高炉布料的焦层坍塌建模方法研究

炉料分布是影响高炉内煤气流分布的决定性因素之一。在高炉布料过程中,矿石的冲击作用使部分焦层坍塌并堆积到炉中心区,考虑这一因素对料层分布的影响,在试验和统计分析基础上,采用一种简化方式模拟了布料过程的焦层坍塌现象。它以专家规则修正料面曲线,依据物料平衡关系求解模型参数,通过分析高炉径向温度和径向矿焦比分布,间接验证了布料模型中焦层坍塌修正方法。     

A static approach towards coke collapse modelling in blast furnace

Abstract

Burden distribution control in a blast furnace has a close relationship with wind acceptance and gas utilisation. Quantification of radial distribution of ore and coke is important for proper control of blast furnace operation. Charging of metallic burden over a layer of coke causes a portion of the coke layer to get dislodged from its original position, similar to the situation observed when a heavy material is dropped on a bed of lighter particles. This phenomenon, designated 'coke collapse', significantly changes the ore/coke distribution in the radial direction and thus affects the permeability of the furnace shaft. In the present work a mathematical model for quantifying the amount of coke collapse has been proposed on the basis of 'stability of slope theory'. The calculation from this model has been compared with the results from experiments in simplified physical models. Predictions of the mathematical model are in good agreement with experimental results.     

高炉中心加焦炉料分布机理及布料方式探讨

 针对当前常见的中心加焦装料过程,建立了布料过程中螺旋布料时溜槽内炉料颗粒复合运动的三维数学模型,并建立了炉料颗粒在空区内下落过程数学模型和在炉内堆积所形成料面形状及其径向矿焦比分布数学模型。通过将模型预测料面形状与高炉开炉实测料面形状进行对比,证明了模型的有效性。基于实际高炉参数,计算了13°完全中心加焦和20°小角度中心加焦时炉料落点分布和径向矿焦比分布。结果表明,由于中心加焦过程中部分炉料会分布在中间环带,使得实际中心加焦量减少,两者有效的中心加焦率分别为49.4%和70.4%,且在前者模式下形成了直径约为1.2 m的贯通的中心焦柱区域,而在后者条件下形成中心直径约为2.5 m的较大范围的低矿焦比分布柱状区域。最后,阐述了中心加焦技术原理,指出了当前中心加焦操作方式存在的问题,并探讨了高效布料方式,对指导实际高炉生产操作有着重要意义。     

并罐式无钟炉顶装料模式对料面炉料分布的影响

 为研究装料模式对并罐高炉料面炉料分布的影响,建立了国内某5 500 m3实际高炉并罐式无钟炉顶系统全模型,利用离散单元法分别对矿（A）-矿（B）-焦和矿-焦两种装料模式下炉料从矿焦槽运动至料面全过程进行数值计算,对比分析了装料模式对料面炉料分布的影响。结果表明,由于A矿与B矿布入料面时落点轨迹不重合,导致两种装料模式下料面炉料分布不同。在料面径向上,装料模式对料面矿石体积分布和矿焦比分布影响较小。在料面周向上,矿-矿-焦装料模式和矿-焦装料模式下料面矿石体积分布标准差分别为0.133和0.147,矿-矿-焦装料模式和矿-焦装料模式下料面矿焦比分布标准差分别为0.074和0.086,矿-矿-焦装料模式下矿石体积分布和矿焦比分布更均匀。     

回旋区深度对上部炉料运动影响的模拟分析

冶炼实践已证实,高炉回旋区形状和大小影响上部炉料的运动,进而影响煤气流分布及煤气利用率。已有研究多集中在回旋区形状、大小与高炉生产指标的关系,对相关影响机理和规律较少有深入分析。针对此问题,建立二维狭槽半高炉模型,采用离散单元法(DEM)对回旋区深度与炉料形态、混合程度、径向矿焦比的关系进行数值模拟探索。模型中考虑了炉料颗粒在下降过程中的粒度变化,利用离散单元法-计算流体力学(DEM-CFD)耦合方法得到料柱孔隙率分布特征。结果表明,随着回旋区深度增加,料批下降趋向均匀,料层倾斜程度减小,块状带下部炉料混合程度减小;随着料批的下降,矿石相对于焦炭逐渐向中心偏移,回旋区深度对料批径向矿焦比分布无明显影响;块状带整体孔隙率随回旋区深度增加而减小,变化幅度在2.1%左右;回旋区深度较大时,软熔带会有孔隙率较高的区域(较宽焦窗)。     

无料钟炉顶布料实践及分析

在武钢2号高炉进行了串罐无料钟炉顶布料实践,分析了多角度中心加焦、折返布矿、拓宽布料区间等布料方式引起煤气流变化及改变煤气利用的原因,在2号高炉的原燃料条件下,采用折返布矿和拓宽布料区间的布料模式取得了较好的技术经济指标,布料模式的摸索还须继续;增加矿石层厚度或调整小粒度矿落点位置,可增大煤气阻力,有利于增加间接还原,提高煤气利用率;完善各种检测设备,开发和应用高精度布料技术,丰富高炉专家系统,可进一步优化高炉操作。     

莱钢3200m^3高炉降低燃料比的操作实践

针对开炉后炉顶煤气温度高、频繁打水降温、燃料比高、渣铁排放不稳定、焦炭热强度偏低等问题,采取调整布料制度、优化煤气流分布、稳定和改善原燃料质量及炮泥质量等措施,燃料比从543kg/t下降到498kg/t,生铁日产量提升约800t,炉况稳定顺行。     

大型高炉实用布料模型开发

针对无料钟炉顶炉料分布检测难的现状,解析炉料的布料机理,结合生产数据和专家经验,开发大型高炉布料数学模型,并在此基础上开发仿真模型,实现了料面形状和矿焦比分布的界面化,指导高炉操作者优化布料制度。系统运行表明,模型可以有效地预测布料矩阵形成的料面形状和矿焦比分布,从而为优化高炉布料操作提供技术支撑,保障高炉稳定顺行。     

武钢5号高炉专家系统在布料状态评估中的应用

高炉布料调剂对于维持高炉的稳定顺行具有决定性的意义。武汉钢铁(集团)公司新开发的5号高炉专家系统利用数学模型实现了高炉布料调剂的自动处理,通过利用数学模型处理高炉操作数据,如炉顶煤气温度、炉顶煤气成分、压差、冷却壁温度变化等,可以获得对气流分布状况、炉型变化状况及高炉运行状况的评估结果;结合高炉当前的运行状况,如焦比、风量、炉身静压力、原料状况(组成、粒度、热性能等)等就可以获得调剂的建议。高炉冶炼专家系统投入运行后,有效指导了高炉的布料调剂,高炉操作稳定,工艺指标得到改善。     

鞍钢无料钟布料数学模型研制与应用

阐述了鞍钢无料钟布料模型的开发与应用,重点分析了模型对料流阀开口度、料面形状和矿／焦比分布应用的结果。选择料流阀开口度采用三种方法,一是理论计算方法;二是利用实际测量数据对理论模型进行修正后,采用体积流速计算方法;三是利用实际测量数据对理论模型进行修正后,采用重量流速计算方法。通过对比三种方法结果,认为采用体积流速计算方法最能够保证布料过程料层均匀,无料钟布料模型可以实现对各种布料制度、料面形状的计算。     

无钟高炉料层内孔隙的分布

高炉装料系统是调节炉料在炉内原始分布的唯一手段,料层的孔隙率分布会对煤气流分布产生重要影响。以某高炉1/10布料模型为研究对象,首先测量了炉料物性参数,然后采用离散元法对散料堆孔隙率分布、布料矩阵和料线高度对料层径向孔隙率分布的影响进行了研究。结果表明,实验室测量获得烧结矿、焦炭和球团矿物性参数和文献中引用的数据相差较大;料堆孔隙分布和颗粒形状有密切关系;布料矩阵通过影响颗粒数目来影响孔隙率分布,布料圈数增加,孔隙率下降,布料角度变化较大时才会影响料层孔隙率的径向分布曲线;随着料线高度增加,料层底部径向孔隙率的值会增大。没有数据显示料堆粒度偏析和孔隙分布有必然关系。     

On-line model of gas distribution in the blast furnace

In this paper a model for on-line estimation of the radial gas distribution in blast furnaces is presented. The model is based on molar and energy flow balances for the blast furnace top, using the top gas temperature and gas temperature measurements from a fixed above-burden probe. The radial distribution of the gas flux in the upper shaft is estimated by means of a Kaiman filter. Using measurement data from a Finnish blast furnace, the method is illustrated to capture short-term dynamics and to detect sudden (larger) changes in the gas distribution.     

Numerical Investigation of the Radial Ore-to-Coke Ratio in the Blast Furnace Throat during Nonuniform Burden Descent

The burden descent in the blast furnace throat affects the radial ore-to-coke ratio, which is directly related to the gas distribution and chemical reactions in the furnace. Herein, the layer structure and the radial ore-to-coke ratio of the burden bed under uniform and nonuniform burden descent are studied numerically by the discrete element method. Two kinds of nonuniform descent are considered, where the descent rate in the furnace center is greater than the descent rate at the wall or vice versa. The descent is realized by deleting particles in virtual boxes of different sizes at the lower end of the simulated domain. The results show that the ore-to-coke ratio decreases where the descent rate is low and increases where the descent rate is high. For a burden profile of the “platform + hopper” type, a faster burden descent in the center has a much stronger influence on the radial ore-to-coke ratio distribution than the case with faster descent at the wall. The size difference between the ore and coke particles and the charging matrix are also found to play a role in the influence of the burden descent on the distribution of the ore-to-coke ratio.     

Mathematical model for burden distribution in blast furnace

Burden distribution in a blast furnace is vital to its smooth running. However, it is difficult to directly measure the burden distribution for an operating blast furnace. Therefore, mathematical models have been applied to guide the charging process to achieve the desired burden distribution. The accuracies of such models depend on the prediction of falling curve, stockline profile formation, and burden descent mode. In this study, a new stockline profile formation model is proposed in which new equations have been developed for the inner and outer repose angle by considering the influence of the burden flow's vertical and horizontal velocity at the apex of the stockline profile. Validation of this new stockline profile formation model is provided through comparison between calculated results and experimental data for stockline profile. A stepped burden descending strategy, in which the burden would descend through a specified distance after each ring charging process, is proposed corresponding to the successive charging process. The influence of the burden descending strategy on the falling point, the final burden profile and radial depth ratio of ore to coke is also analysed. The result shows that the burden descending strategy greatly affects the final burden distribution, especially in the peripheral region.     

高炉上部炉型对炉料运动影响的数值模拟

高炉炉型对炉料在炉内运动规律有着决定性影响.以某企业高炉参数为原型,采用离散元方法对不同炉型条件下炉料运动进行了数值模拟,分析了炉料运动规律及其对矿焦比和孔隙率分布的影响.研究结果表明,在布料条件相同时,炉身角变小后,炉容扩大,炉料运动速度减缓;炉料下降过程中,矿石会向下降最快位置聚集,炉身角减小后,矿石边缘分布趋势更...     

Experimental study on the effect of using nut coke on the permeability of packed beds in blast furnaces

The charging pattern may affect blast furnace permeability,coke ratio,and the freedom to select low-grade raw materials. Ore-coke mixed charging is a potential technique for optimizing the charging pattern. In recent years,charging small-sized coke( nut coke) into the burden layer has been applied to save raw materials and decrease cost.Although mixed charging,especially adding nut coke into the burden layer,may have many advantages,the mechanisms and side effects of nut coke use are not well understood,and the mixing ratio is still limited in industrial blast furnace operation. In this study,the status of mixed charging,especially nut coke used in blast furnaces,was investigated. A cold flow model was established to study the permeability of the packed bed in the blast furnace "dry zone"under different conditions with the aim of better understanding the mechanisms of mixing coke and nut coke into the burden layer. The effect of coke size,mixing coke ratio,layer numbers,and gas flow rate on the pressure drop of the packed bed was investigated. The experimental results show that mixing the nut coke in the ore layers decreases the pressure drop to different extents depending on mixing ratio.     

Burden Distribution Calculation of Bell-Less Top of Blast Furnace Based on Multi-Radar Data

 The burden distribution real-time estimation problem of multi-loop charging based on the real multi-radar data is resolved. Firstly, an iterative algorithm is introduced to calculate the radial coordinate of the pile-top. Then, based on the multi-radar data, the burden profile is estimated by a cubic-curve equation at the end of the multi-loop charging. Furthermore, the burden profile before the next multi-loop charging is calculated based on multi-radar data by considering the impact of burden descent. On the basis of these burden profiles, a more accurate thickness ratio of ore to coke (RO/C) at the radial direction of blast furnace can be obtained. Finally, an example is given to calculate the burden profiles and RO/C by using the real multi-radar data sampled from Baosteel, which shows the effectiveness of the method introduced.     

Influence of Profile of Blast Furnace on Motion and Stress of Burden by 3D-DEM

 The objective of the present investigation is to analyze the influence of profile of blast furnace on the burden motion and stress field through 3D-DEM (three-dimensional discrete element method). It is clarified that the decrease of shaft angle speeds up the velocity of burden descending and decreases normal stress between particles or particle and wall. This change is good for the smooth operation of blast furnace. However, ore and coke would be mixed for the too small shaft angle (75°), which would influence the permeability in blast furnace. Thus, the appropriate shaft angle is around 80°. Decrease of bosh angle prevents the burden descending motion and increases normal stress between particles and bosh wall. Meanwhile, maximum normal stress acting on the wall moves from belly wall to bosh wall in the case of 68° bosh angle, which accelerates abrasion of refractory in bosh by friction force between particles and wall. Although burden descends smoothly in the case of 88° bosh angle, room is not enough for the ascending heated gas flow. Thus, the appropriate bosh angle is about 78°.     

承钢4#高炉调整煤气流分布的实践

煤气流分布对高炉冶炼有重要影响,分析了承钢4#高炉煤气流波动的原因,从送风制度、装料制度、热制度等方面进行调整后,高炉煤气流得到了很好控制,达到了煤气流分布合理、高炉稳定顺行、煤气利用率提高、焦比降低的目的.     

无钟高炉布料数学模型的研究

 结合无钟高炉布料的主要规律,开发出高炉布料模型。该模型有以下主要特点：炉料出下料罐的运动为“烟道流”;原始料面假设条件的改进;料面形状多段线性化处理;料面下降分为二部分对新料面修正。利用该模型可以求解料面形状,并计算炉料的矿焦比（O/C）。