CN104949152B - Aviation gas turbine LNG/aviation kerosene dual fuel combustor - Google Patents

Abstract

An LNG and aviation kerosene dual fuel combustor of an aero-gas turbine comprises a combustion area which comprises a precombustion area and a main combustion area, the outer boundary of the combustion area is provided with an inner flame tube wall, the inner boundary of the combustion area is provided with an outer flame tube wall, the front of the combustion area is provided with a combustor head, and the combustor head is connected with the inner flame tube wall through a head end wall. The LNG and aviation kerosene dual fuel combustor of the aero-gas turbine has the advantages that a center staged combustion concept is adopted, two kinds of fuel can be applied simultaneously, a precombustion level which adopts gas fuel provides a stable ignition source and reduces pollutant emissions, low pollution combustion is achieved through a main combustion level, pollutant emission is reduced, and the stability of the aero-gas turbine combustor can be guaranteed simultaneously; a double-ring cavity combustor structure is adopted, air used for combustion is all fed from the head, a flame tube is only provided with a dilution hole and a necessary cooling hole, the modularization feature is achieved, the combustion structure is simplified, and a premixed pre-evaporation loop structure is simpler and easy to process.

Description

Aviation gas turbine LNG/aviation kerosene dual fuel combustor

technical field

The invention relates to an aviation gas turbine combustor, in particular to an aviation gas turbine combustor capable of using LNG/aviation kerosene dual fuel.

Background technique

With the rapid development of the global military aviation and civil aviation industry, countries such as Europe and the United States realized their excessive dependence on petroleum-based aviation fuel at the beginning of this century, leaving serious hidden dangers to national defense and economic security. At the same time, global climate change has also put forward new requirements for the aviation transportation industry. In order to meet the requirements of more economical and more environmentally friendly aviation gas turbines for aircraft in the future, major aviation industry countries have focused on the environmental pollution caused by aviation gas turbines. Research on aviation gas turbines The control of pollutants has been extensively studied as a key topic. In order to achieve the emission reduction goals proposed by the International Air Transport Association, it is not enough to rely solely on aircraft lightweight and efficient and environmentally friendly aviation power technology under the existing fuel mechanism, and it is also necessary to rely on more environmentally friendly aviation alternative fuels. In the next 30 to 50 years, aviation alternative fuels will be dominated by "ready-to-use" fuels that will not affect aircraft and engine hardware.

Liquefied natural gas (LNG) is a kind of liquid fuel that liquefies natural gas into a liquid state at low temperature after drying and deacidification. . Liquid density is 0.42～0.46t/m ³ (3# aviation kerosene density is 0.78t/m ³ ), liquid heat value is 50MJ/kg (aviation kerosene is about 42.5MJ/kg). LNG is colorless, odorless, non-toxic and non-corrosive, and its volume weight is only about 45% of the same volume of water. Compared with aviation kerosene, LNG has the characteristics of low density, low cost, and high calorific value (the hydrogen-carbon ratio in LNG is 4, the hydrogen-carbon ratio of Jet A aviation kerosene is 1.8, and the calorific value of LNG is 16% higher than that of Jet A aviation kerosene) , At the same time, the pollutants produced by the combustion of LNG are lower than those of aviation kerosene (CO ₂ is 20% lower). Developing LNG engine technology and making LNG an alternative fuel for aviation kerosene will be an effective way to solve aviation kerosene depletion and environmental problems, and it will play a vital role in civil aviation and national defense science and technology.

In order to realize the application of LNG in aviation gas turbines, GE has carried out research on aircraft fuel systems using LNG as fuel, and applied for a number of international patents: WO2012/173651A1, WO2014/105328A1, these patents are mainly for the use of LNG as aviation gas turbine fuel It is necessary to study the fuel supply system, the temperature control of LNG and the coordinated control between LNG and aviation kerosene, but it does not involve the effective combustion of LNG and aviation kerosene in the combustion chamber.

In order to reduce the emission of pollutants from the combustion of aviation gas turbines, GE has proposed a center-staged double-annular premixed swirl combustor (TAPS), and has applied the first-generation TAPS to the GEnx engine of the Boeing 787 aircraft. GE has developed a variety of fuel nozzles using premixed pre-evaporation methods, and applied for a number of US patents: 0178732, 6354072, 6363726, 6381964, 6389815, 6418726 and 6453660, etc. Low emissions in the combustion chamber are achieved by reducing the fuel-air ratio in the main combustion zone, without involving the use of dual fuels.

Contents of the invention

In order to realize the application of LNG on aviation gas turbines, the present invention provides a central staged low-emission combustor that can use LNG and aviation kerosene as dual fuels. Stable operation of kerosene dual fuel; in addition, this technical solution can reduce the weight of the aviation gas turbine fuel system, prolong the cruising range of the aircraft, and reduce the exhaust emission of the aviation gas turbine.

The present invention is achieved through the following technical solutions: an aviation gas turbine LNG/aviation kerosene dual-fuel combustion chamber, including a combustion zone, the combustion zone includes a pre-combustion zone and a main combustion zone, and the outer boundary of the combustion zone is provided with an inner flame cylinder wall, The inner boundary is provided with an outer flame tube wall, an outer casing is arranged outside the outer flame tube wall, an inner casing is arranged outside the inner flame tube wall, an inner mixing hole is installed on the inner flame tube wall, and an outer casing is installed on the outer flame tube wall. Mixing holes, cooling holes are provided on the wall surface of the inner and outer flame tubes, and a combustion chamber head is provided at the front of the combustion zone, and the combustion chamber head is connected to the wall surface of the inner flame tube through the end wall of the head.

The outer flame cylinder wall and the inner flame cylinder wall are annular, and are radially distributed between the annular inner casing and the outer casing.

The combustion chamber head includes a pre-combustion stage and a main combustion stage. The pre-combustion stage and the main combustion stage are arranged concentrically, the pre-combustion stage is at the center, and the main combustion stage is arranged around the pre-combustion stage. The head of the combustion chamber is evenly arranged along the circumference of the LNG/aviation kerosene dual-fuel combustion chamber of the aviation gas turbine, and the number is 10 to 60. 60% to 90% of the air volume, the pre-combustion stage accounts for 10% to 40% of the head air volume.

The pre-combustion stage includes a central nozzle, a primary cyclone, a secondary cyclone, an LNG oil delivery pipe and a Venturi tube. A swirler with a venturi tube embedded in the center nozzle.

The center nozzle adopts a direct jet nozzle.

The main combustion stage includes an annular oil collecting tank, a three-stage cyclone, injection holes, kerosene through the oil delivery pipe and the main mixing area, and the outer side of the annular oil collecting tank is evenly distributed along the circumferential direction. The front end of the hole is provided with a main mixing zone and a three-stage cyclone.

8 to 24 injection holes with a diameter of 0.3 to 0.5 mm are evenly arranged on the outer side of the annular oil collecting groove along the circumferential direction.

Beneficial effects of the present invention: (1) The present invention adopts the concept of central staged combustion to realize the simultaneous application of two fuels. The pre-combustion stage using gaseous fuel also reduces pollutant emissions while providing a stable fire source, and the main combustion stage realizes Low-pollution combustion, which can ensure the stability of the aviation gas turbine combustor while reducing pollution emissions;

(2) The present invention adopts a double-ring combustion chamber structure, and the air for combustion is all supplied from the head, and there are only mixing holes and necessary cooling holes on the flame tube, which has modular features, simplifies the combustion chamber structure, and premixes and pre-evaporates The ring pipe structure is also relatively simple and easy to process.

Description of drawings:

Fig. 1 is a schematic diagram of an aviation gas turbine with a centrally staged low-emission dual-fuel combustor provided by the present invention;

Fig. 2 is a schematic structural view of a center-staged low-emission dual-fuel combustor provided by the present invention;

Fig. 3 is a schematic diagram of the head of the central staged low-emission dual-fuel combustor provided by the present invention;

Fig. 4 is the schematic diagram of the pre-combustion stage in the center-staged low-emission dual-fuel combustor provided by the present invention;

Fig. 5 is a schematic diagram of the main combustion stage in the center-staged low-emission dual-fuel combustor provided by the present invention;

In the figure: 1 low-pressure shaft, 2 high-pressure shaft, 3 fan, 4 low-pressure compressor, 5 high-pressure compressor, 6 aviation gas turbine LNG/aviation kerosene dual-fuel combustor, 7 high-pressure turbine, 8 low-pressure turbine, 9 pre-combustion zone, 10 Main combustion area, 11 inner flame tube wall, 12 outer flame tube wall, 13 inner casing, 14 outer casing, 15 inner mixing hole, 16 outer mixing hole, 17 cooling hole, 18 combustion chamber head, 19 head End wall, 20 pre-combustion stage, 21 main combustion stage, 22 center nozzle, 23 primary cyclone, 24 secondary cyclone, 25 LNG oil pipeline, 26 venturi tube, 27 annular oil collection tank, 28 three-stage cyclone device, 29 injection holes, 30 kerosene through the oil pipeline, and 31 main mixing area.

detailed description

The present invention will be further described below in conjunction with drawings and implementation.

As shown in Figure 1, it is a schematic structural diagram of a two-shaft aviation gas turbine with a centrally staged low-emission dual-fuel combustor. The front end of the low-pressure shaft is a fan 3 and a low-pressure compressor 4, and the rear end is a low-pressure turbine 8 for driving the low-pressure shaft. The fan 3, the low-pressure compressor 4, and the low-pressure turbine 8 are connected to the low-pressure shaft 1 through connecting parts such as bearings, the fan 3 is located in front of the low-pressure compressor 4, and the low-pressure turbine is located behind the high-pressure turbine 7. The front end of the high-pressure shaft 2 is a high-pressure compressor 5, and the rear end is a high-pressure turbine 7. The high-pressure compressor 5 and the high-pressure turbine 7 are connected to the high-pressure shaft 2 through bearings. The high-pressure compressor is located behind the low-pressure compressor. The aviation gas turbine LNG/aviation kerosene Before the dual-fuel combustor 6, the high-pressure turbine 7 is located behind the aviation gas turbine LNG/aviation kerosene dual-fuel combustor 6, and before the low-pressure turbine 8. When the gas turbine is working, the air is pressurized by the fan 3 and the low-pressure air compressor 4, and then enters the high-pressure air compressor 5, and the high-pressure air compressed by the high-pressure compressor 5 enters the LNG/aviation kerosene dual-fuel combustor 6 of the aviation gas turbine for combustion. The fuel injection system injects oil into the high-pressure airflow, and burns effectively in the LNG/aviation kerosene dual-fuel combustion chamber 6 of the aviation gas turbine. The high-pressure gas formed after combustion enters the high-pressure turbine 7 and the low-pressure turbine 8 to drive the turbines to do work.

As shown in Figure 2, the aviation gas turbine LNG/aviation kerosene dual-fuel combustion chamber 6 includes a combustion zone, the combustion zone includes a pre-combustion zone 9 and a main combustion zone 10, the outer boundary of the combustion zone is provided with an inner flame tube wall 11, and the inner boundary An outer flame tube wall 12 is provided, an outer casing 14 is arranged on the outer side of the outer flame tube wall 12, an inner casing 13 is arranged on an outer side of the inner flame tube wall 11, and the annular outer flame tube wall 12 and the inner flame tube wall 11 are arranged in an annular Radially distributed between the inner casing 13 and the outer casing 14 . Inner mixing holes 15 are installed on the inner flame tube wall 11, and outer mixing holes 16 are installed on the outer flame tube wall 12 for adjusting the outlet temperature distribution of the combustion chamber. Cooling holes 17 are arranged on the inner and outer flame tube walls 11 , used to cool the wall of the flame tube to ensure the life of the combustion chamber. A combustion chamber head 18 is arranged at the front of the combustion zone, and the combustion chamber head 18 is connected to the inner flame tube wall 11 through a head end wall 19 .

As shown in Figure 3, the combustion chamber head 18 includes a pre-combustion stage 20 and a main combustion stage 21, the pre-combustion stage 20 and the main combustion stage 21 are arranged together in a concentric manner, the pre-combustion stage 20 is at the center, and the main combustion stage 21 The combustion stage 21 is arranged on the periphery of the pre-combustion stage 20 . Combustor heads 18 are evenly arranged along the 6 circumferential directions of the aviation gas turbine LNG/aviation kerosene dual-fuel combustion chamber. 60% to 90% of the air volume in the head, and 10% to 40% in the pre-combustion stage.

The fuel nozzles supply all the fuel required by the combustion chamber, including pre-combustion level nozzles and main combustion level fuel injectors, wherein the number of main combustion level fuel injectors is 6 to 30, and the main combustion level fuel oil accounts for the total fuel oil The proportion of the amount is 50% to 90%;

The combustion process is completed in the combustion zone of the flame cylinder; the pre-combustion stage 20 and the main combustion stage 21 form two coaxial annular swirling jets in the combustion zone, and the fuel of the pre-combustion stage 20 and the main combustion stage 21 is located in the combustion zone respectively. The internal pre-combustion zone and the external main combustion zone are completed; the function of the pre-combustion zone 9 is to improve the quality of fuel atomization under starting and low power conditions, and to meet the requirements of ignition, starting, lean combustion stability and combustion efficiency, etc. The design requires the required flow field; the function of the main combustion zone 10 is to form a uniformly distributed premixed gas mixture for take-off, climb and cruise;

The air in the flame tube enters the combustion chamber in three streams. The first stream is the air required to cool the head of the combustion chamber and the flame tube. The second air flows through the pre-combustion stage cyclone and the main mixer into the combustion zone of the flame tube. The third air enters the combustion chamber from the mixing hole of the combustion chamber, so that the outlet temperature of the combustion chamber meets the requirements of the turbine inlet;

As shown in Figure 4, the pre-combustion stage 20 includes a central nozzle 22, a primary swirler 23, a secondary swirler 24, an LNG oil delivery pipe 25 and a venturi tube 26, and the front end of the LNG oil delivery pipe 25 is provided with a central nozzle 22 , A primary 23 and a secondary cyclone 24 are arranged in sequence outside the central nozzle 22 , and a venturi tube 26 is nested on the central nozzle 22 .

The pre-combustion stage 20 is realized by matching the inner co-rotating first and second double-stage swirlers with direct injection natural gas nozzles; among them, the first-stage swirlers are axial swirlers, and there are 6 to 16 swirlers swirl vanes; the nozzle and the outer peripheral sleeve of the nozzle jacket are combined and installed in the center of the inlet of the first-stage swirler 23; the second-stage swirler 24 is located outside the first-stage swirler 23, and It is a co-rotating cyclone; the second-stage cyclone 24 is followed by a venturi tube 26, the first swirling air enters the venturi tube 26 through the first-stage cyclone 23, and the second swirling air flows from the second After the inlet of the first-stage swirler 24 passes through the passage of the blades of the second-stage axial swirler to generate a swirling effect, it enters the head of the flame tube from the outlet of the second-stage swirler 24, and the natural gas cone is subjected to the action of two swirling air. A mixture is formed, and a chemical reaction occurs in the duty area by means of diffusion combustion;

The central nozzle 22 adopts a direct jet nozzle, and 3-7 injection holes with a diameter of 0.3-0.5mm are evenly arranged on the oblique section of the oil rod along the circumference. The gasified LNG enters the central nozzle 22 through the LNG oil delivery pipe 25, and the nozzle sprays out The natural gas enters the combustion zone of the combustion chamber for combustion after being mixed by the primary cyclone 23, the secondary cyclone 24 and the venturi tube 26.

As shown in Figure 5, the main combustion stage 21 includes an annular oil sump 27, a three-stage swirler 28, an injection hole 29, kerosene through an oil delivery pipe 30 and a main mixing zone 31, and the outer side of the annular oil sump 27 is uniform along the circumferential direction. Distributing injection holes 29, the upper end of the oil tank 27 is provided with a kerosene delivery pipe 30, and the front end of the injection holes 29 is provided with a main mixing zone 31 and a three-stage cyclone 28.

The main combustion stage 21 uses liquid aviation kerosene as fuel, and the main combustion stage fuel is injected through the main combustion stage oil supply nozzle, oil storage tank, and a plurality of circumferentially evenly distributed flat injection holes to form an oil mist cone with a cone angle, It is directly injected into the cavity of the main mixer through multiple flat injection holes, and the fuel in the cavity is evenly mixed with the air from the inlet of the third-stage swirler and then enters the head of the flame tube to form a uniform premixed oil and gas The mixture burns in the outer recirculation zone, forming a lean premixed main combustion zone;

8 to 24 injection holes 29 with a diameter of 0.3 to 0.5 mm are evenly arranged on the outer side of the annular oil collecting groove 27 along the circumferential direction, and the specific number depends on the number N of blades of the third-stage cyclone, and the number of nozzles is equal to The number N, or half of N. Aviation kerosene enters the annular oil collection tank 27 through the oil delivery pipe 30, and then injects into the main mixing area 31 through the injection hole 29, where the fuel is mixed with the air at the outlet of the three-stage cyclone 28 to realize the premixing of the fuel and air. Evaporated, the evenly mixed oil-gas mixture enters the main combustion zone 10 for combustion.

The third-stage swirler 28 of the main combustion stage 21 is a radial swirler, and its blades are curved blades; the blade installation angle is 47°～67°, and the angle depends on the required swirl intensity; the number of blades It is 8 to 24, which is an even number, and the specific number depends on the flow area of the cyclone;

All the air participating in the combustion enters the flame tube from the combined device of the three-stage swirler 28 at the head, the air used for combustion accounts for 80% to 90% of the total air volume, and the remaining 10% to 20% of the air acts as a film against the flame. The wall of the barrel is cooled and used as mixed air to meet the turbine inlet temperature requirements.

The principle of the invention is as follows: the dual-fuel combustion chamber of LNG and aviation kerosene is realized by adopting the central classification of fuel classification, and the purpose of reducing pollution emission is achieved by controlling the equivalence ratio and uniformity of the combustion zone in the combustion chamber of the aeroengine. The central staged combustion scheme of fuel oil classification is adopted. LNG is converted into a gaseous state through the gasification device and then enters the combustion chamber through the pre-combustion stage nozzle. Diffusion combustion is used to ensure the combustion stability of the entire combustion chamber and ensure that the main combustion stage 21 is in a wide range of equivalence ratio. The internal combustion is complete, while the aviation kerosene enters the main combustion area through the fuel nozzle of the main combustion stage 21. In the main combustion area 10, the premixed pre-evaporation ring is used to evaporate the liquid fuel and mix it with air to provide a uniform combustible mixture to the combustion chamber. , so as to control the equivalence ratio and uniformity of the entire combustion zone to achieve low emissions from the combustion chamber. In the start-up phase of the combustor, the pre-combustion stage fueled by LNG is started first, and the main combustion stage 21 is started under high load conditions. The pre-combustion stage 20 and the main combustion stage 21 work simultaneously under full load and cruise conditions. Since natural gas has the advantages of wide flammable limit, good atomization performance, and low pollutant emission, the use of LNG pre-combustion stage can not only realize the dual-fuel system of aero-engine, but also expand the flammable limit of the combustion chamber and reduce the emission of pollutants in the combustion chamber. . Under low working conditions, the local equivalent ratio of the pre-combustion stage 20 is relatively high and has good stability. Although the overall equivalent ratio of the combustion chamber is very low at that time, it can ensure the stable operation of the combustion chamber. Under large working conditions, the main combustion stage 21 and the pre-combustion stage 20 work at the same time, and the oil flow of the main combustion stage 21 accounts for the majority, and the uniform gas-mixed premixed combustion used in this part makes the equivalent ratio of the combustion zone lower than the pollution emission. In a lower range, the pollution emission under large working conditions is controlled. Therefore, the pollution emission of the combustion chamber is mainly controlled by the main combustion stage, while the stable working range is mainly controlled by the pre-combustion stage, which ensures that the aero-engine has low pollution emissions in a wide operating range, and at the same time, it is under low operating conditions and during the transition process. Has good stability.

The invention adopts a center-staged low-emission dual-fuel combustor, and in order to realize the simultaneous use of LNG and aviation kerosene, a fuel oil graded supply mode is adopted. The gasified LNG and aviation kerosene are divided into two paths and enter the combustion chamber. The first path is that the gasified LNG fuel enters the combustion chamber from the central pre-combustion stage nozzle 22. 24 and Venturi tube 26 under the action of evaporation after combustion, the pre-combustion stage adopts diffusion combustion. When the engine is in a small load state such as approaching or idling, only the pre-combustion stage works independently, and the fuel-rich combustion is adopted, and the combustion chamber can work efficiently and stably. emissions of pollutants.

The second road uses aviation kerosene as fuel, and the fuel oil enters the annular oil sump 27 through the aviation kerosene oil delivery pipe 30. The side of the annular oil sump 27 is provided with a plurality of small holes uniformly distributed along the circumference with a diameter of 0.3-0.5 mm. Injected into the cavity of the main mixing zone 31, the fuel in the cavity is evenly mixed with the air coming in from the inlet of the third-stage swirler 28 and then enters the head of the flame tube to form a uniform premixed oil-air mixture in the outer recirculation zone Combustion, forming a lean premixed main combustion zone. The design equivalence ratio of the main combustion zone is lean combustion with an equivalence ratio of 0.6 to 0.8, which has the dual advantages of lean premixed pre-evaporation (LPP) and lean direct injection (LDI), and reduces the temperature of the main combustion stage in an all-round way. The combustion temperature in the zone is controlled below 1800K, which can effectively suppress the formation of NO _X , especially thermal NO _X.

For heavy loads above approach, such as takeoff and climb, the pre-combustion stage and the main combustion stage work together, and the diffusion combustion in the pre-combustion zone provides a stable ignition source for the main combustion zone, which not only ensures low emission requirements, but also Fully consider the combustion stability, combustion efficiency, etc., and fully meet the basic performance requirements of the combustion chamber.

Claims (4)

1. a kind of aero-gas turbine LNG/ aviation kerosine dual-fuel combustors, it is characterised in that:Including combustion zone, combustion zone Including preignition zone and primary zone, the external boundary of combustion zone is provided with flame barrel, and inner boundary is provided with outer flame tube wall, outer fire Flame barrel outside is provided with outer casing, and flame barrel outside is provided with interior casing, and interior blending is installed on flame tube wall surface Hole, installs outer blending hole on outer burner inner liner wall, on inside and outside burner inner liner wall Cooling Holes are provided with, and is provided with combustion zone front portion Head of combustion chamber, head of combustion chamber is connected by head end wall with flame tube wall surface；Described head of combustion chamber includes pre-burning Level and main combustion stage, pre-combustion grade and main combustion stage are arranged together according to concentric mode, and pre-combustion grade is arranged in pre- in center, main combustion stage Combustion level periphery；Described pre-combustion grade, including central nozzle, one-level cyclone, second cyclone, LNG petroleum pipelines and Venturi tube, LNG petroleum pipelines front end is provided with central nozzle, and central nozzle has been orderly arranged outside each one-level cyclone and second cyclone, in Set is embedded with Venturi tube on heart nozzle；Described central nozzle adopts simple nozzle；

The third level cyclone of the main combustion stage is radial swirler, and its blade is camber blades；Blade angle is

47 °～67 °, angle depends on required swirl strength；Blade number is 8～24, is even number, concrete Number is determined by the flow area of cyclone；

Described pre-combustion grade adopts natural gas for fuel, and main combustion stage is with liquid aviation kerosine as fuel.

2. aero-gas turbine LNG/ aviation kerosine dual-fuel combustors according to claim 1, it is characterised in that: Described outer flame tube wall and flame barrel is annular, and the radial distribution between the interior casing and outer casing of annular.

3. aero-gas turbine LNG/ aviation kerosine dual-fuel combustors according to claim 1, it is characterised in that: Described main combustion stage, including annular oil trap, three swirler device, spray-hole, kerosene Jing petroleum pipelines and main mixed zone, annular oil-collecting Groove outside is uniformly distributed circumferentially spray-hole, and oil groove upper end is provided with kerosene Jing petroleum pipelines, and spray-hole front end is provided with main mixing Area and three swirler device.

4. aero-gas turbine LNG/ aviation kerosine dual-fuel combustors according to claim 3, it is characterised in that: Described annular oil trap outside is circumferentially evenly arranged 8～24 a diameter of 0.3～0.5mm spray-holes.