A look inside the engineering office in Höllriegelskreuth (1910), where
additional uses for the air liquefaction process (rectification) were being tested
at the time. |
The industry’s demand for oxygen-rich gas mixtures quickly fell. The demand for pure oxygen on the other hand grew by leaps and bounds since autogenous (gas) welding and cutting processes began to take hold in metal working. In order not to lose his connection to this very promising market, von Linde intensified his search for a new method of separating out pure oxygen. He finally convinced his son Friedrich and chemistry professor Hempel to try "rectification." |
This was a method of separating alcohol and water that had been long practiced in the field of chemistry: The fermented mash was heated until the alcohol evaporated. Heat was removed from the alcohol vapour by water cooling so that it could be condensed (rectification process) and captured as a liquid.
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In 1900, inventor Paulus Heylandt built the first tank car for liquid
oxygen, called the "Laubfrosch" or "Tree Frog." |
Technological breakthrough
Carl von Linde and his employees set in motion a comparable process, letting liquid air trickle down into to rectification column, while the oxygen vapour provided a countercurrent. This continuous process of liquefaction and evaporation produced nearly pure oxygen.
At the suggestion of Prof. Hempel, the first rectification column consisted of a steel tube filled with glass beads. This heavy apparatus with a long cool-down period was soon replaced with a lighter version with holes in the bottom instead of glass beads. Von Linde and his employees combined the liquefaction and separation units into one unit. "This opened up the road by which low-temperature technology finally found success in industry," wrote von Linde on this sensational breakthrough.
One of the first production plants, used to generate gas for many years, went into operation in Höllriegelskreuth, near Munich, in 1903.