对冲燃烧锅炉低氮燃烧器改造后煤种适应性试验研究

Experimental Research on Coal Applicability after Low-NO_X Burner Retrofit of Opposed Firing Boiler

一台660 MW机组的对冲燃烧锅炉进行了低NO_X 燃烧器改造,将原DRB-4Z燃烧器改造为新型Aire Jet燃烧器,并将燃尽风与上层燃烧器的距离由3.5 m改为7 m。燃烧器改造后,进行了燃用蒙煤和澳煤试验,锅炉运行参数正常,SCR装置入口烟气中NO_X 和CO含量都显著降低。燃用不同煤种时的锅炉参数存在较明显的差异。蒙煤的结渣倾向性较强,前屏有一定的结渣,导致再热器减温水量增加、SCR烟温偏高,不过基本上在可控范围内。燃用蒙煤和澳煤时的烟气中NO_X 含量分别在240 mg/m^3以下和320 mg/m^3以下,燃用2组煤种的烟气中NO_X 含量差异最高达到30%左右。SCR装置入口烟气中CO含量总体达到了200μL/L以下的较低水平,但燃用澳煤的烟气中CO含量明显较高,且排烟温度和飞灰含碳量也明显较高。因此燃用蒙煤比燃用澳煤的锅炉效率高1%左右,发电煤耗低3 g/kWh左右,燃用蒙煤具有显著的经济性。

Low-NOx burner retrofit was applied in opposed firing boiler of a 660 MW unit. The DRB-4Z burn-ers were replaced with the new AireJet burners. The distance between 0FA and upper burner was modified from 3.5mto7m. After the retrofit,tests were conducted on Mongolia coal and Australian coal respectively, and the operation parameters were as normal as before. NOx and CO in SCR inlet decreased significantly. There were significant differences in boiler parameters when burning the two coals. The slagging tendency of Mongolia coal is stronger,so there was a thin layer of slag on the front screen,resulting in attempering water in reheater and SCR temperature rise,but in a controllable range. The NOx concentrations were below 240 mg/m3 and 320 mg/m3 when burning Mongolia coal and Australian coal respectively. The difference was up to 30%. CO concentration in SCR inlet was less than 200 μL/L,but it was relatively higher when burning Aus-tralian coal ,and exhaust gas temperature and carbon content in fly ash were also high. The boiler efficiency of Mongolia coal was 1% higher than that of Australian coal ,and coal consumption for power generation of Mongolia coal was 3 g/kWh lower than that of Australian coal. It is concluded that the Mongolia coal is more economical.