Cryogenic merchant liquid oxygen, argon and nitrogen plant in the nature of a generator consisting of main air compressor, air purification adsorbers, cold box, main heat exchanger, nitrogen recycle compressor and optional nitrogen feed compressor, turboexpander and booster compressor, main distillation columns, optional crude argon and pure argon columns, with optional product compressors with production of gases: liquid oxygen production from 50 to 200 short tons per day, liquid argon from 2 to 10 short tons per day, and liquid nitrogen from 130 to 520 short tons per day