When a nitrogen sealing system is used for gasoline floating roof tanks, how should the nitrogen flow rate be determined?

First of all, both large and small breaths exist. The amount of breathing during material intake and output remains relatively stable, but the range of variation for thermal breathing is quite large. The general specifications provide the maximum value, which is used to determine the diameter of the breather valve or vent pipe. As for the actual amount of nitrogen sealing, a flow rate is generally determined after comprehensive consideration, but it should not be less than the breathing volume during material inlet and outlet

Connecting the tops of the storage tanks could be considered to reduce nitrogen consumption for breathing purposes. If operating the nitrogen-sealed tank independently, it is necessary to take into account both large and small respirations, external climate changes (such as heavy rainfall or snowfall), as well as the maximum output volume, for reference!

I have a case involving a non-insulated storage tank with an output flow rate of 12 cubic hours; the designed maximum nitrogen supply rate is 30 cubic meters per hour. In actual operation, when there are large differences between day and night temperatures, the nitrogen supply speed is not sufficient, which results in the tank reaching near-negative pressure. Therefore, those responsible for the design must conduct thorough calculations. Various factors need to be taken into account, including the flow rate, the maximum temperature differences in the area, the insulation level of the tank, and the volatility of the product itself. It’s advisable to include as much additional information as possible.

At the moment, we only consider the output volume

This post was last edited by cjgj008 on 2017-5-5 at 10:42. In this regard, the design institute needs to carry out calculations; the flow rate of nitrogen supply must take into account both normal breathing (inhalation) and the amount of heat generated through breathing under extreme conditions (such as severe temperature drops or heavy rainfall/snow). Simulations of situations where these factors occur simultaneously are required, along with comprehensive calculations. Furthermore, in my opinion, when the receipt and dispatch of stored materials is not very frequent, thermal breathing loss is the main source of nitrogen consumption (especially in summer). Furthermore, poor sealing of devices such as breather valves, breathing manholes, oil level gauges, and foam generators is a major cause of abnormal nitrogen loss. In short, nitrogen sealing is indeed very expensive! Keeping up with daily management saves a bit, but it still costs money! Hehe.

For nitrogen sealing, I generally only consider the breathing effect caused by the amount of material discharged.