Showing papers on "Clean coal technology published in 2019"

The approach of biodesulfurization for clean coal technologies: a review

Abstract: Coal continues to be a significant source of energy in the world. It is very important to utilize this energy source as much as possible, to operate unutilized loss reserves due to its characteristics. In this context, the necessity to continue studying on clean coal technologies was emphasized in terms of sustainability in energy production and its use, safety and environmental issues. Since approximately 50% of total coal deposits of the world are low rank, it is required to clean them by implementing different and efficient technologies to improve the utilization of low-rank coals. This review summarized the importance of clean coal technology, biological treatments until now, recent advances and future trends in coal biobeneficiation technologies as energy-conserving and environmentally friendly processes. Finally, in light of the data obtained from all studies, the basic steps for the possible use of biocleaning methods in industrial scale are also summarized in this review.

Purified high-sulfur coal as a fuel for direct carbon solid oxide fuel cells

Abstract: The use of low-rank coal in a clean and efficient manner is a major challenge facing the current coal technology. A high-sulfur coal with 4.5 wt% sulfur is chosen to examine the compatibility of the pristine coal and the purified contrast with a solid oxide fuel cell (SOFC) with nickel cermet anodes. Desulfurization of the pristine coal is performed by molten caustic leaching method with a removal ratio of 80%. Analyses of the physicochemical properties of coal samples indicate that the purified coal has a more favorable structure and higher Boudouard reactivity, which is suitable as a fuel for fuel cells. The assessment of electrochemical performance reveals that the purification treatment not only makes the peak power density of SOFCs improve from 115 to 221 mW cm at 900°C but also extends their durability from 1.7 to 11.2 hours under a current density of 50 mA cm at 850°C with a fuel availability increasing from 6.25% to 40%. The postmortem analyses show that far less deposited carbon and nickel sulfide are observed on the anode surface. The fuel-based investigation reveals that the purified coal is a promising fuel for direct carbon fuel cells.

Simultaneous Extraction of Clean Coal and Rare Earth Elements From Coal Tailings Using Alkali-Acid Leaching Process

Abstract: With the supply restriction from traditional rare earth deposits, alternative sources of rare earth elements (REEs) such as coal are being studied. The United States National Energy Technology Laboratory has identified US coal deposits as a potential source of rare earth elements. Several techniques such as physical separation, flotation, ion-exchange, agglomeration, and leaching are being evaluated for the successful exploitation of these elements from coal and its by-products. A previous study published in the Geoscience BC 2018 mineral report on the characterization of REE in the British Columbian coal samples have shown that a major portion of the rare earth in the run of mine coal reports to the middling and tailing streams. Hence, this study is focused on the extraction of the rare earth from coal tailings. Several studies have shown the use of an alkali-acid leaching process to successfully demineralize various high ash coals to produce a clean coal concentrate since the ash-bearing components such as clay and quartz were removed from the coal during this process. In this study, the alkali-acid leach process was adopted to chemically clean coal tailings as well as to extract rare earth elements. Different process parameters such as sodium hydroxide (NaOH) concentration, temperature, and time were studied. Results showed that it is possible to extract more than 85% of REE with this process and simultaneously produce clean coal from coal tailing.

Contributions For Latin America Of The EU ETS Phase 4

Abstract: The urgency in mitigating climate change has led to the establishment of agreements, including the Paris agreement (phase IV) whose implementation will be from 2020 and with this it is expected to reduce greenhouse gas emissions by at least 40% by 2030 compared to 1990. The heart of EU climate policy is the EU's emissions trading system (EU ETS). One of the leading sectors in the emission of CO2, especially in Europe, is the electricity sector. The objective of this paper is to model the operation of the EU ETS under the Paris Agreement and its implications on the short-term market of the electricity sector in Germany. Among the results is a significant reduction in CO2 emissions, mainly caused by changes in the installed capacity of the technologies in the market. The generation of electricity by renewable sources and, consequently, the emissions of the sector, depend on installed capacity of renewable energies and the disinvestment in coal technology. It is also found that under the conditions of phase IV for EU ETS there will still be oversupply of permits, therefore, the secondary market does not operate.

Non-isothermal kinetics analysis of various Indonesian coal thermal characteristics for underground coal gasification purposes

Abstract: Indonesia has abundant coal resources. However, some of the coal is difficult to be mined because of its location. Some are too far below the soil surface, or also called Deep Seated Coal (DSC). Underground Coal Gasification (UCG) is an alternative Clean Coal Technology that carried out gasification underground, thus it may have a potential explore DSC. The primary assessment of underground gasification may be started from a simple thermal analysis. This paper presents those assessment on the characteristics of gasification for further prospects of underground coal gasification implementation in Indonesia. The gasification experiments were carried out in a Thermogravimetric Analyser by using ten samples of coal from various locations in Indonesia. The experimental parameters include gasification media (CO2 or air) at temperature ranges from 35°C to 900°C and a heating rate of 10°C/min. The gasification media is passed at a rate of 100mL/min. Data of weight loss of sample were obtained from this experiment. From the experimental results, Arrhenius constants obtained on gasification with air are in the range 55643 to 114245 min−1 with the activation energy of 46.26 to 96.98 kJ/mol. Meanwhile, the gasification with CO2 yields Arrhenius constant 15301 up to 61339 min−1 and the activation energy of 12.72 to 109.71 kJ/mol. Those kinetics data provide the basic information for further exploring the possibility of underground coal gasification.

Clean coal technology using an iron- and sulfur-oxidizing mixotrophic bacterium

Abstract: Coal is one of the important energy sources in the world. It has been part of the important roles for centuries, not only for generating electricity but also the main fuel for steel and cement production as well as other industrial activities. However, the quality of the coal is generally too low for the practical, economical utilization. High sulfur and ash contents come up as one of the barriers in the productive usage of indigenous coal. Clean coal technology such as coal biobeneficiation can appear as a panacea for upgrading the coal reserves with high sulfur and ash contents. In the current study, the removal potential of the sulfur and ash content from coal of Kalimantan, Indonesia was investigated by using the bacterium Pseudomonas moraviensis. It was reported for the first time that the bacterium had the capability to remove about 17.37% of total sulfur and ash content from the coal. The results revealed that the bacterium Pseudomonas moraviensis used in this study could remove sulfur and ash content from the coal and could thus be used in the pre-combustion operation with appropriate arrangement.

Gasification and Liquefaction: Their Potential Impact on Various Aspects of the Coal Industry

Abstract: This study examines projections of demand for natural gas and gasoline and estimated reserves available to meet these demands. Projections for the period 1980 to 2000 are studied in terms of coal equivalent, and estimates are made of tonnages of coal, number of mines, employees, investment, and coal acreages that would be required if growth were to be supplied by gas and gasoline produced from coal. Geographic, geologic, and market factors that will influence location of future coal liquefaction and gasification plants also are considered.

Modelling of design parameters of intrinsically safe instruments for the safety of oil, gas and coal industries

Abstract: Intrinsic safety is the safest technique to prevent explosions that might occur in underground coal mines and process industries in the presence of explosive atmosphere. Designing of intrinsically safe equipment require keeping its energy below the minimum ignition energy of the explosive gases. In this work, three empirical relations based on standard IS/IEC 60079-11 have been proposed for the first time and used in the calculation of short circuit current (I), permitted capacitance (C) and inductance (L) of intrinsically safe circuits designed for gas groups IIA, IIB, IIC and I. The calculated values are compared with the available experimental and reported values. A fairly good agreement has been obtained between them. The designers of intrinsically safe circuits can use these relations as a very handy tool especially for the explosive gas atmosphere of underground coal mines and process industries. This research will contribute to the reduction of fatal accidents due to explosive gases. [Received: August 20, 2017; Accepted: March 11, 2018]

Experimental Investigation on Sodium Migration and Mineral Transformation in Ash Deposit During Gasification of Zhundong Coal Using a Drop Tube Furnace

Abstract: Zhundong coal has attracted an ever-increasing concern due to its super-huge reserve but high content of alkali metals. Volatilized into the gaseous phase during the gasification process, alkali metals are extremely unfavorable for coal utilization. Gasification technology can promote the large-scale utilization of high-alkali coal. However, few efforts, if any, have been conducted on gasification of Zhundong coal. The present study aimed to elucidate the sodium migration and mineral transformation characteristics in coal ash deposition process under different gasification conditions, while the behavior of sodium migration and mineral transformation were further analyzed using Inductively Coupled Plasma-Atomic Emission Spectrometer (ICP-OES), X-ray diffraction (XRD) and X-ray fluorescence (XRF) techniques. In this paper, the sodium migration characteristics in gasification process under different conditions were investigated by adding three sodium salts (NaCl, Na2CO3 and Na2SO4), kaolin and diatomite into coal, respectively. The effects of ash deposition time on sodium migration and mineral transformation characteristics in ash were also explored. The experimental results showed that the addition of sodium salt could increase the sodium content in the ash to a large extent. Kaolin and diatomite could solidify alkali metals in the gaseous phase during gasification process. As the ash accumulation time increased, the minerals such as chlorine, sulphur, and iron in the gaseous phase were easily bonded to the surface of the ash and reacted to form other crystal phases. The present study can provide guidance for the utilization of Zhundong coal and benefit the development of clean coal technology.