JP5996657B2 - Gas turbine equipment - Google Patents

Description

Related applications

  This application claims the priority of Japanese Patent Application No. 2012-188346 filed on Aug. 29, 2012, and is incorporated herein by reference in its entirety.

  The present invention relates to a gas turbine apparatus that drives a power machine such as a generator by a gas turbine engine.

  A large amount of high-frequency noise is generated in the gas turbine apparatus, but this high-frequency noise can be effectively reduced by means such as packaging by an enclosure or installing an intake / exhaust silencer. On the other hand, it is difficult to effectively reduce the low frequency noise generated from the gas turbine apparatus. This point will be described below with reference to FIGS. 5 and 6.

  In the gas turbine apparatus, the flow velocity of exhaust gas discharged from the last stage rotor blade of the gas turbine engine is generally relatively high, about 300 to 400 m / sec. Therefore, this exhaust gas is led to a long exhaust diffuser DF to reduce the flow velocity. Thus, the dynamic pressure of the exhaust gas is reduced to recover the static pressure, thereby improving the performance. The exhaust diffuser DF includes an inner pipe 28 shown in FIGS. 5 and 6 and an outer pipe (not shown) arranged so as to cover the outer periphery of the inner pipe 28. An exhaust gas passage for introducing the exhaust gas discharged from the final stage moving blade is formed.

  Further, a plurality of exhaust struts 31 for holding the inner pipe 28 and supplying lubricating oil are disposed in the exhaust gas passage in the circumferential direction (see Patent Document 1). The exhaust strut 31 has a flat shape with an elliptical cross section, and is arranged so that its long axis faces the axial direction C of the exhaust diffuser DF, and is set so as not to have a large flow resistance against the exhaust gas. Yes.

  By the way, in a normal gas turbine engine, in order to improve the performance of the exhaust diffuser DF, it is designed to have a flow in the axial direction C during rated operation (full load operation). That is, during rated operation, as shown in FIG. 5, an exhaust gas absolute flow (true flow) vector obtained by combining the turbine rotation direction vector V1 and the exhaust gas relative flow velocity vector V2 from the turbine final stage rotor blade. V is a direction substantially along the axial direction C. The exhaust gas flow S <b> 1 at this time is one in which vortices generated in the downstream portion of the exhaust strut 31 in the flow direction of the exhaust gas are suppressed.

  On the other hand, when the gas turbine engine is operated at a low load, in particular, a no-load operation, when the power machine is a generator and the gas turbine engine is always driven at the same rotational speed, as shown in FIG. Although it becomes the same thing at the time of rated operation, the relative flow velocity vector V2 of the exhaust gas from the last stage rotor blade becomes shorter as the flow velocity of the exhaust gas becomes slower. Therefore, the exhaust gas absolute flow vector V, which is a combination of the turbine rotation direction vector V1 and the exhaust gas relative flow velocity vector V2, is inclined at a large angle with respect to the axial direction C, and the exhaust gas becomes a swirling flow. It flows in the gas passage. Due to the inclined exhaust gas flow S2, a strong vortex Vr is generated in the downstream portion of the exhaust strut 31 in the flow direction of the exhaust gas.

  When the strong vortex Vr generated in this manner flows downstream while riding on the swirling flow of exhaust gas and breaks due to self-excited vibration or separation, low-frequency noise or low-frequency vibration called vortex whistle is generated. The frequency of the vortex whistle is proportional to the flow rate or swirl speed of the exhaust gas and does not depend on the axial length of the exhaust diffuser.

JP 2011-226651 A

  Low-frequency noise and low-frequency vibration called vortex whistle are generated during low-load operation of the gas turbine engine as described above. In recent years, the number of exhaust struts 31 has been reduced for the purpose of reducing exhaust pressure loss. Because of that. For example, in the past, about 8 to 10 exhaust struts 31 were installed, but as shown in FIGS. 4 and 5, the number of exhaust struts 31 tends to be reduced to 4 to 6 arranged at equal intervals in the circumferential direction. When the number of exhaust struts 31 is reduced in this manner, the exhaust gas swirl flows as it is between the two adjacent exhaust struts 31 at large intervals, and the exhaust gas flow swirls with strong vortices. S2. Therefore, if the number of exhaust struts 31 is increased as in the prior art, the exhaust struts 31 can suppress the exhaust gas from turning to some extent, but on the other hand, the pressure loss of the exhaust gas increases.

  Therefore, an object of the present invention is to provide a gas turbine device that can effectively suppress low-frequency noise and low-frequency vibration during low-load operation without causing an increase in exhaust gas pressure loss. .

  In order to achieve the above object, a gas turbine apparatus according to the present invention includes a gas turbine engine including an exhaust diffuser that forms an upstream portion of an exhaust gas passage, an exhaust strut provided in the exhaust diffuser, and the exhaust gas. A swivel restraining plate that is disposed on the downstream side of the exhaust strut in the passage and extends in the axial direction.

  In particular, when the number of exhaust struts is set to be small, a swirling flow of exhaust gas is generated during low load operation of the gas turbine engine. This swirling flow of exhaust gas flows downstream between two adjacent exhaust struts at a large interval, and then swirls against the swirl restraining plate extending along the axial direction on the downstream side of the exhaust struts. Forced change to axial flow. Therefore, although the exhaust gas vortex generated in the downstream part of the exhaust strut cannot be suppressed, the swirl flow of the exhaust gas flowing downstream can be suppressed. (Swirl around the vortex core) is eliminated, and the generation of low-frequency noise and low-frequency vibration, called vortex whistles, is effectively prevented by suppressing the occurrence of vortex self-excited vibration and separation. can do. Further, since the swirl prevention plate is disposed on the downstream side of the exhaust strut where the flow rate of the exhaust gas becomes low, the pressure loss of the exhaust gas can be further reduced from this point.

  In the present invention, preferably, the exhaust strut is provided with a plurality of exhaust struts spaced apart from each other in the circumferential direction, and the turning restraining plate is disposed at an intermediate position between two adjacent exhaust struts. As a result, the swirl flow of the exhaust gas passing between two adjacent exhaust struts can be effectively deflected by the swirl suppression plate, and the swirl can be suppressed.

  It is preferable that an axial length of the swirl prevention plate is larger than an axial length of the exhaust strut. In particular, it is preferable that the axial length of the turning restraining plate is 2 to 4 times the axial length of the exhaust strut. Accordingly, the exhaust strut can be shortened to reduce the pressure loss of the exhaust gas, while the swirl of the exhaust gas can be effectively suppressed by the long swirl suppression plate.

  Preferably, 4-6 said exhaust struts spaced apart in the circumferential direction are provided. By reducing the number of exhaust struts in this way, the resistance of the exhaust gas passage is reduced and exhaust pressure loss is reduced.

In a preferred embodiment of the present invention, the exhaust diffuser has a cylindrical inner case and an outer case arranged concentrically, and the two cases are connected by the exhaust strut. Thereby, a diffuser with a strong structure can be obtained.

  In a preferred embodiment of the present invention, the exhaust duct further includes an exhaust duct connected to a downstream side of the exhaust diffuser, the exhaust duct having an inner pipe and an outer pipe arranged concentrically, A turning restraining plate is attached, and a gap exists between the outer pipe and the turning restraining plate at least when the temperature is cold. As a result, the swirl prevention plate is supported by the inner pipe in a cantilevered manner, so that both the inner pipe and the outer pipe are supported as if both ends of the swirl restraint plate are supported by being supported by the inner pipe and the outer pipe. No thermal distortion of the swirl prevention plate due to the thermal elongation of

  When attaching the turning restraining plate to the inner pipe, the turning restraining plate is formed by superposing two pairs of plate members, and the attachment portions at the inner diameter ends of the respective plate members are curved in a direction away from each other. It is preferable that it is attached to the inner pipe. As a result, since the turning restraining plate can be a sheet metal processed thin plate, the pressure loss of the exhaust gas is less than that of the exhaust strut. In addition, the rotation restraining plate has a simple structure in which two plate members are superposed, but has sufficient strength and can suppress an increase in weight and cost. Further, when thermal distortion occurs in the turning restraining plate, the curved mounting portion is thermally deformed to absorb the above-described thermal strain, and an increase in the radial dimension of the turning restraining plate can be suppressed.

  Any combination of at least two configurations disclosed in the claims and / or the specification and / or drawings is included in the present invention. In particular, any combination of two or more of each claim in the claims is included in the present invention.

The present invention will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are for illustration and description only and should not be used to define the scope of the present invention. The scope of the invention is defined by the appended claims. In the accompanying drawings, the same part numbers in a plurality of drawings indicate the same or corresponding parts.
It is a side view showing the whole gas turbine device composition concerning one embodiment of the present invention. It is a longitudinal cross-sectional view which shows the gas turbine engine and exhaust diffuser of a gas turbine apparatus same as the above. It is a rear view which shows an exhaust diffuser same as the above. It is a perspective view which shows the flow of the exhaust gas in the same embodiment. It is a perspective view which shows the flow of the exhaust gas at the time of the rated operation of a gas turbine engine. It is a perspective view which shows the flow of the exhaust gas at the time of the low load operation | movement of a gas turbine engine.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In FIG. 1, a heavy weight reduction gear 12 is fixed to a base 13, and a gas turbine engine GT is cantilevered via a plurality of (four in this embodiment) stays 14 on this reduction gear 12. It is supported by. The rotating shaft 10 of the gas turbine engine GT is connected to the connecting shaft on the input side of the speed reducer 12, and the connecting shaft 17 on the output side is coupled to the drive shaft 18 of the generator 11 that is a load of the gas turbine engine GT. Are connected by Exhaust gas EG discharged almost horizontally from the gas turbine engine GT enters the exhaust chamber 22 through the exhaust diffuser 20 and the exhaust duct 21, where it is deflected substantially vertically and enters the upper silencer 24. The sound is muted at 24 and discharged to the outside. A guide plate 23 that deflects the exhaust gas EG upward is disposed in the exhaust chamber 22.

  As shown in FIG. 2, the gas turbine engine GT includes a two-stage centrifugal compressor 1 that sucks and compresses air A from an air inlet IN, and a combustor that supplies fuel to the compressed air A and burns it. 4 and a turbine 7 driven by the combustion gas G. The compressor 1 and the turbine 7 are accommodated in a housing 15, and the combustor 4 is attached to the housing 15 so as to protrude upward. The combustion gas G generated in the combustion chamber 5 in the combustor 4 is guided to the turbine 7 through the scroll 9 to rotate the turbine 7, and the two-stage centrifugal compression connected to the turbine 7 by the rotating shaft 10. The generator 1 is driven via the machine 1 and the speed reducer 12 of FIG.

  The exhaust gas EG discharged from the final stage moving blade 27 of the turbine 7 is guided to the annular exhaust gas passage 30 between the inner case 20a and the outer case 20b of the exhaust diffuser 20. The outer case 20b is fixed to the housing 15, and the inner case 20a is supported on the outer case 20b via four exhaust struts 31 that are spaced apart from each other in the circumferential direction and arranged radially at 90 ° intervals. . In this way, the cylindrical inner case 20a and the cylindrical outer case 20b arranged concentrically with each other are connected by the exhaust strut 31, so that the diffuser 20 having a strong structure is configured.

  The exhaust duct 21 connected to the downstream end of the exhaust diffuser 20 is attached with a turning restraining plate 32 formed in a rectangular thin plate shape and extending along the axial direction C by a fastening member 33 such as a bolt and a nut. Yes. The exhaust duct 21 forms an exhaust gas passage 30 between the inner pipe 21a and the outer pipe 21b. Thus, the exhaust diffuser 20 forms the upstream portion of the annular exhaust gas passage 30, the exhaust duct 21 forms the downstream portion of the annular exhaust gas passage 30, and the exhaust chamber 22 and the silencer 24 of FIG. An exhaust gas passage 30 </ b> A having a substantially rectangular cross section connected downstream of the gas passage 30 is formed.

  The upstream portion 21ba facing the turning suppression plate 32 in the outer pipe 21b shown in FIG. 2 is provided so as to be relatively movable in the axial direction C by the thermal expansion absorption mechanism 34 with respect to the downstream portion 21bb. The thermal expansion absorbing mechanism 34 includes a bellows-like expansion / contraction cylinder 37 that can expand and contract in the axial direction C, and an adjustment bolt 38 that limits the expansion / contraction length of the upstream portion 21ba. The thermal expansion absorbing mechanism 34 absorbs thermal expansion caused by the exhaust gas EG in the outer pipe 21b.

  FIG. 3 is a rear view of the exhaust diffuser 20 viewed from the right side (rear) of FIG. The turning restraining plates 32 are arranged radially at two adjacent intermediate positions of the four exhaust struts 31 arranged at equal intervals of 90 ° in the circumferential direction, and are attached to the inner pipe 21a by fastening members 33. Each swirl prevention plate 32 includes a pair of plate members 39 and 40 that are symmetrical with respect to the center plane passing through the axis of the exhaust gas passage 30. That is, in the turning restraining plate 32, the restraining plate portions 39a, 40a of the plate members 39, 40 are superimposed in close contact with each other, and the mounting portions 39b, 40b at the inner diameter ends of the plate members 39, 40 are separated from each other. And is attached to the inner pipe 21a by the fastening member 33.

  The fastening members 33 are arranged at two locations spaced apart in the axial direction C on the turning restraining plate 32. A slight gap exists between the radially outer end of the turning restraining plate 32 and the inner surface of the outer pipe 21b at least in a cold state when the engine is stopped. Therefore, the turning restraining plate 32 is cantilevered by the inner pipe 21a.

  In the gas turbine apparatus having the above configuration, the number of exhaust struts 31 is set as small as four, so that exhaust pressure loss due to passage resistance is suppressed. On the other hand, as shown in FIG. A swirl flow TS of the exhaust gas EG is generated during operation. This swirl flow TS hits the swirl suppression plate 32 on the downstream side of the exhaust strut 31 and is prevented from swirling, and is forcedly deflected into the flow S in the axial direction C. Therefore, although the generation of the vortex of the exhaust gas GT on the downstream side of the exhaust strut 31 cannot be completely suppressed, the swirl flow TS of the exhaust gas EG that flows the vortex on the downstream side can be suppressed. Instability (swirl of the vortex core) is eliminated, suppressing the generation of vortex self-excited vibration, effectively preventing the generation of low-frequency noise and low-frequency vibration, which is called vortex whistle. be able to.

  The above-mentioned vortex whistle often records a peak value at several tens of Hz, but according to the actual measurement results, it was confirmed that the peak value was reduced by 10 dB or more when the rotation suppression plate 32 was provided. As a result, it has been found that low frequency noise and low frequency vibration can be effectively prevented with a simple configuration in which only the turning suppression plate 32 is provided.

  However, in order to obtain the effect of suppressing the occurrence of such low-frequency noise and low-frequency vibration, the length L2 in the axial direction C of the turning restraint plate 32 is made longer than the length L1 in the axial direction C of the exhaust strut 31. It is good to do. In particular, the length L2 in the axial direction C of the turning restraining plate 32 is preferably set to 2 to 4 times the length L1 of the exhaust strut 31 in the axial direction C. If it is less than 2 times, the deflection effect by the turning restraining plate 32 becomes insufficient, and if it exceeds 4 times, the friction loss of the exhaust gas EG by the turning restraining plate 32 becomes excessive. The exhaust strut 31 is a strength member for connecting the inner case 20a and the outer case 20b, and its radial length (height) H1 is 1.0 to 2.0 times the axial length L1. Degree.

  In addition, the swirl prevention plate 32 can be formed by sheet metal processing, whereas the exhaust strut 31 is generally manufactured by casting, so that the thickness is reduced and the pressure loss of the exhaust gas EG is significantly higher than that of the exhaust strut 31. While reducing, increase in weight and cost can be suppressed. In addition, since the swirl prevention plate 32 is disposed on the downstream side of the exhaust strut 31 where the flow rate of the exhaust gas EG becomes low, the pressure loss of the exhaust gas EG can be further reduced from this point.

  Furthermore, since the turning restraining plate 32 is attached in a superposed state to each other as a pair of plate members 39, 40 shown in FIG. 3, it has a sufficient strength despite being a thin plate, When thermal distortion due to high-temperature exhaust gas EG occurs in the turning restraining plate 32, the curved mounting portions 39b, 40b of the plate members 39, 40 are thermally deformed to absorb the above-described thermal strain, thereby turning the turning restraining plate. The 32 radial dimensions can be kept substantially constant. Further, since the turning restraining plate 32 is supported by the inner pipe 21a in a cantilevered manner, the inner pipe 21a and the outer pipe as in the case where the both ends are suspended and supported by the inner pipe 21a and the outer pipe 21b are supported. The thermal distortion resulting from the thermal elongation of both of 21b does not occur.

  In addition, although the case where the rotation suppression plate 32 is supported by the inner pipe 21a in a cantilever manner is illustrated in the above embodiment, the present invention is not limited thereto, and the rotation suppression plate 32 is supported by the outer pipe 21b in a cantilever manner. Even in the configuration, the same effect as the embodiment can be obtained.

  The present invention is not limited to the above-described embodiment, and various additions, modifications, or deletions are possible within the scope not departing from the gist of the present invention, and such modifications are also included in the scope of the present invention.

  As described above, the preferred embodiments have been described with reference to the drawings. However, those skilled in the art will readily understand various changes and modifications within the obvious scope by looking at the present specification. Accordingly, such changes and modifications are to be construed as within the scope of the present invention as defined by the appended claims.

20 Exhaust diffuser 20a Inner case 20b Outer case 30 Exhaust gas passage 31 Exhaust strut 32 Swing suppression plate GT Gas turbine engine C Axial direction

Claims (7)

A gas turbine engine having an exhaust diffuser forming an upstream portion of the exhaust gas passage;
Wherein provided in the exhaust de-Fyn over THE, a plurality of exhaust struts circumferentially spaced,
A swirl restraining plate that is disposed downstream of the exhaust strut in the exhaust gas passage and extends along the axial direction;
Equipped with a,
A gas turbine apparatus in which the swirl prevention plate is disposed at a circumferential position between two adjacent exhaust struts . The gas turbine apparatus according to claim 1 , wherein an axial length of the swirl prevention plate is larger than an axial length of the exhaust strut. The gas turbine apparatus according to claim 2 , wherein an axial length of the swirl prevention plate is 2 to 4 times an axial length of the exhaust strut. The gas turbine device according to any one of claims 1 to 3 , comprising 4 to 6 exhaust struts spaced apart in a circumferential direction. In the gas turbine apparatus according to any one of claims 1 to 4, wherein the exhaust diffuser includes an inner case and outer case are arranged concentrically, said between both cases are connected by the exhaust strut Gas turbine equipment. The gas turbine apparatus according to any one of claims 1 to 5 , further comprising:
An exhaust duct connected downstream of the exhaust diffuser,
The exhaust duct has an inner pipe and an outer pipe arranged concentrically,
The gas turbine device, wherein the turning restraining plate is attached to the inner pipe, and a gap exists between the outer pipe and the turning restraining plate at least when the temperature is cold. A gas turbine engine having an exhaust diffuser forming an upstream portion of the exhaust gas passage;
An exhaust strut provided in the exhaust diffuser;
A swirl restraining plate that is disposed downstream of the exhaust strut in the exhaust gas passage and extends along the axial direction;
An exhaust duct connected downstream of the exhaust diffuser;
With
The exhaust duct has an inner pipe and an outer pipe arranged concentrically,
The swivel suppression plate is attached to the inner pipe, and a gap is formed at least during cold temperatures between the outer pipe and the swirl suppression plate,
A gas turbine apparatus in which the swirl prevention plate is formed by superposing two pairs of plate members, and attached to the inner pipe in a state in which attachment portions at inner diameter ends of the plate members are curved away from each other.

Images