| 摘要 |
PURPOSE:To obtain a high NOx removing efficiency by supplying at least a part of shortage air from the bottom of a furnace in a combustion in which the combustion at a burner part is carried out at an air ratio of 1 or less and an unburnt matter is burnt by the air corresponding to the shortage air supplied through such as an after-airport. CONSTITUTION:A plurality o burners 30 arranged in the furnace 10 are set to have the air ratio of 1 or less, and a low oxygen combustion is carried out by recirculating a part of exhaust gas G through a duct 61. NOx produced in the low oxygen combustion is reduced into N2 in contact with reductive intermediate products such as CN or CO which is also produced in the combustion. In this instance, a gas mixture is supplied from the bottom of the furnace of the recirculated exhaust gas G through the recirculated exhaust gas duct 62 and a combustion air through air ducts 51 and 52. A part of this combustion air is supplied through the after-airport 31 for combustion of the unburnt matter at such a regulated rate as to set the total amount of the air at a necessary and minimum value for the combustion of unburnt substance. |
