WO1997034086A1

WO1997034086A1 - Device for guiding and dividing a fluid stream and use thereof in a steam turbine

Info

Publication number: WO1997034086A1
Application number: PCT/DE1997/000432
Authority: WO
Inventors: Heinrich Oeynhausen
Original assignee: Siemens Aktiengesellschaft
Priority date: 1996-03-11
Filing date: 1997-03-06
Publication date: 1997-09-18

Abstract

The invention concerns a device (1) for guiding and dividing a fluid stream, in particular of steam, of a medium-pressure sub-turbine into a plurality of low-pressure sub-turbines (15a, 15b, 15c), with a flow duct (2) directed along a median line (3). A flow-divider element (4) lying along the median line (3) divides the cross-section (6) of the flow duct (2) into at least two flow-separated cross-section segments (5a, 5b, 5c) and is twisted along the median line (3) in such a way as to alter the position of the cross section segments (5a, 5b, 5c) along the median line (3).

Description

description

Device for guiding and dividing a fluid flow and use in a steam turbine

The invention relates to a device for guiding and dividing a fluid flow with a flow channel which is directed along a center line. The invention further relates to a use of the device for dividing a steam flow in a steam turbine system.

The division of a fluid stream into several sub-streams is used in various fields of technology. DE 30 32 984 AI, for example, describes a pipe distributor station for the distribution of liquid or vaporous media in pipe networks. A typical case is the distribution of heated water or steam in heating systems. A pipe section is provided for distribution, which has openings spaced apart from one another in the axial direction and is designed in the region of the openings as a double pipe with a respective outlet. DE 25 10 830 B2 describes a device for dividing a fluid flow into several lines, consisting of a space that is rotationally symmetrical to a longitudinal axis and that is fed by a single inlet. With the device from a single fluid stream, the z. B. can contain a powder in suspension, a homogeneous distribution between the different secondary gas flows, which come from the single Fluid¬ flow. A flow divider is described in US Pat. No. 3,794,056, which divides a single flow signal into similar flow pulses. A single feed channel with a constant diameter merges into an area in which a plurality of outlet channels are arranged axially one behind the other. In this area, the feed channel narrows from outlet to outlet by the same amount in each case. In the DE 83 31 289 U1 describes a pipe branch, in particular for pneumatic conveying lines with a cross-split branch housing. An outflow-side housing part has a square or rectangular cross section.

In the article "Steam turbines for combined cycle power plants" by W. Engelke in fuel-thermal power, volume 41, 1989, pages 335 - 342, VDI-Verlag, Düsseldorf, various steam turbines with an overflow of steam from a Medium-pressure sub-turbine described in a low-pressure sub-turbine or in two low-pressure sub-turbines. In the event of an overflow of steam through an overflow line in two low-pressure partial turbines, the overflow line is narrowed downstream of the branch for the first low-pressure partial turbine. The overflow line thus consists of two pipe segments with different pipe diameters, which means that at least two axial compensators with different diameters are also required. The compensators shown bring about an axial expansion compensation, which is more necessary due to a different thermal expansion between the overflow line and the partial turbines.

The object of the invention is to provide a device for guiding and dividing a fluid flow, in which fluid partial flows can be guided in a flow channel separately from one another in terms of flow technology.

According to the invention, the object is achieved by a device for guiding and dividing a fluid flow with a flow channel, which is directed along a center line, in that a flow dividing element extending along the center line is provided, which divides the cross section of the flow channel in at least two from a fluidic point of view ¬ divides separate cross-sectional segments and which is rotated along the center line so that the position of the cross-section segments changes along the center line. This ensures that the flow velocity of the fluid, in particular steam from a steam turbine plant, is largely the same for each partial fluid flow. By dividing the flow channel into two or more cross-sectional segments that are separated from one another in terms of flow technology, fluid is derived from each of the cross-sectional segments without influencing the other partial fluid flow or the other partial fluid flows. As a result, a fluidic connection of a medium-pressure turbine section to two or more low-pressure turbine sections of a steam turbine system is achieved in particular.

The current dividing element is preferably rotated continuously at least in regions along the center line, so that the position of the cross-sectional segments along the center line also changes continuously, at least in regions, in particular helically. As a result, in particular in the case of cross-sectional segments of the same shape, a cross-sectional segment assumes the position of an adjacent cross-sectional segment at predetermined, in particular constant intervals, as a result of which the partial fluid flows are discharged in the same direction. Rotation of the flow dividing element preferably takes place immediately downstream of an outlet opening for branching off a partial fluid flow. This has the advantage that the flow channel can be constructed in a modular manner from respective segments with a respective outlet opening and a predetermined rotation of the flow dividing element.

Corresponding to the number of cross-sectional segments, outlet openings spaced apart from one another are preferably provided in the flow channel in order to discharge a respective partial fluid flow. The outlet openings are each arranged in the same partial area of the wall structure of the flow channel, so that each outlet opening has a different cross-sectional segment. is arranged. It is hereby achieved that by rotating the flow dividing element along the center line, each partial fluid flow can be discharged from the flow channel in the same way without influencing the other partial fluid flows. The outlet openings are preferably in the geodetically lowest region of the wall structure. Each partial fluid flow, in particular a steam flow from a steam turbine plant, is thus discharged vertically downward. The steam from a medium-pressure partial turbine can thus be conducted in two, three or more partial flows with essentially the same flow speed and flow direction in a respective low-pressure partial turbine. The low-pressure sub-turbines are thus subjected to essentially equivalent flow technology.

The flow channel preferably has a circular cross section. The current dividing element can subdivide a circular or other type of cross section into three largely identical 120 ° circle segments or similar segments. As a result, the volume flow of steam from a medium-pressure partial turbine can be divided into three equal partial flows to form three low-pressure partial turbines arranged next to one another, so that the flow velocity of each partial flow remains essentially constant and, at most, slight eddy and flow losses occur. The design of a branch area in the wall structure of the flow channel can be identical for each low-pressure turbine section, which significantly simplifies production.

The flow channel preferably has a constant cross section. It can be divided into at least two flow channel components with the same cross section, which are connected to one another via a compensator. The compensator compensates for differences in expansion between the flow channel and the

Partial turbines. These differences in elongation can be several Centimeters. A flow channel with a constant cross-section and with a flow dividing element has the advantage that the flow velocity remains largely constant in each of the remaining fluid partial flows even after each branching of a partial fluid flow. With a flow channel without a flow dividing element, on the other hand, the volume flow would decrease after each branch and thereby vortex and flow losses would occur, since acceleration would take place in particular when deflecting or feeding to the downstream branches. Compared to flow channels, in particular overflow lines in a steam turbine system, with a decreasing diameter, a flow channel with a constant diameter has the advantage that fewer compensators are required and the compensators still required have a uniform size. Downstream of each branch, the corresponding cross-sectional segment has pressure compensation devices, in particular bores, which enable pressure compensation. Downstream of the outlet opening of each cross-sectional segment, the volume area of the flow channel formed by the cross-sectional segment is preferably no longer flowed through.

The device with flow channel and flow dividing element is preferably suitable for dividing and guiding a steam flow in a steam turbine system, in particular in an overflow line, which connects a medium-pressure sub-turbine with two or more low-pressure sub-turbines. For this purpose, steam is supplied to the device from the medium-pressure turbine section via an inlet opening. This steam is divided in the flow channel by the flow dividing element into two or more preferably equally large volume flows, each partial volume flow being fed to a respective low-pressure sub-turbine via a respective outlet opening. The partial steam flows are preferably discharged directly vertically downwards. By rotating the current dividing element, the low partial pressure turbines are set up directly next to one another along an axis and steam is applied to the same quantity and the same flow rate. When using a flow channel with a constant cross-section, the constructive manufacture of the device is further simplified, since in particular the number of compensators required is reduced to a minimum and these can be used in a uniform size.

The device and its use in a steam turbine system are explained in more detail using the exemplary embodiments shown in the drawing. Show it:

1 shows a steam turbine system with a medium-pressure sub-turbine and three low-pressure sub-turbines in a longitudinal section, FIG. 2 shows a longitudinal section through a flow channel connecting the medium-pressure sub-turbine and the low-pressure sub-turbines, and FIGS. 3, 4, 5 show a cross section through the flow channel.

1 shows a steam turbine system 16 with a high-pressure sub-turbine 13, a medium-pressure sub-turbine 14 and three low-pressure sub-turbines 15a, 15b, 15c arranged along a shaft axis 19 in a longitudinal section. From the medium-pressure turbine section 14, steam 7 flows in the direction of the arrow via an inlet opening 11 into a device 1 for guiding and dividing a fluid flow, here a steam flow. The steam 7 emerging vertically upwards is deflected into the horizontal and reaches a flow channel 2 which extends along a center line 3. The flow channel 2 has three flow channel components 2a, 2b and 2c. The flow channel components 2a, 2b, 2c each have the same cross section 6 and are connected to one another by a respective compensator 12 of the same size. A tension rod 17 extends along the center line 3 and components 2a, 2b, 2c sealingly holds together. Each flow channel component 2a, 2b, 2c has in the geodetically deepest part 10 of the wall structure 9 of the flow channel

2 a respective outlet opening 8a, 8b, 8c. Each outlet opening 8a, 8b, 8c merges into a respective branch 20, for example a bend, for introducing a respective partial steam flow into a respective low-pressure partial turbine 15a, 15b, 15c. A flow dividing element 4 is provided in the flow channel 2, which extends along the center line 3 and divides the cross section 6 of the flow channel 2 into three identical cross-sectional segments 5a, 5b, 5c (see FIG

3 to 5) and is rotated such that a different cross-sectional segment 5a, 5b, 5c is present at each outlet opening 8a, 8b, 8c. As a result, a partial steam flow is discharged vertically downward in the geodetically lowest region 10 of the wall structure 9 of the flow channel 2. This enables a particularly, also constructive, simple supply of partial steam flows to low-pressure partial turbines 15a, 15b, 15c of a steam turbine system 16.

2 shows, on an enlarged scale, a section of the flow channel 2 according to FIG. 1. The meaning of the reference symbols corresponds to the respective meaning according to FIG. 1. The flow channel 2, as shown in FIGS. 3 to 5, has a circular cross section 6. This cross section 6 is divided by the current dividing element 4 into three cross-sectional segments 5a, 5b, 5c of the same cross-sectional area, each of which forms a circular segment with an opening angle of 120 °. The current dividing element 4 is formed by three metal sheets which collide on the center line 3 and are connected, in particular welded, there. The current dividing element 4 thus forms a star-shaped, heat-moving insert with three beams each forming an opening angle of 120 ° and formed by metal sheets. According to FIG. 2, there is a continuous rotation of the current dividing element 4 in a partial region 18 downstream of the first outlet opening 8a. 8 pointing direction instead. The position of the metal sheets separating the cross-sectional segments 5a, 5b, 5c is shown with the Greek letters α, β, γ in three different positions (FIG. 3, FIG. 4, FIG. 5) in the partial area 18. In the partial area 18, the current dividing element 4 is rotated through 120 °. Upstream of the partial region 18, the cross-sectional segment 5b is thus connected to the geodetically lowest region 10 of the wall structure 9. By contrast, downstream of the partial region 18, the cross-sectional segment 5a is connected to the geodetically lowest partial region 10. Analogously, a further rotation by 120 ° takes place downstream of the second outlet opening 8b, so that at the third outlet opening 8c the cross-sectional segment 5c is connected to the third steam component flow with the geodetically lowest region 10. Depending on the requirements of the steam throughput quantity and the steam volume to be flowed into a respective low-pressure turbine section 15a, 15b, 15c, the cross section 6 can be divided differently by the flow dividing element 4. An embodiment of the branch 20 for branching steam 7 out of a respective outlet opening 8a, 8b, 8c can take the form of a bend or a specially shaped transition piece with a constant cross section. The arrangement of the cross-sectional segments 5a, 5b, 5c at the ends of the flow channel component 2a, 2b, 2c is predetermined by rotating the flow dividing element 4 downstream of the branch 20 within a flow channel component 2a, 2b, 2c. This results in a particularly simple succession of flow channel components 2a, 2b, 2c with a correct transfer of the partial steam flows.

The invention is characterized by a device for guiding and dividing a fluid flow, in particular a steam flow from a medium-pressure sub-turbine into a plurality of low-pressure sub-turbines, in which one along the center line in a flow channel, an overflow line twisted flow dividing element is provided in the flow channel. With the current dividing element each Depending on the number of low-pressure partial turbines to be supplied with steam, the steam flow is split into a corresponding number of partial steam flows with a largely identical flow rate. As a result of the rotation of the flow dividing element, a respective partial steam flow can be fed, preferably in the geodetically lowest region of the wall structure, through a respective outlet opening vertically downward to a respective low-pressure partial turbine. This eliminates the need for complex pipe constructions with increased flow resistance. Steam is applied to low-pressure turbine sections arranged along a shaft axis in a particularly simple constructive manner. The use of a flow dividing element also allows the flow channel to be designed with a constant cross section over its entire length, so that flow channel components between individual low-pressure partial turbines can each be connected to a compensator of the same size. This leads to an additional simplification of the construction of the device.

Claims

claims

1. Device (1) for guiding and dividing a fluid flow with a flow channel (2), which is directed along a center line (3), so that one that extends along the center line (3) Flow dividing element (4) is provided, which divides the cross-section (6) of the flow channel (2) into at least two cross-sectional segments (5a, 5b, 5c) that are separated from one another in terms of flow technology and which is twisted along the center line (3) that the position of the cross-sectional segments (5a, 5b, 5c) changes along the center line (3).

2. Device (1) according to claim 1, in which the position of the cross-sectional segments (5a, 5b, 5c) along the center line (3) changes continuously at least in regions.

3. Device (1) according to claim 1 or 2, in which the flow channel (2) according to the number of cross-sectional segments (5a, 5b, 5c) spaced apart outlet openings (8a, 8b, 8c) for discharging a respective partial fluid flow having.

4. Device (1) according to claim 3, wherein the flow channel (2) in cross section (6) has a closed wall structure (9), and the outlet openings (8a, 8b, 8c) each in the same partial area (10) Wall structure (9) are arranged at such a distance from one another that each outlet opening (8) is assigned a different cross-sectional segment (5a, 5b, 5c).

5. Device (1) according to claim 4, in which the partial region (10) of the wall structure (9) is the geodetically lowest region of the flow channel (2).

6. Device (1) according to one of the preceding claims, in which the flow channel (2) has a circular cross section (6) and the flow dividing element (4) the cross section (6) in three largely identical 120 ° circle segments ( 5a, 5b, 5c) divided.

7. Device (1) according to one of the preceding claims, wherein the flow channel (2) has a constant cross section

(6) has.

10

8. Device (1) according to one of the preceding claims, wherein the flow channel (2) has at least two flow channel components (2a, 2b, 2c) with the same cross section (6), which are connected to one another via a compensator (12).

_ 15

9. Use of the device (1) according to one of the preceding claims, for dividing a steam flow in a steam turbine system (16).

20 10. Use according to claim 9, in which steam (7), in particular from a medium-pressure turbine section (14), flows into the device (1) via an inlet opening (11) and via a respective outlet opening (8) a respective low-pressure partial turbine (15a, 15b, 15c)

25 current is supplied.