Air separation oxygen production area: [Weekly Topic] Week 9 of 2011——How to avoid the impact of deploying the argon system on the main tower

We fed liquid air into the crude argon condenser very early on, when the oxygen purity was high! Of course, we poured it in gradually, so the impact on the main tower was minimal. Before starting the pump, we slightly reduced the flow rate of the oxygen valve and the liquid nitrogen throttle valve; there were no instances of issues with oxygen purity. It might also be related to the equipment.

The last edit to this post was made by gader on 2011-7-13 at 17:01; when operating the argon purification system, it is important to pay attention to the hydrogenation deoxygenation process. The operation of the hydrogenation deoxygenation reactor can only be carried out when the oxygen content in the crude argon is below 2%. When the oxygen content in the crude argon is below 2%, start the hydrogen compressor and purge the hydrogen pipeline with pure nitrogen. Hydrogenation can only be carried out after confirming that the displacement has been done thoroughly and correctly. Generally, the hydrogen addition amount should be the amount required for complete reaction between hydrogen and oxygen, plus an additional 1% excess hydrogen. The purpose is to ensure complete reaction of oxygen in the crude argon, thereby further improving the purity of the refined argon. When hydrogenation is started according to the calculated amount, the process should proceed slowly. When the hydrogen addition reaches about 10% of the calculated value, pay attention to the temperature of the reaction furnace. Once the temperature of the reactor gradually rises and reaches stability, hydrogenation can be continued until the calculated value is reached. Check whether the temperature of the deoxidizer is below 450°C. After the temperature gradually stabilizes, the excess hydrogen analyzer is put into use. About 1 hour after the excess hydrogen level reaches 1%–2%, prepare to use the oxygen analysis instrument (before analyzing the process argon, manually check its oxygen content to ensure it is below around 10-5, in order to prevent damage to the instrument due to trace amounts of oxygen). When the oxygen content in the process argon is less than 10-6, the operation of the refined argon column can be initiated.

We use internal compression; I usually increase the frequency of the argon pump while raising the oxygen production volume, and at the same time increase the flow rate of the argon fraction. The results are satisfactory, as the low oxygen production volume ensures that the purity remains high. However, the adjustment of the frequency happens quite slowly.

Reply to 1# gader: The situation you described is known as argon blockage. As the operation of the crude argon column gradually returns to normal, the crude argon produced is not delivered promptly to the refined argon column; instead, it accumulates at the bottom of the crude argon column and is pumped back up using a crude argon pump. This results in a large amount of argon accumulating in the middle section of the upper column. If this is not corrected in time, it can severely affect the purity of oxygen. Therefore, when feeding argon to the tower, it is important to note that once the crude argon tower is operating properly, qualified crude argon liquid should be promptly sent to the refined argon tower; at the same time, the oxygen content in the lower part of the crude argon tower should not be kept too low.

I agree with the opinion from the second floor: bring the heavy argon system along when driving, and pay attention to controlling the flow rate of the liquid argon pump back to the tower during the adjustment process.

Focusing on this issue, I agree with the approach suggested on the second floor. The main idea is that once an issue arises in the argon column after the argon system is put into use, the liquid should be left in that column, so as to prevent large amounts of crude argon from being pumped back up to the main column, thereby avoiding impacts on it.

The process on the third floor falls under the category of obsolete methods; nowadays, argon is produced through pure distillation without the use of hydrogen.

Yes, pre-cool the argon tower and the main tower simultaneously before starting up. This helps to minimize the negative effects of large temperature differences on the equipment; before starting the argon pump, it is sufficient to slightly reduce the flow rates of the oxygen and nitrogen gases, as well as to make minor adjustments to the operating conditions of the upper column, without affecting the purity of the product...............

Before putting the crude argon column into operation, the following conditions must be met: (1) The conditions in the main column must be stable, with the operating pressure and resistance being essentially normal； (2) The quality of oxygen and nitrogen in the product is generally satisfactory, with the oxygen purity exceeding 99%. (3) The cooling capacity must not only achieve equilibrium but also have a sufficient surplus.

Reply to 7# 4600881: It is sent back to the top of Tower 1 for crude argon, using a full low-pressure distillation process to produce argon