In the conventional argon production method, the argon content extracted from the distillation column is up to 9% ~ 12% argon fraction, and then conduct oxygen-argon separation in the crude argon tower to obtain the crude argon composed of 96% Ar + 2.5% O2 + 1.5% N2. Then, after hydrofining, deaerating and purifying, finally realize the separation of argon and nitrogen in the refined argon Tower, and obtain 99.999% of the refined argon products.
The hydrofining method is a traditional argon refining method to remove the oxygen from the crude argon. Pure hydrogen is added into the crude argon by using the chemical principle, oxygen and hydrogen in crude argon are synthesized into water under the catalytic action of palladium catalyst, and release heat. About 1% of oxygen can raise the tower temperature by 230 ℃.
After hydrofining, the crude argon is cooled down by the cooler, and the generated water is removed, and then the trace water is removed by the activated alumina Dryer. The oxygen content of the obtained crude argon is 1×10-6 ~ 2×10-6, the content of argon is about 97%, and the rest is nitrogen. This method has complex technological process, low extraction rate of products, high cost of equipment and operation, and poor safety.
The so-called fully rectified argon production means removing all the oxygen and nitrogen in the distillation argon to get high purity argon. Usually, the separation of argon-nitrogen is realized by the method of total rectification. Because the boiling point difference of oxygen-argon under normal pressure is only 3 K, which is very close, it needs about 150 ~ The actual number of 180 theoretical Tower plates separated by sieve tower needs 170 ~ 200 tower plates, calculated by the resistance of each tower plate is 0.3kPa, the differential pressure generated by 170 Tower plates is 51kPa. The condensation of the crude argon steam on the top of the crude argon tower is evaporated by the oxygen-enriched liquid on the other side of the condenser, and the pressure on the evaporating side is balanced with the operating pressure in the middle of the upper tower, the temperature and pressure at the top of the crude argon tower can be determined, while the pressure at the entrance of the distillation argon at the bottom of the crude argon tower depends on the pressure at the middle and bottom of the upper tower. In this way, the total pressure difference of the coarse argon tower is limited, estimated at 5 ~ 18kPa, allow to set 50 ~ 60 Tower plates, so the oxygen content of argon obtained by rectifying in the crude argon tower can only be 2% ~ 3%.
Regular stuffing every time the pressure drop of theoretical Tower plate is about 1/8 of that of every theoretical screen plate, in this way, the regular stuffing equivalent to 170 theoretical Tower plates can be set within the allowable pressure drop range of crude argon Tower, realize the full rectification separation of oxygen-argon. In order to reduce the height of the crude argon Tower, the second-level crude argon tower is often set up, and the technological process is shown in Figure 17. The oxygen content in the outlet argon of the first-class crude argon tower is 2% ~ 3%, the oxygen content in the outlet of the second-level crude argon tower is less than 10-6, and it can directly enter the refined argon tower for rectification.
Compared with the two, the whole rectification method argon process has the advantages of simplified process, convenient operation, safety and stability, and high extraction rate of argon. Although the equipment investment is a little higher at present, with the development of structured stuffing, this technology has great promotion value.
