Sealed system does hermetic seal for double end panel of series connection type, do hermetic seal to comprise by two groups of odd end panel that set continuously. The pure synthesis that passes filter is enraged give priority to sealed gas to enter one class annular seal space, its pressure compares tall 0.2-0.3MPa of craft gas pressure, rise to cut off action, a few sealed gas can enter a crock inside, but its are enraged for pure synthesis, reason won’t produce pollution.
Another part gas passes two level between dry hermetic seal comb age sealed cent is two, one part regards one class as leak (also weigh leak) direct platoon comes torch system, another part enters 2 class annular seal space to act as 2 class are sealed gas. Age via combing again next sealed enrage eduction one case to be brought to torch system by conduit of 2 class leak and segregation. Segregation is angry (nitrogen) having last sealed effect, its pressure summary prep above 2 class are sealed gas, ensure 2 class are sealed gas won’t leak comes atmosphere side.
Through centrifugal compressor synthesis enrages leak example, the centrifugal compressor that analyses sealed system of equipment dry gas sends case of angry body leak, if do the one class leak of hermetic seal,be enraged and advocate sealed gas is passed in divide face leak to bearing box.
1 introduction
As the rapid development of industry of oil, chemical industry, the development trend that the development direction of feebleminded bad news, cost-effective, 0 pollution, long cycle already made petro-chemical trade. Large the crucial equipment that reducing unit is petrifaction industry, its are sealed the stand or fall of function decides device whether smooth safety moves. Do hermetic seal to practical good, sealed life grows small leak, economy and move to wait for a characteristic to show itself reliably with its. Dry hermetic seal is a kind of new-style runner shaft coming back uses blame contact sealed, it is lubricate in gas on the foundation of bearing, by machinery of contact lilquid film sealed improve and come. Go up century 60 time end, company development goes Yaohankelan to first do hermetic seal and apply at centrifugal compressor. As the rapid development of sealed industry and hydrokinetics, the dry gas that has derived all sorts of type is sealed. Current, dry hermetic seal already was in the industry such as oil, chemical industry, metallurgy, aviation use extensively. Because this is in the article, advocate if be opposite,principle of sealed system of centrifugal compressor dry gas and leak reason undertook comprehensive analysis studies, and also be a few content in later development raised over this foundation, the staff that the hope can give identical industry to have the job provides the reference that gives fair value.
2. Do principle of hermetic seal job
Dry hermetic seal is a kind of new-style blame contact is sealed, its use hydrokinetics principle, the blame contact that will achieve seal face through opening the dynamic pressure slot on seal face moves. By rotating ring, static annulus, sealing ring and bedspring coming back, bedspring comprise with axle sleeve. Rotating ring sealing surface passes processing of abrade, polish, it is above its treatment gives the slot of fluid dynamic pressure that has special effect. When rotating ring of dry hermetic seal rotates, will sealed gas is inspiratory inside dynamic pressure chamfer, flow along sealed lasher. Below the reduce expenditure action of sealed lasher, gas is compressed, pressure is elevatory, push sealing surface, a very thin gas film is formed between two sealing surface. The aerodynamics considers to make clear, when dry hermetic seal the gas film ply of two end panel is when 2-3 micron, aeriform flow layer is most stable, accordingly, dry hermetic seal enrages velar ply to design value make choice of to be in 2-3 micron. The closing force that when gas force of quiet pressure, bedspring forms and gas film are turned over when force is equal, gas film ply keeps constant, dry hermetic seal stabilizes movement.
When exterior existence interference, gas film ply is reduced, and retrorse force increases gas film, right now opening force is more than closing force, below the action of opening force, sealing surface clearance increases, as the addition of sealed clearance, opening force is reduced accordingly, till opening force and closing force are equal when, right now sealed clearance recovers normal cost. Be like sealed gas film suffers exterior interference and ply increases, right now retrorse force reduces gas film, closing force is more than opening force, below the action of closing force, sealed clearance is reduced, as sealed clearance reduce, closing force also is reduced accordingly, till closing force and opening force are equal when, sealing surface restores to come to be worth normally. Accordingly, when wanting to assure to be being installed only, sealed clearance is in a design inside limits, after disappearing when exterior interference, sealed system can restore to stabilize.
3. Sealed invalidation reason
It is invalidation of dry hermetic seal tone takes compressor front to do hermetic seal (shaft coupling side) the moving data of close half an year, can see from data, for example pressure of leak of class of thick front cover of dry gas of some compressor front rises to lift from original 0.15MPa from December 2011 0.2MPa, be as long as 3 months are fluctuant all the time and unusual, the specification does hermetic seal occurrence question.
The 2 sealed gas that are dry hermetic seal of invalidation of balata sealing ring are synthetic gas, craft medium is enraged to circulate (include to synthesize gas, propylene and aldehyde gas) , craft medium is corroded to the existence of balata sealing ring of dry gas sealed system, the likelihood causes sealing ring leak.
3 it is face of the cent in housing if sealed invalidation assigns ageing of face fluid sealant or be no longer in force in compressor housing, craft medium is met face of the cent in passing enters bearing case. Because do hereinto of interface of conduit of leak of class of airtight front cover,separate a side around, appear possibly also in the face is being divided to enter cop of one class leak in synthesizing gas to pass, bring about pressure of leak of class of dry airtight front cover to increase, must want to cause enough attention to its accordingly.
4. Leak circumstance is analysed
The one class leak that is dry hermetic seal enrages joint of face of the cent in passing change enters bearing case inside, the phenomenon is bearing synthesis is contained to enrage inside box, spot circumstance is bearing namely synthetic gas is contained inside box, reason this kind of circumstance is possible.
2 be advocate sealed gas (synthesis is angry) face leak is divided to bearing box in passing, be no longer in force of face fluid sealant is assigned in the specification, the scene overhauls discovery actually, face of the cent in contacting place has fluid sealant skin to fall off, and synthetic gas is contained inside box of the bearing when leak happening, reason this kind of circumstance is possible.
3 it is leak way. Advocate sealed gas (synthesis is enraged) after the one form that adopts dry hermetic seal is sealed, to annular seal space of one class leak inside, one part platoon comes torch, gas of one class leak passes another part to compress face of the cent in housing body big top to be in with connective of annular seal space of one class leak, leak comes bearing box. Another leak way is advocate sealed gas passes one class annular seal space and compressor housing sealed part is distributed in big top, direct leak comes bearing box.
4 it is invalidation reason. Face of the cent in housing is rigid sealing surface, the daub when the overhaul a 704 fluid sealant, in checking, disintegrate check separates a side and wait for blemish without indentation, nick, can decide for fluid sealant invalidation.
Invalidation reason: Above all fluid sealant off quality or keep in storage are undeserved, or it is to exceed period of efficacy to continue to use, mix at the same time with many manufacturer fluid sealant. Next check maintenance quality is not strict, fluid sealant daub is inhomogenous, time of fluid sealant solidify is insufficient (requirement 12 ～ 24h) , the big bolt that build spiral shell tightens force beforehand inhomogenous. Last operation craft is not stable. Manufacturing switch is frequent, craft parameter is adjusted, manufacturing bear change or post operation are undeserved.
5. Handle measure
Change around does hermetic seal two sets; Face face is divided in sanitary housing, mark of eliminate remains rubber, rust, dirt and smeary wait for foreign matter. The akin norms that chooses same manufacturer production 704 fluid sealant, check term of validity. Face of the cent in the edge uses knife of be bored with even daub fluid sealant, daub ply makes an appointment with 1mm. Cent face inside leaves 3mm blank about in, the crock is entered after preventing fluid sealant to squash inside. Answer outfit big top, semmetry of spanner of use moment of force screws bolt comes equably of the regulation tighten force beforehand. Compressor housing is answered outfit end, fluid sealant of face of the cent in awaiting 24h to make subsequently is complete solidify. Oily system is debugged reach after it is normal to move, make doing hermetic seal test, system to fill press each sealed dot has air impermeability test.
6. Experience and lesson
It is to make good equipment prescient maintenance. Be aimed at the service life of dry hermetic seal, had done ahead of schedule monitor, evaluation and overhaul change the job, those who avoid to wait for the Jin after dry gas has a thing again when sealed occurrence breakdown to repair is passive. When the factory plans plant shutdown to overhaul formerly, undertake heavying repair to compressor, if undertake on one year enforcing overhauling to equipment when overhaul, should not produce this leak.
2 it is to pay attention to overhaul quality control. The 704 fluid sealant that according to compressor housing big top uses use a standard, note the norms model of fluid sealant and product performance, strict control uses the index such as time of ply of period of efficacy, actual daub, solidify. Install a requirement according to compressor, spanner of use moment of force according to close solid order semmetry is balanced reach close bolt of the regulation tighten force beforehand, assure to get power even and close solid reachs the designated position.
3 it is perfect set protects a system especially. Perfect refine compressor big unit to protect system and key facility status to monitor a system especially, raise breakdown to analyse judgement and ability of seasonable rush to repair. When the machine before discovery seals leak pressure to have wave motion, did not cause take seriously, check-up is solved to repair again when pulling shutdown overhaul, did not make reasonable, accurate move evaluate a report.
4 although just synthesize gas leak this,be, did not produce craft medium leak, but Ying Ji takes a lesson, think over deeply to manage mechanism and overhaul quality to control strength to big unit, sealed system of comprehensive understanding dry gas may produce all sorts of situations of aeriform leak, the analysis that increases trouble of compressor gas leak effectively is judged and seasonable and accurate solve ability.
7. Conclusion
Anyhow, pass the introduction of principle of job of dry gas sealed system, the reason that goes up to do hermetic seal leak to causing in this foundation undertakes an analysis, found out compressor of rich energy of life to do hermetic seal advocate the main reason that sealed air leakage rate greatens, offer a solution, avoided to cause device because of doing hermetic seal leak to be not a plan to jockey.
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(writer unit: Production factory of Shenyang air-blower group)
