环形加热炉管坯二维传热数学模型采用总括热吸收率法的探讨

总括热吸收率法一般只用于钢坯加热过程一维数学模型的计算中,采用CFD模拟并结合黑匣子测试结果来分析管坯加热过程的总括热吸收率,将总括热吸收率法应用于环形加热炉管坯二维在线数学模型中,通过实践证明了该方法的可行性。     

环形加热炉管坯二维在线数学模型的研究

总括热吸收率法一般只用于钢坯加热过程一维在线数学模型的计算中,总结前人的研究工作,采用CFD模拟并结合黑匣子测试结果来分析管坯加热过程的总括热吸收率,将总括热吸收率法应用于环形加热炉管坯二维在线数学模型中,通过模拟计算证明了该方法的可行性。     

燃料比对蓄热式加热炉热工过程的影响

建立了蓄热式加热炉数学模型,研究炉子结构参数及燃料一定时,沿炉长方向燃料比变化对加热炉热工过程的影响。在加热炉额定生产率下,分析了炉子第一、第二加热段和均热段燃料比变化对炉气、炉壁、钢坯上表面温度和钢坯断面温差等参数的影响,得出该加热炉的最优燃料比;研究了不同生产率下燃料比对加热炉热工过程的的影响,研究表明最优燃料比不随生产率变化而变化。该研究结果为优化蓄热式加热炉热工运行提供了重要的指导作用。     

步进梁式连续加热炉总括热吸收率分布规律的实验研究

在某公司步进梁式连续加热炉上进行了钢坯内部温度分布规律的"黑匣子"实验研究,详细地介绍该实验的基本原理和实施方法,得出了总括热吸收率随炉长的分布规律。所做工作对实施加热炉的计算机优化控制奠定了坚实的理论基础。     

热装加热炉热工制度的研究

利用炉内钢坯加热过程的数学模型及热平衡模型,依据加热炉不同产量和不同热装温度条件下,对热装加热炉的钢坯加热过程和燃料消耗进行了数值模拟和优化.结果表明,热装加热炉的热工制度如不作调整,物料热装带来的节能潜力得不到充分发挥,调整后的加热炉温度制度将具有最大的节能潜力.     

管坯加热炉的发展历史及应用现状

在钢管的生产工艺中,轧制前的管坯加热工艺是非常重要的工序之一,管坯是否达到要求的加热温度以及管坯本身的温度是否均匀等因素都会影响最终成品的质量.详尽地介绍了管坯加热炉的发展历史和应用现状,并针对目前先进的蓄热式环形加热炉作了重点介绍,所作工作为管坯加热炉的发展起到了一定的借鉴、指导作用.     

环形加热炉管坯温度优化控制的研究

结合宝山钢铁（集团）公司钢管分公司环形加热炉的实际情况,通过建立环形加热炉数学模型,实现了以管坯温度为直接控制目标的在线优化控制,控制系统包括管坯物料跟踪,温度跟踪,炉温优化动态设定,低氧化烧损空燃比智能设定,待轧控制,出炉温度反馈等功能,取得了良好的控制和节能效果。     

环形加热炉炉温在线分段寻优策略研究

以环形加热炉在标准产量下满足加热质量要求为前提,以燃耗和氧化烧损最低为目标,通过离线优化研究,得到了标准产量下不同管坯的最优升温曲线。在环形加热炉数学模型优化控制系统中,以管坯最优升温曲线为基础,对炉温进行分段在线寻优,取得了良好的控制效果。     

冶金步进式加热炉钢坯加热过程全尺寸数值研究

为了深入了解冶金步进加热炉中钢坯的换热过程，以一种新型燃料分级燃烧器为核心，以某钢厂1422号线3号炉为研究背景，建立了1∶1的全尺寸加热炉模型，同时采用稳态模拟与瞬态模拟结合的方法，研究了钢坯静止在加热炉均热段时的加热过程，得到了此时钢坯的温度分布情况，结果显示：该新型研究方法能够准确地描述步进加热炉加热钢坯时的传热情况；均热段的温度比其他各段的温度约高100℃;采用均热段加热时，顶部燃烧器的高温烟气会绕到钢坯下方对下表面进行加热，使钢坯下表面升温更快；加热60 min时钢坯已经达到目标出炉温度，而且温差最小，为9.83℃,随后由于均热段的二次加热温差反而增大，最终温差为17.42℃;所述工况条件下，钢坯达到目标温度时所用的加热时间和均热时间共64 min,与实际估算的时间80 min相差16 min,基本符合实际情况。     

环形加热炉燃耗影响因素分析及降耗措施

以包钢集团包头无缝钢管厂36m环形加热炉改造项目为例,通过分析指出加热温度、加热时间、热损失、负荷率、炉型结构、设备预留能力等是影响环形炉燃耗的主要因素,并从炉型设计、燃烧控制、生产工艺制度等方面给出具体的降耗措施。经过1年的生产实践证明,管坯氧化烧损少,加热质量好,燃料消耗低,环境污染少。     

蓄热式连续加热炉内流动与换热特性的数值模拟

以某公司大方坯蓄热式连续加热炉为研究对象,对该炉建立了三维物理数学模型,分别采用可实现双方程湍流模型,PDF非预混燃烧模型、离散坐标法辐射模型(DO模型),应用Fluent数值仿真软件进行了模拟研究,得到了蓄热式连续加热炉内的流场和温度场的分布规律,并对炉内对流换热系数的分布进行了详细的分析研究.结果表明:钢坯表面局部对流换热系数在各加热段内分布不均匀,这主要是由于烧嘴进口射流所引起的局部流速的差异性,从整体上来看,预热段和加热1段的对流换热系数要高于其它各段.     

Coupled Heat Transfer Simulation of the Spiral Water Wall in a Double Reheat Ultra-supercritical Boiler

This paper presented a coupled heat transfer model combining the combustion in the furnace and the ultra-supercritical(USC) heat transfer in the water wall tubes. The thermal analysis of the spiral water wall in a 1000 MW double reheat USC boiler was conducted by the coupled heat transfer simulations. The simulation results show that there are two peak heat flux regions on each wall of spiral water wall, where the primary combustion zone and burnt-out zone locate respectively. In the full load condition, the maximal heat flux of the primary combustion zone is close to 500 kW/m~2, which is higher than that in the conventional single reheat USC boilers. The heat flux along the furnace width presents a parabolic shape that the values in the furnace center are much higher than that in the corner regions. The distribution of water wall temperature has a perfect accordance with the heat flux distribution of the parabolic shape curves, which can illustrate the distribution of water wall temperature is mainly determined by heat flux on the water wall. The maximal water wall temperature occurs at the middle width of furnace wall and approaches 530°C, which can be allowed by the metal material of water wall tube 12Cr1MoVG. In the primary combustion zone, the wall temperatures in half load are almost close to the values in 75% load condition, caused by the heat transfer deterioration of the subcritical pressure fluid under the high heat flux condition. The simulation results in this study are beneficial to the better design and operational optimization for the double reheat USC boilers.     

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.     

热处理钢板气雾冷却数学模型的开发与应用

针对某钢厂新建的热处理钢板气雾冷却装置,基于有限差分传热仿真计算,开发了相应的热处理钢板气雾冷却数学模型,其中详细考虑了钢板在冷却区内所经历的多种传热边界条件,包括水冲击传热、辊子接触传热、辐射传热和自然对流传热。通过现场的钢板表面温度测试工作表明,模型预测值与实际测试值之间的吻合情况良好,模型具有较高的仿真精度。应用该模型,按照一定的热处理工艺要求(主要指对出口温度和钢板表面/中心温降速率的控制),对气雾冷却区进行了冷却水表的理论设计(即各种厚度规格钢板所对应的冷却水流量),其设计结果已成功地应用于生产现场。     

Conjugate heat transfer analysis of copper staves and sensor bars in a blast furnace for various refractory lining thickness

Lining erosion is the most important factor for determining the campaign life of a blast furnace. To provide information about the heat transfer of the copper stave in the belly of the No. 1 blast furnace at CSC (China Steel Corporation), a conjugate heat transfer model, including the heat transfer of the stave and sensor bar in thermal conduction and radiation transmission from the gas temperature inside the blast furnace and convection heat transfer in cooling pipe, was developed for the steady state process. The simulations focus specifically on the effects of the gas temperature, the geometric thickness of the cooling stave, the slag layer thickness and the material and diameter of the sensor bar. The results show that the refractory lining and the slag shell provide significant protection for the stave body. A copper sensor bar can be used to measure the residual lining thickness of the cooling stave. To estimate a more reasonable stave thickness, several key factors, such as the diameter and material of the sensor bar, were examined in this study. The results can serve as important reference information for blast furnace operation and the prediction of its campaign life.     

燃用宽筛分煤循环流化床锅炉燃烧模拟计算

建立了循环流化床锅炉炉膛颗粒燃烧和脱硫反应模型。该模型考虑了炉膛下部为高颗粒浓度的密相区和上部为低颗粒浓度稀相区的特征,模拟计算给出了烟气温度,热流密度和各气体成分（Ｏ２,Ｃ２Ｏ,ＣＯ,Ｈ２Ｏ和Ｓ２Ｏ）的轴向分布,模拟计算结果的趋势是合理的。     

A heat transfer model for the analysis of transient heating of the slab in a direct-fired walking beam type reheating furnace

A mathematical heat transfer model for the prediction of heat flux on the slab surface and temperature distribution in the slab has been developed by considering the thermal radiation in the furnace chamber and transient heat conduction governing equations in the slab, respectively. The furnace is modeled as radiating medium with spatially varying temperature and constant absorption coefficient. The steel slabs are moved on the next fixed beam by the walking beam after being heated up through the non-firing, charging, preheating, heating, and soaking zones in the furnace. Radiative heat flux calculated from the radiative heat exchange within the furnace modeled using the FVM by considering the effect of furnace wall, slab, and combustion gases is introduced as the boundary condition of the transient conduction equation of the slab. Heat transfer characteristics and temperature behavior of the slab is investigated by changing such parameters as absorption coefficient and emissivity of the slab. Comparison with the experimental work show that the present heat transfer model works well for the prediction of thermal behavior of the slab in the reheating furnace.     

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.     

Manufacturing and testing of a gamma type Stirling engine

In this study, a gamma type Stirling engine with 276 cc swept volume was designed and manufactured. The engine was tested with air and helium by using an electrical furnace as heat source. Working characteristics of the engine were obtained within the range of heat source temperature 700–1000 °C and range of charge pressure 1–4.5 bar. Maximum power output was obtained with helium at 1000 °C heat source temperature and 4 bar charge pressure as 128.3 W. The maximum torque was obtained as 2 N m at 1000 °C heat source temperature and 4 bar helium charge pressure. Results were found to be encouraging to initiate a Stirling engine project for 1 kW power output.