COMBUSTION PLANT AND METHOD FOR OPERATING A COMBUSTION PLANT

Abstract

A special distribution of nozzles in the flue gas outlet and their alignment make it possible to guide the flue gas along a wavy line. The addition of combustion air for primary air and secondary air can be variably distributed during operation of the combustion plant, for example so as to also keep the burnout per unit of time constant while maintaining a constant combustion air ratio.

Claims

1. A combustion plant with a flue gas outlet, which has nozzles on opposing sides of the flue gas outlet, so as to inject a fluid into the flue gas, wherein the nozzles are arranged and aligned in such a way as to move the flue gas in the flue gas outlet back and forth along a wavy line.

2. The combustion plant according to claim 1, wherein the fluid is a gas.

3. The combustion plant according to claim 2, wherein the gas is air.

4. The combustion plant according to claim 2, wherein the gas is steam.

5. The combustion plant according to claim 1, wherein the wavy line has three, and preferably more than four reversal points.

6. The combustion plant according to claim 1, wherein the primary nozzle direction of the two nozzles arranged on opposing sides of the flue gas outlet lies at an angle of at least 5, preferably of more than 10, from a line connecting the nozzles.

7. The combustion plant according to claim 1, wherein the primary nozzle direction of a nozzle deviates from the shortest connection to the opposing side of the flue gas outlet by an angle of at least 5, preferably of more than 10.

8. The combustion plant according to claim 1, wherein the primary nozzle direction of at least one nozzle deviates from a horizontal plane in the flue gas outlet by an angle of at least 5, preferably of more than 10.

9. The combustion plant according to claim 1, wherein the combustion plant has a furnace grate for combustion.

10. The combustion plant according to claim 9, wherein the flue gas outlet of the furnace grate expands in the direction of flow of the flue gas.

11. The combustion plant according to claim 9, wherein the flue gas outlet has a lower area and an upper area, wherein the access from the furnace grate to the flue gas outlet in the lower area is arranged offset to the upper area.

12. The combustion plant according to claim 9, wherein at least one nozzle is arranged above the furnace grate in the direction of flow of the flue gas before the flue gas outlet, so as to inject fluid into the flue gas.

13. A method for operating a combustion plant according to claim 1, in which at least a portion of the combustion air is added to the flue gas through nozzles arranged on opposing sides of the flue gas outlet, wherein the combustion air is added as primary combustion air and secondary combustion air or as secondary combustion air during operation of the combustion plant at several varyingly different addition points.

14. The method according to claim 13, wherein the combustion air ratio is held constant.

15. The method according to claim 13, wherein the combustion air is added distributed to the nozzles and grate.

16. The method according to claim 13, wherein the distribution of partial volume flows to these nozzles is controllably varied.

17. The method according to claim 13, wherein, during operation of the combustion plant, the combustion air is distributed to the individual addition points optimized for NO.sub.x, CO and/or O.sub.2.

18. The method according to claim 13, wherein the distribution of combustion air is split among the nozzles in the flue gas outlet in such a way as to achieve a nearly constant burnout (gas and/or solid burnout) per unit time.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] An advantageous exemplary embodiment is shown on the drawing, and will be explained in more detail below. Shown on:

[0028] FIG. 1 is a schematic view of the arrangement of fluid addition points on a combustion plant, and

[0029] FIG. 2 is a schematic view of a wavy line of flue gases in a flue gas outlet.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] The combustion plant 1 shown on FIG. 1 has a furnace grate 2 and a flue gas outlet 3. The arrows 4 denote the addition of primary air at the furnace grate 2, and the arrows 5 to 9 denote the addition of secondary air via nozzles. The nozzles 10 to 14 are only schematically denoted. The nozzle 10 is here arranged above the furnace grate 2, and the nozzles 11 and 12 are arranged on a side 15 of the flue gas outlet 3, while the nozzles 13 and 14 are arranged on the opposing side 16 of the flue gas outlet 3.

[0031] The dotted lines 17 to 21 denote the primary nozzle direction of the nozzles 10 to 14.

[0032] With respect to the primary nozzle direction 17, the angle 22 shows the alignment relative to a line 23 connecting the nozzles 12 and 14. The angle 24 shows the alignment of the primary nozzle direction 17 in relation to the shortest connection 25 of the nozzle 14 to the opposing side 15 of the flue gas outlet 3. Finally, the angle 26 shows the primary nozzle direction 17 of the nozzle 14 in relation to a horizontal plane 27 in the flue gas outlet 3.

[0033] The two opposing sides 15 and 16 of the flue gas outlet 3 are at an angle 28 to each other, so that the flue gas outlet 3 conically expands in the area between the access 29 to the flue gas outlet 3 and a transition 30 to perpendicular sides 31 and 32 of the flue gas outlet 3.

[0034] This results in a lower area 33 of the flue gas outlet 3 between the access 29 from the furnace grate 2 to the flue gas outlet 3 and the transition 30 from the area 33 of the flue gas outlet 3 with the inclined sides 15, 16 to the area 34 of the flue gas outlet with perpendicular walls 31 and 32, which is offset relative to this second area 34 between the perpendicular walls 31 and 32.

[0035] The nozzle 10 with its primary nozzle direction 21 is arranged on a wall 35 lying opposite the furnace grate 2, and thus lies in an area 36 above the furnace grate 2 and before the entry into the lower area 33.

[0036] During operation of the combustion plant 1, the nozzles 10 to 14 generate a wavy line 37 of flue gas 38, which arises on the furnace grate 2. Adding secondary combustion air 39 to 43 as the gas to the flue gas 38 produces the wavy line 37 with its reversal points 44 to 48. The primary combustion air 49 is supplied to the combustion plant 1 via the grate 2.

[0037] This makes it possible to add the combustion air in such a way that the flue gas 38 flows on the wavy line 37. A preferred method additionally provides that either the secondary combustion air 39 to 43 or the primary combustion air 49 and the secondary combustion air 39 to 43 be added distributed among the different addition points on the grate 2 or on the nozzles 10 to 14 in varying quantities as a volume flow or mass flow during operation of the combustion plant. The combustion air ratio can here vary during operation of the combustion plant. However, it is advantageous for the combustion air ratio to be held constant.

[0038] Sensors 50, 51 and 52 for NO.sub.x, CO and/or O.sub.2 are connected with a controller 53, so as to optimize the distribution of combustion air comprised of primary combustion air 49 and secondary combustion air 39 to 43 to the individual addition points.

[0039] The burnout can be determined from the measured values ascertained with the sensors 50 to 52, making it possible to adjust the distribution of combustion air to the nozzles so that the burnout per unit time remains nearly constant.