PERFORMANCE OF A PRESSURIZED TWO-STAGE FLUIDIZED GASIFICATION PROCESS FOR PRODUCTION OF LOW-BTU GAS FROM COAL CHAR

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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Two-stage coal gasification process

Heat Recovery Systems and CHP ◽

10.1016/0890-4332(90)90104-r ◽

1990 ◽

Vol 10 (4) ◽

pp. iii-iv

Keyword(s):

Coal Gasification ◽

Two Stage ◽

Gasification Process

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Gasification Kinetics of Bituminous Coal Char in the Mixture of CO2, H2O, CO, and H2

Energies ◽

10.3390/en12030496 ◽

2019 ◽

Vol 12 (3) ◽

pp. 496 ◽

Cited By ~ 2

Author(s):

Junwei Chen ◽

Weibin Chen ◽

Yang Jiao ◽

Xidong Wang

Keyword(s):

Bituminous Coal ◽

Gas Diffusion ◽

Coal Char ◽

Conversion Degree ◽

Diffusion Control ◽

Diffusion Resistance ◽

Gasification Process ◽

Control Step ◽

Kinetics Of ◽

Gasification Temperature

The gasification kinetics of bituminous coal char was investigated in a mixture of CO2, H2O, CO, H2, and N2 under isothermal conditions. In addition, the impacts of gasification temperature, gasification time, and gas composition on the gasification process were analyzed. As the experimental results suggest, there is a significant increase of the carbon conversion degree of bituminous coal char not just when gasification temperature and time increase, but also when H2 and CO concentration decreases. The kinetics of bituminous coal char in the gasification process was successfully modeled as a shrinking unreacted core. It is concluded that the gasification of bituminous coal char is controlled by an internal chemical reaction in the early stage and diffusion in the later stage. The activation energies of bituminous coal char gasification for different stages were studied. Moreover, it is proposed for the first time, to our knowledge, that the diffusion-control step is significantly shortened with the decrease of the CO2/H2O ratio. As scanning-electron-microscopy results suggest, bituminous coal char gasified in CO2/H2O = 1/3 atmosphere has numerous inner pores (0–5 m). Therefore, in the process of gasification, the inner pores provide a gas channel that reduces the gas diffusion resistance and thus shortens the diffusion-control step. These results can serve as a reference for industrialized application of the technology of coal gasification direct reduced iron.

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Gasification process of Cuban bagasse in a two-stage reactor

Biomass and Bioenergy ◽

10.1016/j.biombioe.2003.11.009 ◽

2004 ◽

Vol 27 (3) ◽

pp. 247-252 ◽

Cited By ~ 39

Author(s):

Paolo De Filippis ◽

Carlo Borgianni ◽

Martino Paolucci ◽

Fausto Pochetti

Keyword(s):

Two Stage ◽

Gasification Process

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Pore Structure of Coal-Chars Derived From Atmospheric and Pressurized Spouted Fluidized Bed Gasifiers

18th International Conference on Fluidized Bed Combustion ◽

10.1115/fbc2005-78036 ◽

2005 ◽

Cited By ~ 1

Author(s):

Yufeng Duan ◽

Yi Zhou ◽

Xiaoping Chen ◽

Changsui Zhao ◽

Xin Wu

Keyword(s):

Pore Structure ◽

Fluidized Bed ◽

Positive Impact ◽

Elevated Pressure ◽

Influential Factors ◽

Coal Char ◽

Operational Conditions ◽

Gasification Process ◽

Leading Role ◽

Partial Gasification

Pore structure is one of the most important factors that dominate the reactivity of post-combustion of coal-chars derived from partial gasification process of atmospheric and pressurized spouted fluidized bed gasifiers. The influential factors on pore structure of coal-chars were analyzed in terms of the coal size feed, operational conditions, coal-char size and its components. It concluded that pyrolysis and devolatilization play a leading role in forming the pore structure of coal-chars in the partial gasification process. It is the reaction of coal-char with CO2 and H2O (steam) that plays a dominant positive impact on promoting enlargement and development of the coal-char pores at the elevated pressure gasification. There may exist an optimal coal-char size range that possesses abundant porosity and bigger pore specific surface area, which contributes to enhancing the gasification reactions in the atmospheric gasifier.

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Simulation of two-stage automotive shredder residue pyrolysis and gasification process using the Aspen Plus model

BioResources ◽

10.15376/biores.16.3.5964-5984 ◽

2021 ◽

Vol 16 (3) ◽

pp. 5964-5984

Author(s):

Bin Yang ◽

Ming Chen

Keyword(s):

Process Parameters ◽

Aspen Plus ◽

Product Distribution ◽

Recycling Rate ◽

Main Process ◽

Optimal Process ◽

Two Stage ◽

Shredder Residue ◽

Gasification Process ◽

Automotive Shredder Residue

The disposal of automotive shredder residue (ASR) directly affects China’s goal of achieving a 95% recycling rate for end-of-life vehicles. Pyrolysis and gasification have gradually become the most commonly used thermochemical technologies for ASR recycling. To obtain more hydrogen-rich syngas, it is necessary to determine the optimal process parameters of the ASR pyrolysis and gasification process. The main process parameters of the two-stage ASR pyrolysis and gasification process were studied using the established Aspen Plus model. Through analyzing the effects of process parameters, such as the temperature, equivalence ratio, and mass ratio of steam to ASR feedstock, on the product distribution and product characteristics of ASR pyrolysis and gasification, the optimal process parameters were determined. A series of comparative experiments under different conditions were conducted. The experimental results verified the accuracy and reliability of the Aspen Plus simulation model for the ASR pyrolysis and gasification processes and verified the practical feasibility of the process parameters obtained from the simulation analysis.

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