RU2719751C2 - Honeycomb seal of turbomachine - Google Patents

Abstract

FIELD: turbines or turbomachines.

SUBSTANCE: invention relates to a honeycomb sealing of a turbomachine, which comprises a holder installed in the stator casing, segments with honeycomb blocks and sealing flanges of the rotor. Segments are fixed in the cage and equipped with sealing flanges. Honeycomb blocks are fixed in segments between sealing flanges by soldering. Sealing ledges of rotor form throttling gaps with inner cylindrical surface of honeycomb blocks. Segment sealing flanges form throttling gaps with outer cylindrical rotor surface. Segment sealing ridges and honeycomb blocks are separated by annular channels for deposition of foreign particles.

EFFECT: technical result of using invention consists in increase of turbomachine operating period with permissible values of efficiency and reduction of costs for operation and repair of honeycomb seals.

9 cl, 2 dwg

Description

The invention relates to honeycomb seals of turbomachines and can be used to increase their reliability.

A honeycomb seal of the radial clearance of a turbomachine is known (see patent for utility model RU 31814, IPC F01D 11/02, published August 27, 2013) containing a clip mounted in the stator housing, segments with honeycomb blocks and rotor sealing ridges. Segments are fixed in a clip. Cell blocks are fixed in segments by soldering. The rotor sealing ridges form a throttling gap with the inner cylindrical surface of the honeycomb block. The sealing ridges on the rotor shaft are made thickened with a sharp leading edge and an annular groove at the top having a depth of up to 25% of the height of the comb, the top of the sealing comb has a slope of 10-15 ° against the direction of flow of the main flow of the working medium.

Part of the working medium, falling on the conical surface of the annular groove, changes its direction and is thrown into the throttling gap against the flow of the main stream. The penetration of the working medium into the space of the cell block increases and leads to the formation of additional vortices. The aerodynamic resistance of the throttling gap increases, and the flow rate of the working medium through the seal decreases, providing an increase in the efficiency (efficiency) of the turbine.

A disadvantage of the known honeycomb seal is that the throttling gap of the honeycomb seal is not protected against ingress of foreign particles moving in the flow of the working medium. As a rule, it is not possible to eliminate pollution of the working environment under operating conditions. Foreign particles contained in the working medium, falling between the rotor combs and the honeycomb blocks, subject them to intense destruction. Efficiency and operating efficiency of a turbomachine are reduced. When working with a "dirty" working environment, the well-known honeycomb seal limits the reliability of the turbomachine.

As a prototype, a honeycomb seal of a steam turbine was adopted (see patent for invention RU 2150627, IPC F16J 15/447, published: 10.06.2000), containing a clip installed in the stator housing, segments with honeycomb blocks and rotor sealing ridges. Segments are fixed in a holder and equipped with sealing ridges. Cell blocks are fixed in segments between the sealing ridges by soldering. The rotor sealing ridges form throttling gaps with the inner cylindrical surface of the honeycomb blocks. Sealing ridges of the segments form throttling gaps with the outer cylindrical surface of the rotor.

The known design implements a stepped flow of a throttled working medium with a multiple change in the direction of flow and additional aerodynamic drag on the cellular blocks due to the flow through gaps with different passage sections.

When operating a turbomachine with a “clean” working medium, the sharp edges of the rotor ridges cut through the honeycomb blocks to the radial depth and the length of the axial displacement of the rotor. For permissible rotor movements, the production of cell blocks is also kept within acceptable limits. Permissible output cell blocks provide reliable compaction with a slight decrease in the efficiency of the turbomachine.

The reliability of the honeycomb seal and the efficiency of the turbomachine are reduced when foreign particles enter the working environment. During operation of a turbomachine with a "dirty" working medium, foreign particles fall into the throttling gap between the crests of the segments and the outer cylindrical surface of the rotor, lose some kinetic energy and are crushed to particles commensurate with the size of the gap. In the throttling gap between the rotor flanges and the honeycomb blocks, large foreign particles crush the cells and get stuck in them. The friction of the rotor flanges against solid foreign particles is accompanied by their progressive wear and further crushing of the cellular blocks. With significant contamination of the working environment, the rotor combs and cell blocks are destroyed along the entire circumference. The first rotor comb and the closest cell blocks closest to it turn out to be the most damaged. On subsequent ridges and honeycomb blocks, the level of damage decreases as the number and size of foreign particles that lose their kinetic energy and settle in stagnant zones of the stator decrease (see Sakhnin Yu.A., Ushinin SV, Golovanov OA Experience operation of turbines of type T-100-130. Power plants. - 2014. No. 12. C.9 7-11).

The problem solved by the invention is the protection of the throttling gaps of the honeycomb seal of the turbomachine from foreign particles by crushing them and diverting from the throttling gap.

The technical result from the use of the invention is to increase the period of operation of the turbomachine with acceptable values of efficiency and reduce the cost of operation and repair of honeycomb seals.

The invention can be implemented in several versions.

1st performance.

The honeycomb seal of the turbomachine contains a clip installed in the stator housing, segments with honeycomb blocks and rotor sealing ridges. Segments are fixed in a holder and equipped with sealing ridges. Cell blocks are fixed in segments between the sealing ridges by soldering. The rotor sealing ridges form throttling gaps with the inner cylindrical surface of the honeycomb blocks. Sealing ridges of the segments form throttling gaps with the outer cylindrical surface of the rotor.

To solve this problem, the sealing ridges of the cage and the cell blocks are separated by annular channels for the deposition of foreign particles. Once in the annular channel, foreign particles lose kinetic energy and settle in the annular channels of the lower segments, where they accumulate before periodic maintenance or repair. Accumulating foreign particles, the annular channels protect the cellular blocks and ridges from destruction.

Further improvement of the honeycomb seal of the turbomachine is achieved in the following versions, which are used for the consistent refinement of previously manufactured products.

2nd performance.

The honeycomb seal of the turbomachine in the 1st design, characterized in that in the bottom of the annular channels, internal slurry * cavities are made in the form of blind holes for capturing and concentrating foreign particles (* sludge is a mixture of foreign particles of various origin).

Internal sludge cavities accumulate foreign particles until they are periodically cleaned or repaired.

3rd performance.

A honeycomb seal of a turbomachine in the 1st or 2nd design, characterized in that external slurry cavities are made on the outer cylindrical surface of the segment, which are connected by an opening to the annular channels.

The sediment of foreign particles under the action of vibration and mass forces moves from the annular channels and internal slurry cavities through the connecting holes into the external slurry cavities, where they accumulate before periodic cleaning or repair.

4th performance.

A honeycomb seal of the turbomachine in the 3rd design, characterized in that the hole connecting the sludge cavity with the annular channels is made with a diameter larger than the minimum throttling clearance between the casing flange and the rotor surface and less than twice this gap.

Limiting the diameter of the connecting hole prevents an increase in the flow rate of the working medium in the honeycomb seal and a decrease in the efficiency of the turbomachine.

5th performance.

The honeycomb seal of the turbomachine in one of the versions 2-4, characterized in that a step is made in the annular channel at the inlet of the connecting hole for better capture of foreign particles.

The step is used to quench the kinetic energy of foreign particles and direct them into the connecting hole and the external sludge cavity.

6th performance.

A honeycomb seal of a turbomachine in one of the versions 1-5, characterized in that at least one sealing ridge of the segment is made with a variable height and forms a wedge-shaped gap with the outer surface of the rotor.

The wedge-shaped gap is designed to capture and grind large foreign particles between the crest of the cage and the outer surface of the rotor. Grinding large foreign particles prevents them from reaching the surface of the cell blocks.

7th performance.

A honeycomb seal of a turbomachine in one of versions 1-6, characterized in that the rotor is equipped with at least one sludge-reflecting ridge reflecting foreign particles from the throttling gaps between the sealing ridges of the rotor and the inner cylindrical surface of the honeycomb blocks.

The sludge-reflecting comb protects the honeycomb blocks and sealing ridges from wear and destruction by foreign particles.

8th performance.

The 7th design of the honeycomb seal of the turbomachine, characterized in that the sludge-reflecting comb is made with a concave surface that directs foreign particles into the annular channels.

The concave surface of the sludge-reflecting ridge gives foreign particles counter-transverse motion relative to the flow of the working medium, reduces their kinetic energy and accelerates the process of removal from the seal.

9th performance.

The honeycomb seal of the turbomachine in one of the versions 2-8, characterized in that the external slurry cavities are connected by a pipeline to the cleaning system.

The cleaning system ensures the removal of sludge, for example, by flushing, purging and injection, without taking the turbomachine out of operation.

The most preferred design of the honeycomb seal of the turbomachine contains features of all designs and is intended for new models of turbomachines.

In FIG. 1 is a perspective view of a preferred design of a honeycomb seal of a turbomachine. In FIG. 2 shows a section AA in FIG. 1.

The honeycomb seal of the turbomachine contains a holder 1, segments 2 with honeycomb blocks 3 and sealing ridges 4 of the rotor 5 installed in the stator housing. The segments 2 are fixed in the holder 1 and equipped with sealing ridges 6. Cellular blocks 3 are fixed in segments 2 between the sealing ridges 6 by soldering. The sealing ridges 4 of the rotor form throttling gaps with the inner cylindrical surface of the honeycomb blocks 3. The sealing ridges 6 of the segments form throttling gaps with the outer cylindrical surface of the rotor 5.

The sealing ridges 6 of the segment and the honeycomb blocks 3 are separated by annular channels 7 for the deposition of foreign particles.

At the bottom of the annular channels, internal slurry cavities 8 are made in the form of blind holes for trapping and concentrating foreign particles.

On the outer cylindrical surface of the segments 3, external slurry cavities 9 are made, which are connected by the hole 10 with the annular channels 7.

The hole 10 is made with a diameter, the value of which is greater than the minimum size of the throttling gap between the crest of the cage and the surface of the rotor and less than twice the size of this gap.

In the annular channel 7 at the inlet of the connecting hole 10, a step 11 is made to capture foreign particles.

The sealing ridge 6 of segment 3 is made with a variable height and forms a wedge-shaped gap 12 with the outer surface of the rotor.

The rotor 5 is equipped with sludge-reflecting ridges 13, reflecting foreign particles from the throttling gaps between the sealing ridges of the rotor 4 and the inner cylindrical surface of the honeycomb blocks 3.

Sludge-reflecting ridge 13 is made with a concave surface that directs foreign particles into the annular channels.

The external slurry cavities 9 are made in the form of grooves and are connected by a pipe 14 to a cleaning system 15.

The honeycomb seal of the turbomachine operates as follows.

The flow of the working medium enters the throttling gap between the sealing ridge 6 of the segment and the outer surface of the rotor 5. Large foreign particles 16 are captured by the wide part of the wedge-shaped gap 12 and are pulled by the outer surface of the rotor 5 into the narrow part of the gap. Large foreign particles are crushed in a wedge-shaped gap and lose part of the kinetic energy. Crushed and non-crushed particles enter the vortex chamber between the sealing ridges of the segment and the rotor. As a result of the flow swirl, the foreign particles fall out of the main vortex into the annular channel 7 between the sealing ridges 6 of the segments and the honeycomb blocks 3. In the narrow annular channel 7, the foreign particles lose their axial component of their velocity and settle in the lower part of the channel.

Foreign particles that have passed the first vortex chamber and the throttling gap between the sealing ridges 5 of the rotor and the inner cylindrical surface of the honeycomb blocks 4 are deposited in the annular channels 7 and internal slurry cavities 8 of the subsequent vortex chambers.

The sediment of foreign particles under the action of vibration and mass forces moves from the annular channels 7 and the internal slurry cavities 8 through the holes 10 into the external slurry cavities 9.

The ledge 11 captures the moving foreign particles and also directs them into the connecting hole 10 and the external sludge cavity 9.

The sludge-reflecting ridges 13 direct the foreign particles into the annular channels 7. The concave surface of the sludge-reflecting ridge gives the foreign particles a counter-transverse movement to the flow of the working medium, which reduces the kinetic energy of the foreign particles. Through pipelines 14, the cleaning system 15 removes sludge from the sludge cavities, for example, by flushing, blowing or injecting, without taking the turbomachine out of operation.

The production of honeycomb seals for a turbomachine was implemented in a metalworking plant. The industrial applicability of the honeycomb seal of a turbomachine is confirmed by bench tests.

Claims (9)

1. A honeycomb seal of a turbomachine, comprising a ferrule installed in the stator housing, segments with honeycomb blocks and rotor sealing ridges, segments are fixed in the ferrule and equipped with sealing ridges, honeycomb blocks are fixed in the segments between the sealing ridges by soldering, rotor sealing ridges form throttling gaps from the inner the cylindrical surface of the cell blocks, the sealing ridges of the segments form throttling gaps with the outer cylindrical surface of the rotor, distinguishing It lies in the fact that the sealing ridges of the cage and the cell blocks are separated by annular channels for the deposition of foreign particles. 2. The honeycomb seal of the turbomachine according to claim 1, characterized in that internal slurry cavities are made in the form of blind holes in the bottom of the annular channels for capturing and concentrating foreign particles. 3. The honeycomb seal of the turbomachine according to claim 2, characterized in that external slurry cavities are made on the outer cylindrical surface of the segment and are connected by an opening to the annular channels. 4. The honeycomb seal of the turbomachine according to claim 3, characterized in that the hole connecting the sludge cavity with the annular channels is made with a diameter greater than the minimum throttling gap between the casing flange and the rotor surface and less than twice this gap. 5. The cell seal of the turbomachine according to one of paragraphs. 3, 4, characterized in that in the annular channel at the inlet of the connecting hole is made a ledge to capture foreign particles. 6. The cell seal of the turbomachine according to one of paragraphs. 1-5, characterized in that at least one sealing ridge of the segment is made with a variable height and forms a wedge-shaped gap with the outer surface of the rotor. 7. The cell seal of the turbomachine according to one of paragraphs. 1-6, characterized in that the rotor is equipped with at least one sludge-reflecting ridge, reflecting foreign particles from the throttling gaps between the sealing ridges of the rotor and the inner cylindrical surface of the honeycomb blocks. 8. The honeycomb seal of the turbomachine according to claim 7, characterized in that the sludge-reflecting ridge is made with a concave surface that directs foreign particles into the annular channels. 9. The cell seal of the turbomachine according to one of paragraphs. 3-8, characterized in that the external sludge cavity is connected by a pipe to the cleaning system.

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