and gaseous no x reducing species are preferably further mixed such as by in line static mixer 34 and or turning vanes 36 36 u2032 which are positioned in passage 42 to assure good distribution when the gases reach the catalysts 26 26 u2032 and 26 u2033 fig2 is a partial sectional view taken along line 2 2 in fig1 and shows a preferred arrangement of mechanical mixers 40 40 u2032 and 40 u2033 which take the gases from the bypass channel 25 having sufficient mass for good mixing and facilitate mixing it with the bulk of the flue gas in passage 42 the nozzles 30 are shown to provide an array of spray patterns 31 and the flow of gasses past 28 and through bypass 25 will sweep the gasifying urea into an array of flow mixing devices 40 40 u2032 and 40 u2033 which terminate in openings 44 44 u2032 and 44 u2033 that can be aimed to provide turbulent mixing of the gases from bypass 25 with the bulk of the gases in passage 42 the bypass stream laden with no x reducing species can in this manner be reintroduced to the flue gas with multiple large and angled pipes 40 40 u2032 and 40 u2033 or other structures that extend beyond the wall of channel 25 to provide improved distribution the design of these pipes static mixers baffles turning vanes etc is preferably guided by computational fluid dynamics cfd and cold flow modeling catalysts 26 26 u2032 and 26 u2033 are employed in an array forming a reactor and are scr catalysts as known in the.