JPH0373721B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to steam turbines, and more particularly to steam turbines having an inner casing and vane rings.

Conventional steam turbines are constructed with an outer casing, an inner casing disposed within and supported from the outer casing, and a vane ring supported within the inner casing. By supporting the vane ring within the inner casing, exposure of the outer casing to the highest pressures and temperatures can be avoided. However, if the inner casing is placed between the vane ring and the outer casing, the outer casing will have a relatively large diameter, which is not desirable, since the outer casing must accommodate both the vane ring and the inner casing. .

It is therefore an object of the present invention to significantly reduce the turbine diameter while retaining the advantage of the inner casing of avoiding exposing the outer casing to the highest pressures and temperatures.

To this end, the present invention comprises a horizontally split cylindrical outer casing, a horizontally split cylindrical inner casing partially disposed within and supported from the outer casing; a divergent vane ring disposed generally within the outer casing and partially within the inner casing and surrounding a turbine rotor, the vane ring having a low pressure end within the inner casing; only a high pressure end of a relatively small diameter vane ring projecting axially from the casing is disposed within the inner casing, and the low pressure end extends radially outwardly to the outer casing; A steam turbine is provided having an integral support arm supported directly on the outer casing.

By arranging only the small-diameter high-pressure end of the vane ring inside the inner casing in this way, the inner casing can be made relatively small in diameter, making the diameter and wall thickness of the inner and outer casings smaller. be able to. Also, because the steam pressure and temperature are relatively reduced at the low pressure end of the vane ring, the advantage of the inner casing to avoid exposing the outer casing to the highest pressures and temperatures is not compromised.

The invention will become more readily apparent from the following description of preferred embodiments thereof, illustrated in the accompanying drawings.

The prior art is described in FIGS. 1 and 2, in which the steam turbine 103 shown is operationally identical to the turbine 3 shown in FIGS. 3 and 4 constructed in accordance with the present invention. It is designed with temperature, pressure and steam amount. Reference numerals in the 100 range in the prior art represent similar parts to those designated by the reference numeral 100 minus 100 in FIGS. 3 and 4.

Steam turbine 3 according to a preferred embodiment of the invention
are arranged within the outer casing 5 and are connected to each other by bolts 11 with horizontally split cylindrical outer housings or casings 5 connected to each other by bolts 7 and by supports 13 to the outer casing. 5 and a horizontally split cylindrical inner casing 9 . Disposed partly in the inner casing 9 and partly in the outer casing 5 are longitudinally split vane rings 15, which are also interconnected by bolts 17. . As shown in the drawing, the blade ring 15 has a wide-end shape, with the low-pressure end of the blade ring 15 having a relatively large diameter protruding in the axial direction from the inner casing 9, and the high-pressure end of the blade ring 15 having a relatively small diameter protruding from the inner casing 9 in the axial direction. is located within the inner casing 9 and has an integral support arm 19 whose low pressure end extends radially outwards to the outer casing 5 and is supported directly thereon. The vane ring 15 also has a plurality of circumferentially extending grooves 21 which receive annular rows of fixed vanes 23 therein.

A turbine rotor 25 having a plurality of annular rows of rotating blades 27 is disposed within the blade ring 15, and the rows of rotating blades 27 are arranged in the form of fingers to form fixed blades 2.
It is between the 3 columns.

A nozzle block 29 and a nozzle chamber 31 are arranged within the inner casing 9 at one end of the vane ring 15 to allow steam to flow into the vane passage. Further, a dummy ring 33 is disposed inside the inner casing 9, and the dummy ring 33 is connected to the integrated balance disk 3 on the turbine rotor 25.
5 to balance the thrust generated by the steam and acting on the rotating blades and rotor.

By supporting the low pressure end of the vane ring from the outer casing 5 rather than the inner casing 9, there is the advantage of increasing the moment of resistance acting on the vane ring and reducing stress. feather ring 1
The support area of 5 moves to a lower temperature area which lowers the demands on the material and increases the allowable stresses, and also reduces the overall diameter, wall thickness and bolting requirements of the inner and outer casings, and further reduces the stress from the vane ring. Loads are transferred directly to the outer casing, reducing inner casing support size, thus providing savings in material, manufacturing and handling.

[Brief explanation of drawings]

1 is a plan view, partially in section, of a prior art steam turbine with the various upper rings removed but the upper casing installed; FIG.
FIG. 3 is a partial plan view of a steam turbine constructed in accordance with the present invention, with the upper casing and various upper rings partially removed, FIG. 4; 3 is a partial sectional view taken along line - in FIG. 3; FIG. 3...Steam turbine, 5...Outer casing,
9...Inner casing, 15...Blade ring, 1
9...Support arm, 25...Turbine rotor.

Claims (1)

[Claims] 1 a horizontally split cylindrical outer casing 5 , a horizontally split cylindrical inner casing 9 partially disposed within the outer casing 5 and supported from the outer casing 5 , and partially the outer casing 5
a diverging vane ring 15 disposed within and partially within the inner casing and surrounding the turbine rotor 25, the vane ring 15 comprising:
A low-pressure end of the vane ring 15 protrudes axially from the inner casing 9, only a high-pressure end of the vane ring 15 having a relatively small diameter is disposed within the inner casing 9, and the low-pressure end , an integral support arm 1 extending radially outwardly to and directly supported by the outer casing 5;
Steam turbine with 9.