JPH09256808A - Low pressure steam turbine exhaust chamber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently prevent generation of axial vibration because of eccentricity, which is generated in a rotor when water drops dropped on a rotor cools down the rotor partially and the rotor is bent partially, by installing a drain catcher in the vicinity of a ground of a casing in a low pressure steam turbine exhaust chamber. SOLUTION: Steam flowing inside a low pressure steam turbine vehicle interior passes through a final blade 3 in the low pressure steam turbine and is turned into atomized steam, and the atomized steam flows into a low pressure steam turbine exhaust chamber 1. A drain catcher 5 which covers the upper part of the rotor 2 at least and extends toward the final blade 3 in the low pressure steam turbine is installed in the vicinity of a ground 4 of a casing 1a in the low pressure steam turbine exhaust chamber 1. In this way, the atomized steam passed through the final blade 3 in the lower pressure steam turbine is turned into a water drop and is dropped through a gap between the final blade 3 and the casing 1a in the low pressure turbine exhaust chamber 1. The dropping water drop is received by means of the drain catcher 5, so that dropping of the water drop onto the rotor 2 can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low pressure steam turbine exhaust chamber provided with a drain catcher.

[0002]

2. Description of the Related Art A conventional low pressure steam turbine exhaust chamber is shown in FIG. A gland 4 is attached around a rotor (shaft portion) 2 to a gland attachment portion 7 of the casing 1a of the low pressure steam turbine exhaust chamber 1. In this conventional low-pressure steam turbine exhaust chamber, the mist-like wet steam that has passed through the final blade 3 of the low-pressure steam turbine is, as shown in FIG. 3, between the final blade 3 and the casing 1a of the low-pressure steam turbine exhaust chamber 1. Is dropped on the rotor 2 as water droplets.

[0003]

Since there is no means for capturing water droplets near the gland mounting portion of the conventional low pressure steam turbine exhaust chamber, the degree of wetness passing through the last blade of the low pressure steam turbine is not provided. About 10 to 12% of mist-like vapor drops as water droplets on the rotor (shaft portion), and the rotor is locally cooled. Therefore, the rotor may be locally bent to cause eccentricity, resulting in a thermal unbalanced state of the shaft system, which may cause shaft vibration.

The present invention is intended to provide a low pressure steam turbine exhaust chamber which can solve the above problems.

[0005]

In the low pressure steam turbine exhaust chamber of the present invention, a drain catcher that covers at least the upper portion of the rotor and goes to the last blade of the low pressure steam turbine is provided in a portion of the low pressure steam turbine exhaust chamber near the gland of the casing. It is characterized by being attached to.

According to the present invention, since the drain catcher having the above-described structure is provided, mist-like steam that has passed through the final blade of the low-pressure steam turbine is formed as water droplets and a gap between the final blade and the casing of the low-pressure steam turbine exhaust chamber is generated. It is possible to prevent water droplets from falling on the rotor by catching the falling water with a drain catcher.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. In the low-pressure steam turbine exhaust chamber 1, steam flowing in the low-pressure steam turbine casing 6 as shown by an arrow in FIG. 1 passes through the last blade 3 of the low-pressure steam turbine, and has a mist degree of about 10 to 12%. It flows in as steam.

Casing 1 of low pressure steam turbine exhaust chamber 1
A gland 4 is attached around the rotor (shaft portion) 2 in the gland attachment portion 7 of a.

Further, at least the upper part of the rotor 2 is covered with a space between the rotor 2 and a portion of the casing 1a in the vicinity of the gland 4 of the gland mounting portion 7 toward the final blade 3 of the low pressure steam turbine. The drain catcher 5 is attached. As shown in FIG. 2, the drain catcher 5 has an L-shaped portion having a horizontal plate with an upwardly bent portion.
Although formed in a V-shaped cross section, it may have another cross-sectional shape suitable for receiving a falling water drop.

Furthermore, the drain catcher 5 is
It is arranged to cover at least the upper part of the rotor 2,
The rotor 2 may be arranged so as to cover the upper half circumference or the entire circumference.

In the present embodiment, mist-like steam having a wetness of about 10 to 12% that has passed through the last blade 3 of the low pressure steam turbine flows into the low pressure steam turbine exhaust chamber 1 and the casing 1a of the exhaust chamber 1 is used. Water droplets will fall in the gap between the above and the last blade 3. This water drop is received by the drain catcher 5 and does not fall onto the rotor 2.

Therefore, the rotor 2 is prevented from being locally cooled by the water droplets, the rotor 2 is locally bent and eccentricity is caused, and the rotor 2 as a shaft system is prevented from being in a thermal unbalanced state. No shaft vibration (depending on the shaft system, a conventional vibration may be accompanied by a vibration change of about 5/100 to 25/100 mm in both amplitudes) is generated.

[0013]

According to the present invention, since the drain catcher which covers at least the upper portion of the rotor and faces the final blade of the low pressure steam turbine is attached to a portion of the low pressure steam turbine exhaust chamber in the vicinity of the gland of the casing, water droplets are not formed on the rotor. , The rotor is locally cooled and locally bent, causing eccentricity.
It is possible to effectively prevent the shaft vibration from occurring.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a low pressure steam turbine in which an embodiment of the present invention is used.

FIG. 2 is a sectional view of an embodiment of the present invention.

FIG. 3 is a cross-sectional view of a conventional low pressure steam turbine exhaust chamber.

[Explanation of symbols]

 1 Low Pressure Steam Turbine Exhaust Chamber 1a Casing 2 Rotor 3 Final Blade of Low Pressure Steam Turbine 4 Gland 5 Drain Catcher 6 Low Pressure Steam Turbine Cabin 7 Gland Attachment

Claims (1)

[Claims] 1. A low-pressure steam turbine exhaust chamber, characterized in that a drain catcher covering at least an upper part of a rotor and directed to a final blade of a low-pressure steam turbine is attached to a portion of a casing of the low-pressure steam turbine exhaust chamber near a gland.