Patent ID: 7134297

Claim:
A process for low-temperature fractionation of air in a rectification unit which comprises a pressure column, a low-pressure column and a condenser-evaporator system having at least a first and a second falling-film evaporators, said process comprising: introducing oxygen-rich liquid from the bottom ( 10 ) of said low-pressure column into evaporation passages ( 203 , 403 ) within said first falling-film evaporator and partially evaporating said oxygen-rich liquid, separating a gas-liquid mixture which emerges from the evaporation passages of said first falling-film evaporator into a gas and unevaporated oxygen-rich liquid, introducing said unevaporated oxygen-rich liquid from said first falling-film evaporator into said second falling-film evaporator, and introducing oxygen-rich liquid from the bottom ( 10 ) of said low-pressure column ( 2 ) introduced into evaporation passages of said second falling-film evaporator ( 204 , 404 ).