基于排烟余热深度利用的燃气锅炉低污染排放方案优化
Low pollution emission optimization scheme for gas-fired boiler based on deep utilization of flue gas waste heat
摘要：
针对燃气锅炉排放物氮氧化物含量高、雾气大，降氮改造通常导致锅炉效率降低、烟气回流易造成锅炉腐蚀，为保证锅炉房内空气环境要求需要增加能耗等问题，提出了基于烟气冷凝热能和烟气冷凝水深度回收，排烟余热加热热网水、助燃空气及供暖气流的燃气锅炉低氮排放优化方案。以排烟温度已降低到70 ℃以下、热效率达到95%以上的北京某29 MW燃气供热锅炉增效、降氮、减排和近无烟排放改造工程为例，进行了节能、节水、除雾、降氮等技术经济效益分析。实测结果表明，不同锅炉负荷下，烟气温度从48.6~60 ℃降至37.6~46 ℃，节能5.2%~8.4%，单位容量锅炉（700 kW）回收烟气冷凝水0.68~1.54 t/d，氮氧化物质量浓度降至30 mg/m3以下，烟气除水（雾）率可达66%，节能、节水、环保效果显著。
Abstract：
For the problems of high concentration of nitrogen oxides and fog emission from gas-fired boiler, lower efficiency of the boiler usually resulted by low nitrogen retrofitting, the boiler corrosion caused the flue gas recirculation, energy consumption increased to ensure air environment requirements of the boiler room and other issues, puts forward a low nitrogen emissions optimization scheme that based on deep recovery flue gas condensation heat and flue gas condensate water, which heating the water in the network, combusting air and heating air by flue gas waste heat. Taking a retrofitting project of thermal efficiency improvement and nearly smoke-free emission of a 29 MW boiler in Beijing with the flue gas temperature dropped below 70 ℃ and the thermal efficiency being more than 95% as an example, makes a technical and economic benefit analysis on energy saving, water saving, fog removing and nitrogen emission reduction. The measurement results show that, the flue gas temperature drops from 48.6-60 ℃ to 37.6-46 ℃ under different loads of boiler, resulting 5.2%-8.4% of energy saving, the unit capacity (700 kW) of the boiler recovers condensate water of 0.68-1.54 t/d, the nitrogen oxide emission is under 30 mg/m3 and the water (fog) removing rate of flue gas reaches 66%, and the energy saving, water saving and environmental protection effects are remarkable.
Keywords:gas-firedboiler,lownitrogen,fogremoving,condensationheatoffluegas,wasteheatutilization,practicalmeasurement