Simulation Research on the Fixed-Bed Gasification Process in a Two-Stage Combined Gasifier

AbstractThe present work analyzed the energy generation potential of Buriti (Mauritia flexuosa L. f.) by thermochemical reactions. The experimental part of the study performed immediate analyses, elemental analyses, lignocellulosic analysis, thermogravimetric analysis, calorific values, and syn gas concentrations measurements of the gasification of Buriti in a fixed-bed reactor. Additionally, numerical simulations estimated the syn gas concentrations of the gasification reactions of Buriti. The immediate analysis showed that Buriti has the highest ash content (4.66%) and highest volatile matter content (85%) compared to other Brazilian biomass analyzed, but the higher heating value was only 18.28 MJ.kg−1. The elemental analysis revealed that the oxygen to carbon ratio was 0.51 while hydrogen to carbon ratio was 1.74, indicating a good thermal conversion efficiency. The Lignocellulosic analysis of Buriti resulted in a high content of holocellulose (69.64%), a lignin content of 28.21% and extractives content of 7.52%. The thermogravimetry of the Buriti indicated that the highest mass loss (51.92%) occurred in a temperature range between 150 °C and 370 °C. Lastly, the experimental gasification study in a fixed-bed updraft gasifier resulted in syn gas concentrations of 14.4% of CO, 11.5% of CO2 and 17.5% of H2 while the numerical simulation results confirmed an optimal equivalence ratio of 1.7 to maximize CO and H2 concentrations. Therefore, based on the results presented by the present work, the gasification process is adequate to transform Buriti wastes into energy resources. Graphic abstract

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Deep removal of sulfur and aromatics from diesel through two-stage concurrently and countercurrently operated fixed-bed reactors

Chemical Engineering Science ◽

10.1016/j.ces.2004.09.036 ◽

2004 ◽

Vol 59 (22-23) ◽

pp. 5465-5472 ◽

Cited By ~ 20

Author(s):

Zhen-Min Cheng ◽

Xiang-Chen Fang ◽

Rong-Hui Zeng ◽

Bao-Ping Han ◽

Lei Huang ◽

...

Keyword(s):

Fixed Bed ◽

Two Stage ◽

Fixed Bed Reactors

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Influence of surface area to volume ratio of fuel particles on gasification process in a fixed bed

Energy for Sustainable Development ◽

10.1016/j.esd.2013.12.013 ◽

2014 ◽

Vol 19 ◽

pp. 122-129 ◽

Cited By ~ 30

Author(s):

Sadhan Mahapatra ◽

S. Dasappa

Keyword(s):

Surface Area ◽

Fixed Bed ◽

Volume Ratio ◽

Gasification Process ◽

Fuel Particles

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Optimization of a Biomass Micro-Gasification Process for the Production of Synthesis Gas From Palm Shell

Volume 6A: Energy ◽

10.1115/imece2015-52119 ◽

2015 ◽

Author(s):

Luz M. Ahumada ◽

Arnaldo Verdeza ◽

Antonio J. Bula

Keyword(s):

Particle Size ◽

Fixed Bed ◽

High Energy ◽

Operating Conditions ◽

Air Velocity ◽

Output Variable ◽

Heating Value ◽

Palm Shell ◽

Gasification Process ◽

Air Speed

This paper studied, through an experiment design, the significance of particle size, air speed and reactor arrangement for palm shell micro-gasification process in order to optimize the heating value of the syngas obtained. The range of variables was 8 to 13 mm for particle size, 0.8–1.4m/s for air velocity, and updraft or downdraft for the reactor type. It was found that the particle size and air velocity factors were the most significant in the optimization of the output variable, syngas heating value. A heating value of 2.69MJ / Nm3 was obtained using a fixed bed downdraft reactor, with a particle size of 13 mm and 1.4 m/s for air speed; verification of the optimum point of operation under these conditions verified that these operating conditions favor the production of a gas with a high energy value.

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Investigation of the Coal Gasification Process Under Various Operating Conditions Inside a Two-Stage Entrained Flow Gasifier

Journal of Thermal Science and Engineering Applications ◽

10.1115/1.4005603 ◽

2012 ◽

Vol 4 (2) ◽

Cited By ~ 10

Author(s):

Armin Silaen ◽

Ting Wang

Keyword(s):

Coal Gasification ◽

Operating Conditions ◽

Coal Slurry ◽

Two Stage ◽

Heating Value ◽

Fuel Distribution ◽

Entrained Flow ◽

One Stage ◽

Gasification Process ◽

Entrained Flow Gasifier

Numerical simulations of the coal gasification process inside a generic 2-stage entrained-flow gasifier fed with Indonesian coal at approximately 2000 metric ton/day are carried out. The 3D Navier–Stokes equations and eight species transport equations are solved with three heterogeneous global reactions, three homogeneous reactions, and two-step thermal cracking equation of volatiles. The chemical percolation devolatilization (CPD) model is used for the devolatilization process. This study is conducted to investigate the effects of different operation parameters on the gasification process including coal mixture (dry versus slurry), oxidant (oxygen-blown versus air-blown), and different coal distribution between two stages. In the two-stage coal-slurry feed operation, the dominant reactions are intense char combustion in the first stage and enhanced gasification reactions in the second stage. The gas temperature in the first stage for the dry-fed case is about 800 K higher than the slurry-fed case. This calls for attention of additional refractory maintenance in the dry-fed case. One-stage operation yields higher H2, CO and CH4 combined than if a two-stage operation is used, but with a lower syngas heating value. The higher heating value (HHV) of syngas for the one-stage operation is 7.68 MJ/kg, compared with 8.24 MJ/kg for two-stage operation with 75%–25% fuel distribution and 9.03 MJ/kg for two-stage operation with 50%–50% fuel distribution. Carbon conversion efficiency of the air-blown case is 77.3%, which is much lower than that of the oxygen-blown case (99.4%). The syngas heating value for the air-blown case is 4.40 MJ/kg, which is almost half of the heating value of the oxygen-blown case (8.24 MJ/kg).

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Modeling and simulation of a fixed bed gasification process for thermal treatment of municipal solid waste and agricultural residues

Energy Reports ◽

10.1016/j.egyr.2021.07.124 ◽

2021 ◽

Vol 7 ◽

pp. 256-269

Author(s):

Matheus Oliveira ◽

Ana Ramos ◽

Eliseu Monteiro ◽

Abel Rouboa

Keyword(s):

Thermal Treatment ◽

Municipal Solid Waste ◽

Modeling And Simulation ◽

Solid Waste ◽

Fixed Bed ◽

Agricultural Residues ◽

Gasification Process

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CFD researched on rice husk gasification in a pilot fixed bed up-draft system

Science and Technology Development Journal ◽

10.32508/stdj.v19i3.571 ◽

2016 ◽

Vol 19 (3) ◽

pp. 96-109

Author(s):

Phung Thi Kim Le ◽

Viet Tan Tran ◽

Thien Luu Minh Nguyen ◽

Viet Vuong Pham ◽

Truc Thanh Nguyen ◽

...

Keyword(s):

Mathematical Modeling ◽

Rice Husk ◽

Alternative Energy ◽

Fossil Fuels ◽

Fixed Bed ◽

Steam Gasification ◽

Actual Process ◽

Ansys Fluent ◽

Alternative Energy Sources ◽

Gasification Process

Finding alternative energy sources for fossil fuels was a global matter of concern, especially in developing countries. Rice husk, an abundant biomass in Viet Nam, was used to partially replace fossil fuels by gasification process. The study was conducted on the pilot plant fixed bed up-draft gasifier with two kind of gasification agents, pure air and air-steam mixture. Mathematical modeling and computer simulations were also used to describe and optimize the gasification processes. Mathematical modeling was based on Computational Fluid Dynamics method and simulation was carried by using Ansys Fluent software. Changes in outlet composition of syngas components (CO, CO2, CH4, H2O, H2) and temperature of process, in relation with ratio of steam in gasification agents, were presented. Obtained results indicated concentration of CH4, H2 in outlet was increased significantly when using air-steam gasification agents than pure air. The discrepancies among the gasification agents were determined to improve the actual process.

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