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.

1 . A dense phase swirl pulverized coal burner, characterized by comprising
 a primary air channel ( 1 ) provided with the following parts communicated successively: an elbow section as a pulverized coal inlet, a straight tube section arranged horizontally and a primary air nozzle; and an oil gun casing ( 4 ) arranged on a central shaft of the straight tube section and a torch oil gun of the burner arranged inside the oil gun casing ( 4 );   a direct flow secondary air channel ( 2 ) arranged around outer wall of the nozzle of the primary air channel ( 1 ), and a swirl secondary air channel ( 3 ) arranged around outer wall of a nozzle of the direct flow secondary air channel ( 2 ) with the direct flow secondary air channel ( 2 ) and the swirl secondary air channel ( 3 ) distributed with air in a same big wind box;   wherein, multiple levels of pulverized coal concentration rings ( 6 ) are arranged axially at intervals along the oil gun casing ( 4 ) in the straight tube section of the primary air channel ( 1 ); and each level of the pulverized coal concentration rings ( 6 ) is a cone flaring structure arranged around outer edge of the oil gun casing ( 4 ), and a cone flaring opening thereof faces the primary air nozzle so that pulverized coal air flow is distributed thickly outside and thinly inside the primary air nozzle after being subject to multiple levels of cone flaring.   
     
     
         2 . The dense phase swirl pulverized coal burner according to  claim 1 , characterized in that
 the elbow section of the primary air channel ( 1 ) is provided with a pulverized coal flow equalizing plate ( 5 ) arranged around the central shaft of the elbow section and divided into two-layer air channels in the elbow section;   one end of the pulverized coal flow equalizing plate ( 5 ) is arranged on an inlet of the elbow section, and the other end thereof extends to an outlet of the elbow section, i.e. the position communicating the elbow section with the straight tube section so that the pulverized coal air flow passes through the elbow section, is distributed uniformly and circumferentially, and enters the straight tube section.   
     
     
         3 . The dense phase swirl pulverized coal burner according to  claim 1 , characterized in that
 the nozzle of the primary air channel ( 1 ) is provided with multiple guide vanes ( 7 ) arranged uniformly and circumferentially around inner wall thereof;   positions of the guide vanes ( 7 ) are matched with path field of the dense phase pulverized coal air flow so that the dense phase pulverized coal air flow forms disturbed flow and is ejected at a certain swirl angle; and dilute phase pulverized coal air flow at the center of the nozzle is ejected into an external furnace directly.   
     
     
         4 . The dense phase swirl pulverized coal burner according to  claim 1 , characterized in that
 outer walls of the nozzles of the primary air channel ( 1 ), the direct flow secondary air channel ( 2 ) and the swirl secondary air channel ( 3 ) are provided with flow expanding cone structures ( 8 ,  9 ,  10 ) respectively; and   cone flaring openings of the flow expanding cone structures ( 8 ,  9 ,  10 ) are respectively arranged toward the external furnace so as to delay mixing time of secondary air and primary air.   
     
     
         5 . The dense phase swirl pulverized coal burner according to  claim 1 , characterized in that
 the oil gun casing ( 4 ) of the straight tube section is provided with 2-3 levels of pulverized coal concentration rings ( 6 ), and size of the pulverized coal concentration rings ( 6 ) is enlarged by levels.   
     
     
         6 . The dense phase swirl pulverized coal burner according to  claim 5 , characterized in that
 a cone flaring angle (α) of each level of the pulverized coal concentration rings ( 6 ) is within the range of 10°-25°.   
     
     
         7 . The dense phase swirl pulverized coal burner according to  claim 3 , characterized in that
 the nozzle of the primary air channel ( 1 ) is provided with 10-20 guide vanes ( 7 ) around inner wall thereof.   
     
     
         8 . The dense phase swirl pulverized coal burner according to  claim 7 , characterized in that
 an included angle between each of the guide vanes ( 7 ) and axial direction of the primary air channel ( 1 ) is 10°-30°, and radial height of the guide vanes ( 7 ) along the primary air channel ( 1 ) is 0.05-0.1 time the diameter of the primary air channel ( 1 ).   
     
     
         9 . The dense phase swirl pulverized coal burner according to  claim 4 , characterized in that
 cone flaring angles (β 1 , β 2 , β 3 ) of the multiple flow expanding cone structures are not more than 45° respectively.   
     
     
         10 . The dense phase swirl pulverized coal burner according to  claim 1 , characterized in that
 the direct flow secondary air channel ( 2 ) is provided with a regulating device ( 11 ) for regulating air flow; and the swirl secondary air channel ( 3 ) is provided with a regulating device ( 12 ) for regulating swirl air strength.