加焦方式对气化炉内气流分布的影响

布料模式决定了料床的空隙度,而料床的空隙度分布决定了煤气流的二次分布.本文建立了研究三维气化炉炉料结构和煤气流分布的物理模型和数学模型,物理模型采用热电偶测温的方法,从炉内气体温度分布信息考察了气体的流动情况,由于物理实验无法获得内部空隙度分布信息,故基于离散单元法模型,以Fluent软件为载体,利用多孔介质模型并加入用户自定义函数,通过数学模型进一步研究了不同加焦方式下气化炉内煤气流分布的影响机理,获得了气化炉内煤气的速度场和流线.物理模拟与数值模拟结果相吻合.通过模拟计算获得的非均匀床层内气体流动规律的认识对COREX气化炉加焦工艺有借鉴意义.     

高炉中心加焦制度下煤气流速度与压力场模拟

不同的布料制度决定炉料的分布状态与不同部位炉料孔隙度的大小,进而影响煤气流在炉内的速度与压力分布,而煤气流的分布直接影响高炉顺行、煤气流利用率与料柱透气性的优劣.为促进煤气流合理分布,进一步探索高炉在中心加焦条件下炉内不同部位的煤气流速与压力变化规律,借助数值模拟方法,建立二维高炉煤气流流动物理模型,基于多孔介质算法并...     

COREX熔化气化炉布料模式对煤气流分布的影响

布料模式决定了料床的空隙度,而料床的空隙度分布决定了煤气流的第二次分布.通过建立二维的COREX-3000气化炉煤气流动的数学模型,以Fluent软件为载体,采用多孔介质模型描述了单环布料、多环布料两种不同布料模式下的料床内的煤气流动状况,获得了气化炉内煤气的速度场和压力场.结果表明:因布料过程在料面上发生的炉料粒度偏析造成的空隙度分布对煤气流分布的影响很大.在单环布料时,炉料堆尖处煤气流速很低,随着布料档位外移,气化炉整体压差呈现先增加后减小的趋势,拐点出现在3.0 m布料档位,可见炉料布料方式对煤气流有再分配的作用,较为适宜的布料档位为2.5～3.5 m,不宜低于2.0 m和超过4.0 m的档位.通过模拟计算获得的非均匀床层中气体流动规律的认识对COREX气化炉工艺有借鉴意义.     

COREX熔化气化炉物料运动和气流分布

摘要：基于离散元数值计算方法(DEM),建立了熔化气化炉模型的离散元数学模型。应用此模型从颗粒尺度对气化炉3种软熔区域形状下的物料质量、运动速度、法向力、空隙度分布进行了研究。利用DEM计算空隙度数值,再结合计算流体力学软件对气化炉气流分布进行了计算。结果表明：软熔区域形状对气化炉料面形状和炉内下部法向力的分布影响很小,炉中心下部区域的物料所受的法向力较大;得到了3种软熔区域形状下,气化炉内空隙度分布平均数值;倒“V”型软熔区域结构可使气流分布均匀、稳定,利于气化炉生产实践。     

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)。     

高炉上部煤气流调剂影响研究

利用数值模拟对煤气流的流场及温度场进行了计算.根据高炉不同部位的煤气流速分布,分析得出炉料分布对中上部煤气流分布和软熔带形状有决定作用,而鼓风制度可快速改变下部煤气流分布,并结合实际高炉中的现象及操作讨论了炉料分布的重要性.结果表明:在高炉生产中,有一个合理的布料制度是高炉操作的关键,径向煤气流分布受炉料透气性分布影响很大,初始煤气流对其影响较小,下部煤气流分布信息很难在上部反应.     

COREX 3000竖炉布料的离散元模型

 竖炉内煤气流的分布主宰着其内温度分布、煤气利用率和金属化率的高低,其上部调节方式仅有布料模式。通过引入离散颗粒动力学理论,基于经典牛顿力学和颗粒碰撞软球模型建立了针对COREX 3000竖炉布料过程的离散元数值模拟模型,模型直观可视化再现装料过程,可定量获得料流轨迹、炉料落点及形成料堆的过程。应用模型进一步分析混装2种不同粒径颗粒,获得了炉料运动及形成的料堆过程,发现混装布料过程粒度偏析严重。建立的模型可为寻找和优化合理的布料模式提供重要研究基础。     

布料模式对COREX预还原竖炉煤气流分布的影响

布料模式决定了炉料的空隙度,而炉料的空隙度分布决定了煤气流的第2次分布。采用三维竖炉数学模型,考察了单环布料情况下,挡位分别在竖炉炉顶直径的0.0、0.8、1.6、2.0、2.4、2.8 m时竖炉内煤气压差和煤气流的变化情况。结果表明：布料过程在料面上发生的炉料粒度偏析对煤气流分布的影响很大,料堆尖处煤气流速很低。随着布料档位外移,竖炉整体压差和围管压差呈现增加的趋势,而反窜煤气比例呈现先微弱降低后迅速增加的趋势,拐点出现在2.0 m布料档位。竖炉炉料布料方式对煤气流有再分配的作用,较为适宜的布料档位为1.6 m,不宜超过2.0 m。     

借助边缘环布碎焦和中心加焦控制高炉内气流分布

分析了高炉边缘环布碎焦和中心加焦对气流分布的控制作用。中心加焦可促进中心气流发展，减轻煤气对炉墙的冲刷；环布碎焦可有效隔热且避免矿石结炉墙。此两项措施并用可使高炉内气流分布合理，侵蚀减缓，结果消除、热损失减少，有利于节能。     

高炉中心加焦对气流分布及煤气利用的影响

中心加焦可以减小中心区域的矿焦比,增加中心气流强度,形成倒V形软熔带,提高料柱的透气性;由于中心气流中CO含量高,焦炭的溶损少,颗粒进入炉缸时保持较大的粒度,提高死焦堆的透气透液性。中心加焦对高炉操作有很多积极作用,但中心加焦也会减小中心气流的利用率,提高燃料比。当中心加焦过量时,高炉内的气流分布出现异常,因此需要研究合理的中心加焦量以及中心加焦方式。利用Ergun公式,对不同中心加焦量条件下,高炉内的煤气分布、压差变化等参数进行计算,并根据煤气分布情况简单计算了中心加焦对高炉内煤气利用率的影响。根据计算分析结果,对高炉中心加焦量及中心加焦方式进行讨论。研究结果可以为实际高炉中心加焦操作提供理论参考。     

Mathematical Simulation of Burden Distribution in COREX Melter Gasifier by Discrete Element Method

 COREX process is one of the earliest industrialized smelting reduction ironmaking technology. A numerical simulation model based on discrete element method (DEM) has been developed to analyze the burden distribution in the melter gasifier of COREX process. The DEM considering the collisions between particles can directly reproduce the charging process. The burden trajectory, the location and the burden surface profile are analyzed in melter gasifier with a mixing charging of coal and direct reduction iron (DRI) at the same time. Considering the porosity of packed bed has an important effect on the gas flow distribution of melter gasifier, a method to calculate porosity has been proposed. The distribution of DRI and coal and the porosity in the radial direction are given under different charging patterns, which is necessary to judge the gas flow distribution and provide base data for further researching the melter gasifier for the next work in the future. The research results can be used to guide the operation of adjusting charging and provide important basis for optimizing the charging patterns in order to obtain the reasonable gas distribution.     

熔融气化炉风口回旋区冶炼特征的数值模拟研究

相比于高炉风口喷吹富氧热风,熔融气化炉风口采用常温纯氧,使得炉内质量、动量、热量的传输以及煤气流分布等冶炼特征与高炉存在较大差异.通过建立熔融气化炉风口回旋区二维数学模型,系统考察熔融气化炉风口回旋区内速度分布、温度分布及气体组分分布的冶炼特征.结果表明:在气固相热交换及焦炭 (或块煤形成的半焦) 燃烧反应的综合作用下,熔融气化炉风口回旋区内气体温度迅速升高至3 500 K以上;此外,风口前端存在小规模的气体循环流动现象,故风口前端扩孔破损现象严重,进而导致非计划休风率较高;为减少此类休风现象,可适当额外喷吹富氢燃料性气体 (天然气、焦炉煤气),不仅能降低风口回旋区内气体温度,更可替代部分固体燃料,并充分发挥其中H₂的高温还原优势,提升熔融气化炉冶炼效率.      

The Burden Structure and Its Consumption in the Melter Gasifier of the Corex Process

A major advancement in the Corex ironmaking process is the usage of lump coal considering the shortage of coking coal resources worldwide. However, the burden similar to that of the blast furnace is still essential for the enlarged melter gasifier. The notable difference is that the burden of the melter gasifier is composed of char formed from lump coal with a small amount of coke. The burden structure of the melter gasifier was investigated by the tuyere probing while the plant was shut down at different operating conditions. The specimens representing the different positions of lump zone, cohesive zone, and dripping zone were analyzed by means of coke/char size distribution and X-ray diffraction (XRD) for the degree of graphitization of coke. A chemical analysis of metal composition has also been performed to get a better understanding of the final reduction in the melter gasifier. The burden structure is supposed to be divided into three zones: active zone, outer of deadman, and deadman core, where coke/char was consumed differently. Based on these analyses, some technical advice to improve the Corex operation is given.     

COREX熔融气化炉Rist操作线的建立和应用

考虑了块煤在熔融气化炉上部挥发分的析出和采用部分氧气燃烧析出挥发分中的焦油和碳氢化合物这一特点,利用改进的Rist操作线原理,建立了熔融气化炉操作线图,直观地体现了不同因素对炼铁过程能耗的影响.讨论了COREX熔融气化炉内上部吹氧燃烧焦油和碳氢化合物后操作线的变化,对比了加入不同块煤和半焦对上部吹氧量、能耗的影响,分析了将块煤中挥发分脱除后以半焦的形式加入炉内,熔融气化炉上部煤气氧化度、温度和煤气量的变化,以及对能耗的影响.      

柳钢4号2 000 m3高炉炉役后期布料制度探索实践

阐述了柳钢4号2 000 m3高炉布料方式的特点。为了解决原燃料质量一般和后期炉役护炉生产条件下炉况长期稳定顺行的问题,4号高炉采用大角度、大角差结合中心加焦布料方式,其核心要点是适当压制边沿气流,发展中心气流。柳钢4号高炉生产实践表明,采用大角度、大角差结合中心加焦布料方式,边沿汽流相对较重,边沿十字测温温度在150 ℃以下,但是由于中心加焦的作用,中心煤气流较旺盛,高炉顺行状态良好。     

Influence of Burden Distribution on Temperature Distribution in COREX Melter Gasifier

 The temperature distribution of COREX melter gasifier was studied by using a two-dimensional 1/30 scale thermal dynamic model. A set of operating conditions, such as radial distribution of direct reduction iron (DRI) to lump coal and coke volume ratio, coke charging location, coke charging amount and coke size, were taken into account. The results show that the temperature near the wall region decreases with the decrease of the radial distribution of DRI to lump coal and coke volume ratio. The temperature with central coke charging is higher than that without central coke column. Furthermore, the temperature significantly increases with the increase of central coke charging amount. With the increase of intermediate coke charging amount, the temperature near the wall region decreases while the temperature in the intermediate region increases. The temperature increases with the increase of coke size whether charging central coke or intermediate coke.     

COREX熔化气化炉区域模型及其理论燃烧温度

把熔化气化炉划分为炉缸区、风口区、填充床、流化床和自由空间5个区域。在已开发的COREX工艺整体静态模型的基础上,对各区域分别建立了物料平衡热平衡模型并联立求解。根据各区域内的物理化学进程设定各区域间边界的条件,模型计算可给出熔化气化炉内各区域的能量分布和物料流状况。利用区域模型还可计算喷煤对理论燃烧温度、炉缸渣铁温度、煤气量等的影响。     

Blast furnace circumferential process symmetry: effect of flow distribution in hot blast systems

Abstract

Solid particle flow patterns in the moving bed zone of a melter/gasifier were studied using discrete element method (DEM). Interparticle forces were calculated using the Hertz–Mindlin no slip contact model. The simulation results of the solid particle flow patterns agree well with the experimental results exhibited by tracer particles. The solid particle flow pattern and descending velocity were studied, as well as the effect of the discharge rate of solid particles in the raceway on solid particle flow pattern in the moving bed.

Results show that the moving bed could be divided into four subdomains based on the velocity of solid particles. A stagnation zone with semielliptic geometry is formed at the central bottom of the moving bed during drainage of solid particles. Furthermore, the simulated results of compressive force among solid particles in the moving bed zone indicate that the deadman zone undergoes a high degree of compressive force, especially at the centre of the gasifier. This finding implies that more compressive force resistant solid material should be placed at the centre zone by manipulating solid particles fed into the melter/gasifier.