Gas–liquid mass transfer in three‐phase inverse fluidized bed reactor with Newtonian and non‐Newtonian fluids

Abstract

Liquid-phase volumetric mass transfer coefficients, k L a were determined in three-phase inverse fluidized beds of low-density polyethylene (LDPE) and polypropylene (PP) spheres fluidized by a countercurrent flow of air and Newtonian (water and glycerol solutions) or non-Newtonian liquids [carboxy methyl cellulose (CMC) solutions]. The effects of liquid and gas velocities, particle size, solid loading and addition of organic additives (glycerol and CMC) on the volumetric mass transfer coefficient, k L a were determined. The superficial liquid velocity had a weak effect on the mass transfer whereas the gas flow rate affected the mass transfer positively. k L a increased with increase in particle diameter and decreased with increase in initial bed height (solid loading). k L a decreased as the concentration of glycerol (viscosity) and CMC increased. Empirical correlations are presented to predict the gas-liquid volumetric mass transfer coefficient in terms of operating variables. 

Numerical study of co‐axial bubble coalescence characteristics

“…The operating pressure had been set to be equal to the atmospheric pressure, i.e. 101 325 Pa, and the gravitational force ( g ) of 9.81 m/s has been assigned along negative (‐ve) Y‐direction.…”

“…The performance of the bubble column primarily depends on bubble flow dynamics, bubbles coalescence and bubble break up phenomenon. These types of phenomenon make a suitable mixing between gas and liquid phases by changing the interface areas as well as increase heat and mass transfer between the phases . Now days, bubble column reactor is broadly used as the equipment of gas–liquid interface area in different industrial applications such as chemical, petrochemical and pharmaceutical industries, and relating reactions, namely, oxidation, alkylation and hydrogenation; eventually used as bioreactors to make a precious product such as enzymes, proteins and antibiotics .…”

Microfluidic bubbler facilitates near complete mass transfer for sustainable multiphase and microbial processing

“…Below the peak rate, the K L a decreases because there is a smaller amount of total gas mass released into the liquid. Less oxygen is introduced to the system due to the low flow rates and bubble generation frequency, causing the dissolved oxygen concentration to not increase as rapidly, lowering the overall K L a (Badino et al, 2001;Haribabu and Sivasubramanian, 2013;Sivasubramanian, 2010).…”

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

“…Istraživanja su pokazala da zapreminski koeficijent prenosa mase zavisi od distribucije i veličine mehurova u sistemu [7], kao i da ponašanje mehurova u sistemu, koje je uglavnom uslovljeno načinom disperzije, ima direktan uticaj na prenos mase i hidrodinamiku sistema [8]. U dosadašnjom istraživanjima ispitivan je uticaj različitih tipova ispune poput kamene, sta-klene, keramičke, plastične i sintetske, na prenos mase kiseonika u trofaznim sistemima [4,6,[9][10][11][12][13][14][15][16]. Ova ispitivanja su pokazala da osobine čestica koje čine ispunu, gustina i prečnik, kao i njihova količina, utiču na pojavu koalescencije, odnosno na prečnik mehura i zadržavanje gasa u sistemu [4,6,[9][10][11][12][13][14][15][16].…”

“…Rezultati nekih eksperimentalnih ispitivanja, dostupni u literaturi, pokazuju da se zapreminski koeficijent prenosa mase povećava sa povećanjem protoka tečnosti [9,12,29], dok drugi rezultati govore suprotno, da se zapreminski koeficijent prenosa mase smanjuje sa povećanjem brzine tečnosti [6,10,30].…”