Na/Ca catalyzation of Illinois coals for gasification. Final technical report, September 1, 1992--August 31, 1993

摘要

Gasification for power generation via IGCC processes is expected to become an important market for high sulfur Illinois Basin coals. Fluid-bed gasifiers have significant advantages over entrained flow processes. These advantages include ease of control, large turndown capacity, high thermal efficiency, and moderate oxygen and steam requirements. Three of the most pressing technical problems in fluid-bed gasification of Illinois coals are the caking tendency, high sulfur content, and low carbon conversion and consequent large char recycle required in most systems. This program explores the use of gasification catalysts to attack these three problems. The catalysts are sodium/calcium mixtures. Another advantage of using catalysts is that gasification temperature might be lowered, leading to less expensive materials of construction and a reduction in alkali vaporization. The results of this study indicate that these catalysts can reduce or eliminate the caking of Illinois coals. Loadings below 1 weight % were effective if the catalyst was added by impregnation at low pH (below about 5). An Na/Ca molar ratio of greater than 1 also leads to lower catalyst requirement.