Disclosure of Invention
The invention provides a multi-fuel-adaptive combustion chamber and a multi-stage fuel supply premixing and control method, which aim to solve the technical problems that pollutants are easily generated in the traditional diffusion combustion mode and the multi-fuel low-pollution stable combustion cannot be simultaneously adapted.
The technical scheme adopted by the invention is as follows:
in one aspect, the invention provides a multi-fuel-adaptive combustion chamber, which comprises a combustion chamber head and a flame tube, and is characterized in that the combustion chamber head comprises a first fuel-air injection system and a second fuel-air injection system which is radially positioned outside the first fuel-air injection system, fuel is fed into the first fuel-air injection system and the second fuel-air injection system in a grading manner, the first fuel-air injection system comprises a fuel central air inlet pipe positioned outside a central ignition electric nozzle, a first-stage nozzle arranged on the fuel central air inlet pipe, an inner swirler arranged outside the fuel central air inlet pipe, and a second-stage nozzle, wherein the first-stage fuel is directly injected into the flame tube through the first-stage nozzle, the second-stage fuel is sprayed out through the second-stage nozzle and is premixed with air entering the inner swirler and then is swirledly injected into the flame tube in a lean fuel state, the first-stage fuel and the second-stage fuel enter the flame tube to realize first-stage combustion; the second fuel air injection system comprises an outer swirler and a third-stage nozzle, wherein the outer swirler is positioned on the outer side of the inner swirler, and the third-stage nozzle sprays third-stage fuel through the third-stage nozzle, pre-mixes the third-stage fuel with air entering the outer swirler and then performs swirl injection in a lean fuel state to enter the flame tube for realizing second-stage combustion; the fuel-air mixture respectively injected by the first fuel-air injection system and the second fuel-air injection system is subjected to premixed lean fuel parallel two-stage combustion in the flame tube.
And the second fuel air injection system also comprises a fourth stage nozzle, wherein fourth stage fuel is sprayed out from the fourth stage nozzle, premixed with air entering the outer swirler and then injected into the flame tube in a lean fuel swirling mode to realize second stage combustion.
Furthermore, the first-stage nozzle, the second-stage nozzle, the third-stage nozzle and the fourth-stage nozzle all comprise a plurality of spray holes which are uniformly distributed along the circumference.
Further, the inner swirler has the same swirling direction as the outer swirler.
Further, the inner swirler is an axial flow swirler or a radial swirler, and the outer swirler is an axial flow swirler or a radial swirler.
Furthermore, the first fuel-air injection system also comprises an inner flow passage arranged outside the fuel central air inlet pipe, and the inner swirler is connected with the inlet or the outlet of the inner flow passage; the second fuel-air injection system further comprises an outer flow passage arranged on the outer side of the inner flow passage, and the outer swirler is connected to an inlet or an outlet of the outer flow passage.
According to another aspect of the present invention, there is also provided a multi-fuel supply premixing and control method for the multi-fuel-adapted combustor, comprising the steps of:
a first stage nozzle in the first fuel air injection system supplies fuel until the gas turbine is finished starting;
when the gas turbine reaches a preset working condition, the second-stage nozzle in the first fuel-air injection system starts to gradually supply fuel, and the first-stage nozzle synchronously and gradually reduces the supply of the fuel, so that the first fuel-air injection system is switched to supply fuel-air mixture in a premixed lean state;
when the gas turbine is loaded, the second fuel-air injection system provides a swirl injection of the fuel-air mixture in a premixed, lean state into the combustor basket.
As one embodiment of the above scheme, for a single-shaft gas turbine, when fuel is high-calorific-value fuel and the single-shaft gas turbine reaches an idling state, controlling a first-stage nozzle to gradually decrease until the fuel supply is stopped, simultaneously, a second-stage nozzle starts to synchronously supply fuel, enters a flame tube after being premixed with air through an inner swirler, and gradually and synchronously increases until the fuel is supplied to replace the first-stage nozzle, wherein the fuel increase amount of the second-stage nozzle is equal to the fuel decrease amount of the first-stage nozzle in the adjusting process, and the working state parameter of the gas turbine is unchanged; when the fuel is low-calorific value fuel, the gas turbine is started, firstly, the first-stage nozzle supplies fuel, the second-stage nozzle starts to supply fuel after reaching a preset rotating speed, when the single-shaft gas turbine reaches an idle load state, the first-stage nozzle is controlled to gradually reduce the fuel supply, meanwhile, the second-stage nozzle starts to synchronously increase the fuel supply, the fuel is premixed with air through the inner swirler and then enters the flame tube, the fuel is gradually and synchronously increased until the fuel in the inner swirling first-stage combustion area is mainly supplied by the second-stage nozzle, and the fuel increase amount of the second-stage nozzle is equal to the fuel decrease amount of the first-stage nozzle in the adjusting process and the working state parameters of the gas.
As another embodiment of the above scheme, for the split shaft gas turbine, when the fuel uses high heat value fuel, the split shaft gas turbine starts to increase the load after reaching the idle load state, then the second fuel air injection system starts to supply fuel, when the split shaft gas turbine reaches 10% -45% load, the first stage nozzle is controlled to gradually decrease until stopping supplying fuel, meanwhile, the second stage nozzle starts to synchronously supply fuel, enters the flame tube after premixing with air through the inner swirler, and gradually and synchronously increases until supplying fuel instead of the first stage nozzle, the fuel increase amount of the second stage nozzle is equal to the fuel decrease amount of the first stage nozzle in the adjusting process, and the working state parameter of the gas turbine is unchanged; when the fuel is low-calorific value fuel, the split-shaft gas turbine is started and reaches a preset rotating speed, then the fuel supplied by the first-stage nozzle is kept unchanged, and the fuel supplied by the second-stage nozzle is premixed with air through the inner swirler and then enters the flame tube until the split-shaft gas turbine reaches an idle state; and then the third-stage nozzle starts to supply fuel, when the split-shaft gas turbine reaches 10% -45% of load, the first-stage nozzle is controlled to gradually reduce the fuel supply, meanwhile, the second-stage nozzle starts to synchronously and gradually increase the fuel supply and enters a flame tube after being premixed with air through an inner swirler, the adjustment is carried out until the fuel in the first-stage combustion area of the inner swirler is mainly supplied by the second-stage nozzle, and the fuel increase amount of the second-stage nozzle is equal to the fuel decrease amount of the first-stage nozzle in the adjustment process, so that the working state parameters of the gas turbine are unchanged.
Further, the first stage nozzle, the second stage nozzle, the third stage nozzle and the fourth stage nozzle are respectively independent, and fuel fed into the nozzles at all stages is the same or different; the fuel is any one of natural gas, biomass gasified gas, methane, coal bed gas, coal gas, shale gas, petroleum gas and landfill gas.
According to the invention, the mode that the first fuel air injection system and the second fuel air injection system respectively inject fuel-air mixtures to carry out premixed lean fuel parallel two-stage combustion in the flame tube is adopted, and the fuel adopts multi-stage feeding while the premixed lean fuel is subjected to staged combustion, so that the fuel can better adapt to the combustion of various fuels, including low-calorific-value fuel, and low-pollution combustion is organized; the first combustion stage also adopts a low-pollution combustion mode of premixed lean fuel, and the diffusion combustion on duty is not needed, so that the emission of pollutants is reduced; the staged nozzles can realize simultaneous feeding of different fuels according to proportion, optimize mixed combustion performance control and realize low-pollution mixed combustion in the flame tube. The invention can better adapt to the combustion of various fuels by premixing with air through multi-stage fuel supply control; the discharge of pollutants is reduced; the fuel can be simultaneously fed in different fuels according to a proportion, the mixed combustion performance control is optimized, and the low-pollution mixed combustion is realized in the flame tube.
In addition to the objects, features and advantages described above, other objects, features and advantages of the present invention are also provided. The present invention will be described in further detail below with reference to the accompanying drawings.
Detailed Description
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
Referring to fig. 1, a first embodiment of the present invention provides a multi-fuel compatible combustor, comprising a combustor head 1 and a flame tube 2, the combustor head 1 comprising a first fuel-air injection system and a second fuel-air injection system located radially outside the first fuel-air injection system, fuel being staged to the first fuel-air injection system and the second fuel-air injection system. In the combustion chamber suitable for multiple fuels, a first fuel-air injection system and a second fuel-air injection system both have a premixing function, and fuel-air mixtures respectively injected by the first fuel-air injection system and the second fuel-air injection system are premixed and lean and are subjected to parallel two-stage combustion in a flame tube 2.
Specifically, the first fuel-air injection system includes a fuel center inlet pipe 11 located outside the center ignition electric nozzle 10, a first-stage nozzle 110 provided on the fuel center inlet pipe 11, an inner swirler 12 provided outside the fuel center inlet pipe 11, and a second-stage nozzle 13.
In this embodiment, the first-stage nozzle 110 is disposed on the peripheral wall of the fuel central inlet pipe 11, and includes a plurality of nozzle holes uniformly distributed along the circumference, forming a multi-point injection. The first stage fuel is injected directly into the combustor basket 2 through the first stage nozzle 110.
In this embodiment, the inner swirler 12 is an axial flow swirler. The second stage nozzle 13 is located upstream of the inner swirler 12 and directly opposite the inner swirler 12. The secondary fuel is injected into the vane passage of the inner swirler 12 through the secondary nozzle 13, premixed with the air entering the inner swirler 12, and then swirl-injected into the combustor basket 2 in a lean fuel state. The first stage fuel and the second stage fuel enter the first stage combustion area of the flame tube 2 to realize first stage combustion.
The second fuel air injection system comprises an outer swirler 14, located outside the inner swirler 12, a tertiary nozzle 15. In this embodiment, the tertiary nozzles 15 are disposed on the sidewall of the outer swirler 14. Wherein, the third stage fuel is sprayed into the vane channel of the outer swirler 14 through the third stage nozzle 15, premixed with the air entering the outer swirler 14, and then swirled and sprayed into the flame tube 2 in a lean fuel state, so as to realize the second stage combustion in the second stage combustion area. In this embodiment, the outer swirler 14 is also an axial flow swirler.
Further, in the present embodiment, the second fuel-air injection system further includes a fourth stage nozzle 16. In this embodiment, the fourth stage nozzle 16 is also disposed on the sidewall of the outer swirler 14. Wherein, the fourth stage fuel is sprayed into the vane channel of the outer swirler 14 through the fourth stage nozzle 16, premixed with the air entering the outer swirler 14, and then swirled and sprayed into the flame tube 2 in a lean fuel state, so as to realize the second stage combustion in the second stage combustion area. In this embodiment, the second stage fuel is premixed with the air entering the inner swirler 12 and then swirled and injected from the inner swirler 12 into the combustor basket 2 in a lean state, and the third and fourth stage fuels are premixed with the air entering the outer swirler 14 and then swirled and injected from the outer swirler 14 into the combustor basket 2 in a lean state.
The two groups of nozzles, namely the third-stage nozzle 15 and the fourth-stage nozzle 16, jointly spray fuel into the channel of the outer swirler 14, so that the flow rate of the fuel is favorably adjusted and controlled in a larger range, and the premixing characteristic of the fuel is ensured in a larger adjustment range (the relative speed of the fuel and air is kept in a certain range, and the like, so that premixing and blending are favorably realized.
In the first fuel-air injection system of the present invention, the first-stage nozzle 110 and the second-stage nozzle 13 can supply two different fuels, respectively, to realize multi-fuel mixed low-pollution combustion. The four-stage fuel supply channel and the nozzle can be respectively introduced with fuels with the same characteristics, and can also be respectively introduced with fuels with different characteristics for premixing low-pollution combustion. The fuel is any one of natural gas, biomass gasified gas, methane, coal bed gas, coal gas, shale gas, petroleum gas, landfill gas and other gas fuels.
Further, the first-stage nozzle 110, the second-stage nozzle 13, the third-stage nozzle 15, and the fourth-stage nozzle 16 each include a plurality of nozzle holes that are evenly distributed along the circumference. The structure can form multi-point injection and mix with air, and fuel and air enter the flame tube 2 after being premixed.
Further, in the present embodiment, the inner swirler 12 and the outer swirler 14 have the same swirling direction, and the swirling strength is enhanced, which is beneficial to stable combustion.
Referring to fig. 2, a second embodiment of the present invention is substantially the same as the first embodiment except that: the first fuel-air injection system further includes an inner flow passage 17 disposed outside the fuel central air inlet pipe 11, the inner swirler 12 is connected to an outlet of the inner flow passage 17, that is, a position close to the combustor basket 2, the inner swirler 12 is an axial flow swirler, and the second-stage nozzle 13 is disposed on a side wall of the inner flow passage 17 and located upstream of the inner swirler 12. It is also different in that: the second fuel air injection system further comprises an outer flow channel 18 arranged outside the inner flow channel 17, the outer swirler 14 is connected at an inlet position of the outer flow channel 18, the outer swirler 14 is a radial swirler, and the tertiary nozzles 15 and the quaternary nozzles 16 are arranged on a sidewall of the outer swirler 14. In this embodiment, the second stage fuel is premixed with the air entering the inner swirler 12 from the inner flow passage 17 and then swirled and injected into the combustor basket 2 from the inner swirler 12, and the third and fourth stage fuels are premixed with the air entering the outer swirler 14 and then swirled and injected into the combustor basket 2 from the outer flow passage 18.
Referring to fig. 3, a third embodiment of the present invention is substantially the same as the second embodiment except that: the inner swirler 12 is a radial swirler, the inner swirler 12 is connected at the inlet position of the inner flow passage 17, and the second stage nozzle 13 is arranged on the side wall of the inner flow passage 17 and downstream of the inner swirler 12. In this embodiment, the second stage fuel is premixed with air and swirled out from the inner flow path 17, and the third and fourth stage fuels are premixed with air and swirled out from the outer flow path 18. Of course, the second stage nozzle 13 may be disposed on the sidewall of the inner swirler 12, and the third stage nozzle 15 and the fourth stage nozzle 16 may be disposed on the sidewall of the outer flow passage 18. The invention is not limited thereto.
Referring to fig. 4, a fourth embodiment of the present invention is substantially the same as the third embodiment except that: the outer swirler 14 is an axial flow swirler, the outer swirler 14 is connected to the outer flow passage 18 at an outlet position, and the third stage nozzle 15 and the fourth stage nozzle 16 are disposed on the side wall of the outer flow passage 18 and located upstream of the outer swirler 14. Of course, the third stage nozzle 15 and the fourth stage nozzle 16 may also be provided on the side wall of the outer swirler 14. The invention is not limited thereto.
The multi-fuel-adapting combustion chamber can be applied to a gas turbine and can also be applied to industrial combustors, such as low-pollution energy-saving combustion equipment of thermal equipment such as low-pollution metallurgical industrial furnaces, petrochemical industrial furnaces, boilers, environment-friendly pollutant treatment furnaces, biomass renewable energy application and the like.
According to another aspect of the present invention, there is also provided a multi-fuel supply premixing and control method for the multi-fuel-adapted combustor, comprising the steps of:
the first stage nozzle 110 in the first fuel air injection system feeds fuel until the gas turbine is finished starting;
when the gas turbine reaches a preset working condition, the second-stage nozzle 13 in the first fuel-air injection system starts to gradually supply fuel, and the first-stage nozzle 110 gradually reduces the supply of the fuel synchronously, so that the first fuel-air injection system is changed into supplying fuel-air mixture in a premixed lean state; in this step, the working state parameters of the gas turbine are not changed during the fuel supply conversion process;
when the gas turbine is loaded, the second fuel-air injection system swirls and injects the fuel-air mixture in a premixed lean state into the combustor basket 2.
Referring to fig. 1, for a single-shaft gas turbine, the multi-stage fuel supply premixing and control process is specifically as follows:
firstly, the rotating speed of the single-shaft gas turbine starts to rise under the driving of the starting motor, the ignition electric nozzle 10 works, the first-stage nozzle 110 starts to spray fuel when the single-shaft gas turbine reaches a certain rotating speed, the fuel is sprayed in an increasing mode after the ignition is successful, and the rotating speed of the single-shaft gas turbine gradually increases until the starting is finished to be in an unloaded state.
When the single-shaft gas turbine reaches an idling state when the fuel is high-calorific-value fuel such as natural gas, the first fuel-air injection system is controlled to be switched to a fuel-air mixture which is completely supplied with premixed lean fuel: the first-stage nozzle 110 is controlled to gradually decrease until the fuel supply is stopped, meanwhile, the second-stage nozzle 13 starts to synchronously supply the fuel and enters the flame tube 2 after being premixed with air through the inner swirler 12, and gradually and synchronously increases until the fuel is supplied to replace the first-stage nozzle 110, and the fuel increase amount of the second-stage nozzle 13 is equal to the fuel decrease amount of the first-stage nozzle 110 in the adjusting process and the working state parameter of the gas turbine is unchanged.
When the fuel is low-calorific-value fuel such as biomass gas, the gas turbine is started, the fuel is supplied from the first-stage nozzle 110, the fuel is supplied from the second-stage nozzle 13 after the preset rotating speed is reached, and when the single-shaft gas turbine reaches an idle state, the first fuel-air injection system is controlled to be changed into a fuel-air mixture mainly supplied with premixed lean fuel: the first-stage nozzle 110 is controlled to be gradually reduced to keep supplying a small amount of fuel, meanwhile, the second-stage nozzle 13 starts to synchronously increase the supplied fuel, the fuel is premixed with air through the inner swirler 12 and then enters the flame tube 2, and the fuel is gradually and synchronously increased until the fuel in the inner swirling first-stage combustion area is mainly supplied by the second-stage nozzle 13, namely, the supplied fuel of the second-stage nozzle 13 accounts for more than 50% of the supplied fuel of the first fuel air injection system, and the fuel increase amount of the second-stage nozzle 13 is equal to the fuel decrease amount of the first-stage nozzle 110 in the adjusting process and the working state parameter of the gas turbine is unchanged. The specific ratio of fuel supply to the first stage nozzle 110 and the second stage nozzle 13 during this control is determined by design according to the gas turbine and the specific fuel conditions.
When the single-shaft gas turbine is loaded, the second fuel air injection system swirls and injects the air-fuel mixture combustible gas in a premixed fuel lean state into the combustor basket 2: one of the tertiary nozzles 15 or the fourth stage nozzles 16 is supplied with fuel and premixed with air entering the outer swirler 14 to swirl in a lean state into the combustor basket 2. At this time, the fuel-air mixtures injected by the first fuel-air injection system and the second fuel-air injection system, respectively, undergo premixed lean fuel-parallel two-stage combustion in the combustor basket 2.
The load increase and the load decrease of the single-shaft gas turbine are realized by adjusting the fuel feeding amount of the second fuel air injection system. Specifically, when high calorific value fuel such as natural gas is used as the fuel, only one of the third stage nozzle 15 and the fourth stage nozzle 16 needs to be operated, and the load adjustment is realized by adjusting the increase and decrease of the amount of fuel supplied by the third stage nozzle 15 or the fourth stage nozzle 16. When the fuel is a medium-low calorific value fuel such as biomass gas, the load adjustment is performed by adjusting the increase and decrease of the amount of fuel supplied from the third stage nozzle 15 and the fourth stage nozzle 16. This supply air regulation comprises two schemes: a) the amounts of fuel supplied to the third stage nozzle 15 and the fourth stage nozzle 16 are adjusted simultaneously; b) firstly, one of the third stage nozzle 15 and the fourth stage nozzle 16 is adjusted to start to operate and supply fuel, and when the opening degree of the control valve of one of the third stage nozzle 15 and the fourth stage nozzle 16 which is firstly operated is larger than or equal to about 95%, the other of the third stage nozzle 15 and the fourth stage nozzle 16 starts to operate and carries out load adjustment.
When the single-shaft gas turbine is in a load reduction from high to low to no load state, the third-stage nozzle 15 or the fourth-stage nozzle 16 stops supplying fuel, and only the first fuel air injection system supplies fuel from the second-stage nozzle 13 to realize premixed lean fuel combustion (when high-calorific-value or medium-calorific-value fuel is used); when the medium to low calorific value fuel is combusted, the first-stage nozzle 110 is supplied with a small amount of fuel at that time, and most of the fuel is supplied from the second-stage nozzle 13.
Referring also to FIG. 1, for a split-shaft gas turbine, the multi-stage fuel-feed premixing and control process is embodied as follows:
first, when the fuel is a high calorific value fuel such as natural gas, the first-stage nozzle 110 supplies the fuel to start the split shaft gas turbine to an idling state. When loaded, fuel is supplied from one of the tertiary nozzle 15 and the quaternary nozzle 16 mounted on the outer swirler 14, and premixed with air entering the outer swirler 14 to swirl and inject into the combustor basket 2. When the split-shaft gas turbine reaches about 10% -45% of load, controlling the first fuel-air injection system to be switched to be completely supplied with fuel-air mixture in a premixed lean state: the first-stage nozzle 110 is controlled to gradually decrease until the fuel supply is stopped, meanwhile, the second-stage nozzle 13 starts to synchronously supply the fuel and enters the flame tube 2 after being premixed with air through the inner swirler 12, and gradually and synchronously increases until the fuel is supplied to replace the first-stage nozzle 110, and the fuel increase amount of the second-stage nozzle 13 is equal to the fuel decrease amount of the first-stage nozzle 110 in the adjusting process. At this time, the fuel-air mixtures injected from the first fuel-air injection system and the second fuel-air injection system, respectively, undergo premixed lean fuel parallel two-stage combustion in the combustor basket 2. The predetermined conditions for controlling the first fuel air injection system to be fully supplied with the fuel-air mixture in the premixed lean state are different for different split-shaft gas turbines, some of the split-shaft gas turbines can control the first fuel air injection system to be fully supplied with the fuel-air mixture in the premixed lean state when the load reaches 10%, and other split-shaft gas turbines need to control the first fuel air injection system to be fully supplied with the fuel-air mixture in the premixed lean state when the load reaches 45%.
Secondly, when the fuel is biomass gas and other low-calorific-value fuels, the first-stage nozzle 110 supplies the fuel to ignite and start and gradually increases the flow rate of the fuel, and after the split-shaft gas turbine reaches a preset rotating speed, the second-stage nozzle 13 starts to supply the fuel, premixed with air through the inner swirler 12 and then enters the flame tube 2 until the split-shaft gas turbine reaches an idle state. The fuel-air mixture in premixed lean state is fed to the liner 2 by the second fuel-air injection system when loaded: the fuel is supplied from one of the tertiary nozzles 15 or the quaternary nozzles 16 mounted on the outer swirler 14, premixed with air and introduced into the combustor basket 2. When the split-shaft gas turbine reaches about 10% -45% of load, controlling the first fuel-air injection system to be switched to mainly supply fuel-air mixture in a premixed lean state: the first-stage nozzle 110 is controlled to be gradually reduced to keep supplying a small amount of fuel, meanwhile, the second-stage nozzle 13 starts to synchronously and gradually increase the supplied fuel, the fuel enters the flame tube 2 after being premixed with air through the inner swirler 12, and the fuel is gradually and synchronously increased until the fuel in the inner swirling first-stage combustion area is mainly supplied by the second-stage nozzle 13, namely, the supplied fuel of the second-stage nozzle 13 accounts for more than 50% of the supplied fuel of the first fuel air injection system, and the fuel increasing amount of the second-stage nozzle 13 is equal to the fuel decreasing amount of the first-stage nozzle 110 in the adjusting process, and the working state parameter of the gas turbine is unchanged. At this time, the fuel-air mixtures injected by the first fuel-air injection system and the second fuel-air injection system, respectively, undergo premixed lean fuel-parallel two-stage combustion in the combustor basket 2. The specific ratio of fuel supply to the first stage nozzle 110 and the second stage nozzle 13 during this control is determined by design according to the gas turbine and the specific fuel conditions.
Similarly to the single-shaft gas turbine, the load adjustment and the load adjustment of the split-shaft gas turbine are realized by adjusting the fuel feeding amount of the second fuel air injection system. The split shaft gas turbine stops supplying fuel to the third stage nozzle 15 or the fourth stage nozzle 16 when the load is reduced to 10% -45% from high to low, and only the first fuel air injection system supplies fuel to the second stage nozzle 13 to realize premixed lean fuel combustion.
Further, the first stage nozzle 110, the second stage nozzle 13, the third stage nozzle 15, and the fourth stage nozzle 16 are independent of each other, and the fuel supply to each stage of nozzles may be the same or different. The fuel is any one of natural gas, biomass gasified gas, landfill gas, methane, coal bed gas, coal gas, shale gas, petroleum gas and other gas fuels. The high-calorific-value fuel refers to fuel with higher lower calorific value, and conversely, the high-calorific-value fuel refers to low-calorific-value fuel. Taking natural gas as an example, the natural gas belongs to high-calorific-value fuel, and the standard low-grade calorific value of the natural gas is 8500kcal/NM3And the lower calorific value of other medium calorific value fuels is about half of that of natural gas.
The invention has the following beneficial effects:
1) while the premixed lean fuel is adopted for staged combustion, the fuel is fed in multiple stages, so that the method can be better suitable for the combustion of various fuels, including low-heat-value fuel, and the low-pollution combustion is organized;
2) corresponding to a first fuel-air injection system, fuel and air come from an inner runner 17 (or an inner swirler 12), a first-stage nozzle 110 and a second-stage nozzle 13, the fuel is supplied into the flame tube 2 in a two-stage mode of directly injecting the first-stage fuel and injecting the second-stage fuel into the inner runner 17 or the inner swirler 12 for carrying out lean fuel premixing, and aiming at different working conditions and different fuels used by the gas turbine, the pollutant emission can be further reduced while stable combustion is realized by adjusting the supply proportion of the corresponding two-stage fuel in the first fuel-air injection system, and compared with the prior art of the same kind, the combustion stability is better, and the environmental protection performance is better; the first fuel-air injection system adopts a low-pollution mode of premixing lean fuel, and can further reduce the emission of pollutants on the basis of the prior art;
3) when the gas turbine operates stably with load, all premixed lean fuel can be supplied, and on-duty diffusion combustion is not needed, so that the emission of pollutants is reduced;
4) the low-pollution combustion can be realized in a wider working condition range, the stable low-pollution combustion adjusting range is large, the stable combustion range of a lean fuel boundary is wider, and the performances of spontaneous combustion, tempering and oscillatory combustion prevention are stronger;
5) corresponding to a second fuel-air injection system, fuel and air come from an outer flow passage 18 (or an outer swirler 14), the fuel is supplied in two stages by adopting a third-stage nozzle 15 and a fourth-stage nozzle 16, and enters the flame tube 2 after being subjected to lean fuel premixing in the outer flow passage 18 or the outer swirler 14, and the supply amount of the two-stage fuel is adjusted according to different working conditions of the gas turbine and different fuels used, so that the adjustment of fuels with different characteristics in a wider range can be adapted;
6) can realize simultaneous feeding of different fuels according to proportion, optimize mixed combustion performance control and realize low-pollution mixed combustion in the flame tube 2.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.