Due to the limited space

the SCR equipments cannot be installed in conventional ways during denitration transformation for some coal-fired units. To solve this problem

a new type of connecting flue for the SCR denitration system was designed

which is asingle flue with side-inlet and side-outlet. Based on numerical simulation by computational fluid dynamics(CFD) software

flow field of the new-type SCR equipment was optimized. Through adding reasonable guide plates

the flue gas velocityand NH_3 concentration distribution before the first catalyst layer were improved

and the angle between the flue gas flow line and the vertical direction as well as the system resistance. were also optimized to satisfy the corresponding requirements. Moreover

this new type connecting flue was applied in SCR denitration system of a 2×135 MW coal-fired unit and it effectively solved the problem of installation of SCR equipment in limited space. The denitrification efficiency reached up to 85% and the ammonia escape was controlled below 3 mg/m~3.