Abstract
Excessive coal moisture leads to a lower heating value and power plant efficiency, and increased transportation costs. Therefore, coal stockpile management and moisture control are particularly important in regions with heavy precipitation. This paper and Part 2 address factors influencing moisture retention and migration in coal stockpiles. Part 1 of this paper series simulates phenomena of runoff, infiltration, and drainage in a stockpile after a rainfall event. Part 2 reports the effect of coal particle size and climate conditions on the rate and depth of moisture evaporation process within a coal stockpile. To perform this study, two coal samples were collected from the Witbank mine in South Africa. The results of the present study showed that smaller interparticulate void spaces because of the compaction or fines particles (−0.5 mm fraction) inhibited infiltration, leading to increased runoff volume. An increase stockpile slope increased the amount of runoff due to coal–water contact time reduction. The ability of heavy rainfall to destroy near-surface structures (erosion) happened more readily at stockpiles with high slopes and high fine content. The fine content significantly influenced the dewatering efficiency of drainage. Coals with higher ash contents had stronger moisture retention ability than that of other coals even though coals with low ash contents had a high fine content. This was ascribed to the contribution of the clay minerals, such as kaolinite, in the high ash coal. The results of this paper can be used for the effective management of coal stockpiles to prevent excessive moisture in stockpiles for the best possible utilisation of coal in power plants.
Highlights
The relationship between coal stockpile runoff and infiltration depends on factors such as particle size distribution, rainfall intensity, weather conditions, clay mineral content, initial moisture content, and the degree of compaction of the stockpile bed [13,19]
The relationship between coal stockpile runoff and infiltration depends on factors suchMaterials as particle size distribution, rainfall intensity, weather conditions, clay mineral content,During initial moisture content, and thecoal degree of compaction the the stockpile bedregion
This study described and compared changes in coal moisture content f fall events within a stockpile
Summary
A key fuel, is still one of the most essential energy sources in the world, accounting for more than 70% of disposable energy consumption [1,2]. Factors influencing moisture control on stockpiles are mineral content, porosity, stockpile height and slope, particle size distribution, weather conditions, and compaction rate [8,13]. Since it is difficult to evaluate multiple factors when investigating water movement in coal stockpiles, most previous studies only focused on one or two factors It is still not clear how coal moisture content changes over time following different precipitation rates, and which the key parameters are that specify these changes. To overcome the various limitations found in the literature, this research paper analyses the behaviour of water within a simulated coal stockpile to better understand the mechanisms by which water is transported by focusing on the effects of particle size distribution, weather conditions, coal type, degree of compaction, and stockpile height. In Part 2, the effect of coal particle size and ambient conditions on the rate and depth of moisture evaporation within a stockpile is investigated
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