JP6972035B2 - Static blades for turbine diaphragms and related turbine diaphragms - Google Patents

Description

The present invention relates to a vane ring structure for axial flow turbines, especially steam turbines.

In particular, the invention relates to a turbine diaphragm.

A steam turbine is a rotating machine intended to convert the thermal energy of steam into mechanical energy for driving an alternator, pump, or any other rotating mechanical receiving side. Generally, steam turbines include high pressure modules, medium pressure modules, and low pressure modules.

Steam turbines typically have a symmetrical or asymmetric single-flow or double-flow inner body, which surrounds a rotor with blades and a fixed or stationary blade that forms a diaphragm suspended within the inner body. Support. The diaphragm is configured to direct the steam flow in a particular direction towards the rotor blades, thereby accelerating the steam flow.

The present invention relates to known types of structural diaphragms called "spacer band diaphragms" and "platform diaphragms".

In the so-called "spacer band diaphragm" type structure 10 shown in FIG. 1a, the blade aerofoil 11 is attached to the inner ring 12 and the outer ring 13 by means of inner and outer annular bands 14 and 15 bent from a flat band. Fixed in the radial direction. The through hole 16 is cut out in the bands 14 and 15 by, for example, a laser so as to fit the cross section of the aerofoil shape. Next, the end portion of the aero foil 11 is inserted into the through hole 16 and fillet welded in place. The inner band 14 is welded to the inner ring 12 and the outer band 15 is welded to the outer ring 13. This type of structure has a relatively small amount of blade machining compared to other types of structures used in steam turbines.

For example, in the so-called "platform diaphragm" type structure 20 shown in FIG. 1b, the blade aerofoil 21 has two bilateral ends that are substantially integral with the radial inner and outer platforms 22 and 23. It has a vane-shaped cross section. Blade aero foils and platforms are machined from solid rods or forged. A complete annular stationary wing is assembled by assembling a series of combination of aerofoil-platform components between the inner ring and the outer ring (not shown) and welding the platform to the ring. Depending on the platform, such a diaphragm has better mechanical strength than the spacer band type, but at a much higher manufacturing cost.

European Patent No. 1847689 (A2)

An object of the present invention is to improve the above-mentioned drawbacks.

It is a specific object of the present invention to provide a diaphragm type structure which has good performance characteristics and is economical to manufacture.

In one embodiment, the vane for an axial flow turbine has an aerofoil portion having a leading edge, a trailing edge, a positive pressure side, and a negative pressure side, and a radial inner and outer reinforcing portions integral with the aerofoil portion. Be prepared.

Each reinforcement closely follows the shape of the cross section of the aerofoil portion.

The reinforced portion improves the mechanical strength of the spacer band diaphragm without increasing manufacturing costs.

It is advantageous that each reinforcing portion has a substantially larger cross section than the cross section of the aerofoil portion. The cross section of the reinforced portion has a rounded enlarged shape corresponding to the leading edge surrounding the leading edge of the aerofoil portion and a thin portion corresponding to the trailing edge surrounding the trailing edge of the aerofoil portion.

The vane can be made, for example, from an alloy steel material containing 12% chromium.

According to the second aspect, the present invention has a plurality of identical annulus rings of the same vane as described above and inner and outer having through holes shaped to accommodate the inner and outer reinforcements of each vane. With respect to an axial flow turbine diaphragm structure comprising a spacer band of the same and radial inner and outer diaphragm rings surrounding an annular spacer band.

According to one embodiment, each reinforcement is welded to the corresponding spacer band by a weld.

Welds are located, for example, on each leading and trailing edge of each reinforcing portion.

According to one embodiment, the inner spacer band is welded to the inner ring and the outer band is welded to the outer ring.

The present invention is considered as a completely non-limiting example and will be better understood by reviewing the detailed description of some embodiments shown in the accompanying drawings.

It is a figure of a known spacer band turbine diaphragm type structure. It is the figure of the fixed wing which integrated the platform for use in the known platform turbine diaphragm type structure. It is a three-dimensional perspective view of a part of the steam turbine diaphragm according to the embodiment of this invention. FIG. 3 is a three-dimensional perspective view of a stationary wing for use in the diaphragm structure of FIG. It is the figure which looked at the stationary wing of FIG. 3 from the top. FIG. 3 is a radial cross-sectional view of the stationary blade of FIG. 3 welded to the spacer band of the steam turbine diaphragm of FIG.

Refer to the accompanying drawings for the following detailed description of the exemplary embodiment. The same reference code in different drawings is considered to be the same or similar element. Moreover, the drawings are not always drawn in proportion to the actual size.

As shown in FIG. 2, a portion of the turbine steam turbine diaphragm 30 comprises a nozzle unit with a plurality of identical static blade aerofoils 32, the nozzle units being inner and outer bent from a flat band. An annular spacer bands 38, 40 are radially fixed to the inner ring 34 and the outer ring 36.

The inner and outer rings 34, 36 are concentric, similar to the inner and outer spacer bands 38, 40.

Through holes 38a and 40a are provided in the inner and outer spacer bands 38 and 40, respectively. As shown, the through holes are open at both ends to accommodate the stationary wings. The through holes 38a and 40a may be cut out into the spacer bands 38 and 40, for example, by a laser so as to fit the cross section of the aerofoil shape. Next, the end portion of the aero foil 32 is inserted into the through hole and fillet welded in place. The inner spacer band 38 is welded to the inner ring 34 and the outer band 40 is welded to the outer ring 36.

As shown in FIGS. 3 and 4, each stationary blade 32 has an inner end portion 32a in contact with the inner spacer band 38 and an outer end portion opposite to the inner end portion 32a in contact with the outer spacer band 40. It has an aerofoil portion 44 with an elongated body having 32b.

The inner and outer ends 32a and 32b are connected to the inner and outer spacer bands 38 and 40 by welding with a welding bead configured between the end and the spacer band, respectively. In this way, each vane is welded to both the inner spacer band and the outer spacer band.

Each stationary wing 32 has a substantially vane-shaped cross section, as shown in FIG. 4, having, for example, a rounded enlarged shape corresponding to the leading edge 44a and a thin portion corresponding to the trailing edge 44b. Have.

As shown in FIGS. 3 and 4, the inner and outer ends 32a, 32b of each vane 32 are provided with inner and outer reinforcing portions 46, 48, respectively. Each reinforcing portion 46, 48 has a rounded enlarged shape corresponding to the leading edges 46a, 48a, and a thin portion corresponding to the trailing edges 46b, 48b, of the aerofoil portion 44 as shown in FIG. It has a slightly larger cross section than the cross section.

Each reinforcing portion 46, 48 surrounds the entire cross section of the corresponding end so as to have a substantially larger cross section than the cross section of the aerofoil portion 44. Therefore, the shape of the reinforcing portions 46, 48 as a whole, that is, on and near the leading and trailing edges 44a, 44b, and the negative and positive pressure sides of the aerofoil portion 44, is the cross section of the aerofoil portion 44. Close to the shape.

The first and second reinforcing portions 46, 48 slide into the through holes 38a, 40a of the spacer bands 38, 40 to which they fit, as shown in FIG. Once all the vanes 32 are assembled within the spacer bands 38, 40, they must be firmly welded in place. Each leading and trailing edge of each reinforcing portion is welded to the corresponding spacer band by welds 50a, 50b, and 52a, 52b. The welds 50a, 50b, and 52a, 52b are shown by diagonal lines in FIG.

The vane 32 is made, for example, from an alloy steel material containing 12% chromium.

The stationary wing is reinforced by providing a reinforcing portion at each end of the aero foil portion.

According to the present invention, the diaphragm structure is economically and easily manufactured while having good mechanical strength.

10 Spacer band Diaphragm type structure 11 Aerofoil 12 Inner ring 13 Outer ring 14 Inner annular band 15 Outer annular band 16 Through hole 20 Platform Diaphragm type structure 21 Blade Aerofoil 22 Inner platform 23 Outer platform 30 Diaphragm 32 Static wing 32a Inner end 32b Outer end 34 Inner ring 36 Outer ring 38 Inner annular spacer band 38a Through hole 40 Outer annular spacer band 40a Through hole 44 Aerofoil part 44a Leading edge 44b Trailing edge 46 Inner reinforcement Part 46a Leading edge 46b Trailing edge 48 Outer reinforcement 48a Leading edge 48b Trailing edge 50a Welded 50b Welded 52a Welded 52b Welded

Claims (8)

An aerofoil portion (44) having a leading edge (44a), a trailing edge (44b), a positive pressure side, and a negative pressure side,
A vane (32) for an axial-flow turbine provided with an aero-foil portion (44) and an integral radial inner and outer reinforcement portion (46, 48).
Each of the inner and outer reinforcing portions (46, 48) closely follows the shape of the cross section of the aerofoil portion (44).
The distance between the inner portion (46) and the outer reinforcing portion (46, 48) at the leading edge (44a) is the distance between the inner portion (46) and the outer reinforcing portion at the trailing edge (44b). Longer than the distance to (46, 48),
Each of the inner and outer reinforcing portions (46, 48) has a cross section substantially larger than the cross section of the aerofoil portion (44), and the leading edge (44a) of the aerofoil portion (44). The rounded and enlarged shape corresponding to the leading edge (46a, 48a) surrounding from the positive pressure side to the negative pressure side, and the trailing edge (44b) of the aerofoil portion (44) from the positive pressure side. A stationary wing with a thin portion corresponding to the trailing edge (46b, 48b) surrounding over the negative pressure side. The stationary wing according to claim 1, wherein each of the inner and outer reinforcing portions (46, 48) has a cross section surrounding the entire circumference of the aerofoil portion (44). The stationary blade according to claim 1 or 2, wherein the stationary blade (32) is made of an alloy steel material. The stationary blade according to claim 3, wherein the alloy steel material contains 12% chromium. A plurality of the same stationary blade rings according to any one of claims 1 to 4.
An inner and outer spacer band (38, 40) having through holes (38a, 40a) shaped to accommodate the inner and outer reinforcing portions (46, 48) of each vane (32).
Axial turbine diaphragm structure comprising radial inner and outer diaphragm rings (34, 36) surrounding the inner and outer spacer bands (38, 40). The axial flow turbine according to claim 5, wherein each of the inner and outer reinforcing portions is welded to the corresponding inner and outer spacer bands (38, 40) by welds (50a, 50b, 52a, 52b). Diaphragm structure. 6. The welded portion (50a, 50b, 52a, 52b) is arranged at the leading and trailing edges (48a, 48b, 46a, 46b) of the inner and outer reinforcing portions (46, 48), claim 6. Described axial flow turbine diaphragm structure. Any of claims 5 to 7, wherein the inner spacer band (38) is welded to the inner diaphragm ring (34) and the outer spacer band (40) is welded to the outer diaphragm ring (36). The axial flow turbine diaphragm structure according to claim 1.

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