Turbid milky white sediment is found in liquid oxygen, and the sediment is snow-like, volatilizing as the temperature rises, which is obviously caused by carbon dioxide entering the tower. Carbon dioxide entering the tower is caused by the poor operation of the purifier or the aging of molecular sieve and other factors. Therefore, you must pay attention:
1) for water-cooled purifiers, when heating them, they must follow the operation sequence of releasing water first, adding water to cool them in the blowing and working period. When heating, there is cold water in the periphery, which will make the molecular sieve around the purifier have imperfect regeneration and gradually lose the adsorption effect.
2) the outlet temperature of recycled gas and the amount of recycled nitrogen (not too small) should be well matched. After the outlet temperature of the purifier reaches the requirement, it needs to be heated for a period of time and then blown cold. When blowing cold, the outlet temperature should rise at first and then decrease. As for the temperature rising to, it should comply with the operating instructions.
3) the failure of the purifier is often related to the abnormal operation of the three-stage cooler (referring to leakage) and the improper blowing of the water separator, that is, water enters the purifier. Check whether the cooler leaks when parking. Because when parking, water will enter the air cooling tube from the gap, and when driving again, water will enter the purifier. The water separator should be blown off regularly according to regulations, and the blowing-off method should be appropriate. Some water separators are not well designed and blow off too fiercely, so the water is not blown away, which leads to the water entering the purifier. It is better not to connect the blow-off pipe with the main pipe, otherwise, it is impossible to judge whether the moisture has been blown away. Blow off slowly. Especially in summer, the temperature is high and there is a lot of water, so special attention should be paid to the operation.
4) the general service life of the molecular sieve is 2000 h, which is equivalent to long-term operation. The purifier which is switched every 8 h is replaced every 4 to 5 years.
5) the air temperature before entering the molecular sieve purifier should be reduced as much as possible. One is that it can reduce the inflow of moisture; the other is that it can improve the adsorption capacity of the molecular sieve.
6) regularly measure the content of carbon dioxide in the gas at the air outlet pipe of the purifier. It is better to be equipped with automatic carbon dioxide analyzer, but the price is relatively high. The volume fraction of carbon dioxide in the outlet air of the purifier should be less than 2×10-6. Once the turning point is reached, the content of carbon dioxide will increase linearly. Therefore, knowing the turning point, the working cycle of the purifier should be switched about half an hour in advance to ensure that carbon dioxide is not brought into the tower.
