Development of a CFD-Based Coal Pipe Design Tool

In a coal-fired power plant, pulverized coal, using air as a transport medium, is pneumatically transported toward different burner nozzles by splitting the large pipe into small pipes through bifurcators or trifurcators. The combustion efficiency of the burner is dependent on matching the air and coal in these pipes. Increasingly tight emission standards also make the balance of air and coal a very critical factor for the success of the power plant. Coal roping occurs when the gas-solid flow passes through a curved pipe. The momentum of the particles carries them to the outside of the wall, concentrating in a small region. Therefore, the particle concentration in this small region is much higher than the other part of the pipe cross-section. Coal roping upstream of a coal distributor (bifurcator) can create a significant imbalance in coal loading in the split between the two branches. This can significantly impact plant performance and increase NOx production. Previous research [2] has shown that coal rope characteristics depend on many parameters; the geometry (i.e., elbow radius of curvature-to-pipe diameter ratio, pipe orientation, orifice opening, and the locations of orifices) of the coal pipe, which is determined at the design stage, will strongly affect the coal distribution in the outlet of coal pipes. This characteristic of coal roping indicates that optimizing the pipe geometry may be helpful in getting a more uniform coal distribution at the pipe’s outlet cross-section and minimizing the problems caused by imbalance between burners. In this paper, we present the CFD-based coal pipeline design tool to achieve the evenly distributed coal particle distribution across the pipe cross-section.