| 摘要 |
PURPOSE:To automatically change the preheating amount of a steam air preheater in accordance with the output of a boiler to improve the thermal efficiency of the whole plant by changing the set value of a controller of a boiler air preheating system in accordance with the output of the boiler. CONSTITUTION:In a boiler air preheating system, the average of the inlet air temperature X2 of a boiler air preheater (AH) obtained by an operational element 8 and the outlet gas temperature X1 thereof is given in a PID controller 9. On the other hand, the output X3 of a boiler is given in a functional element 10 and the AH outlet gas temperature set value y for the output X3 of a boiler is output from the functional element 10. After a deviation of the set value y output from the functional element 10 and the AH outlet gas temperature X1 measured by an AH outlet gas temperature measuring device 6 is found by a deviation detection element 11 and a specified constant is multiplied thereby in a proportional element 12, it is added to the set value of an average temperature by an addition element 13 and its output is given to the PID controller 9 as a set value. The PID controller 9 regulates the opening of a steam control valve by the deviation of the set value given from the addition element 13 and the average found by the operational element 8. |
