Model and Simulation of a Ported Kiln for Iron Oxide Pellet Induration

A mathematical model of a ported kiln for iron oxide pelletizing was developed to simulate the effects of under‐bed air injection on kiln fuel requirements and magnetite oxidation. A tanks‐in‐series model was used to set up material and energy balance equations for countercurrent flow of solids and gas through the kiln. The diffusion‐limited, shrinking core model was used for the magnetite oxidation reaction kinetics. The port air distribution in the model was adjusted by global optimization to minimize the fuel requirement. The simulation results show that magnetite oxidation may be completed in the kiln with significant fuel savings.     

回转窑中心线在线监测方法

回转窑中心线变化一般是缓慢的,窑故障的发生也具有隐蔽性和不确定性,当故障严重时会影响回转窑的正常生产,许多企业通常到回转窑运转出现故障后才发现.本文提出一种回转窑中心线的在线监测方法,此方法在检测得到窑中心线的基础上,通过监测回转窑轮带表面三点的位置,实现回转窑中心线的在线监测,使企业自己能够及时获取回转窑中心线的运行...     

Experimental and theoretical investigation on unburned coal char burnout in a pilot-scale rotary kiln

Oxidation reactivity studies are imperative for improving carbon re-burn technologies and valuing the heat content of unburned carbon within coal combustion ashes. Non-isothermal, thermal gravimetric analysis (TGA) was used to examine the oxidation kinetics of unburned carbon in coal combustion fly ashes having different particle size distributions; TGA results were related to combustion efficiencies as measured in a bench-scale rotary kiln. The activation energy and pre-exponential factor were determined for the chemically-controlled reaction regime; the transition temperatures between chemically-controlled and partially diffusion-controlled combustion regimes were obtained for unburned carbon particles of different sizes. After the oxidation reaction rates were evaluated, the residence time distribution (RTD) of fly ashes in the rotary kiln were experimentally measured and the mean residence times related to process parameters, including the rotating velocity and kiln inclination. By comparing these results with an advective-dispersive model, the axial dispersion coefficient of fly ashes was determined. The reaction rates obtained by thermal analyses and the RTDs were used to predict combustion efficiencies within the kiln and oxidation conditions of unburned carbon using various processing options.     

铬铁矿回转窑氧体积分数分布的模拟仿真

针对铬铁矿氧化焙烧过程中氧对窑内温度分布的影响和对提高铬氧化率的重要作用,利用数值仿真（CFD） 方法研究了回转窑内氧体积分数的分布情况。主要分析了空气焙烧过程中回转窑内氧体积分数分布的一般规律,讨论了空气过剩系数和一、二次风中氧体积分数的变化对焙烧温度、氧体积分数的影响。结果表明,空气过剩系数为1.7时,窑内壁附近氧体积分数沿窑长方向不断减小,在高温氧化带之后窑内氧分布趋于均匀,窑尾烟气中氧体积分数约为7.5%;空气过剩系数为1.7左右时较为合理;随着一、二次风中氧体积分数的增加,窑内温度先是明显升高,后略有降低。     

Mathematical modelling of rotary cement kilns by the zone method

A steady state mathematical model of rotary cement kilns based on the fundamental principles of the physical and chemical processes within the kiln was developed. The zone method of analysis was utilized together with the Monte Carlo method to simulate the radiative interchange within the kiln. Steady state energy balances including the chemical reaction terms for each zone were solved simultaneously to give temperature distributions in gas and solid charge, and composition distribution in solid charge. Predictions of the mathematical model were compared with dry process and wet process rotary cement kiln data.     

回转窑传热模型与数值模拟

对回转窑内传热过程进行了分析 ,在已有研究基础上归纳了各项换热系数的关联式 ,尤其结合热渗透模型完善了回转壁面与料床之间传热机制的研究 ,并提出通用的计算关联式。进而提出了内热式炉型的一维轴向传热模型 ,并根据已发表的试验数据验证了该模型和各换热系数的适用性。计算表明在窑内低温段 ,物料的受热主要来自其覆盖的回转壁面对其加热 ;而在高温段 ,气体的辐射热量成为加热料床的主要热源。此外 ,由物料进口端沿轴向窑壁散热增大 ,在窑内高温段窑壁的散热甚至高于物料吸热量 ,因此在回转反应器的设计中应充分考虑窑壁散热造成的热效率降低并采取相应措施。     

窑法磷酸生产的旋窑制气试验研究

以清平和中低品位金河磷矿为原料，研究了窑法制磷酸磷矿炭热还原过程的规律。在小型旋窑内进行了旋窑制气试验，弄清了在同一旋窑内磷矿还原与磷蒸气氧化时，分别要求还原和氧化气 氛的矛盾，以及型料熔结产生窑圈的实质。找到了解决的途径和方法，考查了旋窑制气工艺，测定了有关工艺和设备设计参数。     

浅析红土镍矿回转窑整体窑炉技术的施工与应用

回转窑内衬可用耐火砖砌筑,也可选用其它的耐火材料做内衬,但是近几年,随着施工方法的改进及耐火材料研发的突破,回转窑内衬开始选用整体窑炉技术。将回转窑内衬的材料选用及施工工艺相结合,此方法可以提高回转窑产能,减少热损失,取得了高效节能降耗的显著效果。     

氧化铝回转窑烧成带火焰图像识别系统

针对氧化铝回转窑烧成带工况变化复杂,与产品质量指标密切相关的关键过程变量无法实现在线连续检测的难题,模拟传统的人工看火操作过程,提出利用图像处理与模式分类技术对与回转窑工业过程自动控制密切相关的烧成带状态进行自动识别的方法。组建了系统的硬件、软件平台,设计并开发了基于混合数据特征识别的氧化铝回转窑烧成带工况识别软件。该系统成功应用于国内某氧化铝厂,为回转窑的优化控制提供了重要的辅助决策信息。     

石油焦煅烧回转窑综合传热过程数值模拟

研究了石油焦煅烧回转窑内的物理和化学反应过程对回转窑内传热过程的影响,并在对回转窑内的物料输送过程、传质过程和传热过程具体分析的基础上,建立了石油焦煅烧回转窑的综合传热数学模型. 应用数值计算方法对传热数学模型进行计算求解,预测了窑内气体、物料和窑壁内外表面的轴向温度分布. 结果表明,窑内的高温区域主要集中在挥发分大量燃烧的区段上,三次风的注入会引起窑内气相温度的明显下降,但不会造成料床温度的明显变化;在物料与气体、窑内壁之间热交换过程中,物料与被覆盖的窑内壁表面之间的对流换热和气体与料床表面间的辐射换热为主要的传热机制. 计算预测的结果与测量数据在规律上和数值上都能较好地符合,从而为石油焦煅烧回转窑的优化设计和经济运行提供了指导和依据.     

基于有限元分析的大型回转窑轮带设计

轮带是回转窑上最重要的结构件之一,其主要参数（轮带外径,轮带宽度和轮带截面高度等）的优化设计和合理确定直接影响窑的安全稳定运行。详细介绍了国内外大型回转窑轮带的结构形式、轮带材料的选取及热处理方式和轮带外形参数设计的发展趋势。同时,运用ANSYS软件对土耳其AS水泥厂中5．6m×87m回转窑轮带进行了设计计算实例示范,重点介绍了其分析模型的建立、单元设置与网格划分、边界条件及荷载的施加等设计步骤。     

燃煤式冶金活性石灰回转窑烘窑方案

众所周知,烘窑的好坏直接关系到窑炉正常使用寿命。好的烘窑方案不仅可以缩短烘窑周期,而且可以节约大量的资金。河北龙凤山炉料有限责任公司400t·d^-1活性石灰回转窑烘窑取得了成功,从烘窑到达到设计生产能力为1个月。     

Rotary cement kiln coating estimator: Integrated modelling of kiln with shell temperature measurement

Coating thickness protection in the burning zone of a rotary cement kiln during operation is important from the viewpoint of the kiln productivity. In this paper, an integrated model is presented to estimate the coating thickness in the burning zone of a rotary cement kiln by using measured process variables and scanned shell temperature. The model can simulate the variations of the system, thus the impact of different process variables and environmental conditions on the coating thickness can be analysed. The presented steady‐state model derived from heat and mass balance equations uses a plug flame model for simulation of gas and/or fuel oil burning. Moreover, the heat transfer value from shell to the outside is improved by a quasi‐dynamic method. Therefore, at first, the model predicts the inside temperature profile along the kiln, then by considering two resistant nodes between temperatures of the inside and outside, the latter measured by shell scanner, it estimates the formed coating thickness in the burning zone. The estimation of the model was studied for three measured data sets taken from a modern commercial cement kiln. The results confirm that the average absolute error for estimating the coating thickness for the cases 1, 2, and 3 are 3.26, 2.82, and 2.21 cm, respectively.     

基于灰色关联分析和层次分析法的水泥回转窑用煤质量指标综合评价

本文结合现行国家标准和行业规范，确定水泥回转窑用煤综合评价指标体系和评价指标划分方案，建立基于灰色关联分析和层次分析法（AHP）的水泥回转窑用煤质量等级评价模型，以集团内6家公司进厂煤炭进行综合评价研究。该方法不仅能够反映不同级别样本之间的差别，而且还能反映同一级别的样本质量优劣，可用于不同公司或不同供应商之间的煤炭质量综合评价对比，为回转窑用煤使用价值最大化，合理确定进厂验收指标提供决策依据。     

水泥生产中SP窑烧成系统的组合模型与分析

本文阐述了热平衡分析法的缺点与拥分析的科学性，提出了用于分析的ＳＰ型水泥回转窑烧成系统的组合模型．它可以科学地、准确地找出体系中主要薄弱环节，使节能技改措施更有针对性。     

回转窑轮带间隙数据跟踪与调整方法

回转窑筒体与轮带间隙大小直接影响着筒体的变形量,本文通过分析回转窑椭圆度、轮带间隙、滑移量间相应关系,筒体椭圆度对窑衬压力的影响及轮带间隙的跟踪与控制方法,得出热、冷态的跟踪与调整可提高回转窑耐火材料使用周期和运转率。     

铜陵海螺5 000t/d国产化示范线回转窑技术指标设计与控制

在收集和整理大量大型现代干法预分解窑的基础上，采用统计分析的方法获得适合现代干法预分解窑的统计核算公式和回转窑工艺参数确定体系，并在铜陵海螺5000t/d生产线配套回转窑工艺参数确定中得到实际应用，实践证明，采用该方法建立的回转窑规格确定与能力核算体系用于现代干法预分解窑的设计是合适的，所设计的回转窑已达到设计指标，部分技术指标已达到当前世界先进水平。     

Development of process model of a rotary kiln for volatile organic compound recovery from coconut shell

The volatile organic compounds (VOCs) contained in coconut shell are wasted in the carbonization process of coconut shell due to the difficulty of recovery. The VOCs recovery is useful and necessary, because the VOCs are a sustainable energy source, and the recovery is an economically feasible project. A simulation model of the VOC recovery process from coconut shell using a rotary kiln is developed to investigate the process characteristics and the role of model parameters. The model includes the energy and material balances for the processing solid and the gas in the kiln. The validity of the proposed model is partially examined with the experimental results. From the simulation, the dominant heat transfer mechanism is determined for the understanding of the process operation. In addition, the optimal operating conditions of the rotary kiln are found for the use in the design and control of the kiln.     

垫板调整对窑中心线的影响

本文主要分析回转窑在长周期运转后中心线产生偏差,针对托轮表面存在大量凹坑和裂纹,常规进行托轮调整风险大的情况,提出新的调整办法,介绍笔者团队利用垫板调整的方法对窑中心线进行调整的案例,为回转窑技术人员提供参考建议。     

回转窑筒体轴向弯曲变形和表面圆柱变形动态检测方法

回转窑的筒体轴向弯曲变形和表面圆柱变形对回转窑的稳定运行有着重要的影响,对窑筒体这二种变形的准确检测将可以判断回转窑的运行状态。文章阐述了测量窑轴向弯曲变形和表面圆柱变形测量的意义,分析了引起回转窑筒体轴向弯曲变形和表面圆柱变形的原因,介绍了一种可以在动态条件下测量窑筒体轴向弯曲变形和表面圆柱变形的方法,能准确测量窑筒体轴向弯曲变形和表面圆柱变形的大小。