JPH03249303A - Double-current steam turbine - Google Patents

Abstract

PURPOSE:To avoid bad influence of thermal expansion and prevent leakage of steam by blocking the passage between both shroud plates which cover ends of first step static blade lines on both sides and a flow guide ring through airtight rings. CONSTITUTION:Shroud plates 6, 7 which cover ends of first step static blade lines 6, 7 on both sides, and a flow guide ring 22 which blocks the passage between the shroud plates 20 and 21 through airtight rings 23, are provided. In flow of stem from a stem inlet 2 is divided into two directions by means of the flow guide ring 22 and the shroud plates 20, 21, and introduced into the first step static blade lines 6, 7 on both sides. In this case, the shroud plates 20, 21 are connected to the flow guide ring 22 by means of the airtight rings 23, so that thermal expansion during operation of a turbine is eliminated by the airtight rings 23 and the leakage of steam is prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is characterized in that the steam flowing in from the steam inlet of the casing is
This invention relates to a double-flow steam turbine in which the air flows through stages on both sides of the steam inlet for expansion, and in particular to the elongation of the row of stator blades in the first stage of the steam inlet.

[Conventional technology]

a. In a flow-type steam turbine, the steam that flows in from the steam inlet of the casing is divided into 20,000 parts and is installed between the stator blades of the stator blade rows provided in the casing on both sides of the steam inlet and the shaft.
Work is carried out by passing the flow through multiple stages of stages formed by the #4 row of wJ blades. In order to prevent the inflowing steam from leaking from the gap between the tip of the stationary blade row and the axle that opposes it, the
No. 5 g Sho > O and those shown in Figure 1 are known.

In Fig. 3, inside the casing 1, on both sides of the steam population 2 of the casing 1, there are rows of stator blades consisting of 1 x 3:! ! There are several rows. A plurality of rows of stator blades are disposed on the axle 4 and are composed of rotor blades 5 that form a stage with the stator blades of the stator blade rows. Reference numerals 6 and 7 indicate the stator blade rows of the first stage of the steam inflow section, and shroud plates 8 and 9 cover the tips of the stator blades of the stator blade rows 6 and 7.
is attached, and a bridge piece 12 is attached which extends between the shroud plates 8 and 9 and is tightened with bolts 11 via f210.

With this structure, the steam flowing in from the steam port 2 is divided into two directions by the bridge piece 12 and the shroud plates 8 and 9 connected thereto, and flows to the stages on both sides of the steam port 2. At this time, the bridge and jig pieces 12 and the shroud plates 8 and 9 prevent the steam flowing into the first stage stator blade row from leaking through the gap between the tip of the first stage stator blade row and the axle.

In Fig. 4, the shroud 1 of the stator blade rows 6 and 7 of the first stage is shown.
A 3.14 t labyrinth fin 15 is provided, and a flow kite 17 is provided which takes out the tip of the stationary blade row 5.6 with a gap between the labyrinth fin 15 and the labyrinth fin 15.

With this structure, the steam flowing in from the steam population 2 is divided into 20,000 parts by the flow guide F and flows to the stages on both sides of the steam population 2, but at this time, the labyrinth fins 15 separate the steam from the tip of the stationary blade row 6.7. Sole leaking steam.

[Problem to be solved by the invention]

In the conventional example shown in FIG. 3, the round plate 8.9 and the bridge piece 12 are fastened together via the baffles 210, so that when the baffles expand in the axial and radial directions due to thermal expansion during turbine operation, There is a problem in that the force is transmitted to the stator blades of the stator blade rows 6 and 7 of the first stage, which adversely affects the strength, deformation, etc. of the stator blade rows and the stator blades.

In the conventional example shown in FIG. 4, an appropriate gap must be provided between the labyrinth fins 15 installed on the shrouds 13 and 14 and the flow guide 17 in consideration of thermal expansion and thermal deformation of each member during turbine operation. Therefore, there is a problem in that steam leaks from this space, resulting in steam leakage loss, which is unfavorable in terms of performance.

An object of the present invention is to provide a double-flow steam turbine that does not adversely affect the stator blade rows of the first stage even if they are extended in the axial and radial directions due to thermal expansion during turbine operation, and that can prevent steam leakage. It is to be.

[Means to solve the problem]

In order to solve the above problems, according to the present invention, the stator blades and the axle are provided on both sides of the steam inlet of a casing provided with a plurality of stator blade rows (l number of rotor blade rows). In a double-flow steam turbine, the steam flowing in from the steam turbine is divided into two directions and is expanded by flowing through the stages on both sides. A shroud plate adjacent to the tip and a flow guide ring that closes the space between the two shroud plates via an air MIJ ring are provided.

[Effect]

The steam inlet where steam flows from the steam inlet has a shroud plate that covers the tips of the blade rows containing the first stage on both sides of the steam inlet in the casing, and an airtight ring between these two shroud plates. By providing a flow guide ring that closes with Since the air-tight ring connects the air-tight plate and the flow guide ring, the air-tight ring absorbs heat and swelling during turbine operation and prevents steam leakage.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.
Embodiment 1 FIG. 1 is a partial sectional view of a steam inlet portion of a double flow steam turbine according to Embodiment 1 of the present invention. 3. FIG. 3 in FIG. 1 and FIG. 2, which will be described later.

Components that are the same as those in the conventional example shown in FIG. 4 are given the same reference numerals, and their explanations will be omitted. In FIG. 1, a shroud plate 21) covers the tips of the first stage stator blade rows 6 and 7.

- What is the guide cell ?nid η? As shown in Fig. 2, it is an annular ? *It is inserted into and joined to the annular groove 5 provided in the flow guide link n. Note that an airtight ring B is disposed on the shroud plate 2tJ side with a similar structure. Note that the flow guide ring B has a two-piece structure and is supported by the casing 1 by a support (not shown).

Due to this structure, the rate of inflow from steam population 2 is 2
0, 2] and six flow kites, the flow is divided into two directions and flows into the first stage stator blade rows 6 and 7 on both sides, but the airtight ring B prevents the flow into the stator blade rows 6 and 7. This eliminates steam leakage and absorbs thermal expansion during turbine operation.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, the flow kite ring is closed between the shroud plates covering the tips of the first stage stator blade rows on both sides of the steam inlet of the casing via an airtight ring. As a result, the steam flowing in from the steam inlet can be prevented from leaking into the first stage stator blade row by the airtight ring, and the heat expansion in the axial direction ε and radial direction during turbine operation can be absorbed. Therefore, the structural integrity of the first stage stator blade row can be confirmed.

[Brief explanation of drawings]

Fig. 1 is a partial sectional view of a double flow steam turbine according to practical example 1 of the present invention, Fig. 2 is an enlarged view of section A in Fig. 1, and Fig. 3 is a partial sectional view of a conventional double flow steam turbine. , FIG. 4 is a partial sectional view of a different conventional double-flow steam turbine. 1: Casing, 2: Steam inlet, 3: Stationary blade, 2 milk inlet, 1 cable head diagram diagram diagram diagram diagram diagram

Claims (1)

[Claims] 1) On both sides of the steam inlet of a casing having a plurality of rows of stator blades, a plurality of stages formed by the stator blades and rotor blades of a plurality of rows of rotor blades provided on an axle are provided, and the steam inlet A shroud plate that covers the tips of the stator blade rows of the first stage on both sides of the double flow steam turbine in which steam flowing from the turbine is divided into two directions and expanded by flowing through the stages on both sides;
A double flow steam turbine characterized by being provided with a flow guide ring that closes the space between the two shroud plates via an airtight ring.