JP4728192B2 - Axial turbine and inlet structure - Google Patents

Description

  The present invention relates to an axial flow turbine that obtains energy by flowing a working fluid in the axial direction of a turbine rotor, and an inlet structure of the axial flow turbine that introduces the working fluid into the axial flow turbine.

  The axial turbine has a turbine rotor having a plurality of blade rows attached in the axial direction, and an annular flow path (annular zone) formed on the outer periphery of the turbine rotor, and operates on the annular flow path. A shaft driving force is obtained by causing a fluid to flow and colliding with a plurality of blade rows on the turbine rotor.

  In order to improve the efficiency of the axial flow turbine, it is important to uniformly introduce the working fluid into the annular flow path, and there are various types of inlet structures of the axial flow turbine that serve to guide the working fluid to the annular flow path. Ingenuity is given. Some of the inlet structures of such axial flow turbines introduce a working fluid at a right angle toward the rotational axis of the turbine rotor. And among those adopting this type of axial turbine inlet structure, the flow is adjusted by providing a plate (distribution plate) that disperses the fluid in the path toward the inlet of the annular flow path, Some have improved the turbine efficiency by making the flow rate of the working fluid introduced into the annular flow path uniform (see Patent Document 1, etc.).

JP-A-9-158703

  However, in the technology as described above, the working fluid is not necessarily uniformly distributed on the surface orthogonal to the flow path center line until reaching the installation location of the flow dividing plate, and the case where the distribution is not uniform is also considered. Then, it is not sufficient to install the flow dividing plate in order to uniformly introduce the working fluid into the annular flow path. Further, depending on the flow distribution of the working fluid from the upstream side, the flow dividing plate acts as a resistance and the pressure loss increases, and the turbine efficiency may decrease.

  An object of the present invention is to provide an axial flow turbine and an inlet structure thereof capable of uniformly introducing a working fluid into an annular flow path.

In order to achieve the above object, the present invention provides an axial flow turbine that obtains rotational power by flowing a working fluid in an axial direction of a turbine rotor, covering the turbine rotor from an outer peripheral side of the turbine rotor, A casing that forms an annular flow path for flowing a working fluid between the inlet pipe, an introduction pipe that is a flow path for flowing the working fluid introduced into the annular flow path, and a flow path center line connected to the introduction pipe A bent portion formed so as to be changed in a direction orthogonal to the rotation axis of the turbine rotor, and connected to the annular flow path provided continuously with the bent portion, and distributes the working fluid to the annular flow path. and a distribution chamber having a distribution portion, the bent portion, so that the direction of the passage center line of the connecting portion between the inlet tube coincides with the direction of the passage center line of the inlet pipe at the connecting portion Is connected to the inlet pipe, said distribution chamber, the flow path width in the direction of intersection line of a plane perpendicular to the rotation axis of said the distribution chamber plane perpendicular to the channel center line of the turbine rotor, the distribution It shall be formed so that it may monotonously expand from the connection part with the said introductory pipe in the said bending part along the direction of the flow-path centerline of a chamber.

  According to the present invention, the working fluid can be uniformly distributed on the surface orthogonal to the flow path center line of the distribution chamber, and the working fluid can be uniformly introduced into the annular flow path, so that the turbine efficiency is improved. Can do.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the expressions “parallel”, “right angle (orthogonal)” and “symmetry” described in this specification do not limit strict parallel, right angle, and symmetry, and manufacturing tolerances, design tolerances, or these A range such as an error due to accumulation is allowed.

First, a first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a diagram schematically showing a system of a thermal power plant including an axial turbine according to the first embodiment of the present invention, and FIG. 2 is a side view of a low-pressure turbine in the thermal power plant shown in FIG. FIG. 3 is an enlarged view of the vicinity of the first stage stationary blade in the low-pressure turbine shown in FIG.

  The thermal power plant shown in FIG. 1 includes a high-pressure turbine 1, an intermediate-pressure turbine 2, and a low-pressure turbine 3. The low-pressure turbine 3 includes a turbine rotor 4 that obtains rotational power by flowing a working fluid in the axial direction. The rotors of the high-pressure turbine 1 and the intermediate-pressure turbine 2 are arranged on the same axis as the turbine rotor 4.

  The high-pressure turbine 1 is connected with an introduction pipe 5 and an introduction pipe 6 for circulating a working fluid (steam). The introduction pipe 5 is connected to a steam generation source (not shown) on the upstream side in the working fluid flow direction, and introduces steam into the high-pressure turbine 1. Steam introduced from the high-pressure turbine 1 is discharged to the introduction pipe 6. The introduction pipe 6 is a reheater (not shown) for reheating the steam discharged from the high-pressure turbine 1 on the downstream side in the working fluid flow direction. Connected).

  An introduction pipe 7 and an introduction pipe 8 are connected to the intermediate pressure turbine 2. The introduction pipe 7 is connected to the reheater on the upstream side in the working fluid flow direction, and introduces reheated steam into the intermediate pressure turbine 2. Steam introduced from the intermediate pressure turbine 2 is discharged to the introduction pipe 8, and the introduction pipe 8 is connected to the low pressure turbine 3 on the downstream side in the working fluid flow direction. In addition, the introduction pipe 8 is connected to the low-pressure turbine 3 by connecting to the parallel portion 9 in which the flow path center line is arranged in parallel with the rotation axis O of the turbine rotor 4 in the path to the low-pressure turbine 3. And a distribution chamber 20 (described later) for distributing the working fluid.

  The low-pressure turbine 3 introduces steam that has been introduced into the turbine rotor 4 through the distribution chamber 20 (described later) into the condenser (not shown). In addition, the arrow 10 in a figure has shown the flow of the steam to a condenser.

  Next, the configuration of the low-pressure turbine 3 according to the first embodiment of the present invention will be described in detail with reference to FIG. In FIG. 2, the low-pressure turbine 3 includes a turbine rotor 4 and an annular flow path (annular zone) 11 that covers the turbine rotor 4 from the outer peripheral side (outside in the radial direction) and allows the working fluid to flow between the turbine rotor 4. An inner casing 12 to be formed, a partition wall that covers the inner casing 12 from the outside (the radially outer side of the turbine rotor 4), an outer casing 13 that forms a space held in vacuum with the inner casing 12, and an annular shape A flow channel through which the working fluid introduced into the flow channel 11 circulates, the flow channel center line 14 having a parallel portion 9 disposed in parallel with the rotational axis O of the turbine rotor 4, The bent portion 17 connected to the parallel portion 9 of the pipe 8 and the connecting portion 15 is connected to the bent portion 17 and the bent portion 16 formed so that the flow path center line 16 is changed in a direction orthogonal to the rotational axis O of the turbine rotor 4. Distributing portion 18 connected to annular flow passage 11 and distributing working fluid to annular flow passage 11, and provided in distribution portion 18 and arranged upstream of annular flow passage 11 in the working fluid flow direction. 11 and a distribution chamber 20 having a constricted portion 19 that narrows a flow path through which the working fluid before flowing into the apparatus 11 flows.

  The turbine rotor 4 has moving blades 21 arranged in an annular shape in the circumferential direction of the turbine rotor 4, and a moving blade row 22 that is an array of such annular moving blades 21 extends in the axial direction of the turbine rotor 4. A plurality are provided at predetermined intervals. The arrangement of the rotor blade rows 22 is symmetrically formed toward both ends of the turbine rotor 4 with respect to the position of the distribution chamber 20, and the length of the rotor blades 21 constituting the rotor blade row 22 extends from the distribution chamber 20. It gets bigger as you leave.

  In the annular flow path 11, in addition to the moving blade 21 described above, a stationary blade 23 that is paired with the moving blade 21 to form a turbine stage is held by the inner casing 11. The stationary blades 23 form a plurality of stationary blade rows 24 in the axial direction of the turbine rotor 4 in the same manner as the moving blades 21, and the stationary blade rows 24 are provided alternately with the moving blade rows 22 along the axial direction of the turbine rotor 4. ing. As shown in FIG. 2 and FIG. 3A, the first stage stationary blade 23a in the present embodiment is provided radially near the rotation axis of the turbine rotor 4 in the vicinity of the inlet of the annular flow path 11. Instead of such an arrangement, a first stage stationary blade 23a may be provided in the throttle portion 19 in the distribution chamber 20, as shown in FIG. If comprised in this way, a uniform turning component can be provided with respect to the working fluid immediately before flowing into the annular flow path 11. In this case, the first blade in the annular channel 11 is the moving blade 21a.

Next, the distribution chamber 20 will be described in detail with reference to FIGS.
4 is a view showing the vicinity of the distribution chamber in the low-pressure turbine shown in FIG. 2, and FIG. 5 is a perspective view of the distribution chamber in the low-pressure turbine shown in FIG. 4A is an elevational view of the distribution chamber 20 as viewed from the axial direction of the turbine rotor 4, and FIG. 4B is a cross-sectional view of the cross section of the distribution chamber 20 as viewed from a direction orthogonal to the axis of the turbine rotor 4. . In addition, the same code | symbol is attached | subjected to the same part as the previous figure, description is abbreviate | omitted, and it is the same also about a later figure.

  The distribution chamber 20 has a curved portion 17 and a distribution portion 18, and has a flow path width W in the direction of the intersection line L between the surface S perpendicular to the flow path center line 16 and the surface U perpendicular to the rotation axis O of the turbine rotor 4. However, it forms so that it may expand monotonously along the direction of the flow-path centerline 16 of the distribution chamber 20 from the connection part 15 which the bending part 17 starts.

  The flow path center line 16 is a line located at the center of the flow path formed by the bent portion 17 and the distribution portion 18 of the distribution chamber 20. Here, the points on the flow path center line 16 are defined as points A to F in order from the connecting portion 15 toward the turbine rotor 4 as shown in FIG. The point A that is the start point of the flow path center line 16 is the flow path center point in the connection portion 15, and the point F that is the end point is connected in the longitudinal direction of the distribution chamber 20 (vertical direction on the paper surface of FIG. 4A). It is the edge part (lower end part on the paper surface of Fig.4 (a)) located on the opposite side to the part 15. FIG.

  In the present embodiment, the bending portion 17 starts from point A (connection portion 15) connected to the introduction pipe 8 and ends at point E connected to the distribution portion 19. Since the bent portion 17 is formed so that the flow path center line 16 is changed in a direction orthogonal to the rotation axis O of the turbine rotor 4 as described above, the direction of the flow path center line 16 at the point A is Similar to the flow path center line 14 of the introduction pipe 8, the direction of the flow path center line 16 at the point E is the flow path center line of the distribution unit 18. Similarly to 16, the direction is perpendicular to the rotational axis O of the turbine rotor 4.

  The distributor 19 is connected to the bent portion 17 at point E, and the flow path center line 16 is orthogonal to the rotational axis O of the turbine rotor 4. The turbine rotor 4 passes through the distributor 18, and a constricted portion 19 is provided in a ring shape at a predetermined interval on the radially outer side of the turbine rotor 4. The annular flow path that extends from the throttle portion 19 to the inside in the radial direction of the turbine rotor 4 has a flow passage area that is larger than the flow passage area of the throttle portion 19, and reduces the speed of the working fluid that has passed through the throttle portion 19. The working fluid is configured to be introduced uniformly into the annular flow path 11.

  The surface S is a surface that is individually defined according to the position on the flow path center line 16. In the following, when the surface S at each point (point A to point F in FIG. 5) defined as described above on the flow path center line 16 is represented, for example, the surface at the point A is referred to as a surface Sa. A lowercase letter of a symbol indicating a dot is shown as an S suffix.

  The intersection line L is defined by the intersection line of the surface S and the surface U, and is uniquely determined as a line orthogonal to the surface including the rotation axis O of the turbine rotor 4 and the flow path center line 16 in the present embodiment. The Here, in FIG. 5, the surface Se, the surface U, and the intersection line L at the point E are illustrated. Strictly speaking, the surface Sa and the surface U orthogonal to the flow path center line 16 are the same at the connection portion 15 (point A), and thus the intersection line L is not formed. The direction of the line L.

  The channel width W is a channel width in the direction of the intersection line L of the distribution chamber 20. Similarly to the surface S, the channel width W is represented by a symbol indicating each point when representing the channel width W at each point (points A to F in FIG. 5) defined on the channel center line 16. The lower case letter is indicated by subscripting W. The channel width W in the present embodiment follows the channel center line 16 with the channel width Wa (the channel diameter of the introduction pipe 8) at the point A (connection portion 15) on the channel center line 16 being the minimum value. As point B and point C progress, the angle gradually increases and reaches the maximum value in the plane including the rotation axis O of the turbine rotor 4. The flow path width W having the maximum value is gradually increased from the maximum value to zero in the direction of the point F that is the end point of the flow path center line 16 (the direction opposite to the connection portion 15). to shrink. Thus, the distribution chamber 20 in the present embodiment has the end point of the flow path center line 16 as the apex in the lower half portion that is perpendicular to the flow path center line 16 and below the plane that includes the rotation axis O. A convex curved surface is formed below.

Further, the shape of the flow passage cross section (the shape of the surface S) of the distribution chamber 20 in the present embodiment is the same circular shape (first cross sectional shape) as the cross sectional shape of the introduction pipe 8 at the connection portion 15 (point A). On the other hand, the point E in the vicinity of the turbine rotor 4 is rectangular (second cross-sectional shape) , and the change is significant when the cross-sectional shapes are compared at point A and point E on the flow path center line 16. Thus, when the change in the cross-sectional shape is severe between the upstream side and the downstream side of the distribution chamber 20, the shape change in the direction of the flow path center 16 is performed by continuously changing the cross-sectional shape in the direction of the flow path center line 16. It is better to reduce the ratio. By reducing the rate of change in cross-sectional shape in this way, sudden changes in cross-sectional shape are mitigated and pressure loss due to the working fluid is suppressed from occurring in the flow path, so that the working fluid can be efficiently flown into the annular flow. It can be led to the road 11 .

  Incidentally, as one means for determining the shape of the surface S, there is a method using a so-called super ellipse. Here, a plane Sp at an arbitrary point P on the flow path center line 16 is considered, an x-axis is set in the direction of the intersection line L at the point P, and the line Sp included in the plane Sp is perpendicular to the intersection line L. If the y-axis is set, the flow path width Wp is 2a, and the flow path width orthogonal to the flow path width Wp is 2b (a ≧ b), the super ellipse can be expressed by the following equation (1).

  Equation (1) represents an ellipse when the index n is “n = 2”, and a rectangle when “n → ∞ (infinity)”. Therefore, if the cross-sectional shape is determined by increasing the index n from 2 to infinity as it goes from the surface Sa to the surface Se by using this equation (1), the shape conversion from a circle to a rectangle is smoothly performed. Can be done. Note that the method of determining the cross-sectional shape is not limited to using the above-mentioned super ellipse, and can of course be obtained by a computer using a so-called CAD or the like.

  Next, the operation and effect of the axial turbine according to the present embodiment configured as described above will be described.

First, in order to facilitate understanding of the effects of the present embodiment, two types of axial turbines having structures different from those of the present embodiment will be described with reference to FIG.
FIG. 6 is a view showing the vicinity of the distribution chamber of two types of axial flow turbines, which is a comparative example of the first embodiment of the present invention.

  The distribution chamber 60 shown in FIG. 6A is a first comparative example of the present embodiment, and the working fluid is introduced toward the rotational axis O of the turbine rotor 4 as in the present embodiment. The distribution chamber 60 has a plurality of flow dividing plates 61 that disperse the working fluid in a path toward which the working fluid is directed to the annular flow path 11. The flow rate of the introduced working fluid is made uniform. However, in this type of technology, the working fluid is not necessarily uniformly distributed on the surface orthogonal to the flow path center line 62 until the flow distribution plate 61 is installed, and the distribution is not uniform. In consideration of this, it is not sufficient to install the flow dividing plate 61 in order to uniformly introduce the working fluid into the annular flow path 11. Further, depending on the distribution of the flow of the working fluid from the upstream, the flow dividing plate 61 acts as a resistance and the pressure loss increases, and the turbine efficiency may decrease. In addition, it is necessary to form the flow dividing plate 61 as appropriate so that the flow rate introduced into the annular flow path 11 is uniform, and to attach it to the distribution chamber 60 of the axial flow turbine.

  Further, the distribution chamber 70 shown in FIG. 6B is a second comparative example of the present embodiment. Unlike the present embodiment, the distribution chamber 70 introduces the working fluid to a position different from the rotational axis O of the turbine rotor 4. ing. The distribution chamber 70 has an introduction pipe 71 attached so that the flow path center line 72 is displaced from the rotation axis O of the turbine rotor 4. With this structure, the working fluid in the distribution chamber 70 is rotated to the rotation axis. A swirl flow centered on the center O is given, and the working fluid is uniformly introduced into the annular flow path 11. However, since this type of introduction method gives the working fluid a velocity component for swirling the distribution chamber 70, the working fluid flows into the annular flow path 11 as compared with the method shown in FIG. The speed tends to increase, and it is necessary to give sufficient consideration to the control of the inflow speed in order to reduce the pressure loss that occurs when it flows into the annular flow path 11. Further, as shown in the figure, since the working fluid flows into the annular channel 11 at an incident angle α with respect to the tangent line of the annular channel 11, friction with members constituting the channel occurs during the inflow, resulting in pressure loss. Will get bigger.

  In contrast to these comparative examples, the axial flow turbine of the present embodiment includes a bent portion 17 formed such that the flow path center line 16 is changed in a direction orthogonal to the rotational axis O of the turbine rotor 4, and this A distribution portion 18 that is provided continuously with the bending portion 17 and distributes the working fluid to the annular flow path 11, and includes a plane S perpendicular to the flow path center line 16 and a plane U perpendicular to the rotation axis O of the turbine rotor 4. The distribution chamber 20 is formed so that the flow path width W in the direction of the intersection line L is monotonically expanded from the bent portion 17 along the direction of the flow path center line 16.

  In this way, when the distribution chamber 20 is formed so that the flow path width W in the direction of the intersection line L monotonously expands from the point A where the bent part 17 starts to the end point of the flow path center line 16, the bent part is formed. Since the working fluid is diffused in the direction of the flow path width W by the secondary flow vortex 40 (see the arrows shown on each surface S in FIG. 5) generated at 17, the working fluid can be evenly distributed on the surface S. it can. Since the working fluid uniformly distributed on the surface S is introduced into the annular flow path 11 while being distributed in the distribution chamber 20, the configuration as in the comparative example shown in FIG. The working fluid can be introduced into the annular flow path 11 more uniformly as compared with the axial flow turbine comprising the above. Therefore, the turbine efficiency of the axial turbine according to the present embodiment is improved as compared with that shown in FIG.

  Further, the axial turbine according to the present embodiment exhibits its effect without attaching a special member such as the flow dividing plate 61 in the distribution chamber 20, so that pressure loss due to such a member does not occur. Its manufacture is also easy. Further, unlike the axial flow turbine employing the introduction method shown in FIG. 6B, the speed component for swiveling around the rotation axis O is not positively imparted to the working fluid, so the speed of the working fluid increases. It is also possible to suppress the occurrence of pressure loss due to the above.

  In the above description, an axial turbine in which the bent portion 17 of the distribution chamber 20 is connected to the parallel portion 9 of the introduction pipe 8 has been described as an example that exhibits a particularly remarkable effect. The embodiment that can obtain the effects as described above is not limited to this. That is, if an introduction pipe having a flow path center line is provided on a plane including the rotation axis O of the turbine rotor 4 and the flow path center line 16, and the introduction pipe and the distribution chamber 20 are connected via the bent portion 17, Since the distribution chamber in which the flow path width W is enlarged while being bent at the bent portion 17 is configured, the same principle as that of the above embodiment can be applied to the working fluid. Accordingly, the working fluid can be uniformly distributed on the surface S, and the turbine efficiency can be improved.

  In addition, the distribution chamber 20 of the present embodiment is configured such that the flow path width W is maximized in the rotation axis O, but the position where the flow path width W takes the maximum value is different from that of the rotation axis O. Even if the distribution chamber 20 is configured as described above, the working fluid can be uniformly distributed in a plane orthogonal to the flow path center line 16.

  Further, in the above description, the case where the present invention is applied to the turbine (so-called low pressure turbine) constituting the final stage turbine in the thermal power plant has been described, but the upstream side in the working fluid flow direction of the low pressure turbine in the plant. The present invention can also be applied to a distribution chamber of another turbine (so-called high pressure turbine, medium pressure turbine, or the like) provided in the engine.

  Next, embodiments focusing on changes in the flow passage area of the distribution chamber 20 will be described as first and second modifications of the first embodiment of the present invention.

  First, a first modification will be described with reference to FIG.

  In the distribution chamber 20 according to the present embodiment, the flow area of the surface S orthogonal to the flow path center line 16 increases from the connection portion 15 (point A) toward the end point (point F) of the flow path center line 16. It is formed to do. In addition, the other part is comprised similarly to the axial flow turbine of 1st Embodiment, and description of each part is abbreviate | omitted.

  FIG. 7 is a diagram illustrating changes in the flow path area of the distribution chamber 20 according to the present embodiment. The vertical axis of the figure indicates the size of the area, and the area is expressed as a ratio when the area of the surface Sa at the point A on the flow path center line 16 is 1. The horizontal axis in the figure indicates the distance from the point A on the flow path center line 16, and the reference numerals on the horizontal axis correspond to the respective points (points A to E) on the flow path center line 16. Yes.

  In FIG. 7, the flow passage area of the distribution chamber 20 changes so as to expand from the point A toward the downstream side, and the expansion rate decreases as it goes toward the downstream side. When the distribution chamber 20 is configured so that the flow path area changes in this way, the flow rate of the working fluid toward the annular flow path 11 can be gradually reduced, and the momentum of the working fluid in the vicinity of the annular flow path 11 is reduced. be able to. Thereby, when the working fluid flows into the annular flow path 11, it is possible to reduce the application of a speed component that turns around the rotation axis O, and the working fluid is easily introduced into the annular flow path 11 evenly. The turbine efficiency can be further improved.

  Next, a second modification will be described with reference to FIG.

  The present embodiment is an improvement of the first modification described above, and has the same configuration as that of the first modification except for the value of the flow path cross-sectional area of the distribution chamber 20. In the distribution chamber 20 according to the present embodiment, the flow area of the surface S orthogonal to the flow path center line 16 extends from the connection portion 15 where the bent portion 17 starts to the throttle portion 19 along the flow path center line 16. It is formed to have a flow path area T in the throttle portion 19. Here, the channel area T in the throttle unit 19 is an area of a cylindrical channel that can be formed around the rotation axis O of the turbine rotor 4 in the throttle unit 19.

  FIG. 8 is a diagram showing the principle of the present embodiment. In FIG. 8, point G is a point on the flow path center line 16, and the narrowed portion 19 is in contact with the surface Sg formed by this point G. The distribution chamber 20A shown in FIG. 8A is configured so that the area of the surface S does not reach the flow path area T of the throttle portion 19 from the point A to the point G, as shown in FIG. The distribution chamber 20 </ b> B shown is configured such that the area of the surface S reaches the flow path area T of the throttle portion 19 from the point A to the point G.

  When the flow path is configured like the distribution chamber 20A, the flow area immediately before reaching the annular flow path 11 is smaller than the flow path area T of the narrowed portion 19, so that the working fluid is at a smaller angle toward the downstream from the point G. The tendency to flow into the annular flow path 11 becomes strong, and the uniform flow into the annular flow path 11 is suppressed. On the other hand, when the flow path is configured like the distribution chamber 20B, the flow area immediately before reaching the annular flow path 11 becomes larger than the flow path area T of the throttle portion 19, so that the working fluid flows into the annular flow path 11. When flowing in, the tendency to flow toward the rotation axis O (the tendency to flow in at a large angle) becomes strong, and the uniform flow into the annular flow path 11 is promoted.

  Therefore, as in the present embodiment, the flow area of the surface S is equal to the flow area T in the restricting portion 19 from the connecting portion 15 where the bent portion 17 starts to the restricting portion 19 along the flow passage center line 16. If the distribution chamber 20 is formed as described above, the turbine efficiency can be further improved. The area of the surface S from the point A to the point G is preferably larger than the flow path area T of the throttle portion 19, and the larger the area of the surface S, the more uniformly the annular flow path 11 operates. A fluid can be introduced.

  Subsequently, a second embodiment of the present invention will be described with reference to FIGS.

  This embodiment is different from the first embodiment in that the present invention is applied to an axial turbine of a nuclear power plant.

  FIG. 9 is a diagram schematically showing a system of a nuclear power plant having an axial turbine according to a second embodiment of the present invention, and FIG. 10 is a distribution chamber of a low-pressure turbine in the nuclear power plant shown in FIG. It is a figure which shows the vicinity.

  The nuclear power plant shown in FIG. 9 includes a high-pressure turbine 81, two low-pressure turbines 82a and 82b, and two moisture separation heaters 83a and 83b disposed on both sides around the turbines 81, 82a, and 82b. I have. The low-pressure turbine 82a includes a turbine rotor 84a that obtains rotational power by circulating a working fluid in the axial direction. The rotors of the high-pressure turbine 81 and the low-pressure turbine 82b are arranged on the same axis as the turbine rotor 84a.

  The high-pressure turbine 81 is connected to an introduction pipe 85 through which a working fluid (steam) flows and two introduction pipes 86a and 86b. The introduction pipe 85 is connected to a steam generation source (not shown) on the upstream side in the working fluid flow direction, and introduces steam into the high-pressure turbine 81. Steam that has worked in the high-pressure turbine 81 is discharged to the introduction pipes 86a and 86b. The two introduction pipes 86a and 86b are connected to moisture separation heaters 83a and 83b, respectively, on the downstream side in the working fluid flow direction. ing.

  An introduction pipe 87a and an introduction pipe 88a for circulating a working fluid are connected to the moisture separation heater 83a. Similarly, an introduction pipe 87b and an introduction pipe 88b are connected to the moisture separation heater 83b. Yes. The moisture separation heaters 83a and 83b separate moisture contained in the working fluid supplied by the introduction pipes 86a and 86b to remove moisture from the working fluid, and the working fluid from which the moisture has been removed. Is heating up. The working fluid thus heated is introduced into the low-pressure turbines 82a and 82b via the introduction pipes 87a and 87b and the introduction pipes 88a and 88b.

  Inlet pipes 87a and 87b are connected to the low-pressure turbine 82a, and similarly, introduction pipes 88a and 88b are connected to the low-pressure turbine 82b. The introduction pipes 87a and 87b have parallel portions 90a and 90b in which the flow path center line is disposed in parallel with the rotation axis of the turbine rotor 84a in the path from the moisture separators and heaters 83a and 83b to the low pressure turbine 82a. ing. The parallel portions 90a and 90b are connected to the distribution chamber 100a so as to be line symmetric with respect to the rotational axis O of the turbine rotor 84a. Similarly to the introduction pipes 87a and 87b, the introduction pipes 88a and 88b have parallel parts 92a and 92b, and are connected to the distribution chamber 100b via the parallel parts 92a and 92b.

  In FIG. 10, the distribution chamber 100a is connected to two introduction pipes 87a and 87b, and the distribution in the first embodiment is made so that the shape thereof is axisymmetric with respect to the rotational axis O of the turbine rotor 84a. The chamber 20 is configured to have a shape such that two chambers 20 are combined.

  Further, the distribution chamber 100a is connected to the parallel portions 90a and 90b of the introduction pipes 87a and 87b at the connection portions 94a and 94b, and the flow path center lines 95a and 95b are changed in a direction orthogonal to the rotational axis O of the turbine rotor 84a. Bend portions 91a and 91b formed so as to be distributed, distribution portions 96a and 96b which are provided continuously with the bend portions 91a and 91b and which are connected to the annular flow path 11 and distribute the working fluid to the annular flow path 11, and distribution The throttle part 19 is provided in the parts 96a and 96b and arranged on the upstream side in the working fluid flow direction of the annular flow path 11, and narrows the flow path through which the working fluid before flowing into the annular flow path 11 is circulated. These components constitute two flow paths that connect the annular flow paths 11 from the connecting portions 94a and 94b to distribute the working fluid to the annular flow paths 11, respectively. Two flow paths 98a are linked to each other around the 4a, to form a 98b.

  In the flow path 98a, the flow path width W in the direction of the intersection line L between the surface S orthogonal to the flow path center line 96a and the surface orthogonal to the rotational axis O of the turbine rotor 84a is along the direction of the flow path center line 96a. And is formed so as to monotonously expand from the bent portion 91a. Here, since the flow path 98b is configured in the same manner as the flow path 98a, the description thereof is omitted. The distribution chamber 100b is configured in the same manner as the distribution chamber 100a described above, and description of each part is omitted.

  If the axial flow turbine is configured in this way, the present invention can be applied to the case where two introduction pipes are connected to the distribution chamber as described above, and the same effects as those of the first embodiment can be obtained. Obtainable. Needless to say, if the axial turbine is configured as described in the first and second modifications of the first embodiment, the same effects as those can be obtained.

  In this embodiment, the case where two introduction pipes are connected has been described. However, the present invention can also be applied when three or more introduction pipes are connected to the distribution chamber. In such a case, the position where the introduction pipe is connected to the distribution chamber is arranged point-symmetrically with respect to the rotation axis O, and from the connection portion with each introduction pipe toward the annular flow path 11 via the bent portion. Each flow path may be formed so that the flow path width monotonously increases, and the flow paths thus formed may be combined in the vicinity of the turbine rotor to form the distribution chamber.

It is a figure which shows typically the system of the thermal power plant provided with the axial flow turbine which is the 1st Embodiment of this invention. It is a side view of the axial flow turbine which is the 1st embodiment of the present invention. FIG. 3 is an enlarged view of the vicinity of a first stage stationary blade in the axial turbine shown in FIG. 2. It is a figure which shows the distribution chamber vicinity in the axial flow turbine shown in FIG. FIG. 3 is a perspective view of the vicinity of a distribution chamber in the axial flow turbine shown in FIG. 2. It is a figure which shows the distribution chamber vicinity of two types of axial flow turbines which are the comparative examples of the 1st Embodiment of this invention. It is a figure showing the change of the flow-path area of the distribution chamber 20 of the axial flow turbine which is the 1st modification of the 1st Embodiment of this invention. It is a figure which shows the principle of the 2nd modification of the 1st Embodiment of this invention. It is a figure which shows typically the system of the nuclear power plant provided with the axial flow turbine which is the 2nd Embodiment of this invention. It is a figure which shows the distribution chamber vicinity of the axial flow turbine which is the 2nd Embodiment of this invention.

Explanation of symbols

L Intersection line O between plane S and plane U Rotational axis S Surface T orthogonal to flow path center line 16 Flow path area U in throttle portion 19 Surface W orthogonal to rotational axis O Channel width 3 in the direction of intersection L Low pressure turbine 4 Turbine rotor 8 Introduction pipe 9 Parallel part 11 Annular flow path 13 Outer casing 14 Flow path center line 15 Connection part 16 Flow path center line 17 Bending part 18 Distribution part 19 Restriction part 20 Distribution chamber 22 Moving blade row 24 Stator blade Row 82 Low-pressure turbine 87 Introduction pipe 90 Parallel part 91 Bent part 95 Channel centerline 96 Distribution part 98 Channel 100 Distribution chamber

Claims (12)

In an axial flow turbine that obtains rotational power by flowing a working fluid in the axial direction of the turbine rotor,
A casing that covers the turbine rotor from an outer peripheral side of the turbine rotor and forms an annular flow path for flowing a working fluid to and from the turbine rotor;
An introduction pipe which is a flow path for circulating a working fluid introduced into the annular flow path;
A bent portion connected to the introduction pipe and formed so that a flow path center line is changed in a direction orthogonal to the rotation axis of the turbine rotor, and connected to the annular flow path provided continuously with the bent portion And a distribution chamber having a distribution part for distributing the working fluid to the annular flow path,
The bent portion is connected to the introduction pipe so that the direction of the flow path center line in the connection portion with the introduction pipe matches the direction of the flow path center line of the introduction pipe in the connection portion,
In the distribution chamber, the flow path width in the direction of the intersection of the plane orthogonal to the flow path center line of the distribution chamber and the plane orthogonal to the rotation axis of the turbine rotor is in the direction of the flow path center line of the distribution chamber. An axial flow turbine characterized by being formed so as to monotonically expand from a connection portion with the introduction pipe at the bent portion . In an axial flow turbine that obtains rotational power by flowing a working fluid in the axial direction of the turbine rotor,
A casing that covers the turbine rotor from an outer peripheral side of the turbine rotor and forms an annular flow path for flowing a working fluid to and from the turbine rotor;
An introduction pipe that circulates the working fluid introduced into the annular flow path, the flow path center line having a parallel portion arranged in parallel with the rotation axis of the turbine rotor;
A bent portion connected to the parallel portion of the introduction pipe and formed so that a flow path center line is changed in a direction orthogonal to the rotation axis of the turbine rotor, and the annular flow provided continuously with the bent portion. A distribution chamber having a distribution portion connected to the channel and distributing the working fluid to the annular flow path,
The bent portion is connected to the introduction pipe so that the direction of the flow path center line in the connection portion with the introduction pipe matches the direction of the flow path center line of the introduction pipe in the connection portion,
In the distribution chamber, the flow path width in the direction of the intersection of the plane orthogonal to the flow path center line of the distribution chamber and the plane orthogonal to the rotation axis of the turbine rotor is in the direction of the flow path center line of the distribution chamber. An axial flow turbine characterized by being formed so as to monotonically expand from a connection portion with the introduction pipe at the bent portion . In an axial flow turbine that obtains rotational power by flowing a working fluid in the axial direction of the turbine rotor,
A casing that covers the turbine rotor from an outer peripheral side of the turbine rotor and forms an annular flow path for flowing a working fluid to and from the turbine rotor;
An introduction pipe which is a flow path for circulating a working fluid introduced into the annular flow path;
A bent portion connected to the introduction pipe and formed so that a flow path center line is changed in a direction perpendicular to the rotation axis of the turbine rotor, and connected to the annular flow path provided continuously with the bent portion. A distribution portion that distributes the working fluid to the annular flow path, and a distribution chamber that is provided in the distribution section and has a throttle portion disposed on the upstream side in the working fluid flow direction of the annular flow path,
The bent portion is connected to the introduction pipe so that the direction of the flow path center line in the connection portion with the introduction pipe matches the direction of the flow path center line of the introduction pipe in the connection portion,
In the distribution chamber, the flow path width in the direction of the intersection of the plane orthogonal to the flow path center line of the distribution chamber and the plane orthogonal to the rotational axis of the turbine rotor is along the direction of the flow path center line of the distribution chamber. monotonously expanding from the connection portion between the inlet pipe in the bend portion Te and the diaphragm until the flow passage area of the plane perpendicular to the channel center line of the distribution chamber reaches the narrowed portion from the bent portion An axial turbine characterized by being formed so as to have a flow path area in the section. The axial turbine according to claim 1,
In the distribution chamber, the flow path width in the direction of the intersection of the plane orthogonal to the flow path center line of the distribution chamber and the plane orthogonal to the rotation axis of the turbine rotor is in the direction of the flow path center line of the distribution chamber. An axial flow turbine is formed so as to monotonously extend from a connection portion of the bent portion with the introduction pipe to a rotation axis of the turbine rotor. The axial turbine according to claim 1,
The flow path area of the surface perpendicular to the flow path center line of the distribution chamber is such that the rotation axis of the turbine rotor is connected to the introduction pipe at the bent portion along the flow path center line of the distribution chamber. The axial turbine is characterized by continuously expanding to the point. The axial turbine according to claim 1,
The cross-sectional shape when the distribution chamber is cut along a plane orthogonal to the flow path center line includes a first cross-sectional shape at the connection portion with the introduction pipe and a second cross-section at the turbine rotor shaft center side with respect to the connection portion. It differs from the shape,
The axial flow turbine is characterized in that the distribution chamber is formed such that the cross-sectional shape gradually changes from the first cross-sectional shape to the second cross-sectional shape along a flow path center line . The axial turbine according to claim 1,
An axial flow turbine comprising a plurality of the introduction pipes. The axial turbine according to claim 7, wherein
The plurality of introduction pipes are connected to the distribution chamber so as to be symmetrical with respect to the rotation axis of the turbine rotor,
The distribution chamber is a plurality of flow paths that are connected to the annular flow path from respective connection portions with the plurality of introduction pipes, and a plurality of flow paths that distribute the working fluid to the annular flow path are provided in the turbine rotor. Formed around,
Each of the plurality of channels has a channel width in an intersecting direction of a surface orthogonal to each channel center line and a surface orthogonal to the rotation axis of the turbine rotor in the direction of the channel center line of the distribution chamber. The axial flow turbine is formed so as to monotonously expand from the connection portion with the introduction pipe at the bent portion . The axial turbine according to claim 1,
The axial flow turbine characterized in that the rotational axis of the turbine rotor is arranged on the same line as the rotational axis of another turbine rotor. The axial turbine according to claim 9, wherein
The turbine rotor constitutes a final stage turbine. The axial turbine according to claim 1,
The turbine rotor has a plurality of blade rows that are symmetrically formed toward both ends of the turbine rotor with respect to the position of the distribution chamber. In the inlet structure of an axial flow turbine that obtains rotational power by flowing a working fluid in the axial direction of the turbine rotor,
A casing that covers the turbine rotor from an outer peripheral side of the turbine rotor and forms an annular flow path for flowing a working fluid to and from the turbine rotor;
An introduction pipe which is a flow path for circulating a working fluid introduced into the annular flow path;
A bent portion connected to the introduction pipe and formed so that a flow path center line is changed in a direction orthogonal to the rotation axis of the turbine rotor, and connected to the annular flow path provided continuously with the bent portion And a distribution chamber having a distribution part for distributing the working fluid to the annular flow path,
The bent portion is connected to the introduction pipe so that the direction of the flow path center line in the connection portion with the introduction pipe matches the direction of the flow path center line of the introduction pipe in the connection portion,
In the distribution chamber, the flow path width in the direction of the intersection of the plane orthogonal to the flow path center line of the distribution chamber and the plane orthogonal to the rotation axis of the turbine rotor is in the direction of the flow path center line of the distribution chamber. An inlet structure for an axial-flow turbine, wherein the bent portion is formed so as to monotonously expand from a connection portion with the introduction pipe at the bent portion .

Images