[Q&A Question 212] 2017.07.31
Thread Content
【Q&A Question 212】July 31, 2017: In a hydrofinishing unit, which parts are prone to high-pressure leakage to the low-pressure side? The reference answers will be visible after responding; points are awarded by identifying the key points. (Unless otherwise specified, all questions and answers are based on hydrogenation units.) ) ①Only then does the high-pressure separator leak into the low-pressure separator ； ②New hydrogen compressor outlet bypass inlet ； ③Backflow into the inlet at the outlet of the reaction feed pump ； ④High-pressure injection pump outlet to inlet ； ⑤Circulating hydrogen desulfurization tower rich liquid flash tank ； ⑥Leak from the outlet to the inlet of the high-pressure low-ammonia liquid pump. Scoring criteria: 2 Wealth points for incorrect responses; *incomplete* answers earn 3–8 points. 10 Wealth points are given for correct answers accompanied by detailed explanations; responses that are correct but lack sufficient details earn 15–20 Wealth points. Please score according to these criteria. Note: If there are editing records after answering, only points will be awarded to those who participated. For continuous malicious spamming, 2 points will be deducted each time, with no upper limit. Pure numbers, pure emojis, or random letters that have nothing to do with the answer are all considered malicious spamming; points will start to be deducted after three warnings. 2017 Q&A Summary Thread (updates have begun) http://bbs.hcbbs.com/thread-1657793-1-1.html 2017 Daily Question Summary Thread (updates have begun) http://bbs.hcbbs.com/thread-1657794-1-1.html 2016 Q&A Summary Thread (updates completed) http://bbs.hcbbs.com/thread-1597792-1-1.html Petrochemical Sector – “Creative Ideas for Energy Saving” campaign (the second phase is in full swing) http://bbs.hcbbs.com/thread-1666758-1-1.html (Source: Haichuan Chemical Industry Forum)
High-pressure separator and low-pressure separator
(1) The oil phase between the high-grade and low-grade streams, as well as the acidic water from both grades, is sent to the acidic water tank; the level of the high-grade liquid must be maintained at a certain height to prevent the gas phase from entering the low-grade stream； During shutdown, do not allow the high-level cut-off to become empty to prevent gas phase from entering the acidic water tank. During startup, the cut-off control valve manual valve can be opened only after establishing the high-level cut-off. (2) For the cross-line between the liquid separation tank at the recycle hydrogen inlet and that at the fresh hydrogen compressor inlet, care should be taken during startup, shutdown, and operation to prevent sudden failures of the fresh hydrogen compressor, which could lead to high pressure leaking into the low-pressure system. During normal operation, all the cross-line valves at the top of the liquid separation tank at the recycle hydrogen inlet should be closed, while the inlet valve of the liquid separation tank at the fresh hydrogen compressor inlet should be kept fully open. (3) When the reaction feed pump, fresh hydrogen compressor, and feed water pump stop operating due to a fault, their outlet valves should be closed promptly to prevent high-pressure hydrogen from flowing back into the low-pressure system due to a faulty check valve. Additionally, attention should be paid to closing the two-way and manual valves of the fresh hydrogen compressor in a timely manner. (4) From the low-pressure tank to the distillation system, to prevent gas phase from entering the distillation system due to an excessively low level of liquid in the low-pressure tank
(1) The oil phase between the high-grade and low-grade streams, as well as the acidic water from both grades, is sent to the acidic water tank; the level of the high-grade liquid must be maintained at a certain height to prevent the gas phase from entering the low-grade stream； During shutdown, do not allow the high-level cut-off to become empty to prevent gas phase from entering the acidic water tank. During startup, the cut-off control valve manual valve can be opened only after establishing the high-level cut-off. (2) For the cross-line between the liquid separation tank at the recycle hydrogen inlet and that at the fresh hydrogen compressor inlet, care should be taken during startup, shutdown, and operation to prevent sudden failures of the fresh hydrogen compressor, which could lead to high pressure leaking into the low-pressure system. During normal operation, all the cross-line valves at the top of the liquid separation tank at the recycle hydrogen inlet should be closed, while the inlet valve of the liquid separation tank at the fresh hydrogen compressor inlet should be kept fully open. (3) When the reaction feed pump, fresh hydrogen compressor, and feed water pump stop operating due to a fault, their outlet valves should be closed promptly to prevent high-pressure hydrogen from flowing back into the low-pressure system due to a faulty check valve. Additionally, attention should be paid to closing the two-way and manual valves of the fresh hydrogen compressor in a timely manner. (4) From the low-pressure tank to the distillation system, to prevent gas phase from entering the distillation system due to an excessively low level of liquid in the low-pressure tank.
Leakage from the high-pressure separator to the low-pressure separator; leakage from the outlet of the new hydrogen compressor to its inlet; leakage from the outlet of the reaction feed pump to its inlet; leakage from the outlet of the high-pressure water injection pump to its inlet； Circulating hydrogen desulfurization tower rich liquid buffer tank ； High-pressure lean amine liquid pump outlet to inlet
Reaction system, hydrogen recovery system
(1) The oil phase between the high-grade and low-grade streams, as well as the acidic water from both grades, is sent to the acidic water tank; the level of the high-grade liquid must be maintained at a certain height to prevent the gas phase from entering the low-grade stream； During shutdown, do not allow the high-level cut-off to become empty to prevent gas phase from entering the acidic water tank. During startup, the cut-off control valve manual valve can be opened only after establishing the high-level cut-off. (2) For the cross-line between the liquid separation tank at the recycle hydrogen inlet and that at the fresh hydrogen compressor inlet, care should be taken during startup, shutdown, and operation to prevent sudden failures of the fresh hydrogen compressor, which could lead to high pressure leaking into the low-pressure system. During normal operation, all the cross-line valves at the top of the liquid separation tank at the recycle hydrogen inlet should be closed, while the inlet valve of the liquid separation tank at the fresh hydrogen compressor inlet should be kept fully open. (3) When the reaction feed pump, fresh hydrogen compressor, and feed water pump stop operating due to a fault, their outlet valves should be closed promptly to prevent high-pressure hydrogen from flowing back into the low-pressure system due to a faulty check valve. Additionally, attention should be paid to closing the two-way and manual valves of the fresh hydrogen compressor in a timely manner. (4) From the low-pressure tank to the distillation system, to prevent gas phase from entering the distillation system due to an excessively low level of liquid in the low-pressure tank
1. Only then does the pressure from the high-pressure separator leak into the low-pressure separator ； 2. Outlet bypass inlet of the new hydrogen compressor ； 3. Backflow into the inlet at the outlet of the reaction feed pump ； 4. High-pressure injection pump outlet to inlet ； 5. Rich liquid flash tank of circulating hydrogen desulfurization tower ； 6. Leakage from the outlet to the inlet of the high-pressure lean amine liquid pump.
(1) The oil phase between the high-grade and low-grade streams, as well as the acidic water from both grades, is sent to the acidic water tank; the level of the high-grade liquid must be maintained at a certain height to prevent the gas phase from entering the low-grade stream； During shutdown, do not allow the high-level cut-off to become empty to prevent gas phase from entering the acidic water tank. During startup, the cut-off control valve manual valve can be opened only after establishing the high-level cut-off. (2) For the cross-line between the liquid separation tank at the recycle hydrogen inlet and that at the fresh hydrogen compressor inlet, care should be taken during startup, shutdown, and operation to prevent sudden failures of the fresh hydrogen compressor, which could lead to high pressure leaking into the low-pressure system. During normal operation, all the cross-line valves at the top of the liquid separation tank at the recycle hydrogen inlet should be closed, while the inlet valve of the liquid separation tank at the fresh hydrogen compressor inlet should be kept fully open. (3) When the reaction feed pump, fresh hydrogen compressor, and feed water pump stop operating due to a fault, their outlet valves should be closed promptly to prevent high-pressure hydrogen from flowing back into the low-pressure system due to a faulty check valve. Additionally, attention should be paid to closing the two-way and manual valves of the fresh hydrogen compressor in a timely manner. (4) From the low-pressure tank to the distillation system, to prevent gas phase from entering the distillation system due to an excessively low level of liquid in the low-pressure tank.
1. Leakage from the high-pressure separator to the low-pressure separator. 2. Leakage from the outlet of the new hydrogen compressor to its inlet. 3. Leakage from the outlet of the reaction feed pump to its inlet. 4. Leakage from the outlet of the high-pressure ammonia injection pump to its inlet. 5. Leakage from the circulating hydrogen desulfurization tower to the rich liquid flash tank. 6. Leakage from the outlet of the high-pressure lean amine liquid pump to its inlet
(1) The oil phase between the high-grade and low-grade streams, as well as the acidic water from both grades, is sent to the acidic water tank; the level of the high-grade liquid must be maintained at a certain height to prevent the gas phase from entering the low-grade stream； During shutdown, do not allow the high-level cut-off to become empty to prevent gas phase from entering the acidic water tank. During startup, the cut-off control valve manual valve can be opened only after establishing the high-level cut-off. (2) For the cross-line between the liquid separation tank at the recycle hydrogen inlet and that at the fresh hydrogen compressor inlet, care should be taken during startup, shutdown, and operation to prevent sudden failures of the fresh hydrogen compressor, which could lead to high pressure leaking into the low-pressure system. During normal operation, all the cross-line valves at the top of the liquid separation tank at the recycle hydrogen inlet should be closed, while the inlet valve of the liquid separation tank at the fresh hydrogen compressor inlet should be kept fully open. (3) When the reaction feed pump, fresh hydrogen compressor, and feed water pump stop operating due to a fault, their outlet valves should be closed promptly to prevent high-pressure hydrogen from flowing back into the low-pressure system due to a faulty check valve. Additionally, attention should be paid to closing the two-way and manual valves of the fresh hydrogen compressor in a timely manner. (4) From the low-pressure tank to the distillation system, to prevent gas phase from entering the distillation system due to an excessively low level of liquid in the low-pressure tank.