A dimensionless factor characterizing the ignition of pulverized coal flow: Analytical model, experimental verification, and application

Abstract

SUMMARYAn analytical model describing the ignition process of pulverized coal is proposed, and a dimensionless condition number (N com ) is obtained to describe the comprehensive effect of factors governing the ignition of pulverized coal flow, such as the initial temperature of flow, the sectional heat load of the furnace, and the flux of primary air, secondary air and recirculation flue gas. An optimized concentration of pulverized coal flow is derived explicitly, upon which the earliest ignition of pulverized coal flow is possible. The model is verified in a hot furnace experiment, where it is shown that the derived criterion (N com ) can be used for different kinds of coal and different types of burner. For given coal and sectional heat load of furnace, when the value of N com increases, the condition of ignition is improved and both unburned carbon and NO x emission are reduced. The employment of N com in the optimization of burner operating conditions is demonstrated through two applications. In practice, the criterion N com can be used to guide the selection of the concentration and type of pulverized coal, as well as the choice of burner and desired aerodynamic field, so as to achieve an optimized performance.

Influence of Different Outer Secondary Air Vane Angles on Flow and Combustion Characteristics and NOxEmissions of a New Swirl Coal Burner

“…Costa et al measured local mean gas species concentrations (O 2 , CO, CO 2 , and NO x ), gas temperatures, and char burnout at several ports in a 300 MW e , front-wall-fired, pulverized-coal utility boiler. − Vikhansky et al measured heat fluxes in a 550 MW e , opposite-wall-fired, pulverized-coal utility boiler . Experiments have been performed in pulverized-coal, tangentially fired, down-fired, and wall-fired boilers, − but few detailed measurements have been taken in the burner region.…”