| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem of unbalanced ammonia injection due to the reduction in injection amount of ammonia when the denitrification load lowers by mixing steam into the aqueous ammonia vapor to compensate the decrement of the aqueous ammonia vapor flow rate and apply the same pressure drop across one of nozzles as that before the decrease in aqueous ammonia vapor flow rate is caused, to each of the nozzles when the injection amount of aqueous ammonia vapor is reduced. SOLUTION: In this device, an aqueous ammonia vapor pipeline 10 is provided with a steam injection means downstream from a flow control valve 9 and steam is introduced to a steam pressure reducing valve 15 through a steam pipeline 14 to reduce the stream pressure to a value higher than the total value ((1)+(2)+(3)) of (1) the pressure drop across one of nozzles 13 at the time of allowing the aqueous ammonia vapor to flow at an intended flow rate, namely, at a flow rate before the reduction in injection amount of the aqueous ammonia vapor is caused, (2) the pressure drop across the aqueous ammonia vapor pipeline 10 and one of nozzle headers 11 and (3) the static pressure of a duct 2. When the amount of Nox produced reduced because of a change in denitrification load and accordingly, the injection amount of the aqueous ammonia vapor is reduced, steam is mixed into the aqueous ammonia vapor to compensate the decrement of the aqueous ammonia vapor flow rate and to maintain the injection velocity of the ammonia vapor at an intended nozzles 13 and further, to uniformly inject the aqueous ammonia vapor into the each of the nozzles 13 and further, to uniformly inject the aqueous ammonia vapor into the duct 2. |
