DEHUMIDIFICATION OF MOIST AIR WITH SIMULTANEOUS REMOVAL OF SELECTED INDOOR POLLUTANTS BY TRIETHYLENE GLYCOL SOLUTIONS IN A PACKED-BED ABSORBER

A packed bed absorber-stripper system was used to remove selected indo or pollutants during the dehumidification of air by triethylene glycol solutions. Triethylene glycol concentrations of 90% and 95% by weight in water were used. Both random and structured packings were employed to provide the contact surface between the liquid and gas phases. A s ix-inch I. D. absorption column was operated between 50% and 80% of fl ooding conditions. The heights of a transfer unit for mass transfer fo r randomly packed 5/8-inch polypropylene Flexi rings and 1/2-inch cera mic Intalox saddles varied from 0.12 m to 0.17 m when dehumidifying ai r only. However, the height of a transfer unit was in the range of 0.3 1 m to 0.40 m for the cross corrugated cellulose and PVC structured pa ckings. Heat and mass transfer coefficients were also calculated from the experimental data and were correlated with various process variabl es. The values predicted by these correlations were within +/- 10% of the experimental data. Pollutants used in the study included formaldeh yde, toluene, 1,1,1-trichloroethane and carbon dioxide, and their conc entrations in the air were controlled to 0.02 +/- 0.005 ppm, 3 +/- 0.0 2 ppm, 24 +/- 0.1 ppm, and 1000 +/- 5 ppm; respectively. Although near ly 100% of the toluene and 1,1,1-trichloroethane were removed by the 9 5% triethylene glycol solution, only 56% of the carbon dioxide and 30% of the formaldehyde could be removed from the air stream under simila r conditions. As expected, the removal of these pollutants by the trie thylene glycol solution was not affected by varying the relative humid ity of the air.