Before cooling a liquid oxygen tank, in addition to basic requirements such as personnel, tools, and refrigerant media for pre-cooling, it is crucial that the tank system meets the following conditions:
① All process pipelines related to the tank cooling have completed drying and purging operations.
② After drying, the maximum dew point of the medium inside the tank is -20°C. When annular space is filled with expanded perlite, the maximum allowable dew point in the annular space is -8°C. When using nitrogen for tank purging, the oxygen content in the purged tank must not exceed 9%. No specific requirements apply to the insulation space at the tank bottom during drying and purging.
③ Employ a BOG treatment system to manage the substantial flash gas generated during cooling. All spaces prone to flash gas formation shall be vented via dedicated lines to the flare treatment system.
④ Inspect the status of all process valves, vent valves, downstream manual valves, and isolation valves for instruments on liquid oxygen storage tanks.
⑤ Verify that relevant temperature, concentration, and other instrumentation facilities are in normal operating condition.
⑥ Maintain an emergency plan for interruptions at any stage during the actual liquid oxygen storage tank cooling process.