| 摘要 |
PURPOSE:To prevent the percentage of excess air of a boiler from exceeding of the specified value and consequently stabilize the combustion in the boiler and at the same time prevent the nitrogen oxides in exhaust gas from increasing by a method wherein the signal detecting the oxygen content in the exhaust gas is compared with the set oxygen concentration value in exhaust gas at a subtracter. CONSTITUTION:An oxygen-in-exhaust-gas transmitter 6 detects the oxygen concentration in the exhaust gas passing through a flue 5 and outputs an oxygen-concentration-in- exhaust-gas signal 30 to a subtracter 7. The subtracter 7, in which the set oxygen concentration value 31 set in advance as for the desirable oxygen concentration in exhaust gas is inputted compares said signal 30 with the set oxygen concentration value 31 in order to input the difference between the signal 30 and concentration value 31 in the form of an oxygen-in-exhaust-gas deviation signal 32 to an integrating controller 8 and a function generator 9. When the oxygen concentration in exhaust gas decreases, the function generator 9 immediately outputs the correction signal to increase the air flow rate. On the contrary, when the oxygen concentration in exhaust gas increases, the function generator 9 outputs the correction signal to decrease the air flow rate so as to decrease the oxygen concentration in exhaust gas before the increase of nitrogen oxides become a problem. |
