Aerosols from a Laboratory Pulverized Coal Combustor

Abstract

A laboratory study has been undertaken to characterize the aerosol produced during pulverized coal combustion. The emphasis in this work has been on the particulate matter present in the flue gases at the inlet to the gas cleaning equipment rather than that leaving the stack. Coal is burned at conditions which simulate the combustion region of coal-fired utility boilers. The combustion products then pass through a series of convective heat exchangers which cool them to normal flue gas temperature. Samples extracted from the cool (400-500°K) combustion products are analyzed for major gaseous products and aerosol properties. The size distribution of the particulate matter in the 0.01-5 µm size range is analyzed on line using an electrical mobility analyzer and an optical particle counter. Samples of particles having aerodynamic diameters between 0.05 and 4 µm are classified according to size using the Caltech low pressure cascade impactor. A number of analytical procedures have been used to determine the composition distribution in these particles. A discrete mode of particles is observed between 0.03 and 0.1 µm. The major components of these particles are volatile elements and soot. The composition of the fine particles varies substantially with combustor operating conditions.

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