干熄焦锅炉吊顶管爆裂的原因

Burst Failure of the Ceiling Tubes in a Coke Dry Quenching Furnace

通过对宏观形貌、显微组织、非金属夹杂物、基体化学成分、表面附着物的成分和物相等进行多方面分析,探讨了某厂干熄焦(CDQ)锅炉吊顶管发生爆裂的原因。结果表明:该吊顶管靠近炉壁,且表面未被防磨罩完全覆盖,由于具有腐蚀性的高温烟气被炉壁阻挡而滞积,导致该处吊顶管所受烟气腐蚀较其他位置剧烈。吊顶管外壁在高温烟气环境中,易生成氧化皮,氧化皮被腐蚀后脱落又再生,此过程循环往复,导致管壁厚度减薄,降低了管壁的承压能力。同时,由于长期在高温环境中服役,管壁材料的老化也降低了钢管的力学性能,最终吊顶管不能承受管内压力的作用而爆管。

By analyzing the macro morphology, microstructure observation, nonmetallic inclusions, chemical composition of substrate, component and phase analysis of the attachment on the surface, the reason for burst failure of the ceiling tubes in a coke dry quenching （CI）Q） furnace was discussed. The results showed that the ceiling tube near the inner wall of the furnace without mask on the side of bursting was severely thinned by the accumulation and erosion of flue gas. In the environment of flue gas with high temperature, the oxide scale was easily formed. The oxide scale on the external surface was flaked off by corrosion and then regenerated. Circularly, the thickness of tube was reduced and the strength decreased further. Meanwhile, the steel aging of tube caused the reduced mechanical properties because of long-term service at high temperature. Finally, the ceiling tube burst due to over the limit pressure inside the tube.