基于宽带k分布模型的气体重叠谱带发射率计算与分析

Calculation and Analysis of Gas Overlapping Band Emissivity Based on Wide Band k Distribution Model

针对富氧燃烧方式下烟气中高浓度CO2和H2O混合气体发射率的计算难题,以宽带k分布模型为基础,建立了混合气体2.7μm重叠谱带改进模型。以某富氧燃煤电站锅炉为例,采用改进模型计算了混合气体在不同温度、不同路径长度下的发射率,并与逐线计算和2.7μm重叠谱带差值模型进行了对比分析。结果表明:在炉内主要烟温区,该改进模型与逐线计算结果吻合较好,与差值模型相比,计算精度有所提高,模型更为简单;混合气体发射率随路径长度的增大呈递增趋势,但变化幅度逐渐减小。

Based on the wide-band k distribution model, an improved model of 2.7 μm over- lapping band was developed to calculate the emissivity of carbon dioxide and water vapor gas mixtures under oxy-combustion mode. An oxy-combustion boiler was taken as an example, the emissivity of gas mixtures under different temperatures and path lengths were calculated using improved model. Calculated results were compared with line-by-line calculation and in- terpolated model of 2.7μm overlapping band. It is shown that the results obtained by the im- proved model are in agreement with line-by-line results in the main temperature zones. Com- pared with the interpolated model, the improved model is more accurate and simple. The re- sults also show that the emissivity of the gas mixtures increase with the rising of path lengths, but the variation gradually slows down.