How industrial oxygen is made
Industrial oxygen is liquefied air, boiled apart in a column so tall that nitrogen and oxygen separate by height.
- stations
- 5
- things upstream
- 1
- raw source
- 1
- step from the ground
- 1
The short version
Industrial oxygen is made by cooling air until it liquefies and then distilling it in tall columns. Oxygen boils at a higher temperature than nitrogen, so it collects as a liquid at the bottom. The oxygen is drawn off at purities between 97.5% and 99.5%, then trucked as a liquid or piped to nearby steel and chemical plants.
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Compress the air
Outside air is drawn in and compressed. The compressor supplies the energy that the plant's refrigeration needs, so no separate cooling machine is required.
Goes in -
Clean out moisture and gas
Beds of molecular sieve adsorb water vapor, carbon dioxide and heavy hydrocarbons, none of which may reach the cold section of the plant.
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Cool it until it liquefies
Air is cooled against the cold gases leaving the plant, and expansion turbines chill it further. Part of the air becomes a pale blue liquid enriched in oxygen.
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Distill in two stacked columns
A high-pressure column and a low-pressure column work together. Their shared condenser runs on a temperature difference of just one or two kelvins, so oxygen drains out at the bottom as nitrogen vents off the top.
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Fill tankers and pipelines
Liquid oxygen is stored in insulated tanks and loaded onto tankers. Customers near the plant, such as steel mills, are connected by pipe.
Worth repeating
- Hydrocarbons are scrubbed out of the air before it is liquefied, because they could build up in the liquid oxygen and become an explosion hazard.
- Almost all the oxygen in Earth's air was made by photosynthesis, and it would vanish if living things did not keep replacing it.
Back to the ground
Follow every input upstream and oxygen gas starts as these 1 raw source.
Open the whole family tree
Where it goes next
Oxygen gas feeds 12 lines directly and reaches 380 things in total.
Further down the line
Keep walking
Sources
Cite this page: "How industrial oxygen is made." Assembly Line, 2026-11-03. https://assemblyline.org/make/oxygen