LOX Filling Operations of Liquid Oxygen Storage Tank

 
Liquid oxygen (LOX), as a form of liquefied oxygen, is widely used in various fields such as industry, healthcare, and aerospace. Due to its strong oxidizing properties and potential hazards, the safety management of LOX storage tanks and the filling process is of paramount importance. This article will explore the structural characteristics of LOX storage tanks, filling preparations, safety measures during the filling process, risk management, post-filling procedures, and emergency plans to effectively prevent and control risks associated with LOX usage.

Structural Characteristics of LOX Storage Tanks

 
The design and material selection of LOX storage tanks are key factors in ensuring safe usage.
 
Material Selection: LOX storage tanks are typically constructed from stainless steel or other cryogenic-resistant materials that exhibit excellent strength and toughness in low-temperature environments. The outer layer is usually made of carbon steel or stainless steel, providing an additional protective layer against external conditions.
 
Insulation Design: The vacuum insulation layer between the inner and outer tank effectively reduces heat transfer, minimizing the evaporation rate of liquid oxygen and maintaining its stable state. This design is crucial for preventing volatility during long-term storage.
 
Pressure Control System: LOX storage tanks are equipped with overpressure safety devices, such as pressure relief valves and safety valves, to ensure that excess internal pressure is released promptly, preventing potential explosions or leaks.

Filling Preparations for Liquid Oxygen

 
Thorough preparations before filling liquid oxygen are essential for ensuring a safe and smooth process.
 
Safety Inspections: Prior to filling, the tank truck must undergo a rigorous safety inspection to ensure compliance with all relevant safety standards. This includes checking for leaks, material integrity, and sealing efficiency.
 
Warning Signals: The filling site should be closed off and clearly marked with warning signs to prevent unauthorized vehicle access, reducing the risk of accidents.
 
Site Clearance: The filling area and the interior of the tank truck must be free of any flammable or explosive materials, and the site should be kept tidy to avoid accidents caused by debris.
 
Residual Gas Handling: When connecting to the exhaust gas discharge system, it is crucial to ensure that any residual gas in the tank is effectively recovered. If recovery is not possible, high-altitude venting methods should be employed to prevent oxygen toxicity and environmental pollution.

Safety Measures During the Filling Process

 
During the filling of liquid oxygen, strict adherence to operational protocols is necessary to minimize potential safety hazards.
 
Engine Shutdown: Upon entering the filling area, the tank truck's engine must be turned off, and the handbrake engaged. If necessary, wheel chocks should be added to prevent vehicle movement, ensuring the safety of personnel during the filling process.
 
Static Electricity Precautions: When connecting filling hoses, the use of tools that may produce sparks is strictly prohibited to prevent fire hazards. Personnel must wear anti-static clothing and protective gear to minimize the risk of static-induced fires.
 
Environmental Monitoring: Continuous monitoring of surrounding gas concentrations during filling is essential to ensure that oxygen levels remain within a safe range, preventing combustion or explosion risks associated with high oxygen concentrations.

Risk Management for LOX Storage Tanks

 
During the use and filling of LOX storage tanks, special attention should be given to the following risk factors.
 
Oxygen Concentration Control: LOX's strong oxidizing properties mean that once oxygen concentrations exceed safe limits, combustion or explosion may occur. Thus, maintaining appropriate oxygen levels is critical.
Equipment Maintenance: Regular checks of storage tanks and related equipment are essential to ensure the proper functioning of safety devices. Special attention must be paid to the functionality of pressure relief valves and vent valves to prevent accidents.
Pipeline Inspection: When performing maintenance on oxygen pipelines, air replacement is crucial to avoid the mixing of nitrogen and air, which could lead to combustion. The strength and corrosion resistance of pipeline walls must also meet safety standards to prevent leaks.

Post-Filling Procedures

 
After filling is complete, following the appropriate handling procedures is necessary to ensure the safety of subsequent operations.
 
Residual Liquid Management: After unloading, residual liquid at the interface must be properly drained according to operational procedures to prevent fire or explosion risks from liquid spillage.
 
Leak Detection: After filling, all equipment and pipelines should be inspected to ensure there are no leaks and to restore the safety status of the filling area.

Emergency Plans

 
Despite various safety measures, it is essential to prepare emergency plans to address potential unforeseen circumstances.
 
Evacuation Procedures: In the event of a fire or leak, the emergency evacuation procedure should be initiated promptly to ensure the safe evacuation of all personnel following designated escape routes.
 
Firefighting Equipment: The filling area should be equipped with firefighting equipment suitable for LOX environments (such as CO2 and dry powder extinguishers) and regularly maintained and inspected to ensure readiness in critical situations.

Conclusion

 
The safety management of LOX storage tanks and filling processes is crucial. By adhering to strict operational protocols, conducting regular maintenance, and implementing risk controls, the risks associated with LOX can be effectively reduced, ensuring the safety of personnel and equipment. While LOX has significant application value, its potential hazards require constant vigilance and the implementation of necessary safety measures to prevent accidents. Ultimately, comprehensive safety management and training can enhance the safe usage of LOX, protecting operators and associated facilities.