface, first in a small-local state, over time with a nonlinear law. As a result, small changes in temperature lead to a qualitative change in physical properties. In determining the law of temperature distribution in the raw cotton in Bunt, Laplace’s differential equation of heat transfer was used. The differential equation of heat transfer in Laplace’s law was replaced by a system of ordinary differential equations by approximation. Conditions are solved in MAPLE-17 program by numerical method. As a result, graphs of temperature changes over time in raw cotton were obtained. In addition, the table shows the changes in density, pressure and mass of cotton, the height of the bun. As the density of the cotton raw material increases from the top layer of the bunt to the bottom layer, an increase in the temperature in it has been observed. This leads to overheating of the bottom layer of cotton and is the main reason for the deterioration of the quality of raw materials.

基于热量平衡模型的大曲发酵升温机理研究

中国白酒产业正面临产业转型升级,包括制曲在内的关键工艺采用基于经验式的直接改造,关键工程学机理的缺乏导致无法进行理性设计。该研究从大曲升温机理角度,对曲房固态发酵热量的产生与流动进行了定量分析,跟踪记录大曲发酵过程参数,简化大曲发酵过程生化反应,构建大曲热量平衡模型。通过模型计算,整个曲房发酵过程产生的热量,经水分蒸发途径散热占比54.22%,墙壁和微弱气体流动散热占比42.00%,由室内空气升温引起的热量变化可以忽略,剩余3.77%为累积热量部分,其与大曲升温呈正相关(R^(2)=0.85)。经验证,大曲温度变化模型的平均误差为5.05%,R^(2)=0.94。基于模型探讨了调控水分参数对大曲温度产生的影响,表明了水分控制对于调控大曲温度的重要性。初步探讨从数学建模的角度为未来大曲生产的调控与优化的可行性,研究结果可为智能曲房的构建提供理论支撑。

基于热阻调控方法的低温光学系统二级温区传热特性分析

为了实现低温光学系统二级温区的精准控温,同时不引入额外的热负载,提出了一种热阻调控方法,建立了应用于该方法的一维数学模型,运用该数学模型研究了不同真空腔温度条件下不同热阻参数(不同材料参数和几何参数)对二级温区达到热平衡后温度水平和漏热量的影响,同时将该方法和传统的电加热调控方法进行了比较。研究结果表明:当真空腔温度为定值时,随着热阻的增大,二级温区温度升高,漏热量减小;当热阻为定值时,随着真空腔温度的升高,二级温区温度升高,漏热量增大。在文中的研究工况下,当真空腔温度为253.15 K时,二级温区温度水平调节范围为111.1~185.2 K,相应的漏热量从1.75 W减小至1.10 W;当真空腔温度为293.15 K时,温度水平调节范围为120.9~219.4 K,相应的漏热量从2.58 W减小至1.57 W。电加热调控方法使二级温区热负载达到了16.8 W,是热阻调控方法的11倍左右(真空腔温度为293.15 K,二级温区目标温度为220 K左右),随着二级温区温度的升高,电加热调控方法使得系统热负载增大,热阻调控方法与之相反。热阻调控方法使低温光学系统热负载一直处于较低的水平,同时可减少系统对电功率和散热资源的需求。研究结果可为空间应用中的类似低温光学设计提供参考。

基于二维热传导方程的COB-LED散热器热模拟

针对COB-LED(Chip on Board-Light Emitting Diode)散热问题,文中基于二维热传导方程建立了一个可快速计算COB-LED散热器表面热分布的数学模型。为了便于模型求解,采用有限差分法求解该数学模型并选择交替方向隐格式作为其差分格式。根据模型中的边界条件和初始条件设计COB-LED常温点亮实验,并基于ANSYS有限元分析软件进行仿真分析。通过比较求解结果、仿真结果和实验结果验证该数学模型的合理性。结果表明,求解结果与实验结果中最高温度相对误差约23.57%,且两者的温度变化趋势一致。求解结果与仿真结果中最高温度相对误差约34.84%,且温度分布较为接近,证明了该数学模型的合理性与正确性。

加热炉加热过程数学模型建立

加热炉是钢铁生产中常用的设备,主要用于加热钢坯或钢材,以达到改变其组织、提高其塑性和可加工性等目的。加热炉具有结构简单、操作方便等优点,在钢铁生产中应用广泛。各种工业炉、锅炉都属于高能耗窖炉,对资源的消耗量较大,加热炉在进行钢铁材料加热时的温度较高,会通过烟气造成大量的热能损失,因此对加热炉温度的合理控制是节能降耗的有效渠道。加热炉加热过程数学模型的构建是提升加热炉温度变化精度的重要手段。充分介绍了加热炉加热过程数学模型构建的重要性,从模型理论基础、模型构建假设、数学表达以及求解方法进行探讨,并提出加热炉加热过程数学模型的优化方法,在数学模型的支撑下,加热炉温度得到控制,并且运行效率大幅度提升,为加热炉结构的完善提供借鉴。

步进底加热炉三维瞬态加热过程数学模型与验证

以步进底加热炉炉内钢坯瞬态传热过程为研究对象,综合考虑钢坯、步进底、炉衬、炉气等之间的相互影响,建立了炉内钢坯的三维瞬态传热模型。采用黑匣子实验对模型进行验证表明,该模型能够准确预测加热过程中钢坯内部的温度水平以及变化规律,模型预测精度在6%以内的命中率在80%以上,为今后的工艺优化提供了理论指导。

深度学习在易结焦加热炉温度场软测量应用总结

易结焦加热炉燃烧过程不稳定,会引起炉管局部超温,导致加热炉的损耗和破坏,因此实际工程中需要对加热炉各处的温度进行测量。文中提出一种基于红外图像与计算流体力学(CFD)的加热炉炉管温度场软测量方法,利用不同工况数据构建实验数据集,建立深度学习训练温度场实时预测模型,实现输入工况后模型即可输出对应温度场,实现工业加热炉温度场的软测量。本研究通过CFD仿真计算得出的温度场与炉管壁热电偶实测值误差均在5%以内,因此可以认为CFD仿真得到的加热炉三维温度场能够很好地代表炉膛内的真实温度场。

Zonal method solution of radiative heat transfer in a one-dimensional long roller-hearth furnace in CSP

A radiative heat transfer mathematical model for a one-dimensional long furnace was set up in a through-type roller-hearth furnace （TTRHF） in compact strip production （CSP）. To accurately predict the heat exchange in the furnace, modeling of the complex gas energy-balance equation in volume zones was considered, and the heat transfer model of heating slabs and wall lines was coupled with the radiative heat transfer model to identify the surface zonal temperature. With numerical simulation, the temperature fields of gas, slabs, and wall lines in the furnace under one typical working condition were carefully accounted and analyzed. The fundamental theory for analyzing the thermal process in TI＇RI-IF was provided.

Numerical simulation of the induction heating of a magnesium-alloy round billet

A mathematical model of the transient electro-thermal coupling of the induction heating of a magnesiumalloy round billet is established herein. The heating curve and temperature distribution characteristics of a magnesium alloy were calculated during induction heating under different parameters. Factors such as the number of coil turns and the cooling conditions were analyzed. A method for optimizing the temperature control mode and coil length of the magnesium-alloy round billet is proposed. The length of the coil and corresponding heating mode are determined through the coil length ratio( CLR),which provides a theoretical basis for the optimization of the magnesium-alloy round billet's extrusion.

Modeling of Heat Transfers in Bioreactive Household Waste Storage Facilities: Spatial and Temporal Distributions

In order to enhance the production of biogas and to study the thermal behavior of waste, a numerical study of fluid flows and heat transfers within household waste was developed to predict the distributions of thermal fields. The mathematical model is based on the conservation of mass and energy equations. The resulting system of equations is discretized using the finite volume method and solved using the Thomas algorithm. The results of the model studied are compared with the numerical and site measurements results from other authors. The results have been found to be in good agreement. The results show that the mathematical model is able to reproduce the thermal behavior in anaerobic phase in landfills. The isotherms revealed that temperatures are lower in the upper part of the waste cell, very high in the core and decrease slightly in the bottom of the cell due to the biodegradation of waste.

蓄热式加热炉加热过程在线控制数学模型研究

蓄热式加热炉是一种蓄热式换热器与常规加热炉的结合体,整体结构包括炉体、蓄热室、换向系统、供风系统、排烟系统等。采用蓄热式燃烧技术,能够帮助加热炉达到更高的炉温,从而进行工业加热生产。蓄热式加热炉的优点在于能够使炉温分布均匀,根据不同需求对炉温进行调节,大大改善加热质量,提升加热产品的合格率。在全面分析蓄热式加热炉传热机理的基础上,建立了物理和数学的3D模型来描述炉内传热和加热过程。利用CFD软件对整个炉子的燃烧过程进行模拟。最后,对整个炉内的流动和温度曲线进行了深入研究,详细揭示了炉内的流动特性和温度分布规律,对蓄热式加热炉的合理设计和优化控制具有重要理论意义和实践价值。

汽车温差发电系统的多物理场建模分析与试验

为了得到沿尾气流动方向汽车温差发电系统各温差发电片之间的温度分布差异,建立了汽车温差发电系统的流热电多物理场数学模型,该模型充分考虑了尾气流动和热电材料的温度依变性.分析了尾气温度和流量对温度分布差异的影响,并进行了汽车温差发电系统台架试验.结果表明:尾气温度的增加会加剧尾气流动方向系统各区域温差发电片之间的温度分布差异,当尾气温度从450 K增加到600 K时,差异相对增加105%;尾气流量的增加有益于减小温度分布差异,相比之下尾气温度是影响温度分布差异的主要因素;该多物理场数学模型计算精度可达97%.

基于稳态传热分析的高炉炉壁温度场建模方法

高炉炉壁温度场是掌握炉内热负荷状态和燃料燃烧情况、及时发现高炉异常工况、保障高炉稳定顺行的重要信息。针对现有炉壁温度场获取难及温度场建模过程中未考虑渣皮脱落与生成现象等问题,提出一种基于稳态传热分析的高炉炉壁温度场建模方法。首先,利用COMSOL仿真软件搭建炉壁三维仿真模型;其次,充分考虑渣皮对炉壁温度变化的影响,建立包含渣皮热源项的稳态传热模型,获得初始炉壁内表面温度场;然后,为提高温度场模型精度,基于热传导反问题理论,以冷却壁中热电偶的实测温度为参考,构建炉壁温度场修正模型,实现炉壁温度场数据的迭代修正。实验表明经温度场修正模型修正后,传热模型的计算误差控制在5%以内,满足现场检测精度要求,并能可视化展示炉壁温度场,为高炉调控操作提供了可靠的炉壁温度场数据。

基于PID参数优化的高炉加热炉壳温度控制研究

高炉的炉壳是承受极高温度、腐蚀和机械应力的部件,炉壳温度过高或过低都可能导致热应力、脱渣等问题,从而影响高炉的正常运行和寿命。通过有效的炉壳温度控制,可以保护炉壳免受过高温度和腐蚀的侵害,延长高炉的使用寿命,因此提出基于PID参数优化的高炉加热炉壳温度控制方法。利用空气定压比热、加热炉蓄热室通道面积、蓄热体比热容等多个参数确定高炉加热炉能量平衡方程,采用拉氏变换建立高炉加热炉数学模型。以加热炉数学模型为基础,遗传算法通过变异、交叉和复制等操作优化加热炉PID控制器参数。利用参数优化后的PID控制器、功率调整器、FP93导电仪表、加热管以及温度测量仪组成高炉加热炉壳温度控制架构,实现高炉加热炉壳温度控制。实验结果表明,所提方法可准确检测高炉加热炉壳的温度,控制精度以及效率高,高炉加热炉壳温度控制效果好。

Mathematical Model and Its Application of Radial Effective Thermal Conductivity for Coil Heat Transfer in HPH Furnace

Temperature uniformity of steel coils in High Performance Hydrogen bell-type annealing furnace has a significant effect on their quality and production. The hot rolled coil can be considered as a periodically laminated material composed of steel layers and interface layers in radial direction. A new formula for the radial effective thermal conductivity has been proposed, which is based on surface characteristic, strip thickness and compressive stress of the rolled coil. Furthermore, it has been used to develop a heat transfer mathematical model for steel coils in the HPH furnace. The calculated annealing curves using this mathematical model are in good agreement with the experimental data.

高精度钢坯温度预报模型研究及加热炉二级系统开发

为解决加热炉二级系统中钢坯温度预报模型和炉温设定模型功能不能适应现场生产工况变化的问题,开发了全新的加热炉二级过程控制系统,并研发了高精度钢坯温预报模型和炉温设定模型。钢坯温预报模型精度通过黑匣子试验与工业化试验校验得到了验证;炉温设定模型采用分段加权炉温设定和专家经验相结合的方法,实现了炉温的优化设定,解决了复杂生产状况下炉温自动设定这一难题。