Patent ID: 9302222
Filing Date: 2016-04-05
CPC Classification: B01D,C01B,Y02C

Claim Text:
1. A method for reducing a nitrogen oxide off-gas concentration during at least one of a start-up or shutdown of a nitric acid manufacturing plant that is operated under pressure and is equipped with a residual gas cleaning first reactor configured to remove nitrogen oxides from off-gas during steady state operation of the plant, the method comprising: initiating at least one of the start-up or shutdown of the nitric acid manufacturing plant; directing a pressurized off-gas stream, containing nitrogen oxides from the nitrogen oxide plant and gaseous reducing agent for the nitrogen oxides, into a catalyst-filled second reactor configured to reduce the amount of nitrogen oxides in the off-gas during the at least one of the start-up or shutdown of the nitric acid manufacturing plant; and reducing the NO