scholarly journals Heat and Mass Transfer during Lignocellulosic Biomass Torrefaction: Contributions from the Major Components—Cellulose, Hemicellulose, and Lignin

Processes ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 959
Author(s):  
Ken-ichiro Tanoue ◽  
Kentaro Hikasa ◽  
Yuuki Hamaoka ◽  
Akihiro Yoshinaga ◽  
Tatsuo Nishimura ◽  
...  
Keyword(s):  
Gas Flow ◽  
Model Simulation ◽  
Packed Bed ◽  
Douglas Fir ◽  
Packed Bed Reactor ◽  
Reactor Wall ◽  
Measured Temperature ◽  
Reactor Performance ◽  
Rate Vector ◽  
Determining Factor

The torrefaction of three representative types of biomass—bamboo, and Douglas fir and its bark—was carried out in a cylindrical-shaped packed bed reactor under nitrogen flow at 573 K of the reactor wall temperature. As the thermal energy for the torrefaction was supplied from the top and the side of the bed, the propagation of the temperature profile of the bed is a crucial factor for discussing and improving the torrefaction reactor performance. Therefore, the temperature and gas flow rate (vector) profiles throughout the bed were calculated by model simulation so as to scrutinize this point. The measured temperature at a certain representative location (z = 30 mm and r = 38 mm) of the bed was well reproduced by the simulation. The volume faction of the bed at temperatures higher than 500 K at 75 min was 0.89, 0.85, and 0.99 for bamboo, and Douglas fir and its bark, respectively. It was found that the effective thermal conductivity is the determining factor for this difference. The heat of the reactions was found to be insignificant.

scholarly journals Gas-liquid flows through porous media in microgravity: Packed Bed Reactor Experiment-2

2021 ◽  
Author(s):  
Brian Motil ◽  
Mahsa Taghavi ◽  
Vemuri Balakotaiah ◽  
Henry Nahra
Keyword(s):  
Gas Flow ◽  
Liquid Velocity ◽  
Space Station ◽  
Particle Diameter ◽  
Packed Bed ◽  
Packed Bed Reactor ◽  
Flow Rates ◽  
Test Conditions ◽  
Superficial Gas Velocity ◽  
Liquid Flows

Experimental results on pressure drop and gas hold-up for gas-liquid flow through packed beds obtained from a second flight on the International Space Station are presented and analyzed. It is found that the gas hold-up is a function of the bed history at low liquid and gas flow rates whereas higher gas hold-up and pressure gradients are observed for the test conditions following a liquid only pre-flow compared to the test conditions following a gas only pre-flow period. Over the range of flow rates tested, the capillary force is the dominant contributor to the pressure gradient and is found to be linear with the superficial liquid velocity but is a much weaker function of the superficial gas velocity. The capillary contribution is also a function of the particle size and varies approximately inversely with the particle diameter within the range of the test conditions.

scholarly journals Treatment of milk wastewater using up-flow anaerobic packed bed reactor

2015 ◽  
Vol 17 (2) ◽  
pp. 84-88 ◽  
Author(s):  
Kiran D. Bhuyar ◽  
Sanvidhan G. Suke ◽  
S.D. Dawande
Keyword(s):  
Rural Areas ◽  
Biogas Production ◽  
Packed Bed ◽  
Dairy Wastewater ◽  
Packed Bed Reactor ◽  
Reactor Performance ◽  
Reactor Model ◽  
Loading Rates ◽  
Empirical Relations ◽  
Low Costs

Abstract An up-flow anaerobic packed bed (UAPB) bioreactor has been designed on a laboratory-scale and used for treatment of domestic milk wastewater (MWW). The UAPB bioreactor was operated under mesophilic temperature (37-45°C) and reactor performance evaluated at various organic loading rates of MWW effluent at hydraulic retention times (HRT) of 1, 2, and 3 d based on the removal of organic matter COD, BOD, SS, pH changes and biogas production. The kinetic parameters were estimated using the experimental data to develop a reactor model. Empirical relations were generated for the characteristics like COD, BOD, and SS using modeling equations. This study proved that the UAPB reactor performance is excellent for treating domestic MWW and easily biodegradable dairy wastewater influent. Hence, this system can operate at low costs, making it suited for use in the developing countries and rural areas.

Packed-bed reactor performance with immobilized lactase under thermal inactivation

1998 ◽  
Vol 23 (1-2) ◽  
pp. 3-9 ◽  
Author(s):  
A. Illanes ◽  
C. Altamirano ◽  
A. Aillapán ◽  
G. Tomasello ◽  
M.E. Zuñiga
Keyword(s):  
Thermal Inactivation ◽  
Packed Bed ◽  
Packed Bed Reactor ◽  
Reactor Performance

Parametric Study of Split Flow Cylindrical Packed Bed Reactor for High-Temperature Thermochemical Energy Storage Using Cobalt Oxide Redox Reaction

2019 ◽  
Author(s):  
Nasser Vahedi ◽  
Alparslan Oztekin
Keyword(s):  
High Temperature ◽  
Energy Storage ◽  
Pressure Drop ◽  
Parametric Study ◽  
Redox Reaction ◽  
Packed Bed ◽  
Reactor Design ◽  
Packed Bed Reactor ◽  
Reactor Performance ◽  
Split Flow

Abstract Thermal energy storage has become an integral part of Concentrated Solar Power (CSP) plants to guarantee continuous supply of power demand. For cost-effective solar power generation, the size and operating temperatures of CSP plants should be increased. Thermochemical energy storage (TCES) is the only available solution to meet energy density and high-temperature requirements. Air is mostly used as Heat Transfer Fluid (HTF) for high-temperature CSP plants. For the air-based system, metal redox reactions are good candidates as storage reactant. Application of metal oxide gas-solid redox reaction in storage systems requires an efficient reactor design. Cost-effectiveness and simplicity have made packed bed reactors a viable candidate for high-temperature applications. The high-pressure drop along the bed is the main drawback of such reactors preventing them from widespread applications. Split flow design modification could aid in reducing pressure drop while providing more flexibility in reactor performance control. A cylindrical split-flow packed bed reactor with an annulus for HTF flow is considered as a modified reactor design. The transient two-dimensional axisymmetric numerical model is developed for solving mass, momentum, and energy equations for both gas and solid phases using suitable reaction kinetics for the cobalt oxide redox reaction. A parametric study is performed on cylindrical-shaped split-flow reactor design as a basis for future optimization for complete storage cycle. The effect of split flow ratio and side-channel width on reactor performance are considered. It is shown that both parameters could be used effectively to design and optimize the reactor.

Predicting the packed-bed reactor performance with immobilized microbial lactase

2006 ◽  
Vol 41 (7) ◽  
pp. 1627-1636 ◽  
Author(s):  
Enrique J. Mammarella ◽  
Amelia C. Rubiolo
Keyword(s):  
Packed Bed ◽  
Packed Bed Reactor ◽  
Reactor Performance

Mathematical Modeling and Experimental Study of Hydrogen Production by Catalytic Steam Reforming of Methane

2013 ◽  
Author(s):  
Parham Sadooghi ◽  
Reinhard Rauch
Keyword(s):  
Steam Reforming ◽  
Packed Bed ◽  
Packed Bed Reactor ◽  
Diffusion Reaction ◽  
Reactor Wall ◽  
Radial Temperature ◽  
Heterogeneous Model ◽  
Gas Phase Kinetics ◽  
Steam Reforming Of Methane ◽  
Catalytic Steam Reforming

Steam reforming of methane in a packed bed reactor filled with Nickel based catalyst supported on Alumina, (Al2O3) is theoretically and experimentally studied and analyzed. State of the art Finite Element Method software, COMSOL Multiphysics is used to simulate a steady state two dimensional heterogeneous model, coupled with detailed reaction mechanisms modeling surface and gas-phase kinetics that takes into account the diffusion reaction phenomena inside the particles. The simulation results are compared favorably with experimental data. It is shown that strong axial and radial temperature gradients exist near the reactor wall The obtained results are important in design and optimizing of commercial reactors.

scholarly journals Hydrodynamic effects on three phase micro-packed bed reactor performance – Gold–palladium catalysed benzyl alcohol oxidation

2016 ◽  
Vol 149 ◽  
pp. 129-142 ◽  
Author(s):  
Noor Al-Rifai ◽  
Federico Galvanin ◽  
Moataz Morad ◽  
Enhong Cao ◽  
Stefano Cattaneo ◽  
...  
Keyword(s):  
Benzyl Alcohol ◽  
Alcohol Oxidation ◽  
Packed Bed ◽  
Packed Bed Reactor ◽  
Reactor Performance ◽  
Benzyl Alcohol Oxidation ◽  
Three Phase ◽  
Hydrodynamic Effects

Integrated biological treatment of recalcitrant effluents from pulp mills

2004 ◽  
Vol 50 (3) ◽  
pp. 145-156 ◽  
Author(s):  
A. Ortega-Clemente ◽  
C. Estrada-Vázquez ◽  
F. Esparza-Garcia ◽  
S. Caffarel-Mendez ◽  
N. Rinderknecht-Seijas ◽  
...  
Keyword(s):  
Organic Matter ◽  
Black Liquor ◽  
Packed Bed ◽  
Pollutant Removal ◽  
Packed Bed Reactor ◽  
Soluble Carbohydrate ◽  
Fluidised Bed ◽  
Reactor Performance ◽  
Significant Difference ◽  
Fluidised Bed Reactor

This work aimed at determining the degree of depuration of a recalcitrant effluent (weak black liquor, WBL) achieved in a series treatment consisting of a first stage methanogenic fluidised bed reactor followed by a second stage aerobic, upflow reactor packed with “biocubes” of Trametes versicolor immobilised onto small cubes of holm oak wood. The mesophilic, lab scale methanogenic fluidised bed reactor contained a microbial consortium immobilised onto granular activated carbon 500 mm average size. The process removed decreasing amounts of organic matter at decreasing hydraulic retention times (HRT), eventually reaching an average of 50% at 0.5 day HRT. Colour and ligninoid removals also decreased with decreasing HRT. Although the methanogenic fluidised bed reactor provided an effective treatment for the degradable organic matter, important concentrations of recalcitrant organic matter and colour still remained in the anaerobic effluent. This anaerobic effluent was fed to the aerobic packed bed reactor. Two HRT were tested in this unit, namely 5 and 2.5 days. The reactor averaged an organic matter removal in the range of 32% COD basis, during an experimental run of 95 days. Colour and ligninoid contents were removed in high percentages (69% and 54%, respectively). There was no significant difference in reactor performance at 5- and 2.5-day HRT. There was a positive correlation between pollutant removal efficiencies and Laccase activity in crude extracts of the reactor liquor. No supplemental soluble carbohydrate was required to sustain the fungus activity and the consistent reactor performance. Overall, the two-stage treatment achieved approximately a 78% removal of the original organic matter of the WBL (COD basis) and ca. 75% of colour and ligninoid contents.

scholarly journals The Role of Support in Formic Acid Decomposition on Gold Catalysts

Energies ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 4198 ◽  
Author(s):  
Vladimir Sobolev ◽  
Igor Asanov ◽  
Konstantin Koltunov
Keyword(s):  
Gold Nanoparticles ◽  
Catalytic Activity ◽  
Formic Acid ◽  
Gas Flow ◽  
Catalyst Support ◽  
Gold Catalysts ◽  
Packed Bed ◽  
Packed Bed Reactor ◽  
Hydrogen Carrier ◽  
Supported Gold Nanoparticles

Formic acid (FA) can easily be decomposed, affording molecular hydrogen through a controllable catalytic process, thus attaining great importance as a convenient hydrogen carrier for hydrogen energetics. Supported gold nanoparticles are considered to be among the most promising catalysts for such applications. However, questions remain regarding the influence of the catalyst support on the reaction selectivity. In this study, we have examined the catalytic activity of typical gold catalysts, such as Au/TiO2, Au/SiO2, and Au/Al2O3 in decomposition of FA, and then compared it with the catalytic activity of corresponding supports. The performance of each catalyst and support was evaluated using a gas-flow packed-bed reactor. It is shown that the target reaction, FA → H2 + CO2, is provided by the presence of gold nanoparticles, whereas the concurrent, undesirable pathway, such as FA → H2O + CO, results exclusively from the acid-base behavior of supports.

Sign in / Sign up

Export Citation Format

Share Document