JPH068703U - Erosion prevention structure for rotating machinery - Google Patents

Abstract

(57) [Summary] [Purpose] Efficiently evaporate the water film flowing down on the surface of the stationary blade to prevent erosion of the moving blade arranged behind. [Structure] An electric heating layer 13 is provided on the ventral surface 3 (and / or the back surface 15) of the stationary blade 1 via an electrical insulating layer 12 to evaporate the water film 5 flowing down on the stationary blade ventral surface 3. in this case,
A groove 11 is provided on the upstream side of the electric heating layer 13, and the groove 11
The water film 5 flowing down is temporarily stopped and the flow velocity of the water film is reduced, so that the water film evaporation in the electrical heating layer 13 is effectively performed.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a rotating machine for preventing erosion of a moving blade generated by droplets in wet steam, and more particularly to an erosion preventive structure of a steam turbine, and more specifically, a stationary blade of a steam turbine operating in a wet steam atmosphere. It is applied to the structure to prevent the erosion of the trailing blades.

[0002]

[Prior art]

 FIG. 3 shows a conventional structure for preventing erosion that occurs in the final stage rotor blades of a low pressure steam turbine operating in wet steam, and FIG. 4 is a sectional view taken along line IV-IV of FIG.

As shown in these figures, conventionally, a slit 4 is provided on a ventral surface 3 of a stationary blade 2 placed in front of a moving blade 1 in which erosion is generated by droplets in wet steam, and the slit 4 allows the stationary blade to move. The water film 5 flowing down on the surface is captured and discharged through a drain discharge hole 6, 7 to a condenser (not shown) or the like.

[0004]

[Problems to be solved by the device]

 By the way, in the conventional example having such a structure, the number of slits 4 for capturing the water film 5 flowing down on the blade surface of the stationary blade 2 becomes larger as it is closer to the trailing edge 8 of the stationary blade 2. The water film 5 can be efficiently captured. However, in order to discharge the water film 5 captured by the slit 4 as a drain to the outside of the passage, it is necessary to provide the stationary blade 2 with the drain discharge hole 6 connected to the slit 4. Due to the restriction, the drain discharge hole 6 is usually provided only in the position of 50 to 60% downstream of the blade width 10 from the leading edge 9, so that the drain removal efficiency is low.

The present invention has been made in order to solve the problems of the prior art as described above, and efficiently evaporates the water film (drain) flowing down on the surface of the stationary blade to efficiently remove the water film from the rear moving blade. It is an object of the present invention to provide an erosion preventive structure for a rotating machine capable of preventing erosion.

[0006]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems, the present invention provides a stationary blade that is placed in front of a rotor blade that causes erosion in an erosion-preventing structure for a rotary machine that prevents rotor blade erosion that is caused by droplets in wet steam. A groove for capturing a water film on the surface of the vane is provided on one or both of the ventral surface and the back surface of the vane, and the surface of the vane downstream of this groove is coated with a thin-film electric heating layer via an electrical insulating layer. It was done.

[0007]

[Action]

 According to the above means, the thin film electric heating layer provided on the surface of the vane evaporates the water film on the surface of the vane, eliminating the ejection of coarse water droplets from the trailing edge of the vane. It is possible to prevent erosion of the rotor blade. In this case, the groove located on the upstream side of the electric heating layer temporarily blocks the water film flowing down from the upstream side to reduce the flow velocity of the water film, so that the electric current on the downstream side of the groove is reduced. The heat layer can effectively evaporate the water film.

[0008]

【Example】

 Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 1 and 2. 1 is a sectional view showing an example in which the present invention is applied to a final stage stationary blade of a low-pressure steam turbine, and FIG. 2 is a sectional view taken along line II-II of FIG.

In these drawings, the stationary blade 2 is installed in front of the final stage moving blade 1 of the low-pressure steam turbine as shown in FIG. 3, and according to this embodiment, the stationary blade 2 A groove 11 for capturing the water film 5 on the surface of the vane is provided in the vicinity of the center of the ventral surface 3 of the. Further, an electrical insulating layer 12 is provided by, for example, ceramic coating on the ventral surface 3 of the stationary blade 2 downstream of the groove 11, and the thin film metal foil or conductive powder is further provided on the electrical insulating layer 12. And an electric heating layer 13 is provided. A lead wire 14 for power supply is connected to the electric heating layer 13.

Next, the operation will be described. By supplying electric power to the electric heating layer 13 by the lead wire 14, the water film 5 on the abdominal surface 3 of the stationary blade can be evaporated. In this case, the groove 11 located on the upstream side of the electric heating layer 13 temporarily blocks the water film 5 flowing down from the upstream side and reduces the flow velocity of the water film 5, so The water film 5 can be effectively evaporated by the electric heating layer 13 on the downstream side. By thus evaporating the water film flowing down on the surface of the stationary blade, it is possible to prevent the ejection of coarse water droplets from the trailing edge 8 of the stationary blade 2 and reliably prevent the erosion of the trailing blade. it can.

In this embodiment, the groove 11 and the electric heating layer 13 are provided on the ventral surface 3 of the vane 2. However, the present invention is not limited to this structure, and the groove and the electric heating layer 13 are not limited to this structure. It is also possible to have a structure in which the gas-heating layer is provided on the back surface 15 of the vane, or on both the ventral surface 3 and the back surface 15 of the vane.

[0012]

[Effect of device]

 As described above, according to the present invention, in a rotary machine that operates in wet steam, a water film capturing groove and a groove for capturing the water film, which are provided on the surface of the stationary blade that precedes the rotor blade that causes erosion, are formed. An electric heating layer for water film evaporation provided on the downstream side effectively evaporates the water film on the surface of the vane, thereby eliminating the ejection of coarse water droplets from the trailing edge of the vane and allowing the trailing movement. The effect of reliably preventing the erosion of the wings is exhibited.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a final stage stationary blade portion of a low-pressure steam turbine showing an embodiment of an erosion prevention structure according to the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a sectional view of a final stage portion of a low-pressure steam turbine showing a conventional erosion prevention structure.

4 is a sectional view taken along line IV-IV of FIG.

[Explanation of symbols]

 2 stationary blade 3 ventral surface 5 water film 8 trailing edge 11 groove 12 electrical insulating layer 13 electrical heating layer 14 lead wire 15 rear surface

Claims (1)

[Scope of utility model registration request] 1. An erosion preventive structure for a rotating machine, which prevents erosion of a moving blade caused by droplets in wet steam, is provided on one or both of an abdominal surface and a back surface of a stationary blade placed in front of the moving blade where erosion occurs. An erosion of a rotary machine characterized in that a groove for capturing a water film on the surface of the stationary blade is provided, and a thin film electric heating layer is coated on the surface of the stationary blade downstream from this groove via an electrical insulating layer. Prevention structure.