Discussion on the setup issues of the air separation liquid oxygen backup system

A liquid oxygen storage tank is installed to enable continuous vaporization and supply in the event of an accident. This data should be available from the early stages of design. It is estimated that 1 cubic meter of liquid oxygen can produce 804 Nm³ of oxygen. Based on the time required by conventional air separation equipment to handle such processes, as well as the capabilities for production control, a liquid oxygen storage tank with a capacity of 500 m³ to 1000 m³ is recommended. This decision takes into account the local market conditions regarding the transportation and sales of liquid oxygen. It should be enough. Choose a smaller one for easier transportation in the surrounding area; otherwise, a larger one will have to be chosen. It is best to communicate with the tank manufacturers or consult relevant companies, as they have extensive experience that can serve as a reference.

Oxygen storage tanks, a backup cryogenic oxygen pump, and a high-pressure oxygen buffer tank are installed; in the event of a failure in the air separation unit, the high-pressure oxygen buffer tank provides a buffer for about 1 minute, allowing the cryogenic oxygen pump to take over and ensure a seamless supply of oxygen.

To keep the production line running, a reserve supply of oxygen at the normal production level must be prepared.

I remember discussing this issue with the air separation suppliers in the past; they kept statistics on the accidents that occurred in air separation systems, and I recall that most of these accidents could be resolved within 8 hours. Therefore, this factor needs to be taken into account when designing oxygen backup systems. Additionally, it’s necessary to consider the seamless transition to oxygen backup. The best approach is to look at how gas companies design such systems in their BOO projects.