METHOD AND BURNER ASSEMBLY FOR COMBUSTING A FUEL GAS WITH AN OXIDANT

Abstract

The invention relates to a method for combusting a fuel gas with an oxidant by using a burner assembly (10) comprising a burner (12) and a lance (14), the method comprising providing via the burner (12) a main gas flow to a combustion, wherein the main gas flow comprises a main part of the fuel gas and a first part of the oxidant. Further, the method comprises providing via the lance (14) a staging gas flow to the combustion, wherein the staging gas flow comprises a second part of the oxidant and an auxiliary part of the fuel gas. The main part of the fuel gas is larger than the auxiliary part of the fuel gas. Furthermore, the invention relates to a burner assembly (10) and a furnace comprising such.

Claims

1-14. (canceled)

15. A method for combusting a fuel gas with an oxidant by using a burner assembly (10) comprising a burner (12) and a lance (14), the method comprising: providing via the burner (12) a main gas flow to a combustion, wherein the main gas flow comprises a main part of the fuel gas and a first part of the oxidant; and providing via the lance (14) a staging gas flow to the combustion, wherein the staging gas flow comprises a second part of the oxidant and an auxiliary part of the fuel gas; wherein the main part of the fuel gas is larger than the auxiliary part of the fuel gas, and wherein the auxiliary part of the fuel gas provided via the lance is selected from the group consisting of not more than 20% of the total fuel gas provided to the combustion, not more than 10% of the total fuel gas provided to the combustion, not more than 5% of the total fuel gas provided to the combustion, and not more than 2% of the total fuel gas provided to the combustion.

16. The method according to claim 15, wherein the auxiliary part of the fuel gas preheats at least a part of the staging gas flow before the staging gas flow is provided to the combustion.

17. The method according to claim 15, wherein the first part of the oxidant provided via the burner (12) is selected from the group consisting of not more than 95% of the total oxidant provided to the combustion, not more than 90% of the total oxidant provided to the combustion, not more than 80% of the total oxidant provided to the combustion, not more than 70% of the total oxidant provided to the combustion, and not more than 60% of the total oxidant provided to the combustion.

18. The method according to claim 15, wherein the second part of the oxidant provided via the lance (14) is selected from the group consisting of at least 5% of the total oxidant provided to the combustion, at least 10% of the total oxidant provided to the combustion, at least 20% of the total oxidant provided to the combustion, at least 30% of the total oxidant provided to the combustion, and at least 40% of the total oxidant provided to the combustion.

19. The method according to claim 15, wherein the burner assembly (10) comprises a plurality of burners (12) for providing the main gas flow to the combustion, and a burner block (16) comprising multiple outlet areas (28, 30) for ejecting at least a part of the combusted fuel gas and at least a part of the oxidant.

20. The method according to claim 15, wherein the burner assembly (10) comprises a plurality of lances (14), wherein each of the plurality of lances (14) provides one of a plurality of staging gas flows to the combustion.

21. The method according to claim 15, wherein an amount of the auxiliary part of the fuel gas in the staging gas flow is adjustable.

22. A burner assembly (10) for combusting a fuel gas with an oxidant, the burner assembly (10) comprising: a burner (12) for providing a main gas flow to a combustion, wherein the main gas flow comprises a main part of the fuel gas and a first part of the oxidant; a lance (14) for providing a staging gas flow to the combustion, wherein the staging gas flow comprises a second part of the oxidant and an auxiliary part of the fuel gas; and an injection element for injecting the auxiliary part of the fuel gas to the second part of the oxidant before providing the staging gas flow to the combustion via the lance (14); wherein the main part of the fuel gas is larger than the auxiliary part of the fuel gas, and wherein the auxiliary part of the fuel gas provided via the lance is selected from the group consisting of not more than 20% of the total fuel gas provided to the combustion, not more than 10% of the total fuel gas provided to the combustion, not more than 5% of the total fuel gas provided to the combustion, and not more than 2% of the total fuel gas provided to the combustion.

23. The burner assembly (10) according to claim 22, further comprising control means for adjusting an amount of the auxiliary part of the fuel gas in the staging gas flow.

24. The burner assembly (10) according to claim 22, wherein the burner assembly comprises a plurality of the burners (12) for providing the main gas flow to the combustion, and a burner block (16) comprising multiple outlet areas (28, 30) for ejecting at least a part of the combusted fuel gas and at least a part of the oxidant.

25. The burner assembly (10) according to claim 22, further comprising an outlet area (28, 30) of the burner block (16) for the fuel gas and for the lance (14), the outlet area including a substantially rectangular shape, wherein the outlet area (28, 30) includes a ratio of its width to its height selected from the group consisting of at least 3:1, at least 4:1, at least 5:1, at least 6:1, and at least 6.5:1.

26. The burner assembly (10) according to claim 22, further comprising a plurality of the lances (14), wherein each of the plurality of the lances (14) is adapted to provide one of a plurality of staging gas flows to the combustion.

27. The burner assembly according to claim 22, wherein the burner (12) comprises a flat flame burner.

28. A furnace comprising the burner assembly (10) according to claim 22.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0031] FIG. 1 depicts a burner assembly according to a preferred embodiment.

DETAILED DESCRIPTION OF THE DRAWINGS

[0032] FIG. 1 shows a burner assembly 10 comprising a burner 12 for providing a fuel gas to a combustion in a furnace, a lance 14 for providing an oxidant to the combustion and a burner block 16. The burner block 16 may be made from stone, such as fireclay, and may be used for installing the burner assembly 10 into a furnace while preventing in particular the burner 12 and the lance 14 of being exposed to the high temperatures typically prevailing inside the furnace.

[0033] The burner assembly 10 comprises further a main fuel gas inlet 18 for supplying fuel gas to the burner 12 as a main part of the fuel gas in the main gas flow. In addition, an oxidant inlet 20 is provided for supplying the burner 12 with the first part of the oxidant to be ejected from the burner 12 together with the residual fuel gas. In addition, a further oxidant injector 22 is provided, which allows injecting a further part of the oxidant into the main gas flow into the burner, wherein the further part of oxidant injected via the oxidant injector 22 may be used for precombusting and/or preheating the main gas flow and in particular the fuel gas supplied to the burner 12 via the fuel gas inlet 18. Since typically the volume and/or amount of the further oxidant injected via the oxidant injector 22 is considerably smaller than the amount and/or volume of fuel gas supplied to the burner 12 via the fuel gas inlet 18, the diameter of the oxidant injector 22 is significantly smaller than the diameter of the fuel gas inlet 18.

[0034] The lance 14 is equipped with an oxidant inlet 24, for supplying the lance 14 with oxidant, and with a fuel gas injector 26 (partly covered by the oxidant inlet 20 of the burner 12) having a smaller diameter than the oxidant inlet 24. The fuel gas injector 26 allows injecting an auxiliary part of the fuel gas into the lance 14 for precombusting and/or preheating the staging gas flow and in particular the oxidant provided to the combustion via the lance 14.

[0035] Accordingly, the burner 12, as well as the lance 14, are both supplied with fuel gas and with oxidant to allow a precombustion and/or a preheating of the main gas flow in the burner 12 and of the staging gas flow in the lance 14, respectively.

[0036] The burner block 16 according to the depicted embodiment is formed of stone, in particular of fireclay, which is adapted to sustain high temperatures prevailing in the furnace to which the burner assembly is to be connected or into which the burner block is to be integrated, which may be for instance between 1,000 C. and 2,000 C. Due to the burner block 16, the components, which are less sustainable to such high temperatures, such as the burner 12, the lance 14 and/or supply tubes, are protected from being exposed to the heat prevailing in the furnace. While the burner block 16 is formed from solid stone, it comprises channels for conducting the main gas flow and the staging gas flow, and which connect the burner 12 with a main gas flow outlet area 28 and the lance 14 with a staging gas outlet area 30, respectively.

[0037] The main gas flow outlet area 28 and also the staging gas flow outlet are 30 have essentially a rectangular shape, wherein for both outlet areas the width, i.e. its dimensions in horizontal direction, is significantly larger than the height. According to the depicted embodiment, the main gas flow outlet area 28 has a ratio of its width to its height of 6.9:1, which allows a broad, sheet-like distribution of the main gas flow exiting the main gas flow outlet area 28. The staging gas flow outlet area 30 has a ratio of 7.1:1, which also allows a broad, sheet-like distribution of the staging gas flow when exiting the staging gas flow outlet area 30. By this, a broad (in horizontal direction) and thin (in vertical direction) combustion zone and/or flame can be provided at the outlet side 16a of the burner block. Due to the injection of the auxiliary fuel gas into the lance, a high velocity of the staging gas flow and, hence, a deep penetration of the staging gas flow can be obtained, which consequently allows a deep penetration of the combustion zone and/or the flame into the furnace.

REFERENCE SIGNS

[0038] 10 burner assembly [0039] 12 burner [0040] 14 lance [0041] 16 burner block [0042] 16a outlet side (of the burner block) [0043] 18 fuel gas inlet (of the burner) [0044] 20 oxidant inlet (of the burner) [0045] 22 oxidant injector (of the burner) [0046] 24 oxidant inlet (of the lance) [0047] 26 fuel gas injector (of the lance) [0048] 28 main gas flow outlet area [0049] 30 staging gas flow outlet area