Over-fire air distribution manner in front and back wall opposed firing boiler

Abstract

The invention discloses an over-fire air distribution manner in a front and back wall opposed firing boiler; a boiler firing method is in the form of front and back wall opposed firing, and over-fire air is fed by using a tangent circle method. The front and back wall opposed firing boiler comprises a front and back wall opposed firing boiler; with a symmetric central line of a long edge of the boiler as boundary, the over-fire air is divided into two groups; 4-5 over-fire air nozzles are arranged in each group; central lines of the over-fire air sprayed by the over-fire air nozzles in each group are tangential to the same imaginary ellipse; rotation directions of the ellipses in the two groups are reverse to each other; and one ellipse rotates in an anticlockwise direction and the other ellipse rotates in a clockwise direction. The over-fire air is high speed direct current over-fire air; and the over-fire air nozzles swing up and down and from left to right in a full-swinging form. The over-fire air distribution manner in the front and back wall opposed firing boiler, disclosed by the invention, is beneficial for enhancing the mixing of the over-fire air and rising flue gas and increasing the travel of the flue gas and prolonging the staying time of a fuel in the oven, and has the advantages that NOx emission of the boiler is obviously reduced and the increase of carbon content in boiler fly ash and the increase of the temperature-reduction water quantity are effectively suppressed.

Description

technical field [0001] The invention relates to an arrangement method of overburning air, in particular to an arrangement method of overburning air adopting a double tangential circle feeding method in a front and rear wall opposing combustion boiler, and belongs to the technical field of low-nitrogen combustion of power plant boilers. Background technique [0002] At present, the main combustion methods used in large pulverized coal combustion boilers are the four-corner tangential combustion method and the front and rear wall confrontation combustion method. [0003] In the four-corner tangential combustion method, the axis of the airflow (fuel and air distribution) ejected from the straight-line burners arranged at the four corners of the furnace is tangent to one or more imaginary circles in the center of the furnace, and the flame formed by combustion and the smoke produced The gas rotates and rises in the furnace, and the flames at the four corners interact to form a l...

AI Technical Summary

Problems solved by technology

[0011] The purpose of the present invention is to propose an arrangement of overfire air that adopts a double-cut elliptical feeding method in the opposite-wall combustion boiler, which is specially designed for the low-nitrogen combustion transformation of the rectangular furnace of the opposite-front wall combustion boiler, so as to solve the problem of early subsidence During the low-nitrogen combustion transformation process of the critical front-to-back wall opposed combustion boiler, the way of sending the overfire air into the front and rear wall is adopted. Due to the poor mixing of the flue gas in the later stage and the relatively short stroke of the flue gas, the furnace outlet after the low-nitrogen combustion transformation is Smoke temperature, boiler desuperheating water volume and fly ash carbon content increase, as well as the overheating of the tube wall of the panel heating surface, the technical problems that have an adverse impact on the safety and economy of the boiler after transformation

Images