An overview of the formation of SOx and NOx in various pyroprocessing systems

The authors identify SO₂ and NO_x emission levels of various kiln systems and explain the reasons for the variations ascertained. Various recent methods of reducing SO₂ and NO_x emission from cement kiln systems are outlined. SO₂ emission monitoring and regulations are outlined briefly and a comparison is made of SO₂ emissions from various kiln types. The kilns discussed include: wet-process kilns, long dry-process kilns, preheater kilns, and precalciner kilns. Methods for reducing SO₂ emissions are discussed. The formation of nitrogen oxide in kilns is also discussed. Finally, techniques for reducing NO_x emissions are examined