Should an internal floating roof or a vaulted roof be used for the intermediate storage tank at the dock for unloading ships? ? ? ? ? ? ?
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There is a chemical terminal along the Yangtze River used for unloading p-xylene (PX) and acetic acid. PX belongs to Category A, with a freezing point of around 13.6 degrees Celsius, while acetic acid belongs to Category B, with a freezing point of around 16 degrees Celsius. The level of the storage tanks at the terminal is 50 meters higher than that of the floating barges. The tank area is equipped with 2 PX storage tanks with a capacity of 3,000 cubic meters each, and 2 acetic acid storage tanks with a capacity of 1,000 cubic meters each. Electric tracing is used for pipelines and storage tanks. Should PX and acetic acid tanks use internal floating roof tanks or dome tanks with nitrogen sealing? Is it necessary to purge with nitrogen after each unloading operation? If purging is required, cannot an internal floating roof tank be used?
A dome tank + nitrogen seal should be used, with nitrogen purging.
If line cleaning is required, an internal floating roof tank cannot be used; instead, a dome tank with nitrogen sealing should be employed. If no line cleaning is needed, an internal floating roof tank can be used as well.
The dock is located upstream of the Three Gorges of the Yangtze River, in a very strategic geographical position. I think it would be necessary to clean it with gas; I wonder what the effect would be if nitrogen were used to blow the gas upward along the slope from the bottom of the floating vessel – would that be sufficient to clean it thoroughly?
If nitrogen is used for purging, a dome tank + nitrogen seal should be employed. 1. Purge the line with nitrogen; high-flow, high-pressure nitrogen can have an impact on the floating roof of an internal floating roof tank. For safety reasons, dome tanks should be used. 2. If nitrogen purging is not used, in order to prevent the material from evaporating and to reduce losses, an internal floating roof tank should be employed. If nitrogen is used for purging, a nitrogen seal is employed to reduce losses.