| 摘要 |
PURPOSE: To obtain a safe denitrification controller coping with a NOx regulating value even on startup by inputting extinguishing time on ignition of a gas turbine to calculate the minimum opening degree of an ammonia flow control valve by an arithmetic unit and controlling the lower limit of a control signal. CONSTITUTION: On startup, unreacted NH3 is discharged from a stack because of temperature characteristics of a catalyst. To prevent this fact, a function generator 42 inputs extinguishing time t and outputs a minimum opening degree m. Just after ignition, a contact 43 is operated, and the minimum opening degree m and output of the 2nd PI controller 40 are inputted to a low value controller 41. Therefore, a control signal S12 being outputted of the low value controller 41 is equalized to the minimum degree opening m to control the opening degree of an ammonia flow control valve 32 to the minimum opening degree m. At that time, ammonia injected into the catalyst is reacted only a little, but ammonia adsorbed in the catalyst is dissociated during stoppage and the adsorbed quantity of ammonia is reduced, thereby the injected ammonia is almost adsorbed and its dissociated quantity is small. |
