A temperature-history based model for the sticking probability of impacting pulverized coal ash particles
A temperature-history based model for the sticking probability of impacting pulverized coal ash particles
复制标题
DOI：
10.1016/j.fuproc.2015.08.039
复制
发表时间：
2016
影响因子：
7.5
通讯作者：
A. Brink;D. Lindberg;M. Hupa;M. E. Tejada;M. Paneru;J. Maier;G. Scheffknecht;A. Pranzitelli;M. Pourkashanian
中科院分区：
文献类型：
--
作者：
A. Brink;D. Lindberg;M. Hupa;M. E. Tejada;M. Paneru;J. Maier;G. Scheffknecht;A. Pranzitelli;M. Pourkashanian
几项研究表明，在煤的氧气燃烧和空气燃烧中获得的沉积物之间的差异主要是由于火焰温度的差异。因此，不考虑飞行历史的存款率预测不太可能成功。本文建立了一个基于惯性碰撞机理的煤粉全氧燃烧和空气燃烧中存款倾向性预测模型，并进行了试验。该模型建立在使用粘度作为粘附概率的指标的基础上。在假定热力学平衡的情况下，计算了煤灰中无定形渣相的组成和数量。此外，假定灰颗粒经历的最高温度将控制无定形炉渣相的组成和量。当灰颗粒撞击时，使用该熔融组合物的粘度来估计粘附的可能性，但是使用撞击时刻的颗粒温度的温度。在平衡计算中，假设没有与气相的物质交换。这一假设是基于X射线衍射（XRD）的煤灰样品在实验室规模的燃烧器模拟富氧燃料和空气燃烧的调查。XRD分析表明，气体气氛对煤灰的矿物学没有明显影响。灰颗粒粘附的概率作为最大经历温度和冲击温度的函数进行了评估，为三种煤。对于其中一种煤，在300 kWth试验设备上进行了颗粒存款的CFD研究。
Several investigations have shown that the differences between deposits obtained in oxy-firing and air-firing of coal mainly are due to differences in the flame temperature. Consequently, deposit rate predictions not taking the in-flight history into account are unlikely to be successful. In this paper, a model for predicting the deposit formation propensity of pulverized coal in oxy-fuel and air combustion due to the inertial impaction mechanism is developed and tested. The model builds on the use of viscosity as an indicator of the sticking probability. The composition and amount of the amorphous slag phase in the coal ash are calculated assuming thermodynamic equilibrium. Further, it is assumed that the maximum temperature the ash particle has experienced will control the composition and amount of the amorphous slag phase. As the ash particle impacts the probability to stick is estimated using the viscosity of this melt composition, but with the temperature of particle temperature at the moment of impaction. In the equilibrium calculation no material exchange with the gas phase is assumed. This assumption is based on X-ray diffraction (XRD) investigations of coal ash samples produced in a lab-scale burner simulating oxy-fuel and air combustion. The XRD showed that there was no significant impact on the mineralogy of the coal ash caused by the gas atmosphere. The probability of an ash particle to stick as a function of maximum experienced temperature and impact temperature was evaluated for three coals. For one of the coals a CFD study on particle deposit is done for a 300 kWthtest facility.