Predicting the Impact of Furnace Ash Deposition on Furnace Temperature and NO_X and CO Emissions

摘要

Reaction Engineering International has developed a modeling tool which predicts the impact of ash slagging on furnace temperatures, NO_X, CO and carbon in ash in utility boilers. The overall approach is to combine a slagging sub-model with a comprehensive computational fluid dynamic (CFD) combustion model. The slagging sub-model predicts mineral matter transformations and performs deposit growth, sintering and properties calculations and updates the wall boundary conditions for the comprehensive CFD combustion simulation. This CFD-based slagging deposition model has been applied on PacifiCorp's Hunter Unit 3. The integrated slagging deposition model provided realistic results for conventional air-fired combustion that are in line with industrial experience. The model predicted 27% of the ash deposited in the radiant section of the furnace. After six hours of deposit build-up the predicted temperature increased by 100°F at the horizontal nose, the CO increased by 35% at the horizontal nose, the in-furnace NO_X concentration increased slightly while the emitted NO_X remained essentially unchanged and the carbon in fly ash content was reduced by almost 2.5 percentage points.