Pressure tank nitrogen sealing system
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Dear teachers: According to SH/T 3007-2014, \"Code for Design of Tank Areas in Petrochemical Storage and Transportation Systems\", section 4.2.4 states that for storing Class A liquids with a boiling point below 45°C or a saturated vapor pressure greater than 88 kPa at 37.8°C, pressure tanks, low-pressure tanks, or atmospheric-pressure tanks equipped with cooling systems should be used, and the following requirements must be met: a) When using pressure tanks or low-pressure tanks, measures must be taken to prevent air from entering the tanks, and the gases discharged from the tanks must be collected and treated in a sealed manner； Do pressure storage tanks and low-pressure storage tanks employ measures to prevent air from entering the tanks, and does that refer to nitrogen blanketing? Since it’s a pressurized storage tank, how can air get in?
The measures taken in pressure tanks and low-pressure tanks to prevent air from entering the tanks usually involve the use of a nitrogen purge system, which fills the tanks with nitrogen of high purity to maintain a positive pressure and prevent external air from entering. Even in pressurized storage tanks, during operations such as loading and unloading liquids, or when the pressure inside the tank decreases due to temperature changes, external air may still enter; therefore, a nitrogen protection system is needed to ensure safety. .
1. The liquid level in the storage tank changes up and down due to material inflow and outflow, and as a result the internal volume also changes, leading to a \"breathing\" effect that creates conditions for external air to enter； 2. Changes in temperature can also cause changes in pressure difference ； These are just my personal opinions for reference only.