JP4957358B2 - Steam turbine cylinder connection pipe - Google Patents

Description

  The present invention relates to a steam turbine cylinder connecting pipe.

  In the cylinder connecting pipe of the steam turbine, the steam discharged from the final stage outlet of the intermediate pressure turbine is guided to a plurality of cabins (low pressure portions) of the low pressure turbine. And a branch part is provided in order to guide to a plurality of low-pressure parts. This branch portion has a structure that branches in a right angle direction.

  In addition, there exists a thing of patent document 1, for example as a steam turbine cylinder connection pipe which guide | induces the vapor | steam which flows out from the compartment exit of a high pressure turbine or an intermediate pressure turbine to several low pressure turbines.

Japanese Patent Laid-Open No. 11-229818

  Since the branching portion has a structure branching in a right angle direction, the steam easily flows in a direction in which the steam travels straight by inertial force. For this reason, the distribution of the steam is not uniform among the plurality of low-pressure parts, and a large amount flows to the main flow pipe side. For this reason, the load distribution of the low-pressure turbine becomes unbalanced, and the efficiency of the entire turbine is reduced. In addition, since the branching portion branches in the right angle direction, the pressure loss increases and the efficiency further decreases.

  An object of the present invention is to provide a steam turbine cylinder branch pipe having a structure capable of appropriately distributing the amount of steam and further reducing pressure loss at the branch portion.

In the present invention, the steam turbine cylinder connecting pipe is composed of a main flow pipe and a branch pipe, and the branch pipe is provided so as to branch by being inclined downstream with respect to the main flow pipe, and the main flow pipe and the branch pipe on the downstream side of the branch portion. Are provided such that a reinforcing plate that reinforces the branching portion is provided at a portion where the cross-sectional shapes of the branching portions are oval and intersect with each other, and the reinforcing plate protrudes to the steam passage side.

  In addition, a throttle part for reducing the pipe diameter is provided in the middle of the main flow pipe, and a branch pipe is provided in the throttle part.

Further, as Kanjika diameter φd2 of Kanjika diameter φd1 of the mainstream pipe side distributor pipe side are substantially equal in the steam passage side tip of the reinforcing plate to set the length and angle of inclination protrudes to the steam passage side of the reinforcing plate It is characterized by that.

  According to the present invention, the amount of steam can be properly distributed, and the pressure loss at the branch portion is reduced, and a highly efficient steam turbine can be obtained. Moreover, the stress of the branch part accompanying inclination of a branch pipe can also be reduced.

  An embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a configuration of a steam turbine cylinder communication pipe according to an embodiment of the present invention. The present invention relates to a steam turbine cylinder connecting pipe that distributes steam emitted from a compartment outlet of a high-pressure or medium-pressure turbine to a plurality of compartment inlets of a low-pressure turbine. A case where the steam flowing out from the passenger compartment outlet (final stage outlet) is led to two low-pressure turbines will be described as a representative example.

  The steam flowing out from the compartment outlets 2a and 2b of the intermediate pressure turbine reaches the branching section 4 through the cylinder connection pipe (main flow pipe) 1. The main flow pipe is a straight pipe portion extending substantially parallel to the shaft of the intermediate pressure turbine or the low pressure turbine. In addition, the main flow pipe has a throttle part that reduces the pipe diameter in the middle of the straight pipe part that is arranged substantially horizontally, and has a large diameter part upstream of the throttle part and a downstream part of the throttle part. It is further divided into small diameter parts. The small-diameter portion has its tube center line decentered upward from the large-diameter tube center line. In this embodiment, the large-diameter portion and the small-diameter portion are narrowed so that the upper-side tube wall is substantially straight. It is connected through the part.

  Steam is distributed at the bifurcation to the first low pressure turbine and the second low pressure turbine. In the present embodiment, the branch portion is provided in the throttle portion. In the branch portion, a branch pipe is provided below the main flow pipe, and is connected to the main flow pipe so as to incline downstream. By providing the inclination angle in the range of 45 degrees to 60 degrees, the distribution of the steam amount can be made equal to the main flow and the branch flow at the branch portion of the cylinder connecting pipe. The divided steam flow flows to the first low-pressure turbine casing inlet 3a, and the main stream flows to the second low-pressure turbine casing inlet 3b. Here, a reinforcing plate 5 for reinforcing the branching portion is provided in the branching portion 4 provided in front of the first low-pressure turbine.

  FIG. 2 is an enlarged view of the branch portion, and the reinforcing plate 5 is installed at an angle of inclination α at a portion where the branched pipes a and b intersect. Furthermore, the reinforcing plate is projected to the steam passage side. The protruding length L of the reinforcing plate is set so that the areas of the main flow pipe a and the diversion pipe b are substantially equal at the tip position of the reinforcing plate (φd1≈φd2).

  When the branch pipe is inclined with respect to the main flow pipe at the branch part of the cylinder communication pipe, the pipe shape of the branch part becomes an ellipse. For this reason, when pressure is applied, it deforms to become a perfect circle, and stress concentration occurs in a portion with a small bending radius. In order to reduce this stress, a reinforcing plate is provided. Furthermore, the amount of steam on the diversion side can be controlled by projecting the reinforcing plate toward the flow path. That is, when the inclination angle α of the protruding reinforcing plate is increased, the steam amount on the diversion side increases, and when it is decreased, the steam amount on the diversion side decreases. Moreover, the flow of the branch part becomes smooth and the pressure loss is also reduced.

It is a figure showing the structure of the steam turbine cylinder connecting pipe which is one Example of this invention. It is detail drawing of the branch part of this invention.

Explanation of symbols

1 cylinder communication pipe (main pipe)
2a, 2b Medium pressure turbine casing outlet 3a First low pressure turbine casing inlet 3b Second low pressure turbine casing inlet 4 Branch 5 Reinforcing plate

Claims (2)

A steam turbine cylinder connecting pipe for guiding steam flowing out from a compartment outlet of a high-pressure or medium-pressure turbine to an inlet of a low-pressure turbine of at least two compartments,
The steam turbine cylinder communication pipe is composed of a main flow pipe and a branch pipe, and the branch pipe is provided so as to be inclined and branched downstream with respect to the main flow pipe, and the main flow pipe on the downstream side of the branch portion and the A reinforcing plate that reinforces the branching portion is provided in a portion where the branching pipe intersects and the pipe cross-sectional shape of the branching portion becomes an ellipse, the reinforcing plate is provided so as to protrude toward the steam passage side , A steam turbine cylinder connecting pipe, characterized in that the steam turbine cylinder connecting pipe is provided substantially horizontally and has a throttle portion for reducing a pipe diameter in the middle, and the branch pipe is provided in the throttle portion . Oite to claim 1, wherein the mainstream pipe branch section showing the area ratio of the branch pipe, the reinforcing plate Kanjika diameter φd2 of Kanjika diameter φd1 of the mainstream pipe side distributor tube side of the steam passage side tip of approximately A steam turbine cylinder connecting pipe characterized in that a length of projection and an inclination angle of the reinforcing plate to the steam passage side are set to be equal.

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