石油化工腐蚀与防护
石油化工腐蝕與防護
석유화공부식여방호
PETROCHEMICAL CORROSION AND PROTECTION
2012年
4期
9-10,56
,共3页
塔顶冷凝冷却系统%腐蚀%改造
塔頂冷凝冷卻繫統%腐蝕%改造
탑정냉응냉각계통%부식%개조
Tower overhead condensing system%corrosion%revamping
对某石化分公司10 Mt/a蒸馏装置塔顶冷凝冷却系统腐蚀的原因进行了分析:原油/常压塔顶油气换热器E-102部分管板焊缝及热影响区蚀坑是结垢引起的垢下腐蚀以及HCl露点腐蚀共同作用的结果。结垢及微裂纹的主要原因为常压塔顶系统注剂匹配欠佳、注水量偏低、注水水质不佳及氯化物应力腐蚀开裂,管板在焊接(堆焊)、机加工过程中存在一定的残余应力使管板在拉伸应力和含氯化物水溶液的共同作用下发生氯化物应力腐蚀开裂造成的。原油/初馏塔顶油气换热器E-101管板结垢严重,但腐蚀轻微,其原因为初馏塔顶系统温度较常压塔顶高、冷凝水pH值控制较好且氯离子含量较常压塔顶低。针对以上问题采取了相应对策并对塔顶防腐蚀系统进行了改造,确保塔顶冷凝水pH值控制在6~9,Fe2+和Fe3+质量浓度不大于2 mg/L,取得了良好的效果。
對某石化分公司10 Mt/a蒸餾裝置塔頂冷凝冷卻繫統腐蝕的原因進行瞭分析:原油/常壓塔頂油氣換熱器E-102部分管闆銲縫及熱影響區蝕坑是結垢引起的垢下腐蝕以及HCl露點腐蝕共同作用的結果。結垢及微裂紋的主要原因為常壓塔頂繫統註劑匹配欠佳、註水量偏低、註水水質不佳及氯化物應力腐蝕開裂,管闆在銲接(堆銲)、機加工過程中存在一定的殘餘應力使管闆在拉伸應力和含氯化物水溶液的共同作用下髮生氯化物應力腐蝕開裂造成的。原油/初餾塔頂油氣換熱器E-101管闆結垢嚴重,但腐蝕輕微,其原因為初餾塔頂繫統溫度較常壓塔頂高、冷凝水pH值控製較好且氯離子含量較常壓塔頂低。針對以上問題採取瞭相應對策併對塔頂防腐蝕繫統進行瞭改造,確保塔頂冷凝水pH值控製在6~9,Fe2+和Fe3+質量濃度不大于2 mg/L,取得瞭良好的效果。
대모석화분공사10 Mt/a증류장치탑정냉응냉각계통부식적원인진행료분석:원유/상압탑정유기환열기E-102부분관판한봉급열영향구식갱시결구인기적구하부식이급HCl로점부식공동작용적결과。결구급미렬문적주요원인위상압탑정계통주제필배흠가、주수량편저、주수수질불가급록화물응력부식개렬,관판재한접(퇴한)、궤가공과정중존재일정적잔여응력사관판재랍신응력화함록화물수용액적공동작용하발생록화물응력부식개렬조성적。원유/초류탑정유기환열기E-101관판결구엄중,단부식경미,기원인위초류탑정계통온도교상압탑정고、냉응수pH치공제교호차록리자함량교상압탑정저。침대이상문제채취료상응대책병대탑정방부식계통진행료개조,학보탑정냉응수pH치공제재6~9,Fe2+화Fe3+질량농도불대우2 mg/L,취득료량호적효과。
The causes of corrosion in the overhead condensing system of a 10 MM TPY crude distillation unit were analyzed. The corrosion pits in tube sheet welds and heat - affected area of crude/atmospheric distillation tower overhead heat exchanger E - 102 were the results of common effects of under - deposit corrosion and HC1 dew point corrosion. Fouling and micro cracking were mainly caused by inappropriate matching of corrosion inhibitors, lower water injection, low - quality water injection and chloride stress corrosion and chloride stress corrosion cracking under the common effect of residue stress in welding (deposit welding) and processing and water liquid containing chlorides. The tube sheets of overhead oil vapor heat exchanger E - 101 of crude/ preliminary distillation tower suffered from serious fouling but little corrosion. The causes were that the temperature of overhead system of preliminary tower was higher than that of atmospheric tower, the pH value of condensate was appropriately controlled and chlorine ions were lower than those in atmospheric overhead. The tower overhead corrosion protection system has been revamped to ensure that the pH of overhead condensate was controlled at 6 - 9 and the mass concentration of Fe2 + and Fe3+ was no greater than 2 mg/L. Good results have been achieved.