High-temperature and low-temperature expansion energy-saving nitrogen production device and nitrogen production method

The invention relates to a high-temperature and low-temperature expansion energy-saving nitrogen production device and a nitrogen production method. The high-temperature and low-temperature expansion energy-saving nitrogen production device comprises a precooling heat exchanger and a cooling box connected with the precooling heat exchanger, wherein the cooling box comprises a main heat exchanger, a rectifying tower, a condensation evaporator, a supercooler and a high-temperature supercharge turbine expander. The high-temperature and low-temperature expansion energy-saving nitrogen production device and the nitrogen production method have the advantages that the temperature of air in the rectifying tower is improved, the air is in a superheated state and then enters the rectifying tower, the rectification of the rectifying tower is facilitated and the nitrogen extraction rate is improved; since the air inlet temperature of the high-temperature supercharge turbine expander is high, the output power is larger, the product nitrogen is supercharged by using output power, the operating pressure of an air compressor and the rectifying tower is reduced, the energy consumption of the air compressor is reduced, the separation effect of the rectifying tower is improved and the nitrogen extraction rate is improved.