For nitrogen purging of internal floating roof methanol tanks, should nitrogen be introduced from the top or the bottom?
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For nitrogen purging of internal floating roof methanol tanks, should nitrogen be introduced from the top or the bottom?
Top injection is used because nitrogen has a lower density than air; bottom injection would result in some of the nitrogen being wasted. However, there are many designs that employ bottom injection
If nitrogen is used for displacement, it must be done from the bottom of the storage tank; after all, the density of air is slightly higher than that of nitrogen. If ventilation is carried out from the top, displacement will not be possible at all
It is recommended to start from the bottom, with a density slightly less than that of air.
Considering the floating pad, inject from the top.
The method of using nitrogen for purging internal floating roof storage tanks indeed needs to be discussed
Internal floating roof tanks have edge vent holes; when nitrogen is injected at the top, it escapes through these vent holes. Additionally, after the floating pad sinks to the bottom, the ventilation above and below it is poor. It is better to inflate from the bottom, to reduce nitrogen loss, and to ensure thorough replacement of the air in the space beneath the floating disk.