JP5618879B2 - Axial exhaust turbine - Google Patents

Description

  Embodiments of the present invention relate to an axial exhaust turbine.

Improving the thermal efficiency of steam turbines used in thermal power plants and the like is an important issue that leads to effective use of energy resources and reduction of carbon dioxide (CO ₂ ) emissions.

  An improvement in the thermal efficiency of a steam turbine can be achieved by effectively converting the given energy into mechanical work, which requires reducing various internal losses.

  The internal loss of a steam turbine is typified by a turbine blade row loss based on profile loss due to blade shape, steam secondary flow loss, steam leakage loss, steam wetting loss, steam valves, and crossover pipes. There are passage portion loss in passages other than the blade row, turbine exhaust loss due to the turbine exhaust chamber, and the like.

  Among these losses, the turbine exhaust loss is a large loss that accounts for 10 to 20% of the total internal loss. The turbine exhaust loss is a loss that occurs between the final stage outlet and the condenser inlet, and is further classified into a leaving loss, a hood loss, a turn-up loss, and the like. Among these, the hood loss is a pressure loss due to the steam passing through the exhaust chamber, and depends on the axial flow velocity of the steam, that is, the volume flow rate passing through the exhaust chamber. Therefore, the hood loss depends on the type, shape, and size of the exhaust chamber including the diffuser.

  In general, the pressure loss increases in proportion to the square of the steam flow velocity. Therefore, it is effective to reduce the steam flow velocity by increasing the size of the exhaust chamber within an allowable range. However, when the size of the exhaust chamber is increased, there are restrictions from the manufacturing cost and the layout space of the building. Such restrictions are also imposed when the size of the exhaust chamber is increased in order to reduce the hood loss. Therefore, it is important to have a shape with a small pressure loss with a limited exhaust chamber size.

  In the low-pressure exhaust chamber of an axial exhaust turbine used when the condenser is placed at the same height as the steam turbine, the steam that has passed through the rotor blades of the final turbine stage is an annulus having an inner pipe and an outer pipe. The flow velocity is reduced by the diffuser, which is an enlarged flow path of, and exhausted from the exhaust chamber while recovering the static pressure and led to the condenser.

  In order to reduce the pressure loss in the exhaust chamber, it is necessary to sufficiently reduce the steam speed and restore the static pressure in the diffuser. For this purpose, it is necessary to increase the area ratio of the diffuser (the cross-sectional area at the diffuser outlet / the cross-sectional area at the final turbine stage outlet) as much as possible. However, if the flow path in the diffuser is a sudden expansion flow path, the flow of steam is separated, and effective static pressure recovery is prevented. Therefore, there are optimum conditions for the expansion ratio of the diffuser and the channel shape.

  Generally, the pressure inside the low-pressure exhaust chamber is equal to or lower than atmospheric pressure in the operating state. Therefore, in order to prevent the deformation of the flow path component due to the pressure difference from the atmospheric pressure, and to hold the turbine rotor and bearings in the axial exhaust chamber, pipes and ribs are installed inside and outside the exhaust chamber. Internal structures are installed. Since these internal structures are also installed in the steam flow path, pressure loss occurs. Therefore, studies have been made to reduce pressure loss due to internal structures.

JP-A-2005-290985

  The internal structure described above is arranged symmetrically or asymmetrically in a vertical direction or a horizontal direction perpendicular to the turbine rotor axial direction. That is, they are arranged symmetrically or asymmetrically in the radial direction perpendicular to the turbine rotor axial direction. In the cross section of the flow path of the exhaust chamber, there may be a region where the internal structures are densely or sparsely arranged. Therefore, a steam speed difference, that is, a speed distribution occurs in the flow path cross section at the same position in the axial direction of the turbine rotor. As a result, the flow field is disturbed, and sufficient pressure recovery cannot be performed in the exhaust chamber.

  The problem to be solved by the present invention is to provide an axial exhaust turbine capable of reducing pressure loss in an exhaust chamber.

In the axial exhaust turbine of the embodiment, the flow path cross-sectional area is downstream between the inner wall portion arranged in the turbine rotor axial direction around the turbine rotor and the outer wall portion arranged on the outer periphery of the inner wall portion. An exhaust chamber having an exhaust passage configured to exhaust the working fluid in the axial direction of the turbine rotor is formed so as to gradually increase. An internal structure exists in the exhaust flow path through which the working fluid in the exhaust chamber passes. In this axial exhaust turbine, the inner diameter of the outer wall portion is different between the upper half side and the lower half side on the downstream side from the portion where the internal structure exists.

It is a figure showing the meridional section of the perpendicular direction of the axial flow exhaust turbine of a 1st embodiment concerning the present invention. It is a figure which shows typically the meridional section of the vertical direction of the exhaust chamber in the axial flow exhaust turbine of 1st Embodiment which concerns on this invention. It is a figure which shows typically the AA cross section of FIG. 2 which showed the axial-flow exhaust turbine of 1st Embodiment which concerns on this invention. It is a top view when the exhaust chamber in the axial flow exhaust turbine of the first embodiment according to the present invention is viewed from above. The flow path cross-sectional area A1 of the upper half-side exhaust flow passage excluding the portion blocked by the internal structure 53 and the flow passage cross-sectional area A2 of the lower half-side exhaust flow flow passage excluding the portion blocked by the internal structure 53 It is a figure which shows the relationship between the value ((A1-A2) / A1) which divided the cross-sectional area difference (A1-A2) by flow-path cross-sectional area A1, and a performance fall rate. It is a figure which shows typically an example by which the internal structure was equally arrange | positioned in the predetermined flow-path cross section of the exhaust chamber in the axial flow exhaust turbine of 1st Embodiment which concerns on this invention. It is a figure which shows typically an example in which the internal structure was unevenly arrange | positioned in the predetermined flow-path cross section of the exhaust chamber in the axial flow exhaust turbine of 1st Embodiment which concerns on this invention. It is a figure which shows typically the meridional section of the orthogonal | vertical direction of the exhaust chamber of the other structure in the axial flow exhaust turbine of 1st Embodiment which concerns on this invention. It is a figure which shows typically the cross section equivalent to the AA cross section of FIG. 2 which showed the shape of the different exhaust chamber in the axial flow exhaust turbine of 1st Embodiment which concerns on this invention. It is a figure which shows typically the cross section equivalent to the AA cross section of FIG. 2 which showed the shape of the different exhaust chamber in the axial flow exhaust turbine of 1st Embodiment which concerns on this invention. It is a figure which shows typically the meridional section of the horizontal direction of the exhaust chamber in the axial flow exhaust turbine of 2nd Embodiment which concerns on this invention. It is a figure which shows typically the BB cross section of FIG. 11 by which the axial-flow exhaust turbine of 2nd Embodiment which concerns on this invention was shown. It is a figure which shows typically the meridional section of the orthogonal | vertical direction of the exhaust chamber in the axial flow exhaust turbine of 3rd Embodiment which concerns on this invention. It is a figure which shows typically the CC cross section of FIG. 13 by which the axial-flow exhaust turbine of 3rd Embodiment concerning this invention was shown. It is a figure which shows typically the meridional section of the horizontal direction of the exhaust chamber in the axial flow exhaust turbine of 4th Embodiment which concerns on this invention. It is a figure which shows typically the DD cross section of FIG. 15 by which the axial-flow exhaust turbine of 4th Embodiment which concerns on this invention was shown.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a diagram showing a meridional section in a vertical direction of an axial exhaust turbine 10 according to a first embodiment of the present invention. Here, a steam turbine will be described as an example of the axial exhaust turbine 10. In the following description, the same components are denoted by the same reference numerals, and redundant description is omitted or simplified.

  As shown in FIG. 1, the axial exhaust turbine 10 includes a casing 20, and a turbine rotor 22 in which a moving blade 21 is implanted is provided in the casing 20. A plurality of rotor blades 21 are implanted in the circumferential direction to constitute a rotor blade cascade, and the rotor blade cascade is provided in a plurality of stages in the turbine rotor axial direction. The turbine rotor 22 is rotatably supported by a rotor bearing (not shown).

  A nozzle 24 supported by diaphragms 23a and 23b is disposed on the inner periphery of the casing 20 so as to alternate with the moving blades 21 in the turbine rotor axial direction. A plurality of nozzles 24 are implanted in the circumferential direction to form a nozzle blade row, and the nozzle blade row and the moving blade blade row located on the downstream side constitute one turbine stage.

  A ground seal portion 25 is provided between the turbine rotor 22 and the casing 20 in order to prevent leakage of steam, which is a working fluid, to the outside.

  In the axial exhaust turbine 10, a steam inlet pipe 26 for introducing steam into the inside is provided through the casing 20.

  On the downstream side of the final turbine stage, there is provided an exhaust chamber 30 for exhausting steam that has expanded in the turbine stage. The exhaust chamber 30 has a flow passage cross-sectional area in the downstream direction between an inner wall portion 31 disposed in the turbine rotor axial direction around the turbine rotor 22 and an outer wall portion 32 disposed on the outer periphery of the inner wall portion 31. The exhaust passage 33 is formed to exhaust the working fluid in the axial direction of the turbine rotor. The exhaust passage 33 is a so-called diffuser. Further, the exhaust passage 33 is formed in an annular cross section. As shown in FIG. 1, the outlet 34 of the exhaust passage 33 is an exhaust passage having a circular cross section that is covered with the outer wall portion 32 without the inner wall portion 31 or the like at the center.

  Moreover, the inner wall part 31 and the outer wall part 32 which comprise the exhaust chamber 30 are comprised by the vertically divided structure. Here, the upper side is referred to as the upper half side, and the lower side is referred to as the lower half side.

  Although not shown, the outlet 34 of the exhaust passage 33 is provided with a condenser (not shown) arranged at the same height as the axial exhaust turbine 10, for example. Although not shown, a rotor bearing that rotatably supports the turbine rotor 22, a bearing base that houses the rotor bearing, and a bearing base cover that is provided around the bearing base are provided in the inner wall portion 31. In addition, a ground seal part (not shown) is provided in the inner wall part 31 in order to prevent leakage of air and oil mist filled in the bearing stand on the exhaust flow path 33 side.

  As shown in FIG. 1, for example, a pipe 50 for supplying steam to a ground seal part (not shown) and an internal space of the above-described bearing stand (not shown) are opened to the atmosphere side in the exhaust passage 33. There is an internal structure 53 including a pressure equalizing tube 51 for supporting the inner wall 31 and a support member 52 for supporting the inner wall portion 31 and the like.

  Here, the operation of the axial exhaust turbine 10 will be described.

  The steam flowing into the axial exhaust turbine 10 through the steam inlet pipe 26 passes through the steam flow path including the nozzle 24 and the moving blade 21 of each turbine stage while performing expansion work, and rotates the turbine rotor 22. The steam that has expanded is reduced in flow velocity, passes through the exhaust passage 33 of the exhaust chamber 30 while recovering the static pressure, and is guided to a condenser (not shown).

  Next, the configuration of the exhaust chamber 30 will be described in detail.

  FIG. 2 is a diagram schematically showing a meridional section in the vertical direction of the exhaust chamber 30 in the axial exhaust turbine 10 according to the first embodiment of the present invention. FIG. 3 is a diagram schematically showing an AA cross section of FIG. 2. In FIGS. 2 and 3, a cross section is shown with a part of the configuration omitted. FIG. 4 is a plan view of the exhaust chamber 30 in the axial exhaust turbine 10 according to the first embodiment of the present invention as viewed from above. In FIG. 4, in order to clearly show the shape of the inner wall of the upper half side outer wall part 32a and the lower half side outer wall part 32b in the turbine rotor axial direction, the inner wall of the upper half side outer wall part 32a and the lower half side outer wall part 32b is shown. Only the outline is shown.

  As shown in FIGS. 2 and 3, the internal structure 53 exists in the exhaust flow path 33 on the lower half side of the exhaust chamber 30. Further, as shown in FIG. 3, in the cross section perpendicular to the turbine rotor axial direction in the exhaust flow path 33 where the internal structure 53 exists, the vertical center line L intersecting the central axis of the turbine rotor in this cross section. The internal structure 53 is provided symmetrically on the left half side and the right half side with respect to the axis of symmetry. Here, the left half side indicates the left side of the center line L in the cross section, and the right half side indicates the right side of the center line L in the cross section.

  Here, an example in which the internal structure 53 does not exist in the upper half exhaust flow path 33 is shown. However, for example, the internal structure 53 may exist in the upper half exhaust flow path 33. In addition, the flow path cross-sectional area blocked by the internal structure 53 is generally larger on the lower half side than on the upper half side, but may be configured such that the upper half side is larger than the lower half side. Here, the upper half side exhaust flow path 33 is referred to as an upper half side exhaust flow path 33a, and the lower half side exhaust flow path 33 is referred to as a lower half side exhaust flow path 33b.

  As described above, the inner wall portion 31 and the outer wall portion 32 constituting the exhaust chamber 30 are configured in a vertically split structure on the upper half side and the lower half side. Here, the inner wall portion 31 on the upper half side is referred to as the upper half side inner wall portion 31a, the inner wall portion 31 on the lower half side is referred to as the lower half side inner wall portion 31b, and the outer wall portion 32 on the upper half side is referred to as the upper half side outer wall portion 32a. The outer wall portion 32 on the lower half side is referred to as a lower half side outer wall portion 32b. The upper half side inner wall portion 31a and the lower half side inner wall portion 31b, and the upper half side outer wall portion 32a and the lower half side outer wall portion 32b are fixed by, for example, bolt fastening via a flange portion (not shown). .

  Here, as shown in FIG. 3, the upper half side inner wall portion 31a and the lower half side inner wall portion 31b show an example in which the shapes in the cross section perpendicular to the turbine rotor axial direction are each semicircular. ing. The center of the semicircle is on the central axis of the turbine rotor.

  As described above, the upper half-side outer wall portion 32a and the lower half-side outer wall portion 32b have a semicircular shape in a cross section perpendicular to the turbine rotor axial direction, but on the downstream side from the portion where the internal structure 53 exists. As shown in FIG. 2, the upper half side outer wall portion 32a and the lower half side outer wall portion 32b are configured to have different shapes.

  Specifically, the inner diameter of the lower half side outer wall portion 32b is configured to be larger than the inner diameter of the upper half side outer wall portion 32a on the downstream side from the portion where the internal structure 53 exists. In other words, the radius of the semicircle of the lower half side outer wall portion 32b is larger than the radius of the semicircle of the upper half side outer wall portion 32a in the cross section perpendicular to the turbine rotor axis direction, where the turbine rotor axial direction position is the same. It is configured. The center of the semicircle is on the central axis of the turbine rotor.

  As shown in FIG. 4, the contour lines of the inner walls of the upper half-side outer wall portion 32a and the lower half-side outer wall portion 32b coincide with each other at the outlet 34 of the exhaust passage 33, and at the outlet 34 of the exhaust passage 33, The inner diameters of the upper half side outer wall portion 32a and the lower half side outer wall portion 32b are configured to be equal. Therefore, as described above, the cross-sectional shape of the flow path at the outlet 34 of the exhaust flow path 33 is circular.

  Here, the flow path cross section of each upper half side outer wall portion 32a and the flow path cross section of each lower half side exhaust flow path 33b in the turbine rotor axial direction are blocked by the internal structure 53 in advance as design values. The design channel cross-sectional area excluding the part is set.

  For example, as shown in FIG. 3, when the internal structure 53 is present in the lower half side exhaust flow path 33b, when the radius of the semicircle of the lower half side outer wall portion 32b is increased, the design flow path sectional area is increased. The radius is set so that can be maintained. Further, for example, when the internal structure 53 exists in the upper half side exhaust flow path 33a and the lower half side exhaust flow path 33b, the lower half side outer wall part 32b and the lower half side outer wall part 32b The radius is set so that the area can be maintained. In addition, in the cross-section of the flow path having the same position in the axial direction of the turbine rotor, the cross-sectional area of the upper half side exhaust flow path 33a and the lower half side exhaust flow path 33b excluding the flow path cross-sectional area blocked by the internal structure 53 The flow path cross-sectional area difference is preferably within a predetermined range.

  Next, a predetermined range of the flow path cross-sectional area difference will be described.

  (1) Flow blocked by the internal structure 53 in the cross-section of the flow path in which the internal structure 53 exists and the shape of the outer wall portion is the same in the turbine rotor axial direction of the portions where the upper half side and the lower half side are different. When the road cross-sectional area is larger on the lower half side than on the upper half side, the cross-sectional area A1 of the upper half-side exhaust flow path 33a excluding the portion blocked by the internal structure 53 and the internal structure 53 The difference in channel cross-sectional area (A1-A2) from the channel cross-sectional area A2 of the lower half-side exhaust channel 33b excluding the portion to be blocked is equal to that of the upper half-side exhaust channel 33a excluding the portion blocked by the internal structure 53. The value ((A1-A2) / A1) divided by the channel cross-sectional area A1 is preferably 0.1 or less. The value of ((A1-A2) / A1) is more preferably 0.05 or less.

  Further, in the cross section of the flow path where the internal structure 53 is present and the positions of the outer wall portions in the upper half side and the lower half side are the same in the turbine rotor axial position, (2) If the flow path cross-sectional area is larger in the upper half side than in the lower half side, the flow path cross-sectional area A2 of the lower half side exhaust flow path 33b excluding the portion blocked by the internal structure 53, and the internal structure The lower half side exhaust flow path excluding the portion blocked by the internal structure 53 is represented by the difference in flow path cross-sectional area (A2-A1) from the flow passage cross sectional area A1 of the upper half side exhaust flow path 33a excluding the portion blocked by 53. It is preferable that the value ((A2-A1) / A2) divided by the channel cross-sectional area A2 of 33b be 0.1 or less. The value of ((A2-A1) / A2) is more preferably 0.05 or less.

  In the first embodiment, an example in which the internal structure 53 does not exist in the upper half side exhaust flow path 33a is shown. Therefore, (1) the cross-sectional area of the flow path blocked by the internal structure 53 described above is high. This corresponds to the case where the lower half is larger than the half. As described above, the internal structure 53 exists in the exhaust channel 33 on the upper half side, and the cross-sectional area blocked by the internal structure 53 is larger on the upper half side than on the lower half side. In this case, (2) the flow path cross-sectional area blocked by the internal structure 53 is equivalent to the case where the upper half side is larger than the lower half side.

  As described above, the upper half side exhaust flow path 33a and the lower half side exhaust flow path are set so that the value of ((A1-A2) / A1) and ((A2-A1) / A2) is 0.1 or less. It is preferable to design 33b, and the reason why this is preferable will be described by exemplifying the reason why the value of ((A1-A2) / A1) is preferably 0.1 or less.

  FIG. 5 shows the flow cross-sectional area A1 of the upper half side exhaust flow path 33a excluding the portion blocked by the internal structure 53, and the flow break of the lower half side exhaust flow path 33b excluding the portion blocked by the internal structure 53. It is a figure which shows the relationship between the value ((A1-A2) / A1) which divided | segmented the flow-path cross-sectional area difference (A1-A2) with area A2 by flow-path cross-sectional area A1, and a performance fall rate. FIG. 6 is a diagram schematically illustrating an example in which the internal structures 53 are evenly arranged in a predetermined flow path cross section of the exhaust chamber 30 in the axial exhaust turbine 10 according to the first embodiment of the present invention. . FIG. 7 is a diagram schematically illustrating an example in which the internal structures 53 are unevenly arranged in a predetermined flow path cross section of the exhaust chamber 30 in the axial exhaust turbine 10 according to the first embodiment of the present invention. is there.

  This relationship is obtained by numerical analysis by CFD (Computational Fluid Dynamics). In addition, this relationship is a summary of the results obtained when the predetermined internal structure 53 is assumed and the predetermined internal structure 53 is variously arranged and configured in the circumferential direction in a predetermined flow path cross section.

  The performance reduction rate is defined by the following equation (1).

  Performance degradation rate (%) = (Standard static pressure recovery coefficient−Static pressure recovery coefficient when the internal structure is unevenly arranged) / Reference static pressure recovery coefficient × 100 Equation (1)

  Here, the reference static pressure recovery coefficient is a static pressure recovery coefficient when the internal structures 53 are evenly arranged in the circumferential direction, as shown in FIG. As shown in FIG. 7, the static pressure recovery coefficient when the internal structures are unevenly arranged is a static pressure recovery coefficient when the internal structures 53 are unevenly arranged in the circumferential direction.

  As shown in FIG. 5, with the increase in the value of ((A1-A2) / A1), the performance deterioration rate increases. It is preferable to configure the performance reduction rate to be 5.5% or less, and for that purpose, it is preferable to configure so that the value of ((A1-A2) / A1) is 0.1 or less. Further, it is more preferable to configure the performance reduction rate to be 1.4% or less, and for that purpose, it is preferable to configure the value of ((A1-A2) / A1) to be 0.05 or less.

  Note that the value of ((A2-A1) / A2) is also preferably 0.1 or less, and more preferably 0.05 or less.

  As described above, in the axial exhaust turbine 10 of the first embodiment, the upper half-side outer wall portion 32a and the lower half-side outer wall portion 32b constituting the exhaust chamber 30 have shapes in a cross section perpendicular to the turbine rotor axial direction. Further, it can be configured to be different on the downstream side from the portion where the internal structure 53 exists. Thereby, the pressure loss in the exhaust chamber 30 can be reduced.

  In the axial exhaust turbine 10 of the first embodiment, (1) when the flow path cross-sectional area blocked by the internal structure 53 is larger on the lower half side than on the upper half side, ((A1 By configuring the value of -A2) / A1) to be 0.1 or less, it is possible to configure the flow path cross-sectional area difference (A1-A2) between the flow path cross-sectional area A1 and the flow path cross-sectional area A2. . Further, (2) when the cross-sectional area of the channel blocked by the internal structure 53 is larger on the upper half side than on the lower half side, the value of ((A2-A1) / A2) is set to 0.1 or less. By comprising, the flow-path cross-sectional area difference (A2-A1) of flow-path cross-sectional area A2 and flow-path cross-sectional area A1 can be comprised small.

  Therefore, even when the exhaust passage 33 has a portion blocked by the internal structure 53, the static pressure can be sufficiently recovered. Further, even when either the upper half side exhaust flow path 33a or the lower half side exhaust flow path 33b is blocked by the internal structure 53, the static pressure can be sufficiently recovered. Thereby, the pressure loss in the exhaust chamber 30 can be reduced.

  In addition, the shape of the lower half side outer wall part 32b in the position where the internal structure 53 starts to exist (position on the most upstream side where the internal structure 53 exists) is as shown in FIG. The inner diameter is not limited to a configuration in which the inner diameter is suddenly larger than the inner diameter of the upper half side outer wall portion 32a.

  FIG. 8 is a diagram schematically showing a meridional section in the vertical direction of the exhaust chamber 30 of another configuration in the axial exhaust turbine 10 of the first embodiment according to the present invention. As shown in FIG. 8, it is good also as a structure that the internal diameter of the lower half side outer wall part 32b becomes larger gradually than the internal diameter of the upper half side outer wall part 32a in the downstream from the part in which the internal structure 53 exists. Even in this configuration, the same effects as those described above can be obtained, and the pressure loss in the exhaust chamber 30 can be reduced.

  In the above-described embodiment, the upper half side outer wall portion 32a and the ((A1-A2) / A1) and ((A2-A1) / A2) values are set to 0.1 or less. Although an example in which the shape of the lower half side outer wall portion 32b in the cross section perpendicular to the turbine rotor axial direction is a semicircular shape has been shown, it is not limited to this configuration.

  9 and 10 schematically show a cross section corresponding to the AA cross section of FIG. 2, showing the shape of the different exhaust chamber 30 in the axial exhaust turbine 10 of the first embodiment according to the present invention. FIG. In FIGS. 9 and 10, a cross section is shown with a part of the configuration omitted.

  As shown in FIG. 9, for example, the shape of the upper half side outer wall portion 32 a in a cross section perpendicular to the turbine rotor axial direction may be an ellipse. By configuring in this way, while maintaining the design channel cross-sectional area as an elliptical cross-sectional shape of the upper half side outer wall portion 32a, in the joint portion of the upper half side outer wall portion 32a and the lower half side outer wall portion 32b, The inner peripheral surface can be formed without a step.

  As shown in FIG. 10, for example, the shape of the upper half side outer wall portion 32a in the cross section perpendicular to the turbine rotor axial direction is a semicircular shape, and the shape of the lower half side outer wall portion 32b in the cross section perpendicular to the turbine rotor axial direction is You may comprise by 2 or more types of circular arcs which have a different radius. By configuring in this way, the inner peripheral surface of the coupling portion between the upper half side outer wall portion 32a and the lower half side outer wall portion 32b can be maintained without a step while maintaining the design flow path cross-sectional area of the lower half side outer wall portion 32b. Can be formed.

  Even in the case where the exhaust chamber 30 is configured in this way, the same operational effects as those described above can be obtained, and the pressure loss in the exhaust chamber 30 can be reduced.

(Second Embodiment)
Since the axial exhaust turbine 10 of the second embodiment is the same as the configuration of the axial exhaust turbine 10 of the first embodiment except for the configuration of the exhaust chamber 30, the configuration of the exhaust chamber 30 is here. Is mainly described.

  FIG. 11 is a diagram schematically showing a meridional section in the horizontal direction of the exhaust chamber 30 in the axial exhaust turbine 10 according to the second embodiment of the present invention. FIG. 12 is a diagram schematically showing a BB cross section of FIG. 11. Note that in FIGS. 11 and 12, a part of the configuration is omitted and a cross section is shown.

  As shown in FIGS. 11 and 12, the internal structure 53 exists in the upper half side exhaust flow path 33 a and the lower half side exhaust flow path 33 b of the exhaust chamber 30. Further, as shown in FIG. 12, in the cross section perpendicular to the turbine rotor axial direction in the exhaust flow path 33 where the internal structure 53 exists, it intersects perpendicularly with the vertical center line L and intersects with the turbine rotor central axis. An internal structure 53 is provided symmetrically on the upper half side and the lower half side with the horizontal center line M as the axis of symmetry.

  Here, an example in which the internal structure 53 is provided along the center line L and the internal structure 53 does not exist on the right half side (right side of the center line L in FIG. 12) is shown. There may be a case where the internal structure 53 exists in the exhaust passage on the right half side of the internal structure 53 provided along the line L. Here, in FIG. 12, the exhaust flow path 33 on the left side of the center line L among the exhaust flow paths 33 is referred to as a left half side exhaust flow path 33c, and the exhaust flow path 33 on the right side of the center line L is referred to as the right half. This is referred to as a side exhaust passage 33d.

  As described above, the exhaust chamber 30 has a vertically split structure, and the upper half side inner wall portion 31a and the lower half side inner wall portion 31b, and the upper half side outer wall portion 32a and the lower half side outer wall portion 32b are: Each is fixed by, for example, bolt fastening through a flange portion (not shown). By fixing the upper half side outer wall part 32a and the lower half side outer wall part 32b, the left half side exhaust flow path 33c is located on the left side of the center line L and the right side of the center line L is located on the right side as described above. A half-side exhaust passage 33d is formed.

  Here, as shown in FIG. 12, the upper half side inner wall portion 31a and the lower half side inner wall portion 31b are configured by two circular arcs having different radii in the cross section perpendicular to the turbine rotor axial direction. An example in which the shapes on the left half side and the right half side are different is shown. The center of the semicircle is on the central axis of the turbine rotor.

  In the upper half side outer wall portion 32a and the lower half side outer wall portion 32b, as described above, the shapes of the left half side and the right half side in the cross section perpendicular to the turbine rotor axial direction are semicircular. As shown in FIG. 11, the left half side and the right half side are configured to have different shapes on the downstream side from the portion where 53 is present.

  Specifically, in the upper half side outer wall portion 32a and the lower half side outer wall portion 32b, the inner diameter of the left half side is configured to be larger than the inner diameter of the right half side downstream from the portion where the internal structure 53 exists. Yes. In other words, in the cross section perpendicular to the turbine rotor axial direction where the turbine rotor axial position is the same, the radius of the left half circle is larger than the radius of the right half circle. The center of the semicircle is on the central axis of the turbine rotor.

  In addition, in the upper half side outer wall part 32a and the lower half side outer wall part 32b, at the outlet 34 of the exhaust flow path 33, the inner diameters of the left half side and the right half side are configured to be equal. Therefore, as described above, the cross section of the flow path at the outlet 34 of the exhaust flow path 33 is circular.

  Here, with respect to the cross sections of the left half exhaust passages 33c and the right half exhaust passages 33d in the turbine rotor axial direction, portions that are blocked by the internal structure 53 are excluded as design values in advance. The design channel cross-sectional area is set.

  For example, as shown in FIG. 12, when the internal structure 53 is present in the left half side exhaust flow path 33c and the right half side exhaust flow path 33d, the respective design flow path cross-sectional areas can be maintained. In the upper half side outer wall portion 32a and the lower half side outer wall portion 32b, radii on the left half side and the right half side are set. The cross-sectional areas of the left half-side exhaust flow path 33c and the right half-side exhaust flow path 33d, excluding the flow-path cross-sectional area blocked by the internal structure 53, in the cross-section of the flow path having the same turbine rotor axial position. The difference is preferably within a predetermined range.

  Next, a predetermined range of the flow path cross-sectional area difference will be described.

  (1) Flow blocked by the internal structure 53 in the cross-section of the flow path in which the internal structure 53 exists and the shape of the outer wall portion is the same in the turbine rotor axial position at different portions on the left half side and the right half side When the road cross-sectional area is larger on the right half side than on the left half side, the flow cross-sectional area A3 of the left half side exhaust flow path 33c excluding the portion blocked by the internal structure 53 and the internal structure 53 The difference in channel cross-sectional area (A3-A4) from the channel cross-sectional area A4 of the right half-side exhaust channel 33d excluding the portion to be blocked is equal to that of the left half-side exhaust channel 33c excluding the portion blocked by the internal structure 53. It is preferable that the value ((A3-A4) / A3) divided by the channel cross-sectional area A3 is 0.1 or less. The value of ((A3-A4) / A3) is more preferably 0.05 or less.

  Further, in the cross section of the flow path where the internal structure 53 exists and the shape of the outer wall portion is the same in the turbine rotor axial direction at the portions where the left half side and the right half side are different, (2) If the flow path cross-sectional area is larger on the left half side than on the right half side, the cross-sectional area A4 of the right half side exhaust flow path 33d excluding the portion blocked by the internal structure 53, and the internal structure The right half side exhaust flow path excluding the portion blocked by the internal structure 53 is the difference in flow path cross-sectional area (A4-A3) from the flow path cross sectional area A3 of the left half side exhaust flow path 33c excluding the portion blocked by 53. The value ((A4-A3) / A4) divided by the channel cross-sectional area A4 of 33d is preferably 0.1 or less. The value of ((A4-A3) / A4) is more preferably 0.05 or less.

  In the second embodiment, an example in which the cross-sectional area of the channel blocked by the internal structure 53 is larger on the left half side than on the right half side is shown. Therefore, the above-described (2) internal structure This corresponds to the case where the cross-sectional area of the channel blocked by 53 is larger on the left half side than on the right half side. Moreover, it can also be set as the structure where the flow-path cross-sectional area interrupted | blocked by the internal structure 53 becomes larger on the right half side than the left half side. In this case, (1) the flow path cross-sectional area blocked by the internal structure 53 is equivalent to the case where the right half side is larger than the left half side.

  As described above, the left half exhaust passage 33c and the right half exhaust passage are set so that the values of ((A3-A4) / A3) and ((A4-A3) / A4) are 0.1 or less. The reason why it is preferable to design 33d is that the value of ((A1-A2) / A1) or ((A2-A1) / A2) shown in the first embodiment is preferably 0.1 or less. The reason is the same. The reason why it is more preferable to set the value of ((A3-A4) / A3) or ((A4-A3) / A4) to 0.05 or less is also shown in the first embodiment ((A1- The reason why the value of (A2) / A1) or ((A2-A1) / A2) is more preferably 0.05 or less is the same as the reason.

  Thus, in the axial exhaust turbine 10 of the second embodiment, the left half side of the upper half side outer wall portion 32a and the lower half side outer wall portion 32b, and the upper half side outer wall portion 32a and the lower half side outer wall portion 32b. The shape in the cross section perpendicular to the turbine rotor axial direction on the right half side of the turbine can be configured to be different from the portion where the internal structure 53 exists on the downstream side. Thereby, the pressure loss in the exhaust chamber 30 can be reduced.

  In the axial exhaust turbine 10 of the second embodiment, (1) when the cross-sectional area of the flow path blocked by the internal structure 53 is larger on the right half side than on the left half side, ((A3 By configuring the value of -A4) / A3) to be 0.1 or less, the flow path cross-sectional area difference (A3-A4) between the flow path cross-sectional area A3 and the flow path cross-sectional area A4 can be reduced. . Further, (2) when the cross-sectional area of the channel blocked by the internal structure 53 is larger on the left half side than on the right half side, the value of ((A4-A3) / A4) is set to 0.1 or less. By comprising, the flow-path cross-sectional area difference (A4-A3) of flow-path cross-sectional area A4 and flow-path cross-sectional area A3 can be comprised small.

  Therefore, even when the exhaust passage 33 has a portion blocked by the internal structure 53, the static pressure can be sufficiently recovered. Further, even when either the left half-side exhaust flow path 33c or the right half-side exhaust flow path 33d is blocked by the internal structure 53, the static pressure can be sufficiently recovered. Thereby, the pressure loss in the exhaust chamber 30 can be reduced.

  Further, in the above-described embodiment, in order to configure the value of ((A3-A4) / A3) and ((A4-A3) / A4) as 0.1 or less, the upper half side outer wall portion 32a and Although an example in which the shape of the lower half side outer wall portion 32b in the cross section perpendicular to the turbine rotor axial direction is a semicircular shape has been shown, it is not limited to this configuration.

  For example, from the technical idea similar to the configuration in the first embodiment shown in FIG. 9, for example, perpendicular to the turbine rotor axial direction on the right half side of the upper half side outer wall portion 32a and the lower half side outer wall portion 32b. The shape in a simple cross section can be formed into an elliptical shape while maintaining the design flow path cross-sectional area so that there are no steps on the inner peripheral surfaces of the upper half side outer wall portion 32a and the lower half side outer wall portion 32b.

  For example, in the case where the left half exhaust passage 33c is further provided with the internal structure 53, from the technical idea similar to the configuration in the first embodiment shown in FIG. The shape of the cross section perpendicular to the turbine rotor axial direction on the right half side of 32a and the lower half side outer wall portion 32b may be constituted by two or more arcs having different radii.

  Even in the case where the exhaust chamber 30 is configured in this way, the same operational effects as those described above can be obtained, and the pressure loss in the exhaust chamber 30 can be reduced.

(Third embodiment)
The axial flow exhaust turbine 10 of the third embodiment is configured by shifting the arrangement positions of the internal structures 53 in the upper half side exhaust flow path 33a and the lower half side exhaust flow path 33b in the turbine rotor axial direction. These are the same as the structure of the axial flow exhaust turbine 10 of 1st Embodiment.

  FIG. 13 is a diagram schematically showing a meridional section in the vertical direction of the exhaust chamber 30 in the axial exhaust turbine 10 of the third embodiment according to the present invention. FIG. 14 is a diagram schematically showing a CC cross section of FIG. In FIGS. 13 and 14, a cross section is shown with a part of the configuration omitted.

  Here, the case where the cross-sectional shapes perpendicular to the turbine rotor axial direction of the upper half side inner wall portion 31a and the lower half side inner wall portion 31b in the first embodiment are respectively semicircular will be described as an example. .

  In the axial exhaust turbine 10 of the third embodiment, the internal structure 53 is present, and the flow path in which the positions of the outer wall portions of the turbine rotor are different in the upper half side and the lower half side in the same position in the axial direction of the turbine rotor. In the cross section, (1) when the flow path cross-sectional area blocked by the internal structure 53 is larger on the lower half side than on the upper half side, the installation position of the internal structure 53 in the lower half side exhaust flow path 33b is The upper half exhaust passage 33a is provided on the downstream side of the installation position of the internal structure 53.

  On the other hand, in the cross-section of the flow path where the internal structure 53 exists and the outer wall portion has the same position in the turbine rotor axial direction at different portions in the upper half side and the lower half side, (2) the inner structure 53 When the flow path cross-sectional area to be obtained is larger in the upper half side than in the lower half side, the installation position of the internal structure 53 in the upper half side exhaust flow path 33a is the internal structure in the lower half side exhaust flow path 33b. It is provided downstream of the installation position of 53.

  Here, as shown in FIG. 14, the flow path cross-sectional area blocked by the internal structure 53 is illustrated as being larger on the lower half side than on the upper half side. The installation position of the internal structure 53 in the half-side exhaust flow path 33b is provided downstream of the installation position of the internal structure 53 in the upper half-side exhaust flow path 33a.

  In addition, although the case where the flow path cross-sectional area blocked by the internal structure 53 is larger in the upper half side than in the lower half side is not illustrated, in this case, the internal structure in the upper half side exhaust flow path 33a The installation position of the object 53 is provided downstream of the installation position of the internal structure 53 in the lower half side exhaust flow path 33b.

  In this way, by providing the internal structure 53 on the more downstream side of the upper half side exhaust flow path 33a and the lower half side exhaust flow path 33b that has a larger flow path cross-sectional area blocked by the internal structure 53, The internal structure 53 can be provided at a position where the flow path cross-sectional area is further increased and the flow velocity of the steam is slower. As a result, the static pressure can be sufficiently recovered even in the region where the cross-sectional area of the channel blocked by the internal structure 53 is large. Further, the pressure loss and flow velocity distribution in the upper half side exhaust flow path 33a and the lower half side exhaust flow path 33b can be made uniform. From these things, the pressure loss in the exhaust chamber 30 can be reduced.

(Fourth embodiment)
The axial flow exhaust turbine 10 of the fourth embodiment is configured by shifting the arrangement positions of the internal structures 53 in the left half exhaust passage 33c and the right half exhaust passage 33d in the turbine rotor axial direction. These are the same as the structure of the axial flow exhaust turbine 10 of 2nd Embodiment.

  FIG. 15 is a diagram schematically showing a meridional section in the horizontal direction of the exhaust chamber 30 in the axial exhaust turbine 10 of the fourth embodiment according to the present invention. FIG. 16 is a diagram schematically showing a DD cross section of FIG. 15. In FIGS. 15 and 16, a cross section is shown with a part of the configuration omitted.

  Here, as shown in FIG. 16, in the portion where the internal structure exists, the upper half side inner wall portion 31 a and the lower half side inner wall portion 31 b have different radii of cross-sectional shapes perpendicular to the turbine rotor axial direction. A case will be described by way of example in which the left half side and the right half side have different shapes.

  In the axial exhaust turbine 10 of the fourth embodiment, the internal structure 53 is present, and the flow path in which the positions of the outer wall portions of the turbine rotor are different in the left half side and the right half side in the same position in the axial direction of the turbine rotor. In the cross section, (1) when the cross-sectional area of the channel blocked by the internal structure 53 is larger on the right half side than on the left half side, the installation position of the internal structure 53 in the right half side exhaust flow path 33d is The left half exhaust passage 33c is provided downstream of the installation position of the internal structure 53.

  On the other hand, in the cross-section of the flow path where the internal structure 53 exists and the outer wall has different shapes on the left half side and the right half side at the same position in the turbine rotor axial direction, (2) the inner structure 53 When the flow path cross-sectional area to be obtained is larger on the left half side than on the right half side, the installation position of the internal structure 53 in the left half side exhaust flow path 33c is the internal structure in the right half side exhaust flow path 33d. It is provided downstream of the installation position of 53.

  Here, as shown in FIG. 16, the flow path cross-sectional area blocked by the internal structure 53 is illustrated as being larger on the left half side than on the right half side. The installation position of the internal structure 53 in the half-side exhaust flow path 33c is provided downstream of the installation position of the internal structure 53 in the right half-side exhaust flow path 33d.

  Although the case where the cross-sectional area of the flow path blocked by the internal structure 53 is larger on the right half side than on the left half side is not shown, in this case, the internal structure in the right half side exhaust flow path 33d The installation position of the object 53 is provided on the downstream side of the installation position of the internal structure 53 in the left half side exhaust passage 33c.

  Thus, by providing the internal structure 53 on the more downstream side of the left half side exhaust flow path 33c and the right half side exhaust flow path 33d that has a larger flow path cross-sectional area blocked by the internal structure 53, The internal structure 53 can be provided at a position where the flow path cross-sectional area is further increased and the flow velocity of the steam is slower. As a result, the static pressure can be sufficiently recovered even in the region where the cross-sectional area of the channel blocked by the internal structure 53 is large. Further, the pressure loss and flow velocity distribution in the left half side exhaust flow path 33c and the right half side exhaust flow path 33d can be made uniform. From these things, the pressure loss in the exhaust chamber 30 can be reduced.

  According to the embodiment described above, the pressure loss in the exhaust chamber can be reduced.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. In the above-described embodiment, the steam turbine is illustrated as an example of the axial flow exhaust turbine. However, for example, the present invention can also be applied to an axial flow exhaust chamber of a gas turbine.

  DESCRIPTION OF SYMBOLS 10 ... Axial exhaust turbine, 20 ... Casing, 21 ... Moving blade, 22 ... Turbine rotor, 23a, 23b ... Diaphragm, 24 ... Nozzle, 25 ... Gland seal part, 26 ... Steam inlet pipe, 30 ... Exhaust chamber, 31 ... Inner wall part, 31a ... Upper half side inner wall part, 31b ... Lower half side inner wall part, 32 ... Outer wall part, 32a ... Upper half side outer wall part, 32b ... Lower half side outer wall part, 33 ... Exhaust flow path, 33a ... Upper half Side exhaust flow path, 33b ... Lower half side exhaust flow path, 33c ... Left half side exhaust flow path, 33d ... Right half side exhaust flow path, 34 ... Exit, 50 ... Piping, 51 ... Pressure equalizing pipe, 52 ... Support member, 53: Internal structure, L, M: Center line.

Claims (8)

Between the inner wall portion arranged in the axial direction of the turbine rotor around the turbine rotor and the outer wall portion arranged on the outer periphery of the inner wall portion, the flow passage cross-sectional area is formed so as to gradually increase in the downstream direction. The axial flow exhaust turbine includes an exhaust chamber having an exhaust passage for exhausting the working fluid in the axial direction of the turbine rotor, and an internal structure exists in the exhaust passage through which the working fluid passes in the exhaust chamber.
An axial exhaust turbine characterized in that an inner diameter of the outer wall portion is different between an upper half side and a lower half side on a downstream side from a portion where the internal structure exists.   In the cross section perpendicular to the turbine rotor axial direction in the exhaust passage where the internal structure is present, the internal structure is symmetrically arranged on the left half side and the right half side with the vertical center line in the cross section as the axis of symmetry. The axial exhaust turbine according to claim 1, further comprising an object. The internal structure is present, Oite the turbine rotor axial direction position location of different parts in the shape of the outer wall portion and the upper half side and a lower half side,
(1) When the flow path cross-sectional area blocked by the internal structure is larger on the lower half side than on the upper half side,
A flow passage cross-sectional area A1 of the upper half exhaust passage excluding a portion blocked by the internal structure and a flow passage cross-sectional area A2 of the lower half exhaust flow passage excluding the portion blocked by the internal structure The value obtained by dividing the flow path cross-sectional area difference (A1-A2) by the flow path cross-sectional area A1 ((A1-A2) / A1) is 0.1 or less,
(2) When the flow path cross-sectional area blocked by the internal structure is larger on the upper half side than on the lower half side,
A flow passage cross-sectional area A2 of the lower half exhaust passage excluding a portion blocked by the internal structure, and a flow passage cross-sectional area A1 of the upper half exhaust flow passage excluding the portion blocked by the internal structure. The value ((A2-A1) / A2) obtained by dividing the flow path cross-sectional area difference (A2-A1) by the flow path cross-sectional area A2 is 0.1 or less. Axial exhaust turbine. The internal structure is present, Oite the turbine rotor axial direction position location of different parts in the shape of the outer wall portion and the upper half side and a lower half side,
(1) When the flow path cross-sectional area blocked by the internal structure is larger on the lower half side than on the upper half side,
The installation position of the internal structure in the exhaust channel on the lower half side is downstream from the installation position of the internal structure in the exhaust channel on the upper half side,
(2) When the flow path cross-sectional area blocked by the internal structure is larger on the upper half side than on the lower half side,
4. The installation position of the internal structure in the exhaust channel on the upper half side is downstream of the installation position of the internal structure in the exhaust channel on the lower half side. An axial-flow exhaust turbine according to any one of the above. Between the inner wall portion arranged in the axial direction of the turbine rotor around the turbine rotor and the outer wall portion arranged on the outer periphery of the inner wall portion, the flow passage cross-sectional area is formed so as to gradually increase in the downstream direction. The axial flow exhaust turbine includes an exhaust chamber having an exhaust passage for exhausting the working fluid in the axial direction of the turbine rotor, and an internal structure exists in the exhaust passage through which the working fluid passes in the exhaust chamber.
2. An axial exhaust turbine according to claim 1, wherein a shape of the outer wall portion is different between a left half side and a right half side downstream from a portion where the internal structure exists.   In the cross section perpendicular to the turbine rotor axial direction in the exhaust flow path in which the internal structure exists, the internal structure is symmetrical in the upper half side and the lower half side with the horizontal center line in the cross section as the axis of symmetry. The axial exhaust turbine according to claim 5, further comprising an object. The internal structure is present, Oite shape of the outer wall portion in the axial direction of the turbine rotor position location of different parts in the left half and right half,
(1) When the cross-sectional area of the channel blocked by the internal structure is larger on the right half side than on the left half side,
A cross-sectional area A3 of the exhaust passage on the left half side excluding the portion blocked by the internal structure, and a cross-sectional area A4 of the exhaust passage on the right half side excluding the portion blocked by the internal structure A value obtained by dividing the flow path cross-sectional area difference (A3-A4) by the flow path cross-sectional area A3 ((A3-A4) / A3) is 0.1 or less,
(2) When the cross-sectional area of the channel blocked by the internal structure is larger on the left half side than on the right half side,
A flow passage cross-sectional area A4 of the right half exhaust passage excluding a portion obstructed by the internal structure, and a flow passage cross-sectional area A3 of the left half exhaust passage excluding a portion obstructed by the internal structure. The value ((A4-A3) / A4) obtained by dividing the flow path cross-sectional area difference (A4-A3) by the flow path cross-sectional area A4 is 0.1 or less. Axial exhaust turbine. The internal structure is present, Oite shape of the outer wall portion in the axial direction of the turbine rotor position location of different parts in the left half and right half,
(1) When the cross-sectional area of the channel blocked by the internal structure is larger on the right half side than on the left half side,
The installation position of the internal structure in the exhaust channel on the right half side is downstream of the installation position of the internal structure in the exhaust channel on the left half side,
(2) When the cross-sectional area of the channel blocked by the internal structure is larger on the left half side than on the right half side,
8. The installation position of the internal structure in the exhaust passage on the left half side is downstream of the installation position of the internal structure in the exhaust passage on the right half side. An axial-flow exhaust turbine according to any one of the above.

Images