What are the precautions for shutting down only the vacuum section of a atmospheric and vacuum distillation unit?
Thread Content
Our unit has undergone one maintenance session, with only the pressure reduction section being shut down. Dear sea friends, what should we pay attention to?
Primarily, the water seal tank must maintain its water seal until the pressure reduction system returns to normal pressure.
The main focus is on ensuring safe operations, preventing harm caused by leaks outside the system, as well as avoiding accidents such as those resulting from fires affecting the operating system: 1. Sufficient time must be allocated for distillation and tower cleaning; if possible, chemical cleaning should be used to remove bromine, in order to prevent spontaneous combustion of ferrous sulfide； 2 Isolated from the system by an external blind flange ； 3 In the north, pay attention to anti-condensation cleaning in the blind spots.
1. Ensure that all process pipelines of the pressure relief system and those connecting to the outside environment are equipped with blind flanges, and this should be recorded. 2. During shutdown, pay attention to the procedures required to break the vacuum level; the associated systems must also be operated accordingly, with coordinated and unified steps. 3. The maintenance site must be fixed; do not carry out work in areas where oil has not been removed. Such maintenance poses greater safety risks
When removing the vacuum from the pressure reduction system, it must be done slowly; not too quickly.
A few additional points: 1. During the shutdown process, the final temperature of heat exchange has a significant impact; therefore, it is necessary to pay attention to controlling the outlet temperature of the atmospheric pressure furnace, as well as the operating temperature of the electrodesalination unit, etc； 2. When the vacuum furnace stops, be especially careful to avoid water contamination when using your 0.3 MPa superheated steam (which is typically used as the stripping steam in vacuum furnaces) as the normal bottom steam ； 3. Pay attention to the system’s steam balance, as you need to purge it when shutting it down; don’t neglect one aspect at the expense of another ； 4. Pay attention to the balance of the fuel system.
The main thing is to do it slowly when breaking the vacuum level. And pay attention to the water seal tank. It is best to use diesel for displacement when reducing pressure.
1# Under the parasol trees in the rainy weather, we conduct this operation once a month, mainly considering cost-effectiveness. Let me talk about the key points: 1. It is essential to strictly follow the heating curve during startup and shutdown – there is no room for negligence here； 2. When stopping or reducing pressure, be sure to pay attention to the heat exchanger where the normal slag is discharged, to prevent oil leakage from the valves and resulting fires ； 3. Maintain a slight negative pressure in the towers after stopping the pressure reduction; pay attention to ensure continuous flow in the water seal tank ； 4. Measure the elevation of the oil and gas pipelines before and after startup and shutdown.