JP2018150869A - Exhaust muffler for gas turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust muffler for a gas turbine which makes downsizing compatible with muffling performance.SOLUTION: An exhaust muffler 2 comprises: a package 7 which is formed in a rectangular parallelepiped shape and includes a sound absorber on its inner surface; an exhaust introduction port 8 which is provided in a lower part of one side face; an exhaust discharge port 10 which is provided in an upper part of the other side face; an upside inner projection 12 that is provided just under the exhaust discharge port; and a downside inner projection 13 that is provided on one side face lower than the upside inner projection. An inclined channel 17 between a downward slope 14 and an upward slope 15 that are in parallel is inclined closer to a side face at an opposite side of the exhaust discharge port towards the upside. Downsizing of the exhaust muffler is made compatible with a muffling performance, a height of the exhaust muffler is reduced and in addition to a reduction of noise caused by gas turbine fundamental sound, and an effect of a reduction of fluid noise may also be obtained.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an exhaust silencer for a gas turbine. More specifically, the present invention is used in a packaged gas turbine facility mainly used for power generation in an emergency, and achieves both miniaturization and noise reduction performance. The present invention relates to an exhaust silencer.

  The following Patent Document 1 describes an invention of a plenum type silencer in which a partition section having a triangular cross section protruding from each other is provided on the inner peripheral surface of a cylindrical body forming a duct. In this document, as an action of the invention, “exhaust gas etc. enters the inside from one end of the cylindrical body and passes through the plenum effect caused by colliding with the partition part and the part having a large and small passage cross-sectional area alternately. On the other hand, the cross-sectional shape of the partition portion is substantially triangular, so that the exhaust gas easily flows and the cross-sectional area of the ventilation path through which exhaust gas or the like passes is abrupt as in the prior art. It increases or decreases slowly without increasing or decreasing, and therefore duct resistance is remarkably reduced compared to the conventional case.

  In Patent Document 2 below, an exhaust silencer of a gas turbine in which an exhaust inlet from the gas turbine is provided at the lower part of the side surface of the gas turbine package and an exhaust outlet is provided at the upper part of the opposite side surface of the package. The vessel is described.

Japanese Utility Model Publication No. 6-48096 Japanese Utility Model No.5-1634

These conventional silencers for gas turbines cannot be said to have been sufficiently studied for compatibility between the size reduction of the silencer package and the silencing performance.
In recent years, gas turbine equipment used for emergency power generators and the like has been configured in a form in which the main parts of the equipment are packaged, but tends to be installed in narrow places such as the rooftop, intermediate floors, and basements of buildings. For this reason, there is an increasing demand for a compact gas turbine facility as a whole.

  A silencer constituting a part of gas turbine equipment requires a certain length in a path through which exhaust passes in order to achieve a necessary silencing performance, and is generally in the form of a longitudinal shape. It is an important factor that affects the overall size of the equipment. And when this is installed in a vertically long manner under the restriction of the installation location that there is no margin in the height direction as described above, it is often required to reduce the size of the silencer in the height direction. .

  Furthermore, in a silencer of a gas turbine facility, there is a strong demand for arbitrarily setting the direction in which exhausted air is exhausted. Generally, the exhaust silencer connected to the gas turbine is installed in a vertically long manner as described above, and the exhaust discharge direction is such that the exhaust is introduced from the lower side and discharged from the upper side. There is a feature that is often seen. When exhausting indoors, it is necessary to connect it to a duct that guides the exhaust.When exhausting outdoors, the exhaust is laterally guided, a hood is provided at the discharge destination, and rainwater enters the silencer. This is because it is necessary to avoid entering and damaging the sound absorbing material such as rock wool.

  An object of the present invention is to provide an exhaust silencer for a gas turbine that takes into account the morphological restrictions in the installation state of the silencer of the conventional gas turbine equipment described above, and achieves both downsizing and silence performance. .

An exhaust silencer for a gas turbine according to claim 1 is provided.
A silencer package with a rectangular parallelepiped shape and a sound absorbing material on the inner surface,
An exhaust inlet that is provided at a lower portion of the side surface of the package and introduces exhaust of the gas turbine from an external lateral direction;
An exhaust exhaust port provided at an upper portion of the side surface of the package and exhausting gas turbine exhaust in an external lateral direction;
An upper inner protrusion provided on the inner surface of the package directly below the exhaust outlet, the inner surface protruding in a chevron shape;
A lower inner convex portion that is provided at a position relatively lower than the upper inner convex portion on a side surface facing the side surface of the package provided with the upper inner convex portion, and the inner surface protrudes in a mountain shape. I have.

The exhaust silencer for a gas turbine according to claim 2 is the exhaust silencer for a gas turbine according to claim 1,
The upper inner convex portion has a downward inclined surface in which the direction of the perpendicular on the inner side of the package faces downward from the horizontal,
The lower inner convex portion has an upward inclined surface in which the direction of the vertical line on the inner side of the package faces upward from the horizontal,
The downward inclined surface and the upward inclined surface arranged substantially parallel to each other form an inclined flow path,
The inclined flow path is inclined so as to approach a side surface facing the side surface provided with the exhaust outlet as it goes upward inside the package.

The exhaust silencer for a gas turbine according to claim 3 is the exhaust silencer for a gas turbine according to claim 2,
The exhaust passage width D in the inclined passage is in the range of λ / 2 to λ, where λ is the wavelength of the gas turbine original sound.

The exhaust silencer for a gas turbine described in claim 4 is the exhaust silencer for a gas turbine according to any one of claims 1 to 3,
The exhaust discharge port is provided on a side surface opposite to the side surface provided with the exhaust introduction port.

The exhaust silencer for a gas turbine according to claim 5 is the exhaust silencer for a gas turbine according to any one of claims 1 to 3,
The exhaust outlet is provided on a side surface where the exhaust inlet is provided.

The exhaust silencer for a gas turbine according to claim 6 is the exhaust silencer for a gas turbine according to any one of claims 1 to 5,
An exhaust guide path is connected to an opening of the exhaust discharge port outside the package.

An exhaust silencer for a gas turbine according to claim 7 is provided.
A silencer package having a rectangular parallelepiped shape in which one of three sides orthogonal to each other is longer than the other two sides, and having a sound absorbing material on the inner surface;
An exhaust inlet that is provided near one end of the longitudinal direction on a side surface parallel to the longitudinal direction of the package, and that introduces exhaust of the gas turbine from the outside along a direction intersecting the side surface;
An exhaust outlet that is provided near the other end of the longitudinal direction on a side surface parallel to the longitudinal direction of the package, and exhausts the exhaust of the gas turbine to the outside along a direction intersecting the side surface;
An exhaust discharge port side inward convex portion provided at a position near the center of the package in the longitudinal direction adjacent to the exhaust discharge port on the inner surface of the package;
Provided at a position closer to the exhaust introduction port than the exhaust discharge port side inner convex portion on a side surface facing the side surface of the package provided with the exhaust discharge side inner convex portion, and a cross section on the inner surface is a mountain shape And an exhaust-inlet-side-side convex portion.

  According to the present invention, a package having a rectangular parallelepiped shape is introduced, exhaust is introduced from the lateral direction (direction intersecting the side surface) at the lower portion (one end portion in the longitudinal direction), and the upper portion (the other end in the longitudinal direction). In the exhaust silencer of the gas turbine that exhausts the exhaust gas in the lateral direction (direction intersecting the side surface), it is possible to achieve both the downsizing of the exhaust silencer and the silencing performance, especially in the height direction of the exhaust silencer The (longitudinal direction) size can be reduced. Further, in addition to the reduction of the gas turbine noise using the gas turbine as a generation source, the effect of reducing the fluid noise caused by the exhaust flow can be obtained.

It is a perspective view of a gas turbine concerning a 1st embodiment of the present invention, and an exhaust silencer connected to the gas turbine. FIG. 2A is a perspective view showing the internal structure of a part of the exhaust silencer according to the first embodiment of the present invention, and FIG. 2B is a transmission loss in the exhaust silencer. It is a figure which shows the relationship of a frequency, and fraction (c) is a figure which shows typically the vibration of the air in the package of an exhaust silencer. It is a figure which shows the variation of the exhaust silencer which concerns on 1st Embodiment. It is a figure which shows the effect | action of the exhaust silencer which concerns on 1st Embodiment of this invention, and visualized the flow of the exhaust_gas | exhaustion inside an exhaust silencer using the analysis software based on numerical fluid dynamics (Computational Fluid Dynamics) It is a streamline diagram. It is a figure which shows the effect | action of the exhaust silencer which concerns on 1st Embodiment of this invention, and uses the analysis software based on the numerical fluid dynamics (Computational Fluid Dynamics) for the magnitude | size of the energy of the exhaust noise inside an exhaust silencer It is the contour figure visualized by doing. It is a figure which shows the effect | action of the exhaust silencer which concerns on 2nd Embodiment of this invention, and visualizes the flow of the exhaust_gas | exhaustion inside an exhaust silencer using the analysis software based on numerical fluid dynamics (Computational Fluid Dynamics) FIG. It is the perspective view which fractured | ruptured some exhaust silencers which concern on 3rd Embodiment of this invention, and showed the internal structure. It is a figure which shows the effect | action of the exhaust silencer which concerns on 3rd Embodiment of this invention, and uses the analysis software based on the numerical fluid dynamics (Computational Fluid Dynamics) for the magnitude | size of the energy of the exhaust noise in an exhaust silencer It is the contour figure visualized by doing. It is the perspective view which fractured | ruptured some exhaust silencers which are the comparative examples with respect to each embodiment, and showed the internal structure. It is a figure which shows the effect | action of the exhaust silencer which is a comparative example, and is the streamline figure which visualized the flow of the exhaust in the exhaust silencer using the analysis software based on Computational Fluid Dynamics . It is a figure which shows the effect | action of the exhaust silencer which is a comparative example, and the contour which visualized the magnitude | size of the energy of the exhaust noise inside an exhaust silencer using the analysis software based on Computational Fluid Dynamics FIG. The diagram (a) is a diagram used to examine the noise source in the exhaust silencer as a comparative example, and the analysis software based on computational fluid dynamics (Computational Fluid Dynamics) is used inside the exhaust silencer. It is the contour figure which visualized the flow velocity, and the fraction figure (b) is the contour figure which visualized the magnitude of energy similarly. 6 is a graph showing the results of a noise level evaluation test performed on an actually manufactured apparatus for the first embodiment and a comparative example.

[First Embodiment]
A first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 shows an outline of the gas turbine equipment according to the first embodiment. This gas turbine equipment is an outdoor installation type, and includes a gas turbine 1 and an exhaust silencer 2 connected to an exhaust system of the gas turbine 1. The gas turbine 1 is installed on the common platform 3 via a vibration isolator. A generator 5 is connected to the output shaft of the gas turbine 1 via a speed reducer 4. The gas turbine 1 and the generator 5 are covered by a common enclosure 6. In FIG. 1, a part of the enclosure 6 is broken to show the internal structure.

  As shown in FIGS. 1 and 2A, the exhaust silencer 2 in the first embodiment has a rectangular parallelepiped package 7 that is long in the vertical direction. As can be understood from FIG. 2A showing the cross-sectional structure of the package 7, an exhaust introduction port 8 is provided at a lower portion of one side surface of the package 7. The exhaust introduction port 8 is connected to the exhaust port of the gas turbine 1, and the exhaust of the gas turbine 1 flowing from the outside lateral direction, that is, the direction intersecting the side surface can be introduced into the package 7.

  As shown in FIG. 2A, an exhaust diffuser 9 is connected to the exhaust inlet 8 inside the package 7. The exhaust diffuser 9 prevents damage to wall materials such as a sound absorbing material, which will be described later, due to the exhaust flow directly colliding with the inner wall surface of the package 7. The exhaust diffuser 9 normally has a structure having a cylindrical portion provided with a plurality of slits or holes and a disk-shaped blocking portion that closes an end opening of the cylindrical member, and diffuses exhaust in the circumferential direction of the cylinder. Has the function of

  As shown in FIG. 2A, an exhaust discharge port 10 is provided at the upper part of the side surface of the package 7. In the present embodiment, the exhaust discharge port 10 is provided on the side surface opposite to the side surface on which the exhaust introduction port 8 is provided. The exhaust discharge port 10 can discharge the exhaust of the gas turbine 1 to the outside of the package 7 along a direction intersecting the side surface.

  As shown in FIG. 2 (a), an exhaust hood 11 as an exhaust guide path is connected to the opening of the exhaust outlet 10 outside the package 7. The exhaust hood 11 has a bent shape that directs the exhaust discharged in the horizontal direction upward. Although not shown in detail, the exhaust hood 11 is drained to prevent rainwater from entering the package 7 of the exhaust silencer 2. Is provided.

  In the case of gas turbine equipment installed indoors, an exhaust duct, which is an exhaust guide path in a building, is connected to the outer surface of the package 7 where the exhaust outlet 10 is open. Exhaust gas from the exhaust silencer 2 is exhausted to the outside through an exhaust duct 10 through an exhaust duct.

  As shown in FIG. 2 (a), on the inner surface of the package 7, the inner surface of the package 7 projects inward so as to form a chevron at a position directly below the side surface of the package 7 where the exhaust outlet 10 is provided. The upper inner convex portion 12 is provided. Further, on the inner surface of the side surface facing the side surface provided with the upper inner convex portion 12, the inner surface of the package 7 faces inward so as to form a mountain shape at a position relatively lower than the upper inner convex portion 12. A protruding lower inner convex portion 13 is provided.

  As shown in FIG. 2A, the upper inner convex portion 12 is a mountain-shaped convex portion, and thus has two inclined surfaces, and the relatively lower surface is referred to as a downward inclined surface 14. . The downward inclined surface 14 means an inclined surface in which the direction of the vertical line inside the package 7 is directed downward from the horizontal. Moreover, since the lower inner convex portion 13 is a mountain-shaped convex portion, it has two inclined surfaces, and the relatively upper surface is referred to as an upward inclined surface 15. The upward inclined surface 15 means an inclined surface in which the direction of the vertical line inside the package 7 is directed upward from the horizontal.

  As shown in FIG. 2A, the relatively upper surface of the upper inner convex portion 12 is referred to as an upward inclined surface 16. The upward inclined surface 16 means that, like the upward inclined surface 15, it is an inclined surface in which the direction of the vertical line inside the package 7 is directed upward from the horizontal.

As shown in FIG. 2 (a), the downward inclined surface 14 of the upper inner convex portion 12 and the upward inclined surface 15 of the lower inner convex portion 13 are substantially parallel to each other, and the exhaust passage width Forms an inclined channel 17 having a constant interval D. The inclined flow path 17 is inclined inside the package 7 so as to approach a side surface facing the side surface provided with the exhaust outlet 10 as it goes upward.

  Although not shown, a sound absorbing material in which punching metal is disposed on the surface of rock wool is attached to the inner surface of the package 7 including the surfaces of the upper inner convex portion 12 and the lower inner convex portion 13. Depending on the level of noise required for the exhaust silencer 2, the installation of the sound absorbing material on the inner surface of the package 7 may be omitted, and the iron plate constituting the main body of the package 7 may be left as it is.

  The exhaust silencer 2 of the present embodiment is a sound absorbing duct type silencer in which a sound absorbing material is provided on the inner surface of the package 7. The transmission loss of this type of silencer increases in proportion to the sound absorption rate of the sound absorbing material, and, as shown in FIG. 2B, the wavelength of the gas turbine original sound (or the wavelength of the sound for which a high silencing effect is desired) ) Is λ, the maximum transmission loss is obtained in the frequency range (c / 2D to c / D, where c is the speed of sound) where the exhaust passage width of the package 7 is in the range of λ / 2 to λ. That is, the highest silencing effect is obtained within this range. This is because, when the dimensions of the package 7 are equal to λ / 2 and λ, the vibration of air when sound waves are transmitted through the package 7 becomes larger when the sound absorbing material is stretched as shown in FIG. is there. As a better example of this embodiment, the flow path width D of the exhaust gas, which is the distance between the downward inclined surface 14 and the upward inclined surface 15 in the inclined flow path 17, is the wavelength of the original sound of the gas turbine 1 of the present embodiment. When λ is λ, the range is set in the range of λ / 2 to λ. At this time, the highest silencing effect is obtained. Further, when the wavelength λ of the original sound of the gas turbine 1 is shorter than the dimension of the package 7, as in the variation of the first embodiment shown in FIG. Can be divided into the optimum flow path width D. The exhaust silencer is important for the total silencing effect of gas turbine noise and fluid noise, and does not aim at optimizing the sound absorption effect at the position of the inclined channel 17, and the exhaust channel width D is set to 4λ at the maximum. Even in such a case, a practically effective silencing effect is obtained.

FIG. 4 is a streamline diagram obtained by visualizing the exhaust flow inside the exhaust silencer 2 of the present embodiment using analysis software based on Computational Fluid Dynamics (abbreviated as CFD). In the exhaust silencer 2 of the gas turbine equipment as in the present embodiment, the following two points are important for effective silencing.
1) The gas turbine original sound generated in the gas turbine 1 and led to the exhaust silencer 2 through the exhaust inlet 8 is sufficiently silenced.
2) Sound should not be generated between the exhaust inlet 8 and the exhaust outlet 10 (including the exhaust hood 11 and the exhaust duct) of the exhaust silencer 2.

  As described above, the interval D of the inclined flow path 17 is set such that a transmission loss is obtained in accordance with the frequency component having the highest sound pressure in the gas turbine original sound (or the frequency component for which a silencing effect is desired). The gas turbine 1 includes a compressor and a turbine, and each of the compressor and the turbine generates a gas turbine original sound having a frequency determined by the product of the number of blades and the number of rotations. The exhaust silencer 2 of the present embodiment According to this, the sound of the frequency component with the highest sound pressure can be muted.

  As shown in FIG. 4, the exhaust speed is attenuated from the exhaust introduction port 8 through the inclined flow path 17 of the interval D to the exhaust discharge port 10. Further, in the inclined flow path 17 with the interval D, most of the exhaust flow is arranged in the same direction as the inclined flow path 17 and is directed in the side surface direction opposite to the exhaust discharge port 10. Due to the loss mechanism, the outstanding frequency components in the original gas turbine sound are effectively attenuated.

  As shown in FIG. 4, the flow of the exhaust gas that has passed through the inclined flow path 17 flows in the direction of the exhaust discharge port 10 while suppressing the speed difference that causes fluid noise described later by the action of the upward inclined surface 16. It is in order.

  FIG. 5 is a diagram in which the magnitude of the energy of the exhaust noise in the exhaust silencer 2 of the present embodiment is analyzed and visualized by the CFD method. In this analysis, the sound (fluid noise) generated between the exhaust inlet 8 and the exhaust outlet 10 (including the exhaust hood 11 and the exhaust duct) of the exhaust silencer 2 is evaluated by simulation. Does not contain the components of the original gas turbine sound. According to this example, the energy of the exhaust is attenuated from the exhaust introduction port 8 through the inclined flow path 17 with the interval D to the exhaust discharge port 10. The noise level in the vicinity of the outlet of the exhaust hood 11 (A in the figure) was about 85 dB, and a noise reduction effect of 10 dB was obtained with respect to a comparative example to be compared later.

  In addition, in the figure which visualized the flow of exhaust gas using the analysis software of CFD shown in FIG.4, FIG6 and FIG.10, the flow velocity is represented by the color which changes continuously. That is, in the range from the smallest blue to the largest red, the flow velocity at each position in the exhaust silencer 2 is indicated by a color that changes continuously or in a plurality of stages like a light spectrum. However, since the drawings attached to the present application are monochrome, these colors are not expressed, and only the brightness of each color is displayed.

[Second Embodiment]
An exhaust silencer 2a according to a second embodiment of the present invention will be described with reference to FIG. 6 corresponding to FIG. 4 of the first embodiment.
In the first embodiment described above, the upper part of the inner surface of the exhaust silencer 2 and the side opposite to the side where the exhaust outlet 10 is provided are corners of the rectangular parallelepiped package 7. Such a shape is effective for obtaining a strong effect of the expansion silencer because the cross-sectional area of the fluid flow path inside the exhaust silencer 2 changes, and is suitable when the gas turbine original sound is large.

  In FIG. 6, the figure which visualized the flow of the exhaust_gas | exhaustion in the exhaust silencer 2a of 2nd Embodiment is shown. In the second embodiment, the guide part 18 having a curved surface (R shape) is provided on the inner surface of the package 7a of the exhaust silencer 2a on the side opposite to the side where the exhaust outlet 10 is provided. Yes. The second embodiment is more effective when fluid noise becomes a problem.

[Third Embodiment]
The exhaust silencer 2b of the third embodiment will be described with reference to FIGS.
As shown in FIG. 7, in the third embodiment, the structure in which the exhaust introduction port 8 for introducing the exhaust of the gas turbine 1 from the outside lateral direction is provided in the lower part of the side surface of the package 7b of the exhaust silencer 2b is the first implementation. The form is the same. On the other hand, the exhaust discharge port 10 is provided at the upper portion of the side surface on the same side surface as the side surface on which the exhaust introduction port 8 is provided.

  FIG. 8 is a diagram in which the magnitude of the energy of the exhaust noise in the exhaust silencer 2 of the present embodiment is analyzed and visualized by the CFD method. In this analysis, sound (fluid noise) generated between the exhaust inlet 8 and the exhaust outlet 10 (including the exhaust hood 11 and the exhaust duct) of the exhaust silencer 2b is evaluated by simulation. Does not contain the components of the original gas turbine sound. According to this example, the noise level in the vicinity of the outlet of the exhaust hood 11 (B in the figure) is about 85 dB, and a noise reduction effect of 10 dB was obtained compared to the comparative example to be compared later.

  Further, according to the present embodiment, since the exhaust introduction port 8 and the exhaust discharge port 10 are provided on the same side surface of the package 7b, the length in the direction in which the exhaust introduction port 8 and the exhaust discharge port 10 protrude from the package 7b. However, since it is smaller than the case of 1st Embodiment and 2nd Embodiment, installation space may be smaller than these.

[Comparative example]
Although the first to third embodiments have been described above, an example of an exhaust silencer that does not have the characteristics of each of the embodiments will be referred to as a “comparative example” and described below.
FIG. 9 is a partially broken perspective view of the exhaust silencer 20 of the comparative example. In this comparative example, the inner shape of the package 27 of the exhaust silencer 20 does not include the upper inner convex portion 12 and the lower inner convex portion 13 as in the above embodiments, and is the same as the outer surface of the packages 7, 7a, 7b. The inner surface of the rectangular parallelepiped is not flat and has a flat inner surface shape. A splitter 21 provided with a sound absorbing material is attached in the flue inside the package 7 in order to further exhibit the sound absorbing effect of the sound absorbing material against the noise from the gas turbine 1. The splitter 21 is composed of a plurality of flat plates, and each flat plate is attached between a pair of side surfaces of the package 27 so as to be parallel to the longitudinal direction (vertical direction in the figure) of the package 27 at equal intervals. Yes.

In FIG. 10, the figure which visualized the flow of the exhaust_gas | exhaustion in a comparative example by the method of CFD is shown.
As shown in FIG. 10, in the flue 70 of the exhaust silencer 20 of the comparative example, most of the exhaust gas flows only on the right side in the figure, and this part of the flow is the same as the flow on the left side of the flue 70 in the figure. In comparison, both the flow velocity and the flow velocity difference are large, and the generation of fluid noise is large. Such a state with unevenness in the flow of exhaust has a clear difference from these when compared with a state with little unevenness as in the first embodiment shown in FIG. 4 and the second embodiment shown in FIG. Will be easily understood.

  As shown in FIG. 10, even in the bent portion 80 above the flue 70, due to the inertial force of the exhaust flow, the exhaust flow cannot be smoothly bent and a speed difference is generated. The occurrence is large.

  As described above, in the comparative example, the exhaust flow has a low tendency for uniformity and uniformity as a whole, has various directional components, and reaches the exhaust outlet 90 with a large speed difference. There is noise. While these fluid noises are generated inside the package, the flow of exhaust gas entering the exhaust hood 11 is not rectified as shown in FIG. Fluid noise is also generated in the vicinity of the exhaust hood 11, which is considered to be a major cause of noise.

  FIG. 11 is a diagram in which the magnitude of the energy of exhaust noise in the comparative example is visualized by analysis using the CFD technique. In FIG. 5 of the first embodiment, the energy rapidly decreases in the process from the exhaust inlet 8 to the exhaust outlet 10, whereas in FIG. 11 of the comparative example, the energy distribution in the package is not uniform. Even in the vicinity of the exhaust outlet 90, there is a region where the energy is large, which is a noise source. Specifically, in the comparative example, the noise level in the vicinity of the outlet of the exhaust duct 11 (C in the figure) is about 95 dB, which is about 10 dB larger than each embodiment.

  FIG. 12 is a visualization diagram by CFD used for examining the noise generation mechanism and the noise generation position in the exhaust silencer 20 of the comparative example. FIG. 12 (a) visualizes the exhaust flow velocity in the upper part of the exhaust silencer 20 package, the exhaust outlet 90, the exhaust duct 11, and the vicinity of the upper part of the exhaust duct 11. FIG. This is a visualization of the energy level of exhaust noise in a portion corresponding to 12 (a).

Comparing the two figures, it can be observed that the energy of the exhaust noise increases in the two regions S1 and S2 in which a large difference (velocity gradient) occurs in the flow velocity distribution.
That is, in FIG. 12A, in the region S1 indicated by a substantially circular broken line in the drawing, there is a particularly dark portion where the flow velocity is relatively large below, whereas a thin portion where the flow velocity is relatively small above this. There is. Further, in the region S2 indicated by a vertically long oval broken line in the drawing, there is a dark portion where the flow velocity is relatively large particularly at the right edge, whereas there is a thin portion where the flow velocity is relatively small on the left side.

  As shown in FIG. 12B, the energy of the exhaust noise is large in the region S1 and the region S2 where the velocity gradient is generated as described above. In particular, the region S2 is larger than the region S1, and a portion having a particularly large energy is vertically long at the right edge thereof (portion displayed in black in the drawing). This result can be interpreted that fluid noise is generated due to the flow of fluid when the flow velocity is high and there is a difference in flow velocity with respect to the surroundings.

  As described above with reference to FIG. 10, in the comparative example, the flow of exhaust gas is not rectified, and thus the flow velocity is nonuniform. As shown in FIG. 10, an exhaust band having a remarkably high flow velocity is formed along the inner wall of the package below the exhaust discharge port 90, and the fast exhaust band forms the exhaust discharge port 90 and the exhaust duct 11. It is connected to the outside world of the upper part of exhaust duct 11 via. The fluid noise generated in the vicinity of the outlet of the exhaust duct 11 is released to the outside as it is, so that it is considered that the noise increases.

[Comparison between the first embodiment and a comparative example]
In order to confirm the effect of the present embodiment, the exhaust silencer 2 according to the first embodiment and the exhaust silencer 20 according to the comparative example were actually prototyped. As for the size of the package, the depth in the exhaust inflow direction was 1200 mm, the width orthogonal to the depth was 1500 mm, and the height was 4000 mm. The exhaust passage width D in the first embodiment is 700 mm. A noise meter was installed at a position 1 m away from the opening surface of the exhaust hood 11 in the horizontal direction. An exhaust gas inlet of the gas turbine 1 was connected to the exhaust gas inlets 8 of the exhaust silencers 2 and 20, an operation test was performed under constant conditions, and an evaluation test was performed in which noise was measured with a noise meter.

FIG. 13 is a graph showing the measurement results of the noise described above.
In general, noise analysis (frequency analysis) is required to evaluate noise, but the frequency characteristics felt by human ears are equivalent, so octave that is a pitch that doubles the frequency ratio is required. If the sound pressure level is measured as a reference, it is suitable for the evaluation of noise felt by humans. In this comparison, with respect to the noise to be measured, the sound pressure for each band as shown in the vertical axis of FIG. 13 for each 1/3 octave band in the frequency range of the audible frequency as shown in the horizontal axis of FIG. Asked for the level. Note that the octave band is a frequency band that has a frequency ratio of 1 octave between the upper and lower limits around a certain frequency. The center frequency is called the octave band center frequency. What is divided into 1/3 is called 1/3 octave band.

  As shown in FIG. 13, in the exhaust silencer 2 of the first embodiment, the noise level was improved at almost all frequencies. A noise reduction effect of about 2 to 5 dB was obtained in the vicinity of 1000 to 2000 Hz corresponding to the region of the gas turbine original sound, and a noise reduction effect of about 10 dB was obtained in the vicinity of 400 Hz where the influence of fluid noise was large.

[Features of the present invention and effects of each embodiment]
In an exhaust silencer of a gas turbine, a sound absorbing material and an expansion chamber are conventionally used to reduce the gas turbine original sound generated from the gas turbine. As a noise source other than the gas turbine original sound, the inventor of the present application has found that fluid noise caused by the exhaust flow has a dominant influence on the noise level near the outlet of the silencer of the gas turbine. did. It was also discovered that fluid noise occurs not only when the fluid velocity is high, but also when the fluid velocity difference is locally generated.

  As a result of continual research based on these findings, the inventor of the present application has found that the exhaust flow has inertia, and therefore the flow noise can be reduced by smoothly bending the exhaust flow and reducing the flow velocity difference. It came to the knowledge that it was possible.

  In addition, since the inventor of the present application has a relatively small influence of inertia on the transmission of the original sound of the gas turbine, if the bend part by the inner surface of the right-angled box shape is intentionally provided, the sound absorbing effect by the sound absorbing material and the expansion The inventor has also reached the knowledge that the effect of muffing by the principle of the muffler can be increased.

  The present invention has been made on the basis of the discovery of the inventor of the present invention described above and the knowledge on the discovery, and according to the above-described embodiment that realizes this, the upper internal Protruding portions 12 can be provided to reduce fluid noise by suppressing the occurrence of turbulent flow near the exhaust outlet 10. Further, the flow of exhaust gas can be rectified by the inclined flow path 17 formed by the upper inner convex portion 12 and the lower inner convex portion 13 to reduce fluid noise. Furthermore, by inclining the inclined flow path 17 toward the side surface opposite to the side surface provided with the exhaust discharge port 10 in the package 7, the gas turbine 1 noise using the gas turbine 1 as a generation source The ratio that goes directly to the side can be reduced, and noise can be reduced.

  Furthermore, according to the embodiment, in the exhaust silencer 2 of the gas turbine 1 having the rectangular parallelepiped package 7 and receiving the exhaust from the lateral direction and exhausting the exhaust in the lateral direction, the height of the silencer is particularly high. In the case where there is a strong demand for reduction, there is a practically important effect that the exhaust silencer 2 can be both reduced in size and silenced.

  In the embodiment described above, the rectangular parallelepiped package 7 of the exhaust silencer 2 is arranged in a vertically long manner, but the same effect can be obtained even when the rectangular parallelepiped package 7 is arranged in a horizontally long manner. That is, the rectangular parallelepiped package 7 is arranged so that the longest side is parallel to the horizontal direction, and the exhaust silencer 2 is installed so that exhaust is introduced into the package 7 from the vertical direction and discharged from the vertical direction. However, the silencing effect equivalent to the embodiment can be obtained.

DESCRIPTION OF SYMBOLS 1 ... Gas turbine 2, 2a, 2b ... Exhaust silencer 7, 7a, 7b ... Package 8 ... Exhaust inlet 10 ... Exhaust outlet 12 ... Upper inner convex part 13 ... Lower inner convex part 14 ... Downward inclined surface 15 ... Upward inclined surface 17 ... Inclined flow path 20 ... Exhaust silencer of comparative example

Claims (7)

A silencer package with a rectangular parallelepiped shape and a sound absorbing material on the inner surface,
An exhaust inlet that is provided at a lower portion of the side surface of the package and introduces exhaust of the gas turbine from an external lateral direction;
An exhaust exhaust port provided at an upper portion of the side surface of the package and exhausting gas turbine exhaust in an external lateral direction;
An upper inner protrusion provided on the inner surface of the package directly below the exhaust outlet, the inner surface protruding in a chevron shape;
A lower inner convex portion that is provided at a position relatively lower than the upper inner convex portion on a side surface facing the side surface of the package provided with the upper inner convex portion, and the inner surface protrudes in a mountain shape. Gas turbine exhaust silencer provided. The upper inner convex portion has a downward inclined surface in which the direction of the perpendicular on the inner side of the package faces downward from the horizontal,
The lower inner convex portion has an upward inclined surface in which the direction of the vertical line on the inner side of the package faces upward from the horizontal,
The downward inclined surface and the upward inclined surface arranged substantially parallel to each other form an inclined flow path,
2. The exhaust silencer for a gas turbine according to claim 1, wherein the inclined flow path is inclined so as to approach a side surface opposed to a side surface provided with the exhaust outlet as it goes upward inside the package. .   The exhaust silencer for a gas turbine according to claim 2, wherein the exhaust passage width D in the inclined passage is in a range of λ / 2 to λ, where λ is the wavelength of the gas turbine original sound.   The exhaust silencer for a gas turbine according to any one of claims 1 to 3, wherein the exhaust discharge port is provided on a side surface facing a side surface on which the exhaust introduction port is provided.   The exhaust silencer for a gas turbine according to any one of claims 1 to 3, wherein the exhaust outlet is provided on a side surface provided with the exhaust inlet.   The exhaust silencer for a gas turbine according to any one of claims 1 to 5, wherein an exhaust guide path is connected to an opening of the exhaust exhaust port outside the package. A silencer package having a rectangular parallelepiped shape in which one of three sides orthogonal to each other is longer than the other two sides, and having a sound absorbing material on the inner surface;
An exhaust inlet that is provided near one end of the longitudinal direction on a side surface parallel to the longitudinal direction of the package, and that introduces exhaust of the gas turbine from the outside along a direction intersecting the side surface;
An exhaust outlet that is provided near the other end of the longitudinal direction on a side surface parallel to the longitudinal direction of the package, and exhausts the exhaust of the gas turbine to the outside along a direction intersecting the side surface;
An exhaust discharge port side inward convex portion provided at a position near the center of the package in the longitudinal direction adjacent to the exhaust discharge port on the inner surface of the package;
Provided at a position closer to the exhaust introduction port than the exhaust discharge port side inner convex portion on a side surface facing the side surface of the package provided with the exhaust discharge side inner convex portion, and a cross section on the inner surface is a mountain shape An exhaust silencer for a gas turbine, comprising: