CN1497129A - Turbine transmission and method of cooling a turbine transmission - Google Patents

Abstract

The invention discloses a turbine transmission mechanism with a turbine shaft and a method for cooling the turbine transmission mechanism. On the turbine shaft of such a turbine gear there are a plurality of disks arranged next to each other, on which the moving blades can be fastened radially, wherein the moving blades can be passed by at least one type of flow. Cooling medium in the internal cooling medium channel for cooling. In order to improve the efficiency of the turbine transmission mechanism at a reasonable and economical cost, and at the same time reduce the risk of operation, that is, to improve the life of the components and the reliability of the turbine transmission mechanism, through a simple and reliable, between adjacent wheels The cooling medium delivery system divided into multiple layers in the radial direction supplies the cooling medium to the moving blades.

Description

Turbine transmission and method of cooling a turbine transmission

technical field

The invention relates to a turbine gear with a turbine shaft, which has a plurality of adjacently arranged disks, on which respectively movable blades can be fastened radially, wherein the movable blades The blade can be cooled by at least one cooling medium flowing through the internal cooling medium channel of the moving blade.

The invention also relates to a method for cooling such a turbine drive.

Background technique

Turbine drives are installed in many fields, mainly as transmissions in the aviation industry and for energy generation. In the case of energy generation, a distinction is made between gas turbines and steam turbines, which are used to drive electrical generators and are often used together as so-called gas-steam turbines. In the gas turbine considered below, the fuel-air mixture is introduced into the combustion chamber, and the working medium formed in the combustion chamber flows out of the combustion chamber, flows through the moving blades in the direction of the moving blades, and expands to perform work. The energy of the working medium is converted into kinetic energy by means of moving blades, and then the kinetic energy is transmitted to the generator through the rotation of the turbine shaft.

Typically the fuel-air mixture burns without radiation at temperatures between 1200°C and 1300°C, whereby high efficiencies can be achieved. Efficiency can usually be further increased by further increasing the combustion temperature.

In the case of high combustion temperatures of the working medium, the highest demands are placed on the thermal stability, mechanical strength and service life of the components of the turbo drive that come into contact with the working medium. Therefore, the highest possible efficiency should be achieved taking into account the operating risks and economics of each component.

For the moving blades of the turbine transmission mechanism, thermal stability, long service life and high reliability are also required. In order that the rotor blades of the first rotor blade group viewed from the flow direction of the working medium can withstand the greatest thermal load, the rotor blades are cooled in a known manner. For this purpose, the rotor blades are usually passed through cavities which become bypass channel systems for the flow of the cooling medium. Compressed air or steam or both are used as cooling medium. Of course, the cooling performance of steam is better than that of compressed air. However, steam places high demands on the tightness of the entire cooling system, which means high manufacturing costs for the conduction of the cooling medium.

As is known, the rotor blades are cooled by air and/or steam. Air cooling can be implemented as open or closed cooling, while vapor cooling is only available in closed cooling systems. When cooling the moving blades of a turbine drive, it is technically expensive to maintain a large pressure difference between the working medium and the cooling medium. In order to isolate the areas from one another, a complex sealing system is required over the entire coolant supply path in order to minimize leakage losses and thus ensure effective cooling. Disadvantages are the high economic and technical costs required for this and, moreover, reduced operational safety and reliability due to technical complexity.

Due to the single-component construction, it is very difficult to feed the cooling medium to the individual rotor blades of the different rotor blade groups, and it is also very expensive to ensure the required system tightness and operational reliability.

Contents of the invention

The technical problem to be solved by the present invention is to improve the efficiency of the turbine transmission mechanism on the premise of reasonable economic cost, and at the same time reduce the operation risk, that is, to improve the service life of the components and the reliability of the turbine transmission mechanism.

According to the present invention, the technical solution for solving the above-mentioned problem is: in the turbine transmission mechanism mentioned at the beginning of this specification, a plurality of rings (umgreifen ) cavities of the turbine shaft, and the cooling media have different pressures in these cavities, wherein one or more cooling media can flow into these cavities and can flow out of these cavities respectively.

The starting point of the invention here is that the simplification of the supply of the cooling medium to the rotor blades reduces the operational risks. As a result, the number of seals can be advantageously reduced while reducing the remaining sealing length, which increases operational safety, reduces failure rates, and reduces leakage losses of the cooling medium. In addition, simple sealing systems can be used which also reduce operational hazards. In this case, a variety of cooling media with different properties can be made to flow in the cavities between two adjacent discs, such as "fresh" fresh air and/or fresh steam directed to the moving blades. Cooling medium, and/or "used" cooling medium such as used air and/or used steam expelled from the moving blades. This simple and reliable provision of the cooling medium allows efficient use of the cooling medium and contributes to increased efficiency, since the components exposed to the working medium can withstand higher temperatures.

Particularly preferably, the arrangement according to the invention is such that radially adjacent cavities are sealed from one another by centrifugal seals. This very reliable sealing of radially adjacent areas reduces leakage losses of the cooling medium.

It is advantageous if all integrated cooling channels in one of the moving blades provided on the same disk communicate through a radial bore or passage with the same cavity enclosed by the disk and an adjacent disk To obtain a completely sealed reliable connection.

Preferably, at least one of the cavities communicates with a coolant supply port or a coolant discharge port.

According to the method according to the invention for cooling an above-mentioned turbine gear, the pressure of the cooling medium flowing through one cavity is higher than the pressure of the cooling medium flowing through the radially outwardly adjacent cavity. Therefore, in the unfavorable case of failure of the essentially very strong centrifugal seal, leakage losses occur only from one pressure stage to the next lower pressure stage, that is to say only from a cavity to the radial direction immediately outside the cavity.

In a method for cooling a turbine transmission mechanism of the present invention, fresh steam flows into the radially innermost cavity, and used steam flows into the radially immediately outer cavity. steam, fresh air flowing into said radially outermost cavity. Gas turbines are commonly used in multi-stage steam turbines that require steam with different pressures as the working medium (gas-steam turbine device). A portion of the working medium steam of the high-pressure steam turbine is used to cool the components of the gas turbine. In this application, the part of steam extracted is called live steam, and its pressure is of the order of 40 bar. The returned used steam of approximately 30 bar after cooling the components exposed to the hot gas can be fed as working medium to an intermediate-pressure steam turbine. Thus, the cooling medium vapor can advantageously be used multiple times. The live steam leakage that occurs in the event of a fault occurs partially due to the pressure drop only in the flow direction of the used steam and mixes with the used steam. The used steam is sent to the medium pressure steam turbine, thus reducing the loss caused by leakage. If part of the used steam flows in the direction of pressure reduction due to leakage and mixes with fresh air, this part of the steam can continue to be used for cooling. Partial losses of the cooling medium occur only if there is a leak between the area in which the fresh air flows and the flow channel of the gas turbine working medium.

Thus, the invention describes a radially multilayer system formed of zones with different pressures isolated from each other, where there is a pressure drop radially from the inside to the outside. Seen radially, the innermost cavity between adjacent discs is dominated by the highest pressure produced by live steam, and the radially outwardly adjacent cavity is dominated by used steam The sub-lowest pressure in the outermost cavity in the radial direction is dominated by the lower pressure generated by the fresh air, and the flow channel between the turbine shaft and the rotor is dominated by the The minimum pressure generated by the working medium. The advantages are: while reducing the number of seals, the sealing length between the discs along the circumferential direction is shortened, and the layered arrangement of cooling media with different pressures is adopted for proper further partial utilization of leakage fluid.

Description of drawings

The present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 schematically depicts a partial view of a gas turbine with a turbine shaft, not to scale.

Detailed ways

FIG. 1 shows a section through a gas turbine 17 along the axis of rotation 2 of the turbine shaft 1 . Discs 3 , 4 and 5 are arranged adjacent to one another on the turbine shaft 1 . The moving blades 14 constituting the moving blade set 16 in the first, second and third turbine stages are respectively fixed on these disks 3 , 4 and 5 . Each turbine stage consists of a set of guide vanes arranged on the stator 18 and a set of moving blades 16 immediately downstream of the set of guide vanes seen in the flow direction of the working medium A. The guide vanes 15 are also supplied with fresh air by an externally arranged air supply unit (not shown in the figure), which is indicated by the flow arrow 10 .

The combustion chamber 19 of the gas turbine 17 , partially shown in the figure, communicates with the flow channel 11 of the working medium A. During operation of the gas turbine 17 , the working medium A from the combustion chamber 19 flows through the flow channel 11 . At this time, the working medium flows through the guide blade 15 and acts on the moving blade 14 to perform work on it.

The disks 3 , 4 and 5 arranged adjacent to one another on the turbine shaft 1 enclose between them the cavities 8 , 9 and 20 which surround the turbine shaft in an annular manner. The inner cavity 8 is located radially inwardly, opposite the intermediate cavity 9 . The outer hollow space 20 surrounds the central hollow space 9 radially outward. The inner cavity 8 is sealed from the intermediate cavity 9 by means of a centrifugal seal 6 , and the intermediate cavity is likewise sealed from the cavity 20 by a centrifugal seal. Not shown in the figure, the centrifugal seal made of sealing wire is placed on the grooves (Fase) of two adjacent discs to securely position them. The inner cavity 8 has a bore or passage 7 for communicating the cavity 8 with the feed port of the integral cooling medium channel of the rotor blade 14 . Thus, the inner cavity 8 is used to supply the cooling medium to the moving blade 14 . Similarly, the cavity 9 also has a borehole 7 communicating with the outlet of the integral cooling medium channel of the moving blade 14 for flowing out of the cooling medium.

The flow of the cooling medium will be described below with the aid of the second turbine stage 22 . The live steam flows axially along the turbine shaft 1 from the cooling medium source to the interior space 8 formed between the disks 3 and 4 , which is indicated by the live steam flow arrow 12 . The live steam then flows through the radially running holes 7 in the disc 4 to the supply opening of a rotor blade 4 in the second turbine stage 22 . The fresh steam plays a cooling role in the moving blade 14 and flows out through the outlet. A further radial hole 7 arranged at the discharge outlet conducts the used steam, indicated by the flow arrow 13 , into the intermediate cavity 9 enclosed by the discs 4 and 5 . The used steam flows out of the cavity 9 through an axial channel into another cavity 23, from where the used steam is sent away.

Fresh air 10 from a fresh air source (not shown) flows over the guide vanes 15 and is guided to a cavity 20 located radially further outward than the cavity 9 . From this cavity 20 fresh air is conducted to the rotor blade 14 . The fresh air discharged at the rear edge of the moving blades 14 is then mixed with the working medium A of the gas turbine.

Through the arrangement according to the invention, i.e. forming the cavities 8, 9, 20 coaxially at a radial distance between the discs 3, 4 and 5 and sealing these cavities simply and reliably with centrifugal seals, An advantageous arrangement can be realized. Combined with the method of the present invention, that is, supplying cooling media with different properties and different pressures (decreasing from inside to outside) to the cavities 8, 9, 20, compared with the prior art, significant improvement can be obtained.

Claims (6)

1. A turbine transmission mechanism with a turbine shaft, which has a plurality of wheel discs arranged adjacent to each other, on which the moving blades can be respectively fixed radially, wherein the moving blades It can be cooled by at least one cooling medium flowing through the internal cooling medium channel of the moving blade, and it is characterized in that: a plurality of turbine shafts are formed between two adjacent discs in the radial direction and respectively surround the turbine shaft in the circumferential direction. cavities, and the cooling medium has different pressures in these cavities, wherein the one or more cooling mediums can respectively flow into these cavities and can flow out of these cavities. 2. The turbine transmission mechanism according to claim 1, wherein the cavities adjacent to each other in the radial direction are sealed to each other. 3. The turbine transmission mechanism according to claim 1 or 2, characterized in that: all cooling passages integrated in one of the moving blades arranged on the same wheel are connected to the wheel through a radial bore or passage. The disc communicates with the same cavity surrounded by an adjacent disc. 4. The turbine transmission mechanism according to any one of claims 1 to 3, characterized in that at least one of the cavities communicates with a cooling medium supply port or a cooling medium discharge port. 5. A method for cooling a turbine transmission as claimed in any one of claims 1 to 4, characterized in that the pressure of the cooling medium flowing through a cavity is higher than that flowing through the radially outwardly adjacent cavity The pressure of the cooling medium in the cavity. 6. The method for cooling a moving blade of a turbine transmission mechanism according to claim 5, characterized in that: what flows into the innermost cavity in the radial direction is fresh steam, and flows into the radially adjacent cavity The outer cavity contains used steam, and the flow into said radially outermost cavity is fresh air.

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