CN111550292A - Optimization method of vortex cooling for medium pressure cylinder and its cooling structure - Google Patents

Abstract

A medium-pressure cylinder vortex cooling optimization method and cooling structure thereof, wherein a rectifier corresponding to the jet orifice is arranged at the upstream of each jet pipe outlet arranged on the chamber wall surface of the medium-pressure cylinder along the jet direction, and the jet outlet is controlled by the rectifier. Correct the direction, disturb the upstream cross flow, reduce the cross flow velocity and the upstream diffusion of the steam flow, make the circumferential speed of the steam flow closer to the tangential velocity of the medium pressure rotor surface, enhance the penetration ability of the jet, and effectively improve the rotor surface. cooling effect. The invention can correct the direction of the jet outlet, reduce the diffusion of the steam flow upstream, and make the circumferential speed of the steam flow closer to the tangential velocity of the surface of the medium pressure rotor, thereby effectively reducing the surface temperature of the medium pressure rotor and improving the cooling effect; The airfoil rectifier can disturb the upstream cross flow, reduce the flow velocity of the cross flow, enhance the penetration ability of the jet, and also play a role in improving the cooling effect; in addition, the invention has simple structure, convenient processing, low cost and good engineering application value. .

Description

Optimization method of vortex cooling for medium pressure cylinder and its cooling structure

technical field

The invention relates to a technology in the field of steam turbines, in particular to an optimization method for vortex cooling of a medium-pressure cylinder and a cooling structure thereof.

Background technique

As a key component of thermal power generation, the medium pressure rotor has a large diameter and is in direct contact with high-temperature reheated steam. effective cooling measures. The medium-pressure cylinder vortex cooling technology is a technology that directly uses high-temperature reheated steam without introducing external cooling gas, and enters the medium-pressure cavity through the tangential jet tube at a certain speed to form a vortex to cool the surface of the medium-pressure rotor. The temperature felt on the surface of the rotor is the total temperature of the vapor near the wall relative to the surface of the rotor. Referring to the pre-rotation theory in the turbine disk cavity, when the jet velocity is constant, the difference between the circumferential speed of the jet and the tangential velocity of the rotor surface is smaller. The lower the rotor wall temperature, the better the cooling effect. However, in the process of applying the medium-pressure vortex cooling technology, it was found that there are further improvements, such as the high jet velocity and the serious upstream diffusion of the steam flow, so the cooling effect of the rotor surface is slightly worse; secondly, the cross-flow velocity inside the medium-pressure cavity It is also higher, which reduces the penetration ability of the jet and also deteriorates the cooling effect.

For the medium pressure cylinder vortex cooling technology, in order to give full play to its cooling effect, the key is to reduce the upstream diffusion of the steam flow, so that the tangential speed of the steam flow is as close as possible to the tangential speed of the medium pressure rotor surface. Reasonable correction of the steam flow direction at the outlet of the jet tube can effectively cool the surface of the medium pressure rotor effectively, thereby increasing the service life of the medium pressure rotor, enhancing the safety of the entire unit operation, and improving the unit efficiency.

SUMMARY OF THE INVENTION

Aiming at the defect that the steam flow from the outlet of the jet tube diffuses upstream in the existing medium-pressure cylinder vortex cooling technology, the present invention proposes a medium-pressure cylinder vortex cooling optimization method and a cooling structure, which can correct the direction of the jet outlet and reduce the upstream flow of the steam flow. Diffusion makes the circumferential speed of the steam flow closer to the tangential velocity of the surface of the medium pressure rotor, thereby effectively reducing the surface temperature of the medium pressure rotor and improving the cooling effect; at the same time, the triangular airfoil rectifier can disturb the upstream cross flow, reduce the cross flow velocity, and enhance the jet flow The penetrating ability can also improve the cooling effect; in addition, the invention has the advantages of simple structure, convenient processing, low cost and good engineering application value.

The present invention is achieved through the following technical solutions:

The invention relates to an optimization method for vortex cooling of a medium-pressure cylinder. A rectifier corresponding to the jet orifice is arranged at the upstream of the outlet of each jet pipe arranged on the chamber wall surface of the medium-pressure cylinder along the jet flow direction, and the rectifier is used to control the direction of the jet flow outlet. Correction is performed to disturb the upstream cross flow, reduce the cross flow velocity and the upstream diffusion of the steam flow, make the circumferential speed of the steam flow closer to the tangential velocity of the medium pressure rotor surface, and enhance the penetration ability of the jet, thereby effectively improving the cooling of the rotor surface. Effect.

The rectifier is a triangular airfoil-shaped pentahedron symmetrical structure, the middle section is an arc-like obtuse-angled triangle, and the front end, that is, along the jet flow direction (rotor rotation direction), is provided with a convex portion.

The symmetric structure means that the rectifier is a symmetric structure along the span direction, and the center plane of symmetry coincides with the axis of the jet tube.

The obtuse-like triangle refers to: the obtuse angle β=140°～170° between the side of the rectifier along the jet flow direction on the mid-section and the arc-shaped side on the chamber wall; the side along the jet-flow direction on the mid-section Length h=0.1H～0.4H, in which: H is the height of the chamber; the distance l=1.0D～2.0D from the starting point to the end point along the inner wall of the chamber on the mid-section, and the fillet radius r1 at the bulge on the mid-section =0.1D～0.4D, the fillet radius r2=2D～4D at the connection between the side opposite the obtuse angle and the inner wall of the chamber on the middle section, the spanwise width is b=1.5D～2.5D, where: D is the inner diameter of the jet tube .

The upstream part along the jet flow direction specifically refers to the smooth transition between the upper edge of the convex curved surface of the convex part of the rectifier and the orifice of the jet pipe on the chamber wall surface, and the connection between the end curved surface of the rectifier and the end of the chamber wall surface. There is a smooth transition between.

The number of the jet tubes is more than one, and they are evenly distributed along the circumferential direction.

The included angle between the axis of the jet tube and the tangential direction of the chamber wall surface is 10°˜30°.

technical effect

The invention as a whole solves the problem that in the medium pressure eddy current cooling technology, the tangential jet flow is more serious in the upstream diffusion, the cooling effect cannot be fully exerted, and the cross flow velocity inside the medium pressure cavity is relatively high, which reduces the penetration ability of the jet and deteriorates the cooling ability. technical issues.

Compared with the prior art, the present invention corrects the jet flow direction and disturbs the upstream cross flow through the triangular airfoil rectifier, reduces the diffusion effect of the steam flow upstream, and makes the circumferential speed of the steam flow closer to the surface of the medium pressure rotor. The tangential velocity can significantly enhance the cooling effect while reducing the cross-flow velocity, enhancing the penetration ability of the jet, and significantly improving the cooling effect.

Description of drawings

Fig. 1 is the overall schematic diagram of the present invention in the medium pressure cylinder vortex cooling;

Fig. 2 is a schematic diagram of a middle section of a triangular airfoil rectifier;

Fig. 3 is a three-dimensional schematic diagram of a triangular airfoil rectifier;

Fig. 4 is a meridional cross-sectional schematic diagram of a triangular airfoil rectifier;

Fig. 5 is the overall three-dimensional schematic diagram of the optimized structure of medium-pressure eddy current cooling;

Fig. 6 is the schematic diagram of the flow direction of steam flow in the present invention;

In the picture: 1 jet tube, 2 triangular airfoil rectifier, 3 medium pressure rotor, 4 chamber wall.

Detailed ways

As shown in FIGS. 1 to 6 , the present embodiment relates to a cooling structure for improving the vortex cooling effect of a medium-pressure cylinder, specifically: a cooling structure located at the upstream of the outlet of each jet tube along the jet flow direction and corresponding to the jet orifice A rectifier, the triangular airfoil is a triangular airfoil symmetrical structure, and the front curved surface and the end curved surface are respectively smoothly transitioned with the jet tube orifice of the chamber wall and the end of the chamber wall, and the convex side is along the jet flow direction.

In this embodiment, the number of jet tubes arranged on the wall of the chamber is more than one, and they are evenly distributed along the circumferential direction. If it is a round tube, it can also take other shapes. When taking other shapes, D is the spanwise length of the jet orifice. For the cooling structure in this embodiment, the jet tube hole is preferably circular.

As shown in Figure 4, the vortex cooling optimization method for the medium-pressure cylinder specifically refers to: when the steam is injected into the cavity from the orifice through the jet tube, the triangular airfoil rectifier at the upstream of the orifice has a restricting effect on the flow direction. , reducing the upstream diffusion of the steam flow, making the circumferential speed of the steam flow closer to the tangential speed of the rotor surface, and then the total temperature of the steam flow relative to the rotor surface is smaller, effectively improving the cooling effect of the medium-pressure rotor, extending the medium-pressure rotor. The service life of the compressor rotor is improved and the safety of the entire steam turbine unit is improved. In addition, the triangular airfoil rectifier has a certain disturbance effect on the upstream cross flow, which can reduce the flow velocity of the cross flow, enhance the penetration ability of the jet, and also improve the cooling effect. A specific embodiment will be given below to further illustrate this embodiment.

Specifically, in this embodiment, the number of jet tubes is 4, which are periodically arranged at equal intervals along the circumferential direction, the jet tube holes are circular holes, and the diameter D is 30 mm. The included angle α is 20°, and the cavity height H is 40mm. Correspondingly, the side length h=0.3H=12mm of the triangular airfoil rectifier along the jet flow direction on the middle section of the rectifier in this embodiment, and the obtuse angle β=160 between the side along the jet flow direction and the arc edge on the chamber wall °, the distance from the start point to the end point along the inner wall of the chamber l=1.5D=45mm, the radius of the fillet at the convex part is r1=0.2D=6mm, the radius of the fillet at the connection between the side opposite the obtuse angle and the inner wall of the chamber is r2=2.5D =75mm. The spanwise width of the triangular airfoil rectifier is b=2D=60mm, the radius of the corners on both sides of the triangular airfoil rectifier on the meridian section is r3=0.1D=2.5mm, the surface of the whole triangular airfoil rectifier is smooth and has no edges and corners, and it is in line with the jet orifice. and end wall transitions are smooth.

When the steam flows into the interior of the chamber through the jet tube 1 on the chamber wall 4, the triangular airfoil rectifier 2 corrects the flow direction of the jet at the orifice, which reduces the diffusion of the steam to the upstream and makes the circumferential speed of the steam faster. Close to the tangential speed of the rotor surface, thereby effectively reducing the surface temperature of the medium pressure rotor, and the cooling effect of the rotor has been significantly improved. In addition, the delta airfoil rectifier has a disturbing effect on the cross flow, reduces the flow velocity of the cross flow, enhances the penetration ability of the jet, and also improves the cooling effect of the rotor, which can effectively improve the safety of the unit operation and improve the medium pressure rotor. service life.

The above-mentioned specific implementation can be partially adjusted by those skilled in the art in different ways without departing from the principle and purpose of the present invention. The protection scope of the present invention is subject to the claims and is not limited by the above-mentioned specific implementation. Each implementation within the scope is bound by the present invention.

Claims (7)

1. A method for optimizing eddy current cooling of a medium pressure cylinder is characterized in that a rectifier corresponding to an orifice of a jet flow is arranged at the upstream of the outlet of each jet flow pipe arranged on the wall surface of a cavity of the medium pressure cylinder along the jet flow direction, the outlet direction of the jet flow is corrected through the rectifier, the upstream cross flow is disturbed, the flow velocity of the cross flow and the upstream diffusion of the steam flow are reduced, the circumferential speed of the steam flow is closer to the tangential velocity of the surface of a medium pressure rotor, the penetrating power of the jet flow is enhanced, and therefore the cooling effect of the surface of the rotor is effectively improved;

the rectifier is a pentahedron symmetrical structure of a triangular wing type, the middle section of the rectifier is an arc obtuse triangle, the front end of the rectifier is provided with a protruding portion along the jet flow direction, and the front end of the rectifier is provided with a triangular wing type.

2. The method for optimizing vortex cooling of a medium pressure cylinder according to claim 1, wherein said symmetrical structure is: the rectifier is of a symmetrical structure along the span direction, and the symmetrical center plane is superposed with the axis of the jet pipe.

3. The method for optimizing vortex cooling of a medium pressure cylinder according to claim 1, wherein said obtuse triangle is: the included angle beta between the edge of the rectifier on the middle section along the jet flow direction and the arc edge on the wall surface of the chamber is 140-170 degrees; the length of a side H along the jet direction on the middle section is 0.1H to 0.4H, wherein: h is the chamber height; the distance l from the starting point to the end point along the inner wall surface of the chamber on the middle section is 1.0D-2.0D, the fillet radius r1 at the convex part on the middle section is 0.1D-0.4D, the fillet radius r2 at the connecting part of the obtuse angle opposite side and the inner wall surface of the chamber on the middle section is 2D-4D, and the span width b is 1.5D-2.5D, wherein: d is the diameter of the jet pipe.

4. The method for optimizing vortex cooling of a medium pressure cylinder according to claim 1, wherein the upstream in the jet flow direction specifically means: the smooth transition is formed between the upper edge of the convex curved surface of the convex part of the rectifier and the orifice of the jet pipe on the wall surface of the chamber, and the smooth transition is formed between the curved surface at the tail end of the rectifier and the end part of the wall surface of the chamber.

5. The method for optimizing vortex cooling of a medium pressure cylinder according to claim 1, wherein the number of the jet pipes is more than 1 and is uniformly distributed along the circumferential direction.

6. The vortex cooling optimization method for the intermediate pressure cylinder as claimed in claim 1, wherein an included angle between the axis of the jet pipe and the tangential direction of the wall surface of the chamber is 10 ° to 30 °.

7. A rectifier for implementing the optimization method of any one of claims 1 to 6.

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