Apparatus and method to control emissions of nitrogen oxide

摘要

A combustion apparatus which has a post combustion hot gas fan and a recirculation duct positioned down stream from the fan to reduce NOx emissions by returning a portion of the exhaust from the combustion zone back to the combustion zone. For example, in one embodiment the increased velocity of the exhaust gas stream from the post combustion hot gas fan which is required to overcome the pressure drop in a post combustion treatment unit is used as the motive force for the recirculation of a portion of the exhaust to the combustion zone to reduce the NOx exiting the apparatus to a level below that of the post combustion treatment alone.