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Special Issue "Recent Advances in Coal Combustion and Gasification"

A special issue of Energies (ISSN 1996-1073).

Deadline for manuscript submissions: closed (1 August 2015)

Special Issue Editor

Guest Editor
Prof. Dr. Mehrdad Massoudi

Department of Biomedical Engineering and Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213-3890, USA
Website | E-Mail
Interests: multi-component flows; non-Newtonian fluids; granular materials; heat transfer; mathematical modelling

Special Issue Information

Dear Colleagues,

Developing advanced coal-based fuel production with low pollutants is an important element for a cleaner environment and a more sustainable future. Clean coal technologies are needed to provide better environmental performance at low cost, enabling power plants to continue using coal for electricity generation. As fossil fuel use increases, the amount of waste materials and the environmental issues dealing with their disposal also increase. Atmospheric particulate pollution problems arise from the emissions from a variety of different sources.  Emissions from power plants, motor vehicles, and other sources such as, forest fire, biomass burning, volcanoes, etc., are transported, dispersed, and mixed in the atmosphere.  One of the promising approaches is the development of coal/waste co-firing technology with fuels such as biomass. To improve efficiency and reduce the cost of electricity, it is important to understand factors such as the operating conditions and the impact of fuel properties and additives on carbon conversion, ash, slag, fouling, etc. To develop accurate heat mass transfer models in any type of coal combustion or gasification process, the heat and mass transfer and the rheological properties of materials such as coal-slurries, ash, biomass, and slag, especially in high-temperature environments, needs to be understood and properly modeled.

Dr. Mehrdad Massoudi
Guest Editor

Manuscript Submission Information

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Keywords

  • gasifiers
  • combustion
  • fluidized beds
  • biomass cofiring
  • cfd analysis
  • mathematical and computational modelling
  • slag
  • coal-slurries
  • ash and waste management
  • ash characterization and utilization
  • atmospheric pollution

Published Papers (15 papers)

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Research

Jump to: Review

Open AccessArticle Effect of Heterogeneity in Coal Ash Chemical Composition on the Onset of Conditions Favorable for Agglomeration in Fluid Beds
Energies 2015, 8(11), 12530-12545; https://doi.org/10.3390/en81112329
Received: 10 September 2015 / Revised: 25 October 2015 / Accepted: 29 October 2015 / Published: 4 November 2015
Cited by 3 | PDF Full-text (3017 KB) | HTML Full-text | XML Full-text
Abstract
Ash agglomeration issues that arise due to the sticking of slag-wetted, colliding particles have been creating operational difficulties and monetary losses for the fluidized bed combustion (FBC) industry. Difficulties have been experienced in the detection of slag-liquid at the low operating temperatures in
[...] Read more.
Ash agglomeration issues that arise due to the sticking of slag-wetted, colliding particles have been creating operational difficulties and monetary losses for the fluidized bed combustion (FBC) industry. Difficulties have been experienced in the detection of slag-liquid at the low operating temperatures in fluidized bed combustors (FBCs) and predicting the agglomeration behavior of fuel. This study aims to study the effect of heterogeneity in ash composition on the detection of slag-liquid in FBCs. It quantifies the slag-liquid amounts at the particle-level, under oxidizing environments, by dividing the bulk fuel into density classes. FactSage thermodynamic simulations of each of the particle classes, along with experimental validation of the trends with thermo-mechanical analysis (TMA) and high temperature X-ray diffraction (HT-XRD) were performed. The results obtained can be used to estimate the stickiness of particles in the development of ash agglomeration models based on particle collisions. The study of these particle classes shows that particle classes with specific minerals can form low temperature eutectics and lead to onset of slag-liquid formation at temperatures below those predicted by bulk analysis alone. Comparison of the differences in slag-liquid formation tendencies under reducing and oxidizing environments is also presented. Full article
(This article belongs to the Special Issue Recent Advances in Coal Combustion and Gasification)
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Open AccessArticle Effects of Shear Dependent Viscosity and Variable Thermal Conductivity on the Flow and Heat Transfer in a Slurry
Energies 2015, 8(10), 11546-11574; https://doi.org/10.3390/en81011546
Received: 5 August 2015 / Revised: 2 September 2015 / Accepted: 30 September 2015 / Published: 15 October 2015
Cited by 2 | PDF Full-text (1947 KB) | HTML Full-text | XML Full-text
Abstract
In this paper we study the effects of variable viscosity and thermal conductivity on the heat transfer in the pressure-driven fully developed flow of a slurry (suspension) between two horizontal flat plates. The fluid is assumed to be described by a constitutive relation
[...] Read more.
In this paper we study the effects of variable viscosity and thermal conductivity on the heat transfer in the pressure-driven fully developed flow of a slurry (suspension) between two horizontal flat plates. The fluid is assumed to be described by a constitutive relation for a generalized second grade fluid where the shear viscosity is a function of the shear rate, temperature and concentration. The heat flux vector for the slurry is assumed to follow a generalized form of the Fourier’s equation where the thermal conductivity k depends on the temperature as well as the shear rate. We numerically solve the governing equations of motion in the non-dimensional form and perform a parametric study to see the effects of various dimensionless numbers on the velocity, volume fraction and temperature profiles. The different cases of shear thinning and thickening, and the effect of the exponent in the Reynolds viscosity model, for the temperature variation in viscosity, are also considered. The results indicate that the variable thermal conductivity can play an important role in controlling the temperature variation in the flow. Full article
(This article belongs to the Special Issue Recent Advances in Coal Combustion and Gasification)
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Open AccessArticle Fluidized-Bed Gasification of Plastic Waste, Wood, and Their Blends with Coal
Energies 2015, 8(8), 8052-8068; https://doi.org/10.3390/en8088052
Received: 26 May 2015 / Revised: 23 July 2015 / Accepted: 27 July 2015 / Published: 3 August 2015
Cited by 8 | PDF Full-text (1120 KB) | HTML Full-text | XML Full-text
Abstract
The effect of fuel composition on gasification process performance was investigated by performing mass and energy balances on a pre-pilot scale bubbling fluidized bed reactor fed with mixtures of plastic waste, wood, and coal. The fuels containing plastic waste produced less H2
[...] Read more.
The effect of fuel composition on gasification process performance was investigated by performing mass and energy balances on a pre-pilot scale bubbling fluidized bed reactor fed with mixtures of plastic waste, wood, and coal. The fuels containing plastic waste produced less H2, CO, and CO2 and more light hydrocarbons than the fuels including biomass. The lower heating value (LHV) progressively increased from 5.1 to 7.9 MJ/Nm3 when the plastic waste fraction was moved from 0% to 100%. Higher carbonaceous fines production was associated with the fuel containing a large fraction of coal (60%), producing 87.5 g/kgFuel compared to only 1.0 g/kgFuel obtained during the gasification test with just plastic waste. Conversely, plastic waste gasification produced the highest tar yield, 161.9 g/kgFuel, while woody biomass generated only 13.4 g/kgFuel. Wood gasification showed a carbon conversion efficiency (CCE) of 0.93, while the tests with two fuels containing coal showed lowest CCE values (0.78 and 0.70, respectively). Plastic waste and wood gasification presented similar cold gas efficiency (CGE) values (0.75 and 0.76, respectively), while that obtained during the co-gasification tests varied from 0.53 to 0.73. Full article
(This article belongs to the Special Issue Recent Advances in Coal Combustion and Gasification)
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Open AccessArticle Facile and Economical Preparation of SiAlON-Based Composites Using Coal Gangue: From Fundamental to Industrial Application
Energies 2015, 8(7), 7428-7440; https://doi.org/10.3390/en8077428
Received: 21 May 2015 / Revised: 11 July 2015 / Accepted: 13 July 2015 / Published: 22 July 2015
Cited by 2 | PDF Full-text (2790 KB) | HTML Full-text | XML Full-text
Abstract
The present study aims to synthesize SiAlON-based composites utilizing coal gangue. Different types of SiAlON-based composites were synthesized using coal gangue by carbothermal reduction nitridation method through control of different reaction atmospheres. The experimental results indicate that the oxygen partial pressure was an
[...] Read more.
The present study aims to synthesize SiAlON-based composites utilizing coal gangue. Different types of SiAlON-based composites were synthesized using coal gangue by carbothermal reduction nitridation method through control of different reaction atmospheres. The experimental results indicate that the oxygen partial pressure was an essential factor in the manufacture of SiAlON-based composites and under proper control of the atmospheres, SiAlON-based composites with different crystal structures could be synthesized. The optimum conditions of synthesis of different SiAlON-based composites were respectively determined. Based on the laboratory results, a prototype plant was proposed and constructed, and β-SiAlON composite was successfully produced using coal gangue. The synthesized β-SiAlON composite was applied in preparation of iron ladle brick instead of SiC, which showed that the compression strength, refractoriness under load and high temperature bending strength were increased from 44.5 ± 6.7 MPa, 1618 ± 21 °C and 5.4 ± 1.2 MPa to 64.1 ± 2.5 MPa, 1700 ± 28 °C and 7.1 ± 1.6 MPa, respectively. Compared with the traditional synthesis method, the present technique is expected to save energy both in raw materials and technical process. Full article
(This article belongs to the Special Issue Recent Advances in Coal Combustion and Gasification)
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Open AccessArticle Modeling on the Effect of Coal Loads on Kinetic Energy of Balls for Ball Mills
Energies 2015, 8(7), 6859-6880; https://doi.org/10.3390/en8076859
Received: 15 May 2015 / Revised: 1 July 2015 / Accepted: 2 July 2015 / Published: 9 July 2015
Cited by 1 | PDF Full-text (2280 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a solution for the detection and control of coal loads that is more accurate and convenient than those currently used. To date, no research has addressed the use of a grinding medium as the controlled parameter. To improve the accuracy
[...] Read more.
This paper presents a solution for the detection and control of coal loads that is more accurate and convenient than those currently used. To date, no research has addressed the use of a grinding medium as the controlled parameter. To improve the accuracy of the coal load detection based on the kinetic energy of balls in a tubular ball mill, a Discrete Element Method (DEM) model for ball kinematics based on coal loads is proposed. The operating process for a ball mill and the ball motion, as influenced by the coal quality and the coal load, was analyzed carefully. The relationship between the operating efficiency of a coal pulverizing system, coal loads, and the balls’ kinetic energy was obtained. Origin and Matlab were utilized to draw the variation of parameters with increasing coal loads in the projectile and cascading motion states. The parameters include the balls’ real-time kinetic energy, the friction energy consumption, and the mill’s total work. Meanwhile, a method of balanced adjacent degree and a physical experiment were proposed to verify the considerable effect of the balls’ kinetic energy on coal loads. The model and experiment results indicate that a coal load control method based on the balls’ kinetic energy is therefore feasible for the optimized operation of a coal pulverizing system. Full article
(This article belongs to the Special Issue Recent Advances in Coal Combustion and Gasification)
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Open AccessArticle Effect of Recycle Solvent Hydrotreatment on Oil Yield of Direct Coal Liquefaction
Energies 2015, 8(7), 6795-6805; https://doi.org/10.3390/en8076795
Received: 14 May 2015 / Revised: 19 June 2015 / Accepted: 23 June 2015 / Published: 1 July 2015
Cited by 5 | PDF Full-text (547 KB) | HTML Full-text | XML Full-text
Abstract
Effects of the recycle solvent hydrotreatment on oil yield of direct coal liquefaction were carried out in the 0.18 t/day direct coal liquefaction bench support unit of National Engineering Laboratory for Direct Coal Liquefaction (China). Results showed that the hydrogen-donating ability of the
[...] Read more.
Effects of the recycle solvent hydrotreatment on oil yield of direct coal liquefaction were carried out in the 0.18 t/day direct coal liquefaction bench support unit of National Engineering Laboratory for Direct Coal Liquefaction (China). Results showed that the hydrogen-donating ability of the hydrogenated recycle solvent improved and the hydrogen consumption of solvent hydrotreatment was increased by decreasing liquid hourly space velocity (LHSV) from 1.5 to 1.0 h−1 and increasing reaction pressure from 13.7 to 19.0 MPa. The hydrogen-donating ability of the hydrogenated recycle solvent was enhanced, thus promoting the oil yield and coal conversion of the liquefaction reaction. The coal conversion and distillates yield of coal liquefaction were increased from 88.74% to 88.82% and from 47.41% to 49.10%, respectively, with the increase in the solvent hydrotreatment pressure from 13.7 to 19.0 MPa. The coal conversion and distillates of coal liquefaction were increased from 88.82% to 89.27% and from 49.10% to 54.49%, respectively, when the LHSV decreased from 1.5 to 1.0 h−1 under the solvent hydrotreatment pressure of 19.0 MPa. Full article
(This article belongs to the Special Issue Recent Advances in Coal Combustion and Gasification)
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Open AccessArticle Simulation of Syngas Production from Lignin Using Guaiacol as a Model Compound
Energies 2015, 8(7), 6705-6714; https://doi.org/10.3390/en8076705
Received: 13 May 2015 / Revised: 7 June 2015 / Accepted: 17 June 2015 / Published: 30 June 2015
Cited by 5 | PDF Full-text (1758 KB) | HTML Full-text | XML Full-text
Abstract
Lignin is an abundant component in biomass that can be used a feedstock for producing several value-added products, including biofuels. However, lignin is a complex molecule (involving in its structure three types of phenylpropane units: coumaryl, coniferyl and sinapyl), which is difficult to
[...] Read more.
Lignin is an abundant component in biomass that can be used a feedstock for producing several value-added products, including biofuels. However, lignin is a complex molecule (involving in its structure three types of phenylpropane units: coumaryl, coniferyl and sinapyl), which is difficult to implement in any process simulation task. The lignin from softwood is formed mainly by coniferyl units; therefore, in this work the use of the guaiacol molecule to model softwood lignin in the simulation of the syngas process (H2 + CO) is proposed. A Gibbs reactor in ASPEN PLUS® was feed with ratios of water and guaiacol from 0.5 to 20. The pressure was varied from 0.05 to 1.01 MPa and the temperature in the range of 200–3200 °C. H2, CO, CO2, CH4, O2 and C as graphite were considered in the output stream. The pressure, temperature and ratio water/guaiacol conditions for syngas production for different H2/CO ratio are discussed. The obtained results allow to determine the operating conditions to improve the syngas production and show that C as graphite and water decomposition can be avoided. Full article
(This article belongs to the Special Issue Recent Advances in Coal Combustion and Gasification)
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Open AccessArticle Thermo-Mechanical Simulations of Rock Behavior in Underground Coal Gasification Show Negligible Impact of Temperature-Dependent Parameters on Permeability Changes
Energies 2015, 8(6), 5800-5827; https://doi.org/10.3390/en8065800
Received: 27 April 2015 / Accepted: 9 June 2015 / Published: 16 June 2015
Cited by 20 | PDF Full-text (6861 KB) | HTML Full-text | XML Full-text
Abstract
A coupled thermo-mechanical model has been developed to assess permeability changes in the vicinity of an underground coal gasification (UCG) reactor resulting from excavation and thermo-mechanical effects. Thereto, we consider a stepwise UCG reactor excavation based on a pre-defined coal consumption rate and
[...] Read more.
A coupled thermo-mechanical model has been developed to assess permeability changes in the vicinity of an underground coal gasification (UCG) reactor resulting from excavation and thermo-mechanical effects. Thereto, we consider a stepwise UCG reactor excavation based on a pre-defined coal consumption rate and dynamic thermal boundary conditions. Simulation results demonstrate that thermo-mechanical rock behavior is mainly driven by the thermal expansion coefficient, thermal conductivity, tensile strength and elastic modulus of the surrounding rock. A comparison between temperature-dependent and temperature-independent parameters applied in the simulations indicates notable variations in the distribution of total displacements in the UCG reactor vicinity related to thermal stress, but only negligible differences in permeability changes. Hence, temperature-dependent thermo-mechanical parameters have to be considered in the assessment of near-field UCG impacts only, while far-field models can achieve a higher computational efficiency by using temperature-independent thermo-mechanical parameters. Considering the findings of the present study in the large-scale assessment of potential environmental impacts of underground coal gasification, representative coupled simulations based on complex 3D large-scale models become computationally feasible. Full article
(This article belongs to the Special Issue Recent Advances in Coal Combustion and Gasification)
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Open AccessArticle Influence of Coal Blending on Ash Fusibility in Reducing Atmosphere
Energies 2015, 8(6), 4735-4754; https://doi.org/10.3390/en8064735
Received: 16 April 2015 / Revised: 11 May 2015 / Accepted: 14 May 2015 / Published: 26 May 2015
Cited by 7 | PDF Full-text (2801 KB) | HTML Full-text | XML Full-text
Abstract
Coal blending is an effective way to organize and control coal ash fusibility to meet different requirements of Coal-fired power plants. This study investigates three different eutectic processes and explains the mechanism of how coal blending affects ash fusibility. The blended ashes were
[...] Read more.
Coal blending is an effective way to organize and control coal ash fusibility to meet different requirements of Coal-fired power plants. This study investigates three different eutectic processes and explains the mechanism of how coal blending affects ash fusibility. The blended ashes were prepared by hand-mixing two raw coal ashes at five blending ratios, G:D = 10:90 (G10D90), G:D= 20:80 (G20D80), G:D = 30:70 (G30D70), G:D = 40:60 (G40D60), and G:D = 50:50 (G50D50). The samples were heated at 900 °C, 1000 °C, 1100 °C, 1200 °C, and 1300 °C in reducing atmosphere. XRD and SEM/EDX were used to identify mineral transformations and eutectic processes. The eutectic processes were finally simulated with FactSage. Results show that the fusion temperatures of the blended ashes initially decrease and then increase with the blending ratio, a trend that is typical of eutectic melting. Eutectic phenomena are observed in D100, G10D90, and G30D70 in different degrees, which do not appear in G100 and G50D50 for the lack of eutectic reactants. The main eutectic reactants are gehlenite, magnetite, merwinite, and diopside. The FactSage simulation results show that the content discrepancy of merwinite and diopside in the ashes causes the inconsistent eutectic temperatures and eutectic degrees, in turn decrease the fusion temperature of the blended ash and then increase them with the blending ratio. Full article
(This article belongs to the Special Issue Recent Advances in Coal Combustion and Gasification)
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Open AccessArticle Effects of Design/Operating Parameters and Physical Properties on Slag Thickness and Heat Transfer during Coal Gasification
Energies 2015, 8(5), 3370-3385; https://doi.org/10.3390/en8053370
Received: 12 March 2015 / Revised: 19 April 2015 / Accepted: 21 April 2015 / Published: 24 April 2015
Cited by 7 | PDF Full-text (377 KB) | HTML Full-text | XML Full-text
Abstract
The behaviors of the slag layers formed by the deposition of molten ash onto the wall are important for the operation of entrained coal gasifiers. In this study, the effects of design/operation parameters and slag properties on the slag behaviors were assessed in
[...] Read more.
The behaviors of the slag layers formed by the deposition of molten ash onto the wall are important for the operation of entrained coal gasifiers. In this study, the effects of design/operation parameters and slag properties on the slag behaviors were assessed in a commercial coal gasifier using numerical modeling. The parameters influenced the slag behaviors through mechanisms interrelated to the heat transfer, temperature, velocity, and viscosity of the slag layers. The velocity profile of the liquid slag was less sensitive to the variations in the parameters. Therefore, the change in the liquid slag thickness was typically smaller than that of the solid slag. The gas temperature was the most influential factor, because of its dominant effect on the radiative heat transfer to the slag layer. The solid slag thickness exponentially increased with higher gas temperatures. The influence of the ash deposition rate was diminished by the high-velocity region developed near the liquid slag surface. The slag viscosity significantly influenced the solid slag thickness through the corresponding changes in the critical temperature and the temperature gradient (heat flux). For the bottom cone of the gasifier, steeper angles were favorable in reducing the thickness of the slag layers. Full article
(This article belongs to the Special Issue Recent Advances in Coal Combustion and Gasification)
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Review

Jump to: Research

Open AccessReview On the Heat Flux Vector and Thermal Conductivity of Slags: A Brief Review
Energies 2016, 9(1), 27; https://doi.org/10.3390/en9010027
Received: 27 July 2015 / Revised: 21 December 2015 / Accepted: 30 December 2015 / Published: 6 January 2016
Cited by 1 | PDF Full-text (288 KB) | HTML Full-text | XML Full-text
Abstract
The viscosity and the thermal conductivity of slag are among two of the most important material properties that need to be studied. In this paper we review the existing theoretical and experimental correlations for the thermal conductivity of slag. However, since, in general,
[...] Read more.
The viscosity and the thermal conductivity of slag are among two of the most important material properties that need to be studied. In this paper we review the existing theoretical and experimental correlations for the thermal conductivity of slag. However, since, in general, slag behaves as a non-linear fluid, it is the heat flux vector which must be studied. Both explicit and implicit approaches are discussed and suggestions about the form of the heat flux vector and the thermal conductivity and their dependence on shear rate, porosity, deformation, etc. are provided. The discussion of the constitutive modeling of the heat flux vector for slag is from a theoretical perspective. Full article
(This article belongs to the Special Issue Recent Advances in Coal Combustion and Gasification)
Open AccessReview Modelling Underground Coal Gasification—A Review
Energies 2015, 8(11), 12603-12668; https://doi.org/10.3390/en81112331
Received: 18 August 2015 / Revised: 25 October 2015 / Accepted: 27 October 2015 / Published: 6 November 2015
Cited by 17 | PDF Full-text (8016 KB) | HTML Full-text | XML Full-text
Abstract
The technical feasibility of underground coal gasification (UCG) has been established through many field trials and laboratory-scale experiments over the past decades. However, the UCG is site specific and the commercialization of UCG is being hindered due to the lack of complete information
[...] Read more.
The technical feasibility of underground coal gasification (UCG) has been established through many field trials and laboratory-scale experiments over the past decades. However, the UCG is site specific and the commercialization of UCG is being hindered due to the lack of complete information for a specific site of operation. Since conducting UCG trials and data extraction are costly and difficult, modeling has been an important part of UCG study to predict the effect of various physical and operating parameters on the performance of the process. Over the years, various models have been developed in order to improve the understanding of the UCG process. This article reviews the approaches, key concepts, assumptions, and limitations of various forward gasification UCG models for cavity growth and product gas recovery. However, emphasis is given to the most important models, such as packed bed models, the channel model, and the coal slab model. In addition, because of the integral part of the main models, various sub-models such as drying and pyrolysis are also included in this review. The aim of this study is to provide an overview of the various simulation methodologies and sub-models in order to enhance the understanding of the critical aspects of the UCG process. Full article
(This article belongs to the Special Issue Recent Advances in Coal Combustion and Gasification)
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Open AccessReview Chemical-Looping Combustion and Gasification of Coals and Oxygen Carrier Development: A Brief Review
Energies 2015, 8(10), 10605-10635; https://doi.org/10.3390/en81010605
Received: 24 July 2015 / Revised: 6 September 2015 / Accepted: 16 September 2015 / Published: 24 September 2015
Cited by 21 | PDF Full-text (1471 KB) | HTML Full-text | XML Full-text
Abstract
Chemical-looping technology is one of the promising CO2 capture technologies. It generates a CO2 enriched flue gas, which will greatly benefit CO2 capture, utilization or sequestration. Both chemical-looping combustion (CLC) and chemical-looping gasification (CLG) have the potential to be used
[...] Read more.
Chemical-looping technology is one of the promising CO2 capture technologies. It generates a CO2 enriched flue gas, which will greatly benefit CO2 capture, utilization or sequestration. Both chemical-looping combustion (CLC) and chemical-looping gasification (CLG) have the potential to be used to generate power, chemicals, and liquid fuels. Chemical-looping is an oxygen transporting process using oxygen carriers. Recently, attention has focused on solid fuels such as coal. Coal chemical-looping reactions are more complicated than gaseous fuels due to coal properties (like mineral matter) and the complex reaction pathways involving solid fuels. The mineral matter/ash and sulfur in coal may affect the activity of oxygen carriers. Oxygen carriers are the key issue in chemical-looping processes. Thermogravimetric analysis (TGA) has been widely used for the development of oxygen carriers (e.g., oxide reactivity). Two proposed processes for the CLC of solid fuels are in-situ Gasification Chemical-Looping Combustion (iG-CLC) and Chemical-Looping with Oxygen Uncoupling (CLOU). The objectives of this review are to discuss various chemical-looping processes with coal, summarize TGA applications in oxygen carrier development, and outline the major challenges associated with coal chemical-looping in iG-CLC and CLOU. Full article
(This article belongs to the Special Issue Recent Advances in Coal Combustion and Gasification)
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Open AccessReview A Critical Review of Mineral Matter Related Issues during Gasification of Coal in Fixed, Fluidized, and Entrained Flow Gasifiers
Energies 2015, 8(9), 10430-10463; https://doi.org/10.3390/en80910430
Received: 3 August 2015 / Revised: 8 September 2015 / Accepted: 10 September 2015 / Published: 22 September 2015
Cited by 19 | PDF Full-text (968 KB) | HTML Full-text | XML Full-text
Abstract
Gasification of coal is gaining more popularity due to its clean operation, and its ability to generate products for various markets. However, these technologies are not widely commercialized due to reliability and economic issues. Mineral matter in coal plays an important role in
[...] Read more.
Gasification of coal is gaining more popularity due to its clean operation, and its ability to generate products for various markets. However, these technologies are not widely commercialized due to reliability and economic issues. Mineral matter in coal plays an important role in affecting the availability/reliability of a gasifier. Agglomeration in the bed, slag mobility and blockage of the syngas exit section are some of the operations related concerns in fixed-bed gasifiers, while ash deposition and sudden defluidization are the major concerns in fluidized bed gasifiers. In the case of entrained flow gasifiers, syngas cooler fouling and blockage, corrosion and erosion of refractory, and slag mobility are some of the major issues affecting the operations and the reliability of the gasifier. This review is aimed at critically examining various mineral matter related issues contributing to the operation and reliability problems in three types of generic gasifiers (fixed bed, fluidized bed and entrained flow gasifiers). Based on the review, some strategies to counter the potential mineral matter related issues are presented. Full article
(This article belongs to the Special Issue Recent Advances in Coal Combustion and Gasification)
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Open AccessReview Heat Recovery from High Temperature Slags: A Review of Chemical Methods
Energies 2015, 8(3), 1917-1935; https://doi.org/10.3390/en8031917
Received: 3 December 2014 / Revised: 13 January 2015 / Accepted: 5 March 2015 / Published: 12 March 2015
Cited by 32 | PDF Full-text (652 KB) | HTML Full-text | XML Full-text
Abstract
Waste heat recovery from high temperature slags represents the latest potential way to remarkably reduce the energy consumption and CO2 emissions of the steel industry. The molten slags, in the temperature range of 1723–1923 K, carry large amounts of high quality energy.
[...] Read more.
Waste heat recovery from high temperature slags represents the latest potential way to remarkably reduce the energy consumption and CO2 emissions of the steel industry. The molten slags, in the temperature range of 1723–1923 K, carry large amounts of high quality energy. However, the heat recovery from slags faces several fundamental challenges, including their low thermal conductivity, inside crystallization, and discontinuous availability. During past decades, various chemical methods have been exploited and performed including methane reforming, coal and biomass gasification, and direct compositional modification and utilization of slags. These methods effectively meet the challenges mentioned before and help integrate the steel industry with other industrial sectors. During the heat recovery using chemical methods, slags can act as not only heat carriers but also as catalysts and reactants, which expands the field of utilization of slags. Fuel gas production using the waste heat accounts for the main R&D trend, through which the thermal heat in the slag could be transformed into high quality chemical energy in the fuel gas. Moreover, these chemical methods should be extended to an industrial scale to realize their commercial application, which is the only way by which the substantial energy in the slags could be extracted, i.e., amounting to 16 million tons of standard coal in China. Full article
(This article belongs to the Special Issue Recent Advances in Coal Combustion and Gasification)
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