Gasification Kinetics of Victorian Brown Coal-Derived Char in Fluidised Bed Reactor

2021 ◽  
pp. 1-24
Author(s):  
Imtenan Sayeed ◽  
Mahmud Arman Kibria ◽  
Sankar Bhattacharya
Keyword(s):  
Activation Energy ◽  
Brown Coal ◽  
Gas Flow ◽  
Oxygen Carrier ◽  
Fluidised Bed ◽  
Co2 Partial Pressure ◽  
Fuel Reactor ◽  
Char Particle ◽  
Fluidised Bed Reactor ◽  
Kinetics Of

Abstract In a chemical looping combustion (CLC) system, gasification kinetics of char holds immense importance being the rate-limiting reaction in the fuel reactor. This paper studied the gasification kinetics of char derived from Victorian Brown Coal (VBC) in a fluidised bed reactor which mimics the fuel reactor conditions of a CLC process. Mass of char, char particle size and gas flow conditions were optimised to ensure the gasification reaction free from mass transfer limitations. Effect of oxygen carrier, hematite, being the bed material was also studied. The experiments were conducted in the temperature range of 800C-950C, which is a typical range for fuel reactor. The experimental results were modelled with the help of grain model (GM) and random pore model (RPM) to analyse the kinetic parameters. Activation energy was found to be around 177 kJ/mol in sand bed and 175.5 kJ/mol in the hematite bed. Reaction in hematite bed was found to be 42% faster on average compared to the reaction in a sand bed. Fastest total conversion of char took as low as 4.1 minutes in hematite bed at 950C. While catalytic effect of hematite was ruled out due to insignificant change in activation energy, it was concluded that increase in CO2 partial pressure at the vicinity of char particle enhanced the reaction rate in the case of hematite bed. This study has generated relevant information for the CLC of Victorian Brown Coal with hematite as the oxygen carrier.

The kinetics of typical medical waste pyrolysis based on gaseous evolution behaviour in a micro-fluidised bed reactor

2018 ◽  
Vol 36 (11) ◽  
pp. 1073-1082 ◽  
Author(s):  
Linbo Qin ◽  
Jun Han ◽  
Bo Zhao ◽  
Wangsheng Chen ◽  
Futang Xing
Keyword(s):  
Activation Energy ◽  
Model Fitting ◽  
Activation Energies ◽  
Gaseous Product ◽  
Medical Waste ◽  
Fluidised Bed ◽  
Mechanism Model ◽  
Fitting Method ◽  
Fluidised Bed Reactor ◽  
Kinetics Of

In order to obtain the kinetic parameters during typical medical waste pyrolysis, the typical medical waste is pyrolysed in a micro-fluidised bed reactor. The gases evolved from the typical medical waste pyrolysis are analysed by a mass spectrometer, and only H2, CH4, C2H2, C2H4, C2H6, C3H6, C3H8 and C4H4 are observed. According to the gaseous product concentration profiles, the activation energies of gaseous formation are calculated based on the Friedman approach, and the average activation energies of H2, CH4, C2H2, C2H4, C2H6, C3H6, C3H8 and C4H4 formation during typical medical waste pyrolysis are in sequence as 65.10, 39.98, 35.17, 38.71, 40.75, 41.79, 58.57 and 63.95 kJ mol−1. Moreover, the activation energy with respect to the gases mixture formation is 52.70 kJ mol−1. Hence, it is concluded that the activation energy of typical medical waste pyrolysis is 52.70 kJ mol−1. The model-fitting method is used to determine the mechanism model of medical waste pyrolysis. The results indicate that the chemical reaction ( n = 1) model (G(x) = –ln(1–x)) is the optimum.

scholarly journals A Simple Theoretical Analysis of the Burn-out Times of an Isothermal Particle of Coal Char Under Air-Firing, Gasification and Oxyfuel Combustion in Fluidised Beds

2021 ◽  
Author(s):  
Toyin Omojola
Keyword(s):  
Carbon Dioxide ◽  
Theoretical Analysis ◽  
Coal Combustion ◽  
Coal Char ◽  
Fluidised Bed ◽  
Oxyfuel Combustion ◽  
Burn Out ◽  
Char Particle ◽  
Fluidised Beds ◽  
Fluidised Bed Reactor

<p>Coal combustion in air, gasification with carbon dioxide and oxyfuel combustion in oxygen/carbon dioxide mixtures was studied at high process temperatures in a bubbling fluidised bed reactor where burning is controlled by external mass transfer conditions is considered. Theoretical analysis of the burn-out times of an isothermal particle of coal char in air is provided for the case where a fraction of carbon monoxide is oxidized close to the char particle. Burn-out time equations are provided for the gasification of char in carbon dioxide. Both burn-out time equations are compared to analytical equations derived for the oxy-fuel combustion of char particles in oxygen/carbon dioxide mixtures. </p>

scholarly journals A theoretical analysis of the burn-out times of an isothermal particle of coal char under air-firing, gasification and oxyfuel combustion in fluidised beds

2021 ◽  
Author(s):  
Toyin Omojola
Keyword(s):  
Carbon Dioxide ◽  
Theoretical Analysis ◽  
Coal Char ◽  
Fluidised Bed ◽  
Oxyfuel Combustion ◽  
Burn Out ◽  
Char Particle ◽  
Global Warming Targets ◽  
Fluidised Beds ◽  
Fluidised Bed Reactor

<p></p><p>The combustion of coal in air, its gasification with carbon dioxide, and oxyfuel combustion in oxygen/carbon dioxide mixtures was studied at high process temperatures in a bubbling fluidised bed reactor where burning is controlled by external mass transfer conditions. Theoretical analysis of the burn-out times of an isothermal particle of coal char in air is provided for the case where a fraction of carbon monoxide is oxidized close to the char particle. Burn-out time equations are provided for the gasification of char in carbon dioxide. Both burn-out time equations are compared to analytical equations derived for the oxy-fuel combustion of char particles in oxygen/carbon dioxide mixtures. The results are particularly relevant for retrofitting existing bubbling fluidised bed reactors for sustainable energy generation to meet global warming targets. </p><p></p>

Low Temperature Pyrolysis of an Australian Brown Coal in a Fluidised Bed Reactor

2008 ◽  
Vol 8 (3-4) ◽  
pp. 293-309 ◽  
Author(s):  
L. Shen ◽  
D. K. Zhang ◽  
H. M. Yan ◽  
J. R. Roach ◽  
Q. D. Nguyen
Keyword(s):  
Low Temperature ◽  
Brown Coal ◽  
Fluidised Bed ◽  
Low Temperature Pyrolysis ◽  
Fluidised Bed Reactor

Effect of Fuel and Oxygen Carriers on the Hydrodynamics of Fuel Reactor in a Chemical Looping Combustion System

2013 ◽  
Author(s):  
Atal B. Harichandan ◽  
Tariq Shamim
Keyword(s):  
Oxygen Carrier ◽  
Bubble Formation ◽  
Chemical Looping Combustion ◽  
Chemical Looping ◽  
Calcium Sulfide ◽  
Oxygen Carriers ◽  
Fuel Reactor ◽  
Gas Interactions ◽  
Kinetics Of ◽  
Good Agreement

The hydrodynamics of fuel reactor in a chemical looping combustion (CLC) system has been analyzed by using a multiphase CFD-based model with solid-gas interactions and chemical reactions. In this paper, the fuel reactors of two CLC systems are numerically simulated independently by using hydrogen with calcium sulfide as oxygen carrier, and methane with nickel as oxygen carrier in similar conditions. Kinetic theory of granular flow has been adopted. Conservation of mass, momentum and species equations, and reaction kinetics of oxygen carriers are used for the numerical calculation. The present results obtained are in good agreement with the experimental and numerical results available in open literature. The bubble hydrodynamics in both the fuel reactors are analyzed. The salient features of bubble formation, rise and burst are prominent in hydrogen-fueled reactor as compared to methane-fueled reactor. The fuel conversion rate is found to be larger in the case of hydrogen-fueled reactor.

Effect of Fuel and Oxygen Carriers on the Hydrodynamics of Fuel Reactor in a Chemical Looping Combustion System

2014 ◽  
Vol 6 (4) ◽  
Author(s):  
Atal Bihari Harichandan ◽  
Tariq Shamim
Keyword(s):  
Oxygen Carrier ◽  
Bubble Formation ◽  
Chemical Looping Combustion ◽  
Chemical Looping ◽  
Oxygen Carriers ◽  
Fuel Reactor ◽  
Computational Fluid Dynamics Cfd ◽  
Gas Interactions ◽  
Kinetics Of ◽  
Good Agreement

The hydrodynamics of a fuel reactor in a chemical looping combustion (CLC) system is analyzed by using a multiphase two-dimensional computational fluid dynamics (CFD) model that involves solid–gas interactions and chemical reactions. The study compares the fuel reactors of two CLC systems numerically by using hydrogen with calcium sulfide as an oxygen carrier, and methane with nickel as an oxygen carrier in similar conditions. Kinetic theory of granular flow has been adopted. The model considers the conservation equations of mass, momentum and species, and reaction kinetics of oxygen carriers. The results obtained are in good agreement with the experimental and numerical results available in open literature. The bubble hydrodynamics in both the fuel reactors are analyzed. The salient features of the bubble formation, rise, and burst are more prominent in the hydrogen-fueled reactor as compared to the methane-fueled reactor. The fuel conversion rate is found to be larger for the hydrogen-fueled reactor.

scholarly journals Synthesis of Carbon Nanotubes from Benzene in a Fluidised Bed Reactor

2020 ◽  
Vol 22 (3) ◽  
pp. 235
Author(s):  
G.T. Smagulova ◽  
B.B. Kaidar ◽  
N. Yesbolov ◽  
N.G. Prikhodko ◽  
N.R. Maxumzhanova
Keyword(s):  
Carbon Nanotubes ◽  
Gas Flow ◽  
Nickel Nanoparticles ◽  
Fluidised Bed ◽  
Optimum Temperature ◽  
Solution Combustion ◽  
Flow Rates ◽  
Method Of Solution ◽  
Fluidised Bed Reactor ◽  
Synthesis Of Carbon Nanotubes

The paper presents the results of carbon nanotubes synthesis from benzene in fluidised bed reactor. Al2O3 spheres with iron and nickel nanoparticles coating were used as a catalyst for the synthesis of carbon nanotubes. To deposit nickel nanoparticles on the surface of Al2O3 spheres, the method of solution combustion was used. Optimum temperature conditions and gas flow rates were worked out for each of the catalysts. It was found that the best efficiency in the synthesis of carbon nanotubes from benzene is shown by catalysts based on aluminium oxide coated with iron. The obtained carbon nanotubes were studied by scanning electron microscopy and Raman spectroscopy. It was found that at temperatures above 850 °C from benzene on Al2O3 spheres with Ni/NiO, carbon frame structures are formed.

scholarly journals A Simple Theoretical Analysis of the Burn-out Times of an Isothermal Particle of Coal Char Under Air-Firing, Gasification and Oxyfuel Combustion in Fluidised Beds

2021 ◽  
Author(s):  
Toyin Omojola
Keyword(s):  
Carbon Dioxide ◽  
Theoretical Analysis ◽  
Coal Combustion ◽  
Coal Char ◽  
Fluidised Bed ◽  
Oxyfuel Combustion ◽  
Burn Out ◽  
Char Particle ◽  
Fluidised Beds ◽  
Fluidised Bed Reactor

<p>Coal combustion in air, gasification with carbon dioxide and oxyfuel combustion in oxygen/carbon dioxide mixtures was studied at high process temperatures in a bubbling fluidised bed reactor where burning is controlled by external mass transfer conditions. Theoretical analysis of the burn-out times of an isothermal particle of coal char in air is provided for the case where a fraction of carbon monoxide is oxidized close to the char particle. Burn-out time equations are provided for the gasification of char in carbon dioxide. Both burn-out time equations are compared to analytical equations derived for the oxy-fuel combustion of char particles in oxygen/carbon dioxide mixtures. </p>

Effect of ionizing radiation on the kinetics of hydrogenation on the Ni-MgO mixed catalyst

1982 ◽  
Vol 47 (7) ◽  
pp. 1780-1786 ◽  
Author(s):  
Rostislav Kudláček ◽  
Jan Lokoč
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Liquid Phase ◽  
Ionizing Radiation ◽  
Oxide Catalyst ◽  
Absorbed Dose ◽  
Hydrogenation Rate ◽  
Solution Composition ◽  
Mixed Catalyst ◽  
Kinetics Of

The effect of gamma pre-irradiation of the mixed nickel-magnesium oxide catalyst on the kinetics of hydrogenation of maleic acid in the liquid phase has been studied. The changes of the hydrogenation rate are compared with the changes of the adsorbed amount of the acid and with the changes of the solution composition, activation energy, and absorbed dose of the ionizing radiation. From this comparison and from the interpretation of the experimental data it can be deduced that two types of centers can be distinguished on the surface of the catalyst under study, namely the sorption centres for the acid and hydrogen and the reaction centres.

Sign in / Sign up

Export Citation Format

Share Document