Patent ID: 6455009
Filing Date: 2002-09-24
Classification: B01D,F01N,Y02T,Y10S

Abstract:
An NOx removal system comprising:a combustion apparatus for applying energy to a load based on a predetermined combustion control process and which emits NOx as a product of combustion; an NOx remover for reacting NOx emitted from said combustion apparatus with NH3 and having a gas discharge means for removing N2 and H2O produced in said NOx remover; a gas passage extending from said combustion apparatus to said NOx remover to deliver the gaseous combustion products from said combustion apparatus to said NOx remover; an NH3 and/or urea introducing apparatus connected to said gas passage for introducing NH3 and/or urea into said NOx remover; a sensor connected to said gas discharge means of the NOx remover, for generating a detected signal based on a total of respective concentrations of NH3 and NOx contained in a gas discharged from said NOx remover; and a controller for said NH3 and/or urea introducing apparatus for controlling a rate at which NH3 and/or urea is introduced into said gas passage, said controller being in electrical contact with the sensor to receive the generated detecting signal, and said controller having means for repeatedly increasing and reducing said rate, in response to said detected signal generated by said sensor, wherein said controller and said sensor are arranged such that, when an NOx concentration in said gas passage before the NOx remover is constant, said controller and said sensor operate to cyclically increase and decrease said rate.