What are the gas replacement methods for liquefied gas tank and LPG storage tanks?
Time:2022-09-05
Views:114
Liquefied petroleum gas (also known as gas and gas) is easy to explode and burn under high pressure when it comes into contact with air. Therefore, there are strict standards for the filling safety specifications of liquefied gas tank cars and liquefied gas storage tanks. Article 50.6 of the national relevant specifications - Safety Supervision Regulations for liquefied gas tank cars clearly stipulates:
Newly manufactured automobile tank cars or automobile tank cars filled for the first time after maintenance must be vacuumed or filled with nitrogen for replacement before filling flammable and explosive media. It is required that the vacuum degree shall not be lower than 86.6kpa, or the oxygen content of the gas in the tank shall not be greater than 3%; Clause 12 of Article 50 clearly stipulates that the pre pressure in the storage tank after unloading shall not be lower than 0.1MPa to prevent air from entering.
So, what are the gas replacement methods for liquefied gas tank cars and liquefied gas storage tanks?
1. Water pressure replacement: fill the tank with water, discharge the air out of the tank, and inject liquefied gas to discharge the water through pressure during filling. This method is troublesome and involves many steps. It needs to be familiar with the vehicle structure and operation. Moreover, after water injection, it will corrode the valves, pipes and safety accessories, causing rust and other adverse factors. Therefore, this method is generally not adopted by the operators of gas stations.
2. Vacuuming and replacement: it is to directly pump out the air in the liquefied gas tank car and liquefied gas storage tank by using the vacuuming equipment with large displacement, so as to achieve the required oxygen content of less than 3%. This method is faster than nitrogen replacement, but such vacuuming equipment is expensive, one-time investment is large, and operation cost is expensive, so the utilization rate of gas station owners is not high.
3. Nitrogen replacement: this kind of replacement method is commonly used in most liquefied gas stations. Nitrogen is an extremely inert gas and will not react with other gases. The nitrogen replacement method is to inject nitrogen into liquefied gas tank cars or tanks by using replacement devices. Because of the high density and mass of nitrogen, the air in the tanks is discharged out of the containers, so that the oxygen content in the tank cars or tanks is less than 3%, So as to ensure that accidents such as explosion will not occur during filling. Precautions: the nitrogen used for replacement is ordinary nitrogen with purity of 99.15%, and the tank car needs to be equipped with anti-static and safety protection devices.
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