WO1995004225A1 - Process and device for tapping a partial stream from a stream of compressed gas - Google Patents

Abstract

A process is disclosed for tapping a partial stream (2) from a stream (1) of compressed gas at a gap (6) provided with an arrangement of blade profiles (3) and delimited by at least two walls (4, 5), through which the stream (1) may pass. The partial stream is tapped from an area of the stream (1) spaced apart from the walls (4, 5). A device for carrying out this process has a duct arrangement (7, 8, 9, 10, 21, 23, 24) for taking away the partial stream (2) with an inflow opening (11) into which the stream (1) may flow and which is spaced apart from the walls (4, 5). A high quality partial stream (2) may thus be obtained for cooling purposes in gas turbines. In particular, the stream has a low aerosol content, is under a relatively high pressure and has a relatively low temperature.

Description

description

Method and device for withdrawing a partial stream from a stream of compressed gas

The invention relates to a method and a device for withdrawing a partial stream from a stream of compressed gas at a gap which has an arrangement of blade profiles and is delimited by at least two walls and which can be penetrated by the stream. The device has a line arrangement for discharging the partial flow, which has an inflow opening that can be flowed against by the flow. The invention also relates to the use of this device.

A method or a device of the type described is used, for example, in a turbocompressor of a gas turbine in order to take a partial flow from a stream of compressed air passing through the turbocompressor, which is used to cool another component of the gas turbine, in particular a combustion chamber or a turbine in the narrower sense, should be used. In particular, the cooling of a turbine with such a partial flow is of great importance, since the cooling generally has to take place through cooling channels with relatively small cross sections, which requires the provision of a partial flow with a sufficiently high pressure. In addition, unlike in a combustion chamber, gas is generally not available on a turbine anyway, which gas could easily be used for cooling purposes.

In a turbine, the cooling of blade profiles in the area of the inlet is particularly important since the highest temperatures are present there. The air used for cooling and taken as a partial flow from the turbo compressor should be as free as possible of particles or aerosols which could block the line arrangement for guiding the partial flow. In addition, it must be under as high a pressure as possible, as already mentioned, and their temperature should be as low as possible in order to achieve the highest possible cooling effect.

The removal of a partial stream from a stream of compressed gas at a device having an arrangement of blade profiles and a gap delimited by at least two walls, which gap can be penetrated by the stream, on a turbocompressor of a gas turbine has hitherto occurred in such a way that the partial stream is intercepted on the inner walls of the gap, which contains blade profiles in the form of a blade ring. The reason for this is the assumption that the concentration of particles in areas of the current on an inner wall is minimal. In addition, in order to be able to separate particles entrained in the partial flow, a strong deflection of the partial flow can also be provided immediately after its removal. The disadvantage of such a removal is that a relatively large pressure loss has to be accepted and thus only a partial flow which is at a relatively low pressure and at a relatively high temperature is obtained. For this reason, the known removal generally requires fans to increase the pressure in the partial flow and coolers to lower its temperature. In addition, the strong pressure loss during the known withdrawal of a partial flow very much questions the effectiveness of cooling with this partial flow if the pressure losses which the gas stream to be led through a combustion chamber, for example behind a turbocompressor, suffers through appropriate training the gas turbine are comparatively low. Such low pressure losses are indeed of great importance for reasons of thermodynamics and to ensure the highest possible efficiency of the gas turbine. Thus, if the pressure losses of the stream in a gas turbine cooled in a known manner are reduced, the demands on blower devices to increase the pressure in the partial stream increase, for which at least part of the savings gained due to the improvement of the gas turbine is used up again. The object of the invention is to provide a method for removing a partial stream from a stream of compressed gas at a gap having an arrangement of blade profiles and limited by at least two walls, which can be enforced by the stream, which meets the requirements described above in the context of an implementation in one Gas turbine in a particularly large extent. An apparatus for carrying out this method and the use of this apparatus are also to be specified.

With regard to a method, the object of the invention is achieved by a method for removing a partial stream from a stream of compressed gas at a gap which has an arrangement of blade profiles and is delimited by at least two walls and which can be enforced by the stream, the Removal takes place from an area of the stream spaced from the walls.

According to the invention, the removal of a partial stream from a stream of compressed gas is designed in such a way that a clear improvement is achieved within the framework of careful consideration of the various aspects to be observed, in particular a comparatively high one if the concentration of undesired aerosols in the particle stream is sufficiently limited Pressure is reached at a comparatively low temperature of the partial flow. Requirements for blowers and cooling devices for the particle stream are therefore at least substantially reduced compared to the prior art; depending on the other operating conditions, fan and cooling devices for the partial flow can be completely dispensed with. The quality of the partial flow taken from a thermodynamic point of view is particularly high because the spacing of the means for removal from the walls influences the partial flow by friction on the walls of the gap or on the walls of the gap

Components upstream of the gap are significantly reduced compared to the prior art. In particular, friction effects lead to pressure losses on the one hand and temperature increases on the other; According to the invention, both are substantially suppressed.

It is advantageous to slow down the partial flow during or immediately after removal, for example by leading it through a line arrangement which widens in the manner of a diffuser. A favorable increase in the pressure in the partial flow is thereby achieved.

The gap from which the partial flow is removed according to the invention is advantageously approximately circular in shape with respect to an axis, and the walls are given by an inner wall and an outer wall. If the current has a swirl with respect to the axis, which is generally the case with a current passing through a turbocompressor, the removal takes place with particular advantage from a range between approximately 25% and approximately 60% of a height of the gap tes, determined from the inner wall. The achievable advantage is, in particular, that in one out of one

A stream containing aerosols can be obtained with a partial stream which may have a small proportion of aerosols and, as desired, a low temperature and high pressure.

The method is particularly preferred in the method without prejudice to other configurations, in which the stream has a vortex zone on each wall in which it has vortex and boundary layer zones on each blade profile in which it is delayed a removal zone spaced apart from each vortex zone and each boundary layer zone. Vortex zones form in practically every turbocompressor on the inner wall and on the outer wall due to a lateral pressure gradient in the gap, which is due to the fact that a pressure difference is formed between the sides of each blade profile which are swept by the flow . Such a pressure gradient leads to a more or less direct compensation stroke along the respective wall. flow, which is compensated by a backflow spaced from the wall, so that a vortex is formed from the equalization current and backflow. In addition to boundary layer effects on the walls, vortex zones also occur on the walls, in which the current has significantly higher temperatures due to increased friction than in zones with a greater distance from the walls. Boundary layer effects are effective on the blade profiles themselves due to the friction of the current on the blade profiles; boundary layer zones are formed in which the current is also warmed compared to other zones. In order to achieve a comparatively cool stream, the partial stream should be withdrawn from an extraction zone which is spaced both from the fluidized zones and from the boundary layer zones.

With regard to a device, the solution according to the invention is achieved by a device for removing a partial stream from a stream of compressed gas at a gap which has an arrangement of blade profiles and is delimited by at least two walls and can be penetrated by the stream, with a line arrangement for discharging the partial flow, which has an inflow opening that can be flowed against by the flow, the inflow opening being spaced apart from the walls.

The line arrangement advantageously runs at least partially in a blade profile, as a result of which the outlay in terms of apparatus for displaying the device is kept low. The inflow opening is advantageously located in a piece of pipe which protrudes from the blade profile in the manner of a pitot tube. In this way, a partial flow largely unaffected by frictional effects on the gap or the blade profiles is obtained. As an alternative, a flow box that can be flowed against by the flow can be formed between two blade profiles in the gap, and communicates with at least one channel in one of the blade profiles in order to discharge the partial flow; the flow box is conveniently of both Blade profiles limited. In this way, a partial flow with a relatively high mass throughput can be discharged, the device being able to be produced relatively easily and with little effort.

With particular advantage, the device is designed, without prejudice to any further development, in such a way that a partial flow flowing into the inflow opening is dammed up. As a result, an increase in the pressure in the partial flow can be achieved. The line arrangement of the

Device directly behind the inflow opening extended in the manner of a diffuser in order to delay the partial flow.

In the context of the device, without further development, the gap is approximately circular with respect to an axis, the walls are given by an inner wall and an outer wall, and the blade profiles are arranged approximately rotationally symmetrically about the axis. Such a design is particularly important in turbo compressors, preferably in turbo compressors in gas turbines. In such a device, the inflow opening is advantageously arranged in a range between approximately 25% and approximately 60% of a height of the gap, determined starting from the inner wall. In this way, as already mentioned above, a partial stream with particularly advantageous properties can be obtained.

The blade profiles in the device are advantageously parts of a turbocompressor and are preferably located at an outlet of the turbocompressor. In particular, the latter feature is important for obtaining a partial flow which is particularly suitable for cooling a gas turbine connected downstream of the turbocompressor.

The device according to the invention of any configuration is used in particular for withdrawing a partial flow of Air from a gas turbine turbocompressor; in particular, the partial flow of a combustion chamber and / or a turbine of the gas turbine is supplied as cooling air.

Examples for carrying out the invention are explained in more detail with reference to the drawing. The five figures of the drawing are partially schematic and / or slightly distorted to highlight certain features. In detail: FIG. 1 shows a blade profile which has been upgraded by a line arrangement for discharging a partial flow;

FIG. 2 shows a sketch of the flow conditions in a gap with blade profiles;

FIG. 3 shows a further line arrangement for discharging a partial flow;

FIG. 4 shows a differently designed line arrangement for withdrawing a partial flow from a gap with blade profiles;

FIG. 5 shows a further exemplary embodiment for such a line arrangement;

FIG. 6 shows a sketch to clarify certain features of the embodiment according to FIG. 5; and

FIG. 7 shows a gas turbine in which methods and devices according to the invention can be implemented.

FIG. 1 shows a blade profile 3 which is flown by a stream 1 of compressed gas. The blade profile 3 can, for example, be part of a guide blade in a turbocompressor of a gas turbine. A pipe section 7 protrudes from the blade profile 3 and has an inflow opening 11 into which a partial flow 2 of the flow 1 enters. The partial stream 2 reaches the channels 9 of the blade profile 3 from the pipe section 7 and is drawn off through these channels 9. leads. The partial flow 2 can be used, for example, to cool guide vanes and rotor blades of a turbine which is connected downstream of a turbocompressor, of which the blade profile 3 is a component, and a combustion chamber following the turbocompressor. Behind the inflow opening 11, the pipe section 7 widens in the manner of a diffuser in order to increase the pressure in the partial flow.

FIG. 2 shows the flow conditions in a gap 6 between an inner wall 4, an outer wall 5 and two

Blade profiles 3, seen in cross section. In the flow, which is to be thought in FIG. 2 approximately perpendicular to the plane of the drawing, vortex zones 26 are formed on the inner wall 4 as well as on the outer wall 5 by virtue of the fact that on the sides swept by the flow of each vane profile 3 train different prints. As a result, a lateral pressure drop occurs in a gap 6 delimited by the inner wall 4, the outer wall 5 and two blade profiles 3, which causes equalizing currents which occur laterally on the inner wall 4 or the outer wall 5 run along. These equalizing currents complement one another to form vortices, as a result of which the vortex zones 26 arise. Because of the eddies, there is a comparatively high friction of the current on the inner wall 4 and on the outer wall 5, which results overall in a significant temperature increase in each vortex zone 26. There is also the effect of friction directly on each blade profile 3 and on the side of the vortex zones 26, which leads to boundary layer zones 27 being formed in the vicinity of the blade profiles 3, where on the one hand the current flows relatively slowly and on the other hand is heated up by friction effects. It is therefore particularly advantageous for a partial stream to be withdrawn from the stream in a withdrawal zone 28 which is spaced apart both from the vortex zones 26 and from the boundary layer zones 27. Examples of how this can be done are shown in FIGS. 3 and 4. FIG. 3 shows two blade profiles 3 of a turbocompressor, which are seated on an inner wall 4. The current 1 is indicated by an arrow. Arranged behind the blade profiles is a pipe section 7 with an inflow opening 11 which widens like a diffuser. The partial flow 2 to be discharged enters the pipe section 7 through the inflow opening 11 and is practically delayed upon entry, which results in an advantageous increase in its pressure . The pipe section 7 enables, as shown, a discharge of a partial flow 2 which is largely unaffected by interference effects of the type described above on the inner wall 4, the outer wall 5 (not shown) and the blade profiles 3.

FIG. 4 shows a further embodiment of a device for removing a partial stream 2 from a stream 1 of compressed gas. The blade profile 3 is enclosed between an inner wall 4 and an outer wall 5 and belongs to a guide vane ring in a turbocompressor. A turbine shaft 15 rotatable about an axis 12 is indicated as a further component of this turbocompressor. The blade profiles 3 are regularly arranged around the axis 12. Between two blade profiles 3, a piece of pipe 7 protrudes from the outer wall 5, which is initially directed perpendicular to the axis 12, but has an inflow opening 11 which is opposite to a flow 1 flowing towards the blade profile 3. A duct 9 connects to this inflow opening 11 in the pipe section 7, which opens behind the outer wall 5 into a collecting space 10, from which a cooling gas line 21 (only indicated) leads away. An accumulation effect at the inflow opening 11 is desirable.

FIG. 5 shows a further exemplary embodiment of an arrangement for removing a partial stream 2 from a stream 1 of compressed gas. Between two blade profiles 3, which are seated on an inner wall 4, an inflow box 8 is forms in which the partial flow 2 enters and from which it is discharged through channels 9 in the blade profiles 3.

FIG. 6 shows, in a schematic form, a cross section through an arrangement according to FIG. 5. The blade profile 3 is arranged in the gap 6 between an inner wall 4 and an outer wall 5. The inflow box 8 directly adjoins the blade profile 3 and has an inflow opening 11, which, as can be seen from FIG. 3, is opposed to stream 1 of the gas. The inflow opening 11 extends over a quarter of the height of the gap 6 to be determined between the inner wall 4 and the outer wall 5, wherein it comprises a range between approximately 25% and approximately 60% of the height of the gap 6. This area is particularly suitable for withdrawing a partial flow, especially in this

A partial stream 2 is obtained which is at best slightly aerosolized, is under relatively high pressure and relatively low temperature.

Figure 7 shows a gas turbine, which is used to implement the

Invention is suitable. In the gas turbine, a turbocompressor 13 is supplied with atmospheric air through a supply air line 22; in the turbocompressor 13, which is coupled to a turbine 17 via a turbine shaft 15, the air is compressed and, as a stream of compressed gas, via a

Fresh gas line 18 fed to a combustion chamber 16. A fuel is also supplied to the combustion chamber 16 via a fuel line 25. The air and the fuel burn in the combustion chamber 16 and form flue gases which are fed to the turbine 17 via a flue gas line 19. In the

Turbine 17, the flue gases are thermodynamically expanded and leave the turbine 17 through an exhaust pipe 20. Cooling gas for cooling components of the turbine 17 which are highly thermally loaded is also provided from the turbocompressor 13. The cooling gas is taken from the turbocompressor 13 at the outlet 14 or in the vicinity of the outlet 14 via a cooling gas line 21. To apply cooling gas to cooling gas line 21 the method and the device according to the invention are particularly suitable; in this case, the partial stream removed from the compressed gas serves as cooling gas. Installations in the cooling gas line 21, in particular the cooling and blower devices mentioned, are conceivable depending on the application. In front of the turbine 17, the cooling gas line 21 branches into two branch lines 23 and 24. This is intended to indicate that the turbine 17 can be acted upon with cooling gas in such a way that both rotating parts and stationary parts also have Cooling gas can be applied; Rotating parts can be acted upon, for example, via the branch line 23 guided in the vicinity of the turbine shaft 15, and stationary parts can be acted upon via the branch line 24 led to the periphery of the turbine 17. For this purpose, express reference is made to possibilities for cooling a turbine which are known in the prior art.

The presented method and the presented device for extracting a partial stream from a stream compress

Gases at a gap having an arrangement of blade profiles and delimited by at least two walls, through which the stream can pass, the removal taking place from a region of the stream spaced apart from the walls each deliver a partial stream of high quality for cooling ¬ purposes or the like. Under certain circumstances, they make it possible to dispense with complex blower and cooling devices and are particularly suitable for upgrading gas turbines, in particular a gas turbine which has a combustion chamber and a fresh gas and flue gas line between a turbo compressor and a turbine, the pressure loss exceeding the fresh gas line, the combustion chamber and the flue gas line are particularly small.

Claims

claims 1. Method for removing a partial stream (2) from a stream (1) of compressed gas at a gap (6) having an arrangement of blade profiles (3) and delimited by at least two walls (4, 5), which is separated from the stream (1) is enforceable, characterized in that the removal takes place from an area of the stream (1) spaced from the walls (4, 5). 2. The method according to claim 1, wherein the partial flow (2) is slowed down immediately after removal. 3. The method of claim 1 or 2, wherein the gap (6) with respect to an axis (12) is approximately circular and the walls (4, 5) are an inner wall (4) and an outer wall (5). 4. The method according to claim 3, wherein the current (1) has a swirl with respect to the axis (12) and in which the removal from a range between 25% and 50% of a height of the gap, determined starting from the inner wall (4). 5. The method according to any one of the preceding claims, wherein the flow (1) on each wall (4, 5) has a vortex zone (26) in which it has vortex, and on each blade profile (3) boundary layer zones (27), in which it is delayed, and in which the partial stream (2) is removed from a removal zone (28) spaced apart from each vortex zone (26) and each boundary layer zone (27). 6. Device for removing a partial stream (2) from a stream (1) of compressed gas at a gap (6) having an arrangement of blade profiles (3) and delimited by at least two walls (4, 5), which is separated from the stream (1) is enforceable with a line arrangement (7, 8, 9, 10, 21, 23, 24) for discharging the partial flow (2), which has an inflow opening (11) which can be flowed by the flow (1), characterized in that the inflow opening (11) is spaced from the walls (4, 5). 7. The device according to claim 6, wherein the line arrangement (7, 8, 9, 10, 21, 23, 24) extends at least partially in a blade profile (3). 8. The device according to claim 7, wherein the Einströmöff¬ opening (11) in a pipe section (7) which protrudes from the Schaufel¬ profile (3). 9. The device as claimed in claim 7, in which an inflow box (8) which can be flowed against by the stream (1) and which has at least one channel (9) for discharging the partial stream (2) is formed between two blade profiles (3) one of the blade profiles (3) communicates. 10. The device according to claim 9, wherein the inflow box (8) of both blade profiles (3) is limited. 11. The device according to one of claims 6 to 10, wherein the partial flow (2) in the inflow opening (11) can be stowed. 12. Device according to one of claims 6 to 11, in which the line arrangement (7, 8, 9, 10, 21, 23, 24) is expanded directly behind the inflow opening (11) in the manner of a diffuser. 13. Device according to one of claims 6 to 12, wherein the gap (6) with respect to an axis (12) is approximately circular, in which the walls (4, 5) an inner wall (4) and an outer wall (5) and in which the blade profiles (3) are arranged approximately rotationally symmetrically about the axis (12). 14. The apparatus of claim 13, wherein the blade profiles (3) are designed for a flow (1) which has a swirl, and in which the inflow opening (11) in a range between 25% and 50% of a height Gap (6), determined starting from the inner wall (4), is arranged. 15. Device according to one of claims 6 to 14, wherein the blade profiles (3) are parts of a turbocompressor (13), preferably arranged at an outlet (14) of the turbocompressor (13). 16. Use of a device according to one of claims 6 to 15 for removing a partial flow (2) of air from a turbocompressor (13) of a gas turbine. 17. Use according to claim 16, wherein the partial flow (2) ei¬ ner combustion chamber (16) and / or a turbine (17) of the gas turbine is supplied as cooling air.