Calcium oxide sorbents injected in a slagging combustor react with the sulfur released during coal combustion to form sulfur bearing particles, some of which are deposited on the liquid slag layer on the combustor wall. Since the solubility of sulfur in liquid slag is low, the slag must be drained from the combustor to limit sulfur re-evolution into the gas phase. The objective of this 24 month project is to perform a series of 16 one day tests to determine the factors that control the

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... of the sulfur in the slag that is drained from the combustor. The last of the 16 tests planned for this project was completed in the present reporting period. This was the first test in this project that validated one of the primary hypothesis of this project, namely to retain substantial quantities of sulfur in slag requires high slag mass flow rate. Previous attempts to achieve high sulfur retention with artificial slag met limited success. In this, the 16th test, a high, 37%, ash Indian coal was injected into Coal Tech's 20 MMBtu/hr air cooled, slagging combustor with gypsum, CaSO 4 (2H 2 O). The slag analysis showed that 20% of the sulfur in the gypsum remained in the slag. This is double the highest sulfur concentration in slag measured in numerous test operationn with this combustor. While the test results to date have met the objectives of this project, further high slag mass flow rate tests are planned with the Indian coal to optimize sulfur retention in slag.