Experimental study on the influence of fuel-rich and fuel-lean coal/airflow ratio on aerodynamic characteristics of a 300MWe foster wheeler down-fired boiler.

To address the problem of late ignition and poor burnout of Foster-Wheeler down-fired boilers, this study proposed a new combustion technology, which combines adding on arch secondary air and alternately arranging the fuel-lean coal/airflow (FLCA) and fuel-rich coal/airflow (FRCA). The coal particle trajectories of FLCA and FRCA and overall aerodynamic characteristics in the furnace were studied at FRCA and FLCA ratio (RRL) of 5:5, 7:3, and 9:1. The results showed that even at a low FRCA ratio, the new combustion technology could still effectively ensure the penetration depth of pulverised coal/airflow. At different RRL values, the main airflow from the arch appeared in the near-wall area and could penetrate downwards into the cold ash hopper area. With an increase in the value of RRL, the deflection degree of FLCA towards the furnace wall increased, while that of FRCA decreased. At RRL of 7:3, both the penetration depth and deflection degree of FRCA and FLCA were at a high level, which was conductive to promoting the burnout and recommended in practical applications. [ABSTRACT FROM AUTHOR]