Flue gas recirculating system for low-nitrogen combustion and slag-bonding prevention of W-flame boiler

Abstract

The invention relates to a flue gas recirculating system for low-nitrogen combustion and slag-bonding prevention of a W-flame boiler. The flue gas recycling system comprises a boiler smoke exhaustingopening, a cyclone dust collector and a recirculating flue gas distributor, the boiler smoke exhausting opening communicates with a gas inlet of the cyclone dust collector, the cyclone dust collectoris connected with a recirculating fan through a boiler smoke pipeline, the recirculating fan is connected with the recirculating flue gas distributor, the recirculating flue gas distributor comprisesan inner annular channel and an outer annular channel, the inner annular channel is formed in the outer annular channel, a plurality of hydrocyclones are arranged on the outer annular channel, and anelectric regulating valve is arranged on the inner annular channel. High-temperature flue gas of the system is taken from the lower part of an economizer at the tail of the boiler, the temperature is10 DEG C-20 DEG C higher than the temperature of hot primary air and hot secondary air at an outlet of an air preheater, the flue gas is introduced into an under-arch area of a hearth of the boiler, the amount of the flue gas in the boiler can be increased, the main steam temperature and the reheat steam temperature are increased, the NOx generation amount is controlled, slag-bonding of a water-cooling wall of the under-arch area of the boiler is prevented, and the flue gas recirculating rate is controlled at 10%-20%.

Description

technical field [0001] The invention belongs to the field of power station pulverized coal boilers, and in particular relates to a flue gas recirculation system for low-nitrogen combustion and slagging prevention of a W flame boiler. Background technique [0002] For anthracite with low volatile coal quality, W flame boiler is generally selected for boiler design. W flame boiler pulverized coal ignites and burns out relatively laggingly. In order to improve combustion stability, a guard combustion belt is laid on the lower furnace of W flame boiler to enhance the heat load intensity of the furnace section; due to the low volatile content of coal combustion and the high temperature of the combustion flame , the NOx produced by W flame boiler combustion is generally 1000-1500mg / m 3 , Compared with the NOx concentration produced by burning bituminous coal and lignite boilers, it is much higher. [0003] Due to the high temperature of the furnace, slagging of W flame boilers m...

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Problems solved by technology

In recent years, some scientific research institutes and boiler manufacturers have proposed to use flue gas recirculation technology in traditional intermediate reheat boilers to solve problems such as low reheat steam temperature and high temperature corrosion, but less use of flue gas in W flame boilers The gas recirculation technology and the way of recirculating flue gas entering the furnace are also rarely studied. The problems of slagging in the lower furnace of W flame boilers and high NOx generated by combustion are more prominent

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