An investigation of the evaporation behavior of bioliquid in the pores and its application to hybrid coal combining biomass with coal

Bae, Jong‐Soo; Lee, Dong‐Wook; Lee, Young‐Joo; Park, Se-Joon; Park, Ju-Hyoung; Kim, Joeng-Geun; Han, Choon; Choi, Young-Chan

doi:10.1016/j.applthermaleng.2015.03.025

Cited by 13 publications

(6 citation statements)

References 18 publications

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“…However, the combustion pattern of the hybrid coals (BC) was changed from a multistage combustion pattern to a single combustion pattern through the addition of glycerol and the torrefaction process (changes the chemical properties of the volatile matter). In addition, like the previously reported HCK ,− ,, we observed homogeneous combustion behavior (so-called two-in-one fuel) of the glycerol/carbonized hybrid coals regardless of glycerol content from 10 to 30%, from which we deduce that the carbons from the glycerol with sulfuric acid during torrefaction becomes unified with the carbons inside raw coals; thus, they fill the inherent pores of raw coals. In fact, the infiltration and carbonization mechanism of glycerol inside carbonic pores has been previously reported. − Direct evidence to support this deduction was also obtained by a nitrogen sorption test; the results for the raw coal after drying (BC-D) and hybrid coals are summarized in Figure and Table .…”

Section: Results and Discussionsupporting

confidence: 89%

Preparation and Characterization of the Glycerol-Embedded Hybrid Coal

Park

Lee

et al. 2019

ACS Sustainable Chem. Eng.

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The molasses embedded hybrid coal (Hybrid Coal by Korea Institute of Energy Research; HCK) was previously proposed as an attractive alternative to low-rank coals that tend to show low calorific values and high CO2 emissions. HCK was synthesized by mixing molasses with a low-rank coal to enhance its heating value. Nevertheless, food ethics regarding molasses additives still have impeded its commercial acceptance. In this study, we propose a glycerol (nonfood)-based coal upgrading process to improve the combustion kinetics and heating value of hybrid coal in comparison to the previous HCK. The process involves drying at 105 °C followed by torrefaction process at 250 °C. During torrefaction, the glycerol additive starts to evaporate at about 180 °C and then is almost vaporized out to the coal surface. To avoid glycerol loss, we employ sulfuric acid as a torrefaction catalyst to suppress glycerol evaporation. In comparison to the molasses yield of 65% after torrefaction in the previous HCK synthesis process, glycerol-embedded torrefaction with sulfuric acid showed a 55% yield in mass. The glycerol-embedded hybrid coal shows a homogeneous combustion peak regardless of the mixing ratios, leading to a 35% reduction of unburned carbon emissions, which is one of the particular matter sources of combustion flue gas. Furthermore, the proposed synthesis process increases the net caloric value to 80% and lowers the water uptake to 84%, even without a higher SO2 emission, in comparison with raw coal.

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Section: Results and Discussionsupporting

confidence: 89%

Preparation and Characterization of the Glycerol-Embedded Hybrid Coal

Park

Lee

et al. 2019

ACS Sustainable Chem. Eng.

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“…A part of unreacted coal particles is carried away from the combustion chamber. 17 In papers, 21,22 glycerol is also considered a promising organic additive to fuel. In, 21 it was shown that glycerol in coal pores evaporates at a higher temperature.…”

Section: Introductionmentioning

confidence: 99%

“…17 In papers, 21,22 glycerol is also considered a promising organic additive to fuel. In, 21 it was shown that glycerol in coal pores evaporates at a higher temperature. These changes in the evaporation characteristics are positive because they reduce the explosiveness of CWF and improve the quality of fuel pulverization and, consequently, the efficiency of its combustion.…”

Section: Introductionmentioning

confidence: 99%

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Evidence of the illegitimacy of the additive approach to the determination of the thermophysical properties of coal‐water fuel with glycerol

et al. 2020

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For the fuel ignition, the thermal conductivity and heat capacity are the key properties that determine the pre-ignition behavior of the drop of the fuel. The classic monophase fuels, such as natural gas, liquid propellants, or solid onecomponent fuels, have been investigated for a long time; and their thermophysical properties are well known in most of the cases. Composite fuels, which have recently attracted the attention of the researchers, have complex contents. In many cases, composite fuel is a mixture of solid and liquid components in the form of a slurry. Coal-water fuel and its derivatives with different additives are examples of such type fuels. For those fuels, the thermophysical properties are usually unknown. Nowadays, researchers use simple additivity theory for the calculation of the thermophysical properties of complex fuels for the first approach. Authors of this research believe that the simple additivity approach is not correct and can lead to the wrong results in the case of the numerical research of the ignition and burning processes of such a fuel. In the present research, the thermophysical properties of coalwater fuel with glycerol additives were experimentally obtained. It was found that the coefficient of thermal conductivity increases with temperature and varies in the range of 0.45 to 0.53 W/(mÁK). The heat capacity of the fuel also increases with the temperature and varies from 4.7 to 5.5 kJ/kgÁK. The higher the glycerol content, the lower the thermal conductivity and heat capacity of the composite fuel in the investigated temperature range. The results confirm the failure of the approach of the additivity law usage. Neither, thermal conductivity coefficient or heat capacity of the coal-water fuel with the addition of up to 20% glycerol complies with the additivity law. Differences between real values of the thermophysical properties and calculated ones are more than 30% No colors needed for a print copy of the manuscript.

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“…Shezan et al [23] made a techno-economic analysis of a smart grid solar-wind-diesel system to support a small community in Brisbane (Australia), concluding on its economic and environmental feasibility. Concerning the hybridization of coal plants with biomass, Bae et al [24] analyzed the range of bioliquids that can be burned with coal, and Trop et al [25] considered the torrefaction of biomass and coal. Nevertheless, the most developed, examined alternative for coal hybridization is concentrated solar power that focuses radiation on small areas (receivers) through mirrors [26].…”

Section: Introductionmentioning

confidence: 99%

Exergy and Economic Evaluation of a Hybrid Power Plant Coupling Coal with Solar Energy

2019

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Hybrid power plants that couple conventional with renewable energy are promising alternatives to electricity generation with low greenhouse gas emissions. Such plants aim to improve the operational stability of renewable power plants, while at the same time reducing the fuel consumption of conventional fossil fuel power plants. Here, we propose and evaluate the thermodynamic and economic viability of a hybrid plant under different operating conditions, applying exergy and economic analyses. The hybrid plant combines a coal plant with a solar-tower field. The plant is also compared with a conventional coal-fired plant of similar capacity. The results show that the proposed hybrid plant can emit 4.6% less pollutants due to the addition of solar energy. Fuel consumption can also be decreased by the same amount. The exergy efficiency of the hybrid power plant is found to be 35.8%, 1.6 percentage points higher than the efficiency of the conventional coal plant, and the total capital investment needed to build and operate a plant is 8050.32 $/kW. This cost is higher than the necessary capital investment of 5979.69 $/kW to build and operate a coal-fired power plant, and it is mainly due to the higher purchased equipment cost. Finally, the levelized cost of electricity of the hybrid plant is found to be 0.19 $/kWh (using both solar and coal resources) and 0.12 $/kWh when the plant is fueled only with coal.

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An investigation of the evaporation behavior of bioliquid in the pores and its application to hybrid coal combining biomass with coal

Cited by 13 publications

References 18 publications

Preparation and Characterization of the Glycerol-Embedded Hybrid Coal

Preparation and Characterization of the Glycerol-Embedded Hybrid Coal

Evidence of the illegitimacy of the additive approach to the determination of the thermophysical properties of coal‐water fuel with glycerol

Exergy and Economic Evaluation of a Hybrid Power Plant Coupling Coal with Solar Energy

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