共查询到17条相似文献,搜索用时 203 毫秒
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以FLUENT软件为计算工具,采用Euler-Lagrange方法模拟固废焚烧系统烟气急冷塔内气液两相流动过程.气相用标准k-ε湍流模型描述.喷淋浆滴用颗粒轨道模型描述.同时在烟气急冷塔内建立半干法脱硫的数学模型.脱硫反应模型全面考虑了急冷塔内恒速干燥阶段、降速干燥阶段、干燥后阶段,采用双膜理论模型来模拟干燥阶段的脱硫反应过程,采用未反应核心收缩模型采模拟干燥后阶段的脱硫反应过程.模拟结果与实际经验值吻合较好.利用此模型可以对实际工程的相关参教进行优化计算,能够提供一定的指导和参考作用. 相似文献
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介绍了喷水增湿活化脱硫反应器中的气相流动、水滴运动和蒸发、水滴与脱硫剂颗粒碰撞及碰撞后形成的浆滴过程的模型研究方法和数值计算结果,其中,气相湍流模型采用κ-ε双方程模型进行数值模拟,水滴运动和蒸发模型分别采用随机轨道模型和经Ranz—Mashall修正的水滴蒸发模型,水滴与脱硫剂颗粒的碰撞则采用惯性沉聚模型进行。数值计算结果表明,活化反应器内的气相速度场已经进入紊流充分发展区,喷入反应器的雾化水滴及形成的浆滴在不长的一段距离内即蒸发完全,脱硫剂捕集主要发生在雾化水滴喷入位置后的一段距离内,此后捕集效率迅速降低。 相似文献
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以垃圾焚烧厂脱酸塔为模拟对象,建立了脱酸塔气固液之间的传质模型及化学反应模型,对旋转产生的喷雾建立了浆滴模型以分析其蒸发和传质过程,通过对已有实验模型与脱酸塔实际运行结果进行对比,验证了所建化学反应模型和浆滴模型的准确性,模拟了某垃圾焚烧厂脱酸塔的内流特征,得到其压力、温度、速度和酸性气体质量分数等参数的分布及脱除率。结果表明:脱酸塔中轴线上部是脱酸反应主要发生部位;由于烟气回流区的作用,部分没有蒸发完全的浆滴被吹向脱酸塔壁面,容易造成脱酸塔壁面的结渣和腐蚀,导致脱酸塔壁面所受的热应力增大,不利于脱酸塔长期稳定运行;浆滴进入脱酸塔5s内完全蒸发。 相似文献
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利用以工业石灰、粉煤灰和添加剂制备的高活性吸收剂在循环流化床上进行了脱硫实验.通过对床内流场和温度场的分析,建立了气力输送状态下循环流化床物理模型.在此基础上,针对床内喷水增湿活化脱硫时吸收剂的三种不同物态:新鲜干燥颗粒、干燥再循环颗粒、含水颗粒,分别建立了与之对应的表面覆盖模型、气固反应模型、浆滴脱硫模型,并总结出气力输送状态下利用高活性吸收剂的循环流化床总脱硫模型.同时通过实验数据对模型进行了校核,校核结果误差在5.5%以内,较以往模型具有更高的精度.图8表1参18 相似文献
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大型燃煤电站锅炉脱硫塔脱硫效率的数值模拟 总被引:2,自引:2,他引:0
利用双膜理论建立了脱硫过程的理论模型,以国内某百万千瓦级火电机组烟气脱硫系统的脱硫塔为例进行了数值计算,分析了浆液pH值、入口SO2质量浓度、液气比、锅炉负荷、浆液液滴粒径、喷淋层投运方式及吸收塔塔径等参数对脱硫效率的影响,并与工程实际数据进行了比较.结果表明:数值计算结果与生产现场运行数据比较吻合;各喷淋层的脱硫能力不一样,第3喷淋层的脱硫能力最强,第2喷淋层和第1喷淋层的脱硫能力次之;脱硫效率随浆液pH值和液气比的增大而提高,随入口SO2质量浓度、锅炉负荷和浆液液滴粒径的增加而逐渐降低. 相似文献
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M.K. Akbar 《International Journal of Heat and Mass Transfer》2003,46(24):4561-4571
The absorption of a gaseous species by a slurry droplet containing reactive and sparingly soluble microparticles is numerically simulated. The problem studied is relevant to spray flue gas desulfurization systems and the objective of this study was to elucidate the effect of the reactive solid particles on the parameters that determine the mass transfer processes. Spherical droplets with internal circulation similar to Hill’s vortex flow were considered. Quasi-steady conservation equations representing the absorbed and dissolved reactant species and equations representing the dissolution of particles were numerically solved using the droplet internal circulation streamline as a coordinate. Second-order and instantaneous chemical reactions were both addressed. The results show that the reactant microparticles enhance the absorption rate by increasing the gradient of the absorbed species beneath the droplet surface. The relative effect of solid particles depends strongly on the droplet internal circulation and diminishes as stronger recirculation occurs. 相似文献
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This paper presents a new liquid-screen gas–liquid two-phase flow pattern with discarded carbide slag as the liquid sorbent of sulfur dioxide (SO2) in a wet flue gas desulfurization (WFGD) system. On the basis of experimental data, the correlations of the desulfurization efficiency with flue gas flow rate, slurry flow rate, pH value of slurry and liquid–gas ratio were investigated. A non-dimensional empirical model was developed which correlates the mass transfer coefficient with the liquid Reynolds number, gas Reynolds number and liquid–gas ratio (L/G) based on the available experimental data. The kinetic reaction between the SO2 and the carbide slag depends on the pressure distribution in this desulfurizing tower, gas liquid flow field, flue gas component, pH value of slurry and liquid–gas ratio mainly. The transient gas–liquid mass transfer involving with chemical reaction was quantified by measuring the inlet and outlet SO2 concentrations of flue gas as well as the characteristics of the liquid-screen two-phase flow. The mass transfer model provides a necessary quantitative understanding of the hydration kinetics of sulfur dioxide in the liquid-screen flue gas desulfurization system using discarded carbide slag which is essential for the practical application. 相似文献
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A droplet size dependent multiphase mixture model is developed in this paper, and the droplet size in the gas channel can be considered as a parameter in this multiphase mixture model, which includes the effect of gas diffusion layer (GDL) properties and the gas drag function and cannot be considered in the commonly used multiphase mixture model in the references. The three-dimensional two phase and non-isothermal simulation of the PEMFCs with a straight flow field is performed. The effect of droplet size on the liquid remove, the effect of liquid water on the heat transfer and the effect of gas flow pattern on the heat and mass transfer are mainly investigated. The simulation results show that the large droplet is hard to be dragged by the gas, so it produces large water saturation. The results of the heat transfer show that the liquid water hinders the heat transfer in the GDL and catalyst layer, so it produces the large relative high temperature area, and there are large temperature difference and water saturation in the PEMFCs operated with coflow pattern compared with counter flow pattern. 相似文献