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INVESTIGATION OF PRODUCT-LAYER DIFFUSIVITY FOR CAO SULFATION
Citation:
Borgwardt, R., K. Bruce, AND J. Blake. INVESTIGATION OF PRODUCT-LAYER DIFFUSIVITY FOR CAO SULFATION. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-87/279 (NTIS PB88185509), 1987.
Description:
The paper gives results of comparisons of the sulfation rates of CaO prepared from Ca(OH)2 and CaCO3, using six types of each precursor derived from the same natural limestones. The particles were small enough to eliminate all transport resistances except diffusion through the CaSO4 product layer. No significant difference between the reactivity of the two types of CaO was observed when compared at equal values of specific surface area (23 sq m/g), temperature (800C), and SO2 partial pressure (304 Pa). The apparent product-layer diffusivity at these conditions was 2.1 x 10 to the minus 8th power sq cm/sec. For an activation energy of 33 kcal/mol, the Arrhenius pre-exponential factor for diffusion is estimated to be 0.12 sq cm/sec. Sulfation rates increased with the 0.64 power of SO2 partial pressure. (Copyright (c) 1987 by the American Chemical Society.)