JPH0455202Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to turbines such as gas turbines and steam turbines, and more particularly relates to improvement of the gas outlet portion thereof.

BACKGROUND ART A turbine is known in which gas exiting a turbine is decelerated by a gas diffuser and guided from a gas outlet casing to an exhaust duct, and conventional examples thereof are shown in FIGS. 3a, 3b, and 3c. There is something shown in

In these figures, the gas leaving the turbine 1 is transferred to a gas diffuser 2 and a gas outlet casing 3.
The gas is decelerated in a gas passage surrounded by and guided from the outlet 9 of the gas outlet casing 3 to an exhaust duct (not shown). The area of the cross section 6 of the gas passage increases as it approaches the outlet of the gas diffuser 2.

Problems to be Solved by the Invention Incidentally, such conventional turbines have had the problem of reduced turbine efficiency due to the following two drawbacks.

The first drawback is that the flow rate of the gas leaving the turbine 1 is very high, and the high-speed gas passing through the outlet of the gas diffuser 2 is in the space 4 outside the gas diffuser.
, a vortex is generated at the outlet end 10 of the gas diffuser 2 and the space 4 is therefore useless as a gas passage due to the vortex.

That is, a vortex is generated at the outlet end 10 of the gas diffuser 2, the space 4 is clogged with the vortex, and the area of the gas passage cross section 5 of the gas outlet casing 3 becomes small, resulting in a shortage of gas passage area.

The second drawback is that in the gas passage cross section 5 of the gas outlet casing 3, θ=180° to 90° and 180° to 270°.
Although the gas amount increases over time, θ=
Since the gas passage cross section 5 from 90° to 270° is the same everywhere, the gas cannot be discharged smoothly.

That is, since the outer and inner walls of any part of the gas passage from θ=90° to 270° of the gas outlet casing 3 are formed with a radius of 7 and a radius of 8, respectively, The gas passage cross section 5 is the same everywhere. Therefore, θ=
The 180° cross section and the θ=90° cross section have the same cross-sectional area, and the amount of gas at θ=90° is larger, so the gas density is higher in the θ=90° cross section. In other words,
From θ=180° to 90° and θ=180° to 270°,
The gas density becomes high and the gas does not flow smoothly.

The present invention was made to solve the problems of the prior art, and it prevents the generation of vortices at the outlet end of the gas diffuser and expands the effective area of the gas passage. Allow the gas to flow smoothly to the outlet of the gas outlet casing,
The purpose of the present invention is to provide a turbine with improved turbine efficiency.

Means for Solving the Problems In order to solve the above problems, the present invention provides a turbine in which the gas exiting the turbine is decelerated by a gas diffuser and guided from the gas outlet casing to the exhaust duct. A flange-like wake prevention plate is provided on the outer periphery of the outlet end of the diff user to prevent the generation of vortices, and the gas passage of the gas outlet casing is formed into a volute shape with the outlet side widened.

Effect: According to the above means, the brim-like wake prevention plate provided on the outer periphery of the outlet end of the gas diffuser allows the high flow rate gas flowing through the outlet of the gas diffuser to flow outside the gas diffuser. It is possible to prevent the gas in the space from being drawn in, prevent the generation of vortices, and expand the effective area of the gas passage. Further, by forming the gas passage of the gas outlet casing into a volute shape with a wider outlet side, the gas flow velocity can be made substantially the same in any cross section of the gas passage, and the gas can be discharged smoothly. And the 2 mentioned above
These two effects can improve the efficiency of the turbine.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

In FIG. 1a, the gas leaving the turbine 1 is
The gas is decelerated in a gas passage surrounded by the gas differential user 2 and the gas outlet casing 3, and is guided from the gas outlet casing 3 to an exhaust duct (not shown).

In such a turbine, according to the present invention, a flange-shaped wake prevention plate 20 is provided on the outer periphery of the outlet end of the gas diffuser 2 to prevent generation of vortices. That is, the flow rate of the gas exiting the turbine 1 is very high, and the high flow rate gas passing through the outlet of the gas diffuser 2 flows into the space 4 outside the gas diffuser user.
However, by providing a wake prevention plate 20 on the outer periphery of the outlet end of the gas diffuser 2, the gas in the space 4 is prevented from being drawn in, and the generation of vortices is prevented. This eliminates the reduction in the area of the gas passage due to the vortex, and allows the effective area of the gas passage to be expanded.

Further, according to the present invention, as shown in FIG. 1b, the gas passage of the gas outlet casing 3 is formed into a volute shape with the gas outlet 9 side widened, so that the gas flow velocity is almost constant in any cross section of the gas passage. They are made to be the same so that gas can be discharged smoothly.

That is, in the embodiment shown in FIG. 1b, the gas passage cross section 5 of the gas outlet casing 3 is increased from θ=180° to 90° and from 180° to 270° as shown in FIG. The gas flow velocity is made to be approximately the same in all parts of the throat, so that the gas is smoothly discharged from the gas outlet 9.

Effects of the Invention As described above, according to the present invention, the brim-like wake prevention plate provided on the outer periphery of the outlet end of the gas diffuser in the turbine prevents high flow velocity from flowing through the outlet of the gas diffuser. A volute shape that prevents gas from getting into the space outside the gas diffuser user, prevents the generation of vortices, expands the effective area of the gas passage, and widens the gas passage of the gas outlet casing on the outlet side. By doing so, the gas flow velocity can be made substantially the same in any cross section of the gas passage, and the gas can be discharged smoothly, thereby achieving the effect of improving the efficiency of the turbine. .

[Brief explanation of the drawing]

Fig. 1a is a schematic longitudinal sectional view showing an embodiment of the turbine according to the present invention, Fig. 1b is a front view of the gas outlet casing, and Fig. 2 shows the relationship between the gas passage area and angle of the gas outlet casing. Figure 3a
The figure is a schematic longitudinal sectional view showing a conventional turbine, No. 3b.
The figure is a front view of the gas outlet casing, and FIG. 3c is a sectional view taken along line CC in FIG. 3a. 1... Turbine, 2... Gas differential user, 3
...Gas outlet casing, 4...Space, 5...Gas passage cross section, 9...Gas outlet, 20...Wake prevention plate.

Claims (1)

[Scope of utility model registration request] In a turbine in which gas exiting the turbine is decelerated by a gas diff user and guided from a gas outlet casing to an exhaust duct, a flange-shaped wake prevention device prevents generation of a vortex on the outer periphery of the outlet end of the gas diff user. A turbine characterized in that a plate is provided, and the gas passage of the gas outlet casing is formed into a volute shape with a wider outlet side.