Steam turbine exhaust chamber cooling device and steam turbine

Abstract

A steam turbine exhaust chamber cooling device includes a plurality of spray nozzles, and the plurality of spray nozzles inject spray water from an injection port to the turbine exhaust chamber. Here, a center line of the injection port is inclined with respect to a radial direction of a turbine rotor so that the plurality of spray nozzles inject the spray water in a direction counter to a rotation direction of the turbine rotor. An inclination angle at which the center line of the injection port is inclined to a forward side of the rotation direction with respect to the radial direction of the turbine rotor is in a relationship represented by the following formula (A),
2545(A).

Claims

1. A steam turbine exhaust chamber cooling device for supplying spray water to a turbine exhaust chamber to which steam is exhausted from a turbine stage inside a casing housing a turbine rotor, the device comprising: a plurality of spray nozzles each having a respective injection port for injecting the spray water to the turbine exhaust chamber, wherein at a cross section of a vertical plane orthogonal to a rotation axis of the turbine rotor, a respective center line of a respective injection port is inclined with respect to a radial direction of the turbine rotor, the radial direction connecting the respective injection port with the rotation axis of the turbine rotor, so that the plurality of spray nozzles inject the spray water in a direction counter to a rotation direction of the turbine rotor; and inclination angles at which the center lines of all the injection ports are inclined to a forward side of the rotation direction with respect to the radial direction of the turbine rotor are in a relationship represented by a following formula (A),
2545(A).

2. The steam turbine exhaust chamber cooling device according to claim 1, wherein the plurality of spray nozzles include: a first spray nozzle located more upward than the turbine rotor and placed more forward in the rotation direction of the turbine rotor than a partition plate placed along a vertical plane passing through a rotation axis of the turbine rotor; and a second spray nozzle located more upward than the turbine rotor and placed more backward than the partition plate in the rotation direction of the turbine rotor, and in the rotation direction of the turbine rotor, a mounting angle 1 from the vertical plane passing through the rotation axis of the turbine rotor to a position where the injection port of the first spray nozzle is mounted and a mounting angle 2 from the vertical plane passing through the rotation axis of the turbine rotor to a position where the injection port of the second spray nozzle is mounted are in a relationship represented by a following formula (B),
1<2(B).

3. A steam turbine comprising the steam turbine exhaust chamber cooling device according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a view illustrating a substantial part of a steam turbine according to a first embodiment.

(2) FIG. 2 is a view illustrating flow of spray water S5 which a steam turbine exhaust chamber cooling device 5 supplies to a turbine exhaust chamber K2 in the steam turbine according to the first embodiment.

(3) FIG. 3 is a view illustrating the flow of the spray water S5 which the steam turbine exhaust chamber cooling device 5 supplies to the turbine exhaust chamber K2 in the steam turbine according to the first embodiment.

(4) FIG. 4 is a view illustrating the flow of the spray water S5 which the steam turbine exhaust chamber cooling device 5 supplies to the turbine exhaust chamber K2 in the steam turbine according to the first embodiment.

(5) FIG. 5 is a view illustrating a substantial part of a steam turbine according to a second embodiment.

(6) FIG. 6 is a view illustrating flow of spray water S5 which a steam turbine exhaust chamber cooling device 5 supplies to a turbine exhaust chamber K2 in the steam turbine according to the second embodiment.

(7) FIG. 7 is a view illustrating a substantial part of a steam turbine according to a modification example of the second embodiment.

(8) FIG. 8 is a diagram illustrating the relationship (temperature distribution) between a temperature T of steam which flows through a rotor blade at a final stage and a position H in a radial direction and the relationship (flow rate distribution) between a flow rate FR of the steam which flows through the rotor blade at the final stage and the position H in the radial direction in a steam turbine according to a related art.

(9) FIG. 9 is a view illustrating a substantial part of the steam turbine according to the related art.

(10) FIG. 10 is a view illustrating a substantial part of the steam turbine according to the related art.

(11) FIG. 11 is a view illustrating a substantial part of the steam turbine according to the related art.

(12) FIG. 12A is a diagram for describing a counter flow area in the steam turbine according to the related art.

(13) FIG. 12B is a diagram for describing the counter flow area in the steam turbine according to the related art.

(14) FIG. 13A is a diagram for describing swirling flow (swirl) in the steam turbine according to the related art.

(15) FIG. 13B is a diagram for describing the swirling flow (swirl) in the steam turbine according to the related art.

(16) FIG. 14 is a diagram illustrating the relationship between a pressure difference P (supply water pressure), which is a difference between pressure of water supplied to a spray nozzle 51 (supply water pressure) and pressure at an outlet portion of the spray nozzle 51 (outlet pressure), and a water droplet diameter Rd of the spray water S5 injected from the spray nozzle 51 in the steam turbine according to the related art.

(17) FIG. 15 is a diagram illustrating the relationship between a position H of the rotor blade in the radial direction and the water droplet diameter Rd of the spray water S5 and the relationship between the position H of the rotor blade in the radial direction and a heat exchange rate in the steam turbine according to the related art.

(18) FIG. 16 is a view illustrating flow of the spray water S5 which a steam turbine exhaust chamber cooling device 5 supplies to a turbine exhaust chamber K2 in the steam turbine according to the related art.

DETAILED DESCRIPTION

(19) A steam turbine exhaust chamber cooling device of an embodiment supplies spray water to a turbine exhaust chamber to which steam is exhausted from a turbine stage inside a casing housing a turbine rotor. The steam turbine exhaust chamber cooling device includes a plurality of spray nozzles, and the plurality of spray nozzles inject the spray water from an injection port to the turbine exhaust chamber. Here, a center line of the injection port is inclined with respect to a radial direction of the turbine rotor so that the plurality of spray nozzles inject the spray water in a direction counter to a rotation direction of the turbine rotor. An inclination angle at which the center line of the injection port is inclined to a forward side of the rotation direction with respect to the radial direction of the turbine rotor is in a relationship represented by the following formula (A).
2545(A)

(20) Embodiments will be described with reference to the drawings.

First Embodiment

(21) FIG. 1 is a view illustrating a substantial part of a steam turbine according to a first embodiment.

(22) In FIG. 1, similarly to FIG. 11, a cross section of a vertical plane (x-z plane) orthogonal to a rotation axis AX is illustrated and a rotation direction R of a turbine rotor 3 is indicated using a dotted line arrow. However, FIG. 1 illustrates two spray nozzles 51 (a first spray nozzle 51A and a second spray nozzle 51B) placed on an upper half side.

(23) Although illustration is omitted, a steam turbine 1 according to this embodiment has a casing 2, a turbine rotor 3, and a steam turbine exhaust chamber cooling device 5, as in the case of the above-described related art (refer to FIG. 9 and FIG. 10). However, in this embodiment, as illustrated in FIG. 1, an arrangement of the spray nozzles 51 (the first spray nozzle 51A and the second spray nozzle 51B) constituting the steam turbine exhaust chamber cooling device 5 is different from that in the above-described related art (refer to FIG. 11). This embodiment is the same as the case in the above-described related art except the above-described point and related points. Therefore, in this embodiment, descriptions of parts overlapping with those in the above-described related art will be omitted when appropriate.

(24) In this embodiment, the spray nozzle 51 is placed at the tip of a connecting pipe 52 as illustrated in FIG. 1, as in the case of the related art (refer to FIG. 11). Here, the spray nozzle 51 is constructed so as to spray minute water droplets whose diameter is 200 m or less, for example. The connecting pipe 52 is coaxial with an injection port of the spray nozzle 51.

(25) Further, there are a plurality of spray nozzles 51, and in the plurality of spray nozzles 51, the injection ports are symmetrically arranged with a vertical direction (z direction) passing through a rotation axis AX of the turbine rotor 3 being a symmetrical axis. Specifically, the first spray nozzle 51A and the second spray nozzle 51B are placed on the upper half side, as in the case of the related art (refer to FIG. 11). A mounting angle 1 of the first spray nozzle 51A and a mounting angle 2 of the second spray nozzle 51B are the same as each other, and each of them is, for example, 45 (1=2=45).

(26) However, in this embodiment, each of the first spray nozzle 51A and the second spray nozzle 51B is not placed so that a center line J5 of the injection port is along a radial direction of the turbine rotor 3, unlike the case of the related art (refer to FIG. 11). In other words, in this embodiment, an extension line extending the center line J5 of the injection port and the rotation axis AX (rotation center) do not cross each other.

(27) In this embodiment, the center line J5 of the injection port is inclined with respect to the radial direction of the turbine rotor 3 so that each of the first spray nozzle 51A and the second spray nozzle 51B injects spray water S5 (not illustrated in FIG. 1) in a direction counter to the rotation direction R. That is, in each of the first spray nozzle 51A and the second spray nozzle 51B, the center line J5 of the injection port is inclined to a forward side of the rotation direction R with respect to the radial direction of the turbine rotor 3.

(28) Specifically, an inclination angle at which the center line J5 of the injection port is inclined to the forward side of the rotation direction R with respect to the radial direction of the turbine rotor 3 is 0 in the related art (refer to FIG. 11) (=0), while in this embodiment, it is different from that in the related art. In this embodiment, the inclination angles are the same as each other in the first spray nozzle 51A and the second spray nozzle 51B, and its minimum value is 25 (=25) and its maximum value is 45 (=45). That is, the inclination angle is in a relationship represented by the following formula (A).
2545(A)

(29) Note that the inclination angles may be the same or different in the first spray nozzle 51A and the second spray nozzle 51B.

(30) Operations and effects of the steam turbine exhaust chamber cooling device 5 according to this embodiment will be described.

(31) FIG. 2, FIG. 3, and FIG. 4 are views illustrating flow of the spray water S5 which the steam turbine exhaust chamber cooling device 5 supplies to a turbine exhaust chamber K2 in the steam turbine according to the first embodiment.

(32) In FIG. 2 to FIG. 4, the vertical plane (x-z plane) orthogonal to the rotation axis AX is illustrated similarly to FIG. 1. In FIG. 2 to FIG. 4, the flow of the spray water S5 is indicated using solid line arrows. FIG. 2 illustrates a state of the spray water S5 which the spray nozzle 51 injects when operation of the steam turbine 1 is halted and steam which is working fluid does not flow. On the other hand, FIG. 3 and FIG. 4 each illustrate a state of the spray water S5 which the spray nozzles 51 inject when operation is performed under a very low load (for example, 5% load with respect to 100% rated load) or no load in the steam turbine 1. FIG. 3 illustrates that the inclination angle is 25 which is the minimum value and FIG. 4 illustrates that the inclination angle is 45 which is the maximum value. Note that in FIG. 2, a longitudinal direction is not a vertical direction but a radial direction differently from FIG. 3, and a placement portion of the spray nozzle 51 is illustrated to be enlarged.

(33) As illustrated in FIG. 2, the spray nozzle 51 performs spray so that the spray water S5 conically diffuses. The spray nozzle 51 performs the spray of the spray water S5 at a spray angle of 60, for example. Specifically, in the state where operation of the steam turbine 1 is halted, a water droplet S5a is injected along the center line J5 of the injection port of the spray nozzle 51. Besides the above, a water droplet S5b is injected to a more forward side of the rotation direction R than a direction along the center line J5 of the injection port and at the same time a water droplet S5c is injected to a more backward side of the rotation direction R than the direction along the center line J5 of the injection port. In this embodiment, the water droplet S5a injected along the center line J5 of the injection port goes to a direction inclined to the forward side of the rotation direction R with respect to the radial direction of the rotation axis AX.

(34) As illustrated in FIG. 3 and FIG. 4, in the state where the operation is performed under the very low load or no load in the steam turbine 1, the spray water S5 flows to be biased to the forward side of the rotation direction R (left side in FIG. 3) due to high-speed swirling flow which occurs at an outlet of a turbine stage at a final stage, as in the case of the related art (refer to FIG. 16). For example, in the spray water S5, the water droplet S5a injected along the center line J5 of the injection port of the spray nozzle 51 flows to the more forward side of the rotation direction R than the center line J5.

(35) However, in this embodiment, unlike the case of the related art (refer to FIG. 16), the first spray nozzle 51A and the second spray nozzle 51B are provided to be inclined as described above. Therefore, all of the spray water S5 (water droplets S5a, S5b, and S5c) injected from them reaches an inner peripheral flow guide 24 and cools the vicinity of a blade root.

(36) Consequently, in this embodiment, because cooling is sufficiently performed, it is possible to improve cooling efficiency (heat exchange efficiency). Then, in accordance with the above, it is possible to decrease a supply amount of the spray water S5. That is, a cooling water amount can be reduced. Accordingly, because the water droplet which collides with a rotor blade 31 decreases, it is possible to effectively suppress occurrence of erosion. As a result, in this embodiment, longer operating life of the rotor blade 31 can be achieved, and it is possible to perform the very low load operation or no load operation for a long time. Note that when the inclination angle is smaller than the above-described minimum value (25), the spray water S5 in a front side of the rotor rotation direction does not reach the inner peripheral flow guide 24 as illustrated by the water droplet S5b in FIG. 3 and a problem in that a heat exchange amount is reduced occurs. Further, when the inclination angle is larger than the above-described maximum value (45), the spray water in a back side of the rotor rotation direction does not reach the inner peripheral flow guide 24 as illustrated by the water droplet S5c in FIG. 4 and a problem in that the heat exchange amount is reduced occurs.

(37) Note that in this embodiment, the case where two spray nozzles 51 are placed on the upper half side has been described, but this is not restrictive.

Second Embodiment

(38) FIG. 5 is a view illustrating a substantial part of a steam turbine according to a second embodiment.

(39) In FIG. 5, similarly to FIG. 1, a cross section of a vertical plane (x-z plane) orthogonal to a rotation axis AX is illustrated and a rotation direction R of a turbine rotor 3 is indicated using a dotted line arrow. FIG. 5 illustrates two spray nozzles 51 (a first spray nozzle 51A and a second spray nozzle 51B) placed on an upper half side similarly to FIG. 1.

(40) In this embodiment, as illustrated in FIG. 5, an arrangement of the spray nozzles 51 (the first spray nozzle 51A and the second spray nozzle 51B) constituting a steam turbine exhaust chamber cooling device 5 is different from that in the above-described first embodiment. This embodiment is the same as the first embodiment except the above-described point and related points. Therefore, in this embodiment, descriptions of parts overlapping with those in the above-described related art will be omitted when appropriate.

(41) In this embodiment, the spray nozzle 51 is placed at the tip of a connecting pipe 52 as illustrated in FIG. 5, as in the case of the first embodiment. Here, the spray nozzle 51 is constructed so as to spray minute water droplets whose diameter is 200 m or less, for example. The connecting pipe 52 is coaxial with an injection port of the spray nozzle 51.

(42) Further, in this embodiment, a plurality of spray nozzles 51 are placed on an outer peripheral flow guide 23, as in the case of the first embodiment. Specifically, on the upper half side, the first spray nozzle 51A is placed more forward than a partition plate 25 in the rotation direction R of the turbine rotor 3. In addition, the second spray nozzle 51B is placed more backward than the partition plate 25 in the rotation direction R of the turbine rotor 3.

(43) Each of the first spray nozzle 51A and the second spray nozzle 51B is not placed so that a center line J5 of the injection port is along a radial direction of the turbine rotor 3, as in the case of the first embodiment. In this embodiment, the center line J5 of the injection port is inclined with respect to the radial direction of the turbine rotor 3 so that each of the first spray nozzle 51A and the second spray nozzle 51B injects spray water S5 (not illustrated in FIG. 5) in a direction counter to the rotation direction R. That is, in each of the first spray nozzle 51A and the second spray nozzle 51B, the center line J5 of the injection port is inclined to a forward side of the rotation direction R with respect to the radial direction of the turbine rotor 3. FIG. 5 illustrates that an inclination angle is 25 which is a minimum value, but the inclination angle may be in the range of 25 which is the minimum value to 45 which is a maximum value as represented by the above-described formula (A).

(44) However, in this embodiment, in the first spray nozzle 51A and the second spray nozzle 51B, the injection ports are not symmetrically arranged with a vertical direction (z direction) passing through a rotation axis AX of the turbine rotor 3 being a symmetrical axis.

(45) Specifically, in the rotation direction R of the turbine rotor 3, a mounting angle 1 from a vertical plane passing through the rotation axis AX of the turbine rotor 3 to a position where the injection port of the first spray nozzle 51A is mounted and a mounting angle 2 from the vertical plane passing through the rotation axis AX of the turbine rotor 3 to a position where the injection port of the second spray nozzle 51B is mounted are different from each other (12). Here, the mounting angle 1 of the first spray nozzle 51A and the mounting angle 2 of the second spray nozzle 51B are in a relationship represented by the following formula (B). That is, the mounting angle 1 of the first spray nozzle 51A is smaller than the mounting angle 2 of the second spray nozzle 51B.
1<2(B)

(46) In other words, the distance between the injection port of the first spray nozzle 51A and the partition plate 25 is shorter than the distance between the injection port of the second spray nozzle 51B and the partition plate 25. FIG. 5 illustrates that the mounting angle 1 of the first spray nozzle 51A is 20 and the mounting angle 2 of the second spray nozzle 51B is 45.

(47) Operations and effects of a steam turbine exhaust chamber cooling device 5 according to this embodiment will be described.

(48) FIG. 6 is a view illustrating flow of the spray water S5 which the steam turbine exhaust chamber cooling device 5 supplies to a turbine exhaust chamber K2 in the steam turbine according to the second embodiment.

(49) FIG. 6 illustrates the vertical plane (x-z plane) orthogonal to the rotation axis AX similarly to FIG. 5. In FIG. 6, the flow of the spray water S5 is indicated using solid line arrows. Here, in the spray water S5 which conically diffuses from the spray nozzle 51, besides a water droplet S5a injected at an angle with respect to the center line J5 of the spray nozzle 51, a water droplet S5b injected to a more forward side of the rotation direction R than a direction along the center line J5 and a water droplet S5c injected to a more backward side thereof are illustrated.

(50) As illustrated in FIG. 6, the spray water S5 flows to be biased to the forward side of the rotation direction R due to high-speed swirling flow which occurs at an outlet of a turbine stage at a final stage, as in the case of the first embodiment. For example, in the spray water S5, the water droplet S5a injected at an angle with respect to the center line J5 of the spray nozzle 51 flows to the more forward side of the rotation direction R than the center line J5.

(51) However, in this embodiment, the first spray nozzle 51A located more forward than the partition plate 25 in the rotation direction R is closer to the partition plate 25 than that in the first embodiment. The spray water S5 injected from the first spray nozzle 51A does not collide with the partition plate 25, and more water droplets (in the range of the water droplet S5a to the water droplet S5c) than those in the first embodiment reach an inner peripheral flow guide 24 and contribute to cooling.

(52) Further, in this embodiment, the operation of the spray water S5 injected from the first spray nozzle 51A makes the range Rfa (not illustrated in FIG. 6) illustrated in FIG. 16 small. That is, a dead zone located more forward in the rotation direction R than the partition plate 25 and not supplied with a cooling medium such as the spray water S5 becomes small.

(53) Furthermore, in this embodiment, the spray water S5 does not collide with and is not captured on the partition plate 25, and therefore it is possible to improve cooling efficiency. Further, in this embodiment, because the water droplet ejected from the spray nozzle 51 does not collide with the water droplet ejected from the other adjacent spray nozzle 51 and does not become coarse, it is possible to improve the cooling efficiency.

(54) Consequently, in this embodiment, because the cooling is sufficiently performed, it is possible to improve the cooling efficiency (heat exchange efficiency). Then, in accordance with the above, it is possible to reduce a supply amount of the spray water S5. Then, a decrease in the water droplets which collide with a rotor blade 31 and a sufficiently small diameter of the colliding water droplets make it possible to effectively suppress occurrence of erosion. As a result, in this embodiment, longer operating life of the rotor blade 31 can be achieved, and it is possible to perform the very low load operation or no load operation for a long time.

(55) Note that in this embodiment, the case where two spray nozzles 51 are placed on the upper half side has been described, but this is not restrictive. For example, the number of spray nozzles placed more forward than the partition plate 25 in the rotation direction R and the number of spray nozzles placed more backward than the partition plate 25 in the rotation direction R may be different from each other. That is, the number of spray nozzles placed more forward than the partition plate 25 in the rotation direction R may be more than the number of spray nozzles placed more backward than the partition plate 25 in the rotation direction R. Further, the number of spray nozzles placed more forward than the partition plate 25 in the rotation direction R may be fewer than the number of spray nozzles placed more backward than the partition plate 25 in the rotation direction R.

(56) Further, in the above-described embodiment, the case where the inclination angle of the first spray nozzle 51A and the inclination angle of the second spray nozzle 51B are the same as each other has been described, but this is not restrictive. The inclination angles may be different from each other in the first spray nozzle 51A and the second spray nozzle 51B.

(57) FIG. 7 is a view illustrating a substantial part of a steam turbine according to a modification example of the second embodiment. FIG. 7 illustrates the vertical plane (x-z plane) orthogonal to the rotation axis AX similarly to FIG. 6.

(58) This modification example illustrates a case where the mounting angle 1 of the first spray nozzle 51A is 20 and the mounting angle 2 of the second spray nozzle 51B is 25. Further, in this modification example, both the inclination angle 1 of the first spray nozzle 51A and the inclination angle 2 of the second spray nozzle 51B are different from each other. Here, the inclination angle 1 of the first spray nozzle 51A is 25 and the inclination angle 2 of the second spray nozzle 51B is 45.

(59) In this modification example, similarly to the above-described second embodiment, the operation of the spray water S5 injected from the first spray nozzle 51A makes the range Rfa (not illustrated in FIG. 6) illustrated in FIG. 16 small. That is, a dead zone located more forward in the rotation direction R than the partition plate 25 and not supplied with a cooling medium such as the spray water S5 becomes small.

(60) Furthermore, in this modification example, similarly to the above-described second embodiment, because the spray water S5 does not collide with and is not captured on the partition plate 25, it is possible to improve the cooling efficiency. Further, in this modification example, because the water droplet ejected from the spray nozzle 51 does not collide with the water droplet ejected from the other adjacent spray nozzle 51 and does not become coarse, it is possible to improve the cooling efficiency.

(61) While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.