A Numerical Study on Bed Temperature and Gasifying Agent Effetcs on the Sugarcane Bagasse Gasification Process

Catalytic tar removal is one of the main challenges restricting the successful commercialization of biomass gasification. Hot gas cleaning using a heterogeneous catalyst is one of the methods used to remove tar. In order to economically remove tar, an efficient low-cost catalyst should be applied. Biomass char has the potential to be such a catalyst. In this work, the reactor parameters that affect the conversion of a model tar component “naphthalene” were investigated employing an in situ thermogravimetric analysis of a fixed bed of biomass char. The following reactor and catalyst parameters were investigated: bed temperature (750 to 900 °C), gas residence time in the char bed (0.4 to 2.4 s), char particle size (500 to 1700 μm), feed naphthalene concentration, feed gas composition (CO, CO2, H2O, H2, CH4, naphthalene, and N2), char properties, and char precursor. It was found that the biomass char has a high activity for naphthalene conversion. However, the catalytic performance of the biomass char was affected by the gasification reactions that consumed its carbon, and the coke deposition that reduced its activity. Furthermore, high ash and iron contents enhanced char activity. The results of this work will be used in the design of a process that uses biomass char as an auto-generated catalyst in the gasification process.

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An increase in bed temperature on gasification of dual reactor fluidized bed

E3S Web of Conferences ◽

10.1051/e3sconf/20186702059 ◽

2018 ◽

Vol 67 ◽

pp. 02059

Author(s):

I Nyoman Suprapta Winaya ◽

I Ketut Gede Wirawan ◽

I Wayan Arya Darma ◽

I Putu Lokantara ◽

Rukmi Sari Hartati

Keyword(s):

Fluidized Bed ◽

Gas Production ◽

304 Stainless Steel ◽

Fluidized Bed Reactors ◽

Endothermic Reaction ◽

Gasification Process ◽

Bed Temperature ◽

Superficial Gas Velocity ◽

Bed Material ◽

Co Gas

One of the main issues using biomass as fuel in air gasification is the dilution of its product gas by the nitrogen in the air. A dual reactor fluidized bed (DRFB) overcomes this problem in which the gasification and combustion reactions are decoupled and conducted in two separate fluidized bed reactors connected by circulating bed material. The DFRB unit made of 304 stainless steel pipe with a height of 100 and 150 cm, and inner diameters (i.d.) of 15.2 and 5.1 cm for gasifier and combustor respectively. The rice husk as fuel and quartz sand as bed material having the same size of 0.4 - 0.6 mm were applied in this investigation. Since the gasification process is an endothermic reaction, gasification temperatures are varied at 600°C to 700°C while combustion reactor were kept at 600°C using the electric heaters enclosed in ceramic cover. The superficial gas velocity in this study was kept constant at 17 m/s using the external air volumetric flux of the blower flow entering the DRFB loop. Gas gasification samples are then examined by gas chromatography to determine syngas content (CO, CH4 and H2). The test results showed that by the increasing temperature of the gasification reactor there was an increase in syngas especially CO gas conentration. The temperature increases in the gasification reactor (600°C, 650°C, 700°C) is able to increase the endothermic reaction in the gasification process which is dominated by CO gas production. The syngas efficiency was found to increase from 40.95% to 43.77%.as the temperature of the gasification reactor increased.

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A Numerical Study of the Influence of Process Parameters on the Efficiency of Staged Coal Gasification Using Mixtures of Oxygen and Carbon Dioxide

Energy Systems Research ◽

10.38028/esr.2021.02.0003 ◽

2021 ◽

pp. 27-34

Author(s):

I. G. Donskoy

Keyword(s):

Carbon Dioxide ◽

Reaction Temperature ◽

Numerical Study ◽

Process Efficiency ◽

Conversion Degree ◽

Fuel Conversion ◽

Influence Of Process Parameters ◽

Gasification Process ◽

Coal Fuel ◽

Coal Particles

The paper considers a staged conversion process of pulverized coal fuel in the MHPS-type gasifier, which uses mixtures of oxygen and carbon dioxide as a gasifying agent instead of air. Similar conversion processes can be applied in the process diagrams with the capture and disposal of carbon dioxide. The research tool is a reduced-order mathematical model of coal particles' conversion in a reacting gas flow. Replacement of nitrogen with carbon dioxide leads to significant changes in the gasification process characteristics: the average reaction temperature decreases, but this decrease is partially compensated by an increase in the concentration of gaseous reactants. Thus, the gasification process efficiency and the fuel conversion degree increase. Calculations make it possible to identify a range of parameters with the highest cold gas efficiency values. The influence of oxygen concentration is estimated, the dependence of the fuel conversion degree on the reaction temperature is analyzed.

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Derivation of Entropy and Exergy Transport Equations, and Application to Second Law Analysis of Sugarcane Bagasse Gasification in Bubbling Fluidized Beds

Journal of Energy Resources Technology ◽

10.1115/1.4045541 ◽

2019 ◽

Vol 142 (6) ◽

Cited By ~ 1

Author(s):

Gabriel L. Verissimo ◽

Manuel E. Cruz ◽

Albino J. K. Leiroz

Keyword(s):

Sugarcane Bagasse ◽

Fluidized Beds ◽

Chemical Species ◽

Second Law Of Thermodynamics ◽

Transport Equations ◽

Second Law ◽

Exergy Destruction ◽

Gasification Process ◽

Second Law Analysis ◽

Biomass Particles

Abstract In the present work, the transport equations for mass, momentum, energy, and chemical species as given by the Euler–Euler formulation for multiphase flows are used together with the second law of thermodynamics to derive the entropy and exergy transport equations, suitable to the study of gas-particle reactive flows, such as those observed during pyrolysis, gasification, and combustion of biomass particles. The terms of the derived equations are discussed, and the exergy destruction contributions are identified. Subsequently, a kinetic model is implemented in a computational fluid dynamics (CFD) open source code for the sugarcane bagasse gasification. Then, the derived exergy destruction terms are implemented numerically through user-defined Fortran routines. Next, the second law analysis of the gasification process of sugarcane bagasse in bubbling fluidized beds is carried out. Detailed results are obtained for the local destructions of exergy along the reactor. This information is important to help improve environmental and sustainable practices and should be of interest to both designers and operators of fluidized bed equipment.

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Fractionation of coal through organo-separative refining for enhancing its potential for the CO2-gasification

International Journal of Coal Science & Technology ◽

10.1007/s40789-020-00348-7 ◽

2020 ◽

Vol 7 (3) ◽

pp. 504-515 ◽

Cited By ~ 2

Author(s):

Heena Dhawan ◽

Rohit Kumar ◽

Sreedevi Upadhyayula ◽

K. K. Pant ◽

D. K. Sharma

Keyword(s):

Sugarcane Bagasse ◽

Coal Gasification ◽

Ambient Pressure ◽

Fixed Bed ◽

Fixed Bed Reactor ◽

Inert Gas ◽

Coal Structure ◽

Gasification Reactivity ◽

Gasification Process ◽

Residual Coal

Abstract Coal gasification has already been extensively studied earlier under varying conditions of steam, CO2, O2, inert conditions. Belbaid coal and its e, N and NMP-DETA SCC products recovered through organo-refining under milder ambient pressure conditions were subjected to CO2-gasification in a fixed bed reactor under varying conditions. CO2 being an inert gas becomes the most challenging to be utilized during the gasification process. The SCCs showed better CO2-gasification reactivity than the raw Belbaid coal at 900 °C. The use of the catalyst K2CO3 tremendously increased the gasification reactivity for both raw coal and the SCCs. The use of sugarcane bagasse for CO2-gasification along with raw coal as well as with residual coal was also studied. Gasification under CO2 atmosphere conditions was used to structurally understand the coals as the coal structure gets loosened after extraction.

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An Experimental and Theoretical Study of the Gasification of Miscanthus Briquettes in a Double-Stage Downdraft Gasifier: Syngas, Tar, and Biochar Characterization

Energies ◽

10.3390/en11113225 ◽

2018 ◽

Vol 11 (11) ◽

pp. 3225 ◽

Cited By ~ 2

Author(s):

Tejasvi Sharma ◽

Diego Yepes Maya ◽

Francisco M. Nascimento ◽

Yunye Shi ◽

Albert Ratner ◽

...

Keyword(s):

Surface Area ◽

Reaction Model ◽

Heating Value ◽

Downdraft Gasifier ◽

Gasification Process ◽

Bed Temperature ◽

Bet Analysis ◽

Logarithmic Relationship ◽

Porosity Analysis ◽

The Impact

The goal of this work is to understand the gasification process for Miscanthus briquettes in a double-stage downdraft gasifier, and the impact of different Equivalence Ratios (ER) on syngas, biochar, and tar characteristics. The optimal ER was found to be 0.35, which yielded a syngas maximum heating value of 5.5 MJ/Nm3 with a syngas composition of 20.29% CO, 18.68% H2, and 0.86% CH4. To better understand the observed behavior, an equilibrium reaction model was created and validated using the experimental data. The model showed that the heating value decreased with increasing ER, and that hydrogen production peaked at ER = 0.37, while methane (CH4) became negligible above ER = 0.42. Tar and particle content in the gas produced at a certain temperature can now be predicted. To assess the biochar characteristics, surface structure image analysis and a surface area porosity analysis were carried out. Employing images from a scanning electron microscope (SEM), the biochar cell bonds and pore structures were examined and analyzed. By using the Brunauer-Emmett-Teller (BET) analysis of the surface porosity, the surface area to be 186.06 m2/g and the micro pore volume was calculated to be 0.07 m3/g. The final aspect of the analysis involved an evaluation of tar production. Combining current and prior data showed a logarithmic relationship between the amount of tar produced and the gasifier bed temperature, where the amount of tar produced decreased with increasing bed temperature. This results in very low tar levels, which is one of the known advantages for a double-stage downdraft gasifier over a single-stage system.

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Numerical Analysis of the Sugarcane Bagasse Drying by Cyclone

Diffusion Foundations ◽

10.4028/www.scientific.net/df.20.106 ◽

2018 ◽

Vol 20 ◽

pp. 106-123

Author(s):

J.A. Ribeiro de Souza ◽

Severino Rodrigues de Farias Neto ◽

E. Santana de Lima ◽

A.G. Barbosa de Lima ◽

H. Monteiro Lopes

Keyword(s):

Mass Transfer ◽

Gas Phase ◽

Heat And Mass Transfer ◽

Sugarcane Bagasse ◽

Numerical Study ◽

Flow Direction ◽

Tangential Velocity ◽

Reynolds Stress Model ◽

Lagrangian Model ◽

Lumped Model

Drying is a simultaneous process of heat and mass transfer and dimensional changes. In recent years, cyclones have been used as a modern drying technology. In this sense, this research proposes a numerical study to describe drying of sugarcane bagasse, using the cyclone as dryer. Herein, it was adopted the Eulerian-Lagrangian model in steady state. The Reynolds stress model was considered to describe turbulence of the gas phase, while a transient lumped model was used to describe heat and mass transfer on the particulate phase (sugarcane bagasse). Particles were considered with irregular shape, composed of a binary mixture (solid part and water). The solution of the proposed model was obtained using the commercial software Ansys CFX 12. Results of the moisture content, temperature, dimension variation, and paths of particles, as well as velocity, pressure, and temperature distributions of the gas phase inside the cyclone are presented and analyzed. It has been found that the obtained components for axial and tangential velocity inside the cyclone are in good agreement with experimental data available in the literature, and that the drying kinetics, heating, dimensional variations, and residence time of particles are affected by the velocity of the gas phase, velocity of the particles, and the flow direction of gas and particles at the entrance of the feed duct.

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Parametric gasification process of sugarcane bagasse for syngas production

International Journal of Hydrogen Energy ◽

10.1016/j.ijhydene.2019.04.127 ◽

2019 ◽

Vol 44 (31) ◽

pp. 16234-16247 ◽

Cited By ~ 6

Author(s):

Abdul Raheem ◽

Ming Zhao ◽

Wafa Dastyar ◽

Abdul Qadir Channa ◽

Guozhao Ji ◽

...

Keyword(s):

Sugarcane Bagasse ◽

Syngas Production ◽

Gasification Process

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Plasma-Augmented Fluidized Bed Gasification of Sub-bituminous Coal in CO2–O2 Atmospheres

High Temperature Materials and Processes ◽

10.1515/htmp-2014-0162 ◽

2016 ◽

Vol 35 (1) ◽

pp. 89-101

Author(s):

C. Lelievre ◽

C. A. Pickles ◽

S. Hultgren

Keyword(s):

Fluidized Bed ◽

Energy Minimization ◽

Bituminous Coal ◽

Minimization Method ◽

Gasification Process ◽

Coal Gasifier ◽

Bed Temperature ◽

Gibbs Free Energy Minimization ◽

Fluidized Bed Gasifier ◽

Hsc Chemistry

AbstractThe gasification of a sub-bituminous coal using CO2–O2 gas mixtures was studied in a plasma-augmented fluidized bed gasifier. Firstly, the coal was chemically characterized and the gasification process was examined using Thermogravimetric and Differential Thermal Analysis (TGA/DTA) in CO2, O2 and at a CO2 to O2 ratio of 3 to 1. Secondly, the equilibrium gas compositions were obtained using the Gibbs free energy minimization method (HSC Chemistry®7). Thirdly, gasification tests were performed in a plasma-augmented fluidized bed and the off-gas temperatures and compositions were determined. Finally, for comparison purposes, control tests were conducted using a conventional fluidized bed coal gasifier and these results were compared to those achieved in the plasma-augmented fluidized bed gasifier. The effects of bed temperature and CO2 to O2 ratio were studied. For both gasifiers, at a given bed temperature, the off-gas compositions were in general agreement with the equilibrium values. Also, for both gasifiers, an experimental CO2 to O2 ratio of about 3 to 1 resulted in the highest syngas grade (%CO + %H2). Both higher off-gas temperatures and syngas grades could be achieved in the plasma-augmented gasifier, in comparison to the conventional gasifier. These differences were attributed to the higher bed temperatures in the plasma-augmented fluidized bed gasifier.

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