Abstract Ash particle radiation typically contributes considerably to the total heat absorbed by steam heat exchangers found in pulverized fuel-fired energy systems. As particle concentrations increase due to higher ash content in the parent fuel, radiation scattering should be considered. Furthermore, the relative size of the particles compared to thermal radiation wavelengths also affects the emission, absorption and scattering characteristics. This study presents a refined particle diameter-dependent emissivity and scattering factor model for computational fluid dynamics modelling of heat exchangers located in boilers firing high ash fuels. To demonstrate the impact of the newly proposed model a case study reheater located in an actual boiler, firing high-ash fuel, was studied. The results of the particle radiation property model were also compared to models typically found in the relevant literature. The results show that the new model predicts lower radiation emission when compared to the models reported in literature. This was shown not to be due to increased radiation losses (absorption and scattering) but rather due to reduced particle emission, which in turn is due to the particle diameter-emissivity dependence. The results were also compared to real plant measurements at three different boiler load cases and showed good agreement between calculated and measured steam temperatures.

中文翻译：

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通过工业气体-蒸汽换热器的高灰分气体-颗粒分散流中颗粒辐射特性的增强模型

摘要 灰粒子辐射通常对粉状燃料燃烧能源系统中蒸汽换热器吸收的总热量贡献很大。由于母燃料中较高的灰分含量导致颗粒浓度增加，因此应考虑辐射散射。此外，与热辐射波长相比，颗粒的相对尺寸也会影响发射、吸收和散射特性。本研究提出了一种改进的与粒径相关的发射率和散射因子模型，用于对燃烧高灰分燃料的锅炉中的热交换器进行计算流体动力学建模。为了证明新提出的模型的影响，我们研究了一个位于实际锅炉中、燃烧高灰分燃料的再热器案例研究。粒子辐射特性模型的结果也与相关文献中常见的模型进行了比较。结果表明，与文献报道的模型相比，新模型预测的辐射发射较低。这被证明不是由于辐射损失增加（吸收和散射），而是由于粒子发射减少，这又是由于粒子直径-发射率依赖性。结果还与在三个不同锅炉负载情况下的实际工厂测量值进行了比较，并显示计算出的蒸汽温度和测量的蒸汽温度之间具有良好的一致性。这被证明不是由于辐射损失增加（吸收和散射），而是由于粒子发射减少，这又是由于粒子直径-发射率依赖性。结果还与在三个不同锅炉负载情况下的实际工厂测量值进行了比较，并显示计算出的蒸汽温度和测量的蒸汽温度之间具有良好的一致性。这被证明不是由于辐射损失增加（吸收和散射），而是由于粒子发射减少，这又是由于粒子直径-发射率依赖性。结果还与在三个不同锅炉负载情况下的实际工厂测量值进行了比较，并显示计算出的蒸汽温度和测量的蒸汽温度之间具有良好的一致性。