Before a liquid oxygen storage tank is cooled, in addition to basic conditions such as personnel, tools and equipment, and the cold medium for pre-cooling, it is crucial that the storage tank system meets the following requirements, mainly including:
1.All process pipelines related to the cooling of the liquid oxygen storage tank have completed drying and replacement operations.
After the liquid oxygen storage tank is dried, the maximum dew point of the medium inside the tank shall be -20 ℃. When the annular space is filled with expanded perlite, the maximum allowable dew point in the annular space is -8 ℃. Nitrogen is used to replace the interior of the liquid oxygen storage tank, and the oxygen content in the replaced liquid oxygen storage tank shall not exceed 9%. There is no requirement for drying and replacement of the insulation space at the bottom of the tank.
2.A BOG (Boil-Off Gas) treatment system shall be configured to handle the large amount of flash vapor generated during the cooling process. All spaces that may generate flash vapor shall be able to direct the vapor to the flare treatment system through vent pipelines.
3.Check the status of all process valves, vent valves, hand valves (both on and under the main valves), and external isolation valves of the liquid oxygen storage tank.
4.Confirm that relevant external facilities (such as temperature monitoring devices and concentration detection equipment) are in normal working condition.
5.Develop an emergency plan to address interruptions that may occur at any stage during the cooling process of the liquid oxygen storage tank.