Many utilities are installing wet flue gas desulfurization (FGD) systems to comply with tighter sulfur dioxide regulations. These installations will introduce many utility engineers and other technical personnel to a sometimes complex air pollution control technology. This paper outlines fundamental concepts of wet limestone FGD, particularly in the most common design, spray towers. Topics will include liquid-to-gas ratio, chemistry operating parameters, limestone grinding and classification, materials selection for a rugged environment, byproduct disposal, and scrubber performance monitoring. The paper will also briefly review cutting-edge alternatives to spray towers.
