JP4400314B2 - Gas turbine combustor and fuel supply method for gas turbine combustor - Google Patents

Description

  The present invention relates to a gas turbine combustor and a fuel supply method for the gas turbine combustor.

  In general, in a gas turbine combustor, reducing the emission amount of nitrogen oxides (hereinafter referred to as NOx) has become a major issue from the viewpoint of global environmental conservation. One method of reducing NOx emissions in a gas turbine combustor using gaseous fuel is a lean premixed combustion method in which fuel and combustion air are mixed in advance by a premixer and then burned. However, the lean premixed combustion method has poor combustion stability compared to the diffusion combustion method, causing combustion oscillation in which the internal pressure of the combustor periodically fluctuates, or flame return in which the flame flows backward in the premixer May cause.

  Also, when liquid fuel is used, pre-evaporation premix combustion method in which liquid fuel is sprayed from a fuel nozzle into high-temperature combustion air, atomized, and liquid fuel is evaporated and then mixed with combustion air for combustion There is. However, in this combustion method as well, in the case of gaseous fuel, premixed combustion may cause combustion vibration and flame return, and liquid fuel ejected into high-temperature air is preliminarily generated without an ignition source. There is also the possibility of a spontaneous ignition phenomenon that ignites inside the mixer.

  As a conventional technique related to such a gas turbine combustor for reducing the NOx emission amount, for example, Japanese Patent Application Laid-Open No. H10-228707 adds to the dilution air hole for introducing the combustion air into the combustion chamber on the downstream side of the combustion chamber. It is disclosed that low-NOx combustion is performed by installing a cooking burner and controlling the combustion ratio with the main burner installed upstream of the combustion chamber.

Japanese Patent Application Laid-Open No. 8-210441

  In the combustion system disclosed in Patent Document 1, it is possible to reduce the NOx emission amount by controlling the combustion ratio of the main burner and the additional cooking burner. However, in the additional cooking burner, the fuel is directly diffused and supplied from the fuel nozzle into the air flow flowing into the combustion chamber from the dilution air hole, so that the mixture of air and fuel is mixed before reaching the combustion zone. However, if the fuel flow rate of the additional cooking burner is increased, a high temperature combustion region may be formed in the combustion region of the additional cooking burner and the NOx emission amount may increase rapidly.

  Also, when using liquid fuel, as with gaseous fuel, mixing and evaporation of the fuel droplets ejected from the fuel nozzle and the air flowing in from the dilution air holes are not sufficiently promoted, so additional cooking is required. When the fuel flow rate of the burner is increased, the ejected fuel droplets do not evaporate and mix, resulting in a combustion state such as diffusion combustion, a high-temperature combustion region is formed in the combustion region of the top-burning burner, and the NOx emissions increase rapidly. it was thought.

  An object of the present invention is to provide a gas turbine combustor that reduces NOx emissions.

The present invention forms , on the inner cylinder wall surface on the downstream side of the combustion burner , at least one inflow hole through which a mixture of combustion air and fuel can flow into the inner cylinder ,
A mixing chamber formed in a hollow conical shape that expands in the flow direction is disposed at the position where the inflow hole is formed, and a plurality of small air inflow holes for introducing combustion air into the mixing chamber are provided on the outer peripheral side of the mixing chamber And a second fuel nozzle that ejects fuel in a direction substantially coaxial with the small air inflow hole is provided upstream of the small air inflow hole .

  According to the present invention, it is possible to provide a gas turbine combustor that reduces NOx emissions.

According to the above object the present invention, a first fuel nozzle for injecting fuel, and the air ejection holes located on the outer peripheral side of the fuel nozzles of the first, ejecting combustion air, the first fuel nozzle And a gas turbine combustor having an inner cylinder located downstream of the combustion burner having the air ejection holes and capable of mixing combustion of fuel and combustion air therein, from the first fuel nozzle This is solved by forming at least one inflow hole through which the air-fuel mixture of combustion air and fuel can flow into the inside of the inner cylinder on the inner cylinder wall surface on the downstream side.

  In the case of the combustor configured as in the present invention, the fuel is ejected from the first fuel nozzle and mixed with the combustion air inside the inner cylinder to perform combustion, but the second fuel nozzle is the first fuel nozzle. Since it is installed on the downstream side of the fuel nozzle, the combustion gas generated by the first fuel nozzle is in a complete combustion state with no unburned components at the installation position of the second fuel nozzle.

  For example, when liquid fuel is ejected from the second fuel nozzle, the liquid fuel ejected from the second fuel nozzle and the combustion air are sufficiently premixed in the mixing chamber and then supplied into the completely burned combustion gas. Premixed combustion is performed. The liquid fuel ejected from the second fuel nozzle evaporates while mixing with high-temperature combustion air inside the mixing chamber to become a premixed gas, and further gradually becomes premixed combustion when heated to a combustion temperature or higher by the combustion gas. To start. For this reason, in the combustor according to the present invention, the fuel ejected from the second fuel nozzle is in a combustion state such as premixed combustion in which the fuel is sufficiently mixed, so that the NOx emission amount is reduced.

In the present invention, the first fuel nozzle that ejects fuel, the air ejection hole that is located on the outer peripheral side of the first fuel nozzle and ejects combustion air, the first fuel nozzle, and the air A gas turbine combustor, which is located downstream of a combustion burner having an ejection hole and includes an inner cylinder capable of mixed combustion of fuel and combustion air therein, and a closing plate for fixing the first fuel nozzle. And at least one inflow hole through which a mixture of combustion air and fuel flowing outside the inner cylinder can flow into the inner cylinder is formed on the inner cylinder wall surface on the downstream side of the combustion burner, A mixing chamber formed in a hollow conical shape that expands in the flow direction is disposed at the position where the inflow hole is formed, and a plurality of small air inflow holes for introducing combustion air into the mixing chamber are provided on the outer peripheral side of the mixing chamber. And fuel is ejected to the upstream side of the mixing chamber It was placed a second fuel nozzle.

  The mixing chamber is formed in a hollow conical shape that expands in the flow direction of combustion air, that is, in the ejection direction of the second fuel nozzle. Therefore, for example, when liquid fuel is ejected from the second fuel nozzle, the ejected fuel droplets are mixed into the mixing chamber by adjusting the ejection angle of the second fuel nozzle and the opening angle that expands in the flow direction of the mixing chamber. Collision and adhesion to the inner wall can be prevented, and the occurrence of coking can be suppressed.

  In addition, the mixing chamber wall has a plurality of small air inflow holes for introducing combustion air into the mixing chamber, so that the fuel droplets collide with the mixing chamber wall by the air flow flowing in from the small air inflow holes. Adhesion can be prevented.

Further, since the fuel droplets ejected from the second fuel nozzle can be atomized by the shearing force of the airflow flowing in from the small air inflow hole, the evaporation / mixing of the fuel droplets is promoted,
The amount of NOx emission can be reduced.

Furthermore, in the present invention, a fuel nozzle that ejects liquid fuel and gaseous fuel, an air ejection hole that is located on the outer peripheral side of the fuel nozzle and ejects combustion air, the first fuel nozzle, and the air ejection A gas turbine combustor comprising an inner cylinder located downstream of a combustion burner having a hole and capable of mixed combustion of fuel and combustion air therein, and a closing plate for fixing the fuel nozzle; The inner space of the combustion burner is formed in a hollow conical shape that expands in the flow direction, and a plurality of air inlet holes for introducing combustion air into the combustion burner are formed on the outer peripheral side of the combustion burner, and the upstream side of the combustion burner Is provided with a first liquid fuel nozzle that ejects liquid fuel, and a first gas fuel nozzle that ejects gaseous fuel is installed on the upstream side facing the air inflow hole, and on the downstream side of the combustion burner. Inside Formed on the wall surface is at least one inflow hole through which the mixture of combustion air and fuel flowing outside the inner cylinder can flow into the inner cylinder, and expands in the flow direction to the position where the inflow hole is formed A mixing chamber formed in a hollow conical shape is formed, a plurality of small air inflow holes for introducing combustion air into the mixing chamber are formed on the outer peripheral side of the mixing chamber, and liquid fuel is formed on the upstream side of the mixing chamber Since the second liquid fuel nozzle for spraying is installed and the second gaseous fuel nozzle for ejecting gaseous fuel is installed on the upstream side facing the small air inflow hole, the NOx emission amount can be suppressed.

  That is, since the gaseous fuel nozzle is installed at each position facing the small air inflow hole of the combustion burner and the mixer, and the gaseous fuel is configured to be ejected in a direction substantially coaxial with the small air inflow direction. Is mixed with air inside the small air inflow hole, and mixing is further promoted by vortices generated when the small air inflow hole is ejected into the combustion burner or into the mixing chamber. Further, in the combustion burner or in the mixing chamber, Since the air-fuel mixtures ejected from the small air inflow holes collide with each other, the mixing is greatly promoted.

  Furthermore, in the present invention, a guide ring extending in the axial center of the inner cylinder is installed in the inflow hole, and an extension direction of the guide ring is deflected in an axial direction or a tangential direction of the inner cylinder, so that the second The fuel jet direction of the fuel nozzle is configured to be substantially coaxial with the air flow flowing into the inner cylinder from the guide ring.

  As a result, for example, when liquid fuel is ejected from the second fuel nozzle, the pre-evaporation / premixing distance between the fuel droplets ejected from the second fuel nozzle and the combustion air becomes longer, so that mixing is promoted and NOx is discharged. The amount can be reduced.

  Moreover, since the penetration force of the premixed gas flowing into the inner cylinder is increased by installing the guide ring, the combustion gas is stirred by the premixed gas flowing in from the guide ring, and the combustion gas at the outlet of the combustion chamber Uniform temperature distribution.

  Further, if a guide ring extending in the tangential direction of the inner cylinder is installed in the inflow hole, a swirl flow is formed inside the inner cylinder by the combustion air that has flowed into the inner cylinder. The gas is agitated, the combustion gas temperature distribution at the combustor outlet is made uniform, and the combustion stability can be improved.

  Furthermore, it is possible to ensure combustion stability by deflecting the extending direction of the guide ring in the axial direction of the inner cylinder.

  In the combustor according to the present invention, the premixed gas generated in the mixing chamber is injected into the complete combustion region on the upstream side of the combustor to perform premixed combustion. However, a certain time (distance) is required for the fuel ejected from the first fuel nozzle to burn completely. Therefore, the guide ring extension direction is deflected in the axial direction downstream side of the inner cylinder, and the fuel supplied from the second fuel nozzle is supplied so as to be substantially coaxial with the combustion air flow flowing in from the guide ring. Thus, the position where the fuel supplied from the second fuel nozzle is mixed with the fuel air and evaporated to start combustion can be moved to the downstream side of the inner cylinder. Accordingly, combustion stability can be ensured and NOx emission can be reduced.

  Furthermore, in the present invention, the mixing chamber disposed at the position of the inflow hole, wherein the first fuel nozzle that ejects fuel into the inner cylinder upstream of the combustion burner is a first gaseous fuel nozzle. The second fuel nozzle that ejects fuel into the interior of the nozzle was used as a second gaseous fuel nozzle.

  Thus, fuel is ejected from the first gaseous fuel nozzle and mixed with combustion air inside the inner cylinder for combustion, but the second gaseous fuel nozzle is installed downstream of the first gaseous fuel nozzle. Therefore, the combustion gas generated by the first gaseous fuel nozzle is completely burned without any unburned components at the installation position of the second gaseous fuel nozzle. Similarly, when both the first fuel nozzle and the second fuel nozzle are liquid fuel nozzles, it is possible to achieve a complete combustion state with no unburned components.

  In the present invention, the gaseous fuel and combustion air ejected from the second gaseous fuel nozzle are sufficiently premixed in the mixing chamber and then supplied into the completely burned combustion gas to perform premixed combustion. The gaseous fuel ejected from the second gaseous fuel nozzle is mixed with high-temperature combustion air inside the mixing chamber to become a premixed gas, and further, when heated to a combustion temperature or higher by the combustion gas, premixed combustion is started. For this reason, in the combustor according to the present invention, the gaseous fuel ejected from the second gaseous fuel nozzle is in a combustion state such as premixed combustion in which the gaseous fuel is sufficiently mixed, so that the NOx emission amount is reduced.

  Embodiment 1 will be described below with reference to the drawings. FIG. 1 shows a main part of a gas turbine plant equipped with a combustor according to the present invention. This gas turbine plant mainly includes a turbine 2, a compressor 1 connected to the turbine 2 to obtain compressed air for combustion, and a combustor 3, and the compressed air 4 discharged from the compressor 1 is burned as combustion air. Combusted together with fuel in a combustion chamber 6 led to the combustor 3 and formed inside the combustor inner cylinder 5. The combustion gas 7 generated by the combustion is jetted to the turbine 2 through the transition piece 8 and drives the turbine 2. And generally it is comprised so that it may generate electric power with the generator connected with the gas turbine.

The main configuration of the combustor 3 includes an inner cylinder 5 that generates combustion gas, a main fuel nozzle 9 that is a first fuel nozzle that ejects fuel, and a liquid fuel supply system 10 that is connected to the main fuel nozzle 9. A closing plate includes a swirler 11 that generates a swirl component in the combustion air supplied to the combustion chamber 6, a louver 12 that supports the swirler 11 and the inner cylinder 5, and an ignition plug 13 that ignites the combustor. It is sealed with a certain end cover 14 and outer cylinder 15.

The first embodiment is located on the downstream side of the swirler 11, the inner cylinder 5 capable of mixed combustion of fuel and combustion air, and the mixture of fuel and combustion air in the combustion chamber 6 inside the inner cylinder 5. Were formed, and a mixing chamber 17 was installed at the position of each inflow hole 16. Further, a sub fuel nozzle 18 as a second fuel nozzle is installed in the outer cylinder 15 facing the mixing chamber 17, and a liquid fuel supply system 19 for supplying liquid fuel to the sub fuel nozzle 18 is installed. In the present embodiment, as an example, a case where both the liquid fuel is used as the fuel ejected from the first fuel nozzle and the second fuel nozzle will be described.

  FIG. 2 shows an enlarged detailed view of the combustor 3. FIG. 3 is a longitudinal sectional view showing the positions of the auxiliary fuel nozzles 18a and 18b shown in FIG.

  As shown in FIGS. 2 and 3, in this embodiment, an annular gap between the outer cylinder 15 and the inner cylinder 5 flows down to the wall surface of the inner cylinder 5 on the downstream side L <b> 1 from the main fuel nozzle 9, and the outer side of the inner cylinder 5 is disposed. Six inflow holes 16 for introducing the flowing combustion air into the combustion chamber 6 inside the inner cylinder are formed in the circumferential direction of the inner cylinder 5. A hollow conical mixing chamber 17 that expands in the flow direction is installed at the position of each inflow hole 16, and an auxiliary cylinder 15 that faces the mixing chamber 17 supplies liquid fuel to the inside of the mixing chamber 17. A fuel nozzle mounting seat 20 for installing the fuel nozzle 18 was installed. The sub fuel nozzles 18a and 18b are fixed to the fuel nozzle mounting seat 20, and the liquid fuel supply system 19a is provided for the three sub fuel nozzles 18a, and the liquid fuel supply system 19b is provided for the other three sub fuel nozzles 18b. Connecting.

  FIG. 4 shows the supply fuel flow rate of each fuel supply system with respect to the gas turbine load, and the operation and effect of each component with respect to the gas turbine load will be described with reference to FIGS.

From start-up / acceleration to low load of the gas turbine, fuel is supplied only from the fuel supply system 10 to the main fuel nozzle 9, and fuel droplets ejected from the main fuel nozzle 9 and combustion air flowing from the swirler 11 are Mixing in the combustion chamber 6 in the inner cylinder generates combustion gas. When the flow rate of fuel supplied to the main fuel nozzle 9 is increased, a complete combustion region in which unburned components are not generated can be generated at the position where the sub fuel nozzles 18a and 18b are provided at a distance L1 downstream from the main fuel nozzle 9. it can.

Further, since the rate of change in the flow rate of combustion air supplied to the combustor is large during the period from start-up / acceleration of the gas turbine to a low load, diffusion with excellent combustion stability performed by the main fuel nozzle 9 and the swirler 11 Combustion method is effective.

When the gas turbine reaches a low load, fuel is supplied from the liquid fuel supply system 19a to the three sub fuel nozzles 18a. The fuel droplets ejected from the auxiliary fuel nozzle 18a are mixed with the combustion air inside the mixing chamber 17 and flow into the combustion chamber 6 from the inflow hole 16, so that the mixing of the fuel droplets and the combustion air is promoted. Evaporate with hot combustion air to produce a premixed gas. When this premixed gas is overheated by the combustion gas, preevaporated premixed combustion is gradually started from the region where the temperature becomes higher than the flammable temperature, so that a high temperature combustion region is unlikely to be generated and NOx emission can be reduced. It becomes.

  From a low load to an intermediate load, the fuel flow rate is increased by the liquid fuel supply system 19a according to the load of the gas turbine. When the load of the gas turbine becomes an intermediate load, the fuel is supplied to the other three sub fuel nozzles 18b by the liquid fuel supply system 19b, and an almost equal fuel flow rate is preliminarily ejected from the six sub fuel nozzles at the rated load. It is configured to perform evaporation premixed combustion.

  In order to reduce the NOx emission amount by the pre-evaporation premixed combustion, the fuel concentration which is a ratio of the combustion air flow rate flowing from the inflow hole and the fuel flow rate ejected from the sub fuel nozzle is important. When the fuel concentration increases, that is, when the fuel flow rate increases with respect to the inflowing combustion air flow rate, a high-temperature combustion region is generated in the region where pre-evaporation premixed combustion is performed, and NOx emissions may increase. .

  Therefore, in this embodiment, in order to prevent the fuel concentration from becoming too high, the number of liquid fuel nozzles that supply fuel is controlled according to the load, and the fuel flow rate of each liquid fuel nozzle is equal at the rated load. It is comprised so that it may become.

  Further, in the gas turbine combustor of this embodiment, the combustion gas temperature distribution at the combustor outlet must be made uniform in order to ensure the reliability of the turbine blades located on the downstream side of the combustor. This is because when a high temperature region is generated in the combustion gas temperature distribution at the combustor outlet, cracks and the like are generated in the turbine blades exposed to the high temperature combustion gas. However, in this embodiment, the combustion air or premixed gas flows into the combustion chamber from the plurality of inflow holes, so the combustion gas in the combustion chamber is agitated and the combustion gas temperature distribution at the combustor outlet is Therefore, the reliability of the entire gas turbine can be improved.

  5 to 7 are detailed views of the vicinity of the mixing chamber 17 and the auxiliary fuel nozzle 18a, FIG. 5 is a cross-sectional view, and FIG. 6 is a cross-sectional view of the position of a small air inflow hole 33 formed on the upstream side of the mixing chamber 17. FIG. 7 shows a cross-sectional view of the position of the small air inflow hole 31 formed on the downstream side of the mixing chamber 17.

  Further, in this embodiment, a typical pressure jet type spiral liquid fuel nozzle is applied to the auxiliary fuel nozzle 18a. The auxiliary fuel nozzle 18 a includes a nozzle tip 22 in which a swirl chamber 21 is formed, a closing plate 23 that closes one end of the nozzle tip, and a nozzle cap 24 that houses the nozzle tip 22 and the closing plate 23. The liquid fuel 25 flows into the swirl chamber 21 from the fuel inflow hole 26 formed in the nozzle tip 22, and is sprayed into the mixing chamber 17 as indicated by an arrow 28 by the centrifugal force acting by the swirl force from the fuel spray hole 27. Turn into.

  The inner peripheral wall 29 forming the mixing chamber 17 is formed in a hollow cone shape that expands in the fuel droplet ejection direction, and a plurality of small air inflows for introducing the combustion air 34 into the mixing chamber wall 30 into the mixing chamber. Holes 31, 32, and 33 are formed, and a fuel inflow hole 35 of a liquid fuel nozzle that sprays liquid fuel is installed on the upstream side of the hollow conical mixing chamber 17.

6 and 7 are longitudinal sectional views of the small air inflow holes 33 and 31. In the small air inflow hole 33 close to the auxiliary fuel nozzle 18a, the small air inflow hole 33 is formed at a position offset by a distance X in the circumferential direction from the axial center of the mixing chamber 17, and in the downstream small air inflow hole 31, the mixing is performed. It formed toward the axial center of the chamber 17.

  In this embodiment, as shown in FIG. 6, at the position of the small air inflow hole 33 upstream of the mixing chamber where the fuel droplets 36 are sprayed, a plurality of small air inflow holes are provided over the entire circumference of the mixing chamber peripheral wall 29. 33 is formed, and the combustion air 34 flows into the mixing chamber. Therefore, in this region, there is no stagnation region where the fuel droplets 36 easily adhere, and coking can be prevented.

  In the small air inflow hole 31 on the downstream side of the mixing chamber, since the small air inflow hole 31 flows toward the axial center of the mixing chamber 17, mixing with the droplets atomized on the upstream side of the mixing chamber is promoted. When the swirl component acts on the air flow flowing in on the downstream side of the mixing chamber, the penetrating force of the air flow flowing in from the inflow hole 16 is attenuated, and the action of stirring the combustion gas is reduced. The swirl component does not act on the air flow.

  Furthermore, in this embodiment, the inner wall 29 of the mixing chamber 17 is formed in a hollow conical shape that expands in the flow direction, and the swirling component does not act on the air flow at the outlet of the mixing chamber 17, so the mixing chamber 17 It is possible to prevent the occurrence of a flashback phenomenon in which the flame flows backward, and to improve the reliability of the entire gas turbine.

  Example 2 will be described with reference to FIG. In the second embodiment, a guide ring 39 extending to the axial center of the inner cylinder 5 is installed at the position of the inflow hole 16, and other main components are the same as those of the first embodiment.

  In the present embodiment, the guide ring 39 extending in the axial center portion of the inner cylinder 5 is installed, so that the mixing / evaporation distance between the fuel droplets sprayed from the auxiliary fuel nozzle 40 and the combustion air flowing into the mixing chamber 17 is set. Since it can be lengthened, mixed evaporation is promoted, and further reduction of NOx emission can be expected.

  Further, by installing the guide ring 39, when the premixed gas 41 is ejected into the combustion chamber 6, it is possible to prevent the premixed gas jet from spreading and increase the penetration force. If the spread of the premixed gas jet is suppressed, the time (distance) until the premixed gas 41 is heated to the combustible temperature by the combustion gas becomes longer, so that mixing with the fuel sprayed in the combustion air is promoted. Reduction of NOx emissions can be expected.

  Moreover, since the penetration force of the premixed gas 41 is increased, the action of stirring the combustion gas is increased, so that the combustion gas temperature distribution at the combustor outlet is uniform and the reliability of the gas turbine blade is improved.

  Embodiment 3 will be described with reference to FIG. In the third embodiment, a guide ring 42 that is offset to the outer peripheral side with respect to the axial center portion of the inner cylinder 5 is installed at the position of the inflow hole 16, and other main components are the same as in the first embodiment. It is the same.

  The guide ring 42 is attached offset to the outer peripheral side with respect to the axial center of the combustion chamber 6, and the auxiliary fuel nozzle 43 is installed in a substantially coaxial direction with the guide ring 42. For this reason, the swirl component acts on the combustion chamber 6 by the premixed gas 44 flowing into the combustion chamber 6. When the swirl component acts on the combustion gas, the combustion gas temperature distribution at the combustor outlet is further uniformed, which is advantageous for improving the reliability of the gas turbine blade.

Example 4 will be described with reference to FIGS. FIG. 10 shows a combustion burner 46 having a main fuel nozzle 45 according to the fourth embodiment. A swirler 52 is arranged on the outer peripheral side of the main fuel nozzle 45. The main fuel nozzle 45 is provided with a pressure jet type spiral liquid fuel nozzle 47 at the center of its axis, and a gaseous fuel nozzle 48 for jetting gaseous fuel is arranged on the outer peripheral side thereof.

The gaseous fuel is supplied from a gaseous fuel supply system 49, and is ejected from the fuel ejection hole 50 of the gaseous fuel nozzle 48 to the downstream side of the swirler 52 of the combustion burner 46, and the combustion air 51 and the combustion chamber flow down the swirler 52. 6 is mixed to produce combustion gas.

  FIG. 11 shows the sub fuel nozzle 53 of the fourth embodiment. Like the main fuel nozzle 45, the gaseous fuel nozzle 55 that ejects gaseous fuel to the outer peripheral side of the pressure ejection type spiral liquid fuel nozzle 54. Is arranged. The gaseous fuel supplied to the auxiliary fuel nozzle 53 is supplied from the auxiliary gas fuel supply system 56 and is ejected from a plurality of fuel ejection holes 57 formed in the gaseous fuel nozzle 55. The gaseous fuel ejected from the gaseous fuel nozzle 55 is mixed with the combustion air flowing in from the small air inflow hole of the mixing chamber 17 to generate a premixed gas. At this time, as described in the first embodiment, the combustion air flowing into the mixing chamber 17 has different inflow directions at each position of the small air inflow hole. Mixing with fuel is promoted. The premixed gas sufficiently mixed in the mixing chamber 17 flows out into the combustion chamber 6 and performs premixed combustion from the region heated to the combustion temperature or higher by the combustion gas, so that a high temperature combustion region is generated. This makes it possible to reduce NOx emissions.

  In the fourth embodiment, the case where the gaseous fuel is used has been described. However, effects such as prevention of the flame return phenomenon and uniformity of the combustion gas temperature distribution at the combustor outlet described in the first embodiment are described in the first embodiment. It is the same.

A fifth embodiment will be described with reference to FIGS. FIG. 12 shows a combustion burner having a main fuel nozzle, in which an inner peripheral wall 61 is disposed on the outer peripheral side of the liquid fuel nozzle 58 which is the first liquid fuel nozzle, and further, a gas which is the first gaseous fuel nozzle on the outer peripheral side. A fuel nozzle 60 is installed.

  An inner peripheral wall 61 formed in the inner space of the combustion burner 59 is formed in a hollow conical shape that expands in the flow direction, and burns a plurality of small air inflow holes 63, 64, 65 for introducing combustion air into the combustion burner interior 62. A gas fuel nozzle 60, which is a first gas fuel nozzle that ejects gaseous fuel, is installed on the upstream side facing the small air inflow holes 63, 64, 65 while being formed on the inner peripheral wall 61 of the burner.

  Further, as shown in FIG. 6 of the first embodiment, the small air inflow holes 63, 64, 65 are formed at positions offset from the axial center of the combustion burner interior 62 by a distance X in the circumferential direction. The swirl component acts on the interior 62 by the combustion air flowing in from the small air inflow holes 63, 64, 65.

  According to the fifth embodiment, a plurality of air inflow holes 63 are formed over substantially the entire circumference of the inner peripheral wall 61 of the combustion burner 59 on the upstream side of the combustor where fuel droplets are ejected. And since combustion air flows in toward the ejection center of the liquid fuel nozzle 58, which is the first liquid fuel nozzle, there is no stagnation region where fuel droplets are likely to adhere in this region, thus preventing the occurrence of coking. be able to.

  Further, when a pressure jet type spiral liquid fuel nozzle is used as the liquid fuel nozzle 58, the fuel droplets ejected from the liquid fuel nozzle 58 are ejected to the outer peripheral side by the action of centrifugal force. On the other hand, since the combustion air flows toward the substantial ejection center of the liquid fuel nozzle 58, the shear force of the air flow can be applied to the fuel droplets in a state close to the maximum. In addition to preventing the fuel from colliding with the inner peripheral wall 61 of the combustion burner, the injected fuel droplets can be atomized to promote mixing with the combustion air, and the NOx emission amount can be suppressed.

  Furthermore, in this embodiment, the small air inflow holes 64 and 65 on the downstream side of the fuel burner 59 are also formed at positions offset from the axial center of the combustion burner interior 62 by a distance X in the circumferential direction. A strong swirling component is generated at the outlet of the combustion chamber, and the stability of combustion can be improved.

  And according to the present Example, since the gaseous fuel nozzle 60 which ejects gaseous fuel was installed in the upstream which opposes the small air inflow holes 63, 64, 65, it is possible to perform the combustion which suppressed NOx emission amount. It becomes. That is, the gaseous fuel nozzle 60 is installed at a position opposite to the small air inflow holes 63, 64, 65, and is configured so that the gaseous fuel is ejected in a direction substantially coaxial with the air inflow direction. Mix with combustion air inside the air inlet. Mixing of the air-fuel mixture mixed inside the small air inlet hole is further promoted by vortices generated when the air mixture is ejected from the small air inlet hole into the combustion burner interior 62. Further, in the combustion burner interior 62, the air-fuel mixtures ejected from the small air inflow holes collide with each other, so that the mixing is greatly promoted and the NOx emission amount can be suppressed.

FIG. 13 shows a sub-fuel nozzle 66 that is a second liquid fuel nozzle 66, a mixing chamber 67, a gaseous fuel nozzle 68 that is a second gaseous fuel nozzle, and a fuel manifold that supplies fuel to each gaseous fuel nozzle 68 in the fifth embodiment. The other components are the same as those of the second embodiment.

  In the present embodiment, a gaseous fuel nozzle 68 that is a second gaseous fuel nozzle that ejects gaseous fuel is installed on the upstream side facing the small air inflow holes 70 formed in the mixing chamber 67, and the gaseous fuel is small air. Since the gas fuel is configured to be ejected in a direction substantially coaxial with the inflow direction, the gaseous fuel mixes with air inside the small air inflow hole 70 and is generated when the gas fuel is ejected from the small air inflow hole 70 into the mixing chamber. Further, the mixing is further promoted, and further, since the air-fuel mixture ejected from the small air inflow holes collides with each other in the inside of the mixing chamber, the mixing is greatly promoted, so that the NOx emission amount can be greatly reduced.

  Example 6 will be described with reference to FIG. In this embodiment, a two-fluid nozzle that atomizes liquid fuel by atomizing air is used for the auxiliary fuel nozzle, and other main components are the same as those of the other embodiments.

  The auxiliary fuel nozzle 97 is composed of a nozzle core 71 and a nozzle cap 72, and the nozzle core 71 is formed with an injection hole 75 for spraying the liquid fuel 74 in the mixing chamber 73 formed in the gap with the nozzle cap 72. The liquid fuel sprayed from the nozzle hole 75 is internally mixed with the spray air 76 in the mixing chamber 73, sprayed from the annular gap 77 formed at the downstream end of the sub fuel nozzle 97, and atomized by the shearing force of the spray air. .

  The pressure spray type spiral fuel nozzle used in the other embodiments applies a high pressure to the liquid fuel and atomizes it by the difference in spray speed between the droplet and the spraying place of the droplet, so it is supplied to the fuel nozzle. When the fuel flow rate is small, the fuel supply pressure tends to be low and the atomization characteristics tend to deteriorate. When the atomization of the fuel droplets deteriorates, mixing with the combustion air becomes worse and the time required for evaporation becomes longer. As a result, there is a possibility that the amount of NOx emission increases.

  However, in Example 6, since the liquid fuel is atomized by the atomized air, the atomization characteristics are excellent as compared with the pressure spray type liquid fuel nozzle regardless of the fuel flow rate. Therefore, mixing / evaporation with the combustion air is promoted at a short mixing distance, and an effect of reducing the NOx emission amount in a wide operating range regardless of the flow rate of the liquid fuel can be expected.

  In addition, a liquid fuel supply system 78, a gaseous fuel supply system 79, and a spray air compressor 80 are connected to the auxiliary fuel nozzle 97 via check valves 81, 82, and 83, respectively, It can be switched depending on the application.

When liquid fuel is used, the liquid fuel 74 is supplied from the liquid fuel supply system 78 to the nozzle core 71 via the check valve 81, and the liquid is supplied by the spray air supplied from the atomizing air compressor 80 via the check valve 83. Atomize the fuel. At this time, since the check valve 81 is installed in the liquid fuel pipe, it is possible to prevent the spray air 76 from flowing back to the liquid fuel supply system 78. Similarly, since the check valves 82 and 83 are installed in each pipe, the liquid fuel does not flow back to the gaseous fuel supply system 79 and the atomizing air compressor 80.

  On the other hand, when gaseous fuel is used, when gaseous fuel is supplied from the gaseous fuel supply system 79 to the nozzle core 71, gaseous fuel and sprayed air are mixed in the internal mixing chamber 73 of the auxiliary fuel nozzle 97, and the downstream end of the auxiliary fuel nozzle 97 is mixed. Since the premixed gas is ejected from the formed annular gap 77, it is expected that the mixing is promoted and the NOx emission amount is reduced.

Example 7 will be described with reference to FIG. In the seventh embodiment, the first-stage sub fuel nozzle 84 is installed at a position in the axial direction L2 from the main fuel nozzle 98, and the second-stage sub fuel nozzle 85 is installed at a position in the axial direction L3 from the sub fuel nozzle 84. Other main components are the same as in the other embodiments.

  As described in the first embodiment, in order to completely burn the premixed gas generated by the fuel supplied from the fuel nozzle and the combustion air, the premixed gas is set on the upstream side where the premixed gas is generated. A sufficient amount of combustion gas is required for complete combustion. If the amount of heat of the upstream combustion gas is less than the supplied premixed gas flow rate, the premixed gas cannot be heated above the flammable temperature, causing unburned components and reducing combustion efficiency. appear.

  In this embodiment, the combustion gas necessary for complete combustion is generated by the main fuel nozzle 98, but the main fuel nozzle 98 is operated in a wide operating range from the start-up / speed-up of the gas turbine to the rated load. In many cases, a diffusion combustion method with excellent combustion stability is employed. However, since the diffusion combustion method has a large amount of NOx emission, the ratio of the diffusion combustion flow rate to the total combustion flow rate dominates the NOx emission characteristic of the entire combustor.

  As in other embodiments, in order to satisfy the combustion efficiency by introducing the mixture for premix combustion at one place in the axial direction of the combustor, the main fuel with respect to the premixed combustion amount burned by the sub fuel nozzle Since the combustion rate of the diffusion combustion flow rate combusted by the nozzle increases, it is conceivable that the reduction rate of the NOx emission amount is suppressed.

  For this reason, in the seventh embodiment, the auxiliary fuel nozzles 84 and 85 and the inflow holes 86 and 87 are divided and installed at different positions in the combustion chamber axial direction to divide the fuel flow rate for premixed combustion. .

The combustion gas necessary for the first stage premixed combustion performed in the region of the auxiliary fuel nozzle 84 and the inflow hole 86 is generated by diffusion combustion of the main fuel nozzle 98. Since the combustion gas necessary for the second stage premixed combustion performed in the region of the auxiliary fuel nozzle 85 and the inflow hole 87 can use the combustion gas generated in the first stage premixed combustion, The diffusion combustion ratio to the combustion amount is reduced,
The amount of NOx emission can be greatly reduced.

  Example 8 will be described with reference to FIG. In the eighth embodiment, a guide ring 89 extending to the axial center of the combustion chamber 6 is installed on the downstream side in the axial direction from the main fuel nozzle 88. Then, a guide ring 90 that deflects toward the downstream side of the combustor while extending in the axial center direction of the combustion chamber 6 is installed at a position where the guide ring 89 and the combustor axial direction are the same and different in the circumferential direction of the inner cylinder 5. In the upstream positions of the guide rings 89 and 90, mixing chambers 91 and 92 and auxiliary fuel nozzles 93 and 94 capable of supplying gaseous fuel and liquid fuel are installed. The auxiliary fuel nozzle 93 is supplied with fuel from the fuel supply system 95 and the auxiliary fuel nozzle 94 is supplied with fuel from the fuel supply system 96, respectively, and other main components are the same as those in the first embodiment.

  In the gas turbine combustor to which the present embodiment is applied, it may be difficult to divide the fuel nozzle in the axial direction as shown in the seventh embodiment due to the structure of the gas turbine. It becomes effective.

That is, in this embodiment, the combustion gas generated by the main fuel nozzle burns the fuel ejected from the auxiliary fuel nozzle 93 by premixed combustion. Next, since the combustion air flowing in from the guide ring 90 deflected downstream and the premixed gas generated by the fuel ejected from the auxiliary fuel nozzle 94 flow down toward the downstream side of the combustion chamber 6, Premixed combustion can be started downstream of the region where premixed combustion is performed by the auxiliary fuel nozzle 93, and the same effect as that of the seventh embodiment can be expected.

The principal part of the gas turbine plant in Example 1 is shown. An enlarged detail view of the combustor 3 is shown. The longitudinal cross-sectional view in the position of the sub fuel nozzles 18a and 18b of FIG. 2 is shown. The fuel supply flow rate of each fuel supply system with respect to a gas turbine load is shown. A sectional view of the vicinity of the mixing chamber 17 and the auxiliary fuel nozzle 18a is shown. Sectional drawing of the position of the small air inflow hole 33 formed in the upstream of the mixing chamber 17 is shown. Sectional drawing of the position of the small air inflow hole 31 formed in the downstream of the mixing chamber 17 is shown. The enlarged view of the inflow hole 16 in Example 2 is shown. The enlarged view of the inflow hole 16 in Example 3 is shown. Sectional drawing of the combustion burner 46 which has the main fuel nozzle 45 in Example 4 is shown. The enlarged view of the sub fuel nozzle 53 in Example 4 is shown. Sectional drawing of the combustion burner 59 which has the main fuel nozzle 58 in Example 5 is shown. Sectional drawing of the auxiliary fuel nozzle 66 periphery in Example 5 is shown. Sectional drawing of the auxiliary fuel nozzle in Example 6 is shown. FIG. 9 shows an arrangement plan of a main fuel nozzle 98 and two sub fuel nozzles 84 and 85 in the seventh embodiment. FIG. 9 shows a layout of main fuel nozzles 88 and sub fuel nozzles in Example 8.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Compressor, 2 ... Turbine, 3 ... Combustor, 4 ... Combustion air, 5 ... Inner cylinder, 6 ... Combustion chamber, 7 ... Combustion gas, 8 ... Transition piece, 9, 45, 88, 98 ... Main fuel Nozzle, 10,
95, 96 ... Fuel supply system, 18a, 18b, 40, 43, 53, 66, 84, 85, 93, 94, 97 ... Sub fuel nozzle.

Claims (6)

A first fuel nozzle that ejects fuel;
An air ejection hole located on the outer peripheral side of the first fuel nozzle and ejecting combustion air;
An inner cylinder located on the downstream side of the combustion burner having the first fuel nozzle and the air ejection hole, and capable of mixed combustion of fuel and combustion air therein;
A gas turbine combustor comprising a closing plate for fixing the first fuel nozzle;
On the inner cylinder wall surface on the downstream side of the combustion burner, at least one inflow hole through which a mixture of combustion air and fuel flowing outside the inner cylinder can flow into the inner cylinder is formed,
A mixing chamber formed in a hollow conical shape that expands in the flow direction is disposed at the position where the inflow hole is formed, and a plurality of small air inflow holes for introducing combustion air into the mixing chamber are provided on the outer peripheral side of the mixing chamber And a second fuel nozzle for ejecting fuel in a direction substantially coaxial with the small air inflow hole is provided upstream of the small air inflow hole . A fuel nozzle for ejecting liquid fuel and gaseous fuel;
An air ejection hole located on the outer peripheral side of the fuel nozzle and ejecting combustion air;
An inner cylinder located on the downstream side of a combustion burner having the fuel nozzle and the air ejection hole, and capable of mixed combustion of fuel and combustion air therein;
A gas turbine combustor including a closing plate for fixing the fuel nozzle,
The inner space of the combustion burner is formed in a hollow conical shape that expands in the flow direction, and a plurality of air inlet holes for introducing combustion air into the combustion burner are formed on the outer periphery of the combustion burner.
A first liquid fuel nozzle for ejecting liquid fuel is installed on the upstream side of the combustion burner,
While installing a first gaseous fuel nozzle that ejects gaseous fuel on the upstream side facing the air inflow hole,
At least one inflow hole through which an air-fuel mixture of combustion air and fuel flowing outside the inner cylinder can flow into the inner cylinder is formed in the inner cylinder wall surface on the downstream side of the combustion burner. A mixing chamber formed in a hollow conical shape that expands in the flow direction is disposed at the forming position, and a plurality of small air inflow holes for introducing combustion air into the mixing chamber are formed on the outer peripheral side of the mixing chamber, A second liquid fuel nozzle for spraying liquid fuel is installed on the upstream side of the mixing chamber, and a second gaseous fuel nozzle for ejecting gaseous fuel is installed on the upstream side facing the small air inflow hole. Gas turbine combustor. A gas turbine combustor according to claim 1 ,
A guide ring extending in the axial center of the inner cylinder is installed in the inflow hole, and an extension direction of the guide ring is deflected in an axial direction or a tangential direction of the inner cylinder so that the fuel ejection direction of the second fuel nozzle is A gas turbine combustor configured so as to be substantially coaxial with an air flow flowing into the inner cylinder from the guide ring. A gas turbine combustor according to claim 1 ,
The first fuel nozzle that ejects fuel into the inner cylinder upstream of the combustion burner is used as a first gaseous fuel nozzle, and the fuel is ejected into the mixing chamber disposed at the position of the inflow hole. A gas turbine combustor, wherein the second fuel nozzle is a second gaseous fuel nozzle. A gas turbine combustor according to claim 1 ,
The first fuel nozzle that ejects fuel into the inner cylinder upstream of the combustion burner is used as a first liquid fuel nozzle, and fuel is ejected into the mixing chamber disposed at the position of the inflow hole. A gas turbine combustor, wherein the second fuel nozzle is a second liquid fuel nozzle. A fuel supply method for a gas turbine combustor in which fuel is ejected from a first fuel nozzle and combustion air is ejected from an outer peripheral side of the first fuel nozzle to an inner cylinder for mixing and burning fuel and combustion air. And
In the inner tube wall surface downstream of the first fuel nozzle having an inflow hole for flowing the mixture of the combustion air and the fuel flowing outside of the inner tube to the inside of the inner tube, the flow-in hole Gas having a mixing chamber formed in the shape of a hollow cone that expands in the flow direction at the formation position of the mixing chamber, and a plurality of small air inflow holes for introducing combustion air into the mixing chamber. Turbine combustor,
Fuel is burned in the mixing chamber in the mixing chamber by ejecting fuel in a direction substantially coaxial with the small air inflow hole from a second fuel nozzle arranged to eject the fuel upstream of the small air inflow hole . A fuel supply method for a gas turbine combustor, characterized by mixing with air.

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