Dense Phase Swirl Pulverized Coal Burner

Abstract

A dense phase swirl pulverized coal burner comprises a primary air channel, a direct flow secondary air channel and a outermost swirl secondary air channel; and multiple levels of pulverized coal concentration rings are arranged axially at intervals along the oil gun casing in a straight tube section of the primary air channel, so that pulverized coal air flow is distributed thickly outside and thinly inside the primary air nozzle. In the invention, dense phase pulverized coal outside the primary air nozzle passes through guide vanes, forms disturbed flow, is ejected into a furnace and mixes with high temperature backflow flue gas rapidly and sufficiently at an outlet. Meanwhile, dilute pulverized coal air flow at the center is ejected into the furnace by direct flow, ensuring subsequent mixing and combustion of pulverized coal flow. The primary air nozzle and the secondary air nozzle are provided with cone flaring structures with certain angle to effectively control appropriate mixing of secondary air and pulverized coal. The invention has advantages of strong ignition and combustion stability, good coal adaptability, low nitric oxide emission, simple primary air channel structure and small resistance, which effectively slows wear rate of parts.

Description

FIELD OF THE INVENTION[0001]The invention relates to the technical field of coal fired boilers in power plants, in particular to a dense phase swirl pulverized coal burner used for a coal-fired boiler.DESCRIPTION OF THE RELATED ART[0002]As nitric oxide emissions from boilers of coal-fired power plants are strictly controlled in China in recent years, a supporting low NOx burner technology of full furnace staged combustion low NOX technology is widely used, particularly various different low NOx swirl burner technologies in wall-fired boilers.[0003]In order to effectively reduce nitric oxides produced from combustion in a furnace of a wall-fired boiler, for the full furnace staged combustion technology, part of oxygen that is delivered from a main combustion zone to realize burning-out in early technologies (i.e. pulverized coal is sent to a burner zone of the furnace, hereinafter referred to as the main combustion zone) is supplied to the furnace through a special air port at the up...

AI Technical Summary

Benefits of technology

The invention is a dense phase swirl pulverized coal burner for a power plant boiler. It enhances the mixing of pulverized coal and air flows through a nozzle by a disturbed flow, resulting in rapid ignition and stable combustion. The primary air passes through a pulverized coal flow equalizing plate to form two layers around the air channel. The pulverized coal concentration rings in the burner help enhance the mixing and burning-out of the pulverized coal air flow. The cone flaring action of the primary air nozzle delays the mixing of secondary air and primary air, resulting in an oxygen-deficient atmosphere and preventing clogging and corrosion. The burner has a simple structure, slows down wear and tear, and has high efficiency and low nitric oxide emission. The invention is useful for both new and retrofitted power plants.

Problems solved by technology

However, 3 issues exist for application of the burner technology: 1, in order to divide pulverized coal air flow in the primary air channel into dense flow and thin flow circumferentially, uniformly and effectively, the burner always has relatively complex structure, which may increase system resistance, increase fan load and house supply, wear the channel, shorten life cycle of equipment and increase operation and maintenance cost of power plants; 2, due to poor adaptability of coal, particularly poor steam coal in China, actual coal ignition and combustion stability can not reach original design requirements, and flame at outlet of the burner is always unstable during peak regulation of the boiler; and 3, due to poor subsequent mixing performance of primary air pulverized coal air flow and secondary air pulverized coal air flow at the nozzle of the burner, coal in the burner cannot be burnt out, possibly increasing loss.

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