高、转炉煤气应用于蓄热式轧钢加热炉的特性研究

研究了高炉煤气和转炉煤气的燃烧温度变化规律及应用特点。通过理论计算,分析了炉气成分及燃气种类对炉气发射率和炉内传热过程的影响规律。进行了蓄热式加热炉在蓄热过程中的热量平衡计算,得到了空、煤气在不同预热温度下烟气利用率的变化规律,并进一步分析了烟气利用率对加热炉产生的影响。此外,对比分析了使用两种煤气时对设备投资及现场空间布置的影响。     

A Mathematical Model of a Blast Furnace Injection Tuyere

One way to further utilise produced gases in an integrated metallurgical plant is to replace oil with gas as a reducing agent in a modern blast furnace. Accordingly, it is of great interest to study the injection of reducing gas into the blast furnace. Therefore, a three‐dimensional mathematical model has been developed which simulates the injection of the gas by lances into the tuyere. The model includes the coupled solution of the flow field and the chemical reaction of the gases in the tuyere. Two different types of fuel gas, coke oven gas (COG) and basic oxygen furnace gas (BOF) have been modelled using one injection lance. The modelling technique is presented and discussed as well as the implied results. Furthermore, process parameters such as different gas compositions etc. are investigated using the developed model. Not surprisingly, the main results show that the COG is combusted more completely than BOF gas, which leads to higher flame temperature of the blast putting demand forward to lower the heat load of the tuyere. However, the modelling of the raceway is as far not included in the model, hence the influence of the outlet boundary condition at the tuyere is not reflected in the presented results.     

高炉煤气与煤混烧的热电联产用流化床锅炉

介绍了以高炉煤气和劣质煤为燃料的热电联产用流化床锅炉的工作特性，阐述了为提高锅炉的燃烧效率和增强负调节能力所采取的关键技术。实际运行的情况表明：该种锅炉具有燃烧效率高，燃产适应性强，负荷调节性能好，节能效果明显和环保性能优越等优点，是冶金企业高效大量利用低热值高炉煤的敢的一种新炉型。     

转炉烟道内二次燃烧和传热传质过程的研究

采用非预混燃烧模型和离散传播辐射模型,对转炉烟道内的流动、传热传质和燃烧反应进行三维数值模拟,研究炉气转变为烟气的规律和烟道内烟气浓度分布特点.结果表明,烟道内大体可分为3个区域:炉口燃烧区,卷吸的空气在烟罩附近与炉气发生燃烧反应;烟道混合区,燃烧后的烟气与未燃炉气逐渐混合,但仍有较大的成分波动;弯头混合区,烟气进一步...     

大型光亮退火马弗炉加热段温度场模拟

建立了大型光亮退火马弗炉加热段温度场的三维仿真模型.该模型考虑了马弗炉实际结构、带钢退火速度和升温曲线特点,采用等效热流密度表征马弗管内保护气体和带钢的换热;选择组分传输燃烧模型、离散坐标辐射模型和标准k-ε双方程湍流模型描述马弗炉内燃烧、换热和气体流动;应用SIMPLE计算方法进行求解.典型规格304不锈钢带光亮退火过程实测特征点温度值和模拟结果基本吻合.分析得到了马弗炉内温度场、流场和速度场分布规律.结果表明:马弗管温度比较均匀,喷嘴正对区域温度偏高;燃气气流沿马弗管壁螺旋流动实现均匀加热.喷吹量较小时,喷吹量(入口速度)越大,马弗炉内温度越高;喷吹量继续增大,马弗炉内温度反而开始降低.      

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).     

Computational fluid-dynamics simulation of postcombustion in the electric-arc furnace

To obtain insight on the characteristics of postcombustion (PC) inside an electric-arc furnace (EAF), a three-dimensional computational fluid-dynamics (CFD) model was developed. Simulations of the process, including the PC reactions, radiation heat transfer, and de-PC reactions have been conducted. Dissociation reactions of the PC products were also considered in the PC model. The predicted temperatures are realistic because of the inclusion of radiation and the dissociation of CO₂. Based on gas/liquid and gas/solid interfacial reaction kinetics, a de-PC reaction model was developed and successfully integrated into the CFD model to simulate the reactions between O₂/CO₂ and carbon in the liquid metal, the electrodes, and the scrap. It was found that the de-PC reactions decrease the net heat generated by reactions in the furnace and decrease the PC ratio. The rate of oxidation of the electrodes was also calculated. Radiation was found to be the main heat-transfer mechanism from hot combustion gas to the metal and furnace wall. Under a flat-bath condition, the heat-transfer efficiency is very poor, most of the heat generated by PC is transferred to the furnace wall. When a low-temperature scrap pile exists in the furnace, the heat-transfer efficiency is improved significantly. Air ingress from the slag door significantly decreased the PC ratio and the heat-transfer efficiency.     

多约束条件下回转窑-氧煤燃烧熔分炉热工分析

 传统高炉炼铁工艺具有冶炼流程长、污染物排放大的问题,因此非高炉炼铁技术引起了国内外学者的广泛关注。通过建立热量与物料平衡耦合的数学模型,对回转窑预还原-氧煤燃烧熔分炉物料平衡和热平衡进行计算,揭示不同金属化率、煤气氧化度及鼓风氧含量条件下的热工参数变化规律,最后使用Lingo软件对工艺进行热工分析,确定回转窑内预还原金属化率等与熔分炉适宜煤粉消耗量的关系。结果表明,升高金属化率、煤气氧化度及鼓风氧含量均可以降低工艺煤耗和氧耗,但煤气量及煤气热值并不会随着操作参数的升高而达到最优,在对工况参数进行最优求解后得知,在炉料金属化率为70%、熔分炉煤气氧化度为16%且鼓风氧为100%时,回转窑-氧煤燃烧熔分炉工况条件最好。     

Coal pyrolysis in a rotary kiln: Part II. Overall model of the furnace

In order to simulate coal pyrolysis in a rotary kiln in the steady-state regime, a mathematical model has been developed which calculates the temperature profiles in the charge, the gas, and the furnace walls, together with the gas composition and the degree of removal of volatile species. The model takes into account the principal physicochemical and thermal phenomena involved, including the complex movements of the charge; the gas flow; heat transfer between the charge, the gas phase, and the furnace walls; drying and pyrolysis of the coal; the cracking of tars; the combustion of volatile species; and the combustion and extinction of the coke. The data necessary for the model were obtained by specific experiments or from the literature. The model has been validated by comparing its predictions to measurements performed on an industrial rotary kiln. The model has been used to study the influence of operating parameters such as the furnace rotation speed, in order to optimize the process. It is shown how a modification to the extinction zone leads to an increase in coke yield of 0.75 pct.     

陶瓷蜂窝蓄热体的热应力分析

分析了高风温燃烧系统中陶瓷蜂窝蓄热体和气体间的热量交换,建立了陶瓷蜂窝蓄热体传热过程数学模型。对于由温度分布不均匀,陶瓷蓄热体膨胀或收缩受限制而产生的热应力进行了计算和分析,其结果为蓄热式高风温燃烧系统的设计及运行参数的选择提供了理论依据。     

高炉冷却壁与炉气之间的换热特性

 基于边界条件替换方法建立了高炉冷却壁本体和捣打料与炉气之间的换热系数计算模型。用试验测量冷却壁近热面温度来推算冷却壁热面温度，与冷却壁温度场计算模型结合，确定了炉气温度在500~1 248 ℃范围内，高炉冷却壁与炉气之间的换热系数。结果表明，本模型的计算值与前苏联学者的试验结果吻合。     

Mathematical Model of Combustion in Blunt Annular Ceramic Burner

Symbol L ist　　A—— oxidant flow;　　c1 ,c2 —— constant of the k- ε urbulent model;　　 cg1 ,cg2 —— constant of the turbulent combustion model;　　f—— mixture fraction;　　 f,- f—— value of mixture fraction;　　 fu— fuel;　　F—— fuel flow;　　g—— concentration fluctuation;　　 H—— enthalpy,J;　　k—— kinertic energy for turbulent,m2 / s2 ;　　ma—— mass fraction of material a;　　 ox—— oxidant;　　 r,θ,z—— coordinate axis for cylinder coordinatesystem;　　 s—— equ…     

高温低氧燃烧方法的热工规律和扩大应用

提出了用烟气直接入炉循环建立低氧气氛，实现高温低氧的燃烧方法，导出描述该气氛氧浓度和温度变化规律的数学模型，浅析了燃烧过程的机理，对该方法重新给予定义，分析了该方法节能作用的数量关系，阐述了换热式高温低氧燃烧的优越性，主张换热式高温低氧燃烧方法应该在多种炉窑上使用，以便取得重大的节能环保效果。     

Coal pyrolysis and kinetic model for non-recovery coke ovens

Abstract

In heat recovery non-recovery coke ovens, the volatile gases generated are burnt, and the heat generated is used for cokemaking. The extra heat, along with the flue gases, is utilised in boilers for power generation. JSW Steel has 1·2 Mtpa non-recovery coke ovens to meet the coke requirement of blast furnaces. Until now, very limited work has been carried out on heat distribution in non-recovery coke ovens. In this work, the heat distribution in non-recovery coke ovens is studied to determine the variables influencing the flue gas temperature and thereby power generation. A mathematical model has been developed to predict the power generation using functional group, depolymerisation, vaporisation and cross-linking for non-recovery coke ovens at JSW Steel. Gas generation, heat generation, power generation and total heat distribution are calculated using the model. The present paper details the study on heat distribution, thereby various factors affecting the power generation, and also quantifies the effect of coal quality in particular volatile matter on gas generation, flue gas temperature and power generation.     

Mathematical modeling of an aluminum casting furnace combustion chamber

A mathematical model has been developed for the combustion chambers of aluminum casting furnaces by combining the fluid flow code PHOENICS with a zone model for the radiative heat transfer analysis and a simplified flame model. It offers flexibility in specifying the size and the combustion and heat transfer characteristics of the furnace. Thus, the model can be used to study a combustion chamber under different operating conditions and for different design op-tions. This paper presents the model and describes the coupling mechanism between PHOENICS and the zone method. Various case studies have been carried out for a 72-ton melter-holder. Results are presented which show the negative effect of ambient air inleakage on furnace per-formance as an application example. T. BOURGEOIS, Formerly Graduate Student.     

Comprehensive Mathematical Model and Optimum Process Parameters of Nitrogen Free Blast Furnace简

According to different energy utilization in different regions, blast furnace is divided into raceway zone, bottom heat exchange zone （BHZ）, thermal reserve zone （TRZ）, and top heat exchange zone （THZ）, and a mathe- matical model of nitrogen free blast furnace （NF-BF） is established. The optimum process parameters of two kinds of nitrogen free blast furnaces are calculated by the new mathematical model. The results show that for the nitrogen free blast furnace with a single row of tuyeres, the optimum process parameters are coke ratio of 220 kg/t, coal ratio of 193 kg/t, and volume of recycling top gas of 577 m3/t; for two rows of tuyeres, the process parameters are coke ratio of 202 kg/t, coal ratio of 211 kg/t, volume of recycling top gas in upper area of 296 m3/t, and volume of recy- cling top gas in lower area of 295 ma/t. Energy balances are reached in different regions. Theoretical combustion temperature （TCT） in raceway zone is largely affected by different processes, and a lower TCT should be adopted for the single row of tuyeres, but for two rows of tuyeres, a higher TCT should be maintained. Compared with tradi- tional blast furnace, in NF-BF, the emission of CO2 would be reduced by 45.91% and 49.02G for a single row of tuyeres and two rows of tuyeres, respectively, and combined with CO2 sequestration technology, zero emission of CO2 could be realized.     

宝钢2BF炉身喷涂实践及效果

简述了宝钢2BF炉身喷涂部位及喷涂厚度,并详细分析了喷涂前后生产的多项经济技术指标。2BF此次炉身喷涂消除了因焊缝开裂造成的休减风,降低了崩滑料次数,明显降低了喷涂部位对应的21~54段热负荷,煤气利用率提高,显著改善了高炉顺行状态。高炉顺行整体改善带来了利用系数的增加,总焦比降低,煤比上升,铁水质量大幅度提高。     

高炉喷吹还原气操作的数学模拟研究

副产煤气的高效利用对钢铁产业的节能降耗和环境保护意义重大。为此,提出了一个新的高炉风口喷吹高炉、转炉和焦炉煤气技术,并利用多流体高炉模型对其进行了详细模拟研究,预测了炉内现象和操作性能的变化。在维持回旋区温度、炉腹煤气量及渣面处铁水温度一致的条件下,模拟结果表明与现行常规操作相比,风口喷吹煤气后炉身温度下降,但整个炉内H₂/CO浓度显著提高,炉身烧结矿间接还原加速,产量明显增加,热利用效率明显改善。其中喷吹焦炉煤气效果最为显著,高炉CO₂产生量大幅度降低。随工艺氧制备等技术的进步,高炉喷吹副产煤气技术具有广阔的应用前景。     

CFD仿真技术在板坯加热炉的应用

以某公司热轧厂常规与双蓄热烧嘴组合供热的板坯加热炉为研究对象,建立该加热炉炉内流动、传热和燃烧过程三维物理数学模型,并运用CFD仿真技术对其进行数值计算,得出炉内速度场和温度场的分布规律。同时,研究了板坯和烟气之间传热特性。     

气基竖炉直接还原技术的发展现状与展望

 阐述了气基竖炉直接还原工艺的技术特点和发展现状,分析了在中国资源和能源条件下气基竖炉直接还原技术发展所面临的主要问题。基于气基竖炉直接还原工艺的特点,对该工艺的原料、还原气等进行了分析研究。指出非常规天然气资源的有效开采和加压煤制气工艺投资、运行成本的显著降低,将是未来气基竖炉直接还原技术发展的主要推动力,同时利用钢铁企业过剩的煤气资源和中国局部地区相对丰富的天然气资源生产直接还原铁,是今后中国气基竖炉直接还原技术发展的重要方向。参照唐山地区的原料和能源价格,对年产量为80万t/a的直接还原铁装置的生产成本和技术经济可行性进行了分析,分析结果表明：原燃料价格波动对DRI成本影响显著,其中还原气成本约占DRI生产成本的10%~25%;若按DRI替代转炉废钢计算效益,要求天然气价格低于1.8元/m3。