Bladed coal diffuser and coal line balancing device
View Patent ↗A coal nozzle assembly for a pulverized coal burner includes a diffuser. A flow conditioner also may be used with the assembly. The assembly conditions the coal/air flow before the coal/air flow is introduced to the furnace. The flow conditioner directs the coal into the diffuser where it is swirled to form a fuel rich outer ring disposed about an air rich inner portion before the fuel is delivered to the coal nozzle.
1. A coal nozzle assembly for a pulverized coal burner, the coal nozzle assembly comprising:
a coal nozzle having an upstream inlet and a downstream outlet and a longitudinal direction, the coal nozzle having a wall having an inner surface;
a diffuser positioned in the coal nozzle closer to the upstream inlet than the downstream outlet, the diffuser having a body with a tapered upstream portion, the diffuser having a plurality of blades extending outwardly from the body;
a burner elbow connected to the upstream inlet of the coal nozzle;
wherein the burner elbow defines an observation portion and the elbow comprises a flow conditioner therein, said flow conditioner resulting in a pressure drop in said elbow;
wherein the flow conditioner is adapted to direct a coal rope toward the upstream portion of the diffuser.
2. The assembly of claim 1 , wherein the outer surface of the tapered upstream portion of the body of the diffuser is smoothly curved.
3. The assembly of claim 2 , wherein the tapered upstream portion of the body of the diffuser is partially spherical.
4. The assembly of claim 3 , wherein the body of the diffuser has a downstream portion and the plurality of the blades extend from both the tapered upstream portion and the downstream portion of the body.
5. The assembly of claim 4 , wherein the tapered upstream portion has a longitudinal length and the plurality of the blades extend along at least 25 percent of the longitudinal length of the upstream portion.
6. The assembly of claim 5 , wherein at least one of the blades has a tapered upstream end.
7. The assembly of claim 1 , wherein at least one of the blades has a tapered downstream end.
8. The assembly of claim 1 , wherein at least one of the blades has parallel upstream and downstream sidewalls.
9. The assembly of claim 8 , wherein each of the sidewalls is flat.
10. The assembly of claim 8 , wherein each of the sidewalls is curved.
11. The assembly of claim 1 , wherein at least one of the blades has curved upstream and downstream sidewalls.
12. The assembly of claim 1 , wherein at least one of the blades has at least one sidewall curved away from another sidewall to define an airfoil.
13. The assembly of claim 1 , wherein the diffuser body and blades are fabricated from a ceramic metal;
wherein the diffuser has 8 to 14 blades; and
wherein the blades are positioned at an angle in the range of 16 to 45° with respect to the longitudinal direction of the coal nozzle to provide each blade with an impingement surface such that a coal and air flow passing through the diffuser will be swirled, wherein the swirling motion through coal nozzle imparts centrifugal forces on the coal particles forcing them to an outside perimeter of the coal nozzle.
14. The assembly of claim 1 , wherein the flow conditioner has a flat bottom and is mounted into a burner elbow inspection port; and
wherein the flow conditioner includes a fixed portion and an adjustable portion, the adjustable portion being selectively movable for rotation between 0° and 90° on an angle adjustment plate with respect to the burner elbow to adjust the pressure drop across the burner elbow and fuel flow.
15. A coal nozzle assembly for a pulverized coal burner, the coal nozzle assembly comprising:
a coal nozzle having an upstream inlet and a downstream outlet, the coal nozzle having a wall having an inner surface;
a burner elbow disposed upstream of the upstream inlet wherein the elbow comprises an adjustable flow conditioner therein, the adjustable flow conditioner resulting in a pressure drop in said elbow;
a diffuser positioned in the coal nozzle closer to the upstream inlet than the downstream outlet, the diffuser having a body with a tapered upstream portion, the diffuser having a plurality of angled blades extending outwardly from the body; and
the adjustable flow conditioner having a fixed portion and a moveable portion, the fixed portion being adapted to direct a coal rope into the tapered upstream portion of the diffuser and the moveable portion being selectively movable for rotation between 0° and 90° on an angle adjustment plate to adjust the pressure drop across the burner elbow.
16. The assembly of claim 15 , wherein the tapered upstream portion is semi-spherical.
17. The assembly of claim 15 , wherein the body of the diffuser has a downstream portion; the plurality of the blades extending from both the tapered upstream portion and the downstream portion of the body.
18. The assembly of claim 15 , wherein the tapered upstream portion has a longitudinal length; a plurality of the blades extending along at least 25 percent of the longitudinal length of the upstream portion.
19. The assembly of claim 15 , wherein at least one of the blades has a tapered downstream end.
20. The assembly of claim 15 , wherein at least one of the blades has parallel upstream and downstream sidewalls.
21. The assembly of claim 15 , wherein at least one of the blades has curved upstream and downstream sidewalls.
22. The assembly of claim 15 , wherein at least one of the blades has at least one sidewall curved away from another sidewall to define an airfoil.
23. The assembly of claim 15 , wherein the diffuser has 8 to 14 blades, the blades being angled at an angle in the range of 16 to 45° with respect to the longitudinal direction of the coal nozzle, the blades being adapted to spin a flow of air and coal, wherein the spinning motion through coal nozzle imparts centrifugal forces on the coal particles forcing them to an outside perimeter of the coal nozzle.
24. The assembly of claim 15 , wherein the adjustable flow conditioner has a flat bottom and is mounted into a burner elbow inspection port.
25. The assembly of claim 15 , wherein adjusting the pressure drop through the coal nozzle assembly allows the delivery of primary air/pulverized coal flow to be adjusted.