JP7167772B2 - combustor - Google Patents

Description

The present invention relates to combustors.

For example, Patent Literature 1 discloses a combustor aiming at low NOx. In Patent Document 1 as described above, low NOx is realized by suppressing thermal NOx generated by oxidation of nitrogen in the air by a high-temperature flame during combustion.

JP 2004-28352 A

By the way, it is currently proposed to co-combust ammonia, which does not emit CO2, with natural gas as a fuel. On the other hand, natural gas generates a large amount of thermal NOx when burned in a state where there is a lot of oxygen in the surroundings, ie, a state where the equivalence ratio is high. Therefore, it is preferable to burn natural gas with a low equivalence ratio even when co-firing with ammonia. However, ammonia generates a large amount of ammonia-derived fuel NOx if it is burned in a state where there is little oxygen in the surroundings, that is, in a state where the equivalence ratio is low. Therefore, it is difficult to suppress the generation of NOx in the combustion of both ammonia and natural gas by controlling the amount of oxygen supplied.

SUMMARY OF THE INVENTION An object of the present invention is to reduce NOx generated by combustion of ammonia in a combustor for co-firing natural gas and ammonia.

As a first means for solving the above problems, the present invention provides a combustor comprising a burner for supplying gaseous ammonia and a combustor liner in which the burner is installed and a combustion chamber is formed. and an ammonia injection nozzle that is connected to the burner and that injects ammonia in a gaseous state toward the inner wall of a tube of the burner, and the burner is provided upstream of the ammonia injection nozzle. A configuration is adopted in which combustion air is supplied.

As a second means, a configuration is adopted in which a natural gas burner for supplying natural gas is provided in the first means.

As a third means, in the first means, the burner is supplied with natural gas upstream of the ammonia injection nozzle.

As a fourth means, in any one of the first to third means, an ammonia burner adjacent to the discharge port of the burner and supplying ammonia is further provided.

According to the present invention, the ammonia injected from the ammonia injection nozzle increases the pressure in the burner and obstructs the flow of combustion air, so that the amount of combustion air is small with respect to ammonia, and the equivalence ratio can be supplied to the combustion chamber with a high Therefore, at the time of co-firing with ammonia, the flow rate of combustion air can be adjusted by the flow of ammonia, and it is possible to reduce fuel NOx due to ammonia.

1 is a schematic cross-sectional view of a combustor according to a first embodiment of the present invention; FIG. FIG. 5 is a schematic cross-sectional view of a combustor according to a second embodiment of the present invention; FIG. 6 is a schematic cross-sectional view of a combustor according to a third embodiment of the present invention;

An embodiment of a combustor according to the present invention will be described below with reference to the drawings.

[First embodiment]
A combustor 1 according to this embodiment is provided in a gas turbine (not shown). The gas turbine includes a compressor, turbine and combustor 1 (not shown). The gas turbine compresses air taken in from outside air to a predetermined pressure in the compressor to generate compressed air, and burns fuel in the combustor 1 using the compressed air as an oxidant. Further, the gas turbine generates rotational power by rotating the turbine using a flow of combustion gas generated by burning fuel.

As shown in FIG. 1, the combustor 1 includes a combustor liner 2, a burner 3, an ammonia injection nozzle 4, and a casing (not shown).

The combustor liner 2 is housed inside a casing (not shown) and is a bottomed cylindrical body having an upstream wall portion 2a and a cylindrical peripheral wall portion 2b joined to the upstream wall portion 2a. A combustion chamber N is a space defined by the upstream wall portion 2a of the combustor liner 2 and the inside of the peripheral wall portion 2b. Inside the combustion chamber N, combustion air and fuel flow along the central axis of the peripheral wall portion 2b. Cooling air is supplied along the inner peripheral surface of the combustor liner 2, and a cooling air layer is formed in the vicinity of the inner peripheral surface. Combustion air is taken in and a combustion air flow path is formed between the combustor liner 2 and the casing. The combustion air flow path flows toward the upstream wall portion 2a.

The burner 3 is fixed with its discharge port side end inserted into the upstream wall portion 2 a of the combustor liner 2 . The burner 3 is connected to a supply tank (not shown) and a combustion air flow path, and injects a mixture of natural gas and combustion air supplied from the supply tank into the combustion chamber N. The diameter of the burner 3 is reduced on the upstream side, and the shape of the burner 3 is set so that the pipe diameter on the upstream side is larger than that on the downstream side. Natural gas and combustion air enter the burner 3 upstream of the reduced diameter portion of the burner 3 . Furthermore, an ammonia injection nozzle 4 is connected to the burner 3 in the vicinity of the discharge port, which is a portion with a reduced diameter. In the vicinity of the discharge port of this burner 3, a flame is formed by burning natural gas and ammonia.

The ammonia injection nozzle 4 has a discharge port inserted into the burner 3 and is connected upstream to an ammonia vaporizer (not shown). The ammonia injection nozzle 4 injects ammonia so that the gaseous ammonia hits the inner wall of the tube of the burner 3 .

The operation of such a combustor 1 will be described with reference to FIG.
In the combustor 1, natural gas and combustion air are supplied to the combustion chamber N from the burner 3 in the natural gas mono-firing state. Combustion in the combustor 1 is performed by igniting while the combustion air and the natural gas are mixed. The equivalence ratio between combustion air and natural gas is set to a low state, ie, a state in which a large amount of combustion air is supplied.

When co-firing ammonia, the ammonia injection nozzle 4 injects ammonia into the burner 3 through which natural gas and combustion air flow. At this time, in the burner 3, the pipe internal pressure rises due to the flow of ammonia. Therefore, the ammonia inhibits the discharge of natural gas and combustion air, and the mixture discharged from the burner 3 has a high ratio of ammonia and a low ratio of combustion air and natural gas. As a result, in the combustion chamber N, ammonia and combustion air are combusted with a high equivalence ratio. Moreover, at this time, the natural gas is supplied upstream of the ammonia, and the ratio of the natural gas and the combustion air does not change before and after the injection of the ammonia. Therefore, the natural gas is in a state of low equivalence ratio with respect to the combustion air, similar to the natural gas mono-firing state.

According to this embodiment, when co-firing ammonia, by injecting ammonia from the ammonia injection nozzle 4 toward the inner wall of the burner 3 tube, the flow of combustion air is obstructed, and ammonia and combustion It is possible to make the equivalence ratio with the operating air high. Therefore, at the time of co-firing with ammonia, the flow rate of combustion air can be adjusted by the flow of ammonia, and it is possible to reduce fuel NOx due to ammonia.
In addition, by injecting ammonia into the combustion air to form a premixed gas, it is possible to prevent partial uneven concentration of ammonia in the combustion chamber N.

Further, according to this embodiment, natural gas is supplied to the burner 3 together with the combustion air. As a result, when the natural gas is exclusively burned, the natural gas and the combustion air can be premixed with a low equivalence ratio, and NOx can be reduced even when the natural gas is exclusively burned. . Further, by supplying a large amount of combustion air during mono-fuel combustion of natural gas, it is possible to prevent the combustor from becoming small.

[Second embodiment]
Next, a modification of the first embodiment will be described as a second embodiment with reference to FIG. In addition, about the structure same as 1st Embodiment, the code|symbol is made the same and description is abbreviate|omitted.

The combustor 1A according to the present embodiment includes a combustor liner 2A and a plurality of annularly arranged ammonia burners 3A instead of the combustor liner 2 and the burner 3, and a plurality of annularly arranged natural gas burners 5. , and a rectifier 6, which is an annular combustor.

An annular combustion chamber N is formed inside the combustor liner 2A, and discharge ports of the ammonia burner 3A and natural gas burner 5 are alternately arranged on the upstream wall portion 2a. . Further, the combustion air flow path flows along the outer periphery of the combustor liner 2A toward the upstream wall portion 2a and is divided into two directions, one flowing to the ammonia burner 3A and the other to the rectifier 6.

The ammonia burner 3A supplies combustion air to the combustion chamber N and ammonia supplied from an ammonia injection nozzle 4 inserted from the side.
The natural gas burner 5 injects natural gas stored in a supply tank (not shown) into the combustion chamber N in a gaseous state.
The rectifier 6 is annularly provided near the discharge port of the natural gas burner 5 . The rectifier 6 supplies combustion air from the gap between the insertion opening of the upstream wall portion 2 a and the natural gas burner 5 .

In such a combustor 1A, natural gas is supplied from the natural gas burner 5 and combustion air is supplied from the vicinity of the natural gas burner 5 during natural gas only combustion. At this time, a large amount of combustion air is supplied so that the natural gas has a low equivalence ratio. During co-firing, while natural gas is being burned in the natural gas burner 5, combustion air is supplied to the ammonia burner 3A, and ammonia is injected from the ammonia injection nozzle 4 onto the inner wall of the tube of the ammonia burner 3A. do. As a result, in the ammonia burner 3A, the flow of combustion air is obstructed by ammonia, and ammonia is supplied to the combustion chamber N in a state having a high equivalence ratio with respect to the combustion air. During the co-combustion of ammonia, the NOx concentration of the exhaust gas is measured at the exit side of the combustor liner 2A, and each flow rate of the combustion air is controlled by a control device (not shown).

According to this embodiment, the equivalence ratio between ammonia and combustion air can be kept high by the ammonia injection nozzle 4 . Therefore, at the time of co-firing with ammonia, the flow rate of combustion air can be adjusted by the flow of ammonia, and it is possible to reduce fuel NOx due to ammonia.

In addition, in this embodiment, since the natural gas burner 5 is provided separately, it becomes easy to control the flow rate of the combustion air for each fuel, and the equivalence ratio of the natural gas burner 5 can be appropriately maintained even during co-firing with ammonia. Easy.

[Third embodiment]
Next, a modification of the first embodiment will be described as a third embodiment with reference to FIG. In addition, about the structure same as 1st Embodiment, the code|symbol is made the same and description is abbreviate|omitted.

The combustor 1B according to this embodiment further includes an ammonia burner 7 . The ammonia burner 7 is provided so as to surround the burner 3 . That is, the burner 3 and the ammonia burner 7 have a double tube structure. Gas state ammonia is supplied to the combustion chamber N of the ammonia burner 7 .

In such a combustor 1B, the ammonia injected from the ammonia injection nozzle 4 inhibits the discharge of natural gas and combustion air, and the mixture discharged from the burner 3 has a large proportion of ammonia and is used for combustion. A small proportion of air and natural gas is assumed. Further, gaseous ammonia is discharged from the ammonia burner 7 . The air-fuel mixture discharged from the burner is mixed with the ammonia discharged from the ammonia burner 7, resulting in a state with a higher concentration of ammonia. As a result, it is possible to sufficiently supply ammonia and to burn ammonia in a high equivalence ratio.

Although the preferred embodiments of the present invention have been described above with reference to the drawings, the present invention is not limited to the above embodiments. The various shapes, combinations, and the like of the constituent members shown in the above-described embodiment are merely examples, and can be variously changed based on design requirements and the like without departing from the gist of the present invention.

In the above embodiment, natural gas and ammonia are supplied from the upstream wall portion 2a side, respectively, but the present invention is not limited to this. For example, when separate burners are used for natural gas and ammonia, the ammonia burner may be arranged downstream of the natural gas burner in the combustion chamber N, that is, the ammonia burner may be arranged on the peripheral wall portion 2b. In this case, ammonia can be burned under more suitable conditions.

In either type of combustor, natural gas and ammonia may be discharged from the same burner into the combustion chamber N, or may be discharged from separate burners.

The present invention is also applicable to multi-nozzle burners. In this case, natural gas and ammonia may be separated for each nozzle.

Further, in the third embodiment, the ammonia burner 7 and the burner 3 have a double-tube structure, but the present invention is not limited to this. For example, the ammonia burner 7 may be arranged near the burner 3 .

1, 1A, 1B combustors 2, 2A combustor liner 2a upstream wall portion 2b peripheral wall portion 3 burner 3A ammonia burner 4 ammonia injection nozzle 5 natural gas burner 6 rectifier 7 ammonia burner N combustion chamber

Claims (3)

A combustor comprising a burner for supplying gaseous ammonia and a combustor liner in which the burner is installed and a combustion chamber is formed inside,
An ammonia injection nozzle that is connected to the burner and that injects gaseous ammonia toward the inner wall of the burner tube,
Combustion air is supplied to the burner upstream of the ammonia injection nozzle ,
A combustor , wherein the burner is supplied with natural gas upstream of the ammonia injection nozzle . 2. The combustor of claim 1, comprising a natural gas burner supplying natural gas. 3. The combustor according to claim 1 , further comprising an ammonia burner adjacent to the discharge port of said burner and supplying ammonia .

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