Gas turbine combustor

A gas turbine combustor 2 according to the present invention comprises: a combustion chamber 50 in which fuel is burned with air to generate combustion gas; a plurality of fuel nozzles 30 arranged in multiple concentric annular rows; a first plate 32 arranged downstream of the fuel nozzles 30 and having multiple concentric circular air hole rows made up of a plurality of air holes corresponding to the fuel nozzles 30; a second plate 33 arranged downstream of the first plate 32 and having multiple air hole rows corresponding to the air hole rows of the first plate 32; and a partition wall part 37 which partitions a space part 46 between the first plate 32 and the second plate 33 into rooms corresponding to the air hole rows.

TECHNICAL FIELD

The present invention relates to a gas turbine combustor.

BACKGROUND ART

In recent years, further efficiency improvement and NOx reduction are being required of a gas turbine comprising a compressor, a combustor, a turbine, etc. by the regulations and social demands for environmental conservation. As a method for the efficiency improvement, in this type of gas turbines adopted is a method of increasing the temperature of the combustion gas existing from the combustor to the inlet of the turbine. However, there is a possibility that the amount of NOx emission increases with the increase in the temperature of the flame formed in the combustor.

Combustors designed to reduce the NOx emission include those employing premix combustion. The premix combustion is a combustion method in which air-fuel mixture obtained by previously mixing fuel and air together (premixed gas) is supplied to the combustor and brought into combustion. A combustor of this type comprises a burner having a premixer and a combustion chamber arranged downstream of the burner in the flow direction of the air-fuel mixture. The premixer is a device for generating the air-fuel mixture. The air-fuel mixture is supplied from the premixer to the combustion chamber and combusts in the combustion chamber. In the premix combustion, the fuel and air are previously mixed together and supplied to the combustion chamber, by which the temperature of the flame formed in the combustion chamber is uniformized and the NOx emission from the combustor is reduced. However, if the air temperature or the hydrogen content in the fuel increases, the combustion speed increases and the possibility of the so-called “flashback” (the flame formed in the combustion chamber flowing back to the premixer and so forth) arises. In consideration of the above-described situation, there has been proposed a combustor excelling in flashback resistance while also reducing the NOx emission (see Patent Literature 1, for example).

PRIOR ART LITERATURE

Patent Literature

SUMMARY OF THE INVENTION

Problem to be Solved by the Invention

Patent Literature 1 discloses a configuration in which an air hole plate, including a first perforated plate formed with a plurality of first air holes and a second perforated plate formed with a plurality of second air holes, is arranged downstream of a plurality of fuel nozzles. The air-fuel mixture ejected from the first air holes is made to collide with the second perforated plate and is ejected into the combustion chamber through the second air holes. However, in cases where the fuel is injected from part of the fuel nozzles for partial load operation, air is ejected also from first air holes to which no fuel is supplied. Accordingly, the air-fuel mixture ejected from part of the first air holes is diluted in the space between the first and second perforated plates by the air ejected from the other first air holes and the fuel-air ratio of the air-fuel mixture ejected into the combustion chamber through the second air holes can become excessively low. If the fuel-air ratio of the air-fuel mixture flowing into the second air holes cannot be precisely controlled as in this case, it is difficult to maintain stable combustion in a series of operation steps from the ignition of the gas turbine to the full load operation.

The object of the present invention, which has been made in consideration of the above-described situation, is to provide a combustor capable of precisely controlling the fuel-air ratio in each air hole and thereby achieving stable combustion in a series of operation steps from the ignition of the gas turbine to the full load operation while also reducing the NOx emission.

Means for Solving the Problem

To achieve the above object, a gas turbine combustor in accordance with an aspect of the present invention comprises: a combustion chamber in which fuel is burned with air to generate combustion gas; a plurality of fuel nozzles arranged in multiple concentric annular rows; a first plate arranged downstream of the fuel nozzles and having multiple concentric circular air hole rows made up of a plurality of air holes corresponding to the fuel nozzles; a second plate arranged downstream of the first plate and having multiple air hole rows corresponding to the air hole rows of the first plate; and a partition wall part which partitions a space part between the first plate and the second plate into rooms corresponding to the air hole rows.

Effect of the Invention

According to the present invention, it becomes possible to provide a combustor capable of precisely controlling the fuel-air ratio in each air hole and thereby achieving stable combustion in a series of operation steps from the ignition of the gas turbine to the full load operation while also reducing the NOx emission.

MODES FOR CARRYING OUT THE INVENTION

First Embodiment

1. Gas Turbine Plant

First, a gas turbine plant comprising a gas turbine combustor according to this embodiment will be described below with reference to figures.

FIG. 1is a schematic diagram showing the overall configuration of a power generation gas turbine plant1000comprising the gas turbine combustor2according to this embodiment. As shown inFIG. 1, the gas turbine plant1000comprises a gas turbine and a generator20. The gas turbine includes a compressor1, a gas turbine combustor2and a turbine3.

The compressor1compresses intake air100taken in through an intake part (unshown), thereby generates high-pressure air101, and supplies the high-pressure air101to the gas turbine combustor2. The gas turbine combustor2mixes the high-pressure air101supplied from the compressor1with the fuel supplied through a fuel system200(explained later), combusts the air-fuel mixture, thereby generates high-temperature combustion gas102, and supplies the high-temperature combustion gas102to the turbine3. The turbine3is driven by the expansion of the combustion gas102supplied from the gas turbine combustor2. The generator20is rotated by the drive force obtained by the turbine3and generates electric power. In this embodiment, the compressor1, the turbine3and the generator20are linked together by an integral shaft21. The drive force obtained by the driving of the turbine3is transmitted to the compressor1and the generator20via the shaft21.

The gas turbine combustor2comprises a burner5, a combustor liner10, a flow sleeve11, an inner tail tube12, an outer tail tube13, fuel systems201-204, and a header40. The gas turbine combustor2is stored in the casing4of a gas turbine unit. The burner5is arranged in the gas turbine combustor2. The combustor liner10, formed in a cylindrical shape for separating the combustion gas102generated by the gas turbine combustor2from the high-pressure air101supplied from the compressor1, is arranged inside the gas turbine combustor2and downstream of the burner5in the flow direction of the combustion gas102.

Arranged outside the combustor liner10is the flow sleeve11which is formed in a cylindrical shape to cover the combustor liner10. An annular space formed between the combustor liner10and the flow sleeve11constitutes a channel48through which the high-pressure air101supplied from the compressor1to the gas turbine combustor2flows.

In the combustion chamber50formed inside the combustor liner10, the air-fuel mixture of the high-pressure air101ejected from the burner5and the fuel supplied through the fuel system200is combusted. One end of the combustor liner10farther from the burner5(downstream end in the flow direction of the combustion gas102) is inserted into one end of the inner tail tube12. The inner tail tube12is a tube for leading the combustion gas102generated in the combustion chamber50to the turbine3. The other end of the inner tail tube12is connected to a line connecting the gas turbine combustor2and the turbine3together. Arranged outside the inner tail tube12is the outer tail tube13which is formed in a cylindrical shape to cover the inner tail tube12. One end of the flow sleeve11farther from the burner5(downstream end in the flow direction of the combustion gas102) is inserted into one end of the outer tail tube13. The outer tail tube13forms an annular space between itself and the inner tail tube12. The other end of the outer tail tube13is open to the inside of the casing4. The space between the inner tail tube12and the outer tail tube13constitutes a channel47for the high-pressure air101flowing in from the other end of the outer tail tube13.

The high-pressure air101flowing into the channel47formed between the inner tail tube12and the outer tail tube13cools down the inner tail tube12from its outer surface by means of convection cooling. Further, the high-pressure air101flowing into the annular channel48formed between the flow sleeve11and the combustor liner10after flowing through the channel47is used for convection cooling of the combustor liner10arranged in the gas turbine combustor2.

Part of the high-pressure air101flowing through the annular channel48formed between the flow sleeve11and the combustor liner10flows into the inside of the combustor liner10via a lot of cooling holes (unshown) formed through the wall of the combustor liner10and is used for the film cooling of the combustor liner10. The remaining high-pressure air101that was not used for the film cooling of the combustor liner10flows through the annular channel48and is supplied to the inside of the combustor liner10as combustion air via a great number of air holes31of the burner5provided for the gas turbine combustor2. Then, via the great number of air holes31, the combustion air is ejected from the burner5of the gas turbine combustor2.

The burner5is supplied with the fuel from four fuel systems201-204(F1-F4 fuel systems). The F1-F4 fuel systems201-204are provided with F1-F4 fuel flow control valves211-214, respectively. In this embodiment, the fuel systems201-204branch out from the fuel system200having a fuel shut-off valve (switching valve)210. Incidentally, the number of fuel systems branching out from the fuel system200is not limited to four.

The fuel flowing through the fuel systems201-204is supplied to the header40which is partitioned into multiple rooms differing in the radial direction distance from the central axis of the combustor liner10. In this embodiment, the header40is partitioned into a first header51, a second header52, a third header53and a fourth header54. The F1 fuel system201, the F2 fuel system202, the F3 fuel system203and the F4 fuel system204are connected to the first header51, the second header52, the third header53and the fourth header54, respectively. The fuel supplied to the header40via each fuel system is injected from tip ends of fuel nozzles30supported by the header40and supplied to the burner5. Incidentally, the number of partitioned spaces (rooms) in the header40is not limited to four.

The flow rate of F1 fuel supplied to the burner5through the F1 fuel system201is regulated by the F1 fuel flow control valve211. The flow rate of F2 fuel supplied to the burner5through the F2 fuel system202is regulated by the F2 fuel flow control valve212. The flow rate of F3 fuel supplied to the burner5through the F3 fuel system203is regulated by the F3 fuel flow control valve213. The flow rate of F4 fuel supplied to the burner5through the F4 fuel system204is regulated by the F4 fuel flow control valve214. In this embodiment, the amount of power generation by the gas turbine plant1000is controlled by regulating the flow rates of the F1 fuel, the F2 fuel, the F3 fuel and the F4 fuel with the fuel flow control valves211,212,213and214, respectively.

Next, the detailed configuration of the burner5will be explained.FIG. 2is a partial structural drawing showing the structure around the burner5of the gas turbine combustor2according to this embodiment. As shown inFIG. 2, the burner5includes a plurality of fuel nozzles30, a base plate (first plate)32, a turning plate (second plate)33, and partition wall parts37.

The configuration of each part of the burner5will be explained below. In this embodiment, multiple rows of air holes (air hole rows) arranged concentrically will be referred to as a first row, a second row, . . . , and an eighth row from inside to outside as needed.

Fuel Nozzle

As shown inFIG. 2, a plurality of fuel nozzles30for ejecting the fuel supplied from the fuel system200are supported by the fuel header40. These fuel nozzles30are arranged in a plurality of (eight in this embodiment) concentric annular rows. In each annular row, the fuel nozzles30are formed around the whole circumference of the annular row.

Base Plate

FIG. 5is a schematic diagram of the base plate32in this embodiment viewed from the downstream side. As shown inFIGS. 2 and 5, the base plate32, as a disc-shaped plate coaxial with the central axis of the combustor liner10, is arranged downstream of the fuel nozzles30in the fuel flow direction. The base plate32is formed with a plurality of (eight in this embodiment) concentric circular air hole rows made up of the air holes31A corresponding to the fuel nozzles30, respectively, have been formed. Thus, each air hole31A is arranged on the fuel ejection side of a corresponding fuel nozzle30in its axial direction (downstream side in the fuel ejection direction) in association with the corresponding fuel nozzle30. With one fuel nozzle30and one air hole31A arranged in association with each other as in this example, a coaxial jet, in which the fuel (fuel jet)34ejected from the fuel nozzle30is surrounded and covered with the air (air jet)35flowing through the air hole31, flows through the base plate32. These air holes31A are formed around the whole circumference of each annular air hole row. In this embodiment, each air hole31A is formed in the shape of a right cylinder in which the two circles forming the end faces are orthogonal to the generating line, and arranged coaxially with the corresponding fuel nozzle30. Each fuel nozzle30is not inserted into the corresponding air hole31A, that is, the end face of the air hole31A on the upstream side in the fuel flow direction (hereinafter referred to as an “inlet” as needed) is apart from the end of the fuel nozzle30on the downstream side in the fuel flow direction.

Turning Plate

As shown inFIG. 2, the turning plate33is arranged downstream of the base plate32in the fuel flow direction to face the base plate32. Through the turning plate33, a plurality of concentric circular air hole rows made up of air holes31B and corresponding to the plurality of (eight in this embodiment) air hole rows of the base plate32have been formed. These air holes31B are formed around the whole circumference of each annular air hole row. In this embodiment, the number of air holes31B equals the number of air holes31A of the base plate32.

FIG. 3is an enlarged view of the turning plate33in this embodiment (cross-sectional view taken along the line III-III inFIG. 4).FIG. 4is a schematic diagram of the turning plate33in this embodiment viewed from the downstream side.

As shown inFIG. 3, each air hole31B is formed in the shape of an oblique cylinder in which the two ellipses forming the end faces are not orthogonal to the generating line. The air hole31B is a turning air hole having a turning angle. The end of the air hole31B on the downstream side in the flow direction of the air-fuel mixture (hereinafter referred to as an “outlet” as needed) is shifted from the position of the upstream end (hereinafter referred to as an “inlet” as needed) in the circumferential direction. Specifically, the central axis of the air hole31B (obtained by connecting the centers of two circles at both ends of the air hole31B) is oblique to the turning plate33in the circumferential direction to have a prescribed angle α° from the central axis of the fuel nozzle30, the central axis of the air hole31A, or the central axis of the combustor liner10. In short, the air hole31B is oblique to the turning plate33in the circumferential direction by the prescribed angle α°. Here, the expression “have a prescribed angle” in this embodiment means that the central axis of the air hole31B is not parallel or orthogonal to the other central axis (the central axis of the fuel nozzle30, the central axis of the air hole31A, or the central axis of the combustor liner10). The angle α° is an element prescribing the air ejection direction from the air hole31B. The angle α° has been set at an optimum value in each air hole row of the air holes31B.

As shown inFIG. 2, the base plate32and the turning plate33are attached to the fuel header40via a support15. The base plate32and the turning plate33are held in the combustor liner10via a spring seal14. In this embodiment, the support15is in a shape formed by bending a flat plate. By forming the support15in such a shape, thermal expansion in the circumferential direction can be absorbed by the bent structure and the reliability of the burner5can be increased.

As shown inFIG. 4, the burner5constituting a combustion unit of the gas turbine combustor2is divided into multiple regions. In this embodiment, four rows forming the innermost one of the regions (first through fourth rows) constitute a first-group combustion unit (F1 burner)5A, the fifth row constitutes a second-group combustion unit (F2 burner)5B, the sixth row constitutes a third-group combustion unit (F3 burner)5C, and two rows on the peripheral side (seventh and eighth rows) constitute a fourth-group combustion unit (F4 burner)5D. The F1-F4 fuel systems201-204are connected to the F1-F4 burners5A-5D via the aforementioned first through fourth headers51-54, respectively. Such a group structure with the fuel systems201-204branching out from the fuel system200makes it possible to carry out the so-called “fuel staging” (changing the number of fuel nozzles30used for the fuel supply in stages in response to the change in the fuel flow rate required by the gas turbine).

In the F1 burner5A, the gap formed between two air holes31B adjoining each other in the circumferential direction (inter-hole distance) has been set greater than the flame quenching distance. With this setting, the flame approaches the turning plate33and the stability of the flame is enhanced. In contrast, in the F2 burner5B, the F3 burner5C and the F4 burner5D, the gap formed between two air holes31B adjoining each other in the circumferential direction (inter-hole distance) has been set less than or equal to the flame quenching distance, by which the flame is formed apart from the turning plate33. The mixing of the fuel jet34and the air jet35progresses rapidly when the channel suddenly enlarges from the air holes31B to the combustion chamber50. If the flame is formed at a position apart downstream from the turning plate33, low NOx combustion can be performed since premixed gas of fuel and air sufficiently mixed together reaches the flame and combusts.

Partition Wall Part

As explained above, the first combustion unit F1 and the second through fourth combustion units F2-F4 have different functions; the first combustion unit F1 has the function of enhancing stable combustion while the second combustion unit F2, the third combustion unit F3 and the fourth combustion unit F4 have the function of performing low NOx combustion. To achieve both the enhancement of stable combustion and the low NOx combustion, it is necessary to promote the mixing of fuel and air while precisely controlling the flow rate of the fuel supplied to each combustion unit. For this purpose, the base plate32in this embodiment is provided with the partition wall parts37which partition a space part46formed between the base plate32and the turning plate33into rooms corresponding to the air hole rows of the base plate32and the turning plate33.

The space part46exists between the base plate32and the turning plate33(seeFIG. 2, for example). The periphery of the space part46is covered by a burner partition wall49. The space part46connects with the end of each air hole31A of the base plate32on the downstream side in the flow direction of the air-fuel mixture (hereinafter referred to as an “outlet” as needed) and the inlet of each air hole31B. Thus, the air holes31A and the air holes31B are connected with each other via the space part46. Incidentally, only the air-fuel mixture of the fuel jet34and the air jet35ejected from the air holes31A flows through the space part46covered by the burner partition wall49; there is no inflow of secondary fuel, secondary air, etc. into the space part46covered by the burner partition wall49.

As shown inFIG. 5, the partition wall parts37(seven partition wall parts37in this embodiment) are formed concentrically corresponding to the air hole rows made up of the air holes31A. Each partition wall part37extends from the base plate32to the turning plate33and contacts the opposing surface of the turning plate33(seeFIG. 2). By these partition wall parts37, the space part46is partitioned into a plurality of annular internal channels36(eight internal channels36in this embodiment). These internal channels36are formed in a concentric circular pattern.

FIG. 6is an enlarged view of the region surrounded by dotted lines inFIG. 5.FIG. 7is a perspective view of the VII-VII cross section inFIG. 6. As shown inFIGS. 6 and 7, the width W36of each internal channel36(dimension of the internal channel36in the radial direction of the base plate32) has been set at a dimension greater than or equal to the hole diameter of the air hole31A. The depth D36of each internal channel36with reference to the plane where the partition wall parts37contact the turning plate33(dimension of the internal channel36in the radial direction of the base plate32) has been set at a dimension equivalent to the hole diameter of the air hole31A. Let S31represent the cross-sectional area of the air hole31A (one air hole31A), the width W36and the depth D36of the internal channel36are desired to be set to satisfy the following expression (1):
S31≤W36×D36  (1)

The expression (1) indicates that the cross-sectional area of the internal channel36is greater than or equal to that of the air hole31A.

If the width W36and the depth D36of the internal channel36are set to satisfy S31>W36×D36contrary to the expression (1), the flow velocity in the internal channel36increases and the mixing of fuel and air is promoted; however, the efficiency of the gas turbine plant1000can drop due to an increase in the pressure loss.

In contrast, if the width W36and the depth D36of the internal channel36are set greater than the hole diameter of the air hole31A, a non-stationary vortex or stagnation can locally occur in the internal channel36and deteriorate the reliability of the combustor. Therefore, the width W36and the depth D36of the internal channel36are desired to be set to satisfy the following expression (2):
2×S31>W36×D36  (2)
(Operation)

Next, the combustion operation of the gas turbine combustor2according to this embodiment will be explained below by referring to figures.

FIG. 8is a cross-sectional view schematically showing the flow of fuel and air in the burner5in this embodiment (cross-sectional view taken along the line VIII-VIII inFIG. 6). As shown inFIGS. 2 and 8, the high-pressure air101which has been led to the combustion chamber50via the channels47and48flows into the air holes31A formed through the base plate32of the air hole plate39as the air jets35. Meanwhile, the fuel which has been supplied from the fuel system200to the fuel nozzles30via the fuel header40is ejected from the discharge holes of the fuel nozzles30and flows into the air holes31A as the fuel jets34. Each fuel jet34flowing into the air hole31A is surrounded and covered by the air jet35, flows downstream from the air hole31A to an internal channel36of the space part46, and fills the internal channel36. Since the degree of mixing of the air-fuel mixture jet of the fuel jet34and the air jet35is still low, the fuel concentration is high in the central part and low in the peripheral part. The temperature of the fuel jet34is several hundred ° C. lower than that of the air jet35, and thus the temperature of the air-fuel mixture jet ejected from the air hole31A is low in the central part and high in the peripheral part. When the air-fuel mixture jet flows into the internal channel36, the channel for the jet suddenly enlarges and the mixing is promoted in the vicinity of the inlet of the internal channel36(outlet of the air hole31A) (primary mixing). The air-fuel mixture of the fuel jet34and the air jet35formed by the primary mixing (primary air-fuel mixture) flows from the internal channel36into an air hole31B formed through the turning plate33. When the primary air-fuel mixture flows into the air hole31B, the channel size suddenly reduces and the mixing is promoted further in the vicinity of the inlet of the air hole31B (outlet of the internal channel36) (secondary mixing). The air-fuel mixture of the fuel jet34and the air jet35formed by the secondary mixing (secondary air-fuel mixture) flows through the air hole31B. Since the air hole31B is formed as a path inclined at the angle α° (oblique cylindrical path), a force component in a turning direction is given to the secondary air-fuel mixture flowing through the air hole31B and a circulating flow is formed. Since the outlet of the air hole31B is open to the combustion chamber50, the channel for the secondary air-fuel mixture suddenly enlarges and the mixing is promoted further in the vicinity of the outlet of the air hole31B (tertiary mixing). The air-fuel mixture of the fuel jet34and the air jet35formed by the tertiary mixing (tertiary air-fuel mixture) is ejected into the combustion chamber50as premixed gas38while turning and is combusted in the combustion chamber50.

FIG. 9is a schematic diagram showing the fuel staging in the gas turbine combustor2according to this embodiment. InFIG. 9, the horizontal axis represents the elapsed time and the vertical axis represents the fuel flow rate.

As shown inFIG. 9, at the ignition of the gas turbine, the fuel is supplied from the fuel system200to the F1 burner5A, the F2 burner5B and the F3 burner5C, whereas the F4 burner5D is supplied with no fuel.

After the gas turbine ignition, the operation is switched to solo combustion of the F1 burner5A and the turbine3is accelerated until the turbine3reaches the rated revolution speed no load state (FSNL: Full Speed No Load). In this period, only the F1 burner5A is supplied with the fuel from the fuel system200. The F2 burner5B, the F3 burner5C and the F4 burner5D are supplied with no fuel.

After the turbine3has accelerated to the rated revolution speed, the power generation is started and the load is increased gradually. With the increase in the load, the fuel supply range (area) is enlarged in stages (the fuel is successively supplied in the order of the F2 burner5B, the F3 burner5C and the F4 burner5D) so that the fuel-air ratio of the burner5of the gas turbine combustor2remains in a stable combustion range. In the combustion condition in which all the F1-F4 burners5A-5D are supplied with the fuel, the rated revolution speed full load state (FSFL: Full Speed Full Load) is achieved.

(1) In this embodiment, the space part46between the base plate32and the turning plate33is partitioned by the partition wall parts37into rooms corresponding to the air hole rows of the base plate32and the turning plate33. Therefore, even when the fuel is injected from part of the fuel nozzles30in the partial load operation of the burner5, the air-fuel mixture ejected from part of the air holes31A is not diluted in the space between the base plate32and the turning plate33by air ejected from air holes31A of the other air hole rows. Accordingly, the fuel-air ratio of the premixed gas38ejected from the air holes31B into the combustion chamber50can be prevented from becoming excessively low. Further, since the flow rate and the fuel-air ratio of the premixed gas38ejected from the air holes31B into the combustion chamber50can be equalized among the air holes31B belonging to the same row, circumferential deviations in the flow rate and the fuel-air ratio in the burner5can be reduced. Therefore, it becomes possible to precisely control the fuel-air ratio of the premixed gas38ejected from each air hole31B and thereby achieve stable combustion in a series of operation steps from the ignition of the gas turbine to the full load operation while also reducing the NOx emission.

(2) In this embodiment, the cross-sectional area of each internal channel36formed in the space part46by the partitioning by the partition wall parts37is set larger than or equal to the cross-sectional area of the air hole31A of the base plate32. Therefore, the increase in the flow velocity of the air-fuel mixture jet in the internal channel36can be suppressed and the drop in the efficiency of the gas turbine plant1000due to the increase in the pressure loss can be reduced.

(3) In this embodiment, the group structure enabling the individual control of the F1-F4 burners5A-5D is employed by branching the fuel system200into the fuel systems201-204. With the group structure, the fuel staging (changing the number of fuel nozzles30used for the fuel supply in stages in response to the change in the fuel flow rate required by the gas turbine) can be carried out. Accordingly, stable combustion in the partial load operation of the gas turbine can be performed while also reducing the NOx emission.

(4) In this embodiment, in the F1 burner5A, the distance between two air holes31B adjoining each other in the circumferential direction is set greater than the flame quenching distance. Accordingly, the flame approaches the turning plate33and the stability of the flame can be enhanced further.

(5) In this embodiment, the fuel and air mix together in stages. Therefore, the fuel and air can be prevented from perfectly mixing together in the air hole31A, by which spontaneous ignition of the fuel in the air hole31A can be prevented. Accordingly, erosion (melting) of the base plate32and the turning plate33can be prevented and the reliability of the gas turbine combustor2can be increased.

In this embodiment, the downstream ends of the fuel nozzles30in the fuel flow direction are apart from the inlets of the air holes31A. Therefore, the increase in the flow velocity of the fuel in the air hole31A can be suppressed and the drop in the efficiency of the gas turbine plant1000due to the increase in the pressure loss can be reduced in comparison with a configuration in which the tip ends of the fuel nozzles30are inserted into the air holes31A, for example.

In this embodiment, the fuel jet34and the air jet35are ejected into the combustion chamber50in the form of a coaxial jet, by which the interfacial area between the fuel and air is increased and the mixing of the fuel and air is promoted further. Accordingly, the amount of NOx generated by the combustion in the combustion chamber50can be reduced.

In this embodiment, due to the inclination angle α° of the air holes31B in the circumferential direction, the fluid flowing through the air holes31B is injected from the air holes31B while forming a circulating flow. Accordingly, flame with higher stability can be formed.

(6) According to this embodiment, the gas turbine combustor is formed in simple structure in which the turning plate33having the air hole rows corresponding to the air hole rows of the base plate32is arranged downstream of the base plate32and the partition wall parts37are arranged to partition the space part46between the base plate32and the turning plate33into rooms corresponding to the air hole rows. Therefore, the gas turbine combustor can be manufactured with ease by modifying an existing gas turbine combustor. For example, the present invention is easily applicable to an existing gas turbine combustor comprising: a combustion chamber in which fuel is burned with air to generate combustion gas; a plurality of fuel nozzles arranged in multiple concentric annular rows; and a base plate arranged downstream of the fuel nozzles and having multiple concentric circular air hole rows made up of a plurality of air holes corresponding to the fuel nozzles, by arranging the turning plate33downstream of the base plate and arranging the partition wall parts37in the space part between the base plate and the turning plate33.

Second Embodiment

FIG. 10is a cross-sectional view schematically showing the flow of fuel and air in a gas turbine combustor according to this embodiment. Elements inFIG. 10equivalent to those in the above-described first embodiment are assigned the already-used reference characters and repeated explanation thereof is appropriately omitted.

This embodiment differs from the first embodiment in the configuration of the air holes31B of the turning plate33. The configuration of the air holes31B will be explained below.

While the air holes31B in the first embodiment are formed at positions corresponding to the air holes31A in the circumferential direction, the air holes31B in this embodiment are formed as shown inFIG. 10. InFIG. 10, the inlets of the air holes31B of the turning plate33connecting to the space part46and the outlets of the air holes31A connecting to the space part46are shifted from each other in the circumferential direction. Specifically, the intersection point between the central axis of each air hole31B and the surface of the turning plate33on the fuel nozzle30's side (i.e., the center of the inlet of the air hole31B) is apart from the central axis of the corresponding air hole31A in the circumferential direction. On the central axis of each air hole31A, a wall surface of the turning plate33is situated. The rest of the configuration is equivalent to that in the first embodiment.

As shown inFIG. 10, the fuel jet34ejected from the fuel nozzle30and the air jet35form the primary air-fuel mixture in the internal channel36similarly to the first embodiment. The primary air-fuel mixture collides with the wall surface of the turning plate33situated on the central axis of the air hole31A and then flows in the circumferential direction along the internal channel36. Thereafter, the primary air-fuel mixture flows into an air hole31B and is supplied to the combustion chamber50as the premixed gas38and combusted similarly to the first embodiment.

According to this embodiment, the following effects are achieved in addition to the effects of the first embodiment.

In this embodiment, the outlets of the air holes31A and the inlets of the air holes31B are shifted from each other in the circumferential direction and a wall surface of the turning plate33is situated on the central axis of each air hole31A. Accordingly, the air-fuel mixture jet ejected from the air hole31A with a low-temperature part existing at the center of the jet collides with the wall surface. Thus, the turning plate33heated by the thermal radiation from the flame in the combustion chamber50can be cooled down and the operating life of the turning plate33can be increased. Further, since a flow of the air-fuel mixture jet, flowing into the internal channel36, in the circumferential direction (one direction) is induced, the distance for which the air-fuel mixture jet flows in the internal channel36(hereinafter referred to as a “mixing distance”) can be made longer than that in the first embodiment. Therefore, the mixing of fuel and air in the internal channel36can be promoted further and the NOx emission can be reduced further.

Third Embodiment

FIG. 11is a schematic diagram of a base plate of a gas turbine combustor according to this embodiment viewed from the downstream side.FIG. 12is an enlarged view of the base plate of the gas turbine combustor according to this embodiment (cross-sectional view taken along the line XII-XII inFIG. 11).FIG. 13is a cross-sectional view schematically showing the flow of fuel and air in the gas turbine combustor according to this embodiment. Elements inFIGS. 11-13equivalent to those in the first embodiment are assigned the already-used reference characters and repeated explanation thereof is appropriately omitted.

This embodiment differs from the above-described embodiments in the configuration of the air holes31A.

As shown inFIGS. 11 and 12, in this embodiment, the central axis of the air hole31A of the base plate32(obtained by connecting the centers of the two circles at both ends of the air hole31A) extends obliquely with respect to the circumferential direction of the base plate32to have a prescribed angle β° from the central axis of the fuel nozzle30or the central axis of the combustor liner10. In short, the air hole31A is formed to be oblique to the base plate32by the prescribed angle β°. Here, the expression “have a prescribed angle” in this embodiment means that the central axis of the air hole31A is not parallel to the other central axis (the central axis of the fuel nozzle30or the central axis of the combustor liner10). The angle β° is an element prescribing the air ejection direction from the air hole31A into the internal channel36. The angle β° has been set at an optimum value in each air hole row of the air holes31A. The air hole31A is formed as a path inclined at the angle β° (oblique cylindrical path). The rest of the configuration (e.g., a wall surface of the turning plate33being situated on the central axis of each air hole31A) is equivalent to that in the second embodiment.

As shown inFIG. 13, the fuel jet34ejected from the fuel nozzle30and the air jet35form the primary air-fuel mixture in the internal channel36similarly to the first embodiment and then collide with the wall surface of the turning plate33situated on the central axis of the air hole31A. Since the air hole31A is formed obliquely to the base plate32in this embodiment, the primary air-fuel mixture flows in the internal channel36in one direction (circumferential direction) in an orderly manner while colliding with the wall surface of the turning plate33and then flows into an air hole31B. Thereafter, the air-fuel mixture is supplied to the combustion chamber50as the premixed gas38and combusted similarly to the first embodiment.

According to this embodiment, the following effects are achieved in addition to the effects of the above-described embodiments.

In this embodiment, each air hole31A formed through the base plate32is inclined from the axial direction of the fuel nozzle30or the combustor liner10in the circumferential direction of the base plate32. Therefore, a force component in a turning direction is actively given to the air-fuel mixture jet flowing through the air hole31A. Accordingly, the primary air-fuel mixture in the internal channel36flows in one direction (circumferential direction of the internal channel36) in an orderly manner while colliding with the wall surface of the turning plate33. Consequently, the occurrence of a local vortex or stagnation to the primary air-fuel mixture in the internal channel36can be suppressed, the pressure loss occurring when the air-fuel mixture flows through the internal channel36can be reduced, and the mixing of fuel and air can be promoted.

Fourth Embodiment

FIG. 14is a cross-sectional view schematically showing the flow of fuel and air in a gas turbine combustor according to this embodiment. Elements inFIG. 14equivalent to those in the first embodiment are assigned the already-used reference characters and repeated explanation thereof is appropriately omitted.

This embodiment differs from the above-described embodiments in that the air hole31B of the turning plate33is provided with a restrictor.

As shown inFIG. 14, in this embodiment, a step-like restrictor39A is formed on the inlet side (fuel nozzle30's side) of the air hole31B formed through the turning plate33. The restrictor39A is formed so that the hole diameter of the air hole31B decreases on the inlet side of the air hole31B. As a result, the area of the inlet of the air hole31B is decreased compared to the third embodiment, for example. Also in this embodiment, the intersection point between the central axis of each air hole31B and the surface of the turning plate33on the fuel nozzle30's side is apart from the central axis of the corresponding air hole31A in the circumferential direction, and a wall surface of the turning plate33is situated on the central axis of each air hole31A. The rest of the configuration is equivalent to that in the second embodiment.

As shown inFIG. 14, the fuel jet34ejected from the fuel nozzle30and the air jet35form the primary air-fuel mixture in the internal channel36similarly to the first embodiment. Similarly to the second embodiment, the primary air-fuel mixture collides with a wall surface of the turning plate33(situated on the central axis of the air hole31A) while flowing in the internal channel36in the circumferential direction. In this embodiment, the hole diameter of the air hole31B on the fuel nozzle30's side is reduced by forming the restrictor39A on the inlet side of the air hole31B. Therefore, when the primary air-fuel mixture flowing in the internal channel36in the circumferential direction flows from the internal channel36into an air hole31B of the turning plate33, the primary air-fuel mixture is distributed to the air holes31B of the same row more evenly compared to the first embodiment. Thereafter, the primary air-fuel mixture flows into the air holes31B and is supplied to the combustion chamber50as the premixed gas38and combusted similarly to the first embodiment.

According to this embodiment, the following effects are achieved in addition to the effects of the above-described embodiments.

In this embodiment, the restrictor39A is formed on the inlet side of the air hole31B and the hole diameter of the air hole31B is reduced. Therefore, the circumferential deviation in the flow rate of the premixed gas38injected from each air hole31B into the combustion chamber50(flow rate deviation among the air holes) can be reduced further. Additionally, the mixing of fuel and air can be promoted further since the channel suddenly enlarges downstream of the restrictor39A.

Fifth Embodiment

FIG. 15is a cross-sectional view schematically showing the flow of fuel and air in a gas turbine combustor according to this embodiment. Elements inFIG. 15equivalent to those in the first embodiment are assigned the already-used reference characters and repeated explanation thereof is appropriately omitted.

This embodiment illustrates another example of the configuration of the restrictor formed in the air hole31B of the turning plate33.

As shown inFIG. 15, in this embodiment, a slope-like restrictor39B is formed on the inlet side (fuel nozzle30's side) of the air hole31B of the turning plate33so that the hole diameter gradually decreases from the outlet side (combustion chamber50's side) toward the inlet side of the air hole31B. The restrictor39B is formed so that the hole diameter of the air hole31B hits the minimum at the end on the fuel nozzle30's side. As a result, the area of the inlet of the air hole31B is decreased compared to the third embodiment, for example. Also in this embodiment, the intersection point between the central axis of each air hole31B and the surface of the turning plate33on the fuel nozzle30's side is apart from the central axis of the corresponding air hole31A in the circumferential direction, and a wall surface of the turning plate33is situated on the central axis of each air hole31A. The rest of the configuration is equivalent to that in the second embodiment.

As shown inFIG. 15, the fuel jet34ejected from the fuel nozzle30and the air jet35form the primary air-fuel mixture in the internal channel36similarly to the first embodiment. Similarly to the second embodiment, the primary air-fuel mixture collides with a wall surface of the turning plate33(situated on the central axis of the air hole31A) while flowing in the internal channel36in the circumferential direction. Since a restrictor (restrictor39B) is formed on the inlet side of the air hole31B also in this embodiment, the primary air-fuel mixture flowing in the internal channel36in the circumferential direction is distributed to the air holes31B of the same row more evenly compared to the first embodiment similarly to the fourth embodiment. Thereafter, the primary air-fuel mixture flows into the air holes31B and is supplied to the combustion chamber50as the premixed gas38and combusted similarly to the first embodiment.

According to this embodiment, the following effects are achieved in addition to the effects of the above-described embodiments.

In this embodiment, the slope-like restrictor39B is formed on the inlet side (fuel nozzle30's side) of the air hole31B of the turning plate33so that the hole diameter gradually decreases from the outlet side (combustion chamber50's side) toward the inlet side of the air hole31B. Since the air hole31B is formed in a tapered shape with no step, the increase in the pressure loss caused by the sudden enlargement of the channel when the air-fuel mixture flows from the internal channel36into the air hole31B can be suppressed compared to the fourth embodiment and the efficiency of the gas turbine plant1000can be increased.

Sixth Embodiment

FIG. 16is a cross-sectional view of a gas turbine combustor according to this embodiment.FIG. 17is a schematic diagram of an air hole plate of the gas turbine combustor according to this embodiment viewed from the downstream side (cross-sectional view taken along the line XVII-XVII inFIG. 16). Elements inFIGS. 16 and 17equivalent to those in the first embodiment are assigned the already-used reference characters and repeated explanation thereof is appropriately omitted.

In this embodiment, the present invention is applied to the so-called multiple injection gas turbine combustor in which a plurality of burners, each including a plurality of fuel nozzles and multiple air hole rows made up of air holes are arranged in a concentric circular pattern, are arranged in a combustion unit of the gas turbine combustor. In this embodiment, the concentrically arranged air hole rows will be referred to as the first row, the second row and the third row from the center toward the periphery as needed.

As shown inFIGS. 16 and 17, the gas turbine combustor2according to this embodiment comprises a plurality of burners in each of which a plurality of fuel nozzles30and multiple air hole rows made up of a plurality of air holes31A and31B are arranged in a concentric circular pattern (three rows of fuel nozzles30and three air hole rows in this embodiment). In each burner, six fuel nozzles30and air holes31A and31B are arranged in the first row, twelve fuel nozzles30and air holes31A and31B are arranged in the second row, and eighteen fuel nozzles30and air holes31A and31B are arranged in the third row.

At the center of the combustion unit of the gas turbine combustor2, one burner (pilot burner)41is arranged coaxially with the gas turbine combustor2and six burners (main burners)42are arranged around the pilot burner41. In short, the gas turbine combustor2in this embodiment is configured as a multi-burner structure including seven burners. The seven burners41and42share a base plate32and a turning plate33. Specifically, the turning plate33of the burners41and42is provided with the air holes31A and31B, the partition wall parts37, etc. of each embodiment described above.

FIG. 18is an enlarged view of a part of the turning plate33surrounded by the chain lines (part A) inFIG. 16.FIG. 19is an enlarged view of the main burner42surrounded by the chain line (part B) inFIG. 17. As shown inFIGS. 18 and 19, multiple partition wall parts37are formed in a concentric circular pattern so as to separate the air hole rows (made up of a plurality of air holes31A and31B) from each other (in this embodiment, two partition wall parts37are formed in each burner41/42). By the partition wall parts37, the space part46of the turning plate33is partitioned into multiple internal channels36for leading the air-fuel mixture (ejected from the air holes31A) in the circumferential direction (in this embodiment, the space part46in each burner41/42is partitioned into three internal channels36). The internal channels36are formed in a concentric circular pattern corresponding to the partition wall parts37. Also in this embodiment, the air hole31B is formed as a turning air hole having a turning angle as shown inFIG. 18.

As shown inFIG. 16, in this embodiment, the fuel is supplied from a fuel system200having a fuel shut-off valve210to the pilot burner41and the main burners42via a header40. The fuel system200branches into four fuel systems: an F1 fuel system201having an F1 fuel flow control valve211; an F2 fuel system202having an F2 fuel flow control valve212; an F3 fuel system203having an F3 fuel flow control valve213; and an F4 fuel system204having an F4 fuel flow control valve214.

As shown inFIGS. 16 and 17, the F1 fuel system201is connected to an F1 burner43constituting the pilot burner41. The flow rate of F1 fuel supplied to the F1 burner43is regulated by the F1 fuel flow control valve211. The F2 fuel system202is connected to an F2 burner44constituting the first rows of two main burners42in the six main burners42. The flow rate of F2 fuel supplied to the F2 burner44is regulated by the F2 fuel flow control valve212. The F3 fuel system203is connected to an F3 burner45constituting the first rows of the remaining four main burners42in the six main burners42. The flow rate of F3 fuel supplied to the F3 burner45is regulated by the F3 fuel flow control valve213. The F4 fuel system204is connected to an F4 burner46constituting the second and third rows of the six main burners42. The flow rate of F4 fuel supplied to the F4 burner46is regulated by the F4 fuel flow control valve214.

Incidentally, while the partition wall parts37are formed in every burner (pilot burner41, main burner42) in this embodiment, it is sufficient if the partition wall parts37are formed only in burners that are required to perform the mixing of fuel and air with high accuracy. For example, it is possible to form the partition wall parts37only in the main burners42without forming the partition wall parts37in the pilot burner41.

The operation of the gas turbine combustor2according to this embodiment will be explained below.

Also in this embodiment, the fuel jets34injected from the fuel nozzles30and the air jets35flowing into the gas turbine combustor2flow into the air holes31A of each burner and then flow through the internal channels36and the air holes31B in this order similarly to the first embodiment. Thereafter, as shown inFIG. 16, the air-fuel mixture is ejected from the air holes31B of each burner while forming a swirl flow60and is supplied to the combustion chamber50as the premixed gas38. In this case, the premixed gas38is ejected from the air holes31B of each burner while forming the swirl flow60. Due to the swirl flow60, a circulating flow61is formed at each burner and flame surfaces62are formed in the combustion chamber50. At the startup, the staging is performed and the fuel injection range (area) is enlarged in stages as explained in the first embodiment.

As above, the present invention is applicable also to the multiple injection gas turbine combustors with no problems.

Other Examples

It is to be noted that the present invention is not limited to the aforementioned embodiments, but covers various modifications. While, for illustrative purposes, those embodiments have been described specifically, the present invention is not necessarily limited to the specific forms disclosed. Thus, partial replacement is possible between the components of a certain embodiment and the components of another. Likewise, certain components can be added to or removed from the embodiments disclosed.

While the fuel nozzles30and the air holes31A are arranged coaxially with each other in the above embodiments, the central axes of the fuel nozzles30and the central axes of the air holes31A do not need to perfectly coincide with each other as long as coaxial jets of fuel and air can be formed. It is sufficient if each fuel nozzle30extends toward or points the corresponding air hole31A.

While the fuel nozzles30, the air holes31A and the air holes31B are formed around the whole circumference of each annular row in the above embodiments, the essential effects of the present invention are precisely controlling the fuel-air ratio of each air hole and thereby achieving stable combustion in a series of operation steps from the ignition of the gas turbine to the full load operation while also reducing the NOx emission. Therefore, it is not absolutely necessary to form the fuel nozzles30, the air holes31A and the air holes31B around the whole circumference of each annular row as long as the essential effects are achieved. For example, there are cases where the fuel nozzles30, the air holes31A and the air holes31B are arranged in part of an annular row in the peripheral part.

While eight air hole rows are formed through the base plate32and the turning plate33in the first through fifth embodiments, the number of air hole rows formed through the base plate32and the turning plate33is not limited to eight as long as the aforementioned essential effects of the present invention are achieved. For example, the number of air hole rows formed through the base plate32and the turning plate33can be seven or less, or nine or more.

While the partition wall parts37are formed on the base plate32in the above embodiments, the partition wall parts37do not necessarily have to be formed on the base plate32as long as the aforementioned essential effects of the present invention are achieved. For example, the partition wall parts37may be formed on the turning plate33, or independently of the base plate32and the turning plate33.

While the number of the air holes31A of the base plate32and the number of the air holes31B of the turning plate33are equal to each other in the above embodiments, the numbers of the air holes31A and31B do not necessarily have to be set equal to each other as long as the aforementioned essential effects of the present invention are achieved. For example, the number of the air holes31B may be set larger than that of the air holes31A, or smaller than that of the air holes31A

While the tip ends of the fuel nozzles30are apart from the inlets of the air holes31A of the base plate32in the above embodiments, the tip ends of the fuel nozzles30do not necessarily have to be arranged apart from the inlets of the air holes31A as long as the aforementioned essential effects of the present invention are achieved. For example, the tip ends of the fuel nozzles30may also be inserted into the air holes31A. In this case, the mixing of the fuel ejected from each fuel nozzle30and the air is promoted further thanks to an increase in the flow velocity of the air jet35caused by a decrease in the inlet area of the air hole31A.

While the tip end of each fuel nozzle30is formed in a simple cylindrical shape in the above embodiments, it is also possible to arrange a protrusion at the tip end of each fuel nozzle30to cause a vortical flow in the fuel ejected and thereby further promote the mixing of fuel and air as long as the aforementioned essential effects of the present invention are achieved. The fuel nozzle30may also be formed to have two or more fuel ejection holes so as to enhance the dispersion of the fuel and thereby further promote the mixing of fuel and air.

DESCRIPTION OF REFERENCE CHARACTERS