Testing of Limestone Samples from the TVA (Tennessee Valley Authority) Region as Sulfur Dioxide Sorbents in Atmospheric Fluidized Bed Combustors

摘要

This project summary presents the results from a two-year study of 37 limestone and dolomite samples for application as bed materials in Atmospheric Fluidized Bed Combustion (AFBC). The Tennessee Valley Authority (TVA) supplied the limestone samples for this study. The materials represent a cursory survey of what is currently available from quarries in the region surveyed by the TVA. The following nine techniques were used to characterize the limestone samples: (1) petrographic analysis (2) chemical analysis, (3) thermogravimetric analysis (TGA), (4) attrition test, (5) Brunauer, Emmett, and Teller (BET) surface area, (6) mercury porosimetry, (7) density measurements, (8) transmission electron microscopy (TEM) and (9) scanning electron microscopy (SEM). In addition, both the sensitivity of stone sulfation capacity to temperature changes and the possibility of using hydration to enhance limestone sulfur capture capability were examined. TVA-804, 806, 819, and 829 are the limestones the authors recommend for AFBCs. Their results indicate that thermogravimetric analysis (TGA) is the simplest means of determining the relative sulfur capture capacity of the limestones. The attrition/sulfation test is a good indicator of sulfur capture, attrition, and carry-over properties of the bed material. TEM analysis of calcined stones is useful in ranking stones in order of sulfur capture capacity; however, like the TGA and attrition test data, TEM analysis cannot provide quantitative results.