|
Résumé :
|
Gas–liquid mass-transfer behaviors in aqueous alcohol solutions were studied in an internal-loop airlift reactor of 5-m height and 0.28-m i.d. in the superficial gas velocity (Ug) range from 2.0 to 10.0 cm/s. Air and aqueous n-butanol solutions were used as the gas and liquid phases, respectively. It was found that the volumetric mass-transfer coefficient decreased with increasing n-butanol concentration (CA) below a critical CA value of 0.5 wt % and increased with increasing CA above this concentration. To confirm this result, further experiments were also carried out in a bubble column of 0.12-m i.d. at Ug = 6 cm/s, and similar results were obtained. Further analysis showed that the value of kla/αg was independent of the superficial gas velocity and equal to 0.21 1/s in the air–water system; however, it decreased with increasing CA up to 0.25 wt % in n-butanol solutions, and further addition of n-butanol had no effect on kla/αg. A critical CA value of 0.5 wt % was also found for the liquid-side mass-transfer coefficient (kl). Below this concentration, kl decreased with increasing CA, whereas above this concentration, further addition of n-butanol had no effect on kl.
|
