W-staged flame boiler for multi-stage combustion with multi-ejection and its method thereof

Abstract

A method for a flame boiler with multi-stage combustion with multi-ejection, includes the steps of ejecting inner and outer secondary air flows with speed of 35-65 m/s to guide a fuel-rich pulverized coal flow with speed of 10-20 m/s into a lower chamber to provide first and second combustion stages, ejecting lower secondary air flows with speed of 35-65 m/s into the lower chamber to further guide the pulverized coal so as to provide a third combustion stage. The system includes a lower chamber, an upper chamber, a combustion chamber, fuel-rich pulverized coal flow nozzles, fuel-lean pulverized coal flow nozzles respectively provided at the front and rear boiler arches, and lower secondary air nozzles provided at the front and rear water cooled walls. The combustion of the pulverized coal flow with W-shaped flowing path within the boiler is adapted to reduce NO x emission and minimize the content of combustible substance in ash.

1 . A method for multi-stage combustion with multi-ejection by a boiler, comprising the steps of:
 orderly configuring a plurality of fuel-rich pulverized coal flow nozzles  10 , a plurality of inner secondary air nozzles  11 , a plurality of fuel-lean pulverized coal flow nozzles  12 , and a plurality of outer secondary air nozzles  13  at a combustion chamber, wherein said fuel-rich pulverized coal flow nozzles  10 , said inner secondary air nozzles  11 , said fuel-lean pulverized coal flow nozzles  12 , and said outer secondary air nozzles  13  are alignedly and orderly located between a center line  2 - 1  of said combustion chamber and a front water cooled wall  2 - 2  of said combustion chamber at a front boiler arch  3  and between said center line  2 - 1  of said combustion chamber to a rear water cooled wall  2 - 3  of said combustion chamber at a rear boiler arch;   ejecting fuel-rich pulverized coal flows  5  into said lower chamber  1  through said fuel-rich pulverized coal flow nozzles  10  respectively, ejecting inner secondary air flows  6  into said lower chamber  1  through said inner secondary air nozzles  11  respectively, ejecting fuel-lean pulverized coal flows  7  into said lower chamber  1  through said fuel-lean pulverized coal flow nozzles  12  respectively, and ejecting outer secondary air flows  8  into said lower chamber  1  through said outer secondary air nozzles  13  respectively, wherein a speed of said inner secondary air flow  6  is about 35-65 m/s, a speed of said outer secondary air flow  7  is about 35-65 m/s, a speed of said fuel-rich pulverized coal flow  5  is about 10-20 m/s, wherein said inner and outer secondary air flows  6 ,  7  are sequently ejected into said lower chamber  1  to mix and guide with said fuel-rich pulverized coal flow  5  in a down-streaming manner so as to provide a first combustion stage and a second combustion stage respectively;   ejecting lower secondary air flows  9  into the lower chamber  1  via a plurality of lower secondary air nozzles  14 , wherein a speed of said lower second air flow  9  is about 35-65 m/s, wherein said lower secondary air nozzles  14  are provided at said front and rear water cooled wall  2 - 2 ,  2 - 3  of said lower chamber  1  respectively to eject said lower secondary air flows  9  into the lower chamber  1  and to mix and guide with said fuel-rich pulverized coal flow  5  in a down-streaming manner so as to further provide a third combustion stage; wherein said lower secondary air nozzles  14  are inclinedly extended from said front and rear water cooled wall  2 - 2 ,  2 - 3 , wherein an inclination angle α of each of said lower secondary air nozzles  14  is about 25°-45°, wherein said fuel-rich pulverized coal flow nozzles  10 , said fuel-lean pulverized coal flow nozzles  12 , said lower secondary air nozzles  14 , said inner secondary air nozzles  11  and said outer secondary air nozzles  13  all have a cross section selected from the group consisting of rectangular cross section and round cross section, wherein said fuel-rich pulverized coal flow nozzle  10  with rectangular cross section has a length-width ratio of 4˜5:1.   
     
     
         2 . The method, as recited in  claim 1 , wherein said inclination angle α of each of said lower secondary air nozzles  14  is 45°. 
     
     
         3 . A W-shaped flame boiler for multi-stage combustion with multi-ejection, comprising a lower chamber  1 , an upper chamber  2  positioned below said lower chamber  1 , a combustion chamber formed by two boiler arches which are front boiler arch  3  and rear boiler arch  15  respectively, a plurality of fuel-rich pulverized coal flow nozzles  10 , a plurality of fuel-lean pulverized coal flow nozzles  12 , a plurality of lower secondary air nozzles  14 , a plurality of inner secondary air nozzles  11 , and a plurality of outer secondary air nozzles  13 , wherein said inner and outer secondary air nozzles  11 ,  13  generate two sequent air flows, wherein said fuel-rich pulverized coal flow nozzles  10 , said inner secondary air nozzles  11 , said fuel-lean pulverized coal flow nozzles  12 , and said outer secondary air nozzles  13  are alignedly and orderly located between a center line  2 - 1  of said combustion chamber and a front water cooled wall  2 - 2  of said combustion chamber at said front boiler arch  3  and between said center line  2 - 1  of said combustion chamber to a rear water cooled wall  2 - 3  of said combustion chamber at said rear boiler arch  15 , wherein a plurality of lower secondary air nozzles  14  are provided at said front and rear water cooled wall  2 - 2 ,  2 - 3  of said lower chamber  1  respectively at a position that said lower secondary air nozzles  14  are inclinedly extended from said front and rear water cooled wall  2 - 2 ,  2 - 3 , wherein an inclination angle α of each of said lower secondary air nozzles  14  is about 25°-45°, wherein said fuel-rich pulverized coal flow nozzles  10  are grouped to form a plurality of fuel-rich pulverized coal flow nozzle arrangements  16 , each said fuel-rich pulverized coal flow nozzle arrangement  16  has two fuel-rich pulverized coal flow nozzles  10  positioned close to each other, wherein said fuel-rich pulverized coal flow nozzle arrangements  16  are aligned at an in-line formation along a transverse direction of said combustion chamber and evenly spaced apart with each other, wherein said fuel-lean pulverized coal flow nozzles  12  are grouped to form a plurality of fuel-lean pulverized coal flow nozzle arrangements  17 , each said fuel-lean pulverized coal flow nozzle arrangement  17  has two fuel-lean pulverized coal flow nozzles  12  positioned close to each other, wherein said fuel-lean pulverized coal flow nozzle arrangements  17  are aligned at an in-line formation along said transverse direction of said combustion chamber and evenly spaced apart with each other, wherein said inner secondary air nozzles  11  are aligned at an in-line formation along said transverse direction of said combustion chamber and evenly spaced apart with each other, wherein said outer secondary air nozzles  13  are aligned at an in-line formation along said transverse direction of said combustion chamber and evenly spaced apart with each other, wherein said fuel-rich pulverized coal flow nozzles  10 , said fuel-lean pulverized coal flow nozzles  12 , said lower secondary air nozzles  14 , said inner secondary air nozzles  11  and said outer secondary air nozzles  13  are all communicating with said lower chamber  1 , wherein said fuel-rich pulverized coal flow nozzles  10 , said fuel-lean pulverized coal flow nozzles  12 , said lower secondary air nozzles  14 , said inner secondary air nozzles  11  and said outer secondary air nozzles  13  all have a cross section selected from the group consisting of rectangular cross section and round cross section, wherein said fuel-rich pulverized coal flow nozzle  10  with rectangular cross section has a length-width ratio of 4˜5:1. 
     
     
         4 . The W-shaped flame boiler, as recited in  claim 3 , wherein a total cross sectional area of said fuel-rich pulverized coal flow nozzle  10  with said round cross section is the same as a total cross sectional area of said fuel-rich pulverized coal flow nozzle  10  with said rectangular cross section, wherein a total cross sectional area of said fuel-lean pulverized coal flow nozzle  12  with said round cross section is the same as a total cross sectional area of said fuel-lean pulverized coal flow nozzle  12  with said rectangular cross section, wherein a total cross sectional area of said lower secondary air nozzle  14  with said round cross section is the same as a total cross sectional area of said fuel lower secondary air nozzle  14  with said rectangular cross section, wherein a total cross sectional area of said inner secondary air nozzle  11  with said round cross section is the same as a total cross sectional area of said inner secondary air nozzle  11  with said rectangular cross section, wherein a total cross sectional area of said outer secondary air nozzle  13  with said round cross section is the same as a total cross sectional area of said outer secondary air nozzle  13  with said rectangular cross section. 
     
     
         5 . The W-shaped flame boiler, as in  claim 3  or  4 , wherein said fuel-rich pulverized coal flow nozzles  10  at said front boiler arch  3  are symmetrically aligned with said fuel-rich pulverized coal flow nozzles  10  at said rear boiler arch  15  along said center line  2 - 1  of said combustion chamber, wherein said inner secondary air nozzles  11  at said front boiler arch  3  are symmetrically aligned with said inner secondary air nozzles  11  at said rear boiler arch  15  along said center line  2 - 1  of said combustion chamber, wherein said fuel-lean pulverized coal flow nozzles  12  at said front boiler arch  3  are symmetrically aligned with said fuel-lean pulverized coal flow nozzles  12  at said rear boiler arch  15  along said center line  2 - 1  of said combustion chamber, wherein said outer secondary air nozzles  13  at said front boiler arch  3  are symmetrically aligned with said outer secondary air nozzles  13  at said rear boiler arch  15  along said center line  2 - 1  of said combustion chamber.