The anthracite in Fujian Province, China with extremely low volatile content about 2%～4% is very difficult to burn in grate firing boilers, and operation conditions are very poor, such as steam output well below the nominal capacity and very low burning-out rate. Burning Fujian anthracite in specially designed bubbling fluidized bed (BFB) boilers with capacities between 4 T/H and 20 T/H are still unsatisfactory. In order to increase boiler output and utilize local coal more efficiently, a 10 T/H BFB boiler burning Fujian anthracite was retrofitted with several special techniques, in terms of underbed feeding of recycling fly ash, vortexing secondary air injection, continuous bottom ash removal and adding immersed tube surface. The boiler performances before and after the retrofitting were measured and compared. The experimental results indicate that steam output of the boiler is boosted from 7～8 T/H to more than 14 T/H, unburned carbon content (UBC) in ash from the convective banks drops from 31.39% to 3.89%, UBC in ash from the multicyclone drops from 38.87% to 22.19%, and UBC in fly ash drops from 35.3% to 18.07%. The boiler thermal efficiency increases from 67.27% to 82.93%. Boiler operation becomes more stable. Particulate emission is substantially lessened because of separation by the vortexing secondary air. The retrofitting was completely successful. The technique used and experiences obtained in the retrofitting can be widely applied in industrial BFB boilers.
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机译：在福建省，中国无烟煤约2％〜4％的极低挥发物含量是非常困难的层燃锅炉燃烧和运行条件很差，如蒸汽产量远低于标称容量和非常低的烧出速度。在特别设计的鼓泡流化床（BFB）与4 T / H和20 T / H之间的容量锅炉燃烧福建无烟煤仍不令人满意。为了更有效地增加锅炉输出和利用本地煤，10 T / H BFB锅炉燃烧福建无烟煤用几种特殊技术改装，在回收飞灰的底架馈送而言，涡旋二次空气喷射，连续底灰去除和加入浸渍管表面上。测量和比较改造前后锅炉表演。实验结果表明锅炉的蒸汽输出从7〜8 T / H中灰升压到超过14 T / H，未燃烧的碳含量（UBC）从对流银行滴从31.39％至3.89％，UBC在灰从多管从38.87％下降到22.19％，而UBC飞灰下降，从35.3％到18.07％。锅炉热效率从67.27％增加至82.93％。锅炉操作变得更加稳定。微粒排放基本上减少，因为由涡旋二次空气分离的。改装是完全成功的。该技术使用和改装获得的经验可以在工业锅炉BFB被广泛应用。
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