Help request {Cleaning internal floating roof tanks, steaming, purging}
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There is a floating roof tank with a capacity of 1,000 cubic meters that needs to be emptied. It originally contained MTBE, and now it needs to be cleaned; heating coils will be installed inside the tank. How can steam treatment and cleaning be carried out to create the conditions necessary for working inside the tank?
Steam it, and once the conditions for entering the tank are met, clean it using a high-pressure gun
1. Physically isolate the process flow； 2. Open the manholes and light-transmitting holes, and remove the breather valve etc. to provide the tank with a sufficiently large steam discharge pathway ； 3. Slowly introduce steam to raise the temperature gradually, controlling it at around 65°C–70°C; steam for about 24 hours, while collecting the condensed water at the bottom of the tank from time to time. Welding modifications can only be carried out after it is confirmed that the conditions for welding and entry are met.
A high-pressure water gun won’t work; it will damage the inner float.
1. Empty the oil tank. 2. Install blind flanges as per the process requirements. 3. Create light-transmitting holes, manholes, and float access holes. 4. For steam tanks: be careful not to let the temperature get too high to avoid damaging the anti-corrosion coating, and also be aware of sudden changes in weather conditions. 5. Wash with water, conduct inspections to ensure compliance, and take samples for analysis (work in confined spaces). 6. Disconnect the fire-fighting metal hoses and remove the internal float (this is required when working with open flames). 7. Are the conditions necessary for working with open flames met? Yes, hot work is required. 8. Additionally: MTBE does not need to be heated
Saw it a bit late. MTBE must absolutely not be treated by steaming or rinsing as mentioned above! ! Because MTBE is slightly soluble in water, it will kill the activated sludge in wastewater treatment plants, unlike gasoline. Gasoline should be used for displacement first; of course, the process is taken into account during design. Pre-cook for half a day, then flush with water through the manhole, followed by formal cooking for 70 hours at 60°C. Enter for rinsing later.
1. Physically isolate the process flow; blind plates must be installed on all pipes； 2. Open the manholes and light-transmitting holes, and remove the breathing valve, etc ； 3. Slowly introduce 2S or 5S steam and raise the temperature gradually, controlling it at around 50°C–70°C; steam for approximately 24 hours, while collecting the condensed water at the bottom of the tank from time to time. 4. Welding modifications can only be carried out after the conditions for welding and entry are met. 5. Re-test after 30 minutes. 6. Work in confined spaces requires supervision.
Agree with the 6th floor! MTBE is slightly soluble in water, has strong penetration ability, and is difficult to degrade; once it enters the ground, it contaminates groundwater. Entering the wastewater treatment plant will kill the activated sludge. Gas replacement is possible; after that, it needs to be rinsed with water, and the rinse water must be removed and treated by a company qualified for environmental handling. Everyone has covered other measures such as blinding, steaming, and ventilation in great detail. .
Before steaming the storage tank, it is necessary to remove the floating roof sealing tape, or use an anti-static material to separate the sealing tape from the tank wall, so that steam can steam the upper part of the tank wall where the floating roof is located; this also facilitates the flow of condensed water along the tank wall toward the bottom of the tank.
For all operations, one must be extra careful, pay close attention to safety, and think things through thoroughly. Work can only be carried out once safety measures are in place.