Experimental investigation of combustion and ash deposition characteristics of coal-NH3 cofiring in a 200 kW furnace

Abstract

The coal-NH3 co-firing experiment was conducted in a 200 kW one-dimensional furnace to study the flue gas emission characteristics and ash deposition characteristics under different ammonia co-firing ratios. As ammonia is a carbon-free fuel, CO2 shows a decreasing trend, while H2O gradually increases with the increase of ammonia co-firing ratio. With the increase of ammonia co-firing ratio, the proportion of unburned carbon increases slightly. Compared with the ammonia in flue gas, the ammonia attached to ash is the main reason for ammonia slip. The total ammonia slip rate of the three co-firing ratio conditions is 0.26% (5% NH3), 0.29% (10% NH3) and 0.67% (20% NH3), respectively. The NOx emission reaches the maximum of 349.05 ppm when the ammonia co-firing ratio is 10%, then decreases as the ratio increase to 20%. Ammonia co-firing does not change the composition of ash particles but has a certain deterioration of heat transfer of heat exchange surface in high temperature zone of furnace. This is related to the adhesion of ammonia on the surface of fly ash and the reduction of the size of fly ash.