JP2524778Y2 - Turbine nozzle diaphragm - Google Patents

Description

[Detailed description of the invention] [Object of the invention] (Industrial application field) The present invention relates to a nozzle diaphragm constituting a steam passage portion of a steam turbine, and in particular, tightens an upper half and a lower half of a nozzle diaphragm. The present invention relates to a turbine nozzle diaphragm suitable for preventing bolt erosion.

(Prior Art) Generally, in a thermal power plant and a nuclear power plant, a steam turbine is used as a prime mover for driving a generator, and steam is formed by forming a plurality of turbine stages including a stationary blade and a moving blade. It converts heat energy into mechanical energy. That is, the steam turbine is
As shown in the figure, the nozzle plate 1 is fixed in the turbine casing 4 between the outer ring 3 and the inner ring 2 of the nozzle diaphragm, and the nozzle plate 1 is arranged in the circumferential direction to inject steam toward the rotor blade 5 from between the nozzle plates 1. The heat energy of the steam is converted into mechanical energy.

(Problems to be Solved by the Invention) By the way, as shown in FIG. 3, the nozzle diaphragm serving as a support for the nozzle plate 1 includes an upper half 7 of the upper nozzle diaphragm and a lower side of the horizontal diaphragm 6 as a boundary. And a lower half 8 of the nozzle diaphragm, and when assembled into a steam turbine, the upper half 7 and the lower half 8 of the nozzle diaphragm form an annular nozzle diaphragm.

The pressure of steam determined for each paragraph acts before and after the nozzle diaphragm having the two-part structure, and a gap 9 may be generated in the horizontal joint surface 6 on the high pressure side. When this gap 9 is formed, some steam flows out to the low pressure side without being injected from between the nozzle plates 1, and effective work cannot be performed. For this reason, a nozzle diaphragm of an upper and lower half tightening type in which the upper half 7 and the lower half 8 of the nozzle diaphragm are tightened by tightening bolts so as to eliminate the gap 9 between the horizontal joint surfaces 6 is often used. FIG. 4 shows a nozzle diaphragm of this type. A bolt hole 10 and a screw hole 11 are formed in the upper half 7 and the lower half 8 of the nozzle diaphragm so as to extend in a direction transverse to the joint surface. Tightening. As shown in FIG. 5, a positioning pin 13 is mounted on the upper half 7 of the nozzle diaphragm, whereas a female pin hole 14 is formed in the lower half 8 of the nozzle diaphragm to form a nozzle diaphragm at the time of assembly. The upper half 7 and the lower half 8 can be easily centered.

However, also in this nozzle diaphragm, deformation occurs in the upper half 7 and the lower half 8 of the nozzle diaphragm around the horizontal joint surface 6 due to the pressure difference between the stages. Alternatively, when the casing 4 to which the nozzle diaphragm is fixed is deformed due to thermal expansion, deformation occurs in the upper half 7 and the lower half 8 of the nozzle diaphragm supported thereby. Due to these deformations, a gap 9 is generated in the horizontal joint surface 6 of the nozzle diaphragm of the upper and lower half-tightened type, steam flows through the gap 9, and the invading steam collides with the screw portion 15. At this time, the steam contains oxidized scale and the like due to corrosion of the heat transfer tubes of the boiler, while the moist steam from the nuclear reactor contains a large amount of water droplets, so the tightening bolt 12 erodes around the screw portion 15. However, there is a problem that the bolt strength is lost due to the thinning.

SUMMARY OF THE INVENTION An object of the present invention is to provide a turbine nozzle diaphragm which solves the above-mentioned problems of the prior art and prevents the tightening bolt from being eroded by steam entering from the joint surface of the nozzle diaphragm. I do.

[Structure of device]

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention provides a method in which the upper half and the lower half of a semicircular nozzle diaphragm are inserted through a plurality of tightening bolts inserted in a direction crossing both joint surfaces. In the turbine nozzle diaphragm, the upper half of the nozzle diaphragm covers a predetermined area near the joint surface of the tightening bolt, and the lower half of the nozzle diaphragm is positioned by a tapered portion on the outer surface. It is characterized in that a cylindrical protection member is provided.

(Operation) In the present invention, since the protection member covers the vicinity of the joint surface of the tightening bolt over both the upper half and the lower half of the nozzle diaphragm, the above-mentioned intrudes into the gap between the joint surfaces of the upper half and the lower half of the nozzle diaphragm. Even if it hits only the protection member, it does not hit the tightening bolt directly. Therefore, since the tightening bolt does not directly contact the oxide scale or the water droplet, the thinning does not occur, and the bolt strength can be maintained for a long time.

(Embodiment) An embodiment of a turbine nozzle diaphragm according to the present invention will be described below with reference to FIG. The same parts as those in the related art are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 1 shows a turbine nozzle diaphragm according to the present invention, in which the upper half 7 and the lower half 8 of the nozzle diaphragm are tightened by tightening bolts 12. A counterbore 17 having a larger diameter than the bolt hole 10 is formed along the bolt hole 10 of the upper half 7 of the nozzle diaphragm. A protective member, for example, a protective sleeve 18 made of corrosion-resistant steel is inserted into the counterbore 17 with an inner diameter equal to that of the bolt hole 10 and an outer diameter with an appropriate gap between the counterbore 17. At the same time, caulking 19 is applied and fixed. Further, a hole 20 is formed in the lower half 8 of the nozzle diaphragm while keeping an appropriate gap with the outer diameter of the protective sleeve 18. In addition, a tapered portion 21 is provided at a portion of the protective sleeve 18 to be inserted into the hole 20 so that the protective sleeve 18 can be easily inserted into the hole 20.

As a result, the tightening bolt 12 is surrounded by the protective sleeve 18 around the screw portion 15, and does not reach the screw portion 15 even if steam enters through the gap 9 in the horizontal joint surface 6. Therefore, the fastening bolt 12 is not eroded by the oxide scale or the like contained in the steam or the water droplet in the wet steam. Further, the protective sleeve 18 can be used as a positioning member when assembling the upper half 7 and the lower half 8 of the nozzle diaphragm, instead of the positioning pin 13 shown in FIG.

[Effect of the invention]

As is apparent from the above description, in the present invention, a hollow cylindrical protective member that covers a certain area near the joint surface of the tightening bolt on the upper half of the nozzle diaphragm, and positions the lower half of the nozzle diaphragm by a tapered portion on the outer surface. Therefore, even if steam invades into the gap between the upper and lower joint surfaces of the nozzle diaphragm, it does not flow to the tightening bolt surrounded by the protective member, but the tightening bolt is oxidized by the boiler. Can be prevented from being locally eroded. Also, since the lower half of the diaphragm is positioned by the tapered portion on the outer surface, the upper and lower halves of the diaphragm can be centered without using positioning pins. Therefore, according to the present invention, it is possible to reliably prevent loss of bolt strength due to wall thinning, and to provide an excellent effect of providing an inexpensive nozzle diaphragm that is easy to assemble.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing one embodiment of a turbine nozzle diaphragm according to the present invention, FIG. 2 is a sectional view showing one paragraph of a conventional steam turbine, and FIG. 3 is a perspective view showing a conventional turbine nozzle diaphragm. FIG. 4 is a partially cutaway front sectional view showing a conventional turbine nozzle diaphragm.
FIG. 5 is a sectional view taken along the line VV in FIG. 4, and FIG.
It is sectional drawing which follows the VI-VI line of a figure. DESCRIPTION OF SYMBOLS 1 ... Nozzle plate 4 ... Casing 6 ... Horizontal joint surface 7 ... Upper half of nozzle diaphragm 8 ... Lower half of nozzle diaphragm 9 ... Gap 12 ... Tightening bolt 17 ... Counterbore 18 ... Protective sleeve 20 ... Hole

Claims (1)

(57) [Scope of request for utility model registration] 1. A turbine nozzle diaphragm in which an upper half and a lower half of a semicircular nozzle diaphragm are integrally connected via a plurality of tightening bolts inserted in a direction crossing both joint surfaces. Covering a certain area near the joint surface of the tightening bolt in the upper half of the diaphragm,
And a hollow cylindrical protective member for positioning a lower half of the nozzle diaphragm by a tapered portion on an outer surface.