空气预热温度对天然气加热炉内温度场和NOx排放的影响

作为一种特殊的炉型形式,天然气加热炉不仅是天然气工业中不可或缺的设备,同时也是天然气运用过程中的主要耗能设备。天然气在一次能源消耗结构中的占比越来越高,对加热炉的不断研究将助力天然气工业朝着节能环保的方向发展。为了研究不同空气预热温度对130kW天然气加热炉内温度场和NOx排放的影响,本文分别采用了DO离散坐标辐射模型和P-1辐射模型、标准k-ε双方程湍流模型、非预混燃烧模型和热力型NOx污染物模型对加热炉内温度场和浓度场进行数值模拟和分析。结果表明:随着空气预热温度的升高,火管内燃烧区域提前,燃烧放热量和对流管束内被加热气体吸热量先增后减,NOx排放浓度不断增加。综合分析后得出燃烧器进口空气的最佳预热温度为400 K,此时燃烧放热量和对流管束吸热量最高,且NOx排放浓度低于国家标准。研究结果为天然气加热炉的实际运行及优化设计提供参考。

Effect of Air Preheating Temperature on Temperature Field and NOx Emission in Natural Gas Heating Furnace

As a special type of furnace,natural gas heating furnace is not only an indispensable equipment in the natural gas industry,but also the main energy-consuming equipment in the process of natural gas application.The proportion of natural gas in primary energy consumption structure is getting higher and higher.The continuous research on heating furnace will help the natural gas industry develop towards energy saving and environmental protection.In order to study the influence of different air preheating temperatures on temperature field and NOx emission in 130kW natural gas heating furnace,discrete coordinate(DO)radiation model and P-1 radiation model,standard k-εtwo-equation turbulence model,non-premixed combustion model and thermodynamic NOx pollutant model are used to numerically simulate and analysis temperature field and concentration field in heating furnace.The results show that with the increase of air preheating temperature,the combustion area in the fire tube is ahead of schedule,the heat released from combustion and the heat absorbed by the heated gas in the convective tube bundle increase first and then decrease,and the concentration of NOx emission increases continuously.After comprehensive analysis,the optimum preheating temperature of the air inlet of the burner is 400 K.At this temperature,the combustion heat release and heat absorption of the convective tube bundle are the highest,and the concentration of NOx emission is lower than the national standard.The research results can provide reference for the actual operation and optimization design of natural gas heating furnace.