A method and apparatus for the production of low-energy nitrogen, used in a part of the rectification column for nitrogen air cooling, condensation into liquid nitrogen, nitrogen as part of the product, and the rest as reflux liquid returned to the top of the column; The other part of the nitrogen into the heat exchanger to reheat at room temperature, supercharger booster expansion machine for the user nitrogen transmission network; The bottom of the tower gets the oxygen-rich liquid air, enters the heat exchanger cold liquid undercooling degree, the throttle reenters the condensing evaporator as a cold and heat source and nitrogen, enters the complex heat exchanger and re-enters the expansion machine to expand refrigeration evaporating oxygen-rich gas, and the low-pressure oxygen-rich gas expands into the complex heat resulting in heat transfer device. Through the invention of the output power pressurized nitrogen oxygen rich, reduce the compressor exhaust pressure to reduce energy consumption, low pressure liquid air oxygen, nitrogen rich and rich cold fluid hot cold oxygen pressure changes, reduce the water content in the air to increase the extraction rate, reduce 15 ~ 23% energy consumption, 14 ~ 22% water consumption, The economic benefits are considerable.

The preparation method of low energy nitrogen is characterized in that it comprises the following steps:

A) Low temperature cooling heat exchanger for nitrogen compressor and air purification;

B) After the cooling air enters the rectification tower, the rectification tower, from the top to the bottom plate or packing adopts the heat and mass transfer of the liquid from top to bottom, and nitrogen is generated on the top of the tower;

C) Part of the nitrogen condensing into liquid nitrogen from the distillation tower into the evaporator condenser, the nitrogen machine liquid nitrogen as part of the product is the rest of the liquid nitrogen of the LED, and the liquid nitrogen returns to the top nitrogen of the distillation tower as the reflux liquid; The other part is the normal temperature of the pressurized end of the heat exchanger, which is pressurized and then enters the expansion machine for the user's nitrogen pipe network;

D) The oxygen-rich liquid air is extracted from the bottom of the distillation tower, in the undercooled heat exchanger, the throttle valve enters the evaporator condenser as a cold source, and the pressure of the liquid rich evaporator generated by condensation after evaporation enters the heat exchanger to enter the heat exchanger and reheat to room temperature to discharge the nitrogen generated after low oxygen-rich expansion. The output function is extended to drive the expander pressurized nitrogen pressurized end.