Leakage analysis for a high pressure heat exchanger in hydrorefining unit

摘要

ublishercopyright>? 2019, Editorial Office of PRE. All right reserved.? 2019, Editorial Office of PRE. All right reserved. The leakings of two times on the high-pressure heat exchanger E1103 in 2 # hydrorefining unit of SINOPEC Shijiazhuang Refining & Chemical Co., Ltd. and leaking conditions are analyzed. The results of analysis show that, the water injection at the beginning of start-up is about 3 t/h which is lower than 7.7 t/h, showing that the NH 4 HS crystals are formed in the heat exchanger tubes during the start-up. The failure analysis report shows that, the heat exchanger tubes' metallurgy meet the specifications, and the tube failure is caused by the corrosion from the corrosive media from the reaction of amine salts and water. The causes of corrosion are; the NH 4 Cl or NH 4 HS crystal salts in the process reaction can not be completely dissolved in the water under the original water injection conditions, and therefore amine salts erosion will occur during the unit operation; During the shutdown for maintenance, the heat exchangers are in the long-term water conditions and the under pit corrosion will occur. The effective solutions countermeasures are recommended in respect of water injection rate, space velocity of heat exchanger flow, optimization of unit shutdown procedures and protection of heat exchangers after unit shutdown. The long-term operation of the heat exchangers has been ensured. The leakings of two times on the high-pressure heat exchanger E1103 in 2 ## hydrorefining unit of SINOPEC Shijiazhuang Refining & Chemical Co., Ltd. and leaking conditions are analyzed. The results of analysis show that, the water injection at the beginning of start-up is about 3 t/h which is lower than 7.7 t/h, showing that the NH 44 HS crystals are formed in the heat exchanger tubes during the start-up. The failure analysis report shows that, the heat exchanger tubes' metallurgy meet the specifications, and the tube failure is caused by the corrosion from the corrosive media from the reaction of amine salts and water. The causes of corrosion are; the NH 44 Cl or NH 44 HS crystal salts in the process reaction can not be completely dissolved in the water under the original water injection conditions, and therefore amine salts erosion will occur during the unit operation; During the shutdown for maintenance, the heat exchangers are in the long-term water conditions and the under pit corrosion will occur. The effective solutions countermeasures are recommended in respect of water injection rate, space velocity of heat exchanger flow, optimization of unit shutdown procedures and protection of heat exchangers after unit shutdown. The long-term operation of the heat exchangers has been ensured.