JP2005538310A - gas turbine - Google Patents

Abstract

In order to generate a working medium (M), the gas turbine (1) having a combustor (4) that is combusted by reacting supplied fuel and combustion air is made to have a particularly simple structure with very high equipment efficiency. . For this purpose, according to the invention, the combustor (4) is made coolable and formed as a tube structure, and its combustor wall (23) is formed by a coolant tube (24). If the coolant tube is made of a cast material, the strength of the combustor wall can be improved, and the thermal insulation can be improved by covering with a ceramic protective layer.

Description

  The present invention relates to a gas turbine provided with a combustor in which fuel supplied to generate a working medium reacts with supplied combustion air and burns.

  Gas turbines are employed in many fields to drive generators or work machines. At that time, the energy contained in the fuel is used to generate the rotational motion of the turbine shaft. For this purpose, the fuel is burned by a large number of burners, and at that time, air compressed by an air compressor is introduced. A high-temperature and high-pressure working medium is generated by the combustion of fuel. The working medium is guided to a turbine device that is connected downstream of each burner, where it expands while working. A separate combustor is attached to each burner, and the working medium flowing out of the combustors merges before or in the turbine unit. Alternatively, the gas turbine is formed in a so-called annular combustor structure, with a large number of burners, in particular all the burners, opening into one common combustor, which is generally annular.

  When designing this kind of gas turbine, in addition to the power that can be obtained, a particularly high efficiency is usually a design goal. Increased efficiency can be achieved by increasing the inlet temperature as the working medium exits the combustor and enters the turbine system for thermodynamic reasons. Accordingly, an inlet temperature of about 1200-1500 ° C. is sought and achieved for the gas turbine.

  However, when the working medium is so hot, the components and components exposed to the medium are subject to significant thermal loads. Nevertheless, it is usually necessary to cool the components, especially the combustor, in order to guarantee a very long life of the components with great reliability. In general, it is necessary to cool the components as uniformly as possible to prevent the generation of thermal stresses in the materials that limit the lifetime of the components. Usually, cooling air is employed as the coolant. The air is directed to cool it along the outer surface of the inner wall of the combustor through a cooling system, usually composed of tubes and partition walls.

  However, such a cooling system has the disadvantage that the combustor and the cooling system are very expensive. In particular, a separate cooling system must be attached to the outer surface of the original combustor wall and the cooling system must be fixed from the outside. Therefore, since many parts and joining operations are required for manufacturing the combustor, a long working time and a high cost are required. This further increases the incidence of defects during manufacture and operation of the gas turbine. Furthermore, maintenance work is difficult due to the complicated combustor wall structure.

  An object of the present invention is to provide a gas turbine having a simple structure and particularly high efficiency.

  This problem is solved in accordance with the present invention by forming the walls of the combustor with coolant tubes.

  The invention starts from the idea that in order to guarantee a particularly high efficiency, the gas turbine must be configured to be particularly suitable for high medium temperatures. In so doing, particularly reliable cooling of the thermally loaded components, in particular the combustor, must be ensured in order to keep the occurrence of defects low. This can be achieved at a very low cost by configuring the combustor wall on the one hand to be coolable on its own and on the other hand to a very simple and flexible holding. Both the above-mentioned viewpoints in the case of forming a combustor are particularly easily protected by configuring the surrounding wall of the combustor or the combustor wall with an appropriate tube. In particular, cooling air is used as the coolant, and this air is introduced into the combustor as combustion air additionally preheated by the combustor wall cooling after flowing through the coolant tube.

  In order to guarantee a particularly high strength of the combustor wall, the coolant tube is preferably made of a cast material, in other words a cast product. Another advantage of this material selection is that reliable insulation is particularly easily possible by suitably coating the casting material with a ceramic protective layer.

  In order to make the coolant tube particularly insensitive to thermal stresses, and thus to make the coolant tube particularly robust, in an advantageous embodiment it is formed in a trapezoidal cross section. This trapezoidal cross section has a particularly large thermal elasticity, so that even if the individual tube members of the tube are subjected to significantly different heating, only a small thermal stress is produced between the cold and hot portions of the tube. This provides a long life of the coolant tube.

  In order to form the combustor wall and thus the original combustor, the coolant tube may be secured with a support ring extending in the circumferential direction of the combustor. Depending on its position and shape, the support ring defines the shape of the annular chamber produced by the combustor coolant tube. In this case, a mechanically stable combustor structure can be manufactured in the form of a self-supporting structure by using only a few other components in addition to the original tube.

  Fixing of the coolant pipe to the support ring may be performed via a cooling bolt. The fixing of the coolant tubes by bolts makes it possible to assemble or disassemble individual or multiple coolant tubes in a particularly short time from the combustion gas side, i.e. without having to disassemble the combustor.

  In order to guarantee a particularly high strength of the combustor, a support ring may be connected to one another with a number of longitudinal ribs in addition to the original coolant tube. The longitudinal ribs together with a support ring fixed perpendicular thereto form a support frame with great rigidity and strength. Due to the particularly great stability of this support cradle, the support ring and the longitudinal rib are preferably welded together, so that the ring and the rib form a welded support.

  It is desirable to form the coolant tube from two or more tube members that are joined together in the longitudinal direction, especially when the combustor is formed taking into account the working fluid flow in the combustor. It is done. At the same time, a sufficient length and shape of the coolant tube can be guaranteed. The advantage of the split tube is that it avoids manufacturing problems, especially when manufacturing coolant tubes of sufficient length and desired shape from castings.

  In order to couple two continuous pipe members of the coolant pipe to each other, it is preferable to provide a corresponding transition part or connection part at each pipe end of each pipe member. In particular, the shape of the transition part may be designed to accommodate simple interconnections. In another advantageous embodiment of the invention, the transition part, in particular the pipe member, is configured to be joined by a bayonet joint. If the cross-section of the coolant tube is trapezoidal, the cross-sectional shape of the transition is selected so that it changes to a circular cross-section before the transition reaches the joint or each tube member. This circular end of the cross-section allows a simple task to make a snug connection with the following tube member.

  In order to ensure effective cooling of the coolant tube that forms the combustor wall, the coolant tube may be impact cooled at the inflow of coolant. Therefore, a hole into which the coolant flows is provided on the outer surface of the coolant tube. As a result, the coolant impinges on the inner surface of the tube, and intimate contact with the tube material in this range ensures a particularly effective cooling action. In the subsequent range, the coolant flows longitudinally through the tube and cools the tube by contact with the tube.

  This cooling system has the advantage, on the one hand, that the cooling system is integrated into the combustor wall structure and thus requires few additional parts for the construction of the cooling system. On the other hand, only a slight coolant pressure loss occurs with the relatively linear discharge of coolant. This has the advantage of helping improve turbine efficiency on the coolant side as well.

  For a particularly large overall efficiency of the gas turbine, the heat input to the coolant may be recovered during the natural energy conversion process in the gas turbine. Therefore, considering the supply of cooling air that is heated when the combustor is cooled and used as a coolant to the combustor, the preheated cooling air is used exclusively or as additional combustion air.

  In this sense, in order to supply the effluent coolant to the combustion process in the combustor, the outlet side of each coolant tube may be connected to the collecting chamber, and the air side of the collecting chamber may be pre-connected to the combustor. In this collecting chamber, the coolant is mixed with the other air mass flow from the compressor by means of a throttle device and fed into the combustion process.

  The uniform flow state can be achieved by attaching the above collection chamber to each burner and allowing the same amount of cooling air or coolant to flow into each collection chamber by design. Therefore, it is preferable to connect a collecting chamber to each burner and connect each collecting chamber to the same number of coolant pipes. This arrangement has the special advantage that each burner can be supplied with approximately the same amount of returning cooling air. When the combustor is formed as an annular combustor, particularly uniform combustion occurs in the combustor.

  A particular advantage according to the invention is that the combustor wall is formed as a number of interconnected coolant tubes which are used for the flow of coolant, in particular cooling air, with a simple structure and particularly reliable combustor cooling. Is to be possible. In particular, by integrating the coolant tube into the form of a self-supporting combustor structure with a support ring, the individual tubes that need to be inspected can be replaced very easily, and the flexibility afforded by the tube structure is nonetheless. Therefore, it is possible to easily replace the existing combustor structure of the existing gas turbine. Also, the structure of the combustor consisting of tubes is very stable and resistant to vibration of the combustor wall, since the coolant tube supports and strengthens the annular chamber. The basic flexibility in the formation and component selection achieved by the structure of the combustor wall consisting of tube elements also includes the installation of sensors that monitor and / or diagnose the actual combustion process in the combustor, i.e. monitoring sensors. In particular, for example, by the use of a specially modified tube which allows a suitable sensor to penetrate from the outer chamber into the combustor chamber.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same parts are denoted by the same reference numerals.

  A gas turbine 1 of FIG. 1 includes a compressor 2 for combustion air, a combustor 4, and a turbine 6 that drives a compressor 2 and a generator or work machine (not shown). For this purpose, the turbine 6 and the compressor 2 are arranged on a common turbine shaft 8 which is also called a turbine rotor. The turbine shaft 8 is supported so as to be rotatable about a rotation center line 9 and is coupled to a generator and a work machine.

  The combustor 4 formed in the form of an annular combustor is equipped with a number of burners 10 for burning liquid fuel or gaseous fuel, and further has a heat insulating element on its inner wall.

  The turbine 6 includes a large number of blades 12 attached to a turbine shaft 8. These blades 12 are arranged in a ring shape on the turbine shaft 8 to form a large number of blade rows. The turbine 6 has a large number of stationary blades 14. These stationary blades 14 are similarly arranged in a ring shape to form a stationary blade row, and are fixed to an internal casing 16 of the turbine 6. The moving blade 12 is used to drive the turbine shaft 8 by the impact transmission of the working medium M flowing through the turbine 6. On the other hand, the stationary blade 14 is used to guide the flow of the working medium M between two moving blade rows or moving blade wheels that are continuous in the flow direction of the working medium M. The pair of stationary blade rings or blade rows 14 and the moving blade wheels or blade rows 12 that are continuously located with each other are also referred to as turbine stages.

  Each stationary blade 14 has a blade pedestal 18, also called a blade leg, and the pedestal 18 is arranged as a wall element that fixes the stationary blade 14 to the internal casing 16 of the turbine 6. The wing pedestal 18 forms an outer boundary portion of the combustion gas passage for the working medium M flowing through the turbine 6, and is a component that is thermally subjected to a very large load. Similarly, each rotor blade 12 is fixed to the turbine shaft 8 via a blade base 20 called a blade leg.

  Guide wheels 21 are arranged between the blade bases 18 of the two stationary blade rows adjacent to each other and spaced apart from each other, and are fixed to the inner casing 16 of the turbine 6. Similarly, the inner side surface of each guide wheel 21 is also exposed to a high-temperature working medium M flowing through the turbine 6, and is spaced from the outer end 22 of the moving blade 12 facing this by a gap in the radial direction. The guide wheels 21 arranged between adjacent stationary blade rows serve as a covering element that protects the internal casing 16 or other casing-incorporated parts, in particular, from thermal overloads caused by the hot working medium M flowing through the turbine 6. .

  In order to obtain a relatively high efficiency, the gas turbine 1 is designed for a very high inlet temperature of about 1200 to 1500 ° C. of the working medium M leaving the combustor 4. In that case, in order to guarantee the long life of the gas turbine 1, that is, the operation period, particularly the main components such as the combustor 4 are formed to be coolable. In order to ensure a reliable and sufficient supply of cooling air as coolant K to the combustor wall 23 of the combustor 4, the combustor wall 23 is formed as a tube structure and the combustor wall 23 is formed with each other to form the combustor wall 23. It consists of a number of coolant tubes 24 that are hermetically coupled.

  In this embodiment, the combustor 4 is formed as a so-called annular combustor, and a large number of burners 10 arranged in a circumferential direction around the turbine shaft 8 are open to a common combustor chamber. As a result, the combustor 4 constitutes an annular structure placed around the turbine shaft 8 as a whole. In order to further clarify the structure of the combustor wall 23, a part of the combustor 4 is shown in a longitudinal sectional view in FIG. The combustor portion is continuous in an annular plane around the turbine shaft 8 to form the combustor 4.

  As can be seen from FIG. 2, the combustor 4 has a starting portion, that is, an inflow portion, in which the exit end side of the corresponding burner 10 is opened. The opening cross-sectional area of the combustor 4 is narrowed in the flow direction of the working medium M in consideration of the flow distribution of the working medium M in the spatial range. The combustor 4 has a curved portion in the longitudinal section on the outlet side. By this curved portion, the outflow of the working medium M from the combustor 4 is promoted based on particularly large shock transmission and energy transmission to the first moving blade row in the flow direction.

  As can be seen from FIG. 2, the combustor wall 23 is formed by a coolant pipe 24 at the radially outer portion and the inner portion of the combustor 4. The longitudinal axes of the coolant pipes 24 are substantially parallel to the flow direction of the working medium M in the inner chamber of the combustor 4. The coolant tube 24 is made of a cast material that is appropriately selected taking into account the particularly large mechanical and thermal strength of the coolant tube.

  In order to allow the combustor 4 formed by the coolant tubes 24 to be shaped in a particularly flexible manner adapted to the desired flow state of the working medium M, each coolant tube 24 is a plurality of continuous ones in this embodiment. The tube member 26 is formed by an appropriate combination. The shape and number of the tube members 26 are selected on the one hand to ensure the particularly high mechanical strength of each individual tube member 26 with respect to the length and shape of each tube member 26 and the casting material used. . On the other hand, in any case, the shape is appropriately selected in consideration of the desired flow path for the working medium M. A relatively large local curvature, which is preferably possible in this case, is obtained in a particularly simple and reliable manner by the split structure of the coolant tube 24.

  Further, the coolant pipe 24 is designed to cope with a thermal stress caused by a special strength and a thermal load in consideration of a locally changing thermal load. Therefore, the coolant pipe 24 and in particular the pipe member 26 that forms the coolant pipe 24 are formed in a substantially trapezoidal cross-sectional shape as shown in FIG. The coolant tube 24 has a relatively long inner surface 28 and a relatively short outer surface 30 in cross section to form a structure of the combustor 4 curved in an annular surface. In order to seal the gap between the adjacent coolant tubes 24, a suitable packing, for example, brush seal packing 32, is used. As a result, the gas chamber is hermetically sealed with the appropriate combination of the coolant tubes 24. Will occur.

  By making the tube trapezoidal in cross-section, the flat shape of the structure obtained by joining the adjacent coolant tubes 24 is particularly promoted, and as a result, the sealed shape of the combustor 4 can be obtained very easily.

  In the divided structure of the coolant pipes 24, particularly simplified joints of two pipe members 26 that are continuous with each other on the coolant side of each coolant pipe 24 are considered, particularly in consideration of assembly and inspection. Therefore, the pipe members 26 that are continuous with each other in the coolant pipe 24 are connected to each other through the corresponding transition portions 34. In order to facilitate the assembly of the tube members 26 that are continuous with each other, the terminal portions of the tube members 26 have a substantially circular cross section as shown in FIG. Since the coolant pipe 24 is made of a casting material, the shape of the transition portion 34 to the pipe member 26 can be very easily adjusted. In the transition range, a continuous transition of the trapezoidal cross section of the tube member 26 to a circular cross section is performed on the terminal side. As can be seen from FIG. 2, the transition 34 is displaced toward its outer side of the combustor 4 with respect to its centerline and the central part of the tube member 26, so that a suitable seal in the inner wall of the combustor 4 is obtained. A substantially flat surface is produced over the entire area using a steel plate or a seal plate.

  In order to form the combustor 4 as a self-supporting monolithic structure, the coolant tube 24 is secured to a plurality of common support rings 36. The support ring 36 surrounds the combustor 4 formed by the original coolant tube 24 with a mutual distance selected appropriately in the longitudinal direction, that is, in the flow direction of the working medium M. As shown in the embodiment of FIG. 3 c, the coolant tube 24 or the tube member 26 forming the coolant tube 24 is fixed to the support ring 36 using a coolable bolt 38. In order to further strengthen and mechanically fix the self-supporting structure forming the combustor 4, the support rings 36 are connected to each other by longitudinal ribs extending in a substantially longitudinal direction, that is, in the flow direction of the working medium M.

  By forming the combustor 4 as a pipe structure, a relatively large amount of cooling air can be supplied to the combustor wall 23 as the coolant K with very little pressure loss. Cooling flowing out of the coolant tube 24 so that the heat generated during the cooling of the combustor wall 23 of the coolant K flowing through the coolant tube 24 can be utilized in the original combustion process, advantageously for thermodynamic efficiency. The material K is used for supplying the combustor 4 as dedicated or additional combustion air. Therefore, the inlet of the coolant K to the coolant pipe 24 is provided at the outlet side end of the combustor 4. The coolant K flows into the coolant tube 24 through a suitable inlet opening 42 as shown in FIG. The inlet opening 42 is placed so that the cooling of each pipe member 26 first occurs at the outlet of the combustor 4 by the cooling air flowing in as the coolant K with respect to the spatial orientation. Subsequently, turning of the coolant K occurs inside each pipe member 26, and the coolant K flows through each coolant pipe 24 in the longitudinal direction, and at that time, the coolant K cools by contacting the pipe wall. Is done.

  Accordingly, the coolant K is in the form of a counter flow with the original working medium M, and the interior of the coolant tube 24 is directed from the outlet portion of the combustor 4 toward the inlet portion of the combustor 4 where each burner 10 is also disposed. Flowing. The coolant K heated or preheated by the continuous cooling of each coolant tube 24 flows out of the coolant tube 24 at the inlet of the combustor 4 and flows into a collecting chamber 46 that is connected downstream of the coolant tube 24. Through the collecting chamber 46, the outlet side of the coolant pipe 24 is connected to the corresponding burner 10, and as a result, the coolant K flowing out of the coolant pipe 24 is used in each burner 10 as combustion air. Depending on the design of the gas turbine, the supply of combustion air to each burner 10 is carried out exclusively by the coolant K flowing out of the coolant tube 24 or optionally with other combustion air introduced from the outside.

  When the combustor 4 is formed as an annular combustor, it is usually advantageous to arrange the burners 10 as symmetrically as possible so that the flow conditions inside the combustor 4 are as symmetric as possible. This principle is also considered on the coolant side in the gas turbine 1, and in particular, the same number of coolant tubes 24 are attached to each burner 10 on the combustion air side.

The half section view of a gas turbine. The partial longitudinal cross-sectional view in the combustor of the gas turbine in FIG. The partial cross-sectional view of the combustor wall in FIG.

Explanation of symbols

1 Gas Turbine, 4 Combustor, 23 Combustor Wall, 24 Coolant Tube, 26 Tube Member, 34 Transition, 36 Support Ring, 38 Volt

Claims (10)

  A gas turbine, characterized in that the combustor (4) comprises a combustor wall (23) formed by a coolant tube (24).   The gas turbine according to claim 1, wherein the coolant pipe is made of a casting material.   The gas turbine according to claim 1 or 2, characterized in that the coolant pipe (24) is trapezoidal in cross section.   Gas turbine according to one of the preceding claims, characterized in that the coolant pipe (24) is fixed to a number of common support rings (36).   A gas turbine according to claim 4, characterized in that the coolant pipe (24) is fixed to the common support ring (36) via a coolable bolt (38).   6. A gas turbine according to claim 4 or 5, characterized in that the support ring (36) is connected in the form of a support frame by a number of longitudinal ribs.   The gas turbine according to one of claims 1 to 6, wherein each coolant pipe (24) comprises a plurality of pipe members (26).   8. A gas turbine according to claim 7, wherein successive pipe members (26) of the coolant pipe (24) are connected to each other via corresponding transitions (34).   The outlet side of each coolant pipe (24) is connected to the collecting chamber (46), and the flowing out coolant (K) is introduced into one of the burners (10) through the collecting chamber (46). A gas turbine according to one of claims 1 to 8. 10. A gas turbine according to claim 9, wherein each burner (10) is provided with a collecting chamber (46), and each collecting chamber (46) is connected to the same number of coolant pipes (24).

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