This system is comprised of two absorbers and two electric heaters. By this system air purified by the absorbers is below -65?. The purified air has a content of CO2?1 ppm and its temperature is 21?
The absorbers are of a vertical & double-bed structure. The upper bed contains molecular sieve while the lower bed activated alumina and the two absorbers work alternatively. Part of the air from the air cooling tower, after being rid of free water, CO2 and other Cn Hm via the adsorbed, enters the cold box and the braking compressor (i.e. the booster) of the turbo-expander while the rest is used as the instrument air. When one adsorbed is in operation, the other is being regenerated and cooled. The waste nitrogen from the cold box enters the adsorbed for regeneration after being heated to 180? by the electric heater to remove water and CO2 and then is vented to the atmosphere.