CN1944962A

CN1944962A - Steam turbine exhaust diffuser

Info

Publication number: CN1944962A
Application number: CNA2006101420320A
Authority: CN
Inventors: E·沙劳
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 2005-10-06
Filing date: 2006-09-30
Publication date: 2007-04-11
Also published as: EP1772595A3; JP2007100701A; US20070081892A1; EP1772595A2

Abstract

An axial flow steam turbine includes an exhaust diffuser in the form of a volute (40) for diffusing the exhaust steam and turning the exhaust steam from a generally axial flow direction to a generally radial direction. The volute exit (46) may be at the bottom or to one side of the steam turbine. The volute and casing are independently mounted relative to one another on a foundation with a flexible joint therebetween.

Description

The exhaust diffuser of steam turbine

Technical field

The present invention relates to steam turbine, particularly a kind of scroll casing shape exhaust diffuser.

Background technique

In existing steam turbine, the inner housing of steam turbine has the vertical exhaust hood to the encirclement that divides and extend with two ends of opposite sides thereof along this turbine as double fluid to venting gas appliance.This Large Box columnar structure covers the whole low pressure section of turbine.The steam outlet of turbine is roughly taper, and steam exhaust-gas is guided again, and forwarding to respect to this axial flow direction from the flow direction of stretching vertically substantially is the flow direction of 90 degree.Flow direction of these 90 degree can be along in any plane, downwards, upwards or laterally.Therefore the existing exhaust hood of this steam turbine constitutes a large-scale straight line type structure at the outlet end place of this tapered segment, is used to make vapor stream with right-angle turning and diffusion.This vapor stream path thereby be tortuous causes damage and disadvantageous pressure falls.Also can understand, each parts that contacts turbine for the maintenance purpose are difficult as bearing, because need remove the exhaust hood first half.Secondly, be appreciated that the exhaust hood in traditional steam turbine supports inner casing and the steam path parts of being correlated with such as the dividing plate etc. of turbine usually.Therefore, need provide a kind of new geometrical shape to improve the pressure recovery of exhaust steam and the overall performance of turbine.

Summary of the invention

In a preferred embodiment of the invention, provide a kind of axial flow steam turbine runner, comprising: a rotor and a shell of limiting this axial steam flow channel; And the exhaust diffuser that turbo machine is used, comprise a spiral case, be used for this exhaust steam of diffusion and with this exhaust steam from an axial substantially the flow direction horizontal and tangential substantially direction of turning round.

The accompanying drawing summary

Fig. 1 is the partial schematic diagram according to half of the steam turbine of the downward exhaust of a kind of double fluid of prior art;

Fig. 2 is a kind of local side cross-sectional, view that the exhaust diffuser of spiral case configuration is arranged of the illustration of steam engine; And

Fig. 3 and 4 is the axial end view that can be used to accept two kinds of embodiments of the exhaust steam that comes from steam turbine.

Detailed Description Of The Invention

Referring now to accompanying drawing, Fig. 1 particularly, the part of illustration steam turbine 10 among the figure comprises the rotor 12 that a plurality of turbine blades 14 are installed.A plurality of dividing plates 18 are installed on the inner casing 16.Radially steam inlet 20 substantially that is provided with along the center is applied to steam on each turbine blade and stator vane on the axial opposite sides thereof of this turbine, to drive rotor.The stator vane of dividing plate 18 and vertically adjacent vanes 14 form the at different levels of this turbine of forming a runner.Be appreciated that steam discharges from the final stage of turbine, so that flow into a unshowned condenser.

An outer exhaust hood 22 also is shown among Fig. 1, and this cover centers on and supports inner casing and other parts such as the bearing of turbine.In Fig. 1, this turbine comprises vapor horn 24, is used for guiding the steam of discharging from turbine to enter into outlet 26, so that flow to one or more condensers.Owing to adopt exhaust hood to support turbine, bearing and accessory, the path of exhaust steam is tortuous and runs into the pressure loss, can reduce performance and efficient subsequently.

Referring now to Fig. 2, diagram one aspect of the present invention, wherein identical parts added 1 before the same numeral of Fig. 1.As shown in the figure, the exhaust hood 22 of prior art omits fully and replaces volute diffuser 40.Diffuser 40 comprises that one is connected to taper diffusion section 42 on the inner casing 116 with flexible joint 44.Spiral case 40 has an axis that is parallel to the rotation axis of rotor 112.The axis of spiral case 40 is substantially perpendicular to the direction of passing through the spiral air-flow substantially of this spiral case around this axis.Therefore, the steam of discharge flows into spiral case 40 from the final stage of turbine basically vertically, and air-flow changes about 90 degree of its flow direction there.In addition, utilize spiral case 40, the geometrical shape of spiral case can make steam expansion and reduce its pressure.Spiral case 40 also guides the steam of diffusion by an outlet 46 that is connected on one or more condenser (not shown).As shown in Figure 3, spiral case comprises an inner passage 48, and the latter is long-pending along the direction increasing section towards outlet 46, thus the steam of diffusion discharge.Be appreciated that not necessarily discharge downwards of outlet 46, and can be that side direction is discharged or upwards discharged.In arbitrary configuration, single spiral case can be from single current steam turbine exhaust steam, and perhaps a pair of spiral case can be from double-current steam turbine exhaust steam.A kind of double-walled spiral case of diagram among Fig. 4, it has a partition wall 50 that forms a pair of diffuser exit passage.

Except owing to the steam in this spiral case the steam of turbine is discharged the performance of the improvement that the diffusion on the side produces, also have extra advantage.For example, the exhaust hood in the traditional steam turbine of the prior art can save fully, and no longer needs to support inner casing and the relevant dividing plate of steam path parts as coming out from exhaust hood.Do not surround inner casing because do not re-use exhaust hood, so saved expense yet.Also reduced the total volume of turbine.Previously the vapor horn that needs is also different fully.Importantly, each directly supporting of basis of the inner casing of turbine and spiral case by turbine.For the ease of these, between inner casing and turbine 40, provide a flexible joint 44 (Fig. 2).This flexible joint can be many variety classeses such as expansion bellows, to allow differential thermal expansion.Secondly, no longer need the previous exhaust hood that uses in order to support the turbine bearing.As shown in Figure 2, bearing 54 can be bearing on the pillar 56, and the latter transfers the directly supporting of basis by turbine.Therefore, this pillar provides the support of a rigidity for bearing, and the result has the turbine reliability of improvement.This spiral case can be used any combination of composite material, steel plate or steel pipe, structural steel, fiber reinforced plastic or these materials, to obtain required structural integrity and desired vapor stream diffusion property.

Though got in touch and currently thought that the most practical and preferred embodiment describe the present invention, but be appreciated that, the invention is not restricted to the disclosed embodiments, on the contrary, the present invention's expection comprises various modifications and the equivalent device in the scope of the appended claims and the spirit.

Claims

1. axial flow steam turbine runner comprises:

A commentaries on classics (12) and a shell (16) that limits this axial steam flow channel; And

A turbine exhaust Diffuser comprises a spiral case (40), be used to make this exhaust steam diffusion and with it from an axial flow direction horizontal and tangential substantially direction of turning round substantially.

2. the runner according to claim 1 is characterized in that, described spiral case (40) has an axis that is parallel to the axis of this runner substantially.

3. the runner according to claim 1 is characterized in that, described exhaust diffuser and described shell are to be installed on independently of one another on the basis.

4. the runner according to claim 1 is characterized in that, comprises a flexible joint (44) between described exhaust diffuser and described shell (16).

5. the runner according to claim 1 is characterized in that, described spiral case (40) has an axis that is parallel to the axis of this runner substantially, described spiral case end at one face down, towards last or horizontal outlet (46).

6. the runner according to claim 1 is characterized in that, described spiral case (40) has an axis that is parallel to the axis of this runner substantially, and described exhaust diffuser and described shell are installed on the basis independently of one another.

7. the runner according to claim 6 is characterized in that, comprises a flexible joint (44) between described exhaust diffuser and described shell.