Study of geometry and operational conditions on mixing time, gas hold up, mass transfer, flow regime and biomass production from natural gas in a horizontal tubular loop bioreactor

A horizontal tubular loop bioreactor (HTLB) was used for production of biomass from natural gas. Hydrodynamic characterizations (mixing time and gas hold up) and mass transfer coefficients were considered in the HTLB (L=2.2 m, H=0.4 m and D=0.03 m) as functions of design parameters, i.e., horizontal length to diameter ratio (L/D) and volume of gas–liquid separator (S) as well as operational parameters, i.e., superficial gas and liquid velocities (UsG, UsL). In addition, flow regime in different gas and liquid flow rates was investigated. It was observed from experimental results that UsL has remarkable effects on gas hold up and kLa due to its influence on mixing time. The volumetric mass transfer coefficients for oxygen (kLaO2)(kLaO2) and methane (kLaCH4)(kLaCH4) were determined at different geometrical and operational factors. In average, the amount of oxygen consumption for metabolism is approximately 1.4 times higher than that of methane. In bubble flow regime, the HTLB was used for biomass production, too. A gas mixture of 50% methane and 50% oxygen (based on results of dry cell weight, optical density and doubling time) was the best gas mixture inlet for biomass production. The empirical correlations for mixing time, gas hold up and kLa in terms of UsG, UsL, L/D and volume of gas–liquid separator were obtained and expressed separately.

[1]  J. C. Garver,et al.  Batch‐ and continuous‐culture studies of a methane‐utilizing mixed culture , 1980, Biotechnology and bioengineering.

[2]  N. Slater,et al.  Tracer dispersion in a laboratory air-lift reactor , 1983 .

[3]  D. Meister,et al.  The tubular loop fermentor: Oxygen transfer, growth kinetics and design , 1977, Biotechnology and bioengineering.

[4]  B. Sheehan,et al.  Production of bacterial cells from methane. , 1971, Applied microbiology.

[5]  Chen Dongyan,et al.  Removal of ethyl acetate in air streams using a gas–liquid–solid three-phase flow airlift loop bioreactor , 2005 .

[6]  Maria Gavrilescu,et al.  Mixing studies in external-loop airlift reactors , 1997 .

[7]  J. Ramsay,et al.  On‐line estimation of dissolved methane concentration during methanotrophic fermentations , 2006, Biotechnology and bioengineering.

[8]  B. Han,et al.  Effect of Horizontal Connection Pipe Length on Gas Holdup and Volumetric Oxygen Transfer Coefficient in External-Loop Airlift Reactor , 1990 .

[9]  Prasanta Kumar Das,et al.  Flow regime identification of two-phase liquid-liquid upflow through vertical pipe , 2006 .

[10]  이원국,et al.  외부순환형 이중기포탑내의 기체체류량과 총괄부피 산소전달계수에 대한 수평연결관 길이의 영향 , 1990 .

[11]  Jose C. Merchuk,et al.  The role of the gas—liquid separator of airlift reactors in the mixing process , 1990 .

[12]  J. Zeyer,et al.  Methanotrophic activity in a diffusive methane/oxygen counter-gradient in an unsaturated porous medium. , 2007, Journal of contaminant hydrology.

[13]  B. Kristiansen,et al.  Citric acid production and morphology of Aspergillus niger as functions of the mixing intensity in a stirred tank and a tubular loop bioreactor , 1998 .

[14]  D. H. Phillips,et al.  Aeration in Fermentations , 1961 .

[15]  D. Petrovic,et al.  PREDICTION OF MIXING TIME IN AIRLIFT REACTORS , 1995 .

[16]  Gabriel Wild,et al.  Hydrodynamics and flow regimes in external loop airlift reactors , 1999 .

[17]  B. Volesky,et al.  Batch production of protein from ethane and ethane-methane mixtures. , 1971, Applied microbiology.

[18]  Yusuf Chisti,et al.  Mass transfer in external-loop airlift bioreactors using static mixers , 1990 .

[19]  Bjorn Kristiansen,et al.  Design of a Tubular Loop Bioreactor for Scale‐up and Scale‐down of Fermentation Processes , 2003, Biotechnology progress.

[20]  J. Markoš,et al.  Measurement of mass transfer coefficient in an airlift reactor with internal loop using coalescent and non‐coalescent liquid media , 2004 .

[21]  C. W. Robinson,et al.  Mixing characteristics of external-loop airlifts: non-Newtonian systems , 1993 .

[22]  Howard Dalton,et al.  The Leeuwenhoek Lecture 2000 The natural and unnatural history of methane-oxidizing bacteria , 2005, Philosophical Transactions of the Royal Society B: Biological Sciences.

[23]  M. Jahanshahi,et al.  PRODUCTION OF SINGLE CELL PROTEIN FROM NATURAL GAS: PARAMETER OPTIMIZATION AND RNA EVALUATION , 2005 .

[24]  Johannes Tramper,et al.  Estimation of axial dispersion in individual sections of an airlift-loop reactor , 1989 .

[25]  R. Whittenbury,et al.  Enrichment, isolation and some properties of methane-utilizing bacteria. , 1970, Journal of general microbiology.

[26]  P. Weiland,et al.  Influence of Draft Tube Diameter on Operation Behavior of Airlift Loop Reactors , 1984 .

[27]  Hassan Gomaa,et al.  Using in-line static mixers to intensify gas-liquid mass transfer processes , 2005 .