The air volume in the air separation equipment has an impact on the distillation tower from various aspects such as temperature distribution, pressure, separation efficiency, and product purity.
When the amount of processed air increases, it will cause an increase in the rising vapor in the distillation tower, and the amount of liquid required to condense in the main cooler will also increase accordingly, so it has no effect on the reflux ratio in the tower. Within a certain range of increased air volume, the purity of oxygen and nitrogen can remain basically unchanged, while the yield will increase proportionally with the increase of air volume. However, as the amount of condensed liquid in the main cooler increases, the heat load on the main cooler also increases. When the heat transfer area is insufficient, the temperature difference of the main cooling system will inevitably increase, and the pressure in the lower tower will correspondingly rise. At the same time, due to the increase in airflow velocity inside the tower, the amount of liquid flowing downstream increases, and the liquid layer on the tray thickens, resulting in an increase in resistance on the tray and a corresponding increase in pressure in the upper and lower towers. This will have adverse effects on the separation of oxygen and nitrogen, while also increasing power consumption. When the gas volume is too large, the resistance of the tray and the resistance of the downstream liquid flowing through the overflow hopper will increase significantly, causing the liquid level in the overflow hopper to rise and even resulting in liquid flooding where the liquid cannot flow down. This will disrupt the normal operating conditions of the distillation tower. In addition, due to the increase in rising vapor flow rate, it is easy to carry liquid droplets to the previous tray, which affects the distillation effect, reduces nitrogen purity, and thus lowers the oxygen extraction rate.
The air volume of the air separation equipment directly affects the separation performance, product purity, and energy consumption of the distillation tower. Reasonably controlling the air volume to operate within the designed load range of the equipment is the key to ensuring distillation efficiency and economy.
