Pressure maintaining of cold box

The air cooling tower is the core equipment of the air separation precooling system, which is mainly used to cool and wash the high-temperature compressed air discharged from the air compressor, provide qualified low-temperature gas source for subsequent molecular sieve purification and cold box rectification, and ensure the stable operation of the whole unit. The air cooling tower adopts the countercurrent packing heat exchange structure, the tower is filled with high-efficiency packing, and the top is equipped with a spray device and a wire mesh demister. During operation, the high-temperature compressed air at 80 to 100 ℃ discharged by the air compressor enters from the bottom of the tower and flows from bottom to top; The cooling water is the normal temperature make-up water and the low-temperature chilled water prepared by the water-cooling tower, which is sprayed from top to bottom from the tower top, and the air and water are fully contacted in reverse for heat exchange. Under t

Regulation of liquid nitrogen throttle valveThe opening of the liquid nitrogen throttle valve not only affects the reflux ratio of the upper tower, but also affects the reflux ratio of the lower tower. When the opening is increased, the reflux ratio of the upper tower increases, while the reflux ratio of the lower tower decreases, the purity of the nitrogen in the upper tower increases, and the purity of the oxygen enriched night sky in the lower tower increases. However, after the opening is over, the purity of the liquid nitrogen decreases, and the reduction of the reflux ratio of the upper tower is also detrimental to the improvement of the purity of the liquid oxygen. Therefore, an equilibrium point should be found for the opening of the liquid nitrogen throttle valve. We can generally use the purity difference between liquid nitrogen and gas nitrogen to judge whether the opening is appropriate. Generally, the purity of the sprayed liquid nitrogen is equal to that of the upper towe