CN101476625A - Circumferential oscillating type gas seal - Google Patents

Abstract

The invention discloses a circumferential swinging air seal, which comprises an air seal seat. The air seal seat is provided with a swinging air seal block which is rotatably connected with the air seal seat. A spring is arranged between the swinging air seal block and the air seal seat, and the swinging air seal block is rotatably connected with the air seal seat through an inserted pin. The spring comprises a first spring and a second spring which are positioned on both sides of the inserted pin respectively. The length of the air seal can be changed according to needs, and the circumferential section plane of the inner wall of a cylinder is provided with a plurality of the air seals. Under a working state, an air seal moveable component takes the inserted pin as a supporting point to circumferentially swing under the action of clearance air flow force so as to reduce the air flow exciting force, and prolong the service life.

Description

Circumferential oscillating type gas seal

Technical field

The present invention relates to a kind of sealing gland pattern that adopts in rotating machinery, relate in particular to a kind of circumferential oscillating type gas seal, this sealing gland can significantly improve the wear resistance and the anti-flow-induced vibration ability of sealing gland in the rotating machinery (as steam turbine, compressor etc.).

Background technique

Generally acknowledge both at home and abroad that at present the circumferential speed when air-flow flows is the key factor that causes flow-induced vibration in the sealing gland chamber.Improving the air seal structure pattern, reducing the air-flow speed of rotating in a circumferential direction is the research thinking that generally adopts both at home and abroad at present.People dredge in tradition on the basis of tooth sealing gland for this reason, have proposed novel sealing gland patterns such as honeycomb, brush, derotation stream, damping, spiral chute, ladder by the structure that changes sealing gland itself, have obtained certain effect.But updating of air seal structure pattern causes structure to become increasingly complex, and is easy to generate because the unstable vibration fault that friction causes.In order to solve the contradiction between sealing gland wear resistance and the leakage rate, the nineties in last century, the U.S. proposes adjustable sealing gland notion, and its main thought is to introduce one gas to flow to the sealing gland back, changes dynamic and static gaps by changing gas pressure.Nineteen ninety, U.S. GE company has researched and developed the malleation sealing gland, manually controls the folding of sealing gland piece by introducing high pressure steam.Nineteen ninety-five, Toshiba Corp has proposed to adopt the adjustable sealing gland of pressure ripple management and control system.In recent years, the somebody proposed various sealing glands gap and adjusted controlling method.Though the sealing gland adjustable gaps of above-mentioned pattern can only be adjusted diametrically, and its radial clearance is determined under certain operating mode, therefore still fixing sealing gland in essence.The appearance of adjustable sealing gland has solved the contradiction between sealing gland wear resistance and the leakage rate, is a difficult point but how significantly to improve the anti-flow-induced vibration ability of sealing gland always.Along with large rotating machineries such as steam turbine, compressor develop to high parameter, big capacity direction, the flow-induced vibration problem is more and more outstanding.

Summary of the invention

The present invention proposes a kind of anti-flow-induced vibration ability that can improve sealing gland also can prolong the sealing gland circumferential oscillating type gas seal in working life.

The technical solution adopted for the present invention to solve the technical problems is:

A kind of circumferential oscillating type gas seal, comprise: the sealing gland seat, be provided with swing sealing gland piece and swing sealing gland piece and sealing gland seat at the sealing gland seat and be rotationally connected by latch, swing sealing gland piece can be that fulcrum is circumferentially swung with the latch, is provided with spring between swing sealing gland piece and sealing gland seat.

The sealing gland piece is designed to around fulcrum along circumferentially swing, from the equalising torque of the suffered power of sealing gland piece around its fulcrum, the air-flow power that acts on the sealing gland necessarily means to sealing gland piece fulcrum (frictional force very I is ignored), so air-flow power always arrives the directive effect of sealing gland piece fulcrum along the axle center.Because the sealing gland piece is designed to swing with the displacement campaign of axle journal at any time, therefore can reduce the tangential excitation force that fluid flows and produced in sealing gland again, thereby improve the stability of rotary machine rotor.Concrete principle analysis is as follows:

As shown in Figure 1, the thickness h between axle journal and the sealing gland piece distributes, and depends on axle center O fully _jRelatively with the position of sealing gland piece fulcrum, and this relative position available radial off-centre e _RaWith tangential eccentric e _TaBe expressed as follows:

$e_a=\sqrt{e_{\mathrm{ra}}^2+e_{\mathrm{ta}}^2}$

Angle γ _aFor:

${\mathrm{\γ}}_a=\mathrm{arctg}\left(\frac{e_{\mathrm{ta}}}{e_{\mathrm{ra}}}\right)$

The h representation is:

h＝c+e _acosφ _a

C is the poor of sealing gland piece arc radius and axle journal radius in the formula.

Sealing gland piece initial angle is:

φ _a1＝π-β ₁-γ _a

Sealing gland termination of a block angle is:

φ _a2＝π-β ₁+β ₂-γ _a

β in the formula ₂Be sealing gland piece subtended angle; β ₁Be the subtended angle of sealing gland piece limit to an angle.

Like this, the gas film pressure on the sealing gland piece distributes and can obtain: p=p (φ _a, z; e _Ra, e _Ta), wherein z is a sealing gland piece axial coordinate.It is suffered with joint efforts that integration can get the sealing gland piece:

$F_{\mathrm{ta}}={\∫}_{-\frac{l}{2}}^{\frac{l}{2}}{\∫}_{{\mathrm{\φ}}_{a1}}^{{\mathrm{\φ}}_{a2}}p\sin ({\mathrm{\φ}}_a+{\mathrm{\γ}}_a)\mathrm{rd}{\mathrm{\φ}}_a\mathrm{dz}=F_{\mathrm{ta}}(e_{\mathrm{ra}},e_{\mathrm{ta}})$

$F_{\mathrm{ra}}={\&Integral;}_{-\frac{l}{2}}^{\frac{l}{2}}{\&Integral;}_{{\mathrm{\&phi;}}_{\mathrm{<figure-callout\; id="1"\; label="a"\; filenames="A200910028145E00081.png,A200910028145E00091.png"\; state="\{\{state\}\}">a</figure-callout>}1}}^{{\mathrm{\&phi;}}_{a2}}p\cos ({\mathrm{\&phi;}}_a+{\mathrm{\&gamma;}}_a)\mathrm{rd}{\mathrm{\&phi;}}_a\mathrm{dz}=F_{\mathrm{ta}}(e_{\mathrm{ra}},e_{\mathrm{ta}})$

Air-flow power moment about point of support is F _Tar _a(r _aBe sealing gland piece arc radius).This moment will make the sealing gland piece around a spot wobble if be not 0, and h distributes and p distributes thereby change, and air-flow power also changes thereupon, up to F _Tar _a=0 just reaches the balance orientation of sealing gland piece.Have only when air-flow power during just by fulcrum the sealing gland piece just reach balance.That is:

F _ta(e _ra，e _ta)＝O

Therefore the tangential excitation force that air-flow is produced in the sealing gland can significantly reduce, thereby reaches the purpose that improves rotor stability.

It is not only simple in structure that sealing gland is designed to circumferential mobilization, and because the swing of sealing gland piece can make rotating shaft and sealing gland piece keeping parallelism state in margin of error necessarily, thereby can reduce the frictional vibration fault that factor produced such as off-centring effectively.Can prolong sealing gland working life

Compared with prior art, the beneficial effect of the circumferential movable sealing gland of the present invention's proposition is as follows:

(1) owing to the air-flow power on the sealing gland necessarily means to sealing gland piece back fulcrum, thereby reduces the tangential excitation force that fluid flows and produced effectively in sealing gland, improve the anti-flow-induced vibration ability of sealing gland greatly.

(2) the sealing gland piece can be swung flexibly around fulcrum, rotor and sealing gland can be in certain margin of error keeping parallelism, reduced friction, the loss of sound parts, prolonged the shelf life of sealing gland;

(3) any fixed sealing gland that adopts at present can be changed into corresponding circumferential oscillating type gas seal in view of the above;

Description of drawings

Fig. 1 is a schematic diagram of the present invention.

Fig. 2 is circumferential movable high stable air seal structure and scheme of installation.

Fig. 3 is the circumferential partial sectional view of circumferential movable high stable sealing gland.

Fig. 4 is the axial A-A sectional view of circumferential movable high stable sealing gland.

Among the figure, the 1st, rotor, the 2nd, cylinder, 3 is first springs, 4 is second springs, the 5th, the sealing gland seat, the 6th, can swing the sealing gland piece, the 7th, latch.

Embodiment

A kind of circumferential oscillating type gas seal comprises: sealing gland seat 5, and be provided with swing sealing gland piece 6 and swing sealing gland piece 6 and sealing gland seat 5 at sealing gland seat 5 and be rotationally connected, between swing sealing gland piece 6 and sealing gland seat 5, be provided with spring, in the present embodiment:

Swing sealing gland piece 6 is rotationally connected by latch 7 with sealing gland seat 5;

Described spring comprises that first spring 3 and second spring 4 and first spring 3 and second spring 4 lay respectively at the both sides of latch 7, as shown in Figure 3.Latch 7 is the circumferential swing fulcrum of swing sealing gland piece 6, and first spring 3 and second spring 4 provide certain elastic support for swing sealing gland piece 6.Dotted line is depicted as swing sealing gland piece 6 along the state of circumferentially swinging among the figure.

In Fig. 2,6 circumferential oscillating type gas seals have been installed along cylinder wall 2 circumferential sections.Sealing gland adopts the dovetail groove mounting type to be fixed on cylinder 2 inwalls.

Figure 4 shows that the axial sectional view of single circumferential oscillating type gas seal.Wherein the swing sealing gland piece among the figure 6 is for dredging the tooth sealing, and sealing gland seat 5 is the grooved member, and swing sealing gland piece 6 embeds in sealing gland seat 5 grooves by latch 7.

When rotor 1 rotated, under the effect of air-flow power, swing sealing gland piece 6 can be around 7 spot wobbles of latch, thereby reduced the tangential excitation force of air-flow adaptively.

Claims (3)

1. circumferential oscillating type gas seal comprises: sealing gland seat (5), it is characterized in that, and be provided with swing sealing gland piece (6) and swing sealing gland piece (6) is rotationally connected with sealing gland seat (5) at sealing gland seat (5), be provided with spring at swing sealing gland piece (6) with sealing gland seat (5).

2. circumferential oscillating type gas seal according to claim 1 is characterized in that, swing sealing gland piece (6) is rotationally connected by latch (7) with sealing gland seat (5).

3. circumferential oscillating type gas seal according to claim 2 is characterized in that, spring comprises that first spring (3) and second spring (4) and first spring (3) and second spring (4) lay respectively at the both sides of latch (7).

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