Abstract: A thermomechanically integrated distillation column and method for the separation of ethylene from ethane and other close-boiling light hydrocarbons. The column has a plurality of sections operated at successively lower pressures from a high pressure subcritical section to a superatmosphere bottoms product zone. Bottoms liquid from the high pressure and intermediate sections are flashed in respective cooling loops to about the pressure of the section of next lower pressure, vaporized in heat exchange with an overhead condensing zone and introduced to the top stage of next lower pressure section. Vapor from the intermediate sections and the bottoms product zone are compressed in respective compression loops and fed to the bottom stage of the section of the next higher pressure. External refrigerant can be supplied to the overhead condensing zone for trim as needed for control purposes.