A COMBINED VACUUM AND TEMPERATURE SWING ADSORPTION PROCESS FOR THE RECOVERY OF AMINE FROM FOUNDRY AIR

The removal and recovery of an amine from waste air of a foundry by ad sorption is discussed on the basis of experiments and simulation studi es. The results show that activated carbons as well as a hydrophobic Y -zeolite are well suited for the purification. Since parts of the amin e are chemically bound to the adsorbents, a decrease in adsorption cap acity is found for both adsorbents after the first cycles. For the des orption and recovery, a combined vacuum and temperature swing (VTSA) t echnique is used. To achieve a sufficient degree of regeneration witho ut using too low pressures, a small amount of purge gas is added durin g the vacuum desorption. This allows the condensation to be performed at an ambient temperature (10-20 degrees C). In experiments with a sin gle adsorption column as well as in cyclic experiments with a three co lumn setup it was shown that more than 95% of the continuously fed ami ne can be removed and recovered from the waste air. The further purifi cation down to the required clean gas concentration has to be done in a second purification step, e.g. a bio-filter. (C) 1997 Elsevier Scien ce S.A.