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, k L a 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, d p of 3 and 6 mm and ceramic, d p of 6 mm). The experiments were carried out in 2D plexiglas column, 278 mm×20.4 mm×500 mm, and in cylindrical plexiglas column with the diameter of 64 mm and hight of 2000 mm. The k L a 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.

Fenton process in dispersed systems for industrial wastewater treatment

“…Rezultati su pokazali da prisustvo čestica u sistemu doprinosi povećanju zapreminskog koeficijenta prenosa mase kiseonika iz gasovite u tečnu fazu, a da sa povećanjem brzine gasa i tečnosti njegova vrednost nastavlja da raste. Dobijene vrednosti u ovom eksperimentu za kLa se kreću u opsegu 0,011 -0,195 s -1 , u zavisnosti od protoka fluida i tipa čestica [34].…”

“…Studija je pokazala da sa povećanjem dimenzija staklenih čestica, sferičnog oblika, sa 3 na 6 mm, koje se najviše koriste u trofaznim sistemima, dolazi do povećanja zapreminskog koeficijenta prenosa masa kiseonika [35]. Vrednost povećanja zapreminskog koeficijenta prenosa mase, zavisi od karakteristika samih čestica i mora se ispitati za svaki specifičan slučaj [34]. Podešavanje protoka fluida u anularnoj zoni, podešavanje brzine cirkulacije čestica, niži pad pritiska, dobar prenos mase, kao i jednostavna kontrola operativnih uslova kao što su pH vrednost, temperatura, velika zapremina fluida koja može da se procesuira, su karakteristike ovakvih sistema.…”