【Q&A Question 291】November 5, 2017

Reduce the pressure from high to low; direct the acidic water with a high pressure rating to the acidic water tank. Drain the liquid from the buffer tank at the hydrogen circulation inlet, use high-pressure centrifugal pumps, and remove condensate from the fresh hydrogen tank and the liquid separation tank

High pressure, hydrogen circulation desulfurization tower level, interface level； Outputs of feed pump, injection pump, and lean liquid pump ； New hydrogen machine returning

From high to low score: cutting at high scores, cutting at low scores and fractionation from low scores; outlet of the new hydrogen generator, outlet of the hydrogenation feed pump, outlet of the lean liquid pump, outlet of the injection 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 new hydrogen compressor inlet, care should be taken during startup, shutdown, and operation to prevent sudden failures of the new 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 new hydrogen compressor inlet should be kept fully open. (3) When the reaction feed pump, the fresh hydrogen compressor, and the water injection 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, care should be taken to close the two-way valve and the manual valve 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 new hydrogen compressor inlet, care should be taken during startup, shutdown, and operation to prevent sudden failures of the new 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 new hydrogen compressor inlet should be kept fully open. (3) When the reaction feed pump, the fresh hydrogen compressor, and the water injection 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, care should be taken to close the two-way valve and the manual valve 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 new hydrogen compressor inlet, care should be taken during startup, shutdown, and operation to prevent sudden failures of the new 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 new hydrogen compressor inlet should be kept fully open. (3) When the reaction feed pump, the fresh hydrogen compressor, and the water injection 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, care should be taken to close the two-way valve and the manual valve 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.

①High-pressure separator bypassing to low-pressure separator； ②New hydrogen compressor outlet bypass inlet ； ③Reaction feed pump outlet bypass inlet ； 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.