Purpose of large air separation unit

After the argon fraction is extracted from the top Tower, it enters into the crude argon tower and conducts the separation of oxygen and argon by the rectification method. Generally, the components of crude argon from the top of the crude argon tower are: argon is more than 98%, nitrogen is less than 0.5%, and oxygen is less than 1.5%. Import Crude argon with purity over 98% into molecular sieve adsorber. There are two adsorbers in each group. One is equipped with 5A Molecular sieve to absorb nitrogen in crude argon; the other is equipped with 4A molecular sieve to absorb oxygen in crude argon. In order to release the adsorbents, two groups of adsorbents need to be set up to switch to use. The adsorber works at the temperature of 90 K. The crude argon enters into 5A Molecular sieve adsorber to remove nitrogen first, and then enters into 4A molecular sieve adsorber to remove oxygen. The process is shown in Figure 18. The gas from a group of molecular sieve adsorbers has a purity of 9...

The main causes are as follows: 1. The structure is unreasonable, the welding seam is concentrated and the welding joint stress is too large. 2. When welding, the molten pool is too large and overheated, and the alloy is burnt too much. 3. The arc crater is not filled due to too fast arc closing and too early wire drawing. 4. Material problems, for example, when Mg content is less than 3%, and impurities such as Fe and s exceed the standard, it is easy to cause cracks. When the melting temperature of welding wire is too high, liquefaction cracks in heat affected zone are easy to occur. Preventive measures include: 1. During the design, attention should be paid to the reasonable arrangement of welding seams, avoiding the stress concentration as far as possible, and selecting the welding sequence reasonably. 2. Reduce welding current or increase welding speed properly. 3. The arc stopping operation technology should be correct, and the arc pit should be filled by adding the ou