Global Coal Reserves Research Articles

Experimental Studies on Preheating Combustion Characteristics of Low-Rank Coal with Different Particle Sizes and Kinetic Simulation of Nitrogen Oxide

Low-rank coal, accounting for 45% of the global coal reserves, is easier to use in terms of realizing ignition and stable combustion due to its relatively high levels of volatile content. But the problem of low-rank coal combustion is that its NO formation is in the range of 300–600 mg/m3, which makes the emission’s meeting of the environmental regulation quite difficult or uneconomic. Preheating combustion was a prospective combustion technology which involved preheating in a circulating fluidized bed (CFB) first and then combustion in a combustor for preheated fuel. With three particle sizes (0–0.355 mm, 0–0.5 mm, and 0–1 mm), some experiments were carried out in a 30 kW test rig. The results showed that, in the CFB preheating, a particle size of 0–1 mm had the highest coal-gas heating value due to a long residence time. The release of species in the CFB preheating always followed the order H > N > C > S. For preheated fuel combustion, a particle size of 0–0.355 mm showed the fastest combustion velocity, with the highest temperature point near the nozzle. For all three particle sizes, the combustion of preheated fuel showed a uniform temperature distribution with a small temperature difference. The lowest NO emission was 105 mg/m3 for the particle size of 0–0.5 mm. A GRI-Mech 2.11 mechanism was used to simulate the formation of NO with different influencing factors, such as temperature, oxygen concentration, and secondary-air ratio. There was a good agreement between the experimental data and the simulation’s results. The simulation showed that the NO formation could be further decreased with an optimal secondary-air ratio. This investigation provides support for the basic understanding of preheating-combustion technology and potential industrial applications in the future.

Reconstructing the nanoscale porous structures in coal-based membranes by ultrafast high-temperature sintering for solar-driven water treatment

Lignite, a low-grade coal, accounts for over 40% of the global coal reserves. The use of lignite has been limited compared to other grades due to its low calorific value, high impurities content, and elevated volatile matter. Exploring a scalable and environment-friendly approach to upgrade lignite will offer new opportunities. In this work, Ultrafast High-Temperature Carbonization (UHC) has been developed to carbonize lignite and modify its nanoscale structure to construct a conductive porous membrane. The whole process takes only 30 s with an ultrafast heating rate reaching up to 9000 °C/min and a maximum temperature over 1500 °C. Upon heating the pore structures in the coal membrane evolves into micro- and mesopores with a specific surface area of over 300 m2/g. The carbonized coal-based membrane provides superior performance as a solar evaporator for water treatment, due to its interconnected porous structures, hydrophilicity, and over 85% absorption of full-band visible light. Under 1 sun solar irradiation, the membrane shows over 98.2% removal rate of salts, heavy metal ions, and volatile organic compounds (VOCs).

СУЧАСНІ ТРЕНДИ МЕХАНІЗОВАНОГО ВІДПРАЦЮВАННЯ ТОНКИХ ВУГІЛЬНИХ ПЛАСТІВ В СВІТЛІ КОНЦЕПЦІЇ MINING 4.0

Purpose. Analysis of modern trends in the development of technologies for underground mining of thin coal seams in order to identify common features and trends that allow understanding the place of Ukrainian coal enterprises and the world context. Methods. The work uses the method of engineering analysis, synthesis and generalization of information from various literary sources. Findings. More than 70% of Ukrainian coal is located in seams with a thickness of 0.7-1.2 m. Coal mining in such seams is associated with limited working space, which restrains the intensification of coal mining in the traditional way. The gradual reduction of global coal reserves in thick and medium seams leads to a change in the focus of the development of underground coal mining strategies to seams with an average thinkness of 0.8-1.3 m m, which becomes key in the strategic plans for the production of various coal basins. At the same time, the general trend is unmanned mining methods with a focus on unmanned mining. Already traditional small-body equipment for extracting coal with manual control is being replaced by intelligent mining systems. The modern intelligent system of mechanized mining of thin coal seams includes an electro-hydraulic control system of the longwall support, an automatic coal cutting system and a video surveillance system for the shearer and an integrated fluid supply system and a remote centralized control system. The elements of this system are analyzed in detail in the paper. Originality consists in establishing the general trend of the evolution of the technology of underground mining of thin coal seams by fully mechanized face. Practical implication. Research results can be used in the selection and justification of technological schemes of longwal mining, strategic and operational planning of the development of coal enterprises that extract thin coal seams.

International Energy Security Risk Index—Analysis of the Methodological Settings

The main objective of this paper is to analyze model settings of the International Energy Security Risk Index developed by the U.S. Chamber of Commerce. The study was performed using stepwise regression, principal component analysis, and Promax oblique rotation. The conclusion of the regression analysis shows that Crude Oil Price and Global Coal Reserves are sufficient to explain 90% of the variance of the Index. However, if a model that explains 100% of the variance of the Index is chosen and other variables are added, Global Coal Reserves loses importance due to the presence of other parameters in which it is contained. Regardless of the chosen model of analysis, it is evident that there is room for revising the Index and removing variables that do not contribute to its precision. The research showed that the main disadvantage of the variables that make up the Index rests with the fact that the variables are of different degrees of generality, that is, one parameter is contained in other parameters (unclear which other). The research covers data for 25 countries over a 26-year period, with the first year of the research being 1980 and the last 2016 (the latest available report).

Study on Development and Utilization of Shallow Geothermal Energy in Jilin Province

Under the current trend of striving for economic, energy-saving, low-carbon and environmental protection, geothermal energy has received wide attention due to its advantages such as energy conservation and environmental protection. The so-called geothermal energy is a kind of energy from the interior of the earth. It has a strong vitality. The heat stored in the earth is about 170 million times of the global coal reserves, and the annual heat from the earth through the surface is about 100 billion barrels. The thermal equivalent of petroleum. Shallow geothermal energy is an important part of the earth's thermal energy. It usually refers to the low-temperature geothermal resources located in the shallow rock mass of the earth's crust, which is located at a depth of 15 to 200 meters above the Earth's surface. In new and renewable energy sources, shallow geothermal energy is a new energy source that is competitive with current trends. This paper introduces the utilization and development of shallow geothermal energy in Jilin Province to enrich the research results of shallow geothermal energy in Jilin Province.

CFD ANALYSIS OF PULVERIZED COAL COMBUSTION IN A BLAST FURNACE TUYERE: COMPARISON BETWEEN WSGG AND GG MODELS FOR RADIATION MODELING

Combustion processes are being employed for many years, and remains a major source of energy for industrial operations through the conversion of chemical energy in thermal energy, besides being usually accompanied by formation of pollutants. This work presents a numerical investigation using the software Ansys CFX to model the process of combustion of pulverized coal injected into a blast furnace for production of pig iron making a comparison between WSGG and GG spectral models for gas radiation aim to verify the influence on the radiation heat transfer and the temperature field. Since global coal reserves are being constantly reduced, new techniques using coal are being studied. Among some effective techniques, there is the injection of pulverized coal through a tuyere installed at the bottom of the blast furnace. Thus, among the objectives of this work is to obtain information about the pulverized coal burning process injected. Firstly, it will be employed a North American coal as a base case in order to better understand the involved phenomena. Simulations were made using the actual operating conditions of a blast furnace, which uses atmospheric air enriched with oxygen for burning the coal. The same boundary conditions and operation of other investigations were considered in order to validate the model developed for this work, and so that it can be applied in similar situations, either in assessments or in projects of coal injection systems and combustion in blast furnaces. The results include temperature and velocity fields, oxygen concentration, and the formation of CO and CO2 and they are in agreement with data from literature. Comparing the results of this study with the results obtained in the work (Gu et al., 2010) It observed a qualitative similarity between them and also quantitative. Furthermore, it was found that, in this case, modeling the absorption spectrum of the combustion gases resulting in changes in flame form, but did not significantly alter the magnitude of temperatures, since the walls of the equipment are considered adiabatic.

Twenty-first century, the century of coal? CO2prices to curb coal demand

The paper investigates how a carbon price could halt the comeback of coal, which started in the early 2000s. Since the year 2000, coal has provided roughly 40 per cent of global primary energy growth. The success of coal in the primary energy mix is due to the fact that it is abundant, cheap, and most often a domestic resource. However, global coal reserves, if burnt, would surpass the remaining carbon budget for a 2°C target by a factor of two. The paper shows that a carbon price of 25–100 USD per tonne of CO2 would be needed to phase out coal in the power sector, depending on the technology and the world region, even when assuming significant technological progress.

Report on comparison among current industrial scale lignite drying technologies (A critical review of current technologies)

Lignite constitutes a major energy source and has long been used for energy production despite its contribution in greenhouse gas (GHG) emissions, as a fossil fuel. For example, 27.4% of Germany’s electricity originates from lignite power plants, while in Greece more than 55% of its electric energy consumption is provided by lignite. 45% of the total global coal reserves consist of low-rank coals (LRCs) such as lignite. With this background, the utilization of lignite for energy production is expected to remain a common practice in the decades to come since the availability of lignite is considerable in many countries of Europe and the world (e.g. Germany, Poland, Greece, USA, and Australia). Therefore, problems regarding the combustion and use of lignite should be addressed in a more efficient and environmentally friendly way. One of the main existing problems is the high moisture contained in raw lignite as received from the mine. The high moisture content results in higher CO2 emissions per unit of energy produced and is responsible for high capital and transport costs as well as other technical problems such as reduction in coal friability and difficulties in its blending and pneumatic transportation. Therefore, processing of lignite through drying is considered of great interest in the implementation of energy production in lignite power plants. Taking into account the significance of the subject and the usefulness of such an attempt, an overview of the currently existing drying technologies, including both evaporative and non-evaporative drying methods is reported in the present paper.

Why There Will Be No Peak Coal in the Foreseeable Future

Hard coal and lignite—also referred to here jointly as coal—play a central role in the worldwide supply of humanity with primary energy. As a fossil energy carrier, coal is one of the finite natural resources. The reach of the world’s coal reserves is significant, and coal has the potential to cover some of the global energy and raw-material needs at least into the 22nd century. Precondition for this is a sustainable energy policy, i.e. an equal-ranking view of the goals of environmental and climate compatibility (sustainability), security of supply and competitiveness (affordability). The focus of developments is on resource efficiency and energy savings to obtain more modern and more efficient coal-based power plants. Greater use of coal translates into higher CO2 emissions. So if we are to achieve the climate-protection goals of limiting the rise in temperatures and reducing the CO2 content in the Earth’s atmosphere, the launch of CCS technology is recommended. Within the scope of the climate-protection debate, a discussion is also underway about an alleged drying up of coal availability in the short term (under the heading of “peak coal”). This discussion is an example of how, from the limited perspective of particular interests, a swathe of facts can be ignored. Hence, this article sets out to take a fact-based, sober look at the subject of the “reach of global coal reserves”. How much coal do we really have? And to what extent will coal be available tomorrow to guarantee secure and affordable energy supplies in the future as well? These issues will be investigated here.

Clean liquid fuels from direct coal liquefaction: chemistry, catalysis, technological status and challenges

Increased demand for liquid transportation fuels coupled with gradual depletion of oil reserves and volatile petroleum prices have recently renewed interest in coal-to-liquids (CTL) technologies. Large recoverable global coal reserves can provide liquid fuels and significantly reduce dependence on oil imports. Direct coal liquefaction (DCL) converts solid coal (H/C ratio ≈ 0.8) to liquid fuels (H/C ratio ≈ 2) by adding hydrogen at high temperature and pressures in the presence or absence of catalyst. This review provides a comprehensive literature survey of the coal structure, chemistry and catalysis involved in direct liquefaction of coal. This report also touches briefly on the historical development and current status of DCL technologies. Key issues, challenges involved in DCL process and directions for the future research are also addressed.

The Impact of Carbon Capture and Storage on Coal Resource Depletion

Carbon Capture and Storage is being actively developed for deployment in fossil fuel power stations in an attempt to reduce future emissions of CO2 due to concerns about climate change. The deployment of this technology will cause an inevitable reduction in the overall efficiency of any electricity generation plant leading to an increase in demand for the fossil fuels used to power the generation process. This paper estimates the average reduction in generation efficiency caused by the imposition of Carbon Capture and Storage and considers its effects upon the depletion rate of global coal reserves. Future production of coal is modelled using a symmetrical production curve. The results suggest that the widespread adoption of Carbon Capture and Storage may result in the exhaustion of coal reserves several decades in advance of when this may happen if CCS is not deployed.