PURPOSE: To restrict the amount of production of NOx and maintain stably combustion condition from a high combustion to a low combustion, by a method wherein the supplying amount of a fuel supply means or an air supplying means is controlled so that the output signal of a temperature detecting unit becomes a given value in an area, in which the output signal of a flame electric current detecting unit becomes larger than a set value.
CONSTITUTION: A flame rod 13 transmits an ion current If, flowing through the combustion flame 12 of a burner 1, to the flame electric current detecting nit 15 of a control circuit 14. An electromotive force, generated in the temperature measuring contact 18 of a thermocouple 17, provided in a flow regulating space 3, is transmitted to the temperature detecting unit 20 of the control circuit 14, while a temperature retrieving unit 21 outputs a signal for changing the amount of combustion to an air ratio control unit 22 so that the output signal of the temperature detecting unit 20 becomes a given value. The flow regulating space 3 receives radiant heat from a combustion wire net 4 and the flame 12 of the surface thereof directly, therefore, the output signal from the thermocouple 17 shows a high peak value in the ratio of combustion air to fuel or the air ratio λ=1.0. Accordingly, the air ratio control unit 22 increases or decreases the supplying amount of fuel of the pump 6 so that the electromotive force Ev becomes a proper value or Ev=(a), for example, whereby the air ratio may be controlled so as to be in the vicinity of λ=1.5.
YAMAMOTO KATSUHIKO
KONAKAWA KATSUZO
MORI KEIICHI
IMAI HIROHISA
