0.5 MW富氧燃烧煤粉炉循环倍率对辐射传热的影响

Effect of Flue Gas Recycle Ratio on Radiative Heat Transfer in a 0.5 MW Oxy-fuel Combustion Furnace

本文以某0.5 MW富氧燃烧煤粉炉为研究对象,采用改进的气体、颗粒辐射特性模型以及富氧燃烧骨架机理,对煤粉空气燃烧以及不同烟气循环倍率下的富氧燃烧进行了数值模拟,对炉内气流分布、温度分布以及壁面热流进行了详细地分析。研究结果表明,不同燃烧条件下,预测的壁面辐射热流与试验测量值具有很好的一致性;烟气循环倍率对炉内温度以及传热具有很好的调节作用,在本文中,当循环倍率为67%时,富氧燃烧的炉内峰值温度与空气燃烧基本一致,但传热能力增强;当循环倍率为71%时,富氧燃烧的传热量与空气燃烧一致。

In this study, improved gas and particle radiative property models and a skeletal mechanism are used to simulate the pulverized coal combustion, including the air-nombustion and oxy-fuel combustion with different flue gas recycle ratios. Calculations are presented for experiments carried out in the RWEn 0.5 MWth combustion test facility. In-furnace flow patterns, flue gas temperature distribution, and radiative heat transfer are analyzed in detail. The results show that the predicted radiative heat fluxes on the wall are in good agreement with measurements in all cases. The in-furnace temperature and radiative heat transfer are significantly impacted by flue gas recycle ratios. In this study, at flue gas recycle ratio of 67%, the peak temperature in oxy-fuel combustion is similar with that in air-nombustion, but the heat transfer capability is enhanced. When the recycle ratio is 71%,the radiative heat transfer in oxy-fuel combustion can match with that in air-combustion.