JPH03179104A - Steam turbine chamber - Google Patents

Abstract

PURPOSE:To eliminate the temperature difference of each part so as to prevent cat-like- chamber of a chamber by passing exhaust of a high pressure turbine between an outer chamber in the high pressure turbine part and a thermal shield provided on the inner surface thereof so as to lead-in the exhaust serving as a cooling steam toward an intermediate pressure turbine. CONSTITUTION:A thermal shield 3 is installed on the outside of a high pressure inner chamber 2 in an outer chamber 1, and the inlet of a high pressure exhaust steam 15 is provided on the high pressure exhaust side end part by means of holes 4 opened in the outer chamber 1. In the same way, the inlet of an intermediate pressure cooling steam is provided also on an intermediate pressure inlet side end part by means of holes 5 opened on the outer chamber 1. Moreover, a pipe is arranged on the outside of the outer chamber 1 instead of respective holes 4, 5 so as to communicate a high pressure exhaust part 7 to the thermal shield 3 installing part, and the installing part to the thermal shield 6 installing part of the intermediate pressure inlet respectively. The cooling steam passes between the outer chamber 1 of the high pressure part and the thermal shield 3 from the high pressure exhaust part 7, so as to lead-in the cooling steam between the thermal shield 6 and the outer chamber 1 of an hollow inlet part 10.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to improvements in steam turbine casings, particularly steam turbine casings having integrated high and intermediate pressure elements.

[Prior Art] FIG. 2 is a longitudinal cross-sectional view showing an example of a conventional high-intermediate pressure integrated element of a steam turbine. High-pressure steam entering from the main steam inlet (21) passes through the high-pressure turbine stage (22), performs work, passes through the high-pressure exhaust section (7), and then passes through the high-pressure steam outlet (23).
) to leave. Further, the reheated steam that enters from the reheated steam inlet (24) performs work in the intermediate pressure turbine stage (25), and exits from the intermediate pressure steam outlet (26).

(27), (28), and (29) are all oil outlets.

In such a steam turbine, in order to cool the intermediate pressure turbine, leakage steam (11) from the high pressure dummy ring (9) passes through the intermediate pressure dummy ring (8) and is transferred to the intermediate pressure dummy ring leakage steam (12).
) is introduced into the intermediate pressure turbine. Also, the medium pressure inlet (
10) is provided with a thermal shield (6), cooling steam (13) is also introduced into the thermal shield (6) through a hole or pipe (not shown).

By the way, the amount of high-pressure dummy leaking steam and the amount of medium-pressure cooling steam (
The following two states occur depending on the balance between the amount of leaking steam in the intermediate pressure dummy ring and the amount of cooling steam in the intermediate pressure inlet thermal shield.

a) When the amount of high-pressure dummy ring leakage steam is greater than the amount of medium-pressure cooling steam: As shown in the upper half of Figure 2, some of the high-pressure dummy ring leakage steam (11) is medium-pressure It flows into the intermediate pressure turbine as cooling steam, and the rest flows into the high pressure casing (2) and the outer casing (1).
It flows out through the space between to the high pressure exhaust part (7).

b) When the amount of high-pressure dummy ring leakage steam is less than the medium-pressure cooling steam amount: As shown in the lower half of Figure 2, the high-pressure dummy ring leakage steam (11) alone is insufficient as medium-pressure cooling steam. In order to
The insufficient steam is transferred from the high-pressure exhaust section (7) to the high-pressure vehicle compartment (2).
) and the outer casing (1) into the intermediate pressure turbine.

Problem to be solved by the invention and the radial play between the rotor (14) and the seal fin of the medium pressure dummy ring (8) and the rotor (
14) and the radial play, and the relationship is reversed between the upper and lower halves of the turbine.

That is, when the high pressure dummy ring (9) is set higher than the rotor (14) and the intermediate pressure dummy ring (8) is set lower than the rotor (14), the upper half of the turbine In the lower half of the turbine, the play in the high-pressure gummy ring is larger than that in the intermediate-pressure dummy ring, and in the lower half of the turbine, the play in the high-pressure dummy ring is smaller than that in the medium-pressure dummy ring. Then, the balance of leakage steam between the high-pressure gummy ring (9) and the medium-pressure gummy ring (8) will be as shown in a) above in the upper half of the turbine, and as above in the lower half of the turbine. > is the state. At this time, high pressure gummy ring leakage steam (11) flows in the space between the high pressure casing (2) and the outer casing (1) in the upper half of the turbine, and the high pressure casing (2) flows in the lower half of the turbine. ) and outer compartment (
High pressure exhaust steam (15) flows through the space between 1).

In a typical design example, the temperature of the high pressure dummy ring leakage steam (11) is about 470°C and the temperature of the high pressure exhaust steam (15) is about 350°C. Therefore, in the above case, the metal temperature of the outer compartment (1) in the outer part of the high-pressure compartment (2) is close to 470'C in the upper half, and close to 350'C in the lower half. A large temperature difference of about 100° C. or more occurs between the two. When there is a large temperature difference between the upper and lower parts of the outer compartment (1), this causes the outer compartment (1) to be called a cat sled.
) deformation (deformation in which the outer casing chamber curves upward due to bimetallic phenomenon) occurs, and the radial play between the stationary part and the rotating part disappears, resulting in contact vibration and seal fin wear. The reliability and performance of the turbine will be adversely affected.

[Means to solve the problem]

In order to solve the above-mentioned conventional problems, the present invention provides a steam turbine having an integrated high-pressure and intermediate-pressure element, in which a thermal shield is provided on the inner surface of the outer casing of the high-pressure turbine portion.
The present invention proposes a steam turbine casing characterized in that exhaust gas from a high-pressure turbine is introduced as cooling steam into an intermediate-pressure turbine through a space between the outer casing and the thermal shield.

(Function) The present invention is configured as described above, and by providing a thermal shield on the inner surface of the outer casing of the high pressure section and flowing high pressure exhaust steam between the outer casing and the thermal shield, the outer casing of the high pressure section is heated. The inner surface is shielded from the steam flow that may differ between the upper and lower halves of the turbine, and the temperatures of the outer casings of the upper and lower halves are made equal.

〔Example〕

FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention. In this figure, in order to avoid redundancy, the same reference numerals are given to the same parts as those of the conventional device explained with reference to FIG. 2, and detailed explanation thereof will be omitted.

In this embodiment, a thermal shield (3) is attached to a portion of the outer compartment (1) corresponding to the outside of the high-pressure compartment (2). An inlet for high-pressure exhaust steam (15) is provided at the end of the thermal shield (3) on the high-pressure exhaust side by, for example, providing a hole (4) in the outer compartment (1). On the other hand, thermal shield (3)
An inlet for medium-pressure cooling steam is also provided at the end of the medium-pressure inlet side by, for example, providing a hole (5) in the outer casing chamber (1). Instead of these holes (4) and (5), pipes are installed outside the outer compartment (1) to connect the high pressure exhaust part (7) and the thermal shield (3).
) mounting part, the thermal shield (3) mounting part and the thermal shield (6) mounting part of the intermediate pressure inlet may be connected.

In such a device, the thermal shield (6) provided at the intermediate pressure inlet section (10) passes from the high pressure exhaust section (7) between the outer casing (1) of the high pressure section and the thermal shield (3). and the outer compartment (1) of the medium pressure inlet part (10),
Cooling steam is introduced. On the other hand, as the cooling steam introduced into the medium pressure inlet (6) through the medium pressure gummy ring (8), the high pressure dummy ring leakage steam (
11) Either alone or as shown in the lower half of Fig.
1) is a mixture of the high pressure steam outlet (15) and the high pressure gummy ring leakage steam (1]).

In addition, since high-pressure exhaust steam (15) flows through the inner surface of the outer compartment (1), no matter what the state of the steam flow between the high-pressure inner compartment (2) and the outer compartment (1), the outer compartment The metal temperature in (1) is determined by the high pressure exhaust temperature.

[Effects of the Invention] In the present invention, the metal temperature of the outer casing at the outer periphery of the high-pressure inner casing is not affected by the balance of leaked steam between the high-pressure dummy ring and the intermediate-pressure dummy ring, and is determined by the high-pressure exhaust temperature. Therefore, there is no difference in the metal temperature of the outer casing between the upper and lower halves of the turbine, and therefore cat sledding of the casing does not occur. Since there is no radial contact between the turbines and no contact vibrations or seal fin wear, the reliability and performance of the turbine are not compromised.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view showing an example of a conventional high-intermediate pressure integrated element of a steam turbine. (1)...Outer compartment, (2)...High pressure inner compartment. (3)...Thermal shield, (41,(5)・
... Hole (6) ... Thermal shield, (7) ... High pressure exhaust part (8) ... Medium pressure dummy ring, (9) ... High pressure gummy ring. 0ω...Medium pressure inlet part. (10...High-pressure inlet-circle leakage steam. 02)...Medium-pressure inlet thermal shield cooling steam. En...Rotor, 05)...High pressure exhaust steam. (21)...Main steam inlet, (22)...High pressure turbine stage. (23)...High pressure steam outlet, (24)...Reheat steam inlet. (25)...Intermediate pressure turbine stage. (26)...Medium pressure pure air outlet. (27), (28) (29)...Bleed air outlet. agent

Claims (1)

[Claims] In a steam turbine having an integrated high- and intermediate-pressure element, a thermal shield is provided on the inner surface of the outer casing of the high-pressure turbine section, and the exhaust gas of the high-pressure turbine is passed between the outer casing and the thermal shield to the intermediate-pressure turbine as cooling steam. A steam turbine casing characterized in that a steam turbine casing is introduced.