JP4557787B2 - Steam turbine - Google Patents

Description

  The present invention relates to a steam turbine, and more particularly, to a steam turbine in which a turbine exhaust chamber for supplying turbine exhaust after completion of expansion work to a condenser is improved.

Improving the thermal efficiency of steam turbines used in thermal power generation, etc. is an extremely important issue that leads to the reduction of carbon dioxide (CO ₂ ) emissions, energy savings, and advancement of technology associated with effective use of limited energy. It has become.

  Even if the improvement in the thermal efficiency of a steam turbine is to convert all the given energy into mechanical work, there are actually some internal losses, and it is important to reduce these internal losses. It is the key.

  The internal loss of the steam turbine includes the blade type loss due to the blade shape, the secondary flow loss of the steam, the leakage loss of the steam, the turbine cascade loss based on the wetness loss of the steam, the steam valve and the crossover pipe (steam Loss of accessories such as supply pipes) and turbine exhaust loss due to the turbine exhaust chamber.

  Among these losses, the turbine exhaust loss accounts for a very large proportion of 10% to 20% of the total internal loss.

  Turbine exhaust loss is a loss that occurs between the outlet of the final stage of the turbine and the inlet of the condenser, and is broken down into a leaving loss, a hood loss, an annular area limiting loss, and a turn-up loss.

  Of these, the hood loss is a pressure loss from the turbine exhaust chamber to the condenser inlet, and greatly depends on the type, shape, and size of the turbine exhaust chamber.

  In general, the pressure loss increases with the square of the flow velocity. Therefore, it is effective to reduce the flow velocity by increasing the exhaust size within the allowable range. However, the exhaust size is limited by the cost and the size of the building. .

  The hood loss also depends on the axial flow velocity, that is, the volume flow through the turbine exhaust chamber.

  FIG. 14 is a loss diagram in which the relationship between turbine exhaust loss and axial flow velocity is combined with its breakdown loss.

  The hood loss depends on the design of the turbine exhaust chamber including the diffuser, but the turbine low pressure exhaust chamber occupies a very large capacity in the entire steam turbine. For this reason, in order to reduce the hood loss, it is necessary to design a turbine exhaust chamber having a small size within an allowable range.

  FIG. 12 shows an example of a so-called double flow type (opposite flow type) low-pressure steam turbine in which two turbine stages most frequently used in a thermal power plant or the like are accommodated in one turbine casing. .

The low-pressure steam turbine includes an outer casing upper half 1a ₁ and an inner casing upper half 1b ₁ which are divided into two parts with a transverse center line H as a boundary, an outer casing lower half 1a ₂ and an inner casing lower and a half 1b _2, are so-called double-turbine casing structure.

The low-pressure steam turbine having a double turbine casing structure includes a connecting pipe 3 such as a crossover pipe connected to the steam inlet portion 2 located on the head side of the longitudinal center line V, intersects the steam inlet portion 2 and crosses the steam inlet portion 2. A double flow type in which a turbine rotor 4 extending along a plane center line H is accommodated, and steam flows between the turbine rotor 4 and the upper half 1b ₁ of the inner casing and the lower half 1b ₂ of the inner casing. The steam passages 5a and 5b are formed.

  In the double flow type steam passages 5 a and 5 b, a turbine stage 8 a in which turbine nozzles 6 a and turbine rotor blades 7 a arranged in an annular row along the circumferential direction of the turbine rotor 4 are combined is provided in the axial direction of the turbine rotor 4. It is provided over a plurality of paragraphs.

Of the turbine stage 8a provided over a plurality, it referred to the first paragraph which combines a turbine nozzle 6a ₁ and the turbine moving blade 7a ₁ and turbine first stage 8a _1, a turbine nozzle 6a ₂ and the turbine rotor blades 7a the final paragraph of a combination of a ₂ referred to as the turbine final stage 8a _2.

The outlet side of the turbine final stage 8a ₂ is composed of a steam guide 9 provided at the top thereof and a route flow guide 10 provided at the root thereof, which is used as a guide passage for the turbine exhaust 11 having finished the expansion work. A curved diffuser 12 and a bearing cone 14 that covers a bearing 13 that pivotally supports the turbine rotor 4 are provided. The diffuser 12 and the bearing cone 14 communicate with a turbine exhaust chamber 15 that collects and inverts the turbine exhaust 11 from the turbine final stage 8a ₂ and guides it to a condenser (not shown).

The turbine exhaust chamber 15 is surrounded by an outer casing upper half 1a ₁ having an upper half keel rib 16a and an outer casing lower half 1a ₂ having a lower half keel rib 16b to form a wide space. The turbine exhaust 11 flowing from the diffuser 12 to the outer casing upper half 1a ₁ is reversed, and the inverted turbine exhaust 11 is merged with the turbine exhaust 11 flowing from the diffuser 12 to the outer casing lower half 1a ₂ and the merged Turbine exhaust is supplied to a condenser (not shown).

In the steam turbine including the turbine exhaust chamber 15 having such a configuration, for example, main steam (driving steam) supplied from the communication pipe 3 such as a crossover pipe is divided into the left and right turbine first paragraphs 8a ₁ and 8a _1. After expanding through the turbine final paragraphs 8a ₂ and 8a ₂ , the flow rate is reduced by the curved diffuser 12 formed by the steam guide 9 and the bearing cone 14 as the turbine exhaust 11, After the pressure is restored, a condenser (not shown) that turns downward in a space surrounded by the outer casing upper half 1a ₁ and the outer casing lower half 1a ₂ and is located at the lower part of the turbine exhaust chamber 15 (not shown). ).

  FIG. 13 is a front cross-sectional view of the low-pressure steam turbine shown in FIG. 12 cut from the direction of arrows AA.

  In the turbine exhaust chamber 15 of the low-pressure steam turbine shown in FIG. 13, as main structural members, an upper half keel rib 16a, a lower half keel rib 16b, a central partition plate 17, a front partition plate 18a, and a rear partition plate. 18b, a standing plate 19 and the like are provided, and resists an external force such as atmospheric pressure acting on the vacuum in the room from the outside by these structural members.

  Further, in the turbine exhaust chamber 15, the turbine exhaust 11 flowing out from the diffuser 12 toward the outer casing upper half 1 a 1 side is smoothly reversed and guided to the condenser, and a communication pipe (crossover) An upper half flow guide (flow channel plate) 20 is provided so as not to collide with the tube 3 and take the heat of the steam before expansion.

  As described above, the conventional steam turbine is provided with a number of structural members to sufficiently resist the external force from the outside against the vacuum in the turbine exhaust chamber 15 to ensure the strength and smooth flow of the turbine exhaust. Yes.

  By the way, the steam turbine shown in FIGS. 12 and 13 decelerates the turbine exhaust 11 in the diffuser 12 in order to reduce the loss (static pressure loss) of the turbine exhaust 11 flowing in the turbine exhaust chamber 15. It is important to restore static pressure.

  In order to sufficiently restore the static pressure with the diffuser 12, it is necessary to take a sufficiently long steam guide 9, expand a gentle flow passage area, and suppress separation of the flow of the turbine exhaust 11. .

  However, the turbine casing 1 constituting the turbine exhaust chamber 15 cannot sufficiently secure the length of the steam guide 9 due to restrictions such as a large number of structural members as described above.

  Further, the diffuser 12 causes the turbine exhaust 11 flowing from the upper half part and the turbine exhaust 11 flowing from the lower half part to interfere with each other, or a drift caused by the interference occurs, making the flow unstable. Therefore, it was not sufficient to restore the static pressure, which was a factor in increasing exhaust loss.

As one method for solving such a problem, for example, as seen in Patent Document 1, the lower half of the flow guide is longer than the upper half of the flow guide. As can be seen, it has been proposed that the outlet opening be provided with a flow guiding element that extends beyond the outlet opening diameter.
Japanese Patent Laid-Open No. 11-2000814 Japanese translation of PCT publication No. 2002-510769

In the conventional steam turbine shown in FIG. 12 and FIG. 13, the length of the bell mouth type (trumpet type) steam guide 9 arranged symmetrically about the turbine rotor (turbine shaft) 4 is set to the upper and lower sides of the outer casing. The dimensions of the half parts 1a ₁ and 1a ₂ and the upper and lower half keel ribs 16a and 16
Due to restrictions such as the arrangement of structural members, etc., it cannot be secured sufficiently long.

  For this reason, the length of the diffuser 12 cannot be ensured sufficiently long, and sufficient static pressure recovery is not performed, which causes a large exhaust loss.

  Further, the diffuser 12 shown in FIGS. 12 and 13 includes an upper half portion and a lower half portion, and the flow of the turbine exhaust 11 differs between the upper half portion and the lower half portion, so that a uniform flow can be ensured. It was difficult and caused a large exhaust loss, and some improvement was required.

  The present invention has been made based on such circumstances, and when exhausting the turbine exhaust that has finished the expansion work from the turbine exhaust chamber to the condenser, the pressure (static pressure) of the turbine exhaust is recovered to a higher level. An object of the present invention is to provide a steam turbine with improved turbine exhaust performance.

  In order to achieve the above object, a steam turbine according to the present invention has a turbine casing formed in a double structure of an outer casing and an inner casing as described in claim 1, and the outer casing is centered in a transverse direction. The inner casing is divided into an outer casing upper half and an outer casing lower half, and the inner casing is also divided at a transverse center to form an inner casing upper half and an inner casing lower half, while the inner casing A steam turbine having a turbine exhaust chamber surrounded by the outer casing and the bearing cone on the outlet side of the diffuser, the steam guide having a steam guide, a route flow guide and a diffuser composed of a bearing cone on the outlet side of the diffuser; Cross the center with the upper half steam guide and lower half steam guide The split and divided upper half steam guide is formed in an expanded shape from the upper half steam guide inlet edge line toward the upper half steam guide outlet edge line, while the divided lower half steam guide is The lower half steam guide outlet edge line is formed to expand from the half steam guide inlet edge line toward the lower half steam guide outlet edge line, and the lower half steam guide outlet edge line is expanded from the transverse center toward the bottom side. The inclined outlet edge line extending to the bottom and the bottom outlet edge line are connected by a curved outlet edge line.

Further, in order to achieve the above-mentioned object, the steam turbine according to the present invention has a lower half steam guide outlet edge line from the transverse center to the inclined outlet edge line and the curved outlet edge line. the height position to connecting the door and H _1, when the height to the bottom edge line and H ₀ from the transverse center, the lower half of a steam guide outlet edge line height ratio H _{1 /} H _0, H It is set within the range of ₁ / H ₀ = 0.7 to 1.0.

In order to achieve the above-mentioned object, the steam turbine according to the present invention has a lower half steam guide outlet edge line having an outer casing lower half width of W ₀ and an inclination as described in claim 3. when the bottom outlet edge line width at a position connecting the outlet edge line and the curved outlet edge line and W _1, the lower half of a steam guide outlet edge line width ratio _{W 1 / W 0, W 1} / W 0 ≦ 0 .9 range.

  In order to achieve the above object, the steam turbine according to the present invention includes a support member as described in claim 4.

  Moreover, in order to achieve the above-described object, the steam turbine according to the present invention is configured such that, as described in claim 5, the support member includes an inclined outlet edge line and a bottom outlet of the lower half steam guide outlet edge line. It is installed in a region surrounded by the edge line and the curved outlet edge line.

  Moreover, in order to achieve the above-mentioned object, the steam turbine according to the present invention includes a tongue piece as described in claim 6.

  In order to achieve the above-mentioned object, the steam turbine according to the present invention has a spread angle θ as described in claim 7 where the spread angle of the left and right distribution with respect to the longitudinal center is θ. Is set in a range of θ ≦ 120 °.

  Moreover, in order to achieve the above-mentioned object, the steam turbine according to the present invention is such that the tongue piece is provided on the lower half steam guide outlet edge line as described in claim 8.

  In order to achieve the above object, the steam turbine according to the present invention has a shape in which the tongue piece extends obliquely forward and upward from the lower half steam guide outlet edge line as described in claim 9. It is a thing.

  In order to achieve the above object, the steam turbine according to the present invention applies the upper half steam guide and the lower half steam guide according to claim 1 to the low-pressure steam turbine as described in claim 10. It is characterized by doing.

  In order to achieve the above object, the steam turbine according to the present invention is characterized in that, as described in claim 11, the low-pressure steam turbine according to claim 10 is a double flow type. is there.

  The steam turbine according to the present invention divides the steam guide into an upper half steam guide and a lower half steam guide, and divides the lower half steam guide outlet edge line of the divided lower half steam guide from the transverse center. Since the curved outlet edge line connects the inclined outlet edge line that extends in an expanding manner toward the bottom side and the bottom outlet edge line that is parallel to the transverse center, so that the wet area of the turbine exhaust can be secured more widely. More stable pressure of the turbine exhaust can be recovered to maintain a stable flow of the turbine exhaust.

  DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment of a steam turbine according to the present invention will be described with reference to the drawings and reference numerals attached to the drawings.

  FIG. 1 is a longitudinal sectional view showing a first embodiment of a steam turbine according to the present invention.

The steam turbine according to the present embodiment is applied to a low-pressure steam turbine whose steam flow is a double flow type (counter flow type), and an outer casing having a turbine casing 21 divided into two with a transverse center line _H00 as a boundary. This is a so-called double turbine casing structure including an upper half 21a ₁ and an inner casing upper half 21b ₁ , an outer casing lower half 21a ₂ and an inner casing lower half 21b ₂ .

A steam turbine having a double turbine casing structure is accommodated in a space surrounded by an upper half 21b ₁ and a lower half 21b _{2 of the} inner casing, and extends in the axial direction along the transverse center line H _00. Turbine shaft) 22 is provided.

Steam passages 23 a and 23 b formed between the turbine rotor 22 and the inner casing upper half 21 b ₁ and the inner casing lower half 21 b ₂ are connected to a turbine nozzle 24 a arranged in an annular row with respect to the turbine rotor 22 and turbine operation. A turbine stage 26a configured by combining with the blades 25a is provided.

Of the turbine stage 26a provided over a plurality, it referred to the first turbine stage of a combination of a turbine nozzle 24a ₁ and the turbine rotor blade 25a ₁ and turbine first stage 26a _1, the turbine nozzle 24a ₂ and the turbine rotor blades 25a the final turbine stage of a combination of a ₂ referred to as the turbine final stage 26a _2.

_On the outlet side of the turbine final stage 26a2, there are an upper half steam guide 27a and a lower half steam guide 27b provided on the upper side and the lower side thereof, and an upper half route flow provided on the root side thereof. An upper half diffuser 30a, a lower half diffuser 30b, and a turbine rotor, which are composed of a guide 28a and a lower half route flow guide 28b and are used as a guide passage for the turbine exhaust 29 that has finished expansion work. An upper half bearing cone 32a and a lower half bearing cone 32b are provided so as to cover the bearing 31 supporting the shaft 22.

Vertical halves diffuser 30a, 30b and the upper and lower halves bearing cone 32a, and 32b, the turbine final turbine exhaust 29 from paragraph 26a ₂ was collected inverted one place, condenser and turbine exhaust 29 is inverted (Fig. The upper half turbine exhaust chamber 33a and the lower half turbine exhaust chamber 33b are communicated with each other.

Vertical halves turbine exhaust chamber 33a, each of 33b, the outer casing upper half 21a ₁ having a upper half keel ribs 34a, at each outer casing lower half portion 21a ₂ having a lower half of the keel rib 34b enclosed by a wide space portion is formed, the turbine exhaust 29 flowing on the half 21a ₁ outer casing is inverted over the upper half flow guide 38 from the lower half diffuser 30a, the lower the turbine exhaust 29 is inverted The turbine exhaust 29 flowing from the half diffuser 30b to the lower half 21a ₂ of the outer casing is merged, and the merged turbine exhaust is supplied to a condenser (not shown).

In the steam turbine including the upper and lower half turbine exhaust chambers 33a and 33b having such a configuration, for example, main steam (driving steam) supplied from the communication pipe 35 such as a crossover pipe is the left and right turbine first paragraphs 26a ₁ , 26a ₁ is divided to perform expansion work, and after passing through the respective turbine final stages 26a ₂ and 26a ₂ , the turbine exhaust 29 is formed by upper and lower half steam guides 27a and 27b and upper and lower half bearing cones 32a and 32b. curved widening shape of the upper and lower halves diffuser 30a has, subtracting the flow rate 30b, allowed to recover the static pressure, after having provided in a space surrounded by the outer casing upper half portion 21a ₁ and the outer casing lower half portion 21a ₂ It turns downward through the half flow guide 38 and flows to a condenser (not shown) located at the lower part of the lower half turbine exhaust chamber 33b. To.

In addition, on the bottom side of the lower half 21a ₂ of the outer casing, a lower half rib rib 34b, a front partition 37a, a rear partition 37b, a central partition 36, and a vertical plate 39 are provided to push outside air pressure and the like. The room is protected so as to sufficiently resist pressure.

Further, as shown in FIG. 2, the turbine cross the center line H ₁₁ outer casing upper half 21a ₁ and the inner casing halves 21b ₁ the boundary of the center O through across the rotor 22 and the outer casing lower half section 21a ₂ and a steam turbine having a turbine casing 21 which is a two piece structure with an inner casing lower half portion 21b ₂ is steam guide half on the steam guide 27 in a boundary crossing centerline H ₁₁ 27a and the lower half portion steam guide 27b And divided into two.

  The upper half steam guide 27a is formed in a so-called bell mouth expanding curve from the upper half steam guide inlet edge line 40a toward the lower half steam guide outlet edge line 41a.

Further, the lower half steam guide 27b is formed in an expanded shape from the lower half steam guide inlet edge line 40b toward the lower half steam guide outlet edge line 41b, and the lower half steam guide outlet edge line 41b is formed. , an inclined outlet edge lines 42 extending in expanding shape toward the bottom side of the transverse center line H _11, have a shape that connects a curved exit edge line 44 and a parallel bottom outlet edge line 43 to the transverse centerline H ₁₁ .

In this case, the lower half portion steam guide outlet edge line 41b of the lower half of the steam guide 27b is the height at the position M connecting the transverse center line H ₁₁ and the inclined outlet edge line 43 and the curved outlet edge lines 44 H ₁ and then, when the height of the bottom outlet edge line 43 and _{H 0} from the transverse center line _{H 11,} the lower half of a steam guide outlet edge line height ratio _{H 1 / H 0, H 1} / H 0 = 0. It is set in the range of 7 to 1.0.

The lower half portion steam guide outlet edge line 41b of the lower half of the steam guide 27b, the bottom at the position M of the lower outer casing half width W _0, connecting the inclined outlet edge line 42 and the curved outlet edge line 44 When the outlet edge line width W ₁ is set, the lower half steam guide outlet edge line width ratio W ₁ / W ₀ is set in a range of W ₁ / W ₀ ≦ 0.9.

FIG. 3 is a turbine exhaust chamber pressure loss diagram in which the vertical axis represents the turbine exhaust chamber pressure loss, and the horizontal axis represents the lower half steam guide outlet edge line height ratio. From this diagram, the lower half steam the guide exit edge line height ratio _H 1 / _{H 0,} is set in the range of H ₁ / H 0 = 0.7~1.0, the pressure loss of the turbine exhaust, it was confirmed that less.

  FIG. 4 is a turbine exhaust chamber pressure loss diagram in which the vertical axis represents the turbine exhaust chamber pressure loss and the horizontal axis represents the lower half steam guide outlet edge line width ratio.

From this graph, it is confirmed that if the lower half steam guide outlet edge line width ratio W ₁ / W ₀ is set in the range of W ₁ / W ₀ ≦ 0.9, the pressure loss of the turbine exhaust will be reduced. It was.

Thus, in the present embodiment, the steam guide 27 is divided into the upper half steam guide 27a and the lower half steam guide 27b, and the lower half steam guide outlet edge line of the lower half steam guide 27b. 41b and an inclined outlet line 42 extends expanding shape toward the bottom side of the transverse center line H _11, a shape connecting the parallel bottom outlet edge line 43 to the transverse center line H ₁₁ in a curved exit edge line 44 On the other hand, the lower half steam guide outlet edge line height ratio H ₁ / H ₀ is set in the range of H ₁ / H ₀ = 0.7 to 1.0, and the lower half steam guide outlet edge line width ratio W _{Since 1} / W ₀ is set in the range of W ₁ / W ₀ ≦ 0.9, respectively, it is possible to secure a wider wet area of the turbine exhaust and recover more turbine exhaust pressure (static pressure). .

  FIG. 5 is a cross-sectional view showing a second embodiment of the steam turbine according to the present invention.

  In addition, the same code | symbol is attached | subjected to the same component as the component of 1st Embodiment, and duplication description is abbreviate | omitted.

This embodiment, like the first embodiment, the steam guide 27 and the center upper part steam guide 27a and the lower half portion steam guide 27b a transverse centerline H ₁₁ as a boundary through across the turbine rotor 22 Of the two divided steam guides 27, the lower half steam guide 27b is formed in an expanded shape from the lower half steam guide inlet edge line 40b toward the lower half steam guide outlet edge line 41b, down half steam guide outlet edge line 41b, curved inclined outlet edge lines 42 extending in expanding shape toward the bottom side of the transverse center line H _11, and a bottom outlet edge line 43 parallel to the transverse centerline H ₁₁ While supporting the lower half steam guide 27b in strength while supporting the supporting member 45, the inclined outlet edge line 42, the curved outlet edge line 44, and the bottom outlet edge line 43, while forming the shape connected by the outlet edge line 44. But on the area enclosed.

  Other components are the same as those in the first embodiment.

  Thus, in the present embodiment, the support portion 45 is provided in the region surrounded by the inclined outlet edge line 42, the curved outlet edge line 44, and the bottom outlet edge line 43 of the lower half steam guide 27b. When the reversing turbine exhaust that is reversed from the guide 27a and flows along the upper half flow guide 38 and the turbine exhaust from the lower half steam guide 27b merge, they interfere with each other and drift, and vibration based on the drift occurs. Even in such a case, the lower half steam guide 27b can be maintained in a stable state with sufficient resistance against external forces such as vibration while maintaining a high strength guarantee.

  FIG. 7 is a perspective view showing an embodiment of a steam guide applied to the steam turbine according to the present invention. FIG. 6 is a perspective view showing a conventional steam guide for comparison with the steam guide shown in FIG.

Conventional steam guide 27 shown in FIG. 6, the upper and lower halves steam guide inlet lip line 40a while the two-piece structure of the upper half steam guide 27b and the lower half portion steam guide 27b as a boundary crossing centerline H ₁₁ vertical from 40b halves steam guide outlet edge line 41a, and the enlarging shape toward the 41b, while forming the axially symmetrical transverse centerline H _11, steam guide according to the present embodiment shown in FIG. 7 27, similarly to the above, while the two-piece structure of the upper half steam guide 27a and the lower half portion steam guide 27b as a boundary crossing centerline H _11, the upper and lower halves steam guide inlet lip lines 40a, 40b of the Each of the upper and lower half steam guide outlet edge lines 41a and 41b is expanded toward each other, while a tongue piece 46 is provided on the lower half steam guide outlet edge line 41b. It is intended.

Tongue 46 provided on the lower half steam guide outlet edge line 41b, compared longitudinal center line V _11, the tongue拡Ri angle theta of the right and left distribution, is set to θ ≦ 120 °.

  Further, the tongue piece 46 is formed in a shape extending from the lower half steam guide outlet edge line 41b toward the front oblique upper side.

10 takes the pressure (static pressure) in the lower half of a steam guide outlet edge line on the vertical axis, the lower relative transverse centerline H ₁₁ on the horizontal axis halves steam guide outlet edge line angular position taken was conventional lower half It is a pressure distribution comparison diagram which compares the pressure distribution of a part steam guide, and the pressure distribution of the lower half part steam guide which concerns on this embodiment.

  8 shows the pressure position along the lower half steam guide outlet edge line 41b in the conventional lower half steam guide 27b, and FIG. 9 shows the lower half of the lower half steam guide 27b according to the present embodiment. The pressure position along the steam guide outlet edge line 41b and the tongue piece outlet edge line 47 is shown.

  From the pressure distribution comparison diagram comparing the pressure distribution of the conventional lower half steam guide shown in FIG. 10 with the pressure distribution of the lower half steam guide according to the present embodiment, the tongue 46 is placed on the lower half steam guide 27b. It was confirmed that the present embodiment provided with a higher pressure (static pressure) than the conventional one recovered.

  FIG. 11 is a pressure distribution diagram in which the vertical axis represents the pressure (static pressure) at the lower half steam guide outlet edge line and the horizontal axis represents the tongue piece spreading angle θ of the lower half steam guide.

  From this pressure distribution diagram, it was found that the tongue (spreading angle θ) of the lower half steam guide was set within the range of θ ≦ 120 °, and the pressure (static pressure) increased and recovered.

Thus, the present embodiment is lower provided with a tongue 46 in the upper half steam guide outlet edge line 41b, the tongue spread the right and left distribution for longitudinal centerline V ₁₁ of the tongue 46 of the lower half of a steam guide 27b Since the angle θ is set within the range of θ ≦ 120 °, the turbine exhaust pressure (static pressure) can be recovered to a higher level and the turbine exhaust can be maintained in a stable flow.

1 is a longitudinal sectional view showing a first embodiment of a steam turbine according to the present invention. Sectional drawing cut | disconnected seen from the BB arrow direction of FIG. In the first embodiment of the steam turbine according to the present invention, a turbine exhaust chamber pressure loss diagram when the lower half steam guide outlet edge line height ratio is changed. In the first embodiment of the steam turbine according to the present invention, a turbine exhaust chamber pressure loss diagram when the lower half steam guide outlet edge line width ratio is changed. Front sectional drawing which shows 2nd Embodiment of the steam turbine which concerns on this invention. The schematic perspective view which shows the conventional steam guide. The schematic perspective view which shows the steam guide applied to the steam turbine which concerns on this invention. The figure which shows the pressure position along the lower half steam guide exit edge line in the conventional lower half steam guide. The figure which shows the pressure position which follows the lower half steam guide exit edge line and tongue piece exit edge line in a lower half steam guide among the steam guides applied to the steam turbine which concerns on this invention. The pressure distribution comparison diagram which compares the pressure distribution of the conventional lower half steam guide with the pressure distribution of the lower half steam guide in the steam guide applied to the steam turbine which concerns on this invention. The pressure distribution diagram which shows the pressure distribution with respect to a tongue piece spreading angle when a tongue piece is provided in the lower half steam guide exit edge line of the steam guide applied to the steam turbine which concerns on this invention. The longitudinal cross-sectional view which shows the conventional steam turbine. Sectional drawing cut | disconnected from the AA arrow direction of FIG. The turbine exhaust loss diagram showing the breakdown of the turbine exhaust loss.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Turbine casing 1a ₁ Outer casing upper half 1a ₂ Outer casing lower half 1b ₁ Internal casing upper half 1b ₂ Inner casing lower half 2 Steam inlet 3 Connection pipe 4 Turbine rotor 5a, 5b Steam passages 6a, 6a ₁ , 6a ₂ turbine nozzles 7a, 7a ₁ , 7a ₂ turbine blades 8a turbine stage 8a ₁ turbine first stage 8a ₂ turbine final stage 9 steam guide 10 route flow guide 11 turbine exhaust 12 diffuser 13 bearing 14 bearing cone 15 turbine exhaust chamber 16a Upper half keel rib 16b Lower half keel rib 17 Central divider 18a Front divider 18b Rear divider 19 Standing plate 20 Upper half flow guide 21 Turbine casing 21a ₁ External casing upper half 21a ₂ External casing lower half 21b ₁ on the inner casing halves 2 b ₂ inner casing lower half portion 22 turbine rotor 23a, 23b the steam passage 24, 24a _1, 24a ₂ the turbine nozzle 25, 25a _1, 25a ₂ turbine blade 26 turbine stage 26a ₁ turbine first stage 26b ₂ turbine final stage 27 Steam guide 27a Upper half steam guide 27b Lower half steam guide 28a Upper half flow guide 28b Lower half flow guide 29 Turbine exhaust 30a Upper half diffuser 30b Lower half diffuser 31 Bearing 32a Upper half bearing cone 32b Lower half bearing Cone 33a Upper half turbine exhaust chamber 33b Lower half turbine exhaust chamber 34a Upper half keel rib 34b Lower half keel rib 35 Connecting pipe 36 Central partition portion 37a Front partition portion 37b Rear partition portion 38 Upper half flow guide 39 Standing board 40a Upper half steel Guide inlet edge line 40b Lower half steam guide inlet edge line 41a Upper half steam guide outlet edge line 41b Lower half steam guide outlet edge line 42 Inclined outlet edge line 43 Bottom outlet edge line 44 Curved outlet edge line 45 Support member 46 Tongue 47 Tongue Exit Line

Claims (11)

A turbine casing is formed in a double structure of an outer casing and an inner casing, and the outer casing is divided at a transverse center to form an upper half of the outer casing and a lower half of the outer casing, and the inner casing also has a transverse center. The inner casing upper half and the inner casing lower half are formed, while the inner casing has a diffuser composed of a steam guide, a route flow guide and a bearing cone on the outlet side of the inner casing. In a steam turbine having a turbine exhaust chamber surrounded by the outer casing and the bearing cone, the steam guide is divided into an upper half steam guide and a lower half steam guide at a transverse center, and the divided upper half steam is divided. The upper half steam guide from the upper half steam guide entrance edge line The divided lower half steam guide is formed in an open shape toward the lower half steam guide outlet edge line from the lower half steam guide inlet edge line. In addition, the lower half steam guide outlet edge line is formed by connecting the inclined outlet edge line and the bottom outlet edge line extending in a widening shape from the transverse center toward the bottom side by a curved outlet edge line. Steam turbine. The lower half steam guide outlet edge line has a height from the transverse center to a position connecting the inclined outlet edge line and the curved outlet edge line as H _1, and a height from the transverse center to the bottom edge line as H ₀ . to time, the lower half of a steam guide outlet edge line height ratio _H 1 / _{H 0,} of claim 1, wherein the set in the range of H ₁ / H 0 = 0.7~1.0 Steam turbine. The lower half steam guide outlet edge line has a lower half width when the lower half width of the outer casing is W ₀ and the bottom outlet edge line width at the position connecting the inclined outlet edge line and the curved outlet edge line is W _1. The steam turbine according to claim 1, wherein the partial steam guide outlet edge line width ratio W ₁ / W ₀ is set in a range of W ₁ / W ₀ ≦ 0.9. The steam turbine according to claim 1, wherein the lower half steam guide includes a support member. 5. The steam turbine according to claim 4, wherein the supporting member is installed in a region surrounded by the inclined outlet edge line, the bottom outlet edge line, and the curved outlet edge line in the lower half steam guide outlet edge line. The steam turbine according to claim 1, wherein the lower half steam guide includes a tongue piece. The steam turbine according to claim 6, wherein the tongue piece has a spread angle θ set in a range of θ ≦ 120 °, where θ is a spread angle of left and right distribution with respect to the longitudinal center. The steam turbine according to claim 6, wherein the tongue piece is provided on a lower half steam guide outlet edge line. The steam turbine according to claim 6, wherein the tongue piece has a shape extending from the lower half steam guide outlet edge line toward the diagonally upper front side. A steam turbine, wherein the upper half steam guide and the lower half steam guide according to claim 1 are applied to a low pressure steam turbine. The low-pressure steam turbine according to claim 10 is a double flow type steam turbine.

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