The state of sulfur gas production in Ukraine has been examined. The major producers and consumers of sulfur, as well as available technologies for gases purification from hydrogen sulfide have been characterized. The necessity of applying new methods of gas cleaning from hydrogen sulfide to form sulfur of special grades has been grounded. The advantages of quinhydrone cleaning method to form fine sulfur have been shown.
The enhancement factor of air oxygen absorption by quinhydrone absorbing solution in the apparatus with a continuous bubbling layer and the rate constant for the reaction of chemisorbed oxygen and the reducing form of quinhydrone oligomers have been determined. The obtained results are of practical importance for the choice of mass-transfer apparatus for the regeneration of quinhydrone absorbing solution when removing hydrogen sulfide from gases.
Change of the properties of soda solution of quinhydrone during their exposure in the presence of air has been investigated by the methods of cyclic voltammetry and spectroscopy (IR and UV). It has been shown that in the process of exposure of the solution occurs the process of quinhydrone oligomerization and changes its redox properties. The redox potential of the solution increases, the pH decreases, the currents of oxidation peaks decrease and completely dampen, indicating the stabilization of the properties of the oligomer. It has been established that the oxidizing forms of the oligomer are still present in the quinhydrone catalyst solution for more than 8 years and the solution does not lose oxidizing properties to chemisorbed hydrogen sulfide.
Dissolved oxygen may be contained in the absorbing solution after the stage of its regeneration by air oxygen in line with reaction (3). Oxygen in the solution also causes an adverse reaction of the formation of sodium thiosulfate
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 1.510–3 m to 3.010–3 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 2.00.5 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.
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