EP1443275B1 - Combustion chamber - Google Patents

Description

The invention relates to a combustion chamber for a gas turbine whose combustion chamber is bounded by an annular outer wall on the one hand and an annular inner wall arranged therein on the other hand. The combustion chamber walls are provided on the inside with a lining formed by a number of heat shield elements, wherein the or each heat shield element forms an interior that can be acted upon by a coolant. The invention further relates to a gas turbine with such a combustion chamber.

Combustion chambers are part of gas turbines that are used in many areas to drive generators or work machines. In this case, the energy content of a fuel is used to generate a rotational movement of a turbine shaft. The fuel is burned to burners in their downstream combustion chambers, wherein compressed air is supplied by an air compressor. The combustion of the fuel produces a high pressure working fluid at a high temperature. This working fluid is fed into a turbine unit downstream of the combustion chambers, where it relaxes to perform work.

In this case, each burner can be assigned a separate combustion chamber, wherein the working medium flowing out of the combustion chambers can be brought together before or in the turbine unit. Alternatively, however, the combustion chamber can also be designed in a so-called annular combustion chamber design, in which a plurality, in particular all, of the burner open into a common, usually annular combustion chamber. The turbine unit adjoining the combustion chamber in the flow direction of the working medium usually comprises a turbine shaft which is provided with a number of rotatable blades connected, forming the annular blade rows. Furthermore, the turbine unit comprises a number of stationary vanes, which are also fixed in a ring shape with the formation of rows of vanes on the inner casing of the turbine. The blades serve to drive the turbine shaft by momentum transfer of the working fluid flowing through the turbine unit, while the guide vanes serve to guide the flow of the working medium between two successive blade rows or blade rows seen in the flow direction of the working medium.

Since the rotational movement of the turbine shaft is generally used to drive the air compressor upstream of the combustion chamber, it is extended beyond the turbine unit so that in the area of the annular combustion chamber upstream of the turbine, the turbine shaft is surrounded in a toroidal manner by the annular combustion chamber. The combustion chamber is bounded by an annular outer wall on the one hand and an annular inner wall arranged therein on the other hand. As a rule, the inner wall of the combustion chamber consists of two or more individual parts, which are screwed together on their side facing the turbine shaft.

In the design of such gas turbines in addition to the achievable power usually a particularly high efficiency is a design target. An increase in the efficiency can be achieved for thermodynamic reasons basically by increasing the outlet temperature at which the working fluid from the combustion chamber and flows into the turbine unit. Therefore, temperatures of about 1200 ° C to 1500 ° C are sought for such gas turbines and achieved.

At such high temperatures of the working medium, however, exposed to this medium components and components are exposed to high thermal loads. Nevertheless, at high Reliability to ensure a comparatively long life of the affected components, is usually a design with particularly heat-resistant materials and cooling of the affected components, in particular the combustion chamber, necessary. In order to prevent thermal stresses of the material, which limits the life of the components, the aim is generally to achieve the most uniform possible cooling of the components.

The combustion chamber wall can be lined on its inside with heat shield elements, which can be provided with particularly heat-resistant protective layers, and which are cooled by the actual combustion chamber wall therethrough. For this purpose, a cooling method also known as "impingement cooling" can be used. In the case of impingement cooling, a coolant, as a rule cooling air, is supplied to the heat shield elements through a plurality of bores in the combustion chamber wall, so that the coolant bounces substantially perpendicularly onto its outer surface facing the combustion chamber wall. The coolant heated by the cooling process is then removed from the interior, which forms the combustion chamber wall with the heat shield elements. Such a configuration is made DE-A-1980568 known.

However, the production of such a cooling system can be very complicated, since to achieve the most uniform cooling of the heat shields very many holes in the combustion chamber wall with a comparatively small cross-section are needed, which can be very time consuming and costly. In particular, the requirements for the tools required for the production of bores are very high, since the cooling air bores are relatively long in comparison to their cross-section, since the wall of the combustion chamber wall for reasons of stability must have a sufficiently large thickness. Furthermore, in the case of a large number of cooling air holes, which in their sum have a high surface area, friction and turbulence may occur in the supply of the coolant. This leads to an increased coolant pressure loss in the coolant circuit, which adversely affects the efficiency of the combustion chamber.

The above-described structure of the annular combustion chamber also has some other disadvantages with respect to maintenance work. In these usually regularly performed maintenance and repair work parts of the combustion chamber such as the heat shield elements or the cooling system used and in particular also components of the downstream turbine unit must be repaired or replaced due to the high thermal and mechanical stress. A disadvantage of the construction of the combustion chamber is that the turbine shaft is not accessible from the combustion chamber during maintenance. Thus, for maintenance work on the turbine shaft in the region of the annular combustion chamber or for repairs to the first guide vanes and rotor blades directly adjoining the combustion chamber, generally all the adjoining vanes and guide vanes of the turbine unit must be removed. Only after the disassembly of all guide vanes and blades of the turbine, it is possible to remove the inner wall of the combustion chamber via the gland facing the turbine shaft and thus to gain access to the turbine shaft. The assembly work is therefore very laborious and time consuming. Due to the comparatively long operating failure of the gas turbine, in addition to the installation costs of the gas turbine, operating costs incurred, which lead to comparatively very high total costs of maintenance and repair of the gas turbine.

The invention is therefore based on the object to provide a combustion chamber of the type mentioned above, which is suitable for comparatively simple construction for a particularly high system efficiency and in which the inner wall of the combustion chamber is comparatively quickly and easily disassembled.

Furthermore, a gas turbine to be specified with the above-mentioned combustion chamber.

With regard to the combustion chamber, the object is achieved according to the invention by arranging a number of coolant distributors in the respective heat shield element associated with each interior space, and by forming the inner wall of the combustion chamber from a number of wall elements fastened on a supporting structure of the inner wall, wherein the support structure of a Number of pieces abutting on a horizontal parting line sections is formed, which are connected to each other in the region of the parting line via a number of obliquely aligned with the inner wall surface screw.

The invention is based on the consideration that for a particularly high system efficiency, a reliable and in particular comprehensive coverage of the heat shield elements should be ensured with coolant. Even with consistent compliance with this requirement, the expenditure on equipment and in particular the production cost can be kept low by the variety of hitherto provided coolant holes are replaced by a simplified system. In order to maintain the cooling effect on the one hand unchanged high and on the other hand to simplify the supply, a division of the coolant flow path in individual sub-paths as close as possible to be cooled heat shield element, ie particularly far at the end of the flow path provided. These functions are fulfilled by the coolant distributors. With regard to the maintenance work, the invention is based on the consideration that the attachment of the various wall elements of the combustion chamber inner wall to each other should be accessible from the combustion chamber and the combustion chamber inner wall is therefore also to be dismantled therefrom. At the same time, the various support structure elements of the combustion chamber inner wall, which abut each other at their horizontal parting line, should be connected to each other by a fastening, which by a vertical force on the parting line connects with each other. These two functions are fulfilled by the obliquely oriented to the inner wall surface screw, which has in addition to the accessibility of the combustion chamber of a sufficiently large vertical force component for fastening two adjacent to the horizontal parting support structure elements.

In order to compensate for the horizontal force component produced by the screw connection aligned obliquely to the inner wall surface of two support structure elements connected to one another by the screw connection, each threaded connection is expediently assigned a key. The feather key avoids that the support structure elements bolted to one another on the horizontal parting line are displaced relative to one another by the horizontal force component of the screw connection. For this purpose, the feather key advantageously runs along the horizontal parting line and is fitted snugly into grooves of the abutting support structure elements, so that they can not move against each other, and preferably only the vertical force component of the screw connection on the horizontal parting line required for fastening the screw connection occurs.

Expediently, a coolant supply line is connected in each case via a coolant distributor to a number of coolant outlet openings. As a result, the heat shields located directly in front of the coolant distributors can be cooled by impingement cooling.

In order to increase the effect of impingement cooling when using the coolant distributor, the outlet openings of the coolant distributor are expediently dimensioned such that the sum of their cross-sectional areas of all outlet openings is smaller than the cross section of the coolant supply line. By this reduction in cross-section in the direction of coolant flow, there is advantageously a nozzle effect, in which the exit velocity of the coolant increases at the outlet openings and thus also improves the effect of the impingement cooling on the heat shield elements.

The coolant heated after the cooling process is expediently discharged through bores in the combustion chamber wall from the interior space between the heat shields and the combustion chamber wall into a coolant discharge system. Due to the shape and a suitable arrangement of the coolant manifold, which ensures a sufficient distance of the coolant manifolds from each other, the heated cooling air can flow through the spaces between the coolant manifolds through to the located on the combustion chamber wall openings of the holes. In order to ensure a uniform cooling of the combustion chamber, the return bores are preferably uniformly distributed over the entire length of the combustion chamber in constant proportion to the number of coolant distributors, so that the coolant can be uniformly discharged in all return bores with an approximately equal return temperature.

In order to position the heat shields covering the surface on the inner wall above those located on the wall coolant distributors, the return bores and the Teilfugenverschraubungen, these are conveniently attached via a system with tongue and groove on the inner wall of the combustion chamber. In this case, heat shield elements are preferably formed at their edges in such a way that, through a double bend, they form an anchorage in the combustion chamber, which can be anchored in a recess of the combustion chamber wall which forms the groove and thus fastened. Conveniently, the recess in the combustion chamber wall is summarized for adjacent heat shield elements, so that adjacent heat shield elements abut each other at their, resulting from the bending end face, and thus constitute a seal for the combustion chamber and the working medium flowing therein.

The abovementioned combustion chamber is preferably part of a gas turbine.

The advantages achieved by the invention are in particular that a large-scale and comprehensive loading of the heat shield elements with coolant is made possible by the use of coolant manifolds even with low production costs. In addition, the coolant pressure loss can be kept low during the cooling of the combustion chamber, so that thus increases the system efficiency of the combustion chamber. The low coolant pressure loss can also be achieved, in particular, because the cooling air distributors require only a few supply bores in the combustion chamber wall. The use of a number of coolant distributors can ensure uniform cooling with low coolant pressure loss, since in the case of coolant supply via a coolant distributor, the coolant branches off from a larger coolant supply line into a plurality of smaller coolant outlet openings only shortly before impingement cooling at the heat shield elements. This ensures that the coolant flows through only a short distance with a relatively small cross-section, so that the coolant pressure loss is limited.

Due to the Teilfugenverschraubung the combustion chamber walls a comparatively simple and quick installation of the combustion chamber walls is possible. In particular, the possibility to remove the inner wall of the combustion chamber, allows rapid access to the turbine shaft and the turbine chamber immediately adjacent blades and vanes of the turbine unit for maintenance and repair work. A time-consuming removal of the runners and guide vanes located in the further course of the turbine unit can therefore be dispensed with by the access made possible by the combustion chamber interior, so that maintenance work can be carried out comparatively easily and in a time-saving manner.

By attaching the heat shield elements with a tongue and groove system is at the same time enough space for the located under the heat shields cooling system and the Teilfugenverschraubung created with a sufficient seal of the combustion chamber interior.

The abovementioned combustion chamber is preferably part of a gas turbine.

FIG 1

einen Halbschnitt durch eine Gasturbine,

FIG 2

einen Schnitt durch eine Brennkammer,

FIG 3

eine Seitenansicht der Ringbrennkammer,

FIG 4

im Schnitt eine Schraubverbindung der Wandelemente der Brennkammerinnenwand, und

FIG 5

im Schnitt einen Ausschnitt der Brennkammerwand.

An embodiment will be explained in more detail with reference to a drawing. Show:

FIG. 1

a half-section through a gas turbine,

FIG. 2

a section through a combustion chamber,

FIG. 3

a side view of the annular combustion chamber,

FIG. 4

in section, a screw connection of the wall elements of the combustion chamber inner wall, and

FIG. 5

in section a section of the combustion chamber wall.

The gas turbine 1 according to FIG. 1 has a compressor 2 for combustion air, a combustion chamber 4 and a turbine 6 for driving the compressor 2 and a generator, not shown, or a working machine. For this purpose, the turbine 6 and the compressor 2 are arranged on a common, also called turbine rotor turbine shaft 8, with which the generator or the working machine is connected, and which is rotatably mounted about its central axis 9. The running in the manner of an annular combustion chamber 4 is equipped with a number of burners 10 for the combustion of a liquid or gaseous fuel.

The turbine 6 has a number of rotatable blades 12 connected to the turbine shaft 8. The blades 12 are arranged in a ring on the turbine shaft 8 and thus form a number of blade rows. Furthermore, the turbine 6 comprises a number of fixed vanes 14, which are also fixed in a ring shape with the formation of rows of vanes on an inner casing 16 of the turbine 6. The blades 12 serve to drive the turbine shaft 8 by momentum transfer from the turbine 6 flowing through the working medium M. The vanes 14, however, serve to guide the flow of the working medium M between two seen in the flow direction of the working medium M consecutive blade rows or blade rings. A successive pair of a ring of vanes 14 or a row of vanes and a ring of blades 12 or a blade row is also referred to as a turbine stage.

Each vane 14 has a platform 18, also referred to as a blade root, which is arranged to fix the respective vane 14 on the inner housing 16 of the turbine 6 as a wall element. The platform 18 is a thermally comparatively heavily loaded component which forms the outer boundary of a heating gas channel for the working medium M flowing through the turbine 6. Each blade 12 is attached to the turbine shaft 8 in an analogous manner via a platform 20, also referred to as a blade root.

Between the spaced-apart platforms 18 of the guide vanes 14 of two adjacent rows of guide vanes is in each case a guide ring 21 on the inner housing 16 of the turbine 6 is arranged. The outer surface of each guide ring 21 is also exposed to the hot, the turbine 6 flowing through the working medium M and spaced in the radial direction from the outer end 22 of the blade 12 opposite him through a gap. The arranged between adjacent rows of guide blades guide rings 21st serve in particular as cover elements, which protects the inner wall or other housing-mounting parts from thermal overload by the hot working medium M flowing through the turbine 6.

The combustion chamber 4 is designed in the embodiment as a so-called annular combustion chamber, in which a plurality of circumferentially around the turbine shaft 8 arranged around burners 10 open into a common combustion chamber space. For this purpose, the combustion chamber 4 is configured in its entirety as an annular structure which is positioned around the turbine shaft 8 around.

To further clarify the embodiment of the combustion chamber 4 is in FIG. 2 the combustion chamber 4 shown in section, which continues toroidally around the turbine shaft 8 around. As can be seen in the illustration, the combustion chamber 4 has an initial or inflow section, into which the outlet of the respective associated burner 10 terminates. Viewed in the flow direction of the working medium M then narrows the cross section of the combustion chamber 4, wherein the self-adjusting flow profile of the working medium M is taken into account in this space area. On the output side, the combustion chamber 4 in longitudinal section to a curvature, through which the outflow of the working medium M from the combustion chamber 4 is favored in a for a particularly high momentum and energy transfer to the flow side subsequent first blade row.

As shown in the illustration FIG. 3 can be seen, the combustion chamber 24 of the combustion chamber 4 is bounded by a combustion chamber wall 25 which is formed on the one hand by an annular combustion chamber outer wall 26 and on the other hand by an annular combustion chamber inner wall 28 disposed therein. The combustion chamber 4 is designed to be able to remove the combustion chamber inner wall 28 in a particularly simple manner, for example for maintenance work, in order to gain access to the combustion chamber inner wall 28 surrounded turbine shaft 8 and the combustion chamber 4 immediately adjacent blades 12 and vanes 14 of the turbine 6 to receive. For this purpose, the combustion chamber inner wall 28 consists of two wall elements 30, which are joined together to form a substantially horizontally extending parting line 31 to the combustion chamber inner wall 28.

The combustion chamber 4 is in particular designed to be able to disassemble the wall elements 30 of the combustion chamber inner wall 28 from the combustion chamber 24. These are, as in FIG. 4 is shown in section, the wall elements 30 connected to the horizontal parting line 31 formed by them with obliquely to the inner surface of the combustion chamber inner wall 28 extending screw 32. In this case, each screw connection 32 comprises a screw 33 guided essentially obliquely to the surface formed by the combustion chamber inner wall 28, which cooperates with a thread 34 incorporated in one of the wall elements 30.

Thus, the wall elements 30 do not move against each other by the resulting due to the oblique to the combustion chamber inner wall 28 screws 33 horizontal force component, the screw 32 is assigned a key 35. This extends in a position close to the respective screw connection 32 along the horizontal parting line 31 of the wall elements 30 and is fitted in grooves of the wall elements 30 of the combustion chamber inner wall 28.

To achieve a comparatively high efficiency, the combustion chamber 4 is designed for a comparatively high temperature of the working medium M of about 1200 ° C to 1500 ° C. In order to enable a comparatively long service life even with these, for the materials unfavorable operating parameters, the combustion chamber wall 25, as in FIG. 5 illustrated, provided on its side facing the working medium M side with a lining formed from heat shield elements 38. Each heat shield element 38 is working medium side with a particularly heat-resistant protective layer. Due to the high temperatures inside the combustion chamber 4, a cooling system is also provided for the heat shield elements 38. The cooling system is based on the principle of impingement cooling, in which cooling air K is blown as coolant under sufficiently high pressure at a plurality of points to the component to be cooled.

The cooling system is designed with a simple structure for a reliable, full coverage of the heat shield elements 38 with cooling air and also for a particularly low coolant pressure loss. For this purpose, the heat shield elements 38 are cooled from their outside by the cooling air K, which is passed through a number of arranged in the respective heat shield element 38 and the combustion chamber wall 25 interior 40 arranged coolant manifolds 42 on the surface of the respective heat shield element 38.

To further clarify the embodiment of the cooling for the heat shield elements 38 is in FIG. 5 in section, a section of the combustion chamber wall 25 is shown. As can be seen in this illustration, a number of the coolant distributors 42 are distributed over the entire surface of the respective heat shield element 38 in order to ensure a uniform cooling. In this case, the coolant K flows through an associated Kühlmittelzuführleitung 44 in the respective coolant distributor 42. Through this, the coolant K is passed through a number of coolant outlet openings 46 on the surface of the heat shield element 38 where it is cooled by the coolant K by impingement cooling. The bores for the Kühlmittelzuführleitungen 44 are easy and time-saving to install in the manufacture of the combustion chamber 4, since only one Kühlmittelzuführleitung 44 is required for each coolant manifold 42.

As shown in the illustration FIG. 5 can still be seen, have the coolant outlet openings 46 of the coolant distributor 42 results in the flow of the coolant K through the coolant distributor 42 to a nozzle effect and, consequently, to an increased exit velocity of the coolant K to the coolant outlet openings 46, whereby the effect the impingement cooling on the heat shield elements 38 increases.

As in FIG. 5 by way of example for the combustion chamber wall 25, the heat shield elements 38 are attached to the combustion chamber wall 28 in a space-saving manner for the attached cooling system and the partial joint connection. For this purpose, a system with tongue and groove is used. In this case, the heat shield elements 38 are formed at their edges in such a way that, through a double bend, they form an anchorage in the direction of the combustion chamber, which can be anchored in a recess in the combustion chamber wall 25 which forms the groove and fastened therewith. Like also in the FIG. 5 it can be seen, adjacent heat shield elements 38 are attached to combined grooves that they touch each other and so seal the combustion chamber 24 of the combustion chamber 4.

Claims (7)

1. Combustion chamber (4) for a gas turbine (1), the combustion space (24) of which is bounded by an annular combustion chamber inner wall (28) and an annular combustion chamber outer wall (26) which are provided on their inside with a lining formed from a plurality of heat shield elements (38), wherein the or each heat shield element (38) forms together with the combustion chamber wall an inner space (40) to which a cooling medium (K) can be applied and in which there is disposed a cooling medium distributor (42) and wherein the combustion chamber inner wall (28) is formed from a plurality of wall elements (30) abutting each other at a horizontal parting joint (31), characterised in that the wall elements (30) are connected to each other in the area of the parting joint (31) by means of a plurality of screw connections (32) oriented at an angle to the inner wall surface.
2. Combustion chamber (4) according to claim 1, wherein a feather key (35) is assigned to the or each screw connection (32).
3. Combustion chamber (4) according to claim 1, wherein a cooling medium supply line (44) is connected to a plurality of cooling medium exit openings (46) via a cooling medium distributor (42).
4. Combustion chamber (4) according to claims 1 to 3, wherein the cooling medium exit openings (46) are dimensioned such that the sum total of the cross-sectional areas of all the cooling medium exit openings (46) of a cooling medium distributor (42) is less than the cross-sectional area of the assigned cooling medium supply line (44).
5. Combustion chamber (4) according to one of claims 1 to 4, wherein the or each inner space (40) is connected to a cooling medium discharge system via a plurality of holes.
6. Combustion chamber (4) according to claim 1, wherein the heat shield elements (38) are fixed to the combustion chamber inner wall (28) or to the combustion chamber outer wall (26) via a tongue and groove system.
7. Gas turbine (1) with a combustion chamber (4) according to one of claims 1 to 5.

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