Theoretical studies of H2S, SO2 and O2 absorption in mass exchanged apparatus with a continuous bubbling layer and mechanical dispersion of an absorbent

Abstract

The paper reports the results of theoretical studies on kinetic and technological characteristics of oxygen, hydrogen sulfide and sulfur(IV) oxide absorption by water in mass-transfer apparatus of two various types: absorber with a continuous bubbling layer (AСBL) and horizontal absorber with bucket-shaped dispersers (HABD). The main purpose of these studies was the theoretical reasoning for the choice of mass-transfer equipment used in the purification of exhaust gases from sulfur compounds. It was shown that the resistance of the gas phase in ACBL is less than the resistance of the liquid phase by (2.75…3.78)106, (3.43…4.78)104, and (2.18…3.05)103 times for oxygen, hydrogen sulfide, and sulfur oxide, respectively; and it can be neglected when calculating the mass transfer coefficient. It was found that an increase in the diameter of the bubble from 1.510–3 m to 3.010–3 m leads to a decrease in the mass transfer coefficient by 1.63 times. It was calculated that the values of mass transfer coefficients in ACBL for H2S and SO2 are much higher than for O2, so the purification process will be controlled by the rate of oxygen absorption. It was found that the gas phase resistance during the absorption of oxygen and hydrogen sulfide for HABD has virtually no effect on the mass transfer coefficients and can be neglected. For the absorption of gases that are low-concentrated with respect to sulfur(IV) oxide, the mass transfer coefficient in HABD is determined by the resistance of the gas phase, and the optimal droplet diameter is within 2.00.5 mm. It was calculated that the technologically expedient initial speed of dispersed drops is 12 m/s, and their diameter is 1.5…3.0 mm for the industrial HABD. It was shown that the values of kinetic and technological indicators of mass transfer in HABD are several orders of magnitude higher than those in ACBL and have a significant potential for intensification.