Measurements of Surface Combustion Rate of Single Coal Particles in Laminar Flow Furnace

Abstract

Study of The pulverised coal combustion in air was performed using a laminar flow furnace at gas temperatures between 800 and 1200° C, particle size between 44 and 359 μ m and oxygen level of 21 percent. The time sequential variation of the fractional burn-off, the particle size distribution and the particle density during the pulverized coal combustion were measured by using two different type coals. The curve of the fractional bum-off indicated that the combustion of the pulverized coal is a two-staged combustion — the rapid volatile matter combustion followed by the slow char combustion. However, it was observed that char combustion occured simultaneously in the volatile matter combustion region. From the measurements of the combustion rate based on the unit external surface area of the particle, the rate of large coal particle was higher than that of small ones under the same gas temperature within the range of particle size used in this experiment. The fact could be explained by the temperature difference between the particle surface and the surrounding gas