CN104456628A - Layered part premixing low-pollution combustor of main combustion level lean oil premixing - Google Patents

Abstract

The invention discloses a layered part premixing low-pollution combustor of main combustion level premixing and pre-evaporation. The layered part premixing low-pollution combustor has a pre-heating function. Fuel oil is divided into a main combustion level and an on-duty level. Diffusive combustion is adopted by the on-duty level, lean oil premixed combustion is adopted by the main combustion level, and the premixed combustion of a layered part is achieved through coupling of the diffusive combustion and the lean oil premixed combustion. The on-duty level is composed of a centrifugal atomizing nozzle and first level rotational flow air. The fuel oil of the main combustion level is supplied through multi-point direct-injection type nozzles, and oil and air mixing is enhanced through preheating of second level rotational flow air by combination of transverse jet air and on-duty level flame. The on-duty level is used in part-load conditions such as starting and slow operation, a stable combustion range can be broadened, combustion efficiency can be improved, and emission of CO and UHC is lowered; the on-duty level and the main combustion level work at the same time in the heavy load working condition, the on-duty level provides stable ignition sources for the main combustion level, a main combustion area is in a lean oil state, the temperature is far lower than the adiabatic flame temperature, and emission of NOx of high-load conditions can be reduced remarkably.

Description

A stratified partially premixed low-pollution combustor with lean premixed main combustion stage

technical field

The invention relates to a lean premixed low-pollution combustor with a preheating function, in particular to a stratified partial premixed low-pollution combustor which utilizes duty-level preheating to strengthen the mixing of oil and gas in the main fuel stage.

Background technique

For gas turbine engines using liquid fuels, fuel atomization and mixing have a decisive impact on engine combustion performance, combustion efficiency and pollutant emissions. Therefore, research on fuel atomization has received attention, which has also promoted the development of fuel atomization nozzles.

The International Civil Aviation Organization's pollutant emission standards for aviation gas turbines are becoming more and more stringent, especially for NOx pollution emission requirements. Low-pollution combustion has become the development trend of modern aero-engine combustors. The requirements of the currently implemented CAEP6 standards are already very strict, especially the requirements for NOx pollution emissions. All major airlines and research institutes regard the control of pollutant emissions as an important research topic. The low-pollution combustion technologies currently proposed include rich combustion-quenching-lean combustion (RQL), lean premixed combustion (LPP) and lean combustion. Oil Direct Injection Combustion (LDI).

Major international aero-engine companies GE, PW, R-R, and Snecma have all started research on low-pollution combustion technologies. Recently, GE has developed the TAPS (Twin Annular Premixing Swirler) low-pollution combustor for the new generation of commercial aviation turbofan engine Genx based on the lean premixed combustion (LPP) technology, and the NOx emission is lower than the CAEP2 (Committee on Aviation Environmental Protection) emission standard. up to 50%. In order to pre-mix the air and fuel before the combustion chamber, GE has designed and developed a variety of pre-swirl fuel nozzles, and has applied for a number of US patents for the different designs of the fuel nozzles in the TAPS combustion chamber. The main combustion of these patents The stage is that the fuel is injected to the rear of the main swirler to form a pre-mixed and pre-evaporated oil-air mixture. In order to make the oil-air mixture at the outlet of the pre-mixing pipe evenly mixed, the mixing and evaporation distance required by this mixing method is longer, thereby increasing The length and weight of the combustion chamber. Based on the concept of LDI combustion, R-R company has developed a variety of fuel nozzles for the Engine 3E core engine. The duty class uses air atomizing nozzles or centrifugal atomizing nozzles. The NOx emission on the test piece was reduced by 70% compared with the CAEP2 standard. PW company adopts RQL technology to develop TALON X combustion chamber and apply it to PW1000G engine, the NOx emission is expected to be 40% lower than CAEP6. The low-pollution combustor using lean premixed combustion technology currently under development can effectively control the flame temperature in the combustion chamber by controlling the equivalent ratio of the main combustion zone within the range of 0.5 to 0.7, thereby reducing the generation of thermal pollutants NOx. Combustion chambers using lean premixed combustion technology have a longer head premixing section, which is prone to spontaneous combustion or flashback; in addition, compared with traditional oil-rich head combustion chambers, lean premixed combustion chambers have lower critical combustion performance (such as idle Lean combustion stability and ignition performance) deteriorate.

Contents of the invention

The technical problem to be solved by the present invention is: in order to overcome the shortcomings and deficiencies of the above-mentioned prior art, the present invention adopts the method of preheating part of the air of the main combustion stage to improve the atomization, evaporation and blending quality of the main combustion stage fuel, so that the main combustion stage Combustion grade fuel is blended with a portion of primary combustion grade air in a nearly gaseous form.

The technical solution adopted by the present invention to solve its technical problems:

According to one aspect of the present invention, there is provided a stratified partially premixed low-pollution combustor with lean premixed main fuel stage, the fuel injection device of which includes a main fuel stage nozzle assembly and a duty stage nozzle assembly, characterized in that,

--The duty-level nozzle assembly includes a duty-level fuel pipe, a centrifugal atomizing nozzle, a primary air swirler and a conical flame stabilizer, wherein the centrifugal atomizing nozzle is located at the center of the fuel injection device , its inlet end communicates with the fuel pipe on duty, the first-stage air swirler is arranged on the outer ring of the centrifugal atomizing nozzle, and the diameter of the tapered flame stabilizer is gradually reduced. Located on the outer ring of the primary air swirler, the air outlet section of the tapered flame stabilizer whose diameter gradually enlarges is located behind the centrifugal atomizing nozzle in the axial direction, and the duty-grade fuel is passed through the centrifugal Type atomizing nozzle sprays for primary atomization, and then performs secondary atomization and mixing under the action of primary swirling air, and the flame on duty level is stabilized through the recirculation zone formed by primary swirling air and the conical flame behind the nozzle Stabilizer implementation;

--The main fuel level nozzle assembly is located on the outer ring of the duty level nozzle assembly and coaxially arranged with the duty level nozzle assembly, including the main fuel level fuel pipe, the main fuel level oil collector ring (23), multi-point Direct injection nozzles, secondary air swirlers and tertiary air swirlers; wherein, the secondary air swirlers are sleeved in the intake section of the conical flame stabilizer, and the secondary air swirls The outer part of the device is provided with a secondary air swirl channel housing with a gradually reduced diameter inlet section, and a number of multi-points are uniformly and vertically arranged on the wall surface of the secondary air swirl channel housing with a gradually enlarged diameter. The direct injection nozzle, the main combustion stage oil collecting ring is arranged on the outer wall surface of the secondary air swirl passage housing provided with several multi-point direct injection nozzles, the main combustion stage oil collecting ring and the main combustion stage The combustion-grade fuel pipe is connected, and the main fuel-grade fuel is sprayed radially into the secondary air swirl channel through the multiple multi-point direct injection nozzles, and the temperature of the second-stage swirl air increases under the action of the high temperature of the duty-grade flame , the main fuel oil is perpendicular to the flow direction of the second-stage swirl air, and the fuel is injected into the preheated swirl air for horizontal jet air atomization, and the part of the premixed oil-air mixture in the second-stage air swirl channel is at its outlet with the third-stage swirl Air flow for rapid and uniform mixing.

In the stratified partial premixed low-pollution combustor with lean premixed main combustion stage of the present invention, the fuel atomization method of the main combustion stage adopts atomization, evaporation and partial blending at first, and then complete blending, and the second stage of rotation The temperature of the flow air rises under the action of the high temperature of the duty-grade flame, and the main combustion-grade fuel is injected into the preheated swirl air through the direct-injection nozzle perpendicular to the flow direction of the second-stage swirl air for horizontal jet air atomization. Hot air enhances fuel atomization, evaporation and blending quality, and at the same time, the equivalence ratio in the second-stage swirler channel is greater than 4.0, which can avoid spontaneous combustion and backfire, and the part of the premixed oil-air mixture in the second-stage swirler channel The main combustion stage swirl outlet is quickly and evenly mixed with the third stage swirl air.

Preferably, the combustion chamber includes a casing outside the combustion chamber, a casing inside the combustion chamber, a diffuser, an igniter, an outer cylinder of the flame cylinder, and an inner cylinder of the flame cylinder.

Preferably, the diameter of the multi-point direct injection nozzle is 0.3-0.5mm, and the number is 3-8, injecting fuel perpendicular to the flow direction of the second-stage swirling air, and the fuel is firstly sprayed horizontally under the action of the second-stage swirling air. The jet air is atomized and then rapidly mixed with the third stage cyclone air at the exit of the main combustion stage cyclone.

Preferably, the inner side of the conical flame stabilizer adopts a flaring structure, which is a low-velocity zone for flame stabilization and improved air flow, and the high-temperature flame stabilizer is used to preheat part of the swirling air of the main combustion stage.

Preferably, the main combustion stage cyclone is composed of a second stage cyclone and a third stage cyclone.

Preferably, both the secondary air cyclone and the tertiary air cyclone adopt axial cyclone.

Preferably, the primary air swirler adopts axial blades, consisting of 12 to 24 blades, and the installation angle is 30-60 degrees.

The lean premixed layered partial premixed low-pollution combustion chamber of the main combustion stage of the present invention is coupled with diffusion combustion and lean premixed combustion technology, uses diffusion combustion to widen the stable working range of the combustion chamber, and utilizes lean premixed combustion to reduce thermal NOx emission. When the engine is in low working conditions such as starting and idling, only the duty stage works; when the load increases, the main fuel stage starts to work in the state of take-off, cruise or climb, and at this time the duty stage acts as a stable ignition source for the main fuel stage effect. The local equivalence ratio of the main combustion stage is 0.4-0.8. Since the main combustion stage is in a lean state, the combustion temperature in the main combustion zone of the combustion chamber can be controlled below 1800K, and the amount of NOx generated is small. The amount of NOx produced mainly depends on the combustion temperature and residence time, and increases exponentially with the increase of temperature. In the range of lean and rich oil, the reaction temperature is low, and the formation rate of NOx increases exponentially with the increase of temperature. Therefore, lean and rich oil combustion become the means to reduce NOx emissions, among which lean oil combustion is the most recently developed Widely used on short annular combustors. When the engine is in a large working condition, the main combustion zone is controlled to be in a lean state, and the equivalence ratio is in the range of 0.4 to 0.8. At this time, the temperature of the main combustion zone is controlled below 1800K, which can ensure high combustion efficiency and reduce pollutants (NOx, CO and UHC) ) with low emissions.

The principle of the present invention: the lean premixed stratified partial premixed low-pollution combustion chamber of the main combustion stage is based on the principle of stratified partial premixed combustion organization, and uses the duty-level flame to preheat the part of the swirling air in the main combustion stage, and the main combustion stage The fuel is atomized by transverse jet air in high temperature air, and then the partly blended fuel and air mixture is uniformly and quickly mixed with the remaining swirling air of the main combustion stage in a form close to gaseous fuel, and at the same time, this part of the preheating swirling air The heat removed acts as a cooling effect on the conical flame holder.

Compared with the prior art, the present invention has the following advantages:

(1) The fuel atomization process of the main combustion stage of the present invention uses preheated air to carry out transverse jet air atomization, and then uses a mixture of fuel and air close to the gaseous state to uniformly mix with the third-stage swirl air, and the fuel atomization process Separated from the oil/gas blending process, it enhances the uniformity of oil/gas blending.

(2) Use the preheated air to conduct transverse jet air atomization on the atomization of the main combustion stage fuel oil, which improves the quality of the primary atomization and mixing, and at the same time realizes the second-stage swirling air to the conical flame stabilizer The cooling effect increases the service life of the conical flame holder.

(3) The fuel of the main combustion stage is relatively rich in oil in the channel of the second-stage swirler, and is not easy to spontaneously ignite. Flashback and spontaneous combustion problems.

(4) The present invention adopts layered partial premixed combustion technology, and the on-duty stage adopts diffusion combustion, which works alone under low working conditions to widen the stable working range of the engine. The main combustion zone provides a stable ignition source, and the main combustion zone is lean premixed combustion, which can effectively reduce pollutant emissions under large working conditions.

Description of drawings

Fig. 1 is the structure sectional view of the stratified partial premixed low-pollution combustor of the lean premixed main combustion stage of the present invention;

Fig. 2 is the sectional view of the flame tube structure of the stratified partial premixed low-pollution combustion chamber of the present invention;

Fig. 3 is a cross-sectional view of the head structure of the lean premixed stratified partial premixed low-pollution combustor of the main combustion stage of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and examples.

Fig. 1 is a cross-sectional view of the structure of the lean premixed stratified partial premixed low-pollution combustor of the present invention, which adopts a stratified partial premixed combustion scheme and a short ring structure scheme, including a casing 1 outside the combustion chamber and a casing inside the combustion chamber 2. Diffuser 3, igniter 4, flame cylinder outer cylinder 5, flame cylinder inner cylinder 6, fuel injection device 7 and fuel injection rod 12.

Fig. 2 is the cross-sectional view of the main combustion stage lean premixed layered partial premixed low-pollution combustor flame cylinder structure of the present invention, the main combustion zone flame is divided into duty class flame 14 and main combustion stage flame 15, and the fuel oil passes through the main combustion stage respectively The nozzle assembly and nozzle assembly on duty stage enter the combustion chamber, the duty stage adopts diffusion combustion, which is used to expand the stable working range of the combustion chamber lean fuel combustion, and the main combustion stage adopts lean premixed combustion to reduce the flame temperature in the main combustion zone, thereby reducing NOx pollutant emissions.

Fig. 3 is the sectional view of the head structure of the stratified partial premixed low-pollution combustor head of the lean premixed main combustion stage of the present invention, and the fuel injection device 7 includes a main combustion stage nozzle assembly and a duty-level nozzle assembly, and the duty-grade nozzle assembly includes a centrifugal Atomizing nozzle 16, one-stage axial air cyclone 17 and conical flame stabilizer 27, wherein, centrifugal atomizing nozzle 16 is located at the center of the device, and one-stage axial air cyclone 17 is arranged on centrifugal On the outer ring of the atomizing nozzle 16, the conical flame stabilizer 27 is located behind the centrifugal atomizing nozzle 16, and the duty-grade fuel is sprayed through the centrifugal atomizing nozzle 16 for primary atomization, and then undergoes secondary spraying with the primary swirling air. Secondary atomization and mixing, the flame stabilization of the duty class is realized by the recirculation zone formed by the primary swirl air and the conical flame stabilizer 27 behind the nozzle; the main combustion stage is located at the outer ring of the duty class and is connected with the stage coaxial, including main fuel oil pipe 19, oil collector ring 23, multi-point direct injection nozzle 24, secondary air swirler 18 and third-stage air swirler 20, wherein, multi-point direct injection nozzle 24 is along the circumference The fuel oil enters the oil collecting ring 23 through the main combustion level fuel pipe 19, and enters the secondary swirl air channel through the direct injection nozzle 24; the inner wall of the second level swirler is heated by the high temperature of the duty level flame, thus The second-stage swirling air is heated, and at the same time, the second-stage swirling air plays a cooling role for the conical flame holder 27; the main fuel oil is subjected to horizontal jet air atomization under the action of the preheated second-stage swirling air , evaporation and blending, in the form of gaseous fuel, it is quickly mixed with the third-stage swirl air at the outlet 22 of the main combustion stage swirler, so as to realize the premixing and pre-evaporation of the main combustion stage fuel and air, which is used in the combustion chamber Lean combustion in the main combustion zone.

The duty-level flame 14 and the main combustion-level flame 15 are different in axial and radial spatial distribution, the duty-level flame 14 is closer to the head and center of the combustion chamber, the main combustion-level flame is on the periphery of the duty-level flame and is close to the downstream along the flow direction, Realize the divisional combustion of the middle duty class and the main combustion class in the combustion chamber. When the working condition is low, the duty class works alone, and when the working condition is heavy, the duty class and the main combustion stage work at the same time. The amount of injected fuel in the main combustion stage accounts for 50-90% of the total fuel amount. The direct jet nozzle 25 has a diameter of 0.3-0.5mm, and the number is 3-8, and the jet flow direction of the nozzle is perpendicular to the flow path of the second-stage cyclone. The secondary swirler 18 and the tertiary swirler 20 are axial or radial swirlers with 8 to 24 blades. When the working condition is large, the multi-point direct injection nozzle 25 of the main combustion stage starts to work, and the fuel enters the oil collector ring 23 through the fuel pipe 19, and is sprayed into the flow channel of the secondary swirler through the direct injection nozzle 25.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the present invention. within the range.

Claims (10)

1. A stratified partial premixed low-pollution combustor of a lean premixed main combustion stage with a preheating function, its fuel injection device includes a main combustion stage nozzle assembly and a duty stage nozzle assembly, characterized in that, --The duty-level nozzle assembly includes a duty-level fuel pipe, a centrifugal atomizing nozzle, a primary air swirler and a conical flame stabilizer, wherein the centrifugal atomizing nozzle is located at the center of the fuel injection device , its inlet end communicates with the fuel pipe on duty, the first-stage air swirler is arranged on the outer ring of the centrifugal atomizing nozzle, and the diameter of the tapered flame stabilizer is gradually reduced. Located on the outer ring of the primary air swirler, the air outlet section of the tapered flame stabilizer whose diameter gradually enlarges is located behind the centrifugal atomizing nozzle in the axial direction, and the duty-grade fuel is passed through the centrifugal Type atomizing nozzle sprays for primary atomization, and then performs secondary atomization and mixing under the action of primary swirling air, and the flame on duty level is stabilized through the recirculation zone formed by primary swirling air and the conical flame behind the nozzle Stabilizer implementation; --The main fuel level nozzle assembly is located on the outer ring of the duty level nozzle assembly and coaxially arranged with the duty level nozzle assembly, including the main fuel level fuel pipe, the main fuel level oil collector ring (23), multi-point Direct injection nozzles, secondary air swirlers and tertiary air swirlers; wherein, the secondary air swirlers are sleeved in the intake section of the conical flame stabilizer, and the secondary air swirls The outer part of the device is provided with a secondary air swirl channel housing with a gradually reduced diameter inlet section, and a number of multi-points are uniformly and vertically arranged on the wall surface of the secondary air swirl channel housing with a gradually enlarged diameter. The direct injection nozzle, the main combustion stage oil collecting ring is arranged on the outer wall surface of the secondary air swirl passage housing provided with several multi-point direct injection nozzles, the main combustion stage oil collecting ring and the main combustion stage The combustion-grade fuel pipe is connected, and the main fuel-grade fuel is sprayed radially into the secondary air swirl channel through the multiple multi-point direct injection nozzles, and the temperature of the second-stage swirl air increases under the action of the high temperature of the duty-grade flame , the main fuel oil is perpendicular to the flow direction of the second-stage swirl air, and the fuel is injected into the preheated swirl air for horizontal jet air atomization, and the part of the premixed oil-air mixture in the second-stage air swirl channel is at its outlet and the third-stage Swirling air for rapid and homogeneous mixing. the 2. The stratified partially premixed low-pollution combustor of lean premixed main combustion stage with preheating function according to claim 1, characterized in that, the combustor comprises an outer casing, an inner casing, Diffuser, igniter, flame cylinder outer cylinder, flame cylinder inner cylinder. the 3. The lean premixed stratified partial premixed low-pollution combustor with preheating function according to claim 1, characterized in that the diameter of the multi-point direct injection nozzle is 0.3-0.5mm, each The number is 3 to 8, and the fuel is injected perpendicular to the flow direction of the second-stage swirl air. High-speed swirling air for rapid mixing. the 4. The stratified partially premixed low-pollution combustor with lean premixed main combustion stage with preheating function according to the above claim, characterized in that the inner side of the conical flame stabilizer adopts a flaring structure, which is a flame Steadily increasing the low velocity zone of the air flow, the high temperature flame holder is used to preheat part of the main combustion stage swirling air. the 5. The stratified partially premixed low-pollution combustor with lean premixed main combustion stage with preheating function according to the preceding claim, characterized in that the main combustion stage swirler is composed of the second stage swirler It is combined with the third stage cyclone. the 6. The stratified partially premixed low-pollution combustor with lean premixed main combustion stage with preheating function according to the preceding claim, characterized in that the secondary air swirler and the tertiary air swirler Axial swirlers are used. the 7. The stratified partially premixed low-pollution combustor with lean premixed main combustion stage with preheating function according to the preceding claim, characterized in that the primary air swirler adopts axial vanes, ranging from 12 to 24 It consists of two blades, and the installation angle is 30-60 degrees. the 8. The lean premixed stratified partial premixed low-pollution combustor of the main combustion stage with preheating function according to the preceding claim, characterized in that the fuel injection device also includes a pre-combustion chamber that provides fuel to the combustion chamber stage nozzle, main combustion stage nozzle, nozzle stalk, fuel oil enters the nozzle rod through the pre-combustion stage nozzle and main combustion stage nozzle, the pre-combustion stage nozzle communicates with the pre-combustion stage fuel atomizing nozzle, the main combustion The oil nozzle communicates with the oil collector ring, and the pre-burning grade fuel and the main combustion grade fuel do not meet in the nozzle rod. 9. A gas turbine combustor with preheating function and premixed pre-evaporation of the main combustion stage according to claim 1, wherein the gas turbine is an aviation gas turbine engine or an industrial gas turbine. the 10. A gas turbine combustor with a preheating function of the main combustion stage premixed preevaporation, comprising an outer casing, an inner casing, a diffuser, an igniter and any one of claims 1 to 9 with preheating The main combustion stage premixed and pre-evaporated gas turbine combustor with thermal function, compared with the traditional head oil-rich combustion chamber, the head adopts lean oil combustion technology, the combustion air accounts for 50-90% of the total air volume, and the remaining cooling air It enters the flame tube from the mixing hole (9) to further adjust the outlet temperature distribution of the combustion chamber, so that the outlet temperature distribution of the combustion chamber meets the requirement of the heating intensity of the turbine inlet guide vanes. the