Coal Carbon Research Articles

Nano activated carbon from industrial mine coal as adsorbents for removal of dye from simulated textile wastewater: operational parameters and mechanism study

Feasibility studies were conducted in the preparation of an effective activated carbon (AC) using the new raw Egyptian coal source called Maghara coal. Using this is eco-friendly, economical and highly available since it is a local and a natural material; thus, it was inspected for the removal of methylene blue (MB) dye from aqueous solutions. A very simple technique known as impregnation activated carbon with NaOH by chemical activation process was used. The most proper nano-activated carbon (NAC) was produced from carbonization of average particle size coal of 0.478 mm at 550 °C for 90 min. with 50% NaOH and ratio 35. The equilibrium data of MB onto the most effective prepared material was simulated using Langmuir and Freundlich isotherm models. Moreover, the adsorption mechanism of MB onto the prepared nano-activated carbon was suggested to take place as mono-layers adsorption on the homogenous active sites. The maximum mono-layers adsorption capacity was recorded as 28.09 mg/g. The morphological, chemical, and textural properties of the prepared NaOH activated carbon was investigated using TEM, Raman spectroscopy, FT-IR, and BET. Results indicated that the material was prepared at spherical shape with average diameter of 38 nm with high total pore volume of 0.183 cm3/g. The adsorption stability and reuseability of NAC was established using HCl as an eluent solution. The findings revealed the versatility of Maghara coal as a good precursor for the preparation of high quality, efficient and economical NAC.

Assessment of carbonization of coal as a potential strategy to reduce emissions for domestic applications

Coal mining areas in India have a large number of households that use raw coal for cooking. Emissions from such cookstoves lead to issues of both ambient as well as indoor air pollution. Several studies report that PM ≤ 2.5 μm emissions from coal cookstoves are influenced by the volatile content of the coal. The present study investigates the effect of temperature of carbonization on the extent of reduction in PM ≤ 2.5 μm emissions for two types of bituminous coals. Raw coals and coals carbonized at 200, 400 and 600 °C, are burnt in two different types of domestic cookstoves. PM ≤ 2.5 μm, EC-OC, and CO measurements are made in a 90-min combustion cycle. Emissions are found to decrease from 20 to 70% for the two coals carbonized at 400 and 600 °C. The corresponding ignition temperatures are also estimated for the fuels to address the issue of ignitability with traditional methods. Emission factors for PM ≤ 2.5 μm, CO and EC-OC are developed, and suggest that carbonization at 600 °C is adequate for minimizing PM emissions while assuring ignitability in the cookstoves tested.

Optimization and evaluation of a dispatch model for an integrated wind-photovoltaic-thermal power system based on dynamic carbon emissions trading

To transmit renewable energy on-grid over a large-scale power transmission system, an optimal dispatch model for a multi-energy power generation system is essential. This paper proposed a multi-energy hybrid power dispatch model for an integrated wind-photovoltaic-thermal power system. We consider five different dispatch modes and a dynamic carbon emissions trading system. Design of the modes was based on dispatch objectives. Power dispatch was based on interactive planning of power units and carbon emissions trading. To compare the modes, a comprehensive benefit evaluation index for dispatching is established. The proposed model was applied to supporting power supply system of the Tianzhong ultra-high voltage direct-current transmission project in Xinjiang, China. The results confirmed that high-efficiency mode is an optimal dispatch mode for the power transmission system, and has the most significant benefits. The impact on the optimal mode of the renewable energy penetration rate and carbon emissions trading system, as the two main factors, were further investigated. It was found that high-efficiency mode could maximize existing renewable energy generation and reduce coal consumption and carbon emission used for power generation and has a positive effect on carbon reduction. However, initial quotas need to be controlled more strictly than prices.

Effect of Silicon Inclusion Carbonaceous Composite Particulate on the Thermal-Ageing Characteristics and Mechanical Performance of Low Carbon Steel

This study focus on the effects of silicon inclusion carbonaceous particulate on the hardness and microstructural properties of carburized low carbon steel, at constant temperature of 900 °C with different holding time from 2 to 5 h. The cow bone and coal dust composite particles were varied with 20% CaCO3 used as the energizer. Hardness and microstructural testing of the various specimens were then carried out using Vickers hardness machine and metallurgical scanning electron microscope. From the result, it was noticed that there was an increase in microhardness performance on both cow bone and coal dust reinforced matrix compared to the as-received samples. For coal dust carburized carbon steel, the hardness value improved from 286 HVN control samples 434.55 HVN in 5 h. It was seen that the introduction of cow bone composite particulate also provides a reasonable mechanical hardness improvement to 418.2 HVN although a little short fall against the coal dust metal matrix. From the microstructure and macrostructure studies highly pearlitic matrix steel was observed with grain refinement of CB and CD found at the interface providing an effective nucleation site along the boundaries.

Stress response of noncovalent bonds in molecular networks of tectonically deformed coals

Investigations on macromolecular evolution of tectonically deformed coals are of great theoretical and practical significances for the coal safe production and coalbed methane exploitation. Alteration of covalent bonds in rigid coal carbon skeletons was studied extensively, while insufficient attention was paid to the variation of noncovalent bonds in macromolecular networks. In present study, some insights about stress response of noncovalent bonds are given by investigating a primary coal and six typical tectonically deformed coals collected around a fault structure. Self-associated n-mers (n > 3), OH-ether, cyclic OH, COOH dimers, OH-SH and OH-N are all disrupted by tectonic stress, which is partially resulted from dissociation of functional groups. Conversely, amount of OH-π is in an increasing trend, indicating that there is a transformation between OH-π and other hydrogen bonds. In general, the total content of hydrogen bonds generally decreases from primary coal to granulitic coal, and then slightly increases from scaly coal to wrinkle coal, which is ascribed to the increase of OH-π transformed from other hydrogen bonds. Furthermore, −ΔHtotal and −ΔHav both decrease with the increasing deformation intensity even in scaly and wrinkle coals with slightly increasing total content of hydrogen bonds. While, the amount of ππ bonds increases with enhancement of coal deformation intensity (especially in brittle-ductile and ductile deformed coals), indicating that free molecules liberated by disruption of hydrogen bonds and ππ bonds are rearranged into a more stable, stacked and ordered configuration accompanied by the formation of new noncovalent bonds.

Carbon Sorbent Based on Special Fine Coke for the Extraction of Gold

The production of carbon sorbents based on special fine coke using a combination of steam and gas activation (by gas after the carbonization of Shubarkol coal with carbon dioxide and superheated water vapor) and chemical activation (by sodium hydroxide) was studied. Their textural and sorption properties were characterized. The necessity of separating the carbon and mineral parts of the special fine coke by elutriation in water was shown. The high adsorption capacity of the samples for gold ions was established (the recovery was 99.4–99.9%). The method for the production of a sorbent based on special fine coke in order to extract gold from cyanide solutions and the optimal conditions for its adsorption were recommended.

Nanoporous nickel oxide catalyst with uniform Ni dispersion for enhanced hydrogen production from organic waste

In this report, we propose magnetically separable porous nickel oxide nanostructure with uniform Ni distribution having the large surface area and atomically dispersed Si sites for enhanced hydrogen production from organic waste. The catalyst showed ten times higher production rate from volatiles during carbonization of organic waste and coal than that in the absence of the catalyst. The reduced Ni/NiO catalyst yielded two times higher hydrogen production compared to the traditional Ni/Al2O3 catalyst. The highest yield of hydrogen over reduced Ni/NiO was 32 g/kgfeed at 600 °C in fixed bed reactor via pyrolysis-reforming of bagasse. The Ni/NiO showed far more efficient recyclability compared to traditional Ni/Al2O3. The economic aspect of the Ni/NiO catalyst was compared with the Ni/Al2O3 catalyst based on H2 yield. TGA and TPO analysis confirmed the presence of amorphous coke.

A study on the chemical state of carbon present in fine ash from gasification

AbstractTaking feed coal as a reference, the chemical states, content changes, microstructure, distribution, and graphitizable extent of carbon present in gasification fine ash were investigated in detail. The results show that the fine ash includes a significant amount of unreacted carbon. The C1s spectrum is composed of four components in which the contents of C–C and C–H decrease dramatically and graphitized carbon (39.1%) presents. The elemental carbon primarily distributes on the layer structure, whereas elemental silicon and aluminum are mainly found on spherical particles embedded in the layer structure. After gasification, carbon atoms in gasification fine ash are arranged in an orderly manner, and the extent of graphitization of carbon increases, which indicates that carbon in feed coal may be partly graphitized and deposited in fine ash during gasification process.

Management and Treatment of the Clean-up Water from the Scrubber of a Coal and Biomass Gasification Plant: an Industrial Case Study

This work presents an industrial case-study on the possible application of an on-line treatment of the clean-up waters deriving from a wet scrubber used for the removal of pollutants from the syngas produced by a pilot plant used for test coal and biomass gasification. The wastewater is generated in a pilot-scale plant located in the south west of Sardinia and owned by ENEA and Sotacarbo. The plant platform includes a 5 MWth gasifier equipped with a wet scrubber for syngas clean up in co-current flow conditions and a flare. The plant is used for experimental campaigns with different feedstocks, mainly constituted by mixtures of coal and wood.The wastewater contains suspended and dissolved solids, which must be removed for a possible reuse of the clean-up water in a closed loop with low make-up. Moreover, the high content of pollutants reduces the effectiveness of the cleaning process and may lead to fouling of surfaces and blocking of the recirculation pumps. Adsorption with carbon-based sorbents has been tested to remove dissolved solids from water.Commercial activated carbon and different samples of coal were used to obtain sorption isotherms and breakthrough curves at lab scale. Based on the experimental results, a pilot-scale column has been designed and installed in a side stream of the clean-up system. The column was equipped with different carbon samples and tested during several gasification campaigns. The samples of coal do not show enough sorption capacity for a full-plant application, while good results were obtained when activated carbon was used as sorbent. Results show that the proposed approach can be used at full-scale, minimizing the use of external water sources for the gas cleaning system.

Energy saving and emission reduction of fossil energy based on low carbon economy and its consumption structure optimization

Abstract Energy saving and emission reduction have been not only a slogan but also a policy in this modern society where the phenomenon of greenhouse is exacerbated. In this study, calculation method of carbon emission and integrated parallel acquisition technique (IPAT) scenario prediction model were combined to predict the changes of total carbon emissions, energy structure distribution, and carbon emission intensity under three measures of energy saving and emission reduction in the next ten years in Shandong, China. The results showed that the total carbon emission increased year by year, and the coal ratio and carbon emission intensity decreased under the natural scenario; the total carbon emission in the weakly constrained scenario would increase annually until 2029, the amplitude was smaller than that of the natural scenario, while the coal ratio and carbon emission intensity would decrease, and the amplitude was larger than that of the natural scenario. Under the strongly constrained scenario, the total carbon emission would increase annually before 2025, and the amplitude was smaller than the weakly constrained scenario, while the coal ratio and carbon emission intensity would decrease, and the amplitude was larger than the weakly constrained scenario.

Relevance between various phenomena during coking coal carbonization. Part 2: Phenomenon occurring in the plastic layer formed during carbonization of a coking coal

The characteristics and carbonization behavior of a coking coal during the formation of a plastic layer was analyzed by using a thermogravimetry–plastometer–swelling pressure apparatus. The characteristics of the plastic layer were identified by using a penetrometer. The structural transitions across the plastic layer were investigated by scanning electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and X-ray diffractometry. Various carbonization behaviors are believed to be interrelated and depend significantly on the evolution of the plastic layer. The plastic layer can be divided into four structural zones with different penetrometer-resistance (PR) characteristics, namely, the increasing, decreasing, constant, and re-rising PR zones. The four structural zones of the plastic layer present a physical morphology of softening-fusion, melt-bubbling, foamlike, and a compression pore structure, respectively. At the PR constant zone, it appears that larger amounts of condensed aromatic rings developed because of an accumulation of tar and volatile precursors. In the PR re-rising zone, it appears that a rearrangement of aromatics occurred because of the enhanced conversion of ring systems and condensation. These findings may have an important role in revealing the coking mechanism of coal through the plastic layer and can provide guidance to evaluate the coking performance of coal.

A combined numerical and experimental approach to study the carbonization of low-rank coal ellipsoidal briquettes

This paper reports a combined numerical and experimental approach to study the coal carbonization process. It is applied to low rank coal ellipsoidal briquettes carbonization in a pilot-scale coke oven for demonstration. The integrated mathematical model integrates a DEM model to simulate the packing process of ellipsoidal briquettes in the oven and a CFD model to simulate the flow and thermochemical behaviours related to the carbonization process. The model is validated against the experimental measurements in the pilot-scale coke oven. The comprehensive in-furnace phenomena in the carbonization process are simulated, in terms of flow, temperature, gas composition, and carbonization characteristics. The simulation results indicate that it is necessary to include the briquettes packing structure evolution in the carbonization modelling for reliably describing the in-furnace phenomena. Then the effects of some briquette packing parameters, including briquette dropping height and vertical vibration, on the evolutions of packing structure and carbonization behaviour are studied. It is indicated that the dense packing structure resulting from higher dropping height and one-dimensional vertical vibration before the carbonization can improve the heat and mass transfers between the gas and bed, and thus can improve the carbonization efficiency. The computational cost of this approach as well as its future application are discussed. This model provides a cost-effective tool for understanding and optimizing the carbonization process of non-spherical low rank coal briquettes.

Development of Smelting Technology of Complex Ferroalloy with the Use of High-ash Coals

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Coal production and consumption analysis, and forecasting of related carbon emission: evidence from China

Carbon dioxide (CO2) formed during coal combustion is responsible for over half of the increase in the greenhouse effect, globally. It is crucial to conduct a comprehensive analysis and accurate prediction for coal production and consumption to optimize coal utilization and control emissions. However, several unstable factors inhibit the accurate forecasting of coal. Therefore, taking into account both effect and efficiency of prediction, the Hubbert model is applied in this study to forecast China’s peak coal production, peak year, and future production. Additionally, a combined model, with weights determined by a flower pollination algorithm and no-negative-constraint theory, is proposed to forecast coal consumption, which is superior to that of all individual models. Subsequently, accounting for the vital effect of CO2 from coal combustion on economic issues, correlation analysis and an environmental Kuznets curve (EKC) are applied to quantitatively examine the relationship among coal consumption, economic development, and carbon emissions. The results of this estimation suggest that, compared to the US, China’s economic development relies more on coal consumption; however, the EKC indicates that China has still not reached the ‘inflection point’. Accordingly, it is essential for policymakers to balance the relationship among coal utilization, economic development, and the environment.

Energy efficient technology of hot metal smelting at PAO NLMK

Decrease of energy expenditure for hot metal smelting is an actual task in blast furnace technology perfection. Under conditions of PAO NLMK regimes with maximum forcing of the BF process at the expense of pressure increase under furnace mouth and coke hot strength increase were chosen as one of priority ways to increase the BF operation energy efficiency. Data on blast furnaces productivity, specific coke rate, quantity of blow-in oxygen and fuel at different gas pressure levels under the furnace mouth quoted. A dependence between pulverized coal rate and total carbon consumption determined. It was shown, that application in PAO NLMK blast furnaces of coke having hot strength of 60–65% at maximum possible pressure under the furnace mouth and application of pulverized-coal fuel enabled in the period from 2012 through 2018 to decrease the coke rate by more than 100 kg. Also the total carbon consumption decreased by more than 30 kg per hot metal ton and to increase smelting products chemical composition stability.

A comparative model combining carbon atomic and molecular emissions based on partial least squares and support vector regression correction for carbon analysis in coal using LIBS

This paper proposed an innovation model combining carbon atomic and molecular emissions based on support vector regression correction for quantitative analysis of carbon in coal using LIBS.

DETERMINATION OF SULPHUR AND ASH CONTENTS IN THE COAL BY X-RAY FLUORESCENCE METHOD

Ponte Academic JournalMar 2019, Volume 75, Issue 3 DETERMINATION OF SULPHUR AND ASH CONTENTS IN THE COAL BY X-RAY FLUORESCENCE METHODAuthor(s): Baimolda D. ,Cechak T., Yerzhenbek B, Tlebaev K.B.J. Ponte - Mar 2019 - Volume 75 - Issue 3 doi: 10.21506/j.ponte.2019.3.8 Abstract:Coal is a very heterogeneous solid originating mainly from plant material. Coal is a major source of energy and its quality also depends on its elemental composition. Some elements present in coal can be environmentally hazardous when the coal is burned. In recent years, in the countries using a coal as the main source of energy the issue in the field of environment and ecology has become much stronger than in previous years. The international community began to demand tough measures in the field of non-proliferation of air pollution from the combustion of coal carbon dioxide and other toxic gases in the air. In this case, along with the determination of physical and chemical properties of coal and coal ash, there are quickly need to identify some hazardous elements as sulphur, titan and ash that is harmful to the environment. To fulfill such demands and needs recent years have seen rapid developments and applications of x-ray fluorescence (XRF) techniques in the coal industry. This study concerns sulphur and ash contents of coal samples from Mongolia and Czech Republic by using XRF, which offers several unique advantages over other analytical methods. Download full text:Check if you have access through your login credentials or your institution Username Password

Bridging the gap using energy services: Demonstrating a novel framework for soft linking top-down and bottom-up models

Giving policy advice related to climate mitigation requires insights that take both sectoral and technology effects (and their interactions) into account. This paper develops a novel soft-linking method for bridging the gap between sectoral top-down and technology rich bottom-up models. A unique feature of the approach is the explicit modelling of energy service demand in the top-down model, which creates a direct correspondence to the energy service production in the bottom-up model. This correspondence allows us, unlike previous work, to capture the macroeconomic impact of energy system investment flows. The paper illustrates the full-scale application of the method in the Danish IntERACT model, considering the unilateral introduction of coal carbon capture and storage in the Danish concrete sector. The policy leads to a reduction in the Danish concrete production, and in turn, a carbon leakage effect of 88%. Results also underscores the importance of accounting for the macroeconomic impact of energy system investment flows, as this is the source of approximately half of the policy-induced reduction in macroeconomic activity.

Structure of Carbon Sorbents Produced from Coal

Samples of coal and sorbents derived from coal are investigated by Raman spectroscopy. The results show that a three-dimensionally ordered carbon structure is obtained after carbonization of the initial coal. The sorbents are morphologically similar, regardless of the method of synthesis employed. The degree of graphitization is 12.9 ± 2%.

Influence of coke structure on coke quality using image analysis method

The quality of coke affects the performance of the blast furnace, factors affecting coke quality include coal properties, coal charge granulometry and carbonization conditions. The coke properties include the size analysis, cold strength (Micum Indices-M40, M10) and hot strength (Coke Reactivity Index-CRI, Coke Strength after Reaction-CSR) properties and structural properties such as coke structure and texture. Structural properties comprise the porosity, pore-cell wall thickness and pore sizes, while textures consist of the carbon forms in the coke. In present work, advanced method such as image analysis method was used to interpret coke microstructure. Conventional methods such as determination of coke porosity by measurement of real and apparent density and mercury porosimetry have a number of limitations. Coke size, magnification, number of image frames captured, process of pellet preparations and coke properties such as M40, M10, CRI and CSR (low, medium and high values) were taken as variables for experimental purposes. The coke structure parameters such as porosity, length, perimeter, breadth, roundness, pore-wall thickness and pore size distribution of the pores were determined by image analysis method. This method provided average porosity in addition to pore-wall thickness and pore-size distribution. The pore wall thickness measurement by image analysis method provided significant correlations with M40, CRI and CSR values. This explained the usability of image analysis for coke structure measurement.