Flow-equalizing multi-angle tangential pulverized coal decoupling combustion device and combustion method

Abstract

The invention discloses a flow-equalizing multi-angle tangential pulverized coal decoupling combustion device and a combustion method. The device comprises a multi-angle tangential combustion hearth, wherein the multi-angle tangential combustion hearth comprises a hearth angle wall and hearth side walls; and a plurality of rows of primary air spraying holes, ignition secondary air spraying holes and over-fire air spraying holes, which are formed in the height direction, are formed in the wall of the multi-angle tangential combustion hearth. The invention further discloses a method for performing combustion by utilizing the combustion device. The multi-angle tangential pulverized coal decoupling combustion device provided by the invention can realize multi-scale NOx emission reduction according to the pulverized coal combustion characteristics and the NOx transformation rule, and improves the defects of the conventional multi-angle tangential pulverized coal decoupling combustion device.

Description

technical field [0001] The invention relates to the field of pulverized coal combustion equipment. Specifically, the invention relates to a decoupling combustion device and combustion method for uniform flow multi-angle tangential circle pulverized coal. Background technique [0002] There is a difficult coupling problem between the efficiency of pulverized coal combustion and NOx emissions. Combustion of pulverized coal under high temperature and high oxygen conditions is conducive to burnout, but it will increase the formation of nitrogen oxides NOx; on the contrary, combustion at low temperature and low oxygen is beneficial to suppress the formation of NOx, but pulverized coal is less likely to burn out. [0003] At present, air staged combustion technology is the most effective low NOx combustion technology for pulverized coal boilers. The macro-air staged combustion technology mainly uses the increase of the burn-off air and the distance to the main combustion zone to ...

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Problems solved by technology

Compared with the traditional four-corner tangential combustion pulverized coal furnace, although the scheme proposed by the patent (patent application number: 201110374539X) has improved the degree of centralized arrangement of the primary air, the primary air and secondary air are arranged correspondingly in groups. The mixing of the secondary air is relatively concentrated, which is prone to local overoxygen and high temperature, which is not conducive to the formation of a stable and uniform reducing atmosphere to suppress the formation of NOx

[0006] Compared with the traditional four-corner tangential combustion pulverized coal furnace, since the distance between the upstream and downstream adjacent nozzles of the patent is reduced, and the jet flow direction of some upstream nozzles is perpendicular to the jet flow direction of the downstream nozzle, the lateral thrust of the upstream airflow on the downstream airflow increases. The diameter of the tangential circle of the rotating airflow in the furnace is too large, and the airflow and pulverized coal particles are too concentrated around the furnace wall. On the one hand, it is easy to cause coking on the furnace wall; on the other hand, the combustion fullness of the furnace decreases, and the utilization of the middle part of the furnace decreases.

Due to the large deflection of the furnace wall jet and less jet suction of the secondary air at the corners, the rising speed of the airflow near the furnace wall and the corner area of ​​the furnace in this multi-angle tangential combustion scheme is higher than that of the original four-corner tangential combustion In this way, the downward flow of the airflow in the middle and lower part of the furnace increases, and the falling speed is faster, resulting in an increase in the proportion of slag and the carbon content of slag

[0007] In addition, for the traditional air-staged low-nitrogen combustion of low-volatility and refractory coal, a lower excess air coefficient should be used at the initial stage of combustion and in the lower part of the furnace, but too low air volume will reduce the combustion intensity of the combustion zone and the reaction temperature. Conducive to stable combustion, increased combustion speed and rapid precipitation of nitrogen

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