Knowledge for the Sulphuric Acid Industry
Sulphuric Acid on the Web
Acid Plant Database
Boiler Feed Water
Materials of Construction
DKL Engineering, Inc.
June 22, 2003
The burning of sulphur in air in a typical furnace has temperatures and residence times that result in the formation of thermal NOx. The figure to the right illustrates the relationship between furnace temperature/SO2 concentration and the relative formation of NOx in the sulphur furnace. In some processes where high SO2 concentrations are required, the formation of NOx is at its maximum. At concentrations above 18% SO2, the O2 still present in the gas has a greater influence on the degreeof NOx formation than does the temeprature. Therefore, by limiting the amount of oygen in the gas, NOx formation can be minimize even though the operating temperature is high.
Special stage combustion techniques and gas recycle can be used to reduce NOx formation.