| 摘要 |
PURPOSE:To effectively decrease nitrogen oxides, and to prevent intermediate combustion products such as carbon monoxide from being discharged to the outside, by providing an exhaust gas introducing pipe having a catalytic function to reduce combustion exhaust gas, running from the neighborhood of the forming position of a flame in a combustion chamber to the neighborhood of the inlet of a burner body. CONSTITUTION:The inlet part 18 of an exhaust gas introducing pipe 17 for combustion exhaust gas is inserted into a combustion chamber 9 from a back space 16 to be disposed in the neighborhood of the forming position of a flame 8. The outlet part 19 of an exhaust gas introducing pipe 17 for combustion exhaust gas is inserted into a burner throat 2 from the bottom of a back space 16. The exhaust gas introducing pipe 17 has a double-wall structure, of which inner pipe 20 is made of a material having a catalytic function to reduce gas, stainless steel for example. It is not necessary to use an exhaust gas recycling blower because fuel exhaust gas flowing into the exhaust gas introducing pipe 17 is fully led into the burner throat 2 only by the suction effect of reduced pressure by injecting force of fuel. Low NOx combustion can be caused by the decrease of concentration of O2 in combustion air in the combustion chamber 9 and by lowering of the temperature in a flame because part of combustion exhaust gas is returned to the burner throat 2.
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