CN107923616B - Cooling air optimized metal insulation element - Google Patents

Abstract

The invention relates to an insulating element (01) for a heat shield (21) used in a combustion chamber (26) of a gas turbine. The insulating element comprises: a wall (03) having a hot side (04) and a cold side (05) opposite the hot side (04); and two first edge sections opposite each other (06), first edge sections respectively extending from the hot side (04) beyond the cold side (05) and present in the edge sections (06) distributed over the length of the edge sections A plurality of cooling air ports (11, 12) arranged in the ground. In order to improve the ventilation of the side gap between the two insulating elements ( 01 ), there is at least one cooling air pocket ( 13 ) in the wall ( 03 ) starting from the cold side ( 05 ). Here, cooling air pockets are arranged in the region of the first cooling air openings (11, 12).

Description

Cooling air-optimized metal thermal insulation elements

technical field

The invention relates to an insulating element for use in a heat shield, in particular for lining the combustion chamber walls of a gas turbine.

Background technique

Very high temperatures occur in the combustion chamber of the gas turbine, which, in the absence of effective protective measures, can lead to immediate damage to the gas turbine. Therefore, in a known manner a heat shield is used which separates the hot combustion chamber from the structure behind the heat shield which is protected from thermal damage. For this purpose, heat shields are lined with ceramic insulating tiles and/or metal insulating elements.

Insulation tiles or elements generally have a flat or slightly arched shape with a hot side directed towards the combustion chamber and an opposite cold side and surrounding edges. They are respectively fastened to a load-bearing structure arranged below the insulating tile or the insulating element. In a side-by-side multiple arrangement, the heat shield is formed as closed as possible. Here, a plurality of insulating tiles or insulating elements are positioned spaced apart from one another, so that side gaps are respectively formed between the edges of adjacent insulating elements. In order to be able to withstand different thermal expansions between the insulating tiles or elements and the load-bearing structure arranged thereunder, side clearances between the insulating tiles or elements are necessary.

However, the use of insulating tiles or elements alone is often insufficient to prevent progressive damage. Therefore, in a known manner, cooling air is used to prevent the occurrence of critical component temperatures. In spite of the high temperature resistance of the insulating tiles and the insulating elements, metal-cooled insulating elements are especially required during operation of the gas turbine. In particular, the risk of component damage due to overheating exists in the fixing devices for fixing the insulating tiles or elements, as well as in the heat shield in the region of the side gaps between the insulating tiles or elements. At the load-bearing structure, and at the ends present in the transition between the heat shield and the subsequent structure, where this overheating is caused by the entry of so-called hot gases from the combustion chamber. In order to prevent the ingress of hot gases, cooling air is introduced in a known manner into the side gaps in a targeted manner, so as to protect the load-bearing structure and the fixing device under the insulating tile or the insulating element from overheating.

In practice, however, there is often a problem of uneven distribution of the cooling air over all the side gaps. This is due on the one hand to the unavoidable fluctuations in the width of the gaps between the individual insulation tiles or elements, and on the other hand due to the uneven distribution of the cooling air, which is the norm, especially due to the required fixtures rather than exceptions. Furthermore, there are special problems in the transition from the heat shield of the combustion chamber to the inlet of the subsequent turbine. This results in insufficient cooling in some areas and wasted cooling air in others.

For this purpose, document WO 2013/135702 A2 discloses a metal thermal insulation element which is loaded with cooling air on the cold side. For an advantageous distribution of the cooling air into the side gap, the two opposite edge sections have a plurality of cooling air holes arranged in a row. Through the cooling air holes, the cooling air is blown directly into the side gap, thereby advantageously blocking the entry of hot gases.

Although improvements are achieved in terms of the interception of the gaps for the entry of hot air by the above-mentioned insulating elements with cooling air openings arranged in the gaps of the edge sections, however, as it occurs in practice, The risk of hot air ingress increases especially at the ends of ventilated edge sections.

SUMMARY OF THE INVENTION

The object of the present invention is therefore to improve the distribution of the cooling air over the length of the gap, taking into account the arrangement of the insulating elements in several rows.

The proposed task is achieved by a thermal insulation element according to the invention as taught in claim 1 .

A heat shield according to the invention using the heat insulating element according to the invention is proposed in claim 10 .

Advantageous embodiments are the subject-matter of the dependent claims.

A thermal insulation element of this type forms part of a thermal shield, which is used in particular for being arranged in the combustion chamber of a gas turbine. Here, a number of insulating elements of this type are used on the heat shield. The insulating element firstly includes a wall. The wall has a hot side to which a thermal medium can be applied and a cold side opposite the hot side. As part of a heat shield used in a combustion chamber, the hot side of the heat insulating element is directed towards the interior of the combustion chamber with the hot gases, whereas the cold side is directed away from the combustion chamber. In this case, the wall can be formed flat in its simplest form, but can also have one or more curved shapes.

At least the insulating element has a surrounding edge surrounding the wall. At least two mutually opposite first edge sections are arranged on the surrounding edge. Here, the first edge sections extend substantially parallel to each other along the longitudinal direction. The first edge sections extend linearly parallel to each other in the longitudinal direction as long as they are flat walls with a rectangular shape. In the case of a dome-shaped wall, the first edge sections extend substantially parallel to each other for their part, and here substantially in the longitudinal direction. The first edge sections are designed at least in such a way that, when three identical insulating elements of this type are arranged next to one another, a substantially uniform gap is produced between adjacent first edge sections in each case. The first edge section of the thermal insulation element here extends from the hot side through the cold side as far as the upper side of the web.

In this case, a plurality of cooling air openings are present in each of the first edge sections, which are distributed over the length of the edge section and extend from the inside of the respective edge section to the outside of the respective edge section. Thus, when cooling air is introduced onto the cold side of the wall, the cooling air can pass from the inner side of the edge section to the outer side, thereby entering the gap between adjacent insulating elements.

According to the invention, at least one cooling air pocket is now added to further optimize the cooling air distribution in the gap in the wall. Here, the cooling air pocket is arranged on the cold side and is therefore embedded in the wall in the direction from the cold side towards the hot side. Here, the cooling air pocket is arranged in the region of the first cooling air opening. It is necessary here that the cooling air pockets extend from the inner side in the transverse direction, ie essentially transversely to the inner side. In order to achieve the desired cooling air distribution improvement, it is necessary to arrange the first cooling air port at least partially within the cooling air pocket. Therefore, the cooling air introduced on the cold side can be introduced into the first cooling air port through the cooling air pocket.

By modifying the usual arrangement of the cooling air openings, in particular the first cooling air openings, a targeted cooling of the cooling air in the region of the first cooling air openings can be achieved when using cooling air pockets which are incorporated into the walls. Improvements introduced to gaps. As a result, a better adjustment of the cooling air distribution over the extension of the gap can be achieved. This in turn has the advantage that less cooling air consumption is required, and the ingress of hot gases is effectively avoided.

An advantageous configuration of the cooling air bag is achieved when the cooling air bag has advantageous dimensions relative to the first cooling air opening. In contrast, therefore, the smallest free cross-section of the cooling air opening is considered to be used as the cooling air cross-section. Advantageously, the cooling air pocket has a first cross section which is at least 0.5 times and at most 10 times the cooling air cross section in its extension from the inside of the first edge section to the end of the cooling air pocket. . Here, the first cross section is considered to be parallel to the selected cooling air cross section. It is particularly advantageous here if the first cross section of the cooling air pocket corresponds to at least one and a maximum of five times the cooling air cross section. This advantageous configuration of the cooling air bag ensures on the one hand that sufficient cooling air can be fed efficiently through the cooling air bag to the first cooling air opening; Size is no longer effective for improving cooling air distribution.

Similarly, it is advantageous if the cooling air pockets in the region of the first cooling air openings have a second cross-section transverse to the selected cooling air cross-section which is at least 2 times and at most the cooling air cross-section. 20 times. Here, the selected second cross section lies in a plane which extends substantially through the middle of the cooling air opening and is oriented substantially transverse to the cooling air cross section. It is particularly advantageous here to select for the second cross section of the cooling air bag at least 2 times and at most 10 times the cooling air cross section.

Furthermore, it is advantageous to determine the size of the cooling air bag taking into account the size of the thermal insulation element. It is advantageous here that the cooling air pocket has an extension in the transverse direction transverse to the inner side of the first edge section, which extension is at least 0.05 times and at most 0.2 times the width of the insulating element (in the direction extending from the cooling air pocket). measured in the same direction). Arranging the cooling air bag within such a dimensional relationship has proven to be advantageous in terms of introducing cooling air from the cold side into the cooling air bag for routing through the first cooling air port.

It is also advantageous here that the cooling air pocket has a depth from the cold side which is at least 0.2 and at most 0.5 times the material thickness of the wall (from the cold side up to the hot side at the same location). Thereby, on the one hand, a sufficient cross-section is provided for realizing the cooling air pocket for guiding the cooling air flow through the first cooling air opening, and also so that the wall is not weakened by the unnecessary addition of the cooling air pocket .

As long as a sufficient flow from the cold side through the cooling air bag into the first cooling air port is ensured, the specific implementation of the cooling air bag is not important for the time being. However, it is advantageous for this if the surrounding edges of the cooling air pockets are truncated or rounded in the transition to the cold side.

According to the invention, it is necessary that the first cooling air openings are arranged in sections in the region of the cooling air pockets. It is advantageous here that at least 25% and a maximum of 75% of the inner cross-section of the cooling air opening is arranged in the cooling air pocket. It is particularly advantageous to arrange the first cooling air openings at an inner side having at least 40% but a maximum of 60% within the cooling air pocket. This almost results in the first port air ports being arranged in the middle of the cold side, such that about half of the first port air ports are arranged above the cold side and the other half of the first cooling air ports are arranged below the cold side.

The design of the use of the cooling air bag in conjunction with the first cooling air opening results in an advantageously flush arrangement of the first cooling air opening with the cooling air bag base. In contrast to this, however, there is no disadvantage when there is a small distance between the base of the cooling air bag and the first cooling air opening. Advantageously, this distance is at most 0.5 times the depth of the cooling air bag, ie the distance from the cold side to the base of the cooling air bag. It is particularly advantageous if the distance from the base to the first cooling air opening is at most 0.25 times the depth of the cooling air pocket.

The embodiment and orientation of the cooling air openings (the first cooling air opening as well as the other cooling air openings) are not important for the time being. In this regard, reference may be made to the known prior art. It is advantageous here that the cooling air openings extend from the inner side of the first edge section to the outer side of the first edge section and are oriented substantially perpendicular to the inner or outer side. For this, an angular deviation of +/- 15 degrees is unimportant.

With regard to the orientation of the outside of the first edge section and the orientation of the inside of the first edge section, various possibilities are also available, wherein advantageously the outside and the inside are also oriented substantially perpendicular to the hot side and substantially perpendicular to the cold side side orientation. In this regard, it is also unimportant when there is an angular deviation of +/- 15 degrees.

It is also advantageous here that the material thickness of the first edge section is at least 0.5 times the material thickness of the wall and at most 2 times the material thickness of the wall. This results in favorable strength and avoids unnecessary thermal stress. It is particularly advantageous if the material thickness of the first edge section corresponds substantially to the material thickness of the wall.

Particularly advantageously, the insulating element has a further second edge section at the circumferential edge, which connects the respective one end of the first edge section to one another. Here too, the second edge section extends from the hot side beyond the cold side. In relation to the first cooling air opening and the further cooling air openings, here the first cooling air opening (and the cooling air pockets subordinately adjacent to the second edge section) are arranged as the first of a row of cooling air openings . This takes advantage of the particular advantage of the embodiment with cooling pockets according to the invention, namely by arranging the first cooling air opening with cooling air pockets as the first cooling air opening of the plurality of cooling air openings at the second edge Ahead of the section, an advantageous cooling air supply is achieved in the region of the corners of the insulating element.

It is also advantageous for this when the thermal insulation element comprises ribs arranged on the cold side. The rib is also suitable for connecting between the two first edge sections and is configured protrudingly on the cold side, wherein the rib extends substantially parallel to the second edge section at intervals. The first cooling air opening with the cooling air pocket is here located between the rib and the second edge section. In a particularly advantageous manner, the further cooling air openings are arranged on the opposite side of the rib, ie on the side of the rib facing away from the second edge section. With the use of ribs arranged on the cold side next to the first cooling air openings, this advantageous configuration enables an advantageous flow of air into the first cooling air openings for use in the thermal insulation element Targeted ventilation in the corner areas.

The specific embodiment of the second edge section and the specific embodiment of the ribs are not important, but in a particularly advantageous manner they are formed substantially identically to the first edge section and in this respect also extend to the first edge section the upper side of the tab. Here, they have a material thickness substantially identical to the first edge section and are also oriented substantially perpendicular to the hot side or substantially perpendicular to the cold side, wherein an angular deviation of +/- 15 degrees is also regarded as not important.

The heat insulating element according to the invention constitutes a new heat shield using the heat insulating element according to the invention. Here, the heat shield is especially provided for use in the combustion chamber of a gas turbine. Here, the heat shield forms at least partially the walls of the combustion chamber. In this case, the heat shield has a support structure on which a plurality of heat insulating tiles and/or heat insulating elements are fastened, wherein at least one heat insulating element adopts an embodiment according to the invention or an embodiment advantageous for this. In this case, the insulating tiles or the insulating elements are arranged flat against each other when one gap is loaded. An improved heat shield is achieved by using the heat insulating element according to the invention, since the cooling air distribution in the gap between the two heat insulating elements can now be improved.

It is particularly advantageous here if, in the heat shield, a complete circumferential row of heat insulating elements is each provided with heat insulating elements according to the above-described embodiments, and in this regard, in each case at least one cooling air pocket in the first cooling air opening . Here, it is necessary to arrange the thermal insulation elements according to the invention in a surrounding row such that the first edge sections of the respective thermal insulation elements are arranged adjacent to each other at the gap, wherein the second edge sections are positioned to each other in the extension middle.

Furthermore, it is particularly advantageous if, in particularly advantageous heat shields, the surrounding row of heat insulating elements according to the invention is arranged at the downstream end of the heat shield. Here, the single heat insulating element is oriented such that the two edge sections of the heat insulating element point at the downstream end of the heat shield.

A particularly advantageous cooling air supply is obtained in the end region of the heat shield, in particular in the gap at the output end of the combustion chamber, by a particularly advantageous embodiment of the heat shield, wherein the heat shield is in the heat shield. At the end of the hood there is a cooling air pocket present at each individual insulating element, the cooling air pocket having a first cooling air hole. Especially in this region in the transition to the guide vanes following the combustion chamber in a gas turbine, the entry of hot gases into the corners of the insulating elements in the transition ahead of the guide vanes is avoided.

Description of drawings

In the following figures, embodiments of thermal insulation elements and their arrangement in the combustion chamber are schematically depicted. Icon:

Figure 1 schematically shows a combustion chamber of a gas turbine with a heat shield;

Figure 2 shows an exemplary embodiment of a thermal insulation element according to the invention in a perspective view on the cold side;

FIG. 3 shows a detailed view of the corner region of the thermal insulation element according to FIG. 2 .

Detailed ways

FIG. 1 schematically and exemplarily shows a cross-section of the combustion system of the combustion chamber 26 . The burner 27 is arranged in the inlet in the upper region of the combustion chamber 26 . The mixing of fuel and compressed air takes place there. Combustion occurs in combustion chamber 26 . Through the outlet at the downstream end 24 of the combustion chamber 26 , the hot combustion gases enter the turbine where the fuel gases contact the first stationary vanes 28 . To prevent fouling, the combustion chamber 26 is lined with ceramic insulating tiles 23 and metal insulating elements 01 , which are fastened to the bearing structure 22 of the heat shield 21 .

Figure 2 shows schematically and exemplarily a metal thermal insulation element 01 used in a thermal shield 21 for a combustion chamber 26 of a gas turbine in an embodiment according to the invention. The insulating element 01 comprises a wall 03 with a hot side 04 which can be loaded with a thermal medium, a cold side 05 opposite the hot side 04 and a surrounding edge. The wall portion has an arcuate shape and is substantially rectangular in configuration.

At the circumferential edge, there are two first edge sections 06 opposite one another, which extend from the hot side 04 through the cold side 05 as far as the web upper side 07 . The first edge section 06 here extends in the longitudinal direction of the insulating element 01 . In this embodiment, the longitudinal direction approximately corresponds to the flow direction in the exemplary application in the heat shield shown in FIG. 1 . Furthermore, the two opposing first edge sections 06 each have an inner side 08 extending from the cold side 05 to the upper side 07 of the web, and both have an outer side 09 extending from the hot side 04 to the upper side of the web. Furthermore, a second edge section 16 is located at the surrounding edge, which second edge section 16 connects the two ends of the opposite first edge section 06 to each other at the corners 18 of the insulating element 01 . The second edge section 16 is substantially identical in configuration to the first edge section 06 and extends transversely to the first edge section 06 .

This embodiment also has ribs 17 extending parallel to and at a distance from the second edge section 16 , which are arranged on the cold side 05 and which also connect the two first edge sections 06 to each other.

Along the first edge section 06 there are respectively a plurality of cooling air openings 11 , 12 , wherein the first cooling air opening 12 is arranged at the second edge as the first of the plurality of cooling air openings 11 , 12 in a row Between the segment 16 and the rib 17 , while all other cooling air openings 11 are arranged at the side of the rib 17 facing away from the second edge segment 16 . In the region of the first cooling air openings 12 there are cooling air pockets 13 in the wall 03 starting from the cold side 04 .

FIG. 3 shows the first cooling air opening 12 and the cooling air pocket 13 in a detailed view in the region of the corner 18 of the insulating element 01 in FIG. 2 . The cooling air pockets 13 extend transversely to the inner side 08 from the inner side 08 , ie extend substantially corresponding to the orientation of the first cooling air openings 12 . In this embodiment, approximately half of the first cooling air openings 12 are arranged within the cooling air pockets 13 , ie the middle of the first cooling air openings 12 is approximately at the level of the cold side 04 .

The dimensions of the cooling air pockets 13 are selected such that sufficient cooling air can flow into the first cooling air openings 12 without unnecessarily weakening the wall 03 . Therefore, in this embodiment, the depth of the cooling air pocket 13 is slightly greater than the depth of the first cooling air port 12 . Furthermore, the cross section of the cooling air pocket 13 in a plane parallel to the inner side 08 (the cooling air holes 11 , 12 are oriented substantially transverse to the inner side 08 or the outer side 08 ) is approximately the smallest cooling air cross section of the first cooling air hole 12 twice as large, with the cross-section decreasing towards the end of the cooling air pocket 13 . The length of the cooling air pocket 13 transversely to the inside (ie in the direction of the first cooling air opening 12 ) is approximately 2.5 times the material thickness of the first edge section 06 in the region of the first cooling air opening 12 .

Returning to FIG. 1 , it is provided in this exemplary embodiment that the heat insulating element 01 is arranged at the downstream end 24 of the heat shield 21 , wherein the first edge sections 06 are each oriented adjacent to each other via a gap. For this purpose, in the example, the second edge section 16 is also arranged downstream of the first cooling air opening 12 at the corner 18 , the first cooling air opening having a cooling air pocket 13 . That is, the insulating element 01 is oriented with the second edge section 16 towards the vane 28 .

Claims (13)

1. A thermal insulating element (01) for a thermal shield (21), said element having: a wall (03), wherein the wall (03) has a hot side (04) that can be loaded with a heat medium and a cold side (05) opposite the hot side (04); and two first edge sections (06) which are opposite one another and extend in the longitudinal direction, the two first edge sections (06) each extending from the hot side (04) over the cold side (05) as far as a web upper side (07), and a plurality of cooling air openings (11, 12) being present in the first edge section (06), which are distributed over the length of the first edge section (06) and extend from the inner side (08) to the outer side (09),

it is characterized in that the preparation method is characterized in that,

A cooling air pocket (13) is arranged on the cold side (05), wherein the cooling air pocket (13) is embedded in the wall portion (03) from the cold side (05) in the direction of the hot side (04) and extends from the inner side (08) in a transverse direction, wherein a first cooling air opening (12) is arranged at least partially in the cooling air pocket (13).

2. Insulating element (01) according to claim 1,

It is characterized in that the preparation method is characterized in that,

The first cooling air opening (12) has a minimum free cooling air cross section,

Wherein the cooling air pocket (13) has at least partially a first cross section parallel to the cooling air cross section, which is at least 0.5 times and maximally 10 times the cooling air cross section; and/or

wherein the cooling air pocket (13) has a second cross section transverse to the cooling air cross section in the region of the first cooling air opening (12), which is at least 2 times and at most 20 times the cooling air cross section.

3. insulating element (01) according to claim 1 or 2,

It is characterized in that the preparation method is characterized in that,

The cooling air pocket (13) has an extension in the transverse direction which is at least 0.05 times and at most 0.2 times the width of the insulating element (01); and/or

The cooling air pocket (13) has a depth from the cold side (05) which is at least 0.2 times and at most 0.5 times the material thickness of the wall portion (03) from the cold side (05) up to the hot side (04).

4. Insulating element (01) according to claim 1 or 2,

it is characterized in that the preparation method is characterized in that,

at least 25% and maximally 75% of the first cooling air opening (12) at the inner side (08) is arranged within the cooling air pocket (13).

5. insulating element (01) according to claim 1 or 2,

It is characterized in that the preparation method is characterized in that,

the first cooling air opening (12) is connected flush with the base of the cooling air bag (13), or the first cooling air opening (12) is at a distance from the base of at most 0.5 times the depth of the cooling air bag (13).

6. Insulating element (01) according to claim 1 or 2,

it is characterized in that the preparation method is characterized in that,

The outer side (09) and the inner side (08) are oriented at an angle of between 75 ° and 105 ° towards the hot side (04); and/or

The material thickness of the first edge section (06) is at least 0.5 times the material thickness of the wall section (03) and at most 2 times the material thickness of the wall section (03).

7. Insulating element (01) according to claim 1 or 2,

It is characterized in that the preparation method is characterized in that,

The heat-insulating element (01) has a second edge section (16) which extends from the hot side (04) up to beyond the cold side (05), said second edge section connecting the respective ends of the first edge section (06), the first cooling air opening (12) being closest to the second edge section (16).

8. Insulating element (01) according to claim 7,

it is characterized in that the preparation method is characterized in that,

The heat insulation element (01) comprises a rib (17) arranged on the cold side (05), which rib (17) connects the two first edge sections (06) and extends at a distance from the second edge section (16), wherein the first cooling air opening (12) is arranged between the second edge section (16) and the rib (17).

9. Insulating element (01) according to claim 8,

It is characterized in that the preparation method is characterized in that,

The remaining cooling air openings (11) are arranged on the side of the rib (17) facing away from the second edge section (16).

10. insulating element (01) according to claim 8 or 9,

it is characterized in that the preparation method is characterized in that,

The second edge section (16) and/or the ribs (17) extend substantially as far as the web upper side (07) and/or have a material thickness that substantially corresponds to the first edge section (06) and/or are oriented at an angle of between 75 ° and 105 ° to the hot side (04).

11. Heat shield (21) having a carrier structure (22) and a plurality of flat heat shield tiles (23) and heat shield elements (01) adjoining one another with gaps, which are each fastened to the carrier structure (22),

It is characterized in that the preparation method is characterized in that,

the insulating element (01) is constructed according to any one of claims 1 to 10.

12. Heat shield (21) according to claim 11,

It is characterized in that the preparation method is characterized in that,

the heat insulation elements (01) are each configured in a circumferential row, wherein first edge sections (06) of the heat insulation elements (01) are each adjacent to one another with a gap, and second edge sections (16) are arranged in the manner of extensions of one another.

13. Heat shield (21) according to claim 12,

It is characterized in that the preparation method is characterized in that,

The circumferential row of insulating elements (01) is arranged at a downstream end (24) of the heat shield (21), wherein the second edge section (16) is directed towards the end (24).