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Journal ArticleDOI: 10.1080/19392699.2018.1461624

Improved Slurryability and Rheological Characteristics of High Ash Indian Coal by Hydrothermal Treatment

04 Mar 2021-International Journal of Coal Preparation and Utilization (Taylor & Francis)-Vol. 41, Iss: 3, pp 203-215
Abstract: The crushed and sieved high ash coal samples are treated hydrothermally in a 15 l (liters) lab scale autoclave at a temperature of 394 K and residence times of 30, 45, 75 and 120 minutes. The hydro...

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Topics: Autoclave (61%), Coal (53%)

6 results found

Journal ArticleDOI: 10.1080/19392699.2019.1636787
Abstract: An experimental analysis is done for understanding the effect of various parameters like shear rate, solid concentration, and particle size on rheological behavior of bottom ash slurry. The coarser...

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Topics: Bottom ash (58%), Shear rate (57%), Slurry (56%) ... read more

5 Citations

Journal ArticleDOI: 10.1016/J.IJMECSCI.2020.105909
Abstract: In a slurry pipeline, the diverging sections are an important pipe fitting and also a cause of major pressure loss and sometimes flow separation. To address this potential issue, the complex solid-liquid flow of coal water slurry through conical diverging sections is simulated using the computational fluid dynamics approach. Nine different geometries of the diverging sections are analyzed in the present study. The length of the diverging section is the key variable in the geometric variations and ranges from 0.05 m to 0.6 m. The influx velocity at the entrance of all the diverging sections is varied in the range of 0.5 m/s to 5 m/s. The mass concentration of the solids dispersed inside the liquid phase is varied from 10 to 60%. The results generated by the computational fluid dynamics tool are in good agreement with the experimental data. The design of the diverging section is evaluated based on results obtained for three characterization parameters viz. pressure recovery coefficient, head-loss across the diverging section and volumetric efficiency. The 0.3 m long diverging section is found to be the optimum design for best pressure recovery, maximum volumetric efficiency and lowest head-loss.

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Topics: Pressure drop (54%), Flow separation (51%)

4 Citations

Journal ArticleDOI: 10.1080/19392699.2020.1760854
Abstract: The high-rank coal reserves are limited and getting depleted at an escalating rate to meet the demands of growing population. This concern has compelled the scientific community to use the young hi...

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Topics: Coal (55%), Population (55%)

1 Citations

Open accessJournal ArticleDOI: 10.1051/E3SCONF/202125811002
01 Feb 2021-
Abstract: New methods of processing bituminous and brown coal in synthetic and coal-water fuel production are now gaining relevance. On the one hand, this is dictated by the pragmatic need to reduce the dependence of industrial energy consumers on the prices and quality of hydrocarbon raw materials, especially in the context of the constant exacerbation of market restrictions associated with the pandemic and sanctions, on the other hand, there is an urgent need for environmentally friendly methods of using synthetic and coal-water fuels. The article discusses the currently used technologies for the production of synthetic and coal-water fuels. The authors identify its main disadvantages and limitations and propose a schematic diagram of a technological line for coal-water fuel production with a linear layout. It allows obtaining fuel with good fluidity and higher stability, high-calorie content, and low ash content with less energy consumption.

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Topics: Coal water (57%), Sustainability (54%)


22 results found

Journal ArticleDOI: 10.1016/J.ENCONMAN.2011.11.016
Yujie Yu1, Jianzhong Liu1, Ruikun Wang1, Junhu Zhou1  +1 moreInstitutions (1)
Abstract: Two brown coals from China were dewatered under hydrothermal dewatering (HTD) conditions at 250–320 °C for 1 h in a 2 L autoclave. The hydrothermally dewatered products were used to prepare coal water slurry (CWS) with a lower viscosity than brown raw coal slurry. Moreover, the coal rank and heat value of the brown coal increased as the inherent moisture and oxygen content decreased during the HTD process. The maximum solid concentration of CWS prepared from XiMeng coal increased from 45.7% to 59.3%, whereas that of CWS prepared from BaoTou coal increased from 53.7% to 62.1%, after being dewatered at 320 °C. The improvement in the slurryability of brown coal significantly depended on the final temperature of the HTD process, the mechanism of which can be explained by the chemical analysis of oxygen functional groups, zeta potential, and the contact angle of the surface between coal and water. The oxygen functional groups, the oxygen/carbon ratio and hydrogen/carbon ratio in brown coal decreased, indicating that the coal rank was upgraded during the HTD process. As a result, both the point of zero charge and the contact angle increased, implying that the HTD products were highly hydrophobic.

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Topics: Coal slurry (64%), Coal water (62%), Coal (61%)

118 Citations

Journal ArticleDOI: 10.1016/J.POWTEC.2015.03.003
Wencheng Xia1, Guangyuan Xie1, Yaoli Peng1Institutions (1)
01 Jun 2015-Powder Technology
Abstract: Coal beneficiation is one of the most effective methods for removing minerals (such as gangues and pyrite) and pollutants (such as sulfur) before the burning of coal. In general, the beneficiation process of low rank coals is more difficult to achieve than that of bituminous and/or anthracite coals. However, about 50% of the world's total coal deposits are low rank coals. It is urgently required to develop effective beneficiation technologies for low rank coals. This review highlights recent advances in beneficiation technologies for low rank coals. Physical (gravity and magnetic separation), chemical (leaching), physico-chemical (flotation and oil agglomeration) and bio-beneficiation technologies are summarized in detail. Effective beneficiation technologies for low rank coals in the future are also suggested throughout this paper.

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Topics: Beneficiation (64%), Coal (50%)

112 Citations

Journal ArticleDOI: 10.1016/S0378-3820(03)00095-X
Abstract: Coal–water slurry (CWS) holds promise to offer a long-term alternative to fuel oil, and also it is being conceived as an attractive fuel for power generation industry in India. The essential requirements of the CWS technology, viz., the additive package, concentration of additives, particle size distribution (PSD) of coal, solids loading, methodology for CWS formulation and its rheological properties, have been discussed and reported here. The effect of the two newly developed anionic additives in the formulation of CWS has been studied. The basic parameters were established taking beneficiated Ledo coal samples with 9.7% ash content. Ball milling of the coal samples in a wet grinding process could produce particle size distributions most suited for highly loaded CWS. Coal loadings to the extent of 70% in the CWS have been achieved using a concentration of 0.8 wt.% (on coal charge) of the naphthalene-based additive referred to as ‘P’. Using 0.9 wt.% of the naphthalene-toluene-based additive denoted as ‘R’, a coal loading of 69% has been achieved. The viscosities of the slurries were found to be below 1000 mPa s. The shelf lives of slurries were found to be 22 and 20 days with the use of additives P and R, respectively, in the CWS formulation. The two additives functioned well in CWS formulation with Sirka coal having relatively higher ash content (14.4%). Using the specified concentration of the additives P and R, the solid loadings of 67% and 65%, respectively, could be obtained under the established parameters. The lower values of solids loading from Sirka coal than that from Ledo coal in CWS formulation may be attributed to the higher percentages of oxygen-containing functional groups (OOH and OCOOH), ash content and higher O/C ratio of Sirka coal.

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Topics: Coal water (62%), Coal (59%), Slurry (50%)

81 Citations

Journal ArticleDOI: 10.1021/EF7005244
04 Jun 2008-Energy & Fuels
Abstract: To improve the coal water slurry (CWS) property made from Chinese Shenhua coal with high inherent moisture and oxygen contents, microwave irradiation and thermal heat were employed to modify the coal physicochemical property. Microwave irradiation reduces the inherent moisture and reforms the oxygenic function groups, while it decreases the total specific surface area. Thermal heat markedly decreases the inherent moisture, volatile, and oxygen contents, while it dramatically increases the total specific surface area. Therefore, microwave irradiation gives a higher CWS concentration and a better rheological behavior than thermal heat, while it remarkably reduces the operation time and energy consumption. The maximum CWS concentration given by microwave irradiation at 420 W for 60 s is 62.14%, which is not only higher than that of 60.41% given by thermal heat at 450 °C for 0.5 h but also higher than the initial 58.23%. Meanwhile, the minimum shear stress given by microwave irradiation is 36.4 Pa at the shea...

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Topics: Coal water (58%), Coal (54%), Thermal energy (51%) ... read more

72 Citations

Journal ArticleDOI: 10.1016/J.FUEL.2016.04.027
Junjie Liao1, Yi Fei2, Marc Marshall2, Alan L. Chaffee2  +1 moreInstitutions (2)
15 Sep 2016-Fuel
Abstract: A lignite from Shengli mine in Chinese Inner Mongolia was upgraded by hydrothermal dewatering (HTD). The effects of the HTD process on the solid product yield and the removal rate of elements, organics and inorganics in this coal were determined. The moisture re-adsorption capacities and spontaneous combustion behaviors of coal products from the HTD process were studied, using the saturated salt solution and wire basket reactor methods respectively. FT-IR, XRD, CO2 adsorption, mercury intrusion porosimetry (MIP) and helium pycnometry were carried out to characterize the physicochemical properties of samples. The results show that during the HTD process, organic matter was removed due to the loss of CH3, CH2, and O-containing functional groups, while the inorganic matter was mainly removed in the forms of Ca- and Fe-containing minerals. The amounts of both organic and inorganic matter removed increased with temperature. The equilibrium moisture contents of the hydrothermally dewatered coals at 30 °C in the relative humidity range 11–97% were lower than those of the raw coal. They decreased as the HTD temperature rose, probably due to the increase in the loss of hydrophilic O-containing functional groups and decrease in surface area with the increasing of HTD temperature. Moreover, the critical ignition temperature (Tcr) of all the hydrothermally dewatered coals, as measured by wire basket spontaneous combustion experiments, was lower than that of raw coal.

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71 Citations