JPS59213907A - Barrel-type turbine - Google Patents

Abstract

PURPOSE:To prevent an outer casing from overheating by connecting a pipe line having an orifice to a working fluid chamber between the outer and inner casings of a barrel-type turbine and discharging the working fluid. therefrom. CONSTITUTION:A bypass pipe line 22 is connected from a low temp. reheat pipe 23, through a drain pipe line 21 to a working fluid chamber 15 provided between the outer casing 1 and the inner casing 2 of a barrel-type turbine. An orifice 24 is provided on the pipe line 22 to allow constant flow of steam, the quantity of which is restricted by the orifice 24, from the working fluid chamber 15 to the low temp. reheat pipe. Thereby the stagnation of fluid in the working fluid chamber 15 is eleminated, preventing the outer casing from overheating.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field to which the Invention Pertains] The present invention relates to a pot-type turbine having an outer casing that is not divided into upper and lower halves and is integrally shaped like a tail.

[Prior art and its problems]

When the turbine casing is made into a split mold, the flange portion becomes thick and large in order to firmly connect these parts, and it is also necessary to use a large number of expensive poles with high high temperature strength. In order to eliminate these disadvantages, the outer casing is shaped like a pot, eliminating the need for a flange, and a working fluid chamber is installed in the circumferential direction between the inner casing and the outer casing, and the working fluid is supplied from the inner casing. A collar-type turbine is known as one in which compressive force is applied to the inner casing by the pressure of the fluid in the working fluid chamber. With such a configuration, this type of turbine can have a small flange even if the inner casing is a split type, and the force acting on the bolt for tightening can also be made small.

However, in the above-mentioned turbine, the fluid in the working fluid chamber does not flow out from there, so the temperature rises, which increases the temperature of the outer casing, and it is difficult to predict the degree of this temperature rise, making it difficult to install the turbine. The problem is that

[Purpose of the invention]

In view of the above points, an object of the present invention is to provide a pot-type turbine capable of suppressing the temperature rise of the fluid in the working fluid chamber.

[Key points of the invention]

In order to achieve the above object, in the present invention, a conduit having an orifice is communicated with the working fluid chamber, whereby a small amount of working fluid constantly flows out to the outside, and the fluid in the working fluid chamber is reduced. The configuration is such that the temperature is dominated by the fluid temperature of the turbine stage within the inner casing to which the fluid is supplied.

[Embodiments of the invention]

FIG. 1 shows one embodiment of the tail turbine of the present invention; this example is a steam turbine and therefore the working fluid is steam. Reference numeral 1 denotes an outer casing, which is in the form of a collar-shaped casing that is continuous in the circumferential direction and has no flange portion. An inner casing 2 is provided within the outer casing 1 and supports stator vanes 3. A rotor 4 is rotatably provided in the inner casing 2 and has rotor blades 5 on its outer periphery, and a steam working chamber 10 is formed between the inner casing 2 and the rotor 4. The inner casing 2 is fixed to the outer casing 1 by tightening a threaded ring 6 that engages with a threaded portion on the inner circumference of the outer casing 1.

The inner casing 2 is also formed with a steam inlet chamber 7 and a steam exhaust chamber 8, and the steam supplied from the steam outlet 9 is sent from the steam inlet chamber 7 to each operating stage of the turbine formed by the stationary blades 3 and rotor blades 5. The steam does work in the steam chamber, passes through the exhaust chamber 8, and is discharged from the steam outlet 11.

A working fluid chamber, ie, a steam chamber 15 in this example, is formed between the outer casing 1 and the inner casing 2 and is sealed by an airtight ring 13, 14. Steam room 15
is communicated with the steam working chamber 10 by a balance hole 16. The position of the balance hole 16 is from steam inflow chamber 7 to 4.
The pressure within the steam working chamber 10 at that portion is selected to be the fifth stage, and the pressure within the steam working chamber 10 at that portion acts on the steam chamber 15. As a result, the inner casing receives a compressive force in the radial direction.
The strength of the inner casing itself can be kept low in order to resist the radially outward forces exerted by the steam pressure within the inner casing.

In order to drain the condensed water that accumulates in the steam chamber 15, a plurality of drain ports 17, 18, 19 are provided, each of which is connected to a drain line 21, as illustrated for the drain port 17. The drain pipe has a valve 25, and when a predetermined amount of condensed water has accumulated, the drain pipe 21 is brought into a conductive state and the condensed water is discharged.

In this example, J3 is provided with a bypass pipe 22 extending from this drain pipe 21, and this bypass pipe is connected to a low temperature reheat pipe 23. An orifice 24 is provided in the bypass line 22 so that a limited amount of steam determined by the opening size of the orifice 24 from the steam chamber 15 is constantly transferred to the drain line 21. It flows through orifice 24 and bypass capsule/channel 22 . Therefore, the steam temperature in the steam chamber 15 is maintained approximately at the temperature of the steam at the operating stage where the balance hole 16 is positioned. Therefore, overheating of the outer casing 1 due to overheating of the steam temperature in the steam chamber 15 is avoided, and furthermore, the temperature of the high pressure stage of the inner casing rises due to the insufficient cooling effect of the steam, and the outer casing is overheated due to radiation. This can be prevented.

The orifice 24 may have a constant opening size, but if it is a variable orifice, the opening is increased at the time of turbine startup to increase the flow rate of steam passing through the steam chamber 15 and promote uniform heating of the casing. It can be used for.

Moreover, instead of using a variable orifice, it is also possible to provide a bypass path, and an embodiment in which this is done is shown in FIG. In this example, the parts not shown have the same structure as the example in FIG. 1. In the embodiment shown in FIG. 2, a bypass passage 31 is provided in parallel with the orifice 24, and the opening and closing of this passage is controlled by a bypass valve 32. Bypass valve 32 opens upon startup of the turbine to increase the flow of steam through steam chamber 15 .

FIG. 3 shows another embodiment of the invention, in which the first
Components corresponding to the example in the figure are labeled with the same reference numerals.
Therefore, a description of these will be omitted.

In this embodiment, bypass lines 41 and 42 extend from a plurality of locations other than the attachment point of the drain line 21 of the air chamber 15, and are connected to the bypass lines 22 through orifices 43 and 44 similar to the orifice 24, respectively. It is connected. In this configuration, by appropriately selecting the same opening areas of the orifices 24, 43, 4, 4, it is possible to actively control the temperature distribution of the inner and outer casings.

(Effects of the Invention) In the present invention, since the fluid in the working fluid chamber does not stagnate, overheating of the outer casing can be prevented, and the temperature of this fluid is determined by which stage of the turbine the fluid is led from. This makes it easier to design the entire turbine to deal with thermal stress.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a collar-type turbine which is one embodiment of the present invention, FIG. 2 is an explanatory diagram of a pipe line showing a part of another embodiment of the present invention, and FIG. FIG. 3 is a sectional view of still another embodiment of the invention. (Explanation of symbols) 1: External casing 2: Internal casing 15: Working fluid empty 21.22, 41.42: Pipe line 24.43.44 Niorifice 31: Bypass path Patent applicant Fuji Electric Manufacturing Co., Ltd.

Claims (1)

[Claims] 1) It has a vase-shaped outer casing and an inner casing, and a working fluid chamber is formed between these casings, and the working fluid is supplied to the working fluid chamber from inside the inner casing. In the pot-type turbine, in the working fluid chamber,
A tail-shaped turbine characterized in that a pipe line having an orifice is communicated with each other so that working fluid is constantly discharged from a working fluid chamber. 2. Claims[/JlThe turbine according to paragraph 1 is J
), wherein the orifice is variable. 3) A pot-type turbine according to claim 1, characterized in that a bypass passage 170 whose closing is controlled by a valve is provided in parallel with the orifice. 4) The turbine according to any one of claims 1 to 3, characterized in that a plurality of the pipes are connected to the working fluid at positions separated from each other. type turbine.