JP2017002838A - Turbine inlet structure and steam turbine using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a turbine inlet structure capable of correcting ununiformity of peripheral distribution of flow flowing from the inside of an axial flow turbine inlet structure into the initial stage of a turbine, and thereby improving turbine plant efficiency, and provide a steam turbine using the turbine inlet structure.SOLUTION: On a turbine inlet structure, on the outer peripheral surface side of a turbine inlet lower half part 19 of an annular flow passage, formed is a convex member 50 projecting to an inner peripheral side so that the flow passage area of the annular flow passage is made narrower and then wider from a steam introduction part toward the side opposite to the steam introduction part.SELECTED DRAWING: Figure 12

Description

  The present invention relates to a turbine inlet structure and a steam turbine using the same.

  Generally, an axial turbine has a turbine rotor in which a plurality of rotating blade rows are attached in the axial direction, and an annular flow path formed by stationary blade rows on the outer periphery of the turbine rotor. A shaft driving force is obtained by causing the working fluid to flow through the annular flow path and then rotating the turbine rotor with the fluid force applied to the rotating blade row.

  Among such axial flow turbines, for example, in a steam turbine, there is a system in which a working fluid flows at a right angle toward the rotational axis of the turbine rotor in the turbine inlet structure. Also, in the turbine inlet structure called double flow type, the steam supplied from the steam supply pipe through the throttle duct is divided into two in the circumferential direction inside, and the annular flow of the turbine stage installed on both sides in the turbine axial direction. Leading to the road.

  In order to improve the efficiency of the axial flow turbine, it is important to allow the working fluid to uniformly flow into the annular flow path, and there are various inlet structures of the axial flow turbine having a function of guiding the working fluid to the annular flow path. Are devised.

  For example, when a double-flow turbine inlet structure is used for a low-pressure turbine of a steam turbine, a plurality of flow-dividing plates are installed in order to equalize the flow of steam inside the turbine inlet, so that the low-pressure turbine first stage stationary blade can be divided. Techniques have been proposed for making the circumferential distribution of the incoming steam flow uniform (see Patent Document 1).

  Alternatively, there has also been proposed a technique for uniformly flowing the working fluid into the annular flow path by forming a flow path from the steam supply pipe to the throttle duct so that its cross-sectional area changes monotonously (patent) Reference 2 etc.).

  Alternatively, the steam inlets are arranged on opposite sides of the turbine casing, and the upper and lower casing flow paths are configured so that the cross section decreases in a substantially circumferential direction as the distance from the steam inflow section increases. A technique has also been proposed in which a plurality of flow guides are provided so that steam flows substantially inward in the radial direction around the flow path so as to allow the working fluid to uniformly flow into the annular flow path (see Patent Document 3, etc.). .

JP-A-9-158703 JP 2008-38741 A JP 2003-193809 A

  As a cause of the non-uniformity of the working fluid flowing into the annular flow path at the turbine inlet, generally, separation of the flow at a position from the steam supply pipe through the throttle duct to the inside of the inlet flow path can be considered.

  However, a more serious problem arises when the working fluid does not bisect in the left and right directions in the circumferential direction when flowing into the inlet, but swirls around the rotor from one inlet. In this state, the substantial flow path area at the entrance of the inlet is almost halved and the flow velocity increases, which not only increases the mixing loss, but also the flow at the entrance of the turbine greatly deviates from the direction of the stationary blades. End up. For this reason, the loss inside a turbine will also increase.

  A technique for installing a guide plate is known as means for correcting such uneven distribution in the circumferential direction of the flow flowing into the first stage of the turbine (for example, Patent Document 1). However, the flow inside the turbine inlet has a velocity of about several tens of m / s although the flow velocity is lower than that in the turbine stage, and the density is low, so that the difference between the inflow angle and the angle formed by the guide plate is large (for example, 15 It is easily separated at the tip of the guide plate. In addition, the structure is not designed to prevent turning. Therefore, it is not easy to obtain a desired effect simply by installing a guide plate. In addition, installing a plurality of guide plates in the mainstream increases unnecessary frictional resistance and further increases material costs and production costs.

  In addition, as described in Patent Document 2, when the method of forming the flow path from the steam supply pipe to the throttle duct so that the cross-sectional area changes monotonously, the separation of the flow is surely suppressed. Although it is possible to make the flow uniform, there is a problem in terms of manufacturing cost and manufacturing accuracy because the flow path shape cannot be manufactured by simple plate bending or the like. Also, this is not a structure that takes into consideration the prevention of turning.

  On the other hand, as described in Patent Document 3, by adopting a method of arranging the steam inlet on both side surfaces facing the turbine casing and forming the internal flow path so as to adjust the flow path cross-sectional area, Furthermore, when a plurality of flow guides are installed, it is possible to achieve uniform flow because it is possible to suppress swirling inflow at the same time as the flow separation. However, since the internal structure is complicated, there are problems in terms of manufacturing costs, and since multiple guide plates are installed in the mainstream, unnecessary frictional resistance is increased, resulting in loss reduction. there is a possibility.

  The present invention relates to a turbine inlet structure capable of correcting the non-uniform distribution of the circumferential direction of the flow flowing from the inside of the axial flow turbine inlet structure into the first stage of the turbine and improving the turbine plant efficiency, and a steam turbine using the turbine inlet structure I will provide a.

In order to solve the above problems, for example, the configuration described in the claims is adopted.
The present invention includes a plurality of means for solving the above-described problems. To give an example, the working fluid introduction part connected to the downstream side in the fluid flow direction of the piping for supplying the working fluid, and a part of the outer peripheral side Is a turbine inlet structure of a turbine having an annular flow path connected to the working fluid introduction portion and having an inner circumferential side connected to a turbine stage inlet, and the internal flow path of the turbine inlet is seen in the direction in which the rotor shaft extends. In some cases, the annular channel is configured to expand after the channel area becomes narrower from the working fluid introduction part toward the opposite side of the working fluid introduction part.

  According to the present invention, it is possible to suppress the generation of a swirling flow that flows in while largely swirling around the rotor from one inlet without substantially increasing the flow resistance inside the turbine inlet structure by inexpensive shape improvement. Accordingly, it is possible to improve the efficiency of the turbine plant by promoting the uniform distribution in the circumferential direction of the flow flowing into the first stage of the turbine.

It is a distribution diagram showing the basic structure of a steam turbine typically. It is side surface sectional drawing which represented roughly the basic structure of the turbine inlet_port | entrance part of a steam turbine. FIG. 3 is an enlarged view of a portion near a turbine stage inlet surrounded by a dotted circle in FIG. 2. It is a front view of the low-pressure turbine inlet part of a common steam turbine. It is a perspective view of the low-pressure turbine inlet part of a common steam turbine. It is a side view of the low-pressure turbine inlet part of a common steam turbine. It is the figure which showed typically the mode of the flow field in the ideal state in the low pressure turbine inlet part of a general steam turbine with the line showing a streamline. It is the figure which showed typically the mode of the pressure field corresponding to the flow field of FIG. 7 with the shading shading. It is the figure which showed typically the mode of the flow field which flows in in the low pressure turbine inlet part of a common steam turbine, turning in around the stage inlet part in one direction, and showing the streamline. It is the figure which showed typically the mode of the pressure field corresponding to the flow field of FIG. 9 with the shading of shading. It is the front view which represented typically the structure of the turbine inlet_port | entrance part which concerns on Example 1 of this invention. It is the perspective view which represented typically the structure of the turbine inlet_port | entrance part which concerns on Example 1 of this invention. It is the side view which represented typically the structure of the turbine inlet_port | entrance part which concerns on Example 1 of this invention. It is the figure which showed typically the mode of the flow field in the turbine inlet part which concerns on Example 1 of this invention with the line showing a streamline. It is the figure which showed typically the mode of the pressure field corresponding to the flow field of FIG. 14 with the shading of shading. It is the front view which represented typically the structure of the turbine inlet_port | entrance part which concerns on Example 2 of this invention. It is the front view which represented typically the structure of the turbine inlet_port | entrance part which concerns on Example 3 of this invention. It is the side view which represented typically the other structure of the turbine inlet_port | entrance part of this invention. It is the side view which represented typically the other structure of the turbine inlet_port | entrance part of this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings as appropriate in an example in which steam is used as a working fluid and a steam turbine is used as a turbine. In addition, the same code | symbol is attached | subjected to the equivalent component through each drawing.

<Example 1>
A turbine inlet structure and a steam turbine according to a first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a system diagram schematically showing the basic structure of a steam turbine.

  As shown in FIG. 1, in a steam turbine, steam pressurized and heated by a steam generator (not shown) such as a boiler is sent to a high-pressure turbine 4 through a main steam supply pipe 2. The steam that has worked in the high-pressure turbine 4 is heated again by the reheater 3 and then sent to the intermediate-pressure turbine 5. In the present embodiment, the intermediate pressure turbine 5 has a double flow structure, and the steam flowing from the turbine inlet 10 at the center of the intermediate pressure turbine casing is divided into the front and rear in the turbine axial direction (left and right in the figure). The turbines are rotated in separate paragraphs of intermediate pressure turbines 5a, 5b to perform work.

  The steam discharged from the intermediate pressure turbine 5 passes through a crossover pipe (communication pipe) 8 and is sent to the low pressure turbines 6a and 6b. In the example of FIG. 1, the low-pressure turbines 6 a and 6 b are also a double-flow type, and as with the intermediate-pressure turbine 5, the steam flowing from the turbine inlet structure 11 at the center of the low-pressure turbine casing is front and rear in the turbine axial direction (left and right in the figure). ) And work in the paragraphs of the different low-pressure turbines 6a and 6b.

  The high-pressure turbine 4, the intermediate-pressure turbine 5, the low-pressure turbine 6 a, and the low-pressure turbine 6 b are mechanically connected by a rotatable turbine rotor 1, and rotating work is converted into electric power by a generator 7 connected to the turbine rotor 1. Convert. Steam discharged from the low-pressure turbines 6a and 6b is introduced into a condenser (not shown) installed further downstream, where it is condensed to condensate, recirculated to the steam generator, and heated again. It is sent to the high pressure turbine 4.

  Here, the turbine inlet structure of the present invention is intended for the inlet portion of the intermediate pressure turbine and the inlet portion of the low pressure turbine in the steam turbine. In this embodiment, an example applied to the inlet portion of the low pressure turbine will be described. In addition, although the example of the double flow type | mold intermediate pressure turbine as shown in FIG. 1 was used as a basic structure of the present steam turbine, since this invention can be applied independently to a low pressure turbine inlet part, a high intermediate pressure integrated type etc. Of course, the present invention can be applied to other types of steam turbines. Further, the present invention can be applied to a turbine having a similar inlet structure other than the steam turbine.

  Next, a basic structure of a turbine inlet portion of a general double-flow type low-pressure turbine will be described with reference to FIGS. FIG. 2 is a side cross-sectional view schematically showing the basic structure of the turbine inlet of the steam turbine. FIG. 3 is an enlarged view of the vicinity of the turbine stage inlet surrounded by a circle indicated by a dotted line A in FIG.

  As shown in FIGS. 2 and 3, the turbine inlet 111 of the low-pressure turbine is provided near the center of the low-pressure casing 6 in the turbine axial direction, and is connected to the end of the crossover pipe 8 via the flange portion 14. From the cylindrical tube 15 which becomes the root part of the throat immediately below the part 14, the cross section thereof is gradually flattened and flattened downward. The inside of the turbine inlet 111 is an annular passage formed by the turbine inlet upper half 118 and the turbine inlet lower half 119 including the throttle passage.

  A paragraph inlet cover 31 constituting a paragraph inlet (turbine inlet central portion) 30 is provided on the outer peripheral side of a diaphragm fixing member 32 that is formed in a semicircular shape in the turbine circumferential direction, and forms a throttle channel. The diaphragm fixing member 32 is fixed to the wall surface of the inlet that forms the turbine inlet upper half 118.

  A low pressure turbine first stage diaphragm 33 is attached to the inner peripheral side of the diaphragm fixing member 32. A plurality of stationary blades 35 are attached to the low-pressure turbine first stage diaphragm 33 in the turbine circumferential direction. A plurality of rotor blades 36 are provided in the turbine circumferential direction on the downstream side of the stationary blade 35, and the rotor blades 36 are fixed to the turbine rotor 1 provided at the center of the turbine inlet so as to be rotatable along the turbine axial direction. Has been.

  4 to 6 show a low-pressure turbine inlet of a general steam turbine, and correspond to a front view, a perspective view, and a side view in order.

  As shown in these drawings, a steam inlet 16 for guiding the steam guided in the direction of arrow 12 from the crossover pipe 8 to the stage inlet 30 is provided in the turbine inlet 111 of the low-pressure turbine. The steam introducing portion 16 is connected to the outer peripheral surface side of the annular flow path formed by the turbine inlet upper half 118 and the turbine inlet lower half 119. The stage inlet 30 is connected to the inner peripheral surface side of the annular flow path formed by the turbine inlet upper half 118 and the turbine inlet lower half 119, and the rotor is disposed inside the stage inlet 30.

  A turbine inlet upper half 118 and a turbine inlet lower half 119 that form an annular flow path are connected via a flange portion 20. As shown in FIG. 3, a paragraph inlet cover 31 is provided at the paragraph inlet 30 between the turbine inlet upper half 118 and the turbine inlet lower half 119, thereby forming a throttle channel. The inner peripheral side of the paragraph inlet cover 31 is formed in a cavity and constitutes a paragraph inlet 30 communicating with the paragraphs of the low-pressure turbines 6a and 6b.

  The cross section of the turbine inlet 111 viewed from the turbine axial direction gradually expands downward from the cylindrical tube 15 and gradually shrinks again from below from the flange 20 that joins the upper and lower halves of the turbine inlet. Have Further, in the low pressure turbine exemplified in the present embodiment, the vertical cross section passing through the center of the crossover pipe 8 and the vertical cross section passing through the center of the turbine shaft coincide. Therefore, the turbine inlet 111 has a symmetrical structure when viewed from the turbine axial direction.

  The turbine inlet 111 is a kind of pressure vessel because high-pressure steam flows in, and a force to expand outwardly by the internal pressure works. In order to resist this, ribs 21 having a circular cross section as a reinforcing member that reinforces the structural strength of the turbine inlet 111 are provided at or around the stage inlet cover 31 at regular intervals along the stage inlet. Several are arranged.

  Next, in order to facilitate understanding of the effects of the present embodiment, the flow structure at the turbine inlet of a general turbine will be described with reference to FIGS. 7 to 10 as a comparative example. FIG. 7 is a diagram schematically showing a state of a flow field in an ideal state at a low-pressure turbine inlet of a general steam turbine with lines representing streamlines.

  As shown in FIG. 7, under ideal conditions, the steam 12 flowing into the turbine inlet 111 is spread across the axis of the rotor 1 so as to spread over the entire internal flow path of the pear-shaped turbine inlet 111. Inflow from both sides. In this case, since the flow is divided into two and spreads, the average flow velocity is effectively reduced, and loss generation can be suppressed to a low level.

  Because there are wall friction loss and mixing loss as the main loss generation mechanism in the piping, both increase in proportion to the square of the flow velocity, so reducing the average flow velocity directly leads to loss reduction It is.

  The state of the pressure field corresponding to the flow field in FIG. 7 is schematically shown in shaded shades in FIG. Here, the difference in pressure is roughly shown in four levels of shading. The lightest color area indicates the low pressure area 43, the area where the pressure is higher than the low pressure area 43 is the medium pressure areas 44 a and 44 b in the light color order, and the darkest color area indicates the high pressure area 45.

  The flow inside the turbine inlet of a low-pressure turbine is generally about 0.1 to 0.2 in terms of Mach number, and can be regarded as an incompressible fluid. Therefore, in general, the pressure is low in a region where the flow velocity is relatively higher than the surroundings, and the pressure is high in a region where the flow velocity is low. Further, if the flow path space (flow path cross-sectional area) is the same, the smaller the volume flow rate, the lower the flow velocity. There is a paragraph inlet 30 in the center of the low-pressure turbine inlet 111, and the steam, which is a working fluid, sequentially flows into the inlet, so that the volume flow rate in the flow path decreases toward the downstream side. Therefore, in the case of such a flow field, the flow velocity is the lowest and the pressure is the highest at the lowest position of the pear shape (FIG. 8).

  On the other hand, the actual turbine has a symmetric flow as shown in FIG. 7 such as load fluctuation, structural asymmetry of the upstream / downstream flow path section, and steam mixing from the branch pipe to the crossover pipe 8. There are various factors that break down. For this reason, the flow field is not always symmetrical as shown in FIG. 7, and it is considered that the flow rate balance of the left and right flow paths frequently fluctuates.

  By the way, once the flow is deviated to one side of the left and right flow paths of the turbine inlet upper half 118, the flow rate on the deviated side is relatively increased and the flow is accelerated, so the pressure is lowered. Further, when flowing into the paragraph on the way, the flow is throttled by the paragraph inlet cover 31 at the paragraph inlet portion, so that the flow becomes partially faster and a low pressure region is created.

  Here, the driving force of the flow basically has an inertial force and a pressure difference, and the direction of the flow is determined by the balance between them. When the inertial force is not outstanding, the pressure generally flows from a higher pressure to a lower pressure.

  In an incompressible flow, if the flow accelerates or the material decreases, that is, the flow rate decreases, the pressure there will be lower than the surroundings. However, since the working fluid flows into the paragraph in the vicinity of the paragraph inlet, the flow rate is reduced compared to the surroundings, and the pressure is also lowered. As a result, a low pressure region 43 is formed as shown in the left channel portion of FIG. 10, and a pressure gradient of high, medium, and low is promoted. For this reason, it becomes easier to flow to the side where the flow is more uneven.

  Further, the working fluid that has flown in one direction in the left and right flow paths of the turbine inlet upper half 118 gradually flows after passing through the lower end of the turbine inlet lower half 119 while turning around the axis of the rotor 1. Therefore, on the downstream side, the flow velocity is further lowered and the pressure is increased. Finally, all the working fluid flows into the turbine stage in the process of making a round around the axis of the rotor 1. At this time, a high pressure region 45 is formed on the other side of the left and right flow paths of the turbine inlet upper half 118. Since the high pressure region 45 acts as a breakwater for the working fluid flowing in this direction, a large swirl flow around the axis of the rotor 1 as shown in FIG. 9 is stably formed.

  That is, in the turbine inlet 111 of a general low-pressure turbine as shown in FIG. 4, the flow field as shown in FIG. 7 is not a stable equilibrium state but rather an unstable equilibrium state. Therefore, if there is an opportunity to generate instability, it is considered that the flow field is more easily shifted to a more stable flow field as shown in FIG. And when it transfers to the stable flow field as shown in FIG. 9, it will hardly occur to return to the flow field as shown in FIG. For this reason, the non-uniformity in the circumferential distribution of the flow flowing from the turbine inlet structure into the first stage of the turbine is not eliminated, and it is difficult to improve the turbine plant efficiency.

  The state of the steam flow shown in FIGS. 7 to 10 is based on knowledge obtained from the results of CFD (Computational Fluid Dynamics) analysis.

  Based on the above, a turbine inlet structure 11 according to an embodiment of the present invention will be described below.

  11 to 13 are diagrams schematically showing the structure of the turbine inlet portion according to the first embodiment of the present invention, and correspond to a front view, a perspective view, and a side view, respectively, in order.

  As described above, in a general turbine inlet structure, if there is a factor that breaks the left-right symmetry of the flow when viewed in the axial direction of the rotor 1, the non-uniformity that easily swivels around the axis of the rotor 1 easily It is considered that a steam flow is generated, which is a factor in reducing turbine efficiency.

  On the other hand, in the turbine inlet structure of the low-pressure turbine of this embodiment, the turbine inlet upper half 18 and the turbine inlet lower half 19 are connected via a flange 20 to form an annular flow path. An inlet cover is provided, a throttle channel is configured, a steam inlet 16 is connected to the outer peripheral surface side of the annular channel, and a paragraph inlet 30 is provided on the inner peripheral surface side of the annular channel. Are connected to each other, and the inner peripheral side of the paragraph inlet cover is formed into a cavity, and the paragraph inlet 30 communicating with the paragraphs of the low-pressure turbines 6a and 6b constitutes the general turbine inlet described above. It is almost the same as the structure.

  In addition, as shown in FIGS. 11 to 13, the turbine inlet structure of the low-pressure turbine of the present embodiment is arranged so that the steam inlet is opposed to the steam inlet on the outer peripheral surface side of the turbine inlet lower half 19 of the annular channel. A convex member 50 protruding toward the inner peripheral side is formed so as to expand toward the side after the flow passage area of the annular flow passage becomes narrower. That is, the flow path space in the vicinity of the outer peripheral surface facing the steam introduction part surrounded by the left and right convex members 50 of the turbine inlet lower half 19 is wider than the flow path space on both sides in the circumferential direction. Steam contraction / expansion channels are formed on the left and right of the lower part of the channel.

  When viewed from a direction parallel to the axis of the rotor 1, the convex member 50 is parallel to the outer peripheral wall so as to uniformly reduce the flow path area and then widen it as shown in FIGS. 12 and 13. Projecting to the inner peripheral surface side.

  For this reason, the flow velocity once increases at the convex member 50, and the flow velocity falls in the wide space surrounded by the convex member 50 formed at a position facing the steam introduction portion. In other words, the pressure once decreases at the portion of the convex member 50, and the pressure also increases at the wide space surrounded by the convex member 50 formed at a position facing the steam introducing portion. Accordingly, the pressure in the expanded space portion is increased, and a high pressure region 45 is formed at the lowermost end portion of the pear shape. This high pressure region acts as a wall against the flow from both sides of the high pressure region, and acts to suppress the generation of a flow field that passes through the wall and swirls greatly inside the low pressure inlet. Therefore, as shown in FIG. 14, as a result, a flow field close to ideal conditions as shown in FIG. 7 can be realized.

  As described above, the turbine inlet structure of the present embodiment is devised based on the knowledge obtained from the CFD analysis result, and the effect can be expected more reliably than the conventional technology.

  In addition, since the turbine inlet structure of the present embodiment is configured by simple plate bending and a few additional internal members, the manufacturing cost can be suppressed to the same level as a general turbine inlet structure. is there. In addition, since the flow velocity at the place where the flow is accelerated or decelerated due to the structure of the present embodiment is originally slow, the increase in mixing loss or the like is slight.

  Therefore, according to the present embodiment, an inexpensive shape improvement can suppress a large swirl flow around the axis of the rotor 1 inside the steam turbine inlet structure without substantially increasing the flow resistance inside the steam turbine inlet structure. it can. Therefore, it is possible to suppress the non-uniform circumferential distribution of the flow flowing into the first stage of the turbine, and to reduce the pressure loss in the turbine inlet and the loss occurring in the subsequent stage, thereby improving the turbine plant efficiency. Can do.

<Example 2>
Embodiment 2 of the present invention and the steam turbine will be described with reference to FIG. FIG. 16 is a front view schematically showing the basic structure of the turbine inlet portion according to the second embodiment of the invention. In this figure, portions corresponding to the same portions as those in the previous drawings are denoted by the same reference numerals and description thereof is omitted, and the same applies to the following embodiments.

  As shown in FIG. 16, in the turbine inlet portion 11A of the present embodiment, when realizing the same features as in the first embodiment, the outer peripheral surface is on the inner peripheral side without installing the convex member 50 inside the flow path. The recessed concave portion 51 is directly formed by processing the outer peripheral side wall surface of the turbine inlet lower half portion 19A.

  The configuration other than the concave portion 51 is substantially the same as the turbine inlet structure of the first embodiment described above, and details are omitted.

  In the turbine inlet structure and the steam turbine according to the second embodiment of the present invention, the same effects as those of the above-described turbine inlet structure and the steam turbine according to the first embodiment using the same can be obtained.

<Example 3>
A turbine inlet structure and a steam turbine according to a third embodiment of the present invention will be described with reference to FIG. FIG. 17 is a front view schematically showing the basic structure of the turbine inlet portion according to the third embodiment of the invention.

  As shown in FIG. 17, in the turbine inlet portion 11B of the present embodiment, in realizing the same characteristics as in the first embodiment, the convex member 50 is not installed inside the flow path in the turbine inlet lower half portion 19B. When the internal flow path of the turbine inlet is viewed in the direction in which the axis of the rotor 1 extends, the flow path space in the vicinity of the outer peripheral surface facing the steam inlet is wider than the flow path space on both sides in the circumferential direction. As described above, the annular flow path is formed so that the area decreases from the steam introduction portion toward the opposite side, and has a shape having a convex portion 52 that protrudes to the outer peripheral side on the opposite side.

  The other configuration is substantially the same as the turbine inlet structure of the first embodiment described above, and details are omitted.

  In the third embodiment of the turbine inlet structure and the steam turbine according to the present invention, the same effects as those of the first embodiment of the turbine inlet structure and the steam turbine described above can be obtained.

<Others>
In addition, this invention is not limited to said Example, Various modifications are included. The above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Also, a part of the configuration of a certain embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of a certain embodiment. Moreover, it is also possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  For example, the wall surface shapes shown in FIGS. 11, 16, and 17 are merely examples of the shape, and are not necessarily limited to the shape itself. For example, when the convex member as in the first embodiment is taken as an example, when viewed from a direction parallel to the axis of the rotor, as shown in FIG. 12 and FIG. As shown in FIGS. 18 and 19, when viewed from a direction parallel to the axis of the rotor, the shape of the curve is curved with respect to the outer peripheral wall. Convex members 50a and 50b may be formed.

  Further, the flow field does not necessarily have to be as shown in FIGS. 14 and 15, and the flow area near the lower end is small so that the high pressure region is stably formed at the lower end of the pear shape.・ It should be configured as wide and narrow.

  Further, the flow path area is narrow / wide is not limited to the turbine inlet lower half 19, but the flow path area may be narrow / wide at the turbine inlet upper half 18, or the turbine inlet upper half From the portion 18 to the turbine inlet lower half 19, the flow path area may be narrow or wide.

1 ... turbine rotor,
2 ... main steam supply piping,
3 ... Steam reheating equipment,
4 ... High-pressure turbine,
5 ... Medium pressure turbine,
6a, 6b ... low pressure turbine,
7 ... Generator,
8 ... Crossover tube,
10: Medium pressure turbine inlet,
11, 11A, 11B ... low pressure turbine inlet,
12. Steam flow,
14 ... Low pressure turbine inlet flange,
15 ... Cylindrical tube,
16 ... steam introduction part,
18 ... Upper half of turbine inlet,
19, 19A, 19B ... lower half of turbine inlet,
20 ... flange,
21 ... ribs,
30 ... Paragraph inlet (low pressure turbine first paragraph inflow part),
31 ... Paragraph entrance cover,
32 ... Diaphragm fixing member,
33 ... First paragraph diaphragm of low-pressure turbine,
35 ... Low pressure turbine first stage rotor blade,
36 ... First stage rotor blade of low-pressure turbine,
41 ... streamlines,
43. Low pressure region,
44a, 44b ... medium pressure region,
45 ... high pressure region,
50, 50a, 50b ... convex member,
51 ... concave part,
52 ... Convex part.

Claims (6)

A working fluid introduction section connected to the downstream side in the fluid flow direction of the piping supplying the working fluid;
A turbine inlet structure of a turbine provided with a part of the outer peripheral side connected to the working fluid introduction part and an annular flow path connected to the turbine stage inlet on the inner peripheral side,
When the internal flow path at the turbine inlet is viewed in the direction in which the rotor shaft extends, the annular flow path expands after the flow path area becomes narrower from the working fluid introduction portion toward the opposite side of the working fluid introduction portion. A turbine inlet structure characterized by being configured as follows. The turbine inlet structure according to claim 1, wherein
The annular flow path has a turbine inlet upper half connected to the working fluid introduction part, and a turbine inlet lower half arranged on the opposite side of the working fluid introduction part,
A turbine inlet structure characterized by being configured to expand after the flow passage area of the annular flow passage becomes narrower in the lower half of the turbine inlet. The turbine inlet structure according to claim 1 or 2,
The said annular flow path has the convex-shaped member which protrudes in an inner peripheral side in the outer peripheral surface side between the said opposing sides from the said working fluid introduction part. The turbine inlet structure characterized by the above-mentioned. The turbine inlet structure according to claim 1 or 2,
The annular flow path has a concave portion with an outer peripheral surface recessed toward an inner peripheral side between the working fluid introduction portion and the facing side. The turbine inlet structure according to claim 1 or 2,
The annular flow path is formed so that an area decreases from the working fluid introduction portion toward the opposite side, and has a convex portion protruding to the outer peripheral side on the opposite side. Construction.   A steam turbine comprising the turbine inlet structure according to any one of claims 1 to 5.

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