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 the action of the water film on the surface of the packing, the heat of the compressed air is fully absorbed by the cooling water, and the temperature is reduced to the process standard range of 8 to 12 ℃. At the same time, the water washing process can effectively remove water-soluble impurities such as dust, nitrogen oxides and sulfides in the air, and condense most of the free water in the air, greatly reducing the adsorption load of subsequent molecular sieves. After cooling and impurity removal, the air is sent to the molecular sieve purification system after water mist is captured by the tower top demister and no water is carried.
In order to avoid process risks, the equipment is equipped with exclusive interlocking logic: the stable pressure in the tower must be established before the spraying water supply can be put into use. It is strictly prohibited to spray water at normal pressure and pass water at low pressure, so as to prevent a large amount of water mist entrained by high-pressure air inlet, resulting in failure of molecular sieve with water, freezing and blocking of cold box and other major equipment failures.
