Measurements of the effect of rank on combustion rates of pulverized coal

The rates of reaction of pulverized coal chars have been measured for a range of eleven coals, high rank and low rank, swelling and nonswelling, using a luminar flow furnace technique described in an earlier paper [1] . The changes of size and density that occur during combustion have also been measured. The reaction rate of each of the coal chars is expressed in the form of a diffusional reaction rate coefficien and a surface reaction rate coefficient. The surface reaction rate coefficient is strongly dependent on coal type, increasing by a factor of about 8 from anthracite to low-rank coal at 1600°K. The surface reaction rate coefficient is the same for 5% and 10% oxygen and increases linearly with surface temperature in the range 1200–2000°K, the rate of increase depending on the coal.