System and method for reducing NOx generated by combustion of W flame boiler

Abstract

The invention provides a system and method for reducing NOx generated by combustion of a W flame boiler. The system is simple in structure, rational in design, and safe and controllable in operation,and the concentration of the NOx generated by combustion of a low volatile coal fired boiler can be reduced effectively. The system comprises a furnace, a burner arranged on the furnace, flue gas nozzles arranged at the arch part of the boiler and the lower furnace position separately, and a flue gas recirculation system; the flue gas recirculation system comprises a high temperature flue gas mixing inlet pipeline, a flue gas fan and a high temperature flue gas outlet main pipeline which are connected in sequence according to the flue gas flow direction; the input end of the high temperature flue gas mixing inlet pipeline is separately connected with different positions of a tail flue of the furnace for pumping out high temperature flue gas; and the output end of the high temperature fluegas outlet main pipeline is connected with the burner and the flue gas nozzles, and used for introducing high temperature flue gas into the furnace circularly. Through strengthening of preliminary burning of low volatile coal, the oxygen quantity of the preliminary stage of pulverized coal combustion is reduced, and the formation of a local high temperature area of the furnace is inhibited; and the purpose of controlling and reducing the NOx generated by combustion is achieved.

Description

technical field [0001] The invention relates to the technical field of energy-saving and emission-reduction transformation of coal-fired thermal power units, in particular to a system and method for reducing NOx produced by combustion of a W-flame boiler. Background technique [0002] The good match between the combustion design of the boiler system and the combustion characteristics of low volatile coal is the key to the operation performance. Take the W flame boiler as an example. W flame boiler is the main type of furnace for burning low volatile coal in my country. Due to the use of low-volatile coal, the W-flame boiler operates with high oxygen content and high furnace center temperature, resulting in high concentrations of fuel-type NOx and thermal-type NOx produced by combustion. Even though the W-flame boiler adopts low-nitrogen combustion technologies such as air staging, due to the combustion characteristics of low-volatile coal and the structural characteristics ...

AI Technical Summary

Problems solved by technology

Due to the use of low-volatile coal, the W-flame boiler operates with a high oxygen content and the furnace center temperature is high, resulting in high concentrations of fuel-type NOx and thermal-type NOx produced by combustion

Even though the W-flame boiler adopts low-nitrogen combustion technologies such as air staging, due to the combustion characteristics of low-volatile coal and the structural characteristics of the W-flame boiler, the NOx concentration produced by its combustion is still much higher than that of other furnace-type boilers, resulting in its even Combined with tail flue gas denitrification technology, it is also difficult to meet the ultra-low emission requirements of coal-fired boilers

[0003] In view of the current situation that the NOx concentration produced by the combustion of low-volatile coal W flame boilers is high and difficult to control, it is necessary to develop a technology to reduce the NOx produced by combustion of low-volatile coal boilers

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