共查询到18条相似文献,搜索用时 250 毫秒
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运用流体模拟软件Fluent和Matlab分别对碳素煅烧回转窑内气体空间和物料料层内的传热过程进行了研究,预测了窑内烟气、窑内壁和料层的温度分布。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;二、三次冷空气的引入均会使窑内烟气温度明显下降,但对料层温度影响不显著。将窑外壁的计算结果与其实际测试结果进行了比较,两者吻合较好,说明该模拟方法的适用性,从而为碳素回转窑的优化设计和经济运行提供了指导和依据。 相似文献
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回转窑传热模型与数值模拟 总被引:18,自引:0,他引:18
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。 相似文献
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以某炭素厂φ2.3 m×55 m的回转窑作为研究对象,运用流体模拟软件Fluent 和Matlab 分别对回转窑内气体空间和物料料层内的传热过程进行了模拟,预测了回转窑参数如二、三次供风量和位置、翻料装置、物料填充率、窑转速等对窑内温度场的影响。结果表明合理布置二、三次风供风量和位置、设定翻料装置的尺寸和个数能够有效提高窑内温度,进而提高煅后焦质量;合理增加物料填充率和提高窑转速既能够提高回转窑产能,又能够保证煅后焦质量。 相似文献
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我厂3台Φ3.5×145m湿法回转窑烧成带窑衬寿命一般为200~300天左右,1993年3#窑烧成带窑衬寿命达到312天,创国内湿法窑最好记录,几个工艺带窑衬的使用寿命基本上同步。本文结合实践提出影响烧成带窑衬使用寿命和窑衬保护方面的、见解。 1 窑衬侵蚀机理 无论是湿法窑,还是于法和半干法回转窑,在熟料的煅烧过程中,由于窑内气体温度比物料温度高得多,窑每旋转一圈窑衬表面受到周期性的热冲击,温度变化幅度为150 相似文献
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石油焦煅烧质量的控制与提高 总被引:3,自引:1,他引:3
通过调整窑头窑尾负压,达到控制窑尾温度和干燥带、预热带、缎烧带长度的目的。同时控制回转窑的煅前投料量和大窑转速,亦可在一定程度上达到减少煅后石油焦中流态化焦的产生,降低石油焦在煅烧过程中的二次结焦量,从而改善煅烧石油焦的实物质量和内部结构,为进一步稳定提高炭—石墨制品的实物质量和内部结构奠定基础。 相似文献
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In the present study, an improved numerical heat transfer model has been developed for a rotary kiln used for drying and preheating of wet iron ore. The present model includes radiation exchange among hot gas, refractory wall and the solid surface, transient conduction in the refractory wall, and mass and energy balances of the hot gas and the solids. The contribution of gas convection has also been taken into account in terms of a fraction of the radiative heat transfer to the inner refractory wall and the solid surface. The computer results show that the present model can predict the length of the kiln as well as axial solid and gas temperature distributions with reasonably good accuracy. A detailed parametric study reveals that a good design of a rotary kiln requires medium gas flow rate, small angle of inclination and low rotational speed of the kiln. 相似文献
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Young Han Kim 《Korean Journal of Chemical Engineering》2012,29(12):1674-1679
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. 相似文献
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In this first of a two-article series, a one-dimensional steady-state mathematical model has been developed to simulate the process of calcination of petroleum coke in a rotary kiln. The model is made of 14 ordinary differential equations describing the conservation of energy and mass in the coke bed and in the freeboard gas. They are solved simultaneously using the 4th-order Adams-Moulton numerical method. The model calculates the various temperature profiles and the mass concentration profiles of the different chemical species. Special emphasis is laid on the usual process variables such as calcined coke recovery factor, and the loss of coke in the form of dust exhausted with the gas. In the second article, a complete simulation will be presented and the results discussed. Also, a comparison with existing models will be made. 相似文献
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钛白粉煅烧转窑尾气的高湿、高硫、高酸露点的特性使得转窑尾气余热利用过程中换热器寿命不理想。在总结已有尾气余热利用方式存在问题的基础上,提出了一种长寿命、易维护的套管式热管余热利用装置,该装置由彼此分离的换热套管通过弯头、法兰连接成为整体,尾气垂直横掠双层套管段,与高硫、高湿的尾气通过相变介质的相变完成热量由尾气向取热介质的转移,产生钛白粉生产工艺所急需的蒸汽,双层管的相变换热套管对比单层管的重力热管换热器寿命明显延长;连接换热套管的单层管弯头不与高湿、高硫尾气换热,大大减轻了尾气对单层管的腐蚀。换热器应用在3.6 m×58 m的钛白粉煅烧窑上,每年可以产生0.9 MPa的水蒸气1.12万t,为企业带来可观的经济效益。 相似文献