某煤粉锅炉大渣可燃物异常原因分析

Abnormal Causes Analysis of Large Slag Combustible in a Pulverized Coal Boiler

某电厂300 MW亚临界机组出现了炉底烟花状落渣的现象,锅炉大渣可燃物含量达到20%以上,严重影响了锅炉运行的安全性与经济性。通过对大渣中可燃碳形态及粒径分布分析,结合中速磨煤机煤粉取样细度筛分及形态分析,认为是中速磨运行不正常导致的该现象。通过检查磨煤机内部,发现中央落煤管出现破损。修补该破损后锅炉炉底烟花状落渣现象消失,锅炉大渣可燃物含量降低到1%左右。建议电厂中速磨的日常维护中,除了要对磨辊、分离器挡板、风环部件进行检查维护,还应定期检查中央落煤管磨损情况。当电厂燃用可磨指数较低的煤种时,建议提高中速磨中央落煤管钢材耐磨等级或贴耐磨瓷片等,以避免中央落煤管的磨损。该研究结果可为国内其他锅炉同类问题解决提供参考。

A fireworks-like slag phenomenon at the bottom of a 300MW subcritical boiler occurred in a power plant, the content of combustible material in large slag reached more than 20%, which seriously affected the safety and economy of boiler operation. Based on the analysis of the morphology and particle size distribution of combustible carbon in large slag, combined with the fineness screening and morphology analysis of coal powder sampling in medium speed pulverizer, it was believed that the phenomenon is caused by the abnormal operation of medium speed pulverizer. By examining the inside of the coal mill, it was found that the central coal fall pipe was broken. After repairing the damage, the phenomenon of firework slag falling from boiler bottom disappeared, and the combustible content of boiler slag was reduced to about 1%. It is suggested that in the daily maintenance of medium speed mill in power plant, in addition to the grinding roller, separator baffle, wind ring components for inspection and maintenance, also should regularly check the central coal pipe wear. When the power plant is burning the coal with low grindability index, it is suggested to improve the wear resistance grade of the steel or paste the wear resistance tiles of the middle mill coal pipe at medium speed to avoid the wear of the coal pipe. The results can provide reference for similar faults of other boilers in China.