The influence of fluid-mechanical characteristics of the system on the volumetric mass transfer coefficient and gas dispersion in three-phase system

Abstract

Distribution of gas bubbles and volumetric mass transfer coefficient, kLɑ in a three phase system with different types of solid particles at different operation conditions were studied in this paper. The ranges of superficial gas and liquid velocities used in this study were 0.03-0.09 m/s and 0-0.1 m/s, respectively. The three different types of solid particles were used as a bed in the column (glass, dp of 3 and 6 mm and ceramic, dp of 6 mm). The experiments were carried out in 2D plexiglas column, 278 mmx20.4 mmx500 mm, and in cylindrical plexiglas column with the diameter of 64 mm and hight of 2000 mm. The kLɑ coefficient increases with gas and liquid velocities. The results show that the volumetric mass transfer coefficient has higher values in three phase system with solid particles in comparison to two phase system. The particles' properties (diameter and density) have major impact on oxygen mass transfer in three phase systems.

U ovom radu je proučavana distribucija mehurova i zapreminski koeficijent prenosa mase, kLɑ, u trofaznom sistemu, sa sferičnim česticama od stakla i keramike različitog prečnika pod različitim operativnim uslovima. Brzine gasa su se kretale u intervalu 0,03-0,09 m/s, a brzine tečnosti 0-0,1 m/s. Ispitivanja su se izvodila u kolonama od pleksiglasa različitih geometrija. 2D kolona dimenzija 278 mmx20,4 mmx500 mm i cilindrična kolona, prečnika 64 mm i visine 2000 mm. Rezultati su pokazali da prisustvo čestica u sistemu doprinosi povećanju zapreminskog koeficijenta prenosa mase, a da sa povećanjem brzine gasa i tečnosti njegova vrednost nastavlja da raste. Vrednost povećanja zapreminskog koeficijenta prenosa mase, u konkretnim fluido-mehaničkim uslovima, zavisi od karakteristika samih čestica.