EP1509727A1 - Flame observation flange - Google Patents

Abstract

The invention relates to a flange (1) for the optical flame observation in a gas turbine. Said flange comprises at least one bore for the optical observation in which bore at least one pane (9, 10) is disposed which separates the flame-side chamber in which substantially directly communicates with a combustion chamber in which the at least one flame to be observed is disposed from the exterior from which the at least one flame is observed. The aim of the invention is to provide a simple and long-term reliable means of preventing the at least one pane (9, 10) of said flange (1) from fogging. According to the invention, two panes (9, 10), disposed one behind the after with respect to the optical axis (8), define a sealed-off intermediate space (22) in the bore for the optical observation, and means (24) for dehumidifying the sealed-off intermediate space (22) are provided.

Description

 DESCRIPTION

TITLE

Flange for flame observation

TECHNICAL AREA

The present invention relates to a flange for optical flame observation in a gas turbine. The flange in this case comprises at least one bore for optical observation, in which bore at least one disk is arranged, around the space on the lamb side, which is in essentially direct connection with a combustion chamber in which the at least one flame to be observed is arranged, from the outside , from which the observation of the at least one flame can take place.

STATE OF THE ART

For safety reasons, the flames in the combustion chamber of a gas turbine must be observed and monitored. This happens, among other things, in the case of annular combustion chambers, in which, as it were, a single, rotating one, of a plurality of on the circumference Flame supplied to arranged burners is present, for example, by leading at least one observation tube through the housing of the gas turbine to the outside of the gas turbine. The tube leads through cavities arranged in the housing, which are used, for example, to supply cooling air, additional combustion air or to accommodate fuel supply lines, etc. The tube is usually open to the combustion chamber, i.e. there is usually a pressure in the tube which essentially corresponds to the pressure in the combustion chamber and a temperature which is also in the region of the temperature in the brake chamber, but as a result of the weak convection in the tube with respect to the temperature sets a decreasing gradient towards the outside of the gas turbine.

Observation means in the form of flame monitors with optical detectors are usually arranged on the outside of the gas turbine, which allow automated and continuous observation and control of the flame activity. These observation means are arranged outside the gas turbine, that is essentially at room temperature and normal pressure, on the one hand, in order not to stress these observation means excessively thermally and mechanically, and in order to be able to exchange and maintain them more easily on the other hand. In order to accordingly seal the pipe to the outside, where there is essentially room temperature and normal pressure, without impairing the optical path for observation, at least one suitable, i.e. the optical path of the flame observation is not impaired provided disc which is used either at the end of the observation tube or in a flange placed on the observation tube. As a result of the high temperature differences and pressure differences between the interior of the observation tube and the surroundings of the gas turbine, this disk must meet high mechanical requirements and be well sealed. Usually, the at least one disc is installed in the flange, i.e. z. B. welded into the flange.

PRESENTATION OF THE INVENTION

The present invention is therefore based on the object to provide a flange with at least one recessed disc, which, for. B. the Flames can be observed in the combustion chamber of a gas turbine. It is a flange for optical flame observation, comprising at least one bore for optical observation, in which bore at least one disk is arranged, around the flame-side space, which is in essentially direct connection with a combustion chamber in which the at least one to be observed Flame is arranged to separate from the outside space from which the observation of the at least one flame can take place.

The flange proposed according to the invention is characterized in that two disks are arranged one behind the other in relation to the optical axis, preferably parallel and perpendicular to the optical axis, which delimit a sealed space in the bore, and in that means for dehumidifying the sealed space are. The arrangement of two panes one behind the other has the advantage that a redundant system is created. In other words, the presence of two panes in a row results in increased security, since each pane is advantageously capable of withstanding the entire temperature and pressure difference between the outside environment and the inside of the observation tube. A defect in one of the two disks does not immediately lead to a failure of the gas turbine (which is unavoidable with an open connection between the combustion chamber and the outside environment), since the second disk can immediately take over the full function of the first one. The arrangement of two panes one behind the other is problematic in that moist air, which can be trapped in the space between the two panes, tends to be above a certain level of moisture on the cold pane, i.e. on the pane facing the observation means condense. Fogging of this pane makes it impossible or at least more difficult to observe the flame with the observation means, since this significantly impedes the optical path and thus falsifies the measurement. This problem is solved according to the invention by providing means for dehumidifying the space between the two panes. This can be done, for example, by applying a vacuum. However, applying a vacuum has the disadvantage that the space between the two panes must be sealed extremely well, since otherwise the vacuum cannot be guaranteed in the long term. In addition, the usual pressure and temperature loads when using such a Flange on a gas turbine, the complete tightness of the intermediate space can only be guaranteed with great difficulty, and that, accordingly, a flange with an evacuated intermediate space often has to be replaced, since evacuation on site is hardly possible. The continuous dehumidification of this space by other types of dehumidifiers proves to be easier and more sensible, since in contrast to an evacuation of this area, the maintenance of such dehumidifiers is much easier. In particular, it is usually not necessary to replace the entire flange, but only the dehumidifiers.

According to a first preferred embodiment of the present invention, the means are designed in the form of at least one drying cartridge. The drying cartridge can then be arranged accordingly in the flange in an area which is connected to the space between the two panes, so that dehumidification of this space is ensured. It is also possible to arrange the drying cartridge directly in the intermediate space, provided that this does not interfere with the optical path for observation. Products are particularly suitable as drying cartridges, which can be re-used for dehumidification after simply absorbing moisture by simply heating them. This usually involves, for example, hygroscopic substances stored in a porous aluminum container, which have the property of releasing the absorbed water when an elevated temperature is applied. After the absorption of moisture, such drying cartridges can simply be dried again in an oven by heating, and then used again to dehumidify the intermediate space.

According to a further preferred embodiment of the invention, the dehumidifiers are arranged in the flange such that they can be inserted, exchanged or removed from the outside of the flange facing away from the intermediate space. This arrangement z. B. a dry cartridge in the flange allows replacement of these dehumidifiers without having to remove one of the two discs in series from the flange. The maintenance of the flange is particularly easy and efficient. The preferred procedure is to provide at least one cavity for the dehumidifying means, which is arranged laterally to the intermediate space with respect to the optical axis and which is connected to the intermediate space, this connection in particular via at least one opening between the hollow space and the space is guaranteed. This arrangement allows easy access from the flange side (essentially from the radial side with respect to the optical axis) without the optical path being disturbed by the presence of the dehumidifiers. Accessibility to the dehumidifying means is furthermore preferably ensured in that the flange has at least one hole arranged essentially perpendicular to the optical axis, which is connected to the intermediate space via at least one opening, which hole provides a cavity for receiving the means , and which can be sealed to the outside of the flange via closure means, in particular in the form of a sealing screw. The hole can have any cross-section, but advantageously it is cylindrical (the diameter is preferably reduced shortly before the gap so that the cartridge is held in the large diameter area without falling into the gap), and in its area facing away from the space provided with an internal thread, so that, for. B. a sealing screw (optionally provided with sealing rings) allows easy sealing of this hole after inserting the drying agent.

A further preferred embodiment of the present invention is characterized in that the observation-side disc can be inserted, exchanged or removed from the observation-side end of the flange and / or that the flame-side disc can be inserted, exchanged or removed from the flame-side end of the flange , This simple interchangeability of the panes from the respective side also ensures simple and inexpensive maintenance of the observation flange. In this way, the panes can easily be replaced or cleaned if they break or become dirty. Particularly preferably, the mechanical design of the interchangeability is designed identically from the two sides, so that both the two disks and their fastening means in the flange are identical and therefore there are as few different parts as possible. Grub screws with a central bore are advantageously used as the fastening means of the disks, that is to say at least one of the washers is held in an internal thread arranged in the flange by at least one grub screw with an external thread and with an axial hole from the side facing away from the intermediate space. It also proves to be advantageous to provide second means, one Fixation of the grub screw in relation to its rotation in the internal thread allowed. This is to prevent the vibrations that occur in gas turbines from preventing me from loosening the grub screws during operation, and thus reducing the tightness of the space as a result of loosening the pressure on the disks. The tightness on the side of the panes facing the intermediate space is usually ensured by sealing rings (O-rings). Sealing rings can also be arranged on the side facing the grub screw, possibly in combination with a washer.

A preferred embodiment of the grub screw is characterized in that it has on the side facing away from the disk at least one, substantially parallel to the optical axis and laterally offset to this, in particular in the form of a blind hole, and that the flange on the corresponding Front end has at least one, substantially parallel to it, arranged with respect to the optical axis axially outside of the internal thread, in particular in the form of a blind hole, wherein the grub screw can be fixed via a protruding clip in the two holes. This is a simple and easy to implement version of the second means for fixation. The mounting bracket, which, for. B. can be easily realized by a U-shaped wire, is so easily and to a certain extent automatically fixed on the combustion chamber side by striking the flange on the housing and / or observation tube, or equally by attaching an observation means on the outside.

Another preferred embodiment is characterized in that the flame is observed via a flame monitor with an optical detector, and in particular that the flange on the housing of a gas turbine is attached via a flange plate, the observation of the at least one flame in the combustion chamber of the gas turbine via a Observation tube takes place, which projects through the housing of the gas turbine on the optical axis to the combustion chamber and thus connects the combustion chamber via the interior of the observation tube.

Yet another preferred embodiment of the invention has disks made of quartz glass with a thickness in the range from 0.5 to 2 cm, in particular in the range of 1 cm, the disks having a diameter in the range from 1.5 to 4 cm, in particular in the range of 3 cm. The two disks are advantageously around Range of 2 to 10 cm, in particular in the range of 3 to 5 cm from each other along the optical axis, and seals are provided in the direction of the space and / or to the fastening means facing away from the space, in particular in the form of Teflon or graphite gaskets.

Further preferred embodiments of the present invention result from the dependent claims.

BRIEF EXPLANATION OF THE FIGURES

The invention will be explained in more detail below on the basis of exemplary embodiments in connection with the drawing. It shows:

Figure 1: an axial section through a flange for flame observation.

WAYS OF CARRYING OUT THE INVENTION

Figure 1 shows an observation flange, which is to serve as an embodiment of the present invention. The flange 1 has a flange plate 2, via which the observation flange can be attached to a housing 4 of a gas turbine. For this purpose, the flange plate 2 is provided with holes through which corresponding fastening screws 3 can be guided and screwed to the housing 4. The flange 1 has a body which is cylindrical in this case, the body tapering in a region between the part facing away from the housing 4 and the flange plate 2 so that the screws 3 can be inserted and fastened without problems. On the side of the flange 1 facing away from the housing 4, a flame monitor 6 is arranged, which has an optical detector 7. This optical detector 7 is electronically connected directly to the control of the gas turbine and is used for the continuous monitoring of the flame in the combustion chamber.

The flange 1 has a bore in its central region along the optical axis 8, which is used to observe the flame. In this case, this bore is cylindrical. The bore can also have a rectangular or polygonal cross section. The bore is filled in steps from both sides of the flange, so that the two disks 9 and 10 are pushed in from both sides until they come to a stop can. A sealing ring 11 is arranged between the stop and the disks 9 and 10, which seals the gap 22 arranged between the disks when the disks 9 and 10 are pressed against the stop. At the end of the flange, the bore widens further on both sides to the disks 9 and 10, an internal thread 15 being provided in the outermost region. A set screw 13 or 14 with a central hole (so that the optical axis is not blocked) is screwed into this outer area of the bore, with which the respective disk 9 or 10 is pressed against the abovementioned stop. Between the set screw 13 or 14 and the washer 9 or 10, a further seal 11 is initially arranged, and between this seal 11 and the set screw 13 or 14 preferably an additional washer 12, which, among other things, is to prevent the sealing ring 11 from being damaged when the set screw is screwed in , The grub screw 13 or 14 is cylindrical in its area 19 facing the disk, while in the outer area 20 the inner cross section of the grub screw 13 or 14 is polygonal or similar, so that this nut can be inserted from the outside with a corresponding tool (e.g. . Allen key) can be easily screwed into flange 1. The grub screw 13 or 14 also has one or more blind holes 17, and the flange 1 has corresponding blind holes 16 on its end faces. The blind holes 16 and 17 are provided to receive a mounting bracket 18 so that the nut can no longer be rotated relative to the flange 1 after the mounting bracket 18 has been inserted. Usually, a blind hole 16 is sufficient because it through the plurality of holes 17 in the grub screws 13 and. 14 always gives a favorable distance for inserting the wire 18 without disturbing the optical axis. This fixation prevents the grub screw 13 or 14 from being loosened in the thread 15 in the case of the vibrations customary in gas turbines during operation, and accordingly the sealing of the disks 9 or 10 is no longer guaranteed in the long term.

This special mechanical implementation of the fastening of the disks 9 and 10 in the flange now enables, in contrast to the welding which is customary in the prior art, easy replacement or cleaning of the disks, since the disks are removed from the flange and cleaned or cleaned by slightly loosening the grub screws can be replaced. Especially in combination with the fixation mechanism The grub screw, which makes this flange particularly suitable for use on gas turbines, has this new realization.

The flange 1 now has an additional bore running essentially perpendicular to the axis 8, which tapers step-like shortly before the intermediate space 22 to form a connecting opening 23. Through the opening 23, the cavity 21 formed in the bore is connected to the intermediate space 22. From the transversal outside of the flange, a drying cartridge 24 can now be inserted into this bore, and then a sealing screw 25 can be tightened in a thread 26 provided in the bore, the screw 25 sealing the cavity 21 to the outside in a graduated manner with sealing rings ,

The opening 23 has a diameter of 10 mm, the space 21 corresponds to a ³ / "thread.

The drying cartridge 24 is thus in operative connection with the intermediate space 22 and can thus dehumidify this intermediate space 22. On the other hand, this drying cartridge 24 can also be replaced or replaced very easily, since it is easily accessible from the outside of the flange by simply screwing on the sealing screw 25 (possibly even when the gas turbine is in operation). Suitable drying cartridges 24 are, for example, products of type A3 from Süd Chemie AG, Cologne, DE. Such cartridges are made of aluminum sheet, have a filling of approx. 3 g molecular sieves and can be regenerated. Moisture absorption takes place through a fleece disc through a hole in the underside. They have a diameter of 23mm and a height of 11mm. The molecular sieves (M-sieves) are synthetically produced zeolites. The water absorption is approx. 18 percent by weight regardless of the relative humidity. The regeneration temperature is between 250 and 300 degrees Celsius (the moisture stored in the desiccant is released again at these temperatures). At lower temperatures, silica gel or blue gel would also be conceivable as a drying agent. In other words, cartridges of this type have the advantage that they can be regenerated simply by heating them out, and thus do not have to be replaced as a whole. If necessary, the cartridges additionally have a moisture indicator which can be inserted into the housing and which enables the status of the cartridge to be checked or monitored. This design of the flange 1 proves to be suitable for connection to observation tubes 5. These observation tubes 5 have a diameter which is usually at least as large as the bore in the area of the intermediate space 22, ie, for example 3 cm. Such an observation tube is in direct connection with the combustion chamber (the observation is usually about 1 meter from the flame) and serves as a channel through the casing 4 of the gas turbine. In the tube there are essentially the same pressure conditions as in the combustion chamber, ie usually pressures in the range of z. B. about 30 bar. Corresponding to a pressure in the outside area of 1 bar, there is a pressure difference of 29 bar on the panes. There are also temperatures that are comparable to temperatures in the combustion chamber. Accordingly, the flange 1 is usually at a total temperature of over 100 degrees Celsius during operation of the gas turbine. As a result, the seals 11 should be made of graphite or Teflon or similar heat-resistant materials, and the disks 9 and 10 are usually made of quartz glass with a thickness of approximately 1 cm. The disks are spaced about 3 cm apart and have an outside diameter of about 3 cm. The diameter of the bore in the area of the intermediate space 22 is 2 cm. In order to also ensure redundancy and completeness with regard to the observation, three such observation tubes are typically distributed around the circumference of the gas turbine.

LIST OF REFERENCE NUMBERS

1 observation flange

2 flange plate

3 fastening screw

4 casing of the gas turbine

5 observation tube

6 flame monitors

7 optical detector

8 optical axis / axis of rotation of the flange

9 first disc

10 second disc

11 sealing ring

12 washer

13 first grub screw with central bore

14 second grub screw with central bore

15 threads of 13 or 14

16 hole in the flange

17 Hole in grub screw

18 mounting bracket

19 cylindrical part of 13 or 14

20 Allen part of 13 and 14 respectively

21 cavity for dry cartridge

22 space between the two disks 9 and 10

23 connection opening between 21 and 22

24 drying cartridge Sealing scraper for dry cartridge

Thread of 25

Claims

1. flange (1) for optical flame observation in a gas turbine, comprising at least one bore for optical observation, in which bore at least one disk (9, 10) is arranged, around the flame-side space, which is in essentially direct connection with a combustion chamber, in which the at least one flame to be observed is arranged is to be separated from the outside space from which the observation of the at least one flame can take place, characterized in that with respect to the optical axis (8) and preferably essentially perpendicular to it, two disks (9, 10) are arranged one behind the other, which delimit a sealed gap (22) in the bore, and that means (24) for dehumidifying the sealed Intermediate space (22) are arranged. 2. Flange (1) according to claim 1, characterized in that the means (24) are designed in the form of at least one drying cartridge (24), which can particularly preferably be re-used for dehumidification after simply absorbing moisture by simple heating. 3. flange (1) according to one of the preceding claims, characterized in that the means (24) are arranged in the flange (1) in such a way that they are inserted and replaced from the outside of the flange (1) facing away from the intermediate space (22), or can be removed. 4. Flange (1) according to claim 3, characterized in that at least one, with respect to the optical axis (8) laterally to the intermediate space (22) arranged cavity (21) for the means (24) for dehumidification is provided, which with the intermediate space (22) is connected, this connection in particular via at least one opening (23) between the cavity (21) and the intermediate space (22) is ensured. 5. flange (1) according to claim 4, characterized in that the flange (1) has at least one substantially perpendicular to the optical axis (8) arranged hole, which via at least one opening (23) with the intermediate space (22) in connection stands, which has a cavity (21) for receiving the means (24), and which can be sealed to the outside of the flange (1) via closure means, in particular in the form of a sealing screw (25). 6. flange (1) according to any one of the preceding claims, characterized in that the observation-side disc (10) from the observation-side end of the flange (1) can be inserted, replaced or removed, and / or that the flame-side disc (9) from end of the flange (1) on the flame side can be inserted, exchanged or removed. 7. flange (1) according to claim 6, characterized in that at least one of the washers (9, 10) via at least one grub screw (13, 14) with external thread (15) and axial hole from the side facing away from the intermediate space (22) an internal thread (15) arranged in the flange (1) is held, with second means (16, 17, 18) being particularly preferred, which allow the grub screw (13, 14) to be fixed in relation to its rotation in the internal thread (15) , Flange (1) according to claim 7, characterized in that the grub screw (13, 14) on the side facing away from the disc (9, 10) has at least one bore (17) arranged essentially parallel to the optical axis (8) and laterally offset from it ), in particular in the form of a blind hole, and in that the flange (1) on the corresponding end face has a bore (16), in particular in the form of a bore (16) which runs essentially parallel to it and is axially outside the internal thread (15) with respect to the optical axis a blind hole, wherein the fixation the grub screw (13, 14) can take place via a fastening clip (18) projecting into the two bores (16, 17). 9. flange (1) according to any one of the preceding claims, characterized in that the flame is observed via a flame monitor (6) with an optical detector (7), and in particular that the flange (1) on the housing of a gas turbine (4) a flange plate (2) is attached, the at least one flame in the combustion chamber of the gas turbine being observed via an observation tube (5) which projects through the housing of the gas turbine (4) on the optical axis (8) to the combustion chamber and thus the Combines the combustion chamber over the interior of the observation tube (5). 10. flange (1) according to any one of the preceding claims, characterized in that the disks (9, 10) made of quartz glass have a thickness in the range of 0.5 to 2 cm, in particular in the range of 1 cm, that they have a diameter of in the range of 1.5 to 4 cm, in particular in the range of 3 cm, that the two disks (9, 10) are in the range of 2 to 10 cm, in particular in the range of 3 to 5 cm from one another along the optical axis ( 8) are spaced, and that the disks (9, 10) in the direction of the intermediate space (22) and / or to the fastening means (13, 14) facing away from the intermediate space (22) with seals (11), in particular in the form of Teflon or graphite seals are sealed.