Burner with center air jet
View Patent ↗A new burner apparatus and method of combusting fossils fuels for commercial and industrial application is provided wherein the new burner apparatus achieves low NO x emissions by supplying oxygen to the center of the burner flame in as manners so as to create a fuel rich internal combustion zone within the burner flame.
1. A center air jet burner comprising:
an axial pipe defining an axial zone therein, wherein the axial pipe is plugged on one end and open on the other end,
an annular pipe concentrically surrounding the axial pipe defining a first annular zone there between,
a barrel concentrically surrounding the annular pipe defining a second annular zone there between,
a burner zone wall concentrically surrounding the barrel defining a third annular zone there between,
a feeder duct radially interposed between the axial pipe and the annular pipe, wherein the feeder duct provides fluid communication between the axial zone and a windbox,
a means for conditioning a pulverized coal flow around a portion of the feeder duct contained in the first annular zone, and
a flow regulating damper in the feeder duct.
2. A burner as recited in claim 1 , wherein the axial zone contains a flow conditioning device.
3. A burner as recited in claim 1 , wherein the first annular zone contains a flow conditioning device.
4. A burner as recited in claim 2 , wherein the first annular zone contains a deflector upstream of the axial pipes plugged end.
5. A burner as recited in claim 3 , further comprising a means for providing the first annular zone with a pulverized coal.
6. A burner as recited in claim 3 , wherein the second annular zone and the third annular zone are in fluid communication with the windbox.
7. A burner as recited in claim 6 , further comprising a vane in the second annular zone.
8. A burner as recited in claim 7 , further comprising a vane in the third annular zone.
9. A burner as recited in claim 7 , further comprising an air flow measuring device and a damper in the second and third annular zones.
10. A burner as recited in claim 1 , further comprising a conduit concentrically surrounded by the axial zone.
11. A burner as recited in claim 1 ,
wherein the diameter of the axial zone is between about 9 inches and about 20 inches and the diameter of the first annular zone is between about 15 inches and 30 inches.
12. A burner as recited in claim 11 , wherein the diameter of the second annular zone is between about 20 inches to about 40 inches.
13. A burner as recited in claim 12 , wherein the diameter of the third annular zone is between about 22 inches to about 50 inches.
14. A burner as recited in claim 13 , further comprising a conduit concentrically surrounded by the axial zone.
15. A method of reducing NOx emissions in a center air jet burner comprising the steps of;
providing a four zone burner, wherein the innermost zone is an axial zone concentrically surrounded by a first annular zone, and the first annular zone is concentrically surrounded by a second annular zone, and the second annular zone is concentrically surrounded by a third annular zone;
providing a windbox in fluid communication with the axial zone, the second annular zone, and the third annular zone;
supplying the windbox with a secondary air;
providing the first annular zone with a carrier gas comprising a pulverized coal;
discharging the the carrier gas from the first annular zone at a velocity greater than about 3000 ft/min;
producing a flame by combusting the discharged pulverized coal with the secondary air discharged from the second and third annular zones;
creating a secondary air pocket in the core of the flame by discharging the secondary air provided to the axial zone at a velocity significantly greater than the carrier gas,
combusting the flame from the inside with the secondary air contained in the secondary air pocket,
creating a internal recirculation zone by discharging the secondary air provided to the second annular zone at a velocity less than the carrier gas and by discharging secondary air provided to the third annular zone at a velocity greater than the carrier gas; and
suppressing NOx emission by recirculating uncombusted coal, oxygen and NOx radicals into the flame.
16. The method as recited in claim 15 , further comprising swirling the secondary air discharged from the second annular zone.
17. The method as recited in claim 15 , further comprising swirling the carrier gas discharged from the first annular zone.
18. The method as recited in claim 16 , further comprising swirling the secondary air discharged from the third annular zone.
19. The method as recited in claim 18 , further comprising swirling the secondary air discharged from the axial zone.
20. A method of reducing NOx emissions in a center air jet pulverized coal burner comprising the steps of;
providing a burner having an axial zone concentrically surrounded by a first annular zone, a second annular zone concentrically surrounding the first annular zone and a third annular zone concentrically surrounding the second annular zone;
providing the axial zone with a first gas comprising oxygen, wherein the first gas exits the axial zone at a velocity between about 5000 ft/min and about 10,000 ft/min;
providing the first annular zone with a carrier gas comprising a pulverized coal, wherein the carrier gas exits the first annular zone at a velocity between about 3000 ft/min and about 5000 ft/min
providing the burner with a second gas comprising oxygen, wherein the second gas exits the second annular zone at a velocity between about 3000 ft/min and about 4500 ft/min, and
providing the burner with a third gas comprising oxygen, wherein the third gas exits the third annular zone at a velocity between about 5500 ft/min and about 7500 ft/min.
21. The method as recited in claim 20 , wherein the first gas exits the axial zone at a velocity between about 5500 ft/min and 7500 ft/min, and wherein the carrier gas exits the first annular zone at a velocity between about 3500 ft/min and 4500 ft/min.
22. The method as recited in claim 21 , wherein the second gas exits the second annular zone at a velocity between about 3100 ft/min and about 3900 ft/min, and wherein the third gas exits the third annular zone at a velocity between about 5700 ft/min and about 6700 ft/min.
23. The method as recited in claim 21 , further comprising the step of providing a burner flame with oxygen wherein about 20 percent to about 40 percent of the total oxygen is provided by the first gas through the axial zone, about 10 percent to about 30 percent of the total oxygen is provided by the second gas through the second annular zone, and about 40 percent to about 70 percent of the oxygen is provided by the third gas through the third annular zone.
24. The method as recited in claim 23 , further comprising the step of swirling at least one of the group consisting of the first gas, the second gas, the third gas, and the carrier gas prior to reaching the burner flame.
25. The method as recited in claim 23 , further comprising the steps of; combusting the pulverized coal in the carrier gas stream from the inside of the stream with the first gas, combusting the pulverized coal in the carrier gas stream from the outside with the second gas and the third gas;
providing a means for creating a recirculation zone within the burner flame; and
suppressing NOx formation and accelerating combustion by recirculation of uncombusted coal and oxygen in the burner flame.
26. The method as recited in claim 23 , further comprising the step of utilizing a flow conditioning means for conditioning gas flow within at least one of the group consisting of the axial zone, the first annular zone, the second annular zone, and the third annular zone.