The flow field of flue gas in denitrification reactor using selective catalytic reduction (SCR) has remarkable influence upon the actual effectiveness of said reactor.A mathematical simulation has been carried out for flow field of the flue gas at entrance of SCR reactor

for ammonia distribution in the reactor

and for flow field of flue gas at outlet of the reactor.Through adding arc-shaped baffle plates at the elbows

adjusting the open-degree of ammonia spraying valves

and adding four vertical baffle plates at outlet section of the SCR reactor

the flow speed of flue gas and the ammonia distribution in SCR denitrification reactor have been optimized.Under prerequisite condition of ensuring the escape rate of ammonia

the denitrification efficiency can reach the designed value.Through simulation

the flue duct and reactor have been optimized

reducing greatly the washing away of catalyst by flue gas

eliminating ash deposition in the flue duct and reactor.