The problem
Evaporating cane juice in open kettles wasted enormous fuel, burned the sugar, and maimed the enslaved workers doing it.
The innovation
A sealed series of vacuum pans in which the vapour boiled off in one pan supplies the heat for the next, at successively lower pressures.
How it worked
Lowering pressure lowers the boiling point, so waste steam from stage one is hot enough to boil stage two — the same energy does the work several times.
Why it mattered
Fuel consumption fell dramatically and product quality rose; the design spread through Louisiana, Cuba and Mexico.
The legacy
Still the standard method of industrial evaporation, including in thermal desalination plants supplying drinking water today.
You use this today
Refined sugar, powdered milk, paper pulp and desalinated water are all produced with descendants of this process.
Sources
US Patent 4,879
Primary recordNational Historic Chemical Landmark designation
Institutional record
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