Effect of CO2during Coal Pyrolysis and Char Burnout in Oxy-Coal Combustion

2011 ◽  
Vol 25 (6) ◽  
pp. 2452-2459 ◽  
Author(s):  
Prabhat Naredi ◽  
Sarma Pisupati
Keyword(s):  
Coal Combustion ◽  
Coal Pyrolysis ◽  
Char Burnout

scholarly journals Mercury Speciation in Various Coals Based on Sequential Chemical Extraction and Thermal Analysis Methods

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2361
Author(s):  
Yinjiao Su ◽  
Xuan Liu ◽  
Yang Teng ◽  
Kai Zhang
Keyword(s):  
Thermal Stability ◽  
Coal Combustion ◽  
Decomposition Methods ◽  
Chemical Extraction ◽  
Anthropogenic Source ◽  
Coal Rank ◽  
Coal Pyrolysis ◽  
Mercury Emissions ◽  
Sequential Chemical Extraction ◽  
Removal Technology

Coal combustion is an anthropogenic source of mercury (Hg) emissions to the atmosphere. The strong toxicity and bioaccumulation potential have prompted attention to the control of mercury emissions. Pyrolysis has been regarded as an efficient Hg removal technology before coal combustion and other utilization processes. In this work, the Hg speciation in coal and its thermal stability were investigated by combined sequential chemical extraction and temperature programmed decomposition methods; the effect of coal rank on Hg speciation distribution and Hg release characteristics were clarified based on the weight loss of coal; the amount of Hg released; and the emission of sulfur-containing gases during coal pyrolysis. Five species of mercury were determined in this study: exchangeable Hg (F1), carbonate + sulfate + oxide bound Hg (F2), silicate + aluminosilicate bound Hg (F3), sulfide bound Hg (F4), and residual Hg (F5), which are quite distinct in different rank coals. Generally, Hg enriched in carbonates, sulfates, and oxides might migrate to sulfides with the transformation of minerals during the coalification process. The order of thermal stability of different Hg speciation in coal is F1 < F5 < F2 < F4 < F3. Meanwhile, the release of Hg is accompanied with sulfur gases during coal pyrolysis, which is heavily dependent on the coal rank.

Simulation on Coal Devolatilization Combined a Multi-Step Kinetic Model with Chemkin Software

2012 ◽  
Vol 608-609 ◽  
pp. 1375-1382
Author(s):  
Rui Zhang ◽  
Qin Hui Wang ◽  
Zhong Yang Luo ◽  
Meng Xiang Fang
Keyword(s):  
Experimental Data ◽  
Kinetic Model ◽  
Intermediate Product ◽  
Coal Combustion ◽  
Model Complexity ◽  
Coal Pyrolysis ◽  
Simple Application ◽  
Calculation Results ◽  
Simulation Results ◽  
Good Agreement

As the first step in coal combustion and gasification, coal devolatilization has significant effect on reaction process. Previous coal devolatilization models have some disadvantages, such as poor flexibility, model complexity, and requirement of characterization parameters. Recently, Sommariva et al. have proposed a multi-step kinetic model of coal devolatilization. This model avoids the disadvantages mentioned above and can predict elemental composition of tar and char. In this paper, the mechanism of this model has been revised for simple application to Chemkin. Revision method is that some reactions are split into more reactions by using one pseudo-intermediate-product to replace several final products. Simulation results show that calculation results from revised mechanism compare quite well with that from original mechanism and have good agreement with experimental data. The revised mechanism is accurate and can be applied to Chemkin very easily, which gives it wide application to simulation of coal pyrolysis, gasification and combustion.

High-Pressure Coal Combustion: Char Burnout Behavior

2014 ◽  
Vol 2 (3) ◽  
pp. 237-268
Author(s):  
Donald J. Eckstrom ◽  
Albert S. Hirschon ◽  
Ripudaman Malhotra ◽  
Stephen Niksa
Keyword(s):  
High Pressure ◽  
Coal Combustion ◽  
Char Burnout

scholarly journals Specific Features of Solid Fuels Combustion in Oxygen Atmosphere with Recirculation of CO2

2015 ◽  
Vol 17 (3) ◽  
pp. 213
Author(s):  
D.A. Melnikov ◽  
G.A. Ryabov
Keyword(s):  
Coal Combustion ◽  
Carbon Capture ◽  
Circulating Fluidized Bed ◽  
Combustion Process ◽  
Carbon Capture And Storage ◽  
Combustion Model ◽  
Coal Pyrolysis ◽  
Char Particle ◽  
Isothermal Kinetic ◽  
Gasification Reaction

<p>Aspects of coal combustion have been experimentally studied under oxyfuel conditions, one of the promising technologies for carbon capture and storage (CCS). Here, the thermogravimetric analysis (TGA) method was chosen as an experimental technique. Coal pyrolysis tests performed under an O<sub>2</sub>/CO<sub>2</sub> atmosphere were compared with a conventional O<sub>2</sub>/N<sub>2</sub> environment in terms of reaction rate and total volatile yield. Combustion of the resulting chars in the corresponding atmospheres revealed somewhat different combustion rates with a less vigorous reaction in the O<sub>2</sub>/CO<sub>2</sub> medium. The two manipulated factors – namely, the inherently different char reactivities due to the different atmospheres they were obtained in and the different atmospheres of the actual combustion process – were distinguished by performing another series of tests with chars pyrolysed under identical conditions using a standard routine. These chars also showed a weaker reaction in O<sub>2</sub>/CO<sub>2</sub> atmosphere, which was attributed to the lower binary diffusion coefficient of the O<sub>2</sub>/CO<sub>2</sub> pair. The activity of the char – CO<sub>2 </sub>gasification reaction in an O<sub>2</sub>/CO<sub>2</sub> environment was also investigated and revealed some contribution of this reaction to the conversion process. This was particularly noticeable at temperatures above 750 °C and under an internal diffusional controlled regime (zone II), implying displacement of oxygen out of the char particle pore volume, which allowed free reaction of CO<sub>2</sub> on the developed pore surface. Non-isothermal kinetic analysis of the intrinsic kinetics of the oxidation reaction in O<sub>2</sub>/CO<sub>2</sub> revealed no particular difference compared to the O<sub>2</sub>/N<sub>2</sub> medium, at least when the char-CO<sub>2 </sub>reaction was inhibited. The obtained data were used to develop a coal combustion model under O<sub>2</sub>/CO<sub>2</sub> conditions, which was then incorporated as a combustion module into circulating fluidized bed (CFB) computation software.</p>

On Predicting Char Burnout in Pulverized Coal Combustion

2015 ◽  
Vol 229 (5) ◽  
Author(s):  
Roman Weber ◽  
Marco Mancini
Keyword(s):  
Coal Combustion ◽  
Pulverized Coal ◽  
Heterogeneous Reactions ◽  
Basic Knowledge ◽  
Pulverized Coal Combustion ◽  
Oxidation Rates ◽  
Char Burnout ◽  
Char Oxidation ◽  
Kinetics Of

AbstractThe objective of this paper is twofold: to summarise the basic knowledge on kinetics of heterogeneous reactions and to clarify several misconceptions concerning both derivation and usage of expressions for calculating char oxidation rates. This paper is concerned with char reactions only; coal devolatilization is not considered although it may affect char oxidation rates.

Development and Validation of a Coal Combustion Model for Pulverised Coal Combustion

2010 ◽  
Author(s):  
M. J. Chernetsky ◽  
A. A. Dekterev
Keyword(s):  
Coal Combustion ◽  
Pulverized Coal ◽  
Laboratory Scale ◽  
Combustion Model ◽  
Pulverized Coal Combustion ◽  
Nox Formation ◽  
Coal Particles ◽  
Model Predictions ◽  
Char Burnout ◽  
Development And Validation

To fully understand the processes of heat-and-mass transfer on the laboratory-scale and full-scale coal boilers, computer models are needed to develop, which can predict flow fields, heat transfer and the combustion of the coal particles with reasonable accuracy. In the work reported here, a comprehensive model for pulverized coal combustion has been presented. Attention has been given to the char burnout submodel, NOx formation sub-model and accurate calculation of the temperature of the particles. The model predictions have been compared with the experimental measurements of the laboratory-scale pulverized-coal combustion burner.

scholarly journals An evaluation of the efficacy of various coal combustion models for predicting char burnout

Fuel ◽  
2017 ◽  
Vol 201 ◽  
pp. 53-64 ◽  
Author(s):  
Josh McConnell ◽  
Babak Goshayeshi ◽  
James C. Sutherland
Keyword(s):  
Coal Combustion ◽  
Combustion Models ◽  
Char Burnout
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