BOILER PROVIDED WITH AN INTEGRATED SYSTEM FOR CATALYTIC ABATEMENT OF NITROGEN OXIDES

摘要

According to the invention, the descending vertical convective-exchange channel (5) of the boiler, downstream from the last bank of economiser tubes (6) and upstream from the outlet section of the horizontal channels (7), is provided with a U-shaped lower extension (20) located between the descending vertical channel (5) downstream from the last bank of economiser pipes (6) and the horizontal gas-outlet channels (7), which extension includes a specific catalyst (10) for the reaction comprising nitrogen oxide abatement by an ammoniacal reducing agent. The reagent can be injected after the economiser (6) and before the catalyst (10) or in warmer upstream areas where the non-catalytic abatement reaction is produced. The invention can be used to design new boilers and to modify existing boilers.