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Force-System Resultants and Equilibrium
Published in Richard C. Dorf, The Engineering Handbook, 2018
The ultimate coal analysis is a laboratory analysis that lists the mass fraction of carbon (C), hydrogen H2, oxygen O2, sulfur (S) and nitrogen N2 in the coal along with the higher heating value (HHV) It also lists the moisture, M, and ash, A. This analysis is required to determine the combustion-air requirements for a given combustion system and the size of the draft system for the furnace.
A novel dry beneficiation process for coal
Published in International Journal of Coal Preparation and Utilization, 2022
Liang Dong, Ziming Wang, Enhui Zhou, Xuan Wang, Gongmin Li, Xuchen Fan, Bo Zhang, Chenlong Duan, Zengqiang Chen, Zhenfu Luo, Haishen Jiang, Yuemin Zhao
According to the raw coal analysis in Section 3.1, the combustible composition of the 100–50 mm raw coal was mainly distributed in the low-density component which is lower than 1.58 g/cm3. When the theoretical separation density was 1.58 g/cm3, the content of the ±0.1 g/cm3 of 100–50 mm raw coal was 8%, washability was easy to select, the theoretical clean coal yield was 90%, and the ash content was 8%. Therefore, the optimal separation density was set at 1.58 g/cm3. According to the evolution law of bed density with gas velocity, presented in Fig. 8, the operating gas velocity was set as 0.11 m/s, 0.12 m/s, and 0.13 m/s for coal separation, and the bed density was 1.56–1.61 g/cm3 at this time. The separation results are presented in Table 5.
An investigation of performance characteristics and energetic efficiency of vertical roller coal mill
Published in International Journal of Coal Preparation and Utilization, 2021
This section reveals the variation of mill outlet temperature on the key parameters of coal content. Humidity content is a vital criterion in coal analysis. It is necessary for determining the net calorific value of a fuel. Moisture absorbs heat, so high-moisture content in coal reduces the boiler performances when coal is combusted. Moisture content strongly impacts combustion efficiency (Huang, Ng, and Giroux 2020: Potter and Keogh 1981). Therefore, coal is heated inside the mill with the primary air stream, and thus moisture level is decreased at mill outlet. Bituminous coal is known as a high-rank coal type that includes lower moisture. According to Figure 7 moisture content drops down slightly as the mill outlet temperature increase. PA air heats coal powder and evaporates moisture within the coal therefore dried coal is obtained. Also, the moisture level is reduced to below more than 50% of the input coal moisture level for each type. CMC includes less moisture so, coal quality becomes better at the mill outlet at the same output temperature.
Mineralogical, chemical, and petrographic properties of selected South African power stations’ feed coals and their corresponding density separated fractions using float-sink and reflux classification methods
Published in International Journal of Coal Preparation and Utilization, 2019
R. Rautenbach, C. A. Strydom, J. R. Bunt, R. H. Matjie, Q. P. Campbell, C. Van Alphen
The modal proportion of minerals in the samples can be observed in Fig. 7 for; i) Feed coals, ii) Coal A, iii) Coal B and iv) Coal C. Similar trends are observed in the modal proportions for the feed coals B and C, while coal A feed exhibited a different modal proportion of minerals. Coal A was more enriched in vitrinite with less fusinite and reactive semi fusinite compared to coals B and C, while significantly less clay minerals were also observed in coal A. The modal proportion of minerals in the density fractions (ii to iv) are in accordance with the feed coal analysis. High proportions of clay minerals were observed in the sink fractions while the vitrinite reported to the float fraction as expected (Koekemoer 2010; Matjie et al. 2011, 2008).