Journal of Flow Visualization and Image Processing

ISSN for PRINT: 1065-3090

For Online Access

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2006, Volume13

Issue 2

110 pages

DOI: 10.1615/JFlowVisImageProc.v13.i2

Issue price - $154.00

A. Aroussi
Mechanical Engineering, The University of Nottingham, Malaysia Campus Jalan Broga, Samenyih 43500, Selangor Darul Ehsan, Malaysia

Pulverized fuel (PF), and especially pulverized coal, is widely used as a source of energy for power generation in utility boilers. This stems from its wide distribution and low cost under present economic structures. At the same time there is increasing awareness of the adverse environmental impacts associated with its use. These include the high carbon-to-hydrogen ratio, resulting in high greenhouse gas emissions, and the pollutant emissions associated with impurities, including nitrogen and sulfur. While alternative sources of energy are being developed, it is clear that coal will form the dominant source of primary energy for the immediate future and will be a major source for many years. As a result it is necessary to continue to improve the effectiveness of its utilization.
Although pulverized coal has been both used and studied for more than a century, many details of the processes of supplying and burning it remain poorly understood. As a result there is considerable scope for refinement and optimization of the PF combustion.
The processes of conveying and burning PF are complex two-phase processes involving the particles and the conveying gas but also influenced by the substantial variations in the distribution of size, shape, and properties of the fuel particles. Further, they involve both turbulence and combustion, neither of which is fully understood even in gaseous flames. Particles in industrial PF flames are never distributed uniformly and the extent of the maldistribution depends upon the size of the particles. The combined effects of gravity and the complex interaction between particles and turbulence means that particles tend to concentrate locally, even within the pipes supplying the fuel to the burners, creating the effect known as "roping". This is the source of fuel distribution imbalance at power stations and is the topic of this paper, where the emphasis is on the pneumatic conveying of pulverized coal and the remedies being developed and applied to ensure better uniformity of pulverized fuel at pipe splits. This includes both vertical and horizontal bifurcation, trifur-cation, and quadrafurcation.

DOI: 10.1615/JFlowVisImageProc.v13.i2.50 Download article, 175-202 pages

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