Patent ID: 6039560
Filing Date: 2000-03-21
Classification: F23C,F23G,F23L

Abstract:
A low NO.sub.x burner comprising:a burner body comprising a combustion chamber, a nozzle that opens into a burner port that in turn opens into said combustion chamber, a fuel supply passage connected to the nozzle, a blower for supplying air for combustion, an air suction passage extending from an air source to said blower, and an air supply passage for supplying air for combustion that extends from the blower to the nozzle and surrounds the nozzle;an exhaust-gas chamber into which combustion exhaust gas is introduced from said burner body;an exhaust-gas duct connected to said exhaust-gas chamber, for conducting exhaust gas to an outlet;an exhaust-gas recirculation passage for supplying combustion exhaust gas from said burner to said air supply passage, the exhaust-gas recirculation passage having an inlet connected to said exhaust-gas chamber and an outlet connected to said air suction passage;an exhaust-gas recirculation fan provided within said exhaust-gas recirculation passage, to forcibly recirculate exhaust gas from said exhaust-gas chamber to said air supply passage;a bypass passage formed between said exhaust-gas recirculation passage and said air supply passage, one end of said bypass passage connecting to said exhaust-gas recirculation passage upstream of said exclusive exhaust-gas recirculation fan;a fuel flow meter and a fuel flow adjustment valve in said fuel supply passage;a NO.sub.x sensor in said exhaust-gas duct;a flow rate meter in said exhaust-gas recirculation passage, for detecting the quantity of exhaust gas recirculated; anda control unit for controlling said exhaust gas recirculation fan.