JPH06213444A - Combustion chamber of gas turbine - Google Patents

Abstract

PURPOSE: To reduce NOx emission by minimizing the amount of cooling air. CONSTITUTION: An inner wall 33 is cooled through collision with by air from an air tank via the plurality of collision tubes 40, which opens into a cooling chamber 42 adjacent to the inner wall 33 in a primary combustion region. Outlet edge parts of inner rubes surrounding a secondary combustion region and the outlet of the cooling chamber 42 of the primary combustion region are connected only to burners 20 via a circular path 43 through which the collision pipes 41 penetrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas turbine combustion chamber having a bowl-shaped combustion space, in which the wall of the combustion space is provided with a burner having a circular cross section from a combustion chamber inlet to a gas turbine. A combustion chamber of the type which extends to the inlet of a hot gas casing associated with the air turbine and is thereby exposed to and cooled by the air stream fed from the compressor of the gas turbine to the air reservoir.

[0002]

2. Description of the Related Art A bowl-shaped gas turbine combustion chamber having an air-cooled inner tube is known, for example, from U.S. Pat. No. 3,422,620. In this case, at least the upper portion of the inner tube is substantially composed of a plurality of wall portions having a small area and overlapping in the turbine axis direction. These walls are
It has a plurality of openings distributed circumferentially on the side opposite to the combustion space, through which air flows into the combustion space. In this case, the openings are arranged so that the resulting cooling air film adheres to the inner tube wall and forms a cooling insulation layer for the inner tube.

For the purpose of burning gaseous or liquid fuel while suppressing the generation of harmful substances, a so-called "lean premixed combustion" system has recently become popular. This is a system in which the fuel and the combustion air are premixed as evenly as possible before burning. This combustion method, which is normally done in gas turbine installations, is carried out with a large amount of excess air, which results in a relatively low flame temperature, which in turn leads to the desire to generate nitrogen oxides. It is suppressed to the value.

The above known gas turbine combustion chamber has the following drawbacks. That is, the air consumption for cooling purposes is extremely large, and as a result of supplying cooling air into the inner tube, this air cannot be used for the original combustion process downstream of the flame. The combustion chamber therefore cannot operate at the required high excess air value.

[0005]

SUMMARY OF THE INVENTION The invention is therefore based on minimizing the consumption of cooling air and reducing the emission of NO _x in the case of a gas turbine combustion chamber of the type mentioned at the outset. .

[0006]

According to the present invention, this problem has been solved by the following. That is, the combustion space is divided into a primary combustion region and a secondary combustion region, the flow restricting wall portions of these regions are separated so as to be cooled independently of each other, and in the primary combustion region, the flow is limited. The limiting wall is collision cooled through multiple collision tubes,
These collision tubes are opened from the air reservoir to the cooling chamber adjacent to the flow restricting wall portion, and the secondary combustion region located downstream is restricted by the inner wall of the double wall. The inlet end facing the casing is opened toward the air reservoir, and the inner pipe outlet end facing the primary combustion region and the cooling chamber in the primary combustion region are both on the outlet side. Thus, only the burner at the inlet of the combustion chamber is guided and connected through the annular passage that penetrates the collision tube.

The effects of the present invention are found especially in the following points. In other words, with the new measures, both cooling air streams are guided in parallel, so that the pressure drop in both cooling stages can be maintained slightly, which has a positive effect on the total pressure loss value of the combustion chamber. . Finally, all the cooling air is fed to the combustion process after cooling is complete, and the pollutant emission values are improved as desired.

All of the air that cools the primary and secondary fuel zones is obtained directly from the sump and, after cooling, is directed to the burner instead of to the combustion space so that the area of the primary combustion zone is Is forced to produce intersections of both cooling air streams. Therefore, the cooling chamber in the primary combustion region communicates with the annular passage via a plurality of outlets, and also the outlets are associated with each collision tube. This measure of supplying both air streams together in the annular passage enables evenly distributed and low loss air guidance.

The wall which extends from the combustion chamber plane to the inlet of the hot gas casing and which is cooled is advantageously constructed in one piece. In this way, on the one hand, the production is simple and, on the other hand, leakage losses into the combustion space are minimized.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to an example of the illustrated single shaft axial flow gas turbine.

Only the components necessary for understanding the invention are shown in the drawings. Of the gas turbine equipment, for example,
Not shown are the entire exhaust casing with the exhaust gas pipe and the flue, the rotor bearing and the inlet part of the compressor part. The flow direction of the working medium is indicated by arrows.

In the device shown schematically in FIG. 1, the side of the gas turbine 1 essentially consists of a rotor 5 with moving blades and a blade holder 11 with stationary blades. The blade carrier 11 is suspended via a projection in a corresponding receptacle in the turbine casing 13. An exhaust casing 14 is flange-connected to the turbine casing 13.
The exhaust casing essentially consists of a hub-side ring-shaped inner part and a ring-shaped outer part, both of which limit the diffuser 15.

The turbine casing 13 is likewise
It has a reservoir 50 of compressed combustion air. Compressed air is sent from the diffuser 16 of the compressor 2 into the air reservoir 50. In that case, the outflow side diffuser end is configured as a radial diffuser 17. Only the last four stages of the compressor are shown. Like the blade holder 11 of the turbine, the blade holder 12 of the compressor is suspended via projections in corresponding receptacles in the turbine casing 13. The moving blades of the compressor and the moving blades of the turbine are mounted on a common shaft 5. The central axis of the shaft 5 coincides with the vertical axis 4 of the gas turbine unit.

The shaft portion arranged between the turbine and the compressor is constructed as a drum 6. This drum is
It is surrounded by the drum cover 7 over its entire axial length. The drum cover 7 is connected to the diffuser outer casing of the compressor 2 via a rib (not shown). This outer casing is shown in FIG. 1 in a simplified manner in one piece with the blade holder 12 of the compressor 2. The drum cover 7 forms a shroud of the blade of the final compressor guide blade row on the compressor side. On the turbine side, the drum cover, together with the turbine rotor end side, limits the radially extending wheel lateral space. This space forms the outlet end of the annular space 8. The annular space 8 emerges from the hub behind the last compressor blade row and extends between the drum cover 7 and the drum 6. The rotor side cooling air branched from the compressor is guided through the annular space 8.

Air reservoir 5 inside the turbine casing 13
0 also surrounds the toroidal hot gas casing 9. The hot gas casing 9 guides the combustion gas from the combustion chamber 3 to the turbine inlet. The circular inlet of the hot gas casing 9 is located in the flange plane 38 of the turbine casing 13. The hot gas casing 9 is covered with a thin plate outer casing 51 for cooling purposes. Thereby, the cooling chamber 10 is formed. Air from the hub diffuser 18 is sent into the cooling chamber 10. The hub diffuser 18 emerges from the compressor diffuser 16 and is limited on the one hand by the drum cover 7 and on the other hand by the diffuser outer wall 19. The diffuser outer wall 19 is connected to the drum cover 7 via a rib (not shown). In the example shown, the members supporting the diffuser outer wall 19 likewise form the inner ring of the radial diffuser 17.

In this embodiment, the vertical combustion chamber 3 has the outer wall 3
Turbine casing 1 in the flange plane 38 via 9
It is supported by 3.

Combustion air is sent from the air reservoir 50 into the burner chamber 22 of the bowl-shaped combustion chamber 3. The combustion space of the combustion chamber 3 is open to the hot gas casing 9 on the outlet side.

The combustion chamber has a premix burner 20 at its upper end.
Is equipped with. These burners are, for example, EP-B1.
-321 809. A premix burner of this kind, which is shown diagrammatically in FIG. 2, is a so-called multi-conical burner. The burner consists essentially of two hollow conical sections 23, 24 which are nested in the flow direction. In that case, the central axes of both parts are offset from each other. Both parts 23, 24
The adjoining wall of the said has its longitudinal extension forming a connecting slit 25 for combustion air. Combustion air reaches the inside of the burner through these slits. A fuel nozzle 21 for liquid fuel is arranged inside the burner. Fuel is injected into the hollow cone at an acute angle. The resulting conical contoured liquid fuel surrounds the tangential inflowing air for combustion. The combustion concentration becomes gradually leaner due to the mixing with the combustion air. The burner can likewise be operated with gaseous fuel. For this purpose, in the area of the connecting slits, gas inlet holes are provided which are distributed longitudinally in the walls of both parts 23, 24. In the case of gas operation, mixture formation with combustion air is already started in the area of the inlet slit 25. It goes without saying that a mixed operation with two types of fuel is also possible in this way.

At the burner outlet, as uniform a fuel concentration as possible is adjusted over the cross section of the circular ring. At the burner outlet, a constant backflow region having a hemispherical shape is generated, and ignition is performed at the tip of this region.

Since the combustion gas reaches a high temperature during combustion, cooling of the combustion chamber wall is particularly required. This cooling requirement is in the case of so-called low NO _x burners, for example the premixed burners on which the present invention is based, i.e. burners which require a relatively modest amount of cooling air to cool a large inner tube surface area. , Will be even stronger.

Downstream of the burner opening, a bowl-shaped combustion space extends to the inlet of the hot gas casing 9. The interior of the combustion space is limited by the inner walls 33 to be cooled, which inner walls 33 are mostly constructed as self-supporting structures.

This combustion chamber is equipped with 37 burners. The arrangement of these burners can be known from FIG. 3, which shows the quadrant cut out. These burners are distributed on the front plate 26 as evenly as possible. The front plate 26 is formed from hexagonal segments and forms a heat shield.

The inside of the combustion chamber is divided into two regions, and the common wall portion 33 of these regions is cooled by different cooling types.

The secondary combustion region 31, which is located downstream and reaches the inlet of the hot gas casing 9, is limited by the double wall inner tube. The inner tube consists of a welded sheet metal structure without a flange, which is held via spacers, not shown. The inner tube is open at the turbine end and forms a cooling air inlet in the flange plane 38. For this purpose, an inner wall 3 is provided in the area of the secondary combustion zone.
A ring-shaped intermediate wall 34 is provided around the circumference of the circle 3.

The annular space 35 between the double walls 33, 34 of this inner tube obtains air directly from the air reservoir 50, as can be seen in FIG. Due to the effective convective cooling, the air flows countercurrent to the combustion chamber flow in the direction of the primary combustion zone 30.

Cooling of the walls of this heavily loaded area 30 is effected via individually supplied impingement tubes 41, as shown in FIG. The required air is also withdrawn directly from the air reservoir 50 via the annular passage 40.

At the end of the primary combustion zone 30 or the beginning of the secondary combustion zone 31, an annular space 35 is arranged to extend in a further intermediate wall 36 away from the inner wall 33. This intermediate wall 36, which follows the inner wall at the boundary of the two regions 30, 31, extends into the burner plane, forming an annular cooling chamber 42. Another middle wall 3
No. 4 also extends into the burner plane, and the annular passage 40 described above
And is connected to the outer wall 39 by the burner plane.
The annular space 35 of the secondary combustion zone thus opens in the area of the primary combustion zone into an annular passage 43 which is surrounded by the annular passage.

A plurality of impingement tubes 41 are provided over the entire height of the primary combustion region, and these tubes 41 are evenly distributed over the entire circumference of the combustion chamber as shown in FIG. These collision tubes 41 have an inlet in the extended intermediate wall 34, penetrate the annular passage 43 and the intermediate wall 36,
It opens near the inner wall in the cooling chamber 42. After colliding with the inner wall 33 to be cooled, the cooling air flow is deflected, and then exits from the cooling chamber 42 via the multiple outlets 44. 2 and 3
It can be seen from the above that the outlet 44 is assigned to each collision tube. But you don't have to. The important point is that the total cross-sectional area of the outlet is selected to be larger than the flow-through cross-sectional area of the collision tube. Such impingement cooling of the primary combustion region thereby has the effect of keeping the pressure drop low. Assigning an outlet to each impingement tube additionally has the effect of preventing the generation of lateral flow in the cooling tube 42, which diminishes the effect of impingement cooling.

The outlet 44 opens into a passage 43 which opens toward the burner chamber 22 on the burner side. This burner room 22
Are restricted to the outside by a burner chamber cover 52 that is flanged to the burner chamber outer wall 39. The inside is restricted by the front plate 26 to which the burner 20 is attached.

The annular passage 43 thus serves as a common guide for the impingement cooling air and the cooling air supplied to the secondary combustion zone. The inner pipe 33, which is oriented toward the primary combustion region,
The outlet of 34 and the outlet of the cooling chamber 42 thus open directly to the burner chamber inlet via the annular passage 43 so that all the air is supplied to the combustion process without a significant pressure drop.

[Brief description of drawings]

FIG. 1 is a partial vertical cross-sectional view of a gas turbine.

FIG. 2 is a partially enlarged view of a primary combustion region of a burner chamber.

3 is a partial cross-sectional view of a primary combustion region taken along line 3-3 of FIG.

[Explanation of symbols]

 1 Gas Turbine 2 Compressor 3 Burner Chamber 4 Turbine Axis 5 Rotor 6 Drum 7 Drum Cover 8 Annular Space 9 High Temperature Gas Casing 10 Cooling Chamber 11 Gas Turbine Blade Holder 12 Compressor Blade Holder 13 Turbine Casing 14 Exhaust Casing 15 Turbine Diffuser 16 Compressor diffuser 17 Compressor radial diffuser 18 Compressor hub diffuser 19 Diffuser outer wall 20 Burner 21 Burner nozzle 22 Burner chamber 23, 24 Burner part 25 Tangent slit 26 Front plate 30 Primary combustion area 31 Secondary combustion area 33 Inner wall 34,36 Intermediate wall 35 Annular space 38 Flange plane 39 Outer wall 40 Annular space 41 Collision tube 42 Cooling chamber 43 Annular passage 44 Outlet 50 Air reservoir 51 Thin plate outer tray 52 Combustion chamber Bar

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Reiner Gize, Germany Worms 15 Huntschusstraße 1 (72) Inventor Stefan Tiren Switzerland Dugingen Oberdorf 4

Claims (5)

[Claims] 1. A gas turbine combustion chamber having a bowl-shaped combustion space (30, 31), wherein a wall portion (33) of the combustion space is from a fuel chamber inlet having a burner (20) in a circular cross section. , Of the type which extends to the inlet of a hot gas casing (9) associated with the gas turbine (1) and is thereby exposed to and cooled by the air stream supplied by the compressor (2) of the gas turbine, Combustion space is 1
It is divided into a secondary combustion zone (30) and a secondary combustion zone (31), the flow limiting inner walls (33) of these zones being separated and cooled independently of each other, and also the primary combustion zone (30). Then, the flow restricting walls are cooled by collision through the plurality of collision tubes (41), and these collision tubes (41) collect in the air reservoir (5
0) to the cooling chamber (42) adjacent to the flow restricting inner wall, and further to the secondary combustion region (3) located downstream.
1) is limited by a double-walled inner tube (33, 34), the inlet end of this inner tube facing the hot gas casing (9) being open towards the air reservoir (50), Further, the outlet end of the inner pipe (33, 34) facing the primary combustion region (30) and the cooling chamber (42) in this region (30) are both on the outlet side, and the collision pipe (41) Burner (20) at the combustion chamber inlet through an annular passage (43) passing through
A gas turbine combustion chamber having a pot-shaped combustion space, characterized in that it is guided and connected only to. 2. A cooling chamber (42) in the primary combustion zone (30).
A gas turbine combustion chamber according to claim 1, characterized in that it communicates with the annular passage (43) via a plurality of outlets (44). 3. The flow-through cross section of the collision tube (41) has an outlet (44).
Gas turbine combustion chamber according to claim 2, characterized in that it has a dimension smaller than the cross section of the gas turbine combustion chamber. 4. Gas turbine combustion chamber according to claim 2, characterized in that an outlet (44) is associated with each collision tube (41). 5. A gas turbine combustion chamber according to claim 1, characterized in that the cooled inner wall (33) extending from the combustion chamber inlet to the hot gas casing (9) is integrally formed.