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Coal Conversion Processes
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Coal Conversion Processes

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "H: Geo-Energy".

Deadline for manuscript submissions: closed (1 May 2021) | Viewed by 20465

Special Issue Editors

Dr. Panagiotis Grammelis

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Guest Editor
Centre for Research & Technology Hellas, Chemical Process and Energy Resources Institute (CERTH/CPERI), 4th km. N.R. Ptolemais-Mpodosakeio, 50200 Ptolemais, Greece
Interests: energy efficiency and environmental technologies for the exploitation of solid fuels; market uptake of new solid biofuels, waste and gaseous fuels, e.g., LNG; advanced energy systems of low or zero carbon footprint and process modelling
Special Issues, Collections and Topics in MDPI journals
Dr. Aristeidis Nikolopoulos

E-Mail Website
Guest Editor
Chemical Process and Energy Resources Institute, Centre for Research and Technology Hellas (CERTH), 52 Egialias Str., Marousi, GR-15125 Athens, Greece
Interests: CO2 capture; power plant’s flexibility; co-combustion; fludized bed reactors; CFD
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

This Special Issue focuses on the coal conversion processes through the prism of the transition to a CO2-neutral energy production. The primary exploitation path of coal, i.e., coal combustion for energy production, is strongly affected by CO2 emission-related penalties. This Special Issue presents the new policy and scientific developments for a more sustainable exploitation of coal that will enable versatility and provide energy security. High-quality technical knowledge and research results from specific tests around the world are being analyzed, providing a holistic view of the main aspects of the coal exploitation issue. The respective policies and the role of coal in the new era is analyzed, and the technical challenges are identified. Flexible coal plants will support and boost electrification, providing grid stability to the highly RES-penetrated electricity grids, while CCU&S technologies can promote the environmentally benign use of coal in the energy sector. However, as the coal-based energy production will be reduced, alternative paths are scrutinized. This includes coal liquefaction, underground gasification, co-combustion, and co-gasification with biomass and waste.

Dr. Panagiotis Grammelis
Dr. Aristeidis Nikolopoulos
Guest Editors

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Keywords

  • coal co-combustion
  • CCU
  • CCS
  • coal liquefaction
  • co-gasification
  • coal policy

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Related Special Issue

Published Papers (7 papers)

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Research

21 pages, 8621 KiB  
Article
Research on Directional Controllability of Cracking in Hydraulic Fracturing of Hard Overburden Based on Local Stress Field Intervention
by Dingchao Chen, Xiangyu Wang, Feiteng Zhang, Menglong Li, Xiangqian Zhao, Guanjun Li, Yang Yu, Guanghui Wang, Jiaxin Zhao and Xiangdong Wang
Energies 2022, 15(12), 4252; https://doi.org/10.3390/en15124252 - 9 Jun 2022
Cited by 9 | Viewed by 1658
Abstract
As a widely-used method of digging roadways in China, gob-side entry driving features specific advantages, such as a high recovery rate and good isolation effects. However, under the condition of hard overburden, the excessive bearing pressure of small coal pillars will easily cause [...] Read more.
As a widely-used method of digging roadways in China, gob-side entry driving features specific advantages, such as a high recovery rate and good isolation effects. However, under the condition of hard overburden, the excessive bearing pressure of small coal pillars will easily cause serious internal damage in the coal and the run-through of the plastic zone, leading to harmful gas leakage in the goaf. Therefore, based on the engineering background of small coal pillars in the 18506 working face of Xiqu Coal Mine, this paper comprehensively adopts theoretical analysis, numerical simulation, industrial tests, and other methods, analyzes the evolution mechanism of isolated bearing and plastic fracture areas of small coal pillar under hard overburden, studies the influence law of hard overburden cutting parameters on the isolation and stability of small coal pillars, and puts forward the technology of actively cutting the top to weaken the stress concentration of coal pillars under hard overburden. With the reasonable cutting parameters determined, the controllable mechanism of hydraulic fracturing cutting under hard overburden further revealed, and the hydraulic fracturing cutting technology with “controllable cutting orientation of hydraulic fracturing with local stress field intervention” formed as the basic core, the stress situation on the roof is improved, realizing the stability control of the coal pillars for the roadway protection, and avoiding gas leakage and other disasters caused by small coal pillar destruction. Full article
(This article belongs to the Special Issue Coal Conversion Processes)
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18 pages, 5336 KiB  
Article
Study on the Combined Mining Scheme for Coal Resources under High-Voltage Pylons and the Reinforcement for Pylons
by Hongyang Liu, Mingrui Du, Boyang Zhang, Zhibin Lin, Chengwei Liu and Feng Wang
Energies 2022, 15(11), 3978; https://doi.org/10.3390/en15113978 - 27 May 2022
Cited by 1 | Viewed by 2042
Abstract
The increasing use of high-voltage transmission wires requires more and more high-voltage pylons, and sometimes, constructing pylons in mining areas is very urgent. To ensure the safe operation of pylons, coal pillars with large side lengths are usually used to provide sufficient support; [...] Read more.
The increasing use of high-voltage transmission wires requires more and more high-voltage pylons, and sometimes, constructing pylons in mining areas is very urgent. To ensure the safe operation of pylons, coal pillars with large side lengths are usually used to provide sufficient support; however, this results in a huge waste of coal. Eight high-voltage pylons are arranged on the ground surface corresponding to the location of working face 1110 of Sima Coal Mine in Shanxi Province, China, which cannot be mined by traditional methods. Taking this as the engineering background, the failure mode of high-voltage pylon is first analyzed. Using FLAC3D numerical simulations, the influence of five different mining plans on ground surface deformation in working face 1110 is evaluated, and the vertical settlement and horizontal deformation in different areas of the ground surface, as well as the variation law of horizontal strain and slope are analyzed. According to the numerical simulation results, the range of thickness-limiting mining or backfill mining in working face 1110 is shown in scheme 3, and the key regions in the mining process are determined. Secondly, the strengthening scheme of high-voltage pylons is designed, that is, the four foundations of high-voltage pylons are connected as a whole with steel supports and steel connectors so as to improve the structural strength of the high-voltage pylon. Finally, the position change in the foundation of high-voltage pylons was monitored for 22 consecutive months. The results show that the maximum settlement of the high-voltage tower foundation is 3.1 m, which is consistent with the actual mining thickness; The high-voltage pylon was stably moved, and the change in transmission line tension and total length was usually less than 1.0%. The combined mining scheme and foundation strengthening scheme can ensure the safe operation of high-voltage pylons and provide a new method for the stability control of ground buildings in coal mining subsidence area. Full article
(This article belongs to the Special Issue Coal Conversion Processes)
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14 pages, 3665 KiB  
Article
Investigation and Control Technology on Excessive Ammonia-Slipping in Coal-Fired Plants
by Xuan Yao, Man Zhang, Hao Kong, Junfu Lyu and Hairui Yang
Energies 2020, 13(16), 4249; https://doi.org/10.3390/en13164249 - 17 Aug 2020
Cited by 10 | Viewed by 2836
Abstract
After the implementation of the ultra-low emissions regulation on the coal-fired power plants in China, the problem of the excessive ammonia-slipping from selective catalytic reduction (SCR) seems to be more severe. This paper analyzes the operating statistics of the coal-fired plants including 300 [...] Read more.
After the implementation of the ultra-low emissions regulation on the coal-fired power plants in China, the problem of the excessive ammonia-slipping from selective catalytic reduction (SCR) seems to be more severe. This paper analyzes the operating statistics of the coal-fired plants including 300 MW/600 MW/1000-MW units. Statistics data show that the phenomenon of the excessive ammonia-slipping is widespread. The average excessive rate is over 110%, while in the small units the value is even higher. A field test data of nine power plants showed that excessive ammonia-slipping at the outlet of SCR decreased following the flue-gas process. After most ammonia reduced by the dust collector and the wet flue-gas desulfurization (FGD), the ammonia emission at the stack was extremely low. At same time, a method based on probability distribution is proposed in this paper to describe the relationship between the NH3/NOX distribution deviation and the De–NOX efficiency/ammonia-slipping. This paper also did some original work to solve the ammonia-slipping problem. A real-time self-feedback ammonia injection technology using neural network algorithm to predict and moderate the ammonia distribution is proposed to decrease the NH3/NOX deviation and excessive ammonia-slipping. The technology is demonstrated in a 600-MW unit and works successfully. The excessive ammonia-slipping problem is well controlled after the implementation of the technology. Full article
(This article belongs to the Special Issue Coal Conversion Processes)
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Graphical abstract

9 pages, 1128 KiB  
Article
A Preliminary Techno-Economic Analysis on the Calcium Looping Process with Simultaneous Capture of CO2 and SO2 from a Coal-Based Combustion Power Plant
by Antonio Coppola and Fabrizio Scala
Energies 2020, 13(9), 2176; https://doi.org/10.3390/en13092176 - 1 May 2020
Cited by 16 | Viewed by 2552
Abstract
The increase of capital investments and operation and maintenance (O&M) costs represents a current limitation to the diffusion of carbon capture systems for the clean combustion of fossil fuels. However, post-combustion systems, such as calcium looping (CaL), for CO2 capture from flue [...] Read more.
The increase of capital investments and operation and maintenance (O&M) costs represents a current limitation to the diffusion of carbon capture systems for the clean combustion of fossil fuels. However, post-combustion systems, such as calcium looping (CaL), for CO2 capture from flue gas are the most attractive carbon capture systems since they can be installed at new plants and retrofitted into existing power plants. This work investigates the pros and cons of employing a calcium looping system for CO2 capture and also as a desulphurization unit. A preliminary techno-economic analysis was carried out comparing a base case consisting of a coal-based power plant of about 550MWe with a desulphurization unit (Case 1), the same plant but with a CaL system added for CO2 capture (Case 2), or the same plant but with a CaL system for simultaneous capture of CO2 and SO2 and the removal of the desulphurization unit (Case 3). Case 2 resulted in a 67% increase of capital investment with respect to the benchmark case, while the increase was lower (48%) in Case 3. In terms of O&M costs, the most important item was represented by the yearly maintenance cost of the desulphurization unit. In fact, in Case 3, a reduction of O&M costs of about 8% was observed with respect to Case 2. Full article
(This article belongs to the Special Issue Coal Conversion Processes)
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17 pages, 494 KiB  
Article
Synthesis Gas Composition Prediction for Underground Coal Gasification Using a Thermochemical Equilibrium Modeling Approach
by Christopher Otto and Thomas Kempka
Energies 2020, 13(5), 1171; https://doi.org/10.3390/en13051171 - 4 Mar 2020
Cited by 17 | Viewed by 3585
Abstract
Underground coal gasification (UCG) is an in situ conversion technique that enables the production of high-calorific synthesis gas from resources that are economically not minable by conventional methods. A broad range of end-use options is available for the synthesis gas, including fuels and [...] Read more.
Underground coal gasification (UCG) is an in situ conversion technique that enables the production of high-calorific synthesis gas from resources that are economically not minable by conventional methods. A broad range of end-use options is available for the synthesis gas, including fuels and chemical feedstock production. Furthermore, UCG also offers a high potential for integration with Carbon Capture and Storage (CCS) to mitigate greenhouse gas emissions. In the present study, a stoichiometric equilibrium model, based on minimization of the Gibbs function has been used to estimate the equilibrium composition of the synthesis gas. Thereto, we further developed and applied a proven thermodynamic equilibrium model to simulate the relevant thermochemical coal conversion processes (pyrolysis and gasification). Our modeling approach has been validated against thermodynamic models, laboratory gasification experiments and UCG field trial data reported in the literature. The synthesis gas compositions have been found to be in good agreement under a wide range of different operating conditions. Consequently, the presented modeling approach enables an efficient quantification of synthesis gas quality resulting from UCG, considering varying coal and oxidizer compositions at deposit-specific pressures and temperatures. Full article
(This article belongs to the Special Issue Coal Conversion Processes)
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20 pages, 5790 KiB  
Article
Research on the Processes of Injecting CO2 into Coal Seams with CH4 Recovery Using Horizontal Wells
by Jarosław Chećko, Tomasz Urych, Małgorzata Magdziarczyk and Adam Smolinski
Energies 2020, 13(2), 416; https://doi.org/10.3390/en13020416 - 15 Jan 2020
Cited by 22 | Viewed by 2981
Abstract
The paper presents a research study on modeling and computer simulation of injecting CO2 into the coal seams of the Upper Silesian Coal Basin, Poland connected with enhanced coal bed methane (ECBM) recovery. In the initial stage of the research activities, a [...] Read more.
The paper presents a research study on modeling and computer simulation of injecting CO2 into the coal seams of the Upper Silesian Coal Basin, Poland connected with enhanced coal bed methane (ECBM) recovery. In the initial stage of the research activities, a structural parameter model was developed specifically with reference to the coal-bearing formations of the Upper Carboniferous for which basic parameters of coal quality and the distribution of methane content were estimated. In addition, a lithological model of the overall reservoir structure was developed and the reservoir parameters of the storage site were analyzed. In the next stage of the research, the static model was supplemented with detailed reservoir parameters as well as the thermodynamic properties of fluids and complex gases. The paper discusses a series of simulations of an enhanced coalbed methane recovery process with a simultaneous injection of carbon dioxide. The analyses were performed using the ECLIPSE software designed for simulating coal seam processes. The results of the simulations demonstrated that the total volume of CO2 injected to a designated seam in a coal mine during the period of one year equaled 1,954,213 sm3. The total amount of water obtained from the production wells during the whole period of the simulations (6.5 years) was 9867 sm3. At the same time, 15,558,906 sm3 of gas was recovered, out of which 14,445,424 sm3 was methane. The remaining 7% of the extracted gas was carbon dioxide as a result of reverse production of the previously injected CO2. However, taking into consideration the phenomena of coal matrix shrinking and swelling, the total amount of injected CO2 decreased to approximately 625,000 sm3. Full article
(This article belongs to the Special Issue Coal Conversion Processes)
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22 pages, 9978 KiB  
Article
Drying of Lignite of Various Origins in a Pilot Scale Toroidal Fluidized Bed Dryer using Low Quality Heat
by Halina Pawlak–Kruczek, Michał Czerep, Lukasz Niedzwiecki, Emmanouil Karampinis, Ioannis Violidakis, Ioannis Avagianos and Panagiotis Grammelis
Energies 2019, 12(7), 1191; https://doi.org/10.3390/en12071191 - 27 Mar 2019
Cited by 7 | Viewed by 3881
Abstract
An experimental study was carried out for lignites of different places of origin, i.e., Poland, Greece, Romania and Australia, using a toroidal bed dryer. The effect of the temperature on the drying efficiency, including the loss of moisture content over time under fixed [...] Read more.
An experimental study was carried out for lignites of different places of origin, i.e., Poland, Greece, Romania and Australia, using a toroidal bed dryer. The effect of the temperature on the drying efficiency, including the loss of moisture content over time under fixed drying conditions was the subject of the investigation. The main goal was to confirm the possibility of the use of a toroidal bed as a base for a drying system that could utilize low quality heat from sources such as flue gases from a boiler and determine the optimum parameters for such a system. The conducted study has conclusively proven the feasibility of the use of low temperature heat sources for drying lignite in a toroidal bed. A moisture content of 20% could be achieved for most of the tested lignites, using the toroidal bed, with reasonably short residence times (approx. 30 min) and an air temperature as low as 60 °C. Moreover, the change of the particle size distribution, to some degree, affected the final moisture content due to the entrainment of wet, fine particles. The study also determined that the in-bed attrition of the particles is partially responsible for the generation of fines. Full article
(This article belongs to the Special Issue Coal Conversion Processes)
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