Coupling staged combustion and smoke recirculation low NOx chain grate furnace

Abstract

The invention discloses a coupling staged combustion and smoke recirculation low NOx chain grate furnace. The chain grate furnace is composed of a hearth, a coal feeder, a chain grate stoker, a slag hopper and a tail flue. The hearth is divided into an upper hearth part and a lower hearth part through a front furnace arch and a rear furnace arch. Secondary air and over fire air are arranged in a suspension combustion area of the lower hearth body to organize staged combustion in the suspension combustion area, the secondary air of the lower hearth body is fed through secondary air spraying ports in the lower areas of the front furnace arch and the rear furnace arch, the over fire air is fed through over fire air spraying ports in the intersection of the upper hearth body and the lower hearth body, primary air is fed in a segmented mode below the stoker so as to organize the staged combustion of a stocker combustion area, low-temperature furnace smoke is extracted from the tail flue to be fed to the bottom of the stoker through a recirculation draught fan to perform recirculation, coal particles in the furnace are in the state far away from the stoichiometric ratio combustion state for a long time through two-layer staged combustion of the stocker combustion area and the suspension combustion area and smoke recirculation of the stoker combustion area, and efficient and low NOx combustion of the chain grate furnace is achieved.

Description

technical field

[0001] The invention relates to a chain furnace, in particular to a low NOx chain furnace coupled with staged combustion and flue gas recirculation, and belongs to the technical field of industrial boiler combustion. Background technique

[0002] Among the large number of coal-fired industrial boilers in my country at present, chain furnaces account for more than 60% of the market share. In terms of combustion organization, the chain furnace is dominated by constant-speed moving grate layer combustion, supplemented by suspended combustion formed by fine particles in the upper area of ​​the grate. Correspondingly, the air distribution is dominated by the primary air sent from the bottom of the grate, and the secondary air is supplemented by the front and back arches on the upper part of the grate (used to supply the air required for the suspended combustion zone and to adjust the combustion); The coal seam goes through several stages of preheating and drying,...

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