循环流化床锅炉分离器结构优化对锅炉性能的影响研究

Study on the Influence of Separator Structure Optimization on CFB Boiler

针对240 t/h循环流化床锅炉的分离器筒体耐火材料磨损、分离效率低、排烟温度偏高、锅炉NO_(x)生成量高、带负荷能力不足等问题,对旋风分离器结构进行了优化改造。工程试验研究表明:通过分离器入口弧线尺寸优化及筒体内部耐火材料修复,旋风分离效率明显提高,飞灰中位粒径D_(50)降低到22.73μm,返料灰中位粒径D_(50)降低到132.30μm;锅炉NO_(x)初始排放浓度(质量浓度)从350 mg/Nm^(3)降至150 mg/Nm^(3)以下、结合SNCR脱硝技术NO_(x)排放浓度(质量浓度)降到50 mg/Nm^(3)以下;同负荷平均床温降幅约110℃;锅炉带负荷能力从200 t/h恢复至240 t/h。分离器效率过高时会造成高温过热器、低温过热器、空气预热器积灰严重以及旋风分离器耐火材料磨损加剧。

The problems of wear of refractory material,low separation efficiency,high exhaust gas tempera⁃ture,high NO_(x) production and insufficient load capacity in CFB is studyed by optimizing cyclone separator structure.The practice shows that the cyclone separation efficiency is obviously improved by optimizing the size of separator inlet shape and repairing the refractory,the median particle size D_(50) of fly ash is decreased to 22.73μm,the median particle size D_(50) of return ash is decreased to 132.30μm,initial NO_(x) emission concentration(mass concentration)is reduced from 350 mg/Nm^(3) to 150 mg/Nm^(3),then can be reduced less than 50 mg/Nm^(3) by SNCR,the bed temperature is reduced by 110℃,boiler load capacity is recovered from 200 t/h to 240 t/h,and serious ash deposition in high temperature superheater,low temperature superheater and air preheater is caused by high separator efficiency,wear of refractory materials in cyclone separator is increased.