JPH08261465A - Gas turbine - Google Patents

Abstract

PURPOSE: To make possible low NOx combustion using a lean mixture of both gaseous and liquid fuels by leading a flow of gaseous fuel into a first annular passageway and mixing it with compressed air and leading a flow of liquid fuel into a second annular passageway and mixing it with compressed air. CONSTITUTION: A primary preliminary-mixing passageway is composed of first and second annular passageways 90, 92 which divide an inflow of air into two flows 8', 8". The first passageway 90 has a radially directed upstream part and an axially directed downstream part. The upstream part of the second passageway 92 is placed on the downstream side, in the direction of the axis, of the upstream part of the first passageway 90. The downstream part of the second passageway 92 encloses the downstream part of the first passageway 90. A flow of gaseous fuel 16' is led into the first passageway 90 and mixed with compressed air flowing therein. A flow of liquid fuel 14' is led into the second passageway 92 in a state of spray and mixed with compressed air flowing in the second passageway 92. A lean mixture of the gaseous/liquid fuels is produced short of a primary combustion zone 36.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to gas turbine combustors for burning both liquid and gaseous fuels (gaseous fuels) in compressed air. In particular, the present invention relates to low NO _x combustor having the capability of burning liquid and gaseous fuels both lean (lean) mixture.

[0002]

In a gas turbine, fuel is combusted in compressed air produced by a compressor in one or more combustors. Conventionally, this type of combustor typically has a primary combustion zone in which an approximately stoichiometric mixture of fuel and air is formed and burned in a diffusion combustion process. Fuel is introduced into the primary combustion zone via a centrally located fuel nozzle. When operating with liquid fuel, the nozzle atomizes the liquid fuel into the compressed air so that the fuel atomizes before entering the primary combustion zone. Additional air is introduced into the combustor downstream of the primary combustion zone such that the overall air / fuel ratio is significantly less than the stoichiometric air / fuel ratio, ie lean. Thus, despite the use of lean air-fuel ratios, due to the locally rich nature of the air-fuel mixture in the primary combustion zone,
It was easily ignited at start-up, and good flame stability was achieved over a wide range of ignition temperatures.

Unfortunately, conventional combustors experience very high temperatures when using rich air-fuel mixtures in the primary combustion zone. That is, when a high temperature occurs,
Nitrogen oxides (NO _x ) considered to be air pollutants
Formation is promoted. The combustion of a thin or lean air-fuel ratio, it is known to reduce the formation of such a NO _x. However, to achieve such a lean mixture, a wide distribution of fuel in the combustion air and a very good mixing is required. This requirement can be achieved by premixing the fuel into the compressed air prior to its introduction into the fuel zone.

In the case of gas or gaseous fuels, the premixing introduces fuel into the primary and secondary annular passages and premixes the fuel and air in these passages to produce the resulting premixed air-fuel mixture. The above requirements can be achieved by directing to the primary and secondary combustion zones respectively. In this case, the gaseous fuel is introduced into these primary and secondary premixing passages by means of fuel spray tubes distributed around the periphery of each of the primary and secondary premixing passages. As this type of combustor, "American Society of Mechanical Engineers (American Socie
ty of Mechanical Engineers ”(May 1993), J. Willis et al.'s paper“ Industrial RB211 Dry Low Emission Combustio ”.
n) ”is disclosed.

However, this type of conventional combustor
Unfortunately, it can only operate on gaseous fuel.
This is because the fuel spray tubes are not adapted to spray liquid fuel into the combustor. However, liquid fuel spray nozzles such as are used in devices for burning conventional rich air-fuel mixtures are known. However,
Sufficient mixing of fuel and air to achieve a sufficiently thin or lean air-fuel ratio cannot be achieved by simply providing a liquid fuel spray nozzle as described above in the premix passage. The reason for this is that known liquid fuel atomizing nozzles of this kind cannot completely atomize the fuel, resulting in the formation of large fuel droplets or locally rich air-fuel mixtures. Because it will be.

Thus, there is obtained a combustor for a gas turbine having primary and secondary passages for premixing gaseous fuel with combustion air, which is also capable of premixing liquid fuel in at least one gas premixing passage. If so, that is desirable.

[0007]

Accordingly, it is a general object of the present invention to provide a primary and premixed gaseous fuel to compressed air which is capable of premixing liquid fuel in at least one gas premixing passage. It is to provide a combustor for a gas turbine having a secondary passage.

[0008]

SUMMARY OF THE INVENTION In summary, the above and other objects of the present invention include a gas having a compressor portion for producing compressed air and a combustor for heating the compressed air. Achieved in the turbine. The combustor has a primary combustion zone and first and second concentric cylindrical liners arranged around the primary combustion zone. The first liner surrounds the second liner and forms between them an annular passage in flow or fluid communication with the compressed air section, whereby compressed air is contained in the annular passage. Can flow through. The combustor also has first and second fuel introduction means. First
Of the fuel introducing means introduces the gaseous fuel into the annular passage, whereby the gaseous fuel is mixed with the compressed air flowing in the annular passage. The second fuel introducing means introduces the liquid fuel into the annular passage, whereby the liquid fuel is mixed with the compressed air flowing in the annular passage.

In a preferred embodiment of the present invention, the second fuel introducing means includes (i) means for discharging the liquid fuel in the form of spray, and (ii) introducing the liquid fuel spray into the annular passage. Before expanding the liquid fuel spray. The spray expansion means comprises an expansion passage having a first portion in which the liquid fuel spray discharge means is arranged and a second portion connected to the annular passage.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic diagram of the gas turbine 1. The gas turbine 1 comprises a compressor 2 driven by a turbine 6 via a shaft 26. The ambient air 12 is sucked into the compressor 2 and compressed. The compressed air 8 generated by the compressor 2 includes one or more combustors 4 and fuel nozzles for introducing both gaseous fuel 16 and oil fuel 14 into the combustors.
18 to a combustion system comprising. As is customary, the gaseous fuel 16 can be natural gas and the liquid fuel 14
Could be No. 2 deal oil, however, other gaseous or liquid fuels could also be used. In the combustor 4, the fuel is combusted in the compressed air 8, which produces a hot compressed gas 20.

Hot compressed gas 20 produced by the combustor 4
Is sent to the turbine 6 where it is expanded and the compressor 2
In addition, a shaft driving force or torque for driving a load such as the generator 22 is generated. The expanded gas 24 produced in the turbine 6 is discharged directly into the atmosphere or, in the case of combined cycle plants, sent to a heat recovery steam generator and then discharged into the atmosphere.

FIG. 2 shows a combustion portion of the gas turbine 1.
A plurality of combustors 4 (only one of which is shown in FIG. 2) arranged in the circumferential direction are arranged in the cross-flame tube shown in FIG.
They are connected to each other by a flame tube) 82 and are arranged in the chamber 7 formed by the body or outer shell 22. Each combustor has a primary portion 30 and a secondary portion 32.
The hot gas 20 flowing out of the secondary part 32 is sent to the turbine part 6 via the duct 5. The primary part 30 of the combustor 4 is a support plate
Supported by 28. The support plate 28 is fixed to the cylinder 13 extending from the outer shell 22 and surrounding the primary portion 30. The secondary portion 32 is supported by eight arms (not shown) extending from the support plate 28. In this way, by individually supporting the primary portion 30 and the secondary portion section 32, the thermal stress due to the difference in thermal expansion is reduced.

The combustor 4 has a combustion zone having a primary and a secondary part. Referring to FIG. 3, the primary combustion zone portion 36 of the combustion zone in which a lean mixture of fuel and air is burned is provided within the primary portion 30 of the combustor 4. More specifically, the primary combustion zone 36
Is surrounded by a cylindrical inner liner 44 of the primary portion 30. The inner liner 44 is a cylindrical intermediate liner.
It is surrounded by 42, while the cylindrical middle liner 42 is surrounded by a cylindrical outer liner 40. In these liners 40, 42 and 44, an inner annular passage 70 is formed between the inner liner 44 and the intermediate liner 42, respectively, and an outer annular passage 68 is formed between the intermediate liner 42 and the outer liner 44. Thus, they are arranged concentrically around the axial centerline 71. The transverse flame tube 82 (one of which is shown in FIG. 3) traverses the liners 40, 42 and 44 to the primary combustion zone 36 of the adjacent combustor 4 to facilitate ignition or ignition. Connected together.

According to the present invention, as shown in FIG. 3, a dual fuel nozzle 18 is centrally located within the primary portion 30.
The fuel nozzle 18 is composed of a cylindrical outer sleeve 48 and a cylindrical inner sleeve 51, and the cylindrical outer sleeve 48 together with a cylindrical intermediate sleeve 49 has an outer annular passage.
56, while the cylindrical inner sleeve 51, together with the intermediate sleeve 49, defines an inner annular passage 58. An oil fuel (liquid fuel) supply pipe 60 is arranged in the inner sleeve 51 and supplies the oil fuel 14 ′ to the oil fuel spray nozzle 54. The oil fuel 14 'injected from the atomizing nozzle 54 is the outer sleeve 48.
Flows into the primary combustion zone 36 via the oil fuel (liquid fuel) discharge port 52 formed in the. On the other hand, gas fuel 16 '
Flows through the outer annular passage 56 and through the plurality of gaseous fuel ports 50 formed in the outer sleeve 48 into the primary combustion zone 36.
Is discharged inside. In addition, cooling air 38 flows through the inner annular passage 58.

Premixing of the gaseous fuel 16 "with compressed air from the compressor 2 precedes the primary combustion zone 36 and the primary portion 30.
Is achieved by a primary premix passage formed at the front end of the. As shown in Fig. 3, the primary premix passage is formed by first and second passages 90 and 92 which divide the incoming air into two streams 8'and 8 ". The first passage 90 is upstream. The first passage 90 has an upstream portion between a radially extending circular flange 88 and a radially extending portion of the flow guide 46. Is formed on the downstream side.
And a sleeve 48 on the outer side of the fuel nozzle 18 and surrounded by a second passage 92.

The second passage 92 also has an upstream radial portion and a downstream axial portion. The upstream portion of the second passage 92 is formed between the radially extending portion of the flow guide 49 and the radially extending portion of the inner liner 44.
The downstream portion of the second passage 92 is formed between the axial portion of the flow guide 46 and the axially extending portion of the inner liner 44, and the upstream portion of the passage 92. It is surrounded by. As shown in FIG. 3, the upstream side portion of the second passage 92 is arranged axially downstream from the upstream side portion of the first passage 90, and the downstream side portion of the second passage 92 is It surrounds the downstream portion of the first passage 90.

As shown in FIGS. 3 and 4, a number of axially oriented tubular primary fuel spray pegs 62 extend through the upstream portions of both the first and second passages 90 and 92. Are distributed in the circumferential direction of the primary premixing passages. Also, two rows of gaseous fuel discharge ports 64 (only one of which is shown in FIG. 3) direct the gaseous fuel 16 ″ into the air streams 8 ′ and 8 ″ flowing through the passages 90 and 92. Distributed along the length of each of the primary fuel spray pegs 62. The gaseous fuel discharge port 64 is oriented to discharge gaseous fuel 16 "circumferentially in clockwise and counterclockwise directions.

Further, as shown in FIGS. 3 and 4, a large number of swirl vanes (vortex flow guide plates) 85 and 86 are distributed around the circumference of the upstream portions of the passages 90 and 92. In the preferred embodiment, one swirl vane is located between each primary fuel spray peg 62. As shown in FIG. 4, swirl vane 85 imparts counterclockwise swirl or rotation (when viewed in the axial direction) to airflow 8 ', while swirl vane 86 provides airflow 8 ". Provides clockwise rotation. Thus, the vortices provided by vanes 85 and 86 for air streams 8'and 8 "help achieve good mixing between gaseous fuel 16" and air, thus, the locally fuel, such as to increase the generation of the NO _x dark mixture and hot generation associated therewith can be suppressed.

As shown in FIG. 3, the secondary combustion zone portion 37 of the combustion zone is formed within a liner 45 within the secondary portion 32 of the combustor 2. The outer annular passage 68 opens into the secondary combustion zone 37 and forms both liquid and gas fuel premix passages for the secondary combustion zone in accordance with the teachings of the present invention. The passage 68 defines a centerline that coincides with the axial centerline 71. A portion 8 ″ ′ of the compressed air 8 from the compressor section 2 flows into the passage 68.

A number of radially oriented secondary gas fuel spray pegs 76 are circumferentially distributed around the secondary premix passage 68. The secondary gas fuel spray pegs 76 are supplied with fuel 16 "'from a circumferentially extending manifold 74. An axially extending fuel supply pipe 73 guides the fuel 16"' to the manifold 74. . Two rows of gas fuel discharge ports 78 are distributed along the length of each of the secondary gas fuel spray pegs 76 to allow the gaseous fuel 16 "'to pass through the secondary premixing passage.
It is introduced into the secondary air stream 8 "'flowing through 68. As best shown in FIG. 4, the gaseous fuel discharge port 78 allows the gaseous fuel 16"' to flow circumferentially in both clockwise and counterclockwise directions. Oriented to eject.

In accordance with the present invention, the secondary premix passage 68 is also
Used to premix liquid fuel 14 "and compressed air 8"'. As shown in FIGS. 3 and 4, this premixing is accomplished by six liquid fuel spray nozzles 84 circumferentially arranged around the centerline 71. Although six liquid fuel spray nozzles are shown in the figure, a larger or smaller number of liquid fuel spray nozzles could be used. Each atomizing nozzle 84 is supplied with liquid fuel 14 "by an axially extending fuel tube 72 that can also be utilized to support swirl vanes 85 and 86, as shown in FIGS.

In the preferred embodiment, each spray nozzle 84
5, has an orifice 59 through which the liquid fuel 14 "is injected in the form of a flat (stratified) spray 58. It should be noted that this type of nozzle Is commercially available from Parker-Hannifin, Inc. of Andover, Ohio, USA. Fuel and air are mixed by atomizing liquid fuel 14 "in this form. A certain degree of atomization, which is advantageous above, is achieved. As shown in FIG. 3, to further enhance the mixing of liquid fuel 14 ″ and air 8 ″ ′,
The spray nozzle 84 is secondary along the line 88 where the fuel spray 53 is located at an angle A with respect to the centerline 71 of the passageway, ie along the line 88 which is located at an angle A with respect to the flow direction of the compressed air 8 "'. Oriented to be directed into the premix passage 68. In the preferred embodiment, the angle A is about 60 °.

In accordance with an important aspect of the present invention, the liquid fuel spray nozzle 84 is disposed within a fan-shaped channel portion (passage space) 96, as best shown in FIGS. Six such channel portions 96 are arranged around the center line 71 in a circumferential array or array. Further, these channel portions 96 have the same center line as the liquid fuel spray 53.
It extends outward in the radial direction and downstream in the axial direction so as to be oriented at an angle A with respect to 71.

As shown in FIG. 6, the channel portion 96 is a side wall.
It is formed by 100 and 101 and a front wall 102 and a rear wall 108. These four walls of each channel portion 96 converge toward the channel portion 97. Hereinafter, for convenience of description, the portion 97 will be referred to as a “vertex portion”. An outlet 98 is formed so as to face the apex portion 97 and is connected to the secondary annular passage 68 as shown in FIG. Referring again to FIG. 6, the sidewalls 100 and 101 are arranged at an oblique angle with respect to each other so that the channel portion circumferentially expands from the apex portion 97 toward the outlet 98. Further, the front wall 102 and the rear wall 103 are oriented at an acute angle to each other so that the channel portion expands in the axial direction from the apex portion 97 toward the outlet portion 98. Thus, in the preferred embodiment of the invention, the channel portion 96 widens in two directions from the apex 97 to the outlet 98.

Each liquid fuel spray nozzle 84 is located within the apex 97 of the associated channel portion 96 and is oriented so that the fuel spray 53 is directed toward the outlet 98 of the channel portion. As a result of the widening of the flow cross section of the channel portion 96 in the direction from the apex 97 to the outlet 98, the liquid fuel spray 53 is also expanded on its way to the secondary premix passage 68. This expansion further facilitates atomization of the liquid fuel 14 "into the compressed air 8"'. As a result of this expansion, in combination with the circumferential arrangement of the spray nozzles 84, the liquid fuel 14 "is distributed relatively evenly along the circumference of the passage and is well atomized in the secondary premix passage. Introduced into 68. This secondary premix passage
The length of 68 is such that the atomized fuel 14 "and air 8"'are in the passage
Well mixed in 68, a lean or lean air-fuel ratio is achieved in the secondary combustion zone 37, which results in NO
It is chosen so that the formation of _x is minimized.

During operation with gaseous fuel, the central combustion nozzle
The introduction of gaseous fuel 16 'via 18 first causes a flame in primary combustion zone 36. Since a higher ignition temperature is required as the load of the turbine 6 increases,
Additional fuel is added by introducing gaseous fuel 16 ″ through the primary fuel spray pegs 62. Primary fuel spray pegs
The 62 gives a very good distribution of fuel in the air, so
An air-fuel mixture that is leaner than the central nozzle 18, ie N
O _x to generate a low air-fuel mixture. In this way, when ignition or ignition occurs in the primary combustion zone 36,
The fuel supply to the central nozzle 18 can be shut off. The requirement for fuel flow beyond that supplied by the primary fuel spray pegs 62 is determined by the secondary gas fuel spray pegs.
This can be satisfied by supplying additional fuel 16 "'via 76.

During liquid fuel operation, a flame is first generated in the primary combustion zone 36 by introducing liquid fuel 14 'through the central fuel nozzle 18 as in gas fuel operation. Additional fuel is added by introducing liquid fuel 14 ″ into secondary combustion zone 37 via secondary premix passage 68.
By using the distributed fuel spray nozzles 84 and the fan-shaped channels 96, the fuel is distributed much better in the air than in the central nozzle 18 and therefore via the secondary premixing passage 68. "in the combustion of the fuel 14 supplied through the central nozzle 18" introduced liquid fuel 14 compared to combustion, the air-fuel mixture becomes more lean mixture, thus, NO _x becomes even lower. Thus, once ignition occurs in the primary combustion zone 36, fuel to the central nozzle 18
There is no need to further increase the 14 'supply. This is because the requirement or demand for additional fuel flow can be met by supplying fuel 14 "to the spray nozzle 84.

The liquid fuel spray nozzle 84 is used in the primary combustion zone 36.
It is important to cool the nozzle 84 in order to prevent coking of the liquid fuel 14 "because it is located relatively close to it. According to the present invention, this is as shown in FIG. , By forming a number of holes 94 in the radially extending portion of the inner liner 44.
A portion 66 of the compressed air 8 from the compressor section 2 is able to flow into an annular passage 70 formed between the inner liner 44 and the intermediate liner 42.

At the outlet of the passage 70, a substantially cylindrical baffle (baffle plate) 80 is arranged and extends between the inner liner 44 and the intermediate liner 42. A number of holes are formed along the circumference of the baffle 80 to divide the cooling air 66 into a number of jet streams which impinge on the outer surface of the inner liner 44, thereby causing Cool liner 44. Thus, the air 66 flows through the passage 77 and is discharged to the secondary combustion zone 37. In other words, the air flows over the liquid fuel tube 72 and the upper portion of the channel portion 96, which minimizes the heating of the liquid fuel spray nozzle 84.

Although the preferred embodiment of the invention has been described above, the invention may be embodied in other specific ways without departing from its spirit or essential attributes. Therefore, it is noted that the present invention is not limited to the above description of the preferred embodiment.

[Brief description of drawings]

1 is a simplified schematic diagram of a gas turbine including a combustor according to the present invention.

FIG. 2 is a longitudinal sectional view of a combustion portion of the gas turbine shown in FIG.

3 is a cross-sectional view of the combustor shown in FIG. 2 taken along line III-III in FIG.

4 is a sectional view taken along line IV-IV in FIG.

5 is a cross-sectional view of the fan-shaped channel portion and the fuel spray nozzle shown in FIGS. 3 and 4, taken along line VV in FIG.

6 is a perspective view of the fan-shaped channel portion shown in FIG.

[Explanation of symbols]

 1 Gas Turbine 2 Compressor 4 Combustor 6 Turbine 8 Compressed Air 8 ', 8 "Air Flow 12 Air 13 Cylinder 14, 14', 14" Liquid Fuel 16, 16 ', 16 "Gas Combustion 18 Dual Fuel Nozzle 20 Compressed Gas 24 expansion gas 36 primary combustion zone 37 secondary combustion zone 38 cooling air 40 outer liner 42 middle liner 44 inner liner 46 flow guide 48 outer sleeve 49 middle sleeve 50 gas fuel port 51 inner sleeve 52 liquid fuel discharge port 53 liquid fuel spray 54 Oil fuel spray nozzle 56 Outer annular passage 58 Inner annular passage 58 Flat spray 62 Primary fuel spray peg 64 Gaseous fuel discharge port 66 Air 68 Outer annular passage 68 Secondary premixing passage 68 Secondary annular passage 70 Inner annular passage 71 Shaft Direction Center line 72 Fuel pipe 73 Fuel supply pipe 74 Manifold 76 Secondary gas fuel spray peg 78 Gaseous fuel discharge port 82 Transverse flame pipe 84 Liquid fuel spray nozzle 85, 86 Swirl vane 90 First passage 92 Second Passage 94 hole 96 channel 97 apex 98 exit

Claims (2)

[Claims] 1. A gas turbine having a compressor section for generating compressed air and a combustor for heating the compressed air, wherein the combustor has at least one of (i) a combustion zone and (ii) the combustion zone. First and second cylindrical liners concentrically arranged so as to surround a portion thereof, the first liner surrounding the second liner and between the second liner and the second liner. An annular passage, the annular passage being in fluid communication with the compressor section and the combustion zone, the compressed air flowing through the annular passage to the combustion zone; Liner, and (iii) first fuel introducing means for introducing gaseous fuel into the annular passage to mix the compressed air flowing through the annular passage with the gaseous fuel; (iv) the annular passage Liquid fuel is introduced into the annular passage Gas turbine having a second fuel introduction means for mixing the compressed air flowing and the liquid fuel. 2. A gas turbine having a compressor section for generating compressed air and a combustor for heating the compressed air, wherein the combustor comprises: (i) primary and secondary combustion zones; and (ii) Means for introducing a first fuel stream into a primary combustion zone for combustion within the combustion zone, the first fuel stream being prior to the first fuel stream entering the primary combustion zone. , A first passage having means for premixing with the first portion of the compressed air
And (iii) means for introducing a second fuel stream, which is a liquid fuel, into the secondary combustion zone for combustion in the secondary combustion zone, wherein the second fuel stream is A second passage having means for premixing the second fuel stream with a second portion of the compressed air before entering the secondary combustion zone; and the second fuel with the second passage. Atomizing means comprising a third passage connected to the second passage for atomizing the second fuel before premixing with the compressed air in the passage. A gas turbine having a flow introducing means.