1. The separation efficiency of regular packing is high, and the extraction rate of oxygen and nitrogen in the high separation equipment of the distillation tower is divided into two types: the extraction rate of the complete set of equipment and the extraction rate of the distillation tower. Due to the extraction rate of the complete set of equipment and the capacity of the air separation equipment. The production of liquid products is related to other factors, making it difficult to measure the high separation efficiency of structured packing. The extraction rate of distillation columns, especially the extraction rate of argon, can better represent the design level of air separation equipment. After actual testing, it has been found that a new type of air separation equipment has been put into operation. The oxygen extraction rate of its distillation tower has reached over 99%; The argon extraction rate has reached 79%.
The operating value of oxygen content in the upper tower polluted nitrogen is the main indicator of the extraction rate of distillation. Through actual measurement, the oxygen content in the polluted nitrogen can be less than 0.1%, and even reach 150-200x10-4%.
The high separation efficiency of regular packing tower and crude argon tower is due to the significant reduction in their operating pressure. The lower the operating pressure, the more favorable it is for the separation of oxygen, nitrogen, and argon, especially for the separation of oxygen and argon. In general, the extraction rate of oxygen can be increased by 1% to 3%; The argon extraction rate can be increased by 5% to 10%.
The extraction rate of a distillation tower largely depends on the amount of expansion air entering the tower, especially the extraction rate of argon. Therefore, continuously improving the isentropic efficiency of the turbine expander and the boost ratio of the booster is the key to improving the extraction rate of the distillation tower.
2. The gap of regular packing is large, the production capacity is high, and the tower diameter is reduced for easy transportation
The porosity of regular packing can reach over 95%. In a sieve tray tower, the area of the orifice plate accounts for about 80% of the cross-section of the tower, and the opening rate is about 8-12%, which is much smaller than the airborne rate of the packing layer. For the same load, the diameter of the packed tower is smaller than that of the sieve tray tower; In general, its cross-sectional area is only about 70% of that of a sieve plate tower, which is beneficial for transportation of large air separation equipment with reduced tower diameter.
3. Regular packing has a low liquid holding capacity, a high operating liquid to gas ratio and elasticity, and can quickly change working conditions
The operating load of sieve tray towers is limited by the leakage and flooding rate of the sieve holes, while packed towers are only limited by the flooding rate. Therefore, their operating load can vary within a large range. The design load range of packed towers can reach 40% to 120%. The oxygen production of the packed tower in the 12000m3/h air separation equipment of Shanggang Fifth Plant can be adjusted within the range of 9000-14000mm3/h, and the operating load range is only 75% to 117%.
Due to the low liquid holding capacity of packed towers, which is generally only 1% to 6% of the tower volume, while the liquid holding capacity of sieve plate towers is 8% to N% of the tower volume, the low liquid holding capacity means that the liquid stays in the tower for a short time, the operating pressure drop is small, and it is also conducive to variable operating conditions, but it needs to be verified in actual variable operating conditions in the future.
4. The startup time of the device has been significantly reduced
The start-up process of air separation equipment operates without product output, so shortening the start-up time is one of the ways to save energy and reduce consumption of air separation equipment. The start-up time of air separation equipment refers to the time required to start the expansion machine until oxygen is discharged. After using fresh packing in the upper tower, the amount of liquid held during normal distillation is significantly reduced, which greatly shortens the start-up time of the air separation equipment.
