吹灰用空氣壓縮機熱交換銅管破損分析

Failure Analysis of Heat Exchanger Used in Blowing Compressor

吹灰用空氣壓縮機係作為鍋爐吹灰器之吹灰空氣源，鍋爐吹灰其主要目的是在防止鍋爐內所有爐管外表積灰結渣。吹灰空氣壓縮機中間冷卻器金屬熱交換管，自民國85年加入運轉以來頻頻發生內部銅管嚴重破管情形，冷卻器破管數高達68根，佔108根總管數的63%，斷裂並非集中於某段位置，而是整根管材皆出現裂痕，裂痕為沿管壁圓周延伸斷裂，圓周裂痕成陣列式排列。斷裂沿著管徑圓周方向產生裂痕，各圓周裂痕皆具方向性沿軸心水流方向陣列式平行排列，垂直於主應力方向，銅管主要在水流速方向受到單軸荷重的應力影響，管材斷裂破壞形態為疲勞腐蝕，疲勞腐蝕的成因推測為流體振動、加工時的殘留應力及冷卻水中腐蝕物所引起。

The main function of blowing compresser was used in boiler for blowing away fly ash. The heat exchanger was serious blow out during the system staring operation in 1996. The failure heat exchanger was more than 68 tubes, about 63% by total 108 tubes, for uniaxial stress systems; there will be an array of parallel cracks, which are perpendicular to the direction of principal stress. The failure analysis corrosion fatigue continues to be a serious cause of failure. The stress source was attributed to fluid vibration, residual stress of fabrication and corrosive in cooling water.