Users reported that the on-line analyzer of a 30000 grade air separation plant showed that the outlet CO₂of the molecular sieve suddenly increased from the normal value of 0.43×10-6 to 120×10-6, and the temperature difference in the expansion air channel entering the two high-pressure plate fin heat exchangers began to expand. At the same time, the temperature in front of expander also decreased from - 105°C to - 132°C with liquid entrainment.
After receiving the user's notice, DEAR air separation sent technical personnel to the site for observation and detection. It was found that the location of the self-cleaning filter of the equipment was close to the chemical boundary area. When the wind direction was in the downwind direction of the chemical industry boundary area, the phenomenon that the concentration of CO₂ in the air at the inlet of the self-cleaning filter of the air compressor exceeded the standard.
In view of this phenomenon, the following opinions are given:
1.Shorten the switching cycle of molecular sieve adsorber: appropriately shorten the switching cycle of molecular sieve adsorber, shorten the time of heating, cold blowing and adsorption, and ensure that the adsorption capacity of molecular sieve is switched to the regeneration process before the adsorption capacity declining.
2.Regular detection ofCO₂concentration: operators use portable gas detector to detect the inlet of air filter every hour. Once the concentration of carbon monoxide in the air is found to be higher than the normal value, the air separation unit shall be operated under load reduction in time.
3.Load reduction operation of the plant: under the condition that the concentration of CO₂in the atmospheric environment exceeds the standard, it is necessary to reduce the air supply volume of the air compressor, so that the total amount of carbon monoxide in the air passing through the molecular sieve adsorber will be reduced, and the air separation plant will be operated at reduced load at the same time. The normal operation of the equipment can be resumed when theCO₂concentration at the inlet of the self-cleaning filter is reduced to the normal value.
