Method for combusting fuel reburning low-nitrogen oxide

Abstract

The invention discloses a method for combusting a fuel reburning low-nitrogen oxide and belongs to a clean combustion method for a coal-fired boiler. Secondary medium air is used as a powder conveying medium of a combustor on the upper layer of the main combustion area of the boiler, coal powder used as a reburning fuel is conveyed into the boiler, the secondary medium air is used as distributed air of the combustor, the secondary air of the combustor on the upper layer is reduced correspondingly, the distributed air in the reburning area is reduced correspondingly, low excess air combustion is formed, the distributed air in a hearth is not enough, and finally over fire air (OFA) complements the required air; and the mixed medium of air and fuel gas is used as the conveying medium of the coal powder of the combustor of the upper layer, and the coal powder with the conventional fineness is conveyed into the boiler from the combustor on the upper layer by using a coal mill and a powder making system and is re-burnt and denitrated, and is burnt out by OFA. The problem that the reburning fuel and the fuel gas are not mixed uniformly, the reduction time is short, and the denitration efficiency is low is solved, the original design working conditions of maximum continuous evaporation capacity of the boiler and the like are not influenced, transformation is easy to realize, and the running cost is low.

Description

technical field [0001] The invention relates to a method for clean combustion of a coal-fired boiler, in particular to a method for fuel reburning and low-nitrogen oxide combustion. Background technique [0002] Combustion of pulverized coal in thermal power stations is currently the main source of nitrogen oxides. Currently, developed countries mainly use selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR) to remove nitrogen oxides. The focus of domestic research is on removal through organized combustion in the furnace, including low-nitrogen burners, fuel concentration separation, air classification, fuel classification and recombustion technology, flue gas recirculation, etc. However, the actual denitrification efficiency of the reburning technology is much lower than that of the laboratory. The reburning denitrification efficiency on the test bench can reach more than 70%, while the actual operation of large boilers has proved that it can on...

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Problems solved by technology

[0004] The purpose of the present invention is to provide a method for fuel reburning with low nitrogen oxides to solve the problem of reburning requiring specially ground ultra-fine pulverized coal, and the source of ultra-fine pulverized coal is difficult; air is a powder feeding medium with high oxygen content and fast ignition , the generation of reducing substances is small, and the reburning fuel is injected at a high level, so that the mixing space of nitrogen oxides and reducing substances in the flue gas is small, the time is short, the mixing is insufficient, and the denitrification efficiency is low.

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