燃气锅炉降氮提效改造工程实测
Practical measurement of nitrogen reduction and efficiency improvement of a gas-fired boiler project
摘要：
针对燃气锅炉降氮改造中遇到的回流烟气冷凝腐蚀和对热效率要求高等问题，采用基于排烟冷凝余热深度回收利用的降氮提效及改善锅炉房内空气环境的方案，对北京某燃气供暖锅炉房进行改造。实测表明，当锅炉运行负荷为42%~67%，烟气再循环率为15%~20%，过量空气系数为1.36~1.55时，排烟中NOx含量为11.5~42.7 mg/m3，锅炉系统未发现腐蚀，供暖回水温度为33.3~40.7 ℃，烟温从88~112 ℃降至40~44 ℃，燃气热效率提高8.2%~12.1%，单位容量（700 kW）锅炉回收烟气冷凝水0.88~1.25 t/d，烟气除雾率37%~50%，同时改善了锅炉房内空气品质。2个供暖季耗气量对比结果表明，锅炉房总节气率为14.8%，降氮、提效、节水、除雾，节能和环保效益显著。
Abstract：
In view of the problems of condensation and corrosion of returning flue gas and high thermal efficiency in the nitrogen reduction reform of gas-fired boilers, adopts a low nitrogen and high efficient scheme based on exhaust gas condensing waste heat recovery as well as improving the air environment in boiler room renovation. After the retrofitting, the practical measurement shows that when the flue gas recirculation rate is 15% to 20% and the excess air coefficient is 1.36 to 1.55, the NOx content in the exhaust air is 11.5 to 42.7 mg/m3 in the load range of 42% to 67%. Corrosion is not found in the boiler system. The return water temperature of the primary heating is 33.3 to 40.7 ℃, the flue temperature is reduced from 88-112 ℃to 40-44 ℃, gas utilization thermal efficiency is increased by 8.2% to 12.1%, and the unit capacity (700 kW) boiler recovers 0.88 to 1.25 t/d of the flue gas condensate. The flue gas demisting rate is 37% to 50%, and the air quality in the boiler room is effectively improved. According to the comparison of gas consumption in the two heating seasons, the total gas saving rate of the boiler room is 14.8%, the benefits of nitrogen reduction, efficiency increasing, water saving, defogging, energy saving and environmental protection are significant.
Keywords:gas-fired boiler, nitrogen reduction, flue gas recirculation, flue gas condensation heat, gas utilization thermal efficiency