| 摘要 |
PURPOSE:To keep the generation of NOx in a low level by flowing a part of air along furnace walls near burners to keep only the neighborhood of the furnace walls in an oxidizing atmosphere. CONSTITUTION:At the lower, middle, and upper locations of burners 2 a plurality of air nozzles 8, 9 are placed and the input of a certain amount of air (10-20% of theoretical air amount) into a furnace 1 from those nozzles results in forming air layer only at the neighborhood of furnace wall surfaces and sealing the front wall 1a, the back wall 1b, and the both side walls 1c not to be exposed directly to strong reducing gas. Further, as the upper air nozzles 3 are placed above the burners 2 and remaining air necessary to complete burning is put into the furnace 1 from those nozzles, an atmosphere is gradually changed into the oxidizing one to complete burning reaction at the outlet of the furnace 1. As reliable air layers are formed at the neighborhood of the furnace walls, furnace wall tubes are surely prevented from corroding and also adhesion of molten ash on the surfaces of the furnace wall tubes is reduced, when coal is used and reduction of NOx is able to be more surely carried out.
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