JPH05902U - Low-pressure cabin of steam turbine - Google Patents

Abstract

(57) [Abstract] [Purpose] To reduce the thermal deformation of the inner passenger compartment and reduce the internal steam leak. [Structure] A blade ring 5a having a plate structure for supporting a plurality of stages of stationary blades 6a at a steam inlet 1 and a first pressure partition wall 4a having a plate structure are integrated by welding. Second and third pressure partition walls 4b,
The reinforcing ribs 9 attached between the 4c are separated. A reinforcing rod 15 such as a pipe is provided between the first and second pressure partition walls 4a and 4b instead of a reinforcing rib. The first, second and third pressure partition walls 4a, 4b and 4c are provided integrally with the inner casing 3, respectively.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low pressure casing of a steam turbine, and more particularly to the structure of its blade ring and pressure partition.

[0002]

[Prior Art]

 FIG. 2 shows an example of the upper half of a steam turbine low-pressure casing that has been conventionally used. The steam flow 2 entering the low-pressure casing from the steam inlet 1 is caused to flow into the first pressure partition wall 4 a by the inner casing 3. A plurality of stages of stationary blades 6a fitted into a blade ring 5a supported via a blade ring 5b having a plate structure integrated with a second pressure partition wall 4a integrally formed with the first pressure partition wall 4a. A plurality of stationary vanes 6b supported, a stationary vane 6c supported by a blade ring 5c having a plate structure integrated with a third pressure partition wall 4c integrally formed with the inner casing 3, and the inner casing 3 It is jetted to the moving blade 7 through the stationary blade 6d supported by and the rotor 8 is rotated. Reinforcing ribs 9 are provided between the pressure partition walls 4a and 4b, 4b and 4c and between the inner casing 3 and the pressure partition wall 4c, respectively. In addition, 10 is an outer car room, 11 is a 1st extraction chamber, 12 is a 2nd extraction chamber, and 13 is a reinforcing material.

[0003]

[Problems to be solved by the device]

 However, the structure of the low-pressure casing of the conventional steam turbine described above, however, has the following problems.

(1) Since the steam flow 2 at the steam inlet 1 is higher in temperature than the steam flow 14 exiting from the inner casing 3 after finishing work, thermal expansion of the heated pressure partition walls 4a to 4c causes the inner casing to expand. The whole of No. 3 is deformed, so that the steam leak inside increases and the performance deteriorates. That is, at the fitting portion A between the blade ring 5a that supports the plurality of stages of stationary blades 6a at the steam inlet 1 and the first pressure partition wall 4a, axial displacement (waviness deformation) occurs, and the fitting A gap is created in the portion A and the steam 2'leaks. Further, radial displacement (oval deformation) becomes a problem at the places where the stationary blades 6a to 6c are welded. That is, the gaps between the stationary blades 6a to 6d and the rotor 8 and between the moving blade 7 and the stationary blades 6a to 6d become non-uniform, resulting in increased steam leakage or fin contact trouble. To do.

(2) High stress is generated at the joint B between the first and second pressure partition walls 4a and 4b and the inner casing 3 and at the joints between the respective pressure partition walls 4a to 4c and the reinforcing ribs 9, and the strength is increased. Is reduced.

(3) The blade ring 5a that supports the plurality of stages of the stationary blades 6a at the steam inlet 1 is a machined material of a thick plate material or a cast steel product and is costly.

The present invention has been made in order to solve the problems of the prior art as described above, and reduces thermal deformation of the inner casing to reduce internal steam leakage, and reduces the number of parts to reduce The purpose is to provide a low-pressure passenger compartment of a steam turbine that has a low strike.

[0008]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems, the present invention is to weld a blade ring of a plate structure supporting a plurality of stages of stationary blades at a steam inlet in a low pressure casing of a steam turbine and a first pressure partition wall of the plate structure by welding. Between the first pressure partition wall and the second pressure partition wall of the plate structure adjacent to the first pressure partition wall, and between the second pressure partition wall and the third pressure partition wall of the plate structure adjacent to the first pressure partition wall. A reinforcing rib attached to one of the above is separated, and a reinforcing rod is provided to the other in place of the reinforcing rib, and the first, second and third pressure partition walls are respectively provided integrally with the inner casing. is there.

[0009]

[Action]

 According to the above means, the first pressure partition, which is first heated by the high-temperature steam flow, is integrated with the blade ring and the stationary blade, and the pressure partition between any one of the first, second, and third pressure partitions is integrated. Since the reinforcing ribs provided are separated and the other pressure bulkheads are joined by reinforcing rods that relieve the thermal deformation constraint, the deformation of the inner casing due to thermal expansion is reduced and the internal steam leak is reduced. To do.

Further, since the stress of the joining portion of the reinforcing rod is smaller than that of the reinforcing rib, the fatigue strength is improved. Further, since the first pressure partition wall, the blade ring, and the plurality of stages of stationary blades are integrated, the number of parts is reduced.

[0011]

【Example】

 Hereinafter, an embodiment of the present invention will be described in detail with reference to FIG. Note that, in FIG. 1, the same parts as those shown in FIG. 2 are denoted by the same reference numerals, and overlapping description will be omitted.

As shown in FIG. 1, according to the present embodiment, the blade ring 5a that supports the plurality of stages of stationary blades 6a at the steam inlet 1 has a plate structure. The partition wall 4a is integrated by welding.

Further, the reinforcing ribs 9 attached between the second pressure partition wall 4b and the third pressure partition wall 4c in the second bleed chamber 12 are separated, and the second and third pressure partition walls 4b are separated from each other. , 4c. A plurality of reinforcing rods 15 such as pipes are provided in place of the reinforcing ribs 9 between the first pressure partition wall 4a and the second pressure partition wall 4b in the first extraction chamber 11.

According to such a configuration of this embodiment, the first pressure partition wall 4a, which is first heated by the high-temperature steam flow 2, the blade ring 5a, and the stationary blade 6a are integrated, and the second and second blades are integrated. The reinforcing ribs 9 provided between the three pressure partition walls 4b and 4c are separated, and the first and second pressure partition walls 4a and 4b are joined by the reinforcing rod 15 that softens the thermal deformation restraint. As a result, the deformation of the inner casing 3 is reduced, and the steam leak inside is reduced.

Further, the reinforcing bar 15 has a smaller stress at the joint portion than the reinforcing rib 9, so that the fatigue strength is improved. Further, since the first pressure partition wall 4a, the blade ring 5a, and the plurality of stages of stationary blades 6a are integrated, the number of parts is reduced.

As a modified example, reinforcing ribs 9 are provided separately between the first and second pressure partition walls 4a and 4b, and a reinforcing rod 15 is provided between the second and third pressure partition walls 4b and 4c. Also, substantially the same effect can be obtained.

[0017]

[Effect of the device]

 As described above, according to the present invention, the high-temperature region in the low-pressure casing of the steam turbine is integrated, the reinforcing ribs mounted between the pressure bulkheads are separated, and the reinforcing rod for softening the thermal deformation restraint is provided. As a result, the thermal deformation of the inner compartment is reduced, and the steam leak inside is reduced. As a result, turbine performance is improved.

Further, the stress of the joint portion of the reinforcing rod for joining the pressure partition walls is reduced, and the fatigue strength is improved. Further, since the first pressure partition wall, the blade ring, and the plurality of stages of stationary vanes are integrated, the number of parts is reduced, and since the stationary vane holding portion has a plate structure, the weight is reduced and the cost is reduced. To do.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an upper half of a passenger compartment showing a low-pressure passenger compartment of a steam turbine according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the upper half of the passenger compartment showing a low-pressure passenger compartment of a conventional steam turbine.

[Explanation of Codes] 1 steam inlet 2 steam flow 3 inner casing 4a-4c pressure partition wall 5a-5c blade ring 6a-6d stationary blade 7 moving blade 8 rotor 9 reinforcing rib 10 outer casing 11 extraction chamber 12 extraction chamber 13 reinforcement 14 Steam flow 15 Reinforcing rod

Claims (1)

Claims for utility model registration: 1. A blade ring having a plate structure for supporting a plurality of stages of stationary blades at a steam inlet and a first pressure partition wall having a plate structure are integrated by welding, and the first Reinforcing ribs attached to one of the pressure partition wall and the second pressure partition wall of the plate structure adjacent thereto and between the second pressure partition wall and the third pressure partition wall of the plate structure adjacent thereto. A low pressure casing for a steam turbine, characterized in that a reinforcing rod is provided on the other side instead of a reinforcing rib, and the first, second and third pressure partition walls are provided integrally with the inner casing. .