JP2014145563A - Combustor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce influences of supplied water on a fuel jetted from a fuel nozzle and uniformly spread the water in compressed air.SOLUTION: A combustor 1 includes: an air passage 20 which is formed between an inner peripheral surface of a combustor outer cylinder 5 and an outer peripheral surface of a combustor inner cylinder 3; multiple fuel nozzles 8 which are provided in the combustor inner cylinder 3 and jet a fuel. In the combustor 1, a flow direction of air flowing in the air passage 20 is reversed in a reverse part 21 located at a rear end of the combustor inner cylinder 3, and then the air is introduced into the multiple fuel nozzles 8. The combustor 1 further includes a water supply part 22 which is provided before the reverse part 21 in the air passage 20 and supplies water to the air.

Description

  The present invention relates to a combustor for a gas turbine.

2. Description of the Related Art As a combustor used in a gas turbine, a dual-fired combustor capable of burning oil fuel that is liquid fuel as backup fuel is known along with gas fuel.
In the dual-type dual-fired combustor, not only oil fuel but also water is injected into the combustion cylinder, thereby reducing the flame temperature and reducing NOx (nitrogen oxide), soot, etc. (for example, patents) Reference 1). Water is mixed with fuel and supplied, or is injected from a nozzle hole provided separately. In order to sufficiently reduce NOx and soot, it is necessary to add a certain amount of water.

JP-A-6-66156

  However, by increasing the amount of water to be added, the trajectory of the fuel injected from the fuel nozzle such as the main nozzle may change, which may affect the combustion characteristics. The change in combustion characteristics leads to problems such as increased combustion vibration and increased combustor metal temperature, so the amount of water input is limited.

  The present invention has been made in consideration of such circumstances, and its purpose is to supply water or steam supplied in a combustor of a gas turbine to which water or steam is supplied in order to reduce NOx, soot and the like. An object of the present invention is to provide a combustor capable of reducing the influence of the fuel on the fuel injected from the fuel nozzle and uniformly allowing water to flow through the compressed air.

In order to achieve the above object, the present invention provides the following means.
The combustor according to the present invention includes a combustor outer cylinder, a cylindrical combustor inner cylinder provided inside the combustor outer cylinder, an inner peripheral surface of the combustor outer cylinder, and an outer peripheral surface of the combustor inner cylinder. An air flow path formed between the plurality of fuel nozzles for injecting fuel, and air flowing through the air flow path is provided at a rear end of the combustor inner cylinder. Is a combustor whose flow direction is reversed at the reversing part and introduced into the plurality of fuel nozzles, and is provided before the reversing part in the air flow path, and supplies water or steam to the air And a supply unit.

  According to the said structure, the influence which the supplied water or vapor | steam has on the fuel injected from a fuel nozzle can be made small by providing the water supply part for supplying water or a vapor | steam separately. In addition, since a sufficient distance from the water supply unit to the fuel nozzle can be secured, the compressed air can be uniformly distributed.

  The said combustor WHEREIN: It is preferable that the said water supply part is provided on the said air flow path.

In the combustor, it is preferable that the water supply unit is provided inside the combustor and at the base of the fuel nozzle.
According to the said structure, it becomes easy to adjust the inflow amount of the water to each fuel nozzle.

  In the combustor, water or steam is supplied from the fuel nozzle until the ratio W / F between the supply amount of the water or steam and the injection amount of the fuel reaches a predetermined value, and the ratio W / F is predetermined. From the above value, it is preferable to have a control unit that controls the supply amount of water or steam from the fuel nozzle to be constant and supplies water from the water supply unit.

  According to the above configuration, since water or steam is added from the fuel nozzle close to the flame up to a predetermined W / F, NOx is effectively reduced. On the other hand, since water or steam is added from the water supply unit from a predetermined W / F or higher, it is possible to suppress unexpected behavior such as an increase in combustion vibration associated with water or steam injection and an increase in metal temperature. Can do.

  In the combustor, when supplying water or steam from the water supply unit, the control unit supplies water or steam from the fuel nozzle so that a ratio between the momentum of the air and the momentum of the fuel is constant. It is preferable to control the supply amount.

  According to the said structure, the mutation of a combustion state can further be suppressed.

  According to the present invention, by separately providing the water supply unit for supplying water or steam, the influence of the supplied water or steam on the fuel injected from the fuel nozzle can be reduced. In addition, since a sufficient distance from the water supply unit to the fuel nozzle can be secured, the compressed air can be uniformly distributed.

It is sectional drawing which shows the structure inside the inner cylinder in the combustor of 1st embodiment of this invention. It is sectional drawing which shows the structure inside the inner cylinder in the combustor of 2nd embodiment of this invention. It is a graph explaining the control method of the combustor of 3rd embodiment of this invention. It is a graph explaining the control method of the combustor of 4th embodiment of this invention. It is a flowchart explaining the control method of the combustor of 4th embodiment of this invention.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings.
As shown in FIG. 1, the gas turbine combustor 1 (hereinafter simply referred to as the combustor 1) of the present embodiment is a dual type capable of oiling in addition to gas burning. The inner cylinder 3 accommodated in the inner cylinder 3, the tail cylinder 4 fitted to the inner cylinder 3, and the outer cylinder 5 that covers the outer peripheral side of the inner cylinder 3 and abuts against the inner wall of the passenger compartment 2. The tail cylinder 4 is a hollow tubular member. The inner cylinder 3 is also a hollow tubular member, and has an outer diameter slightly smaller than the inner diameter of the tail cylinder 4.

  The combustor 1 is installed at the center of the pilot nozzle 7 that performs diffusion combustion, and a plurality of the combustors 1 that are arranged at equal intervals in the circumferential direction on the outer peripheral side of the pilot nozzle 7 and that perform premixed combustion. A fuel nozzle including the nozzle 8 is provided. The combustor 1 includes a pilot cone 9 installed so as to cover the front end side of the pilot nozzle 7, a main burner 10 installed so as to cover the front end side of the main nozzle 8, an outer wall of the pilot nozzle 7, and a pilot. A pilot swirler 11 installed between the inner wall of the cone 9 and a main swirler 12 installed between the outer wall of the main nozzle 8 and the inner wall of the main burner 10 are provided.

  Further, the combustor 1 is provided with a plurality of second ribs 15 connected to the outer periphery of the inner cylinder 3 on the other side (left side in FIG. 1) of the inner cylinder 3 in the axial direction (hereinafter simply referred to as the axial direction). It has been. Further, the combustor 1 has a first rib 14 for supporting a punch metal 16 constituted by a perforated plate provided at an entrance portion to a space between the outer cylinder 5 and the inner cylinder 3 on one axial side. Is provided. By connecting the first rib 14 and the second rib 15 to the outer cylinder 5 and the inner cylinder 3, the inner cylinder 3 is supported and fixed to the outer cylinder 5.

  The main nozzle 8 is connected to a fuel pipe 19 through which water is supplied together with oil fuel. Between the inner peripheral surface of the outer cylinder 5 and the outer peripheral surface of the inner cylinder 3, an air flow path 20 through which compressed air flows is formed. The compressed air that has flowed into the air flow path 20 is turned 180 ° at the reversing portion 21 of the bottom portion of the outer cylinder 5 (the base portion of the pilot nozzle 7 and the main nozzle 8) as shown by the arrow in FIG. Supplied inside the cylinder 3.

  A plurality of water injection nozzles 22 (water supply units) for injecting water into the compressed air flowing through the air flow channel 20 are provided on the air flow channel 20 and upstream of the reversing unit 21. Yes. Specifically, the water injection nozzles 22 are arranged at equal intervals in the circumferential direction of the inner cylinder 3 and include a plurality of water injection holes 23 for injecting water.

Next, the operation of the combustor 1 of the present embodiment will be described.
First, compressed air discharged from the compressor outlet (not shown) into the vehicle compartment 2 flows into the space formed between the outer cylinder 5 and the inner cylinder 3 through the punch metal 16. The punch metal 16 plays a role of rectifying the compressed air flowing into the combustor 1 by providing a resistance by forming a perforated plate. The compressed air that has flowed into the space between the outer cylinder 5 and the inner cylinder 3 through the punch metal 16 flows along the inner wall of the outer cylinder 5. At this time, water is supplied to the compressed air from the water injection nozzle 22. Water is supplied from the water injection nozzle 22 as water droplets (liquid), but evaporates according to the temperature of the compressed air to become water vapor.
On the other hand, during the oiling operation, the supply of fuel gas to the pilot nozzle 7 and the main nozzle 8 is stopped, and oil fuel and water are supplied to each through the fuel pipe 19.

  Then, the compressed air turns 180 ° at the reversing unit 21. The compressed air and water vapor are further mixed by the vortex generated in the compressed air in the reversing unit 21. Then, compressed air containing water vapor is supplied into the inner cylinder 3. A swirl flow is given to the compressed air by the pilot swirler 11 and the main swirler 12 of the combustor 1 and is used for diffusion combustion by the pilot nozzle 7 and premixed combustion by the main nozzle 8.

According to the above embodiment, by separately providing the water injection nozzle 22 for injecting water, the influence of the supplied water on the fuel injected from the fuel nozzles 7 and 8 can be reduced.
In addition, by ensuring a sufficient distance from the water injection nozzle 22 to the fuel nozzles 7 and 8, water can be uniformly distributed in the compressed air.

  In addition, in the said embodiment, although the structure which injects water from the water injection nozzle 22 was shown, you may inject a vapor | steam (water vapor | steam) from the water injection nozzle 22. FIG.

(Second embodiment)
Next, the combustor 1 according to the second embodiment of the present invention will be described. In the present embodiment, differences from the first embodiment described above will be mainly described, and description of similar parts will be omitted.
As shown in FIG. 2, the water injection nozzle 22 of the present embodiment is provided inside the combustor outer cylinder 5 and at the base of fuel nozzles 7 and 8 having a pilot nozzle 7 and a main nozzle 8. .
The water sprayed from the water spray nozzle 22 is sprayed toward the compressed air that is reversed in the reversing unit 21.

  According to the above embodiment, the water injection nozzle 22 is provided in each of the fuel nozzles 7 and 8, so that the amount of water flowing into each of the fuel nozzles 7 and 8 can be easily adjusted.

(Third embodiment)
Next, the combustor 1 of the third embodiment of the present invention will be described. In the present embodiment, differences from the first embodiment described above will be mainly described, and description of similar parts will be omitted.
The combustor 1 of the present embodiment controls the water injection amount from the main nozzle 8 and the water injection amount from the water injection nozzle 22 according to the ratio W / F of the amount of water and the amount of fuel. It is characterized by. That is, in the combustor 1 of this embodiment, the water injection amount is controlled based on W / F by a control device (control unit) (not shown).

  Specifically, as shown in the graph of FIG. 3, the combustor 1 of the present embodiment injects water from the main nozzle 8 up to a predetermined W / F, and from the predetermined W / F or more, the water injection nozzle Control is performed so that water is ejected from 22. On the other hand, from the predetermined W / F or higher, the amount of water ejected from the main nozzle 8 is controlled to be constant.

  According to the embodiment, water is added from the main nozzle 8 close to the flame until the predetermined W / F, so that NOx is effectively reduced. On the other hand, since water is added from the water injection nozzle 22 from a predetermined W / F or higher, unexpected behavior such as an increase in combustion vibration accompanying a water injection and an increase in metal temperature can be suppressed.

(Fourth embodiment)
Next, a combustor 1 according to a fourth embodiment of the present invention will be described. In this embodiment, the difference from the above-described third embodiment will be mainly described, and the description of the same parts will be omitted.
The combustor 1 of the present embodiment controls the water injection amount from the main nozzle 8 and the water injection amount from the water injection nozzle 22 according to the ratio W / F of water and fuel, The water injection amount from the fuel nozzle is controlled so that the ratio between the momentum and the momentum of the fuel is constant.

Specifically, as shown in the graph of FIG. 4, water is injected from the main nozzle 8 until a predetermined W / F, and water is injected from the water injection nozzle 22 from a predetermined W / F or higher. Control. On the other hand, water is slightly added from the main nozzle 8 even at a predetermined W / F or more.
The ratio of the water injection amount added from the main nozzle 8 at a predetermined W / F or higher is determined by the following method.

FIG. 5 is a flowchart showing a method for determining the ratio of the amount of water injection added from the main nozzle 8 used in the control method of the combustor 1 of the present embodiment.
First, as the momentum ratio defining step S1, the momentum ratio RT that optimizes the mixing of air and fuel is defined. That is, the optimum mixing of air and fuel is limited to one condition that optimizes the momentum ratio RT, and thus the momentum ratio RT is defined in advance.

  Next, as the total addition flow rate command step S2, the total flow rate of water added to the compressed air is determined. The total flow rate of water is determined according to the specifications of the combustor 1 and the required amount of NOx reduction.

  Next, as the upstream water ratio assumption step S3, the ratio of the water injection amount added from the main nozzle 8 (upstream water ratio) is assumed. That is, at a predetermined W / F or higher, the supply amount of water from the main nozzle 8 with respect to the total flow rate of added water commanded in the total addition flow rate command step S2, and the water from the upstream water injection nozzle 22 Assuming a ratio with the amount of supply.

  Next, as the momentum calculation step S4, the momentum of fuel and water injected from the main nozzle 8 based on the upstream water ratio assumed in the upstream water ratio assumption step S3 (hereinafter referred to as fuel momentum FM) is calculated. At the same time, the momentum of compressed air containing water added from the water injection nozzle 22 (hereinafter referred to as air momentum AM) is calculated.

  The fuel momentum FM can be calculated from, for example, the flow rate measured by a flow meter provided in the fuel pipe 19 and the diameter of the main nozzle 8. The air momentum AM can be calculated using numerical values such as the rotational speed of the compressor of the gas turbine, the load, and the control state of the IGV (Inlet Guide Vane). These numerical values can be grasped from an operation map set in advance by the control device of the gas turbine.

Next, as a momentum ratio comparison step S5, a predetermined momentum ratio RT is compared with the momentum ratio RA calculated from the fuel momentum FM calculated in the momentum calculation step S4 and the air momentum AM. Here, if the calculated momentum ratio RA is equal to the prescribed momentum ratio RT, the fuel-side water ratio assumed in the upstream water ratio assumption step S3 is adopted. On the other hand, when the calculated momentum ratio RA is not equal to the prescribed momentum ratio RT, a series of steps from the upstream water ratio assumption step S3 to the momentum calculation step S4 is performed again.
The ratio of the water injection amount added from the main nozzle 8 is determined by the above steps S1 to S5. That is, the ratio of the air momentum and the fuel momentum is controlled to be constant by setting the fuel-side water ratio determined by the above steps.

  According to the above embodiment, since the water injection amount on the fuel side is adjusted so as to maintain the momentum ratio at which the mixing of air and fuel is optimal, the combustion state mutation can be further suppressed.

  In the embodiment described above, the upstream water ratio is determined while comparing the prescribed momentum ratio RT and the calculated momentum ratio RA. However, the present invention is not limited to this, and the operation created by performing the momentum calculation in advance. You may drive according to the map.

DESCRIPTION OF SYMBOLS 1 Combustor 2 Carcass 3 Inner cylinder 4 Tail cylinder 5 Outer cylinder 7 Pilot nozzle 8 Main nozzle 9 Pilot cone 10 Main burner 11 Pilot swirler 12 Main swirler 14 First rib 15 Second rib 16 Punch metal 17 Strut 19 Fuel pipe 20 Air Flow path 21 Inversion part 22 Water injection nozzle (water supply part)
23 Water injection holes

Claims (5)

A combustor barrel,
A cylindrical combustor inner cylinder provided inside the combustor outer cylinder;
An air flow path formed between an inner peripheral surface of the combustor outer cylinder and an outer peripheral surface of the combustor inner cylinder;
A plurality of fuel nozzles provided inside the combustor inner cylinder and for injecting fuel;
The combustor in which the air flowing through the air flow path is introduced into the plurality of fuel nozzles by reversing the flow direction at the reversing portion at the rear end of the combustor inner cylinder,
A combustor comprising a water supply unit that is provided before the reversing unit in the air flow path and supplies water or steam to the air.   The combustor according to claim 1, wherein the water supply unit is provided on the air flow path.   The combustor according to claim 1, wherein the water supply unit is provided inside the combustor and at a base of the fuel nozzle.   Water or steam is supplied from the fuel nozzle until the ratio W / F between the supply amount of the water or steam and the injection amount of the fuel is a predetermined value, and the ratio W / F is more than a predetermined value, The control part which controls to supply water or steam from the water supply part while making the supply amount of water or steam from the fuel nozzle constant. The combustor as described in any one of Claims.   The controller controls the supply amount of water or steam from the fuel nozzle so that the ratio of the momentum of the air and the momentum of the fuel is constant when supplying water or steam from the water supply unit. The combustor according to claim 4.

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