Air separation plant maintenance

1. Before hoisting, check and confirm whether the crane body, crane legs, lifting rigging and wire rope meet the safety requirements and hoisting conditions. 2. The hanging points of hoisting facilities shall be confirmed to prevent deviation and inclination; steel wire rope or sling shall be used for protection of edges and corners; sling and U-ring shall be used for lifting objects. 3. The commander shall use inter-phone for command, and special personnel shall be assigned for command, and the personnel shall stand at the position where the lifting object can be fully observed; warning isolation shall be set up in the hoisting area, and no one shall stand under the lifting object. 4. For large-scale hoisting, the hoisting safety scheme shall be formulated in combination with the company's special operation system.

The reflux liquid in the upper column of the distillation column is throttled by the lower column to the liquid air and liquid nitrogen of the upper column, and the reflux ratio of the upper column is regulated by the liquid nitrogen throttle valve. When the liquid air and liquid nitrogen pass through the throttle valve, the pressure will decrease, and the corresponding saturation temperature will also be reduced. If the supercooling degree of liquid is not enough, some liquid will be vaporized. The higher the gasification rate is, the lower the reflux ratio of the upper column is, and the purity of nitrogen is affected. Therefore, in order to improve the supercooling degree of the liquid nitrogen in the night sky through the throttle valve, a subcooler is generally set up to increase the supercooling degree of the liquid nitrogen in the liquid air.