JPS6229834A - Combustion chamber for gas turbine engine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to combustors for gas turbine engines, and more particularly to multi-burner combustors.

BACKGROUND OF THE INVENTION Such combustors for high-efficiency turbines operate under harsh conditions and must be able to withstand gas outlet temperatures in the region of 1200°C.

Therefore, there is a need to provide a cooling means for the combustor that does not significantly degrade the performance of the combustion system.

It is also necessary to consider the different turbine load conditions between idle and full load, which impose different demands on the combustor. The need for large variations in the ratio of fuel to combustion air over load conditions creates problems at very low loads when attempting to maintain stable combustion at very low fuel supplies. Applying multiple burners in a single combustion chamber can provide a partial answer to this problem. This is because while some burners are completely stopped, the fuel supply to the remaining burners can be maintained at a reasonable level.

However, this requires complex control of the fuel supply system, which is to be avoided if possible. This "solution" results in a highly non-uniform temperature distribution, resulting in thermal stresses and therefore short operating periods. If such "r-staged" fueling is not applied, the multi-burner configuration still has advantages resulting from its combination with other features.

(a) because the large number of fuel injection points spread across the upstream inlet and into the flame tube, together with uniform cooling of the flame tube wall, allows good control of the temperature distribution, especially the turbine inlet temperature distribution; , the operating period becomes longer.

(b) The multi-burner configuration, together with the very high proportion of compressed air supplied to the -fire combustion, provides conditions for greatly suppressing nitrogen oxide emissions.

(.) A large number of fuel injection points evenly distributed across the flame tube entrance provides excellent fuel/oxidizer mixing conditions for low heating value fuels containing inerts.

As shown in Figure 1 of the accompanying drawings, the combustion air is supplied in the form of jets through fairly large holes in the combustor wall, and the gaps between successive concentric wall sections are utilized, thereby allowing the membrane to Some attempts have been made to control low fuel operating conditions and maintain stable combustion by introducing cooling air. The turbulence introduced in this way is
Application of fuel injectors and secondary air stirrers helps stabilize the flame, but results in loss of efficient yet uniform cooling of the combustor. When air is injected through the wall of the flame tube, the cooling film on the wall is destroyed, causing temperature variations. As a result, thermal distortion and/or hot corrosion occurs, reducing the pot life of the flame tube.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to exhibit effective wall cooling under all operating conditions, as well as good flame stability, and furthermore to provide excellent combustion outlet temperature distribution, low emissions of nitrogen oxides, and low nitrogen oxide emissions. It is an object of the present invention to provide a multi-burner type combustor that exhibits excellent combustion performance even when using fuel with a calorific value.

According to the present invention, a combustor for a gas turbine engine includes a flame tube, a plurality of fuel injectors, each injector having a fuel discharge passage with a radial component and extending in a plane transverse to the axis of the flame tube. axially directing compressed air around said injector and flame stabilizing means, with an axial flow path for atomizing air directed through each fuel outlet (with stabilizing means provided); and means for directing compressed air generally radially inwardly into the flame tube through double walls with an annular gap therebetween, the double walls being not radially aligned with each other. The air impinging through the holes in the outside wall and the air flowing out through the holes in the inside wall can cool the inside wall and have minimal impact on the aerodynamic flow pattern formed within the flame tube. It is characterized by having chain pores arranged so as to give.

In a preferred embodiment, each fuel injector comprises a nozzle closed at one end and having a plurality of radial orifices, and a baffle plate from which the nozzle projects. The baffle plate is formed with atomization holes arranged in a ring shape so as to surround the nozzle at a position corresponding to the orifice but on the upstream side thereof. The baffle plate has a shallow cup shape that opens toward the downstream end of the flame tube and forms a containment wall for the flame stabilization region.

Preferably, the peripheral shape of the baffle plates is such that a gap of substantially constant width is formed between them. For this purpose, a weir plate can also be provided between the flame tube wall and the baffle plates. The profile of the dam plate is such as to provide a substantially uniform air supply path around each outer baffle plate. Preferably, the baffle plates are hexagonal and arranged in a honeycomb configuration.

Preferably, the fuel injectors are cantilevered from the fuel manifold plate upstream of the flame tube. In this way, the fuel injector and the corresponding baffle plate within the flame tube opening are free to move under the influence of heat.

Preferably, each fuel injector comprises separate ducts for liquid and gaseous fuels, and means are provided for selecting between the two types of fuel. Additionally, means for spraying water may also be provided.

Adjacent baffle plates may be interconnected by a wind shield strip member that is freely movable relative to at least one of the connected baffle plates. These windshield strip members assist in the spread of the flame between adjacent injectors and baffle plates.

Besides the atomization holes, a number of holes are formed in each baffle plate,
It is possible to allow air to flow into the flame side of the baffle plate, prevent the formation of carbon precipitates, and further improve ventilation of the mixture.

Preferably, the proportion of air passing through the atomization holes is limited to 10% of the total air sent to the combustor.

Still further, the proportion of air supplied to and between the baffle plates is set at 70% of the total air supplied to the combustor.
90% and the proportion of air supplied to cool the flame tube to 10%-30% of the total air supplied to the combustor.
You can also do this.

The total cross-sectional area of the holes in the inner wall of the flame tube is larger than that of the holes in the outer wall of the flame tube.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION A combustor for a gas star engine according to the invention will now be described with reference to the accompanying drawings.

In the conventional combustor shown in Figure 1, the tube consists of a series of coaxial cylinders - 1, 2, 3, 4 and 5, with narrow spaces between each adjacent cylinder to form an air film that cools the walls. Form a slot. A single fuel injector 7 atomizes the fuel and a surrounding primary air stirrer 9 imparts turbulence to the radially incoming air. flame tube cylinder 2
and 3 relatively large holes II inject secondary combustion air into the flame tube, which, together with the outflow flow from the igniter, imparts turbulence to the flow of the combustion mixture.

Holes I2 and 13 in cylinders 1 and 5 introduce dilution air to complete the combustion of the fuel and reduce the average gas temperature to a level acceptable to the turbine. These various air jets flowing across the flame tube disturb the cooling film and cause thermal distortion, as described above. This is further exacerbated by the necessarily large pressure drop between the duplex walls.

FIG. 2 is a partial side view showing an example of a combustor according to the present invention. The flame tube consists of an outer wall 15 radially spaced from an inner wall I7. The outer walls are a single uniform concentric cylinder, each having apertures as described with respect to FIG. Therefore, the flame tube is easier to manufacture than that of conventional combustors.

19 fuel injectors 10 are attached to the fuel manifold plate 21. In another embodiment (not shown), the injector is attached to a separate support member. Bolts 23 support the salt plate (shown in FIG. 6), which is then secured by bolts to the flanges (not shown) of the flame tube opening. The fuel injection nozzle 25 is provided so as to be located in a cross section within the flame tube opening.

One short cylinder 27 forms a guiding gap, which serves as the starting point for the wall cooling film. This cylinder is also installed within the opening of the flame tube.

FIG. 3 is a diagram showing the main parts of one fuel injector in detail on a scale twice the actual size. The injector consists of a tubular body 29 containing a central liquid fuel tube 3I. Liquid fuel (oil) is routed along the center of the central tube 3I and gaseous fuel is routed along the annular gap between 29 and 31. A valve (not shown) controls the selection of gaseous and liquid fuel.

The nozzle end 33 serves as a heat shield (sealed and covered by a refractory metal disc 35). Six orifices 37 are provided radially adjacent the nozzle end to provide an outlet for the pressurized fuel. Orifice 37 formed in the wall of main body 29
The six holes 39 of the central tube 3I are aligned. If oil is selected and used, it flows as a jet along the center 41 and exits radially from the orifice 37 via the hole 39 and the annular gap. A shallow cup-shaped baffle plate 44 is provided just upstream of the orifice 37 of the fuel injector. This baffle plate opens downstream (to the left in Figure 3 and to the left in Figure 2).As shown in Figure 4, this baffle plate is The shape is hexagonal. In this embodiment, the baffle plate consists of two parts: a circular flange 43 that is integral with the injector body 29 and a hexagonal ring 45 that is secured to the flange by rivets 47.

Flange 43 is formed with six axial holes 49 adjacent to injector body 29 and aligned with radially disposed fuel orifices 37 . The jet flow of atomized air through these axial holes 49 interrupts the jet flow of fuel from the orifice 37 . Since atomization of liquid fuel occurs through the interaction of liquid/air jet streams, the requirements for the pressure of the supplied fuel are considerably lower than those required for conventional stirrers - injection pressure atomizers.

In a modification of this embodiment, baffle plate 44 is integrally formed and secured to injector body 29 by welding or other means.

The fuel injector is cantilevered at its rear end from the fuel manifold plate 21.

4 is a view of the downstream side of the fuel injector of FIG. 3, looking toward the cup-shaped baffle plate 44. FIG.

In addition to the atomization axial holes 49, the baffle plate 44 is provided with a number of air holes. The holes 51 arranged in a ring shape, which are approximately half the size of the eruption forming holes 49, are located in the same plane as the rivets 47.

Additional holes 53 of the same size are formed in the corners of the hexagon, and 48 smaller holes 55 are provided in a hexagonal configuration around the baffle plate.

FIG. 5 shows a part of the baffle plate 44 on a large scale, and also shows two ring-shaped small holes 57, which are not shown in FIG.

The holes 51, 53, 55 and 57 serve to vent the fuel in the area of the baffle plate and thus prevent partially burned carbon from depositing on the surface of the baffle plate.

FIG. 6 is a (right half) view of the combustor, looking at each burner module 19 from the upstream side. These modules are arranged in a honeycomb configuration with uniform spacing between adjacent baffle plates to form a flow path for combustion air, ensuring the amount and flow of primary air completely surrounding each baffle. It becomes uniform and the compressor output and fuel flow rate can be known and calculated.

In order to maintain uniform air flow around each baffle plate at the edge of each injector and baffle plate, a weir plate 61 is provided in the same plane as the baffle plate 44 to separate the peripheral baffle plate and the flame tube. Make sure to seal any irregular gaps that may occur between the wall and the wall. The shape and dimensions of the weir plate 61 are such that it leaves a gap 63 approximately half the width of the gap between adjacent baffle plates, thereby reducing the amount of air required on one side of the gap. Therefore, a uniform air flow path is formed around each baffle plate.

The weir plate is supported by bolts 23 which extend the length of the injector and are secured to the fuel manifold plate 2. This weir plate itself is located at the center 65 at the flange of the flame tube opening.
It is fixed with bolts. As shown in FIG. 7, the edge of the weir plate 61 is oriented toward the downstream side so that the air flow path is uniform around the entire circumference of the outer baffle plate. The weir plate may be provided with small holes for cooling.

A feature of this embodiment is that its construction allows the flame to spread between the baffle plates.

A strip of metal 67, which acts as a windshield strip, is formed extending in the plane of the barbed full plate opening to the opposite edge section of the adjacent baffle plate. The strip is welded to the baffle plate at one end, but is free to move relative to its opposing baffle plate. During operation,
A low-pressure area is created on the lower side of this strip, which causes the flame to cross the "brisono" so to speak and impinge on the flame of the next burner. An important feature of this construction is that it suppresses any thermal forces generated by the strips between the bonding baffle plates. The baffle plate is therefore free to float in the cantilevered mounting.

It should be noted that each strip may be brought into the wall to avoid binding the ends, for example by inserting the strip ends into slots in the baffle plate wall and twisting them into the wall.

In another embodiment (not shown), the baffle is not affixed to the injector, but the baffle arrangement is provided as an integral disk (individual baffles are attached to each other by wind shield strips) and, in some cases, thermal suitable means capable of moving with limited degrees of freedom under the action of, e.g.
It is connected to the flame tube via a weir plate by a protruding member that slides within a larger slot. The injector nozzle can be inserted into the center hole of each baffle with sufficient clearance to allow for thermal transfer. An advantage of this embodiment is that the injector can be easily removed for periodic cleaning or replacement.

Referring now to FIG. 7, the three burner combustor shown in this figure is suitable for smaller engines than the previously described combustors.

Similarly, the fuel injector 29 is attached to the fuel manifold 21.
and attach baffle plate 4 =1. Similar to the combustor described in Moe, the manifold plate 21 is fixed by a bolt to the flange of the cylindrical caning 69 of the combustor built in the double-walled flame tube 7I.

Similarly, baffle plate 44 and dam plate 61 are installed to provide a primary air flow path around and through baffle plate 44. Combustion air is provided by a compressor (not shown) and is directed along the outer casing 69 and then reversed and directed to the flame tube.

The outer wall 15 of the flame tube 71 is provided with a large number of small holes in its surface. The inner wall 17 of the flame tube is also provided with a number of holes. In this embodiment, however, the cross-sectional area ratio of the inner wall to the outer wall is approximately 4.1. Therefore, the pressure drop across the outer wall 15 is extremely large compared to the inner wall 17. This is desirable because the outer cooling wall can withstand larger pressure points. In addition, the materials used for these two walls can be adapted to different operating conditions. That is, the outer wall can be made to withstand pressure stresses, and the inner wall can be made to be able to withstand thermal stresses. With reference to FIG. 8, wall cooling will be explained in more detail. In addition, in FIGS. 7 and 8, small holes are enlarged for clarity of illustration. The annular gap relative to the inner wall is also shown enlarged. For example, this gap is three times the diameter of the impingement hole. The inner and outer walls are fixed only at the upstream end, and the downstream end is allowed to move relatively freely thermally.

In yet another embodiment (not shown), the substantially uniform annular gap between the inner and outer walls is divided axially and/or circumferentially to form different cooling zones that are provided with different cooling air pressures. to act.

By fixing the partition plate to only one wall and providing a clearance between the tip and the opposite end of the partition plate, the partition plate is provided between the walls without canceling out the relative freedom between the walls.

When held in the middle of the flame tube 71 by a joint that expands and contracts freely, 7
Connect 7. This intermediate duct is a single wall duct without cooling holes. Alternatively, the intermediate cap 77 may be cooled in conventional manner or by a single-walled vigil construction similar to that for flame tubes 15 and 17.

The cooling ring 27 is the starting point of the cooling film formed on the inner wall 17.

FIG. 8 shows in detail a cross-section of the combustor in the area of the outer burner 19 (in the case of FIG. 7, one of the three burners), together with the flow pattern occurring in the combustion mixture.

In certain operating examples, the flow patterns shown are obtained. The liquid fuel supplied to the central tube 31 of the liquid injector exits from the hole 37 as a radial jet.

For the sake of brevity, only one of the six jets is shown. The jet emerging from the outer orifice 37 is immediately atomized by an axial jet of air from the holes 49 in the baffle plate 44 and ignited by means not shown.

This occurs in the fuel atomization region A. The water may be injected by further ducts of the injector.

The atomized fuel/air mixture then flows along the divided flow paths. That is, as shown, one flow path rotates counterclockwise toward the baffle plate and forms a region S, called the flame stabilization region, which is confined by the cup shape of the baffle. Meanwhile, the other flow path rotates clockwise and proceeds in the downstream direction, forming a relatively large area C9, ie, the main combustion area. Most of the air to this main combustion area is supplied from the gap 59 around the baffle plate 44. In this case, completion of the combustion process and dilution of the hot gas by convective mixing takes place in the dilution region. Dilution air is not separately supplied to the dilution area.

Apparently, the flow pattern is symmetrical about the axial arm of the fuel injector. This is because the radial fuel injection stream is evenly spaced around the injector and the air flowing through and around the baffle plate is homogenized by the gaps 59. In this context, the meaning of "clockwise" and "counterclockwise" should be understood.

Cooling of the flame tube occurs as shown in FIGS. 7 and 8.

The outer wall 15 is substantially covered with a large number of small holes which provide a relatively large pressure drop and allow jets of cooling air to impinge on and cool the inner wall 17. In this embodiment, a large number of holes are also formed in the inner wall with a total hole area about four times that of the outer wall. Therefore, the pressure drop across the inner wall is
Compared to that of the outer wall, it is about 1/16th the size. Different sizes and numbers of holes can be used to obtain the desired total cross-sectional pore area. The holes in the inner and outer walls are each positioned so that they are mutually aligned vl and impingement on the outer surface of the inner wall provides forced convective cooling. If the pressure drop across the inner wall and its pores is small, effluent cooling (eff
'usion cooling) occurs. Cooling air exiting the inner wall at low velocity adheres to the inner surface and is entrained in the flow of hot working gas to provide a continuous cooling film. ring 2
7 is a short cylinder located within the opening of the flame tube and away from the inner wall. This is the origin of the cooling film.

In another embodiment (not shown), the first upstream outlet hole in wall I7 is omitted and the cooling film originates from the axial air supplied by the holes in the weir plate.

In either case, the cooling air passing through the double wall of the flame tube has only a negligible effect on the flow pattern of the combustion mixture within the flame tube.

One of the major effects of this all-impingement/outflow cooling method is that the temperature distribution in the flame tube can be maintained more evenly. However, the cross-jet flow of air supplied through the flame tube wall, used before the fire combustion, also serves to stabilize the flame.

Applying continuous film cooling eliminates this advantage, but flame stabilization can be achieved by atomizing the air downstream of the baffle axially via multiple radial jets, as previously discussed. (formation of region S, by which high fuel/air ratios can be reduced to very weak mixing ratios, as can be applied, for example, during unloaded idling).

Furthermore, in the embodiments described above, the mixing and dilution achieved by the transverse or tangential air jets is obtained by the uniform distribution of the air supplied to the baffle plates. In this case, air flows through the gap 59 between the baffle plates and the anti-carbon ventilation
It flows axially through the atomization hole and into the flame tube opening.

According to the invention, extremely high combustion temperatures can be obtained. Additionally, the combination of features listed above allows the fuel to "see" more oxygen than with conventional designs. Compared to conventional designs, a flame tube with a shorter axial length can be used.The invention is particularly suitable for low BTU gaseous fuels.

Further, according to the present invention, the amount of air required for cooling can be significantly reduced, more air can be used in the axial flow path for dilution, and nitrogen oxide release iF1 can be suppressed. Temperature distribution can be controlled. In addition, it produced less smoke in tests.

In one example operation of the embodiment of FIG. 8, the air distribution was as follows. A major portion of the air, ie 59%, passed through the gap 59 between the baffle plates. 14% of the air passed through the flame tube wall for impingement and cooling. 9% of the air flowed through baffle plates 51, 53 and 55. 6% air flowed through the atomization holes 49. 0.9% air flowed from the film cooling gap formed by cylinder 27. Then, 0.7% of the air was used for outflow cooling of the weir plate 69.

The remainder was used for cooling the intermediate duct 77 shown in FIG.

These proportions can, of course, be varied to a certain extent without detracting from the advantages of the present invention. Atomizing air can be kept within a 10% upper limit. Gap between baffle plates 5
The proportion of air passing through 9 can be maintained in the range 50-80%, and the amount of air used for impingement and outflow cooling of the flame tube can be kept at a maximum of 30%.

Although the term "air" is used herein for convenience, air is the most commonly used oxidizing agent, and therefore,
Other gaseous oxidants or coolants can also be used if desired.

Although the embodiment described in IRF uses hexagonal baffle plates, similar results can be obtained using circular or other shaped baffle plates even if the gaps between the baffle plates are not completely uniform. .

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a conventional tubular combustor using a single fuel injector and a segmented flame tube, and FIG. 2 is a partial cross-sectional view of a multi-burner combustor according to the present invention. Fig. 3 is a sectional view showing the main parts of the fuel injector and baffle on a larger scale than Fig. 2, and Fig. 4 is a burner module shown on the same scale as Fig. 3, viewed from the flow side. FIG. 5 is an enlarged view showing the main part of FIG. 4, and FIG. 6 is an end view of 19 in the entire configuration.
7 is a schematic cross-sectional view of a three-nana combustor showing the combustor outlet duct and outer casing; FIG. and FIG. 8 shows the flow path of the fuel/air component of the combustion mixture.
FIG. 3 is a schematic cross-sectional view of a fuel injection nozzle within a flame tube opening; 15.17---Flame tube 19---One injector 25------ Nozzle 37------ Orifice 44---Baffle plate 49---One spray Kahole 4/1. −−−−−One dam board

Claims (1)

Claims: (1) a double-walled flame tube (15, 17) and a nozzle (25) each having a plurality of fuel discharge orifices (37);
) and provided with flame stabilizing means arranged in a plane transverse to the axis of the flame tube (15, 17).
17) A combustor for a gas turbine engine comprising a plurality of fuel injectors (19) provided in a combustor, the stabilizing means comprising a baffle plate (44) from which a nozzle (25) projects, each baffle plate Atomization holes (49) arranged in a ring shape are formed to surround the nozzle (25) at a position corresponding to the orifice (37) but on the upstream side of the orifice (37), and compressed air is supplied to the injector during operation. (19) and around the baffle plate (44), the orifice (37) is fed through the atomization hole (49) and is at least partially radial.
The baffle plate (44) has a shallow cup shape that opens toward the downstream end of the flame tube (15, 17), and forming a confinement wall for the stabilization region and further directing compressed air generally radially inwardly into the flame tube through the double wall with an annular gap therebetween during operation; Since the double wall has small holes that are not radially aligned with each other, the air from the holes in the outer wall (15) collides and the air flows out from the holes in the inner wall (17). A combustor characterized in that an inner wall (17) can be cooled. (2) A weir plate (61) is provided between the flame tube wall (17) and the baffle plate (44), and the weir plate (61)
and the surrounding shape of the baffle plate (44), each baffle plate (
44) A combustor according to claim 1, wherein a uniform air supply path is provided around the combustor. (3) The combustor according to claim 2, wherein the baffle plate has a hexagonal shape and is arranged in a honeycomb shape. (4) Rigid support on the upstream side of the flame tube (15, 17). Parts (2
1), and the fuel injector (19) is mounted on the support member (21).
), the baffle plate (44) is supported by each fuel injector (19), and the fuel injector (19) and each baffle plate (44) are free under the influence of heat. The combustor according to any one of claims 1 to 3, characterized in that it is movable. (5) A plurality of wind shielding strip members (67) are provided, and each strip member (67) connects a pair of adjacent baffle plates (4
4), and this member is loosely attached to at least one of the baffle plates to enable relative thermal movement and promote the spread of flame between adjacent injectors (19). The combustor according to claim 4, characterized in that: (6) Each of the baffle plates (44) has atomization holes (
49), a large number of holes are formed, and each baffle plate (49) is formed with a large number of holes.
4) The combustor according to any one of claims 1 to 5, wherein compressed air is made to flow to the flame side. (7) The proportion of air supplied to and between the baffle plate (44) is 70% of the total air supplied to the combustor - 9
Combustion according to claim 6, characterized in that the proportion of air supplied for cooling the flame tubes (15, 17) is between 10% and 30% of the total air. vessel. (8) The baffle plates (44) are connected by fixed wind shield strips (67) that facilitate the spread of the flame between adjacent baffle plates (44), allowing movement under the influence of limited area heat. The weir plate (61) is attached to a baffle plate, and a center hole is formed in each baffle plate to accommodate each fuel injector (19) with sufficient clearance to allow thermal transfer. A combustor according to claim 2 or 3. (9) The combustor according to any one of claims 1 to 8, characterized in that the cross-sectional area of the hole in the inner wall (17) of the flame tube is larger than that of the hole (15) in the outer wall of the flame tube. . (10) The first aspect of the present invention is characterized in that the inner wall (17) and the outer wall (15) are fixed only at their upstream ends.
- The combustor according to any of clause 9. (11) A plurality of wall partition plates are provided between the inner wall (17) and the outer wall (15) of the flame tube, and the annular gap is axially and/or
Alternatively, the partition plate is divided into cooling zones in the circumferential direction, and the partition plate is fixed to the other wall (15, 17) with a clearance from one wall (15, 17). The combustor according to any one of paragraphs 1-10. (12) An intermediate duct (77) is connected to the downstream ends of the flame tubes (15, 17) to send exhaust gas to the turbine, and non-coherent cooling holes are formed in both walls of this duct (77). A combustor according to any one of claims 1 to 11.