Application of Test Methods for Use in Limestone Selection for Wet Flue Gas Desulfurization

摘要

Industry standard test methods for determination of limestone composition and reactivity are crucial for ensuring adequate performance of limestone force-oxidized (LSFO) wet flue gas desulfurization (WFGD) absorber units. To determine if a limestone will provide design level performance and/or meet contract specifications, it is tested with regard to composition and reactivity. Essential parameters for the composition are the fraction of CaCO_3, MgCO_3, and inerts. ASTM Method C1271 (XRF), a combination of ASTM Method C25, Section 22 for CO_2, ASTM Method C25, Section 17 for CaO, and ASTM Method C25, Section 18 for MgO or TGA, are widely accepted for such determination. Such procedures are commonly incorporated within contract guarantee language and unit performance test plans. In contrast, an industry standard procedure for limestone reactivity is presently unavailable, with different OEMs and many suppliers having their own tests. An ASTM Task group is presently addressing this need, drafting a test method for limestone reactivity that may become the industry standard. Herein is discussed usage of the ASTM test methods C1271 and C25 as well as TGA for limestone compositional analysis and a comparison of some methods presently available for limestone reactivity testing for use in WFGD.