EP4673631A1

EP4673631A1 - Turbine deflector

Info

Publication number: EP4673631A1
Application number: EP24720748.3A
Authority: EP
Inventors: Marek BOBCIK
Original assignee: Individual
Current assignee: Individual
Priority date: 2023-03-02
Filing date: 2024-03-01
Publication date: 2026-01-07
Also published as: WO2024179628A1; CZ310106B6; KR20250155612A; CZ202383A3; WO2024179628A4

Abstract

A turbine deflector comprising a collar (3) having an increasing cross-section of the central hole provided with an interface (6) in the plane (YZ) for attachment to a turbine inner body output (2). Shape of the collar (3) is described in the cross-section by at least one generic forming curve (k) forming the collar (3) inner surface. The deflector has a non-rotary shape defined so that the collar (3) profile in the cross-section in the plane (XZ) is axially asymmetrical along the plane (XY) and differs from the lateral cross-section in the plane (XY). Favourably, the generic forming curve (k) initial point (XO) lies in the intersection of the collar (3) and the interface (6), and the end point (X2) is the generic forming curve (k) end point. Then, the intermediate point (XI) between the initial point (XO) and end point (X2) has the perpendicular distance from the plane (YZ) highest of all points of the generic forming curve (k).

Description

Turbine deflector

Field of the invention

The present invention relates to the field of turbine structural components (in particular steam or gas turbines) having working fluid output from an outer casing in radial direction.

Background of the invention

The turbines (steam and gas, in particular) contain an inner body with a rotor (a flow portion) provided in the outer body. Among others, the outer body traps and guides the working fluid (steam, combustion products) being output from the inner body output after the last rotor vane phase. The outer body is provided with a radial working fluid drain. Usually, a steam turbine has a bottom drain provided with a condenser. Usually, a gas turbine has a top drain provided with a heat exchanger, if appropriate. A lateral outlet may be contemplated as well.

According to the prior art, the turbine inner body is provided with an annular deflector at output. The body is a rotary body (rotates around a machine axis) and all cross-sections thereof have the same shape. One of the tasks of the deflector is to guide and slow down flow, which results in change to working fluid pressure being output from the turbine inner body. Indeed, the working fluid outputs from horizontally oriented turbine inner body in axial direction and upon passing a diffuser, trajectory of streamlines of the working fluid changes to radial direction. This is caused by restriction of its movement in axial direction using a rear wall of the inner body, or the deflector provided thereon. For the inner body with the bottom or top drain, the change to the flow direction from axial to the radial direction is hindered by uneven distribution of the flow field in the YZ vertical plane. The most obvious difference results from comparison of the flow field over and under the turbine partitioning plane (i.e., above and below the plane XY). The reason is in particular shape of the output tract with the working fluid drain where the working fluid has a propensity to flow in the drain direction from the turbine inner body (e.g., to a superstructure of the condenser). Hence, a local pressure increase of the working fluid occurs on the inner body side being opposite to the working fluid drain. Finally, lower efficiency and lower working range of the turbine occurs.

According to the prior art, the problem may be eliminated by altering the shape of the turbine inner body. For the inner body with the bottom drain, one solution includes volume increase of the inner body portion above the partitioning level. Then, the inner body may be flatter in the upper portion and extended in the area of the partitioning level. However, this solution brings higher costs.

In particular in the steam turbines there is a diffuser portion in the output tract in order to reach as lowest static pressure as possible after the last vane to get more performance from the turbine. Pressure in the condenser directly depends on cooling water temperature and therefore, the turbine performance changes with respect to season. Attempts are made to use a suitable structure of the diffuser portion to reach pressure lower most favourably after the last vane phase than in the condenser. A prerequisite is an even flow field across the circumference after the last vane phase. The issues of uneven flow field is obvious also in a multi-body turbine where each body has radial flowing out as well. By making the flow field even also brings appreciable benefits for the machine performance.

CN211819541U discloses an annular deflector of a steam turbine. The deflector has a rotary shape and provided with a mounting assembly for attaching to the turbine. The mounting assembly includes two cooperating arc-shaped fixing plates that fix the deflector onto the turbine by tightening each other.

CN204175657 discloses an annular deflector for large-scale fans. The deflector has an enlarging funnel-shaped rotary shape with a flange with mounting bolt holes and allcircumference groove on the side of higher diameter.

CN115008136 discloses a welding forming device for manufacture of an annular deflector for a turbine. The device includes a plurality of arc-shaped plates and a plurality of arc-shaped rods that support said plates. The device may be used for production of a deflector having a rotary shape.

CN218151077 discloses a system for manual balancing of a steam turbine rotor by a mounting hole in a deflector. The deflector has a rotary shape and is provided with a closable hole through which a counterweight to each rotor vane may be either installed or demounted during the turbine shutdown.

Summary of the invention

The present invention relates to shape of a turbine deflector. The deflector includes a collar having its base with a circular central hole that forms an interface for attaching of the deflector to output from the turbine inner body according to the prior art. The interface defines the plane YZ perpendicular to longitudinal axis of the turbine and of the deflector. In use of the deflector, the plane YZ is a vertical plane perpendicular to longitudinal axis of the turbine (i.e., to the turbine rotor rotation axis). The interface may be connected to the turbine inner body so that the deflector becomes an integral part of the turbine inner body (e.g., by welding, bonding, etc.). However, it is favourable for the reasons of manufacture and operation when a releasable connection is used for connection of the deflector and the turbine inner body. In this way, the interface may be provided with a flange having a central hole. The flange is provided with an internal bearing surface in the plane YZ for connection to the turbine inner body output, and with an outer surface by which it is connected to the collar. The flange may be then used to connect the deflector to the turbine internal body in a separable (e.g., screw) joint.

The collar is a non-rotary shaped body comprising a flat profile, being either symmetrical or asymmetrical along the vertical XZ plane crossing turbine and deflector longitudinal axis, perpendicular to the plane YZ.

A free edge of the flat profile being remote from the interface is shaped in the radial direction (i.e., in the direction from the turbine and deflector longitudinal axis) into a variable collar cross-section.

In a plurality of radial planes crossing turbine and deflector longitudinal axis, the variable collar cross-section comprises a plurality of forming curves of shapes being changed depending on a specific point on the collar circumference. All separate, mutually different collar profiles in the plurality of said radial planes follow each other seamlessly in the circumferential direction of the plane YZ. This means that the collar shape transitions are as smooth as possible without abrupt changes.

It is applied at least in the plane XZ that at least first collar end has a deflector shape defined so that the forming curve, which forms the inner collar surface, has:

- an initial point XO lying in the interface;

- an end point X2 having the highest distance from the turbine and deflector longitudinal axis of all points on said forming curve;

- and an intermediate point XI of which distance from the turbine and deflector longitudinal axis is higher than distance of the initial point XO and lower than distance of the end point X2. At the same time, the intermediate point XI is the only point of relevant forming curve in which a tangent of the forming curve is parallel to the plane YZ. Perpendicular distance of the intermediate point XI from the plane YZ is highest of all points of said forming curve. This is the distance in the direction from the turbine inner body; the plane crossing the end point X2, which is parallel to the plane YZ, is located between the plane YZ and the intermediate point XI. Hence, the intermediate point XI is the most distant point from the turbine inner body downstream the working fluid after output from the turbine inner body.

In another favourable embodiment, said definitions about mutual position of the points XO, XI, and X2 apply to any of said plurality of the forming curves that jointly form the inner collar surface.

The variable collar cross-section increases in axial direction (i.e., in the direction from the interface to the intermediate points XI of the forming curves) so that the collar has a funnellike shape extending from the interface. The collar inner surface defines an extending volume through which the working fluid (steam, combustion products, and more) moves through diffuser central hole from the turbine inner body output.

The deflector cross-section in the plane XZ is axially asymmetrical according to the plane XY crossing the turbine and deflector longitudinal axis being perpendicular to the XZ and YZ planes. At the same time, the cross-section in the plane XZ differs from the one in the plane XY. An intersection point of the plane XY with the plane XZ in the plane YZ is the geometrical centre of the diffuser central hole in the plane YZ.

The end points X2 of two forming curves in the plane XZ are located on the end points X2 line being concurrent to the plane YZ. Thus, the plane YZ contains the intersection point with the end points X2 line. Indeed, the end points X2 line forms acute angle a with the plane YZ. In the plane XZ, the perpendicular distance between the forming curve end point X2 and the plane YZ is lower on the first collar edge than the perpendicular distance between the forming curve end point X2 of the opposite second collar edge and the plane YZ.

The intermediate points XI of two forming curves in the plane XZ are located on the intermediate points XI line being concurrent to the plane YZ as well. Thus, the plane YZ contains the intersection point with the intermediate points XI line. The intermediate points XI line also forms acute angle a’ with the plane YZ.

When absolute value of perpendicular distance of the end point X2 from the plane YZ is higher than absolute value of perpendicular distance of the intermediate point XI, then the line being crossed by two intermediate points X2 and crossing the intersection point of the plane XY with the plane XZ is a secant line of the turbine inner body when the deflector is mounted thereon. This occurs when the outer collar edge is extremely long and bent so that it interferes deeply behind the interface upstream the working fluid.

Favourably, the perpendicular distance of the end point X2 of the first collar edge in the plane XZ from the plane XY (or from the central axis O) is lower than the perpendicular distance of the end point X2 of the second collar edge.

At least on the second collar edge, a portion of the generic forming curve with zero curvature and a finite length may be in the plane XZ and perpendicular to the plane YZ. This is the portion of the generic forming curve facing from the initial point XO to the intermediate point XI. Therefore, a portion of the collar inner surface is a portion of a cylindrical surface at that location. Considering the line crossing the end points X2 of both collar edges, which is not parallel in the plane XZ with the interface, the cylindrical surface obviously narrows down towards the first collar edge. This embodiment may be favourable in an application where the axial space for flowing out the working fluid between turbine inner and outer body is higher.

In use of the deflector in the turbine, the first collar edge in the plane XZ is that one being remote from the drain of the working fluid from the outer body. On the contrary, the second collar edge is directed to the working fluid drain from the outer body. Hence, when the diffuser is used in the turbine provided with the bottom working fluid drain, the first collar edge is the upper one in the plane XZ. Analogically, when the diffuser is used in the turbine provided with the top working fluid drain, the first collar edge is the lower one in the plane XZ. When the turbine is provided with a lateral working fluid drain, both first and second collar edges are located out of the vertical section.

The present invention aims for changing a trajectory of individual streamlines of a flow field using a suitable deflector shape upon output from the turbine inner body, and to reduce unevenness of the flow field. The flow field modelling achieves loss reduction due to reduced speed of the flow field after the diffuser. The liquid flow then flows more efficiently between the turbine inner and outer body because the effective cross-section between the bodies increases. The other positive results include increased turbine performance, vibration, and noise reduction. Reduced unevenness of the flow field in circumferential direction in the working space of the vanes increases their life, and the turbine will have higher working range. The effective cross-section between the bodies through which the fluid flows is increased due to the moderation of the flow field. In particular, the outer body can be reduced at the turbine design stage to achieve cost savings. The deflector is usable for steam turbines, gas turbines, etc. Where the collar is modified, negative manifestations of liquid back flow mixing with the main flow are prevented. Forming of eddies, which produce loss, is eliminated thereby. A suitable collar shape creates a space that expands on the circumference towards the working fluid drain from the side opposite the working fluid drain from the outer body. Thereby, the space for the working fluid drain, which is not disturbed by the working fluid flowing from the turbine output, is created. Said diffuser shape makes the flow field uniform and models the flow field without any negative manifestations. When considering the solution in a general way, it should be appreciated that the working fluid is divided into a plurality of mutually non-influencing flows. At the same time, unlike conventional solutions, the volume between the turbine inner and outer body is utilized much better, and there are no vortices that cause losses.

Explanation of drawings

The exemplary embodiment of the proposed technique is described with reference to the drawings where

Fig: 1 - is external view in the plane XZ to a deflector embodiment having a rotary shape according to the prior art;

Fig. 2 - is external view in the plane XZ to another deflector embodiment having a rotary shape according to the prior art;

Fig. 3 - is external view in the plane XZ to a deflector according to the present invention;

Fig. 4 - is external view in the plane XZ to a deflector according to the present invention having a portion of a forming curve with zero curvature and a finite length perpendicular to the plane YZ;

Fig. 5 - is front axial view in the plane YZ to a deflector according to the present invention;

Fig. 6 - is cross-section view in the plane XZ to the deflector according to the present invention;

Fig. 7 - is close up sectional view according to Fig. 6 showing the first collar edge;

Fig. 8 - is sectional view in the plane XZ to the deflector according to the present invention showing lines P and P’ and distances between end points of the forming curves and the plane YZ. Exemplary embodiment of the invention

A turbine deflector described in this example is intended for a steam turbine having a bottom working fluid drain from an outer body to a condenser. The deflector includes an interface 6 in the form of a flange 1_ with a central hole. On one side, the flange j_ is provided with an inner bearing surface 4 in the plane YZ for attachment to an output 2 from a turbine inner body. Further, the flange 1_ is provided with an outer surface 5 to which a collar 3 with increasing cross-section of the central hole is attached.

Shape of the collar 3 is defined in lateral cross-section by a plurality of generic forming curves k forming the collar 3 inner surface. The deflector has a non-rotary shape defined so that the collar 3 profile in the cross-section in the plane XZ is axially asymmetrical along the plane XY and differs from the lateral cross-section in the plane XY. Here, the cross-section in the plane XZ is vertical one, whereas the cross-section in the plane XY is horizontal one. All separate, mutually different cross-sections of the collar 3 profiles follow each other seamlessly in the circumferential direction of the plane YZ.

An intersection point of the plane XY with the plane XZ in the plane YZ is a geometrical centre of a circular central hole of the flange 1 in the turbine and deflector longitudinal axis O. The following applies in any cross-section crossing the turbine and deflector longitudinal axis O: the generic forming curve k initial point XO lies in the intersection of the collar 3 and the interface 6; an end point X2, being the generic forming curve k end point, has the highest distance from the longitudinal turbine and deflector axis Q of all points on said generic forming curve k; an intermediate point XI between the initial point XO and the end point X2 having perpendicular distance from the plane YZ highest of all points of the generic forming curve k has the distance from the turbine and deflector longitudinal axis Q higher than the distance of the initial point XO and lower than the distance of the end point X2.

The distance of the generic forming curve k initial point X2 of a first (here, upper) collar 3 edge 31 from the plane XY is lower than the generic forming curve k end point X2 of second (here, bottom) collar 3 edge 32. The line P crossing the generic forming curve k end point X2 of the first collar 3 edge 31 and the generic forming curve k end point X2 of the second collar 3 edge 32 in the plane XZ is not parallel to the inner flange 1 bearing surface 4 in the plane YZ.

The line P’ crossing the generic forming curve k intermediate point XI of the first collar 3 edge 31 and the generic forming curve k intermediate point XI of the second collar 3 edge 32 in the plane XZ is not parallel to the inner flange 1_ bearing surface 4 in the plane YZ.

In the plane XZ, the perpendicular distance Cl between the generic forming curve k end point X2 of the first collar 3 edge 31 and the plane YZ is lower than the perpendicular distance C2 between the generic forming curve k end point X2 of the second collar 3 edge 32 and the plane YZ.

List of reference numerals

1 - flange

2 - turbine inner body output

3 - collar

4 - flange bearing surface

5 - flange outer surface

6 - interface

31 - first collar edge

32 - second collar edge k - generic forming curve

O - turbine and deflector longitudinal axis

P - end points line

P' - intermediate points line

XO - generic forming curve initial point

XI - generic forming curve intermediate point

X2 - generic forming curve end point a - angle between end points line P and plane YZ a' - angle between intermediate points line P' and plane YZ

XY, XZ, YZ - planes based on Cartesian coordinates x, y, z

Claims

1. A turbine deflector comprising a collar (3) having an increasing cross-section of the central hole provided with an interface (6) in the plane (YZ) for attachment to a turbine inner body output (2), wherein shape of the collar (3) is described in the cross-section by at least one generic forming curve (k) forming the collar (3) inner surface, characterized in that the deflector has a non-rotary shape defined so that the collar (3) profile in the crosssection in the plane (XZ) is axially asymmetrical along the plane (XY) and differs from the lateral cross-section in the plane (XY).

2. The deflector according to claim 1 characterized in that in the first cross-section in the plane (XZ), the shape of at least first collar (3) edge (31) is defined so that a generic forming curve (k) initial point (XO) lies in an intersection of the collar (3) and the interface (6), an end point (X2) is the generic forming curve (k) end point, an intermediate point (XI) between the initial point (XO) and end point (X2) has a perpendicular distance from the plane (YZ) highest of all points of the generic forming curve (k), and an end points line (P) crossing the end point (X2) of the first collar (3) edge (31) and the end point (X2) of the second collar (3) edge (32) is not parallel to the interface (6), wherein the perpendicular distance (Cl) between the end point (X2) of the first collar (3) edge (31) and the plane (YZ) is lower than the perpendicular distance (C2) between the end point (X2) of the second collar (3) edge (32) and the plane (YZ).

3. The deflector according to claim 1 or 2 characterized in that in the first cross-section in the plane (XZ) the perpendicular distance of the end point (X2) of the first collar (3) edge (31) from the plane (XY) is lower than the perpendicular distance of the end point (X2) of the second collar (3) edge (32).

4. The deflector according to claim 2 or 3 characterized in that in any cross-section crossing the turbine and deflector longitudinal axis (O), the generic forming curve (k) initial point (XO) lies in the intersection of the collar (3) and the interface (6), the end point (X2) is the generic forming curve (k) end point, and the intermediate point (XI) between the initial point (XO) and end point (X2) has the perpendicular distance from the plane (YZ) highest of all points of the generic forming curve (k).

5. The deflector according to any of the claims 1 to 4 characterized in that at least on the second collar (3) edge (32), a portion of the generic forming curve (k) from the initial point (XO) towards the intermediate point (XI) in the first cross-section in the plane (XZ) has zero curvature with finite length and is perpendicular to the plane (YZ).

6. The deflector according to any of the claims 1 to 5 characterized in that the interface (6) is provided with a flange (1) with central hole, wherein the flange (1) is provided with an inner gearing surface (4) in the plane (YZ) for attachment to the turbine inner body output (2), and with an outer surface (5) by which it is attached to the collar (3).